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Pipeline politics has been on the uptick in recent years. From sit-ins outside the White House to canoe flotillas, days of actions, legal challenges, rallies, numerous reports, blockade, town halls, letters and petitions.
Last night the Thunder Bay city council agreed to put a resolution opposing TransCanada's 1.1 million barrel per day Energy East pipeline project on hold.
In no small irony, the motion to defer was brought forward by Iain Angus, Vice President of NOMA (Northwestern Ontario Municipal Association) who has openly endorsed the project, including appearing on TransCanada's webpage. The resolution will again be considered by council two months after the National Energy Board declares TransCanada's project application complete.
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\section{Future R\&D Needs} \label{sec:randd}

While much of the DUNE ND-GAr baseline design is based on the ALICE TPC and CALICE calorimeter designs, there are several important differences and requirements.  The major areas of R\&D needed for ND-GAr are outlined below.

\begin{enumerate}

\item \textbf{Gas mixture studies}

The ALICE TPC baseline gas mixture is Ne/CO$_2$/N$_2$ at near atmospheric pressure. Neon offers a higher response to ionization than argon (higher avalanche gain) while the combination of a high ion mobility (stemming from the fact that neon is a light gas) and small ageing effects (through the use of CO$_2$ as the quenching gas) are crucial choices at the reaction rates typical of LHC operation. When aiming at high gain operation of argon gas in a low-rate environment, however, an Ar/hydrocarbon-based mixture is \emph{a priori} preferred, as was done in PEP-4 (Ar/CH$_4$, 80/20). For ND-GAr, establishing the optimum quencher concentration will require a balance between the present safety limits of the mixture (e.g. 8\% for CH$_4$), minimizing the number of non-Ar interactions, maintaining good drift-diffusion characteristics, and allowing sufficient charge gain~\cite{Hamacher-Baumann:2020ogq}. A promising R\&D line is the addition of wavelength-shifting species in the gas phase, which would allow time-tagging of that fraction of events for which the charged-particle content is not energetic enough to be time-tagged in the calorimeter.

\item \textbf{Light Collection}

Primary light production in pure argon in the vacuum ultraviolet (wavelengths $<$200 nm) is well understood~\cite{Gonzalez-Diaz:2017gxo}. In pure argon at a pressure of 10~atm, we estimate that a minimum ionizing particle will produce approximately 400 photons/cm~\cite{Chandrasekharan:2005edc}, but in typical gas TPC operation, a quenching gas or gases are added that either quench or absorb most of the VUV emission.   Recent studies have indicated that with the addition of Xe~\cite{Gonzalez-Diaz:lidine2021}
or CF$_4$~\cite{Gonzalez-Diaz:APS2021} (among possibly other wavelength-shifting species), it is possible to quench the hard VUV component of argon (thus improving avalanche gain) while producing light in the visible or near-IR bands. In Ref.~\cite{Gonzalez-Diaz:APS2021} in particular, the possibility of producing up to 700 photons/MeV in Ar/CF$_4$ mixtures at 1\% molar fraction is shown. With suitable instrumentation (e.g., a SiPM plane at the cathode and a teflon reflector in the field cage) about 350~photoelectrons/5MeV track are anticipated. Utilizing this light would be a novel development for a gaseous argon TPC.
However, R$\&$D is needed in order to understand the impact of impurities on the yields, maximum avalanche gain achievable in different charge amplification structures, mitigation of secondary scintillation backgrounds, and finally the design of a photon detection system. In close coordination with groups investigating the gas mixture, field cage, HV, and DAQ, a conceptual design will be developed for the collection and readout of light in the gas volume, once a suitable gas mixture is identified.

\item \textbf{Readout Chambers}

Figure~\ref{fig:HPgTPC_ROC} indicates the locations of Inner Readout Chambers (IROCs) and Outer Readout Chambers (OROCs) in ALICE. These chambers have been removed from ALICE as part of the upgrade for LHC Run 3, and can be used for DUNE.   At a minimum, even in the baseline scenario, new  readout chambers will need to be designed to cover the central area of the endcaps, which was not part of the TPC in ALICE.

However, it is possible to consider a totally new design for the full circular readout plane. This could employ a different technology, such as GEM or MicroMegas charge readout.  Such charge amplification structures allow staging, thereby being more flexible in principle at achieving high and stable gains. In the case of using a scintillating mixture like Ar/CF$_4$ for reconstructing the primary scintillation (t$_0$) signal, readouts based on Gas Electron Multipliers (GEMs) can be optimized for screening of the secondary scintillation signal into the photosensor plane.

Alternatively, and given the present technological landscape, it seems timely to consider a fully-optical readout, as a scintillating gas mixture is already under investigation for the $t_0$ light collection system. For this readout concept, a camera is mounted on the outside of the active gas volume and images, through a transparent anode, the scintillation light produced during the gas amplification of tracks. This produces 2D images of the interactions inside of the TPC. Optical readout could offer an unprecedented pixel size in the readout plane equivalent to $\leq1\times$~mm$^2$ over an area as large as $1$~m$^2$, where all pixels are read out by one integrated device, the camera. It would also offer the attractive feature of passing signals from millions of readout channels through the pressure vessel wall at just the cost of a window. The third coordinate perpendicular to the anode plane can be reconstructed by using fast cameras or tailored ones such as the TimePix3 camera, which have already demonstrated effective pixel sizes down to $3\times3$ mm$^2$~\cite{Fisher_Levine_2016, Roberts_2019}.

ALICE also had a central cathode with two-drift regions for the electrons, with the readout chambers placed on both ends of the detector. The main advantages of this design are the simplicity of HV insulation, about a factor two reduction in purity requirements and collection times, a reduction of space-charge effects, and a factor $\sqrt{2}$ reduction in ionization spread. Alternatively, DUNE could consider a single-drift region, with the readout on one side, which would reduce the number of electronics channels needed, and would provide a space for a light-collection system near the cathode. The optimization of the chamber readout must be developed in close connection with performance figures such as tracking and energy threshold, $dE/dx$, energy and momentum resolution, and physics impact of a t$_0$ signal.

\begin{figure}[htb]
\centerline{ \includegraphics[width=0.5\textwidth]{figures/ROCs.png}}
\caption{Diagram of a possible arrangement of readout chambers of the ND-GAr HPgTPC, based on a drawing of Ref.~\cite{Alme:2010ke}. The Central Readout Chambers would need to be designed and added to the HPgTPC.}
\label{fig:HPgTPC_ROC}
\end{figure}

\item \textbf{Electronics and DAQ development}

The electronic readout of the detector is under development with an aim to maximize synergies with existing electronics. The system's design is driven by the high magnetic field and pressure that the electronics must be situated in. The primary limitation of the pressure is that data and power cables must pass through the pressure vessel, so some in-vessel aggregation is necessary to limit the total number of penetrations. The planned system is comprised of front end cards (FECs) hosting digitizer ASICs; these FECs are read out by a smaller number of in-vessel aggregation cards (AGGs), which then send data to out-of-vessel timing, interface and power cards (TIPs). We aim to digitize the signal to the level of tens of MHz, and this is driven by z-axis resolution.
For the FEC, two approaches are under investigation. The first uses similar electronics to the liquid argon near detector, based on the LArPix ASIC~\cite{dwyerLArPixDemonstrationLowpower2018a} chip. This chip would achieve very low cost per channel, but some modifications are needed to adapt it for use in the HPgTPC, since the HPgTPC signal is faster and inverted compared to the liquid argon near detector (multi-wire-proportional-chamber-based gaseous argon readout chambers mainly detect induced charge from ions moving in relation to the pickup electrodes, rather than electrons moving to collection plane wires), and the gain in the gas results in a widened dynamic range. The other approach is based on the SAMPA ASIC~\cite{Barboza:2016ala} in use by ALICE. This system has a higher cost per channel but does not require modification. The AGGs and TIPs are being designed to both use the same PCB design to minimize costs, and will both be based around the same Xilinx Kintex FPGA. Both power and data will be passed down the same cables, with the current plan to use standard ethernet cables and RJ45 feedthroughs.

Readout electronics will also need to be developed for a light collection system.

\item \textbf{Field Cage and High Voltage}

A new field cage and mechanical endcap structures will need to be constructed for the ND-GAr HPgTPC. Since the ND-GAr detector will be movable, a robust mechanical design for the field cage will be needed. A buffer region with an insulating gas is planned for the region in between the field cage and pressure vessel.  As the HPgTPC will be operated at higher pressure and cathode potential, the insulating gas and vessel-field cage spacing requires optimization~\cite{Norman:2021fdy}.  Differential-pressure regulation between the different gas volumes will be needed.

\item \textbf{Calibration}

To precisely monitor any variations of the drift velocity and inhomogeneities in the drift field,  a laser calibration system  that can illuminate the entire drift volume is desirable.  Its design will need to be developed in close collaboration with the high voltage field cage design, and R\&D will need to be performed to ensure that an adequate signal amplitude can be obtained in the high-pressure gas mix.

\item \textbf{Calorimeter}

The calorimeter must fulfill several roles, ranging from photon energy and direction measurements to muon/pion separation and neutron detection, which impose different constraints on the capabilities of the system. While the general technology of plastic scintillator tiles and strips read out with silicon photomultipliers is already well-established, most notably in the framework of CALICE\cite{CALICE:2010fpb}, several areas of R\&D specific to ND-GAr remain. On the system level, this includes the design and optimization of the absorber geometry, readout granularity and of the overall mechanical structure. Specific front-end electronics that are suitable for the high envisioned channel count, provide a time resolution on the few 100 picosecond level, and possibly the capability for pulse-shape discrimination while meeting the low-power requirements, will need to be developed. In the area of scintillators, strip concepts that provide a sufficient time resolution for the measurement of neutron energies via time of flight, are needed. Specific scintillator materials that enhance the neutron detection capability, and their matching to silicon-based photon sensors, will need to be studied.

\item \textbf{Muon system}

The ND-GAr muon system is in a very preliminary stage of design, and it crucially depends on the particulars of both the calorimeter and magnet systems.  The current design consists of a single layer outside the iron.  The iron itself is not segmented in depth to allow for multiple measurements.  Current technologies under consideration include scintillator extrusions, resistive plate chambers, or MicroMegas.

\end{enumerate}

\section*{Acknowledgements} \label{sec:acknowledgements}

This document was prepared by the DUNE collaboration using the
resources of the Fermi National Accelerator Laboratory
(Fermilab), a U.S. Department of Energy, Office of Science,
HEP User Facility. Fermilab is managed by Fermi Research Alliance,
LLC (FRA), acting under Contract No. DE-AC02-07CH11359.
This work was supported by
CNPq,
FAPERJ,
FAPEG and
FAPESP,                         Brazil;
CFI,
IPP and
NSERC,                          Canada;
CERN;
M\v{S}MT,                       Czech Republic;
ERDF,
H2020-EU and
MSCA,                           European Union;
CNRS/IN2P3 and
CEA,                            France;
INFN,                           Italy;
FCT,                            Portugal;
NRF,                            South Korea;
CAM,
Fundaci\'{o}n ``La Caixa'',
Junta de Andaluc\'ia-FEDER,
MICINN, and
Xunta de Galicia,               Spain;
SERI and
SNSF,                           Switzerland;
T\"UB\.ITAK,                    Turkey;
The Royal Society and
UKRI/STFC,                      United Kingdom;
DOE and
NSF,                            United States of America.

\section{Summary} \label{sec:conclusion}

The complete ND-GAr detector is required in order for DUNE to reach its full physics potential.  A magnetized tracker will allow for excellent momentum resolution and sign-selection for the long-baseline oscillation physics.  Its wide acceptance and low tracking threshold for neutrino interactions on argon will provide crucial contributions to the oscillation physics.
ND-GAr will also provide a rich physics program of cross-section measurements and will extend the capabilities of the DUNE ND for physics beyond the standard model.  While the current design benefits from work done on the ALICE TPC and by the CALICE calorimeter collaboration, it is desirable both to adapt it to the DUNE ND environment, and to explore new technological developments that offer a window of opportunity. A focused R\&D program will need to be implemented, aimed at completion of the detector baseline as well as exploration of these timely new technologies and extended physics reach.

\section{ND-GAr Detector Overview} \label{sec:det}

The ND-GAr concept is based on a central high-pressure gaseous argon TPC; the HPgTPC is surrounded by a calorimeter, with both situated in a 0.5~T magnetic field generated by superconducting coils. A muon system is integrated with the magnet return yoke.   A cutaway view of the full ND-GAr system is shown in Fig.~\ref{fig:ndgarlayout}.

\begin{figure}[ht]
\centering
\includegraphics[width=0.5\textwidth]{figures/NDGAr_concept_annotated.png}
\caption[ND-GAr Schematic]{Cutaway view of the full ND-GAr detector system showing the HPgTPC, the calorimeter, the magnet, and the iron yoke.  The detectors for the muon-tagging system are not shown.}
\label{fig:ndgarlayout}
\end{figure}

The baseline concept of the ND-GAr HPgTPC is based closely on the design of the ALICE TPC~\cite{ALICE:2000jwd}. However, an opportunity exists to reconsider this design
This paper focuses on the baseline design in order to present physics motivations and performance. Future R\&D lines aimed at optimizing this design will be discussed later in the document.

\subsection{High-Pressure Gaseous Argon Time Projection Chamber and Calorimeter}

At the heart of the ND-GAr detector, the HPgTPC contains an argon-based gas mixture held at a pressure of approximately 10~atm to increase the rate of neutrino interactions.  The drift region of the HPgTPC has a diameter of roughly 5~m and a length of roughly 5~m, corresponding to a fiducial mass of nearly 1~ton of argon. With this fiducial mass, a one-year exposure (defined as $1.1 \times 10^{21}$ protons on target) would result in approximately 1 million neutrino interactions on argon in the on-axis position.

The calorimeter is inspired by the CALICE analog hadron calorimeter (AHCAL)~\cite{CALICE:2010fpb}. The scintillating layers will consist of a mix of tiles and strips.
More details of the HPgTPC and calorimeter for the ND-GAr are described in Ref.~\cite{DUNE:2021tad}.

\subsection{Magnet and Pressure Vessel}

The design of the magnet system has evolved over the past few years and no longer uses a separate pressure vessel as was described in Ref.~\cite{DUNE:2021tad}.   The superconducting magnet uses a semi-continuous thin solenoid approach with 6 separate windings.  The design is based on the decades-long evolution of internally wound, aluminum stabilized superconducting magnets.  The required field in the warm bore is relatively low, 0.5T, therefore a single-layer coil is sufficient to provide the needed current density even with a diameter of $\simeq 7$~m.  The design parameters are conservative when compared to previously built magnets.  The iron yoke must be asymmetric to reduce the material budget between ND-LAr and ND-GAr. The magnet system design, a solenoid with a partial return yoke (SPY), makes its design rather unique.

A key feature of SPY is that the pressure containment for the 10~bar of argon gas for the HPgTPC is now provided by the solenoid's vacuum vessel and ``stayed'' flat heads are supported by the magnet system yoke.  Figure~\ref{fig:pv} shows the exterior of the complete detector system.  The iron return yoke for the magnet wraps around the sides, top, and bottom of the magnet and has a window on its upstream beam face to minimize the amount of material between the ND-LAr and ND-GAr tracking regions, as shown in Figure~\ref{fig:pv}. The end flanges of the pressure vessel are ``stayed'' by the iron yoke end plates.

Many of the features of the solenoid are based on the design of the solenoid for the MPD for the Nuclotron-based Ion Collider FAcility (NICA) at JINR~\cite{Abraamyan:2011zz}.

\begin{figure}
    \centering
    \includegraphics[width=0.55\textwidth]{figures/pv.png}
    \includegraphics[width=0.35\textwidth]{figures/stayedhead.png}
    \caption{The left image shows the full system, with the magnet return yoke shown in red. The right image shows a cutaway view of one of the end plates, where some of the ``stays'' that support the load of the flat heads are visible.}
    \label{fig:pv}
\end{figure}

\subsection{Muon Tagger}
ND-GAr will need an active layer, the Muon Tagger, outside the iron yoke that will detect particles that penetrate the iron.  These data will be used in conjunction with the calorimeter and HPgTPC to provide $\mu/\pi$ separation. The current design consists of a single active layer outside the iron.  The iron itself is not segmented in depth to allow for multiple measurements. Current technologies under consideration include scintillator extrusions, Resistive Plate Chambers (RPCs), or MicroMegas.

\section*{Executive Summary}
\label{sec:summary}

This document presents the concept and physics case for a magnetized gaseous argon-based detector system (ND-GAr) for the Deep Underground Neutrino Experiment (DUNE) Near Detector.  This detector system is required in order for DUNE to reach its full physics potential in the measurement of CP violation and in delivering precision measurements of oscillation parameters.

The ND-GAr concept is based on a central high-pressure gaseous argon time projection chamber (HPgTPC); the HPgTPC is surrounded by a calorimeter, with both situated in a 0.5~T magnetic field generated by superconducting coils. A muon system is integrated with the magnet return yoke. The baseline concept of the HPgTPC at the heart of ND-GAr is based closely on the design of the ALICE TPC~\cite{Alme:2010ke}. An opportunity exists to reconsider this design, given the
timeline to construct the full DUNE. This paper focuses on the baseline design in order to present physics motivations and performance. Future R\&D lines aimed at optimizing this design are discussed as well.

The DUNE CP violation measurement requires complementary detectors at the near site: an upstream modular non-magnetized liquid argon TPC (ND-LAr), a magnetized tracker containing a pressurized gaseous argon TPC (ND-GAr), and a large magnetized beam monitor (SAND). In the early years of DUNE running, a smaller and simpler detector than ND-GAr can be placed downstream of ND-LAr to measure the momentum and charge sign of forward-going muons exiting ND-LAr. However, after approximately 200 kt-MW-yrs of exposure, the full ND-GAr detector is critical for DUNE to reach 5$\sigma$ sensitivity to CP violation over most of the possible values of $\delta_{CP}$, the Standard Model parameter that controls CP violation in neutrinos.

In addition to its critical role in the long-baseline oscillation program, ND-GAr will extend the overall physics program of DUNE. This detector will collect a significant number of neutrino interactions ($\sim$1.6 M/yr) on its one-ton gaseous argon target, enabling a variety of neutrino interaction cross section measurements capable of detecting the resulting charged particles with lower energies than achievable in the far or near liquid argon TPCs, and with enhanced particle identification performance relative to the LArTPCs. These capabilities enable better constraints of systematic uncertainties for both oscillation and cross section analyses.  Another unique advantage of ND-GAr is its flexibility to use various gas mixtures as interaction targets, such as potentially using a hydrogen-rich gas mixture to probe more fundamental neutrino-hydrogen interactions, which can also better constrain understanding of neutrino-argon interactions.

The LBNF high-intensity proton beam will provide a large flux of neutrinos that is sampled by ND-GAr, enabling DUNE to discover new particles and search for new interactions and symmetries beyond those predicted in the Standard Model. In particular, ND-GAr can search for neutrino tridents, heavy neutral leptons, light dark matter, heavy axions, and anomalous tau neutrinos from short-baseline mixing with sterile neutrinos.

The baseline design of ND-GAr takes advantage of much work done on the ALICE TPC and by the CALICE calorimeter collaboration, but it is necessary to adapt these to the DUNE near detector environment.  A focused R\&D program is presented, aimed at optimization of the detector design along with exploration of timely new technological developments that offer a window of opportunity for extending the capabilities of DUNE.
\section{Introduction}
\label{sec:intro}
The Deep Underground Neutrino Experiment (DUNE) is a next-generation international particle physics experiment seeking to answer fundamental questions about the neutrino.
It will use a new high-intensity neutrino beam that will be generated at the U.S. Department of Energy's Fermi National Accelerator Laboratory (Fermilab).
The experiment will consist of a far detector (FD) located approximately 1.5~km underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, at a distance of 1285~km from Fermilab, and a near detector (ND) that will be located on the Fermilab site in Illinois.  The FD will consist of a large, modular liquid-argon time projection chamber (LArTPC) with a fiducial mass of roughly 40~kt (total mass of 68 kton).

The reference ND will be located approximately 574~m from DUNE's
neutrino target, which is the starting point for the Long-Baseline Neutrino Facility (LBNF) beam. The conceptual design for the DUNE ND is described in detail in Ref.~\cite{DUNE:2021tad}.
The reference ND design consists of several different components shown in Fig.~\ref{fig:ndlayout}: an upstream modular non-magnetized LArTPC (ND-LAr), a magnetized tracker containing a pressurized gaseous-argon time projection chamber (ND-GAr), and a large, magnetized tracking spectrometer (SAND).  SAND will remain fixed on the beam axis, while ND-LAr and ND-GAr will move transverse to the beam to collect data at various off-axis positions, providing different neutrino energy spectra by the PRISM concept~\cite{bhadra2014letter}.  In a conventional neutrino beam, the peak energy of the neutrino spectrum decreases and the size of the high energy tail is reduced when the detection angle relative to the beam axis is increased.  For this reason the DUNE-PRISM measurement program consists of moving ND-LAr and ND-GAr laterally, transverse to the beam's direction through the underground ND hall, over an off-axis angle range of 0$^\circ$ to 3.2$^\circ$  (a distance of $\sim$31~m).  These measurements will allow for a data-driven determination of the relationship between true and reconstructed energy and will provide data samples that can be combined to produce a flux at the ND that is very similar to the expected oscillated flux at the FD.

While ND-GAr has a long history in DUNE and is part of the reference design,
the near detector complex has been organized into a phased program, in which Phase~I contains a minimal tracking detector downstream of ND-LAr, and Phase~II includes the upgrade to ND-GAr that is necessary to achieve the DUNE physics goals. This white paper presents the arguments for why ND-GAr is needed in the long term and also includes the R\&D program needed to get there.

\begin{figure}[ht]
\centering
\includegraphics[width=0.95\textwidth]{figures/NDHall_Feb22.JPG}
\caption[DUNE ND Hall]{Profile view of the DUNE ND hall and the reference DUNE ND detectors foreseen to operate in Phase~II.  The neutrino beam enters from the right.}
\label{fig:ndlayout}
\end{figure}

\subsection*{Detector Concept}

In order to constrain neutrino interaction model uncertainties, it is essential that the near detector contain an active argon medium to measure neutrino interactions on the same target nucleus as the far detector.  The non-magnetized ND-LAr can measure neutrino interactions on argon with a similar detection principle as the far detector, but only muons below 1~GeV/$c$ will be fully contained in the detector. The FD has better acceptance due to its larger size, so the ND needs access to uncontained muons to match the types of events that will be seen in the FD.  Thus an additional magnetized detector is required in addition to ND-LAr to measure the momentum and charge-sign of the exiting muons.

\begin{figure}[ht]
\centering
\includegraphics[width=\textwidth]{figures/nd-gar-evd-sevenprotons-annotated-crop.pdf}
\caption[GArSoft simulated and reconstructed event with low energy protons]{A charged current $\nu_\mu$ event with seven low energy protons (kinetic energies ranging from 7 to 51~MeV) in a 10~atm argon-based TPC, simulated and reconstructed with the GArSoft software suite. The detector has a radius of approximately 2.5 m and a width of 5 m.   Charged particle trajectories for both simulated (thin lines) and reconstructed (thick lines) tracks are shown. The $\mu^{-}$ (green reconstructed track) enters the ECAL, while the protons are contained within the TPC. The reconstruction algorithm finds all eight tracks, although only six are visible by eye in this view.
}
\label{fig:garsoft-evd-manyp}
\end{figure}

\begin{figure}[ht]
\centering
\includegraphics[width=0.75\textwidth]{figures/nd-gar-evd-annotated-p-KE-crop.pdf}
\caption[GArSoft simulated and reconstructed event]{A charged current $\nu_\mu$ event with two pions in a 10~atm argon-based TPC, simulated and reconstructed with the GArSoft software suite. The detector has a radius of approximately 2.5 m and a width of 5 m.   The annotations are from Monte Carlo truth. Charged particle trajectories for both simulated (thin lines) and reconstructed (thick lines) tracks are shown, as well as reconstructed clusters in the ECAL (shown as green polyhedra). The $\pi^{+}$ decays in flight, and the resulting muon enters the ECAL. Also seen in the ECAL are reconstructed clusters from the decay of a final state $\pi^{0}$ created in the neutrino interaction (the two $\gamma$'s from the $\pi^{0}$ decay do not produce ionization tracks in the TPC, and so are only detected by the ECAL), and a cluster from the outgoing $\mu^{-}$ in the interaction.
}
\label{fig:garsoft-evd}
\end{figure}

\begin{figure}[ht]
\centering
\includegraphics[width=0.5\textwidth]{figures/PEP4-TPC-80Ar-20CH4-8_5atm_dEdx.png}
\caption[PEP-4 TPC dE/dx]{$dE/dx$-based particle identification in the TPC of the PEP-4 detector at SLAC~\cite{Grupen:1999by}.  This TPC used a gas mixture of 80:20 Ar-CH$_4$, operated at 8.5~atm~\cite{TPCTwoGamma:1982efn}.}
\label{fig:pep4-dedx}
\end{figure}

A gaseous argon-based time projection chamber (gaseous-argon TPC, or GArTPC) can reconstruct pions and protons with lower detection thresholds than a liquid-argon TPC (LArTPC). For comparison, a proton must have a kinetic energy of 46~MeV in order to make a 2-cm track in liquid argon, but only it only needs 4~MeV to make the same length track in 10~atm of gaseous argon. Proton tracks have been successfully reconstructed in the MicroBooNE LArTPC down to kinetic energies of approximately 46~MeV (momentum of 300~MeV/$c$)~\cite{MicroBooNE:2020akw}. The GArTPC is also less susceptible to confusion of primary and secondary interactions, since secondary interactions occur infrequently in the lower density gas detector ($\lambda \sim$90~m). If the TPC is inside a magnet, it can better distinguish neutrinos and anti-neutrinos and can determine the momenta of particles that range out of the detector. It can also measure neutrino interactions over all directions, unlike the ND-LAr, which loses acceptance at high angles with respect to the beam direction. Therefore, a gaseous-argon TPC provides a valuable and complementary sample of argon interactions to better understand neutrino-argon interactions.  An example of a simulated and track-reconstructed neutrino event in a gaseous-argon TPC is shown in Fig.~\ref{fig:garsoft-evd}. To ensure adequate statistics of more than 1 million events per year in a reasonably sized detector, this gaseous-argon TPC will need to operate at approximately 10~atm.  Using a gaseous TPC as the primary tracking element in the spectrometer allows for excellent particle momentum resolution and particle identification (PID). An example of the $dE/dx$-based PID capabilities achieved in the high-pressure TPC in the PEP-4 detector facility~\cite{TPCTwoGamma:1982efn} at SLAC is shown in Fig.~\ref{fig:pep4-dedx}. ND-GAr, at a similar or slightly higher pressure and larger sampling volume, is expected to achieve similar or better identification capabilities.

To detect neutrons and photons (mainly from neutral pions), the TPC must be surrounded by a calorimeter, though this might be thinner on the upstream side to keep acceptance high for tracks entering from ND-LAr.  A muon system outside the magnet is needed to help separate muons and charged pions.  Putting all of these general requirements together leads to the complete ND-GAr concept, with a central high-pressure gaseous-argon TPC (HPgTPC) surrounded by a calorimeter (ECAL) and a ~0.5 T magnetic field, and a muon tagger system.  More details of the current detector concept can be found in Section~\ref{sec:det}.

\section{Physics Motivation}
\label{sec:physicsmotivation}

The full physics program of DUNE is described in Refs.~\cite{DUNE:2015lol, Abi:2018dnh, DUNE:2020ypp}. The near detector for DUNE Phase I is planned to consist of ND-LAr, a Temporary Muon Spectrometer (TMS), which measures the charge and momentum of muons that exit ND-LAr but is not designed to perform additional precision physics measurements, and SAND. This configuration is shown to be sufficient for the early DUNE physics milestones, including determination of the neutrino mass ordering and sensitivity to maximal CP violation. To reach the precision physics goals, including sensitivity to CP violation over a broad range of values of $\delta_{CP}$, systematic uncertainties must be constrained to a level well beyond what is achieved by current experiments, and this requires a more capable near detector.  Even if CP violation is found to be large and near maximal, precise measurements will require ND-GAr.

 In addition to measuring the momentum and sign of charged particles exiting ND-LAr,  ND-GAr provides a magnetized gaseous argon target within ND-GAr, which will extend charged-particle measurement capabilities.

 It will also greatly extend the particle ID (PID) performance, particularly for proton-pion separation. These capabilities enable precision measurements of neutrino interaction cross sections to further constrain systematic uncertainties for the long-baseline oscillation analysis. Since the target nucleus in ND-GAr is the same as in the near and far LArTPCs, this information helps constrain interaction models by minimizing contributions from nuclear physics effects. The ND-GAr detector, with its full solid-angle acceptance, will be used to measure ratios of inclusive, semi-exclusive, and exclusive cross sections as functions of neutrino energy, where the flux cancels in the ratio.

 Cross sections for different particle species multiplicities (pions, protons, kaons, etc.) will help constrain interaction models used in the near and far liquid argon detectors. ND-GAr will also replace the TMS in its capacity as a muon spectrometer for events originating in ND-LAr.

In addition to its critical role in the DUNE long-baseline oscillation program, ND-GAr will collect a significant number of neutrino interactions ($\sim$1.6 M/yr) on its gaseous argon target, enabling a broad stand-alone physics program of neutrino interaction cross section measurements including the study of exotic physics channels, as well as Beyond Standard Model searches.

\subsection{Oscillation Physics}

The ND-GAr detector provides lower threshold measurements than ND-LAr can provide, making it possible to pin down the interaction model and associated systematic uncertainties needed for the oscillation program.   In particular, ND-GAr measures hadron species,  multiplicity, and momenta both to very low threshold and also at energies where hadrons would interact in the ND-LAr or exit the detector volume, thus preventing particle identification in ND-LAr.  This complementary advantage allows the oscillation analysis strategy to constrain interaction processes by outgoing particle content, which correlates strongly with momentum transfer, intranuclear reinteraction processes, and missing energy from neutrons that affect the neutrino energy estimate. Since these interaction processes are not strongly correlated with flux, ND-GAr will be able to disentangle these uncertainties.

\begin{figure}[ht]
\centering
\includegraphics[width=0.495\textwidth]{figures/cpv_exp_ndforwp_dcpmax.png}
\includegraphics[width=0.495\textwidth]{figures/cpv_exp_ndforwp_dcp50pct.png}
\caption[Impact of full ND-GAr on CP violation sensitivity]{Impact of the Phase~I and reference near detector configurations on CP violation sensitivity, shown for maximal CP violation (left) and for 50\% coverage of $\delta_{CP}$ space.}
\label{fig:cpsens}
\end{figure}

Figure~\ref{fig:cpsens} shows the early running (left) and ultimate (right) impact of the ND-GAr detector on the long-baseline oscillation sensitivity to CP violation. The Phase I sensitivity is evaluated from a case study where data based on the NuWro generator~\cite{Golan:2012wx,Golan2012nuwro} are fit with the nominal GENIE model, resulting in a bias to oscillation parameters that can be mitigated by adding data from ND-GAr. As seen in the left panel, if CP violation is maximal, there is not much difference between the exposure required to achieve sensitivity with $3\sigma$ significance using TMS (Phase~I Near Detector) and ND-GAr (Reference Near Detector~\cite{Abi:2020qib, DUNE:2021tad}). Maximal CP violation is the most favorable case for DUNE's sensitivity, but a more realistic assessment of sensitivity is given by looking at the full range of possible values of $\delta_{CP}$ (or some fraction of that range of values). The right panel shows DUNE's expected sensitivity to 50\% of all $\delta_{CP}$ values, for the same detector configurations. In this case, the experiment with TMS
may possibly never reach the $5\sigma$ significance level even with very long exposures. The full ND-GAr detector is ultimately needed to achieve DUNE's scientific goal for CP violation.  This need becomes more critical after DUNE reaches an exposure of approximately 200 kt-MW-yrs.

\subsection{Cross Section Physics}

Precision measurements of neutrino interaction cross sections are critical to the oscillation program, but are also interesting in and of themselves. In liquid argon detectors, secondary interactions are a significant effect~\cite{Friedland:2018vry}, since the hadronic interaction length of pions is $\lambda \sim$1~m in LAr. By contrast, in 10~atm of gaseous argon, $\lambda \sim$90~m.  The relative lack of secondary interactions for particles formed in neutrino interactions in the gaseous argon fiducial volume will provide event samples that are less dependent on understanding of detector response and models of secondary interactions.
Since the target nucleus in ND-GAr is the same as that in the ND-LAr and far detectors, this information feeds directly into the interaction model constraints for the oscillation analysis, but without complicating nuclear physics concerns. These measurements will also be useful inputs for tuning the interaction models to better reflect what is seen in data, as the agreement among models and existing world data is not great.

ND-GAr, with its full solid-angle acceptance and MeV-level proton tracking threshold, is ideal for performing exclusive final-state measurements. In the exclusive channels, $\nu+\textrm{A}\rightarrow\ell+\textrm{hadrons}+\textrm{A}'$, where the final-state hadrons are measured, the details of the intranuclear dynamics of the interactions can be precisely extracted by exploring momentum conservation in the transverse plane to the neutrino direction, regardless of the unknown neutrino energy. This technique of measuring Transverse Kinematic Imbalance (TKI) in neutrino interactions~\cite{Lu:2015hea,Lu:2015tcr,Furmanski:2016wqo,Lu:2019nmf} has been successfully applied in MINERvA~\cite{MINERvA:2018hba,MINERvA:2019ope,MINERvA:2020anu} and T2K~\cite{T2K:2018rnz,T2K:2021naz}. With the state-of-the-art tracking resolution, ND-GAr will use TKI to further explore neutrino-argon interactions with unprecedented precision~\cite{DUNE:2021tad}.

The predicted event yields for one year of neutrino running are shown in Table~\ref{tab:Stats}, assuming the DUNE flux~\cite{DUNE:2020ypp},
cross-sections from GENIE~\cite{Dytman:2015xaa, Andreopoulos:2009rq} 2.12.2, and a fiducial mass of 1~t ($\simeq$ 55\% of the active mass).  The lower portion of the table highlights the expected yields for some of the exclusive final states for which ND-GAr will be able to make precise measurements. The baseline gas in ND-GAr is assumed to be 10~atm of an argon gas admixture of 90\% Ar and 10\% CH$_4$, which results in $\simeq 97\%$ of interactions occurring on Ar nuclei.

\begin{table}[!ht]
    \centering
    \caption{Number of events in the ND-GAr HPgTPC with 1~t fiducial mass for 1 year of running in $\nu$-mode, where the horn current direction generates a beam that is primarily neutrinos. The upper portion of the table shows overall numbers of events in broad categories of charged and neutral current interactions, while the lower portion shows event yields for exclusive final states.}
\begin{tabular}{l|c}
\hline
Event class     &     Number of events per ton-year \\
\hline\hline
$\nu_{\mu}$ CC & $1.6 \times 10^{6}$ \\
$\bar{\nu}_{\mu}$ CC & $7.1 \times 10^{4}$ \\
$\nu_{e} + \bar{\nu}_{e}$ CC & $2.9 \times 10^{4}$ \\
NC total & $5.5 \times 10^{5}$ \\ \hline
$\nu_{\mu}$ CC$0\pi$ & $5.9 \times 10^{5}$ \\
$\nu_{\mu}$ CC$1\pi^{\pm}$ & $4.1 \times 10^{5}$ \\
$\nu_{\mu}$ CC$1\pi^{0}$ & $1.6 \times 10^{5}$ \\
$\nu_{\mu}$ CC$2\pi$ & $2.1 \times 10^{5}$ \\
$\nu_{\mu}$ CC$3\pi$ & $9.2 \times 10^{4}$ \\
$\nu_{\mu}$ CC other & $1.8 \times 10^{5}$ \\
\hline \hline
\end{tabular}
 \label{tab:Stats}
\end{table}

\subsection{Potential to Employ Different Targets}

One unique advantage of ND-GAr, compared to the other DUNE ND components, is its flexibility to use various gas mixtures as interaction targets. A safe and hydrogen-rich gas mixture (such as 92\% Ar and 8\% CH$_{4}$), with the help of the superb tracking, would enable measurements of event-by-event neutrino-hydrogen interactions~\cite{Lu:2015hea,Hamacher-Baumann:2020ogq}, providing direct access to the more fundamental physics parameters, such as the axial form factor and proton radius, for the first time in 40 years, with better detector technology and better understood fluxes.  These measurements would also provide an anchor to enable comparison of Ar/H and C/H cross section ratios. Filling ND-GAr with these other targets could be considered after sufficient data to perform the oscillation analysis constraints are collected with the baseline argon gas mixture.

\subsection{Physics Beyond the Standard Model}

LBNF's high-intensity proton beam will provide a large neutrino flux that will be sampled by ND-GAr.  This will enable DUNE to discover new particles and unveil new interactions and symmetries beyond those predicted in the Standard Model (beyond the standard model, or BSM). In particular, ND-GAr can search for neutrino tridents, heavy neutral leptons (HNL), light dark matter, heavy axions, and anomalous tau neutrinos that come from short-baseline mixing with sterile neutrinos~\cite{DUNE:2020fgq}.

In general, the background contributions in searches for rare events tend to scale directly with the detector mass (which is larger for ND-LAr), while signal events often scale with detector volume (which is similar for ND-LAr and ND-GAr). As a result, the ND-LAr suffers more significantly from backgrounds than ND-GAr. ND-GAr's relatively large volume will be beneficial in the search for the rare decay events. Independent ND-GAr analyses that complement those in ND-LAr will serve to constrain backgrounds and achieve a stronger BSM physics reach with the near detector complex than could be achieved with either detector alone~\cite{koppetalpaper}.

\subsubsection{Neutrino Tridents}
Neutrino trident production---the production of a pair of oppositely-charged leptons through the scattering of a neutrino on a heavy nucleus---is a powerful probe of new physics in the leptonic sector. The Standard Model expectation is that the DUNE near detector will collect around a dozen of these rare events per ton of argon per year, enough to measure with precision the cross sections of such processes~\cite{Altmannshofer:2019zhy}. The main challenge is to distinguish the trident events from the copious backgrounds, mainly consisting of charged-current single-pion production events, as muon and pion tracks can be easily confused. ND-GAr will will tackle this search by improving muon-pion separation through $dE/dx$ measurements in the HPgTPC and the calorimeter system, and ND-GAr's magntic field will significantly improve signal background separation by tagging the opposite charges of the two leptons in the final state.

Measurement of neutrino trident interactions may reveal new evidence for or constrain BSM physics models. For instance, a class of models that modify the trident cross section are those that contain an additional neutral gauge boson, $Z^{\prime}_0$, that couples to neutrinos and charged leptons. This $Z^{\prime}_0$ boson can be introduced by gauging an anomaly-free global symmetry of the Standard Model, with a particular interesting case realized by gauging L$_{\mu} -$L$_{\tau}$. Such a $Z^{\prime}_0$ is not very tightly constrained and could address the observed discrepancy between the Standard Model prediction and measurements of the anomalous magnetic moment of the muon, (g$-$2)$_{\mu}$. Its presence would be apparent through a large increase (a factor of 2-3) of the measured trident cross section over the SM prediction, whereas a measurement consistent with the SM would provide new  $Z^{\prime}_0$ constraints in the region of parameter space relevant to (g$-$2)$_{\mu}$.

\subsubsection{Heavy Neutral Leptons}
Searches for several possible HNL decay channels, including those with $\nu e^{+} e^{-}$, $\nu e^{+/-} \mu^{-/+}$, $\nu \mu^{+} \mu^{-}$, $\nu \pi^{0}$, $e^{+/-} \pi^{-/+}$, and $\mu^{+/-} \pi^{-/+}$ final states, can be undertaken in the near detector complex~\cite{breitbach2021searching}. Neutrino interactions such as neutral-current neutral pion (NC $\pi^{0}$) interactions can act as backgrounds to some of these HNL decay channels. In ND-GAr, we will be able to reject many of these backgrounds, since the pressurized gaseous argon medium of ND-GAr can track charged particles with kinetic energies as low as 5~MeV, providing hadronic information right at the interaction vertex and enabling rejection of a significant fraction of the NC $\pi^{0}$ background events. The ND-GAr calorimeter surrounding the argon medium can be used to efficiently reconstruct photons that do not convert in the gas volume, aiding in background rejection for HNL searches. Another example of a dominant background (particularly for HNL channels with $\nu \mu^{+} \mu^{-}$, and $ \mu^{+/-} \pi^{-}$ final states) consists of charged-current muon neutrino interactions with charged pions in the final state, where the muons are misidentified as pions. The pressurized gaseous argon medium in ND-GAr will enable us to more extensively sample ionization per unit track length providing improved muon-pion separation through $dE/dx$ measurements, as can be seen in Fig.~\ref{fig:pep4-dedx}. For even better muon-pion separation, we can further use the calorimeter system in ND-GAr.  In addition to PID in the pressurized gas argon component of ND-GAr, the calorimeter and the muon tagger system will help to further reduce muon-pion confusion, especially at high energies~\cite{DUNE:2021tad}.

\begin{figure}[ht]
\centering
\includegraphics[width=0.6\textwidth]{figures/DUNE_HNL_sensitivity.png}
\caption[DUNE HNL sensitivity]{The background-rejection capability of the ND-GAr detector results in improved coverage of parameter space in HNL searches, as shown by the comparison of the ``no background'' sensitivity with the ``on-axis only'' and ``DUNE-PRISM'' sensitivities~\cite{koppetalpaper}.}
\label{fig:koppetalfig}
\end{figure}

As an example, the DUNE sensitivity to the search for HNL is shown as a function of HNL mass in Figure~\ref{fig:koppetalfig}, which is taken from Ref.~\cite{koppetalpaper}. This sensitivity was obtained by taking into account the individual capabilities of ND-LAr and ND-GAr. In particular, the analysis benefits from the better signal-to-background ratio achieved in ND-GAr, which is due to the fact that HNL signal scales with volume while backgrounds scale with mass. Allowing the detectors to move to positions off the beam axis with the DUNE-PRISM technique only results in a small change to the sensitivity (comparing the ``on-axis'' and ``DUNE-PRISM'' lines in the plot) because effective background suppression can be achieved with ND-GAr even in the on-axis position. Furthermore, since going off-axis also does not harm the sensitivity, despite the lower fluxes in off-axis positions, the search for HNLs can be carried out for any positioning of the detectors~\cite{koppetalpaper}. The ``DUNE-PRISM'' line is the expected achievable sensitivity with ND-LAr and ND-GAr, assuming running time equally split between the on-axis position and six different off-axis locations, while the ``no background'' line represents the sensitivity for a hypothetical background-free analysis, showing that the expected achievable sensitivity at the DUNE near detector complex is not far from what could be achieved with an ``ideal'' experiment.

\subsubsection{Light Dark Matter}
ND-GAr can also search for light dark matter that is produced in the neutrino beam target and subsequently interacts or decays inside the detector. In particular, a light dark matter signal with a single-electron final state (DM e $\rightarrow $ DM e) can be captured with the near detector complex. The neutrino-electron scattering ($\nu$ e $\rightarrow $ and $\nu$ e) and electron neutrino charged current quasi-elastic scattering interactions ($\nu_{e}$ n $\rightarrow $ e p) can look very similar to these signals and can act as backgrounds. According to a study done in Ref.~\cite{lightdm}, the $\nu_{e}$ n $\rightarrow $ e p is easily reducible using energy and angular information of the single-electron final state in ND-LAr. In ND-GAr, we can take advantage of the low detection threshold and use the vertex information to reduce this background even further. From the same reference~\cite{lightdm}, however, the electron scattering interactions are irreducible in ND-LAr, while in ND-GAr, the number of electron scattering events is very small to start with (135 per kton per year, as shown in Table~\ref{tab:Stats}), enabling a nearly background-free light dark matter selection in ND-GAr.

\subsubsection{Heavy Axions}
There are also opportunities to search for heavy axions in the near detector complex~\cite{PhysRevD.103.095002}. Two main signatures of an axion-like particle have $\gamma \gamma$ and hadrons in final states. The NC $\pi^{0}$ events act as backgrounds to these axion-like particle signals, but as mentioned above, we can easily reject most of these backgrounds by focusing on the rich hadronic information at the vertex that only ND-GAr can provide.

\subsubsection{Tau Neutrinos}
ND-GAr also presents the opportunity to carry out a physics program geared towards probing anomalous $\nu_{\tau}$ interactions.
The $\tau$ lepton is not directly observable in the DUNE detectors due to its short $2.9\times^{-13}$\,s lifetime, and it is only produced for interactions where the incoming $\nu_\tau$ has an energy of $\sim3.5$\,GeV due to the relatively large $\tau$ mass of 1776.82\,MeV. However, the final state of $\tau$ decays, $\sim65\%$ into hadrons, $\sim18\%$ into $\nu_\tau+e^-+\bar{\nu}_e$, and $\sim17\%$ into $\nu_\tau+\mu^-+\bar{\nu}_\mu$, is readily identifiable in the DUNE ND, given the excellent spatial and energy resolution of ND-GAr and the other ND instruments. While within a three-flavor scenario, the DUNE ND baseline is far too short for $\nu_\mu\rightarrow\nu_\tau$ oscillations to occur, there exists the exciting possibility that $\nu_\tau$ originating in sterile-neutrino driven fast oscillations could be detected with ND-GAr. In particular, ND-GAr would provide excellent sensitivity to the $\tau\rightarrow\mu$ detection channel, with high energy muons in the final state, inaccessible with ND-LAr due to its lack of magnetic field and limited muon energy containment. Furthermore, the TMS detector option is limited to measuring muons up to $\sim$6 GeV/$c$ before they range out, while ND-GAr's use of curvature in the magnetic field to reconstruct muon momentum extends that range to 15 GeV/$c$ and beyond. This extension will become even more valuable when operating LBNF in the high-energy tune, aimed at enriching the available sample of $\nu_{\tau}$ at the far detector, while enhancing sensitivity to anomalous $\nu_{\tau}$ appearance at the near detector~\cite{DeGouvea:2019kea}. Preliminary studies using LBNF's nominal flux and including ND-GAr, estimate that DUNE's sensitivities to anomalous $\nu_\tau$ appearance may extend beyond those of previous searches, such as those carried out by NOMAD and CHORUS.

\section{Detector Performance Requirements} \label{sec:detperf}

The overall DUNE requirements for the near detectors include transferring measurements to far detector, constraining the cross section model, measuring the neutrino flux, and obtaining measurements with different fluxes.   The ND must have reconstruction capabilities that are comparable to or exceed those of the FD in order to effectively transfer measurements.  The ND must measure outgoing recoil particles in neutrino-Ar interactions to ensure that sensitive phase space is properly modeled. It must also measure the wrong sign contamination and measure the intrinsic beam $\nu_{e}$ component.

ND-GAr is able to meet these requirements with its argon target, magnetization,  uniform angular acceptance, excellent particle identification, low energy tracking thresholds, and wider range for muon momenta measurements. It will also have the ability to probe different off-axis fluxes with spectra spanning region of interest as part of the PRISM concept.  Fulfilling the DUNE ND requirements leads to a set of derived detector capabilities for the ND-GAr.  These are extensively detailed in Ref.~\cite{DUNE:2021tad}, and the key performance capabilities are summarized below.

{\bf Derived ND-GAr detector capabilities}
\begin{itemize}

\item The DUNE near detector must classify interactions and measure outgoing particles in a LArTPC with performance comparable to or exceeding that of the FD. It must
measure particles in neutrino-argon interactions with uniform acceptance, lower thresholds than LArTPC, and minimal secondary interaction effects.  To achieve these goals, the ND-GAr must be able to \textbf{constrain the muon energy scale with an uncertainty of 1\% or better} to achieve the oscillation sensitivity described in Vol.~II of the DUNE FD TDR~\cite{DUNE:2020ypp}. The strongest constraint comes from the calibrated magnetic field of the HPgTPC coupled with {\it in-situ} measurements of strange decays.

  \item {The DUNE ND must be able to measure muons with \textbf{a momentum resolution of less than 4\%}, with non-Gaussian tails corresponding to an RMS $<$ 10\%.  Simulations indicate that a high-pressure gaseous argon TPC should achieve or exceed this resolution.~\cite{DUNE:2021tad} }

  \item {The near detector must be able to detect, identify, and measure the momentum of protons emitted from neutrino-argon interactions. To fulfill this, the ND must have a tracking threshold low enough to \textbf{measure the energy spectrum of protons emitted due to final state interactions (FSI) in CC interactions}. Theoretical studies, such as those reported in Refs.~ \cite{Nieves:2005rq,Lalakulich:2012gm,Mosel:2013fxa}, suggest that FSI cause a dramatic increase in final state nucleons with kinetic energies in the range of a few tens of MeV. ND-GAr is suitable for measuring such low-energy protons. The threshold in ND-GAr is an interplay between the argon gas density, readout pixel size, and ionization electron dispersion. Performance studies indicate that a tracking threshold of 5 MeV (or a momentum of 97 MeV/c) is achievable and satisfies this requirement. }

  \item {The ND must be able \textbf{to characterize the charged pion energy spectrum in $\nu_{\mu}$ and $\bar{\nu}_{\mu}$ CC interactions from a few GeV down to the low energy region} where FSI are expected to have their largest effect.
      \begin{itemize}
      \item {Theoretical studies, such as those reported in Ref.~\cite{Mosel:2014lja}, predict that FSI are expected to cause a large increase in the number of pions with kinetic energies between 20-150 MeV and a decrease in the range 150-400 MeV. A kinetic energy of 20 MeV corresponds to a momentum of 77 MeV/c. ND-GAr must be able to measure 70 MeV/c charged pions with an efficiency of at least 50\% so as to keep the overall efficiency for measuring events with three pions at the 70 MeV/c threshold above 10\%.

      }

      \item  {ND-GAr must also have the ability to \textbf{measure the pion multiplicity} and charge in final states with up to 3 pions, so as to inform the pion mass correction in the ND and FD LArTPC. This capability is most important for pions with an energy above a few 100 MeV since those pions predominantly shower in LAr.
      }
      \end{itemize}
    }

    \item {ND-GAr must be able \textbf{to detect and measure $\pi^{0}$'s}, using their decay photons, over the same momentum range as for charged pions.

    }

     \item {ND-GAr must be able \textbf{to identify electrons, muons, charged pions, charged kaons, and protons}. ND-GAr addresses this requirement using a combination of $dE/dx$ in the HPgTPC, $E/p$ using the energy measured in the calorimeter, and the momentum measured by magnetic spectroscopy in the HPgTPC, and by penetration through the calorimeter and muon system.
    }

\end{itemize}

ND-GAr, because of the calorimeter surrounding its HPgTPC, is also able to characterize the energy carried by neutrons with kinetic energies in the range 50-700~MeV. This capability, while not a requirement, is desirable for constraining uncertainties related to the multiplicity and energies of nucleons ejected from the nucleus during neutrino interactions.

redpajama_set_name: RedPajamaArXiv


text:
myscience.org › news › news 2021 › Vaccinated people with breakthrough COVID infections had lower viral loads
Vaccinated people with breakthrough COVID infections had lower viral loads - 19.11.21
Vaccinated people with breakthrough COVID infections had lower viral loads
Health | Pharmacology
Vaccinated health care workers who experienced breakthrough COVID-19 infections during the winter of 2020-21 had lower viral loads than their similarly infected but unvaccinated co-workers, according to a new UCLA study.
The findings, published this week in the peer-reviewed journal Open Forum Infectious Diseases, show that infected workers who were fully or even partially vaccinated with either of the two mRNA vaccines authorized for use in U.S. had less of the virus in their test samples and were therefore less likely to "shed" — or orally or nasally expel — viral particles.
While the research was conducted prior to the recent delta variant surge, the findings are consistent with current data showing that those who are vaccinated are less likely to spread the virus, said the study's lead author, Dr. Paul Adamson, an assistant professor of infectious diseases at the David Geffen School of Medicine at UCLA.
"These findings should be reassuring for the general public because lower amounts of virus might translate to decreased transmissibility," Adamson said. "This is another benefit of the vaccines and yet another reason to get vaccinated against COVID-19."
For the study, the researchers analyzed 43,516 COVID-19 tests administered to approximately 11,930 UCLA health care workers between Dec. 16, 2020 — roughly the time the two-dose Pfizer-BioNTech and Moderna mRNA vaccines became available at UCLA — and March 31, 2021. During the course of the study, 880 individuals tested positive for infection.
The research team examined these workers' vaccination status at the time of their infections to see who had received either of the mRNA vaccines and who had not been vaccinated. They also specifically measured cycle threshold, or CT, values from the COVID-19 tests of infected individuals. These CT values have an inverse relationship to the amount of virus one has: The lower the CT value, the higher the viral load, and vice versa.
Of the 880 total COVID-19 infections, 616 (70%) occurred among unvaccinated employees, while 264 (30%) occurred among those who had received at least one vaccine dose. The researchers then examined CT values for each infected employee, broken down into vaccination status and time categories:
The lowest CT values, corresponding with the highest amount of the virus, were seen in the samples from unvaccinated employees. The amount of virus in the samples decreased with each of vaccination category, with employees who had received both mRNA vaccine doses carrying the lowest amounts of the virus.
The researchers noted that recent data suggest that viral loads of the delta variant — which became the dominant strain in Los Angeles County in May 2021, after the study period had ended — are similar in both vaccinated and unvaccinated people. But data also indicate that vaccinated individuals experience a more rapid decline in delta variant viral loads and clear the virus faster than unvaccinated people, which also helps to reduce viral transmission.
"SARS-CoV-2 viral loads are known to be a critical driver of transmission," the researchers wrote. "Thus, our findings, using real-world data, suggest that COVID-19 vaccination might translate into decreased transmissibility of SARS-CoV-2 infections."
The researchers said the study may have some limitations. For instance, they may not have captured variables such as age, infection onset and severity of symptoms, and collection and testing methods, which might have had an impact on CT values. In addition, the number of people with mild or asymptomatic infection may have been undercounted, possibly affecting the overall lower CT values across all categories.
Additional study authors are Dr. Michael Pfeffer, Dr. Valerie Arboleda, Omai Garner, Dr. Annabelle de St. Maurice, Benjamin von Bredow, Dr. Jonathan Flint, Leonid Kruglyak, and Dr. Judith Currier.
Top UCLA News
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redpajama_set_name: RedPajamaCommonCrawl


Vodafone has demonstrated dynamic spectrum sharing between 2G and LTE in the 900MHz band on its commercial network in Turkey.
The trials, which took place in Trabzon (pictured) on the country's Black Coast in partnership with Huawei, were held over several months. Vodafone was able to provide up to 10MHz of LTE capacity on the band, which it said led to an improvement in network performance and an increased user experience.
It added that download and upload throughput was increased by a fifth.
The breakthrough builds upon work Vodafone conducted with Huawei in April last year, when they demonstrated non-dynamic spectrum sharing in the 900MHz band. It said downlink throughputs increased by an average of 58 percent and uplink by 44 percent.
A report last year from the European Union said spectrum sharing may be required for future 5G networks.
The Turkish spectrum sharing demonstration is the latest collaboration between Vodafone and Huawei in the country.
Last summer, both telcos deployed a self-organising network in Turkish capital Istanbul, which they said increased the quality of Vodafone's 3G and LTE networks.
Mobile Europe is currently polling operators for its annual survey - click here to take part.


WASHINGTON, D.C. - Today U.S. Senators Tom Udall and Martin Heinrich and U.S. Representative Ben Ray Luján announced that the Department of Transportation has awarded Los Alamos Atomic City Transit $1.485 million through the Low or No Emission Grant Program to purchase new zero-emission battery electric buses to replace the City's existing diesel fleet.
Atomic City Transit offers transit service in both Los Alamos and White Rock, ADA complementary paratransit, and a shuttle service to Bandelier National Monument during peak visitor season. This project is the first stage of the County of Los Alamos's effort to introduce low or no emissions vehicles. Battery electric buses reduce energy consumption and carbon emissions. It's estimated that over the 12-year life of a typical bus, replacing just one diesel transit bus with a zero-emission battery electric bus can save over 2.4 million pounds of direct emissions.
"Once again, Los Alamos is leading the way, this time by making the transition to all electric public transit," said Heinrich, a member of the Senate Energy and Natural Resources Committee. "The electrification of the transportation sector, including public transit, will be critical in solving our climate and carbon pollution challenges. I am proud to support this grant for Los Alamos as it helps to accelerate the transition to an emission free transportation sector."


Scientists at Imperial College London have designed a concept mission to land astronauts on Mars.
The plan envisages a three-person crew journeying to Mars aboard a small two-part craft.
The craft would rotate to generate artificial gravity and use a heat shield to protect itself against solar flares.
The crew would then return to Martian orbit in a pre-sent craft fuelled using ice from beneath the planet's surface.
The concept, developed in conjunction with the BBC, is intended to spark further debate about the technical obstacles and risks that would have to be overcome in order to put humans on Mars.
"Every part of this mission scenario has been demonstrated one way or the other, including the in situ propellant production on the surface of Mars," said Prof Tom Pike, who led the Imperial design team.
The new Imperial concept comes amid renewed interest in the Red Planet with two private groups having proposed missions in recent months.
The Imperial team have designed a two-part craft, consisting of a Martian lander with a heat shield, inside which the crew would also ascend into Earth orbit.
Directly beneath the lander on the launch pad would be a "cruise habitat vehicle", a cylindrical craft split into three floors and measuring some 10m (30ft) in height and 4m in diameter.
Once in Earth orbit, the astronauts would move from the lander into the larger habitat vehicle before a rocket burst would propel the conjoined craft on a trajectory to Mars. The quickest journey time would be nine months when Earth and Mars are in optimum alignment.
Shortly into the journey, the lander and cruise vehicle would unwind from each other on a steel cable tether to a distance of some 60m. Short thruster bursts from both vehicles would then set them spinning around a centre of gravity.
This would create artificial gravity within the habitat vehicle similar to Earth's gravity, which the scientists believe would prevent the type of muscle and bone wastage that weightlessness would cause, which would render the astronauts unable to walk on Mars once they arrived.
Later in the mission, the spin rate could be reduced to better emulate Martian conditions, where gravity is 40% that on Earth.
"We've obviously got some real issues with a long-term mission in terms of the de-conditioning which goes on in the space environment," Ryan Robinson, the Imperial team's physiologist, told BBC News.
During the journey, the crew's health would be monitored closely with wireless sensors – but they would rely entirely on medication aboard the craft and the skills of their fellow crew members should they fall sick.
The long journey and confined quarters could also affect their mental health, and conflicts between the crew could arise.
During the journey, the craft could deploy a number of measures to try to reduce the threat to the astronauts from solar and cosmic radiation, the former from the Sun, the later emanating from beyond our solar system.
Water could run within the shell of the cruise craft to absorb radiation, while the Imperial team also examined the idea of fitting superconducting magnets to the craft, which would generate a magnetosphere to deflect solar and cosmic radiation in the way the Earth's natural magnetosphere does.
The crew would also deploy emergency procedures should satellites detect a major incoming solar flare.
This would involve winding in the tether and re-directing the lander's heat shield towards the Sun to protect the astronauts in the cruise craft.
The crew would also put whatever they could find between them and the front of the vehicle to absorb the solar burst.
Even with such measures, a solar flare could still kill, or result in cancers. Cosmic radiation could also take its toll.
"We've got some great results from the Mars curiosity rover," said Imperial's Martin Archer, who specialises in solar and cosmic radiation.
Once the craft reaches Martian orbit, it would contract together and the astronauts would pass into the lander ready for detachment and descent.
Its shield would absorb the heat of entry before being jettisoned and then multiple parachutes would deploy to slow the craft, with thrusters used to further slow and guide it through the final metres to the landing site.
The Imperial team propose a landing site near the equator, where milder conditions exist.
They would hope to land near a pre-sent Martian habitat module and rover, although the rover could be robotically controlled to travel from the habitat to the landing site if the distance was too great for a crossing on foot.
Then the Martian visit would begin – a first human landing on another planet.
The time spent on the Martian surface would be dictated by the next time Earth and Mars aligned for a speedy return home. It could be two months, or we might choose to spend more than two years on Mars, says the Imperial team.
It is during this time that the human crew could try to demonstrate why humans could still outperform robots in analysing and understanding the Martian environment.
"Some people think that the use of humans is just something that is popular and attractive from an adventure and inspirational point of view, but there are also real scientific benefits for sending humans," said Prof Mark Sephton, the team's geologist.
Radiation would remain a danger during the stay, with Mars possessing no magnetosphere to shield the surface from cosmic and solar rays. Shovelling up soil from the surface during the mission and part-burying the habitat module could help, as could staying inside during a solar burst.
Then comes the return home, which would be far from simple.
The approach taken by the Imperial scientists would be to pre-send both the habitat module, rover and a return vehicle before any human launch.
The return vehicle would land at a latitude where water ice would be found in large amounts just a few centimetres beneath the surface. Robotic devices would mine the ice, which would then be split into hydrogen and oxygen using electrolysis.
These gases could be used as fuels on their own, or the hydrogen could be combined with carbon dioxide from the Martian atmosphere using a catalyst to produce methane, which is a more stable and energy-dense fuel than hydrogen.
As the Imperial team propose landing near the equator, a crew would have to travel by rover to a cooler latitude where the return vehicle and ice-mining devices would be waiting. Several hundreds of kilometres may have to be crossed, posing both risks and opportunities to further explore the Martian landscape.
Should they make it safely, the crew would have a narrow launch window to ensure the quickest most fuel-efficient return to Earth.
After leaving Mars, the return vehicle would dock with the orbiting cruise vehicle and replace the Martian lander as the counter-balance within the spinning tethered structure en route to Earth. Like the lander, the return vehicle would have to be fitted with a shield to protect the crew during extreme solar activity.
After at least nine months, the craft would reach Earth orbit and dock with the International Space Station before the astronauts could take a Soyuz capsule home, the team envisages.
The new Imperial concept comes amid renewed interest in the Red Planet, with two private groups having proposed missions.
Businessman and former space tourist Dennis Tito wants to send an American couple on a mission beginning in 2018 that would pass within 100 miles (160km) of Mars before using the planet's gravity to "slingshot" the craft back to Earth.
The Dutch project Mars One proposes putting a human colony on the planet beginning in 2023, while SpaceX chief executive Elon Musk has spoken of sending a private human mission to Mars within 12-15 years.
The US, Russian, European and Chinese space agencies maintain long-term plans to put humans on Mars.
The documentary How to put a human on Mars can be seen this weekend on the BBC News channel and BBC World News.
I thought the heat shield was not enough, but if the habitat is spinning then how do you keep it facing our Sun? Even if you do Some of the solar storm comes in sideways so that would not be enough. The Solar storm shelter should be a colletion of all your water, food, and much other mass.
Stopping the spin and realing in the cable will also use more fuel and then more much be used agian once the solar storm has stopped.
The "Mars Direct" plan calls for bringing hydrogen form Earth because there is a risk depending on the ability to collect ground water ice wherever you land. Methan is much easier to store than Liquid hydrogen. If fact the tempraure and pressures are even a bit easier than LOX. Also hydrogen is even smaller than the gaps between the closest atoms in all fuel tanks so under pressure it can leak through all containers. If we can collect twenty five tons of water then again make methan LOX fuel.
About the easiest and most practical way to get and keep hyrogen in the tank is to let is blead off and vaporize. The way we make hydrogen that cold is to run it though a radiator and then let it faporize so we get lots of vapor and some liquid under lower pressure.
If you only spend two months on the surface then it takes much more fuel to get to Mars in nine months that you can take in six month, but then you spend a year and a half on the surface of Mars. The two month surface stay is far more dangeorus than the year and a half, and takes far more fuel.
Spending a full year travling there and back to only spend a year and a half should only be the first trip. From then on it should be at least three and a half years for one year of travel. After few trips like this almost all going to Mars should be one way.
You need a heat shield and some fuel or lots of fuel to go to the ISS. Far easier it to come in from Mars also using a capsul. The US is developing a few of these. The Dragon Rider is desinged to get a thicker heat shield and return from Mars. As I understand the Soyus capsule is not desinged to do this.
As I understand both the Tito Inspiration Mars, and the Dutch Mars One are using SpaceX equipment which will be ready in two years or less. The Mars one will be largely a SpaceX mission one way to homestead on Mars.


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HomePoliticsImpact of Border Deployments Is Felt by Troops at Home and Away
Impact of Border Deployments Is Felt by Troops at Home and Away
December 25, 2018 Politics Comments Off on Impact of Border Deployments Is Felt by Troops at Home and Away
WASHINGTON — Instead of preparing for a coming deployment to Europe, soldiers with the First Cavalry Division at Fort Hood, Tex., are checking IDs at the base's entrance gates, filling in for troops who have been sent to the southwest border.
Nearby, a medical company is not getting ready for its overseas deployment, either; the soldiers are instead building aid stations in southwestern Texas.
And in Nogales, Ariz., public affairs officers who are supposed to be heading to Poland, Romania and Germany in April have spent the last month not studying the internecine rivalries that govern the former Soviet bloc, but fielding telephone calls from "The Daily Show" and other media asking if border troops are playing cards all day.
Eight weeks after President Trump's decision to send 5,900 active-duty American troops to the border with Mexico to help stop a migrant caravan fleeing drug violence in Central America, Pentagon officials say the mission is starting to affect "readiness" — a military measure to determine whether American soldiers are prepared for battle.
If the border deployment ends in January, the latest date for which the military mission has been extended, Defense Department officials said the damage could be absorbed.
But the diversion of forces follows warnings — including by Gen. Mark A. Milley, the Army's chief of staff and Mr. Trump's pick as the next chairman of the Joint Chiefs of Staff — that the Army was still years away from its goal of having 30 combat brigades ready to fight at any given time.
American troops stationed at the southwest border to drive and fly Border Patrol officials around are not conducting the missions and training needed, in one military catchphrase, to "fight tonight," officials said. And military units that have not been sent to the border must now pick up the routine duties for those who have.
The government shutdown, spurred by Mr. Trump's demand for $5 billion for a border wall, has not affected staffing of the border deployment, Defense Department officials said, because Pentagon and Department of Homeland Security employees at the border are considered essential personnel.
To be sure, the number of troops being diverted is small enough that, so far, the effect on overall readiness has been minimal.
Speaking to reporters this month, Jim Mattis, the departing defense secretary, said the rotating schedule of units and the gradual drawdown of troops on the border are part of why the deployments would not have an "appreciable impact in military readiness." Mr. Mattis resigned on Thursday, and will leave the Pentagon by Jan. 1, over what he described as a differing approach with Mr. Trump over military worldviews.
Marine Col. Amy R. Ebitz, a fellow with the Brookings Institution, said the border deployment might actually help readiness, not hurt it. She noted that troops who are welding structures and driving around Border Patrol agents are still engaged in training — even on tasks unrelated to combat.
"It's an opportunity to train," Colonel Ebitz said. "We do it all over the world, so why would our border be any different?"
As evidenced by the duties at Fort Hood, the border missions also affect the soldiers still in garrison. The deployment has taxed — if not heavily — how the Army trains and prepares to go abroad on a deployment schedule that is planned and orchestrated months in advance.
It also comes after concerns by top Defense Department officials that 17 years of war in Afghanistan and Iraq has made troops battle-hardened and ready to fight terrorists and insurgents, but unprepared for conventional warfare against big state armies.
Pentagon officials worry that Mr. Trump may try to extend the border deployment well into 2019 to show his political base that he is tough on immigration issues. Such a move, Defense Department officials said, would run counter to his administration's national defense strategy to prepare for conflict with world powers like Russia, China, North Korea and Iran, after almost two decades of fighting terrorism.
On Twitter this month, Mr. Trump suggested that troops would finish building sections of his proposed wall on the southwest border if Congress refused to fund the project.
One Defense Department official said the Pentagon was well aware that the military's budget generally cannot be reprogrammed to pay for projects that Congress has not explicitly approved. But concerns remain that Mr. Trump will seek a creative workaround to the rules.
"If the Democrats do not give us the votes to secure our country, the military will build the remaining sections of the wall," Mr. Trump wrote on Dec. 11.
Representative Adam Smith, Democrat of Washington and the likely next chairman of the House Armed Services Committee, told reporters this month that next year's Democratic-led House would keep a close eye on moves by the White House to use American troops or Pentagon funding to build a border wall.
"The president will send up his budget and we'll see," Mr. Smith told the Defense Writers' Group. "And if there is wall funding, we'll all flip out and say, 'We can't do that.'"
Relations have also deteriorated between the Defense Department, which was ordered to the border, and the Department of Homeland Security, which is responsible for policing it.
Pentagon officials have accused Kirstjen Nielsen, the homeland security secretary, of using the military as a shield against Mr. Trump's anger over the flood of migrants heading to the United States. That surge, in turn, has jeopardized his campaign promise of stopping illegal immigration.
Publicly, Mr. Mattis and other senior military leaders have refrained from criticizing the border mission. But privately, according to a senior official, they are furious over its impact on readiness and morale among soldiers who will be spending Christmas away from their families.
Some of the troops have already begun to return home. But as many as 3,000 soldiers and Marines will be posted on the southwest border over Christmas the New Year.
The deployment was originally scheduled to end Dec. 15 and has been extended through the end of January. At the same time, the overall number of migrants headed to the border is low compared with the early 2000s. The number of migrants traveling in families, however, has surged.
Officials said there was little engineering work to do for the troops, who have already strung concertina wire to bolster border crossings. That means the soldiers and Marines are largely transporting Border Patrol agents or working as military police.
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First, let me say the upper 80 miles are not at all effected by any ODFW closures. Water temps coming out of Pelton are 54 degrees. Well in the SAFE ZONE for the fish, where Trout Unlimited says optimal water temps for Trout range from 45 to 58 degrees.
This afternoon the water temps at Moody Rapid was 64. That was 2 degrees warmer than this morning, but daily fluctuations are normal. There is an ODFW closure from 2 PM to Dark from Mack's Canyon to the Columbia everyday at this time. If you are going to go steelheading near the mouth, keep that in mind it's a morning fish from dawn to 2 PM and then it's beer drinking time the rest of the afternoon and evening.
On August 1st, the bottom release at the dam will begin and we anticipate seeing water temperatures drop several more degrees. I just can't imagine why, after August 3rd or so, why ODFW would continue to have the after 2 PM closure in the macks to the mouth run but thine will tell and biologist will make the call as to what is safe for the steelhead.
Up in the Warm Springs section our guides are getting fish on Spent Caddis and X Caddis, PMD, Purple Haze, Frenchie, Psycho Prince, Girdle Bug, Hares Ear, Caddis Pupa and 3 Dollar Dips. Fishing is good to very good some days.
Give us a week to 10 days and we will start targeting steelhead but at the moment, where they are in the system we are giving them a rest as they come out of the Columbia.


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Home » Health » German police search for 1,000 men after mass sexual assault in Cologne
German police search for 1,000 men after mass sexual assault in Cologne
Posted by Admin on Jan 6th, 2016 // No Comment
Police said some of the attackers were known to them already
by Jess Stauffenberg
German police has received numerous complaints from women who said they were groped and attacked in Cologne city centre. One woman has claimed she was raped.
Wolfgang Albers, the Cologne police chief, says witnesses described the assaults as coming from a group of up to 1,000 men whose appearance indicated they were of "Arab or North African origin."
He said the incidents were "a completely new dimension of crime".
An MP in Angela Merkel's party has claimed the events are proof Germany needs to tighten its borders.
But the police also said many of the men had been known to them for some time and were not newly-arrived refugees, according to The Local.
The crowd, believed to be men between 15 and 35 who were possibly intoxicated, reportedly flooded the city's famous square and began to throw firecrackers and shoot fireworks.
As the festivities took place outside the famous Cologne cathedral, some of the men allegedly began sexually assaulting women and pickpocketing others, according to Reuters.
Local media reported that at least 80 people fell victim to the assaults, 35 of whom were sexually assaulted.
One of the victims, named only as Katja L, told Der Express her buttocks and breasts were grabbed.
"I was groped everywhere. It was a nightmare. Although we shouted and beat them, the guys did not stop. I was desperate and think I was touched around 100 times in the 200 meters," she said.
"Fortunately I wore a jacket and trousers. A skirt would probably have been torn away from me."
Some 60 criminal complaints have so far been filed, including the allegation of rape.
MP Steffan Bilger from Angela Merkel's Christian Democratic Union has claimed the events in Cologne were proof Germany needed to reduce its intake of refugees.
"It can't go on like this," he tweeted. "Urgently needed: reduction of influx, secure borders, intensifying of deportations and meaningful justice."
But others urged Germans not to jump to conclusions, with one user tweeting "it makes me sad that the refugees who really need protection will bear the brunt of the hatred because of Cologne".
"We need to be able to tell the difference."
Police sent 143 local officers and 70 federal officers into the area in a large-scale operation to clear the area.
But due to the dark and sheer scale of people, Mr Albers said that this operation was not effective.
http://www.independent.co.uk/news/world/europe/german-police-search-for-1000-men-after-mass-sexual-assault-in-cologne-a6797126.html
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[Weekender] Kensington resort opens new European-themed branch in Seorak
By Yoon Min-sik
Published : Nov 7, 2019 - 15:13 Updated : Nov 7, 2019 - 15:13
Kensington Hotel & Resort, which opened its 23rd branch up in the mountains of Seoraksan last week, has mostly adopted a strategy of acquiring existing brands and remodeling them instead of building from scratch. This has both pros and cons, but it does result in diversity in terms of the look and features of each hotel and resort under its umbrella.
Kensington Resort Seorak Valley, the newest edition to the brand, shoots for a relaxing getaway in nature. The officials say the buildings are meant to be reminiscent of a mountain range in the Alps, and this resort is considered the finest of the 13 Kensington branches operating in South Korea.
Kensington Resort Seorak Valley / Kensington Hotel & Resort
The resort is located in Goseong-gun, Gangwon Province, well up in the mountains. It is not to be confused with Kensington Resort Seorak Beach, which is -- as the name suggests -- located by the beach roughly half an hour away, making any confusion between the two a highly frustrating mistake.
Be warned that the Seorak Valley is located quite far away from any villages, and the pitch blackness of the woods makes it very difficult to leave the premises at night. But there is a large convenience store on the resort grounds, so you can get pretty much anything you need there.
Upon stepping into the welcoming center, I noticed the wooden decorations, cowbells and indigenous flowers from Europe as well as other props. Its ceilings extended several feet higher than normal, and the lighting felt warm and cozy. Even though it looked suspiciously clean for what is supposed to be a mountain ranch, I had to admit the place did look pretty.
This center doubled as a cafe where we were treated to a barbecue dinner, and having lucked out with the weather we saw the hills through the giant windows -- a spectacle indeed. Employees told me that many of the cabins had been positioned to offer a view of Ulsanbawi (Rock of Ulsan), one of the most well-known features of Seorak.
The cabins were located in mini-villages named after Swiss cities, and I was ushered to the Lucerne section. This held 17 of the biggest cabins, detached 119-square-meter dwellings with separate parking spaces and consisting of three rooms, two bathrooms, a kitchen, a living room and an outdoor area where you could have a cookout. The antler hung over the living room was in keeping with the theme, but the cabin actually felt like a nice, sizable house that people could actually live in.
Gigantic windows allowed me a great view of the surrounding area, and some view it was. Seoraksan is considered one of the most beautiful mountains on the Korean Peninsula. So much so that legend has it that the aforementioned Ulsanbawi was on its way to Kumgangsan -- supposedly the most beautiful place on the peninsula -- but mistook Seoraksan for it and settled there instead.
Slightly smaller 115-square-meter cabins are in the Basel section -- housing up to six, compared with seven in Lucerne. The Lausanne and Bern sections have smaller attached cabins, also with three bedrooms each but with only one bathroom.
I was glad I could sleep in, as the "good morning delivery service" would deliver my breakfast -- a full-sized Korean-style meal -- to my door at around 8 a.m. After unpacking, I stepped outside to experience the resort's outdoor facilities.
As I visited before the official opening, some of those were still undergoing preparation. The family farm was due to open next year, a museum was due in 2023, and a Swiss-themed garden was on its way after that, with the facility expected to be completed around 2025.
Now, I wasn't sure what to make of an empty field being called a "sports zone," but I did enjoy the rest of the outdoor facilities. The walk along the trails was nice -- the resort was spread across almost a million square meters, so there was plenty of space to do just that -- there were several photo zones, and the deer at the deer farm were absolutely adorable, although I felt a little guilty for making them all run away. The arterial lake area was a bit underwhelming, but I heard at night it was decorated with all sorts of colorful lights that were supposed to make it spectacular.
There was a section of the woods where people could just take a nap on hammock, which was my personal favorite. I lay there, looking up at the blue skies, the wind gently tickling my face, with the fresh smell of the forest and without a care in the world.
While I didn't get a chance to explore it, there was also a forest of metasequoia trees where nighttime activities are planned for the future, such as checking out the constellations in the sky.
As I walked backed toward my cabin, the astonishing sight of the sunset sent me off, a spectacle I frankly would never have seen in the gigantic city of Seoul.
In celebration of its opening, the resort is offering a package deal until Dec. 31 that encompasses lodging, breakfast and dinner, all activities, an all-you-can-drink coupon for either Kloud draft beer or Americano coffee, a coupon for a bottle of wine, a late checkout option and a ticket to enter Seoraksan National Park.
For more information in Korean, English or Chinese, visit the homepage at http://www.kensingtonresort.co.kr.
(minsikyoon@heraldcorp.com)
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