You will be presented with the full text of a science research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
lsw experiments search for wisps via the process @xmath1  @xcite . for a photon - counting detection scheme , the signal rate , @xmath2 ,
is given by @xmath3 where @xmath4 is the rate of photons fed into the experiment , @xmath5 , @xmath6 the efficiency of the detector and @xmath7 the probability for photon - wisp and wisp - photon conversion , respectively , which are both proportional to the square of the photon - wisp coupling , @xmath8 .
hence , the sensitivity on the coupling , @xmath9 , i.e.  the expected upper limit on @xmath8 for the case that @xmath10 is realized in nature , scales with the detector parameters as @xmath11 with @xmath12 the count - rate sensitivity and @xmath6 the quantum efficiency of the detector .
the count rate sensitivity is typically roughly proportional to the square root of the dark count rate , @xmath13 .
hence , the sensitivity can be improved ( i.e.  lowered ) by decreasing the dark count rate or increasing the quantum efficiency .    to compare different detectors ,
the figure of merit @xmath14 , is used .
thus , larger values of @xmath15 identify better detectors .
the count rate sensitivity is taken to be the average upper limit of unified confidence intervals and is estimated using toy monte carlo simulations  @xcite .
early lsw experiments used pmts for photo - detection  @xcite .
recent lsw experiments used ccds and lasers in the visible spectrum  @xcite .
future lsw experiments will use nir lasers  @xcite because optical elements are known to withstand high powers at these wavelengths . at nir wavelengths ,
silicon based ccds have a much reduced quantum efficiency compared to the visible spectrum .
therefore , other devices for photo - detection are sought .
these detectors should have a quantum efficiency that is similar to the quantum efficiency of ccds in the optical and a dark count rate below that of ccds .
additionally , it is desirable that these detectors can time - resolve single photons ( spd ) . a review of spds is given in ref .
@xcite .    in sections  [ seggern :
sec : ccd ] to [ seggern : sec : pmt ] ( electron - multiplying ) ccds , qi spds from ref .
@xcite and pmts are discussed , respectively , and the figures of merit are calculated .
the results are compared in section  [ seggern : sec : concl ] . to calculate the count rate sensitivity , @xmath12 , a confidence level of @xmath16 is assumed .
ccds are currently the prime choice for scientific visual imaging with a wide range of devices to choose from .
the imaging area of ccds is segmented into columns each consisting of a series of mis capacitors . during data taking
, these capacitors are biased into deep - depletion .
incident photons are absorbed in the semiconductor material and produce free charges which are stored by the capacitors .
these charges are integrated during an exposure . at the end of an exposure ,
the collected charges are transported to a read - out structure and digitized .
hence , a ccd can not resolve single photons .
in addition to the charges generated by incident photons , thermally generated free charges are produced and stored as well .
these constitute the dark counts , which contributes to the overall noise .
the process of read - out and digitization adds a second source of noise .
hence , the total noise is given by @xmath17 where @xmath18 is the read - out noise , @xmath19 the exposure time and @xmath20 the production rate of dark counts .
o0.37     the lsw experiment alps at desy used a commercially available , low noise ccd camera with @xmath21 sized pixels ( pixis ccd )  @xcite .
a dark count rate below @xmath22 was achieved by liquid cooling of the ccd chip and the camera was equipped with low - noise read - out electronics ( @xmath23 )  @xcite .
thus , the read - out noise is the larger contribution to the total noise for exposures shorter than @xmath24 .
if the signal can be focussed to a single pixel , a data set of 20 one hour exposures yields a figure of merit @xmath25 for a quantum efficiency of @xmath26 which is typical in the visible spectrum .
electron multiplying ccds ( emccds ) amplify the charge signal before read - out in an avalanche multiplication register  @xcite .
this allows to neglect the read - out noise and , hence , short exposure times are possible .
but at the same time , the quantum efficiency is effectively reduced by a factor of two due to the additional noise from the multiplication process  @xcite .
the original quantum efficiency , i.e.  without charge multiplication in an avalanche register , can be recovered by interpreting the read - out values in a binary fashion , i.e.  photon detected yes / no  @xcite , where a photon is counted if the digitized signal is above a threshold , @xmath27 .
hence , the analysis can be reduced to that of a counting experiment .
if contamination by noise and loss of signal due to the threshold can be neglected , this yields @xmath28 assuming the same values as above ( @xmath29 , @xmath30 and @xmath31 of data ) .    for nir wavelengths ,
the pixis ccd was found to have a reduced quantum efficiency of @xmath32  @xcite .
the figure of merit is reduced accordingly for the pixis ccd ( @xmath33 ) and emccd ( @xmath34 ) .
ingaas based ccds exist , which have a much smaller band gap than silicon and , therefore , a much higher quantum efficiency ( @xmath35 ) than the silicon - based pixis ccd .
but these devices also have a dark count rate , which is six orders of magnitude above that of the pixis ccd  @xcite .
therefore , these specialized ccds are of no help when improving the detector part of lsw experiments .
to maintain a low dark count rate and achieve a high quantum efficiency at nir wavelengths at the same time , sensors operated at cryogenic temperatures can be used .
most of the devices listed in ref .
@xcite ( cryogenic or not ) have however dark count rates much above that of the pixis ccd
. only transition edge sensors ( tes ) were found to have low dark count rates below that of the pixis ccd  @xcite .
tes are bolometric sensors which are operated at @xmath36 . combined with a proper coating
, high quantum efficiencies of @xmath16 can be reached  @xcite .
the dark count rate and quantum efficiency expected for alps - ii ( @xmath37 @xmath38 ) are assumed here as benchmark parameters  @xcite .
the corresponding figure of merit for 20 hours of data is @xmath39 .
the sensitive area of tes detectors and the pixels of a ccd are both of order @xmath40 .
if the signal can not be focussed on such a small area , the pixels of a ccd can be binned .
but , as discussed above , the integrated dark count rate increases at the same rate as the area of interest . accordingly , the figure of merit and the sensitivity on the coupling may worsen significantly . in this case ,
pmts are a very good alternative although they have a limited quantum efficiency ( @xmath41 ) and a limited spectral range ( @xmath42 )  @xcite .
the sensitive area of a    o0pt    [ cols="<,^,^,^",options="header " , ]     pmt consists of a photo - sensitive material with a low work function .
incident photons produce free electrons which are directed to an electron multiplier by a focussing electrode .
the high gain of the electron multiplier allows single photon detection . cooling the sensitive area reduces the dark count rate .
for example , the ships helioscope uses a pmt with an active area of @xmath43 , which has a peak quantum efficiency of @xmath44 and a dark count rate of @xmath45 when cooled to @xmath46  @xcite .
this corresponds to @xmath47 .
surprisingly , of all spds used in qi experiments , only tes detectors have a sufficiently low dark count rate to improve significantly over conventional ccds
. the figures of merit of the detectors mentioned in the above sections are summarized in tab .
[ seggern : tab : comparison ] . of the presented alternatives ,
a tes is the best option . especially in the nir ,
a tes is superior to a ccd because its quantum efficiency does not deteriorate for these wavelengths . in the visible regime ,
ccds remain a viable option when only few resources are available for detector development . from the values listed in tab .
[ seggern : tab : comparison ] , it seems that pmts are the worst option .
their figure of merit is two orders of magnitude below that of ccds ( visible ) , which is caused mainly by their high dark count rate .
however , considering their large sensitive area , pmts are the detector of choice if the signal can not be focussed very well .
these findings are schematically summarized in fig .
[ seggern : fig : findings ] .
the study of the pixis ccd was kindly supported by g.  wiedemann ( hamburger sternwarte ) .
99 j.  redondo and a.  ringwald , contemp .
phys .   * 52 * , 211 ( 2011 ) [ arxiv:1011.3741 [ hep - ph ] ] .
g.  ruoso , r.  cameron , g.  cantatore , a.  c.  melissinos , y.  semertzidis , h.  j.  halama , d.  m.  lazarus and a.  g.  prodell _ et al .
_ , z.  phys .
c * 56 * , 505 ( 1992 ) .
k.  ehret , m.  frede , s.  ghazaryan , m.  hildebrandt , e .- a .
knabbe , d.  kracht , a.  lindner and j.  list _ et al .
_ , phys .
b * 689 * , 149 ( 2010 ) [ arxiv:1004.1313 [ hep - ex ] ] .
p.  pugnat _ et al .
_ [ osqar collaboration ] , arxiv:1306.0443 [ hep - ex ] . + m.  sulc [ osqar collaboration ] , _ contribution to this workshop_. r.  bhre , b.  dbrich , j.  dreyling - eschweiler , s.  ghazaryan , r.  hodajerdi , d.  horns , f.  januschek and e.  -a .
knabbe _ et al . _ , jinst * 8 * , t09001 ( 2013 ) [ arxiv:1302.5647 [ physics.ins-det ] ] .
+ b.  dbrich [ for the alps - ii collaboration ] , _ contribution to this workshop _ [ arxiv:1309.3965 [ physics.ins-det ] ] .
m.  d.  eisaman , j.  fan , a.  migdall and s.  v.  polyakov , rev .
instrum .  * 82 * , 7 ( 2011 ) [ doi:10.1063/1.3610677 ] .
g.  j.  feldman and r.  d.  cousins , phys .
d * 57 * , 3873 ( 1998 ) [ physics/9711021 [ physics.data-an ] ] .
princeton instruments , http://www.princetoninstruments.com/uploads/princeton/documents/datasheets/pixis/princeton_instruments_pixis_1024_excelon_rev_n3_8.21.2012.pdf j.  e.  v.  seggern , phd thesis , in preparation .
s.  madan , b.  bhaumik and j.  vasi , ieee ted * 30 * , 694 ( 1983 ) [ doi:10.1109/t - ed.1983.21191 ] . m.  stanford and b.  hadwen , ieee ted * 50 * 1227 ( 2003 ) [ doi:10.1109/ted.2003.813462 ] . o.  daigle , c.  carignan , j .- l .
gach , c.  guillaume s.  lessard c .- a .
fortin , s.  blais - ouellette , publ .
* 121 * 866 ( 2009 ) .
princeton instruments , http://www.princetoninstruments.com/uploads/princeton/documents/technotes/ingaas_tech_note_princeton_instrumentsrevb0.pdf g.  cantatore , _ contribution to this workshop_. + j.  dreyling - eschweiler and d.  horns , _ contribution to this workshop _ , [ arxiv:1309.5024 [ physics.ins-det ] ] .
a.  lita , a.  miller , and s.  nam , opt .
express * 16 * 3032 ( 2008 ) .
hamamatsu , `` photomultiplier tubes '' , edition 3a ( 2007 ) .
et enterprises , 9215b , http://my.et-enterprises.com/pdf/9215b.pdf .
m.  schwarz , _ contribution to this workshop_.
laboratory based searches for weakly - interacting slim particles ( wisps ) of the light - shining - through - a - wall type ( lsw ) use visible or near - infrared ( nir ) laser light . 
 low - noise and highly efficient detectors are necessary to improve over previous experiments . 
 these requirements overlap with the requirements for single - photon detectors ( spds ) for quantum information ( qi ) experiments . in this contribution , the sensitivity of several qi spds is compared to photo - multiplier tubes ( pmts ) and imaging charge - coupled devices ( ccds ) . it is found that only transition edge sensors ( tess ) are viable alternatives to ccds if the signal can be focussed to a few @xmath0 .