Two Thousand Feet Below Lake Erie
Larry "Harris" Taylor, Ph.D.
This is an
electronic reprint and expansion of an article that appeared in Skin Diver (September, 1989,
p. 80-81.116-119). This article is copyrighted (minus the PDK pool image
which belongs to National
Geographic ) and all rights retained by the author. This article is made available as
a service to the diving community by the author and may be distributed for any
non-commercial or Not-For-Profit use.
All rights reserved.
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Long ago and far away a star twenty times more massive
than our own sun went supernova. As this stellar mass exploded, it expelled
particles at the speed of light in all directions. Recently, neutrino detectors
in Japan and the United States simultaneously observed some of these sub-atomic
particles from that explosion. The observations from this supernova event, along
with continuing studies, are allowing astrophysicists to gain a new
understanding of the nature of the universe.
The United States neutrino detector is 2000 feet underground
in a salt mine near Fairport, Ohio (slightly east of Cleveland). The detector is
the collaborative effort of the Proton Decay Group of the University of
Michigan, the University of California (Irvine) and the Brookhaven National
Laboratory. The detector is 10,000 metric tons of highly purified water. In this
pool are 2048 extremely sensitive light-detecting photo multiplier tubes. These
tubes uniformly cover the walls, floor and ceiling of the totally enclosed pool
of ultra-pure water that measures approximately 80' x 70' x 70'.
A neutrino travels through water faster than light travels
through water. This gives rise to an optical shock wave (analogous to a sound
wave's sonic boom) that is perceived as a blue light, so-called Cerenkov
radiation. The array of photo multiplier tubes senses this light and a
sophisticated computer system quantifies the amount of light, its location
within the tank and the time that the light flashes occurred. Physicists then
interpret the meaning of the observed light patterns. The entire complex is
2,000 feet underground so that the mass of the earth shields the detector from
stray cosmic, as well as earth-born radiation.
Since the detector portion of the device is totally submerged,
the most cost effective way to inspect/maintain the device is with scuba divers.
Scientific divers of the University of Michigan supervised by Karl Luttrell do
the underwater inspection. Admission to the U of Michigan dive team requires
documentation of diving abilities, an interview with Dr. Lee Somers, Diving
Safety Officer, approval of the U of MI Diving Safety Board, i.e. be acceptable
to AAUS and OSHA as a scientific/working diver and passing an OSHA physical.
(This is not sport diving; the standards are more rigorous.)
Before entering the mine, the Bureau of Mines requires that
one attend a mine safety orientation. All persons entering the Morton-Thiokol
salt mine must wear steel reinforced boots, safety glasses and a hard hat with a
battery powered light. In addition, everyone carries a canister with a breathing
mouthpiece containing a catalyst to oxidize carbon monoxide to carbon dioxide.
(CO poisoning is a major life threat in any mine fire.) Lastly, everyone is
issued a pass and a brass numbered disc. (The purpose of the disc is to identify
a corpse that has been burned beyond recognition.) Safety is a primary concern of this
The dive team of three (supervisor, tender and diver) and
their guide enter the mine through a mine shaft elevator (just like an ice dive:
one way in, one way out) and take a five minute ride down to the 2000 foot
level. Leaving the elevator, one sees a large sign, "Welcome to the Fairport
Mine.". On the right are two large black holes big enough to drive trucks
through. These are mine drifts whose white salt crystal walls are blackened from
diesel fumes. (A drift is a horizontal tunnel; vertical tunnels are
Divers & guide ready to
Long, dark walk to PDK
As you walk away from the elevator into a quarter-mile corridor in total darkness, you are very conscious of the fact that all the light in the world is on your head. There is a peculiar odor of salt and diesel fumes in the air. You begin to question the wisdom of what you are doing and uncomfortable visions of diving through mine drifts begin to enter your mind. Fortunately, the mine drift is too large to induce claustrophobia. You worry about finding the elevator (your only way out) if your light fails and you find yourself counting steps and turns.
Ultimately, you arrive at a locked door set in a drift
wall. After unlocking the door, one enters a smaller dirt covered drift filled
with seemingly discarded bits of large odd shaped machinery. You approach
another door. Before going through this door, you walk through a scrubbing
machine that vacuums the dirt/salt from your shoes.
Walking through this set of double doors, especially the
first time, can best be described as simple relief. Suddenly, there is light and
sweet smelling air. It's like something from a James Bond movie. Here is a small
"lobby" where you change into clean clothes (dirt/salt contamination is kept to
a minimum in an effort to protect the sensitive electronics). Adjacent to the
"lobby" is a large mechanical room that contains machinery to purify the water
in the detector pool and to maintain the local environment. There is also a
machine shop for repairs and a scuba air compressor and cascade bank for the
dive team air cylinders. Also here are all of the controls and monitors that
provide the utilities for the entire facility. This room is really typical of
any basement mechanical room. However, the presence of emergency breathing
apparatus and a methane detector along the walls remind you that this is a
little deeper than the typical basement.
You walk past a water
to the walkway surrounding the PDK pool
Passing through the mechanical room, you enter the main
room of the facility -a combination electronic workbench, office space and
kitchen (complete with microwave, hot plates, refrigerator and trash compactor).
At the end of this long narrow room, the room splits into a T shape. One branch
of the T houses the rather impressive Vax 1170 computer system that monitors
acquisition and processing of data from each of the 2048 photo multiplier tubes
that comprise the proton decay detector. The other branch of the T is the
combination computer documentation storeroom/dive locker. Access to the detector
is from this point.
The detector pool is housed in a cavern about 150' x
130' x 110' that has been carved out of the salt and lined with heavy plastic.
As you enter the detector room, you are simply overwhelmed by the abundance of
cables and wires surrounding the covered pool. There are electrical power
cables, support wires, and fiber optic lines everywhere. Around the immense
cabled jungle there is a 4 foot wide green carpeted walkway. At the southeast
corner of this walkway, the dive team removes a couple of access panels and
prepares a 3' x 4' entry point. (At this point you are thankful that you will
not be diving through some dark mine tunnel.)
“Waveshifters” Detectors Surround Pool Diver entry point-the pool is 10 feet below
Now, you must help move a lot of dive gear from the storage
area to the entry point. However, first everything must be rinsed with very pure
water to avoid the diver's gear contaminating the pool water. Next, a hoist is
assembled which will lower the diver through the small entry point into the
As a well-dressed proton decay diver, you wear a Viking
dry suit (the rubberization on the outside makes it easy to decontaminate) with
dry gloves and hood. Ankle weights are worn inside the suit to prevent them from
contaminating the water. No lubricants (i.e. contaminants) are allowed on the
dry suit seals. Since the pool is maintained at a constant 70 oF, you
need only wear light polypropylene underwear. Next, you don a chest harness and
the umbilical/communication line is attached. After your fins are put on for
you, you sit down into a cradle and get into a set of twin 80's. Finally, the
Aquadyne DM-5 full-face mask is strapped on. This mask has two separate air
sources, each with its own first stage connected to a Benjamin crossover
manifold on the twin 80's. Lastly, your head is covered with a hard hat
containing a dive light.
just before PDK dive
Diver grabs X-bar for descent
After checking air and communication lines, you hang onto an
X-bar above your head and the hoist lifts you gently while your tender helps
position you over the entry point. (Here, your shoulders remind you how heavy
commercial dive gear can be.) You are slowly lowered seven feet down to the
water. Just before dropping below the surface, there is yet another gear check
before the hoist lowers you to a depth of 10 feet.
in the proton decay detector can only be described as bizarre. There is nothing
in sport diving that is even remotely comparable. You enter the water, at first
apprehensive because of the newness of the environment and the commercial dive
gear. As you submerge, there is a great sense of relief as the water removes the
weight of the twin 80's and the dive mask/helmet. With no regulator in your
mouth there is a small sense of claustrophobia as you adjust to breathing within
a hard shell. It takes more than a few moments to get comfortable as you can
feel your pulse slowing from the initial entry. After a while you do manage to
convince yourself that it is possible to breathe without a regulator in your
mouth. While sitting on the cradle you verify that you can find and use the
secondary air and mask clearing knobs. After approval from Karl, the dive
supervisor, you roll backwards out of the hoist chair and slowly sink towards
You look around, absolutely amazed at
a setting that makes the interior of Star Wars' Death Star seem pale by
comparison. The pictures of the pool in Astronomy magazine (Feb. 1988), as well
as the pre-dive map briefing were not enough to describe the visual impact of
being inside this device "Awesome" is just too insufficient a concept! Since you
are weightless and nowhere wet, you feel more like an astronaut than a diver.
(You remember childhood dreams of being a moon explorer.) The
water is infinitely clear. (A continuing filtration process removes everything
larger than 0.5 micron.) You feel as if you could touch everything, but the
sheer magnitude of this device tells your rational brain that that is simply not
possible. You ask for more umbilical cord (Jim, your tender, instantly responds)
and you begin your inspection tour.
You force yourself to concentrate on the purpose of the dive. You begin to focus on individual columns of detectors as you look for evidence of cable stress or broken support wires, weights that have dropped off the bottom of their housings and tubes at irrational angles that would signify a broken support beam. You are to look for pool liner leaks and check the integrity of existing patches. After all, you are here to work, not to play. (Here, the diver is merely an underwater janitor/handyman who supports the work of others.) You scan the bottom looking for tools and other objects that may have fallen from above. (Hoping, of course, that you don't find anything because you are really not sure you can squeeze between the individual photo multiplier assemblies without hanging up your umbilical line.) You treat the detector assemblies on the bottom as if they were fragile living things, not wanting your kick to cause any damage.
As you swim about 2-6 feet above the top of the floor detector tubes, you roll to your right to look up along the wall and become slightly disoriented. Everywhere, it is the same! You are in a totally black void, punctuated by a few thousand large dark eyes (photo multiplier tubes) surrounded by their 2' square bluish "waveshifters". There is no feeling of distance. Tour eyes search, but can find nothing to fix orientation. The water is too clear. The pool is too large. Your mind begins to whirl and lose rationality. There is a sense of insignificance in the infinity of the cosmos. You are truly alone. You are warm, weightless and many of your senses are deprived. Yet, your mind seems so alive and so totally unconfined as it whirls away from reality! (The movie "Altered States" takes on a new meaning for you.)
Diver moves replacement
Diver patches pool retaining wall
Suddenly, there is a spray of water coming at you and
the air tastes wet. Your eyes slowly focus on the glass plate in front of you,
seeing water rising rapidly above your eyes. You realize that turning your head
has broken a seal. In that tank that probes the infinite, you are once again
reminded of the finiteness of human life. First, you get scared! A lifetime
later, you remember a knob that clears your faceplate. You find it and blow the
water out of the helmet and thus stay alive. Relief is spelled, "No water in
YOUR helmet!" You now realize that the mask could have been a little tighter
(next time it will be!), but you have no control over that now. You remember
once reading that commercial diving is demanding physical labor conducted in
environments hostile to life. That passage takes on a new reality.
You now find that there is a continual leakage of water
into your mask. You feel apprehension.
You try to adjust the mask and find that the only way to keep the mask
dry is with a continual free flow. Losing air bothers you, but you remember that
you are wearing a lot of air. You also know that even if you should forget to
monitor, Karl will ask you for the air pressure via the communicator. Since you
have previously been a tender and know who is on the other end of the line, you
feel confident to continue. The free flow bubbling noise is bothersome, but it
does allow you your first priority, breathing.
You see a power cable that has drifted down and covers a section of one of the photo multiplier tubes. You remove the cable and place it behind that unit's assembly. It is a simple task, but somehow it brings satisfaction, a feeling of having done "a good job." You move on. You find two arrays twisted towards each other, out of plane with the rest of the detectors on that wall. You try to free them and cannot. The ever-present Karl suggests that you follow the column to top of the pool and try to ascertain the cause of the problem. The ascent seems to take forever. (The long ascent reminds you that you have been swimming near the bottom of a 70 foot deep pool- the incredible clarity of the pool makes all dive distance/time estimates grossly inaccurate. Diving in Michigan waters (6-12 foot visibility) does not prepare you to assess accurately seemingly infinite visibility.) On your ascent you can find nothing to indicate the nature of the problem. You count columns from a corner so that surface personnel can examine this part of the detector. You continue to swim and inspect. You find an old liner patch and it appears intact. You move on.
As you look around, with no compass, you again lose
orientation. North becomes East or is that West? You don't know. You ask Karl
and he tells you where you are. (Your pre-dive briefing had warned you of the
disorientation problem; it is quite common in this pool, particularly on the
first dive. But like most things in life, it must be experienced to be truly
appreciated.) Later, the presence of the light from the entry hole tells you
that your bottom inspection lap is finished and now you ascend about halfway up
the wall to begin another inspection lap.
On this lap, you must be particularly conscious of your
umbilical cord. In the center of the detector ceiling hangs what looks like an
old-fashioned light fixture- a bare incandescent bulb hanging from a power cord.
In reality it is the end of a fiber optic laser driven light source used to
equally disperse light in all directions. The physicists use this to calibrate
all of the photo multiplier tubes. As a diver, your concern is not to tangle
your umbilical cord and thus do damage.
This lap seems easier. The bothersome escape of air
appears to have slowed. You begin to pick out subtleties of the pool that make
orientation easier. It appears as if your perception is increasing as you find
yourself seeing more and more of the pool. You note what appears to be a very
large distortion in a ceiling support beam. You ascend near the farthest corner
(that would be the NW corner) from the entry point to examine the structure. You
realize that all of the ceiling beams are similarly distorted. In reality, there
is only a slight bow due to the mass of the detectors on the support beams.
However, the magnitude of this distortion appears to be much larger because of
the refraction of the water. Again, the extreme clarity of the water has been
playing games with your perceptions.
Near the ceiling of that corner you turn around and look back
toward the entry hole to check your umbilical. At this moment in time, the free
flow of air stops. The sound of silence is so peaceful and the word tranquility
comes to mind. The sight explodes into your permanent memory. All of the more
than 2000 dark eyes of the detector seem visible. Their surrounding blue hued
"waveshifters" add an eerie glow within the black void. Your white umbilical
makes a gentle arc underneath the small laser ball and disappears into the light
of the access hole. The only light in the pool is that coming through the entry
point plus that from the small light on your helmet. Yet, this seems sufficient
to illuminate the entire pool. (You question how much of what you see is real
and how much is imagination?) You have often told people of a "diver's high" - a
sense of oneness of self and environment, an inner peace, that comes from
playing in Planet Ocean. Your eyes, hypnotized, follow the curve of the
umbilical to the light of the entry point and stare transfixed at the
brightness. You sense a "diver's high" of a magnitude beyond all previous
experience. It overwhelms! Your mind races at the speed of light up the
umbilical into the light and out beyond self, the pool and the universe. The
moment is fleeting, but the ecstasy is very real. Almost embarrassed, you again
focus on the nearest phototube and resume your job, inspecting. You move
You end the dive by sitting on the hoist cradle at a depth of
10 feet for a mandatory four-minute decompression safety stop. During that time
you strain your head time and time again to gaze upon that incredible feat of
human engineering that is the proton decay detector. This dive, like most dives,
has been too short. As you leave the water, there is a certain relief (nothing
broken was found, thus you were spared hard physically demanding labor in
awkward positions) mixed with a degree of sadness. You grab the X-bar over your
head and the hoist lifts you slowly to the surface. The weight of the helmet and
the twin 80's signals the end of a truly unique dive.
inspection swim within the PDK pool (National Geographic
After surfacing, you are helped out of your diving gear. The
emotions of the just completed dive become secondary to the task at hand. All
the gear must be cleaned, moved back to the dive locker and stored. The air
cylinders must be filled and stored. Reports must be written. Finally, all
working is done.
Sadly, you must now leave the detector facility. You put on
your mine attire and take that long, long guided walk in darkness to the
elevator. As you wait for the elevator to descend, Jim, your tender on this
dive, gives you a hunk of blackened salt crystal. Somehow, that is a most
perfect memento. It seems like the elevator takes forever to reach the surface.
It has been just a typical workday in the sub-sub-basement. The air on the
surface smells so very sweet.
The next scheduled maintenance dive is in
three weeks. You will return.
Surface Photos: Larry “Harris” Taylor
pool: National Geographic (May
1988, p. 643), Joe Stancampiano & Karl Luttrell
Further Reading On The PDK Experiment
R. Kirshner, Supernova Death Of A Star, National Geographic, May.1988, 618-647.
J.M. LoSecco, F. Reines, & D. Sinclair, The Search For Proton Decay, Scientific American, June, 1985, 54-62.
J. Monczunski, Star Dust Memories, Notre Dame Magazine, Winter, 1989, 44-48.
R. Talcott, Insight Into Star Death, Astronomy, February, 1988, 6-23.
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About The Author:
Larry "Harris" Taylor, Ph.D. is a biochemist and Diving Safety Coordinator at the University of Michigan. He has authored more than 100 scuba related articles. His personal dive library (See Alert Diver, Mar/Apr, 1997, p. 54) is considered one of the best recreational sources of information In North America.
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