Two Thousand Feet Below Lake Erie

by

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 mining operation.

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 shafts.)

  

 Divers & guide ready to enter mine                      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 filtration plant                        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 detector pool.

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.

 

 Diver 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.

Diving 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 the bottom. 

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 beam                                       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 on. 

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. 

 Diver on inspection swim within the PDK pool (National Geographic Image) 

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.  

Photo Credits:  

 Surface Photos: Larry “Harris” Taylor

Diver Photos: Karl Luttrel

PDK 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. 

  Copyright 2001-2004 by Larry "Harris" Taylor

All rights reserved.

Use of these articles for personal or organizational profit is specifically denied.

These articles may be used for not-for-profit diving education