Pictures below show the construction in the
Morton salt mine in Mentor, Ohio

Funding was provided by
the University of Michigan,
the University of California at Irvine,
and the U.S. Department of Energy

(These pictures can be clicked to enlarge)

Dosco machine that
dug the cavity

From bottom of finished cavity
looking out of tunnel to mine

Installing double layered
"Schlegel" liner


Scuba diver in finished tank ("pool")

For more pictures click here

and search for "Vander Velde"



In October, 1981 the double-walled liner was in place and we started filling the pool with ultra-pure water. At a depth of 11 feet the expected signals from cosmic ray muons looked good. However some small leaks developed and the water was emptied in order to make repairs on the liner.

In January of 1982 we started to refill, but at a depth of 13 feet a new large leak developed. We needed to rethink the problem of how to contain this much water. A scheme was devised to support the liner by pouring low-density concrete on the outside at the same rate the water was introduced on the inside. This was a slow process but it worked well and the full 70 foot depth was reached in July, 1982.

At that point all of the electronics and the data acquisition computers were in place. We started to record our first events.

Even though the detector was 1900 feet underground, cosmic ray muons went through at a rate of three per second. Since our design goal was to identify as few as one proton decay per year we needed to find one needle in a haystack of 100 million muons.

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