The Igloo Page

This page is meant to document studies made of the performance of the igloos. A stand-alone QVT monitoring system was set up by Peter Nemethy and Bob Ellsworth in December, 1996. Several logbook entries have also been made regarding these studies.

There are seven igloos currently installed in the pond. They lie in a row running west to east along the northern edge of the floor of the pond. This places them in patches 10 and 15. They are numbered such that igloo 1 lies in the northwest corner. Igloos 1 and 7 have two sets of scintillator "paddle" detectors installed with them; there is one set of paddles beneath each igloo, and one set of paddles above each.

The primary task thus far has been to determine the number of photoelectrons (PEs) seen by the igloo's phototube (PMT) when a muon passes through the igloo. To do this we used ADC output from igloo 1's tube. We looked at the spectrum of the tube while triggering on muons, with the paddles, to find the muon-peak. We then needed to find the 1-PE peak. We tried two methods for this. First I amplified the signal and took a muon peak spectrum. This stretched out the pedestal enough to see a small "shoulder" very near the pedestal, which I interpreted as one PE. The other, more reliable, method was to use the surrounding patch as the trigger, and look at the spectrum of the tube. We worked to reduce the noise in the signal, and using the patch trigger we found the 1-PE peak more easily.

In late January and early February I attempted to amplify the muon peak signal to find one PE in igloo 1. I was able to do this and estimated 30 PEs in the muon peak. I presented some results at the collaboration meeting in Irvine.

During the week of March 17-22, Peter Nemethy and I worked to determine the number of photoelectons (PE's) per muon in igloo 1. Our efforts to reduce signal noise are detailed in the logbbok. (March 22, 1997) We were able to find the one-PE peak and use this to determine that igloo 1 sees an average of 30 PE's per through-going muon, thus confirming my earlier, and rougher, estimate. I presented this result at the Milagro Monday Morning Meeting (MMMM) on 3/30/97.