From: Nathan Rodning <rodning@relay.phys.ualberta.ca>
Date: Wed, 06 Jun 2001 21:57:23 -0600
To: e614chambers@relay.phys.ualberta.ca
Subject: [Fwd: Report on testing modules in helium]
--
Nathan Rodning
Professor of Physics
(780) 492-3518 / Fax: (780) 492-0714
http://www.thehungersite.com/
An embedded message follows:
From: Peter Kitching <trpk@sitka.triumf.ca>
Date: Wed, 6 Jun 2001 10:50:18 -0700
To: nate rodning <rodning@relay.phys.ualberta.ca>, robert henderson <rhend@triumf.ca>, fasz@triumf.ca, drgill@triumf.ca
Subject: Report on testing modules in helium
I have to go to BNL tomorrow for 2 weeks, so I have written up what I have
done so far. I can continue when I get back, or someone else could take
over. The student you assigned never showed up and I had no time to seek
him out. However Wayne is pretty familiar with the procedures.~
Progress Report on Helium Tests for E614 Detectors
P.Kitching June 5 2001
UV Modules
Used blank (dummy preamps) throughout the UV module work,except for preamp
#'s 2019,2070, which may therefore have been damaged
during these tests by sparking etc.
Tested HV leads in pure Helium without the chamber - leads good up to 4000 volts
Put UV chambers into box. Flowed isobutane through chambers, He/Nitrogen mix in box
Volume of He box = 136 litres - flush 0f 5 x 136 = 680 litres considered sufficient.
Isobutane in chamber had positive pressure of 122mT with respect to Helium in box.
Helium in box has positive pressure of 30 mT with respect to outside air.
Tests with Module 259
Measurement He-flow N2-flow %N2 HV(discharges) HV(trips)
L/min L/min
#1 0.0 1.0 0.0 1800 1900
#2 .041 1.21 3.03 >2500 >2500
#3 .054 4.99 1.07 2300 2400
#4 .105 4.9 2.06 >2500 >2500
#5 .075 4.9 1.48 2400 2500
#6 .025 4.9 0.5 1900 2000
When discharges occurred, sparks were seen, always from middle to bottom, never to top.
In between taking measurements #1 and #2 we removed 2-3mm of copper around
edge of bottom plate, left side. This seemed to make no discernible difference
Keeping % N2 fixed at 1.48 %, the remaining modules (Numbers 254,264,257,254,258) were tested and showed no
evidence of discharges or sparking at 2300 volts. No trips occurred when left at 2300 volts for more than 1 hour.
PC Module
It is expected that the PC modules will run at voltages several hundred volts higher than the UV and dense stack
modules, because of different wire spacing etc.
Module # 267 was tested first in air with a 1mC Fe55 source and pure isobutane gas flowing through the chamber.
The preamp voltage was +4 volts As a function of voltage, the top right module gave the following pulse heights
(averaged over 100 pulses)
HV Average pulse height
1800 volts 3.5 mV
1900 6
2000 11
2100 22
2200 52
2300 100
2400 180
2500 250 - starting to saturate preamp
2600 290
2700 320 - total saturation for 380 mv pulses
The HV stayed on at 2500 volts for > 10 minutes
The module was next tested in helium/Nitrogen with 2.5 % Nitrogen content
The module contains 2 U-planes (which we label Top-L, Bottom-L) and two V_planes (labeled Top-R, Bottom-R).
With both U-planes at voltage and/or both V-planes at voltage, there was no evidence of sparking or discharge
at 2500 volts. However this was not the case when we tried 1 U-plane (or 1 V-plane) at voltage with the other at
ground. (This circumstance might arise, for instance, if a fault developed in a single plane and it was
desired to continue operating the other.) In this mode, frequent discharges occurred with a voltage of 2400 and
it was necessary to lower the voltage to 2300 to get rid of them. Increasing the Nitrogen content to 3% lowered
the frequency of discharges at 2400 to 1 every few minutes, but did not eliminate them.
Lack of time prevented further investigation, but if we want to have discharge-free operation at 2500 in this
mode (1 U or V-plane on with the second U or V-plane off), it may be necessary to go to considerably higher
nitrogen content.
Future work
1.Establish N2 content needed to operate PC at 2500 volts with 1-U(V)plane on, other-U(V)plane off .
2.Open up PC module to look for any visible evidence of damage caused by sparking
3.Establish actual working point for PC module
4.Carry out Monte-Carlo calculations to investigate effect of Nitrogen percentage on muon energy loss and
multiple scattering
5.Check out Dense Stack module in Helium box
NB. It was necessary to carry out these PC tests with preamps in place,
since there were not enough blank spares.
Although no preamp power was present when sparking occurred, it is possible that the following preamps were
damaged by the sparks:
2007,2026,2001,2005,2093,2091,2090,2086,2009,2024,2022,2008
These units together with 2067 and 2127, should be checked before
installing them in the detector
--
Department of Physics Office: C207 Centre for Subatomic Research
University of Alberta Voice : (403) 492-4170 FAX : (403) 492 3408
Edmonton, Canada T6G 2N5 email : Peter.Kitching@Phys.UAlberta.CA
WWW: http://inuit.phys.ualberta.ca/~trpk/trpk.html
TRIUMF Office: 201 Trailer Ff
4004, Wesbrook Mall Voice : (604) 221 3210 : FAX (604) 222 7309
Vancouver,BC,Canada V6T 2A3 email : trpk@sitka.triumf.ca
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[Fwd: Report on testing modules in helium] / Nathan Rodning
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