chiho wang atlas trt istanbul workshop duke university may, 2001 1 module gas leak chiho wang duke...
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Chiho Wang ATLAS TRT Istanbul WorkshopDuke University May, 2001
Title: (AIATL_LOGO2.eps)Creator: Adobe Illustrator(r) 6.0CreationDate: (4/3/97) (11:26 AM)
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Module Gas Leak
Chiho Wang
Duke University
Chiho Wang ATLAS TRT Istanbul WorkshopDuke University May, 2001
Title: (AIATL_LOGO2.eps)Creator: Adobe Illustrator(r) 6.0CreationDate: (4/3/97) (11:26 AM)
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Gas leak requirements
Operating condition: ionization gas at 1 atm with 70% Xe purging gas at 1 atm with 100% CO2 allow 10 volume / year of Xe loss
Measurement simulates Xe loss with: Same gas (or different gases assuming both
are ideal gas) in each gas volume Slight over pressure of ionization gas
volume monitoring pressure change over time
(indifference of composition change)
Present requirement at Duke/IU:< 0.1 mBar/Bar/minute
Chiho Wang ATLAS TRT Istanbul WorkshopDuke University May, 2001
Title: (AIATL_LOGO2.eps)Creator: Adobe Illustrator(r) 6.0CreationDate: (4/3/97) (11:26 AM)
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Module leak test setup
Chiho Wang ATLAS TRT Istanbul WorkshopDuke University May, 2001
Title: (AIATL_LOGO2.eps)Creator: Adobe Illustrator(r) 6.0CreationDate: (4/3/97) (11:26 AM)
4
Module leak test setup
Chiho Wang ATLAS TRT Istanbul WorkshopDuke University May, 2001
Title: (AIATL_LOGO2.eps)Creator: Adobe Illustrator(r) 6.0CreationDate: (4/3/97) (11:26 AM)
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Leak Measurement
Measurement procedure: pressurize/equalize module and
reference tank pressure to ~ 20mB above room atm
isolate module from reference tank monitor pressure change between
reference tank and module over time
Leak rate is calculated = dP/P/T dP = pressure difference
Tank - Module (mBar) P = module pressure vs room (Bar) T = elapsed time (minute)
Chiho Wang ATLAS TRT Istanbul WorkshopDuke University May, 2001
Title: (AIATL_LOGO2.eps)Creator: Adobe Illustrator(r) 6.0CreationDate: (4/3/97) (11:26 AM)
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Module 2.07 mechanical
~42 hrs, Leak rate = -0.007 mB/B/min
Chiho Wang ATLAS TRT Istanbul WorkshopDuke University May, 2001
Title: (AIATL_LOGO2.eps)Creator: Adobe Illustrator(r) 6.0CreationDate: (4/3/97) (11:26 AM)
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Measurement Accuracy
Affecting factors: Temperature may swing 2ºC during
measurement. The measurement assumes module and
reference tank responds to temperature change equally.
Suppose there’s a 10% mismatch in their responses, the error in dP measurement would be
~ 10% * 2/300*1013 ~ 0.68 mB To wash out temperature effect with time to
0.05mB/B/min would be:
0.05 = 0.68(mB) / 0.02(Bar) / T (minute)
T ~ 675 minutes = 11.3 hours Room pressure may swing 10s of mBar and
affect module P used in calculating leak rate This, however, can be corrected by taking
average P or integrating P over time.
Chiho Wang ATLAS TRT Istanbul WorkshopDuke University May, 2001
Title: (AIATL_LOGO2.eps)Creator: Adobe Illustrator(r) 6.0CreationDate: (4/3/97) (11:26 AM)
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Module leak measurements
* measured at mechanical completion
Module Leak Rate module stage2.01 -0.017 done*2.02 -0.015 done*2.03 -0.080 done2.04 0.080 done2.05 -0.004 done2.06 0.024 mechanical2.07 -0.007 mechanical
Chiho Wang ATLAS TRT Istanbul WorkshopDuke University May, 2001
Title: (AIATL_LOGO2.eps)Creator: Adobe Illustrator(r) 6.0CreationDate: (4/3/97) (11:26 AM)
9
Summary
Modules built are leak tight Continue to improve leak
measurement and understand the measurement error Added barometer to obtain absolute
module pressure Try to understand temperature
dependence of dP between module and tank
Try different method of leak rate calculation, e.g. using P/T = nR/V without using reference tank.
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