1. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 1 Xe-CO 2 Stability Chiho Wang Duke University

2. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 2 Setup  X-ray aperture limits active region ~ 6-7cm on straw.  0.002” Cu foil reduced X-ray intensity to ~0.1uA/cm  Only 1 pair of ASD sockets are active to draw current.  Scan along straw at 8cm intervals.  At each location, raise HV from 1550V to 1750V at 25V step, 20 sec interval.  Record current & # of Trips.

3. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 3 Module 2.09 ASD #1

4. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 4 Module 2.09 ASD #2

5. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 5 Module 2.09, ASD #3

6. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 6 Module 2.09, ASD #4

7. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 7 Module 2.09, ASD #5

8. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 8 Module 2.09, ASD #6

9. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 9 Module 2.09, ASD #10

10. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 10 Module 2.09, ASD #11

11. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 11 Module 2.09, ASD #15

12. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 12 Module 2.09, ASD #16

13. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 13 Module 2.09, ASD #21

14. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 14 Module 2.09, ASD #22

15. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 15 Module 2.09, ASD #27

16. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 16 Module 2.09, ASD #28

17. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 17 Module 2.09, ASD #30

18. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 18 Module 2.09, ASD #31

19. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 19 Module 2.09, ASD #32

20. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 20 Module 2.09, ASD #33

21. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 21 Observation  Most ASD HV trip at mid wire support location.  Some ASD HV trip at end wire support.  After several hours of “burning” at the wire support, it gets more stable and less likely to trip u ASD 28-33 were scanned many times with Ar-CO2 before taking Xe data. They are obviously more stable. u In the case of Ar-CO2, X-ray also triggers a self-sustained current draw that lasts for several hours even after X-ray is turned off. This contributes to an increase of current draw when X-ray passes through mid wire support. This current, however, also dies out after burning.

22. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 22 Module 2.09, ASD 30, Ar-CO2

23. Chiho Wang ATLAS TRT Duke University Hampton, May. 2002 23 Summary  Xe-CO2 is stable at 1750V with 0.3uA/cm local rate  Mid wire support tends to be unstable in the beginning of the chamber operation, but can be improved with “burning”.  Some end wire supports also show the same instability but not as often as mid wire support.