Gas Studies with H8 Water Contamination and Series Effect Flow rate effects Changes in CO2 percentage Air Contamination (2001 measurements)

Water contamination (P. Bagnaia, C. Bini, F. Cerutti, S. Fiore, L.P., E. Solfaroli, ) Only 2 “good points” : 2700 ppm, 500 ppm Data Analized only with spectra Tmax variations up to 200 ns  tmax/ (100 ppm H2O) = 6-7 ns Same dependance found in the Series Effect, (assuming water to be the cause) Max effect +-7 ns (BILPV) Agreement with Garfield calculation To be completed: Variation of the RT-relations vs H2O To be done: Variation of the Resolution Variation of the efficiency.

Water 2700, 500 ppm 500 ppm 2700 ppm Time ns Space mm Tracking with BML and BOL and extrapolating to BIL

Difference RT ( ) Difference mm Time ns RT difference at equal times A better comparison should be at equal space …… Next step

Garfield calculation on H2O Drift time at 14 mm as a function of the H2O content 6-7 ns/100 ppm

Alignment From the difference of the right and left branch of the rt relation we get the twice the displacement of multilayer w.r.t. the other chambers ML position mm

Gas Series Effect BIL PV RO side

Direct water measurement on BIL RM and BILPV & Bundle 3 Bar The Water contamination decreases after flushing nitrogen in the FC It seems that the water gets in from O-rings/end plugs/ jumpers. Measurement on Bundle to be redone next week Bundle

Flow rate effects Example of time dependence (b) BOL6/1 (l=1) +4 h +22 h +35 h +77 h

Flow dependance  (T 1 -T 3 ) 20 l/h after 77 h 33 l/h 63 l/h

Chamber with closed Gas Maximum drift time increases with time (as expected if due to an increase of water)

Dependance on CO2 % Data taken with 6%, 6.5%, 7.5%, 8% of CO2 Only BILRM and BIL PV with “new gas” To be completed : Study the differences in RT-relation To be done : Effects on the Resolution Effects on the efficiency

CO2 results Tmax for all the BILs tubes 71 ns/(%CO2) Tmax vs %CO2 Data Taken at high Flow nl/h (Atlas Flow 60 NL/h)

RT-relation studies with different CO2 % Tracking using BML and BOL enable to directly measure the RT-relation on BIL. Using this technique it is possible to measure the differences on the RT-relation, Multilayer position, resolution and efficiency. Time ns Space mm

Difference RT 6%-8% CO2 Difference mm Time ns

Multilayers Position Difference between the two branches of RT relation for the 2 MLayers

Air Contamination (F.Cerutti) Data taken in 2001 “Lab AIR” = 80% N2, 20% O2 Air Contamination: 0.5%, 0.3%, 0.1% 0.05% O2 contents (ppm):1000, 600, 200, 100 Measured : Change in RT relation in Resolution and in efficiency. Comparison with Garfield only in qualitative agreement with data

RT-Relations Differences up to 200  m Contaminated gas faster (No air-5 per mill)~3% Differences up to 200  m Contaminated gas faster (No air-5 per mill)~3%

Resolution Deterioration of the resolution >1 per mill contamination Average resolution: No air 113  m 1 per mill 125  m 3 per mill 141  m 5 per mill 158  m Deterioration of the resolution >1 per mill contamination Average resolution: No air 113  m 1 per mill 125  m 3 per mill 141  m 5 per mill 158  m

3  Efficiency Plateau efficiency ~96% Inefficiency due to  -ray Significant difference only for 5 per mill at the end of the tube: attachment ? Plateau efficiency ~96% Inefficiency due to  -ray Significant difference only for 5 per mill at the end of the tube: attachment ?

Hit Efficiency Plateau efficiency ~100% Inefficiency only close to the tube Significant difference only for 5 per mill at the end of the tube: attachment ? Plateau efficiency ~100% Inefficiency only close to the tube Significant difference only for 5 per mill at the end of the tube: attachment ?