1. BOS Testbeam Results in 2001 MPI & LMU, Munich 1. Drift time spectra 2. RT-relation 3. Resolution - HV & threshold dependance -Comparison with the 1999 data 4. Summary 1. Drift time spectra 2. RT-relation 3. Resolution - HV & threshold dependance -Comparison with the 1999 data 4. Summary ________________________________________________________________________________________ Sandra Horvat 10.12.2000, Testbeam meeting, CERN

2. Teststand & Program Chamber: BOS-0 - same chamber type as in the 1999 testbeam, (differrent electronics!) - runs with 2 or 4 mezzanine cards - flowing nitrogen in ML2, to avoid high HV currents Threshold scan: 60 mV 77 mV 90 mV 98 mV HV scan: 2980 V 3080 V 3180 V Angular scans (90 0 -100 0, 110 0 -130 0 ) => still to be analised… ML1 ML2 ______________________________________________________________________________________ 1 Sandra Horvat 10.12.2000, Testbeam meeting, CERN 3 sections scanned, 10 cm each

3. Drift Time Spectra _____________________________________________________________________________________ 2 Sandra Horvat 10.12.2000, Testbeam meeting, CERN 3080 V77 mV 60 mV 77 mV 98 mV 2980 V 3080 V 3180 V 2001: 60 mV threshold, t rise =(10.6±0.3) ns 1999: 25e threshold, t rise =(8.4±0.4) ns

4. Fine Time Oscillations _____________________________________________________________________________________ 3 Sandra Horvat 10.12.2000, Testbeam meeting, CERN Channel 2Channel 16 Fine time spectra Uncorrected Drift Time Corrected Drift Time Uncorrected Drift Time Corrected Drift Time t rise =11.6 ns t rise =12.8 ns Excluded from the analysis!

5. Maximum drift time & Rise time ______________________________________________________________________________________ 4 Sandra Horvat 10.12.2000, Testbeam meeting, CERN  t=t 0 -t max t rise =4T 0  t decreases with : threshold (due to the change in t 0 ) HV (due to t 0 & t max ) - t rise degradation at higher threshols and lower HV => implies degradation in the tube resolution

6. RT-relation 1. step: applying the rt-relation from 1999 testbeam (determined by a silicon tracker) and tracking through the 6 layers (using LMU analysis software) 2. step: Autocalibration – correcting the rt-relation using residuals from the track, 15 bins of 1 mm _____________________________________________________________________________________ 5 Sandra Horvat 10.12.2000, Testbeam meeting, CERN residuals r=4.5mmr=10.5 mm

7. Tube Resolution Method: - tracking through the 5 layers, - track interpolation to the tube in the excluded layer (excluding layers 1, 3, 4 & 6) -histograming the distance of the real hit from the track, r extrapolated -r measured Measured resolution:  meas =  (r extrapolated -r measured ) tube resolution: Correcting for the fit error-> tube resolution:  real = sqrt (  2 measured -   corr ),  Where   corr =  2 (m)*z 2 +  2 (b),  track is given by : y=z*m+b _____________________________________________________________________________________ 6 Sandra Horvat 10.12.2000, Testbeam meeting, CERN

8. Tube Resolution - Results _____________________________________________________________________________________ 7 Sandra Horvat 10.12.2000, Testbeam meeting, CERN -Similar resolution curves obtained for all layers. - Good reproducibility! Preliminary!

9. Tube Resolution – Threshold & HV dependence _____________________________________________________________________________________ 8 Sandra Horvat 10.12.2000, Testbeam meeting, CERN Preliminary! - degradation of the resolution with the rising threshold - resolution improves with higer HV (at lower radii)

10. Comparison with the 1999 data _____________________________________________________________________________________ 9 Sandra Horvat 10.12.2000, Testbeam meeting, CERN Resolution curve for the 1999 testbeam: obtained using the same analysis method as for 2001 testbeam data This is compared to the single tube resolution, obtained by a silicon tracker => 5-hit tracking method gives similar results as silicon tracker (differences for large radii) 2001 testbeam results show a slight degradation in the resolution with respect to the 1999 testbeam (same chamber type and gas as in 1999)  Electronis? Preliminary!

11. BOS BIL 2001 testbeam results _____________________________________________________________________________________ 10 Sandra Horvat 10.12.2000, Testbeam meeting, CERN BOSBIL - BOS resolution curve rises somewhat more slowly - similar resolution at large r

12. Summary Drift time spectra : low noise larger rise time compared with 1999. dependence on threshold & HV fine time oscillations in some channels Tube Resolution: calculated by tracking through 5 layers (LMU software) similar resolution for all layers, reproducible results dependence on threshold & HV degradation with respect to the 1999. data (both silicon tracker and tracking through 5 layers give similar result for 1999.) BOS 2001. comparable to BIL 2001. testbeam results _____________________________________________________________________________________ 11 Sandra Horvat 10.12.2000, Testbeam meeting,CERN Many, many special thanks to the ROME group, for the constant help, support & encouragement !!! Many, many special thanks to the ROME group, for the constant help, support & encouragement !!!