Difference between revisions of "CDC 60 40"
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Resolution is calculated as fitted drift distance - measured distance, so it is positive when the measured drift time and distance are too small. | Resolution is calculated as fitted drift distance - measured distance, so it is positive when the measured drift time and distance are too small. | ||
In this case they are slightly too small at small drift distance but too large at large drift distance. This could be a problem with the gas mix. For reference, plot res vs distance for tz=5,7,and 0. | In this case they are slightly too small at small drift distance but too large at large drift distance. This could be a problem with the gas mix. For reference, plot res vs distance for tz=5,7,and 0. | ||
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| + | {| border="0" cellpadding="2" | ||
| + | |+ Resolution for 1975V, hit thresholds 5sigma, timing thresholds 4sigma, 1sigma, pedestal at t(t4sig)-13, tz_add=8, 60/40 Garfield | ||
| + | |[[Image:run_31842_res20_tz8_6040.png|thumb|x250px|1975V, resolution ch 20]] | ||
| + | |[[Image:run_31842_resx20_tz8_6040.png|thumb|x250px|1975V, resolution vs hit radius]] | ||
| + | |} | ||
| + | Increasing tz_add to 8ns shifts the resolution up at earlier times but it hardly moves at later times. This would probably have been obvious from the tz=0 data (below). | ||
| + | |||
| + | {| border="0" cellpadding="2" | ||
| + | |+ Resolution for 1975V, hit thresholds 5sigma, timing thresholds 4sigma, 1sigma, pedestal at t(t4sig)-13, tz_add=0, 60/40 Garfield | ||
| + | |[[Image:run_31842_res20_tz0_6040.png|thumb|x250px|1975V, resolution ch 20]] | ||
| + | |[[Image:run_31842_resx20_tz0_6040.png|thumb|x250px|1975V, resolution vs hit radius]] | ||
| + | |} | ||
Suspect total flow of 60sccm might be too low for the CO2 MFC. Increase to 80sccm and repeat. Also try Garfield for different gas mixes and look at tmax. | Suspect total flow of 60sccm might be too low for the CO2 MFC. Increase to 80sccm and repeat. Also try Garfield for different gas mixes and look at tmax. | ||
Revision as of 16:54, 11 September 2012
60/40 Ar/CO2 and cosmics, prototype horizontal
This does not look nearly as good as 50/50 gas mix. Resolution is calculated as fitted drift distance - measured distance, so it is positive when the measured drift time and distance are too small. In this case they are slightly too small at small drift distance but too large at large drift distance. This could be a problem with the gas mix. For reference, plot res vs distance for tz=5,7,and 0.
Increasing tz_add to 8ns shifts the resolution up at earlier times but it hardly moves at later times. This would probably have been obvious from the tz=0 data (below).
Suspect total flow of 60sccm might be too low for the CO2 MFC. Increase to 80sccm and repeat. Also try Garfield for different gas mixes and look at tmax.
