User name X. Zheng
Log entry time 15:50:58 on June13,2001
Entry number 62969
keyword=Gas cherenkov PID performanceAttached are two plots for gas cherenkov PID performance. Run #1523 and #20523 (beam 5.7 GeV, Pl=Pr=1.455 GeV/c) are used for analysis. These are high pion runs so only the pion rejection results shown below are reliable.
First plot shows electron efficiency and pion rejection factor for left arm GC.
Second plot is for right arm GC.
For both plots, x-axis is cut in adc_sum_t of GC, y-axis is electron efficiency /pion rejection factor. Single ph.e. peaks for both GCs are aligned to channel #150, so usually a cut of adc_sum_t>250 is applied to select electrons. With this cut the pion rejection factor of left arm GC is above 300, and right arm GC is above 500.
Analysis (please refer to E99117 homepage, http://hallaweb.jlab.org/physics/experiments/he3/A1n/pid/memo12/) shows that average numbers of ph.e. for left arm GC are all better than right arm. The result shown here (right arm better than left arm) is different, partly due to the quality of sample events is different for left/right arms. (samples are selected by 2-D cuts in lpr1e-lpr2e or showerE-preshowerE, calibration for shower/preshower is better than that of pion rejectors).
But in general both give pretty good pion rejection performance.
FIGURE 1
FIGURE 2
