User name X. Zheng
Log entry time 22:26:34 on July 3,2001
Entry number 65612
keyword=Analysis dependence on gas cherenkov cutFor quasi offline analysis 1D cut in gas cherenkov adc_sum_t has been used to select electrons. For both arms it is (300, 10000). With enough statistics asymmetry dependence on cherenkov cut has been studied.
A cut in pion rejectors and shower/preshower is used in this analysis, which has > 98% pion rejection efficiency.
Figure 1: left arm
Figure 2: right arm
Top: Longitudinal raw asymmetry vs. cut in spec_l.gas.adc_sum_t. Four configurations of beam and target half waveplate are plotted;
Bottom: Transverse raw asymmetry vs. cut in spec_l.gas.adc_sum_t. Two configurations of beam half waveplate are plotted;
Present conclusion:
With 2D cut in pion rejector, asymmetry shown here is not sensitive to cut in gas cherenkov adc_sum_t at x=0.6 kinematics. (which has been expected since pion/e ratio here 20 and there is only a tiny pion contamination envolved.)
For right arm, we expected that the asymmetry doesnot change as we put tighter cut in cherenkov,( since 2D cut in shower/preshower cut out 98.7% pions already). But here we observe a small evolution in longitudinal setting. I furthur calculate the parallel asymmetry combining all 4 configurations and the final one is not sensitive to cherenkov cut (please see next entry). Later a more careful analysis will be done, for the present we conclude that:
The original cuts are good for current quasi offline analysis. Moreover, since asymmetry is almost unchanged when cut in cherenkov is loosed by a factor of 10, PID efficiency should also be good enough for the other two kinematics: x=0.33 and 0.45, where pion/electron ratio will be 10 times higher.
FIGURE 1
FIGURE 2
