Sample events

• top left: preshowerE vs. showerE, cut in 800<spec_r.gas.adc_sum_t<10000;
  - This is the definition of sample electron events from gas cerenkov detector, which will be used for shower/preshower efficiency analysis. Solid curve shows additional 2D cut in preshowerE and showerE to eliminate pion contamination in sample electron events due to inefficiency of gas cerenkov detector.
• top right: preshowerE vs. showerE, cut in spec_r.gas.adc_sum_t>10000;
  - This defines sample pion events from gas cerenkov detector, which will be used for shower/preshower efficiency analysis.
• bottom left: preshowerE vs. showerE, no cut, lines show the cuts in preshowerE and showerE to select sample electron events, which will be used for gas cherenkov efficiency analysis;
• bottom right: preshowerE vs. showerE, no cut, lines show the rectangular region in preshowerE and showerE to select sample pion events, which will be used for gas cherenkov efficiency analysis;

Figure: sample events for a high pion run