1. FVTX dEdx digitization Zhengyun You Peking University Los Alamos National Lab Jun 05, 2007

2. 2 Charge sharing on strips Digitize hit’s energy loss by length on each strip; From position in and out to get a hit’s length on each strip; 300 µm 75 µm / strip eStrip1 eStrip2 eStrip3 eStrip4

3. 3 E loss distribution E loss on a layer; pT = 2GeV Kaon µ from W pT > 10GeV pT = 2GeV Kaon µ from W pT > 10GeV E loss on a strip; ADC

4. 4 Digitization pT = 2GeV Kaon µ from W pT > 10GeV pT = 2GeV Kaon µ from W pT > 10GeV Digitize with 3 bit [1500, 30000] E loss on a layerSum of E loss on strips (after digi) ADC 18500

5. 5 Digitization pT = 2GeV Kaon µ from W pT > 10GeV pT = 2GeV Kaon µ from W pT > 10GeV E loss on a layerSum of E loss on strips (after digi) ADC Digitize with 4 bit [1500, 30000] 18500

6. 6 Cut Cut on ADC of each hit on a track (Only all (4) hit’s ADC > cut value will be considered as µ from W) ADC cut : 18700 ADC precise pT = 2GeV Kaon µ from W pT > 10GeV ADC One hit’s ADC distribution 18500 ADC after digitization

7. 7 Efficiency of Kaon Kaon’s rejection factor : Precise value : ~ 40 4 bit : ~ 30 3 bit : 20 W efficiency 3 bit (77% pT>20) W efficiency 4 bit (87% pT>20)

8. 8 W ‘s fake high pT background primary_pt<2GeV contribute ~90% of fake high reco_pt background K ‘s contribution is 91%, π is only 9% ; Real low pT Kaon Real high pT µ from W Cut efficiency : dE/dx (fvtx track required) vs primary_p T K+ π+π+

9. 9