1. final state study Jaewon Park University of Rochester MINERvA/Jupiter Group Meeting, Apr 04, 2007

2. 2 Single gamma (electron) calibration Gamma will have a little bit longer atten uation length at low energy. It means it’ll reach to ECAL and calibrat ion constant will be dropped slightly. But why not happened here?

3. 3 Single gamma (electron) energy deposit in subdetector Theta=40deg Low energy gamma h as longer interaction l ength For low energy electr on, most of energy is deposited in ID. gamma electron

4. 4 Do we need Upstream ECAL? When E(pi0) is sma ll, there’are more e vents that one of ga mma go to US-EC AL

5. 5 Upstream ECAL calibration for gamma Theta=180deg (pointing to upstream) E average deposit is calculated using summation At low energy gamma, reconstructed E drops. Distance to UECAL was 20cm.  Need to check other distances too.  For theta=40deg, distance to ECAL is about 91cm / sin40 = 140cm

6. 6 Goal is eliminating tails on pi0 mass distribution For instance, Pi0 mass E(gamma)>30MeV

7. 7 E id fraction vs. Pi0 mass, E(gamma)>30MeV At low pi0 energy, small fraction ID en ergy deposit (E id) give tails on pi0 ma ss distribution.

8. 8 mass Pi0 mass is determi ned from two gam ma energy and angl e between them New pi0 event selec tion using E,id(gam ma) > E(gamma)