final state study Jaewon Park University of Rochester MINERvA/Jupiter Group Meeting, May 09, 2007

2 Processes involving with final state Proton or muon tracks will determine primary vertex decays into two gammas CC NC

3 Energy vector for gammas Gamma track is not good f or reconstructing pi0 Extrapolating long distance makes big uncertainty Instead, we used center of e nergy position with respect to primary vertex, that is de termined by proton track ? Actual primary vertex position ?

4 Overview of calorimetry particle iron scintillator lead After careful study of ener gy response in each sub-de tector with given energy of incoming particle, then we can determine the energy o f particle IDECALHCAL

5 Simple but fatal mistake on calorimetry calculation While working on converting fortran analysis code to c++ based code, coupl e of lines look weird. It’s turned out to be a big bug. Separating ECAL region from ID was wrong. It selected only half side of it. The impact is making ECAL energy lower. This error propagates all the way to old calibration calculation. I believe that primary particle in old data was pointed to the side that ECAL is selected correctly.

6 Resolution of proton, pi0, and each gammas before correction Asymmetric energy distribution having lower side tail.

7 Resolution of proton, pi0, and each gammas after correction Now it looks much better Also resolution gets smaller

8 Reco E vs. True E of gamma Because lower energy gamma is shown to makes resolution wors e, I used event selection that req uires energy loss fraction in ID greater than 10% But this doesn’t make sense bec ause earlier calibration study sh ows such event election was onl y useful for HCAL Smart analysis technique can’t beat up removable systematic er ror corrected gamma1 gamma2

9 Pi0 mass before correction Pi0 mass is determined from two gamma energies and angle between them

10 Pi0 mass after correction Lower-side tail has been reduced

11 Enhance pi0 mass resolution using chi-squire minimization with pi0 mass constraint Guaranteed single solution

12 Comparing Minuit solution with Mathematica’ numerical solution Minuit result Mathematica’s numerical solution First and second run

13 Chi-square minimization result – gamma energy resolution True angle is used Chi-square minimization makes each gamma’s resolution work They become correlated with constra int are acquired from these plots before after

14 Chi-square minimization result – pi0 energy resolution Pi0 resolution is enha nced We can apply chi-squ are cut to remove po or data points beforeafter

15 W resolution – this part didn’t use chi-square fit W: invariant mass of hadrons Didn’t use E(id)/E > 0.1, so efficiency incr eased. Reconstruced proton direction means usin g reconstructed prima ry vertex Pi0 mass cut: m(pi0) =[90, 150] true proton dirreco proton dir true proton dir Pi0 mass cut Reco proton dir Pi0 mass cut