Understanding of the E391a Detector using KL

decayKen Sakashita

( Osaka University )for the E391a collaboration

1.Overview2.KL → 30 analysis3.KL beam & Detector study4.Conclusion

• Engineering RunOverview(1)

» CsI » Charged Veto» Collar counter (CC03)» Edge counter

• Detector & KL beam understanding– Data sample vs MonteCarlo

• KL 30

– Confirm our MC simulation• We need confirmed MC simulation in order to study acceptance and so on.

Detector only downstream part

Overview(2)• Data sample (only 3 hours run used in this study)

– Mainly KL 30 6 – Energy measured by CsI calorimeter– Only neutral decay mode ( no spectrometer !!)

• MonteCarlo Simulation – Input KL beam (avr. P = 4GeV@Detector)– GEANT3 based Detector simulation

• Method– Reconstructed KL events

• Simple clustering (typically 3x3)• Reconstructed KL 30 with good vertex chi square

• 0.46 < MKL (GeV) < 0.53

KL momentum (GeV/c)

Generated by Beam line Simulation

• Invariant mass of 6 # of KL Data/MC = 0.74KL->30 Data vs MC

Compare in 0.5 GeV energy bin

DataMC

• Wrong KL momentum distribution

Is the problem due to input KL momentum or

detector response ?

KL->30 Data vs MC( 0.5GeV EKL bin)• Vertex Z distribution

– Sensitive to energy response

DataMC

DataMC

• Minimum distance between clusters– Sensitive to energy response

DataMC

DataMC

KL->30 Data vs MC( 0.5GeV EKL bin )

KL->30 Data vs MC( 0.5GeV EKL bin )• Cluster Hit Position (distance from the

center)– Sensitive to detector response

DataMC

DataMC

Reweighted input KL momentum• MC は、よく　 detector 　を再現しているように見

える。• 実験で得られた KL momentum を、

MC の　 input KL momentum に反映させてみる。 DataMC

KL momentum is softer than estimated one. consistent with results of the Beam survey.

KL->30 Data vs MC( reweighted )– Vertex Z match well– Cluster Hit position ( Rij ) still match

DataMC

DataMC

KL->30 Data vs MC (reweighted)• PT

2 distribution is not consistent with MC.

• Beam shape D 2

( ) is not also consistent with MC. MC does not reproduce KL Beam shape well.

DataMC

22 yvertexxvertexD

Summary• E391a detector is working well.• We can get good KL pencil beam.

• Detector & KL beam understanding using KL->30

– KL Beam•Yield Data/MC = 0.74•Momentum distribution

– Softer than estmated distribution– It is consistent with the results of the beam survey– After reweighting Data vs MC match well

•Beam shape– MC did not reproduce well. It needs more study.

– Detector• More detail study in the next step

予備 OHPs

KL->30 Data vs MC( reweighted )– Cluster Hit position ( Rij ) still match– Minimum distance between clusters still match

KL->30 Z reconstruction

1. Make 3 gamma pairs from 6 clusters– Resonstruct Z vertex by asusuming M0 from 2

2. Calculate vertex chi square for 15 combinations of 30

3. Select best combination for KL candidate

0

12

22 ).(

N

i Z

ii

i

ZZavr

2χ

KL->30 Data vs MC( reweighted )– Beam shape ( vertex X,Y )

DataMC

TargetCsI

TargetEOC ZZ

ZZvertexXXvertex

...