1. Background understanding and detector inefficiency
Can we understand the remaining events from a view of photon inefficiency ? ( if possible, subtract them as backgrounds.)
An Idea :
Special trigger
Kp2 but one photon is missed.
(2) Event reconstruction
Missing photon kinematics
(3) Photon inefficiency as a function of its energy and direction ?
NOTE :
Different type of critical backgrounds.　　　　　　　　
Geometrical dependence : Detector hole, dead material
Energy dependence 　 : Photonuclear interaction …

2. Phase space correction factors
Polar angle distribution
Correction factors
Monte Carlo simulation
Real data

3. Daughter Table Method w/ Binominal error Convoluted inefficiency
Daughter tables produced by random number generator
300 daughter tables

4. p0  gg background subtraction

6. p0  gg background subtraction

7. Improvement by the subtraction
Upper limit on
Improvement (Before/After)
Before subtraction
After subtraction

11. Convoluted p0 rejection
Results
Dip angle dependence
Next Slide …
p0 rejection from 1gamma
inefficiency tables.
p0 rejection from real data
(from pnn1 analysis.)
p0 rejection from 1gamma
inefficiency tables.
p0 rejection from real data
(from pnn1 analysis.)

12. Stretch functions

13. Kinematical Fitting Before/After
Performance checks with MC sample

14. c2 Probability from Kin Fitting
Kp2(1) for denominator map
1gamma for numerator map

15. Self-vetoing effect due to split photon
MC simulation
Missing photon kinematics

16. Single Photon Inefficiency

17. Single Photon Inefficiency

18. p0  gg detection inefficiency
(1) Photon kinematics
(2) Single photon inefficiency
from MC simulation

19. Daughter Table Method w/ Binominal error Convoluted inefficiency
Daughter tables produced by random number generator
300 daughter tables

20. Polar angle distribution Correction factors
Monte Carlo simulation
Real data

21. p0  gg background subtraction

23. p0  gg background subtraction

24. Improvement by the subtraction
Upper limit on
Improvement (Before/After)
Before subtraction
After subtraction

28. Abs(sin(theta)) < 0.45
Energy leakage
Einner > 10 MeV

29. Fiducial Constraints

30. Performance of the clustering Method
MC sample
theta

31. p0 gg backgrounds Photon inefficiency 20<Eg[MeV]<225
Low energy g : sampling fluctuation
High energy g: photonuclear interaction ( hard to simulate reliably.)
Detector photon inefficiency
(measured with real data)
20~40MeV
40~60MeV
60~80MeV
80~100MeV
100~120MeV
120~140MeV
140~160MeV