1. Gamma Flux Bubble Chamber Expected Rates – Sept 2015 January 20, 2016 1

2. GEANT Model Gamma Flux vs Electron Kinetic Energy Expected Natural N 2 O Rate Expected Rates of: I. 18 O( ,  ) 14 C II. 17 O( ,n) 16 O III. 14 N( ,p) 13 C Remarks O UTLINE 2

3. 3 G EANT 4 M ODEL Gap between radiator and collimator = 0.59 inches Distance between radiator and center of glass cell = 14.02 inches

4. 4 GEANT4 Cut = 1 keV Forward flux from radiator Flux entering glass cell

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19. For natural N 2 O, most events are γ-α from 18 O 19 E XPECTED N ATURAL N 2 O R ATES No Threshold Cut

20. Chamber threshold = 130 keV Elastic neutron scattering – 16 O(n,n) and 14 N(n,n) – is not included 20 E XPECTED 17 O( ,n ) 16 O R ATE

21. Chamber threshold = 90 keV Elastic neutron scattering – 16 O(n,n) and 14 N(n,n) – is not included 21

22. Expected rate from 14 N(γ,p) 13 C with lower operational pressure (Chamber threshold = 50 keV) 22 E XPECTED 14 N( ,p ) 13 C R ATE

23. Expected rate from 14 N(γ,p) 13 C with lower operational pressure (Chamber threshold = 20 keV) 23

24. Design new radiator to match lower electron energy for 19 F( ,  ) 15 N Must reduce distance between radiator and chamber to increase flux by at least a factor of 10 Use silver (or even gold) radiator? Use silver collimator C ONCLUSIONS 24