1. Converted Photon Hits in Muon Higgs Factory
T. Markiewicz
MAP at SLAC
30 April 2014

2. FLUKA Geometry
Takashi Maruyama

3. Use Takashi’s GEANT3 Hit Files
Unnormalized: x510 to get 1 bunch
# hits on layer per photon (all layers in this plot)
Long tail to software maximum of 200; mean number for whole sample is 10 hits/incident photon

4. Time when photon produced+75ns

5. Time (relative to photon production time) when electron from converted photon hits any silicon layer
111552/11216=9.95

6. R versus Z of Photons that will hit any Silicon layer

7. R versus Z of hits any Silicon layer

8. Z Distribution of r=50 Barrel
Look at converted photons at r=50cm -91<z<91 Silicon layer: 1st layer of tracker
Z Distribution of r=50 Barrel

9. Time Distribution of e+/e- hits on r=50 Barrel
time=time_parent+time_child (with 75ns subtracted from the time of the parent)

10. Time Distribution of e+/e- hits on r=50 Barrel Expanded Scale
NB: Max. transit time for prompt photon from vertex is 3.75ns

11. Time Distribution of photons that later convert on r=50cm Barrel
Nb: Photon times are plotted for each e+/e- hit seen, up to software max of 200

12. Time Distribution of photons that later convert on r=50cm Barrel (expanded scale)
Nb: Photon times are plotted for each e+/e- hit seen, up to software max of 200

13. Time Distribution of e+e- hits relative to photon production time on r=50cm Barrel

14. Origin of photons that later convert & produce hits on r=50cm Barrel

15. Conclusion r=50cm
A 4ns time cut would leave <~5-10/50k hits or (1-2)E-4 rejection
10 x 510 x 2 x 1000 = 10^7 hits per train on this barrel layer
10^7/57176 cm^2=175 hits/cm^2 or 0.9 hits/(50um x 1cm strip)

16. Z Distribution of r=5.5 Barrel

17. Time Distribution of e+/e- hits on r=5.5 Barrel
time=time_parent+time_child

18. Time Distribution of e+/e- hits on r=5.5 Barrel Expanded Scale
NB: Max. transit time for prompt photon from vertex is 0.71ns

19. Origin of photons that later convert & produce hits on r=5.5 cm Barrel

20. Conclusion r=5.5cm A 1ns time cut would leave <0/20k hits
A 2ns time cut would leave 12/20k hits, rejection is 6.14E-4
12 x 510 x 2 x 1000 = 1.22 x 10^7 hits per train on this barrel layer
1.22 x 10^7/1417 cm^2=8600 hits/cm^2 or hits/(20um x 20um pixel)

21. Z Distribution of r=131cm Barrel

22. Time Distribution of e+/e- hits on r=131cm Barrel
time=time_parent+time_child

23. Time Distribution of e+/e- hits on r=131cm Barrel Expanded Scale
125 hits t<8ns
325 hits t<11ns
NB: Max. transit time for prompt photon from vertex is 8.0ns

24. Origin of photons that later convert & produce hits on r=131cm Barrel

25. Conclusion r=131cm
A 8ns time cut would leave <125/43k hits, rejection is 2.9E-3
A 11ns time cut would leave 325/43k hits, rejection is 7.6E-3
( ) x 510 x 2 x 1000 = ( ) x 10^7 hits per train on this barrel layer
( ) x 10^7 /3.3E5 cm^2=( ) hits/cm^2 (1cm x 1cm sensor)
Will need an energy cut as well

26. Time Distribution of e+/e- hits on disks at z=25, 92 and 200cm
125 hits t<8ns
325 hits t<11ns
Two disks at z=25cm, 6.7<r<18.4
TOF from vertex =1.0 ns
0 hits
Two disks at z=92cm, 25.3<r<53.3
TOF from vertex =3.5 ns
0 hits
Two disks at z=200cm, 38.0<r<130.9
TOF from vertex =8.0 ns
0 hits

27. Radial distribution of hits on z=200cm disks Note hits from r=50cm barrel