1. Pi0 Simulation for BigCal
Jixie Zhang
July 2nd, 2015

2. What Is New? https://github.com/jixie/sane_geant3_mc
1. The weighting of event from various targets (H,He,N,Al) were calculated according to the numbers listed in the wiki, aluminum including target nose and 4k-shielding.
2. Weight thrown events to match the cross section in 3-D space of p:cosq:phi.
3. Checked the weighting carefully.
4. Due to statistics reason, rebin the RCS and Protvino calorimeter by 2x2.

3. Definition of Electron Cut
In the geant3 simulated ntuple, an electron is defined as the following:
A) cer_npe > 60 && cer_npe < 110
B) E_m > 0.5
cer_npe is the number of photon electron
E_m is the energy deposited in the BigCal

4. About Thrown Events

5. Number of Atoms in The Target Nose
Material Z
Thickness
(cm)
Density (g/cm^3)
Moll-Mass (g/moll)
Number of Atoms
Al end caps 14
0.0065x2.54 x 2
2.7
26.982 H 1
1.8
NH3=0.817
NH3=
x 3 N 7
LHe 2
0.145
4.003
A) 60% packing fraction,
B) target cell length is 3 cm,
C) the liquid helium thickness outside the cell is 0.5 cm on both ends,
D) Aluminum include 2 end caps(1.5 mil), 4k-shielding (1 mil) and target nose (4mil).
This table shows the relative relation among materials in the target cell. If normalized to N14, the result is:
H : He : N : Al = 3 : : 1 :

6. Weight Thrown Events to Match Cross Section Shape
1) Fill four 3-D histograms, H3XS, of E:CosTh:phi, the content in each 3-D grid is the averaged cross section of H, He, N and Al.
2) Sum these four 3-D histograms, weighted by the number of atoms in the target to get H3XS_total. Integrate the resulting 3-D histogram to get total cross section, XS_total.
3) Fill four 3-D histograms, H3N, of E:CosTh:phi, weighted by the number of atoms in the target. Add them together to get H3N_total. The integral of H3N_total, N_total, is the total number of thrown events.
4) Scale H3XS_total such that its integral equal to that of H3N_total, then H3Weight=H3XS_total/H3N_total. This weighting will match thrown events into the shape of cross section. Later on, use H3Weight to weight each event in the analysis.
5) Charge is proportional to N_total/XS_total. The yield from BigCal after all cuts will be scaled by Charge .

7. Log file Electron runs: 22 M events TotalXS_All = 0.0561277
TotalXS_H = weight_H = 3
TotalXS_He = weight_He =
TotalXS_N = weight_N = 1
TotalXS_Al = weight_Al =
_e: TotalXS= N_Thrown= e+07 fChargeScale=
TYPE N_thrown N_bigcal N_bigcal_cut N_e+_or_e N_e+
Count_
Count_w e e e e
Yield e e e e
Count_w/Yield
Pi0 runs: 61M events
TotalXS_All =
TotalXS_H = weight_H = 3
TotalXS_He = weight_He =
TotalXS_N = weight_N = 1
TotalXS_Al = weight_Al =
_pi0: TotalXS= N_Thrown= e+07 fChargeScale=
TYPE N_thrown N_bigcal N_bigcal_cut N_e+_or_e N_e+
Count_
Count_w e e e e
Yield e e e
Count_w/Yield

8. BigCal RCS: 24 rows x 30 (columns) Y=0 at geant3 code
Protvino: 32 rows x 32 (columns)
different colors indicating the groupings of the trigger channels

9. Binned by groups of blocks
Coded by 2-digit row index and
2-digit column index. i.e. This is 0103
0300
0200
Y=0 at geant3 code
0100
0000
Protvino: 32 rows x 32 (columns)
Grouped by: 8(rows) x 8 (columns)
RCS: 24 rows x 30 (columns)
Grouped by: 6(rows) x 6 (columns)

10. PROT Yield for Electron

11. PROT Yield for Pi0

12. RCS Yield for Electron

13. RCS Yield for Pi0

14. PROT Yield Ratio: Pi0 to Electron

15. RCS Yield Ratio: Pi0 to Electron

16. RCS Yield Ratio: Pi0 to Electron

17. PROT Pi0 Fraction: Pi0 to Total

18. RCS Pi0 Fraction: Pi0 to Total

19. PROT Yield for Electron

20. BigCal Yield Ratio: Pi0 to Electron

21. BigCal Pi0 Fraction: Pi0 to Total