# Pair Production Rate Calculation

## LINAC parameters used in calculations

1) pulse width 50 ps
2) pulse current 50 A
3) repetition rate 300 Hz
4) energy 44 MeV

## Number of photons/sec out of radiator

### 1/2 mil of Ti






Alex factor is 6.85 %




### 1/2 mil of Al






Alex factor is 6.85 %




### Conversion factor from Ti to Al

All my following calculation for pair production rate are based on (1/2) mil of Ti radiator. If we want to recalculate for (1/2) mil of Al converter we need to use the conversion factor:




### Appendix

in (10,20) MeV region we have about 0.1 photons/electrons/MeV/r.l both for Ti and Al radiators

## Pair production rate

### out of Al converter



 (by varying width we can vary the yield)






### through 1 m of air

Assume air consists entirely from Nitrogen:










### 1 m of air vs. 3.0 um of Al converter




### Appendix

#### pair production cross sections in an Al target

Ref. Geant4 and Theoretical Pair Production Cross Sections for 1 MeV - 100 GeV photons in Aluminum. Vakho Makarashvili, December 18, 2007

#### pair production cross sections in a Nitrogen

Ref. Photon Cross Section, Attenuation Coefficients, and Energy Absorption Coefficients From 10 keV to 100 Gev. J.H.Hubbell. Center for Radiation Research.National Bureau of Standards. Washington, D.C. 20234

Here I just plotted the table above for pair production cross section in (0, 40) MeV energy region