G4Beamline PbBi

Development of a Positron source using a PbBi converter and a Solenoid

Converter target properties

Definition of Lead Bismuth

1cm diameter target 2 mm thick PbBi

0.5 Tesla solenoid

G4BeamLine and MCNPX

Target thickness optimization

First simple test is to send 1 million, 10 MeV electrons towards a PbBi target and count how many positrons leave the downstream side

The Random number seed is set by Time in G4beamline to use a different set of pseudo random numbers each time it is run

The G4Beamlin incident electron beam has the following properties

beam gaussian particle=e- nEvents=1000000 beamZ=0.0 
        sigmaX=1.0 sigmaY=1.0 sigmaXp=0.100 sigmaYp=0.100 
        meanMomentum=10.0 sigmaP=4.0 meanT=0.0 sigmaT=0.0

PbBi Thickness (mm)	#positrons/million electrons (G4Beamline)	#positrons/million electrons (MCNPX)
1	960,874, 916,934,897=916 +/- 33	1091
1.5	1508	1728
2	1963,1919,1880,1877,1970 = 1902 [math]\pm[/math] 43	1984
2.5	1997	2062
3	2233,2250, 2251,2226 , 2222=2236 [math]\pm[/math] 13	1986
3.5	2193	1938
4	2184,2156,2089,2173,2181=2157 [math]\pm[/math] 39	1858
5	2042	1646
6	1851, 1932, 1857, 1896,1924 = 1892[math] \pm[/math] 37	1541
10	1480,1488	1216

Comparison of G4Beamline and MCNPX

Energy Distribution

Angular distribution of positrons

2mm thick, 10 MeV, 1 cm cylindrical incident electron distribution

I was unable to do anything other than a gaussian beam right now, I will try to do one later

For now I have a gaussian with an 8mm RMS and 10 MeV incident electrons as shown below.

The positron and electron momentum distributions after the PbBi converter are shown below

A comma delimited text file with the above events in the format of

x,y,z,Px,Py,Pz

in units of cm for distance and MeV for momentum is located at

for positrons

http://www2.cose.isu.edu/~foretony/Positrons_2mm10MeV.dat

and

http://www2.cose.isu.edu/~foretony/Electrons_2mm10MeV.dat

for electrons

Solenoid

Positrons#Simulations