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

and

for electrons

Solenoid

Positrons#Simulations