# PbBi THickness GaussBeam

Use Gaussian to make a incident uniform beam that is 1 cm in diameter and has a beam sigma of 1 cm , then cut out the beam to have a 0.5 cm circular radius.


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 43 1984 2.5 1997 2062 3 2233,2250, 2251,2226 , 2222=2236 13 1986 3.5 2193 1938 4 2184,2156,2089,2173,2181=2157 39 1858 5 2042 1646 6 1851, 1932, 1857, 1896,1924 = 1892 37 1541 10 1480,1488 1216

Comparison of G4Beamline and MCNPX

Energy Distribution

Angular distribution of positrons

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

For now I have a gaussian with an 1mm 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

Dmitry's processing of Tony's GEANT simulations showing transverse phase space portrait (left) and longitudinal phase space portrait (right). Phase space portraits show coordinate x or y vs diveregense=px/pz or py/pz (or time vs kinetic energy ). Captions show:

1. geometric (not normalized) emittance for transverse and emittance for longitudinal phase space portraits (ellipse areas divided by "pi")

2. Twiss parameters

3. Ellipse centroid for longitudinal phase portrait

4. sqrt(beta*emittance) and sqrt(gamma*emittance) - half sizes of the projections of the ellipses on the coordinate and divergence axes respectively.

Electrons - RMS

Electrons - 68.2% core

Positrons - RMS

Positrons - 68.2% core