Niowave 10-2015

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Initial rate study

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

G4beamline pencil beam 10 cm radius

beam ellipse particle=e- nEvents=1000000 beamZ=0.0 beamX=0. beamY=0. \
        sigmaX=10.0 sigmaY=10.0 sigmaXp=0.000 sigmaYp=0.000 \
      meanMomentum=10. sigmaE=0. maxR=10.

Incident Electron spatial distribution and energy

PbBi 5-1-15 X-Yposition.pngPbBi 5-1-15 Ein.png

Positron and Electron Momentum after the converter

PbBi 5-1-15 Ppositron.pngPbBi 5-1-15 Pelectron.png

PbBi Thickness (mm) #positrons/million electrons (G4Beamline) #positrons/million electrons (MCNPX)
1 1169,1083,1068,1090,1088 =1100[math]\pm[/math] 40 1091
1.5 1723, 1668,1671, 1687,1726=1695[math]\pm[/math] 28 1728
2 1902,1921,1886,1967,1922=1920[math]\pm[/math] 30 1984
3 1920,1880,1883,1864,1857=1881 [math]\pm[/math] 24 1986
4 1688, 1766, 1712, 1709, 1753=1726[math]\pm[/math] 33 1858
5 1569,1585,1509 ,1536,1551=1550[math]\pm[/math] 29 1646
7 1475,1450,1457,1428,1477 =1457[math] \pm[/math] 20 1541
10 1250,1180,1178,1186,1166=1192[math]\pm[/math] 33 1216

G4Bl-vs-MCNPX 5-5-2015.png

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

E1.png

Electrons - 68.2% core

E2.png

Positrons - RMS

P1.png

Positrons - 68.2% core

P2.png



The plot below shows the energy deposited in MeV along the pipe. The Z axis is along the beam direction. The distance around the beam pipe is determine by taking the pipe radius (34.8 mm) and multiplying it by the Phi angle around the pipe. The bins are 1cm x 1cm.



BeamPipeDepEPhi 34.8 082815.png BeamPipeDepE 34.8 082815.png
A maximum of 450,000 MeV is deposited in a 1 cm[math]^2[/math] bin when 20 Million , 10 MeV electrons are incident on a 2 mm thick PbBi target located at Z=-902 mm.

Below is energy deposited contributions from from photons(AVSzWg), positrons (AVSzWpos), and electrons.


BeamPipeDepE 34.8 082815 parttype.png

Why is the positron hotspot upstream of the target? Because beam was going from right to left.



root commands used

TH2D *AVSz=new TH2D("AVSz","AVSz",100,-1000,0,12,-60,60)
BeamPipeE->Draw("35.*atan(PosYmm/PosXmm):PosZmm>>AVSz","DepEmeV"); 
AVSz->Draw("colz");


Rate comparison with Energy and target thickness

Difference with above simulation are that GEANT4 has SS windows and all created positrons that leave the target are counted , not just those going through a Sensitive detector downstream

6MeV

PbBi Thickness (mm) #positrons/million electrons (GEANT4.9.6.p02 #positrons/million electrons (G4Beamline)
0.5 284,306,281,290,288 = 290[math]\pm[/math]10
1 465,449,457,454,472 = 459[math]\pm [/math]9
1.5 456,416,445,445,434 =439[math]\pm [/math]15
2 396,418,394,415,395 =404[math]\pm [/math]12
4 338,327,332,341,336=335[math]\pm [/math]5
7 257,280,265,268,259 =266[math] \pm [/math]9
10 223,225,234,210,221 =223[math]\pm[/math] 9

8 MeV

PbBi Thickness (mm) #positrons/million electrons (GEANT4.9.6.p02 #positrons/million electrons (G4Beamline)
0.5 458,458,535,533,516=500 [math]\pm [/math]39
1 994,996,967,971,956=977[math] \pm [/math]18
1.5 1166,1196,1139,1176,1178=1171[math]\pm[/math] 21
2 1184,1212,1175,1194,1178=1189[math]\pm[/math] 15
4 989,1013,975,962,956= 979[math]\pm[/math]23
7 815,765,829,806,817=806[math] \pm[/math] 25
10 641,660,636,671,682 = 658[math]\pm[/math]20

10 MeV

PbBi Thickness (mm) #positrons/million electrons (GEANT4.9.6.p02 #positrons/million electrons (G4Beamline)
0.5 628,653,713,686,689 = 674[math]\pm[/math]33
1 1524,1607,1565,1598,1581 = 1575 [math]\pm[/math] 33
1.5 2163,2264,2091,2154,2094= 2153[math]\pm[/math] 70
2 2445,2386,2321,2359,2368 = 2376 [math]\pm[/math] 45
4 2087,2104,2121,2154,2118 = 2117 [math]\pm[/math] 25
7 1675,1697,1708,1720,1750=1710 [math] \pm[/math] 28
10 1398,1421,1374,1418,1398 = 1402[math]\pm[/math] 19


PosProd-vs-E 2-9-16.png

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 [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


Comparison.png


Energy Distribution

TF PosE 04-28-15.png Positrons2.png

Angular distribution of positrons

TF Theta 04-28-15.png


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


4-30-2015 PositronMomentum 2mm.png4-30-2015 ElectronMomentum 2mm.png

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

For now I have a gaussian with an 1mm RMS and 10 MeV incident electrons as shown below.

4-30-2015 BeamPosDelta.png4-30-2015 ElectronMomentum.png


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


4-30-2015 PositronMomentum 2mmDelta.png4-30-2015 ElectronMomentum 2mmDelta.png

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_2mm10MeVDelta.dat


and

http://www2.cose.isu.edu/~foretony/Electrons_2mm10MeVDelta.dat


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

Ed1.png

Electrons - 68.2% core

Ed2.png

Positrons - RMS

Pd1.png

Positrons - 68.2% core

Pd2.png