G4Beamline PbBi: Difference between revisions

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


=Converter target properties=
=Conclusions=
 
Definition of Lead Bismuth
 


1cm diameter target
#A 0.3 (0.6)  Tesla Solenoid with a diameter to allow a 9.74 (3.94) cm diameter pipe would collect a positron per thousand incident electrons on a 2mm thick LBE target with 0.25 mm thick SS windows.
2 mm thick PbBi
# A 15 cm long, 0.2 Tesla solenoid with a 3.94 diameter beam pipe would collect a positron per two thousand electrons impinging a 2mm thick LBE target with 0.25 mm thick SS windows.
#A 4 Tesla Solenoid will remove beam pipe heating from scattered electrons downstream of the target when using a 3.94 cm diameter beam pipe.


0.5 Tesla solenoid
=Reports=


=G4BeamLine and MCNPX=
[[Niowave_Report_11-30-2015]]


==Target thickness optimization==


deadline 4/12/16


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
==[[Niowave_9-2015]]==
==[[Niowave_10-2015]]==
==[[Niowave_11-2015]]==
==[[Niowave_12-2015]]==
==[[Niowave_1-2016]]==
==[[Niowave_2-2016]]==
==[[Niowave_3-2016]]==
==[[Niowave_4-2016]]==
==[[Niowave_5-2016]]==
==[[Niowave_6-2016]]==


The G4Beamlin incident electron beam has the following properties
=Task List=


<pre>
0.) 34.8 mm pipe, 0.0 -> 0.5 Tesla, E= 6,8,10 MeV.
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
</pre>




{| border="1"
1.) Create a positron (10,000 positrons) and electron event file containing t,x,y,z,Px,Py,Pz for positrons exiting the solenoid and an incident Gaussian beam 1cm in diameter and with a sigma of 1cm.
| PbBi Thickness (mm) || #positrons/million electrons (G4Beamline)|| #positrons/million electrons (MCNPX)
|-
| 1    ||  || 1091
|-
| 1.5    ||  || 1728
|-
| 2    || 1873,1945<math>\pm</math> 43 || 1984
|-
| 2.5    || || 2062
|-
| 3|| <math>\pm</math> 13|| 1986
|-
| 3.5||  || 1938
|-
| 4||<math>\pm</math> 39 || 1858
|-
| 5||  || 1646
|-
| 6|| <math> \pm</math> 37 || 1541
|-
| 10||  || 1216
|-
|}


Comparison of G4Beamline and MCNPX
compare distributions with and without solenoid.


2.) Determine the back ground when using a 3.48 diameter beam pipe and Solenoid field of 0.2  for a NaI detector placed at


[[File:Comparison.png | 200 px]]
3.) Experiment, install dipole and solenoid in the tunnel.


=Beam Pipe Heating=


Energy Distribution
[[PbBi_BeamPipeHeatin_2015]]


[[File:TF_PosE_04-28-15.png | 200 px]]
=Converter target properties=
[[File:Positrons2.png | 200 px]]


Angular distribution of positrons


[[File:TF_Theta_04-28-15.png | 200 px]]
[[PbBi_NioWave_TargetProperties_2015]]




=== 2mm thick PbBi, 10 MeV, 1 cm cylindrical incident electron distribution===
=Target thickness optimization=


[[File:ElectronTracks.png| 200 px]][[File:PhotonTracks.png| 200 px]]
==[[PbBi_THickness_CylinderBeam]]==


[[File:ElectronEnergy.png| 200 px]][[File:PhotonEnergy.png| 200 px]]
==[[PbBi_THickness_GaussBeam]]==


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


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


The positron and electron momentum distributions after the PbBi converter are shown below
==Uniform ideal Solenoid==


=== [[PbBi_BeamPipeHeating_w_Solenoid_2015]]===


[[File:4-30-2015_PositronMomentum_2mm.png| 200 px]][[File:4-30-2015_ElectronMomentum_2mm.png| 200 px]]
===[[PbBi_60cmLong_Solenoid_Collection_Efficiency_2015]]===


A comma delimited text file with the above events in the format of
==Positron & Electron event files==


x,y,z,Px,Py,Pz
[[PbBi_PosEventFiles_VaccumGaps_2015]]


in units of cm for distance and MeV for momentum is located at
[[PbBi_PosEventFiles_NoGaps_2016]]


for positrons
==Solenoid Map==


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


Outer Radius =


and
Length =


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


Magnetic Field Map in cylindrical coordinates (Z & R) from Niowave


for electrons
=Rear Window Thickness=


=== 2mm thick PbBi, 10 MeV,  point source===


I was unable to do anything other than a gaussian beam right now,  I will try to do one later
Question:  Will a thicker downstream exit window increase the positron production efficiency by providing more material for a brehm photon to pair produce in?


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


[[File:4-30-2015_BeamPosDelta.png| 200 px]][[File:4-30-2015_ElectronMomentum.png| 200 px]]
Positrons were counted exiting a ideal 0.2 Tesla solenoid that was 15 cm long. A ten MeV electron beam with a 0.5 cm cylindrical radius impinged a 2mm thick PbBi liquid target that had a surface area of 2.54 cm x 2.54 cm.  A 0.25 mm thick stainless steel entrance window was used. 


Target is at -106 mm, entrance SS window is at -108.25 mm , exit SS window is at -103.75 mm, A sensitive detector for positron is placed at Z= +44mm.  The sensitive detector is a cylinder of radius 11.74 cm.
{| border="1"
{| border="1"
| SS Exit WIndow Thickness (mm) || Positrons/Million electrons
|-
|0.0  || 1142,1096,1149,1073,1083 = 1109 +/- 35
|-
| 0.25  || 774,836,800,785,798 = 798 +/- 23
|-
|  0.5    ||  693,704,713,697,715 = 704 +/- 10
|-
|  1.0    ||  587,606,548,592,550 =577 +/- 26
|+
|}


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


;Conclusion 1:  Positron production efficiency improves when the exit window is made thinner


[[File:4-30-2015_PositronMomentum_2mmDelta.png| 200 px]][[File:4-30-2015_ElectronMomentum_2mmDelta.png| 200 px]]
;Conclusion 2 : You loose about 28 +/- 4 % of the positrons in the 0.25 mm thick SS exit window.


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


x,y,z,Px,Py,Pz
==Brem Spectrum==


in units of cm for distance and MeV for momentum is located at
Below is the photon energy distribution (from Brem & pair production) using a 2mm Pb target for two different incident electron energies; 6 and 10 MeV.  The photons are 1 cm downstream of the target and intersection a large forward region.


for positrons
[[File:PbBi_Brem_6-10MeV_4-7-16.png | 200 px]]


http://www2.cose.isu.edu/~foretony/Positrons_2mm10MeVDelta.dat
insert photon spacial distributions


Now move the scoring region downstream to a position representing the location of a NaI detector.


and
=Beam Line Design=


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


=goals for JLab=


for electrons


==Solenoid==


[[Positrons#Simulations]]
[[Positrons#Simulations]]

Latest revision as of 21:39, 8 June 2016

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

Conclusions

  1. A 0.3 (0.6) Tesla Solenoid with a diameter to allow a 9.74 (3.94) cm diameter pipe would collect a positron per thousand incident electrons on a 2mm thick LBE target with 0.25 mm thick SS windows.
  2. A 15 cm long, 0.2 Tesla solenoid with a 3.94 diameter beam pipe would collect a positron per two thousand electrons impinging a 2mm thick LBE target with 0.25 mm thick SS windows.
  3. A 4 Tesla Solenoid will remove beam pipe heating from scattered electrons downstream of the target when using a 3.94 cm diameter beam pipe.

Reports

Niowave_Report_11-30-2015


deadline 4/12/16


Niowave_9-2015

Niowave_10-2015

Niowave_11-2015

Niowave_12-2015

Niowave_1-2016

Niowave_2-2016

Niowave_3-2016

Niowave_4-2016

Niowave_5-2016

Niowave_6-2016

Task List

0.) 34.8 mm pipe, 0.0 -> 0.5 Tesla, E= 6,8,10 MeV.


1.) Create a positron (10,000 positrons) and electron event file containing t,x,y,z,Px,Py,Pz for positrons exiting the solenoid and an incident Gaussian beam 1cm in diameter and with a sigma of 1cm.

compare distributions with and without solenoid.

2.) Determine the back ground when using a 3.48 diameter beam pipe and Solenoid field of 0.2 for a NaI detector placed at

3.) Experiment, install dipole and solenoid in the tunnel.

Beam Pipe Heating

PbBi_BeamPipeHeatin_2015

Converter target properties

PbBi_NioWave_TargetProperties_2015


Target thickness optimization

PbBi_THickness_CylinderBeam

PbBi_THickness_GaussBeam

PbBi_THickness_PntSource

Solenoid

Uniform ideal Solenoid

PbBi_BeamPipeHeating_w_Solenoid_2015

PbBi_60cmLong_Solenoid_Collection_Efficiency_2015

Positron & Electron event files

PbBi_PosEventFiles_VaccumGaps_2015

PbBi_PosEventFiles_NoGaps_2016

Solenoid Map

Inner Radiusu=

Outer Radius =

Length =

Current=

Magnetic Field Map in cylindrical coordinates (Z & R) from Niowave

Rear Window Thickness

Question: Will a thicker downstream exit window increase the positron production efficiency by providing more material for a brehm photon to pair produce in?


Positrons were counted exiting a ideal 0.2 Tesla solenoid that was 15 cm long. A ten MeV electron beam with a 0.5 cm cylindrical radius impinged a 2mm thick PbBi liquid target that had a surface area of 2.54 cm x 2.54 cm. A 0.25 mm thick stainless steel entrance window was used.

Target is at -106 mm, entrance SS window is at -108.25 mm , exit SS window is at -103.75 mm, A sensitive detector for positron is placed at Z= +44mm. The sensitive detector is a cylinder of radius 11.74 cm.

SS Exit WIndow Thickness (mm) Positrons/Million electrons
0.0 1142,1096,1149,1073,1083 = 1109 +/- 35
0.25 774,836,800,785,798 = 798 +/- 23
0.5 693,704,713,697,715 = 704 +/- 10
1.0 587,606,548,592,550 =577 +/- 26


Conclusion 1
Positron production efficiency improves when the exit window is made thinner
Conclusion 2
You loose about 28 +/- 4 % of the positrons in the 0.25 mm thick SS exit window.

Background studies

Brem Spectrum

Below is the photon energy distribution (from Brem & pair production) using a 2mm Pb target for two different incident electron energies; 6 and 10 MeV. The photons are 1 cm downstream of the target and intersection a large forward region. 

insert photon spacial distributions

Now move the scoring region downstream to a position representing the location of a NaI detector.

Beam Line Design

PbBi_BeamLine_Elements

goals for JLab

Positrons#Simulations

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