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


=Task List=
=Conclusions=


1.) new electron and positron files for the case of two 0.25 mm thick SS windows around the PbBi 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.
# 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.


2.) Determine electron energy deposition in SS pipe per cm^2 of pipe surface area for pipes with a radius of 34.8, 47.5, 60.2, 72.9, and 97.4 mm and thickness of 5mm along the z-axis.
=Reports=


3.) Insert uniform B-field that can be scaled from 0 to 0.3 and 1 Telsa.
[[Niowave_Report_11-30-2015]]


=Beam Pipe Heating=


deadline 4/12/16


[[BeamPipeHeating_4mmthick_PbBi_PositronTarget]]


==[[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]]==


==Results Table==
=Task List=


0.) 34.8 mm pipe, 0.0 -> 0.5 Tesla, E= 6,8,10 MeV.
{| border="1"
{| border="1"
| Beam Pipe Radius (mm) || Hot Spot (<math>keV/cm^2/e^-</math>)
|-
| 34.8   || 5
|-
|  47.5   ||
|-
|  60.2  ||
|-
|  72.9    ||
|-
|  97.4    ||
|-
|}


=Converter target properties=


Definition of Lead Bismuth
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.


1cm diameter target
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
2 mm thick PbBi


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


=Beam Pipe Heating=


Desire to know
[[PbBi_BeamPipeHeatin_2015]]


Emmittance (mrad * mm)
=Converter target properties=


dispersion (Delta P/P)  (mradian/1000th  mm/1000th)


of electrons after the PbBi target.
[[PbBi_NioWave_TargetProperties_2015]]




pole face rotation in vertical plane.
=Target thickness optimization=


=G4BeamLine and MCNPX=
==[[PbBi_THickness_CylinderBeam]]==


==[[PbBi_THickness_GaussBeam]]==
==Target thickness optimization==


===[[PbBi_THickness_GaussBeam]]===
== [[PbBi_THickness_PntSource]]==
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")
=Solenoid=


2. Twiss parameters
==Uniform ideal Solenoid==


3. Ellipse centroid for longitudinal phase portrait
=== [[PbBi_BeamPipeHeating_w_Solenoid_2015]]===


4. sqrt(beta*emittance) and sqrt(gamma*emittance) - half sizes of the projections of the ellipses on the coordinate and divergence axes respectively.
===[[PbBi_60cmLong_Solenoid_Collection_Efficiency_2015]]===


Electrons - RMS
==Positron & Electron event files==


[[File:Ed1.png| 400 px]]
[[PbBi_PosEventFiles_VaccumGaps_2015]]


Electrons - 68.2% core
[[PbBi_PosEventFiles_NoGaps_2016]]


[[File:Ed2.png| 400 px]]
==Solenoid Map==


Positrons - RMS
Inner Radiusu=


[[File:Pd1.png| 400 px]]
Outer Radius =


Positrons - 68.2% core
Length =


[[File:Pd2.png| 400 px]]
Current=


=== [[PbBi_THickness_CylinderBeam]]===
Magnetic Field Map in cylindrical coordinates (Z & R) from Niowave
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")
=Rear Window Thickness=


2. Twiss parameters


3. Ellipse centroid for longitudinal phase portrait
Question:  Will a thicker downstream exit window increase the positron production efficiency by providing more material for a brehm photon to pair produce in?


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
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. 


[[File:E1.png| 400 px]]
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.
 
Electrons - 68.2% core
{| border="1"
 
{| border="1"
[[File:E2.png| 400 px]]
| SS Exit WIndow Thickness (mm) || Positrons/Million electrons
 
|-
Positrons - RMS
|0.0  || 1142,1096,1149,1073,1083 = 1109 +/- 35
 
|-
[[File:P1.png| 400 px]]
| 0.25  || 774,836,800,785,798 = 798 +/- 23
 
|-
Positrons - 68.2% core
|  0.5    ||   693,704,713,697,715 = 704 +/- 10
 
|-
[[File:P2.png| 400 px]]
|  1.0    ||   587,606,548,592,550 =577 +/- 26
 
|+
=== [[PbBi_THickness_PntSource]]===
|}
 
Electrons and Positrons after 2mm of LBE:
 
Electrons:
 
[[File:e01.png| 200 px]][[File:e02.png| 200 px]]
 
Positrons:
 
[[File:p01.png| 200 px]][[File:p02.png| 200 px]]
 
===Energy Deposition in Target system (Heat)===




[[File:ElectronTracks.png| 200 px]][[File:PhotonTracks.png| 200 px]]
;Conclusion 1: Positron production efficiency improves when the exit window is made thinner


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


MCNPX simulations of energy deposition into different cells are below. There is a slight overestimate (they add up to about 120%). Positrons contribute less than 1% of electrons' contribution. No magnetic filed is assumed.
=Background studies=


[[File:Model.png| 400 px]]
==Brem Spectrum==


[[File:Tablen1.png| 200 px]]
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.


[[File:Tablen2.png| 200 px]]
[[File:PbBi_Brem_6-10MeV_4-7-16.png | 200 px]]


==Solenoid==
insert photon spacial distributions


 
Now move the scoring region downstream to a position representing the location of a NaI detector.
Inner Radiusu=
 
Outer Radius =
 
Length =
 
Current=
 
Magnetic Field Map in cylindrical coordinates (Z & R) from Niowave


=Beam Line Design=
=Beam Line Design=

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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