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| | [[Niowave_Report_11-30-2015]] | | [[Niowave_Report_11-30-2015]] |
| − | =Task List=
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| | | | |
| − | 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.
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| | | | |
| − | compare distributions with and without solenoid.
| + | deadline 4/12/16 |
| | | | |
| − | 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
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| | | | |
| − | 3.) Experiment, install dipole and solenoid in the tunnel.
| + | ==[[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]]== |
| | | | |
| − | =Beam Pipe Heating= | + | =Task List= |
| | | | |
| | + | 0.) 34.8 mm pipe, 0.0 -> 0.5 Tesla, E= 6,8,10 MeV. |
| | | | |
| − | A 10 MeV electron beam with a radius of 0.5 cm was incident on a 2 mm thick PbBi target. The target is positioned at Z = -902 mm.
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| | | | |
| | + | 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. |
| | | | |
| − | [[File:TF_Niowave_SolenoidDesign_9-3-15.png | 200 px]] [[File:TF_Niowave_SolenoidDesign_9-11-15.png | 200 px]]
| + | 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. |
| − | {| border="1"
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| − | |Element || dimension
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| − | |-
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| − | | Inner beam pipe radius || 1.74 cm
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| − | |-
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| − | | Inner beam pipe thickness || 0.165 cm
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| − | |-
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| − | |water jacket thickness || 0.457 cm
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| − | |-
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| − | | outer beam pipe radius || 2.362 cm
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| − | |-
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| − | | outer beam pipe thickness || 0.165 cm
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| − | |-
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| − | | Solenoid inner radius || 2.527 cm
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| − | |-
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| − | | Solenoid outer radius || 4.406 cm
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| − | |}
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| − | | |
| − | | |
| − | ==Max power deposited in beam pipe from uniform beam heating==
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| − | | |
| − | If you assume a 1mA beam then the beam power incident on the target is
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| − | | |
| − | Beam Power = E(MeV) <math> \cdot </math>I (<math>\mu</math> A) = 10 MeV <math>\times</math> 1000 mA = 10 kW
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| − | | |
| − | If the beam does not interact with the target and all the beam power is distributed uniformly along a 100 cm long beam pipe with a diameter of 3.48 cm then the power deposited per area would be
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| − | | |
| − | :<math>10000 \mbox{W} \times \frac{1}{100 \mbox{cm}}\times \frac{1}{ \pi \times 3.48 \mbox {cm} } = 2.3 \frac{\mbox{W}}{\mbox{cm}^2}</math>
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| − | | |
| − | | |
| − | A simulation predicts that about 8 out of 20 electrons will interact with the target and intercept a 34.8 mm diameter beam pipe surrounding the target.
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| − | | |
| − | | |
| − | :<math>\mbox{P}_{\mbox{max}} = \left ( \frac{2}{5} \right ) 2.3 \frac{\mbox{W}}{\mbox{cm}^2}< 1 \frac{\mbox{W}}{\mbox{cm}^2}</math>
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| − | | |
| − | '''BUT the beam does not intersect the pipe uniformly and instead can have a hot spot.'''
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| − | | |
| − | ==Heating along the Z-axis==
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| − | | |
| − | GEANT4 predicts that scattered electrons, photons, and positrons (mostly scattered electrons) deposit
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| − | | |
| − |
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| − | {| border="1"
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| − | | [[File:BeamPipeDepEmev_34.8_082915.png |200px]] || [[File:MCNPXBeamPipeDepEmev_34.8_090315.png |200px]]
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| − | |+ Energy deposited (MeV) in a 1 m long 3.48 cm diameter beam pipe surrounding a 2 mm target located at Z=-900 mm.
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| − | |}
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| − | | |
| − | According to the above figure, GEANT4 predicts a total of <math>3.08\times 10^7</math> MeV (the integral adds up the energy in each 1cm bin) of energy will be deposited in
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| − | a 1m long beam pipe surrounding a 2 mm thick PbBi target located at Z=-902 mm when 20 million electrons impinge the target. The peak energy deposition is 0.3 MeV/e<math>^-</math>
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| − | | |
| − | If this energy were uniformly distributed along the 5 mm thick beam pipe having a diameter of 3.48 cm then I would see
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| − | | |
| − | :<math>3.08 \times 10^{10} \mbox{keV} \times \frac{1}{100 \mbox{cm}}\times \frac{1}{ \pi \times 3.48 \mbox {cm} } \times \frac{1}{2 \times 10^7 \mbox{e}^-}=3.5\frac{\mbox{keV}}{\mbox{cm}^2 \;\;\mbox{e}^-}</math>
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| − | | |
| − | | |
| − | | |
| − | if you assume a 1 mA beam of electrons then this becomes
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| − | | |
| − | <math>\left ( \frac{3.5 \; \mbox{W} }{ \mbox{cm}^2 } \right) </math>
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| − | | |
| − | I converted the above histogram to deposited power by 1000 mA, divide by the number of incident electrons, divide by the circumference of the beam pipe, convert the number of electrons to Coulombs, and use a unit conversion from MeV to W-s per MeV.
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| − | | |
| − | <math>\left(Counts \frac{\mbox{MeV}}{\mbox{cm}}\right) \times \left( \frac{1}{2 \times 10^{7} \mbox{e}^-} \right ) \times \left( \frac{1}{ \pi \times 3.48 \mbox{cm}} \right ) \times \left( \frac{1. \times 10^{-3}\mbox{ C}}{\mbox{s} }\right )\times \left( \frac{\mbox{e}^- }{1.6 \times 10^{-19}\mbox{ C}}\right ) \left( \frac{1.6 \times 10^{-13}\mbox{W} \cdot \mbox{ s}}{\mbox{MeV} }\right ) \times </math>
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| − | | |
| − | If you use the above factors to weight the histogram, then the figure below shows that GEANT4 predicts a power deposition density of <math>= 4 \frac{W}{cm^2}</math>, 1 cm downstream of the target.
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| − | Back scattered electrons appear to create the hottest spot of <math>= 15 \frac{W}{cm^2}</math> about 1cm upstream of the target.
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| − |
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| − | {| border="1"
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| − | | [[File:BeamPipeDepE_34.8mmA_082815.png| 200 px]] ||[[File:BeamPipeDepE_34.8mmB_082815.png| 200 px]]
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| − | |-
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| − | | Power Deposition Zoomed in and 902 mm offset applied ||Power deposition over the 1 m long beam pipe
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| − | |-
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| − | |}
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| | | | |
| | + | =Beam Pipe Heating= |
| | | | |
| − | | + | [[PbBi_BeamPipeHeatin_2015]] |
| − | | |
| − | [[BeamPipeHeating_4mmthick_PbBi_PositronTarget]] | |
| − | | |
| − | ==Unit conversion==
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| − | | |
| − | The energy deposited by photon, electrons, and positrons is predicted by GEANT4 and recorded in energy units of keV per incident electron on the PbBi target. To convert this deposited energy to a power you need to assume a beam current. Assuming 1 beam current of 1 mA, the conversion is given easily as
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| − | | |
| − | <math>\left( \frac{\mbox{keV}}{\mbox{cm}^2 \mbox{e}^-}\right) \times \left( \frac{ \mbox{e}^-}{1.6 \times 10^{-19}\mbox{C}} \right ) \times \left( \frac{1 \times 10^{-3} \mbox{C}}{\mbox{s}} \right ) \times \left( \frac{1.6 \times 10^{-16}\mbox{W} \cdot \mbox{ s}}{\mbox{keV} }\right )</math>
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| − | | |
| − | <math>\left( \frac{\mbox{keV}}{\mbox{cm}^2 \mbox{e}^-}\right) = \left( \frac{\mbox{W} }{\mbox{cm}^2 } \right )</math>
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| − | | |
| − | ==Results Table==
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| − | | |
| − |
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| − | {| border="1"
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| − | {| border="1"
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| − | | Beam Pipe Diameter (mm) || Hot Spot (<math>MeV/e^-</math>)|| Hot Spot (<math>keV/cm^2/e^-</math>)
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| − | |-
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| − | | 34.8 || 0.35
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| − | |-
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| − | | 47.5 || 0.24
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| − | |-
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| − | | 60.2 || 0.20
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| − | |-
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| − | | 72.9 || 0.16
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| − | |-
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| − | | 97.4 || 0.12
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| − | |-
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| − | |}
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| | | | |
| | =Converter target properties= | | =Converter target properties= |
| | | | |
| − | Definition of Lead Bismuth
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| − |
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| − |
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| − | 1cm diameter target
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| − | 2 mm thick PbBi
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| − |
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| − | 0.5 Tesla solenoid
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| | | | |
| | + | [[PbBi_NioWave_TargetProperties_2015]] |
| | | | |
| − | Desire to know
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| | | | |
| − | Emmittance (mrad * mm)
| + | =Target thickness optimization= |
| | | | |
| − | dispersion (Delta P/P) (mradian/1000th mm/1000th)
| + | ==[[PbBi_THickness_CylinderBeam]]== |
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| − | of electrons after the PbBi target.
| + | ==[[PbBi_THickness_GaussBeam]]== |
| | | | |
| | + | == [[PbBi_THickness_PntSource]]== |
| | | | |
| − | pole face rotation in vertical plane.
| + | =Solenoid= |
| | | | |
| − | =G4BeamLine and MCNPX= | + | ==Uniform ideal Solenoid== |
| | | | |
| − |
| + | === [[PbBi_BeamPipeHeating_w_Solenoid_2015]]=== |
| − | ==Target thickness optimization== | |
| | | | |
| − | ===[[PbBi_THickness_GaussBeam]]=== | + | ===[[PbBi_60cmLong_Solenoid_Collection_Efficiency_2015]]=== |
| | | | |
| − | === [[PbBi_THickness_CylinderBeam]]=== | + | ==Positron & Electron event files== |
| | | | |
| − | === [[PbBi_THickness_PntSource]]===
| + | [[PbBi_PosEventFiles_VaccumGaps_2015]] |
| | | | |
| − | ===Energy Deposition in Target system (Heat)===
| + | [[PbBi_PosEventFiles_NoGaps_2016]] |
| | | | |
| − | | + | ==Solenoid Map== |
| − | [[File:ElectronTracks.png| 200 px]][[File:PhotonTracks.png| 200 px]]
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| − | | |
| − | [[File:ElectronEnergy.png| 200 px]][[File:PhotonEnergy.png| 200 px]]
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| − | | |
| − | 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.
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| − | | |
| − | [[File:Model.png| 400 px]]
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| − | | |
| − | [[File:Tablen1.png| 200 px]]
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| − | | |
| − | [[File:Tablen2.png| 200 px]]
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| − | | |
| − | ==Solenoid==
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| − | | |
| − | ===Uniform ideal Solenoid===
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| − | | |
| − | ==== Beam Pipe Heating with Solenoid====
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| − | | |
| − | The energy deposited by electrons scattered into a 3.48 diameter stainless steel beam pipe (1.65 mm thick) from a PbBi target as a function of a uniform Solenoidal magnetic field.
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| − | | |
| − |
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| − | {| border="1"
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| − | {| border="1"
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| − | | B-field (Tesla) || Hot Spot (<math>MeV/e^-</math>)
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| − | |-
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| − | | 0.0 || 0.35
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| − | |-
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| − | | 0.3 || 0.35
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| − | |-
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| − | | 1.0 || 0.35
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| − | |-
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| − | | 1.5 || 0.22
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| − | |-
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| − | | 2.0 || 0.10
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| − | |-
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| − | | 4.0 || 0.002
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| − | |+
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| − | |}
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| − | | |
| − | | |
| − | To convert this deposited energy per incident electron on the target to a heat load in the pipe you need to divide by the area of the pipe.
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| − | | |
| − | A histogram is filled with 1 cm bins along the Z axis. The surface area becomes <math>1 cm \times 2 \pi 3.48/2 = 10.933 cm^2</math>. The beam pipe diameter assumed is 3.48 cm.
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| − | | |
| − | When filling the histogram binned 1 cm in Z, you should weight it by the amount of depositred energy divided by the circumference of the pipe and divided by the number of incident electrons on the target (5 million). The energy units are converted to keV by multiplying the numberator by 100 or in this case dividing by 5000 instead of 5 million.
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| − | | |
| − | | |
| − | TH1F *T00N=new TH1F("T00N","T00N",100,-1000.5,-0.5)
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| − | | |
| − | Electrons->Draw("evt.EoutPosZ>>T00N","evt.DepE/10.088/5000")
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| − | | |
| − | | |
| − | | |
| − | To convert From Mev/ e- to kW/cm^2 assuming a current of 1mA (10^-3 C/s) you
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| − | | |
| − | <math>\left( \frac{\mbox{MeV}}{\mbox{cm}^2 \mbox{e}^-}\right) \times \left( \frac{ \mbox{e}^-}{1.6 \times 10^{-19}\mbox{C}} \right ) \times \left( \frac{1 \times 10^{-3} \mbox{C}}{\mbox{s}} \right ) \times \left( \frac{1.6 \times 10^{-13}\mbox{W} \cdot \mbox{ s}}{\mbox{MeV} }\right )</math>
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| − | | |
| − | <math>\left( \frac{\mbox{keV}}{\mbox{cm}^2 \mbox{e}^-}\right) = \left( \frac{\mbox{W} }{\mbox{cm}^2 } \right )</math>
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| − | | |
| − | | |
| − | | |
| − |
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| − | {| border="1"
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| − | | [[File:BeamPipeDepEmev-vs-B.png |200px]] || [[File:BeamPipeDepPower-vs-B.png |200px]]|| [[File:BeamPipeDepPower-vs-lowB.png |200px]]
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| − | |+ Energy deposited (MeV) along a 1 m long beam pipe of stainless steel 1.65 mm thick.
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| − | |}
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| − | | |
| − | With SS windows
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| − | Positrons->Draw("sqrt(evt.BeamPosPosX*evt.BeamPosPosX+evt.BeamPosPosY*evt.BeamPosPosY)","evt.BeamPosMomZ>0 && evt.BeamPosPosZ>-500 && sqrt(evt.BeamPosPosX*evt.BeamPosPosX+evt.BeamPosPosY*evt.BeamPosPosY)<97.4/2");
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| − | | |
| − | ====Positron Collection rates with '''60 cm''' long Solenoid====
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| − |
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| − | {| border="1"
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| − | | [[File:PositronEventWithSolenoid_09-16-15A.png|200px]] ||[[File:PositronEventWith0.3Solenoid_09-16-15A.png|200px]]
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| − | |-
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| − | | When the solenoid is 1.5 Tesla, a 10 MeV electron produces a 6.5 MeV photon that pair produces a 4.4 MeV positron and a 1 MeV electron || Same Event but this time the solenoid is 0.3 Tesla and the positron hits the beam pipe, annihilates and makes two 511 keV photons
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| − | |+ Sample Positron Production Events
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| − | |}
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| − |
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| − | {| border="1"
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| − | | [[File:PositronEventWithSolenoid_09-16-15B.png|200px]] ||[[File:PositronEventWith0.3Solenoid_09-16-15B.png|200px]]
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| − | |-
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| − | | When the solenoid is set to 1.5 Tesla, a 10 MeV electron produces three photons less than 1 MeV in the target, two of them compton scatter in the beam pipe || The same event but this time the electron produces only 1 photon than ionizes in the target
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| − | |+ Sample Brem event producing no positrons
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| − | |}
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| − | | |
| − | | |
| − | With SS windows
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| − | Positrons->Draw("sqrt(evt.BeamPosPosX*evt.BeamPosPosX+evt.BeamPosPosY*evt.BeamPosPosY)","evt.BeamPosMomZ>0 && evt.BeamPosPosZ>-500 && sqrt(evt.BeamPosPosX*evt.BeamPosPosX+evt.BeamPosPosY*evt.BeamPosPosY)<97.4/2");
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| − | | |
| − |
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| − | {| border="1"
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| − | {| border="1"
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| − | | B-field (Tesla) || || 34.8 mm diameter pipe || 47.5 || 60.2 || 72.9 || 97.4
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| − | |-
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| − | | 0.0 || 0.35 || 1,2,4,4,5 || 2,3,4,4,6 || 4,4,6,7,9 || 6,8,9,10,11 || 16,14,15,16,17
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| − | |-
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| − | | 0.1 || ||225,236,250,246,249=241<math> \pm</math> 10 || 282,282,293,294,306=291<math> \pm</math> 10 || 373,366,370,364,373=369<math> \pm</math> 4 || 451,437,440,438,451=443<math> \pm</math> 7 || 602,584,563,558,570=575<math> \pm</math> 18
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| − | |-
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| − | | 0.3 || 0.35 || 626,619,596,619,611 =614<math> \pm</math> 11|| 720,726,706,730,717=720<math> \pm</math> 9|| 871,864,840,841,834 =850<math> \pm</math> 16|| 987,968,939,943,952 =958<math> \pm</math> 20|| 1118,1106,1069,1067,1080=1088<math> \pm</math> 23
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| − | |-
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| − | | 0.6 || ||929,935,949,969,961=949<math> \pm</math> 17 ||1022,1031,1046,1059,1052 =1042<math> \pm</math> 15 || 1120,1130,1152,1154,1146 =1140<math> \pm</math> 15|| 1168,1184,1210,1221,1206 =1198<math> \pm</math> 21|| 1212, 1218,1240,1254,1242=1233<math> \pm</math> 18
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| − | |-
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| − | | 1.0 || 0.35 ||1117,1085,1083,1061,1085=1086<math> \pm</math> 20 || 1188,1154,1140,1111,1134=1145<math> \pm</math> 28||1225,1190,1178,1149,1172 =1183<math> \pm</math> 28||1243.1208,1195,1164,1184=1199<math> \pm</math> 30|| 1252,1219,1206,1178,1200=1211<math> \pm</math> 27
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| − | |-
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| − | | 1.5 || 0.22 ||
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| − | |-
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| − | | 2.0 || 0.10 ||1198,1210,1215,1223,1176=1204<math> \pm</math> 18 || 1216,1227,1235,1241,1196 =1223<math> \pm</math> 18|| 1237,1243,1252,1257,1214=1241<math> \pm</math> 17|| 1249,1252,1262,1266,1225 =1251<math> \pm</math> 16|| 1257,1262,1270,1276,1234=1260<math> \pm</math> 16
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| − | |-
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| − | | 4.0 || 0.002 ||
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| − | |+
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| − | |}
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| − | | |
| − | | |
| − |
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| − | {| border="1"
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| − | | [[File:PositronRates-vs-SolenoidField_10-1-15.png |200px]]
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| − | |+ Positron Rates -vs- Solenoid Field for 2mm thick PbBi target and several Beam pipe diameters
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| − | |}
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| − | | |
| − | ===Positron & Electron event files===
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| − | | |
| − | Event files were generated assuming an ideal solenoid having an inner radius of 2.527 cm surrounding a beam pipe with a radius of 1.74 cm. Electrons impinge a 2mm thick PbBi liquid target that has a surface area of 2.54 cm x 2.54 cm. Stainless steel windows 0.25 mm thick sandwhich the PbBi target at locations Z= -90.325 and Z= -89.875 cm. The target is located at Z =-90.1 cm and the beam begins 20 cm upstream at Z = -110.1 cm. The incident electron beam is a 0.5 cm radius cylinder.
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| − | | |
| − | ====Positrons exiting the Solenoid====
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| − | | |
| − | The solenoid design has changed such that the max field is 0.20 Tesla (0.22) and its length is 150 mm.
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| − | | |
| − | | |
| − | | |
| − |
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| − | {| border="1"
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| − | | [[File:TF_Niowave_SolenoidDesign_12-04-15.png | 200 px]] || [[File:TF_LBEtarg1_1-12-16.png | 200 px]]|| [[File:TF_LBEposEvent_1-12-16.png | 200 px]]
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| − | | |
| − | |-
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| − | | Overall Target layout || Closeup of Target Simulation Geometry. The center of the 0.25mm thick stainless steel windows are a distance of 2.25 mm from the center of the LBE target. <math>d_{USS} = d_{DSS} =</math> 2.25 mm, <math>t_{LBE}=2</math> mm, <math>t_{SS} =</math> .25 mm. || An example positron production event. The yellow lines represents a sensitive detector used to record all positron events. The red line represents the incident 10 MeV electron that produces two bremsstrahlung photons shown in green. The first photon has an energy of 2.151 MeV and pair produces in the stainless steel window. The second photon has an energy of 1.393 MeV and exits the system without interacting. The first photon is created at time t= 3.323 ns. The first photon produces a 234.6 keV electron and a 894.2 keV positron at time t=3.336 ns. Only the positron has enough energy to exit the stainless steel window.
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| − | |+ Apparatus
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| − | |}
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| − | | |
| − | | |
| − | In other words I should generate position and momentum files for positrons and electrons at the Z location 15 cm downstream from the middle of the LBE target and within a 3.48 cm diameter beam pipe.
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| − | | |
| − | /vis/viewer/zoom 2
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| − | | |
| − | /gps/pos/centre 0.0 0.0 -150.
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| − | | |
| − | /vis/viewer/panTo -90.1 0 cm
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| − | | |
| − | /vis/viewer/reset
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| − | | |
| − | | |
| − | Twenty (20) million incident electrons with an energy of 10 MeV and forming a cylindrical beam with a 0.5 cm radius cylinder impinged a 2mm thick LBE target located at Z = -106 mm. The Z location of positrons exiting the beam pipe at the end of the 15 cm long solenoid is 44 mm. The positrons are 150.00 mm from the middle of the LBE target (Z=44mm).
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| − | | |
| − | A space delimited text file with the above events in the format of
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| − | | |
| − | PID, x(mm),y,z,Px,Py,Pz(MeV),t(ns)
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| − | | |
| − | in units of cm for distance and MeV for momentum is located at
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| − | | |
| − | for positrons
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| − | | |
| − | http://www2.cose.isu.edu/~foretony/Positrons_2mm10MeVCyl.dat
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| − | | |
| − | | |
| − | and
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| − | | |
| − | http://www2.cose.isu.edu/~foretony/Electrons_2mm10MeVCyl.dat
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| − | | |
| − | The file below contains all the positrons that were created at the target
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| − | | |
| − | format
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| − | | |
| − | | |
| − | A space delimited text file with the above events in the format of
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| − | | |
| − | Initial electron (x,y,z,Px,Py,Pz), Final electron (t,x,y,z,Px,Py,Pz), Positron location after leaving LBE target (t,x,y,z,Px,Py,Pz),Location of positron as it exits a SS window (t,x,y,z,Px,Py,Pz). Units are ns, mm, MeV/c.
| |
| − | | |
| − | http://www2.cose.isu.edu/~foretony/AllPositrons_2mm10MeVCyl.dat
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| − | | |
| − |
| |
| − | {| border="1"
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| − | | [[File:PositronTime_1-10-16.png|200px]] ||
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| − | |-
| |
| − | | Particle flight times for 20 million incident electrons on a 0.2mm thick LBE target with 0.25 mm thick stainless steel windows (no material exists after the last stainless steel window, only vacuum). The time an electron brems in the target (EscatTime) is shown in black. The time a positron is created in the target (PosTime) is shown in blue. The time a positron has traveled 15 cm traversing a uniform 0.2 Tesla Solenoidal field (PosBeamTime) is shown in fuchsia. The field exists throughout the entire world. PosBeamTimeCuts are positrons that are constrained to a beam pipe diameter of 34.8 mm. Positrons are traveling about the speed of light (30 cm/ns) so after 15 cm they arrived 0.5 nsec after the initial electron beam impinges the target.
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| − | |+ Positron Distributions
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| − | |}
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| − | | |
| − | | |
| − | ====Positrons and Electrons after the SS Exit window====
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| − | | |
| − | The same configuration as the previous subsection except that the 1mm thick sensitive detector is placed at
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| − | Z = -100.5 mm. Most of the electrons exit at Z = -100.9 mm.
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| − | | |
| − | A space delimited text file with the above events in the format of
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| − | | |
| − | PID, x(mm),y,z,Px,Py,Pz(MeV),t(ns)
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| − | | |
| − | in units of cm for distance and MeV for momentum is located at
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| − | | |
| − | for positrons
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| − | | |
| − | http://www2.cose.isu.edu/~foretony/PositronsAtExitWindow.dat
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| − | | |
| − | | |
| − | and
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| − | | |
| − | http://www2.cose.isu.edu/~foretony/ElectronsAtExitWindow.dat
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| − | | |
| − | ===Solenoid Map===
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| | | | |
| | Inner Radiusu= | | Inner Radiusu= |
| Line 392: |
Line 83: |
| | Magnetic Field Map in cylindrical coordinates (Z & R) from Niowave | | Magnetic Field Map in cylindrical coordinates (Z & R) from Niowave |
| | | | |
| − | ===Rear Window Thickness===
| + | =Rear Window Thickness= |
| | | | |
| | | | |
| Line 419: |
Line 110: |
| | ;Conclusion 1: Positron production efficiency improves when the exit window is made thinner | | ;Conclusion 1: Positron production efficiency improves when the exit window is made thinner |
| | | | |
| − | ;Conclusion 2 : You loose about 28 +/- % of the positrons in the 0.25 mm thick SS exit window. | + | ;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. |
| | + | |
| | + | [[File:PbBi_Brem_6-10MeV_4-7-16.png | 200 px]] |
| | + | |
| | + | insert photon spacial distributions |
| | + | |
| | + | Now move the scoring region downstream to a position representing the location of a NaI detector. |
| | | | |
| | =Beam Line Design= | | =Beam Line Design= |
