G4Beamline PbBi

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

Converter target properties

Definition of Lead Bismuth


1cm diameter target 2 mm thick PbBi

0.5 Tesla solenoid


Desire to know

Emmittance (mrad * mm)

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

of electrons after the PbBi target.


pole face rotation in vertical plane.

G4BeamLine and MCNPX

Target thickness optimization

PbBi_THickness_GaussBeam

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

PbBi_THickness_CylinderBeam

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

PbBi_THickness_PntSource

Electrons and Positrons after 2mm of LBE:

Electrons:

E1.pngE2.png

Positrons:

P1.pngP2.png

Energy Deposition in Target system (Heat)

Layout.png

ElectronTracks.pngPhotonTracks.png

ElectronEnergy.pngPhotonEnergy.png

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.

Model.png

Tablen1.png

Tablen2.png

Solenoid

Inner Radiusu=

Outer Radius =

Length =

Current=

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

Beam Line Design

PbBi_BeamLine_Elements

goals for JLab

Positrons#Simulations