G4Beamline PbBi

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

Task List

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

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.

3.) Insert uniform B-field that can be scaled from 0 to 0.3 and 1 Telsa.


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:

E01.pngE02.png

Positrons:

P01.pngP02.png

Energy Deposition in Target system (Heat)

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