Optimization of Positron Capturing

• Thickness of the Tungsten target: 1.25 mm
• Beam size at Tungsten target: Gaussian, $\sigma_{x,y} = 3~mm$

Optimization with ELEGANT Simulation on the Region from Gun Exit to Tungsten Target

Emittance: $\epsilon_{x,y} = 13~\mu m$ (Not sure yet, need to be calculated)

Average Peak $Q = 14~pC$

Beam Energy: $10~MeV$

Energy Spread: $\sigma_{\delta}=4.23%$

Alpha Function: $\alpha =$

Beta Function: $\beta =$

RMS longitudinal Bunch Length: $\sigma_{z} = 10.6~ps$

GEANT4 Simulation for 2 mm W-Target

Thickness of the Tungsten target: 2 mm

Electron Beam:

Beam size at Tungsten target: Gaussian, $\sigma_{x,y} = 3~mm$

Beam divergence at target: 0

Beam Energy: $10~MeV$

Energy Spread: $\sigma_{\delta}=4.23%$

A volume called "detector" is placed at the of the W-target to get the information on the only of the outgoing positrons from the W-target. Followings are from "detector".

Phase Spaces of e+ Created

Phase space for positrons coming out W-target. Include 100 % of the particles

X phase space

Y phase space

Phase Spaces ellipse of 39% particles

Total positrons created are 75483, and 39 % of them will be 29438. Core 39% area of the phase space ellipse is RMS emittance, $\epsilon_{rms}$.

a = 3.791; b = 1.189;

c = 3.791; d = 1.189;