Hybrid source: positrons distribution

(Robert Chehab’s graphic and summary)
In the following we took:

$p_z=cos\phi=\frac{P_z}{P}$
$p_y=sin\phi sin\theta=\frac{P_y}{P}$
$p_x=sin\phi cos\theta=\frac{P_x}{P}$

For both case (10 GeV and 5 GeV) the inital x and y electron distribution follow (ROOT syntax)

x=gRandom->Gaus(0,2.5e-3)/sqrt(2.); // gaussian centered x=0 with rms_x=2.5mm
y=gRandom->Gaus(0,2.5e-3)/sqrt(2.); // gaussian centered y=0 whith rms_y=2.5mm

Electron beam energy : 10 GeV

• Crystal thickness : 0.1 cm
• Distance between amorphous and amorphous : 2m
• Amorphous thickness : 0.8 cm

(initial particles impinging on the crystal = 5000 macro e-)

Positrons phase space after the amorphous target

Energy (no energy cut)

Energy (below 400 MeV):

X:

Y:

Px:

Py:

Positrons spatial distribution after capture section (AMD)

AMD caracteristics

• AMD length: 50 cm
• B = B0/(1+alpha*z) with B0=6 Tesla and alpha=22/m
• Transverse phase space of the positrons from the target.
We apply a cut in the radius, r<20mm corresponding to the aperture of the
pre-accelerating cavities.

In blue after the amorphous and in red after the AMD

Angle distribution

$\phi=acos\frac{P_z}{P}$

Electron beam energy : 5GeV

• Crystal thickness : 0.14 cm
• Distance between amorphous and amorphous : 2m
• Amorphous thickness : 1 cm

(initial particles impinging on the crystal = 6000 macro e-)

Positrons phase space after the amorphous target

Energy (no energy cut):

Energy (below 200 MeV):

X:

Y:

Px:

Py:

Positrons spatial distribution after capture section (AMD)

AMD caracteristics

• AMD length: 50 cm
• B = B0/(1+alpha*z) with B0=6 Tesla and alpha=22/m
• Transverse phase space of the positrons from the target.
We apply a cut in the radius, r<20mm corresponding to the aperture of the
pre-accelerating cavities.

In blue after the amorphous and in red after the AMD

Angle distribution

$\phi=acos\frac{P_z}{P}$

EXTRA …
(thanks to Laurent Garnier Qt implementation see http://users.lal.in2p3.fr/garnier/G4QtTutorial.html#interface)

g4movie2

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