Difference between revisions of "July2012PosSimulation"

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=== Sharp drop issue ===
 
=== Sharp drop issue ===
  
−
The Y-position distribution of the beam shown in Figure XXXX has a sharp drop in the region between -25.8 mm and -27.2 mm that corresponds to the boundary of the target T1.  , which makes a 1.4 mm wide strip.
+
The Y-position distribution of the beam shown in Figure XXXX has a sharp drop in the region between -25.8 mm and -27.2 mm that corresponds to the boundary of the target T1.  Figure YYY shows the geometry of the target T1 and the sensitive detector DDNT1.  , which makes a 1.4 mm wide strip.
  
 
The distance from the back of T1 to the detector is 25.8 mm. DDNT1T1 is 1.016 mm thick, and the projected thickness of T1's thickness on the detector DDNT1 is 1.4 mm (<math>1.016 \sqrt{2}=1.44</math>).
 
The distance from the back of T1 to the detector is 25.8 mm. DDNT1T1 is 1.016 mm thick, and the projected thickness of T1's thickness on the detector DDNT1 is 1.4 mm (<math>1.016 \sqrt{2}=1.44</math>).

Revision as of 22:28, 24 April 2013

In G4beamline manual "The electromagnetic processes of these physics lists are advertised to be valid above a few hundred electron Volts; Geant4 has a set of low energy electromagnetic processes, indicated by a suffix “_EMX” in the physics list name."

2 MeV Positrons

Measured Electron energy distribution at 10 MeV on 1.mm target

Simulation steps

1.) GEANT4 Simulated Beam energy distribution


2.) GEANT4 Simulated Positrons emitted from 1.x mm thick target


3.) Now use above Positron distribution as the particle source for G4beamline

Positrons hitting Tungsten Converter target

4.) Use GEANT4 to determine 511s from the positrons distribution impinging converter target

Oct 16th 2012 BenchMark

stages:

1. Program to input emittance, output beamsize, beam, divergence and beam energy.

2. e- on W, outcome e+. Incident electron distribution on T1. with general particle source with step 1 histogram. check graph x, y, z theta, En_dis out_put is the input. (directory for each).

3. insert T1 and generate positron distribution.

4. Acceleractor code to transport positron along the beamline. Out put positron theta, beamsize (x,y), energy distribution, out puts transported positron.

5. Geant4 takes step 4 output generates gamma (and other e+,e-) and look at those goes to detectors. beamline, plus shielding, and detectors.

HRRL pos sim benchmark Oct 16th 2012 update.jpg

Simulations

Partical Data Ground ID: PDGid=11 is electron. PDGid=-11 is positron. PDGid=22 is photon.

Parameters

Dipole vacuum chamber width is [math] 17 \pm 0.5 [/math] mm

The cavity exit diameter is about 7.3 mm.


Energy Spread Two Skewed Gaussian Fit

Energy spread fitted with two skewed Gaussian.

Hrrl 17May2012 12MeV En Spread2.png

Beam Distributions Beyond RMS: Media:Beam_Distributions_Beyond_RMS.pdf

Amplitude = 2.13894, mean = 12.07181, sigma_L = 4.46986, sigma_R = 1.20046

Sigma = 2.83516, Es = -0.57658

rms = 2.56472, skew = -0.94853


Amplitude2 = 10.88318, mean2 = 12.32332, sigma_L2 = 0.69709, sigma_R2 = 0.45170

Sigma2 = 0.57440, Es2 = -0.21360

rms2 = 0.56719, skew2 = -0.34231


Electron Distribution Upstream and Positron Distribution Downstream of Target1

simulation: Electron Distribution Upstream and Positron Distribution Downstream of Target1

3067274 Electrons fired.

T1_s=943.5

FDT1_s=$T1_s-26.52

BDT1_s=$T1_s+26.52

Thickness of T1 is 1.016 mm, radius of T1 is 15.875 mm (0.625 inches).

HRRL pos Jul2012 sim FDT1 BDT1 T1.png

HRRL pos Jul2012 sim FDT1 BDT1 Oerlay.png


Step 1: Generating positron from electron beam

Detector is after T1 to saple positron distribution. 1,379,974,500 electrons shot at the tungsten target to generate positrons.

step 1: ratio

DDNT1 = Detector DowN from T1

DQ4 = Detector at entrance Quad 4 located right after T1

DD1 = Detector at entrance of the first Dipole.

e-(DDT1)/e+(DDNT1) = 1248

e-(DDT1)/e+(DQ4) = 123698

e-(DDT1)/e+(DD1) = 936846


e+(DDNT1)/e+(DQ4) = 99

e+(DDNT1)/e+(DD1) = 750


e+(DQ4)/e+(DD1) = 7.6

Step 1: Generated Beam on DDNT1

Detector down T1:

Positrons on detector right before Q4.

X profile Hrrl pos sim s2 beam DDNT1 x s1.png

Y profile (why is the distribution clipped on the left side in the figure) Hrrl pos sim s2 beam DDNT1 y s1.png


X divergence profile Hrrl pos sim s2 beam DDNT1 xp s1.png

Y divergence profile Hrrl pos sim s2 beam DDNT1 yp s1.png

Momentum distribution Hrrl pos sim s2 beam DDNT1 mom s1.png

Momentum distribution Hrrl pos sim s2 beam DDNT1 En s1.png

Sharp drop issue

The Y-position distribution of the beam shown in Figure XXXX has a sharp drop in the region between -25.8 mm and -27.2 mm that corresponds to the boundary of the target T1. Figure YYY shows the geometry of the target T1 and the sensitive detector DDNT1. , which makes a 1.4 mm wide strip.

The distance from the back of T1 to the detector is 25.8 mm. DDNT1T1 is 1.016 mm thick, and the projected thickness of T1's thickness on the detector DDNT1 is 1.4 mm ([math]1.016 \sqrt{2}=1.44[/math]).

The positrons created in the T1 has small probability to make to the strip area, because they need to travel through thick tungsten in that direction. Only the few positrons created on the lower edge of the T1 can make to the strip area. The positrons observed for y < -27.2 mm are the positrons passed through the upstream side of the T1.

Hrrl pos sim pos sharp drop geometry2.png

Hrrl pos sim s2 beam DDNT1 xy zoom s1.png Hrrl pos sim s2 beam DDNT1 xy zoom2 s1.png

Cut off line is around 26.5 mm corresponding to the large angle.

Hrrl pos sim beam DDNT1 y yp s1.png Hrrl pos sim beam DDNT1 y yp zoom s1.png


Hrrl pos sim s2 beam DDNT1 y s1.png Hrrl pos sim s2 beam DDNT1 xy s1.png

Hrrl pos sim s2 beam DDNT1 yp s1.png Hrrl pos sim s2 beam DDNT1 xpyp s1.png


DDNT1 is at 26.52 mm (53.04 mm)downstream of T1.

T1 radius is 25.4 mm (d=50.8 mm)

DDNT1 radius is 31.75 mm (d=63.5 mm).


Hrrl pos sim s2 beam DDNT1 xy zoom s1.png


Hrrl pos sim pos sharp drop geometry.png

Step 1: Generated Beam on DQ4

Positrons on detector right before Q4.

X profile Hrrl pos sim s2 beam DQ4 x s1.png

Y profile Hrrl pos sim s2 beam DQ4 y s1.png

X divergence profile Hrrl pos sim s2 beam DQ4 xp s1.png

Y divergence profile Hrrl pos sim s2 beam DQ4 yp s1.png

Momentum distribution Hrrl pos sim s2 beam DQ4 mom s1.png

Momentum distribution Hrrl pos sim s2 beam DQ4 En s1.png

Step 1: Generated Beam on DD1

Positrons on detector right before D1 - first dipole.

X profile Hrrl pos sim s2 beam DD1 x s1.png

Y profile Hrrl pos sim s2 beam DD1 y s1.png

X divergence profile Hrrl pos sim s2 beam DD1 xp s1.png

Y divergence profile Hrrl pos sim s2 beam DD1 yp s1.png

Momentum distribution Hrrl pos sim s2 beam DD1 mom s1.png

Momentum distribution Hrrl pos sim s2 beam DD1 En s1.png

Step 2: generate positron

The positrons after T1 is detected on a virtual detector. The positrons beam size, divergence and momentum distributions are extracted and created new positron beam.

Generate positron beam from the detector after T1 and transport it to right before D1.

221032400*16=3,536,518,400 positrons generated.

step 2: ratio

e+(DDNT1)/e+(DQ4) = 3536518400/47788670 = 74

e+(DDNT1)/e+(DD1) = 3536518400/5464220 = 647

e+(DQ4)/e+(DD1) = 8.7

Generated Beam on DQ4

Positrons on detector right before Q4.

X profile Hrrl pos sim s2 beam DQ4 x.png

Y profile Hrrl pos sim s2 beam DQ4 y.png

X divergence profile Hrrl pos sim s2 beam DQ4 xp.png

Y divergence profile Hrrl pos sim s2 beam DQ4 yp.png

Momentum distribution Hrrl pos sim s2 beam DQ4 mom.png

Momentum distribution Hrrl pos sim s2 beam DQ4 En.png


Generated Beam on DD1

Positrons on detector right before D1 - first dipole.

X profile Hrrl pos sim s2 beam DD1 x.png

Y profile Hrrl pos sim s2 beam DD1 y.png

X divergence profile Hrrl pos sim s2 beam DD1 xp.png

Y divergence profile Hrrl pos sim s2 beam DD1 yp.png

Momentum distribution Hrrl pos sim s2 beam DD1 mom.png

Momentum distribution Hrrl pos sim s2 beam DD1 En.png

Beam Compare Step1 and Step2

Compare Ratio

S1 S2
e-(DDT1)/e+(DDNT1) 1248
e-(DDT1)/e+(DQ4) 123698
e-(DDT1)/e+(DD1) 936846
e+(DDNT1)/e+(DQ4) 99 74
e+(DDNT1)/e+(DD1) 750 647
e+(DQ4)/e+(DD1) 7.6 8.7

Positrons at DDNT1

Step 1 Step 2
X profile Hrrl pos sim s2 beam DDNT1 x s1.png
Y profile Hrrl pos sim s2 beam DDNT1 y s1.png
X divergence profile Hrrl pos sim s2 beam DDNT1 xp s1.png
Y divergence profile Hrrl pos sim s2 beam DDNT1 yp s1.png
Momentum distribution Hrrl pos sim s2 beam DDNT1 mom s1.png
Momentum distribution Hrrl pos sim s2 beam DDNT1 En s1.png


Compare at DQ4

Step 1 Step 2
X profile Hrrl pos sim s2 beam DQ4 x s1.png Hrrl pos sim s2 beam DQ4 x.png
Y profile Hrrl pos sim s2 beam DQ4 y s1.png Hrrl pos sim s2 beam DQ4 y.png
X divergence profile Hrrl pos sim s2 beam DQ4 xp s1.png Hrrl pos sim s2 beam DQ4 xp.png
Y divergence profile Hrrl pos sim s2 beam DQ4 yp s1.png Hrrl pos sim s2 beam DQ4 yp.png
Momentum distribution Hrrl pos sim s2 beam DQ4 mom s1.png Hrrl pos sim s2 beam DQ4 mom.png
Momentum distribution Hrrl pos sim s2 beam DQ4 En s1.png Hrrl pos sim s2 beam DQ4 En.png

Compare at DD1

Step 1 Step 2
X profile Hrrl pos sim s2 beam DD1 x s1.png Hrrl pos sim s2 beam DD1 x.png
Y profile Hrrl pos sim s2 beam DD1 y s1.png Hrrl pos sim s2 beam DD1 y.png
X divergence profile Hrrl pos sim s2 beam DD1 xp s1.png Hrrl pos sim s2 beam DD1 xp.png
Y divergence profile Hrrl pos sim s2 beam DD1 yp s1.png Hrrl pos sim s2 beam DD1 yp.png
Momentum distribution Hrrl pos sim s2 beam DD1 mom s1.png Hrrl pos sim s2 beam DD1 mom.png
Momentum distribution Hrrl pos sim s2 beam DD1 En s1.png Hrrl pos sim s2 beam DD1 En.png
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