View source for July2012PosSimulation

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.

[[File:HRRL_pos_sim_benchmark_Oct_16th_2012_update.jpg | 400 px]]

== 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.

[[File:hrrl_17May2012_12MeV_En_Spread2.png | 400 px]]

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, Skewness = -0.57658 

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

 Sigma2 = 0.57440, Skewness2 = -0.21360

=== 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).

[[File:HRRL_pos_Jul2012_sim_FDT1_BDT1_T1.png | 500 px]]

[[File:HRRL_pos_Jul2012_sim_FDT1_BDT1_Oerlay.png | 500 px]]


= Step 1: Generating positron from electron beam =

Detector is after T1 to saple positron distribution.
13,799,743,800 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-(DUPT1) = 13,799,743,800

e+(DDNT1) = <math>1.095179 \times 10^7</math>

e+(DQ4) = <math>62780</math>

e+(DQ4) = <math>6742</math>


e-(DUPT1)/e+(DDNT1) = 1260

e-(DUPT1)/e+(DQ4) = 219811 = <math>2.2 \times 10^5</math>

e-(DUPT1)/e+(DD1) = 2046832 = <math>2.0 \times 10^6</math>


e+(DDNT1)/e+(DQ4) = 174

e+(DDNT1)/e+(DD1) = 1624


e+(DQ4)/e+(DD1) = 9.3

== Step 1: Generated Beam on DDNT1 ==

Detector down T1:

Positrons on detector right before Q4.

X profile [[File:hrrl_pos_sim_s2_beam_DDNT1_x_s1.png | 300 px]]

Y profile (why is the distribution clipped on the left side in the figure) [[File:hrrl_pos_sim_s2_beam_DDNT1_y_s1.png | 300 px]]


X divergence profile  [[File:hrrl_pos_sim_s2_beam_DDNT1_xp_s1.png | 300 px]]

Y divergence profile  [[File:hrrl_pos_sim_s2_beam_DDNT1_yp_s1.png | 300 px]]

Momentum distribution  [[File:hrrl_pos_sim_s2_beam_DDNT1_mom_s1.png | 300 px]]

Momentum distribution  [[File:hrrl_pos_sim_s2_beam_DDNT1_En_s1.png | 300 px]]

=== Sharp drop issue ===

The Y-position distribution of the beam shown in Figure ~\ref{sim-DDNT1-y-vs-x} 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 ~\ref{sim-DDNT1-T1-geo} shows the geometry of the target T1 and the sensitive detector DDNT1.   If the target size was increased, it would eventually intersected the detector DDNT1 at a distance of 25.8 mm from the beam center.   A 1.4 mm wide stripe of low counts is visible on DDNT1 that is a result of the target's thickness of 1.016 mm and the 45 degree angle of intersection.  (<math>1.016 \sqrt{2}=1.44</math>).  The edge of the target does not produce many positrons compared to the face of the target, and as a result you see the stripe.

As shown in figures ~\ref{sim-DDNT1-theta-vs-y} and ~\ref{sim-DDNT1-theta-vs-y-zoom} (zoomed figure) the positron distribution decrease occures at <math>\theta = 45^o</math>.   Positrons are emitted from both the downstream and upstream side of the target.  As shown in the figure, positrons from the downstream side of the target intersect the detector at angles below 45 degrees while positrons from the upstream side of the target begin to hit the detector at angles beyond 45 degrees.   The 1.4 mm gap represents the transition of positrons between these two extremes.  

[[File:hrrl_pos_sim_pos_sharp_drop_geometry2.png | 400 px]]

[[File:hrrl_pos_sim_s2_beam_DDNT1_xy_zoom_s1.png | 400 px]] [[File:hrrl_pos_sim_s2_beam_DDNT1_xy_zoom2_s1.png | 400 px]]

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

[[File:hrrl_pos_sim_beam_DDNT1_y_yp_s1.png | 400 px]] [[File:hrrl_pos_sim_beam_DDNT1_y_yp_zoom_s1.png | 400 px]] 



[[File:hrrl_pos_sim_s2_beam_DDNT1_y_s1.png | 400 px]]   [[File:hrrl_pos_sim_s2_beam_DDNT1_xy_s1.png | 400 px]]

[[File:hrrl_pos_sim_s2_beam_DDNT1_yp_s1.png | 400 px]]   [[File:hrrl_pos_sim_s2_beam_DDNT1_xpyp_s1.png | 400 px]]


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).


[[File:hrrl_pos_sim_s2_beam_DDNT1_xy_zoom_s1.png | 400 px]]


[[File:hrrl_pos_sim_pos_sharp_drop_geometry.png | 400 px]]

== Step 1: Generated Beam on DQ4 ==

Positrons on detector right before Q4.

X profile [[File:hrrl_pos_sim_s2_beam_DQ4_x_s1.png | 300 px]]

Y profile [[File:hrrl_pos_sim_s2_beam_DQ4_y_s1.png | 300 px]]

X divergence profile  [[File:hrrl_pos_sim_s2_beam_DQ4_xp_s1.png | 300 px]]

Y divergence profile  [[File:hrrl_pos_sim_s2_beam_DQ4_yp_s1.png | 300 px]]

Momentum distribution  [[File:hrrl_pos_sim_s2_beam_DQ4_mom_s1.png | 300 px]]

Momentum distribution  [[File:hrrl_pos_sim_s2_beam_DQ4_En_s1.png | 300 px]]

== Step 1: Generated Beam on DD1 ==

Positrons on detector right before D1 - first dipole.

X profile [[File:hrrl_pos_sim_s2_beam_DD1_x_s1.png | 300 px]]

Y profile [[File:hrrl_pos_sim_s2_beam_DD1_y_s1.png | 300 px]]

X divergence profile  [[File:hrrl_pos_sim_s2_beam_DD1_xp_s1.png | 300 px]]

Y divergence profile  [[File:hrrl_pos_sim_s2_beam_DD1_yp_s1.png | 300 px]]

Momentum distribution  [[File:hrrl_pos_sim_s2_beam_DD1_mom_s1.png | 300 px]]

Momentum distribution  [[File:hrrl_pos_sim_s2_beam_DD1_En_s1.png | 300 px]]

= 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 [[File:hrrl_pos_sim_s2_beam_DQ4_x.png | 300 px]]

Y profile [[File:hrrl_pos_sim_s2_beam_DQ4_y.png | 300 px]]

X divergence profile  [[File:hrrl_pos_sim_s2_beam_DQ4_xp.png | 300 px]]

Y divergence profile  [[File:hrrl_pos_sim_s2_beam_DQ4_yp.png | 300 px]]

Momentum distribution  [[File:hrrl_pos_sim_s2_beam_DQ4_mom.png | 300 px]]

Momentum distribution  [[File:hrrl_pos_sim_s2_beam_DQ4_En.png | 300 px]]


== Generated Beam on DD1 ==

Positrons on detector right before D1 - first dipole.

X profile [[File:hrrl_pos_sim_s2_beam_DD1_x.png | 300 px]]

Y profile [[File:hrrl_pos_sim_s2_beam_DD1_y.png | 300 px]]

X divergence profile  [[File:hrrl_pos_sim_s2_beam_DD1_xp.png | 300 px]]

Y divergence profile  [[File:hrrl_pos_sim_s2_beam_DD1_yp.png | 300 px]]

Momentum distribution  [[File:hrrl_pos_sim_s2_beam_DD1_mom.png | 300 px]]

Momentum distribution  [[File:hrrl_pos_sim_s2_beam_DD1_En.png | 300 px]]

= Beam Compare Step1 and Step2 =


== Compare Ratio ==


{| border="3"  cellpadding="5" cellspacing="0"

|  || 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 ==
{| border="3"  cellpadding="5" cellspacing="0"
|  || Step 1  ||  Step 2
|-
| X profile || [[File:hrrl_pos_sim_s2_beam_DDNT1_x_s1.png | 300 px]]  ||  
|-
| Y profile ||  [[File:hrrl_pos_sim_s2_beam_DDNT1_y_s1.png | 300 px]] ||  
|-
| X divergence profile || [[File:hrrl_pos_sim_s2_beam_DDNT1_xp_s1.png | 300 px]]  ||  
|-
| Y divergence profile ||  [[File:hrrl_pos_sim_s2_beam_DDNT1_yp_s1.png | 300 px]] ||  
|-
| Momentum distribution ||  [[File:hrrl_pos_sim_s2_beam_DDNT1_mom_s1.png | 300 px]]  ||  
|-
| Momentum distribution || [[File:hrrl_pos_sim_s2_beam_DDNT1_En_s1.png | 300 px]]  ||  
|-

|}



== Compare at DQ4 ==



{| border="3"  cellpadding="5" cellspacing="0"
|  || Step 1  ||  Step 2
|-
| X profile || [[File:hrrl_pos_sim_s2_beam_DQ4_x_s1.png | 300 px]]  ||  [[File:hrrl_pos_sim_s2_beam_DQ4_x.png | 300 px]]
|-
| Y profile ||  [[File:hrrl_pos_sim_s2_beam_DQ4_y_s1.png | 300 px]] ||  [[File:hrrl_pos_sim_s2_beam_DQ4_y.png | 300 px]]
|-
| X divergence profile || [[File:hrrl_pos_sim_s2_beam_DQ4_xp_s1.png | 300 px]]  ||  [[File:hrrl_pos_sim_s2_beam_DQ4_xp.png | 300 px]]
|-
| Y divergence profile ||  [[File:hrrl_pos_sim_s2_beam_DQ4_yp_s1.png | 300 px]] ||   [[File:hrrl_pos_sim_s2_beam_DQ4_yp.png | 300 px]]
|-
| Momentum distribution ||  [[File:hrrl_pos_sim_s2_beam_DQ4_mom_s1.png | 300 px]]  ||  [[File:hrrl_pos_sim_s2_beam_DQ4_mom.png | 300 px]]
|-
| Momentum distribution || [[File:hrrl_pos_sim_s2_beam_DQ4_En_s1.png | 300 px]]  ||  [[File:hrrl_pos_sim_s2_beam_DQ4_En.png | 300 px]]
|-
|}

== Compare at DD1 ==



{| border="3"  cellpadding="5" cellspacing="0"
|  || Step 1  ||  Step 2
|-
| X profile || [[File:hrrl_pos_sim_s2_beam_DD1_x_s1.png | 300 px]]  ||  [[File:hrrl_pos_sim_s2_beam_DD1_x.png | 300 px]]
|-
| Y profile ||  [[File:hrrl_pos_sim_s2_beam_DD1_y_s1.png | 300 px]] ||  [[File:hrrl_pos_sim_s2_beam_DD1_y.png | 300 px]]
|-
| X divergence profile || [[File:hrrl_pos_sim_s2_beam_DD1_xp_s1.png | 300 px]]  ||   [[File:hrrl_pos_sim_s2_beam_DD1_xp.png | 300 px]]
|-
| Y divergence profile ||  [[File:hrrl_pos_sim_s2_beam_DD1_yp_s1.png | 300 px]] ||   [[File:hrrl_pos_sim_s2_beam_DD1_yp.png | 300 px]]
|-
| Momentum distribution ||  [[File:hrrl_pos_sim_s2_beam_DD1_mom_s1.png | 300 px]]  ||   [[File:hrrl_pos_sim_s2_beam_DD1_mom.png | 300 px]]
|-
| Momentum distribution || [[File:hrrl_pos_sim_s2_beam_DD1_En_s1.png | 300 px]]  ||  [[File:hrrl_pos_sim_s2_beam_DD1_En.png | 300 px]]
|-
|}



= S3 =


{| border="3"  cellpadding="5" cellspacing="0"
|       || DD1UP  || DD45  || DD2ND || DT2UP || DT2UP (Px>0) || DT2UP (Px>) 
|-
| 1 MeV || <math>1.4\times10^8</math> [[File:ST_sim_s3_1Mev_En_D1UP.png | 300 px]]  ||  <math>3.8 \times 10^5</math>[[File:ST_sim_s3_1Mev_En_D45.png | 300 px]] || <math>1.8 \times 10^3</math> [[File:ST_sim_s3_1Mev_En_DD2ND.png | 300 px]] ||<math>1.2 \times 10^1</math> [[File:ST_sim_s3_1Mev_En_DT2ND.png | 300 px]] || [[File:ST_sim_s3_1Mev_En_DT2ND_BT_0.png | 300 px]] || [[File:ST_sim_s3_1Mev_En_DT2ND_BT_A.png | 300 px]]
|-
| 2 MeV || <math>1.4\times10^8</math> [[File:ST_sim_s3_2Mev_En_D1UP.png | 300 px]]  ||  <math>2.6 \times 10^6</math>[[File:ST_sim_s3_2Mev_En_D45.png | 300 px]] || <math>6.1 \times 10^4</math>[[File:ST_sim_s3_2Mev_En_DD2ND.png | 300 px]] ||<math>4.3 \times 10^2</math> [[File:ST_sim_s3_2Mev_En_DT2ND.png | 300 px]] || [[File:ST_sim_s3_2Mev_En_DT2ND_BT_0.png | 300 px]] || [[File:ST_sim_s3_2Mev_En_DT2ND_BT_A.png | 300 px]]
|-
| 3 MeV || <math>1.4\times10^8</math> [[File:ST_sim_s3_3Mev_En_D1UP.png | 300 px]]  || <math>5.9 \times 10^6</math>[[File:ST_sim_s3_3Mev_En_D45.png | 300 px]]  ||<math>4.2 \times 10^5</math>[[File:ST_sim_s3_3Mev_En_DD2ND.png | 300 px]] || <math>2.3 \times 10^3</math>[[File:ST_sim_s3_3Mev_En_DT2ND.png | 300 px]] || [[File:ST_sim_s3_3Mev_En_DT2ND_BT_0.png | 300 px]] || [[File:ST_sim_s3_3Mev_En_DT2ND_BT_A.png | 300 px]]
|-
| 4 MeV || <math>1.4\times10^8</math> [[File:ST_sim_s3_4Mev_En_D1UP.png | 300 px]]  ||  <math>5.1 \times 10^6</math>[[File:ST_sim_s3_4Mev_En_D45.png | 300 px]] || <math>5.9 \times 10^5</math>[[File:ST_sim_s3_4Mev_En_DD2ND.png | 300 px]] ||<math>4.4 \times 10^3</math> [[File:ST_sim_s3_4Mev_En_DT2ND.png | 300 px]] || [[File:ST_sim_s3_4Mev_En_DT2ND_BT_0.png | 300 px]] || [[File:ST_sim_s3_4Mev_En_DT2ND_BT_A.png | 300 px]]
|-
| 5 MeV || <math>1.4\times10^8</math> [[File:ST_sim_s3_5Mev_En_D1UP.png | 300 px]]  || <math>4.8 \times 10^6</math>[[File:ST_sim_s3_5Mev_En_D45.png | 300 px]]  || <math>7.4 \times 10^5</math>[[File:ST_sim_s3_5Mev_En_DD2ND.png | 300 px]] ||<math>5.0 \times 10^3</math> [[File:ST_sim_s3_5Mev_En_DT2ND.png | 300 px]] || [[File:ST_sim_s3_5Mev_En_DT2ND_BT_0.png | 300 px]] || [[File:ST_sim_s3_5Mev_En_DT2ND_BT_A.png | 300 px]]
|-
|}



==1 MeV ==

En @ DD1UP [[File:ST_sim_s3_1Mev_En_D1UP.png | 300 px]]

En @ DD45 [[File:ST_sim_s3_1Mev_En_D45.png | 300 px]]

En @ DD2ND [[File:ST_sim_s3_1Mev_En_DD2ND.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_1Mev_En_DT2ND.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_1Mev_En_DT2ND_BT_0.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_1Mev_En_DT2ND_BT_A.png | 300 px]]



==2 MeV ==

En @ DD1UP [[File:ST_sim_s3_2Mev_En_D1UP.png | 300 px]]

En @ DD45 [[File:ST_sim_s3_2Mev_En_D45.png | 300 px]]

En @ DD2ND [[File:ST_sim_s3_2Mev_En_DD2ND.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_2Mev_En_DT2ND.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_2Mev_En_DT2ND_BT_0.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_2Mev_En_DT2ND_BT_A.png | 300 px]]

==3 MeV ==

En @ DD1UP [[File:ST_sim_s3_3Mev_En_D1UP.png | 300 px]]

En @ DD45 [[File:ST_sim_s3_3Mev_En_D45.png | 300 px]]

En @ DD2ND [[File:ST_sim_s3_3Mev_En_DD2ND.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_3Mev_En_DT2ND.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_3Mev_En_DT2ND_BT_0.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_3Mev_En_DT2ND_BT_A.png | 300 px]]

==4 MeV ==

En @ DD1UP [[File:ST_sim_s3_4Mev_En_D1UP.png | 300 px]]

En @ DD45 [[File:ST_sim_s3_4Mev_En_D45.png | 300 px]]

En @ DD2ND [[File:ST_sim_s3_4Mev_En_DD2ND.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_4Mev_En_DT2ND.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_4Mev_En_DT2ND_BT_0.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_4Mev_En_DT2ND_BT_A.png | 300 px]]

==5 MeV ==

En @ DD1UP [[File:ST_sim_s3_5Mev_En_D1UP.png | 300 px]]

En @ DD45 [[File:ST_sim_s3_5Mev_En_D45.png | 300 px]]

En @ DD2ND [[File:ST_sim_s3_5Mev_En_DD2ND.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_5Mev_En_DT2ND.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_5Mev_En_DT2ND_BT_0.png | 300 px]]

En @ DT2ND [[File:ST_sim_s3_5Mev_En_DT2ND_BT_A.png | 300 px]]