Vertex Reconstruction studies
Inclusive electron GEMC 2.4 & Coatjava 2.4
LB_GEMC2.4CJ2.4_Vertex
Summary
Set all histogram ranges to -6,6 cm and bin sizes of 0.1 cm
Point target X,Y,Z=0 cm
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No Rastering
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Vx Difference |
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Vy Difference |
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Vz Difference |
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X Resolution (cm) |
0.2362 +/- 0.0008
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Y Resolution(cm) |
0.09809 +/- 0.00033
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Z Resolution (cm) |
0.05435 +/- 0.00017
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These histograms raise some questions. To begin I created a LUND file with 6 GeV incident electrons at 25 degrees in theta and 0 degrees in phi. All of the vertex positions were set to 0. I then ran GEMC 2.4 using the command line
~/src/CLAS/GEMC/source/gemc -USE_GUI=0 -INPUT_GEN_FILE="LUND,No_Raster.LUND" -N=75000 eg12_sol_No_Raster.gcard
which created an output file called eg12_sol_75k_No_Raster.ev. After that the reconstruction command line used was
~/src/CLAS/coatjava-2.4/bin/clas12-reconstruction -i eg12_sol_75k_No_Raster.ev-config GEOM::new=true -config MAG::torus=-1.0 -config MAG::solenoid=1.0 -o eg12_sol_75k_No_Raster_rec.evio -s DCHB:DCTB:EC:FTOF:EB -config DATA::mc=true -config DCTB::useRaster=true
After the reconstruction a root file was created using
~/src/CLAS/evio2root/bin/evio2root eg12_sol_75k_No_Raster_rec.evio eg12_sol_75k_No_Raster_rec.root 75000
A plot was then created to show the X Vertex and Y Vertex Differences
The first question is why is there a shift in the Y Difference. What would make X more centered around 0? The next question is when rastering begins, why do the resolutions in the X Vertices remain unchanged while the resolutions in the Y Vertices change?
Point in 2-D but extended target in 1-D
Two vertex variables are fixed at zero and the third vertex variable is altered
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2cm X Raster, Y=0,Z=0 |
2 cm Y Raster, X=0,Z=0 |
2 cm Z Raster ,X=0,Y=0 |
6 cm Z Raster ,X=0,Y=0
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Vx Difference |
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Vy Difference |
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Vz Difference |
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X Resolution (cm) |
0.2658 +/- 0.0010 |
0.2531 +/- 0.0009 |
0.2544 +/- 0.0009 |
0.2539 +/- 0.0009
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Y Resolution(cm) |
0.1728 +/- 0.0007 |
0.2368 +/- 0.0007 |
0.2644 +/- 0.0007 |
0.6191 +/- 0.0013
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Z Resolution (cm) |
0.1792 +/- 0.0006 |
0.1998 +/- 0.0004 |
0.4318 +/- 0.0009 |
1.105 +/- 0.002
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Extended target -3 < Z < 3 cm
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1cm X Raster |
1 cm Y Raster |
1 cm X & Y Raster
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X Resolution (cm) |
0.2696 +/- 0.0009 |
0.2588 +/- 0.0009 |
0.2734 +/- 0.0009
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Y Resolution (cm) |
0.6234 +/- 0.0014 |
0.6851 +/- 0.0014 |
0.6927 +/- 0.0013
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Z Resolution (cm) |
1.136 +/- 0.002 |
1.361 +/- 0.002 |
1.381 +/- 0.003
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Generated Vx (cm) |
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Generated Vy (cm) |
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Generated Vz (cm) |
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Reconstructed Vx (cm) |
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Reconstructed Vy (cm) |
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Reconstructed Vz (cm) |
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Vx Difference (cm) |
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Vy Difference (cm) |
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Vz Difference (cm) |
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Extended target in Z. Vy shift analysis
All Histograms below were created by simply making the target longer along the Z axis. Each case uses vertex points for X and Y ranging from -1cm to 1cm
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0.5cm Z Target |
1cm Z Target |
2cm Z Target |
3cm Z Target |
4cm Z Target |
5cm Z Target
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X Resolution (cm) |
0.2705 +/- 0.0010 |
0.2726 +/- 0.0010 |
0.2716 +/- 0.0010 |
0.2731 +/- 0.0010 |
0.2702 +/- 0.0009 |
0.2736 +/- 0.0010
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Y Resolution (cm) |
0.2041 +/- 0.0010 |
0.2282 +/- 0.0011 |
0.3152 +/- 0.0014 |
0.433 +/- 0.002 |
0.5584 +/- 0.0018 |
0.6454 +/- 0.0015
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Z Resolution (cm) |
0.28 +/-0.00 |
0.3582 +/- 0.0013 |
0.5659 +/- 0.0018 |
0.7927 +/- 0.0023 |
1.034 +/- 0.003 |
1.253 +/-0.003
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X Mean (cm) |
0.0139 +/- 0.001 |
0.0139 +/- 0.00107 |
0.01436 +/- 0.00104 |
0.01217 +/- 0.00107 |
0.00991 +/- 0.00104 |
0.009022 +/- 0.00105
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Y Mean (cm) |
-0.1893 +/- 0.0011 |
-0.2004 +/- 0.0012 |
-0.2379 +/- 0.0016 |
-0.2936 +/- 0.0022 |
-0.3648 +/- 0.0027 |
-0.3871 +/- 0.0026
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Z Mean (cm) |
0.0928 +/- 0.0014 |
0.06464 +/- 0.0013 |
-0.0337 +/- 0.0028 |
-0.1582 +/- 0.0040 |
-0.3016 +/- 0.0053 |
-0.486 +/- 0.006
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Generated Vx (cm) |
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Generated Vy (cm) |
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Generated Vz (cm) |
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Reconstructed Vx (cm) |
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Reconstructed Vy (cm) |
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Reconstructed Vz (cm) |
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Vx Difference (cm) |
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Vy Difference (cm) |
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Vz Difference (cm) |
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It would seem that increasing the length of the target in the Z direction has an effect on the resolution of the Y vertex position along with how far the center of the Gaussian peak will shift for the Y vertex differences.
Localized Vertex Resolution Investigation of Line Targets
GEMC was ran to create electrons being produced in a line along certain axes. These include three separate 2cm targets centered at (0,0,0) in the X, Y , and Z directions. The final target is a line along the Z axis centered at (0,0,0) that is 6cm long. The generated electrons were shot at 25 degrees in theta and 0 degrees in phi at an energy of 6GeV.
Here is an example of how the cuts were made. Consider the case of a 2cm line target in the Z direction centered at (0,0,0). Closed intervals begin at the end of the target and are 0.1cm long. So the first interval would be [-1.0,-0.9], then the next would be [-0.9, -0.8] and so on until the entire target is covered. The events in the EVENTHB bank were cut so that in any given interval there would be a margin of +/- 1cm to remove any outliers that may cause the histograms to have long tails.
Below are the histograms for the 2cm line target in Y,X=0,Z=0. The electrons were fired with an energy of 6 GeV at 25 degrees in theta at 0 degrees in phi.
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[-1.0 , -0.9] |
[-0.9 , -0.8] |
[-0.8 , -0.7] |
[-0.7 , -0.6] |
[-0.6 , -0.5] |
[-0.5 , -0.4] |
[-0.4 , -0.3] |
[-0.3 , -0.2] |
[-0.2 , -0.1] |
[-0.1 , 0.0]
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Resolution (cm) |
0.09406 +/- 0.00128 |
0.0868 +/- 0.0013 |
0.08961 +/- 0.00128 |
0.09853 +/- 0.00148 |
0.1038 +/- 0.0016 |
0.1202 +/- 0.0018 |
0.1755 +/- 0.0026 |
0.1847 +/- 0.0028 |
0.1255 +/- 0.0019 |
0.09663 +/- 0.00160
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Vy Difference |
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* |
* |
* |
* |
* |
* |
* |
*
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[0.9 , 1.0] |
[0.8 , 0.9] |
[0.7 , 0.8] |
[0.6 , 0.7] |
[0.5 , 0.6] |
[0.4 , 0.5] |
[0.3 , 0.4] |
[0.2 , 0.3] |
[0.1 , 0.2] |
[0.0 , 0.1]
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Resolution (cm) |
0.1001 +/- 0.0016 |
0.1221 +/- 0.0018 |
0.1144 +/- 0.0017 |
0.169 +/- 0.003 |
0.171 +/- 0.003 |
0.1105 +/- 0.0016 |
0.09508 +/- 0.00137 |
0.09065 +/- 0.00140 |
0.09302 +/- 0.00133 |
0.09008 +/- 0.00122
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Vy Difference |
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Below are the histograms for a 2cm target along the Y axis, X = 0 Z = 0. The electrons were fired with an energy of 6 GeV at 25 degrees in theta and 180 degrees in phi.
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[-1.0 , -0.9] |
[-0.9 , -0.8] |
[-0.8 , -0.7] |
[-0.7 , -0.6] |
[-0.6 , -0.5] |
[-0.5 , -0.4] |
[-0.4 , -0.3] |
[-0.3 , -0.2] |
[-0.2 , -0.1] |
[-0.1 , 0.0]
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Resolution (cm) |
0.07741 +/- 0.00166 |
0.0976 +/- 0.0017 |
0.09924 +/- 0.00150 |
0.1386 +/- 0.0024 |
0.1278 +/- 0.0027 |
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Vy Difference |
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* |
* |
* |
* |
* |
* |
* |
*
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[0.9 , 1.0] |
[0.8 , 0.9] |
[0.7 , 0.8] |
[0.6 , 0.7] |
[0.5 , 0.6] |
[0.4 , 0.5] |
[0.3 , 0.4] |
[0.2 , 0.3] |
[0.1 , 0.2] |
[0.0 , 0.1]
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Resolution (cm) |
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Vy Difference |
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Below are the Histograms for a 2cm long target in the X Direction with a 6GeV electron fired at 25 degrees in theta and 90 degrees in phi
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[-1.0 , -0.9] |
[-0.9 , -0.8] |
[-0.8 , -0.7] |
[-0.7 , -0.6] |
[-0.6 , -0.5] |
[-0.5 , -0.4] |
[-0.4 , -0.3] |
[-0.3 , -0.2] |
[-0.2 , -0.1] |
[-0.1 , 0.0]
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Resolution (cm) |
0.1341 +/- 0.0140 |
0.1304 +/- 0.0051 |
0.1182 +/- 0.0036 |
0.09062 +/- 0.0031 |
0.06816 +/- 0.00191 |
n/a |
0.0635 +/- 0.0013 |
0.0618 +/- 0.0012 |
0.07473 +/- 0.00178 |
0.08787 +/- 0.00132 |
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Vx Difference |
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* |
* |
* |
* |
* |
* |
* |
*
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[0.9 , 1.0] |
[0.8 , 0.9] |
[0.7 , 0.8] |
[0.6 , 0.7] |
[0.5 , 0.6] |
[0.4 , 0.5] |
[0.3 , 0.4] |
[0.2 , 0.3] |
[0.1 , 0.2] |
[0.0 , 0.1]
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Resolution (cm) |
0.01572 +/- 0.00020 |
0.01844 +/- 0.00031 |
0.01722 +/- 0.00028 |
0.02386 +/- 0.00088 |
0.024 +/- 0.001 |
0.04406 +/- 0.00182 |
0.04517 +/- 0.00118 |
0.04722 +/- 0.00107 |
0.05667 +/- 0.00106 |
0.08356 +/- 0.00159
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Vx Difference |
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Below are the Vx Differences using a 2cm target in X with incident 6 GeV electrons at 25 degrees in theta and 270 degrees in phi
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[-1.0 , -0.9] |
[-0.9 , -0.8] |
[-0.8 , -0.7] |
[-0.7 , -0.6] |
[-0.6 , -0.5] |
[-0.5 , -0.4] |
[-0.4 , -0.3] |
[-0.3 , -0.2] |
[-0.2 , -0.1] |
[-0.1 , 0.0]
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Resolution (cm) |
0.01571 +/- 0.0002 |
0.0163 +/- 0.0003 |
0.01821 +/- 0.0003 |
0.03065 +/- 0.00163 |
0.02109 +/- 0.00217 |
0.03772 +/- 0.00133 |
0.04817 +/- 0.00125 |
0.05154 +/- 0.00113 |
0.05677 +/- 0.00113 |
0.08348 +/- 0.00144 |
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Vx Difference |
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* |
* |
* |
* |
* |
* |
* |
* |
* |
* |
*
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[0.9 , 1.0] |
[0.8 , 0.9] |
[0.7 , 0.8] |
[0.6 , 0.7] |
[0.5 , 0.6] |
[0.4 , 0.5] |
[0.3 , 0.4] |
[0.2 , 0.3] |
[0.1 , 0.2] |
[0.0 , 0.1]
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Resolution (cm) |
0.1257 +/- 0.0100 |
0.112 +/- 0.004 |
0.1162 +/- 0.0034 |
0.08958 +/- 0.00316 |
0.07347 +/- 0.00210 |
0.07271 +/- 0.00159 |
0.06196 +/- 0.00146 |
0.06087 +/- 0.00114 |
0.07298 +/- 0.00149 |
0.09017 +/- 0.00128
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Vx Difference |
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Elastic electron proton GEMC 2.4 & Coatjava 2.4
References
https://clasweb.jlab.org/wiki/index.php/TF_EG12_Vertex#Z_resolution_With_micro-megas
EG12#Vertex_Studies