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

	No Rastering
Vx Difference
Vy Difference
Vz Difference
X Resolution (cm)	0.2362 +/- 0.0008
Y Resolution(cm)	0.09809 +/- 0.00033
Z Resolution (cm)	0.05435 +/- 0.00017

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

	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
Vx Difference
Vy Difference
Vz Difference
X Resolution (cm)	0.2658 +/- 0.0010	0.2531 +/- 0.0009	0.2544 +/- 0.0009	0.2539 +/- 0.0009
Y Resolution(cm)	0.1728 +/- 0.0007	0.2368 +/- 0.0007	0.2644 +/- 0.0007	0.6191 +/- 0.0013
Z Resolution (cm)	0.1792 +/- 0.0006	0.1998 +/- 0.0004	0.4318 +/- 0.0009	1.105 +/- 0.002

Extended target -3 < Z < 3 cm

	1cm X Raster	1 cm Y Raster	1 cm X & Y Raster
X Resolution (cm)	0.2696 +/- 0.0009	0.2588 +/- 0.0009	0.2734 +/- 0.0009
Y Resolution (cm)	0.6234 +/- 0.0014	0.6851 +/- 0.0014	0.6927 +/- 0.0013
Z Resolution (cm)	1.136 +/- 0.002	1.361 +/- 0.002	1.381 +/- 0.003
Generated Vx (cm)
Generated Vy (cm)
Generated Vz (cm)
Reconstructed Vx (cm)
Reconstructed Vy (cm)
Reconstructed Vz (cm)
Vx Difference (cm)
Vy Difference (cm)
Vz Difference (cm)

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

	0.5cm Z Target	1cm Z Target	2cm Z Target	3cm Z Target	4cm Z Target	5cm Z Target
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
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
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
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
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
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
Generated Vx (cm)
Generated Vy (cm)
Generated Vz (cm)
Reconstructed Vx (cm)
Reconstructed Vy (cm)
Reconstructed Vz (cm)
Vx Difference (cm)
Vy Difference (cm)
Vz Difference (cm)

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

	[-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]
Resolution (cm)	0.09406 +/- 0.00128	0.0868 +/- 0.0013	0.08961 +/- 0.00128
Vy Difference
*	*	*	*	*	*	*	*
	[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]
Resolution (cm)
Vy Difference