GAS TARGET BACKGROUND SUBTRACTION FOR TRITIUM/ARGON CONFIGURATION SHUJIE LI HALL A/C ANALYSIS WORKSHOP JUNE, 2017
GAS TARGET CELL 2017 FALL E12-10-103 MARATHON E12-11-112 x>1 SRC E12-14-011 (e,e p) SRC 2017 SPRING E12-14-012 ARGON https://wiki.jlab.org/jlab_tritium_target_wiki/index.php/file:hall_a_tritium_target_system-1.docx 2
GAS TARGET CELL exit window 0.279mm side wall 0.5mm Length 251mm Diameter 12.5mm entrance window 0.254mm https://wiki.jlab.org/jlab_tritium_target_wiki/index.php/file:hall_a_tritium_target_system-1.docx 3
GAS TARGET CELL * 20% density reduction at 25 ua Gas in Cell Total Window Thickness Gas Thickness Gas Rad Length Tritium 0.16 g/cm 2 0.075 g/cm 2 183.6 g/cm 2 Helium 3 0.16 g/cm 2 0.075 g/cm 2 71.07 g/cm 2 Deuterium 0.16 g/cm 2 0.120 g/cm 2 122.6 g/cm 2 Argon 0.16 g/cm 2 1.675 g/cm 2 19.55 g/cm 2 Dummy Target: Al7075 foil x 2 Thickness: Foil 1: 0.8886 ± 0.002 g/cm 2 Foil 2: 0.8893 ± 0.002 g/cm 2 10 times thicker than target windows for better statistics http://hallaweb.jlab.org/collab/meeting/2017-winter/hall%20a%20tritium%20target%20status.pptx http://pdg.lbl.gov/2017/atomicnuclearproperties/html/argon_gas_ar.html https://hallaweb.jlab.org/wiki/images/a/ad/ar-ti_err.pdf 4
BACKGROUND SUBTRACTION https://logbooks.jlab.org/entry/3461816 5 Goal: use dummy target data to remove the window contamination in gas target cells
BACKGROUND SUBTRACTION Use left-arm delta scan runs from the Ar40 experiment. Run # target Ebeam (GeV) P0 (GeV) Scattering angle 733 dummy 2.2 2.03 15.548 734 Argon cell 2.2 2.03 15.548 Cuts: trigger PID Acceptance Tracking (DR.evtypebits>>3)&1 L.cer.asum_c >500 && (L.prl1.e+L.prl2.e)>1600 abs(l.tr.tg_ph)<0.04 && abs(l.tr.tg_th)<0.06 && abs(l.tr.tg_dp)<0.05 L.tr.n==1 6
yield 16000 RUN 733, DUMMY 14000 RUN 734, GAS CELL 12000 10000 8000 2000 0-0.2-0.15-0.1-0.05 0 0.05 0.1 0.15 0.2 target z (meter) 7 6000 4000
Run # target Total Window Thickness (g/cm 2 ) Gas thickness (g/cm 2 ) Prescale 733 dummy 1.778 0 100 734 Argon cell 0.16 1.675 88 yield 16000 RUN 733, DUMMY 6000 4000 2000 0-0.2-0.15-0.1-0.05 0 0.05 0.1 0.15 0.2 target z (meter) 8 14000 RUN 734, GAS CELL 12000 10000 8000 To use dummy as target windows:!! Align dummy and window positions! Check peak width! Scale by luminosity and prescale factor!
ENDCAP SUBTRACTION RESULTS ENDCAP SUBTRACTION yield 3000 2500 RUN 733, DUMMY RUN 734, GAS CELL ENDCAP REMOVED 2000 1500 1000 500 0-0.2-0.15-0.1-0.05 0 0.05 0.1 0.15 0.2 target z (meter) 9
GAS TARGET CELL IN MONTE-CARLO SIMULATION Simulate two foils (and gas fillings) separately with FULL target and chamber configuration. Then combine results with necessary normalization. 10
- Plot ztar, ztari - To combine *.rzdat : call hmerge(nfile,infiles[],outfile) in Fortran - To combine *.root : hadd outfile infile1 infilen in command line 11
CHECK PEAK WIDTH IN MONTE-CARLO SIMULATION VDC resolution Optics resolution Single-arm SIMC as the phasespace generator https://github.com/jeffersonlab/halla-xem-analysis Energy loss distribution Multiple scattering XEMC as the radiative cross section model https://userweb.jlab.org/~yez/work/xemc/ 12
VDC RESOLUTION IN SIMULATION VDC time resolution from 5-cell events χ 2 / ndf 234.7 / 12 Constant 4057 ± 31.0 4000 Mean 2.137e-10 ± 7.402e-11 Sigma 1.23e-08 ± 6.98e-11 3500 3000 2500 2000 FWHM = 2.355 σ = 29 ns 1500 resolution = 29/sqrt(5)/sqrt(4) = 6.5 ns 1000 500-0.2 0 10-0.1 0 0.1 0.2 t 12 - t 45 (sec) -6 VDC position resolution = 6.5 ns * 50 um/ns = 325 um 13
ELECTRON ENERGY LOSS IN SIMULATION Ionization energy loss + radiative energy loss (Collisions with atomic electrons) (Collisions with atomic nuclei) NOT in phase-space generator yet Ionization energy loss straggling follows Landau distribution Mean given by bethe-bloch Eq. 5 from Y. Mejaddem, NIM B 173 (2001) 397-410 http://pdg.lbl.gov/2014/reviews/rpp2014-rev-passage-particles-matter.pdf 14
MULTIPLE SCATTERING IN SIMULATION http://pdg.lbl.gov/2014/reviews/rpp2014-rev-passage-particles-matter.pdf z1, z2 are two independent Gaussian distributions Deflection in two planes are independent and identically distributed 15
ENDCAPS IN SIMULATION Less than 2% difference in peak width (negligible) Don t need to change the shape of dummy yield distribution for target windows 16
DATA TO MC COMPARISON The width of downstream foil does not match DATA TO MC COMPARISON yield 16000 MC, = 6.467e-03 DATA, = 9.776e-03 14000 12000 RUN 733, DUMMY MC is shifted and scaled to match DATA 10000 8000 6000 4000 2000 0-0.2-0.15-0.1-0.05 0 0.05 0.1 0.15 0.2 target z (meter) 17
DATA TO MC COMPARISON The 2 nd Gaussian (non-gaussian) tail is missing in simulation!!! yield 10 4 DATA TO MC COMPARISON MC DATA 3 10 2 10 MC can t provide window contamination information, need dummy run 10 1-0.2-0.15-0.1-0.05 0 0.05 0.1 0.15 0.2 target z (meter) 18
THANKS Barak Schmookler Douglas Higinbotham Eric Christy All Tritium students 19
TARGET CELL IN SIMULATION - Randomly generate N tot =5000000 vertices in each windows/gas within Ω tot = 8(10%* P 0 )(100mr)(100mr) - Include multiple scattering for entire target cell - Not include energy loss (TBD) - Only good event recorded in ntuples 20
TARGET CELL IN SIMULATION 21
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Show rootfile 23
RATE ESTIMATION rate = I ρ l / A Atomic mass Ωeff dσ dω dω = I ρ l / A Ωtot dσ dω ε(ω)dω # of scattering centers per area = g/cm 2 / (g/mol) * 6.02e23 atoms/mol # of electron /sec = ua / (1.602e-19 C per e - ) 24
RATE ESTIMATION rate = I ρ l / A Ωeff dσ dω dω = I ρ l / A Ωtot dσ dω ε(ω)dω Ωtot Ωeff ε(ω) = 0 if 1. Events generated in that phase space area can not arrive the focal plane 2. Events in that area is unphysical (i.e. w 2 <0) 25
RATE ESTIMATION rate = I ρ l / A Ωeff dσ dω dω = I ρ l / A Ωtot dσ dω ε(ω)dω Ωtot Ωeff rate MC = I ρ l / A N tot dσ dω ε(ω) Ω tot N tot 26
RATE ESTIMATION 20 ua rate MC = I ρ l / A N tot dσ dω ε(ω) Good events in simulation and XEMC Ω tot N tot efficiency # of trials in simulation (!! The single arm simulation will only record good events) Cross section tables generated from XEMC model: - from Zhihong - Included bremsstrahlung radiation - y-scaling. Use He3 fitting parameter for H3 27