ARTIE Data Analysis Plan Jingbo Wang 11/05/2019 Calibration Task - PowerPoint PPT Presentation

ARTIE Data Analysis Plan Jingbo Wang 11/05/2019 Calibration Task Forth meeting

Goal of ARTIE § The goal of ARTIE is to measure the neutron total cross-section around 57 keV in natural argon, using a liquid argon target with a column density of 3.5 atoms/barn. 3 10 [b] ENDF natural Ar tot 2 10 σ Winters 10 1 − 1 10 − 2 10 − 3 10 20 40 60 80 Neutron Energy [keV] Slide 2

Target Setup Slide 3

ARTIE Measurement Strategy § ACED took sufficient data during the October 8-20 beam run at LANL § Several types of data were taken: – Beam off : understand constant-in-time backgrounds – Beam on, shutter closed: understand the beam-related backgrounds (gammas, skyshine neutron) – Liquid argon filled, beam on: sample-in neutron transmission counting – Gaseous argon filled, beam on : sample-out neutron transmission counting – Aluminium filter in, beam on : understand the background from scattering in the beam pipe – Carbon target, beam on: reference material measurement Slide 4

ARTIE Runs Total fraction shutter Start Finish Config Hours good Good Air/N2 Good LAr Good GAr GAr+C close 1in Al 10/10/19 8:50 PM 10/11/19 8:00 AM Some N2 to Air 11.17 1.00 11.17 10/11/19 9:20 AM 10/11/19 7:30 PM LAr 10.17 0.75 7.62 GAr 4.00 1.00 4.00 10/12/19 12:00 AM 10/14/19 9:00 AM Air 57.00 1.00 57.00 10/14/19 4:00 PM 10/15/19 12:41 PM LAr 20.68 0.75 15.51 10/15/19 12:41 PM 10/15/19 2:10 PM shutter close 1.48 1.00 1.48 10/15/19 5:46 PM 10/17/19 8:00 AM LAr 38.23 0.75 28.68 10/17/19 8:00 AM 10/17/19 2:40 PM LAr+GAr shutter close 6.67 1.00 6.67 10/17/19 1:00 PM 10/17/19 6:00 PM GAr 5.00 1.00 5.00 10/17/19 6:30 PM 10/17/19 9:00 PM GAr+1 C 2.50 1.00 2.50 10/17/19 10:00 PM 10/18/19 8:30 AM 1in Al 10.50 1.00 10.50 10/18/19 12:00 PM 10/18/19 6:00 PM LAr 6.00 0.75 4.50 10/18/19 7:30 PM 10/19/19 8:00 AM LAr to GAr with 2C 12.50 1.00 12.50 10/19/19 8:00 AM 10/19/19 4:30 PM GAr, beam down 8.50 0.00 10/19/19 4:30 PM 10/19/19 8:30 PM GAr 4.00 1.00 4.00 10/19/19 8:30 PM 10/20/19 8:00 AM Air 11.50 1.00 11.50 HOURS: 79.67 56.31 13.00 15.00 8.15 10.50 Slide 5

Cross-section Measurement "#$ − 𝐶 ! "#$ 𝑛𝑝𝑜 %#$ 𝑈 ! = 𝐷 ! %#$ − 𝐶 ! %#$ 𝑛𝑝𝑜 "#$ 𝐷 ! 1 𝜏 ! = − ln 𝑈 ! 𝑜 "#$ − 𝑜 %#$ 𝑈 ! = transmission in TOF channel i "#$ =dead-time corrected counts for liquid argon sample measurement 𝐷 ! %#$ = dead-time corrected counts for gaseous argon sample measurement 𝐷 ! "#$ = background counts for liquid argon measurement 𝐶 ! %#$ = background counts for gaseous argon measurement 𝐶 ! 𝑛𝑝𝑜 %#$ = monitor counts for liquid argon measurement 𝑛𝑝𝑜 "#$ = monitor counts for gaseous argon measurement 𝜏 ! = total cross-section in TOF channel i 𝑜 "#$ = column density of liquid argon target (atoms/barn) 𝑜 %#$ = column density of gaseous argon target (atoms/barn) Slide 6

Effective column density § Gas argon: – density: 1.289 g/L +.-.×0- .-/0123 0- 6.7 )* . ( 1.289×10 &' Column density: 𝑜 "#$ = 168𝑑𝑛 )* - O 4 1× = 0.003248 𝑏𝑢𝑝𝑛𝑡/ – '1.123 5 45$6 4 𝑐𝑏𝑠𝑜 § Liquid argon: – density: 1.395 g/cm3 +.-.×0- .-/0123 0- 6.7 )* . ( – Column density: 𝑜 %#$ = 168𝑑𝑛 1.395 )* - O 4 1× = 3.5 𝑏𝑢𝑝𝑛𝑡/𝑐𝑏𝑠𝑜 '1.123 5 45$6 4 § Instead of measuring the counts for vacuum-filled target, we measured the counts for Gas-argon-filled target. We need to use the effective column density n in the the cross-section formula 𝜏 ! = − 1 𝑜 ln 𝑈 ! 𝑜 = 𝑜 "#$ − 𝑜 %#$ = 3.496752 (𝑏𝑢𝑝𝑛𝑡/𝑐𝑏𝑠𝑜) Slide 7

“Black resonance” Technique “black resonance” method: placing material in the neutron beam that have resonances with large cross sections at specific neutron energies. This allows us to remove all the neutrons in the beam at that energy, leaving only the off-energy neutrons and gamma rays to interact with the detector https://core.ac.uk/download/pdf/38628834.pdf An example Slide 8

ARTIE “Black resonance” measurements § In ARTIE, we have several types of filters in the beam: Bi, Au, Cd, Al, § The thickness of these filters are not optimized for “black resonance” measurement, so not all of them are “black” § Decent black resonance filters: – Cd (<0.025 eV) – Al (35 keV) – Liquid argon (75 – 95 keV, 175 -190 keV) § Issues: – 1 inch Al filter was not thick enough to block all the 35 keV neutrons. Need to fit the data to known cross-section to study the background level. § We need detailed simulations to help understand the background level Slide 9

Slide 10

ARTIE Systematics (1) 1. LAr Contamination 2. Effective density of LAr 3. Energy resolution a. Time jitter in PMTs b. Time jitter in T0 signal c. Translation of time to energy (absolute scale) d. MCNP moderator function uncertainty 4. Beam intensity stability and systematic shift 5. Gas target scattering background, Al black resonance 6. Liquid target scattering background, Ar black resonance Slide 11

ARTIE Systematics (2) 7. Shutter closed “CIT” background (gammas from beam) 8. Beam off CIT background (constant background) 9. PMT after pulsing 10. Beam alignment stability 11. Detector efficiency stability 12. Ice buildup on target 13. Air pressure changes due to weather affecting air, Gar, and N2 density 14. Dead time correction Slide 12

Energy Calibration § The moderator adds a time delay that is energy dependent. § 2D moderator function is simulated for 10 m flight path using MCNP. The moderator response can be scaled to any particular length of flight path. § The moderator function is asymmetric. The median of the moderator response distribution was subtracted from the measured TOF. Then the well-known resonance energies (Cd, Ar, Al) were used to calibrate TOF § The median of the moderator function was subtracted from the measured TOF 1D slice at 57 keV Slide 13

Error on TOF TOF error Error [ns] Plus error 4 10 Minus error 3 10 2 10 Cd resonance region Al and Ar resonance region 5 6 4 10 10 10 TOF_measured [ns] Slide 14

Error on Energy Energy error Error [MeV] Plus energy error Minus energy error 5 0 Cd resonance region Al and Ar resonance region − 5 − − − − − 5 4 3 2 1 10 10 10 10 10 1 Energy [MeV] Slide 15

TOF-Energy Correlation § The TOF-Energy correlation is fitted using the following formula: 𝑀 𝑈 = + ∆𝑈 1 𝑑 1 − ! 𝐹 1 + 𝑛𝑑 ! 𝑛𝑑 ! = rest mass energy of a neutron 𝑈 = neutron Time − of − Flight ∆𝑈 = Time offset Slide 16

Cd resonance § The fit for Cd gives an flight path of 63.37 m. χ χ 2 2 / ndf / ndf 2.144 / 4 2.144 / 4 0.7092 0.7092 Prob Prob ± ± 63.37 63.37 0.8341 0.8341 L L Corrected Time of Flight [us] ∆ ∆ ± ± T T 3.858 3.858 6.496 6.496 800 ENDF Cd resonance 600 400 50 100 150 200 ENDF Energy [eV] Slide 17

Ar + Al resonance § The fit for Ar and Al gives the same flight path of 63.37 m χ χ 2 2 / ndf / ndf 6.654 / 4 6.654 / 4 Prob Prob 0.1553 0.1553 ± ± 25 L L 63.37 63.37 0.8949 0.8949 Corrected Time of Flight [us] ∆ ∆ − − ± ± T T 0.2749 0.2749 0.1734 0.1734 ENDF Ar resonance 20 ENDF Al resonance 15 10 × 3 10 50 100 150 200 250 ENDF Energy [eV] Slide 18

Initial Result on Energy Calibration § The correlation between measured TOF and the know resonance energy is fit using the theoretical formula § The length of the flight path and the time offset are set to be the free parameters in the fit. § Data analysis for Al after energy calibration (without background subtraction): After energy calibration Before energy calibration Al: Xsec VS Energy (log bin) Al: Xsec VS Energy (log bin) Xsec [barn] Xsec [barn] ENDF Al-27 20 ENDF Al-27 20 Al (log bin) Al (log bin) 15 15 10 10 5 5 0 0 × 3 10 × 3 10 100 200 300 400 500 100 200 300 400 500 Energy [eV] from TOF Energy [eV] from TOF Slide 19

To-Do: § Understand all the systematics in ARTIE. This is important for the precision needed for the antiresonance. § Use carbon and aluminium data to study the systematics § Run realistic simulations to help understand the background model § Apply background subtraction to liquid argon data and perform analysis for the total cross-section. § Tasks of data analysis are assigned to the group members. We aim at presenting the first cross-section result soon. Slide 20

Cd resonance CTOF_Log10Ene CTOF_Log10Ene CTOF_Log10Ene Entries Entries 4162105 4162105 4 10 Run020855 Mean Mean 292.4 292.4 RMS RMS 942.9 942.9 85 eV Cd-113 192 eV Cd-113 27 eV Cd-111 67 eV 3 164 eV 10 Cd-112 Cd-111 89 eV Cd-110 2 10 3 2 4 10 10 10 10 Energy [eV] from TOF ENDF Slide 21