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
11/05/2019 Calibration Task Forth meeting
Neutron Energy [keV] 20 40 60 80 [b]
tot
σ
3 −
10
2 −
10
1 −
10 1 10
2
10
3
10
ENDF natural Ar Winters
Slide 2
§ 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
Slide 3
§ 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
Slide 5
Start Finish Config Total Hours fraction good Good Air/N2 Good LAr Good GAr GAr+C shutter 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
𝑈! = transmission in TOF channel i 𝐷!
"#$=dead-time corrected counts for liquid argon sample measurement
𝐷!
%#$= dead-time corrected counts for gaseous argon sample measurement
𝐶!
"#$ = background counts for liquid argon measurement
𝐶!
%#$ = background counts for gaseous argon measurement
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
𝑈! = 𝐷!
"#$ − 𝐶! "#$
𝐷!
%#$ − 𝐶! %#$
𝑛𝑝𝑜%#$ 𝑛𝑝𝑜"#$ 𝜏! = − 1 𝑜"#$ − 𝑜%#$ ln 𝑈!
§ Gas argon:
– density: 1.289 g/L – Column density: 𝑜"#$ = 168𝑑𝑛 1.289×10&'
( )*- O +.-.×0-.-/0123
4
'1.123 5
4
1×
0-6.7)*. 45$6
= 0.003248 𝑏𝑢𝑝𝑛𝑡/ 𝑐𝑏𝑠𝑜
§ Liquid argon:
– density: 1.395 g/cm3 – Column density: 𝑜%#$ = 168𝑑𝑛 1.395
( )*- O +.-.×0-.-/0123
4
'1.123 5
4
1×
0-6.7)*. 45$6
= 3.5 𝑏𝑢𝑝𝑛𝑡/𝑐𝑏𝑠𝑜
§ Instead of measuring the counts for vacuum-filled target, we measured the counts for Gas-argon-filled target. We need to use the effective column density n in the the cross-section formula
Slide 7
𝜏! = − 1 𝑜 ln 𝑈! 𝑜 = 𝑜"#$ − 𝑜%#$ = 3.496752 (𝑏𝑢𝑝𝑛𝑡/𝑐𝑏𝑠𝑜)
Slide 8
“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 9
§ 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 10
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
7. Shutter closed “CIT” background (gammas from beam) 8. Beam off CIT background (constant background) 9. PMT after pulsing
Slide 12
Slide 13
§ 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 14
TOF_measured [ns]
4
10
5
10
6
10 Error [ns]
2
10
3
10
4
10
Plus error Minus error
TOF error
Cd resonance region Al and Ar resonance region
Energy [MeV]
5 −
10
4 −
10
3 −
10
2 −
10
1 −
10 1 Error [MeV] 5 − 5
Plus energy error Minus energy error
Energy error
Slide 15 Cd resonance region Al and Ar resonance region
Slide 16
!
§ The TOF-Energy correlation is fitted using the following formula:
ENDF Energy [eV] 50 100 150 200 Corrected Time of Flight [us] 400 600 800
/ ndf
2
χ 2.144 / 4 Prob 0.7092 L 0.8341 ± 63.37 T ∆ 6.496 ± 3.858 / ndf
2
χ 2.144 / 4 Prob 0.7092 L 0.8341 ± 63.37 T ∆ 6.496 ± 3.858 ENDF Cd resonance
Slide 17
§ The fit for Cd gives an flight path of 63.37 m.
§ The fit for Ar and Al gives the same flight path of 63.37 m
Slide 18
ENDF Energy [eV] 50 100 150 200 250
3
10 × Corrected Time of Flight [us] 10 15 20 25
/ ndf
2
χ 6.654 / 4 Prob 0.1553 L 0.8949 ± 63.37 T ∆ 0.1734 ± 0.2749 − / ndf
2
χ 6.654 / 4 Prob 0.1553 L 0.8949 ± 63.37 T ∆ 0.1734 ± 0.2749 −
ENDF Ar resonance ENDF Al resonance
Energy [eV] from TOF 100 200 300 400 500
3
10 × Xsec [barn] 5 10 15 20 ENDF Al-27 Al (log bin) Al: Xsec VS Energy (log bin)
Slide 19
§ 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):
Energy [eV] from TOF 100 200 300 400 500
3
10 × Xsec [barn] 5 10 15 20 ENDF Al-27 Al (log bin) Al: Xsec VS Energy (log bin)
Before energy calibration After energy calibration
§ 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
Slide 21
CTOF_Log10Ene Entries 4162105 Mean 292.4 RMS 942.9
Energy [eV] from TOF 10
2
10
3
10
4
10
2
10
3
10
4
10
CTOF_Log10Ene Entries 4162105 Mean 292.4 RMS 942.9
CTOF_Log10Ene
27 eV Cd-111 67 eV Cd-112
Run020855 ENDF
85 eV Cd-113 89 eV Cd-110 164 eV Cd-111 192 eV Cd-113