Supermirror polarizer and beam simulations Christopher Crawford UKy
Supermirror polarizer and beam simulations Christopher Crawford (UKy) NPDGamma Collaboration Meeting ORNL, 2010 -10 -15
Outline § Mc. Stas simulations of beam profile § Characterization of SM polarizer by Swiss Neutronics § Analysis of FP 12 statistics
Fn. PB supermirror polarizer Fe/Si on boron float glass, no Gd m = 3. 0 n = 45 r = 9. 6 m l = 40 cm d = 0. 3 mm critical angle channels radius of curvature length vane thickness T=25. 8% P=95. 3% N=2. 2£ 1010 n/s transmission polarization output flux (chopped) simulations using Mc. Stas / ROOT ntuple
Mc. Stas Simulations
Transmission Comparison Presented at collab, mtg. 2007 -02 -23 34% -> 26% Transmission Changes: -Fe/Si coating -No Gd undercoat -No line of sight
Transmission
Comparison of optimal stats. vs. open pedestal after chopper, pedestal
Comparison of optimal stats. vs. open pedestal after chopper, pedestal
Polarization Comparison Presented at collab, mtg. 2007 -02 -23 95. 6% Polarization Changes: -Fe/Si coating -No Gd undercoat -No line of sight
Polarization Comparison Presented at collab, mtg. 2007 -02 -23 95. 6% -> 95. 3% Polarization Changes: -Fe/Si coating -No Gd undercoat -No line of sight
Neutron Flux vs. wavelength, position in vane from polarimetry MRI proposal
Polarization vs. wavelength, position in vane
Neutron flux vs. Λ, Θx
Polarization vs. Λ, Θx
Beam profile before and after Smpol before horizontal after vertical
Beam profile at 1 st lead wall
Beam profile at 2 nd lead wall
Beam profile at LH 2 target
Horizontal profile vs. dist. from SMpol
Vertical profile vs. dist. from SMpol
SM polarizer characterization by Swiss Neutronics at PSI
Specifications from SNAG Waviness
Individual Vanes – 2
Individual Vanes – 6
Individual Vanes – 10
Individual Vanes – 14
Individual Vanes – 19
Individual Vanes – 22
Individual Vanes – 26
Individual Vanes – 26 R
Reflectivity profile use in Mc. Stas simulations Mc. Stas R+ , P
Reflectivity profile use in Mc. Stas simulations Mc. Stas R+ , P
Transmission measurement at PSI
Polarization measurement at PSI
Polarization measurement data
Measurement of Flux at FP 12 Americo Salas Bacci, et al. Technical Note #3
LANSCE FP 12 Neutron Flux Measurement Americo Salas Bacci, Technical Note #3
LANSCE FP 12 Neutron Flux – Electronics
Fission Chamber energy spectrum from Americo
LANSCE FP 12 Neutron Flux – Electronics
Comparison of statistics at LANSCE FP 12 § Calculation based on: David’s estimate 2010 -09 -24, Americo’s note 2010 -10 -14, and Gericke, NIMA 611 239 (2009) § 2. 68 x 107 n/s cm 2 neutron flux at 100 μA, measured with FC § 3. 5” collimator, 87. 6 μA proton current § 4966 runs (after cut) x 104/20 Hz § 0. 88 (air) x 0. 90 (Al) x 0. 88 (glass) x 0. 346 (3 He) transmission § 0. 60 capture in LH 2 x 0. 3017 geom. factor § 0. 53 pol. 3 He x 0. 989 SF eff. / (1+0. 25) bkg. dilution § δA = 1. 9 x 10 -7 from above vs. 2. 1 x 10 -7 RMS width in A § Comparison of raw counts vs. above estimate?
- Slides: 41