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

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

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?