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The n- 3 He Experiment

The n- 3 He Experiment. Christopher Crawford University of Kentucky for the n- 3 He Collaboration FnPB PRAC ORNL, TN 2013-01-23. Outline. Physics Reaction & observable EFT calculation Statistical sensitivity Systematic effects Experimental design Experimental setup

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The n- 3 He Experiment

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  1. The n-3He Experiment Christopher Crawford University of Kentucky for the n-3He Collaboration FnPB PRAC ORNL, TN 2013-01-23

  2. Outline • Physics • Reaction & observable • EFT calculation • Statistical sensitivity • Systematic effects • Experimental design • Experimental setup • Installation at FnPB • Commission & run plan • ES&H issues • Collaboration • Organization / Manpower • WBS subpackages • Neutron beamline • Stand / Alignment • Magnetic field • RF Spin Rotator • Target Chamber • Preamps • Data Acquisition • Project • Timeline • Resources

  3. n-3He PV asymmetry p n p 20.578 19.815 n p + + n PV observables: n n n p p p • Sensitive to isoscalar couplings (I=0) of the Hadronic Weak Interaction • Complementary to NPDGamma (I=1)and p-p scattering (I=0 & 2) • Large asymmetry A = 1.15 x 10-7Viviani, et al., PRC 82, 044001 (2010), Tilley, Weller, Hale, Nucl. Phys. A541, 1 (1992)

  4. Theoretical calculations – progress • Gerry Hale (LANL) PC Ay(90) = -1.7 +/- 0.3 x 10-6 • R matrix calculation of PC asymmetry,nuclear structure , and resonance properties • Michele Viviani et al. (INFN Pisa) PV A = -(.248 – .944)£10-7 • full 4-body calculation of scattering wave function • Kohn variational method with hyperspherical functions • No parity mixing in this step: Jπ = 0+, 0-, 1+, 1- • Tested against n-3He scattering lengths • evaluation of weak <J-|VPV|J+> matrix elements • In terms of DDH potential Viviani, Schiavilla, Girlanda, Kievsky, Marcucci, PRC 82, 044001 (2010) Girlanda, Kievsky, Marcucci, Pastore, Schiavilla, Viviani, PRL 105 232502 (2010) • Vladimir Gudkov (USC) PV A = -(1 – 4)£10-7 • PV reaction theory Gudkov, PRC 82, 065502 (2010) • Michele Viviani et al. (INFN Pisa) PV VNNEFT, a0 – a5 Viviani, PAVI (2011), preliminary

  5. Sensitivity matrix for few-body reactions Contribution: 1.15 0.087 1.55 – -.002 -0.47 –

  6. EFT NN potential revisited to NNLO • Viviani et al., preliminary (PAVI 11) • (a) Q0 h1π gπ(r) • (CT) Q1 C1,2,3,4,5 Z(r) • (b,c) Q2 zero • (e,h) Q2 renorm./absorb in h1π • (d), Q2 h1π+C3 (triangle) L(r) • (f,g,g’) Q2 h1π (box) H(r)+L(r) Azn3He (prelim) using N3LO (Emtem & Macheleidt) + 3N N2LO (Navratil) Λ = 500: a0=-0.15 a1=.026 a2=.021 a3=0.11 a4=-.043 a5=-.0022

  7. Experimental setup longitudinal holding field – suppressed PC nuclear asymmetry A=1.7x10-6(Hales) sn  kn x kpsuppressed by two small angles RF spin flipper – negligible spin-dependence of neutron velocity 3He ion chamber – both target and detector supermirror bender polarizer (transverse) FnPB cold neutron guide 10 Gauss solenoid 3He Beam Monitor RF spinrotator 3He target / ion chamber FNPB n-3He

  8. MC Simulations • Two independent simulations: • a code based on GEANT4 • a stand-alone code including wire correlations • Ionization at each wire plane averaged over: • neutron beam phase space • capture distribution • ionization distribution (z) • uniform distribution of proton angles cos n¢kp/kp • Used to calculate detector efficiency (effective statistics / neutron flux)

  9. MC Simulations – Results • Majority of neutron captures occur at the very front of chamber • Self-normalization of beam fluctuations • Reduction in sensitivity to A

  10. Runtime estimate for n-3He at FnPB • N = 1.5x1010 n/s flux (chopped) x 107 s (116 days) • P = 96.2% neutron polarization • d = 6 detector efficiency • 15% measurement in 1 beam cycle (without contingency), assuming Az= 1.15 x 10-7 = 1.6 x 10-8

  11. Systematics • Beam fluctuations, polarization, RFSF efficiency: • knr ~ 10-5 small for cold neutrons • PC asymmetries minimized with longitudinal polarization • Alignment of field, beam, and chamber: 10 mrad achievable • Unlike NPDG, NDTG: insensitive to gammas (only Compton electrons)

  12. Assembly in the FnPB cave

  13. Commissioning / run plan • Scan beam profile upstreamand transfer centroid to crosshairs • Scan beam profile downstream • Align theodolite to crosshairs • Align B-field to theodolite • Field map in RFSR/Target region • Align the position / angle of target with theodolite / autocollimator • Tune RSFR / measure polarization • Measure physics asymmetry

  14. ES&H Issues • Radiation much lower than from NPDGamma • IRR will cover 3 activities: • Front and back beam scans 3He detector + 6Li aperture • Polarimetry 3He polarizer + 3He monitor • Physics data run 3He target/detector • Beam friendly materials • Aluminum windows transparent to neutrons • 3He, 6Li have large cross section with no γ radiation • Graduate student will create MCNP model based on NPDG • Will be validated by radiation group • No other safety concerns • No HV, pressure, vacuum, cryogenics, ladders, …

  15. n-3He collaboration • Spokespersons D. Bowman, M. Gericke, C. Crawford • Local Project Manager S. Penttila • Project Engineer Rick Allen • Work Subpackage Leaders M. Gericke Beam monitors G. Greene Polarimetry L. Barrón Magnetic fields C. Crawford Spin rotator M. Gericke Target chamber J. Hamblen Preamplifiers I. Novikov Data acquisition D. Bowman Alignment J. Calarco Shielding

  16. Neutron beamline • Scope: • FnPB guide, polarizer, beam monitors (existing, NPDG) • Beam profile scanners, polarimetry • Status: • All equipment exists except aluminum aperture / crosshair • Must design shielding to accommodate xy-scanner • Must design mount for 3He analyzer

  17. Alignment • Scope: • Aperture / crosshairs for beam scan • Support stand and xy-adjustment for theodolite • Alignment V-block for trimming B-field • Optical system and adjustable mount for target • Progress: • Conceptual design

  18. Magnetic field • Scope: • Magnetic field simulations to verity adiabatic spin rotation and uniformity • Design and construct longitudinal solenoid and frame • Map fields at UNAM before delivery to SNS • Status: • Conceptual design, preliminary calculations indicate adiabaticity 15 coils, 15 cm apart, 35 cm radius, 150 A turns

  19. Transverse RF spin rotator • Resonant RF spin rotator • P-N Seo et al., Phys. Rev. S.T. Accel. Beam 11, 084701 (2008) • Properties suitable for n-3He expt. • Transverse horizontal RF B-field • Longitudinal or transverse flipping • No fringe field - 100% efficiency • Real, not eddy currents along outsideminimizes RF leaked outside SR • Doesn’t affect neutron velocity • Compact geometry • Matched to the driver electronicsof the NPDGamma spin flipper • Construction • Development in parallel with similar design for nEDM neutron guide field • Few-winding prototype built at UKy; Production RFSF being built now NPDGamma windings n-3He windings field lines end cap windings

  20. Inner / outer coil design • Windings calculated using scalar potential • Uniform transverse RF field inside • Zero leakage field enforced by B.C.’s • Copper wires run along equipotentials • Inner region: • Intermediate: • Outer region: • 4:1 inside / outside winding ratio • By choosing appropriate radii • Perfect cos theta windings inside & out • 48 inner loops of 18 AWG wire

  21. Electrical specifications – compatible with NPDG • Holding field: • Resonant frequency: • Inductance: 4.5 mH • Capacitance: 7.5 nF • Resistance: 5.1 Ω • Maximum voltage: • Stored energy: • Dissipated power: • Quality factor: Q=151 • R&D: test 3 winding patterns with same field in high-frequency limit INNER INNER/OUTER OUTER easiest to wind no eddy currents no copper in beam

  22. Progress & Schedule • Design completed in 2011 • Resonator machined except wire grooves • March 2013:Finish machining • May 2013:Finish winding • September 2013:RF field map • November 2013:Test with preamps and DAQ system

  23. Target Chamber • Chamber design finished in 2010 • delivered to U. of Manitoba, Fall 2010 • All aluminum except for the knife edges. • 4 feedthrough ports (200 readout channels) • 2 HV ports + 2 gas inlets/outlets • 12 inch Conflat aluminum windows (0.9 mm thick).

  24. Frame Design and Construction • Chamber frame design finished in 2012 • Received 50 Macor wire frames (up to 25 signal and 25 HV) $30K • Final feature machining planned for early this year at UT shop. • Platinum-Gold thick film wire solder pads on Macor to be completed early this year by Hybrid Sources Inc..

  25. Frame Assembly and Signal Readout • The frame mounting structure is designed • pieces will be ordered in the spring • Two options for frame mounting: • Mount into exit flange with threaded rods • Insert into existing exit window flange • Signal readout via circuit board traces • Single HV connections • Guide wires to feedthroughs with PMT- inspired stand-offs and ceramic beads

  26. Target Chamber Assembly Schedule • February 2013: Have test frame finished by Hybrid Sources and verify measurements. • March 2013: Complete feature machining at UT shop. • April 2013: Order remaining parts for frame assembly and feedthroughs. • June-July 2013: Completed solder pad deposition by Hybrid Sources. • October 2013: Complete chamber assembly • December 2013: Testwith RFSF and DAQ

  27. Preamps • Scope • 4 boxes with 32 channels each$41k • Design and fabricate circuit, and mechanical enclosure • Connector to Target Chamber port and cabling to DAQ module • Status – on critical path – need resources soon! • Have preliminary design (from NPDG preamps) • Must modify circuit for n-3He (high channel density, 10x larger signal)

  28. Data Acquisition • Scope: • 128 channels of 16/24 bit ADC, > 60 KS/s $51kdata acquisition software; RAID storage array $25k • Status – need resources soon to begin development and testing! • selected candidate system D-tAcq CQ196CPCI-96-500 • Each card 96 sim. channels + antialiasing filters + FPGA signal proc.runs Linux on 400MHz XScale processor with Gigabit Ethernet • Inexpensive cPCI chassis used only for power and cooling • DAQ software included with hardware – turn-key system • awaiting funds to purchase and test system

  29. Equipment summary • FnPB / NPDG hardware • 3He beam monitor • SM polarizer • Beam position monitor • Radiation shielding • Pb shield walls • Beam Stop • New equipment • Longitudinal field solenoid mounted on stand • Longitudinal RFSF resonator mounted in solenoid • 3He target/ion chamber mounted in solenoid • Preamps mounted on target • Data acquisition system + RAID storage • NPDG electronics • B-field power supply • RFSF electronics • Trigger electronics • SNS / chopper readout • Fluxgate magnetometers • Computer network

  30. Timeline • Construction of subsystems in parallel • Will be ready for beam at beginning of cycle Aug 2014 • Critical path: preamp design and construction (possibly DAQ) • Will stage experiment in EDM building and performdry run of field map, beam map, and alignment procedures • See Gantt chart for details • Milestones • 2014-04-21 Begin assembly and testing in EDM building • 2014-07-18 Begin installation in FnPB cave • 2014-10-27 IRR – begin commissioning phase • 2015-02-?? Physics data taking at beginning of beam cycle • Time budget • 76 days commissioning (all equipment pre-assembled) • 15 days PC transverse asymmetry 1.7 x 10-6 ± 0.5 x 10-7 • 116 days PV longitudinal asymmetry 1.15 x 10-7 ± 1.6 x 10-8

  31. Resources • All equipment funded except Preamp, DAQ, RAID ($117k) • UNAM: (CONACYT $31k) Solenoid and support stand • U. Kentucky: (NSF $23k)RF spin rotator • U. Manitoba: (NSERC $111k)Target chamber • Minimal utilization of SNS crafts • Most equipment mounted on single support structure,staged in the EDM building, craned onto NPDG det. support • 3D solid model will be drafted by graduate (Mark McCrea),reviewed by SNS engineer, and incorporated into SNS model • MCNP radiation simulation will created by UKy graduate,validated by radiation group • Machining will be done at university shops • Alignment is relative to beam scan • Total P-Division operations budget request ($200k) • $117k for DAQ + $83k for Engineering/Radiation/Craft support • See budget spreadsheet for details

  32. Standing in between elephants

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