1. Systematics of the SNS n- 3 He Experiment Christopher Crawford University of Kentucky for the n- 3 He Collaboration APS April Meeting Denver, CO, 2013-04-16

2. Overview – Hadronic Weak Interaction (HWI) Hadronic Nuclear EW Nuclear PV Few-body PV Viviani et al, PRC 82 (2010), 044001 Wasem, PRC 85 (2012), 022501 2/10

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

4. Asymmetry Measurement – Statistics  Extract physics asymmetry from single-wire spin asymmetries – operating in current-mode: t, p downstream background  Two independent simulations: 1.a code based on GEANT4 2.a stand-alone code including wire correlations N = 1.5x10 10 n/s flux (chopped) x 10 7 s (116 days) P = 96.2%neutron polarization  d = 6detector efficiency  15% measurement in 1 beam cycle (without contingency), assuming A z = 1.15 x 10 -7 = 1.6 x 10 -8 4/10

5. Systematic Uncertainties  Beam fluctuations, polarization, RFSF efficiency:  k n r ~ 10 -5 small for cold neutrons  PC asymmetries minimized with longitudinal polarization  Alignment of field, beam, and chamber: 10 mrad achievable  Unlike n p -> d ° or n d -> t °, n 3 He is very insensitive to gammas (only Compton electrons) 5/10

6. Transverse RF spin rotator  Resonant RF spin rotator P-N Seo et al., PRSTAB 11, 084701 (2008)  Properties suitable for n- 3 He expt. Transverse horizontal RF B-field Longitudinal or transverse flipping No fringe field - 100% efficiency Real, not eddy currents along outside minimizes RF leaked outside Doesn’t affect neutron velocity Compact geometry Matched to the driver electronics of 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 6/10

7. Target Ion Chamber  Chamber all aluminum except for the knife edges. 4 feedthrough ports (153 readout channels) 2 HV ports + 2 gas inlets/outlets 12 inch aluminum windows (0.9 mm thick).  Macor wire frames Platinum-gold thick film wire solder pads  Filled with 1 atm of 3 He 7/10

8. Assembly in the FnPB cave 8/10

9. Commissioning / run plan 1. Scan beam profile upstream and transfer centroid to crosshairs 2. Scan beam profile downstream 3. Align theodolite to crosshairs 4. Align B-field to theodolite 5. Field map in RFSR/Target region 6. Align the position / angle of target with theodolite / autocollimator 7. Tune RSFR / measure polarization 8. Measure physics asymmetry 9/10

10. Summary n- 3 He collaboration  Last measurement for the a characterization of the Hadronic Weak Interaction  15% projected uncertainty will be the most accurate HWI experiment in a few-body system  Scheduled FnPB beam time June 2014 – Dec 2015 10/10

12. Theoretical calculations – progress  Gerry Hale (LANL) PC A y ( 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: J π = 0 +, 0 -, 1 +, 1 - -Tested against n- 3 He scattering lengths evaluation of weak 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 V NN EFT, a 0 – a 5 Viviani, PAVI (2011), preliminary

13. EFT NN potential revisited to NNLO  Viviani et al., preliminary (PAVI 11) (a) Q 0 h 1 π g π (r) (CT) Q 1 C 1,2,3,4,5 Z(r) (b,c) Q 2 zero (e,h) Q 2 renorm./absorb in h 1 π (d), Q 2 h 1 π+ C 3 (triangle) L(r) (f,g,g’) Q 2 h 1 π (box) H(r)+L(r) A z n3He (prelim) using N3LO (Emtem & Macheleidt) + 3N N2LO (Navratil) Λ = 500: a 0 =-0.15 a 1 =.026 a 2 =.021 a 3 =0.11 a 4 =-.043 a 5 =-.0022

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

15. 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 3 He analyzer

16. 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

17. 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

18. 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

19. 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- 3 He (high channel density, 10x larger signal)

20. Data Acquisition  Scope: 128 channels of 16/24 bit ADC, > 60 KS/s $51k data 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

21. 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 perform dry 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