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The n- 3 He Project

The n- 3 He Project. Christopher Crawford University of Kentucky for the n- 3 He Collaboration n-3He Technical Review ORNL, TN 2013-01-08. Outline. Experiment design Physics reaction and observable Experimental setup Installation in the FnPB cave Commissioning and run plan

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The n- 3 He Project

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  1. The n-3He Project Christopher Crawford University of Kentucky for the n-3He Collaboration n-3He Technical Review ORNL, TN 2013-01-08

  2. Outline • Experiment design • Physics reaction and observable • Experimental setup • Installation in the FnPB cave • Commissioning and run plan • ES&H issues • Collaboration • Organization • Manpower • WBS subpackages • Neutron beamline • Magnetic field • RF Spin Rotator • Target Chamber • Preamps • Data Acquisition • Stand / Alignment • Timeline • Resources • P-Division needs

  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 = 1.3 x 10-7Viviani, et al., PRC 82, 044001 (2010), Tilley, Weller, Hale, Nucl. Phys. A541, 1 (1992)

  4. 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

  5. Assembly in the FnPB cave

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

  7. 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, …

  8. 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

  9. 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

  10. Magnetic field • Scope: • Magnetic field simulations to verity adiabatic spin rotation and uniformity • Design and construct longitudinal solenoid and frame • Unistructure frame to support RFSR, Target, alignment jigs, mounts on NPDG detector stand. • Status: • Conceptual design, preliminary calculations indicate adiabaticity 15 coils, 15 cm apart, 35 cm radius, 150 A turns

  11. Transverse RF spin rotator • Scope: • Design and construct RF resonator • Driving circuit (use NPDG electronics) • Status: • Prototype built and tested, DC current • Final design completed • Al shell & nylon winding forms machined • Need to wind RF coils and map field NPDGamma windings n-3He windings

  12. 3He Target / Ion Chamber • Scope: • Vacuum chamber, HV + sense wire frames. • Gas handling system • Status: • Chamber and Macor wire frames delivered • Beginning to string wire frames

  13. Preamps • Scope $15k • 4 boxes with 32 channels each • Design and fabricate circuit, and mechanical enclosure • Connector to Target Chamber port and cabling to DAQ module • Status – on critical path • Have preliminary design (from NPDG preamps) • Must modify circuit for n-3He (10x larger signal)

  14. Data Acquisition • Scope: • 128 channels of 16/24 bit ADC, > 60 KS/s $25kdata acquisition software; RAID storage array $15k • Progress: • selected candidate system D-tAcq CQ196CPCI-96-500 • Each card 96 sim. channels + antialias filters + FPGA signal proc.runs Linux on 400MHz XScale processor with gigabit ethernet • Inexpensive cPCI chasis used only for power and cooling • DAQ software included with hardware – turn-key system • awaiting funds to purchase and test system

  15. 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

  16. 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

  17. Timeline • Construction of subsystems in parallel • Expect to 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 • Milestones • 2014-06-30 Integration of experiment on common stand • 2014-08-10 IRR – begin commissioning phase • 2014-09-15 Begin physics data taking • Runtime • 45 days commissioning (all equipment pre-assembled) • 15 days PC transverse asymmetry 1.7 x 10-6 ± 1 x 10-7 • 208 days PV longitudinal asymmetry 1.3 x 10-7 ± 1 x 10-8

  18. Resources • All equipment funded except Preamp, DAQ, RAID ($60k) • 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 • P-Division operations budget request ($75k) • Mainly for Engineering/Radiation support, removal of NPDG • See budget spreadsheet for details

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