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The n- 3 He Project Christopher Crawford University of Kentucky for the n- 3 He Collaboration n-3He...
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Transcript of The n- 3 He Project Christopher Crawford University of Kentucky for the n- 3 He Collaboration n-3He...
The n-3He Project
Christopher CrawfordUniversity of Kentucky
for the n-3He 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• 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
n-3He PV asymmetry
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 10-7
Viviani, et al., PRC 82, 044001 (2010),
PV observables:
19.81520.578
Tilley, Weller, Hale, Nucl. Phys. A541, 1 (1992)
nn + nn pp ppnn ppnn +pp nn pp
nnpp
10 Gausssolenoid
RF spinrotator
3He target /ion chamber
supermirrorbender polarizer
(transverse)
FnPB coldneutron guide
3He BeamMonitor
FNPB n-3He
Experimental setup
longitudinal holding field – suppressed PC nuclear asymmetry A=1.7x10-6 (Hales) sn kn x kp suppressed by two small angles
RF spin flipper – negligible spin-dependence of neutron velocity
3He ion chamber – both target and detector
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, …
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
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
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
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
NPDGammawindings
n-3Hewindings
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
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)
Data Acquisition
Scope: • 128 channels of 16/24 bit ADC, > 60 KS/s $25k
data 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
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
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
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 perform
dry 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
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