Transcript Hadronic PV and latest results – Neutron capture reactions

The n-3He Project
Christopher Crawford
University of Kentucky
for the n-3He Collaboration
n-3He Technical Review
ORNL, TN 2013-01-08
Outline
 Experiment design
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Physics reaction and
observable
Experimental setup
Installation in the
FnPB cave
Commissioning
and run plan
ES&H issues
 Collaboration
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Organization
Manpower
 WBS subpackages
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Neutron beamline
Magnetic field
RF Spin Rotator
Target Chamber
Preamps
Data Acquisition
Stand / Alignment
 Timeline
 Resources
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P-Division needs
n-3He PV asymmetry
n
+
20.578
p
n p
n
n pp
p
+
PV observables:
n
n p
19.815
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Sensitive to isoscalar couplings (I=0)
of the Hadronic Weak Interaction
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Complementary to NPDGamma (I=1)
and p-p scattering (I=0 & 2)
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Large asymmetry A = 1.3 x 10-7
Viviani, et al., PRC 82, 044001 (2010),
Tilley, Weller, Hale, Nucl. Phys. A541, 1 (1992)
Experimental setup
FnPB cold
neutron guide
supermirror
bender polarizer
(transverse)
10 Gauss
solenoid
3He
Beam
Monitor
RF spin
rotator
FNPB
3He
target /
ion chamber
n-3He
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longitudinal holding field – suppressed PC nuclear asymmetry
A=1.7x10-6 (Hales) sn  kn x kp suppressed by two small angles
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RF spin flipper – negligible spin-dependence of neutron velocity
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3He
ion chamber – both target and detector
Assembly in the FnPB cave
Commissioning / run plan
1. Field map in RFSR/Target region
2. Scan beam profile upstream
and transfer centroid to crosshairs
trim the field to longitudinal
6. Align the position / angle of target
with theodolite / autocollimator
3. Scan beam profile downstream
7. Tune RSFR / measure polarization
4. Align theodolite to crosshairs
8. Measure physics asymmetry
5. Align field probe with theodolite and
ES&H Issues
 Radiation much lower than from NPDGamma
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IRR will cover 3 activities:
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3He
detector + 6Li aperture
3He polarizer + 3He monitor
3He target/detector
Beam friendly materials
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Front and back beam scans
Polarimetry
Physics data run
Aluminum windows transparent to neutrons
3He, 6Li have large cross section with no γ radiation
Graduate student will create MCNP model based on NPDG
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Will be validated by radiation group
 No other safety concerns
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No HV, Pressure, vacuum, cryogenics, ladders, …
n-3He collaboration
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Spokespersons
D. Bowman, M. Gericke, C. Crawford
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Local Project Manager
S. Penttila
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Project Engineer
Rick Allen
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Work Subpackage Leaders
M. Gericke
G. Greene
L. Barrón
C. Crawford
M. Gericke
J. Hamblen
I. Novikov
D. Bowman
J. Calarco
Beam monitors
Polarimetry
Magnetic fields
Spin rotator
Target chamber
Preamplifiers
Data acquisition
Alignment
Shielding
Neutron beamline
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Scope:
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FnPB guide, polarizer, beam monitors (existing, NPDG)
Beam profile scanners, polarimetry
Status:
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All equipment exists except aluminum aperture / crosshair
Must design shielding to accommodate xy-scanner
Must design mount for 3He analyzer
Magnetic field
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Scope:
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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:
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Conceptual design, preliminary calculations indicate adiabaticity
15 coils, 15 cm apart, 35 cm radius, 150 A turns
Transverse RF spin rotator
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Scope:
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Design and construct RF resonator
Driving circuit (use NPDG electronics)
Status:
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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
3He
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Scope:
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Target / Ion Chamber
Vacuum chamber, HV + sense wire frames.
Gas handling system
Status:
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Chamber and Macor wire frames delivered
Beginning to string wire frames
Preamps
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Scope
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$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
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Have preliminary design (from NPDG preamps)
Must modify circuit for n-3He (10x larger signal)
Data Acquisition
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Scope:
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128 channels of 16/24 bit ADC, > 60 KS/s $25k
data acquisition software; RAID storage array $15k
Progress:
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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
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Scope:
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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:
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Conceptual design
Saturday, January 05, 2013
10:37 PM
Equipment summary
 FnPB / NPDG hardware
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3He
beam monitor
SM polarizer
Beam position monitor
Radiation shielding
Pb shield walls
Beam Stop
 NPDG electronics
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B-field power supply
RFSF electronics
Trigger electronics
SNS / chopper readout
Fluxgate magnetometers
Computer network
 New equipment
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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
Timeline
 Construction of subsystems in parallel
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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
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2014-06-30 Integration of experiment on common stand
2014-08-10 IRR – begin commissioning phase
2014-09-15 Begin physics data taking
 Runtime
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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
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All equipment funded except Preamp, DAQ, RAID ($60k)
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Solenoid and support stand
RF spin rotator
Target chamber
Minimal utilization of SNS crafts
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UNAM:
(CONACYT $31k)
U. Kentucky:
(NSF $23k)
U. Manitoba: (NSERC $111k)
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)
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Mainly for Engineering/Radiation support, removal of NPDG
See budget spreadsheet for details