Status update of
n-3He experiment
DOE FnPB Review, ORNL
2009-04-23
D. Bowman, S. Penttila
Oak Ridge National Laboratory
M. Gericke
University of Manitoba
C. Crawford, Y. Shin
University of Kentucky
DOE FnPB Review, ORNL, 2009-04-23 #2
Outline
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Executive summary
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Experimental team
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Scientific motivation
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Projected schedule
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Funding profile
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FnPB infrastructure needed
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Summary
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theory calculations
statistical sensitivity
systematics negligible
Experimental design
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experimental layout
solenoid design
spin flipper design
3He target / drift chamber
R&D at LANL
DOE FnPB Review, ORNL, 2009-04-23 #3
Executive summary
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n-3He experiment approved by the FnPB PRAC, 2008-01-07
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recent progress in experimental design
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experience on hadronic PV experiments at LANL
funding profile
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major components based on similar NPDGamma instrumentation
can reuse NPDGamma electronics / power supplies
capable experimental team
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full 4-body calculation of PV observable
R&D projects on target/detector design at LANL
new spin flipper design permitting compact / less expensive layout
preliminary holding field design
leverage existing hardware / technology
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first measurement of PV in the n-3He reaction
University of Manitoba
University of Kentucky
ORNL operation
$100k target / drift chamber
NSERC funded
$ 57k DAQ / electronics
DOE-OJI proposal
$120k solenoid, spin flipper, shielding, alignment, design
FnPB infrastructure
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no safety hazards, no LH2 target, new power or cooling requirements
minimal modification of FnPB cave – stand for n-3He solenoid
technician support for readiness review preparation, setup of experiment
Hadronic Weak Interaction (HWI)
DOE FnPB Review, ORNL, 2009-04-23 #4
Meson Exchange model (DDH)
N
N
STRONG
WEAK
(PC)
Meson (PV)
exchange
N
N
Effective Field Theory (EFT)
p-p and nuclei
n-3He
DOE FnPB Review, ORNL, 2009-04-23 #5
PV Asymmetry
PV observables:
~ kn very small for
low-energy neutrons
S(I):
- essentially the same asym.
- must discriminate between
back-to-back proton-triton
20.578
Tilley, Weller, Hale, Nucl. Phys. A541, 1 (1992)
19.815

4He J =0+ resonance

sensitive to EFT coupling
or DDH couplings
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~10% I=1 contribution
(Gerry Hale, qualitative)
Theoretical calculations – progress
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Vladimir Gudkov (USC)
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PC
Ay(90±) = -1.7±0.3£10-6
R matrix calculation of PC asymmetry,
nuclear structure, and resonance properties
Anna Hayes (LANL)
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A = 3£10-7
PV
PV reaction theory
Gerry Hale (LANL)
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DOE FnPB Review, ORNL, 2009-04-23 #6
No-core shell model calculation with AV18 potential, etc.
Michele Viviani et al. (INFN Pisa)
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PV
A = 3£10-7
full 4-body calculation of scattering wave function
calculation of asymmetry within DDH framework
progress on calculation of EFT low energy coefficients
preliminary – still improving convergence of 0+ wave functions
DOE FnPB Review, ORNL, 2009-04-23 #7
Experimental sensitivity to DDH couplings
Viviani et al.
preliminary
n+3Het+p
(ppm)
-0.1821
-0.1447
0.0267
0.0012
-0.1269
0.0495
Az
cont.
-0.830
2.373
-0.074
-0.016
-0.410
0.096
DOE FnPB Review, ORNL, 2009-04-23 #8
Experimental setup
FnPB cold
neutron guide
supermirror
bender polarizer
(transverse)
10 Gauss
solenoid
1010 steel
flux return
-metal
shield
3He
Beam
Monitor
transition field
(not shown)
3He
RF spin
rotator
FNPB
target /
ion chamber
n-3He
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longitudinal holding field – suppressed PC asymmetry
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RF spin flipper – negligible spin-dependent neutron velocity
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3He
ion chamber – both target and detector
DOE FnPB Review, ORNL, 2009-04-23 #9
Solenoid holding field
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uniformity requirements
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preliminary design
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solenoid with compensation coils
at end for uniformity
-metal shield for residual earth’s field
1010 steel flux return to prevent
saturation of -metal
design parameters
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B~ 0.3 G ¢B/2En=10-10 < Az
z ~ 0.1± + alignment of wires
3 m length x 50 cm diameter
B =10 G for spin flipper
j = 9 A/cm winding density
I0 = 1560 A (or end-cap windings)
simulation using COMSOL
10 Gauss
solenoid
1010 steel
flux return
3 m £ 50 cm diam.
I0=1500+60 A turns
j = 8+1 A/cm
4 m £ 55 cm diam.
I0
Radio frequency spin rotator
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extension of design for NPDGamma
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P-N Seo et al., Phys. Rev. ST Accel.
Beam, vol 11, 084701 (2008)
new resonator for n-3He experiment
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transverse horizontal RF B-field
longitudinal / transverse flipping
no fringe field - 100% efficiency
compact geometry - efficient
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small diameter solenoid
matched to driver electronics
for NPDGamma spin flipper
prototype design
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parasitic with similar design for
nEDM guide field near cryostat
fabrication and testing at UKy – 2009
NPDGamma
windings
n-3He
windings
DOE FnPB Review, ORNL, 2009-04-23 #10
Magnetostatic calculation with COMSOL
red - transverse field lines
blue - end-cap windings
3He

MC simulations of sensitivity to proton
asymmetry
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including wire correlations
 A ~ 6 /pN
tests at LANSCE FP12
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target / ion chamber
fission chamber flux calibration
prototype drift chamber R&D
new beam monitors for SNS
design of new ion chamber for
NPDGamma, test at LANL
DOE FnPB Review, ORNL, 2009-04-23 #11
LANSCE FP12 absolute neutron flux
DOE FnPB Review, ORNL, 2009-04-23 #12
LANSCE FP12
3He
chamber R&D
DOE FnPB Review, ORNL, 2009-04-23 #13
DOE FnPB Review, ORNL, 2009-04-23 #14
LANSCE FP12: test of NPDGamma monitors
Left: LANL FP12 beam line
with new beam monitor
Below: new beam monitor signal
at 100 mA proton beam current
and neutron beam cross-section.
Inverted Signal
Comparison of beam monitors
DOE FnPB Review, ORNL, 2009-04-23 #15
(same gain)
New monitors for SNS
RMS
RMS
Old monitors used
for NPDGamma at FP12
n-3He
DOE FnPB Review, ORNL, 2009-04-23 #16
collaboration
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J.D. Bowman (PI), S.I. Penttilä
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M.T. Gericke (PI), S.A. Page, Mark McCrea
University of Manitoba
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C.B. Crawford (PI), Y. Shin, E. Martin
University of Kentucky
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C. Gillis, J. Mei

J. Martin
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V. Gudkov
University of South Carolina
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M. Viviani
INFN, Sezione di Pisa
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A. Klein, A. Salas-Bacci, A. Hayes, G. Hale Los Alamos National Lab

R. Mahurin

P.-N. Seo
Triangle Universities Nuclear Lab

L. Barron
Universidad Nacional Autónoma de México
Oak Ridge National Laboratory
Indiana University
University of Winnipeg
University of Tennessee
DOE FnPB Review, ORNL, 2009-04-23 #17
Projected schedule
ORNL
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Jan 2010 – Jan 2011
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Offsite, LANL
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June 2009 – Aug 2010
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NPDGamma data-taking
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Aug 2010 – Dec 2010
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Construction of solenoid
Test of field uniformity,
alignment procedures
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Sept 2010 – Nov 2010
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Feb 2011 – Mar 2011
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Installation at FnPB
Commissioning
Apr 2011 – Sept 2011
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3He
data-taking
Construction of new RFSF
resonator at ORNL
Construction of 3He ion
chamber at Univ. Manitoba
DAQ electronics and software
production at Univ. Kentucky
test RFSF, 3He chamber, and
DAQ at LANL FP12
window of opportunity for
the n-3He experiment between
NPDGamma and Nab (2011)
DOE FnPB Review, ORNL, 2009-04-23 #18
Funding Profile
 University of Manitoba $100k
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target / drift chamber
$500k for FnPB-related activities in last 2 years
 University of Kentucky $ 57k
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DAQ / electronics
$40k university funding for R&D
 ORNL operations
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NSERC funded
$120k
solenoid, spin flipper
neutron, gamma shielding
design, stands, alignment
technician support
DOE-OJI proposal
Requirement of FnPB infrastructure
DOE FnPB Review, ORNL, 2009-04-23 #19
 modification of FnPB
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retained equipment:
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support stand for solenoid
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polarizer, beam monitor, spin flipper electronics
computer interface to chopper and TOF from SNS
DC holding field supply
beam collimation and shielding, beam stop
possible reuse of NPDGamma detector motion stand
power & cooling requirements
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same as NPDGamma
 manpower
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shielding calculations, preparation for readiness review
1 month technician support for setup of experiment
 safety hazards – none
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target – 1 atm inert gas; n+3Het+p (no  radiation)
radiation shielding: polarizer is still the major background
3He
Conclusion
DOE FnPB Review, ORNL, 2009-04-23 #20
 by doing NPDGamma, n-3He experiments along with
existing p-p, p-, n- (few body systems) we can
significantly improve statistical uncertainties in DDH
couplings and eliminate nuclear structure uncertainties
 EFT calculations are in progress for few-body systems
 n-3He is on-track to run after NPDGamma