Status update of n- 3 He experiment DOE FnPB Review, ORNL 2009-04-23

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

Executive summary

Scientific motivation• theory calculations • statistical sensitivity• systematics negligible

Experimental design• experimental layout• solenoid design• spin flipper design• 3He target / drift chamber

R&D at LANL

Experimental team

Projected schedule

Funding profile

FnPB infrastructure needed

Summary


Executive summary

n-3He experiment approved by the FnPB PRAC, 2008-01-07• first measurement of PV in the n-3He reaction

recent progress in experimental design• 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• major components based on similar NPDGamma instrumentation• can reuse NPDGamma electronics / power supplies

capable experimental team• experience on hadronic PV experiments at LANL

funding profile• University of Manitoba $100k target / drift chamber NSERC funded• University of Kentucky $ 57k DAQ / electronics DOE-OJI proposal• ORNL operation $120k solenoid, spin flipper, shielding, alignment, design

FnPB infrastructure• 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)

N N

N N

Meson exchang

e

STRONG(PC)

WEAK(PV)

p-p and nuclei

Meson Exchange model (DDH)

Effective Field Theory (EFT)


n-3He PV Asymmetry

~ kn very small for low-energy neutrons

- essentially the same asym.- must discriminate between back-to-back proton-triton

S(I):

4He J =0+ resonance

sensitive to EFT couplingor DDH couplings

~10% I=1 contribution(Gerry Hale, qualitative)

PV observables:

19.81520.578

Tilley, Weller, Hale, Nucl. Phys. A541, 1 (1992)


Theoretical calculations – progress

Vladimir Gudkov (USC) PV A = 3£10-7

• PV reaction theory

Gerry Hale (LANL) PC Ay(90±) = -1.7±0.3£10-6

• R matrix calculation of PC asymmetry,nuclear structure , and resonance properties

Anna Hayes (LANL)• No-core shell model calculation with AV18 potential, etc.

Michele Viviani et al. (INFN Pisa) 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


Experimental sensitivity to DDH couplings

n+3Het+p (ppm)

Viviani et al.preliminary

-0.1821 -0.830-0.1447 2.373 0.0267 -0.074 0.0012 -0.016-0.1269 -0.410 0.0495 0.096

Az cont.


-metal shield

1010 steelflux return

10 Gausssolenoid

RF spinrotator

3He target /ion chamber

supermirrorbender polarizer

(transverse)

FnPB coldneutron guide

3He BeamMonitor transition field

(not shown)

FNPB n-3He

Experimental setup

longitudinal holding field – suppressed PC asymmetry

RF spin flipper – negligible spin-dependent neutron velocity

3He ion chamber – both target and detector


Solenoid holding field

uniformity requirements• B~ 0.3 G ¢B/2En=10-10 < Az

• z ~ 0.1± + alignment of wires

preliminary design• 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• 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

1010 steelflux return

10 Gausssolenoid

4 m £ 55 cm diam.3 m £ 50 cm diam.

I0=1500+60 A turns I0

j = 8+1 A/cm


red - transverse field linesblue - end-cap windings

Radio frequency spin rotator

extension of design for NPDGamma• P-N Seo et al., Phys. Rev. ST Accel.

Beam, vol 11, 084701 (2008)

new resonator for n-3He experiment• transverse horizontal RF B-field• longitudinal / transverse flipping• no fringe field - 100% efficiency• compact geometry - efficient

- small diameter solenoid• matched to driver electronics

for NPDGamma spin flipper

prototype design• parasitic with similar design for

nEDM guide field near cryostat• fabrication and testing at UKy – 2009

NPDGammawindings

n-3Hewindings

Magnetostatic calculation with COMSOL


3He target / ion chamber

MC simulations of sensitivity to proton asymmetry• including wire correlations• A ~ 6 /pN

tests at LANSCE FP12• fission chamber flux calibration• prototype drift chamber R&D• new beam monitors for SNS

design of new ion chamber for NPDGamma, test at LANL


LANSCE FP12 absolute neutron flux


LANSCE FP12 3He chamber R&D


Left: LANL FP12 beam line with new beam monitor

Below: new beam monitor signal at 100 mA proton beam currentand neutron beam cross-section.

Inverted Signal

LANSCE FP12: test of NPDGamma monitors


Comparison of beam monitors

New monitors for SNS

Old monitors usedfor NPDGamma at FP12

(same gain)

RMS

RMS


n-3He collaboration

J.D. Bowman (PI), S.I. Penttilä Oak Ridge National Laboratory

M.T. Gericke (PI), S.A. Page, Mark McCrea University of Manitoba

C.B. Crawford (PI), Y. Shin, E. Martin University of Kentucky

C. Gillis, J. Mei Indiana University

J. Martin University of Winnipeg

V. Gudkov University of South Carolina

M. Viviani INFN, Sezione di Pisa

A. Klein, A. Salas-Bacci, A. Hayes, G. Hale Los Alamos National Lab

R. Mahurin University of Tennessee

P.-N. Seo Triangle Universities Nuclear Lab

L. Barron Universidad Nacional Autónoma de México


Projected schedule

Jan 2010 – Jan 2011• NPDGamma data-taking

Aug 2010 – Dec 2010• Construction of solenoid• Test of field uniformity,

alignment procedures

Feb 2011 – Mar 2011• Installation at FnPB• Commissioning

Apr 2011 – Sept 2011• 3He data-taking

June 2009 – Aug 2010• Construction of new RFSF

resonator at ORNL• Construction of 3He ion

chamber at Univ. Manitoba• DAQ electronics and software

production at Univ. Kentucky

Sept 2010 – Nov 2010• test RFSF, 3He chamber, and

DAQ at LANL FP12

window of opportunity forthe n-3He experiment between NPDGamma and Nab (2011)

ORNL Offsite, LANL


Funding Profile

University of Manitoba $100k NSERC funded• target / drift chamber• $500k for FnPB-related activities in last 2 years

University of Kentucky $ 57k DOE-OJI proposal• DAQ / electronics• $40k university funding for R&D

ORNL operations $120k • solenoid, spin flipper• neutron, gamma shielding• design, stands, alignment• technician support


Requirement of FnPB infrastructure

modification of FnPB• retained equipment:

- polarizer, beam monitor, spin flipper electronics- computer interface to chopper and TOF from SNS- DC holding field supply- beam collimation and shielding, beam stop

• support stand for solenoid- possible reuse of NPDGamma detector motion stand

• power & cooling requirements- same as NPDGamma

manpower• shielding calculations, preparation for readiness review• 1 month technician support for setup of experiment

safety hazards – none• 3He target – 1 atm inert gas; n+3Het+p (no radiation)• radiation shielding: polarizer is still the major background


Conclusion

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

Documents

Status update of n- 3 He experiment DOE FnPB Review, ORNL 2009-04-23