The n3 He Experiment Christopher Crawford University of

The n-3 He Experiment Christopher Crawford University of Kentucky for the n-3 He Collaboration Fn. PB PRAC ORNL, TN 2015 -11 -10

Outline § Introduction • • Experimental setup Long. vs. trans. asym Timeline & beam time Statistics & sensitivity § Components • • Chopper – window tune RFSF – polarimetry Ion Chamber – scans DAQ – instrumental asym. § Simulations • • Status of simulations MC Validation § Physics analysis • • L/R wire pair asym. U/D singles asym. § Conclusion

Experimental setup Fn. PB cold neutron guide y x Super-mirror polarizer 3 He z Beam Monitor 10 Gauss Holding field FNPB RF spin rotator 3 Collimator He target / ion chamber n-3 He

Longitudinal vs. transverse PV asymmetry § Initial design: measure a longitudinal PV asymmetry • • • Insensitive to misalignment: L/R – U/D mixing Problem: chamber not self-normalizing Solution: flip spin half-way during TOF of pulse § Reconsideration: measure transverse PV asymmetry • Factor of 2 x better sensitivity to PV asymmetry: - • No dilution due to the opposite sign of asymmetry coming from upstream vs. downstream of sense wire Can decrease pressure so ions make it out of beam We decided to run both PC and PV in transverse mode

Timeline – Installation & Commissioning: 2014 § Spring – construction: Solenoid, RFSF, Ion Chamber, Preamp, DAQ § June – removed NPDG from Fn. PB § July – construction: barrier wall, mounting hardware tuned solenoid, tested major components § Aug – installation of solenoid / frame in Fn. PB § Sept – transverse fieldmap; ISSR tritium safety meeting § Nov – commissioning without beam; IRR 1 review filled Ion Chamber with 3 He, tested § Dec – beam profile scans; RFSF tune / polarimetry Accomplished installation and commissioning (except for IRR 2 and L/R asymmetry) on schedule during Fall 2014.

Timeline – Data collection: 2015 § Jan 21 – IRR 2 approval; tune RFSF / polarimetry; initial PV data § Feb 10–Feb 16 – PC data collection : 116 hr @ 900 k. W δA= 6. 8 x 10 -8 § Feb 16 – tuned chopper, began PV collection in final configuration § June 26–Aug 13 – summer shutdown 1920 MW hr RUN 1 § Sept 26–Oct 14 – SNS target failure 1040 MW hr RUN 2 § Oct 14– Dec 22 – production expect~1300 MW hr RUN 3 δA=1. 1 x 10 -8 JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC 4520 hr = 1. 6 x 107 s @ 1. 07 MW ave

Chopper efficiency Neutron Flux [arb. units] Optimization of Chopper, RFSF, DAQ window Unchopped single-pulse neutron spectrum Dropped pulse every 10 s Chopped spectrum TOF x 60 Hz Chopper efficiency Chopped 60 Hz beam Ion chamber TOF signal

Solenoid • Definition of σndirection – Adiabatic rotation from transverse to longitudinal spin – 10 m. G, 0. 1% uniformity Univ. Nacional Autónoma de México

Transverse RF Spin Rotator § Double-cosine-theta coil • • • Fringeless transverse RF field Longitudinal OR transverse Designed using scalar potential Univ. Tennessee / Univ. Kentucky

3 He transmission polarimetry Larmor Resonance Rabi Oscillation Beam Polarization of 3 He Cell Spin Flip Efficiency

Target / Ion Chamber • 3 He – – for both target and ionization gas Macor frames with 9 x 16 sense wires, 8 x 17 HV wires All aluminum chamber except for knife edges, 0. 9 mm Al windows 7 psi pure 3 He 16 m. Ci tritium over life of experiment University of Manitoba

Measured ion yield in target chamber

Garfield / gmsh / Elmer simulation of ion drift Ion collection across diagonal

Readout electronics • Ionization read out in current mode – 144 channels read out simultaneously – Low-noise I-V preamplifiers mounted on chamber – 24 -bit, 100 k. S/s, 48 channel Δ-Σ ADC FMC modules Oak Ridge National Lab, Univ. Kentucky, Univ. Tennessee Electronic Tests: Instrumental false asymmetry measurements

False electronic asymmetries

MC Simulations § Three independent simulations: 1. GEANT 4 with white source – Manitoba 2. C-code with Mc. Stas ntuple source – UKy 3. C-code with Fn. PB measured source – UTK • Ionization weighted averages: ionization yield covariance geometry factor • Used to calculate detector efficiency (effective statistics / neutron flux)

Test of MC simulation – ionization deposit § Three independent simulations: 1. GEANT 4 with white source 2. C-code with Mc. Stas ntuple source 3. C-code with Fn. PB measured source • Event - weighted averages: ionization correlation geometry • Used to calculate detector efficiency – work (effective. PRELIMINARY statistics / neutron flux) in progress

Test of MC simulation – correlations Difference of correlation: MC - experiment PRELIMINARY – work in progress

PC Asymmetry analysis § Single-wire asymmetry, 30 hr. data subset

PC Asymmetry analysis § Single wire asymmetries – offset due to beam asymmetry

PC Asymmetry analysis § Wire pair asymmetry – does not include correlations

Covariant – weighted analysis • Histogrammed extracted physics PC asymmetry from each good run (746 total = 86 hr) PRELIMINARY – work in progress • used full covariant weighting of each wire pair to extract the PC asymmetry G. Hale, R-matrix theory (PV Workshop, Madison, WI 2008)

PV asymmetry – wire 2

Conclusion § Sensitivity of data collected by December • Expect 1. 1 x 10 -8 statistical uncertainty in PV asymmetry § Preliminary analysis of PC asymmetry • • 7 x 10 -8 statistical uncertainty in 5 days of data taking Data appear statistically consistent § Analysis of PV asymmetry underway • Investigating some inconsistencies § Preliminary MC validation • Still needs work

n 3 He Collaboration Duke University, TUNL • Pil-Neo Seo INFN, Sezione di Pisa • Michele Viviani University of Kentucky • Chris Crawford • Latiful Kabir • Aaron Sprow Western Kentucky University • Ivan Novikov Los Alamos National Laboratory • Gerry Hale University of Manitoba • Michael Gericke • Mark Mc. Crea • Carlos Olguin University of New Hampshire • John Calarco Universidad Nacional Autónoma de México • Libertad Barrón • José Favel • Andrés Ramírez Oak Ridge National Laboratory • David Bowman • Vince Cianciolo • Paul Mueller • Seppo Penttilä • Jack Thomison University • Rob Mahurin University of Tennessee • Noah Birge • Chris Coppola • Nadia Fomin • Irakli Garishvili • Connor Gautham • Geoff Greene • Chris Hayes • Serpil Kucuker • Eric Plemons • Mae Scott University of Tennessee at Chattanooga • Josh Hamblen University of South Carolina • Jeremy Watts • Vladimir Gudkov • Caleb Wickersham • Matthias Schindler University of Virginia • Young-Ho Song • Stefan Baessler Middle Tennessee State