1. Hadronic Parity Violation at the SNS Christopher Crawford University of Kentucky 2011-01-31 symmetries and interactions properties of the neutron NPDGamma & n- 3 He exp. designing coils with ϕ m MadisonSpencer

2. Weak Interaction Strong Interaction Hadronic Interaction (residual nuclear force) Standard Model of Particles E&M Interaction SPACE TIME

3. Degenerate Fermi Gas Particle Decay Higgs? Annihilation Standard Model of Automobiles

4. Symmetries Continuous Symmetries –space-time translation –rotational invariance –Lorentz boosts –gauge invariance Noether’s Theorem continuous symmetries correspond to conserved quantities –energy-momentum –angular momentum –center-of-momentum –electric charge Discrete Symmetries –parity P : x  -x –time T : t  -t –charge C : q  -q –particle P 12 : x 1  x 2 exchange Discrete Theorems –CPT theorem –spin-statistics theorem position symmetry conserved momentum

5. CPT theorem : ALL laws are invariant under CPT Car Symmetries LR R CP (charge, parity) 100 km/h 100 km/h 99.7 km/h T (time) I’m coming home … Be careful, some idiot’s going the wrong way on the freeway. Only one? They’re all over the place!

6. Parity-violation in weak interaction October 1, 1956 issue of the Physical Review Parity-transformation (P) :

7. Madame C.S. Wu

8. Hadronic Weak Interaction Desplanques, Donahue, & Holstein (DDH) formalism: –6 meson-nucleon coupling constants: range + isospin structure –pion channel dominated by neutral current (Z 0 ) –PV effects: interference between strong and weak vertex other treatments: –partial waves, chiral perturbation theory, lattice QCD N N N N Meson exchange STRONG (PC) WEAK (PV)

9. Why Study Hadronic PV? probe of atomic, nuclear, and hadronic systems –map out coupling constants –resolve 18 F, 133 Cs discrepancy –probe nuclear structure effects –anapole and qq contributions to PV electron scattering probe of QCD in low energy non-perturbative regime –confinement, many-body problem –sensitive to qq correlations –measure QCD modification of qqZ coupling n + p  d +  A  = -0.11 f   + -0.001 h ρ 1 + -0.003 h  1 n-captureelastic scatteringspin rotation np A  nD A  n 3 He A p np  n n  pp A z p  A z f  -0.11 0.92-0.19-3.12-0.97-0.34 hρ0hρ0 -0.50-0.036-0. 23-0.32 0.080.14 hρ1hρ1 -0.001 0.10 0.019 0.11 0.080.05 h2h2 0.0006-0.25 0.03 h0h0 -0.16-0.033-0. 23-0.22-0.070.06 h1h1 -0.003-0.002 0.041 0.22 0.070.06

10. p-p and nuclei Existing Measurements Anapole Nuclear anapole moment (from laser spectroscopy) Polarized proton scattering asymmetries Light nuclei gamma transitions (circular polarized gammas)

11. Properties of the Neutron m n = m p + m e + 782 keV  n = 885.7 ± 0.8 s q n < 2 x 10 -21 e d n < 3 x 10 -26 e cm  n = -1.91  N r m = 0.889 fm r e 2 = -0.116 fm 2 –3 valence quarks + sea –exponential magnetization distribution –pion cloud: spin 1/2 isospin 1/2 p p n n uududdupdown data from BLAST

12. Neutron sources - Reactors ILL, Grenoble, France

13. Spallation Neutron Source (SNS) spallation sources: LANL, SNS –pulsed -> TOF -> energy LH2 moderator: cold neutrons –thermal equilibrium in ~30 interactions Oak Ridge National Laboratory, Tennessee

14. Spallation Neutron Source (SNS) spallation sources: LANL, SNS –pulsed -> TOF -> energy LH2 moderator: cold neutrons –thermal equilibrium in ~30 interactions

15. Guides - neutron optical potential slide courtesy A. Young

16. 1B - Disordered Mat’ls Commission 2010 2 - Backscattering Spectrometer Commission 2006 3 - High Pressure Diffractometer Commission 2008 4A - Magnetism Reflectometer Commission 2006 4B - Liquids Reflectometer Commission 2006 5 - Cold Neutron Chopper Spectrometer Commission 2007 18 - Wide Angle Chopper Spectrometer Commission 2007 17 - High Resolution Chopper Spectrometer Commission 2008 13 - Fundamental Physics Beamline Commission 2007 11A - Powder Diffractometer Commission 2007 12 - Single Crystal Diffractometer Commission 2009 7 - Engineering Diffractometer IDT CFI Funded Commission 2008 6 - SANS Commission 2007 14B - Hybrid Spectrometer Commission 2011 15 – Spin Echo 9 – VISION Flight Paths at the SNS

17. What can we do with neutrons? scattering / diffraction –complementary to X-ray Bragg diffraction –large penetration –large H,D cross section life sciences fuel cell research oil exploration fundamental tests of quantum mechanics –neutron interferometry scattering lengths neutron charge radius spinor 4  periodicity gravitational phase shift –quantum states in a gravitational potential

18. p (or d) d (or t) n γ What can we do with neutrons? fundamental symmetry tests of the standard model –neutron decay lifetime and correlations –PV: NPDGamma, 4 He spin rotation –T reversal: electric dipole moment Electron Proton Neutrino Neutron Spin A B C nEDM

19. Neutron Traps ultra cold neutrons: slow enough to be completely reflected by 58 Ni optical potential kinetic: 8 m/s thermal: 4 mK wavelength: 50 nm nuclear: 335 neV ( 58 Ni) magnetic: 60 neV (1 T) gravity: 102 neV (1 m) 3m g

20. Car Traps

21. R. Alarcon, L. Barron, S. Balascuta Arizona State University S.J. Freedman, B. Lauss Univ. of California at Berkeley S. Santra Bhabbha Atomic Research Center Todd Smith Univ. of Dayton G.L. Jones Hamilton College W. Chen, R.C. Gillis, J. Mei, H. Nann, W.M. Snow, M. Leuschner, B. Losowki Indiana University R.D. Carlini Thomas Jefferson National Accel.Facility E. Sharapov Joint Institute of Nuclear Research T. Ino, Y. Masuda, S. Muto High Energy Accel. Research Org. (KEK) C. B. Crawford, E. Martin Univ. of Kentucky J.D. Bowman (spokesman), N. Fomin, G.S. Mitchell, S. Penttila, A. Salas-Bacci, W.S. Wilburn, V. Yuan Los Alamos National Laboratory M.T. Gericke, S. Page, D. Ramsay Univ. of Manitoba L. Barron University National Autonomica de Mexico T.E. Chupp, M. Sharma Univ. of Michigan T.R. Gentile National Institute of Standards and Tech. S. Covrig, M. Dabaghyan, F.W. Hersman Univ. of New Hampshire P.N. Seo North Carolina State University G.L. Greene, R. Mahurin, M. Musgraves Univ. of Tennessee S. Baessler, D. Pocanic Univ. of Virginia NPDGamma Collaboration

22. PV Gamma Asymmetry

23. 3 He Polarizer Overview of NPDGamma Setup Gamma Detectors LH 2 Target RF Spin Rotator Beam Monitors

24. 3 He neutron polarizer n + 3 He  3 H + p cross section is highly spin-dependent  J=0 = 5333 b / 0  J=1 ¼ 0 10 G holding field determines the polarization angle rG < 1 mG/cm to avoid Stern-Gerlach steering Steps to polarize neutrons: 1.Optically pump Rb vapor with circular polarized laser 2.Polarize 3 He atoms via spin-exchange collisions 3.Polarize 3 He nuclei via the hyperfine interaction 4.Polarize neutrons by spin- dependent transmission n n + n n p p p p n n p p n n + p p P 3 = 57 %

25. Neutron Beam Monitors 3 He ion chambers measure transmission through 3 He polarizer

26. RF Spin Rotator –essential to reduce instrumental systematics spin sequence:   cancels drift to 2 nd order danger: must isolate fields from detector false asymmetries: additive & multiplicave –works by the same principle as NMR RF field resonant with Larmor frequency rotates spin time dependent amplitude tuned to all energies compact, no static field gradients holding field snsn B RF NPDGamma windings n- 3 He windings

27. 16L liquid para-hydrogen target 15 meV ortho para capture E n (meV)  (b) 30 cm long  1 interaction length 99.97% para  1% depolarization super-cooled to reduce bubbles SAFETY !! p p p p para-H 2 p p p p ortho-H 2  E = 15 meV

28. CsI(Tl) Detector Array 4 rings of 12 detectors each –15 x 15 x 15 cm 3 each VPD’s insensitive to B field detection efficiency: 95% current-mode operation –5 x 10 7 gammas/pulse –counting statistics limited

29. activation of materials, e.g. cryostat windows Stern-Gerlach steering in magnetic field gradients L-R asymmetries leaking into U-D angular distribution (np elastic, Mott-Schwinger...) scattering of circularly polarized gammas from magnetized iron (cave walls, floor...)  estimated and expected to be negligible (expt. design) Systematics, e.g: AA stat. err. systematics (proposal) Statistical and Systematic Errors Systematic Uncertainties slide courtesy Mike Snow

30. LANSCE Results

31. 2 nd phase at the SNS: SM polarizer Fe/Si on boron float glass, no Gd m = 3.0 critical angle n = 45 channels r = 9.6 m radius of curvature l = 40 cm length d = 0.3mm vane thickness T=25.8%transmission P=96.2%polarization N=2.2 £ 10 10 n/soutput flux (chopped) simulations using McStas / ROOT ntuple NPDG at the FnPB: 50x higher luminosity 4x higher FOM of polarization 6x longer run time Goal:  A = 1 x 10 -8

32. n- 3 He PV Asymmetry S(I):  4 He J  =0 + resonance  sensitive to EFT coupling or DDH couplings  ~10%  I=1 contribution (Gerry Hale, qualitative)  A ~ -1–3x10 -7 (M. Viviani, PISA) ~ k n very small for low-energy neutrons - must discriminate between back-to-back proton-triton PV observables: 19.815 20.578 Tilley, Weller, Hale, Nucl. Phys. A541, 1 (1992) n n + n n p p p p n n p p n n + p p n n p p n n p p

33. 10 Gauss solenoid RF spin rotator 3 He target / ion chamber supermirror bender polarizer (transverse) FnPB cold neutron guide 3 He Beam Monitor transition field (not shown) FNPBn- 3 He Experimental setup longitudinal holding field – suppressed PC asymmetry RF spin flipper – negligible spin-dependent neutron velocity 3 He ion chamber – both target and detector

34. Projected Sensitivity Statistical SensitivitySystematic Sensitivity

35. Magnetic Scalar Potential

36. Examples capacitorsolenoid

37. Boundary Conditions

38. Designing fields from the inside out Standard iterative method: Create coils and simulate field. New technique: start with boundary conditions of the desired B-field, and simulate the winding configuration 1.Use scalar magnetic potential (currents only on boundaries) 2.Simulate intermediate region using FEA with Neumann boundary conditions (H n ) 3.Windings are traced along evenly spaced equipotential lines along the boundary red - transverse field lines blue - end-cap windings Magnetostatic calculation with COMSOL

39. Prototype RFSF Developed for static nEDM guide field 1% uniformity DC field

40. Conclusion The hadronic parity violation is a unique probe of short distance nuclear interactions and QCD structure Cold neutrons valuable for tests of symmetry in particle interactions –neutron capture is an important key to mapping the structure of the hadronic weak interaction We expect results of NPDGamma from the SNS in 2012 New techniques have been developed for designing magnetic fields – our “handle” on neutrons