Tests of Fundamental Symmetries with Neutrons

1. Tests of Fundamental Symmetries with Neutrons • The Science • Violation of Parity Symmetry in NN Force • Search for new Symmetries in n b-decay • (eg. SUperSYmmetry aka SUSY) • New Sources of CP Violation (n EDM) • Neutron Technology • Facilities & Experiments • (focus on US effort – relatively new ) • Outlook B. Filippone PANIC 05 10/25/05

2. Related PANIC05 Talks Section XII.2: New Accelerator Facilities II Parallel Session 2, Monday, October 24, 4:30 - 6:00PM, room: Hilton - Ortiz Section VII.1: EDM of electrons, muons, neutrons, atoms Parallel Session 3, Tuesday, October 25, 2:30 - 4:00PM, room: Sweeney - Meeting 3 Section VII.2: Fundamental Measurements in Atomic and Molecular Physics Parallel Session 4, Thursday, October 27, 2:30 - 4:00PM, room: Sweeney - Meeting 3 Section VII.3: Neutron lifetime and beta decay Parallel Session 5, Thursday, October 27, 4:30 - 6:00PM, room: Sweeney - Meeting 3 Maurits van der Grinten Search for the Electric Dipole Moment of the Neutron

3. Overview of the Science • Hadronic Weak Interaction • Should be interpretable via QCD • May play role in nucleon structure and neutrinoless bb-decay • Decay Correlations and Neutron Lifetime • Decay parameters sensitive to non-SM phys. • tn important for Big-Bang Nucleosynthesis • Neutron EDM • New sources of CP violation (complements LHC) • May contribute to Baryon-Antibaryon asymmetry of Universe

4. N-N Weak Interaction • Purely hadronic weak interaction influenced by QCD • Plays role in Atomic and Nuclear Parity Violation • Desplanques, Donahue and Holstein estimated NN weak interaction via a quark model • 6 parameters in meson exchange model fp , hr0, hr1, hr2, h0, h1

5. Status of N-N Weak Interaction experiments Experimental constraints on combinations of the couplings are not consistent (x 10-7) DDH (x 10-7) From Haxton & Wieman 01

6. Sensitivity to NN Weak Meson Couplings in few-nucleon observables Table from J. D. Bowman • Role of Neutrons • n + p gd + g (NPDg ) spin asymmetry can isolate fp • n + a Spin rotation provides unique constraints • also n + p spin rotation and n + d gt + g

7. Neutron Decay and Unitarity Mass eigenstates Weak eigenstates æ ö æ ö æ ö d V V V d ç ÷ ç ÷ ç ÷ w ud us ub = s V V V s ç ÷ ç ÷ ç ÷ w cd cs cb ç ÷ ç ÷ ç ÷ b V V V b è ø è ø è ø w td ts tb æ ö æ ö æ ö d 0 . 975 0 . 22 0 . 005 d ç ÷ ç ÷ ç ÷ w = s 0 . 22 0 . 97 0 . 04 s ç ÷ ç ÷ ç ÷ w ç ÷ ç ÷ ç ÷ b 0 . 005 0 . 04 0 . 99 b è ø è ø è ø w Unitarity, , (or lack thereof) of CKM matrix tests existence of possible new physics (eg. Supersymmetry) eg. |Vud|2 + |Vus|2 + |Vub|2 = 1

8. ne ne GF GFVud m- nm u d e- e- W- W- Vud from b-decay • GV is related to Fermi coupling GF via Vud • GV measured in b-decay (ugd) • 0+-0+ nuclear decay (must include nuclear corrections) • neutron decay (must extract GV and GA)

9. Polarized Neutron decay m e σ . p σ σ . . n e n n A E r e Summing over final-state polarization r r r r r r r r ö æ . p p p p x p ç d + G = G + + + e ν ν b e n 1 a B + D ÷ ç n E E E E E ø è e e ν ν e • Gn =1/tntotal decay rate (depends on GA and GV) • Correlations a, A and B depend on GA and GV • Coefficient b requires S and T interaction • Correlation D violates Time Reversal Invariance Must measure two observables to extract GA and GV (eg. tn and A)

10. Neutron Lifetime versus Year Data points used by Particle Data Group (PDG) 2004 for averaging Serebrov et al., Phys. Lett. B 605, 72 (2005) (878.5 ± 0.7 ± 0.3) seconds

11. CKM Summary: PDG04 UCNA UCNA

12. CKM Summary: PDG06? UCNA

13. CKM Summary: Other? New tn !! UCNA

14. Neutron EDM beyond the Standard Model • New physics (e.g. SUSY) should have additional CP violating phases in couplings • sinqCP should be ~ 1 • Contributions to EDMs depends on masses of new particles • In MSSM (Minimal Supersymmetric Standard Model) • dn ~ 10-25 e-cm x (200 GeV)/M2SUSY experiment: dn < 6 x 10-26 e-cm

15. n-EDM vs Time

16. Neutron Technology • Cold neutrons ~ 4 • Produced from Cold Moderator (20K) • Ultra-Cold Neutrons (UCN) ~ 500 • Boltzmann tail from Reactor cold moderator • Superthermal Converters • LHe, SD2 • Cold Neutron Advantages • High Flux • Improved polarization with pulsed source • UCN Advantages • Can be trapped in certain materials • Can be easily polarized (B = 6T)

17. Worldwide Neutron source comparison Adapted from NSAC Subcommittee Report on Fundamental Physics with Neutrons (03)

18. US Facilities for Fundamental Physics with Neutrons • NIST • NG6 - Cold Neutron Lines • LANSCE • Flight Path 12 (FP12) - Pulsed Cold Neutrons • Area B - UCN • SNS • Fundamental Neutron Physics Beamline (FNPB) • Other Initiatives • PULSTAR Reactor @ NCSU • LENS Cold neutrons @ IUCF

19. Non-US Facilities for Fundamental Neutron Physics • ILL – Cold & Ultra-Cold lines • Improved EDM experiment (Cryo-EDM) • Improved correlation experiments • PSI – Spallation SD2 UCN source • EDM experiment under development • Correlation experiments possible • Germany - FRM-II 20MW research reactor • Work underway for SD2 UCN source • Japan • Osaka UCN, JPARC?

20. The Fundamental Neutron Physics Program at NIST • 20 MW research reactor with a LH2 cold source • Operates ~210 days/year • 5 Fundamental neutron physics facilities

21. Upcoming Experiments at NIST • Neutron lifetime using magnetically trapped UCN (Underway - 0.9 nm Monochromatic neutron line) • Neutron spin rotation in liquid helium (05-06) • Electron-neutrino asymmetry - “a” • Proton asymmetry - “A” + “B”

22. UCN Source LANSCE (Los Alamos Neutron Science CEnter) Proton Linac FP12

23. FP12 at LANSCE LH2 moderator 2 x 109 polarized cold n/sec Available for nuclear physics experiments and staging SNS experiments after 2007

24. NPD experiment - measure f •  f = 5  10-7 • 2005-6 at LANSCE • f = 5  10-8 • 2007-8 at SNS From S. Penttila

25. Liquid N2 Be reflector LHe Solid D2 77 K poly Tungsten Target LANSCE Area B Experiment commissioning Underway Initial goal is 0.2% measurement of A-correlation UCNA

26. NCSU PULSTAR UCN Source • 1MW research reactor • Possible UCN source could provide densities > 1,000/cm3 Construction underway From P. Huffman

27. Low Energy Neutron Source(LENS) at Indiana Univ. <10 K CH4 moderator 13 MeV Proton beam Poly/Pb Shielding From M. Snow Be target and H2O reflector Ideal for development of new moderators and neutron scattering instruments

28. SNS at ORNL 1.4 MW Spallation Source

29. SNS Target Hall p beam FNPB construction underway Cold beam available ~2007 UCN line via LHe ~2009 FNPB-Fundamental Neutron Physics Beamline

30. FNPB Beamline Double monochrometer Selects 8.9 neutrons for UCN via LHe

31. SNS EDM Experiment Based on Golub & Lamoreaux (94) concept: • Produce UCN in superfluid 4He • Use higher |E| field in 4He • Use polarized 3He as comagnetometer • Measure precession frequency via n-capture on 3He • Can also “dress” the 3He and neutron spin • Extra RF field gives

32. New Technique for n-EDM? E-field • Inject polarized neutron • & 3He 2. Rotate both spins by 90o 3. Measure n+3He capture vs. time (note: sih>>shh) 4. Flip E-field direction B-field

33. EDM Sensitivity

34. n EDM Experiment at SNS He Liquifier Isolated floor

35. Status of SNS neutron EDM • Feasibility of <1x10-28 e-cm demonstrated (2003-2005 R&D) • Internal Review 2/05 • Construction Possible: FY07-FY10 • Cost: 15-18 M$ • Collaboration prepared to begin construction in FY07

36. n-EDM Sensitivity vs Time 2000 2010 EDM @ SNS dn<1x10-28 e-cm

37. Worldwide n-EDM Sensitivity Proposal funded Phase 1 underway SNS Proposal under review Adapted from NSAC Subcommittee Report on Fundamental Physics with Neutrons (03)

38. Outlook • Program to Test Fundamental Symmetries with neutrons is developing in the US • There exists an active program worldwide • Compelling science is anticipated within the next 5-10 years • NN weak current • n b-decay (correlations & lifetime) • n EDM

39. The End

40. Supplemental Slides

41. US Fundamental Neutron Physics Facilities

42. New US Neutron Experiments

43. Possible US Neutron Experiments

44. Systematic Controls in new EDM experiment • Highly uniform E and B fields • Cosq coil in Ferromagnetic shield • Kerr effect measurement of E-field • Two cells with opposite E-field • Ability to vary influence of B0 field • via dressed spins • Control of central temperature • Can vary 3He diffusion

45. m- d ~ u ne ne ~ nm c0 c0 ~ ~ ~ ~ m u n d e- e- W- W- Sensitivity to Supersymmetry? Kurylov&Ramsey-Musolf (02) • Supersymmetric particles produce loop corrections

46. Extraction of Vud via neutrons

47. C P T m - + - d - + - E - - + B - + - J + + - Quantum Picture – Discrete Symmetries Non-Relativistic Hamiltonian 123 123 C-even P-even T-even C-even P-odd T-odd

48. Experimental EDM’s Adapted from Erler & Ramsey-Musolf (hep-ph/0404291) Tl PbO GGG < 1 x n ILL-new 2 x 10-28

49. EDM

50. Possible impacts of non-zero EDMs e- n 199Hg • Sharply constrains models beyond the Standard Model (especially with LHC data) • May account for matter- antimatter asymmetry of the universe (EW Baryogenesis) Note: From Erler & Ramsey-Musolf (hep-ph/0404291)