1. Ultra-cold Neutron Fundamental Physics at LANSCE Alexander Saunders Los Alamos National Laboratory Neutron Lifetime Beta Decay Correlations Beta Decay Theory

2. Outline Introduction: why neutron beta decay allows search for physics beyond the Standard Model Ultra-cold neutrons UCNA experiment: progress and goals UCN Lifetime experiment prospects A UCN user facility at LANSCE The UCN effort world wide

3. Probing Physics Beyond the Standard Model Through Neutron Beta Decay Neutron beta decay as a probe for physics beyond the standard model –Quark mixing –Unitarity sum rule violated? d s d u d u d u np V ud V us K  Neutron decay Kaon decay |V ud | 2 + |V us | 2 + |V ub | 2 = 1 0

4. Probing Physics Beyond the Standard Model Through Neutron Beta Decay Neutron beta decay as a probe for physics beyond the standard model –Quark mixing in standard model –Unitarity sum rule violated? d s d u d u d u np V ud V us K  Neutron decay Kaon decay Next level of reality? |V ud | 2 + |V us | 2 + |V ub | 2 ≠ 1 0 ?

5. Neutron Decay and Unitarity Unitarity,, (or lack thereof) of CKM matrix tests existence of further quark generations and possible new physics (eg. Supersymmetry) eg. |V ud | 2 + |V us | 2 + |V ub | 2 = 1 B. W. Filippone

6. CKM Summary: New V us &  n ? New  n !! UCNA M. Ramsey-Musolf

7. Neutron  -Decay gives G A and G V Measuring A and neutron lifetime G F from muon decay CKM unitarity gives V ud a = electron neutrino correlation A = beta asymmetry B = neutrino asymmetry D = triple correlation (T-violating) b = Fierz interference term Jackson et al

8. Contribution to the V ud uncertainty Contribution  V ud (10 -4 ) RR 1.1 CC 1.5 RR 1.9 total2.7 0+ 0+0+ 0+ Contribution  V ud (10 -4 )  n (  n = 0.8 s) 4 (  A/A = 0.6%) 12 RR 2 total13 neutron Marciano and Sirlin, PRL 96, 032002 (2006)

9. Principle of the A-coefficient Measurement B field Detector 1Detector 2 Polarized neutronDecay electron (End point energy = 782 keV) n e  dW=[1+  PAcos  ]d  (E)

10. What is an Ultracold Neutron (UCN)? UCN can be stored in material bottles for 100s of seconds and piped around corners Typical velocities (0-8 m/s), V (En 0- 350 neV) Wavelengths > 50 nm 100% Polarizable with magnetic fields – m n B=60 neV/T mgh = 102 neV, h=1 meter Lifetime < 1000 seconds ~ Bottle Lifetime kT<4mK

11. UCN can also be essentially 100 percent polarized  100% polarization, provided v UCN is low enough UCNs provide a remarkable tool for studying neutron beta decay: 100% polarization and no source-related backgrounds

12. UCN sources, Solid, LHe, Doppler E CN E UCN phonon n nnn n n Classic Doppler Source New “Superthermal” UCN sources utilize phonon scattering. Both liquid and solid media are being used. 1-2 ucn/cc What makes a good superthermal UCN source? Low neutron absorption High single phonon energy Light atoms Weak crystal

13. Prototype LANSCE UCN Source Liquid N 2 Be reflector Solid D 2 77 K poly Tungsten Target 58 Ni coated stainless guide UCN Detector Flapper valve LHe SS UCN Bottle Beam detector UCN guide Cryostat UCN bottle

14. LANSCE Area-B UCN Source 800 MeV proton beam hits a tungsten target. Spallation neutrons interact with various parts of the source. >2 MeV neutrons undergo n-2n reactions in Be. Neutron thermalize in Graphite, Be, poly and solid deuterium. Cold neutrons scatter in the solid deuterium to ultracold state. UCN valve to increase source lifetime Warm poly added in 2007, yellow

15. UCNA Experiment — Apparatus Neutron Absorber Field Expansion Region

16. UCNA Experiment — General Approach Neutron Polarization –UCN (can produce >99% polarization with 7T magnetic field) –Diamond-like carbon coated neutron guide (low depolarization) Background –Pulsed UCN source –MWPC+Plastic scintillator Electron backscattering –MWPC+Plastic scintillator Fiducial volume selection –MWPC Detector Characterization –Off-line calibration system –Larger light collection Novel features: UCN from pulsed spallation source MWPC + plastic scintillator as  detector Goal: 0.2% measurement of A (  A/A = 0.2%)

17. UCNA Apparatus in LANSCE Area B

18. UCNA Results of 2007 Cycle ~50 hours of DAQ 0.8 M decays Signal/BG = 20 4% uncertainty Published 1/2009

19. 2007 Systematic Uncertainties

20. Example: Backscattering

21. 2008 Data run: 12-32 M decays One of three data periods

22. A Correlation history UCNA 2007 PDG Value w/ 2.3x inflation

23. Neutron lifetime measurement using UCNs in magnetic trap Recent measurement disagrees with accepted value by >6 sigma Our Goal: independent 1 second measurement (0.1%) New experiment design eliminates leading error of previous experiments: material wall interactions Design and initial procurement supported by LANL LDRD-DR funding Now in detailed design and procurement phase UCNs from source enter vertically UCN Trap Beta Detectors Guide Field Coils 1 meter 1 s uncertainty, 7 s discrepancy

24. Lifetime Experiment Goals and Progress Construction underway First measurement w/ prototype in 2010

25. The future: a UCN User Facility at LANSCE Fundamental physics with UCN in the U.S. –1995: about 5 active US faculty and staff –2009: 44 active US faculty and staff –7 current projects (5 based in the US) UCN Sources in US –Around 1995, only source in world of extracted UCN for experiments – Steyerl rotor at ILL –1995, superthermal LHe source development began at NIST for dedicated lifetime experiment –no extracted UCN capability –1998, SD2 source development began at LANL –2004, first tests of production SD2 source at LANL –2005, SD2 source development began at PULSTAR: much smaller than LANL source; first tests expected in 2010 –2007, superthermal LHe source development began at SNS for dedicated EDM experiment –no extracted UCN capability 2009, LANL source remains the only, operational source for extracted UCN in the US

26. Capabilities of LANSCE UCN Source Test Beam

27. Test beam port available in parallel w/ UCNA UCN Source

28. Possible Experiments for User Facility Neutron EDM experiment engineering and optimization (nEDM collaboration) Neutron beta decay measurements –Neutron lifetime (Saunders et al.) –Beta asymmetry measurements (UCNb, abBA, UCNB) Short ranged forces and quantum gravity (Baessler, NIST) Neutron interactions with surfaces and solids (Korobkina) NNbar development (NNbar collaboration) UCN source technology development (Liu et al.)

29. World’s UCN Projects SourceTypeEc (neV)  UCN (UCN/cm3) (experiment) StatusPurpose LANLSpallation/D 2 18035OperatingUCNA/ Users ILLReactor/ turbine 25040Operatingn-EDM/ Users PulstarReactor/D2335120Constructio n Users PSISpallation/D 2 2501,000Constructio n n-EDM TRIUMFSpallation/ HE-II 21010,000Planningn-EDM/ Users MunichReactor/D225010,000R&DGravity SNSn beam/HE- II 130400R&Dn-EDM

30. J. Martin

32. nEDM Storage Time at LANSCE Area B New nEDM Storage apparatus Switcher Pre-polarizer UCN Detectors Previous data Vacuum enclosure Storage cell UCN from SD 2 Source Goal: 20 K 100K300K 400s

33. Summary Ultra-cold neutrons provide a unique tool for studying fundamental weak nuclear interactions and searching for physics beyond the standard model UCNA experiment, in progress, promises world’s best measurement of A correlation parameter Neutron lifetime experiment will break new ground UCN facilities are operating or under construction world wide to exploit this growing field

34. UCNA Collaboration R. W. Pattie, Jr.R. W. Pattie, Jr., 1,2 J. Anaya, 3 H. O. Back, 1,2 J. G. Boissevain, 3 T. J. Bowles, 3 L. J. Broussard, 2,4 R. Carr, 5 D. J. Clark, 3 S. Currie, 3 S. Du, 1 B. W. Filippone, 5 P. Geltenbort, 6 A. García, 7 A. Hawari, 8 K. P. Hickerson, 5 R. Hill, 3 M. Hino, 9 S. A. Hoedl, 7,10 G. E. Hogan, 3 A. T. Holley, 1 T. M. Ito, 3,5 T. Kawai, 9 K. Kirch, 3 S. Kitagaki, 11 S. K. Lamoreaux, 3 C.-Y. Liu, 10 J. Liu, 5 M. Makela, 3,12 R. R. Mammei, 12 J. W. Martin, 5,13 D. Melconian, 7,14 N. Meier, 1 M. P. Mendenhall, 5 C. L. Morris, 3 R. Mortensen, 3 A. Pichlmaier, 3 M. L. Pitt, 12 B. Plaster, 5,15 J. C. Ramsey, 3 R. Rios, 3,16 K. Sabourov, 1 A. L. Sallaska, 7 A. Saunders, 3 R. Schmid, 5 S. Seestrom, 3 C. Servicky, 1 S. K. L. Sjue, 7 D. Smith, 1 W. E. Sondheim, 3 E. Tatar, 16 W. Teasdale, 3 C. Terai, 1 B. Tipton, 5 M. Utsuro, 9 R. B. Vogelaar, 12 B. W. Wehring, 8 Y. P. Xu, 1 A. R. Young, 1,2 and J. Yuan 5J. AnayaH. O. BackJ. G. BoissevainT. J. BowlesL. J. BroussardR. CarrD. J. ClarkS. CurrieS. DuB. W. FilipponeP. GeltenbortA. GarcíaA. HawariK. P. HickersonR. HillM. HinoS. A. Hoedl G. E. HoganA. T. HolleyT. M. ItoT. KawaiK. KirchS. KitagakiS. K. LamoreauxC.-Y. LiuJ. LiuM. MakelaR. R. MammeiJ. W. MartinD. MelconianN. MeierM. P. MendenhallC. L. MorrisR. MortensenA. PichlmaierM. L. PittB. PlasterJ. C. RamseyR. RiosK. SabourovA. L. SallaskaA. SaundersR. SchmidS. SeestromC. ServickyS. K. L. SjueD. SmithW. E. SondheimE. TatarW. TeasdaleC. TeraiB. TiptonM. UtsuroR. B. VogelaarB. W. WehringY. P. XuA. R. YoungJ. Yuan 1Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA 2Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA 3Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA 4Department of Physics, Duke University, Durham, North Carolina 27708, USA 5W. K. Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USA 6Institut Laue-Langevin, 38042 Grenoble Cedex 9, France 7Physics Department, University of Washington, Seattle, Washington 98195, USA 8Department of Nuclear Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA 9Research Reactor Institute, Kyoto University, Kumatori, Osaka, 590-0401, Japan 10Physics Department, Princeton University, Princeton, New Jersey 08544, USA 11Tohoku University, Sendai 980-8578, Japan 12Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, USA 13Department of Physics, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada 14Cyclotron Institute, Texas A&M University, College Station, Texas 77843, USA 15Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA 16Department of Physics, Idaho State University, Pocatello, Idaho 83209, USA