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The Neutron Alphabet Exploring the properties of fundamental interactions with cold neutrons

The Neutron Alphabet Exploring the properties of fundamental interactions with cold neutrons. Hartmut Abele. The Neutron Alphabet and Symmetries. A: P-odd B: P-odd C: P-odd D: T-odd a N R: T-odd. A. Neutron Spin. . Electron. B. Neutrino. C. Proton.

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The Neutron Alphabet Exploring the properties of fundamental interactions with cold neutrons

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  1. The Neutron Alphabet Exploring the properties offundamental interactions with cold neutrons Hartmut Abele

  2. The Neutron Alphabet and Symmetries • A: P-odd • B: P-odd • C: P-odd • D: T-odd • a • N • R: T-odd A Neutron Spin  Electron B Neutrino C Proton

  3. Experimental Groups, Neutron b-DecayNew experiments are greatly profiting from new sources & techniquesTalks at NIST workshop from different groups in 2004:

  4. Facilities 2.0 Nico, Snow, Annu Rev Nucl Part Sci 55 (2005) 55

  5. Facilities Nico, Snow, Annu Rev Nucl Part Sci 55 (2005) 55

  6. Nuclear and Particle Physics Neutrograph, Radio- and Tomography station

  7. The PERKEO II Setup @ ILL 1. Polarizer M. Schumann 2006 2. Spin Flipper 3. Spectrometer 4. Beam Stop

  8. The new Polarizer: 99.7 % EfficiencyKreuz, Soldner, Pekoutov, Nesvizhevsky, NIM 2006 100 % • ILL, HD • A new geometry for Beam polarization • Towards a perfectly polarized neutron beam 96 % 94 % Status 2002 90 % 100 % Spin up: reflected Spin down: absorbed Coherent nuclear (strong) and electronic (magnetic) scattering 98 % 96 % 95 % Status 2004

  9. Lab frame Rotating frame Rotating frame Rf Spin flipper: 100% efficiencyT. Soldner & A. Petoukhov

  10. Cold NeutronsFor Correlation Coefficient A Measurements… • High Flux:  = 2 x 1010 cm-2s-1  Decay rate of 1 MHz / meter / sec • Count rate: 106 s-1 • Polarized to 98%: 2.5 x 105 s-1 • Polarized to 99.7%: 1.4 x 105 s-1 • Pulsed/unpulsed • Spectrometer

  11. Experiments

  12. PERKEO III Characteristics of Experiments Using Magnetic Fields 

  13. PERKEO III20 October 2006 – 11 April 2007 • Small systematic errors - background - edge effect - mirror effect to beamstop B. Maerkisch, D. Dubbers, H.A. et al.

  14. PERKEO III

  15. Aim: Weak Magnetism form factor f2 Neutron Decay Transition Matrix: f2 Weak Magnetism Form Factor (SM prediction) Electron Asymmetry: 2 % additional Edependence of A PERKEO III can deliver the necessary statistics! Talk Marc Schumann at ILL

  16. a Spect, Univ. MZ/TUM • Proton spectroscopy

  17. First impression aSPECT is a retardation spectrometer for protons of free neutron decay aSPECT

  18. PNPI Experiment

  19. aCORN Surface barrier detector

  20. emiT Trine D-Coefficient

  21. Electron and neutrino momenta from electron energy cose from proton momentum and electron energy using 4T  1T TOF between electron and proton Nab

  22. UCNA Collaboration California Institute of Technology R. Carr, B. Filippone, J. Hsiao, R. McKeown, B. Plaster, B. Tipton, J. Yuan Institute Lau-Langevin P. Geltenbort Idaho State University R. Rios, E. Tatar Los Alamos National Laboratory J. Anaya, T. J. Bowles (co-spokesperson), T. Brun, M. Fowler, R. Hill, G. Hogan, T. Ito, K. Kirch, S. Lamoreaux, M. Makela, C. L. Morris, A. Pichlmaier, A. Saunders, S. Seestrom, P. Walstrom North Carolina State University/TUNL H. O. Back, L. Broussard, A. T. Holley, R. K. Jain, R. W. Pattie, K. Sabourov, A. R. Young (co-spokesperson), Y.-P. Xu Petersburg Nuclear Physics Institute A. Aldushenkov, A. Kharitonov, I. Krasnoshekova, M. Lasakov, A. P. Serebrov, A. Vasiliev Tohoku University S. Kitagaki University of Kyoto M. Hino, T. Kawai, M. Utsuro University of Washington A. Garcia, S. Hoedl, D. Melconian, A. Sallaska, S. Sjue University of Winnipeg J. Martin Virginia Polytechnic Institute and State University R. Mammei, M. Pitt, R. B. Vogelaar

  23. Results: A A Neutron Spin Electron

  24. Results PERKEO II(2006) • Spectra Dissertation D. Mund, 2006

  25. Result for A Dissertation D. Mund, 2006

  26. Beamrelated Background Electron-Spectrum Beamline BG • Collimation system < 0.15 s-1 Det. 0 Det. 1 Fitregion

  27. 2002: result: A = -0.1189(8)  = -1.2739(19)2006: result: A = -0.1198(5)  = -1.2762(13)

  28. a bit history:l from neutron b-decay • -1.19(2), PDG (1960) • -1.25(2), PDG (1975) • -1.261(4), PDG (1990) • -1.2594(38), Gatchina (1997) • -1.2660(40), M, ILL (1997) • -1.2740(30), HD, ILL (1997) • -1.2686(47), Gatchina, ILL (2001) • -1.2739(19), HD, ILL (2002) • -1.2762(13), HD, ILL (2006) Red: PDG 2006

  29. Why ratio= gA/ gV from Neutrons? • Processes with the same Feynman-Diagram Slide from D. Dubbers

  30. What about the lifetime?PDG: 885.7 ± 0.7 sSerebrov et al.: 878.5 ± 0.7 s • Calculate SM Lifetime • t = 880.5 ± 1.5 s • vs 885.7 ± 0.7 s PDG 2006 • vs 878.5± 0.7 s Serebrov et al.

  31. A Neutron Spin Neutron Spin B Electron B  Neutrino Neutrino C Proton 2. Correlation B in neutron -decay Neutrino Asymmetry Wd~ (1 + B cos ) d n  p e e

  32. The Neutrino-Asymmetry B Systematically clean method: Integration over two hemispheres • Electron and Proton in same hemisphere • Electron and Proton in opposite hemispheres Neutron Spin Electron Proton ‚‘ Neutrino Neutron Spin Electron Neutrino Proton

  33. Proton detector C foil on 25 keV Scintillator Proton • Proton detection: • Measure electron energy • Wait for proton • Convert proton into • electron signal n-Spin

  34. Proton “electron” spectrum Dissertation J. Reich Dissertation: J. Reich

  35. Result: AsymmetryBThesis: M. Schumann 9 May 2007 • only experiment that measures B in the same hemisphere •  result is virtually independent from detector calibration • result limited by statistics and error in beam position relative to magn. field ( magnetic mirror effect) Background Bn Displacement Our Result: New mean Value:Bmean = 0.9807(30) B = 0.9802(50)

  36. Corrections and Errors: AsymmetryB

  37. A Neutron Spin Neutron Spin Electron  C C Proton Proton 2. Correlation C in neutron -decay Wd~ (1 + C cos ) d n  p e e

  38. Neutron Spin Proton Electron Neutrino Proton AsymmetryC Dissertation M. Schumann, 2007 • proton emission w.r.t. neutron spin: N↑, N↓ (coincidence measurement with electrons) • use electron spectra and integrate over electron energy E • define ProtonAsymmetry • Problem: Energy threshold for electron detection • PERKEO II (2004): C = 0.238(11)PhD M. Kreuz, J. Res. NIST. 110 (2005)

  39. Proton Asymmetry C, ResultsThesis: M.Schumann 9 May 2007 • Our Result: • first precision measurement • error dominated by extrapolation and detector calibration • C is better known than e correlation a • agrees with SM value: • new SM Tests possible: Q++ Q C = 0.2377(25) proton in spin direction proton against spin direction Q+ Q+ CSM = 0.2392(4) • One-parameter fit • Extrapolation • Integration

  40. The future

  41. Aim: Spectra and angular distributions distortion-free on the level of 10-4, 10x better than achieved today

  42. A clean, bright andversatile source ofneutron decay products:Perc n-guide: white, continuous n-beam n-velocity selector n-polarizer n-spin flipper n-guide n-chopper gap + dump n-guide + solenoid: field B0 polarized, monochromatic n-pulse n + γ-beam stop solenoid, field B1 solenoid, field B2 p+ + e− window-frame p+ + e− beam

  43. Cont. unpol: After mag. Barrier: Polarized to 98%: Pulsed: Pulsed polarized 99.7% Expected count rates Tn·Is=1.2104s−1. Tn'Is'=300s−1.

  44. Dubbers, Baessler, Märkisch, Schumann, Soldner, Zimmer, H.A. • Table 1: Error budget of PERC in standard configuration. • The numbering in this list is the same as in Sections 4.1 to 4.5.

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