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

Hartmut Abele, University of Heidelberg 2 The Neutron Alphabet and Symmetries A: P-odd B: P-odd C: P-odd D: T-odd a N R: T-odd Electron Proton Neutrino Neutron Spin A B C

Hartmut Abele, University of Heidelberg 3 Experimental Groups, Neutron -Decay New experiments are greatly profiting from new sources & techniques Talks at NIST workshop from different groups in 2004:

Hartmut Abele, University of Heidelberg 4 Facilities Nico, Snow, Annu Rev Nucl Part Sci 55 (2005)

Hartmut Abele, University of Heidelberg 5 Facilities Nico, Snow, Annu Rev Nucl Part Sci 55 (2005) 55

Hartmut Abele, University of Heidelberg 6 Nuclear and Particle Physics Neutrograph, Radio- and Tomography station

Hartmut Abele, University of Heidelberg 7 The PERKEO II ILL 1. Polarizer 2. Spin Flipper 3. Spectrometer 4. Beam Stop M. Schumann 2006

Hartmut Abele, University of Heidelberg 8 The new Polarizer: 99.7 % Efficiency Kreuz, Soldner, Pekoutov, Nesvizhevsky, NIM 2006 ILL, HD A new geometry for Beam polarization Towards a perfectly polarized neutron beam Status 2002 Status % 100 % 96 % 100 % 90 % 95 % 94 % 96 % Spin up: reflected Spin down: absorbed Coherent nuclear (strong) and electronic (magnetic) scattering

Hartmut Abele, University of Heidelberg 9 Rf Spin flipper: 100% efficiency T. Soldner & A. Petoukhov Lab frame Rotating frame

Hartmut Abele, University of Heidelberg 10 Cold Neutrons For Correlation Coefficient A Measurements… High Flux: = 2 x cm -2 s -1 Decay rate of 1 MHz / meter / sec Count rate: 10 6 s -1 Polarized to 98%: 2.5 x 10 5 s -1 Polarized to 99.7%: 1.4 x 10 5 s -1 Pulsed/unpulsed Spectrometer

Hartmut Abele, University of Heidelberg 11 Experiments

Hartmut Abele, University of Heidelberg 12 Characteristics of Experiments Using Magnetic Fields PERKEO III

Hartmut Abele, University of Heidelberg 13 B. Maerkisch, D. Dubbers, H.A. et al. Small systematic errors - background - edge effect - mirror effect PERKEO III 20 October 2006 – 11 April 2007 to beamstop

Hartmut Abele, University of Heidelberg 14 PERKEO III

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Hartmut Abele, University of Heidelberg 19 Aim: Weak Magnetism form factor f 2 Neutron Decay Transition Matrix: Electron Asymmetry: f 2 Weak Magnetism Form Factor (SM prediction) 2 % additional E dependence of A PERKEO III can deliver the necessary statistics! Talk Marc Schumann at ILL

Hartmut Abele, University of Heidelberg 20 a Spect, Univ. MZ/TUM Proton spectroscopy

Hartmut Abele, University of Heidelberg 21 aSPECT is a retardation spectrometer for protons of free neutron decay aSPECT First impression

Hartmut Abele, University of Heidelberg 22 PNPI Experiment

Hartmut Abele, University of Heidelberg 23 aCORN Surface barrier detector

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Hartmut Abele, University of Heidelberg 25 D-Coefficient emiT Trine

Hartmut Abele, University of Heidelberg 26 N ab Electron and neutrino momenta from electron energy cos e from proton momentum and electron energy using 4T 1T TOF between electron and proton

Hartmut Abele, University of Heidelberg 27 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 UCNA Collaboration

Hartmut Abele, University of Heidelberg 28 Results: A Electron Neutron Spin A

Hartmut Abele, University of Heidelberg 29 Results PERKEO II (2006) Spectra Dissertation D. Mund, 2006

Hartmut Abele, University of Heidelberg 30 Result for A Dissertation D. Mund, 2006

Hartmut Abele, University of Heidelberg 31 Beamrelated Background Collimation system < 0.15 s -1 Det. 0 Det. 1 Fitregion Electron- Spectrum Beamline BG

Hartmut Abele, University of Heidelberg : result: A = (8) = (19) 2006: result: A = (5) = (13)

Hartmut Abele, University of Heidelberg (2), PDG (1960) -1.25(2), PDG (1975) (4), PDG (1990) (38), Gatchina (1997) (40), M, ILL (1997) (30), HD, ILL (1997) (47), Gatchina, ILL (2001) (19), HD, ILL (2002) (13), HD, ILL (2006) a bit history: from neutron -decay Red: PDG 2006

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Hartmut Abele, University of Heidelberg 35 Why ratio = g A / g V from Neutrons? Processes with the same Feynman-Diagram Slide from D. Dubbers

Hartmut Abele, University of Heidelberg 36 What about the lifetime? PDG: ± 0.7 s Serebrov et al.: ± 0.7 s Calculate SM Lifetime = ± 1.5 s -vs ± 0.7 s PDG vs ± 0.7 s Serebrov et al.

Hartmut Abele, University of Heidelberg Correlation B in neutron -decay Neutrino Asymmetry n p e e Wd ~ (1 + B cos ) d Wd ~ (1 + B cos ) d Neutrino Neutron Spin B Electron Proton Neutrino Neutron Spin A B C

Hartmut Abele, University of Heidelberg 38 Electron and Proton in same hemisphere Electron and Proton in opposite hemispheres The Neutrino-Asymmetry B Electron Proton Neutron Spin Neutrino Electron Proton Neutrino Neutron Spin Systematically clean method: Integration over two hemispheres

Hartmut Abele, University of Heidelberg 39 Proton detector C foil on 25 keVScintillator Proton Proton detection: Measure electron energy Wait for proton Convert proton into electron signal Proton detection: Measure electron energy Wait for proton Convert proton into electron signal n-Spin

Hartmut Abele, University of Heidelberg 40 Proton electron spectrum Dissertation: J. Reich Dissertation J. Reich

Hartmut Abele, University of Heidelberg 41 Our Result: New mean Value: B mean = (30) Result: Asymmetry B Thesis: M. Schumann 9 May 2007 Background B n Displacement B = (50) 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)

Hartmut Abele, University of Heidelberg 42 Corrections and Errors: Asymmetry B Detector 1Detector 2 Corr. [%]Error [%]Corr. [%]Error [%] Polarization Flipper-Efficiency0.1 Statistics Coincidence Measurement Background Detector0.02 Systematics. Mirror Effect Displacement Other Other Coefficients0.07 Sum

Hartmut Abele, University of Heidelberg Correlation C in neutron -decay n p e e Proton Neutron Spin C Wd ~ (1 + C cos ) d Wd ~ (1 + C cos ) d Electron Proton Neutron Spin A C

Hartmut Abele, University of Heidelberg 44 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) Proton Asymmetry C Electron Proton Neutron Spin Neutrino Dissertation M. Schumann, 2007

Hartmut Abele, University of Heidelberg 45 Proton Asymmetry C, Results Thesis: M.Schumann 9 May ) 1)One-parameter fit 2) 2)Extrapolation 3) 3)Integration proton in spin direction proton against spin direction 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 + Q C = (25) C SM = (4)

Hartmut Abele, University of Heidelberg 46 The future

Hartmut Abele, University of Heidelberg 47 Aim: Spectra and angular distributions distortion-free on the level of 10 -4, 10x better than achieved today

Hartmut Abele, University of Heidelberg 48 n-guide: white, continuous n-beam n-velocity selector n-polarizer n-spin flipper n-guide n-chopper gap + dump n-guide + solenoid: field B 0 polarized, monochromatic n-pulse n + γ -beam stop solenoid, field B 1 solenoid, field B 2 p + + e window-frame p + + e beam A clean, bright and versatile source of neutron decay products: Perc

Hartmut Abele, University of Heidelberg 49 Expected count rates Cont. unpol: After mag. Barrier: Polarized to 98%: Pulsed: Pulsed polarized 99.7% T n ·I s = s 1. T n 'I s '=300s 1.

Hartmut Abele, University of Heidelberg 50 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. SOURCE OF ERRORCOMMENT SIZE OF CORRECT. SIZE OF ERROR: non-uniform n-beam for ΔΦ/Φ = 10 % over 1 cm width 2.5·104 5·10 5 other edge effects on e/p-window for worst case at max. energy 4·10 4 1·104 magn. mirror effect, contin's n- beam 1.4·102 2·104 magn. mirror effect, pulsed n- beam for ΔB/B = 10 % over 8 m length 5·10 5 <10 5 non-adiabatic e/p-transport 5·10 5 background from n-guide }is separately measurable ·10 4 background from n-beam stop 2·10 4 1·10 5 backscattering off e/p-window 2·10 5 1·105 backscattering off e/p-beam dump backscatt. off plastic scintillator }for worst case ·10 4 ~ same with active e/p-beam dump 1·10 4 neutron polarisation present status 3·10 3 1·10 3 Dubbers, Baessler, Märkisch, Schumann, Soldner, Zimmer, H.A.