1. Hartmut Abele, Technische Universität Wien Bastian Märkisch Hartmut Abele CKM2014 Neutron Beta Decay: Determination of the Weak Axial Vector Coupling

2. 2 Neutron  -decay lifetime  ~ 15 min  -endpoint: E max = 782 keV V-A Theory: Vector coupling:g V = G F V ud f 1 (q 2 →0) Axial vector coupling: g A = G F V ud g 1 (q 2 →0) ratio = g A / g V = -1.276 Standard Model: V ud,, e i  = -1 Standard Model and Neutron Decay

3. 3 Parameters Strength: G F Quark mixing: V ud Ratio: = g A /g V Observables Lifetime  Correlation A Correlation B Correlation C Correlation a Correlation D Correlation N Correlation Q Correlation R Beta Spectrum Proton Spectrum Beta Helicity Electron Proton Neutrino Neutron Spin A B C a D R N Neutron Alphabet deciphers the SM High Precision - Low Energy Hartmut Abele, Atominstitut, TU Wien R Q

4. 4 a,A  = g A / g V A +   V ud from CKM matrix A + B +   Right Handed Currents (RHC)? WLWL WRWR Neutron Alphabet deciphers the SM H. Abele, NIM A 611 (2009) 193–197

5. 5 D, R ? T-odd  CP-violation CP See P. Herczeg, Prog. Part. Nucl. Phys. 46 (2001) 413.  Candidate models for scalar couplings (at tree-level):  Charged Higgs exchange  Slepton exchange (R-parity violating super symmetric models)  Vector and scalar leptoquark exchange  The only candidate model for tree-level tensor contribution (in renormalizable gauge theories) is:  Scalar leptoquark exchange Courtesy of K. Bodek Neutron Alphabet deciphers the SM

6. Hartmut Abele, Technische Universität München 6 Characteristics of Experiments Using Magnetic Fields (Dubbers 1980s) A, B, C PERKEO I Method: P. Bopp et al., NIM A 267 (1988) 436.

7. 7 Why ratio = g A / g V from Neutrons? Processes with the same Feynman-Diagram Courtesy of D. Dubbers

8. P ERKEO II Spectrometer 8.9.2014CKM 2014, Vienna - Bastian Märkisch8 X-SM crossed polariser geometry: Kreuz et al., NIM A 547, 583 (2005) Neutron polarisation P = 99.7(1)% Largely reduced background (Mund et al., PRL 110 (2013)) Improved beam line setup and shielding, Overall S:B = 8:1 Beam related background : 1/1700 in signal region (previous:1/200) 3 rd run (beta asymmetry), major Improvements: Magnetic field: alignment of neutron  spin guide e , p onto detectors separation into hemispheres  2 x 2  detector backscatter suppression

9. Error Budget A 9

10. 10 -1.1900(200), PDG (1960) -1.2500(200), PDG (1975) -1.2610(40), PDG (1990) -1.2594(38), Gatchina (1997) -1.2660(40), M, ILL (1997) -1.2740(30), PERKEO II (1997) -1.2686(47), Gatchina, ILL (2001) -1.2739(19), PERKEO II (2002) −1.27590(+409)(−445), UCNA (2011) -1.2756(30), UCNA (2013) -1.2748 +13 -14 PERKEO II (2013) a bit history:  from neutron  -decay

11. PERKEO II: Combined Result 8.9.2014CKM 2014, Vienna - Bastian Märkisch11 Combine all PERKEO II results: H. Abele et al., Phys. Lett. B 407, 212 (1997)A = - 0.1189(12) H. Abele et al., PRL 88, 211801 (2002)A = - 0.1189(8) D. Mund et al., PRL 110, 172502 (2013)A = - 0.11972( +53 -65 ) Final Perkeo II result: A = - 0.11926( +47 -53 )ΔA/A = 4.2 ∙ 10 -3 λ = - 1.2748( +13 -14 ) Δ λ / λ = 1.1 ∙ 10 -3 Conservative treatment of correlated errors: detector calibration and uniformity, background determination, edge effect, radiative correction Vud = 0.97449(18) RC (40) tau (80) A Vud = 0.97425(8) exp.(10) nucl.dep. (18) RC (superallowed)

12. 12 -1.1900(200), PDG (1960) -1.2500(200), PDG (1975) -1.2610(40), PDG (1990) -1.2594(38), Gatchina (1997) -1.2660(40), M, ILL (1997) -1.2740(30), PERKEO II (1997) -1.2686(47), Gatchina, ILL (2001) -1.2739(19), PERKEO II (2002) −1.27590(+409)(−445), UCNA (2011) -1.2756(30), UCNA (2013) -1.2748 +13 -14 PERKEO II (2013) a bit history:  from neutron  -decay

13. 13  -1.2756(30), UCNA (2013) UCNA (2013)

14. Recent Results: PERKEO Collaboration 14 A =-0.1197(6) A PII =  0.1193(5) PII =  1.2748(13) error: 1×10  3 Electron Asymmetry A: PRL 110, 172502 (2013) Proton Asymmetry C: Neutrino Asymmetry B: B = 0.9802(50) Schumann et a. PRL 99, 191803 (2007) PERKEO II combined: first precision measurement C =  0.2377(36) Schumann et al., PRL 100, 151801 (2008)

15. Coefficient B,C Proton detector H. Abele, NIM A 611 (2009) 193–197 15 C foilScintillator 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

16. M. Schumann: The Neutrino-Asymmetry B M. Schumann,M. Kreuz, M. Deissenroth,F. Glück,J. Krempel, B. Märkisch,D Mund, A. Petoukhov, T. Soldner, H. Abele, PRL 100, 151801 (2008) 16 Electron and Proton in same hemisphere  low dependence on energy calibration and energy resolution  higher sensitivity due to larger exp. asymmetry Electron and Proton in opposite hemispheres  more statistics since this case occurs for ~78% of the events Electron Proton Neutron Spin Neutrino Electron Proton Neutrino Neutron Spin Systematically clean method: Integration over two hemispheres

17. Coefficient B, Serebrov et al. H. Abele, TU Wien 17

18. PERKEO III B. Märkisch:Spectrometer P ERKEO III 8.9.201418 Magnetic field : alignment of n  spin guide e , p onto detectors  2 x 2  detector separation into hemispheres detector neutron beam electron tracks B = 150 mT active volume ~2m, 15x15cm² B = 90 mT decay volume 10x longer: ~50.000 events/s in cont. Beam B = 0.15T CKM 2014, Vienna - Bastian Märkisch B. Maerkisch et al., NIM 611 (2009) 216–218

19. PERKEO III velocity selector =5.0Å ∆  ~2m, 150mT beam dump, enriched 10 B homogeneous field Continuous, “monochromatic” neutron beam chopper ( 6 LiF) @ 94Hz magnetic field Pulsed Cold Neutron Beam 8.9.201419 electron detector Edge-free projection onto detectors: full 2 x 2  detection without distortions Background can be fully measured and subtracted D. Werder, UHD Magnetic mirror effect controlled Benefits: CKM 2014, Vienna - Bastian Märkisch

20. PERKEO III Pulsed Neutron Beam 8.9.2014CKM 2014, Vienna - Bastian Märkisch20 time for signal measurement neutrons hit beam dump time for background measurement slopes due to magnetic mirror Signal region 300 keV < E < 700 keV upstream downstream

21. PERKEO III Background Subtraction 8.9.201421 Time variation of background signal consistent with zero! Signal region 300 keV < E < 700 keV Additional background tests: Background monitors (NaI and He), control measurements with blocked beam Chopper 83 Hz Chopper 94 Hz CKM 2014, Vienna - Bastian Märkisch counts (a.u.)

22. PERKEO III Installation at PF1B, ILL 8.9.201422 One of two trucks Plastic scintillator Experimental Zone 96% of data acquired in analysis 6 ∙ 10 8 neutron decay events

23. PERKEO III Beta Asymmetry, Chopper 94 Hz 23 Raw Signal + Background Signal, Background Subtracted Sum and Difference Experimental Asymmetry preliminary

24. PERKEO III Source Correction ∆A/A (10 -4 ) Uncertainty ∆A/A (10 -4 ) Predecessor Neutron beam Polarisation < 10 / 1.4 Spin flip efficiency Background/ 7 Undetected1 Time variation1 Electrons Magnetic mirror effect4 Lost backscatter energy1.4 Detector Deadtime *-52 Non-linearity4/ 4.6 Non-uniformity3 Stability *2 Calibration0.5 Theory Radiative corr. *-1.12 Total Systematics12.4/ 3.2 Statistics 13.9/ 2.7 Total 18.6 Error Budget 24 separate analysis Result (still blinded): separate analysis 2.3x better than Perkeo II

25. PERKEO III P ERKEO III Team 8.9.201425 D. Dubbers, B. Märkisch, H. Mest, C. Roick, D. Werder Heidelberg University H. Abele, H. Saul, X. Wang Institut Laue Langevin, Grenoble T. Soldner, A. Petoukhov TU Vienna, TU Munich PERKEO III Team, ILL

26. Source Correction ∆A/A (10 -4 ) Uncertainty ∆A/A (10 -4 ) Predecessor Neutron beam Polarisation < 10 / 1.4 Spin flip efficiency Background/ 7 Undetected1 Time variation1 Electrons Magnetic mirror effect4 Lost backscatter energy1,4 Detector Deadtime *-52 Non-linearity4/ 4.6 Non-uniformity3 Stability *2 Calibration0,5 Theory Radiative corr. *-1,12 Total Systematics12,4/ 3.2 Statistics 13,9/ 2.7 Total 18,6 Error Budget Uni HD Maerkisch et al., ILL: Soldner et al. TU Wien: Wang et al. 26 separate analysis Result: separate analysis Factor 4 improvement over PDG 2013 average

27. Close to Publication aCORN @ NIST aSPECT @ Mz, ILL, TUW PERKEO III @ UHD, ILL, TUW: A (B,C not so close) New Instruments Nab, PERC Hartmut Abele, Atominstitut, Vienna University of Technology 27

28. R. Feynman Hart mut Abe le, Hel mut Lee b, Tec hnis che Uni vers ität Wie n 28

29. A physicist wants … -… to derive the basic laws of nature Fundamental Physics

30. 30 Standard Model of Particle Physics Input: Principia: -Gauge principle U(1) x SU(2) x SU(3) -Lorentz invariance : x‘ = Lx -CPT,...Invariance Output: -Interactions -Equation of motion Maxwell, Schrödinger, Dirac -Existence of Photons, Gluons, W ±, Z 0 (carriers of interaction) -Charge conservation (Source of interaction) Conclusion: SM very successful -e.g. as basis for technology, chemistry, biology, mol.biologie D. Dubbers 2007

31. 31 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

32. Beyond SM A search for -right-handed admixtures to the left-handed feature of the Standard model. They are forbidden in the Standard-Model, but, as a natural consequence of symmetry breaking in the early universe, they should be found in neutron-decay. Signatures are a W R mass with mixing angle z. -scalar and tensor admixtures g S and g T to the electroweak interaction. g S and g T are also forbidden in the Standard model but supersymmetry contributions to correlation coeffi­cients or the Fierz interference term b can approach the 10 −3 level. A precision measurement of -the weak-magnetism form factor f 2 prediction of electroweak theory. Such an experiment would be one of the rare occasions, where a strong test of the underlying structure itself of the Standard model becomes available. Supersymmetry search in the LHC era: -one could expect small deviations in the low-energy tests, such as deviations from CKM unitarity, but no effect at the LHC, especially if the supersymmetry spectrum is below one TeV, but the spectrum is compressed, or if some of the superpartners are light and others are heavy (a variant on the “split-SUSY” scenario) Hartmut Abele, Atominstitut, TU Wien 32

33. Participating Institutions: IST Braunschweig Univ. Heidelberg ILL Univ. Jena Univ. Mainz Priority Areas CP-symmetry violation and particle physics in the early universe. The structure and nature of weak interaction and possible extensions of the Standard Model. Tests of gravitation with quantum objects Charge quantization and the electric neutrality of the neutron. New Infrastructure (UCN-Source, cold Neutrons) -* Coordinators first round (S. Paul, H.A. ) DFG/FWF Priority Programme 1491 : Precision experiments in particle- and astrophysics with cold and ultracold neutrons, Exzellenzcluster ‚Universe‘ München Techn. Univ. München * PTB Berlin Vienna University of Technology *

34. Priority Programme 1491 Research Area A: CP-symmetry violation and particle physics in the early universe -Neutron EDM  E = 10 -23 eV Research Area B: The structure and nature of weak interaction and possible extensions of the Standard Model -Neutron  -decay V – A Theory Research Area C: Test of gravitation with quantum interference -Neutron bound gravitational quantum states Research Area D: Charge quantization and the electric neutrality of the neutron -Neutron charge Research Area E: New measuring techniques -Particle detection -Magnetometry -Neutron optics

35. Experiment PERC -PERC, a clean, bright and versatile source of neutron decay products (Maerkisch) -Proton spectroscopy (Heil, Zimmer) -Electron spectroscopy (Abele) -Neutron polarisation + analysis with 10 -4 accuracy (Soldner) - design of the beam line for PERC (Soldner, Jericha) -Development of a non-depolarising neutron guide needed for PERC (Schmidt) Measurement of the neutron lifetime -O. Zimmer et al. Measurement of n -> H -S. Paul et al. Priority area B (first 3 years round): Novel experiments on neutron beta-decay

36. SM tests on 10 -4 level Theory -Recalculation of corrections induced by the “weak magnetism”, the proton recoil and the radiative corrections. -A. Ivanov, M. Pitschmann, and N. Troitskaya, Phys.Rev. D88, 073002 (2013), 1212.0332. Experiment PERC -High statistic measurements: -Today: High Average Flux:  = 2 x 10 10 cm -2 s -1 -Decay rate of 1 MHz / metre -Thesis C. Klauser (2013) Polarizer  P/P = 10 -4, Spin Flipper  f/f = 10 -4 Hartmut Abele, Atominstitut, Vienna University of Technology 36

37. Proton Electron Radiation Channel: B. Maerkisch D. Dubbers et al., NIM A 596 (2008) 238 and arXiv:0709.4440 G. Konrad et al. (for the PERC collaboration), J. Phys.: Conf. Ser. 340 (2012) 012048 =0.5T cold Versatile: A, B, C, a, b, κ, … Sensitivity:improved by up to 2 orders of magnitude high phase space density Systematics:10 -4 (for e - ) precise cuts in d Ω e : Requirements:no local field minima adiabaticity criterion B 1 homogeneity 10 -4 in e/p beam

38. Superconducting Magnet 8.9.201438 Preliminary Magnet Design L = 11.3m Precision experiments in particle and astrophysics with cold and ultracold neutrons Priority Programme 1491 6 T 1.5 T Status: Magnet in production Installation in 2016 Physikalisches Institut Universität Heidelberg

39. G. Konrad: R x B Spectrometer 39

40. R×B Drift Momentum Spectroscopy  Small drift distances  (cm) Xiangzun Wang, G. Konrad et al., NIM A (2012), DOI 10.1016/ j.nima.2012.10.071 + Adiabatic transport of particles + Low momentum measurements + Large acceptance of θ 0 + Small corrections for θ 0 Last Coil of PERC Tilted Coils e - /p + beam Detector Aperture y z x y x z RxBRxB vdvd qR²B² B 3 =0.15T B 2 =0.5T ElectronsProtons D D R B α

41. Hartmut Abele, Technische Universität München 41 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 2.5·10 −4 5·10 −5 other edge effects on e/p-window for worst case at max. energy 4·10 −4 1·10 −4 magn. mirror effect, contin's n-beam 1.4·10 −2 2·10 −4 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 2∙10 −3 1·10 −4 background from n-beam stop 2·10 −4 1·10 −5 backscattering off e/p-window 2·10 −5 1·10 −5 backscattering off e/p-beam dump 5∙10 −5 1∙10 −5 backscatt. off plastic scintillator }for worst case 2∙10 −3 4·10 −4 ~ same with active e/p-beam dump − 1·10 −4 neutron polarisation present status 3·10 −4 1·10 −4 Dubbers, Baessler, Märkisch, Schumann, Soldner, Zimmer, H.A., arXiv 2007

42. PERC Collaboration B. Märkisch U. Schmidt D. Dubbers H. Mest L. Raffelt C. Roick N. Rebrova C. Ziener R. Maix B. Windelband H. Abele E. Jericha G. Konrad J. Erhart C. Gösselsberger X. Wang H. Fillunger M. Horvath R. Maix J. Klenke T. Lauer H. Saul K. Lehmann T. Soldner O. Zimmer C. Klauser W. Heil M. Beck Heidelberg Vienna FRM II, Munich Grenoble 8.9.201442CKM 2014, Vienna - Bastian Märkisch

43. Reserva Hartmut Abele, Atominstitut, Vienna University of Technology 43

44. P ERKEO II: Polarisation 44 Single Polariser:X-SM Geometry: New polarisation technique: X-SM (crossed super mirror) polarisers Kreuz et al., NIM A 547, 583 (2005) New analyser technology: 3 He Spin Filters Average polarisation: 99.7(1)%, spin flip efficiency 100.0(1)% Correction 4 times smaller, uncertainty 3 times smaller wavelength 8.9.2014CKM 2014, Vienna - Bastian Märkisch

45. P ERKEO II: Background 8.9.201445 shutter up shutter down closed Shutter Down – Shutter Up, Detector 1 Overall S:B = 8:1 in fit region Background variation due to changes of neighbouring instruments: reduced data set (70%) Beam-related background determined by extrapolation procedure, Reich al., NIM A 440. Only 1/1700 of the electron rate in signal region (previous: 1/200)

46. P ERKEO II: Error Budget 8.9.2014CKM 2014, Vienna - Bastian Märkisch46 Mund et al., PRL 110 (2013)

47. PERKEO II Result, 2013 8.9.2014CKM 2014, Vienna - Bastian Märkisch47 Combined, including corrections: A = −0.11972 (45) stat ( +32 -44 ) sys = −0.11972( +53 -65 ); = −1.2761( +14 -17 ) Combined, including corrections: A = −0.11972 (45) stat ( +32 -44 ) sys = −0.11972( +53 -65 ); = −1.2761( +14 -17 ) Fit: A det 1 = −0.11846(64) stat Fit: A det 2 = −0.12008(64) stat Difference in results for both detectors in agreement with expectation from magnetic mirror effect.

48. PERKEO II: Combined Result 8.9.2014CKM 2014, Vienna - Bastian Märkisch48 Combine all PERKEO II results: H. Abele et al., Phys. Lett. B 407, 212 (1997)A = - 0.1189(12) H. Abele et al., PRL 88, 211801 (2002)A = - 0.1189(8) D. Mund et al., PRL 110, 172502 (2013)A = - 0.11972( +53 -65 ) Final Perkeo II result: A = - 0.11926( +47 -53 )ΔA/A = 4.2 ∙ 10 -3 λ = - 1.2748( +13 -14 ) Δ λ / λ = 1.1 ∙ 10 -3 Conservative treatment of correlated errors: detector calibration and uniformity, background determination, edge effect, radiative correction

49. 49 M. Pitschmann, A. Ivanov, Atominstitut, Vienna University of Technology

50. 50 M. Pitschmann, A. Ivanov, Atominstitut, Vienna University of Technology

51. 51 M. Pitschmann, A. Ivanov, Atominstitut, Vienna University of Technology

52. 52

53. 53

54. 54

55. Coefficient A 55 Hartmut Abele, Vienna University of Technology

56. Coefficient C 56 Hartmut Abele, Vienna University of Technology

57. Error budget B

58. Error Budget C 58