1 / 39

P and T violating correlation in muon and beta decays

P and T violating correlation in muon and beta decays. Oscar Naviliat-Cuncic LPC-Caen (IN2P3/CNRS-ENSI) and Université de Caen Basse-Normandie. context and plan. describe some searches for signatures of NP in weak decays, specifically sensitive to P and/or T violation.

ray-gilliam
Télécharger la présentation

P and T violating correlation in muon and beta decays

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. P and T violating correlationin muon and beta decays Oscar Naviliat-Cuncic LPC-Caen (IN2P3/CNRS-ENSI) and Université de Caen Basse-Normandie

  2. context and plan describe some searches for signatures of NP in weak decays, specifically sensitive to P and/or T violation • CP-even, P-odd correlation (muon decay) • CP-odd, P-odd correlation (neutron decay)

  3. 1. The longitudinal e+ polarizationin polarized muon decay (initially motivated by the sensitivity of P -/P + measurements in nuclear beta decay)

  4. nm ne GF m e • beyond SM: include all Lorentz invariants • decay amplitude parametrized by • in the SM (all others are zero) m-decay phenomenology 4-fermions point-like interaction: (W.Fetscher PLB 173(86)102) g = S,V,T interactions e,m = L,R helicity of charged fermions

  5. parameterization of observables Observables commonly expressed in terms of Michel parameters: status the parameter x’’ enters the angular/energy dependence of PL by the combination: (present PDG value)

  6. q PL Pm e+ m+ longitudinal e+ polarization sensitivity vs x and q for Pm = 0.95 x = Ee /E0 reduced positron energy → measure near q = p and x = 1 relation to exotic couplings

  7. relative measurement compare e+ polarizations between polarized and unpolarized muons: avoids the precise determination of the polarimeter analyzing power sensitivity coefficient: r -, r 0: rates of positrons incident on the polarimeter for polarized and unpolarized muon decays (measured) implementation • produce polarized muons • maintain/destroy the muon polarization • select backward emitted positrons near the end point • measure the longitudinal polarization

  8. realization pE3 area muons are naturally produced 100% polarized from pion decay at rest “surface muons” (contamineted by “cloud muons”)

  9. 28.9 MeV/c m+ > 44 MeV/c e+ Spectrometer Polarimeter Wien filter (B < 0.0004 T) monitor telescopes Al or S target experimental setup e+/m+ velocity separation N(e+)/N(m+) < 0.12 m stop rate: 3x107 s-1 at 1.6 mA

  10. muon polarization Hanle method (with two plastic telescopes) polarization vs muon momentum “surface muons” at 28.5 MeV/c: Pm = 0.94(1) use two muon stop targets: Al: Pm = 0.94 “polarized” S: Pm = 0.10 “unpolarized”

  11. 1.9T 2.7T 0.8T energy and angular selection selector tracker refocus pe = 50 MeV/c 60% transmission for Ee > 44 MeV 12 < q < 13 dump of beam positons pe = 29 MeV/c

  12. 1 2 3 2 e+ 1 z 3 d12 d23 silicon tracker determine momentum from helix geometry redundancy constraint! - 3 planes with 4 detectors each - 60x60 double SSD 1 mm pitch 300 mm thick resolution Dpe = 1.15(1) MeV/c

  13. Hodoscope WC BGO WC scintillator Vacoflux foils with opposite magnetization positron polarimeter use two processes: - Bhabha scattering - Annihilation in flight (have analyzing powers with opposite signs) BHA: Aeff ~ 0.037 AIF: Aeff ~ -0.015 (incl. fraction of polarized electrons and foil orientation) but similar FOM (luminosity) CoNiFe foils: 75x15x0.1 cm3 with 0.75mm active region to reduce Brehmstralung events

  14. hodoscope and calorimeter • 7x7 plastic scintillators (x and y) • 90x7 cm2 with single PM readout • 127 BGO crystals, 55mm diam, 20cm long • external magnetic shielding • temperture stabilized DT = ±2° • resolution DE/E = 10% at 42 MeV

  15. measuring conditions • two magnetized foils with opposite magnetizations (simultaneous) • two directions of magnetization for each foil • two orientations of the polarimeter: +45°, -45° • two analyzing processes with opposite analyzing powers (BHA, AIF) • two stop targets for polarized and unpolarized muons • measure energy dependence of the longitudinal polarization typical trigger rates: • total 15 kHz • AIF 60/s • BHA 250/s (consistent with MC simulations)

  16. cluster recognition, event reconstruction,cuts, ratios, asymmetries… • triggers defined from scintillators and BGO • SSD readout is slave • event type sorted from hits in MWPCs, Hodoscope and BGO

  17. preliminary results (X. Morelle, PhD) asymmetries of ratios under inversion of foils magnetization PRELIMINARY! x” = 1.020 ± (0.062)stat ± (…)sys (factor of 6 improvement if sys remains negligible)

  18. status • experiment did not acquired the planned statistics • no present plans to make a new run

  19. people and institutions J.Egger, N.Danneberg, J.Deusch, W.Fetscher, F.Foroughi, J.Govaerts, M.Hadri, Ch.Hilbes, K.Kirch, P.Knowles, K.Koehler, A.Kozela, J.Lang, M.Markiewicz, R.Medve, X.Morelle, O.Naviliat-Cuncic, A.Ninane, R.Prieels, L.Simons, J.Sromicki and P.Van Hove • Institut de Physique Nucléaire, UCL, Louvain-la-Neuve, Belgium • Institut für Teilchenphysik, ETH, Zurich, Switzerland • Paul Scherrer Institut, PSI, Villigen, Switzerland • Département de Physique, Uni-Fribourg, Switzerland • Laboratoire de Physique Corpusculaire, Caen, France (thanks to R.Prieels)

  20. related projects TRIUMF Weak Interaction Symmetry Test: “TWIST” http://twist.triumf.ca/~e614/experiment.html tracking of e+ from polarized muon decay goal: detemine r, d, Pmx with a relative precision at the 10-4 level prelim. results expected in 2004

  21. 2. Measurement of the R parameterin neutron decay

  22. Jn Pp e pe p the R coefficient decay rate function: • the coefficients A, R, N, … probe the dynamics • JTW parameterization: Ci , C’i(i = S, V, A, T )

  23. R and D in neutron decay D: P-even T-odd R: P-odd T-odd DFSI = 1.310-5 (10-6) RFSI = 910-4 (510-6)

  24. Jn Pp e pe p measuring principle highest sensitivity to R for mutually perpendicular vectors Mott scattering

  25. experimental concept (J. Sromicki NIM A 440 (2000) 609) • produce polarized cold neutron beam • observe neutron decay in flight • track low energy decay electrons • use large angle Mott scattering • trigger with “opposite” scintillator

  26. realization • Spallation neutron source SINQ • target: “zircalloy” (Zr-Pb) • D2O moderator • liquid D2 vessel cold source FUNSPIN area

  27. polarized cold neutron beam • A. Schebetov et al. • NIM A 497 (2003) 479 • J. Zejma et al. • to be submitted to NIM A • flux: 2×108 /(cm2·s·mA) • ‹P› ≈ 97 % FUNSPIN area

  28. scheme of the experimental setup

  29. photo gallery MWPC HODOSCOPE DECAY REGION

  30. results from commissioning run • Energy spectra of electrons from single track events S/B > 3:1

  31. Mott scattering analysis cross section and Sherman function in Au … Pb is better (higher Z) and cheaper! - 1mm evaporated Pb layer on 2mm mylar - 2 or 3 bands for 50x50cm2 active surface

  32. a “golden event”

  33. vertex reconstruction (A. Kozela) positions of Pb scattering foils

  34. vertex signals • after vertex reconstruction with VETO condition on • the hodoscope at the vertex side S/B > 10:1 • inclusion of hot spots of the setup geometry is in • progress to further improve S/B

  35. comments 2. precision goal:R =510-3 1. polarimetry control • “up-down” asymmetry probes R • “left-right” asymmetry probes N the simultaneous measurement of N ≠ 0 provides a control of the polarimeter Exclusion plot on S and T frombeta decay experiments (±1s)

  36. interpretation P. Herczeg 2004: constraints on |Im(aLS)| from Rp are hard to beat with Rn Rn at 10-2 would require fine-tuned cancellations → make life less exciting… … important considerations for new generation experiments

  37. status and outlook • The Mott polarimeter for the measurement of R in neutron decay • is complete. • The commissioning run in autumn 2003 was successful. • The first data taking run starts next month. • The measurement of R with an accuracy of 10-2 is expected to be achieved within one year. • The sensitivity goal of 510-3 seems feasible; • will be checked after first complete data analysis.

  38. people, institutions, support G.Ban, M.Beck, A.Bialek, K.Bodek, T.Brys, A.Czarnecki, W.Fetscher, P.Gorel, K.Kirch, St.Kistryn, A.Kozela, A.Lindroth, O.Naviliat-Cuncic, J.Pulut, A.Serebrov, N.Severijns, E.Stephan and J.Zejma • Laboratoire de Physique Corpusculaire, Caen • Institute of Physics, Jegellonian University, Cracow • Institute of Nuclear Physics, Cracow • University of Alberta, Edmonton • St Petersburg Nuclear Physics Institute, Gatchina • University of Silesia, Katowice • Catholic University Leuven, Leuven • Paul Scherrer Institute, Villigen • Institute of Particle Physics, ETH Zurich support for PhD students (thanks to K. Bodek and P. Gorel)

More Related