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Study of b - n correlations with LPCTrap

Laboratoire de Physique Corpusculaire - Caen. Study of b - n correlations with LPCTrap. Dominique Durand LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen, France On behalf of the LPCTrap collaboration. EXON 2012. Outline. Motivation Physics case and m easurement principle

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Study of b - n correlations with LPCTrap

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  1. Laboratoire de Physique Corpusculaire - Caen Study of b-ncorrelations with LPCTrap Dominique Durand LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen, France On behalf of the LPCTrap collaboration

  2. EXON 2012 Outline • Motivation • Physics case and measurement principle • Experiments and results • Summary

  3. STANDARD MODEL of Particle Physics is a very powerful and predictive model (recent Higgs probable discovery) but it is probably not complete • Questions: nmass hierarchy, strong CP problem, matter/anti-matter, dark energy/matter • Test at low energy: • high precision measurements • search for very small deviations from SM predictions • EDM’s, correlations (A, a, b, B, D, R, ….), g-2… • search for very rare (presumably forbidden) processes • neutrinoless double bdecay, proton decay, … • High precision and high energy experiments are complementary

  4. bdecay and the weak interaction 2+ Measurement of the beta neutrino angular correlation parameter abn + • observables linked to  are sensitive to abn • Recoil Ion (RI) momentum spectrum b- b decay rate: E: energy and velocity of the beta particle Wo(E): phase space distribution as given by the Fermi theory of beta decay : angle between the antineutrino and beta particle

  5. bdecay, Vector -Axial, abn • SM Test  pure vector axial interaction theory study through b decay • abn is a function of the coupling constants • Gamow-Teller  Axial / Tensor • Fermi  Vector / Scalar CL : 95.5% • Exotic currents (beyond SM) tensor/scalar abn(CV, CS, CA, CT, MF, MGT) : b-nangularcorrelationparameter Pure F : aF (CV, CS) = +1 (SM, CS = 0) Pure GT : aGT (CA, CT) = -1/3 (SM, CT = 0) Goal: new physics or Improve constraints on couplings - angular correlation coefficient measurement a with relative statistical uncertainty less than 0.5% deviation from abn=-1/3 or 1 (SM) might reveal existence ofnew particles: leptoquark bosons …

  6. CKM matrix and abn For mirror transitions : r=GT/F & abn(r) = (1-r ²/3)/(1+r ²) Proceedings of CKM2010, the 6th International Workshop on the CKM Unitarity Triangle. T Sparado , A. Young • Mirror transitions : • Analysis of available data (5 nuclei) • competitivewithneutron/pion decay • Valuablealternative to 0+->0+ transitions • Several parameters to be measured: T1/2, BR, Q, r • and to be computed (corrections) O. NaviliatCuncic et al., PRL102 (2009)

  7. How to measure abn • observables linked to  are sensitive to abn • Recoil Ion (RI) momentum spectrum • Ion trapping techniques are universal (several nuclei) • - LPCTrap:abndeduced from RI ToF measurement • - ions almost at rest and well localized • - open configuration, few dead zones • Precision measurement Dabn/ abn <1%: • very difficult experiment: • systematic effects such as the • RF field  ToF spectrum deformation • «shake-off»ionization probability required Transparent Paul Trap

  8. Nuclei of interest V-A 6He+ pure GT transition, tensorcoupling abn=-1/3 High Q value, RI (6Li) up to 1.4 keV T1/2 high rate and efficient transmission to the trap Vud and V-A 35Ar+, Mirror 35Cln+ scalarcoupling, mixed transition corrections abn=0.904 High Q value but heavier ion RI (35Cl) up to 450 eV T1/2 high rate and efficient transmission to the trap Other candidates: 19Ne, 37K, 39Ca

  9. LIRAT LIRAT Production target ECR source LPCtrap@GANIL/SPIRAL1 • Beam characteristics : • 10-30 keV, 80 p mm mrad • rate : ~ 108 ions/s LPCTrap Paul trap Effective potential 1-2 V Beam-handling SPIRAL 6He beam 10 keV DE ~ 20eV

  10. Beam line preparation 1meter Beam6He+ • RFQCB: • High-voltage platform • Buffer-gas cooling technique: H2 or He • Ion bunches • Continuous voltage: longitudinal confinement • RF field: radial confinement • Cycle period: 200ms (accumulation) ~5 1046He+/s trapped ions • Total efficiency: ~2.5 10-4 ~2 1086He+/s • Ions bunches • Cycle period: 200ms • (accumulation)

  11. Detectors and trap 6He+ bunch MCP with delay line anode • Beta position • Eβ • MCP •  telescope Ion trap Recoils b- Time of flight: Free flight tube Charge state separation: Free flight tube MCPPSD Post-acceleration Silicon + plastic scintillator + PMT • Detection in coincidenceof recoil ion (RI) and b particle • ToF measurement (b detection: START, RI detection: STOP) • Post-acceleration between the two collimators (Installed 2009) • 50 cm free flight tube  charge state separation(identified by ToF)

  12. Recoil ion detector design Focusing electrode Collimator Grounded collimator • Acceleration electrode Grid MCPPSD • Focusing electrode to collect recoil ions with maximal efficiency • Geometry design and bias voltages estimation with “SIMION” software • Successfully tested during four days in November 2010 LPCTrap : simultaneous measurement of abnand the «shake-off»probability

  13. 6He+ :experimental results (2006-2010) 1963 Vise (coincidence) 1963 Pshake-off = 0.02339(35)stat(07)syst PRL (Couratin et al.) 108 (2012) 243201 2010 Result: abn= - 0.3335(73)stat(75)syst SM value = -1/3 PRL (Fléchard et al.) 38 (2011) 055101 6He+ Pure GT Limit on Tensor 105 events • ( Dabn/abn ) stat~2% Improvestatisticsalsoimprovesystematicuncertainties - effect of ion cloudtemperature - effect of b back-scattering

  14. 6He+ : experimental results (2006-2010), shake off Experiment: ~4 days,Intensity ~108 pps, ~1.2 106 «true» coincidences • Complete Monte-Carlo simulation w/all systematic effects: RF fields, ion cloud characteristics, detectors response functions... • Experimental spectrum fit w/ Pshake-off as free parameter assuming abn = -1/3 Li2+ Li3+ Pshake-off = 0.02339(35)stat(07)syst PRL (Couratin et al.) 108 (2012) 243201 “exceptional research” from APS • High precision: DPshake-off=3.6 10-4 • Excellent agreement: theoretical value • of 0.0233 Data analysis still in progress GOAL: abn estimation Preliminary: agreement w/ SM value Relative stat. uncertainty < 0.5%

  15. 35Ar+ : experiments results (2011-2012) 35Cl charge state distribution 3 - 4 10735Ar+/s incoming beam with ~2.5 x 108contaminants/s 2 - 3 x 104 trapped 35Ar+ ions (every 200 ms) • 2011commissioningrun 2 days • 2012 8 daysrun @GANIL/LIRAT • expected final uncertainty Dabn(stat) < 0.002 • full analysis is underway

  16. PREMS: re-submitted to the ANR Implantation tape station Multi Reflection Time Of Flight Mass Spectrometer (MR-TOF-MS needed for new beams) Small RFQ ("rebuncher") Main RFQ taccu ~ 1-10ms taccu ~ 100ms New chamber At least a factor ~ 10 in statistics

  17. Summary & future plans • Precision measurement of the b-decay of exotic nuclei can probe • the weak interaction part of the Standard Model: abn V-A, Vud • LPCTrap is a universal tool that measures accurately abnfor • several nuclei of interest and provide shake-off probabilities • Near future: Ne19 experiment accepted by GANIL PAC • Future: new beams and new apparatus • - PREMS: renewal of the experimental set-up on the LIRAT beam line • - new exotic beams and facilities are needed  S3/DESIR@SPIRAL2

  18. LPC CAEN : Claire Couratin (PhD-2013) Dominique Durand Xavier Fabian (PhD-2015) Xavier Fléchard Etienne Liénard François Mauger Oscar Naviliat-Cuncic Gilles Quéméner Philippe Velten (PhD-2011) GANIL:Pierre Delahaye Bertrand Jacquot Jean-Charles Thomas CIMAP:Alain Méry KUL Leuven: Martin Breitenfeldt Simon Van Gorp TomikaPorobic NathalSeverijns and the LPC technicalstaff alsothanks to the GANIL beamoperators

  19. EXON 2012 WITCH ISOLDE CERN Measureabnwith a precisionbetter than 0,5 % ISOLDE+ REXTRAP (beam handling) Penningtraps Retardation spectrometer Main isotope 35 Ar + Scalarsearches

  20. EXON 2012 WITCH ISOLDE CERN • After solving all kind of problems • Local penning, mechanical… • Data Obtained in 2011 with 35Ar • abn= 1.12 (33)stat • SM value of a =0.9004(16). • Still a lot to measure and simulate • Next run Oct 2012

  21. EXON 2012 We are not alone… From N. Severjins, KUL

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