1 Beta Neutrino Correlation and T-Violation Experiment in Nuclear Beta Decay Rikkyo Univ. Jiro Murata Collaboration Rikkyo Univ. / RIKEN Asahi ANL / Titech Asahi Lab./KEK J. Murata, H. Kawamura, K. Narita, T. Suehiro, T. Shimoyama, T. Toyoda K. Asahi, D. Kameda, H. Ueno, A. Yoshimi M. Uchida, D. Nagae, K. Shimada N. Imai, K. Hirayama Beta Neutrino Correlation using Recoil Measurement from free slow radioactive nuclei at RIKEN-RIBF (RIAB / SlowRI) Beta Transverse Polarization Measurement Beta Transverse Polarization Measurement from stopped polarized radioactive nuclei from stopped polarized radioactive nuclei at KEK-TRIAC / RIKEN-RIBF

2 Unique Slow / Stopped RI Facilities at RIBF Noble Gas Stopper RI Beam ~ 100MeV/u Supersonic Gas Jet Cold RI Atomic Beam ~ 400 m/sec RI Beam Gas Catcher + Gas Jet Production System RIAB for Magnetic Moment Study using Atomic Beam Method SLOWRI Facility for Atomic Physics Beta Decay in Vacuum Recoil Measurement NO EM Field Yoshimi (RIKEN), this conf. Wada (RIKEN) et. al.

3 Experimental Setup for Beta Neutrino Correlation measurement w/o using Ion Traps Recoil Ion Detector Static Electric Field Acceleration Static Electric Field Acceleration 2d Position Sensitive MCP 2d Position Sensitive MCP Electron Tracking Chamber Electron Momentum Measurement Electron Momentum Measurement + Vertex Determination R&D of Slow RI Production 2008 ~ ???

4 Measurement using Slow RI Recoil Measurement P beta P neutrino P recoil Test of V-A interaction a=1 (Fermi), -1/3 (GT) ? Scaler / Tensor Int. exists ? Scaler / Tensor Int. exists ? precision ~ 10 ^ -3 |Cs/Cv|<8% (Fermi) |C T /C A |<13% (GT) Beta Decay Electron Measurement P beta Transverse Polarization P recoil PSI ’03 8Li exp. Angular Distribution T-Violating TRANSVERSE polarization R=0 or NOT ? PSI ’05 muon exp. PSI nTRV exp. ?

5 Stopped RI Facility at KEK-TRIAC 2005 Hirayama et. al. (KEK) Unpol 8Li Beam (178keV/u) ~ % polarization Tilted Foil : 10ug/cm^2 Carbon x 70deg. up to 10% ? Polarized Low Energy 8Li beam is available !

6 R-Correlation Measurement Transverse pol. of electron from pol. Nuclei Mott Scattering ~ 10mg/cm2 ( ~micron) Systematic Error Pol. Exists ~ 50% max. Backward scatt. ~ 10^-3 ~ -4 ~ 10^-3 ~ -4 max. at 110deg.

7 Experimental Setup for R-Measurement Projectile RIPS Tilted TRIAC, KEK-JAERI Angular Resolution < 1 deg. Full Backward Solid Angle Polarized RI in Solid Stopper like beta-NMR Maximum Mott Sensitivity Drift Chamber : as Polarimeter

8 Advantages of the New Points A(q) Changing Counter Foil Tracking Scatt. Angle Measurement U/D ratio Slits Fake Events U/D Acceptance Changing Changing Large Acceptance Select Scattering Events Independent on Decay Asymmetry Changing Foil No Slits Foil Activation Off Foil Scatt. Tracking Tracking

9 Background Rate in Counter Experiment Test RIKEN-RIPS Beam Line Qbeta- = 8.0MeV Polarized Secondary Beam : 31Al 95MeV/u 9um Gold Foil electron veto stop start TDC (start – stop) Signal / Backgound ~ 10% Foil ON/OFF No Accidental Tracking Device -> Reject Ghost Events stopper ON OFF

10 DC Polarimeter 64ch ASD preamp x 2 + VME AMU-TDC x 2 XX’ UU’ VV’ Planer DC 104 Anode Sense 20um 50g x 104 Field 100um 150g x 110 Cathode 100um 150g x 413 Total 627 Wires Sense - Field Pitch = 10mm Sense - Cathode Gap = 10mm XX’(1/2cell off) x 40 UU’(15.9deg.) x 32 VV’(-15.9deg.) x 32 Cathode(90deg.) Point Source Tracks ~ 200 um res.

11 Track Reconstruction for Scattered Events 90Sr/Y beta source (Qb=2.283MeV) Lead Foil Source DC start Reconstructed V-Tracks (real data)

12 Configuration Dependence on Acceptance Drift Chamber Polarimeter : Limited Solid Angle, not suitable for High Rate : Limited Solid Angle, not suitable for High Rate Present Design PSI 8Li Exp. type 10MeV 0.9uA 7Li(d,p)8Li 99.9% 7Li target, GBq B = 7mT, Pol = Relaxation time > 20sec Lead foil analyzer 35mg/cm2 Plastic Polarimeter GOAL : Cylindrical MWPC Polarimeter : Large Solid Angle, good for High Rate : Large Solid Angle, good for High Rate

13 Monte-Carlo Estimation of the Acceptance 0.84% 9.6% on foil Drift Chamber Polarimeter Plastic Polarimeter Over 90deg ~ 10micron Gold Foil Total Abs. Acc. 7.5 x 10^-5 (75cps from 1MBq) Around peak FOM

14 Expected Sensitivity PSI ’03: 700MBq, pol 10% TRIAC: 1-10MBq. pol 10% RIBF : GBq. pol ??? Fitting Simulated Asymmetry

15 Final State Interaction Systematic Evaluation of the FSI 1.Nuclear dep. 2.Beta energy dep. Experimental Sensitivity reaching Electromagnetic Final State Interaction Contribution from pure V-A 1. FSI is BG, for T-Violation Physics Extract True T-Violation 2. Study of FSI Physics Heavy Isotope Measurement Nuclear Size, Structure effect, etc. Possible way is.. AND/OR Suitable for RI Beam Factory

16 Summary Status 1.Drift Chamber Polarimeter has been built. 2.Polarized 8Li is now available at TRIAC. 3.Study of physics sensitivity is completed. 4.Stopper R&D is undergoing. 5.First test experiment using DC- polarimeter & polarized beam will be performed in early 2007 Plan 1.Perform 1 st step experiment at TRIAC. 2.Upgrade. Beam Intensity: 10^5 to 10^7 design value Beam Intensity: 10^5 to 10^7 design value Polarization: 5% to 10% using tilted foil Polarization: 5% to 10% using tilted foil 10% to 20% or more using optical pumping ? 10% to 20% or more using optical pumping ? 3.Utilize 10^10 RIBF Optical Pumping in Solid Optical Pumping in Solid Cylindrical Proportional Counter Polarimeter Cylindrical Proportional Counter Polarimeter