Parity Non-Conservation in the  Decay of Polarized 17/2 - Isomers in 93 Tc

1. Parity Non-Conservation in the  Decay of Polarized 17/2- Isomers in 93Tc B.S. Nara Singh1, M. Hass1, G. Goldring1, D. Ackerman2, J. Gerl2, F.P. Hessberger2, S. Hofmann2, P. Kuusiniemi2, H. Schaffner2, B. Sulignano2, B. A. Brown 1. Weizmann Institute of Science, ISRAEL, 2. GSI, GERMANY, 3.NSCL, Michigan, USA. PNC in Nuclei Exp. Method Triple Ratios, A Independent of Gamma efficiency • Non-leptonic, Non-strangeness changing. • Probes HWeak of Nuclear Hamitonian. • Etablishes IS, IV and IT strengths. • Parity mixing in Nuclear levels: can be Observed through their Eletro Magnetic and Strong decays. • Polarization: Tilted Foil Technique. • 0-180° Asymmetry (A) in the M2/E3() -decay due to E2 Component • Previous work at SHIP-GSI, RMS-LNL: M. Hass et al., PLB 371, 25 Beam current fluctuation and experimental artifacts Only Few Cases 45Sc 1mg/cm2 SHIP, GSI Results 19F~380(100) meV 21Ne30 meV 18F90 meV 93Tc ~ 0.59 (31) meV 180Hf~1.0(0.1)  eV pl = 0.15 known from QP interaction measurements M. Hass et al., PRC 43, 2140. 93Tc High Spin Isomer 16 foils, @70º 15-15 g/cm2 PLB, 371, 25: A = 8.4(2.7). 10-4 , <Hpnc>=0.59(19)(25) meV Setup • Parity doublet at 300 eV Proximity. • N=50, Reasonable nuclear Structure Calculations within Shell model. • Establishes IT component and complementary to the studies in light nuclei. • Unique case For non-zero PNC. Isomer Beam Present+PLB, 371, 25: A = 4.8 (2.1). 10-4 , <Hpnc>=0.34(14)(25) meV • 45Sc(52Cr, 2p2n)93Tc Elab(93Tc) = 65 MeV • SHIP: Tranfers to Focal Plane Area • E-degrader 0.2 mg/cm2 avoids foil stack damage. • SHIP optimization: PSD at the Entrance of Foils and gamma counting. • Acquisition system upgraded to handle high counting rates. • VME-CPU and Labview control. • Counts in 751 keV line, 6M per crystal Theory:1p1/2-0g9/2 withIV strength correction by an empirical factor of 0.15±0.15. <Hpnc> = - 0.2 to 1 meV