parity non-conservation in the decay of polarized 17/2 - isomers in 93 tc
DESCRIPTION
Parity Non-Conservation in the Decay of Polarized 17/2 - Isomers in 93 Tc. B.S. Nara Singh 1 , M. Hass 1 , G. Goldring 1 , D. Ackerman 2 , J. Gerl 2 , F.P. Hessberger 2 , S. Hofmann 2 , P. Kuusiniemi 2 , H. Schaffner 2 , B. Sulignano 2 , B. A. Brown. - PowerPoint PPT PresentationTRANSCRIPT
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.
• 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.
PNC in Nuclei
Only Few Cases19F ~380(100) meV
21Ne 30 meV
18F 90 meV
93Tc High Spin Isomer
• 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.
Exp. Method
• 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.
45Sc 1mg/cm2
16 foils, @70º15-15 g/cm2
Independent of Gamma efficiency
Results
A
A
W
W
llrr
lrrlDR
1
1
)0(
)(
Beam current fluctuation and experimental artifacts
)751(
)()(
iDR
iDRiTR
)751(1
)751(1
TR
TRA
pl = 0.15 known from QP interaction measurements M. Hass et al., PRC 43, 2140.
meVQp
A
lpncH
1
||)28(91|
2
17||
2
17|
Triple Ratios, A
SHIP, GSI
• 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
93Tc ~ 0.59 (31) meV
180Hf~1.0(0.1) eV
Isomer Beam
• Acquisition system upgraded to handle high counting rates.
• VME-CPU and Labview control.• Counts in 751 keV line, 6M per crystal
A
PLB, 371, 25:
A = 8.4(2.7). 10-4 , <Hpnc>=0.59(19)(25) meV
Present+PLB, 371, 25:
A = 4.8 (2.1). 10-4 , <Hpnc>=0.34(14)(25) meV
Theory: 1p1/2-0g9/2 with IV strength correction by an empirical factor of 0.15±0.15.
<Hpnc> = - 0.2 to 1 meV
Setup