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Isospin Purity and Lifetime Measurements in A=38, T=1 Nuclei via 38K Study

This study explores the isospin purity and lifetime measurements of nuclei with A=38 and T=1, focusing on 38K. We systematically analyze B(E2) values and transition matrix elements between the T=1 states, using experimental setups involving various detectors and configurations. The findings suggest intriguing discrepancies in expected matrix elements for Tz=0, Tz=1, and Tz=-1. Additionally, the significance of branching ratios for the 2+ states is discussed. Our results contribute to a better understanding of nuclear structure and behavior in isospin triplets.

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Isospin Purity and Lifetime Measurements in A=38, T=1 Nuclei via 38K Study

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  1. Isospin purity in the A=38, T=1 nuclei tested via lifetime measurements in 38K. F. M. Prados Estevez, A.M.Bruce, M.J.Taylor1 University of Brighton H.Amro, C.W.Beausang2, R.F.Casten, J.J.Ressler3 Yale University C.J.Barton1 Daresbury Laboratory C.Chandler, G.Hammond1 University of Keele Current address: 1 University of York 2: University of Richmond 3: Simon Fraser University

  2. Systematics of B(E2) values and matrix elements between 2+ (T=1) and 0+ (T=1) states in T=1 isospin triplets. 2+2(T=1) 2+1(T=1) A=22: Ne, Na, Mg A=26: Mg, Al, Si A=30: Si, P, S A=34: S, Cl, Ar A=38: Ar, K, Ca A=42: Ca, Sc, Ti 0+ (T=1)

  3. Systematics of N=Z=odd nuclei 2+1 -> 0+ 2+2 -> 0+

  4. 2+ T=1 1+ T=0 38K Is it the right 2+ state?The energy agrees with the neighbours. 2403 keV 2167 keV 2206 keV 1+ T=0 0+ T=1 3+ T=0 38Ca 38Ar

  5. Comparison across the T=1 triplet 2 * M (Tz=0) M (Tz=1) + M(Tz=-1) Data suggests all three values are low but, in fact, it’s hiding something: (for Tz=0 nucleus)

  6. The variation of M against Tz Tz defined as (N-Z)/2 38Ar 38Ca 38K

  7. Clearly something of interest in 38K: 7+ T=0 22ms Fusion-evap not possible: 3 previous measurements 40Ca(d,a) 76 (50) fs 39K (3He,a) 54 (25) fs 40Ca(d,a) 90 (25) fs Weighted average t = 72 (16) fs 2403 keV 2+ T=1 1+ T=0 2272 keV 1944 keV 1+ T=0 0+ T=1 3+ T=0 38K

  8. Experimental set-up. Target: 220 g/cm2 Ca on a Ni backing of 1mg/cm2. Flash of gold on front face. d a-particles

  9. Experimental set up, 8 solar cells ~ 2cm from the target.Angles subtended 1430-1660.8 clovers (900, 1400) and 2 LEPS (900).

  10. Angular behaviour of the 1944 keV transition.

  11. F(t) value from the 1944 keV transition 0.868 (36)

  12. Data fitted with a modified version of Dechist. Fitted t values for the 2403 keV level: 114 (26) fs 159 (30) fs

  13. The variation of M against Tz Provisional data point added for 38K 38Ar 38Ca

  14. 2403 keV 2+ T=1 1+ T=0 2272 keV 1944 keV 38K Branching ratio of the 2+ state is also important: Ratio from previous work is: 2272 keV: 6.4 1944 keV: 100 but 1944 is clearly a doublet which we are currently trying to sort out, this will increase the relative strength of the 2272 keV transition. A factor of 2 would take the matrix element to 7.5. 1+ T=0 0+ T=1 3+ T=0

  15. Shell model calculations B.A.Brown et al Phys Rev C26(1982)2247 sd model space Chung-Wildenthal wave functions

  16. Thanks to all Yale staff for their efforts during the experiment.

  17. Dedication Dave Warner 1950-2005

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