The gamma decay of high spin states of39K

Abstract

Abstract. The decays of high spin states in 39K, populated in the reactions 28Si (160, ~p) and 25Mg(160, pn), have been measured for oxygen beam energies between 30 and 50 MeV.Using the recoil distance Doppler shift method, mean lifetimes were determined for the states at 2814keV (r=62+5 ps), 3597 (51+4ps), 3943 (ll.4+l.6ps), 4830 (19+5 ps), 5715 (<3ps), 6473 (11.9+0.5 ps), and 8028 (10<~<50ps), respectively. Possible spin assignments and transition rates for these levels will be discussed.

Lifetimes of high-spin levels in39Ar

“…As the 993 keV 5.17--+4. 18 MeV transition in 36Ar originating from the reaction 25Mg(160, c~n), overlaps with the 5.544-*4.54 MeV transition in 39Ar, the 26Mg(180, en)39Ar reaction was mainly employed for measuring the lifetimes. The 50 nA l sO beam from the HVEC tandem accelerator at the University of K61n (at energies of 45 and 55 MeV) bombarded a 300 lag/cm 2 enriched 26Mg target (99.4~o).…”

“…On the basis of these wave functions, the 5.54~4.54 MeV transition should vanish, in contrast to the experimental result of B(M1)>0.058g 2. Furthermore, the 4.54~3.99 MeV transition is a spin flip within the multiplet which is given by [20] 3.94 MeV 11/2-and 2.81 MeV 7/2-states in the respective core-plus-proton system 39K [18] where the weak-coupling picture holds nicely as illustrated in Figure 2. (Similar deviations as in 39Ar have been previously observed in 33p and in 35C1.)…”

“…Data taken from [18], except for 3SAr [17] and 39Ar is equivalent to a fT/z ~d3/z transition which requires M2 as lowest multipolarity.…”