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Single particle structure of high spin states in [sup 144]Pm and [sup 145]Pm

Thesis/Dissertation ·
OSTI ID:5705275

The level structures of [sub 61][sup 144]Pm[sub 83] and [sub 61][sup 144]Pm[sub 84] were investigated using heavy-ion reactions and the techniques of [gamma]-ray and electron spectroscopy as well as transfer reactions. Decay schemes were constructed from prompt [gamma]-[gamma]-coincidence, delayed [gamma]-[gamma]-coincidence, excitation function, angular distribution and conversion electron measurements of the [sup 19]F + [sup 130]Te fusion-evaporated reaction at beam energies between 70 and 95 MeV. A total of 53 new transitions and 31 new levels were placed in [sup 144]Pm. The level scheme extends to spin J = 20 [h bar] and an excitation energy of 5.8MeV. Transitions feeding the 841 keV (J[sup [pi]] = 9[sup +]) isomeric state were observed for the first time. The reduced B(E3) transition strength for the 669 keV (9[sup +] [yields] 6[sup [minus]]) transition deexciting this state was determined to be 3.2(7) Weisskopf units, supporting the interpretation of the 9[sup +] level as a [[pi]1h[sub 11/2] [circle times] [nu]2f[sub 7/2]] non-collective state. Nineteen new levels connected by 32 new transitions extended the decay scheme of [sup 145]Pm up to a tentative spin of (33/2)[h bar] and an excitation energy of 4.7 MeV. The 11/2[sup [minus]] isomeric state at 795 keV was identified as a single h[sub 11/2] proton state in the [sup 144]Nd ([sup 7]Li, [sup 6]He) stripping reaction at a beam energy of 34 MeV. A measurement of the B(E3) reduced transition strength (7.8(18) Weisskopf units) of the 795 keV (11/2[sup [minus]] [yields] 5/2[sup +][sub g.s]) transition deexciting this state supports this interpretation. A weak coupling model can explain the structure of the deduced decay scheme up to an excitation energy of 2.5 MeV. The spectroscopy of [sup 144]Pm and [sup 145]Pm is discussed in terms of couplings of single-particle states to a [sup 146]Gd core using empirical shell-model calculations. Good agreement with the experimental results is obtained.

Research Organization:
Florida State Univ., Tallahassee, FL (United States)
OSTI ID:
5705275
Country of Publication:
United States
Language:
English

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