Radiative decays of unbound high-spin states in 24Mg (II)

Abstract Known negative-parity levels at 11.59(5 − ), 12.44 (7 − ), 13.06(5 − ), and 13.76(5 − ) MeV in 24 Mg have been studied as resonances in the 20 Ne(α, γ) 24 Mg reaction, and their radiative and α-particle decay widths deduced. The 12.44 MeV level is identified as the 7 − member of a K π = 0 − band by virtue of a strongly enhanced E2 γ-ray transition to the 10.03 MeV 5 − level. The 13.06 MeV level exhibits a strongly enhanced γ-ray transition to a probable 3 − level at 10.33 MeV, indicating the existence of a new negative-parity rotational band in 24 Mg. Known 4 + levels at 12.05, 12.12, 12.16, 12.51 and 13.05 MeV have also been studied as 20 Ne(α, γ) 24 Mg resonances in a search for the 4 + member of a proposed excited K π = 0 + band via an enhanced E2 transition to the 8.65 MeV 2 + level. No such transition was observed, but the 12.05 MeV level was identified as the second 4 + T = 1 level in 24 Mg. In addition, γ-ray decay schemes and angular distributions provided the following information on the spins and parities of three sharp resonances near 14 MeV in 24 Mg: 14.10, (2, 4) + ; 14.146, 4 + (3 − , 5 − ) and 14.32, 4 + .