Intruder configurations of excited states in the neutron-rich isotopes P 33 and P 34

Excited states in the neutron-rich isotopes P-33 and P-34 were populated by the O-18 + O-18 fusion-evaporation reaction at E-lab = 24 MeV. The Gammasphere array was used along with the Microball particle detector array to detect gamma transitions in coincidence with the charged particles emitted from the compound nucleus S-36. The use of Microball enabled the selection of the proton emission channel. It also helped in determining the exact position and energy of the emitted proton; this was later employed in kinematic Doppler corrections. 16 new transitions and 13 new states were observed in P-33 and 21 gamma rays and 20 energy levels were observed in P-34 for the first time. The nearly 4 pi geometry of Gammasphere allowed the measurement of gamma-ray angular distributions leading to spin assignments for many states. The experimental observations for both isotopes were interpreted with the help of shell-model calculations using the (0+1)(h) over bar omega PSDPF interaction. The calculations accounted for both the 0p-0h and 1p-1h states reasonably well and indicated that 2p-2h excitations might dominate the higher-spin configurations in both P-33 and P-34.