Intruder configurations of excited states in the neutron-rich isotopes P33 and P34

Excited states in the neutron-rich isotopes ³³P and ³⁴P were populated by the ¹⁸O+¹⁸O fusion-evaporation reaction at E_lab = 24 MeV. The Gammasphere array was used along with the Microball particle detector array to detect γ transitions in coincidence with the charged particles emitted from the compound nucleus ³⁶S. 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 ³³P and 21 γ rays and 20 energy levels were observed in ³⁴P for the first time. The nearly 4π geometry of Gammasphere allowed the measurement of γ-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) $\overline{h}$ω PSDPF interaction. Furthermore, 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 ³³P and ³⁴P.