Experimental Efforts to Study the Nuclear Structure of ³³P and ³⁸Cl and a Theoretical Endeavor to Develop an Empirical Shell-Model Interaction

In this thesis, the excited states ³³P were populated by the ¹⁸O+¹⁸O reaction at E[subscript lab]=24 MeV. The GAMMASPEHRE 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 position and energy of the emitted proton; which eventually helped in calculating more precise direction of the recoils to achieve better Doppler corrections. 16 new transitions and 13 new states were observed in ³³P for the first time. The nearly 4π geometry of GAMMASPEHRE allowed the measurement of γ-ray angular distributions leading to spin suggestions for many states. In a separate experiment conducted at the John D. Fox laboratory in Florida State University, the higher-spin structure of ³⁸Cl (N = 21) was investigated following the ²⁶Mg(¹⁴C, pn) reaction at 30 and 37 MeV. The outgoing protons were detected in an E ‒ ΔE Si telescope placed at 0° close to the target with a Ta beam stopper between the target and telescope. Multiple γ rays were detected in time coincidence with the protons using an enhanced version of the FSU γ detection array. A total of 11 new γ transitions and 6 new states were reported for the first time. DCO ratio analysis and measurement of polarization asymmetry for the emitted γ transitions were performed to assign spins and parities to a number of states. The level scheme was extended up to 8420 keV with a likely spin of 10 ħ. A new empirical shell model interaction was developed in the spsdfp model space. This FSU interaction was built by fitting to the energies of 270 experimental states from ¹³C to ⁵¹Ti. Calculations using the FSU interaction reproduced observed energy states of ³³P and ³⁸Cl rather well, including other spectroscopic properties. The interaction has been used to predict the intruder states of other sd-shell nuclei, along with the configurations of the nuclei belong to the Island of Inversion region of the nuclear landscape.