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Doctoral Dissertation Announcement
Candidate: Scott T. Marley
Doctor of Philosophy
Title: Study of the Structure of 9C via Single Neutron Transfer
Dr. Alan Wuosmaa, Chair
Dr. Dean Halderson
Dr. Michael Famiano
Dr. K. Ernst Rehm
Date: Thursday, May 17, 2012 12:30 p.m. to 3:30 p.m.
2202 Everett Tower
This thesis describes a study of the nucleus 9C, produced in the single-neutron transfer reaction d(10C,t)9C using a radioactive 10C beam. The structure of the neutron-deficient nucleus 9C is poorly known. Only a few excited states have been observed and no information exists of their single-particle characteristics. The measured ground-state magnetic dipole moment of 9C is anomalously small and could imply large contributions from sd-shell orbitals in the ground-state wave function. The positions of the 9C excited states and their single-particle properties are vital to furthering the accuracy of ab initio nuclear models which have excelled in modeling light nuclear systems in the p-shell. To probe the structure of 9C the neutron-removing reaction 10C(d,t)9C, in inverse kinematics, was performed at the ATLAS facility at Argonne National Laboratory.
An “in-flight” radioactive 10C beam was developed at ATLAS through the p(10B,10C)n reaction using a 185-MeV 10B beam incident on a cryogenic hydrogen (H2) gas cell. The resulting 171-MeV 10C beam had an average intensity of 2.2×104 ions per second and was placed on a 657 μg/cm2 deuterated polyethylene (CD2)n target. Tritons were detected and identified in an array of annular double-sided silicon detectors (DSSDs) covering laboratory angles between 7° and 42° . Heavy recoils from particle-bound and unbound states were detected in a set of forward-angle silicon detectors in a ΔE-E configuration.
The 9C ground state transition was unambiguously identified in the detector system and angular-distribution data were extracted. The neutron-pickup spectroscopic factor was deduced from a comparison of distorted-wave Born approximation (DWBA) calculations using both traditional bound-state form factors and those derived from ab initio calculations. The comparison between the two results assesses the reliability of applying ab initio calculations to transfer reaction theory and provides insight into the low-lying structure of 9C.