Continuum Nuclear Structure via
Abstract
Nuclear spectra are generally well-understood for excitation energies below the particle-emission threshold. Above this threshold, excited states decay preferentially by emission of nucleons or nucleon clusters. These resonant excitations are short-lived, producing continuum spectra of overlapping states accompanied by non-resonant, probe -dependent background processes. The resonant excitations' properties are difficult to deduce from these spectra. Many important advances in nuclear physics require understanding of such excitations. (e,e^' X) coincidence experiments have established the utility of angular correlation measurements of particle (X) emitted by decaying resonances for continuum studies. However, electron-induced reactions excite only a subset of the total nuclear response. Hadronic probes are necessary for a complete study. This dissertation describes a (p,p^' X) coincidence experiment, the first at intermediate energies where microscopic theories apply. The reaction's utility was investigated and applied to ^{12 }C. The experiment was performed using a 156 MeV polarized proton beam. A magnetic spectrometer was used to detect scattered protons. An array of eight silicon-detector telescopes was constructed and used to measure the angular correlation of charged particles (X). Inclusive (p,p ^') and exclusive (p,p ^' X) data were acquired simultaneously. The momentum transfer range (0.6<= q<= 1.2 fm^{-1}) was covered in three spectrometer angle settings. The excitation energy range spanned the region from sharp states to quasifree processes. Analyzing powers and cross sections were measured for both inclusive and exclusive data. A simple reaction model was developed which suggested a Legendre-polynomial series should describe the sigma(theta_{X}) data. The model relates the polynomial coefficients to nuclear structure information. A result of this work is that this series was found to satisfactorily describe the data and provided new information about the ^{12} C continuum. This work also establishes a significant modification of the general picture of the continuum of light nuclei. Analysis of the coincidence data indicated that previous inclusive (p,p^') studies have grossly overestimated the size of nonresonant-background contributions. A combined analysis of our coincidence data and high-precision inclusive data was made to provide a more consistent picture of the ^{12}C continuum. Experimental and theoretic advances needed to improve the new techniques were identified.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- January 1993
- Bibcode:
- 1993PhDT........44T
- Keywords:
-
- PROTON;
- PROTON'X) REACTIONS AND APPLICATION TO CARBON (CARBON;
- PROTON SCATTERING;
- Physics: Nuclear