Study of excited states in $^1$ $^4$ C via the $^4$ He( $^1$ $^0$ Be $\alpha$ ) $^1$ $^0$ Be resonance scattering reaction

Malcolm, Jonathan (2013). Study of excited states in $^1$ $^4$ C via the $^4$ He( $^1$ $^0$ Be $\alpha$ ) $^1$ $^0$ Be resonance scattering reaction. University of Birmingham. Ph.D.

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Abstract

A study has been made of the $^4$ He( $^1$ $^0$ Be $\alpha$ ) $^1$ $^0$ Be resonant scattering reaction to explore possible molecular rotation bands in $^1$ $^4$ C. The experiment was performed at a range of beam energies from 25 to 42 MeV. The recoil particles from the reaction were detected by a set of surface barrier zero degree monitors and two 'lampshade' arrays of silicon strip detectors. A range of new resonances were discovered in the excitation function of $^1$ $^4$ C between 13 and 24 MeV. Properties of some of these states were identified using angular distribution methods and monte carlo simulations. An R-matrix analysis was performed on the excitation function to provide additional information about the resonances. Three states, at excitation energies of E $_x$ = 18.8, 19.76 and 20.66 MeV, have been measured and their spins and parities positively determined by angular correlation to be 5 $^-$ , 5 $^-$ and 6 $^+$ respectively. Two additional states at energies E $_x$ = 17.5 and 17.98 MeV have had their spins and parities identified by R-matrix analysis to be 3 $^-$ and 4 $^+$ respectively.