Breakup Studies with a SODIUM(23) Beam

Available from UMI in association with The British Library. The RPS technique has been used to study the breakup of ^{23}Na into ^{11}B + ^{12 }C and of ^{24}Mg into ^{12}C + ^{12}C following excitation by inelastic scattering and by proton transfer from the target respectively. A ^{12}C target was used, together with beams of 176 MeV ^{23}Na produced at the N.S.F., Daresbury Laboratory. The breakup fragments were detected in coincidence by an array of position sensitive detector telescopes; during off-line analysis the events were kinematically reconstructed to obtain the total energy of the exit channel and hence the excitation energy of the scattered target -like nucleus prior to its decay. Clear evidence was found for the breakup of the ^{23}Na and ^ {24}Mg nuclei into the ground states of both fragments, although with a reaction yield almost an order of magnitude below that of the ^{12}C(^{24}Mg,^ {12}C^{12}C)^{12 }C reaction at a similar beam energy. The yield from the ^{12}C( ^{23}Na,^{12}B_ {g.s.}^{12}C_{g.s. })^{12}C_{g.s.} reaction was concentrated in the regions of excitation energy in ^{23}Na around 24 and 28 MeV and appeared fragmented into a number of states, possibly corresponding to those previously seen in elastic scattering and radiative capture work. The ^{12}C(^{23 }Na,^{12}C_{g.s.} ^{12}C_{g.s.})^ {11}B_{g.s.} reaction was found to proceed chiefly via broad states at 22.1 and 23.9 MeV in ^{24}Mg; the excitation spectrum shows very little similarity to that obtained from the ^{12}C( ^{24}Mg,^{12}C_ {g.s.}^{12}C_{g.s. })^ {12}C_{g.s.} reaction with a beam energy of 170 MeV, but greatly resembles that obtained with a beam energy of 357 MeV. The broad state seen in this work at 22.1 MeV has also been reported in radiative capture and electro-fission work, and is thought to be derived from the giant quadrupole resonance.