C.D. Jones

Association of the 12C+12C breakup states in 24Mg with the quasimolecular resonances.

A high resoution measurement of the [sup 12]C([sup 24]Mg,[sup 12]C[sup 12]C)[sup 12]C reaction shows that the [sup 24]Mg breakup states have widths in the region of 100 to 250 keV. The energies, widths, and spins of these states are seen to be consistent with those of the [sup 12]C +[sup 12]C quasimolecular resonances which occur in the same region of excitation in the [sup 24]Mg nucleus.

Comparison of resonances observed in the 12C(24Mg, 12C12C)12C and 12C(20Ne, 12C12C)8Be reactions

Abstract A study of the 12 C( 24 Mg, 12 C 12 C) 12 C reaction has revealed discrete states at excitation energies between 20 and 30 MeV in 24 Mg. Angular correlation analyses of some of the lower energy states confirms the report by earlier authors of monotonically increasing spin values consistent with a rotational sequence. Comparison with breakup observed in the 12 C( 20 Ne, 12 C 12 C) 8 Be reaction suggests that the same states in 24 Mg are populated, while the difference in laboratory cross sections in the two reactions is interpreted as evidence for the association of the breakup states with a prolate hyper-deformed configuration appearing in theoretical calculations for 24 Mg.

Search for {sup 16}O+{sup 16}O+{sup 16}O structure in {sup 48}Cr

Two theoretical papers have suggested the existence of an {sup 16}O+{sup 16}O+{sup 16}O configuration in {sup 48}Cr. We report on three experimental searches for the ternary breakup of {sup 48}Cr to the {sup 16}O+{sup 16}O+{sup 16}O channel. No evidence is seen for the process. Upper limits for the cross section are reported. {copyright} {ital 1996 The American Physical Society.}

Reaction mechanism for the symmetric breakup of 24Mg following an interaction with 12C

Abstract Data on the yield of the symmetric breakup of 24 Mg as a function of beam energy are presented and compared with detailed calculations of the energy dependence. The 24 Mg states seen in symmetric breakup agree with previously observed breakup states having spin and parities J π = 4 + ,(6 + ),8 + . The data allow the variations of yield for individual states to be judged, as the beam energy is varied. The variation in the yield of the 4 + states is compared in detail with calculations assuming several possible compound nuclear or direct reaction mechanisms. It is concluded that a massive ( 12 C) transfer or a simple statistical compound process are unlikely mechanisms, but that each of several other mechanisms is consistent with the data.

Termination of the 12C12C cluster states revealed in the 12C(20Ne,12C12C) 8Be breakup reaction

Abstract An investigation of the 12C(20Ne,12C12C)8Be reaction at 300 MeV shows the breakup yield disappears at the same excitation energy as observed in a previous measurement at 160 MeV. This would be consistent with the breakup being associated with highly-deformed-shape isomeric bands which model calculations predict will terminate at high excitation energies.

Two-dimensional alpha cluster structures in 28Si

Abstract A study has been made of the 12C(16O,12C12C) α reaction between the centre of mass energies of 28.3 to 36.8 MeV. A number of resonances in 28Si have been observed for final channels leading to the unbound 10.35, 11.09 and 14.82 MeV states in 16O. At two energies associated with previously observed resonances, the angular correlations of the exit channel particles have been analysed to measure the dominant angular momentum of the 28Si compound nucleus. Additional data were acquired at two off-resonance energies for comparison. Using an essentially model independent analysis, the values obtained were all in the region of 19–21 h , and are comparable with the grazing angular momentum in the entrance channel. The results are relevant to recent theoretical predictions of planar α-cluster structures in 28Si and are discussed in the context of the model predictions.

Association of the [sup 12]C+[sup 12]C breakup states in [sup 24]Mg with the quasimolecular resonances

A high resoution measurement of the [sup 12]C([sup 24]Mg,[sup 12]C[sup 12]C)[sup 12]C reaction shows that the [sup 24]Mg breakup states have widths in the region of 100 to 250 keV. The energies, widths, and spins of these states are seen to be consistent with those of the [sup 12]C +[sup 12]C quasimolecular resonances which occur in the same region of excitation in the [sup 24]Mg nucleus.