P.M. Simmons

The construction and operation of a hybrid gas-silicon detector for studies of cluster breakup reactions

A hybrid detector system has been constructed consisting of a gas filled ionization chamber and a large area silicon semiconductor strip detector within the same gas volume. The construction and operation of these detectors is described, together with a brief description of the electronics and data acquisition system used in cluster breakup studies. The techniques for software correction and gain matching of the detector energy signals are described and results are presented for the resolutions in energy, position and time. In a typical application, elements up to Ca are easily resolved and the positions of individual ions are measured with a resolution of <0.2 mm in the reaction plane, whilst energy resolutions approaching 200 keV can be obtained from the Si strip detector over a small area. Some spectra are presented for measurements of the breakup of Mg-24 into C-12 + C-12.

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.

Calibration of position sensitive detectors with low-energy elastic scattering

Abstract We present a technique by which to calibrate the energy and position of particles striking a position-sensitive strip detector using a resistive charge division read out where the precise polar angle of the detector in the scattering chamber and the relative gains in various channels are unknown. The method is illustrated for a 16-strip detector using low-energy elastic scattering of ions from different targets.

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.

Can break-up reactions be used to probe high-lying inelastic channels in scattering?

The reaction has been studied to investigate a possible overlap with the scattering resonances observed in the and channels. Evidence for the break-up of was observed, but the yield was too low to be able to associate it with specific resonances.

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.

Association of the C-12 + C-12 breakup states in Mg-24 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.