[en] Angular distributions for the reactions ²⁶Mg(⁶Li, ⁷Besub(0.0))²⁵Na and ²⁶Mg(⁶Li, ⁷Besub(0.43))²⁵Na have been measured at E6sub(Li)=36 MeV. Elastic and inelastic scattering data for ⁶Li + ²⁶Mg have also been collected. The inelastic scattering has been analysed using a zero-range DWBA calculation and a value of 0.26 +- 0.02 has been extracted for the β₂ deformation parameter of the 2⁺(1.81 MeV) state in ²⁶Mg. An exact finite-range DWBA analysis of the single-proton pick-up reaction has been performed and the overall normalisation of the theoretical cross section was found to depend critically on the optical-model potentials used. A value for C²S for ²⁶Mg(0.0 MeV)→²⁵Na(0.0 MeV) + p of 3.0 +- 0.3 has been obtained using shallow heavy-ion radius potentials. This value is in good agreement with those deduced from light-ion work and with theoretical values. (author)

[en] Heavy ion charge exchange reactions have a great potential for probing spin-transfer strength in nuclei. Provided that the reaction mechanism is simple (one step) in nature, projectile and ejectile quantum numbers can be chosen to isolate isovector, spin transferring (ΔS=ΔT=1) transitions. Tests of two of the more promising such reactions, (⁶Li, ⁶He) and (¹²C, ¹²N) have shown that they are dominantly one step above about 25 and 60 MeV/nucleon, resp. Phenomenological calibration curves have been established for each of these reactions. The (¹²C, ¹²N) reaction has been studied on ^54956958Fe to test electron capture strengths relevant to supernova collapse. This and available results from other laboratories are discussed

[en] Angular distributions have been measured for the (⁹Be,¹⁰B[3⁺, 0.0] and (⁹Be,¹⁰B[1⁺, 0,72]) reactions on ⁶³Cu, ⁵⁴Fe, sup(26,24)Mg and ¹⁶O at 43 MeV and on ⁴⁰Ca at 45 and 30 MeV. EFR-DWBA calculations which used optical potentials from the measured elastic scattering of ⁹Be from ²⁶Mg, ¹⁶O and ⁴⁰Ca and ¹⁰B from ²⁵Mg and ³⁹K have generally reproduced well the shape of the cross sections. Initially, a standard prescription was used in the form-factor calculation and Cohen and Kurath spectroscopic factors were assumed for ⁹Be-¹⁰Be. Inconsistencies, concerning whether ¹⁰B was left in its ground or first excited state, of up to 60% were found between the extracted target spectroscopic factors. This anomaly was insensitive to changes in either optical-potential or bound-state parameters. A simple calculation of a two-step process could not account for the anomaly. Use of modified spectroscopic factors for the ⁹Be-¹⁰B system essentially removed the discrepancies except for the magnesium targets, and an improved form-factor description further alleviated the anomaly. This form-factor method uses a shell-model potential in conjunction with a surface-peaked potential, the depth of which is adjusted to give the correct asymptotic form to the wave function. (orig.)

[en] Heavy-ion reactions can be powerful probes for spin-transfer strength in nuclei, provided their reaction mechanism is simple so that a correlation can be established between cross sections and the relevant matrix elements. We discuss the desirable features of heavy-ion reactions in general and a series of tests of reaction mechanisms that have been carried out for two of the most favorable reactions: (⁶Li, ⁶He) and (¹²C, ¹²N). We establish that the (⁶Li, ⁶He) reaction is one-step in nature above 25 Mev · nucleon^-1 and establish a calibration function relating cross sections and Gamow-Teller matrix elements. We also find that the (¹²C, ¹²N) reaction is likely to be dominated by the one-step process above about 50 MeV · nucleon^-1

[en] Charge exchange and inelastic scattering of heavy ions appear to offer significant advantages over nucleon projectiles for the study of spin-isospin strength in nuclei. This paper discusses studies performed to data and assesses the potential for further advances, including applications to astrophysics, with the new generation of heavy ion spectrographs. Coincident detection of gamma rays at the target location will permit experiments with selectivity not available with lighter projectiles. A brief description of the NSCL S800 spectrograph project is also presented

[en] Heavy ion charge-exchange reactions have great potential for probing spin-transfer strength in nuclei, provided beams of sufficient energy are used so that the reactions might be expected to be simple (one-step) in nature. Tests of reaction mechanisms have been carried out for two of the most favorable reactions, (⁶Li,⁶He) and (¹²C,¹²N). We have shown that the first reaction is mainly one-step in nature at 25 MeV/nucleon and above and have established a calibration curve relating cross sections to Gamow-Teller matrix elements. We have also shown that the second reaction is likely to be mainly one-step above about 50 MeV/nucleon. A (¹²C,¹²N) measurement on Fe targets was done recently, with the aim of determining astrophysically interesting Gamow-Teller strengths in Fe nuclei. (orig.)

[en] A ''hybrid'' focal plane counter comprising a gridded ionization chamber with position sensitive proportional counters, 300 mm long, 510 mm deep and with an active height of 60 mm, is described. The detector is designed for use with the Oxford MDM-2 magnetic spectrometer and is suitable for both light and heavy ions. Typical results obtained are 0.6 mm position resolution and 1% total energy resolution. Two energy loss, a veto and two position signals are available as well as provision for height and timing signals. Techniques are described for the reduction of capacitive noise, correction of electric field nonuniformities, and the reduction of interference from positive ions on the ionization signals. (orig.)

[en] The ¹¹Be(p, d)¹⁰Be reaction has been performed in inverse kinematics with a radioactive ¹¹Be beam of E/A = 35.3 MeV. Angular distributions for the 0⁺ ground state, the 2⁺, 3.37 MeV state and the multiplet of states around 6 MeV in ¹⁰Be were measured at angles up to 16 cm by detecting the ¹⁰Be in a dispersion-matched spectrometer and the coincident deuterons in a silicon array. Distorted wave and coupled-channels calculations have been performed to investigate the amount of 2⁺ core excitation in ¹¹Be_gs. The use of 'realistic' ¹¹Be wave functions is emphasised and bound state form factors have been obtained by solving the particle-vibration coupling equations. This calculation gives a dominant 2s component in the ¹¹Be_gs wave function with a 16% [2⁺ scal. prod. 1d] core excitation admixture. Cross sections calculated with these form factors are in good agreement with the present data. The Separation Energy prescription for the bound state wave function also gives satisfactory fits to the data, but leads to a significantly larger [2⁺ scal. prod. 1d] component in ¹¹Be_gs. (authors)

[en] A general scheme of the layout of a large acceptance magnetic spectrometer based on a wide aperture quadrupole and a multipurpose bending magnet is described. Physical quantities such as momentum resolution, focal plane size and inclination are explicitly represented as functions of transport matrix elements. In this way such quantities are directly related to the parameters defining the configuration of the spectrometer. Realistic assumptions on the shapes, the distances and the fields of the magnetic elements are taken into account in order to limit the parameter space to be spanned. A self-consistent technique simplifies the search for the best configuration and avoids the problem of ending in local minima. This technique is applied to the MAGNEX spectrometer, for which two competitive configurations, characterised by different bending angle, are found and discussed

[en] Angular distributions have been measured for the (⁶Li, ⁶He) reaction on targets of ⁷Li, ^12,14C, ²⁶Mg and ⁹⁰Zr at bombarding energies of 35, 25 and 14 MeV/A. The ratios of observed cross sections for states in ¹⁴N and ⁷Be suggest that the reaction mechanism is predominantly one-step at 35 MeV/A with an increasing contribution from sequential transfer at lower energies. One-step DWBA calculations at 35 and 25 MeV/A are consistent with the data. Good proportionality is observed between the measured cross sections for Gamow-Teller transitions and the corresponding β-decay matrix elements