No abstract

The spectra of 20Na and 20F obtained by charge exchange reactions on 20Ne are compared; differences are seen close to the respective break-up thresholds. The excitation energies of 16 levels in 20Na have been obtained and spins assigned from DWBA calculations are compared with predictions of the shell model. In 20F, a strongly excited state is seen at 6.75 MeV, but the intruder state at 3.17 MeV is very weak.

W h a t m e Laboratory. King's College. London WCZR 2LS. UK Received 4 May 1993 AbslracL Differential cmss seaions are presented for the analogue charge exchange maim wNe(3He~t~aNaand'oNe(~~He)ZoFat an incident energy of 33.4 MeV. Theangulardisuibutions are very similar for states of the same spin-parity assignment. On this basis, the analogue of the 2646keV stale in wNa is identsed with the 2966keV state (3") in "F.

A current measuring system capable of detecting single ions is described. The detector operates at a frequency of nominally 900 kHz and utilizes a superconducting inductor with high Q(Q≊8500) and a cryogenic GaAs field-effect transistor (FET) amplifier with noise temperature less than 0.3 K. Noise measurements of the FET are presented along with details of the construction of the superconducting inductor.