E. Poirier

Beta-delayed neutron decay of 33Na

Abstract Beta-delayed neutron decay of 33 Na has been studied using the on-line mass separator ISOLDE. The delayed neutron spectra were measured by time-of-flight technique using fast scintillators. Two main neutron groups at 800(60) and 1020(80) keV were assigned to the 33 Na decay, showing evidence for strong feeding of states at about 4 MeV in 33 Mg. By simultaneous β–γ–n counting the delayed neutron emission probabilities P 1n =47(6)% and P 2n =13(3)% were determined. The half-life value for 33 Na, T 1/2 =8.0(3) ms , was measured by three different techniques, one employing identifying gamma transitions and two employing beta and neutron counting.

Non-analog beta decay of Rb-74

The magnitude of the Coulomb mixing parameter δ 1 has been experimentally deduced, for the first time, for the β decay of 74 Rb. The estimated magnitude is derived from the feeding of the non-analog first excited 0 + state in 74 Kr. The inferred upper limit of 0.07% is small compared to theoretical predictions. The half-life was measured to be 64.90(9) ms.  2001 Published by Elsevier Science B.V.

Beta decay and structure of exotic nuclei in the mass regions N=Z, A ~ 70 and near the N=20 closed shell

This paper describes two beta decay experiments performed at the CERN/ISOLDE mass separator. The structure of 74Kr has been studied using a total absorption g spectrometer (TAgS). The measured Gamow-Teller strength is presented and compared to HFBCS+QRPA calculations. The 33Na decay is also presented. The structure of the 33Mg daughter nucleus is compared to shell-model calculations, showing for the first time an inversion of states in the A~35 mass region.

STRUCTURE OF THE HEAVY CA ISOTOPES AND EFFECTIVE INTERACTION IN THE SD-FP SHELL

p decays of the neutron-rich nuclei 51,52,53K have been used to populate bound and unbound levels in 50,51,52,53Ca. y r a y spectroscopy as well as P-delayed neutron spectroscopy by time of flight were carried out to obtain a detailed decay scheme to levels in 53Ca, 52Ca, 51Ca and 50Ca. A half-life of 1 1 6 f 6 ms was deduced and new PI, and Pzn delayed neutron emission probabilities have also been determined for 52K. A total of 11 and 3 new y transitions have been observed in the decay of 52K and 53K, respectively. The low-lying level structure of 52Ca is compared to shell-model calculations. Implications of these results on the determination of the Y-Y interaction in the fp shell are discussed.

A new Total Absorption Spectrometer for the study of exotic nuclei at the CERN/ISOLDE mass separator

We report here on a new Total Absorption Spectrometer dedicated to the study of exotic nuclei, presently installed at the CERN/ISOLDE mass separator.

Doppler broadened gamma lines as a means to derive new information about the β-decay of 11Li

The low-energy βγ-decay from 11Li has recently been shown to be a sensitive tool for extracting information about halo wave functions [1]. Here we present a method for using the shape of Doppler-broadened γ-lines to extract information about excited states fed in β-decay [2]. The procedure has been used to extract new information about the β-decay of 11Li through the de-excitation of excited states in 10Be.

A step further in the A = 33−35, N ≃ 21, island of inversion: the structure of 33Mg

Experimental indications have been found in the seventies for the deformation of neutron-rich A ≃ 32 nuclei [1]. This could be explained by Hartree-Fock calculations, predicting deformed configurations in the ground state of nuclei in the A = 33−35, N ≃ 21 mass region. This exotic region, called the island of inversion [2], knows a renewed interest since it can be now experimentally accessible for detailed studies.