R. Klapisch

Hyperfine structure and isotope shift of the D2 line of 118–145Cs and some of their isomers

Abstract High-resolution laser spectroscopy has been performed on 118–145 Cs and 119m, 121m, 122m, 130m, 134m, 135m, 136m, 138m, Cs.The Cs nuclei have been produced either by spallation of La or by fission of U by the 600 MeV proton beam, from the SC at CERN. The hyperfine structures, spins, and isotope shifts have been measured. The charge radii changes deduced from the isotope shifts exhibit shell effects at N = 82, isomeric staggering for N = 64,66,67 and a strong odd-even staggering for all isotopes with N

Isotope shifts and hyperfine structure of 38–47K by laser spectroscopy

Abstract Laser optical spectroscopy on a thermal atomic beam has been performed on the 4 2 S sol1 2 −4 2 P 1 2 D 2 line of 38,39,41–47K. Hyperfine structure constants and isotope shifts have been measured. Magnetic moments and changes in the mean square charge radii are deduced.

β-delayed charged particles from 9Li and 11Li

Abstract β-delayed emission of α-particles from 9Li and of both α and 6He particles from 11Li is observed. Singles energy spectra and two-dimensional energy spectra of coincident particles are measured. A time-of-flight versus energy measurement is used to identify the mass of the particle. New β-branches are observed which populate high-energy levels in the daughter nuclei. The branching ratios are measured and the β-delayed neutron emission probabilities P n for 9 Li and P 3n for 11 Li are deduced.

Direct mass measurements on francium isotopes and deduced masses for odd-z neighbouring elements

Abstract The masses of 204–210, 212 Fr and 224–228 Fr have been determined with direct on-line mass spectrometry. From previously known Q a values, the masses of 28 isotopes of Pa, Ac, At, Bi and Tl are deduced. All these experimental masses are compared with the current mass predictions.

The PS on-line mass spectrometer dedicated to the study of the exotic light nuclei

Abstract The experiments performed with the PS on-line mass spectrometer: atomic hyperfine structure determinations and nuclear spectroscopy of Li, Na and K isotopes require high efficiency and as low as possible radioactive background in the area of the detectors. A view of the lay-out will be given concerning in particular the very thick iron and concrete shielding and the mass separated ion beam line going through the shielding from the mass spectrometer to the detector room. This device is an L-shaped pipe with electrostatic focusing elements. The background correlated with the proton beam pulse is lower than the sensitivity of the γ detector and the neutron flux is less than 1 n/cm2s. Slow rate events, corresponding to nuclei far from the stability, such as 34Na, are recorded with a good signal-to-noise ratio.

On-line laser spectroscopy with thermal atomic beams

Abstract On-line high resolution laser spectroscopy experiments have been performed in which the light from a cw tunable dye laser interacts at right angles with a thermal atomic beam. 76–98Rb, 118–145Cs and 208–213Fr have been studied using the ionic beam delivered by the ISOLDE on-line mass separator at CERN while 20–31Na and 38–47K have been studied by setting the apparatus directly on-line with the PS 20 GeV proton beam. The principle of the method is briefly explained and some results concerning nuclear structure are given.

Antiproton-proton mass comparison with a radio-frequency mass spectrometer

Abstract The experiment aims at the reduction of the upper limit on a hypothetical CPT violation in the antiproton-proton system. A radio-frequency mass spectrometer (RFMS) has been designed and built to make the comparison of the charge to mass ratios of p and p by measuring the ratios of the cyclotron frequencies of p and H− ions. At present, the RFMS is installed on-line to the LEAR facility at CERN. The resolving power has been found to be close to 3 × 105 and it still could be improved. A decelerating system (RFQ) has been installed in order to decelerate antiprotons from 2 MeV to 200 keV and to match as well as possible the acceptance of the spectrometer. It is presently under test and data taking should take place in 1992.

The radiofrequency mass spectrometer for the comparison of proton-antiproton masses

The radiofrequency mass spectrometer has been prepared in Orsay, and moved to CERN to be installed on-line with LEAR (PS189). The present and finally expected performances are given.

Measurement of the antiproton inertial mass using a radio-frequency mass spectrometer: Present status

Abstract In order to test CPT invariance theorem, PS189 aims at checking the equality of proton and antiproton masses via the measurement of the ratio of H − and p masses using a radio-frequency mass spectrometer. Recent progress, including a resolving power of 6 × 10 5 , is presented.

Present Status of the Radiofrequency Mass Spectrometer for the Comparison of the Proton-Antiproton Masses (Experiment PS 189)

The principle and the main parameters of the radiofrequency mass spectrometer for the experiment PS 189 (Fig. 1) have already been discussed and described in detail1,2,3. We shall here only recall them very briefly and give the present status of the preparation of the experiment.