G. Lebée

The Orsay radio-frequency mass spectrometer

An RF mass spectrometer of the L. G. Smith type was built with 2 aims: to provide an experimental test of the CPT invariance (proton-antiproton mass comparison) and to measure the atomic masses of nuclei far from stability produced in the ISOLDE-PS Booster facility. As a priority was given to the first application, the features of the spectrometer are presented in this framework. Then, a discussion is made about the adaptation, currently under way, to the second application.

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.

Present status of the MISTRAL mass measurement experiment

The MISTRAL experiment for measuring masses of very short-lived nuclides at ISOLDE has been installed during the summer of 1997 and has had its first radioactive beam in November 1997. Tests are presently been carried out to study all possible systematic effects. This paper recalls the basic principles of the Smith-type radio-frequency spectrometer, gives its present characteristics and limitations, and describes the methods used to improve its performances.

MISTRAL: The beginning of a new mass measurement program at ISOLDE

The MISTRAL* experiment is now on-line at ISOLDE. Installed in May 1997, MISTRAL received its first stable beam in October and first radioactive beam in November 1997. These first tests, with a plasma ion source, resulted in excellent isobaric separation and reasonable transmission. Further testing and development enabled first data taking in July 1998 on neutron-rich Na isotopes having half-lives as short as 31 ms.

Accurate mass measurements of short-lived isotopes with the MISTRAL* rf spectrometer

The MISTRAL* experiment has measured its first masses at ISOLDE. Installed in May 1997, this radiofrequency transmission spectrometer is to concentrate on nuclides with particularly short half-lives. MISTRAL received its first stable beam in October and first radioactive beam in November 1997. These first tests, with a plasma ion source, resulted in excellent isobaric separation and reasonable transmission. Further testing and development enabled first data taking in July 1998 on neutron-rich Na isotopes having half-lives as short as 31 ms.

First results using a new technology for measuring masses of very short-lived nuclides with very high accuracy: The MISTRAL program at ISOLDE

MISTRAL is an experimental program to measure masses of very short-lived nuclides (T1/2 down to a few ms), with a very high accuracy (a few 10−7). There were three data taking periods with radioactive beams and 22 masses of isotopes of Ne, Na, Mg, Al, K, Ca, and Ti were measured. The systematic errors are now under control at the level of 8×10−7, allowing to come close to the expected accuracy. Even for the very weakly produced 30Na (1 ion at the detector per proton burst), the final accuracy is 7×10−7.

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.