57 Laser Spectroscopy of Short-Lived Isotopes H. T. Duong
Downloaded by UNIV OF CALIFORNIA SAN DIEGO on April 22, 2016 | http://pubs.acs.org Publication Date: November 14, 1986 | doi: 10.1021/bk-1986-0324.ch057
Laboratoire Aimé Cotton, Centre Nationale de Recherche Scientifique, Bât. 505, 91405 Orsay, France Nuclear properties (spins, moments, charge radii) revealed by the analysis of hyperfine structure and isotope shift of atomic levels have been obtained in decades of experiments. Since 1975 with the introduction of tunable dye laser, the rebirth of the methods, some already known since 1930, had led to many on line experiments on short lived isotopes not investigated before. I report here a sample of the experiments done by the Orsay, Mainz groups at CERN. Although experiments have been carried out by the Orsay group using the proton beam of the CERN Proton Synchrotron, most of the experiments have been done at Isolde, the on - line mass separator at CERN, whose radioactive beams are essential to the success of these experiments [RAV 84]. 20-31
Na The method of particle detection of optical resonances, in alkali atoms, by means of magnetic deflection has been developed [DUO 74] and applied to Na at Orsay [HUB 75]. A target, placed inside a high temperature oven, is bombarbed with a proton beam. The thermalised reaction products are emitted from the oven and form an atomic beam, see Fig 1 a. The atoms interact with the light from a C.W. tunable single mode dye laser in the presence of a constant weak magnetic field H , which defines the quantization axis, parallel to the laser beam. At optical resonance with one of the hyperfine component of the D or D line, the laser light induces an optical pumping which changes the population distribution between the magnetic substates (F, m ) of the ground state. The population changes are analysed by a six pole magnet which focuses those corresponding to nijr + 1/2 and defocuses those corresponding to mj =-1/2. After the six pole magnet the focused atoms of the beam are ionized, mass separated and counted When the laser frequency is scanned the optical resonances appear as positive or negative peaks on a baseline ion signal. Between the interaction region with the laser light and the six pole magnet, see fig 1 b, a r.f magnetic field given by a r. f loop could be applied to the optically pumped atoms for magnetic resonance measurement of the hyperfine structure of the ground state [ DUO 82] or the spin determination. Part of the optical resonances observed in the case of sodium [ HUB 78] and the magnetic resonance curve in the ground state of K , [DUO 82] are shown in fig lc and Id respectively.
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0097-6156/ 86/ 0324-0380S06.00/ 0 © 1986 American Chemical Society Meyer and Brenner; Nuclei Off the Line of Stability ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
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Downloaded by UNIV OF CALIFORNIA SAN DIEGO on April 22, 2016 | http://pubs.acs.org Publication Date: November 14, 1986 | doi: 10.1021/bk-1986-0324.ch057
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