25 research outputs found
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ATOMIC RESEARCH ON RADIOACTIVE ATOMS (THE FIRST ERNEST O. LAWRENCE MEMORIAL LECTURE, MEETING OF THE NATIONAL ACADEMY OF SCIENCES, BERKELEY, CALIF.)
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ATOMIC RESEARCH ON RADIOACTIVE ATOMS (THE FIRST ERNEST O. LAWRENCE MEMORIAL LECTURE, MEETING OF THE NATIONAL ACADEMY OF SCIENCES, BERKELEY, CALIF.)
Expérience de double résonance dans un jet atomique
Transitions that are not otherwise observable in an atomic beam flop-in apparatus have been observed by means of a double resonance technique. The method has been used to observe the ÎF = 0 transitions in 39K, and involves the use of three rf hairpins through which the beam passes in succession. The frequency of the rf in the first and third hairpins is adjusted to produce the transition (2, â 1) ââ (1, â 1). If an atom enters the transition region in the state (2, â 1), it will go to (1, â 1) in the first hairpin and then back to (2, â 1) in the third. Thus a small signal will be seen at the detector. If the transition (1, â 1) ââ (1, 0) is excited in the second hairpin, some of the atoms that have gone from (2, â 1) to (1, â 1) will go to (1,0) and will not go back to (2, â 1) in the third hairpin. An increase in detector reading will thus be seen when the transition (1, â 1) ââ (1, 0) is excited. All of the possible ÎF = 0, Î M = ±1 transitions have been observed in the case of 39K by choosing the proper ÎF = ± 1 transition. Certain precautions are necessary, however, to observe some of them. The transition (2, 0) ââ (1, â 1) and (2, â 1) ââ (1, 0) are an unresolved doublet. If these transitions are excited in the first and third hairpin, the transitions (2, 0) ââ (2, â 1) or (1, â 1) ââ (1, 0) cannot be observed when they are excited in the second hairpin. This is found to be generally true ; that whenever the ÎF = ± 1 transition involves both of the levels of the ÎF = 0 transitions, the latter cannot be observed. In order to observe these ÎF = 0 transitions, the ÎF = ± 1 transition (2, 0) ââ (1, 0) must be excited in the first and third hairpins. Certain of the Î F = 0 transitions form doublets, the components of which are separated by 2gIÎŒ0H. It is hoped to use this technique to measure nuclear magnetic moments of radioactive nuclei.Des transitions qui ne sont pas observables par la mĂ©thode de rĂ©sonance ordinaire des jets atomiques deviennent observables grĂące Ă une technique de double rĂ©sonance. La mĂ©thode a Ă©tĂ© utilisĂ©e pour observer les transitions Î F = 0 dans 39K. Elle emploie trois circuits RF successifs sous forme d' « Ă©pingle Ă cheveux » qui sont traversĂ©s successivement par les atomes du jet. La frĂ©quence RF commune du premier et du troisiĂšme circuit est ajustĂ©e de façon Ă provoquer la transition (2, â 1) ââ (1, â 1). Si un atome entre dans la rĂ©gion de transition Ă l'Ă©tat (2, â 1) il subira dans le premier circuit la transition vers (1, â 1) et dans le troisiĂšme circuit la transition inverse qui le ramĂšnera vers (2, â 1). Le dĂ©tecteur utilisant la mĂ©thode « flop-in » ne donnera qu'un signal faible. Si dans le deuxiĂšme circuit on excite la transition (1,â1) ââ (1, 0) quelques-uns des atomes qui avaient subi la transition (2, â 1) â (1, â 1) dans le premier circuit, vont transiter maintenant vers (1, 0) et ne pourront pas retourner Ă l'Ă©tat (2, â 1) dans le troisiĂšme circuit. On observera ainsi un accroissement du signal du dĂ©tecteur en excitant la transition (1, -1) ââ (1, 0). De cette maniĂšre on a pu dĂ©tecter toutes les transitions possibles ÎF = 0, ÎM = ± 1 dans le cas du 39K en y associant la transition ÎF = ± 1 convenable. Mais il faut observer certaines prĂ©cautions pour quelques-unes d'entre elles. Les transitions (2, 0) ââ (1, â 1) et (2, â 1) ââ (1, 0) forment un doublet non rĂ©solu. Si ces transitions sont excitĂ©es dans les rĂ©gions I et III, les transitions (2, 0) ââ (2, â 1) ou (1, â 1) ââ (1, 0) ne peuvent pas ĂȘtre observĂ©es par excitation dans la rĂ©gion II. Ceci est gĂ©nĂ©ral : dans tous les cas oĂč la transition Î F = ± 1 intĂ©resse les deux niveaux bordant une transition ÎF = 0, cette derniĂšre ne peut pas ĂȘtre observĂ©e. Pour pouvoir observer ces transitions ÎF = 0, il est nĂ©cessaire d'exciter la transition (2, 0) ââ (1, 0) dans les rĂ©gions I et III. Certaines des transitions Î F = 0 forment des doublets d'intervalle 2gI ÎŒ0 H. On espĂšre utiliser cette technique pour mesurer ainsi les moments nuclĂ©aires de noyaux radioactifs
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STUDY OF OPTICAL-PIMPING TRANSIENTS IK RUBIDIUM AND CESIUM VAPORS
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