A determination of the PSEC half life of the 39.85 keV level in Tl208

Sevier, K.D.

doi:10.1016/0029-5582(65)90610-3

Cited by 14 publications

(2 citation statements)

References 12 publications

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“…Accepting the single-particle shell model as valid, the spectrum of 207 Tl reveals the relative locations of these states below 3s 1/2 as 351 keV, 1348 keV, and 1683 keV [21]. The coupling between the valence neutrons and the proton hole is very weak, as evidenced by the lowest-lying states in 208 Tl which form a one-neutron-particle one-proton-hole (2g 9/2 ⊗3s 1/2 ) J=4,5 doublet separated by only 40 keV, with the higher-spin state most bound [22]. Thus, the low-lying states of 209 Tl may be anticipated to be a near-degenerate series of multiplets arising from coupling 3s 1/2 or 2d 3/2 proton holes to the 210 Pb neutron particle states.…”

Section: Resultsmentioning

confidence: 99%

γ -ray spectroscopy of Tl209

et al. 2017

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States in 209 Tl were populated using a multi-nucleon transfer reaction with a 136 Xe beam impinging on a thick 208 Pb target at E = 785 MeV. The beam was pulsed at 825 ns intervals in order to perform isomer decay spectroscopy. The known J π = 17/2 + isomer in 209 Tl was located at 1228(4) keV and measured to have a half-life of T 1/2 = 146(10) ns. A second isomer with J π = 13/2 + was found to have T 1/2 = 14(5) ns. The previously suggested low-energy "X" and "Y" transitions were found to have energies 57(2) and 47(2) keV respectively, while the measurement of conversion coefficients and a new decay path make the spin assignments below the isomers experimentally firm. Correlating the delayed γ-transitions with the prompt beam flash allowed the decay of states above the isomer to be found. The longer-lived isomer represents full alignment of the simplest two-particle, one-hole configuration, and illuminates the remarkably weak coupling of the proton hole to the 210 Pb core.

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Section: Resultsmentioning

confidence: 99%

γ -ray spectroscopy of Tl209

et al. 2017

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“…The measurement of the lifetimes of excited nuclear states Novakov et aZ(l964) and Sevier (1965) used a variation of this technique where the conversion electrons recoiled into a strong electrostatic potential gradient. The conversion electrons then receive an acceleration which depends on the position of decay.…”

Section: Conversion Electron Techniquesmentioning

confidence: 99%

The measurement of the lifetimes of excited nuclear states

1979

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The experimental techniques of measuring the mean lifetimes T of excited nuclear states is reviewed. Emphasis is put on direct measurements of T in the region 10-18-10-6 s, especially on techniques involving the observation of Doppler energy shifts of y-rays. Indirect methods of obtaining T by measuring the widths or partial widths are discussed. Comparisons are made of the applicability, accuracy and reliability of the different experimental techniques.

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