Delayed proton emission of N=81 odd-odd precursors: Ho148, Tm150, and Lu152

J. M. Nitschke, Phillip Wilmarth, J. Gilat, K. S. Toth, F. T. Avignone

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Abstract

Beta-delayed proton decay was observed in Ho148, Tm150, and Lu152 for the first time. Contrary to neighboring even-Z N=81 isotones, the proton spectra appear structureless and statistical in nature. Proton branching ratios for the high-spin isomers in these isotopes, based on the intensity of -ray transitions in the intermediate nuclei, are (8-2+1)×10-4, (1.2-0.4+0.2)×10-2, and (1.50.7)×10-1, respectively. The onset of proton emission in all three cases occurs at a proton to width ratio of about 10-4. Protons were found to be in coincidence with x rays, rays, and positrons. Coincident K x rays served to identify the Z of the precursor, while the rays gave quantitative information about proton decay to excited states in the daughter nuclei. By comparing the final state branching ratios with statistical model calculations, it was concluded that Ho148 and Tm150 both have isomers with probable spin values of 1+ and 6-. Statistical model calculations with standard prescriptions for level densities and widths, and with a reduced level density parameter are compared to experiment. To reproduce the shape of the proton spectrum it was necessary to assume Gaussian-shaped Gamow-Teller strength functions centered near 8 MeV excitation energy. In the course of these experiments -delayed proton emission in Er148 was also identified.

Original languageEnglish (US)
Pages (from-to)2694-2703
Number of pages10
JournalPhysical Review C
Volume37
Issue number6
DOIs
StatePublished - 1988
Externally publishedYes

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protons
rays
isomers
nuclei
decay
excitation
positrons
x rays
isotopes
energy

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Nuclear and High Energy Physics

Cite this

Delayed proton emission of N=81 odd-odd precursors : Ho148, Tm150, and Lu152. / Nitschke, J. M.; Wilmarth, Phillip; Gilat, J.; Toth, K. S.; Avignone, F. T.

In: Physical Review C, Vol. 37, No. 6, 1988, p. 2694-2703.

Research output: Contribution to journalArticle

Nitschke, J. M. ; Wilmarth, Phillip ; Gilat, J. ; Toth, K. S. ; Avignone, F. T. / Delayed proton emission of N=81 odd-odd precursors : Ho148, Tm150, and Lu152. In: Physical Review C. 1988 ; Vol. 37, No. 6. pp. 2694-2703.
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abstract = "Beta-delayed proton decay was observed in Ho148, Tm150, and Lu152 for the first time. Contrary to neighboring even-Z N=81 isotones, the proton spectra appear structureless and statistical in nature. Proton branching ratios for the high-spin isomers in these isotopes, based on the intensity of -ray transitions in the intermediate nuclei, are (8-2+1)×10-4, (1.2-0.4+0.2)×10-2, and (1.50.7)×10-1, respectively. The onset of proton emission in all three cases occurs at a proton to width ratio of about 10-4. Protons were found to be in coincidence with x rays, rays, and positrons. Coincident K x rays served to identify the Z of the precursor, while the rays gave quantitative information about proton decay to excited states in the daughter nuclei. By comparing the final state branching ratios with statistical model calculations, it was concluded that Ho148 and Tm150 both have isomers with probable spin values of 1+ and 6-. Statistical model calculations with standard prescriptions for level densities and widths, and with a reduced level density parameter are compared to experiment. To reproduce the shape of the proton spectrum it was necessary to assume Gaussian-shaped Gamow-Teller strength functions centered near 8 MeV excitation energy. In the course of these experiments -delayed proton emission in Er148 was also identified.",
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AB - Beta-delayed proton decay was observed in Ho148, Tm150, and Lu152 for the first time. Contrary to neighboring even-Z N=81 isotones, the proton spectra appear structureless and statistical in nature. Proton branching ratios for the high-spin isomers in these isotopes, based on the intensity of -ray transitions in the intermediate nuclei, are (8-2+1)×10-4, (1.2-0.4+0.2)×10-2, and (1.50.7)×10-1, respectively. The onset of proton emission in all three cases occurs at a proton to width ratio of about 10-4. Protons were found to be in coincidence with x rays, rays, and positrons. Coincident K x rays served to identify the Z of the precursor, while the rays gave quantitative information about proton decay to excited states in the daughter nuclei. By comparing the final state branching ratios with statistical model calculations, it was concluded that Ho148 and Tm150 both have isomers with probable spin values of 1+ and 6-. Statistical model calculations with standard prescriptions for level densities and widths, and with a reduced level density parameter are compared to experiment. To reproduce the shape of the proton spectrum it was necessary to assume Gaussian-shaped Gamow-Teller strength functions centered near 8 MeV excitation energy. In the course of these experiments -delayed proton emission in Er148 was also identified.

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