A photonuclear mechanism for promethium synthesis excluding technetium

Details A photonuclear mechanism for promethium synthesis excluding technetium A photonuclear mechanism for promethium synthesis excluding technetium

Feb 1975

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1975apl....16...87h&link_type=abstract

Astrophysical Letters, vol. 16, no. 3, 1975, p. 87-95. Research supported by North Texas State University.

Astronomy and Astrophysics

Astrophysics

4

Astrophysics, Photonuclear Reactions, Promethium, Stellar Atmospheres, Abundance, Atmospheric Composition, Neodymium Isotopes, Nuclear Fusion, Technetium

Scientific paper

A nuclear mechanism that can produce promethium to the exclusion of technetium is examined which may explain the possible presence of promethium in certain stars. Calculations are presented which show that because of differences in the photoneutron threshold energy between the isotopes Mo-100 and Nd-148, Pm-147 can be produced during CNO burning, but neither Tc-99 nor any other isotope of technetium can be. The changing abundance of Pm relative to Nd is determined as a function of time in terms of a free parameter that combines an anticipated value of the cross section for the Nd-148 (gamma, n) Nd-147 photoneutron reaction with a known photon flux. Results are given for the cases of a continuous source of Nd and depletion of Nd with time in a radiative zone. Effects of beta decay during the transit time between the shell and the surface are estimated along with the dilution which takes place en route. Envelope dilution is found to be the dominant factor in determining the detectability of atmospheric promethium.

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