Abstract
Evidence is presented for three new, light neptunium isotopes formed by deuteron bombardments of , , and . The isotope has a half-life of 50±3 min. and emits alpha-particles of 6.28-Mev energy; the proportion of decay by electron-capture has not been determined. The isotope decays predominantly by electron-capture with a 35±3-min, half-life; it has an alpha-decay half-life roughly determined to be . 10 yr. corresponding to a -branching ratio of 1.5× and the alpha-particles have an energy of 5.53 Mev. A 13±3-min. period with electromagnetic radiation, indicating orbital electroncapture, is attributed to . Approximate cross sections for formation of various neptunium isotopes by deuterons of energy from 15 to 100 Mev have been determined. The cross sections are low, of the order of , possibly because most of the excited nuclei undergo fission.
- Received 7 February 1950
DOI:https://doi.org/10.1103/PhysRev.78.363
©1950 American Physical Society