THE PHOTODISINTEGRATION OF NEON

Abstract

A proportional counter, filled to 4-atmosphere pressure with pure neon, and a cylindrical gridded ionization chamber, filled to 9-atmosphere pressure with neon containing some helium, have been irradiated with the gamma-ray flux from a thick lithium target bombarded with 500-kev protons. Pulse height analysis led to the assignment of the following photodisintegration cross sections in millibarns:Ne²⁰(γ_17.6, α)O¹⁶, 0.05 to the ground state of O¹⁶, 0.67 to the 6.06- and 6.14-Mev levels of O¹⁶, 1.80 to the 6.91- and 7.12-Mev levels of O¹⁶;Ne²⁰(γ_14.8, α)O¹⁶, 0.086 to the ground state, about 1.0 to the 6.06- and 6.14-Mev levels;Ne²⁰(γ_17.6, p)F¹⁹, 21 to the ground and low-lying levels at 110, 197 kev in F¹⁹, about 5 to the 1.35- and/or 1.57-Mev levels in F¹⁹;Ne²²(γ_17.6, α)O¹⁸, 0.76 to the ground level.The Ne²⁰(γ, α)O¹⁶ cross sections are in good accord with the selection rules put forward by Gell-Mann and Telegdi for the photodisintegration of an even–even nucleus.