In-flight production of an isomeric beam of ${}^{16}$N

Abstract

An in-flight beam of ${}^{16}$N was produced via the single-neutron adding ($d$,$p$) reaction in inverse kinematics at the recently upgraded Argonne Tandem Linear Accelerator System (ATLAS) in-flight system. The amount of the ${}^{16}$N beam which resided in its excited 0.120-MeV $J^{\pi }=0^{-}$ isomeric state (T${}_{1/2}\approx 5$ $\mu$s) was determined to be 40(5)% at a reaction energy of 7.9(3) MeV/$u$, and 24(2)% at a reaction energy of 13.2(2) MeV/$u$. The isomer measurements took place at an experimental station $\approx 30$ m downstream of the production target and utilized an Al beam-stopping foil and a HPGe Clover detector. Composite ${}^{16}$N beam rate determinations were made at the experimental station and the focal plane of the Argonne in-flight radioactive ion-beam separator (RAISOR) with Si $\Delta$E-E telescopes. A Distorted Wave Born Approximation (DWBA) approach was coupled with the known spectroscopic information on ${}^{16}$N in order to estimate the relative ${}^{16}$N isomer yields and composite ${}^{16}$N beam rates. In addition to the observed reaction-energy dependence of the isomer fraction, a large sensitivity to angular acceptance of the recoils was also observed.

Comments: 21 pages, 7 figures