Spin differences in the Zr90 compound nucleus induced by (p,p′) , (p,d) , and (p,t) surrogate reactions

Autor: B. Abromeit, H. I. Park, Richard Hughes, R. A. E. Austin, Jason Burke, Nicholas Scielzo, Jutta Escher, Robert Casperson, N. J. Foley, Jennifer J. Ressler, M. McCleskey, Ian J. Thompson, E. McCleskey, S. Ota, T.J. Ross, Antti Saastamoinen
Rok vydání: 2015
Předmět:
Zdroj: Physical Review C. 92
ISSN: 1089-490X
0556-2813
DOI: 10.1103/physrevc.92.054603
Popis: The effect of the production mechanism on the decay of a compound nucleus is investigated. The nucleus $^{90}\mathrm{Zr}$ was produced by three different reactions, namely $^{90}\mathrm{Zr}(p,{p}^{\ensuremath{'}})^{90}\mathrm{Zr}$, $^{91}\mathrm{Zr}(p,d)^{90}\mathrm{Zr}$, and $^{92}\mathrm{Zr}(p,t)^{90}\mathrm{Zr}$, which served as surrogate reactions for $^{89}\mathrm{Zr}(n,\ensuremath{\gamma})$. The spin-parity $({J}^{\ensuremath{\pi}})$ distributions of the states populated by these reactions were studied to investigate the surrogate reaction approach, which aims at indirectly determining cross sections for compound-nuclear reactions involving unstable targets such as $^{89}\mathrm{Zr}$. Discrete $\ensuremath{\gamma}$ rays, associated with transitions in $^{90}\mathrm{Zr}$ and $^{89}\mathrm{Zr}$, were measured in coincidence with light ions for scattering angles of ${25}^{\ensuremath{\circ}}--{60}^{\ensuremath{\circ}}$ and $^{90}\mathrm{Zr}$ excitation energies extending above the neutron separation energy. The measured transition systematics were used to gain insights into the ${J}^{\ensuremath{\pi}}$ distributions of $^{90}\mathrm{Zr}$. The $^{90}\mathrm{Zr}(p,{p}^{\ensuremath{'}})$ reaction was found to produce fewer $\ensuremath{\gamma}$ rays associated with transitions involving high spin states $(J=6--8\phantom{\rule{4.pt}{0ex}}\ensuremath{\hbar})$ than the other two reactions, suggesting that inelastic scattering preferentially populates states in $^{90}\mathrm{Zr}$ that have lower spins than those populated in the transfer reactions investigated. The $\ensuremath{\gamma}$-ray production was also observed to vary by factors of 2--3 with the angle at which the outgoing particle was detected. These findings are relevant to the application of the surrogate reaction approach.
Databáze: OpenAIRE