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Nuclear Spectroscopy in Cr 52 , Cr 53 , and<mml:math …

1967; American Institute of Physics; Volume: 156; Issue: 4 Linguagem: Inglês

10.1103/physrev.156.1228

1536-6065

C. Whitten,

Nuclear Physics and Applications

The ${\mathrm{Cr}}^{54}(p,d)$ and ${\mathrm{Cr}}^{54}(p,t)$, ${\mathrm{Cr}}^{53}(p,d)$ and ($p,t$), ${\mathrm{Cr}}^{53}(p,{p}^{\ensuremath{'}})$, and ${\mathrm{Cr}}^{52}(p,t)$ reactions were studied with 17.5-MeV protons from the Princeton FM cyclotron. Thin, essentially self supported, isotopic chromium foils were used in these experiments, the deuterons and tritons being identified by a $\frac{\mathrm{dE}}{\mathrm{dx}}\ensuremath{-}E$ solid-state-detector telescope. The total experimental resolution of this system for the various deuteron and triton groups was between 55 and 70 keV. Angular distributions for many ($p,d$), ($p,t$), and ($p,{p}^{\ensuremath{'}}$) transitions were obtained from 15\ifmmode^\circ\else\textdegree\fi{} to 150\ifmmode^\circ\else\textdegree\fi{}. Spectroscopic factors were determined for ${l}_{n}=0,1,2,\mathrm{and} 3$ ($p,d$) transitions, using distorted-wave Born-approximation calculations which included both finite-range and nonlocal effects. In the ${\mathrm{Cr}}^{53}(p,d)$ reaction, both the ${0}^{+}$ ground state and the 1.434-MeV ${2}^{+}$ level in ${\mathrm{Cr}}^{52}$ were excited by ${l}_{n}=1$ transitions, showing admixture in the ${\mathrm{Cr}}^{53}$ ground state of the configuration ${{{({\mathrm{Cr}}^{52} 1.434 \mathrm{MeV})}^{{2}^{+}}2{p}_{\frac{3}{2}}}}^{\frac{3}{2}}$. Levels in ${\mathrm{Cr}}^{52}$ and ${\mathrm{Cr}}^{53}$ were strongly, excited in the ($p,d$) reaction with ${l}_{n}=3$ angular distributions, and these transitions are ascribed to $1{f}_{\frac{7}{2}}$ pickup. In the ${\mathrm{Cr}}^{54}(p,d){\mathrm{Cr}}^{53}$ reaction, definite $J$ dependence was observed in both ${l}_{n}=1$ ($J=\frac{1}{2} or \frac{3}{2}$) and ${l}_{n}=3$ ($J=\frac{5}{2} or \frac{7}{2}$) transitions. A single ${l}_{n}=0$ transition was found in the ${\mathrm{Cr}}^{54}(p,d)$ reaction which seems to exhaust most of the ${T}_{<}$ spectroscopic strength. The ${\mathrm{Cr}}^{54,53,52}(p,t)$ experiments along with the ${\mathrm{Cr}}^{53}(p,d)$ work indicate that a large component of the 2.648-MeV ${0}^{+}$ level in ${\mathrm{Cr}}^{52}$ is a two-particle-two-hole neutron configuration. In the ${\mathrm{Cr}}^{53}(p,{p}^{\ensuremath{'}})$ reaction, the 0.563-MeV ${\mathrm{\textonehalf{}}}^{\ensuremath{-}}$, 1.001-MeV ${\frac{5}{2}}^{\ensuremath{-}}$, 1.284-MeV ${\frac{7}{2}}^{\ensuremath{-}}$, and 1.967-MeV levels were strongly excited, and their angular distributions are similar to that of the ${\mathrm{Cr}}^{52}(p,{p}^{\ensuremath{'}}){\mathrm{Cr}}^{52}$ 1.434-MeV ${2}^{+}$ transition. The results of the ${\mathrm{Cr}}^{54}(p,d)$, ${\mathrm{Cr}}^{53}(p,d)$, and ${\mathrm{Cr}}^{53}(p,{p}^{\ensuremath{'}})$ experiments are used in conjunction with the weak-coupling model and the theoretical model calculations of Maxwell and Parkinson and of Ramavataram to discuss the structure of the low-lying levels of ${\mathrm{Cr}}^{53}$.