Level density of ${}^{56}$Fe and low-energy enhancement of $\gamma$-strength function

Abstract

The ${}^{55}$Mn$(d,n{)}^{56}$Fe differential cross section is measured at $E_d=7$ MeV\@. The ${}^{56}$Fe level density obtained from neutron evaporation spectra is compared to the level density extracted from the ${}^{57}$Fe${(}^3$He,$\alpha \gamma {)}^{56}$Fe reaction by the Oslo-type technique. Good agreement is found between the level densities determined by the two methods. With the level density function obtained from the neutron evaporation spectra, the ${}^{56}$Fe $\gamma$-strength function is also determined from the first-generation $\gamma$ matrix of the Oslo experiment. The good agreement between the past and present results for the $\gamma$-strength function supports the validity of both methods and is consistent with the low-energy enhancement of the $\gamma$ strength below $\sim 4$ MeV first discovered by the Oslo method in iron and molybdenum isotopes.

7 pages, 5 figures

References in corpus (6)

• Extraction of level density and gamma strength function from primary gamma spectra
• Radiative strength functions in 93-98Mo
• Large enhancement of radiative strength for soft transisitons in the quasicontinuum
• Thermal properties and radiative strengths in 160,161,162Dy
• Evolution of level density step structures from 56,57-Fe to 96,97-Mo
• Level density and gamma strength function in 162-Dy from inelastic 3-He scattering

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• Novel Techniques for Constraining Neutron-Capture Rates Relevant for r-Process Heavy-Element Nucleosynthesis
• Thermodynamic Properties of ${}^{56,57}$Fe
• Test of nuclear level density inputs for Hauser-Feshbach model calculations
• Statistical structure and $\gamma$-decay properties of closed shell Pb nuclei
• Systematics of strength function sum rules
• Low-energy enhancement and fluctuations of $\gamma$-ray strength functions in ${}^{56,57}$Fe: test of the Brink-Axel hypothesis
• Experimental signature of collective enhancement in nuclear level density
• Transition sum rules in the shell model
• Spin distribution of nuclear levels using static path approximation with random-phase approximation
• Nuclear level density of ${}^{69}$Zn from gamma gated particle spectrum and its implication on ${}^{68}$Zn(n, $\gamma$)${}^{69}$Zn capture cross-section