Restricted spin-range correction in the Oslo Method: The example of nuclear level density and $\gamma$-ray strength function from ${}^{239}\mathrm{Pu}(\mathrm{d},\mathrm{p}\gamma {)}^{240}\mathrm{Pu}$

Abstract

The Oslo Method has been applied to particle-$\gamma$ coincidences following the ${}^{239}\mathrm{Pu}$(d,p) reaction to obtain the nuclear level density (NLD) and $\gamma$-ray strength function ($\gamma$SF) of ${}^{240}\mathrm{Pu}$. The experiment was conducted with a 12 MeV deuteron beam at the Oslo Cyclotron Laboratory. The low spin transfer of this reaction leads to a spin-parity mismatch between populated and intrinsic levels. This is a challenge for the Oslo Method as it can have a significant impact on the extracted NLD and $\gamma$SF. We have developed an iterative approach to ensure consistent results even for cases with a large spin-parity mismatch, in which we couple Green's Function Transfer calculations of the spin-parity dependent population cross-section to the nuclear decay code RAINIER. The resulting $\gamma$SF shows a pronounced enhancement between 2-4 MeV that is consistent with the location of the low-energy orbital $M1$ scissors mode.

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Cited by in corpus (4)

• Nuclear level densities and $\gamma$-ray strength functions in ${}^{120,124}$Sn isotopes: impact of Porter-Thomas fluctuations
• Statistical properties of the well deformed ${}^{153,155}$Sm nuclei and the scissors resonance
• A new software implementation of the Oslo method with rigorous statistical uncertainty propagation
• Correlations between energy and $\gamma$-ray emission in ${}^{239}\mathrm{Pu}(n,\mathrm{f})$