New experimental constraint on the ${}^{185}$W($n,\gamma$)${}^{186}$W cross section

Abstract

In this work, we present new data on the ${}^{182,183,184}$W($\gamma ,n$) cross sections, utilizing a quasi-monochromatic photon beam produced at the NewSUBARU synchrotron radiation facility. Further, we have extracted the nuclear level density and $\gamma$-ray strength function of ${}^{186}$W from data on the ${}^{186}$W($\alpha ,{\alpha }^{\prime }\gamma$)${}^{186}$W reaction measured at the Oslo Cyclotron Laboratory. Combining previous measurements on the ${}^{186}$W($\gamma ,n$) cross section with our new ${}^{182,183,184}$W($\gamma ,n$) and ($\alpha ,{\alpha }^{\prime }\gamma$)${}^{186}$W data sets, we have deduced the ${}^{186}$W $\gamma$-ray strength function in the range of $1<E_{\gamma }<6$ MeV and $7<E_{\gamma }<14$ MeV. Our data are used to extract the level density and $\gamma$-ray strength functions needed as input to the nuclear-reaction code \textsf{TALYS}, providing an indirect, experimental constraint for the ${}^{185}$W($n,\gamma$)${}^{186}$W cross section and reaction rate. Compared to the recommended Maxwellian-averaged cross section (MACS) in the KADoNiS-1.0 data base, our results are on average lower for the relevant energy range $k_{B}T\in [5,100]$ keV, and we provide a smaller uncertainty for the MACS. The theoretical values of Bao \textit{et al.} and the cross section experimentally constrained on photoneutron data of Sonnabend \textit{et al.} are significantly higher than our result. The lower value by Mohr \textit{et al.} is in very good agreement with our deduced MACS. Our new results could have implications for the $s$-process and in particular the predicted $s$-process production of ${}^{186,187}$Os nuclei.

17 pages, 15 figures; to be submitted to Phys. Rev. C

References in corpus (9)

• The r-process of stellar nucleosynthesis: Astrophysics and nuclear physics achievements and mysteries
• Analysis of possible systematic errors in the Oslo method
• The SiRi Particle-Telescope System
• Large low-energy $M1$ strength for ${}^{56,57}$Fe within the nuclear shell model
• Modification of the Brink-Axel Hypothesis for High Temperature Nuclear Weak Interactions
• s-process branching at 185W revised
• Comprehensive test of nuclear level density models
• Spectral distribution and flux of $\gamma$-ray beams produced through Compton scattering of unsynchronized laser and electron beams
• Monte Carlo simulation method of polarization effects in Laser Compton Scattering on relativistic electrons

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