New experimental constraint on the W-185(n, & gamma;) W-186 cross section

Abstract

In this work, we present new data on the 182,183,184W(& 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 186W from data on the 186W(& alpha;, & alpha;'& gamma; ) 186W reaction measured at the Oslo Cyclotron Laboratory. Combining previous measurements on the 186W(& gamma; , n) cross section with our new 182,183,184W(& gamma; , n) and (& alpha;, & alpha;'& gamma; ) 186W data sets, we have deduced the 186W & 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 TALYS, providing an indirect, experimental constraint for the 185W(n, & gamma; ) 186W cross section and reaction rate. Compared to the recommended Maxwellian-averaged cross section (MACS) in the KADoNiS-1.0 database, our results are on average lower for the relevant energy range kBT & ISIN; [5, 100] keV, and we provide a smaller uncertainty for the MACS. The theoretical values of Bao et al. [At. Data Nucl. Data Tables 76, 70 (2000)] and the cross section experimentally constrained on photoneutron data of Sonnabend et al. [Astrophys. J. 583, 506 (2003)] are significantly higher than our result. The lower value ingredient in simulations for investigating the neutron density and the 186,187Os production in the s process.