Mon·May 2, 2022Monday·May 2, 2022

1. 01*

   The fast neutron induced fission of ${}^{240}$Pu and ${}^{242}$Pu

   A. Pica · A.T.Chemey🇺🇸 · W. Loveland🇺🇸

   We report the measurement of the TKE release in the fast neutron induced fission of ${}^{240}$Pu and ${}^{242}$Pu. The results are compared to the predictions of the GEF model, the CGMF model, and the model of Denisov and Sedykh as well as previous experimental work on these reactions. Our absolute measurements of the TKE release are in good agreement with the previous measurements of Nethaway \textit{et al.} for the interaction of 14.8 MeV neutrons with ${}^{240}$Pu \cite{Nethaway} and of Winkelmann and Aumann for the interaction of 15 MeV neutrons with ${}^{242}$Pu \cite{Winkelmann}. The general trends of the measured TKE values agree with phenomenological models but the variances of the TKE distributions are significantly less than predicted by various models. The mean post neutron emission TKE release decreases non- linearly with increasing neutron energy and can be represented as TKE(MeV) = 175.8 $\pm$ 0.3 - (2. 4 $\pm$ 0.8)log${}_{10}$E${}_n$ - (1.4 $\pm$0.4)log${}_{10}$E${}_n^2$ for ${}^{240}$Pu and TKE(MeV) = 177.1 $\pm$ 0.3 - (1.2 $\pm$ 0.9)log${}_{10}$E${}_n$ - (1.8 $\pm$0.5)log${}_{10}$E${}_n^2$ for ${}^{242}$Pu.

   nucl-exnucl-thPRC(2022)·5 citations
2. 02*

   Long-term evolution of the neutron rate at the Canfranc Underground Laboratory

   S.E.A. Orrigo🇪🇸 · J.L. Tain🇪🇸 · N. Mont-Geli🇪🇸 · A. Tarifeño-Saldivia🇪🇸 · L.M. Fraile🇪🇸 · M. Grieger🇩🇪 · J. Agramunt🇪🇸 · A. Algora🇪🇸 · D. Bemmerer🇩🇪 · F. Calviño🇪🇸 · G. Cortés🇪🇸 · A. De Blas🇪🇸 and 5 other authors

   We report results on the long-term variation of the neutron counting rate at the Canfranc Underground Laboratory, of importance for several low-background experiments installed there, including rare-event searches. The measurement campaign was performed employing the High Efficiency Neutron Spectrometry Array (HENSA) mounted in Hall A and lasted 412 live days. The present study is the first long-term measurement of the neutron rate with sensitivity over a wide range of neutron energies (from thermal up to 0.1 GeV and beyond) performed in any underground laboratory so far. Data on the environmental variables inside the experimental hall (radon concentration, air temperature, air pressure and humidity) were also acquired during all the measurement campaign. We have investigated for the first time the evolution of the neutron rate for different energies of the neutrons and its correlation with the ambient variables.

   nucl-exhep-exEPJC(2022)·8 citations
3. 03*

   Nuclear equation of state for arbitrary proton fraction and temperature based on chiral effective field theory and a Gaussian process emulator

   J. Keller🇩🇪 · K. Hebeler🇩🇪 · A. Schwenk🇩🇪

   We calculate the equation of state of asymmetric nuclear matter at finite temperature based on chiral effective field theory interactions to next-to-next-to-next-to-leading order. Our results assess the theoretical uncertainties from the many-body calculation and the chiral expansion. Using a Gaussian process emulator for the free energy, we derive the thermodynamic properties of matter through consistent derivatives and use the Gaussian process to access arbitrary proton fraction and temperature. This enables a first nonparametric calculation of the equation of state in beta equilibrium, and of the speed of sound and the symmetry energy at finite temperature. Moreover, our results show that the thermal part of the pressure decreases with increasing densities.

   ↳ nucl-thastro-ph.HEnucl-exPRL(2023)·117 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.