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We have investigated the diffuse reflection probabilities of Replica guides for ultra-cold neutrons (UCN) using the so-called helium method. For the first time we could establish a consistent description of the diffuse reflection mechanism…

Instrumentation and Detectors · Physics 2017-01-27 S. Wlokka , P. Fierlinger , A. Frei , P. Geltenbort , S. Paul , T. Pöschl , F. Schmid , W. Schreyer , D. Steffen

The transparency of metal foils for ultracold neutrons (UCNs) plays an important role in the design of future high-density UCN sources, which will feed a number of fundamental physics experiments. In this work, we describe and discuss the…

Nuclear Experiment · Physics 2021-01-13 Stefan Döge , Jürgen Hingerl , Egor V. Lychagin , Christoph Morkel

Neutrino transport and neutrino-matter interactions are known to play an important role in the evolution of neutron star mergers, and of their post-merger remnants. Neutrinos cool remnants, drive post-merger winds, and deposit energy in the…

High Energy Astrophysical Phenomena · Physics 2021-11-18 Francois Foucart , Matthew D. Duez , Francois Hebert , Lawrence E. Kidder , Phillip Kovarik , Harald P. Pfeiffer , Mark A. Scheel

We analyze accumulation of ultracold neutrons (UCN) in a superfluid-helium converter vessel surrounded by a magnetic multipole reflector. We solved the spin-dependent rate equation, employing formulas valid for adiabatic spin transport of…

Instrumentation and Detectors · Physics 2015-03-05 O. Zimmer , R. Golub

Ultracold neutrons (UCN) are free neutrons that can be stored in experimental setups for several minutes. Some of the most important properties of the neutron, such as its tiny permanent electric dipole moment and its beta decay lifetime,…

Nuclear Experiment · Physics 2020-06-09 Klaus Kirch , Bernhard Lauss

Ultracold neutrons (UCNs) are key for precision studies of fundamental parameters of the neutron and in searches for new CP violating processes or exotic interactions beyond the Standard Model of particle physics. The most prominent example…

The dynamical structure factor of solid $^{15}$N$_{2}$ in the $\alpha$ phase ($T<35$K) is measured at the IN4 time-of-flight spectrometer at the Institut Laue Langevin, and the potential performance of this substance as a UCN converter is…

Nuclear Experiment · Physics 2015-06-16 D. J. Salvat , E. Gutsmiedl , C. -Y. Liu , P. Geltenbort , A. Orecchini , S. Paul , H. Schober

This paper presents a calculation of the neutron cross-sections in solid materials (used in practical neutron sources) with a large coherent scattering contribution. In particular, the dynamic structure function S(Q, $\omega$) of…

Nuclear Theory · Physics 2010-05-07 C. -Y. Liu , A. R. Young , C. M. Lavelle , D. Salvat

The small energy exchange via nucleon recoils in neutrino-nucleon scattering is now supposed to be one of the important factors for successful explosion of core-collapse supernovae (CCSNe) as they can change neutrino spectra through…

High Energy Astrophysical Phenomena · Physics 2020-07-08 Chinami Kato , Hiroki Nagakura , Yusuke Hori , Shoichi Yamada

Neutrino-matter interactions play an important role in the post-merger evolution of neutron star-neutron star and black hole-neutron star mergers. Most notably, they determine the properties of the bright optical/infrared transients…

High Energy Astrophysical Phenomena · Physics 2018-09-19 Francois Foucart , Matthew D. Duez , Lawerence E. Kidder , Ronny Nguyen , Harald P. Pfeiffer , Mark A. Scheel

An open source software package for simulating thermal neutron propagation in geometry is presented. In this system, neutron propagation can be treated by either the particle transport method or the ray-tracing method. Supported by an…

Computational Physics · Physics 2023-12-05 Zi-Yi Pan , Ni Yang , Ming Tang , Peixun Shen , Xiao-Xiao Cai

The ultracold neutron (UCN) upscattering rate from para-deuterium contaminated solid deuterium near T=0K is calculated and found to be 4 msec for a room-temperature-equilibrium concentration. The para-deuterium contamination appears to be…

Nuclear Experiment · Physics 2007-05-23 C. -Y. Liu , A. R. Young , S. K. Lamoreaux

Precision measurements of neutron properties, like its permanent electric dipole moment, rely on understanding complex experimental setups in detail. We show how the properties of stored and transported ultracold neutron ensembles can be…

Neutron lifetime is a critical parameter in the Standard Model. Its measurements using, particularly, the beamline and ultracold neutron storage techniques reveals serious tension. The status of the tension between various measurements have…

Nuclear Experiment · Physics 2024-01-22 Prajwal Mohanmurthy , Joseph Formaggio , Daniel J. Salvat , Jeff A. Winger

Neutral-current neutrino scattering from the deuteron leading to proton-neutron final states is considered using an approach that incorporates relativistic dynamics and consequently provides robust modeling at relatively high energies and…

Nuclear Theory · Physics 2020-07-01 Sabine Jeschonnek , J. W. Van Orden , T. W. Donnelly

We study the neutrino distributions that arise in a simulation of a neutron star merger that uses a Monte Carlo (MC) neutrino transport scheme. In a snapshot taken 1 ms after merger, we calculate relevant observables to test when neutrinos…

High Energy Astrophysical Phenomena · Physics 2026-03-10 Mark G. Alford , Liam Brodie , Francois Foucart , Alexander Haber

The aim of this short note is to present an option for a source of ultracold neutrons (UCNs), which could profit from the pulse time-structure of the future ESS spallation neutron source in Lund, and thus which could produce a very high UCN…

Instrumentation and Detectors · Physics 2014-05-30 Valery V. Nesvizhevsky

There are worldwide efforts to search for physics beyond the Standard Model of particle physics. Precision experiments using ultracold neutrons (UCN) require very high intensities of UCN. Efficient transport of UCN from the production…

Instrumentation and Detectors · Physics 2015-12-09 B. Blau , M. Daum , M. Fertl , P. Geltenbort , L. Goeltl , R. Henneck , K. Kirch , A. Knecht , B. Lauss , P. Schmidt-Wellenburg , G. Zsigmond

We present the results of numerical simulations of the dynamical behavior of trajectories of ultra cold neutrons (UCN) in a magnetic trap. The main goal of our simulations was to optimize the trap parameters in order to minimize the…

Nuclear Experiment · Physics 2007-05-23 Vyacheslav N. Gorshkov , Gennady P. Berman

Reliable predictions of weak rapid neutron capture ($\textit{r}$-process) abundances require a systematic treatment of nuclear physics uncertainties, especially neutron capture rates far from stability. We employ new neutron capture rates…