Related papers: Neutron reflection from the surface of normal and …
The puzzle remains in the large discrepancy between neutron lifetime measured by the two distinct experimental approaches -- counts of beta decays in a neutron beam and storage of ultracold neutrons in a potential trap, namely, the beam…
Neutrinos give a novel probe to explore deep interior of astrophysical objects, which otherwise is not accessible with optical observations; among notable examples are solar and supernova neutrinos. We show that there is a new class of…
We have studied natural purity $^{4}$He single crystals and polycrystals between 10 and 600 mK using a torsional oscillator with a 2 cm$^{3}$ rigid cell made of sapphire with a smooth geometry. As the temperature was lowered, we observed…
We have performed a single crystal neutron scattering experiment on Ce0.7La0.3B6 to investigate the order parameter of phase IV microscopically. Below the phase transition temperature 1.5 K of phase IV, weak but distinct superlattice…
Using simple arguments based on photometric light curves and velocity evolution, we propose that some stripped envelope supernovae (SNe) show signs that a significant fraction of their helium is effectively transparent. The main pieces of…
Path Integral Monte Carlo calculations of the superfluid density throughout ^4He droplets doped with linear impurities (HCN)_n are presented. After deriving a local estimator for the superfluid density distribution, we find a decreased…
Surface waves on both superfluid 3He and 4He were examined with the premise, that these inviscid media would represent ideal realizations for this fluid dynamics problem. The work on 3He is one of the first of its kind, but on 4He it was…
We have performed quantum Monte Carlo simulations measuring the finite size and temperature superfluid response of helium-4 to the linear and rotational motion of the walls of a nanopore. Within the two-fluid model, the portion of the…
Electrons can be reflected at an interface between two metals because of a dielectric barrier or different properties of the Fermi surface. Andreev reflection allows to directly measure normal reflection when one of the metals is a…
Ultracold neutrons (UCNs) were produced in a 4 liter volume of superfluid helium using the PF1B cold neutron beam facility at the Institut Laue-Langevin and then extracted to a detector at room temperature. With a converter temperature of…
We report here experimental evidence of the reflection of a large fraction of a beam of low energy antiprotons by an aluminum wall. This derives from the analysis of a set of annihilations of antiprotons that come to rest in rarefied helium…
The inelastic scattering of neutrino off 4He is calculated microscopically at energies typical for core collapse supernova environment. The calculation is carried out with the Argonne V18 nucleon--nucleon potential and the Urbana IX three…
Matter at low temperatures exhibits unusual properties such as superfluidity, superconductivity, Bose-Einstein condensation, and supersolidity. These states display quantum mechanical behaviours at scales much larger than atomic dimensions.…
Liquid helium 4 had been the only bosonic superfluid available in experiments for a long time. This situation was changed in 1995, when a new superfluid was born with the realization of the Bose-Einstein condensation in ultracold atomic…
Development of large mass detectors for low-energy neutrinos and dark matter may allow supernova detection via neutrino-nucleus elastic scattering. An elastic-scattering detector could observe a few, or more, events per ton for a galactic…
The scattering of atoms and rotons at the free surface of superfluid 4He is studied in the framework of linearised time dependent mean field theory. The phenomenological Orsay-Trento density functional is used to solve numerically the…
SuperSUN, a new superthermal source of ultracold neutrons (UCN) at the Institut Laue-Langevin, exploits inelastic scattering of neutrons in isotopically pure superfluid $^4$He at temperatures below $0.6\,$K. For the first time, continuous…
The wavelike processes of crystallisation and melting or crystallisation waves are well-known to exist at the crystal 4He surface in its rough state. Below the roughening transition temperature the crystal surface experiences the transition…
In specular reflection experiments the reflected beam from the end side of thick substrates is typically neglected. This is equivalent to assuming the substrates as semi-infinite matter. However, it is known that we should also consider the…
Speed plot and time delay analysis confirms a two-pole S-matrix structure of the lowest 3/2+ level in 5He. Real parts of neutron-alpha elastic and 4He(n,d)3H reaction pole energies are 17.669+/-0.006 and 17.705+/-0.001 MeV n-4He c.m.,…