Related papers: UCN production by multiphonon processes in superfl…
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…
It is generally accepted that the main cause of ultracold neutron (UCN) losses in storage traps is the upscattering to the thermal energy range by hydrogen adsorbed on the surface of the trap walls. However, the data on which this…
We installed a source for ultracold neutrons at a new, dedicated spallation target at TRIUMF. The source was originally developed in Japan and uses a superfluid-helium converter cooled to 0.9$\,$K. During an extensive test campaign in…
We consider ultracold neutron (UCN) sources based on a new method of UCN production in superfluid helium (4He). The PIK reactor is chosen as a perspective example of the application of this idea, which consists of installing a 4He UCN…
The WWR-M reactor of PNPI offers a unique opportunity to prepare a source for ultracold neutrons (UCN) in an environment of high neutron flux (about 3*10^12 n/cm^2/s) at still acceptable radiation heat release (about 4*10^-3 W/g). It can be…
The paper considers the concept of an ultracold neutron source (UCN) based on the deceleration of very cold neutrons (VCN) by a local decelerating device. As the latter, it is proposed to use a gradient spin flipper. It is shown that in…
Efficient neutron transport is a key ingredient to the performance of ultracold neutron (UCN) sources, important to meeting the challenges placed by high precision fundamental physics experiments. At the Paul Scherrer Institute's UCN source…
The work presented in this thesis forms part of a program at the Paul Scherrer Institute (PSI) to construct a high intensity superthermal ultra-cold neutron (UCN) source based on solid deuterium as UCN production medium. We carried out a…
We present the concept of the ultracold neutron (UCN) source with a superfluid helium-4 converter located in the thermal column of the WWR-K research reactor at the Institute of Nuclear Physics (INP) in Almaty, Kazakhstan. The conceptual…
The general theory of neutron scattering is presented, valid for the whole domain of slow neutrons from thermal to ultracold. Particular attention is given to multiple scattering which is the dominant process for ultracold neutrons (UCN).…
Ultracold neutrons (UCN) can be stored in suitable bottles and observed for several hundreds of seconds. Therefore UCN can be used to study in detail the fundamental properties of the neutron. A new user facility providing ultracold…
Solid deuterium (sD_2) is used as an efficient converter to produce ultracold neutrons (UCN). It is known that the sD_2 must be sufficiently cold, of high purity and mostly in its ortho-state in order to guarantee long lifetimes of UCN in…
The physics model of a next-generation spallation-driven high-current ultracold neutron (UCN) source capable of delivering an extracted UCN rate of around an-order-of-magnitude higher than the strongest proposed sources, and around…
Commissioning of the new high-intensity ultracold neutron (UCN) source at the Paul Scherrer Institut (PSI) has started in 2009. The design goal of this new generation high intensity UCN source is to surpass by a factor of ~100 the current…
We have investigated solid oxygen as a converter material for the production of ultra-cold neutrons. In a first series of experiments the crystal preparation was examined. An optically semi-transparent solid $\alpha$-oxygen crystal has been…
We report on our efforts to optimize the geometry of neutron moderators and converters for the TRIUMF UltraCold Advanced Neutron (TUCAN) source using MCNP simulations. It will use an existing spallation neutron source driven by a 19.3 kW…
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…
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…
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,…
We present the first measurements of the survival time of ultracold neutrons (UCNs) in solid deuterium SD2. This critical parameter provides a fundamental limitation to the effectiveness of superthermal UCN sources that utilize solid…