Search results for " NEUTRON"

Transmission of very slow neutrons through material foils and its influence on the design of ultracold neutron sources

2009

At the Paul Scherrer Institute (PSI), a very intense source of ultracold neutrons (UCN) is being built. The UCN converter of solid deuterium must be contained in a vessel. Produced UCN leave that vessel through its top lid. To decide on the design of the vessel and the top lid, we have measured the transmission of neutrons with velocities between 3 and 20 m/s through different material foils. Contrary to expectations, we found that transmission through aluminium and aluminium alloys is equal or even higher compared to zirconium and reactor-grade zirconium alloys, respectively.

Observation of beta-delayed neutron decay to excited 0+ states in the residual nucleus: The case

1981

Abstract Beta-delayed neutron emission from 97 Rb to excited 0 + states in 96 Sr has been observed. The experimental branching ratios ( P n i ) are compared to predictions from a statistical model. It is demonstrated that, considering the influence of the strength of β -decay preceding neutron emission, the ( P n i ) reflect the different structure of the two excited 0 + states, in agreement with conclusions drawn from the measurement of their lifetimes.

Total absorption γ-ray spectroscopy of beta delayed neutron emitters

2013

Preliminary results of the data analysis of the beta decay of 94Rb using a novel - segmented- total absorption spectrometer are shown in this contribution. This result is part of a systematic study of important contributors to the decay heat problem in nuclear reactors. In this particular case the goal is to determine the beta intensity distribution below the neutron separation energy and the gamma/beta competition above.

Quasi-elastic electron-deuteron scattering and the electric form factor of the neutron

1978

Improved instrument for the determination of the neutron electric charge

2015

Abstract We present an improved instrument for the determination of the neutron electric charge with ultracold neutrons. Several technical upgrades with respect to a former experiment will be discussed in detail. As a first test, we applied the apparatus to investigate the influence of gravitational attraction by means of a massive block of lead. The calculated sensitivity for a charge measurement is δ q n ≈ 2.14 × 10 − 20 e / day . Planned modifications increasing the sensitivity up to δ q n ≈ 1.34 × 10 − 21 e / day are demonstrated.

Direct Experimental Verification of Neutron Acceleration by the Material Optical Potential of SolidH22

2008

We have measured the acceleration of neutrons by the material optical potential of solid $^{2}\mathrm{H}_{2}$. Using a gravitational spectrometer, we find a minimal kinetic energy ${E}_{c}=(99\ifmmode\pm\else\textpm\fi{}7)\text{ }\text{ }\mathrm{neV}$ of neutrons from a superthermal ultracold neutron (UCN) source with solid $^{2}\mathrm{H}_{2}$ as an UCN converter. The result is in excellent agreement with theoretical predictions, ${E}_{c}=106\text{ }\text{ }\mathrm{neV}$.

Ion implant-β-decay correlation half-lives in a pulsed beam for isotopes beyond N=126

2018

Half-lives and β-delayed neutron emission probabilities of several isotopes of Au, Hg, Tl, Pb and Bi, in the neutron-rich region around and beyond N=126, were determined in an experiment performed at the RIB facility of GSI [1]. These are decay properties that are directly related to the final abundance distribution of the elements due to their contribution during the freeze-out of the r-process nucleosynthesis. This contribution summarizes the main aspects of the analysis methodology followed for the determination of β-decay half-lives. The main particularities of the present analysis concern the characterization of the β-background, as well as the effect of the pulsed-beam in the ion-β ti…

Status of delayed-neutron precursor data: half-lives and neutron emission probabilities

2002

Abstract We present in this paper a compilation of the present status of experimental delayed-neutron precursor data; i.e. β-decay half-lives ( T 1/2 ) and neutron emission probabilities ( P n ) in the fission-product region (27 ≤ Z ≤ 57). These data are compared to two model predictions of substantially different sophistication: (i) an update of the empirical Kratz-Herrmann formula (KHF), and (ii) a unified macroscopic-microscopic model within the quasi-particle random-phase approximation (QRPA). Both models are also used to calculate so far unknown T 1/2 and P n values up to Z = 63. A number of possible refinements in the microscopic calculations are suggested to further improve the nucle…

Single-Neutron States inS133n

1996

The location of several single-neutron states in ${}^{133}\mathrm{Sn}$ has been identified. The ${p}_{3/2}$, ${h}_{9/2}$, and ${f}_{5/2}$ states were found at 853.7, 1560.9, and 2004.6 keV, respectively, by measuring $\ensuremath{\gamma}$ rays in coincidence with delayed neutrons following the decay of ${}^{134}\mathrm{In}$. Crucial for obtaining the new data were the improved yields at the mass-separator facility ISOLDE-PSB at CERN. A semiempirically adjusted Woods-Saxon calculation, based on parameters from the Pb region and normalized on the mass data at ${}^{132}\mathrm{Sn}$, reproduces the new single particle energies with good precision.

β-delayed neutron emission measurements around the third r-process abundance peak

2013

This contribution summarizes an experiment performed at GSI (Germany) in the neutron-rich region beyond N=126. The aim of this measurement is to provide the nuclear physics input of relevance for r-process model calculations, aiming at a better understanding of the third r-process abundance peak. Many exotic nuclei were measured around 211Hg and 215Tl. Final ion identification diagrams are given in this contribution. For most of them, we expect to derive halflives and and β-delayed neutron emission probabilities. The detectors used in this experiment were the Silicon IMplantation and Beta Absorber (SIMBA) detector, based on an array of highly segmented silicon detectors, and the BEta deLayE…