Search results for "capture"
showing 10 items of 463 documents
Determining therp-Process Flow throughNi56: Resonances inCu57(p,γ)Zn58Identified with GRETINA
2014
An approach is presented to experimentally constrain previously unreachable (p, γ) reaction rates on nuclei far from stability in the astrophysical rp process. Energies of all critical resonances in the (57)Cu(p,γ)(58)Zn reaction are deduced by populating states in (58)Zn with a (d, n) reaction in inverse kinematics at 75 MeV/u, and detecting γ-ray-recoil coincidences with the state-of-the-art γ-ray tracking array GRETINA and the S800 spectrograph at the National Superconducting Cyclotron Laboratory. The results reduce the uncertainty in the (57)Cu(p,γ) reaction rate by several orders of magnitude. The effective lifetime of (56)Ni, an important waiting point in the rp process in x-ray burst…
Expected performance of an ideal liquid argon neutrino detector with enhanced sensitivity to scintillation light
2014
Scintillation light is used in liquid argon (LAr) neutrino detectors to provide a trigger signal, veto information against cosmic rays, and absolute event timing. In this work, we discuss additional opportunities offered by detectors with enhanced sensitivity to scintillation light, that is with light collection efficiencies of about $10^{-3}$. We focus on two key detector performance indicators for neutrino oscillation physics: calorimetric neutrino energy reconstruction and neutrino/antineutrino separation in a non-magnetized detector. Our results are based on detailed simulations, with neutrino interactions modelled according to the GENIE event generator, while the charge and light respo…
Muon capture on light isotopes measured with the Double Chooz detector
2016
Using the Double Chooz detector, designed to measure the neutrino mixing angle $\theta_{13}$, the products of $\mu^-$ capture on $^{12}$C, $^{13}$C, $^{14}$N and $^{16}$O have been measured. Over a period of 489.5 days, $2.3\times10^6$ stopping cosmic $\mu^-$ have been collected, of which $1.8\times10^5$ captured on carbon, nitrogen, or oxygen nuclei in the inner detector scintillator or acrylic vessels. The resulting isotopes were tagged using prompt neutron emission (when applicable), the subsequent beta decays, and, in some cases, $\beta$-delayed neutrons. The most precise measurement of the rate of $^{12}\mathrm C(\mu^-,\nu)^{12}\mathrm B$ to date is reported: $6.57^{+0.11}_{-0.21}\time…
The Extremely Metal‐poor, Neutron Capture–rich Star CS 22892‐052: A Comprehensive Abundance Analysis
2003
High-resolution spectra obtained with three ground-based facilities and the Hubble Space Telescope (HST) have been combined to produce a new abundance analysis of CS 22892-052, an extremely metal-poor giant with large relative enhancements of neutron-capture elements. A revised model stellar atmosphere has been derived with the aid of a large number of Fe-peak transitions, including both neutral and ionized species of six elements.Several elements, including Mo, Lu, Au, Pt and Pb, have been detected for the first time in CS 22892-052, and significant upper limits have been placed on the abundances of Ga, Ge, Cd, Sn, and U in this star. In total, abundance measurements or upper limits have b…
Discovery of an Exceptionally Strong β -Decay Transition of F20 and Implications for the Fate of Intermediate-Mass Stars
2019
A significant fraction of stars between 7 and 11 solar masses are thought to become supernovae, but the explosion mechanism is unclear. The answer depends critically on the rate of electron capture on ^{20}Ne in the degenerate oxygen-neon stellar core. However, because of the unknown strength of the transition between the ground states of ^{20}Ne and ^{20}F, it has not previously been possible to fully constrain the rate. By measuring the transition, we establish that its strength is exceptionally large and that it enhances the capture rate by several orders of magnitude. This has a decisive impact on the evolution of the core, increasing the likelihood that the star is (partially) disrupte…
Near-threshold $\pi^-$ photoproduction on the deuteron
2018
The first experimental investigation of the near-threshold cross section for incoherent $\pi^-$ photoproduction on the deuteron $\gamma$ d -> $\pi^-$ pp is presented. The experimental technique involved detection of the ~131 MeV gamma ray resulting from the radiative capture of photoproduced $\pi^-$ in the target. The total cross section has been measured using an unpolarized tagged-photon beam, a liquid-deuterium target, and three very large NaI(Tl) spectrometers. The data are compared to theoretical models that give insight into the elementary reaction $\gamma$ n -> $\pi^-$ p and pion-nucleon and nucleon-nucleon final-state interactions.
Towards Laser Spectroscopy of Superheavy Elements
2016
The sensitivity of laser spectroscopic methods has been increased over the past two decades dramatically so that today the spectroscopy of superheavy elements appears on the horizon as a realistic option. For elements with Z > 100 no experimental atomic or ionic level structure information is known so far. These elements cannot be bread in high flux nuclear power reactors via successive neutron capture and \(\beta ^-\) decay but must be produced in accelerator-based nuclear fusion-evaporation reactions. Laser spectroscopic investigations at low rates take advantage of the storage of ions or atoms in rare gas traps. A first successful experiment was conducted only recently for the element no…
High performance 3D CZT spectro-imager for BNCT-SPECT: preliminary characterization
2018
The National Institute of Nuclear Physics (INFN) is supporting the 3CaTS project with the aim of developing a new Single Photon Emission Computed Tomography (SPECT) system for real time 10 B therapeutic dose monitoring in the binary experimental hadron therapy called Boron Neutron Capture Therapy (BNCT). BNCT is a highly selective tumour treatment based on the neutron capture reaction 10 B(n,α) 7 Li. The secondary particles have a high LET with ranges in tissues of the order of 10 μm (thus less than the mean cell diameter of few tens μm). Targeting the 10 B delivery towards cancer, the released energy lethally damages only the malignant cells sparing the normal tissues, thus enabling a cell…
Potentialities of High-Resolution 3-D CZT Drift Strip Detectors for Prompt Gamma-Ray Measurements in BNCT
2022
Recently, new high-resolution cadmium–zinc–telluride (CZT) drift strip detectors for room temperature gamma-ray spectroscopic imaging were developed by our group. The CZT detectors equipped with orthogonal anode/cathode collecting strips, drift strips and dedicated pulse processing allow a detection area of 6 × 20 mm2 and excellent room temperature spectroscopic performance (0.82% FWHM at 661.7 keV). In this work, we investigated the potentialities of these detectors for prompt gamma-ray spectroscopy (PGS) in boron neutron capture therapy (BNCT). The detectors, exploiting the measurement of the 478 keV prompt gamma rays emitted by 94% 7Li nuclides from the 10B(n, α)7…
Networks to State Capture: Business Elite Networks and Mechanisms of Corporate State Capture in Central American Countries
2017
This paper aims to find out what configuration of business elite networks enables corporate state capture. To achieve this goal, it first uncovers and analyses business elite networks through interlocking directorates in three Central American countries using network analysis, and second, analyses the relationship between business elite networks and the mechanisms that enable corporations to capture states: namely revolving doors and the funding of political parties in the 2014 elections. Findings indicate that when some of the business elites configure a large and cohesive networked business community, while the rest is fragmented, corporate state capture is more likely to occur, as in the…