Preliminary results on the 233U capture cross section and alpha ratio measured at n_TOF (CERN) with the fission tagging technique

233U is of key importance among the fissile nuclei in the Th-U fuel cycle. A particularity of 233U is its small neutron capture cross-section, which is on average about one order of magnitude lower than the fission cross-section.The accuracy in the measurement of the 233U capture cross-section depends crucially onan efficient capture-fission discrimination, thus a combined set-up of fission and ¿-detectors is needed. A measurement of the 233U capture cross-section and capture-to-fissionratio was performed at the CERN n_TOF facility. The Total Absorption Calorimeter (TAC) of n_TOF was employed as ¿-detector coupled with a novel compact ionization chamber as fission detector. A brief description of the experimental set-up will be given, and essential parts of the analysis procedure as well as the preliminary response of the set-up to capture are presented and discussedPostprint (published version

Towards high accurate neutron-induced fission cross sections of 240,242Pu: Spontaneous fission half-lives

Fast spectrum neutron-induced fission cross sections of transuranic isotopes are being of special demand in order to provide accurate data for the new GEN-IV nuclear power plants. To minimize the uncertainties on these measurements accurate data on spontaneous fission half-lives and detector efficiencies are a key point. High -active actinides need special attention since the misinterpretation of detector signals can lead to low efficiency values or underestimation in fission fragment detection. In that context, 240,242Pu isotopes have been studied by means of a Twin Frisch-Grid Ionization Chamber (TFGIC) for measurements of their neutron-induced fission cross section. Gases with different drift velocities have been used, namely P10 and CH4. The detector efficiencies for both samples have been determined and improved spontaneous fission half-life values were obtained.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Sensitivity of seismically cued antineutrino detectors to nuclear explosions

We evaluate the sensitivity of large, gadolinium-doped water detectors to antineutrinos released by nuclear fission explosions, using updated signal and background models and taking advantage of the capacity for seismic observations to provide an analysis trigger. Under certain realistic conditions, the antineutrino signature of a 250-kiloton pure fission explosion could be identified several hundred kilometers away in a detector about the size of the largest module currently proposed for a basic physics experiment. In principle, such an observation could provide rapid confirmation that the seismic signal coincided with a fission event, possibly useful for international monitoring of nuclear weapon tests. We discuss the limited potential for seismically cued antineutrino observations to constrain fission yield, differentiate pure fission from fusion-enhanced weapon tests, indicate that the seismic evidence of an explosion had been intentionally masked, or verify the absence of explosive testing in a targeted area. We conclude that advances in seismic monitoring and neutrino physics have made the detection of explosion-derived antineutrinos more conceivable than previously asserted, but the size and cost of sufficiently sensitive detectors continue to limit applications

Antineutrino flux from the Laguna Verde Nuclear Power Plant

We present a calculation of the antineutrino flux produced by the reactors at the Laguna Verde Nuclear Power Plant in M\'exico, based on the antineutrino spectra produced in the decay chains of the fission fragments of the main isotopes in the reactor core, and their fission rates, that have been calculated using the DRAGON simulation code. We also present an estimate of the number of expected events in a detector made of plastic scintillator with a mass of 1 ton, at 100 m from the reactor cores.Comment: 15 pages, 8 figures, 4 table

A compact fission detector for fission-tagging neutron capture experiments with radioactive fissile isotopes

In the measurement of neutron capture cross-sections of fissile isotopes, the fission channel is a source of background which can be removed efficiently using the so-called fission-tagging or fission-veto technique. For this purpose a new compact and fast fission chamber has been developed. The design criteria and technical description of the chamber are given within the context of a measurement of the 233U(n, ) cross-section at the n_TOF facility at CERN, where it was coupled to the n_TOF Total Absorption Calorimeter. For this measurement the fission detector was optimized for time resolution, minimization of material in the neutron beam and for alpha-fission discrimination. The performance of the fission chamber and its application as a fission tagging detector are discussed.French NEEDS/NACRE ProjectEuropean Commission within HORIZON2020 via the EURATOM Project EUFRA

A compact fission detector for fission-tagging neutron capture experiments with radioactive fissile isotopes

© 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).In the measurement of neutron capture cross-sections of fissile isotopes, the fission channel is a source of background which can be removed efficiently using the so-called fission-tagging or fission-veto technique. For this purpose a new compact and fast fission chamber has been developed. The design criteria and technical description of the chamber are given within the context of a measurement of the 233U(n, γ) cross-section at the n_TOF facility at CERN, where it was coupled to the n_TOF Total Absorption Calorimeter. For this measurement the fission detector was optimized for time resolution, minimization of material in the neutron beam and for alpha-fission discrimination. The performance of the fission chamber and its application as a fission tagging detector are discussed.Peer reviewe