197 research outputs found

    Measurement of the <math><mrow><mmultiscripts><mi>Se</mi><mprescripts/><none/><mn>77</mn></mmultiscripts><mo>(</mo><mi>n</mi><mo>,</mo><mi>ő≥</mi><mo>)</mo></mrow></math> cross section¬†up to 200 keV at the n_TOF facility at CERN

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    International audienceThe Se77(n,ő≥) reaction is of importance for Se77 abundance during the slow neutron capture process in massive stars. We have performed a new measurement of the Se77 radiative neutron capture cross section¬†at the Neutron Time-of-Flight facility at CERN. Resonance capture kernels were derived up to 51 keV and cross sections¬†up to 200 keV. Maxwellian-averaged cross sections¬†were calculated for stellar temperatures between kT=5keV and kT=100keV, with uncertainties between 4.2% and 5.7%. Our results lead to substantial decreases of 14% and 19% in Se77 abundances produced through the slow neutron capture process in selected stellar models of 15M‚äô and 2M‚äô, respectively, compared to using previous recommendation of the cross section

    Improving Fission-product Decay Data for Reactor Applications: Part I -- Decay Heat

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    Effort has been expended to assess the relative merits of undertaking further decay-data measurements of the main fission-product contributors to the decay heat of neutron-irradiated fissile fuel and related actinides by means of Total Absorption Gamma-ray Spectroscopy (TAGS/TAS) and Discrete Gamma-ray Spectroscopy (DGS). This review has been carried out following similar work performed under the auspices of OECD/WPEC-Subgroup 25 (2005-2007) and the International Atomic Energy Agency (2010, 2014), and various highly relevant TAGS measurements completed as a consequence of such assessments. We present our recommendations for new decay-data evaluations, along with possible requirements for total absorption and discrete high-resolution gamma-ray spectroscopy studies that cover approximately 120 fission products and various isomeric states

    miniBELEN: A modular neutron counter for (, ) reactions

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    miniBELEN is a modular and transportable neutron moderated counter with a nearly flat neutron detection efficiency up to 10 MeV. Modularity implies that the moderator can be reassembled in different ways in order to obtain different types of response. The detector has been developed in the context of the Measurement of Alpha Neutron Yields (MANY) collaboration, which is a scientific effort aiming to carry out measurements of (, ) production yields, reaction cross-sections and neutron energy spectra. In this work we present and discuss several configurations of the miniBELEN detector. The experimental validation of the efficiency calculations using 252Cf sources and the measurement of the 27Al(, ) 30P reaction is also presented

    Measurement of the neutron-induced fission cross section of <math><mmultiscripts><mi>Th</mi><mprescripts/><none/><mn>230</mn></mmultiscripts></math> at the CERN n_TOF facility

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    International audienceThe neutron-induced fission cross section of Th230 has been measured at the neutron time-of-flight facility n_TOF located at CERN. The experiment was performed at the experimental area EAR-1 with a neutron flight path of 185 m, using Micromegas detectors for the detection of the fission fragments. The Th230(n,f) cross section was determined relative to the U235(n,f) one, covering the energy range from the fission threshold up to 400 MeV. The results from the present work are compared with existing cross-section datasets and the observed discrepancies are discussed and analyzed. Finally, using the code empire 3.2.3 a theoretical study, based on the statistical model, was performed leading to a satisfactory reproduction of the experimental results with the proper tuning of the respective parameters, while for incident neutron energy beyond 200 MeV the fission of Th230 was described by Monte Carlo simulations

    Neutron-induced fission cross sections of <math><mmultiscripts><mi>Th</mi><mprescripts/><none/><mn>232</mn></mmultiscripts></math> and <math><mmultiscripts><mi mathvariant="normal">U</mi><mprescripts/><none/><mn>233</mn></mmultiscripts></math> up to 1 GeV using parallel plate avalanche counters at the CERN n_TOF facility

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    International audienceThe neutron-induced fission cross sections¬†of Th232 and U233 were measured relative to U235 in a wide neutron energy range up to 1 GeV (and from fission threshold in the case of Th232, and from 0.7¬†eV in case of U233), using the white-spectrum neutron source at the CERN Neutron Time-of-Flight (n_TOF) facility. Parallel plate avalanche counters (PPACs) were used, installed at the Experimental Area 1 (EAR1), which is located at 185¬†m from the neutron spallation target. The anisotropic emission of fission fragments were taken into account in the detection efficiency by using, in the case of U233, previous results available in EXFOR, whereas in the case of Th232 these data were obtained from our measurement, using PPACs and targets tilted 45‚ąė with respect to the neutron beam direction. Finally, the obtained results are compared with past measurements and major evaluated nuclear data libraries. Calculations using the high-energy reaction models INCL++ and ABLA07 were performed and some of their parameters were modified to reproduce the experimental results. At high energies, where no other neutron data exist, our results are compared with experimental data on proton-induced fission. Moreover, the dependence of the fission cross section¬†at 1 GeV with the fissility parameter of the target nucleus is studied by combining those (p,f) data with our (n,f) data on Th232 and U233 and on other isotopes studied earlier at n_TOF using the same experimental setup

    Total absorption ő≥\gamma-ray spectroscopy of the ő≤\beta decays of 96gs,m^{96\text{gs,m}}Y

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    The ő≤\beta decays of the ground state (gs) and isomeric state (m) of 96^{96}Y have been studied with the total absorption ő≥\gamma-ray spectroscopy technique at the Ion Guide Isotope Separator On-Line facility. The separation of the 8+^{+} isomeric state from the 0‚ąí^{-} ground state was achieved thanks to the purification capabilities of the JYFLTRAP double Penning trap system. The ő≤\beta-intensity distributions of both decays have been independently determined. In the analyses the de-excitation of the 1581.6 keV level in 96^{96}Zr, in which conversion electron emission competes with pair production, has been carefully considered and found to have significant impact on the ő≤\beta-detector efficiency, influencing the ő≤\beta-intensity distribution obtained. Our results for 96gs^{96\text{gs}}Y (0+^+) confirm the large ground state to ground state ő≤\beta-intensity probability, although a slightly larger value than reported in previous studies was obtained, amounting to 96.6‚ąí2.1+0.3%96.6_{-2.1}^{+0.3}\% of the total ő≤\beta intensity. Given that the decay of 96gs^{96\text{gs}}Y is the second most important contributor to the reactor antineutrino spectrum between 5 and 7 MeV, the impact of the present results on reactor antineutrino summation calculations has been evaluated. In the decay of 96m^{96\text{m}}Y (8+^{+}), previously undetected ő≤\beta intensity in transitions to states above 6 MeV has been observed. This shows the importance of total absorption ő≥\gamma-ray spectroscopy measurements of ő≤\beta decays with highly fragmented de-excitation patterns. 96m^{96\text{m}}Y (8+^{+}) is a major contributor to reactor decay heat in uranium-plutonium and thorium-uranium fuels around 10 s after fission pulses, and the newly measured average ő≤\beta and ő≥\gamma energies differ significantly from the previous values in evaluated databases (...

    High Energy Physics Opportunities Using Reactor Antineutrinos

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    Nuclear reactors are uniquely powerful, abundant, and flavor-pure sources of antineutrinos that continue to play a vital role in the US neutrino physics program. The US reactor antineutrino physics community is a diverse interest group encompassing many detection technologies and many particle physics topics, including Standard Model and short-baseline oscillations, BSM physics searches, and reactor flux and spectrum modeling. The community's aims offer strong complimentary with numerous aspects of the wider US neutrino program and have direct relevance to most of the topical sub-groups composing the Snowmass 2021 Neutrino Frontier. Reactor neutrino experiments also have a direct societal impact and have become a strong workforce and technology development pipeline for DOE National Laboratories and universities. This white paper, prepared as a submission to the Snowmass 2021 community organizing exercise, will survey the state of the reactor antineutrino physics field and summarize the ways in which current and future reactor antineutrino experiments can play a critical role in advancing the field of particle physics in the next decade

    Advances and new ideas for neutron-capture astrophysics experiments at CERN n_TOF

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    This article presents a few selected developments and future ideas related to the measurement of (n,ő≥)(n,\gamma) data of astrophysical interest at CERN n_TOF. The MC-aided analysis methodology for the use of low-efficiency radiation detectors in time-of-flight neutron-capture measurements is discussed, with particular emphasis on the systematic accuracy. Several recent instrumental advances are also presented, such as the development of total-energy detectors with ő≥\gamma-ray imaging capability for background suppression, and the development of an array of small-volume organic scintillators aimed at exploiting the high instantaneous neutron-flux of EAR2. Finally, astrophysics prospects related to the intermediate ii neutron-capture process of nucleosynthesis are discussed in the context of the new NEAR activation area

    Results of DTAS Campaign at IGISOL: Overview

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    International audienceThe ő≤ decays of more than twenty fission fragments were measured in the first experiments with radioactive-ion beams employing the Decay Total Absorption ő≥-ray Spectrometer. In this work, we summarize the main results obtained so far from this experimental campaign carried out at the Ion Guide Isotope Separator On-Line facility. The advances introduced for these studies represent the state-of-the-art of our analysis methodology for segmented spectrometers

    High Energy Physics Opportunities Using Reactor Antineutrinos

    No full text
    Nuclear reactors are uniquely powerful, abundant, and flavor-pure sources of antineutrinos that continue to play a vital role in the US neutrino physics program. The US reactor antineutrino physics community is a diverse interest group encompassing many detection technologies and many particle physics topics, including Standard Model and short-baseline oscillations, BSM physics searches, and reactor flux and spectrum modeling. The community's aims offer strong complimentary with numerous aspects of the wider US neutrino program and have direct relevance to most of the topical sub-groups composing the Snowmass 2021 Neutrino Frontier. Reactor neutrino experiments also have a direct societal impact and have become a strong workforce and technology development pipeline for DOE National Laboratories and universities. This white paper, prepared as a submission to the Snowmass 2021 community organizing exercise, will survey the state of the reactor antineutrino physics field and summarize the ways in which current and future reactor antineutrino experiments can play a critical role in advancing the field of particle physics in the next decade
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