Articles de revues : « Neutron flux measurement »

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Rindi, Alessandro, Francesco Celani, Marco Lindozzi et Silvia Miozzi. « Underground neutron flux measurement ». Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment 272, n^o 3 (novembre 1988) : 871–74. http://dx.doi.org/10.1016/0168-9002(88)90772-3.

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Fourmentel, D., J.-F. Villard, C. Destouches, B. Geslot, L. Vermeeren et M. Schyns. « In-Pile Qualification of the Fast-Neutron-Detection-System ». EPJ Web of Conferences 170 (2018) : 04025. http://dx.doi.org/10.1051/epjconf/201817004025.

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In order to improve measurement techniques for neutron flux assessment, a unique system for online measurement of fast neutron flux has been developed and recently qualified in-pile by the French Alternative Energies and Atomic Energy Commission (CEA) in cooperation with the Belgian Nuclear Research Centre (SCK•ECEN). The Fast-Neutron-Detection-System (FNDS) has been designed to monitor accurately high-energy neutrons flux (E > 1 MeV) in typical Material Testing Reactor conditions, where overall neutron flux level can be as high as 1015 n.cm-2.s-1 and is generally dominated by thermal neutrons. Moreover, the neutron flux is coupled with a high gamma flux of typically a few 1015 γ.cm-2.s-1, which can be highly disturbing for the online measurement of neutron fluxes. The patented FNDS system is based on two detectors, including a miniature fission chamber with a special fissile material presenting an energy threshold near 1 MeV, which can be 242Pu for MTR conditions. Fission chambers are operated in Campbelling mode for an efficient gamma rejection. FNDS also includes a specific software that processes measurements to compensate online the fissile material depletion and to adjust the sensitivity of the detectors, in order to produce a precise evaluation of both thermal and fast neutron flux even after long term irradiation. FNDS has been validated through a two-step experimental program. A first set of tests was performed at BR2 reactor operated by SCK•CEN in Belgium. Then a second test was recently completed at ISIS reactor operated by CEA in France. FNDS proved its ability to measure online the fast neutron flux with an overall accuracy better than 5%.

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Aitkulov, M. T., D. S. Dyussambayev, N. K. Romanova, Sh H. Gizatulin, A. A. Shaimerdenov, Zh T. Bugybay, K. S. Kisselyov et A. O. Beisebayev. « Measurement of the spatial-energy distribution of neutrons in the irradiation channel of the critical facility ». Journal of Physics : Conference Series 2155, n^o 1 (1 janvier 2022) : 012021. http://dx.doi.org/10.1088/1742-6596/2155/1/012021.

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Abstract One of the basic installations of the Republican State Enterprise “Institute of Nuclear Physics” of the Ministry of Energy of the Republic of Kazakhstan is a critical assembly, which is a zero-power reactor. Desalinated water and beryllium serve as moderators and neutrons reflectors. The energy spectrum of neutrons in the core is thermal. The main purpose and area of application is the modeling and study of the neutronic characteristics of the cores of water-moderated research reactors of various types. The paper presents the results of experimental measurements of the spatial-energy distribution of neutrons in the dry, central channel of the critical assembly. Measurements of the neutron flux were carried out using activation foils for three energy groups of neutrons: thermal, epithermal, and fast. The measured thermal neutrons flux in the irradiation channel is ~ 3·108 cm‒2s‒1, and fast neutrons flux (with energies above 0.7 MeV) is ~ 8·108 cm‒2s‒1. The fraction of thermal neutrons in the integral flux was 0.23%, and the fraction of fast neutrons was 0.62%. In the axial distribution of thermal and fast neutrons, the maximum value of the neutron flux is 50 mm below the midplane of the core.

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Chatel, Carole, Ludovic Mathieu, Mourad Aïche, Maria Diakaki et Olivier Bouland. « Development of a small Time-Projection-Chamber for the quasi-absolute neutron flux measurement ». EPJ Web of Conferences 284 (2023) : 01012. http://dx.doi.org/10.1051/epjconf/202328401012.

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Accurate actinides fission cross sections around 1 MeV are of primary importance for the safety of generation IV reactors. To have accurate measurements, the neutron flux must also be accurately estimated. This is usually done with respect to the 235U(n,f) cross section. It is however possible to measure the neutron flux with respect to the 1H(n,n)p cross section which is a primary standard, providing an independent and precise measurement. Typically, the usual proton recoil technique uses a silicon detector for neutrons of energy between 1 and 70 MeV. However, the high electron and gamma background due to neutron production under irradiation makes the use of this or any other detector not suitable for an accurate measurement below 1 MeV. To this end, the Gaseous Proton Recoil Telescope is developed and characterized. The goal is to provide quasi-absolute neutron flux measurements with an accuracy better than 3%. It consists of a double ionization chamber with a Micromegas segmented detection plane and the gaseous pressure can be adjusted to protons – and hence neutron – energy. The sensitivity to gamma and electrons background, the intrinsic efficiency as well as the resolution of this detector have been investigated.

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Zeinalov, Shakir, Olga Sidorova, Pavel Sedyshev, Valery Shvetsov, Youngseok Lee et Uk-Won Nam. « Thermal neutron intensity measurement with fission chamber in current, pulse and Campbell modes ». EPJ Web of Conferences 231 (2020) : 05009. http://dx.doi.org/10.1051/epjconf/202023105009.

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In thermal nuclear reactors, most of the power is generated by thermal neutron induced fission. Therefore, fission chambers with targets that respond directly to slow neutrons are of great interest for thermal neutron flux measurements due to relatively low sensitivity to gamma radiation. However, the extreme conditions associated with experiments at very low cross section demand highly possible thermal neutron flux, leading often to substantial design changes. In this paper we report design of a fission chamber for wide range (from 10 to 1012 n/cm2 sec) measurement of thermal neutron flux. Test experiments were performed at the first beam of IBR2 pulsed reactor using digital pulse processing (DPP) technique with modern waveform digitizers (WFD). The neutron pulses detected by the fission chamber in each burst (5 Hz repetition rate) of the reactor were digitized and recorded to PC memory for further on-line and off-line analysis. New method is suggested to make link between the pulse counting, the current mode and the Campbell technique.

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Perelli Cippo, E., C. Cazzaniga, M. Paoletti, S. Colombi, F. Caruggi, M. Petruzzo, D. Rigamonti, C. Frost et M. Rebai. « Towards the use of SDD as an absolute detector for high-energy neutron measurements ». Journal of Instrumentation 18, n^o 05 (1 mai 2023) : C05019. http://dx.doi.org/10.1088/1748-0221/18/05/c05019.

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Abstract As of today, the standard method employed in tokamaks for the absolute measurement of the neutron flux (thus of the nuclear fusion power) is based on activation foils, being the most robust and unbiased technique for the absolute determination of neutron fluence. However, this technique is not able to provide real-time data useful for the control of future fusion plants like DEMO. In this paper, we present some preliminary results about the R&D activity aimed at developing the Single-crystal Diamond Detectors (SDD) used for fast neutron measurements into an absolute neutron flux monitor. Tests have been conducted at the new NILE neutron source of the Rutherford-Appleton Laboratory, a facility with compact neutron generators with a maximum yield of 109 n/s and 1010 n/s for 2.5 MeV and 14 MeV neutrons, respectively. A series of neutron spectra and flux measurements have been taken with different SDD and associated DAQ. Comparisons with standard activation foils (and namely Fe, Zr, Al and Nb foils for 14 MeV neutrons and In for 2.5 MeV neutrons) and with other reference detectors are presented and discussed. Also discussed is the stability of the SDD over time when employed at high neutron rates in realistic neutron environment, and the effects of neutron irradiation on both the counting rate and detector resolution.

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Pan, Yongyu, Fengzhao Shen, Qibin Fu et Tuchen Huang. « A thermal neutron detection system based on boron-coated straw detector with prompt gamma coincidence ». Journal of Instrumentation 17, n^o 09 (1 septembre 2022) : P09021. http://dx.doi.org/10.1088/1748-0221/17/09/p09021.

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Abstract Accurate measurement of the neutron flux is of crucial importance for rare event search experiments in underground laboratories. The intrinsic radioactive background of the detector becomes the limiting factor for the detection of extremely low neutron flux. In this study, a thermal neutron detection system aimed at low flux measurement was developed based on boron-coated straw (BCS) neutron detectors. The neutron events can be distinguished from the detector background by coincidence measurement of neutron and the prompt gamma ray. With state-of-the-art BCS neutron detectors and NaI(Tl) gamma detector, a system sensitivity of ∼120 cps/nv was achieved, comparable to that of the commonly used 3He counters. Based on the selected coincidence criteria, the background events were rejected to 0.1% with 45.3% of the neutrons preserved. The background accidental coincidence count rate of the system was measured as 2.3×10-5 cps, corresponding to a lower limit of measurable thermal neutron flux of 1.9×10-7 n/cm2/s. The performance of the system can be further improved by using other gamma scintillator with lower neutron absorption (such as BGO) and adding extra shielding for ambient gamma rays.

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Zhang, Jie, Yipo Zhang, Jinglong Zhang, Jianhang Zhou, Xuwen Zhan, Zuowei Wen, Shikui Cheng et al. « Development of a high-temporal resolution neutron flux measurement system for the HL-2M tokamak ». Journal of Instrumentation 17, n^o 07 (1 juillet 2022) : P07027. http://dx.doi.org/10.1088/1748-0221/17/07/p07027.

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Abstract To enhance the understanding of the physics of energetic ions in fusion plasma, a high-temporal resolution neutron flux measurement (HTRNFM) system, which is equipped with a fast-neutron scintillation detector embedded with ZnS:Ag phosphor, has been developed for the HL-2M tokamak. It has a temporal resolution of 10 μs during conventional operations. Its dynamic range is sufficiently wide for neutron flux measurements by adopting the combination use of the scalar mode and the Campbell mode. Based on the Monte Carlo calculations, the applicable count rate ranges of both the scalar mode and the Campbell mode are respectively 0.1–10 Mcps and 10–200 Mcps. The performance validation of the HTRNFM system has been performed by neutron flux measurements in magnetohydrodynamic (MHD) quiet plasmas in the HL-2A tokamak. In another plasma with abundant MHD instabilities, both the continuous neutron flux decreases and the rapid neutron flux decreases caused by different MHD instabilities are observed in a more detailed manner for the first time with the HTRNFM system than with other neutron flux measurement (NFM) systems that have a lower temporal resolution of 1 ms. The HTRNFM system will serve as a powerful diagnostic tool for research on energetic ion confinement quality in the HL-2M tokamak.

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Désert, Sylvain, Tobias Panzner et Patrice Permingeat. « Focusing neutrons with a combination of parabolic and elliptical supermirrors ». Journal of Applied Crystallography 46, n^o 1 (21 décembre 2012) : 35–42. http://dx.doi.org/10.1107/s0021889812047346.

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Cold-neutron focusing is a challenge with regard to improving the flux at the sample, decreasing measurement time and/or gaining statistical reliability. Several techniques are used for neutron focusing, such as simple or multi-beam collimation, refractive or magnetic lenses, and focusing mirrors. In this work, a new device for focusing neutrons using a combination of a parabolic supermirror, an asymmetric slit system and an elliptical supermirror is presented. The aim of this focusing system is to improve the neutron flux at the sample compared to other techniques without either achromatism or absorption. The performance of the device obtained by simulations and measurements with a prototype on a small-angle neutron scattering setup shows a flux gain of four at the sample position and an intensity gain higher than 100 when the sample size can be increased compared to classical setups. Finally the applications for neutron instruments are commented on.

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Richardson, J. M., T. E. Chupp, R. G. H. Robertson et J. F. Wilkerson. « A calorimeter for neutron flux measurement ». Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment 306, n^o 1-2 (août 1991) : 291–99. http://dx.doi.org/10.1016/0168-9002(91)90335-n.

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Robertson, R. G. H., et Paul E. Koehler. « Calorimetric measurement of thermal neutron flux ». Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment 251, n^o 2 (octobre 1986) : 307–12. http://dx.doi.org/10.1016/0168-9002(86)90795-3.

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Tashani, Ahmed A. « Measurement of thermal neutron flux and cadmium ratios using neutron activation analysis ». Libyan Journal of Science &Technology 7, n^o 2 (18 septembre 2022) : 96–99. http://dx.doi.org/10.37376/ljst.v7i2.2244.

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Irradiation of known foil samples in a reactor and subsequent measurement of induced activity allows determination of neutron flux. This is an important information for many purposes. It can be used reciprocally to determine contents of unknown samples irradiated at the same position in the reactor. On the other hand, neutron flux information is used in the assessment of a safe operation of nuclear power reactors. In the frame of this work, bare and cadmium covered foils of gold and dysprosium have been irradiated at different positions of the reactor. Induced activity measurements were made using a standard procedure. Thermal neutron flux and cadmium ratio values were determined for the irradiation positions.

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Manna, A., O. Aberle, V. Alcayne, S. Amaducci, J. Andrzejewski, L. Audouin, V.-Suarez Babiano et al. « Setup for the measurement of the 235U(n, f) cross section relative to n-p scattering up to 1 GeV ». EPJ Web of Conferences 239 (2020) : 01008. http://dx.doi.org/10.1051/epjconf/202023901008.

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The neutron induced fission of 235U is extensively used as a reference for neutron fluence measurements in various applications, ranging from the investigation of the biological effectiveness of high energy neutrons, to the measurement of high energy neutron cross sections of relevance for accelerator driven nuclear systems. Despite its widespread use, no data exist on neutron induced fission of 235U above 200 MeV. The neutron facility n_TOF offers the possibility to improve the situation. The measurement of 235U(n,f) relative to the differential n-p scattering cross-section, was carried out in September 2018 with the aim of providing accurate and precise cross section data in the energy range from 10 MeV up to 1 GeV. In such measurements, Recoil Proton Telescopes (RPTs) are used to measure the neutron flux while the fission events are detected and counted with dedicated detectors. In this paper the measurement campaign and the experimental set-up are illustrated.

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Ino, T., H. Otono, K. Mishima et T. Yamada. « Precision neutron flux measurement with a neutron beam monitor ». Journal of Physics : Conference Series 528 (24 juillet 2014) : 012039. http://dx.doi.org/10.1088/1742-6596/528/1/012039.

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Dupont, C., P. Leleux, P. Lipnik, W. K. Sindano et P. Wauters. « Simultaneous measurement of neutron flux and neutron detector efficiency ». Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment 256, n^o 2 (mai 1987) : 339–41. http://dx.doi.org/10.1016/0168-9002(87)90228-2.

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Varmuza, Jan, Karel Katovsky, Miroslav Zeman, Ondrej Stastny, Ivan Haysak et Robert Holomb. « New experimental research stand SVICKA neutron field analysis using neutron activation detector technique ». EPJ Web of Conferences 177 (2018) : 01004. http://dx.doi.org/10.1051/epjconf/201817701004.

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Knowledge of neutron energy spectra is very important because neutrons with various energies have a different material impact or a biological tissue impact. This paper presents basic results of the neutron flux distribution inside the new experimental research stand SVICKA which is located at Brno University of Technology in Brno, Czech Republic. The experiment also focused on the investigation of the sandwich biological shielding quality that protects staff against radiation effects. The set of indium activation detectors was used to the investigation of neutron flux distribution. The results of the measurement provide basic information about the neutron flux distribution inside all irradiation channels and no damage or cracks are present in the experimental research stand biological shielding.

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Chauhan, Bhavesh, Basudeb Dasgupta et Vivek Datar. « A deuterated liquid scintillator for supernova neutrino detection ». Journal of Cosmology and Astroparticle Physics 2021, n^o 11 (1 novembre 2021) : 005. http://dx.doi.org/10.1088/1475-7516/2021/11/005.

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Abstract For the next galactic supernova, operational neutrino telescopes will measure the neutrino flux several hours before their optical counterparts. Existing detectors, relying mostly on charged current interactions, are mostly sensitive to ν̅e and to a lesser extent to νe . In order to measure the flux of other flavors (νμ ,ν̅μ ,ντ ,and ν̅τ ), we need to observe their neutral current interactions with the detector. Such a measurement is not only crucial for overall normalization of the supernova neutrino flux but also for understanding the intricate neutrino oscillation physics. A deuterium based detector will be sensitive to all neutrino flavors. In this paper, we propose a 1 kton deuterated liquid scintillator (DLS) based detector that will see about 435 neutral current events and 170 (108) charged current νe (ν̅e ) events from a fiducial supernova at a distance of 10 kpc from Earth. We explore the possibility of extracting spectral information from the neutral current channel by measuring the quenched kinetic energy of the proton in the final state, where the neutron in the final state is tagged and used to reduce backgrounds. We also discuss the secondary interactions of the recoil neutrons in the detector.

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Namakonov, V., S. Andreyev, D. Gabbasov, A. Moseyeva et D. Sergina. « MEASUREMENT OF 14 MEV NEUTRONS TRANSMISSION THROUGH LITHIUM HYDRIDE LAYERS WITH TIME-OF-FLIGHT METHOD ». PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. SERIES : NUCLEAR AND REACTOR CONSTANTS 2020, n^o 4 (26 décembre 2020) : 33–39. http://dx.doi.org/10.55176/2414-1038-2020-4-33-39.

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The results of experiments on transmission of 14 MeV neutrons through lithium hydride layers of thickness up to 25 cm are presented in the article. The measurements were performed with time-of-flight method on a pulse channel of neutron generator NG-12I. The operating mode of the neutron generator is pulse-periodic. Neutrons passing through the layers of Li hydrides were registered by detector based on a 70×70 mm stilbene crystal scintillator. NIM standard modules were used as measuring equipment. The neutron yield from the generator target was estimated by neutron monitor with a fluorine plastic activation detector. Activity of radiation-exposed neutron activation detectors was measured using a gamma spectrometer with high purity germanium detector (HPGe). The averaged 14 MeV neutrons flux from the target was ∼2⋅108 n/s. The measurement results were used to obtain instrumental neutron spectra for samples of various thicknesses and to estimate coefficients of 14 MeV neutrons passing through the layers of Li hydrides. The obtained results can be used for validation of neutron-physical calculations and for improvement of neutron constants libraries.

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Adamek, Evan R., Maynard S. Dewey, Nadia Fomin, David M. Gilliam, Geoffrey L. Greene, Shannon F. Hoogerheide, Hans P. Mumm, Jeffrey S. Nico et William M. Snow. « Precision neutron flux measurement using the Alpha-Gamma device ». EPJ Web of Conferences 219 (2019) : 10004. http://dx.doi.org/10.1051/epjconf/201921910004.

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The Alpha-Gamma device at the National Institute of Standards and Technology (NIST) utilizes neutron capture on a totally absorbing 10B deposit to measure the absolute neutron flux of a monochromatic cold neutron beam. Gammas produced by the boron capture are counted using high purity germanium detectors, which are calibrated using a well-measured 239Pu alpha source and the alpha-to-gamma ratio from neutron capture on a thin 10B target. This device has been successfully operated and used to calibrate the neutron flux monitor for the BL2 neutron lifetime experiment at NIST. It is also being used for a measurement of the 6Li(n,t)4He cross section. We shall present its principle of operation along with the current and planned projects involving the Alpha-Gamma device, including the recalibration of the U.S. national neutron standard NBS-1 and (n,f) cross section measurements of 235U.

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CHEN, T., H. ZHANG, Y. X. SUN, S. C. LIANG, H. T. REN, L. XIAO, Q. HE et S. S. YAN. « THE EFFECT OF NEUTRON IRRADIATION ON FLUX PINNING IN MELT-TEXTURED GROWTH YBa2Cu3O7 SUPERCONDUCTOR ». Modern Physics Letters B 05, n^o 11 (10 mai 1991) : 763–70. http://dx.doi.org/10.1142/s0217984991000940.

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The distribution of flux pinning energy in melt-textured growth (MTG) YBa 2 Cu 3 O 7 superconductor irradiated by fast neutrons was determined by rotating-sample magnetic measurement at liquid nitrogen temperature. It was found that neutron irradiation strengthened flux pinning by increasing the most probable pinning energy along c-axis and in ab plane by 47% and 82% respectively. Anisotropy of flux pinning was also observed. New strong pinning sites might be created by neutron irradiation.

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Kormilitsyn, T., A. Pankratenko, Yu Kashchuk, S. Obudovsky, R. Rodionov, D. Fridrikhsen, A. Krasilnikov, S. Syromukov et D. Yurkov. « Characterization of the Fast Neutron Generators for Calibration of Fusion Neutron Diagnostics ». EPJ Web of Conferences 288 (2023) : 03002. http://dx.doi.org/10.1051/epjconf/202328803002.

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Modern magnetic confinement fusion devices increasingly rely on extensive neutron diagnostic configurations to measure a plethora of key plasma parameters. Measurement accuracy for these diagnostics depends heavily on in situ calibration. In order to enable said calibration, we set out to propose a reliable and powerful fast neutron source, to define a characterization plan for this source in terms of yield, flux and energy distributions, propose an optimized set of tools suitable for online monitoring of neutron source performance and its metrological characteristics. In the framework of this research activity with the ultimate aim of ITER tokamak neutron diagnostics calibration we rely on industrial-grade fast neutron generator NG-24 (D-D neutron yield ~109 n/s, D-T neutron yield ~1011 n/s) with sealed tube and stuffed, titanium target developed by FSUE VNIIA. The well-known analytical expressions for thick target NGs and our measurements using neutron spectrometers utilizing threshold reactions – diamond detector and LaCl3 scintillator for D-T and D-D neutron generators respectively – were found to be significantly coherent. These data are supported through our multi-step forward modelling including ion stopping in target, fusion reaction kinematics modelling and calculating detector response based on modelled neutron spectra. We discuss methods of uncertainty mitigation of neutron spectrometer measurements. Application of both neutron activation analysis and gas-filled neutron flux monitors during source characterization and operation allows for lowing statistical uncertainty of neutron flux measurements to 1% level over 1 minute of time resolution. Over the course of several measurement campaigns the optimal set of measurement tools have been determined including detector dimensions, required acquisition time, calibration methods.

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Brall, Thomas, Vladimir Mares, Rolf Bütikofer et Werner Rühm. « Assessment of neutrons from secondary cosmic rays at mountain altitudes – Geant4 simulations of environmental parameters including soil moisture and snow cover ». Cryosphere 15, n^o 10 (11 octobre 2021) : 4769–80. http://dx.doi.org/10.5194/tc-15-4769-2021.

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Abstract. Ground-based measurements of neutrons from secondary cosmic rays are affected by environmental parameters, particularly hydrogen content in soil. To investigate the impact of these parameters, in particular snow cover, Geant4 Monte Carlo simulations were carried out. In a previous study the model used for the Geant4 Monte Carlo simulations was already validated by measurements performed with an extended-range Bonner sphere spectrometer (ERBSS) at Zugspitze, Germany, and at Jungfraujoch, Switzerland. In the present study a sensitivity analysis including different environmental parameters (i.e. slope of mountain, snow height, and soil moisture) and their influence on the flux of neutrons from secondary cosmic rays was performed with Geant4. The results are compared with ERBSS measurements performed in 2018 at the Environmental Research Station Schneefernerhaus located at the Zugspitze, Germany. It is shown that the slope of the Zugspitze mountain reduces the neutron flux from secondary cosmic rays between about 25 % and 50 % as compared to a horizontal surface, depending on neutron energy and snow cover. An increasing height of snow cover, simulated as snow water equivalent (SWE), reduces the total neutron flux exponentially down to a factor of about 2.5 as compared to soil without any snow cover, with a saturation for snow heights greater than 10 to 15 cm SWE, depending on neutron energy. Based on count rates measured with the individual spheres of the ERBSS, SWE values were deduced for the whole year 2018. Specifically, mean SWE values deduced for the winter months (January to March) are between 6.7 and 10.1 cm or more, while those for the summer months (July to September) are between 2.1 and 3.6 cm. Soil moisture of 5 % water mass fraction in limestone leads to a decrease of the total neutron flux by about 35 % compared to dry limestone. It is concluded that the measurement of neutrons from secondary cosmic radiation can be used to gain information on the height of snow cover and its seasonal changes, on soil moisture, and on local geometry such as mountain topography. Because the influence of such parameters on neutron flux from secondary cosmic rays depends on neutron energy, analysis of the whole neutron energy spectrum is beneficial.

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GOLDBERG, HAIM. « TEV ANTINEUTRINOS FROM CYGNUS OB2 ». International Journal of Modern Physics A 20, n^o 06 (10 mars 2005) : 1132–39. http://dx.doi.org/10.1142/s0217751x05024006.

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High energy cosmic ray experiments have identified an excess from the region of the Galactic Plane in a limited energy range around 1018 eV ( EeV ). This is very suggestive of neutrons as candidate primaries, because the directional signal requires relatively-stable neutral primaries, and time-dilated neutrons can reach Earth from typical Galactic distances when the neutron energy exceeds an EeV . We here point out that if the Galactic messengers are neutrons, then those with energies below an EeV will decay in flight, providing a flux of cosmic antineutrinos above a TeV which is observable at a kilometer-scale neutrino observatory. The expected event rate per year above 1 TeV in a detector such as IceCube, for example, is 20 antineutrino showers (all flavors) and a 1° directional signal of [Formula: see text] events. A measurement of this flux can serve to identify the first extraterrestrial point source of TeV antineutrinos.

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Ziaie, F., A. A. Hosseini et S. A. Durrani. « Neutron flux distribution measurement methods & ; comparison ». Radiation Measurements 28, n^o 1-6 (janvier 1997) : 533–36. http://dx.doi.org/10.1016/s1350-4487(97)00134-0.

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Gutierrez, Tonatiuh Rivero, Jorge S. Benitez Read, Javier C. Palacios Hernandez, Armando Segovia de los Rios et Luis C. Longoria Gandara. « Software-based Neutron Flux Measurement Channel (NFMC) ». International Journal of Nuclear Energy Science and Technology 5, n^o 2 (2010) : 91. http://dx.doi.org/10.1504/ijnest.2010.030551.

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Böhmer, B., M. Grantz, W. Hansen, D. Hinke, J. Konheiser, K. Noack, H. C. Mehner, I. Stephan et S. Unholzer. « Measurements of gamma and neutron flux spectra in iron-water configurations ». Kerntechnik 68, n^o 5-6 (1 octobre 2003) : 223–27. http://dx.doi.org/10.1515/kern-2003-0086.

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Abstract Neutron and gamma spectra were measured behind and inside of modules consisting of variable iron and water slabs which were installed in radial beams of the zero-power training and research reactors AKR of the Technical University Dresden and ZLFR of the University of Applied Sciences Zittau/Görlitz. The applied NE-213 scintillation spectrometer allowed the measurement of gamma and neutron fluence spectra in the energy regions 0.3–10 MeV for photons and 1.0–20 MeV for neutrons. Measurements with thermoluminescence dosemeters (TLD) between slabs supplied additional information about the space distribution of energy integrated fluxes. The paper describes the experiments and presents some important results of the measurements. They will be compared with the results of transport calculations made by means of MCNP and TRAMO in another paper.

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Sabaibang, S., S. Lekchaum et C. Tippayakul. « Analysis of Neutron Flux Measurement in Thai Research Reactor-1/Modification 1 Using the Monte Carlo Method ». Advanced Materials Research 979 (juin 2014) : 23–26. http://dx.doi.org/10.4028/www.scientific.net/amr.979.23.

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This study adopts the Monte Carlo method to analyze the neutron flux measurement technique in Thai Research Reactor-1/Modification 1(TRR-1/M1) by performing simulations using MCNPX computer program. The neutron flux measurement technique being analyzed is called “gold foil activation technique”. The simulation model consists of gold foil located in the middle of in-core irradiation which is in the center of the reactor core. The variation in the calculated neutron flux is assessed by varying the gold foil thickness from approximately 500 – 800 μcm. It is found from the simulation that the calculated neutron flux can differ by 33 % when increasing the gold foil thickness by 60%. In addition, more detailed simulations to determine neutron flux distribution within the gold foil are performed to study and explain the variation in neutron flux calculated at different foil thicknesses. The simulation result shows that self-shielding effect has significant impact to the neutron flux distribution within the gold foil, and hence to the average neutron flux.

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Song, G., S. Lee, J. Park, W. Kim, K. Ko, H. Kim et G. Cho. « Optimization of fast neutron and X-ray pulse shape discrimination (PSD) using an EJ276G scintillator in high radiation mixed conditions ». Journal of Instrumentation 17, n^o 03 (1 mars 2022) : C03016. http://dx.doi.org/10.1088/1748-0221/17/03/c03016.

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Abstract Organic crystalline, liquid, and plastic scintillators with low Z-number materials are commonly used in fast neutron detectors. Pulse shape discrimination (PSD) is used to distinguish neutrons from X-rays because these detectors are affected by X-rays due to Compton scattering during fast neutron measurement. PSD was performed with a 1 × 1 × 3 cm3 EJ276G plastic scintillator, SiPM, and DAQ (10-bit resolution, 400 MHz) using the charge comparison method, which compares the total charge (Q body) and the delayed charge (Q tail) from the peak. Most studies have been conducted under laboratory conditions, such as with 252Cf or 241Am-Be sources. This study will perform PSD in a 15 MeV electron accelerator with a total flux of 6.72 × 1014 #/sec and an X-ray-to-neutron ratio of up to 4071:1. The PSD was optimized before the measurement in high flux conditions because it was difficult to perform PSD due to the pile-up effect in these conditions. Optimization focused on the figure of merit (FoM), which is an index of PSD performance. To distinguish neutrons from X-rays under these conditions, lead shielding is necessary to reduce the X-ray-to-neutron ratio. We performed Monte Carlo N-Particle Transport Code (MCNP6) simulations to determine the optimal shielding thickness. Fast neutrons interact with lead due to its high density, which results in small neutron energy loss and direction changes by scattering. This effect can affect other pixels as noise. We plan to evaluate the neutron images under high X-ray flux conditions by comparing the images of the MCNP6 simulation results and the measurement results.

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Doukellis, G., T. Paradellis et S. Kossionides. « Energy and flux measurement of the neutrons produced in a gas cell ». HNPS Proceedings 3 (5 décembre 2019) : 196. http://dx.doi.org/10.12681/hnps.2386.

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The neutron flux and energy distribution of the neutrons produced in a gas cell were measured using a silicon semiconductor detector. The energy spectra produced by the borbardment of the silicon detector with neutrons were simulated using Monte Carlo techniques and were compared with the measured spectra

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Orrigo, S. E. A., J. L. Tain, N. Mont-Geli, A. Tarifeño-Saldivia, L. M. Fraile, M. Grieger, J. Agramunt et al. « Measurement of the neutron flux at the Canfranc Underground Laboratory with HENSA ». Journal of Physics : Conference Series 2156, n^o 1 (1 décembre 2021) : 012169. http://dx.doi.org/10.1088/1742-6596/2156/1/012169.

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Abstract We have performed a long-term measurement of the neutron flux with the High Efficiency Neutron Spectrometry Array HENSA in the Hall A of the Canfranc Underground Laboratory. The Hall A measurement campaign lasted from October 2019 to March 2021, demonstrating an excellent stability of the HENSA setup. Preliminary results on the neutron flux from this campaign are presented for the first time. In Phase 1 (113 live days) a total neutron flux of 1.662 × 10−5 cm−2 s−1 is obtained. Our results are in good agreement with those from our previous shorter measurement where a reduced experimental setup was employed.

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Walencik-Łata, Agata, Katarzyna Szkliniarz, Jan Kisiel, Kinga Polaczek-Grelik, Karol Jędrzejczak, Marcin Kasztelan, Jacek Szabelski et al. « Characteristics of Natural Background Radiation in the GIG Experimental Mine ‘Barbara’, Poland ». Energies 15, n^o 3 (18 janvier 2022) : 685. http://dx.doi.org/10.3390/en15030685.

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Underground locations can be used in various ways for scientific and economic purposes. One of the main factors influencing the safety level in the underground mine workings is natural radioactivity. The article presents research carried out on the natural radioactivity in shallow mine workings at the GIG Experimental Mine ‘Barbara’. The description of the natural radiation includes radon determination in the air, in situ gamma spectrometry, neutron flux measurements, and laboratory measurements of 226,228Ra, 40K, and 234,238U isotopes using gamma and alpha spectrometry techniques. In the measurement chamber at the depth 46 m (122 m w.e.) in the sandstone layer, the photon flux registered at the 7–3150 keV energy range is equal to 17.6 ± 1.9 cm−2s−1, the gamma-ray dose rate is 0.200 ± 0.029 µSv/h, and the thermal neutron flux is equal to (8.6 ± 1.1) × 10−6 cm−2s−1. After closing the measurement chamber and turning off ventilation, a significant ingrowth of 222Rn content was observed, reaching the value of 4040 ± 150 Bq/m3. An increased gamma-ray flux and thermal neutron flux were observed in the investigated location.

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Chen, Yonghao, Guangyuan Luan, Jie Bao, Hantao Jing, Qi An, Huaiyong Bai, Ping Cao et al. « Measurement of the neutron energy spectrum of Back-n #ES1 at CSNS ». EPJ Web of Conferences 239 (2020) : 17018. http://dx.doi.org/10.1051/epjconf/202023917018.

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The China spallation neutron source (CSNS) was built and started running since 2018. It produces neutrons by impinging 1.6 GeV protons onto a tungsten target with 25 Hz repetition frequency. A beam line exploiting the back-streaming neutrons (Back-n) was built mainly for nuclear data measurement and started commissioning simultaneously with CSNS in 2018. There are two experimental endstations along the Back-n beam line: endstation 1 (#ES1) with a neutron flight path of about 55 m and endstation 2 (#ES2) with about 76 m. The neutron energy spectra of both #ES1 and #ES2 were measured since it is important for feasibility study and analysis. In this paper, the measurement of the neutron energy spectrum of Back-n #ES1 is reported. It is measured by a multi-layer fission chamber using the 235U samples as the neutron converters. The neutron energy spectrum from 0.1 eV to 30 MeV is obtained. The integral neutron flux (from 0.1 eV to 30 MeV) normalized to the proton beam power of 100 kW is 1.55×107 neutrons/cm2/s.

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Vo, Van Tai, Van Kien Nguyen, Nhi Dien Nguyen, Dinh Hai Trinh et La Son Phan. « Design of a neutron flux measurement channel using the ionization chamber KNK-3 at the Dalat Nuclear Research Reactor ». Nuclear Science and Technology 11, n^o 3 (30 septembre 2021) : 11–18. http://dx.doi.org/10.53747/nst.v11i3.367.

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This paper presents a design of the neutron flux measurement channel that consists of a Boron-contained gamma-compensated ionization chamber (CIC) named KNK-3 and operates in current mode, a current to frequency (I to F) converter, and a neutron flux measurement and control module (FPGA-WR). The designed measuring channel allows to measure and control the neutron flux density from 1.0x106 to 1.2x1010 n/cm2.s corresponding to the range from 0.1 to 120% of the nominal power of 500 kW of the Dalat nuclear research reactor (DNRR). The measurement and control module uses FPGA Artix-7 and digital signal processing algorithms to measure and calculate the reactor power and period values and generate warning and emergency signals by the reactor power and period. The measurement channel was tested by using simulated signals and examining in the reactor to compare with the neutron flux measurement channel using the BPM-107R neutron flux controller of the existing complex ASUZ-14R for the DNRR control and protection system (CPS). The comparison results show that the measurement channel fully meets the requirements on the accuracy of the reactor power and period parameters as well as the ability to respond at once to the warning and emergency signals of the reactor power and period. Therefore, the measurement channel can be used for testing, research, and training. The FPGA-WR measurement and control module can replace the BPM-107R controller for the working range of the CPS.

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Du, Xianan, Xuewen Wu, Youqi Zheng et Yongping Wang. « Reactivity Effect Evaluation of Fast Reactor Based on Angular-Dependent Few-Group Cross Sections Generation ». Energies 14, n^o 13 (4 juillet 2021) : 4042. http://dx.doi.org/10.3390/en14134042.

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Among all the possible occurring reactivity effects of a fast reactor, the situations whereby the control rod was inserted, or the coolant was voided could lead to strong anisotropy of neutron flux distribution, therefore the angular dependence on neutron flux should be considered during the few-group cross-sections generation. Therefore, the purpose of this paper is to compare the influence whether the angular dependence on neutron flux is considered in the calculation of few-group cross sections for the reactivity effect calculation. In the study, the 1-D SN finite difference neutron transport equation solver was implemented in the TULIP of SARAX code system so that the high-order neutron flux could be obtained. Meanwhile, the improved Tone’s method was also applied. The numerical results were obtained based on three experimental FR cores, the JOYO MK-I core, ZPPR-9 core, and ZPPR-10B core. Both control rod worth and sodium void reactivity were calculated and compared with the measurement data. By summarizing and comparing the results of 46 cases, significant differences were found between different consideration of the neutronic analysis. The consideration of angular dependence on neutron flux distribution in the few-group cross-sections generation was beneficial to the neutronic design analysis of FR, especially for the reactivity effect calculation.

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McCormack, O., L. Giacomelli, G. Croci, A. Muraro, I. Mario, M. Zuin, L. Cordaro et al. « First measurement of neutrons produced by deuterium fusion reactions in SPIDER ». Journal of Instrumentation 17, n^o 02 (1 février 2022) : C02015. http://dx.doi.org/10.1088/1748-0221/17/02/c02015.

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Abstract The inaugural deuterium acceleration campaign in the SPIDER negative ion source facility in Padua has recently taken place. The first neutrons generated by deuterium-deuterium beam-target fusion reactions (2.45 MeV) have been recorded, occurring from the collision of accelerated deuterium with deuterium absorbed by the calorimeter of SPIDER. A neutron detector based on a novel EJ276 plastic scintillator has been employed to successfully measure the neutron flux, which shows strong agreement with the extracted current of the acceleration grid. We have performed neutron-gamma pulse shape discrimination with the EJ276 device at SPIDER combined with direct spectroscopic comparisons of the D-D neutrons with data from the Frascati neutron generator (241AmB quasi-monoenergetic 2.5 MeV). Despite the low statistics produced in this first campaign, both pulse shape discrimination and spectral analysis of the fusion neutrons was viable. The success of these first measurements has led to the installation of an array of 6 new scintillators to be used for further physical studies in future campaigns.

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Sun, Lingyu, Ce Liu et Lili Zhu. « Reliability Assessment of RIC Neutron Flux Measurement System ». IOP Conference Series : Materials Science and Engineering 585 (13 août 2019) : 012092. http://dx.doi.org/10.1088/1757-899x/585/1/012092.

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Schumann, Olaf J., Theo Köble, Andreas Havenith, Bo Fu et Laurent Coquard. « QUANTOM® − Optimization of the online neutron flux measurement system ». EPJ Web of Conferences 225 (2020) : 06014. http://dx.doi.org/10.1051/epjconf/202022506014.

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For the final disposal of radioactive waste, the waste packages have to meet the acceptance requirements defined by national licensing and supervisory authorities. Nondestructive methods are very much preferred over destructive methods for the qualification or re-qualification. Existing nondestructive methods as integral or segmented gamma scanning or neutron counting only determine the isotope specific activity but do not allow quantifying other non-radioactive hazardous substances. These should have been documented during creation, conditioning, and packaging of the waste. But especially for legacy waste, this documentation is often poor or even missing. This gap is to be filled by the QUANTOM® measurement device that will determine the mass fraction of elements within a 200-l-drum using the Prompt- and Delayed- Gamma-Neutron-Activation-Analysis. In order to obtain a spatially resolved characterization, it will employ a segmented scanning approach. For the determination of the absolute mass fractions, the neutron flux inside the drum has to be known accurately. As the waste itself will alter the neutron distribution and flux, it is not possible to calculate the latter a priori from the gamma measurement. Hence the neutron flux has to be measured simultaneously with the gamma radiation. In this presentation, we will introduce the system for measuring the thermal neutron flux surrounding the waste drum from which the flux within the waste package has to be reconstructed. We performed a simulation study to score several possible detector placements for an improved reconstruction performance. We will show the outcome of these calculations and present the final design of the detector arrangement.

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Safwan Shalbi, Norazlianie Sazali et Wan Norharyati Wan Salleh. « Measurement of Neutron Flux at Thermal Column Using Gold Foil Activation Analysis and TLD Detector : Technical Review ». Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 83, n^o 2 (8 juin 2021) : 25–43. http://dx.doi.org/10.37934/arfmts.83.2.2543.

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The thermal column at the TRIGA PUSPATI (RTP) research reactor can produce thermal neutron. However, the optimization on the thermal neutron flux produced should be performed to gain a sufficient thermal neutron for boron neutron capture therapy purpose. Thus, the objective of this review is to optimize the thermal neutron flux by designing the collimator with different materials at the thermal column. In order to fulfil the requirement, set by the IAEA standard, the study of Boron Neutron Capture Therapy (BNCT) around the world was being reviewed to study the suitable measurement, material, design, and modification for BNCT at the thermal column of TRIGA MARK-II, Malaysia. Initially, the BNCT mechanisms and history was review. Then, this paper review on the design and modifications for BNCT purpose around the world. Based on this review, suitable material and design can be used for the BNCT in Malaysia. Moreover, this paper also reviews the current status of BNCT at the RTP with the measurement of the thermal neutron flux was conducted along the thermal column at 250 kW. The thermal column of RTP was divided into 3 phases (Phase 1, Phase 2 and Phase 3) so that an accurate measurement can be obtained by using gold foil activation method. This value was used as a benchmark for the neutron flux produced from the thermal column. The reviewed demonstrated that the final thermal neutron flux produced was significantly for BNCT purpose.

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Zhao, Qiang, Zhiyong He, Xueyin Zhang, Wenjuan Cui, Hushan Xu, Zhiqiang Chen et Yuxi Luo. « ICONE23-1172 ON THE MEASUREMENT OF INCORE NEUTRON FLUX IN ACCELERATOR DRIVEN SUB-CRITICAL SYSTEMS ». Proceedings of the International Conference on Nuclear Engineering (ICONE) 2015.23 (2015) : _ICONE23–1—_ICONE23–1. http://dx.doi.org/10.1299/jsmeicone.2015.23._icone23-1_94.

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Das, Basanta, Anurag Shyam, Rashmita Das et Durga Rao. « The neutron production rate measurement of an indigenously developed compact D-D neutron generator ». Nuclear Technology and Radiation Protection 28, n^o 4 (2013) : 422–26. http://dx.doi.org/10.2298/ntrp1304422d.

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One electrostatic accelerator based compact neutron generator was developed. The deuterium ions generated by the ion source were accelerated by one accelerating gap after the extraction from the ion source and bombarded to a target. Two different types of targets, the drive - in titanium target and the deuteriated titanium target were used. The neutron generator was operated at the ion source discharge potential at +Ve 1 kV that generates the deuterium ion current of 200 mA at the target while accelerated through a negative potential of 80 kV in the vacuum at 1.3?10-2 Pa filled with deuterium gas. A comparative study for the neutron yield with both the targets was carried out. The neutron flux measurement was done by the bubble detectors purchased from Bubble Technology Industries. The number of bubbles formed in the detector is the direct measurement of the total energy deposited in the detector. By counting the number of bubbles the total dose was estimated. With the help of the ICRP-74 neutron flux to dose equivalent rate conversion factors and the solid angle covered by the detector, the total neutron flux was calculated. In this presentation the operation of the generator, neutron detection by bubble detector and estimation of neutron flux has been discussed.

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Zhu, Lin, Jian-rong Zhou, Li-xin Zeng, Liang Xiao, Xiao-juan Zhou, Jin-hao Tan, Yuan-guang Xia et al. « A ceramic-GEM neutron detector with a wide neutron-flux measurement range for the beam monitoring at China spallation neutron source ». Journal of Instrumentation 18, n^o 01 (1 janvier 2023) : P01033. http://dx.doi.org/10.1088/1748-0221/18/01/p01033.

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Abstract The increase of neutron flux in pulsed spallation neutron facilities imposes demands on the neutron detector for beam monitoring, including excellent neutron/gamma discrimination, wide dynamic neutron-flux measurement range, wavelength resolution, and long-term stability. In this paper, we developed a ceramic GEM-based (gas electron multiplier) neutron detector with an active area of 100 mm × 100 mm. It adopted a thinner conversion material and the stopping layer to lower the detection efficiency so as to extend the dynamic measurement range of the detector. The detection efficiency of this detector was investigated by the Monte Carlo (MC) tool FLUKA, showing that the low efficiency around 0.01% for 1 Åneutrons was reached by using a 0.1 μm natB4C converter appended with an aluminum film of 2 μm thickness. Its validation of the wavelength spectra measurement was verified by comparisons with that made with an LND monitor, and it could work at the condition of 7.1 × 109 n/s for 2.5 Åneutrons. In addition, it was demonstrated that this detector was able to measure the beam profile with a position resolution of better than 2.1 ± 0.1 mm. The results of simulations and experiments show that this ceramic-GEM neutron detector can meet the requirements of the direct measurement of high-flux beam, and it will be a new neutron detector for the beam monitoring at the China spallation neutron source (CSNS).

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Chauhan, Bhavesh. « A deuterated liquid scintillator for supernova neutrino detection ». Journal of Physics : Conference Series 2156, n^o 1 (1 décembre 2021) : 012098. http://dx.doi.org/10.1088/1742-6596/2156/1/012098.

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Abstract For the next galactic supernova, operational neutrino telescopes will measure the neutrino flux several hours before their optical counterparts. Existing detectors, relying mostly on charged current interactions, are mostly sensitive to and to a lesser extent to ve. In order to measure the flux of other flavors, we need to observe their neutral current interactions with the detector. Such a measurement is not only crucial for overall normalization of the supernova neutrino flux but also for understanding the intricate neutrino oscillation physics. A deuterium based detector will be sensitive to all neutrino flavors. In this paper, we propose a 1 kton deuterated liquid scintillator (DLS) based detector that will see about 435 neutral current events and 170 (108) charged current [INLINE] (fe) events from a fiducial supernova at a distance of 10 kpc from Earth. We explore the possibility of extracting spectral information from the neutral current channel by measuring the quenched kinetic energy of the proton in the final state, where the neutron in the final state is tagged and used to reduce backgrounds.

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Sarsour, M., J. Amadio, E. Anderson, L. Barrón-Palos, B. Crawford, C. Crawford, D. Esposito et al. « Neutron spin rotation measurements ». EPJ Web of Conferences 219 (2019) : 06002. http://dx.doi.org/10.1051/epjconf/201921906002.

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The neutron spin rotation (NSR) collaboration used parity-violating spin rotation of transversely polarized neutrons transmitted through a 0.5 m liquid helium target to constrain weak coupling constants between nucleons. While consistent with theoretical expectation, the upper limit set by this measurement on the rotation angle is limited by statistical uncertainties. The NSR collaboration is preparing a new measurement to improve this statistically-limited result by about an order of magnitude. In addition to using the new high-flux NG-C beam at the NIST Center for Neutron Research, the apparatus was upgraded to take advantage of the larger-area and more divergent NG-C beam. Significant improvements are also being made to the cryogenic design. Details of these improvements and readiness of the upgraded apparatus are presented. We also comment on how recent theoretical work combining effective field theory techniques with the 1/Nc expansion of QCD along with previous NN weak measurements can be used to make a prediction for dϕ/dz in 4He. An experiment using the same apparatus with a room-temperature target was carried out at LANSCE to place limits on parity-conserving rotations from possible fifth-force interactions to complement previous studies. We sought this interaction using a slow neutron polarimeter that passed transversely polarized slow neutrons by unpolarized slabs of material arranged so that this interaction would tilt the plane of polarization and develop a component along the neutron momentum. The results of this measurement and its impact on the neutron-matter coupling gA2 from such an interaction are presented. The NSR collaboration is also preparing a new measurement that uses an upgraded version of the room-temperature target to be run on the NG-C beamline; and it is expected to constrain gA2 by at least two additional orders of magnitude for λc between 1 cm and 1 μm.

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Bikchurina, Marina, Timofey Bykov, Dmitrii Kasatov, Iaroslav Kolesnikov, Aleksandr Makarov, Ivan Shchudlo, Evgeniia Sokolova et Sergey Taskaev. « The Measurement of the Neutron Yield of the 7Li(p,n)7Be Reaction in Lithium Targets ». Biology 10, n^o 9 (24 août 2021) : 824. http://dx.doi.org/10.3390/biology10090824.

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A compact accelerator-based neutron source has been proposed and created at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. An original design tandem accelerator is used to provide a proton beam. The neutron flux is generated as a result of the 7Li(p,n)7Be threshold reaction using the solid lithium target. A beam shaping assembly is applied to convert this flux into a beam of epithermal neutrons with characteristics suitable for BNCT. The BNCT technique is being tested in in vitro and in vivo studies, and dosimetry methods are being developed. Currently, the BNCT technique has entered into clinical practice in the world: after successful clinical trials, two clinics in Japan began treating patients, and four more BNCT clinics are ready to start operating. The neutron source proposed at the Budker Institute of Nuclear Physics served as a prototype for a facility created for a clinic in Xiamen (China). It is planned to equip the National Medical Research Center of Oncology (Moscow, Russia) and National Oncological Hadron Therapy Center (Pavia, Italy) with the same neutron sources. Due to the impending use of an accelerator neutron source for treating patients, the validation of the neutron yield of the 7Li(p,n)7Be reaction in lithium metal targets is required. The theoretical neutron yield has not been evaluated experimentally so far.

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Oprea, A., F. Gunsing, P. Schillebeeckx, O. Aberle, M. Bacak, E. Berthoumieux, D. Cano-Ott et al. « Measurement of the ²⁴¹Am(n,γ) cross section at the n_TOF facility at CERN ». EPJ Web of Conferences 284 (2023) : 01036. http://dx.doi.org/10.1051/epjconf/202328401036.

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The neutron capture cross section of 241Am is an important quantity for nuclear energy production and fuel cycle scenarios. Several measurements have been performed in recent years with the aim to reduce existing uncertainties in evaluated data. Two previous measurements, performed at the 185 m flight-path station EAR1 of the neutron time-of-flight facility n_TOF at CERN, have permitted to substantially extend the resolved resonance region, but suffered in the near-thermal energy range from the unfavorable signal-to-background ratio resulting from the combination of the high radioactivity of 241Am and the rather low thermal neutron flux. The here presented 241Am(n,γ) measurement, performed with C6D6 liquid scintillator gamma detectors at the 20 m flight-path station EAR2 of the n_TOF facility, took advantage of the much higher neutron flux. The current status of the analysis of the data, focussed on the low-energy region, will be described here.

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Danon, Y., P. Brain, K. Cook, D. Fritz, A. Golas, G. Siemers, S. Singh et al. « Recent Nuclear Data Activity at the RPI Gaerttner LINAC Center ». EPJ Web of Conferences 294 (2024) : 01001. http://dx.doi.org/10.1051/epjconf/202429401001.

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The nuclear data group at the RPI Gaerttner LINAC Laboratory uses a 60 MeV pulsed electron LINAC to produce short pulses of neutrons and perform cross section and other nuclear data measurements in a wide energy range from below 1 meV to about 20 MeV. This paper will cover several recent activities that are of interest to nuclear applications. Interest in thermal neutron scattering evaluations prompted the need for accurate thermal total cross section measurements for validation. To improve the neutron flux in the sub-thermal region (below 0.01 eV) a cold moderator was designed and installed. A polyethylene moderator operating at about 26 K resulted in a factor of 8 increase in neutron flux below 0.01 eV. Using this new capability, several transmission measurements were performed with samples of polyethylene, polystyrene, Plexiglas, and yttrium hydride. Neutron capture and transmission measurements in the keV energy range were made for 54Fe, which will be used in an evaluation effort that is underway. Capture measurements were collected on an array of C6D6 detectors that was expanded from 4 to 7 detectors, and a complementary transmission measurement was also performed. Finally, research aimed at experimental validation of neutron capture gamma production is in progress. Energy dependent capture gamma cascades are measured with the RPI 16-segment gamma multiplicity detector. Measurements are then compared to capture gamma cascades generated from nuclear structure evaluations processed with DICEBOX and transported with a modified version of MCNP. This system provides important information on the completeness of primary gamma-ray databases.

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Junghans, Arnd, Roland Beyer, Jürgen ClauBner, K. Toniögler, Sebastian Urlass, Daniel Bemmerer, Anna Ferrari et al. « Neutron transmission measurements at nELBE ». EPJ Web of Conferences 239 (2020) : 01006. http://dx.doi.org/10.1051/epjconf/202023901006.

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Neutron total cross sections are an important source of experimental data in the evaluation of neutron-induced cross sections. The sum of all neutron-induced reaction cross sections can be determined with a precision of a few per cent in a relative measurement. The neutron spectrum of the photoneutron source nELBE extends in the fast region from about 100 keV to 10 MeV and has favourable conditions for transmission measurements due to the low instantaneous flux of neutrons and low gamma-flash background. Several materials of interest (in part included in the CIELO evaluation or on the HPRL of OECD/NEA) have been investigated: 197Au [1, 2], natFe [2], natW [2], 238U, natPt, 4He, natO, natNe, natXe. For gaseous targets high pressure gas cells with flat end-caps have been built that hold up to 200 bar pressure. The experimental setup will be presented including results from several transmission experiments and the data analysis leading to the total cross sections will be discussed.

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Kochkarov, M. M., M. M. Boliev, I. M. Dzaparova, R. V. Novoseltseva, Yu F. Novoseltsev, V. B. Petkov, V. I. Volchenko, G. V. Volchenko et A. F. Yanin. « Neutron flux measurement at the Baksan Underground Scintillation Telescope ». Physics of Particles and Nuclei 49, n^o 1 (janvier 2018) : 97–100. http://dx.doi.org/10.1134/s1063779618010227.

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Borio di Tigliole, A., A. Cammi, D. Chiesa, M. Clemenza, S. Manera, M. Nastasi, L. Pattavina et al. « TRIGA reactor absolute neutron flux measurement using activated isotopes ». Progress in Nuclear Energy 70 (janvier 2014) : 249–55. http://dx.doi.org/10.1016/j.pnucene.2013.10.001.

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Trofimov, Yu N. « Measurement of fast-neutron flux density by means of156dY ». Atomic Energy 73, n^o 6 (décembre 1992) : 1018. http://dx.doi.org/10.1007/bf00761447.

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