A novel fast neutron detector for nuclear data measurements

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2012

The Low Energy Neutron Detector Array (LENDA) is a neutron time-of-flight (TOF) spectrometer developed at the National Superconducting Cyclotron Laboratory (NSCL) for use in inverse kinematics experiments with rare isotope beams. Its design has been motivated by the need to study the spin-isospin response of unstable nuclei using (p, n) charge-exchange reactions at intermediate energies ( > 100 MeV/u). It can be used, however, for any reaction study that involves emission of low energy neutrons (150 keV -10 MeV). The array consists of 24 plastic scintillator bars and is capable of registering the recoiling neutron energy and angle with high detection efficiency. The neutron energy is determined by the time-of-flight technique, while the position of interaction is deduced using the timing and energy information from the two photomultipliers of each bar. A simple test setup utilizing radioactive sources has been used to characterize the array. Results of test measurements are compared with simulations. A neutron energy threshold of < 150 keV, an intrinsic time (position) resolution of ∼ 400 ps (∼ 6 cm) and an efficiency > 20 % for neutrons below 4 MeV have been obtained.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1992

We present design studies, results of test measurements, and Monte Carlo simulations which served as a basis for the realization of a large area neutron detector (LAND). It has a front area of 2 m x 2 m and a depth of 1 m, and features a multilayer structure of passive converter and active scintilla tor materia!. The detector is subdivided in independently operating paddles which allow time-of-flight and position measurement. An energy resolution of f1Tn / Tn = 5.3% for a flight path of 15 m and an overall detection efficiency of E "" 1 is anticipated for neutrons with Tn "" 1 GeY. The operation of LAND at the SIS facility of GSI is described.

1996

Los Alarnos National Laboratory, an affirmative action/equal opportunity employer, is operated by the University of California for the US. Department of Energy under contract W-7405-ENG-36. By acceptance of this article, the publisher recognizes that the US. Government retains a ~~XCluSiVe, royaltyfree license to publish or reproduce the published form 01 this contribution, or to allow others lo do so, for U.S. Government purposes. The Los Alamos National Laboratory requests that the publisher identify this article as work performed under the auspices of the US. Department of Energy.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2012

The AMANDE facility produces monoenergetic neutron fields from 2 keV to 20 MeV for metrological purposes. To be considered as a reference facility, fluence and energy distributions of neutron fields have to be determined by primary measurement standards. For this purpose, a micro Time Projection Chamber is being developed to be dedicated to measure neutron fields with energy ranging from 8 keV up to 1 MeV. In this work we present simulations showing that such a detector, which allows the measurement of the ionization energy and the 3D reconstruction of the recoil nucleus, provides the determination of neutron energy and fluence of these neutron fields.

Journal of Nuclear Engineering and Radiation Science, 2016

Among GEN IV projects for future nuclear power plants, lead-cooled fast reactors (LFRs) seem to be a very interesting solution due to their benefits in terms of fuel cycle, coolant safety, and waste management. The novelty of this matter causes some open issues about coolant chemical aspects, structural aspects, monitoring instrumentation, etc. Particularly, hard neutron flux spectra would make traditional neutron instrumentation unfit to all reactor conditions, i.e., source, intermediate, and power range. Identification of new models of nuclear instrumentation specialized for LFR neutron flux monitoring asks for an accurate evaluation of the environment the sensor will work in. In this study, thermal hydraulics and chemical conditions for the LFR core environment will be assumed, as the neutron flux will be studied extensively by the Monte Carlo transport code MCNPX (Monte Carlo N-Particles X-version). The core coolant's high temperature drastically reduces the candidate instrumentation because only some kinds of fission chambers and self-powered neutron detectors can be operated in such an environment. This work aims at evaluating the capabilities of the available instrumentation (usually designed and tailored for sodiumcooled fast reactors) when exposed to the neutron spectrum derived from the Advanced Lead Fast Reactor European Demonstrator, a pool-type LFR project to demonstrate the feasibility of this technology into the European framework. This paper shows that such a class of instrumentation does follow the power evolution, but is not completely suitable to detect the whole range of reactor power, due to excessive burnup, damages, or gamma interferences. Some improvements are possible to increase the signal-to-noise ratio by optimizing each instrument in the range of reactor power, so to get the best solution. The design of some new detectors is proposed here together with a possible approach for prototyping and testing them by a fast reactor.

Nuclear Instruments and Methods, 1976

The detecUon efficiency of a 3 × 3 mamx of NE 110 scintillator blocks, 153 × 153 × 270 mm long, has been measured m the neutron kmenc energy range 15-120 MeV for several thresholds, ranging from 2.80 to 15 75 MeV equivalent electron energy, and for various thicknesses of lead shielding m front of the counter. The probabd~ues of detecting a neutron in a block d~ffereat from the one struck by the beam ('mlxlng') and in more than one block ('multlfirlng') have also been measured as a function of threshold and shielding. Comparisons have been made w~th a Monte Carlo program which accounts for the modular structure of the counter The effioency and the spatml resoluuon of a very large matrix have been obtained, using both experimental and Monte Carlo results.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

Prototypes of the Low Energy Neutron detector Array (LENA) have been tested and compared with detailed GEANT simulations. LENA will consist of plastic scintillation bars with the dimensions 1000 Â 45 Â 10 mm 3. The tests have been performed with gray sources and neutrons originating from the neutron-induced fission of 235 U. The simulations agreed very well with the measured response and were therefore used to simulate the response to mono-energetic neutrons with different detection thresholds. LENA will be used to detect low-energy neutrons from (p,n)-type reactions with low momentum transfer foreseen at the R 3 B and EXL setups at FAIR, Darmstadt.

We describe the upgraded Magnetic Proton Recoil fusion neutron spectrometer (MPRu). The original MPR was installed at the JET fusion experiment in 1996, and was designed for diagnosis of the 14-MeV neutron emission in high-power deuterium-tritium (DT) fusion experiments. The goal of the MPR upgrade project is to widen the operational range of the instrument to the full range of fusion relevant neutron energies, 1.5 < E n < 18 MeV, to increase its flexibility and to improve the background immunity of the spectrometer's focal plane detector. In this paper we describe how these goals have been achieved by the installation of a new detector hodoscope, based on phoswich scintillators, in combination with state-of-the-art digital data acquisition electronics and enhanced monitoring capabilities. Examples of test results and predicted performance are given.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2004

A unique experimental facility has been developed to measure absolute neutron scattering cross-sections through the use of tagged intermediate-energy neutrons. The neutrons are produced via the reaction p þ d-n þ 2p with an electron-cooled circulating proton beam of 200 MeV bombarding energy incident on a deuterium gas jet target. The ''tagging'' of the neutrons is accomplished by detection of the associated recoil protons in an array of silicon microstrip detectors located in vacuum. The detection of two protons in coincidence signals the production of a neutron, while energy and position measurements on the recoil protons allow for reconstruction of the four-momentum of the neutron, and its impact position on a secondary target, on an event-by-event basis. Performance characteristics of this facility are presented, and its future application to an absolute measurement of the np elastic scattering cross-section is described.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011