Fabrication and nuclear reactor tests of ultra-thin 3D silicon neutron detectors with a boron carbide converter

Fleta, C.; Guardiola, Consuelo; Esteban, S.; Jumilla, C.; Pellegrini, G.; Quirion, D.; Rodriguez, J.L.; Lousa, A.; Martínez-de-Olcoz, L.; Lozano, M.

doi:10.1088/1748-0221/9/04/p04010

Cited by 9 publications

(8 citation statements)

References 16 publications

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“…Monte Carlo simulations with GEANT4 were developed to investigate optimal detection layer thickness by irradiating different geometry possibilities with a thermal neutron beam perpendicular to the detection layer, incident from the side of detector A. The materials considered were 99% enriched 10 B4C, as reported achievable in literature [3], surrounded by Ar:CO2 (90%:10%), a commonly used gas in boron-coated gaseous detectors, at atmospheric pressure. A 0.9 µm Mylar layer was used as substrate, which despite being indispensable to support the B4C, does not contribute to the conversion of neutrons, but rather only to the absorption of the reaction secondary products, and therefore should ideally be as thin as practically feasible.…”

Section: Monte Carlo Simulation Resultsmentioning

confidence: 99%

Improving spatial resolution in neutron detectors with submicrometric B4C layers

Duarte¹,

Marcos²,

Amaro³

2022

Proceedings of Particles and Nuclei International Conference 2021 — PoS(PANIC2021)

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Due to their physical properties, neutrons are an excellent probe for the investigation of matter in different scientific fields, such as physics, chemistry and biology as well as for specific medical and industrial applications. Neutron detection is usually achieved via nuclear capture reactions, where the neutron is absorbed by the nucleus of an atom, which decays into two heavy charged particles. These reactions only occur with significant cross-section for a few isotopes and the ones of practical interest for detection applications are, by decreasing cross-section, 3 He, 10 B and 6 Li. Until recent years, proportional counters filled with 3 He gas were considered the golden standard for neutron detection. However, when a severe shortage of this gas was acknowledged, prices skyrocketed and heavy acquisition restrictions were implemented, which urged to pursue alternative technologies. Consequently, over the last decade, a lot of effort and investment was put into the development of 3 He-free neutron detectors for a wide range of applications. Gaseous detectors equipped with boron layers, deposited on the inner walls of the detector or on substrates that are then inserted into it emerged as the most obvious alternative. Due to momentum and energy conservation, the reaction products of the 10 B neutron capture are emitted along the same, in opposite directions. Consequently, in conventional boron coated detectors, for each neutron capture, only one of the reaction products can travel towards the gas to generate a signal in the detector, while the other is absorbed by the boron layer or the substrate. Furthermore, depending on the depth of the nuclear capture, the range of the α particles in typical gases used in gaseous detectors at atmospheric pressure can extend up to about 10 mm, which intrinsically limits their spatial resolution. In this work, we propose an alternative approach that aims at simultaneously detecting both secondary products of neutron capture reactions which can be achieved if thin enough converter and substrate layers are deployed. Monte Carlo simulations were developed to validate the detection concept and to optimize its geometry by computing the detection efficiency as a function of substrate and converter thicknesses. A 0.9 µm Mylar foil was stretched over an aluminium frame obtaining a smooth 100×100 mm 2 effective surface, suitable for boron carbide (B4C) deposition. Considering this substrate, simulation results indicate that a 1.5% detection efficiency for thermal neutrons can be reached with a total 1 µm thick B4C (99% enriched) layer, equally distributed over both sides of the substrate surface. Although this value is inferior to that of conventional boron-based detectors employing a thick conversion layer (~4.5%), it offers the advantage of allowing a more precise estimation of the interaction site for each detected neutron, which leads to an improvement of spatial resolution.

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Section: Monte Carlo Simulation Resultsmentioning

confidence: 99%

Improving spatial resolution in neutron detectors with submicrometric B4C layers

Duarte¹,

Marcos²,

Amaro³

2022

Proceedings of Particles and Nuclei International Conference 2021 — PoS(PANIC2021)

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“…Measurements of recoil proton spectra were carried out at room temperature and atmospheric pressure using a 241 Am-Be fast neutron source with an activity of 1.62 • 10 6 Bq. Polyethylene (PE) films with density of 0.90 g/cm 3 were placed directly on the detector package at a distance of 3 mm from the GaAs sensor. The neutron source has a cylinder shape with a height of 3.2 cm and with a diameter of 2.2 cm and was placed on the top of the PE layer.…”

Section: Fast Neutron Measurementsmentioning

confidence: 99%

“…Semiconductor detectors combined with converters are generally used. It is usually Si detectors with various designs [1][2][3][4][5] or diode structures based on wide-bandgap materials [6][7][8]. Also the internal conversion of neutron radiation in semiconductor material is widely used [9][10][11][12].…”

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confidence: 99%

Characterization and simulation of fast neutron detectors based on surface-barrier VPE GaAs structures with polyethylene converter

Черных

Baryshnikov

et al. 2016

J. Inst.

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A: Fast neutron detectors with an active area of 80 mm 2 based on surface-barrier VPE GaAs structures were fabricated and tested. Polyethylene with density of 0.90 g/cm 3 was used as a converter layer. The recoil-proton surface-barrier sensor was fabricated on high purity VPE GaAs epilayers with a thickness of 50 µm. The neutron detection efficiency measured with a 241 Am-Be source was 1.30 • 10 −3 puls./neutr. for the PE converter thickness of 670 µm. The signal-togamma-background ratio was at the level of 50. Simulation of the detector characteristics with Geant4 toolkit has showed good correlation with the experimental data and allowed to estimate the maximal theoretical detection efficiency of the detector which is determined by the PE converter and equals to 1.37 • 10 −3 puls./neutr. The difference between the measured and simulated values of the detection efficiency is due to the fact that the events with energies below 0.5 MeV were not taken into account during the measurements. K: Neutron detectors (cold, thermal, fast neutrons); Solid state detectors; Instrumentation for neutron sources 1Corresponding author.

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“…The columnar electrodes are distributed in a square array with 80 µm pitch between columns of the same doping type, with a whole area of 0.57 cm 2 . The complete fabrication process of the 3D sensor and the device geometry is described in [28], although for 20 µm active thickness. For the microdosimetric application, after the sensor fabrication, the supporting wafer is selectively etched resulting on a 'membrane' detector surrounded by a supporting frame.…”

Section: Ultra-thin 3d Silicon Membrane Detectorsmentioning

confidence: 99%

Preliminary microdosimetric measurements with ultra-thin 3D silicon detectors of a 62 MeV proton beam

Guardiola¹,

Fleta²,

Rodriguez³

et al. 2015

J. Inst.

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In this paper we present the first direct microdosimetric measurements of 62 MeV proton beams using ultra-thin 3D silicon detectors at different depths in a solid-water phantom. The detectors have 3D columnar electrodes that penetrate a 10 µm thick silicon membrane, resulting in a micrometric scale sensitive volume. The 62 MeV proton beam was generated in a cyclotron CYCLONE-110 at Centre de Recherches du Cyclotron (CRC) at Louvain-la-Neuve. The proton beam average energy was modulated with stacked tissue-equivalent solid water layers. The energy loss profile was studied through the Bragg curve and pulse height spectra. The experimental silicon microdosimetric spectra showed the lineal energy dependence along the Bragg curve. This work demonstrates the potential capability of the ultra-thin 3D silicon detectors as 3D detector technology-based microdosimeters.

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Fabrication and nuclear reactor tests of ultra-thin 3D silicon neutron detectors with a boron carbide converter

Cited by 9 publications

References 16 publications

Improving spatial resolution in neutron detectors with submicrometric B4C layers

Improving spatial resolution in neutron detectors with submicrometric B4C layers

Characterization and simulation of fast neutron detectors based on surface-barrier VPE GaAs structures with polyethylene converter

Preliminary microdosimetric measurements with ultra-thin 3D silicon detectors of a 62 MeV proton beam

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