F. Piscitelli

10B multi-grid proportional gas counters for large area thermal neutron detectors

Introduction 10B fi lms have been studied as neutron convertors in semi-conductors [1], and in different types of gas proportional counters for neutron scattering applications: for example in [2] the detector is made of several layers of straw tubes coated on the inner side with B4C; in [3] several parallel GEM (Gas Electron Multipliers) operated with an amplifi cation gain of 1 are coated with B4C fi lms on both sides; and in [4], inclined substrates are proposed to reduce the self-absorption of fi ssion products in the convertor. These different solutions are well suited for small size detectors requiring high counting rate and high spatial resolution but not for large area detectors mounted in vacuum chambers. The multi-grid detector, introduced at the ILL in 2010 [5], is developed in collaboration with European Spallation Source (ESS) in the CRISP project (http://www.crisp-fp7.eu/) to replace 3He in large-Area Neutron detectors. We present its principle as well as some results obtained with a prototype of 8 cm × 200 cm. This contribution to the study of 10B-fi lms detectors has been done in the frame of the International Initiative to search for 3He alternative technologies (http://icnd. org/). Results obtained by other institutes are accessible via the web page of the last workshop dedicated to BF3 and 10B-fi lm detectors (http://www.ill.eu/10bbf3, see also NN 23.3, p. 6).

In-beam test of the Boron-10 Multi-Grid neutron detector at the IN6 time-of-flight spectrometer at the ILL

A neutron detector concept based on solid layers of boron carbide enriched in 1 B has been in development for the last few years as an alternative for He-3 by collaboration between the ILL, ESS and ...

(B4C)-B-10 Multi-Grid as an Alternative to He-3 for Large Area Neutron Detectors

Despite its present shortage, 3He continues to be the most common neutron converter for detectors in neutron scattering science. However, it is obvious that the development of large area neutron detectors based on alternative neutron converters is rapidly becoming a matter of urgency. In the technique presented here, grids each comprising 28 10B4C layers (each 1 μm thick) are used to convert neutrons into ionizing particles which are subsequently detected in proportional gas counters. The total active area of the prototype is 8 cm × 200 cm. To instrument this detector 4.6 m2 of 10B-enriched boron carbide were coated onto aluminium blades using a DC magnetron sputtering machine.Despite its present shortage, 3He continues to be the most common neutron converter for detectors in neutron scattering science. However, it is obvious that the development of large area neutron detectors based on alternative neutron converters is rapidly becoming a matter of urgency. In the technique presented, grids each comprising 30 10B4C layers (each 1 µm thick) are used to convert neutrons into ionising particles which are subsequently detected in proportional gas counters. Several prototypes, the largest with a total active area of 8 cm x 200 cm, were tested. Up to 4.6 m2 of 10B-enriched boron carbide were coated onto aluminium blades using a DC magnetron sputtering machine. Characterisation of the prototype showed neutron efficiency to be n = 53.04% for 2.5 A neutrons, which is in line with expectations from MC simulation. Gamma-sensitivity = 5 · 10-5 was measured for a broad range of energies. Long term stability measurements were also performed. These results demonstrate the potential of this technique as alternative to 3He-based position sensitive detectors.

Investigation of background in large-area neutron detectors due to alpha emission from impurities in aluminium

Thermal neutron detector based on films of

Adaptive algorithms of position and energy reconstruction in Anger-camera type detectors: experimental data processing in ANTS

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ANTS — a simulation package for secondary scintillation Anger-camera type detector in thermal neutron imaging

B

Multi-Grid detector for neutron spectroscopy: results obtained on time-of-flight spectrometer CNCS

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Neutron reflectometry with the Multi-Blade 10B-based detector

C have been developed as an alternative to

Characterization of the Multi-Blade 10B-based detector at the CRISP reflectometer at ISIS for neutron reflectometry at ESS

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Multi-Grid boron-10 detector for time-of-flight spectrometers in neutron scattering science

He detectors. In particular, The Multi-Grid detector concept is considered for future large area detectors for ESS and ILL instruments. An excellent signal-to-background ratio is essential to attain expected scientific results. Aluminium is the most natural material for the mechanical structure of of the Multi-Grid detector and other similar concepts due to its mechanical and neutronic properties. Due to natural concentration of