High Resolution Neutron Detection

Review of Scientific Instruments, 2014

We present the development of a high-resolution position sensitive device for detection of slow neutrons in the environment of extremely high γ and e − radiation background. We make use of a planar silicon pixelated (pixel size: 55 × 55 μm 2) spectroscopic Timepix detector adapted for neutron detection utilizing very thin 10 B converter placed onto detector surface. We demonstrate that electromagnetic radiation background can be discriminated from the neutron signal utilizing the fact that each particle type produces characteristic ionization tracks in the pixelated detector. Particular tracks can be distinguished by their 2D shape (in the detector plane) and spectroscopic response using single event analysis. A Cd sheet served as thermal neutron stopper as well as intensive source of gamma rays and energetic electrons. Highly efficient discrimination was successful even at very low neutron to electromagnetic background ratio about 10 −4 .

2011

We present a readout system for thermal neutron detection. Redesigning neutron detector electrical fields can speed time response without an increase in gamma sensitivity. Gamma distribution affects the neutron counting area as single events rather than pileup of very low amplitude pulses. Operation at negative bias can resolve humidity issue. New shaper design could improve dead time and capacitance tolerance over what is commercially available .

Radiation Protection Dosimetry, 2014

In order to measure energy and fluence of neutron fields, with energy ranging from 8 keV to 1 MeV, a new primary standard is being developed at the IRSN (Institute for Radioprotection and Nuclear Safety). This project, µ-TPC (Micro Time Projection Chamber), carried out in collaboration with the LPSC, is based on the nucleus recoil detector principle. The measurement strategy requires track reconstruction of recoiling nuclei down to a few keV, which can be achieved with a low pressure gaseous detector using a micro-pattern gaseous detector. A gas mixture, mainly isobutane, is used as a n-p converter to detect neutrons into the detection volume. Then electrons, coming from the ionization of the gas by the proton recoil, are collected by the pixelised anode (2D projection). A self-triggered electronics is able to perform the anode readout at a 50 MHz frequency in order to give the third dimension of the track. Then the scattering angle is deduced from this track using algorithms. The charge collection leads to the proton energy, taking into account the ionization quenching factor. This article emphasizes the neutron energy measurements of a monoenergetic neutron field produced at 127 keV. The measurements are compared to Monte Carlo simulations using realistic neutron fields and simulations of the detector response. The discrepancy between experiments and simulations is 5 keV mainly due to the calibration uncertainties of 10%.

2014

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

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2005

Semiconductor pixel radiation detector systems have recently made significant progress achieving excellent spatial resolution, high sensitivity, wide dynamic range and low noise. The hybrid silicon pixel device of Medipix type developed at CERN was originally designed for position sensitive single X-ray photon detection. We have adapted this device to a position sensitive detector of slow neutrons by covering the detector surface with a 6 LiF neutron converter. Neutrons are converted to tritons and alpha particles which are subsequently detected by the silicon pixel detector. The basic parameters of such a pixel neutron sensitive device were investigated using thermal neutron beams. Tests for neutron imaging applications and comparison with currently used devices for neutron radiography (CCD camera with scintillator, imaging plates) were performed. The aim of this article is to demonstrate the exceptional good spatial resolution for neutrons (up to 8.5 lp/mm in the case of Medipix-2 option), reasonable neutron detection efficiency with very low sensitivity to background gamma radiation, low noise, perfect linearity and wide dynamic range. Results and future prospects are presented in this article.

EPJ Web of Conferences

It is possible to detect individual flashes from thermal neutron impacts in a ZnS scintillator using a CMOS camera looking at the scintillator screen, and off line image processing. Some preliminary results indicated that the efficiency of recognition could be improved by optimizing the light collection and the image processing. We will report on this ongoing work which is a result from the collaboration between ESS Bilbao and the ILL. The main progress to be reported is situated on the level of the on-line treatment of the imaging data. If this technology is to work on a genuine scientific instrument, it is necessary that all the processing happens on line, to avoid the accumulation of large amounts of image data to be analyzed off line. An FPGA-based real-time full-deca mode VME-compatible CameraLink board has been developed at the SCI of the ILL, which is able to manage the data flow from the camera and convert it in a reasonable “neutron impact” data flow like from a usual neutr...

The Group for the development of neutron and gamma detectors in the Central Institute of Engineering, Electronics and Analytics (ZEA-2) at Forschungszentrum Juelich (FZJ) has developed, in collaboration with European institutes, an Anger Camera prototype for improving the impact point reconstruction of neutron tracks. The detector is a chamber filled with $^3He+CF_4$ gas for neutron capture and subsequent production of a tritium and a proton. The energy deposition by the ions gives rise to drifting electrons with an avalanche amplification as they approach a micro-strip anode structure. The scintillating light, generated during the electron drift and avalanche stage, is collected by four vacuum photomultipliers. The position reconstruction is performed via software algorithms. The JUDIDT readout electronics was modified at ZEA-2 to cope with the data acquisition requirements of the prototype. The results of the commissioning of the electronics are here presented and commented.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2010

Measurement of the three dimensional trajectory and specific ionization of recoil protons using a hydrogen gas time projection chamber provides directional information about incident fast neutrons. Here we demonstrate directional fast neutron detection using such a device. The wide field of view and excellent gamma rejection that are obtained suggest that this device is well suited to searches for special nuclear materials, among other applications.

2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC), 2009

The High Efficiency Neutron Detector Array (HENDA) project at the Spallation Neutron Source (SNS), Oak Ridge Tennessee, has driven the need for state of the art radiation detector readout electronics. Readout electronics of this class must support multi-channel inputs while providing a high level of integration and precision. The Patara II ASIC targets this need by integrating a charge sensitive front end followed by analog and digital signal processing that supports the connectivity of 64 detectors. A monolithic biasing system and digital programmability was integrated in order to reduce the amount of required external components on the end system motherboard. ). J. L. Britton is with Texas Instruments,