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The development and testing of a two-dimensional (2-D) prototype detector based on a microstrip gas chamber (MSGC) is reported using a gas mixture of 2.5 bar ³He and 2.5 bar CF4. The second coordinate is obtained by utilising a plane of wires as pick up electrodes. The detector is operated with the wire plane at such a potential so as not to induce any gain around the wires. This means that the high tolerances normally associated with wire planes in multi wire proportional counters are not mandatory. The detector comprises of 48 individually instrumented channels in both X (MSGC strips) and Y (orthogonal wire plane). A specially designed encoding module has been constructed which feeds digital addresses for each event to the ISIS Data Acquisition Electronics (DAE) system. An intrinsic detector resolution of ∼1 mm full-width at half-maximum has been measured for both dimensions (in experimental exposures on the ROTAX beamline at ISIS) which is degraded slightly by the digital resolution for the overall system. This readout method is shown to be very tolerant of a poor signal to noise ratio in the readout channels (unlike traditional analogue wire chamber readout systems) and permits the operation of the MSGC at low avalanche gains (∼10) which helps to maximize the rate and lifetime performance of the detector as well as permitting data capture rates in the megahertz range. The event timing resolution is comfortably submicrosecond and is, therefore, suitable for applications on spallation neutron sources. [ABSTRACT FROM AUTHOR]

The development and testing of a two-dimensional (2-D) prototype detector based on a microstrip gas chamber (MSGC) are reported. The second coordinate is obtained by utilising a plane of wires as pick up electrodes. The detector is operated with the wire plane at such a potential so as not to induce any gain around the wires. This means that the high tolerances normally associated with wire planes in multiwire proportional counters are not necessary, making the manufacture and repair of such a device relatively easier. The detector comprises of 48 individually instrumented channels in both X (MSGC strips) and Y (transverse wire plane). A specially designed encoding module has been constructed which feeds digital addresses for each event to the ISIS data acquisiton electronics (DAE) system. (ISIS is the spaliation neutron source at the Rutherford Appleton Laboratory.) An intrinsic detector resolution of ∼ 0.5 mm full-width at half-maximum (FWHM) has been measured for both dimensions which is degraded slightly by the digital resolution for the overall system. This readout method is shown to be very tolerant of a poor signal-to-noise ratio in the readout channels (unlike traditional analogue wire chamber readout systems) and permits the operation of the MSGC at moderate avalanche gains (∼ 1000) which helps to maximize the rate and lifetime performance of the detector as well as permitting data capture rates in the MHz range. [ABSTRACT FROM AUTHOR]

We introduce the microhole and strip plate (MHSP) detector as a micropattern detector for the detection of thermal and epithermal neutrons. Detection sensitivity is obtained by filling these detectors with ³He at high pressures. We propose the use of argon-xenon penning mixtures as the stopping gas as opposed to the usual carbon based stopping gases. These argon-xenon mixtures provide suitable gas gains for the high pressure/high resolution neutron detector applications. With these mixture it is possible to obtain a sealed detector with only rare-gas filling which is simple to purify and not subject to ageing. An MHSP gas detector filled with a 3-bar argon/50-mbar xenon/6-bar helium mixture can achieve gains above 2 ×103. This mixture allows neutron detection efficiencies of about 70% at 1 Å for a 2.5-cm thick absorption region and intrinsic position resolution (full-width at half-maximum) of about 1.8 mm. The sensitivity to γ-rays of the present mixture will be the same when compared to that of 2.6-bar CF4. [ABSTRACT FROM AUTHOR]

Position sensitive detectors at the ISIS facility largely comprise of a mixture of 3He proportional counters and fibre-coded scintillation detectors based on ZnS/6LiF. The latest developments of these devices at ISIS will be discussed with reference to three ISIS instruments, MERLIN, GEM and ENGIN-X. MERLIN is the new chopper spectrometer now being developed at ISIS and features a large 2D detector array covering more than 20 m2 with a requirement in position resolution of 25×25 mm2. Resistive wire detectors are proposed for this detector, but to minimise gaps in the solid angle, detectors with active lengths of 2.9 m are being proposed. Initial results from prototype detectors will be presented. GEM is a general materials diffractometer now nearing completion and ENGIN-X is the engineering instrument, which became operational in November 2002. Detectors for both these instruments use linear arrays of fibre optic-encoded ZnS/6Li scintillator, with position resolutions of 5 and 3 mm, respectively. Work has now started on the construction of the ISIS second target station, TS-2. This facility will be tailored to the production of lower-energy neutrons compared with target station 1, with applications predominantly in soft condensed matter, bio-molecular sciences and advanced materials. The challenges this presents for future neutron detector development at ISIS will be reviewed together with some potential lines of detector development. [Copyright &y& Elsevier]

In this paper it is shown that solid-state cadmium-zinc-telluride (CZT) is a promising photon detector for neutron spectroscopy in a wide energy interval, ranging from thermal (∼25 meV) to epithermal (∼70 eV) neutron energies. In the present study two CZT detectors were tested as part of the inverse-geometry neutron spectrometer VESUVIO operating at the ISIS pulsed neutron source. The response of the CZT detector to photon emission from radiative neutron capture in [sup 238]U was determined by biparametric measurements of neutron time of flight and photon energy. The scattering response function F(y) from a Pb sample has been derived using both CZT and conventional [sup 6]Li-glass scintillator detectors. The former showed both an improved signal to background ratio and higher efficiency as compared to [sup 6]Li glass, allowing us to measure F(y) up to the fourth [sup 238]U absorption energy (E[sub r]=66.02 eV). Due to the small size of CZT detectors, their use is envisaged in arrays, with high spatial resolution, for neutron-scattering studies at high energy (ℎω>1 eV) and low wavevector (q <10 Å[sup -1]) transfers. [ABSTRACT FROM AUTHOR]

Reports on the instrumentation concepts proposed on the VESUVIO spectrometer at the ISIS spallation neutron source. Scientific interests of the proposal, including a study of short time single particle dynamics in quantum and molecular systems; Information on the deep inelastic neutron scattering, an experimental tool to derive a single particle momentum distribution; Effect of the high energy inelastic neutron scattering on the neutron spectroscopy on the VESUVIO instrument.

Scintillator-based ZnS:Ag/ 6 LiF neutron detectors have been under development at ISIS for more than three decades. Continuous research and development aim to improve detector capabilities, achieve better performance and meet the increasingly demanding requirements set by neutron instruments. As part of this program, a high-efficiency 2D position-sensitive scintillator detector with wavelength-shifting fibres has been developed for neutron-diffraction applications. The detector consists of a double scintillator-fibre layer to improve detection efficiency. Each layer is made up of two orthogonal fibre planes placed between two ZnS:Ag/ 6 LiF scintillator screens. Thin reflective foils are attached to the front and back scintillators of each layer to minimize light cross-talk between layers. The detector has an active area of 192 × 192 mm with a square pixel size of 3 × 3 mm. As part of the development process of the double-layer detector, a single-layer detector was built, together with a prototype detector in which the two layers of the detector could be read out separately. Efficiency calculations and measurements of all three detectors are discussed. The novel double-layer detector has been installed and tested on the SXD diffractometer at ISIS. The detector performance is compared with the current scintillator detectors employed on SXD by studying reference crystal samples. More than a factor of 3 improvement in efficiency is achieved with the double-layer wavelength-shifting-fibre detector. Software routines for further optimizations in spatial resolution and uniformity of response have been implemented and tested for 2D detectors. The methods and results are discussed in this manuscript., (© Giacomo Mauri et al. 2024.)

Experimental tests are presented that assess the cross-talk level among three scintillation detectors used as neutron counters exploiting the thermal neutron radiative capture on Cd. The measurements were done at the INES diffractometer operating at the ISIS spallation neutron source (Rutherford Appleton Laboratory, UK). These tests follow a preliminary set of measurements performed on the same instrument to study the effectiveness of this thermal neutron counting strategy in neutron diffraction measurements, typically performed on INES using squashed 3 He filled gas tubes. The experimental data were collected in two different geometrical configurations of the detectors and compared to results of Monte Carlo simulations, performed using the MCNP code., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The silicon photomultiplier (SiPM) is a recently developed photosensor used in particle physics, e.g., for detection of minimum ionizing particles and/or Cherenkov radiation. Its performance is comparable to that of photomultiplier tubes, but with advantages in terms of reduced volume and magnetic field insensitivity. In the present study, the performance of a gamma ray detector made of an yttrium aluminum perovskite scintillation crystal and a SiPM-based readout is assessed for use in time of flight neutron spectroscopy. Measurements performed at the ISIS pulsed neutron source demonstrate the feasibility of gamma-detection based on the new device.