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ABSTRACT: Here we present a new concept for a time-of-flight neutron scattering instrument allowing for simultaneous application of three different techniques: time-of-flight neutron diffraction, neutron resonance capture analysis and Bragg edge transmission analysis. The instrument can provide average resolution neutron radiography too. The potential of the proposed concept was explored by implementing the necessary equipment on INES (Italian Neutron Experimental Station) at the ISIS spallation neutron source (UK). The results obtained show the effectiveness of the proposed instrument to acquire relevant quantitative information in a non-invasive way on a historical metallurgical sample, namely a Japanese hand guard (tsuba). The aforementioned neutron techniques simultaneously exploited the extended neutron energy range available from 10 meV to 1 keV. This allowed a fully satisfactory characterization of the sample in terms of metal components and their combination in different phases, and forging and assembling methods.
EPL (Europhysics Letters) 08/2011; 95(4):48007. · 2.17 Impact Factor
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A. Pietropaolo,
C. Andreani,
M. Rebai,
L. Giacomelli,
G. Gorini,
E. Perelli Cippo,
M. Tardocchi,
A. Fazzi,
G. Verona Rinati,
C. Verona,
Marco Marinelli,
E. Milani,
C. D. Frost, E. M. Schooneveld
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ABSTRACT: A novel type of fast-neutron (energy En>1 MeV) counter is presented. It is made of a fissionable natural-uranium foil faced to an intrinsic single-crystal diamond that detects the neutron-induced fission fragments escaping the uranium sheet. The fast response of the diamond is a key feature for its use at pulsed spallation neutron sources for applications in beam monitoring and spectrum measurements with mm spatial resolution. This is an important issue to be addressed in the development of beam lines dedicated to the investigation of the so-called single-event effects in electronics, such as the ChipIr instrument designed for the ISIS spallation source in the UK. Tests of the device at the ROTAX beam line at ISIS have shown its potentiality for the proposed application.
EPL (Europhysics Letters) 06/2011; 94(6):62001. · 2.17 Impact Factor
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ABSTRACT: 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.
The Review of scientific instruments 09/2009; 80(9):095108. · 1.52 Impact Factor
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ABSTRACT: A new neutron resonant transmission (NRT) detector for epithermal neutron imaging has been designed and built for the ANCIENT CHARM project, which is developing a set of complementary neutron imaging methods for analysis of cultural heritage objects. One of the techniques being exploited is NRT with the aim of performing bulk elemental analysis. The 16-pixel prototype NRT detector consists of independent crystals of 2 × 2 mm pixel size, which allow for 2D position-sensitive transmission measurements with epithermal neutrons. First results obtained at the ISIS pulsed spallation neutron source are presented.
Journal of Physics D Applied Physics 07/2009; 42(15):152003. · 2.54 Impact Factor
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ABSTRACT: A gas electron multiplier with a micro-induction gap amplifying structure (GEM-MIGAS) is formed when a conventional GEM is operated with a short induction gap, typically set at 50 mum. Experimental studies were carried out to investigate the single-electron response of a GEM-MIGAS, using a He/iso-C<sub>4</sub>H<sub>10</sub> (85/15%) gas mixture operated in a flow mode at atmospheric pressure. The additional charge multiplication in the induction gap results in a gain increase up to one order of magnitude when compared to the GEM mode operation alone. A series of measurements were undertaken to examine the pulse height distributions induced by single-electrons under a wide range of bias voltages applied across the GEM holes, 100 to 550 V, and for a wide range of electric fields in the induction gap, 0.6 to 100 kV/cm. It was possible to sustain effective charge gains in excess of 3times10<sup>5</sup> B and multiplication relative variances around 0.4 over a large range of GEM voltages, enabling us to demonstrate single-electron detection efficiencies above 98%.
IEEE Transactions on Nuclear Science 09/2008; · 1.45 Impact Factor
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E Perelli Cippo,
G Gorini,
M Tardocchi,
R Cattaneo,
N J Rhodes, E M Schooneveld,
T Nakamura,
P Radaelli,
W A Kockelmann,
A Pietropaolo,
the ANCIENT CHARM Collaboration
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ABSTRACT: A position sensitive detector for epithermal neutrons is being developed as a tool for neutron resonance tomography at pulsed neutron sources. Neutron-scattering effects in the detector elements were investigated with GEANT4 simulations. The simulations show that the effect of neutron scattering is generally low, and can be further suppressed by proper choice of construction materials.
Measurement Science and Technology 01/2008; 19(3):034027. · 1.49 Impact Factor
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ABSTRACT: Strong demand exists for an experimental facility enabling new experimental investigations on condensed matter systems based
on epithermal neutron scattering at high energy and low momentum transfers. This need will be met by the very low angle detector
(VLAD) bank, to be installed on the VESUVIO spectrometer at the ISIS spallation neutron source. The equipment will operate
in the scattering angular range 1°<2θ<5°. Scattering measurements from a polycrystalline ice sample using a VLAD prototype
demonstrates the effectiveness of the detection technique adopted for the construction of the full detector array. The resulting
density of states in ice is 9±2 atoms/cell, in agreement with previous measurements.
Applied Physics A 01/2006; 83(3):453-460. · 1.63 Impact Factor
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ABSTRACT: We report a recent study undertaken at the Council for the Central Laboratory of the Research Councils (CCLRC) Rutherford Appleton Laboratory to evaluate the performance of a gas electron multiplier (GEM) coupled with a microstrip gas counter (MSGC) for X-ray spectroscopy. The parameters investigated during this study were effective gain, effective gain stability, and energy resolution at 8.05 keV using Cu-K X-rays. These parameters were studied as a function of drift field, induction field, and potential differences across the GEM holes and that across the MSGC anodes and cathodes. This study demonstrates that a single stage GEM can sustain effective gains up to 6000 whilst retaining adequate X-ray energy resolution. By utilizing the MSGC as well as the GEM amplification the gains easily exceed 100 000 and allow the MSGC operation at much lower voltages. This study also demonstrates that the introduction of the GEM preamplification to the MSGC enables the operation of the latter at much higher effective gains (30 000) before any degradation in the X-ray energy resolution
IEEE Transactions on Nuclear Science 01/2006; · 1.45 Impact Factor
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ABSTRACT: 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 <sup>3</sup>He and 2.5 bar CF<sub>4</sub>. 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.
IEEE Transactions on Nuclear Science 11/2005; · 1.45 Impact Factor
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ABSTRACT: The design and prototype tests of the Very Low Angle Detector (VLAD) for epithermal neutron scattering at low momentum transfers are presented. The detector will be installed on the VESUVIO spectrometer at the ISIS spallation neutron source for so-called High-energy Inelastic Neutron Scattering (HINS) experiments. It will consist of an array of Resonant Detectors (RD) covering the scattering range 1 $^circ$ –5 $^circ$ . The results of prototype tests with a reduced set of RD units demonstrate the feasibility of the measurement in the adverse environmental conditions of ISIS. Simulations of particle interactions using the GEANT4 code show that the envisaged detector design can meet the requirements in terms of efficiency, cross-talk between detection channels and neutron scattering events in the detector.
IEEE Transactions on Nuclear Science 09/2005; · 1.45 Impact Factor
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ABSTRACT: 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 acquisition electronics (DAE) system. (ISIS is the spallation 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.
IEEE Transactions on Nuclear Science 07/2005; · 1.45 Impact Factor
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ABSTRACT: Results on the application of the resonant detector (RD) for epithermal neutron scattering in an unexplored kinematical region are presented. The RD is based on resonance radiative neutron capture for energy analysis of the scattered neutrons in an inverse geometry time of flight spectrometer. Application of the RD to detection of epithermal neutrons at very low scattering angles allows access to an unexplored scattering kinematical region, the High-energy Inelastic Neutron Scattering (HINS) region, of low wave vector (3 Å <sup>-1</sup>≪q≪10 Å <sup>-1</sup>) and high energy transfers (0.1 eV ≪ω≪10 eV ) . Results of HINS measurements from polycrystalline ice are presented.
Applied Physics Letters 12/2004; · 3.84 Impact Factor
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ABSTRACT: The design and prototype tests of the Very Low Angle Detector (VLAD) for epithermal neutron scattering at low momentum transfers are presented. The detector will be installed on the VESUVIO spectrometer at the ISIS spallation neutron source for so-called High-energy Inelastic Neutron Scattering (HINS) experiments. It will consist of an array of resonant detectors covering the scattering range 1°-5°. The results of prototype tests with a reduced set of RD units demonstrate the feasibility of the measurement in the adverse environmental conditions of ISIS. Simulations of particle interactions using the GEANT4 code show that the envisaged detector design can meet the requirements in terms of efficiency, cross-talk between detection channels and neutron scattering events in the detector.
Nuclear Science Symposium Conference Record, 2004 IEEE; 11/2004
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ABSTRACT: The development and testing of a 2-D prototype detector based on a gas microstrip detector (GMSD) is reported using a gas mixture of 2.5 bar <sup>3</sup>He and 2.5 bar CF<sub>4</sub>. 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 (GMSD 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 taking electronics system (DAE). An intrinsic detector resolution of ∼1 mm FWHM 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 GMSD at low avalanche gains (∼10) which helps to maximise the rate and lifetime performance of the detector as well as permitting data capture rates in the MHz range. The event timing resolution is comfortably sub microsecond and is therefore suitable for applications on spallation neutron sources.
Nuclear Science Symposium Conference Record, 2004 IEEE; 11/2004
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[show abstract]
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ABSTRACT: The development and testing of a 2-D prototype detector based on a gas microstrip detector (GMSD) is 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 multi wire 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 (GMSD strips) and V (transverse wire plane). A specially designed encoding module has been constructed which feeds digital addresses for each event to the ISIS data taking electronics system (DAE). An intrinsic detector resolution of ∼0.5 mm 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 GMSD at moderate avalanche gains (∼1000) which helps to maximise the rate and lifetime performance of the detector as well as permitting data capture rates in the MHz range.
Nuclear Science Symposium Conference Record, 2004 IEEE; 11/2004
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ABSTRACT: 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 <sup>3</sup>He 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 mixtures 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 2×10<sup>3</sup>. 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 CF<sub>4</sub>.
IEEE Transactions on Nuclear Science 11/2004; · 1.45 Impact Factor
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ABSTRACT: 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 (25meV) to epithermal (70eV) 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 238U 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 6Li-glass scintillator detectors. The former showed both an improved signal to background ratio and higher efficiency as compared to 6Li glass, allowing us to measure F(y) up to the fourth 238U absorption energy (Er=66.02eV). 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 (>1eV) and low wavevector (q
<10-1) transfers.
Applied Physics A 02/2004; 78(6):903-913. · 1.63 Impact Factor
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ABSTRACT: We propose the use of argon-xenon penning-mixtures as the stopping gas, in substitution of carbon-based gases, in <sup>3</sup>He neutron detectors. Such stopping gas presents a solution for the use of GEMS or MHSPs electron multipliers with suitable gains for neutron detection. With these mixtures it is possible to obtain a sealed detector with only rare-gas filling which is simple to purify and not subject to ageing. A MHSP gas detector filled with a 3-bar argon/50-mbar xenon/6-bar helium mixture can achieve gains above 2 × 10<sup>3</sup>. This mixture allows neutron detection efficiencies of about 70% for a 2.5-cm thick absorption region and intrinsic position resolution (FWHM) of about 1.7-mm. Increasing the argon partial pressure to 6-bar, it is possible to reduce the detector intrinsic position resolution to 1-mm. The sensitivity to γ-rays will be the same when compared to that of 2.6-bar CF<sub>4</sub>.
Nuclear Science Symposium Conference Record, 2003 IEEE; 11/2003
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ABSTRACT: The Micro-Hole and Strip Plate (MHSP) is a hybrid electron multiplier which combines the working principles of a Gas Electron Multiplier (GEM) and a Micro-Strip Gas Counter (MSGC). The compact double stage electron multiplication processes found in the MHSP enables the realisation of higher gas gain than the lone GEM operation. Thermal neutron detection using gas detectors involves the use of gas with another suitable stopping gas, operated at elevated pressure to confine the products of the neutron- reaction. It is, however, well known that the gain of GEMs drops too sharply with increasing chamber pressure.We have pursued experimental work using the MHSP to infer the upper limits of thermal neutron position resolution. The stopping gas used during the present studies was Tetrafluoromethane (CF4) chosen due to its low X-ray and γ-ray efficiency, requiring only 2.6 bar to yield a position resolution of 1 mm. In the present studies, systematic measurements were taken to establish the gain versus CF4 pressure characteristics of the MHSP, in the 1 to 2.65 bar range. These studies demonstrated that it was possible to sustain gains above 104 and 300 with pressures of 1 and 2.65 bar, respectively. The advantage of having two multiplication stages in the MHSP separated by only few tens of microns, results in a less pronounced gain reduction with pressure, presenting higher gains than single or multiple GEMs. The energy resolution at 1 bar was 29% FWHM for the 5.9 keV Mn Kα line from a source, which is a typical value for micro-patterned gas detectors operating in CF4.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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ABSTRACT: A Gas Electron Multiplier with Micro-Induction Gap Amplifying Structure (GEM-MIGAS) is formed when the induction gap of the GEM is set between 50 and 100 μm using kapton pillars spaced at regular intervals. This configuration combines the properties of a GEM and Micromegas, allowing operation in tandem to generate high charge gains. We measured the essential operational parameters of this system using argon–isobutane (IB) and helium–IB gas mixtures. The present short induction gap GEM was able to achieve effective gains exceeding 2×104 using argon–IB and 105 using helium–IB mixtures. In view of the high gains achieved, particularly when using helium-based gas mixtures, these studies confirmed the possibility of using the present system for high-performance sub-keV X-ray detection.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
