50 research outputs found
Design study of the imaging beam line at J-PARC MLF, ERNIS
No full textWe have a plan to build an imaging beam line, ERNIS (Energy-Resolved Neutron Imaging System), at MLF (Materials and Life Science Experimental Facility) at J-PARC (Japan Proton Accelerator Research Complex). In pulsed neutron imaging, we use characteristic features of the neutron total cross section, depending on the neutron wavelength, to get sample information such as crystallographic structure and nuclide composition. One of the most important items to be determined for a beam line at J-PARC is the choice of moderator among coupled, decoupled, and poisoned moderators. From the wavelength resolution point of view, we decided to use the decoupled moderator, which could cover major experiments performed at a pulsed neutron source. Here, we discuss the structure of the imaging beam line at beam line 22 of the J-PARC neutron source as well as the arrangement of insertion devices and the experimental area
Energy resolution of pulsed neutron beam provided by the ANNRI beamline at the J-PARC/MLF
No full textWe studied the energy resolution of the pulsed neutron beam of the Accurate Neutron-Nucleus Reaction Measurement Instrument (ANNRI) at the Japan Proton Accelerator Research Complex/Materials and Life Science Experimental Facility (J-PARC/MLF). A simulation in the energy region from 0.7 meV to 1 MeV was performed and measurements were made at thermal (0.76-62 meV) and epithermal energies (4.8-410 eV). The neutron energy resolution of ANNRI determined by the time technique depends on the Lime structure of the neutron pulse. We obtained the neutron energy resolution as a function of the neutron energy by the simulation in the two operation modes of the neutron source: double- and single bunch modes in double bunch mode, the resolution deteriorates above about 10 eV because the time structure of the neutron pulse splits into two peaks. The time structures at 13 energy points from measurements in the thermal energy region agree with those of the simulation. In the epithermal energy region, the time structures at 17 energy points were obtained from measurements and agree with those of the simulation. The FWHM values of the time structures by the simulation and measurements were found to be almost consistent. In the single-bunch mode, the energy resolution is better than about 1% between 1 meV and 10 keV at a neutron source operation of 17.5 kW. These results confirm the energy resolution of the pulsed neutron beam produced by the ANNRI beamline. (C) 2013 Elsevier B.V. All rights reserved
A NEW TECHNIQUE FOR DIRECTLY PROBING THE INTRINSIC TRISTABILITY AN DITS TEMPERATURE-DEPENDENCE IN A RESONANT-TUNNELING DIODE
No full text3D Radiation Detectors: Charge Collection Characterisation and Applicability of Technology for Microdosimetry
No full textA study of charge collection in SINTEF 3D active edge silicon detectors was carried out at ANSTO using Ion Beam Induced Charge (IBIC) technique. An IBIC study has shown that several different geometries of 3D detectors have full depletion under low applied bias. The effect of fast neutron and gamma radiation on their charge collection efficiency was also investigated. A 3D active edge silicon detector technology has demonstrated extremely promising performance for application of the 3D Sensitive Volumes (SVs) fabrication methods to SOI microdosimetry.© 2014, IEEE
Effect of fibre treatments on tensile properties of ethylene vinyl acetate/natural rubber/mengkuang leaf fibre (EVA/NR/MLF) thermoplastic elastomer composites
No full textEvaluation of silicon detectors with integrated JFET for biomedical applications.
No full textThis paper presents initial results from electrical, spectroscopic and ion beam induced charge (IBIC) characterisation of a novel silicon PIN detector, featuring an on-chip n -channel JFET and matched feedback capacitor integrated on its p-side (frontside). This structure reduces electronic noise by minimising stray capacitance and enables highly efficient optical coupling between the detector back-side and scintillator, providing a fill factor of close to 100%. The detector is specifically designed for use in high resolution gamma cameras, where a pixellated scintillator crystal is directly coupled to an array of silicon photodetectors. The on-chip JFET is matched with the photodiode capacitance and forms the input stage of an external charge sensitive preamplifier (CSA). The integrated monolithic feedback capacitor eliminates the need for an external feedback capacitor in the external electronic readout circuit, improving the system performance by eliminating uncontrolled parasitic capacitances. An optimised noise figure of 152 electrons RMS was obtained with a shaping time of 2 mus and a total detector capacitance of 2 pF. The energy resolution obtained at room temperature (2°C) at 27 keV (direct interaction of I-125 gamma rays) was 5.09%, measured at full width at half maximum (FWHM). The effectiveness of the guard ring in minimising the detector leakage current and its influence on the total charge collection volume is clearly demonstrated by the IBIC images. © 2009, Institute of Electrical and Electronics Engineers (IEEE
Representative brainstem fiber tracts and corresponding neuroanatomy in two brainstem levels.
No full textLeft: color-coded anisotropic map (red: left-right oriented; blue: superior-inferior oriented; green: anterior-posterior oriented); Middle: six brainstem reticular tracts superimposed on a T1WI; Right: corresponding anatomic sections. Abbreviations: CP = cerebral peduncle; ML = medial lemniscus; STT = spinothalamic tract; MCP = middle cerebellar peduncle; SCP = superior cerebellar peduncle; MLF = medial longitudinal fasciculus); DLF = dorsal longitudinal fasciculus; MFT = Medial Forebrain Tract; NST = nigrostriatal tract; LC = locus coeruleus; PAG = periaqueductal gray matter. The brainstem anatomical pictures are downloaded from the web site (http://www.dartmouth.edu/~rswenson/Atlas/BrainStem/index.html) with permission of the author.</p
Development of a large-area silicon α-particle detector
No full textCircular ion-implanted silicon detector of α-particles with a large, 5-cm2, sensitive area has been developed. An advantage of the detector is that the detector surface is easily cleanable with chemicals. The hardened surface of the detector shows no signs of deterioration of the spectroscopic and electrical characteristics upon repeated cleaning. The energy resolution along the diameters of the detector was (1.0±0.1)% for the 5.486-MeV α-particles. Detailed tests of the charge collection efficiency and uniformity of the detector entrance window were also performed with a 5.5-MeV He2+ microbeam. © 2014, Elsevier Ltd
A novel silicon microdosimeter using 3D sensitive volumes: modeling the response in neutron fields typical of aviation
No full textA 4th generation silicon microdosimeter has been designed by the Centre for Medical Radiation Physics (CMRP) at the University of Wollongong using three dimensional (3D) Sensitive Volumes (SVs). This new microdosimeter design has the advantage of well-defined 3D SVs as well as the elimination of lateral charge diffusion by removal of silicon laterally adjacent to the 3D SVs. The gaps between the sensitive volumes are to be backfilled with PolyMethyl MethAcrylate (PMMA) to produce a surrounding tissue equivalent medium. The advantage of this design avoids the generation of secondary particles from inactive silicon lateral to SVs. The response of the microdosimeter to the neutron field from 252Cf, Pu-Be sources and an avionic radiation environment were simulated using the Geant4 Monte Carlo toolkit for design optimisation. The simulated energy deposition in the SVs from the neutron fields and microdosimetric spectra is presented. The simulation study shows a significant reduction in silicon nuclear recoil contribution to the energy deposition for the novel microdosimeter design. The reduction of silicon recoil events from outside of the SV's will consequently reduce the uncertainty in the calculated dose equivalent. The simulations have demonstrated that a 3D silicon microdosimeter surrounded by PMMA can produce microdosimetric spectra similar to those of a tissue equivalent microdosimeter.© 2014, IEEE
