Search results for "Neutron temperature"
showing 10 items of 103 documents
Effects of Thermal Neutron Irradiation on a Self-Refresh DRAM
2020
International audience; In this study, static and dynamic test methods were used to define the response of a self-refresh DRAM under thermal neutron irradiation. The neutron-induced failures were investigated and characterized by event cross-sections, soft-error rate and bitmaps evaluations, leading to an identification of permanent and temporarily stuck cells, block errors, and single-bit upsets.
EPR and optical spectroscopy of neutron-irradiated Gd3Ga5O12 single crystals
2020
Abstract In this paper, we have performed comparative analysis of EPR, optical absorption (OA) and luminescence spectra for a series of Gd3Ga5O12 (GGG) single crystals irradiated with fast neutrons with fluencies varied from 1016 to 1020n/cm2. In a crystal irradiated with the maximum neutron fluence, the EPR spectra demonstrated the formation of several paramagnetic defects. In particular, EPR spectrum shows a strong resonance at (effective) g ≈ 1.4 with practically isotropic behavior in the crystal rotation around the [1 1 1] direction (magnetic field being perpendicular to [1 1 1]) and several weaker lines in the g ≈ 1.1–2.6 region, which show more pronounced angular dependences. While th…
Optical properties of natural topaz
2013
The results of investigation of infrared, Raman and UV-Visible absorption spectra of natural topaz crystals from Ukraine before and after fast neutron irradiation are presented. We assume that the ~ 620 nm band in topaz crystals is associated with the presence of Cr 3+ , Fe 2+ and Mn 2+ impurities. The broad band with maxima at 650 cm -1 observed in Raman spectra for topaz irradiated by fast neutrons may be connected with lattice disorder. Exchange interaction between radiation defect and impurity ions during neutron irradiation leads to appearance of additional absorption band in UV-VIS spectra and bands broadening in infrared and Raman spectra of investigated crystals.
Determination of phosphorus by instrumental neutron activation and bremsstrahlung measurement in bone samples
1997
A non destructive method based on the31P(n,γ)32P reaction for the assay of phosphorus in bone samples is described. This method involves a thermal neutron irradiation of 2 minutes in a reactor followed by the measurement of the bremsstrahlung produced by the β− of32P in a Ge-detector surrounded by an anti-Compton shield. Accuracy and precision were tested by analysing the certified NIST 1486 Bone Meal reference material and tri-calcium phosphate (Ca3(PO4)2) samples. The value obtained for the reference material was in good agreement with the certified value and with relative standard deviation of 4.1% the precision was acceptable. The value obtained for Ca3(PO4)2 shows a deviation of −6% fr…
Comparison of EPR response of alanine and Gd2O3-alanine dosimeters exposed to TRIGA Mainz reactor.
2015
In this work we report some preliminary results regarding the analysis of electron paramagnetic resonance (EPR) response of alanine pellets and alanine pellets added with gadolinium used for dosimetry at the TRIGA research reactor in Mainz, Germany. Two set-ups were evaluated: irradiation inside PMMA phantom and irradiation inside boric acid phantom. We observed that the presence of Gd2O3 inside alanine pellets increases the EPR signal by a factor of 3.45 and 1.24 in case of PMMA and boric acid phantoms, respectively. We can conclude that in the case of neutron beam with a predominant thermal neutron component the addition of gadolinium oxide can significantly improve neutron sensitivity of…
Monte Carlo simulation of the response of ESR dosimeters added with gadolinium exposed to thermal, epithermal and fast neutrons
2009
Abstract Monte Carlo numerical calculations of the response of alanine and ammonium tartrate ESR (electron spin resonance) dosimeters exposed to neutron fields with different energy spectra are reported. Results have been obtained for various gadolinium concentrations inside the dosimeters. Furthermore, in order to simulate the in-phantom response we have carried out calculations by varying the depth of the dosimeter. We have found that a large enhancement is obtained for thermal neutrons, because of the very high capture cross section of gadolinium to thermal neutrons. A good enhancement was obtained for epithermal neutrons, whereas the sensitivity improvement in the case of fast neutron i…
The alanine detector in BNCT dosimetry: Dose response in thermal and epithermal neutron fields
2014
Purpose: The response of alanine solid state dosimeters to ionizing radiation strongly depends on particle type and energy. Due to nuclear interactions, neutron fields usually also consist of secondary particles such as photons and protons of diverse energies. Various experiments have been carried out in three different neutron beams to explore the alanine dose response behavior and to validate model predictions. Additionally, application in medical neutron fields for boron neutron capture therapy is discussed. Methods: Alanine detectors have been irradiated in the thermal neutron field of the research reactor TRIGA Mainz, Germany, in five experimental conditions, generating different secon…
Position-sensitive neutron detector
2002
Abstract A position-sensitive neutron detector has been developed for use in nuclear physics research. The detector consists of a ∅5.5 cm×100 cm long quartz tube filled with liquid scintillator viewed from both ends by photomultipliers and enclosed in a light-tight titanium container. The properties of the detector were determined both experimentally and by Monte Carlo simulations (EFEN code). A time resolution of 0.4 ns was reached resulting in the position resolution of less than 4 cm. The neutron registration efficiency varies from 36% to 20% within neutron energy range 1–10 MeV and is practically independent of the position along the detector length. Good n–γ separation is achieved for …
Chronological development of element concentrations in grapes during growth and ripeness and during fermentation of must determined by instrumental n…
2014
Abstract The chronological development of element concentrations during growth and ripeness of grapes described in the literature has only been concerned with the macro elements Mg, K, and Ca. Concentrations of trace elements in must are only described as a snapshot at the end of the ripeness. Therefore, the motivation for the present work was to accompany the growth and the ripening process of grapes successively by systematically determining element concentrations in grapes of Riesling and Cabernet Sauvignon by neutron-activation analyses. While for a number of elements, the concentrations in the grapes increased as a function of grape development (e.g., Na, K, Rb, Al), other concentratio…
On-line Mössbauer measurements at low temperatures of 83mKr implanted into Al
1978
Abstract A vacuum ion implantation chamber housing a helium flow cryostat and a Mossbauer transducer has been constructed and coupled directly to an ion separator for low temperature implantation and on-line Mossbauer measurements. 83m Kr, produced by thermal neutron activation of enriched 82 Kr gas, has been implanted into Al foils in the temperature range 15–300 K. Annealing effects and the temperature dependence of the Lamb-Mossbauer factor have been studied by Mossbauer measurements (at 15–35 K) using the implanted Al targets as sources and Kr/hydrochinone as absorber.