Search results for "Neutron temperature"
showing 10 items of 103 documents
Exposure of -alanine and -ammonium tartrate ESR dosimeters to thermal neutrons: Experiments and Monte Carlo simulations
2008
Abstract Electron spin resonance solid state dosimetry with alanine and ammonium tartrate pellets is a valuable tool in both medical and industrial applications when dealing with photon and charged particle beams. Its use in neutron beams is limited by the low nuclear cross section values of atoms in the pellets. Addition of boron (10B) or gadolinium ( Gd 2 O 3 ) , known to have high neutron capture cross sections, has been proposed to improve neutron sensitivity. In this paper we present the results of an experimental study concerning neutron sensitivity vs. gadolinium concentration in dosimeter mixtures, with the aim of optimizing mixture composition and maximizing the electron spin resol…
Testing and linearity calibration of films of phenol compounds exposed to thermal neutron field for EPR dosimetry
2015
This paper reports the preliminary results obtained by Electron Paramagnetic Resonance (EPR) measurements on films of IRGANOX® 1076 phenols with and without low content (5% by weight) of gadolinium oxide (Gd2O3) exposed in the thermal column of the Triga Mark II reactor of LENA (Laboratorio Energia Nucleare Applicata) of Pavia (Italy). Thanks to their size, the phenolic films here presented are good devices for the dosimetry of beams with high dose gradient and which require accurate knowledge of the precise dose delivered. The dependence of EPR signal as function of neutron dose was investigated in the fluence range between 10(11) cm(-2) and 10(14) cm(-2). Linearity of EPR response was fou…
Effect of boron doping in the microwave surface resistance of neutron irradiated melt-textured Y1.6Ba2.3Cu3.3O7−x samples
2012
We report on the microwave surface resistance of melt-textured Y_1.6Ba_2.3Cu_3.3O_7-x samples, doped with different amount of B_2O_3 and, subsequently, irradiated by thermal neutrons at the fluence of 1.476 \times 10^17 cm^-2. The microwave surface resistance has been measured as a function of temperature and DC magnetic field. The experimental results are quantitatively discussed in the framework of the Coffey and Clem theory, properly adapted to take into account the d-wave nature of cuprate superconductors. By fitting the experimental data at zero DC field, we have highlighted the effects of the induced defects in the general properties of the samples, including the intergranular region.…
Evaluation of the displacement energy of Gd atoms in GdBa2Cu3O7−δ from experimental data
1994
Abstract The processing of experimental data on Gd-containing high-temperature superconductor degradation resulting from thermal neutron irradiation has made it possible to evaluate the ratio of the degradation rates of GdBa2Cu3O7−gd enriched with 155Gd and 157Gd isotopes respectively. The defect production in the compound due to (n, γ) reactions on Gd nuclei and consequent recoil of Gd nuclei emitting γ-quanta was simulated with experimentally determined γ-spectra by a Monte Carlo technique. The displacement probabilities pd(155) and pd(157) for different threshold energies Ed and the threshold energy of Gd atom displacement producing disordered bubbles in GdBa2Cu3O7−δ, E d ∗ ≈ 150 eV , we…
The SuperK-Gd Project
2018
The SuperK-Gd project is the proposed and approved upgrade of the Super-Kamiokande detector in order to enable it to efficiently detect thermal neutrons. The project consists in dissolving a Gd salt into SK at a concentration of 0.2%.
Creation of glass-characteristic point defects in crystalline SiO2 by 2.5 MeV electrons and by fast neutrons
2019
The support from M -ERANET project “MyND” is acknowledged. K.K. was partially supported by the Collaborative Research Project of Laboratory for Materials and Structures, Tokyo Institute of Technology . Visiting researcher support from Ecole Polytechnique, Palaiseau is appreciated. Mr. Olivier Cavani is thanked for the expert help with irradiations.
Combined TL and 10B-alanine ESR dosimetry for BNCT
2004
The dosimetric technique described in this paper is based on electron spin resonance (ESR) detectors using an alanine-boric compound acid enriched with 1 0 B, and beryllium oxide thermoluminescent (TL) detectors; with this combined dosimetry, it is possible to discriminate the doses due to thermal neutrons and gamma radiation in a mixed field. Irradiations were carried out inside the thermal column of a TRIGA MARK II water-pool-type research nuclear reactor, also used for Boron Neutron Capture therapy (BNCT) applications, with thermal neutron fluence from 10 9 to 10 1 4 n t h cm - 2 . The ESR dosemeters using the alanine-boron compound indicated ESR signals about 30-fold stronger than those…
EPR/ALANINE PELLETS WITH LOW Gd CONTENT FOR NEUTRON DOSIMETRY
2013
This paper reports on results obtained by electron paramagnetic resonance (EPR) measurements and Monte Carlo (MC) simulation on a blend of alanine added with low content of gadolinium oxide (5 % by weight) to improve the sensitivity to thermal neutron without excessively affecting tissue equivalence. The sensitivity is enhanced by this doping procedure of more an order of magnitude. The results are compared with those obtained with the addition of boric acid (50 % by weight) where boron is in its natural isotopic composition in order to produce low-cost EPR dosemeters. The gadolinium addition influences neutron sensitivity more than the boron addition. The presence of additives does not sub…
Alanine blends for ESR measurements of thermal neutron fluence in a mixed radiation field
2007
In this paper, the results of a study on the electron spin resonance (ESR) dosimetry to measure thermal neutron fluence in a mixed radiation field (neutron and photons) are presented. The ESR responses of alanine dosemeters with different additives are compared. In particular, the (10)B-acid boric and the Gd-oxide were chosen to enhance the sensitivity of alanine dosemeters to thermal neutrons. Irradiations were carried out inside the thermal column of the TAPIRO reactor of the ENEA center, Casaccia Rome. The main results are a greater neutron sensitivity and a smaller lowest detectable fluence for the dosemeters with gadolinium than for dosemeters of alanine with (10)B, which is well known…
Neutron flux and gamma dose measurement in the BNCT irradiation facility at the TRIGA reactor of the University of Pavia
2018
Abstract University of Pavia is equipped with a TRIGA Mark II research nuclear reactor, operating at a maximum steady state power of 250 kW. It has been used for many years to support Boron Neutron Capture Therapy (BNCT) research. An irradiation facility was constructed inside the thermal column of the reactor to produce a sufficient thermal neutron flux with low epithermal and fast neutron components, and low gamma dose. In this irradiation position, the liver of two patients affected by hepatic metastases from colon carcinoma were irradiated after borated drug administration. The facility is currently used for cell cultures and small animal irradiation. Measurements campaigns have been ca…