Search results for "IRRADIATION"

Irradiation induced defects in fluorine doped silica

2008

International audience; The role of fluorine doping in the response to UV pulsed laser and c radiation of silica preforms and fibers was studied using electron spin resonance (ESR) spectroscopy. Exposure to radiation mainly generates E0 centers, with the same effectiveness in fibers and in preforms. The E'concentration in F-doped silica fibers is found to increase with UV energy fluence till a saturation value, consistently with a precursor conversion process. These results show the fluorine role in reducing the strained Si–O bonds thus improving the radiation hardness of silica, also after drawing process.

Isotopic Enriched and Natural SiC Junction Barrier Schottky Diodes Under Heavy Ion Irradiation

2022

The radiation tolerance of isotopic enriched and natural silicon carbide junction barrier Schottky diodes are compared under heavy ion irradiation. Both types of devices experience leakage current degradation as well as single-event burnout events. The results were comparable, although the data may indicate a marginally lower thresholds for the isotopic enriched devices at lower linear energy transfer (LET). Slightly higher reverse bias threshold values for leakage current degradation were also observed compared to previously published work.

Efficiency and timing performance of the MuPix7 high-voltage monolithic active pixel sensor

2018

The MuPix7 is a prototype high voltage monolithic active pixel sensor with 103 times 80 um2 pixels thinned to 64 um and incorporating the complete read-out circuitry including a 1.25 Gbit/s differential data link. Using data taken at the DESY electron test beam, we demonstrate an efficiency of 99.3% and a time resolution of 14 ns. The efficiency and time resolution are studied with sub-pixel resolution and reproduced in simulations.

Measurement of proton and nitrogen polarization in ammonia and a test of equal spin temperature

1998

The 1996 data taking of the SMC experiment used polarized protons to measure the spin-dependent structure function g(1) of the proton. Three liters of solid granular ammonia were irradiated at the Bonn electron linac in order to create the paramagnetic radicals which are needed for polarizing the protons. Proton polarizations of +/- (90 +/- 2.5)% were routinely reached. An analysis based on a theoretical line shape for spin-1. systems with large quadrupolar broadening was developed which allowed the nitrogen polarization in the ammonia to be determined with a 10% relative error. The measured quadrupolar coupling constant of N-14 agrees well with earlier extrapolated values. The polarization…

Determination of methemoglobin in human blood after ionising radiation by EPR

2015

In the present work presents results of investigations of radiation influence on blood of patients examined by radio-isotopes diagnosis (Tc 99m ), blood of Chernobyl clean-up workers and human blood irradiated by LINAC using Electron Paramagnetic Resonance (EPR). The EPR spectroscopy reveals information on electronic states of transition metal ions, particularly Fe 3+ in different spin states. It is shown that EPR spectra of blood of patients before examination has signal from metal-protein transferrin (g=4.3) and after administration of radio- isotope proves signal of Fe 3+ (methemaglobin) in the high spin state (g=6.0). The EPR spectra of Chernobyl liquidator display number of signals inc…

Erratum to "Determination of the irradiation field at the research reactor TRIGA Mainz for BNCT" [J. Appl. Radiat. Isot. 67 (2009) S242-S246].

2016

Heavy isotopes of actinium: 229Ac, 230Ac, 231Ac and 232Ac

1973

Abstract By irradiation of 232Th with 150-MeV bremsstrahlung and with 14-MeV neutrons, three new neutron-rich isotopes of actinium, 230Ac, 231Ac and 232Ac, were produced and identified and the previously reported isotope, 229Ac, was confirmed. The actinium isotopes were chemically isolated by a fast procedure based on elution with α-hydroxyisobutyric acid from cation exchange resins. For 229Ac, a half-life of 62·7 ± 0·5 min and a β-ray energy of 1·14 ± 0·15 MeV were found; 35 γ-rays were observed, the strongest ones with the following energies and relative intensities: 135·3(34), 146·4(35), 164·6(100), 252·2(24), 261·9(39), 317·0(23), 539·9(20), 569·1(91), and 605·2 keV(23). For 230Ac, a ha…

The Szilard–Chalmers effect in macrocyclic ligands to increase the specific activity of reactor-produced radiolanthanides: Experiments and explanatio…

2012

Abstract Successful utilization of medical isotopes in the radiolabeling reactions to a significant degree depends on the technically achievable specific activity. In this respect, the Szilard-Chalmers effect is considered in detail as a radiochemical tool to increase the specific activity of radionuclides produced by direct nuclear reactions. In the present study, a physico-chemical model is described utilizing the specific aspects of thermodynamically and kinetically stabilised metal-ligand complexes. The approach is applied as a proofof- principle study to increase the specific activity of 166Ho, produced via the (n, γ) nuclear reaction. As a target material, 165Ho-DOTA is used. In this …

Study of Proton and 3He Induced Reactions on 235U at Low Energies

2014

Abstract Highly enriched 235 U targets were irradiated with 6.5 − 16.1 MeV protons and 20.4 − 42.0 MeV 3 He ions. The irradiated targets were measured with γ and α spectrometric methods to identify and quantify the produced reaction products. After primary activity measurements the targets were dissolved, and interesting Pu and Np reaction products were chemically separated from the target material, and measured for activity again. From the activity results it was possible to calculate the reaction cross sections for differently produced nuclides. The data obtained from the experiment resulted in earlier unknown excitation functions on proton and 3 He induced nuclear reactions on 235 U.

Mycotoxin contamination of animal feedingstuff: detoxification by gamma irradiation and reduction of aflatoxins and ochratoxin A concentrations

2014

Mycotoxins are fungal secondary metabolites identified in many agricultural products screened for toxigenic moulds. They have been reported to be carcinogenic, teratogenic, tremorogenic, haemorrhagic and dermatitic to a wide range of organisms. With the increasing stringent regulations for mycotoxins imposed by importing countries such as those of the European Union, many cereals that are not safe for human consumption are used in formulations intended for animal feed. Gamma-rays are reported in the scientific literature to destroy ochratoxin A and aflatoxin in food crops and feed. The present study provides preliminary data for establishing the effect of dose of gamma-irradiation, ranging …