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Applied Radiation and Isotopes

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https://www.readbyqxmd.com/read/29335157/thermal-and-epithermal-neutron-flux-distributions-measurement-in-thermal-column-of-trr-using-an-experimental-simulation-method
#1
Ruhollah Adeli, Yaser Kasesaz, Seyed Pezhman Shirmardi, Arsalan Ezaty
For designing an appropriate neutron beam, the determination of neutron flux at any irradiation facility is an important key factor. Due to the importance of determining the thermal and epithermal neutron fluxes in a typical thermal column of a reactor, a simple and accurate technique is introduced in this study. Absolute thermal and epithermal fluxes were measured experimentally at a certain point using the foil activation method by neutron bombardment of bare and cadmium covered Au foils. The relative neutron fluxes were also derived simply by means of Monte Carlo simulation by accurate modelling of the reactor components...
December 28, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29331926/two-hump-shaped-angular-distributions-of-neutrons-and-soft-x-rays-in-a-small-plasma-focus-device
#2
Morteza Habibi
Angular distributions of soft X-rays (SXRs) and neutrons emitted by a small plasma focus device (PFD) were investigated simultaneously using TLD-100 dosimeters and Geiger-Muller activation counters, respectively. The distributions represented two humps with a small dip at the angular position 0° and reduced from the angles of ± 15° and ± 30° for the neutrons and SXRs, respectively. The maximum yield of 2.98 × 108 neutrons per shot of the device was obtained at 13.5kV and 6.5mbar. A time of flight (TOF) of 75...
December 28, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29310104/estimation-of-photoneutron-dosimetric-characteristics-in-tissues-organs-using-an-improved-simple-model-of-linac-head
#3
Rahim Khabaz, Roya Boodaghi, Mohammad Reza Benam, Vahid Zanganeh
Neutrons as a one of the by-products of high-energy photons in radiotherapy increase the patient's risks and could cause secondary cancers. Therefore, a new corrected simplified model for linac head was introduced to calculate equivalent (H) and absorbed (D) doses in different tissues/organs of a phantom model. The photoneutron spectrum calculated with this model was in agreement with the spectrum obtained by using a detailed linac´s head model having all components. Besides, an anthropomorphic phantom was irradiated under different gantry angles of the corrected simplified model aiming to emulate 15, 18, 20, and 25MV Siemens linacs...
December 28, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29310103/calculation-of-neutron-spectra-produced-in-neutron-generator-target-code-testing
#4
V V Gaganov
DT-neutron spectra calculated using the SRIANG code was benchmarked against the results obtained by widely used Monte Carlo codes: PROFIL, SHORIN, TARGET, ENEA-JSI, MCUNED, DDT and NEUSDESC. The comparison of the spectra obtained by different codes confirmed the correctness of SRIANG calculations. The cross-checking of the compared spectra revealed some systematic features and possible errors of analysed codes.
December 28, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29294419/development-of-a-prototype-hybrid-l-edge-l-xrf-densitometer-for-nuclear-fuel-assay
#5
Sungyeop Joung, Seunghoon Park
The hybrid L-edge/L-XRF densitometer (HLED) was developed for on-site nuclear fuel assays intended for safeguards purpose. The HLED can simultaneously measure both X-ray photon transmissions and characteristic X-ray emissions, which characterizes the elemental composition of samples of interest to determine the concentration of actinide-bearing materials, such as plutonium and uranium, in a nuclear fuel. A prototype of the HLED equipment was fabricated and tested to study the feasibility of nuclear material assays using a surrogate material (lead) to avoid radiation effects from nuclear materials...
December 28, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29289812/validating-production-of-pet-radionuclides-in-solid-and-liquid-targets-comparing-geant4-predictions-with-fluka-and-measurements
#6
T Amin, A Infantino, R Barlow, C Hoehr
The Monte Carlo toolkit Geant4 is used to simulate the production of a number of positron emitting radionuclides: 13N, 18F, 44Sc, 52Mn, 55Co 61Cu, 68Ga, 86Y, 89Zr and 94Tc, which have been produced using a 13MeV medical cyclotron. The results are compared to previous simulations with the Monte Carlo code FLUKA and experimental measurements. The comparison shows variable degrees of agreement for different isotopes. The mean absolute deviation of Monte Carlo results from experiments was 1.4±1.6 for FLUKA and 0...
December 21, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29288909/on-the-feasibility-of-determining-the-230th-activity-in-minerals-without-the-addition-of-a-th-radiotracer
#7
Mohammad Hosseinpour Khanmiri, Roman V Bogdanov
The necessity of measuring the radioactivity of the 230Тh nuclide arises when attempting to solve a number of geochemical or geochronological problems based on the effects of radioactive disequilibrium in the 238U series. It is the authors' opinion that the use of the traditional α- and β-emitters of thorium as a radiotracer in order to determine the activity of 230Тh leads to various inconveniences and difficulties of a technical nature. The authors recommend using the 234Тh isotope contained in the study sample as the simplest and most natural way of measuring the chemical yield of the targeted nuclide (230Тh)...
December 20, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29294418/study-of-radon-and-thoron-exhalation-from-soil-samples-of-different-grain-sizes
#8
N Chitra, B Danalakshmi, D Supriya, I Vijayalakshmi, S Bala Sundar, K Sivasubramanian, R Baskaran, M T Jose
The exhalation of radon (222Rn) and thoron (220Rn) from a porous matrix depends on the emanation of them from the grains by the recoil effect. The emanation factor is a quantitative estimate of the emanation phenomenon. The present study is to investigate the effect of grain size of the soil matrix on the emanation factor. Soil samples from three different locations were fractionated into different grain size categories ranging from <0.1 to 2mm. The emanation factors of each of the grain size range were estimated by measuring the mass exhalation rates of radon and thoron and the activity concentrations of 226Ra and 232Th...
December 19, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29276964/disentangling-the-16o-cross-section-using-light-water-and-heavy-water-benchmark-assemblies
#9
Martin Schulc, Michal Košťál, Davit Harutyunyan, Evžen Novák
Fast neutron leakage spectra from the light and heavy water sphere of 30cm in diameter with neutron source in its centre were measured by a stilbene scintillation detector in the region of 1-10MeV in the distance of 85cm from the spheres surface. We use the light and heavy water to eliminate the effect of hydrogen. 252Cf with the approximate emission rate of 5.5E8 n/s was used as a neutron source for all measurements involved and was placed in the centres of the spheres. The measured neutron spectra are compared with MCNP transport code calculations in ENDF/B-VII...
December 19, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29276965/development-of-an-externally-controllable-sealed-isotope-generator
#10
Toru Sasaki, Katsumi Aoki, Ryosuke Yamashita, Kensuke Hori, Taiga Kato, Misaki Saito, Kazuhiro Niisawa, Kotaro Nagatsu, Tadashi Nozaki
An externally controllable sealed isotope generator has been proposed for radiation education activities. Column (68Ge-68Ga and 137Cs-137mBa) and solvent extraction (68Ge-68Ga)-based isotope generators were applied as radioactive sources. These generators showed high milking efficiencies and low breakthrough after repeated uses, and are expected to promote the use of isotope generators without radioactive contamination or the emission of radioactive waste. This isotope generator provides a new concept for sealed radioisotope sources...
December 18, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29274522/characterization-and-application-of-in-vacuum-pixe-ebs-system-for-the-direct-elemental-analysis-of-thick-solid-biological-samples
#11
M S Rihawy, D Halloum
Utilization of combined particle-induced X-ray emission (PIXE) and elastic backscattering (EBS) spectrometry for the direct elemental analysis of thick solid biological samples was thoroughly discussed. Powdered samples pressed as pellets were directly analyzed. Combination of applying low ion beam currents, random scanning of the sample across the beam during data acquisition, and using special sample holder enabled effective minimization of local ion beam heating. This subsequently inhibited potential element loss during ion beam irradiation...
December 18, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29272822/in-vitro-evaluation-of-the-monoclonal-antibody-64cu-igg-m75-against-human-carbonic-anhydrase-ix-and-its-in-vivo-imaging
#12
Adam Čepa, Jan Ráliš, Vlastimil Král, Monika Paurová, Jan Kučka, Jana Humajová, Milan Lázníček, Ondřej Lebeda
Specific oncology diagnostics requires new types of the selective radiopharmaceuticals, particularly those suitable for the molecular PET imaging. The aim of this work is to present a new, specific PET-immunodiagnostic radiopharmaceutical based on the monoclonal antibody IgG M75 targeting human carbonic anhydrase IX labelled with 64Cu (T½ = 12.70h) and its in vitro and in vivo evaluation. The antibody IgG M75 was conjugated with a non-commercial copper-specific chelator "phosphinate" and then labelled with the positron emitter 64Cu...
December 16, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29275039/investigation-of-n-p-n-2n-reaction-cross-sections-for-sn-isotopes-for-fusion-reactor-applications
#13
Siddharth Parashari, S Mukherjee, Vibha Vansola, Rajnikant Makwana, N L Singh, Bhawna Pandey
The compound Nb3Sn possess superconductivity at suitable temperatures, therefore, it is best suited to be used in the toroidal coils of superconducting magnets which holds the fusion plasma and confine it inside the reactor core. The neutron induced reaction cross-sections are required from threshold to 20MeV for different isotopes of Tin (Sn). Since limited data is available for the reactions with the Sn isotopes. Therefore, we have optimized the (n, p) and (n, 2n) reaction cross-sections for all possible Sn isotopes from threshold to 20MeV with modified input parameters in the nuclear reaction modular codes EMPIRE-3...
December 15, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29289813/characterization-of-a-neutron-calibration-field-with-241am-be-source-using-bonner-sphere-spectrometer
#14
Thiem Ngoc Le, Hoai-Nam Tran, Quynh Ngoc Nguyen, Giap Van Trinh, Khai Tuan Nguyen
This paper presents the characterization of a neutron calibration field of a 241Am-Be source using Bonner sphere spectrometer. The characterization of the neutron field in terms of neutron ambient dose equivalent, H*(10), rates and neutron flux spectra was performed using generalized-fit and semi-empirical fit methods together with an unfolding technique using the MAXED code. Monte Carlo simulations using MCNP5 have also been conducted to qualify the characterization process. Comparison of the neutron fluxes and the H*(10) rates obtained from the various methods shows that the components of the neutron fluxes are in good agreement with a discrepancy of about 2% while the discrepancy of the direct H*(10) rates is within 3%...
December 14, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29275040/radiosynthesis-and-modified-quality-control-of-o-2-18f-fluoroethyl-l-tyrosine-18f-fet-for-brain-tumor-imaging
#15
Ibrahim Saber Siddiq, Shoukar Tawfik Atwa, Sayed Ahmed Shama, Magdy Hafez Eltaoudy, Walid Mohamed Omar
O-(2-[18F]fluoroethyl)-L-tyrosine ([18F]FET) is the most promising radio-labeled amino acid tracer for brain tumor imaging due to the limitation of 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) and L-methyl-[11C]methionine (11C-MET). However, it has some limitations in radiosynthesis and related quality control that make it less frequently used in many PET centers, in this study, we report a new modification of [18F]FET production using a commercially available fully automated GRP SCINTOMICS module overcoming some of the existing limitations along with a suggestion of a simplified quality control procedure with special focus placed on enantiomeric and radiochemical purity...
December 13, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29274523/calculation-of-the-detection-limits-for-radionuclides-identified-in-gamma-ray-spectra-based-on-post-processing-peak-analysis-results
#16
M Korun, B Vodenik, B Zorko
A new method for calculating the detection limits of gamma-ray spectrometry measurements is presented. The method is applicable for gamma-ray emitters, irrespective of the influences of the peaked background, the origin of the background and the overlap with other peaks. It offers the opportunity for multi-gamma-ray emitters to calculate the common detection limit, corresponding to more peaks. The detection limit is calculated by approximating the dependence of the uncertainty in the indication on its value with a second-order polynomial...
December 11, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29289428/preface
#17
EDITORIAL
Pablo Arenillas, Dirk Arnold, Uwe Wätjen
No abstract text is available yet for this article.
December 10, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29272820/production-of-curie-quantities-of-68ga-with-a-medical-cyclotron-via-the-68zn-p-n-68ga-reaction
#18
Mai Lin, Gregory J Waligorski, Carlos González Lepera
PET imaging with 68Ga-labeled tracers has seen a dramatic increase over the past five years primarily due to the increased accessibility of 68Ge/68Ga generators, the availability of tracers with superb targeting properties for labeling, straightforward labeling procedures and the approval of these tracers by regulatory entities. Available 68Ge/68Ga generators nominally deliver up to 1.85 GBq (50mCi) when fresh limiting production and distribution of 68Ga-labeled tracers to a few daily doses per generator. The focus of this study was to provide a simple and efficient method for 68Ga production in clinically relevant quantities using a low energy medical cyclotron with a solid target...
December 9, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29247862/the-application-of-u-isotopes-to-assess-weathering-in-contrasted-soil-water-regime-in-brazil
#19
Vania Rosolen, Guilherme Taitson Bueno, Daniel Marcos Bonotto
This paper presents the use of U-series radionuclides 238U and 234U to evaluate the biogeochemical disequilibrium in soil cover under a contrasted soil-water regime. The approach was applied in three profiles located in distinct topographical positions, from upslope ferralitic to downslope hydromorphic domain. The U fractionation data was obtained in the samples representing the saprolite and the superficial and subsuperficial soil horizons. The results showed a significant and positive correlation between U and the Total Organic Carbon (TOC)...
December 9, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29253756/non-dependence-of-nuclear-decay-rates-of-123i-and-99mtc-on-earth-sun-distance
#20
Joseph A Borrello, Alan Wuosmaa, Mark Watts
Recently published studies have suggested an annual fluctuation of the decay rate of several radionuclides, in particular 32Si and 226Ra. Variation of solar neutrino flux caused by variation of Earth-Sun distance has been proposed as the mechanism of this fluctuation. In this study we prospectively look at two radionuclides which have not previously been studied for annual variation, 123I and 99mTc. Half-lives of samples of these radionuclides were measured approximately weekly and semiweekly respectively over a period of 2 years...
December 8, 2017: Applied Radiation and Isotopes
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