Neutron activation analysis using 14 MeV neutron generator

Hlavním cílem práce je vyšetřit neutronový tok neutronového generátoru MP 320 od firmy Thermo Fisher Scientific, zkonstruovat transportní systém pro přenos vzorků v laboratoři pro neutronovou aktivační analýzu a gama spektrometrii v Ostravě a provést první testy detekce krátcežijících radionuklidů pomocí 14 MeV neutronů. Určení neutronového toku bylo provedeno pomocí metody Texaské konvence. Úspěšně zkonstruovaný pneumatický transportní systém byl použit během neutronové aktivace vzorků, v kterých byly aktivovány krátcežijící radionuklidy a přeneseny za pomocí transportního systému do scintilačního detektoru. Hmotnosti vybraných izotopů byly analyzovány z výsledků z měření neutronového toku a z dat získaných detektorem.The purpose of this thesis is to examine the neutron flux of Thermo Fisher Scientific MP 320 14 MeV Neutron generator, construct pneumatic transport system for samples in the Laboratory for Neutron Activation Analysis and Gamma Spectrometry in Ostrava and present first detection of short-lived radionuclides using 14 MeV neutrons. The determination of neutron flux was performed by Texas convention technique. Successfully constructed pneumatic transport system was used during neutron activation of samples in which short-lived radionuclides were formed, to obtain gamma spectra of activated samples using scintillation spectrometer. Masses of selected isotopes in sample contents were analyzed by means of the results from neutron flux measurement and gamma spectrometry data of activated samples.717 - Katedra fyzikyvýborn

Possibilities of Use of COMSOL Multiphysics in Biomedical Engineering

Import 04/11/2015Tato diplomová práce se zaměřuje na možnosti modelování biologických systémů prostřednictvím programu COMSOL Multiphysics a prostředí MATLAB. V práci jsou představeny možnosti modelování biomedicínských systémů v programu COMSOL ve formě případových studií zabývajících se konkrétními vytvořenými modely. Dále práce poskytuje základní informace jak pracovat s nástrojem LiveLink for MATLAB, který umožňuje propojení mezi COMSOLem a MATLABem. Možnosti tohoto propojení jsou předvedeny na několika vytvořených modelech. Vytvořené modely jsou následně analyzovány jak z hlediska přesnosti, tak časové náročnosti výpočtu.This thesis focuses on possibilities of modeling biological systems using COMSOL Multiphysics and MATLAB. In the work there are presented already created biomedical models in COMSOL Multiphysics. The work then provides information of how to use the tool called LiveLink for MATLAB which connects COMSOL and MATLAB to communicate. Possibilities of this connection are shown in several models. The work presents analysis of proposed solution in the way of accuracy and performance.450 - Katedra kybernetiky a biomedicínského inženýrstvívelmi dobř

Radiocaesium contamination of mushrooms at high- and low-level Chernobyl exposure sites and its consequences for public health

We compare the specific activities of Cs-137 and K-40 in stipes and caps of three different common mushroom species (Xerocomus badius, Russula ochroleuca and Armillariella mellea) measured at the Czech Chernobyl hot spot in the Opava area (Silesia) and at a low-exposed site at the Beskydy mountains in 2011. The highest values of Cs-137 were found in caps of Xerocomus badius and Russula ochroleuca in the Opava area (11.8 and 8.77 kBq/kg, respectively). The source of Cs-137 was verified by the measurement of the Cs-134/Cs-137 ratio. Based on our results, we estimate an effective dose per year due to radiocaesium intake in the two investigated areas for Xerocomus badius, one of the most popular edible mushrooms in the Czech Republic. In 2011, the effective dose reached the maximum value of 0.102 mSv in the Opava area and 0.004 mSv at the low-exposed site at the Beskydy mountains. Therefore, it does not represent a significant risk for public health.Web of Science1112art. no. 137

Radiocaesium Contamination of Mushrooms at High- and Low-Level Chernobyl Exposure Sites and Its Consequences for Public Health

We compare the specific activities of 137Cs and 40K in stipes and caps of three different common mushroom species (Xerocomus badius, Russula ochroleuca and Armillariella mellea) measured at the Czech Chernobyl hot spot in the Opava area (Silesia) and at a low-exposed site at the Beskydy mountains in 2011. The highest values of 137Cs were found in caps of Xerocomus badius and Russula ochroleuca in the Opava area (11.8 and 8.77 kBq/kg, respectively). The source of 137Cs was verified by the measurement of the 134Cs/137Cs ratio. Based on our results, we estimate an effective dose per year due to radiocaesium intake in the two investigated areas for Xerocomus badius, one of the most popular edible mushrooms in the Czech Republic. In 2011, the effective dose reached the maximum value of 0.102 mSv in the Opava area and 0.004 mSv at the low-exposed site at the Beskydy mountains. Therefore, it does not represent a significant risk for public health

Modified Texas Convention Method for fast neutron flux measurements

The Texas Convention Method (TCM) is a standard method used for relatively fast calibration and check of the 14-MeV neutron flux from DT neutron generators in laboratory and field applications. It is shown that the homogeneous gamma source approximation used in the TCM overestimates the detection efficiency. To increase the accuracy of the method, a careful examination of sources of uncertainties is necessary. To be able to measure neutron fluxes lower than approximately 10(4) neutrons/cm(2)/s, a proper modification of the copper foil dimensions is beneficial. The article addresses both issues.Web of Science67138838

Measurement of dosimetrical cross sections with 14.05 MeV neutrons from compact neutron generator

This paper deals with the measurement of the differential dosimetry cross sections using a small compact D-T neutron generator with 14.05 ± 0.08 MeV neutron emission (1 × 108 n/s into 4π). In spite of low neutron flux, it is possible to get measurable gamma-ray activities by irradiating a larger amount of target material placed in close geometry. The experimentally determined cross sections are in good agreement with the cross sections in the IRDFF-II dosimetry library. The comparison with other nuclear data libraries was performed as well. It is worth noting that the mean standard deviation in IRDFF-II library is about 4 %, while in the case of other data libraries they are from 5.5 % to 7.5 %. This result can be understood as a validation of IRDFF-II using 14.05 MeV neutrons and also a confirmation of the applicability of small compact generators in the measurement of activation cross sections.Web of Science191art. no. 10990