P. Vermaercke

Bio: P. Vermaercke is an academic researcher. The author has contributed to research in topics: Neutron activation analysis & Neutron. The author has an hindex of 8, co-authored 32 publications receiving 255 citations.

Characterisation of synthetic multi-element standards (SMELS) used for the validation of k0-NAA

Abstract: A synthetic multi-element standard material (SMELS) has been prepared for the validation of k0-standardised Neutron-Activation Analysis (k0-NAA). SMELS consists of three different materials in a polymer matrix spiked with different elements, so that each material can be used for an elemental analysis monitoring respectively short lived (SMELS Type I), medium (Type II) and long-lived (Type III) radionuclides. In previous studies the homogeneity and radiation stability of the material have been proven. The final step, discussed in this article, is the characterisation of the material in terms of the elemental content by neutron-activation analysis techniques.

Experimental determination of k0, Q0, \bar{E}_{r} factors and neutron cross-sections for 41 isotopes of interest in Neutron Activation Analysis

Abstract: The k 0 -literature has been reviewed every decade but some of its nuclear data is still more than 30 years old. Sometimes Q 0 values were adopted from the nuclear data at that time or were experimentally determined by only 1 laboratory. Other isotopes were listed with accurate pairs of (k 0 , Q 0 ) values but were also quoted as candidates for redetermination for different reasons (i.e. imprecise cadmium transmission factors, half-lives). In this work we aim at the experimental re-determination of k 0 and Q 0 values for 41 isotopes of analytical interest while introducing a methodology for simultaneous $$ \bar{E}_{r} $$ and Q 0 determination employing N irradiation channels. In order to satisfy the metrological level required, up to 12 repeats per standard were irradiated in up to 4 irradiation channels of the Belgian Reactor 1 (BR1, SCK∙CEN) having a wide spread in neutron characteristics. Our relative percentile differences to the literature values were usually ≤10 % for Q 0 factors, ≥25 % for $$ \bar{E}_{r} $$ values and ≤4 % for k 0 values. Our precision and accuracy are discussed thoroughly.

The 2012 recommended k 0 database

Abstract: Many overview papers have been published with recommended nuclear data for use in the k 0 method of NAA and made available in scientific journals or in the form of a downloadable database. In September 2009, the k 0-International Scientific Committee formed the k 0-Nuclear Data Committee (k 0-NDC) whose first task was to collect all these data at a single place to facilitate updating and to correct any evident errors. This task of the k 0-NDC was successfully completed in March 2012 when the 2012 recommended k 0 database was published in the form of an Excel file.

Experimental determination of k0, Q0 factors, effective resonance energies and neutron cross-sections for 37 isotopes of interest in NAA

Abstract: The recommended k 0 nuclear data from 2003 has been re-investigated by some authors during the last decade, motivated by some discrepancies that were systematically observed during the analysis of reference materials. Their significant findings have not been included (yet) on a newer compilation, as it is difficult to draw conclusions on the accuracy of k 0 and Q 0 factors when the statistical population of independent experimental values are quite scarce. In some cases, a strong correlation to the adopted Q 0 factor means that a direct comparison between the results of different authors is not possible if the data required for a proper renormalization was not provided. At the SCK-CEN and UGent (Belgium) we would like to continue with the experimental k 0 determination exercises performed during the last years and to supply to the k 0-community with the nuclear data of 37 additional target isotopes, for a total of 77 isotopes investigated since 2012. The isotopes were investigated on up to 4 channels of the BR1 reactor at the SCK-CEN, obtaining values with <2.6 % uncertainty. Our results are discussed and compared to the literature elsewhere.

Study of neutron irradiation-induced colors in Brazilian topaz

Abstract: In this work, preliminary results of the investigation of the coloring mechanisms in topaz from different regions of Brazil, irradiated by the TRIGA MARK I IPR-R1 and BR1 nuclear reactors of the CDTN/CNEN (Brazil) and SCK.CEN(Belgium), respectively, are presented . The samples were analyzed by the k0-NAA method for impurities and total activity. The color and color centers were investigated by optical absorption and electron paramagnetic resonance (EPR) spectroscopy. The total integrated flux dependence of the induced blue colors and color centers is discussed.

Non-cancer, cancer, and dermal sensitization risk assessment of heavy metals in cosmetics.

Abstract: The heavy metal content of cosmetics may be a cause for concern in that exposure to these metals is associated with adverse consequences. Thus, the aim of this study was to assess consequences attr...

Recommended nuclear data for medical radioisotope production: diagnostic positron emitters

Abstract: An IAEA coordinated research project that began in 2012 and ended in 2016 was primarily dedicated to the compilation, evaluation and recommendation of cross-section data for the production of medical radionuclides. One significant part of this work focused on diagnostic positron emitters. These particular studies consist of 69 reactions for direct and indirect or generator production of 44Sc(44Ti), 52mMn(52Fe), 52gMn, 55Co, 61Cu, 62Cu(62Zn), 66Ga, 68Ga(68Ge), 72As(72Se), 73Se, 76Br, 82Rb(82Sr), 82mRb, 86Y, 89Zr, 90Nb, 94mTc, 110mIn(110Sn), 118Sb(118Te), 120I, 122I(122Xe), 128Cs(128Ba), and 140Pr(140Nd) medical radionuclides. The resulting reference cross-section data were obtained from Pade fits to selected and corrected experimental data, and integral thick target yields were subsequently deduced. Uncertainties in the fitted results were estimated via a Pade least-squares method with the addition of a 4% assessed systematic uncertainty. Experimental data were also compared with theoretical predictions available from the TENDL-2015 and TENDL-2017 libraries. All of the numerical reference cross-section data with their corresponding uncertainties and deduced integral thick target yields are available on-line at the IAEA-NDS medical portal www-nds.iaea.org/medicalportal and also at the IAEA-NDS web page www-nds.iaea.org/medical/positron_emitters.html .

Production, characterization and operation of $^{76}$Ge enriched BEGe detectors in GERDA

Abstract: The GERmanium Detector Array (Gerda) at the Gran Sasso Underground Laboratory (LNGS) searches for the neutrinoless double beta decay ( $$0 u \beta \beta $$ ) of $$^{76}$$ Ge. Germanium detectors made of material with an enriched $$^{76}$$ Ge fraction act simultaneously as sources and detectors for this decay. During Phase I of theexperiment mainly refurbished semi-coaxial Ge detectors from former experiments were used. For the upcoming Phase II, 30 new $$^{76}$$ Ge enriched detectors of broad energy germanium (BEGe)-type were produced. A subgroup of these detectors has already been deployed in Gerda during Phase I. The present paper reviews the complete production chain of these BEGe detectors including isotopic enrichment, purification, crystal growth and diode production. The efforts in optimizing the mass yield and in minimizing the exposure of the $$^{76}$$ Ge enriched germanium to cosmic radiation during processing are described. Furthermore, characterization measurements in vacuum cryostats of the first subgroup of seven BEGe detectors and their long-term behavior in liquid argon are discussed. The detector performance fulfills the requirements needed for the physics goals of Gerda Phase II.