55 research outputs found

    ToyBox Malaysia Panduan Umum Guru

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    Konsep ToyBox Study diadaptasi daripada program ENERGY, program intervensi Cretan Health and Nutrition, manakala teks dan bahan diadaptasi daripada TigerKids. Bahan berkaitan Pinggan Sihat Malaysia digunapakai dengan izin daripada Bahagian Pemakanan, Kementerian Kesihatan Malaysia

    Production of Mass-Separated Erbium-169 Towards the First Preclinical in vitro Investigations

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    The ÎČ−-particle-emitting erbium-169 is a potential radionuclide toward therapy of metastasized cancer diseases. It can be produced in nuclear research reactors, irradiating isotopically-enriched 168Er2O3. This path, however, is not suitable for receptor-targeted radionuclide therapy, where high specific molar activities are required. In this study, an electromagnetic isotope separation technique was applied after neutron irradiation to boost the specific activity by separating 169Er from 168Er targets. The separation efficiency increased up to 0.5% using resonant laser ionization. A subsequent chemical purification process was developed as well as activity standardization of the radionuclidically pure 169Er. The quality of the 169Er product permitted radiolabeling and pre-clinical studies. A preliminary in vitro experiment was accomplished, using a 169Er-PSMA-617, to show the potential of 169Er to reduce tumor cell viability. © Copyright © 2021 Talip, Borgna, MĂŒller, Ulrich, Duchemin, Ramos, Stora, Köster, Nedjadi, Gadelshin, Fedosseev, Juget, Bailat, Fankhauser, Wilkins, Lambert, Marsh, Fedorov, Chevallay, Fernier, Schibli and van der Meulen.The authors thank CERN ISOLDE and RILIS teams for the laser operation (Maxim D. Seliverstov, Katerina Chrysalidis), radiation protection and logistic teams of PSI (Tobias Schneider) and CERN (Alexandre Dorsival, Matthieu Deschamps and Elodie Aubert, Philippe Bertreix, Nicolas Riggaz, Nabil Menaa, Aurore Boscher, Jeremie Comte, Benjamin Juif); the LARISSA workgroup of Mainz University for the laser preparation and erbium laser ionization scheme development (Prof. Dr. Klaus Wendt and Dr. Dominik Studer). The authors are grateful to Fan Sozzi-Guo, Muhamet Djelili, Alexander V?gele and Walter Hirzel (PSI) and Bernard Cr?pieux, Giacomo Lunghi, Francesco Riccardi, Miranda Van Stenis, Thomas Schneider (CERN) for technical support. Funding. ZT and NM received funding from the Swiss National Science Foundation (SNF Grant Number: 200021_188495). CM obtained funding for this project from the Swiss Cancer Research (KFS-4678-02-2019-R). FB received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sk?odowska-Curie Grant Agreement No 701647

    Measurement of the 77Se(n,Îł)^{77}Se ( n , Îł ) cross section up to 200 keV at the n_TOF facility at CERN

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    The 77Se(n,γ)^{77}Se ( n , γ ) reaction is of importance for 77Se^{77}Se abundance during the slow neutron capture process in massive stars. We have performed a new measurement of the 77Se^{77}Se radiative neutron capture cross section at the Neutron Time-of-Flight facility at CERN. Resonance capture kernels were derived up to 51 keV and cross sections up to 200 keV. Maxwellian-averaged cross sections were calculated for stellar temperatures between kT=5 keVkT=5 \space keV and kT=100 keVkT=100\space keV, with uncertainties between 4.2% and 5.7%. Our results lead to substantial decreases of 14% and 19% in 77Se^{77}Se abundances produced through the slow neutron capture process in selected stellar models of 15M⊙15M⊙ and 2M⊙2M⊙, respectively, compared to using previous recommendation of the cross section

    Measurement of the 14^{14}N(n,p)14^{14}C cross section at the CERN n_TOF facility from sub-thermal energy to 800 keV

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    Background: The 14^{14}N(n,p)14^{14}C reaction is of interest in neutron capture therapy, where nitrogen-related dose is the main component due to low-energy neutrons, and in astrophysics, where 14N acts as a neutron poison in the s-process. Several discrepancies remain between the existing data obtained in partial energy ranges: thermal energy, keV region and resonance region. Purpose: Measuring the 14N(n,p)14C cross section from thermal to the resonance region in a single measurement for the first time, including characterization of the first resonances, and providing calculations of Maxwellian averaged cross sections (MACS). Method: Time-of-flight technique. Experimental Area 2 (EAR-2) of the neutron time-of-flight (n_TOF) facility at CERN. 10^{10}B(n,α{\alpha})7^7Li and 235^{235}U(n,f) reactions as references. Two detection systems running simultaneously, one on-beam and another off-beam. Description of the resonances with the R-matrix code sammy. Results: The cross section has been measured from sub-thermal energy to 800 keV resolving the two first resonances (at 492.7 and 644 keV). A thermal cross-section (1.809±\pm0.045 b) lower than the two most recent measurements by slightly more than one standard deviation, but in line with the ENDF/B-VIII.0 and JEFF-3.3 evaluations has been obtained. A 1/v energy dependence of the cross section has been confirmed up to tens of keV neutron energy. The low energy tail of the first resonance at 492.7 keV is lower than suggested by evaluated values, while the overall resonance strength agrees with evaluations. Conclusions: Our measurement has allowed to determine the 14^{14}N(n,p) cross-section over a wide energy range for the first time. We have obtained cross-sections with high accuracy (2.5 %) from sub-thermal energy to 800 keV and used these data to calculate the MACS for kT = 5 to kT = 100 keV.Comment: 18 pages, 15 figures, 4 table

    Neutron capture cross section measurements of Am-241 at the n_TOF facility

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    Neutron capture on Am-241 plays an important role in the nuclear energy production and also provides valuable information for the improvement of nuclear models and the statistical interpretation of the nuclear properties. A new experiment to measure the Am-241(n,gamma) cross section in the thermal region and the first few resonances below 10 eV has been carried out at EAR2 of the n_TOF facility at CERN. Three neutron-insensitive C6D6 detectors have been used to measure the neutron-capture gamma cascade as a function of the neutron time of flight, and then deduce the neutron capture yield. Preliminary results will be presented and compared with previously obtained results at the same facility in EAR1. In EAR1 the gamma-ray background at thermal energies was about 90% of the signal while in EAR2 is up to a 25 factor much more favorable signal to noise ratio. We also extended the low energy limit down to subthermal energies. This measurement will allow a comparison with neutron capture measurements conducted at reactors and using a different experimental technique

    Measurement of the 244^{244}Cm and 246^{246}Cm Neutron-Induced Cross Sections at the n_TOF Facility

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    The neutron capture reactions of the 244^{244}Cm and 246^{246}Cm isotopes open the path for the formation of heavier Cm isotopes and of heavier elements such as Bk and Cf in a nuclear reactor. In addition, both isotopes belong to the minor actinides with a large contribution to the decay heat and to the neutron emission in irradiated fuels proposed for the transmutation of nuclear waste and fast critical reactors. The available experimental data for both isotopes are very scarce. We measured the neutron capture cross section with isotopically enriched samples of 244^{244}Cm and 246^{246}Cm provided by JAEA. The measurement covers the range from 1 eV to 250 eV in the n_TOF Experimental Area 2 (EAR-2). In addition, a normalization measurement with the 244^{244}Cm sample was performed at Experimental Area 1 (EAR-1) with the Total Absorption Calorimeter (TAC)

    Measurement of the radiative capture cross section of the s-process branching points 204Tl and 171Tm at the n-TOF facility (CERN)

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    The neutron capture cross section of some unstable nuclei is especially relevant for s-process nucleosynthesis studies. This magnitude is crucial to determine the local abundance pattern, which can yield valuable information of the s-process stellar environment. In this work we describe the neutron capture (n,Îł) measurement on two of these nuclei of interest, 204Tl and 171Tm, from target production to the final measurement, performed successfully at the n-TOF facility at CERN in 2014 and 2015. Preliminary results on the ongoing experimental data analysis will also be shown. These results include the first ever experimental observation of capture resonances for these two nuclei

    JOURNAL OF ENVIRONMENTAL RADIOACTIVITY

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    The use of expanded perlite for the adsorption of thorium from aqueous solution by batch technique is presented. The effects of particle size, pH of the solution, initial thorium concentration, shaking time, V/m ratio and temperature were determined. It was found that the adsorption capacity increases by the increase in the pH of the suspensions. The rate of thorium adsorption on expanded perlite was observed to be fast in the first hour of the reaction time. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models and the adsorption experiments conducted at 30 +/- 1 degrees C showed that the adsorption isotherms correlated well with the Langmuir model. From the adsorption data, thermodynamic parameters such as Delta G(0), Delta H-0 and Delta S-0 were calculated as a function of temperature. (C) 2008 Elsevier Ltd. All rights reserved

    The dissolution of helium in La-doped UO2 as a surrogate of hypo-stoichiometric UO2

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    In this work, the dissolution of helium in La-doped UO2 samples was studied by helium infusion in an autoclave followed by thermal desorption (laser heating) coupled to mass spectrometer systems for the determination of helium release rate and the total helium quantity. Lanthanum was chosen as a dopant in UO2 to study the effect of hypo-stoichiometry on helium solubility together with the impurity effect. Comparison of the dissolved He quantity from the samples with different La content showed that the dissolved He quantity slightly increases with increasing oxygen vacancy concentration in the samples
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