Animé par Eamonn Weitz
jeudi 3 juin 2021 à 14:00
Several radionuclides of Terbium family are intended to be used in nuclear medicine: 149Tb can be used for alpha therapy, 152Tb as a positron emitter can be used for positron emission tomography (PET), 155Tb can be used for single photon emission tomography (SPECT) and for auger therapy and finally 161Tb can be an alternative to 177Lu for β-therapy. At the moment, the first three radionuclides are obtained using spallation reactions followed by mass separation. This technique requires high-energy beam and mass separation devices that are not so frequent and are expensive. A way to overcome these drawback is to use enriched Gd targets with low energy accelerators through the following reactions: 154Gd(p, 6n)149Tb, 152Gd(p, n)152Tb, 155Gd(p, n)155Tb and 160Gd(n,γ)161Gd→161Tb. Objectives of this study is to optimize these productions by working on the manufacture of enriched Gd targets. Due to the properties of gadolinium, electroplating of Gd metal can not be achieved in aqueous solution. To overcome this issue, two different methods are developed in this work for two foreseen applications. Co-electrodeposition method is used to fabricate thin targets for cross section measurements. In this approach, Gd2O3 particles are trapped into a nickel matrix. Oxyde is the form in which enriched gadolinium can be purchased. After varying different electroplating parameters (the potential, the pH, the stirring speed, the nickel concentration and the duration of the deposition), deposits with a thickness of 20 μm, which contains 5% of Gd, were obtained. Optimization is still on-going to increase the amount of Gd in the deposit. Pelletizing method is used for mass production of terbium isotopes. One millimeter thick targets have been obtained using Gd2O3. Thermal constants have been extracted up to 400°C that will be used for thermal calculations of the irradiation process.
More details of the two methods will be presented in the presentation.
Core-collapsed supernovae (CCSN) are gigantic and luminous explosions which occur when a star comes to death. During the last decades, many of them have been observed and studied with telescopes, through the detection of the electromagnetic radiations. Still, many questions remain unanswered about the mechanism which leads to such a violent explosion. The detection of the neutrinos emitted during a supernova would provide a new way to answer these questions. The Jiangmen Underground Neutrino Observatory (JUNO) is a next generation neutrino detector under construction in China. Thanks to a 20- kton liquid scintillator detection volume, JUNO will detect a burst of ∼ 104 neutrinos from the next galactic CCSN. Such high statistics will allow for the constraint of the supernovae explosion models. This presentation will be focused on the detection of CCSN neutrino with the 3" photomultiplier (PMT) system of the JUNO detector.