(n,p) reactions contribution in spherical proton recoil proportional counter responses

Proton recoil proportional counters are used in several metrological institutes as reference neutron spectrometers within the energy range from a few tenth of keV up to a few MeV. When such counters are used to determine the low energy range of neutron fields with energies above 5 MeV, protons generated by (n,p) reactions within the stainless steel counter walls will add their contribution to the proton recoil process. In this work, this contribution has been estimated in the calculated response of the counter, using MCNPX Monte Carlo code. The validation of the calculated response has been performed at several AMANDE mono-energetic neutron fields. © 2006 IOP Publishing Ltd and SISSA

Individual neutron monitoring in workplaces with mixed neutron/photon radiation

EVIDOS (‘evaluation of individual dosimetry in mixed neutron and photon radiation fields') is an European Commission (EC)-sponsored project that aims at a significant improvement of radiation protection dosimetry in mixed neutron/photon fields via spectrometric and dosimetric investigations in representative workplaces of the nuclear industry. In particular, new spectrometry methods are developed that provide the energy and direction distribution of the neutron fluence from which the reference dosimetric quantities are derived and compared to the readings of dosemeters. The final results of the project will be a comprehensive set of spectrometric and dosimetric data for the workplaces and an analysis of the performance of dosemeters, including novel electronic dosemeters. This paper gives an overview of the project and focuses on the results from measurements performed in calibration fields with broad energy distributions (simulated workplace fields) and on the first results from workplaces in the nuclear industry, inside a boiling water reactor and around a spent fuel transport cas

Structural and Luminescence Properties of Silica-Based Hybrids Containing New Silylated-Diketonato Europium(III) Complex

A new betadiketonate ligand displaying a trimethoxysilyl group as grafting function and a diketone moiety as complexing site (TTA-Si = 4,4,4-trifluoro-2-(3-trimethoxysilyl)propyl)-1-3-butanedione (C4H3S)COCH[(CH2)3Si(OCH3)3]COCF3) and its highly luminescent europium(III) complex [Eu(TTA-Si)3] have been synthesized and fully characterized. Luminescent silica-based hybrids have been prepared as well with this new complex grafted on the surface of dense silica nanoparticles (28 (+/-3 nm) or on mesoporous silica particles. The covalent bonding of Eu(TTA-Si)3 inside the core of uniform silica nanoparticles (40 (+/- 5 nm) was also achieved. Luminescence properties are discussed in relation to the europium chemical environment involved in each of the three hybrids. The general methodology proposed allowed high grafting ratios and overcame chelate release and tendency to agglomeration, and it could be applied to any silica matrix (in the core or at the surface, nanosized or not, dense or mesoporous) and therefore numerous applications such as luminescent markers and luminophors could be foreseen

The Hubble PanCET program: The near-ultraviolet transmission spectrum of WASP-79b

We present Hubble Space Telescope (HST) transit observations of the Hot-Jupiter WASP-79b acquired with the Space Telescope Imaging Spectrograph (STIS) in the near ultraviolet (NUV). Two transit observations, part of the PanCET program, are used to obtain the transmission spectra of the planet between 2280 and 3070{\AA}. We correct for systematic effects in the raw data using the jitter engineering parameters and polynomial modelling to fit the white light curves of the two transits. We observe an increase in the planet-to-star radius ratio at short wavelengths, but no spectrally resolved absorption lines. The difference between the radius ratios at 2400 and 3000{\AA} reaches $0.0191\pm0.0042$ ($\sim$4.5$-\sigma$). Although the NUV transmission spectrum does not show evidence of hydrodynamical escape, the strong atmospheric features are likely due to species at very high altitudes. We performed a 1D simulation of the temperature and composition of WASP-79b using Exo-REM. The temperature pressure profile crosses condensation curves of radiatively active clouds, particularly MnS, Mg$_2$SiO$_4$, Fe, and Al$_2$O$_3$. Still, none of these species produces the level of observed absorption at short wavelengths and can explain the observed increase in the planet's radius. WASP-79b's transit depth reaches 23 scale height, making it one of the largest spectral features observed in an exoplanet at this temperature ($\sim$1700 K). The comparison of WASP-79b's transmission spectrum with three warmer hot Jupiters shows a similar level of absorption to WASP-178b and WASP-121b between 0.2 and 0.3$\mu$m, while HAT-P-41b's spectrum is flat. The features could be explained by SiO absorption.Comment: Accepted for publication January 31, 2023 in the Journal Astronomy & Astrophysic

Review of neutron calibration facilities and monitoring techniques: New needs for emerging fields

Neutron calibration facilities and monitoring techniques have been developed since the middle of the 20th century to support research and nuclear power energy development. The technical areas needing reference neutron fields and related instruments were mainly cross section measurements, radiation protection, dosimetry and fission reactors, with energy ranging from a few millielectronvolts to about 20 MeV. The reference neutron fields and calibration techniques developed for these purposes will be presented in this paper. However, in recent years, emerging fields have brought new needs for calibration facilities and monitoring techniques. These new challenges for neutron metrology will be exposed with their technical difficulties. © The Author 2013

Les installations de l’IRSN dédiées à la métrologie des neutrons

La responsabilité des références françaises pour la fluence et les grandeurs dosimétriques neutroniques est du ressort du laboratoire de métrologie et de dosimétrie des neutrons de l’Institut de radioprotection et de sûreté nucléaire (IRSN). C’est dans ce cadre, que l’institut développe et exploite, à Cadarache, des installations produisant des champs neutroniques de référence pour des utilisations diverses. Certaines (sources radioactives émettrice neutrons respectant la norme ISO 8529-1) sont utilisées pour effectuer des étalonnages de routine de dispositifs de mesure. D’autres installations produisent des champs neutroniques « réalistes » simulant les champs rencontrés sur les postes de travail en modérant les champs neutroniques générés à partir de sources radioactives ou d’accélérateurs. Enfin, l’installation AMANDE dont l’inauguration a eu lieu en mai 2005 produit des champs de neutrons monoénergétiques d’énergie comprise entre 2 keV et 20 MeV à partir de l’interaction de particules chargées accélérées jusqu’à 4 MeV sur différentes cibles. Avec l’arrivée de cette dernière installation, l’IRSN offre un plateau technique très complet pour la production de tous les types de champ neutronique recommandés par les normes internationales pour l’étalonnage des instruments de détection des neutrons