153 research outputs found
Preparation and certification of 243Am spike reference material: IRMM-0243 : Certified reference material for the amount content of 243Am and n(241Am)7n(243Am) isotope amount ratio
This report describes the preparation and certification of IRMM-0243, a 243Am spike reference material. It is certified for the amount content of 243Am and the isotope amount ratios of n(241Am)/n(243Am) and n(242mAm)/n(243Am). Furthermore, the material is certified for the amount contents of 241Am and total Am, the mass fractions of 243Am, 241Am and total Am, the isotope amount and mass fractions (e.g. isotopic composition) and the molar mass of Am. The material was produced in compliance with ISO/IEC 17034:2016 and certified in accordance with ISO Guide 35:2006.
The material was prepared by dilution of an americium starting solution in nitric acid and dispensing of the solution into glass ampoules. In total 587 units were produced.
Between-unit homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2006.
The characterisation of the amount content of 243Am was performed by Isotope Dilution Mass Spectrometry (IDMS) using a 241Am spike, produced from highly enriched 241Pu material. The isotope amount ratios of n(241Am)/n(243Am) and n(242mAm)/n(243Am) were measured by Thermal Ionisation Mass Spectrometry (TIMS).
The certified values were verified by alpha particle spectrometry, alpha particle counting at a defined solid angle (DSA) and high-resolution gamma-ray spectrometry as independent verification methods.
The uncertainties of the certified values were estimated in compliance with the Guide to the Expression of Uncertainty in Measurement (GUM) [ ] and include uncertainties related to possible inhomogeneity, instability and characterisation.
The main purpose of this material is for use as a spike isotopic reference material for the quantification of americium by IDMS in unknown samples. A unit of IRMM-0243 consists of a glass ampoule with a screw cap containing about 3.5 mL nitric acid solution (c = 1 mol/L) with an
americium mass fraction of about 1.5 ÎŒg/g solution.
The material is a true solution; therefore there is no recommended minimum sample intake to be taken into account.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard
R&D progress on second-generation crystals for Laue lens applications
The concept of a gamma-ray telescope based on a Laue lens offers the
possibility to increase the sensitivity by more than an order of magnitude with
respect to existing instruments. Laue lenses have been developed by our
collaboration for several years : the main achievement of this R&D program was
the CLAIRE lens prototype. Since then, the endeavour has been oriented towards
the development of efficient diffracting elements (crystal slabs), the aim
being to step from a technological Laue lens to a scientifically exploitable
lens. The latest mission concept featuring a gamma-ray lens is the European
Gamma-Ray Imager (GRI) which intends to make use of the Laue lens to cover
energies from 200 keV to 1300 keV.
Investigations of two promising materials, low mosaicity copper and gradient
concentration silicon-germanium are presented in this paper. The measurements
have been performed during three runs on beamline ID15A of the European
Synchrotron Radiation Facility, and on the GAMS 4 instrument of the Institute
Laue-Langevin (both in Grenoble, France) using highly monochromatic beam of
energy close to 500 keV. Despite it was not perfectly homogeneous, the
presented copper crystal exhibits peak reflectivity of 25% in accordance with
theoretical predictions, and a mosaicity around 26 arcsec, the ideal range for
the realization of a Laue lens such as GRI. Silicon-germanium featuring a
constant gradient have been measured for the very first time at 500 keV. Two
samples showed a quite homogeneous reflectivity reaching 26%, which is far from
the 48% already observed in experimental crystals but a very encouraging
beginning. This results have been used to estimate the performance of the GRI
Laue lens design
Concept design of low frequency telescope for CMB B-mode polarization satellite LiteBIRD
LiteBIRD has been selected as JAXAâs strategic large mission in the 2020s, to observe the cosmic microwave background (CMB) B-mode polarization over the full sky at large angular scales. The challenges of LiteBIRD are the wide field-of-view (FoV) and broadband capabilities of millimeter-wave polarization measurements, which are derived from the system requirements. The possible paths of stray light increase with a wider FoV and the far sidelobe knowledge of -56 dB is a challenging optical requirement. A crossed-Dragone configuration was chosen for the low frequency telescope (LFT : 34â161 GHz), one of LiteBIRDâs onboard telescopes. It has a wide field-of-view (18° x 9°) with an aperture of 400 mm in diameter, corresponding to an angular resolution of about 30 arcminutes around 100 GHz. The focal ratio f/3.0 and the crossing angle of the optical axes of 90⊠are chosen after an extensive study of the stray light. The primary and secondary reflectors have rectangular shapes with serrations to reduce the diffraction pattern from the edges of the mirrors. The reflectors and structure are made of aluminum to proportionally contract from warm down to the operating temperature at 5 K. A 1/4 scaled model of the LFT has been developed to validate the wide field-of-view design and to demonstrate the reduced far sidelobes. A polarization modulation unit (PMU), realized with a half-wave plate (HWP) is placed in front of the aperture stop, the entrance pupil of this system. A large focal plane with approximately 1000 AlMn TES detectors and frequency multiplexing SQUID amplifiers is cooled to 100 mK. The lens and sinuous antennas have broadband capability. Performance specifications of the LFT and an outline of the proposed verification plan are presented
LiteBIRD satellite: JAXA's new strategic L-class mission for all-sky surveys of cosmic microwave background polarization
LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental physics. JAXA selected LiteBIRD in May 2019 as a strategic large-class (L-class) mission, with its expected launch in the late 2020s using JAXA's H3 rocket. LiteBIRD plans to map the cosmic microwave background (CMB) polarization over the full sky with unprecedented precision. Its main scientific objective is to carry out a definitive search for the signal from cosmic inflation, either making a discovery or ruling out well-motivated inflationary models. The measurements of LiteBIRD will also provide us with an insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. To this end, LiteBIRD will perform full-sky surveys for three years at the Sun-Earth Lagrangian point L2 for 15 frequency bands between 34 and 448 GHz with three telescopes, to achieve a total sensitivity of 2.16 ΌK-arcmin with a typical angular resolution of 0.5° at 100 GHz. We provide an overview of the LiteBIRD project, including scientific objectives, mission requirements, top-level system requirements, operation concept, and expected scientific outcomes
Overview of the medium and high frequency telescopes of the LiteBIRD space mission
LiteBIRD is a JAXA-led Strategic Large-Class mission designed to search for the existence of the primordial gravitational waves produced during the inflationary phase of the Universe, through the measurements of their imprint onto the polarization of the cosmic microwave background (CMB). These measurements, requiring unprecedented sensitivity, will be performed over the full sky, at large angular scales, and over 15 frequency bands from 34 GHz to 448 GHz. The LiteBIRD instruments consist of three telescopes, namely the Low-, Medium-and High-Frequency Telescope (respectively LFT, MFT and HFT). We present in this paper an overview of the design of the Medium-Frequency Telescope (89{224 GHz) and the High-Frequency Telescope (166{448 GHz), the so-called MHFT, under European responsibility, which are two cryogenic refractive telescopes cooled down to 5 K. They include a continuous rotating half-wave plate as the first optical element, two high-density polyethylene (HDPE) lenses and more than three thousand transition-edge sensor (TES) detectors cooled to 100 mK. We provide an overview of the concept design and the remaining specific challenges that we have to face in order to achieve the scientific goals of LiteBIRD
Updated Design of the CMB Polarization Experiment Satellite LiteBIRD
Abstract: Recent developments of transition-edge sensors (TESs), based on extensive experience in ground-based experiments, have been making the sensor techniques mature enough for their application on future satellite cosmic microwave background (CMB) polarization experiments. LiteBIRD is in the most advanced phase among such future satellites, targeting its launch in Japanese Fiscal Year 2027 (2027FY) with JAXAâs H3 rocket. It will accommodate more than 4000 TESs in focal planes of reflective low-frequency and refractive medium-and-high-frequency telescopes in order to detect a signature imprinted on the CMB by the primordial gravitational waves predicted in cosmic inflation. The total wide frequency coverage between 34 and 448 GHz enables us to extract such weak spiral polarization patterns through the precise subtraction of our Galaxyâs foreground emission by using spectral differences among CMB and foreground signals. Telescopes are cooled down to 5 K for suppressing thermal noise and contain polarization modulators with transmissive half-wave plates at individual apertures for separating sky polarization signals from artificial polarization and for mitigating from instrumental 1/f noise. Passive cooling by using V-grooves supports active cooling with mechanical coolers as well as adiabatic demagnetization refrigerators. Sky observations from the second SunâEarth Lagrangian point, L2, are planned for 3 years. An international collaboration between Japan, the USA, Canada, and Europe is sharing various roles. In May 2019, the Institute of Space and Astronautical Science, JAXA, selected LiteBIRD as the strategic large mission No. 2
Cosmic ray oriented performance studies for the JEM-EUSO first level trigger
JEM-EUSO is a space mission designed to investigate Ultra-High Energy Cosmic Rays and Neutrinos (E > 5 â
1019 eV) from the International Space Station (ISS). Looking down from above its wide angle telescope is able to observe their air showers and collect such data from a very wide area. Highly specific trigger algorithms are needed to drastically reduce the data load in the presence of both atmospheric and human activity related background light, yet retain the rare cosmic ray events recorded in the telescope. We report the performance in offline testing of the first level trigger algorithm on data from JEM-EUSO prototypes and laboratory measurements observing different light sources: data taken during a high altitude balloon flight over Canada, laser pulses observed from the ground traversing the real atmosphere, and model landscapes reproducing realistic aspect ratios and light conditions as would be seen from the ISS itself. The first level trigger logic successfully kept the trigger rate within the permissible bounds when challenged with artificially produced as well as naturally encountered night sky background fluctuations and while retaining events with general air-shower characteristics
Comparaisons interlaboratoires de comptage de lâactivitĂ© des Ă©metteurs alpha et bĂȘta dans des eaux Ă diffĂ©rentes charges salines
La CETAMA a organisé 3 essais de comparaisons interlaboratoires depuis 2011 afin
dâĂ©valuer la capacitĂ© des laboratoires Ă dĂ©terminer lâactivitĂ© globale des radionuclĂ©ides
Ă©metteurs alpha et bĂȘta des eaux reprĂ©sentatives de matrices environnementales. La natures
des radionucléides (naturels et artificiels) et la variation de la charge saline de la
solution, de faiblement minĂ©ralisĂ© jusquâĂ celle de lâeau de mer, sont les variables
prises en compte. Les modalités de ces essais ont été définies au sein du groupe de
travail « Analyse de lâeau » dans le but de rĂ©soudre certaines difficultĂ©s rencontrĂ©es
lors de la rĂ©alisation de la mesure des activitĂ©s alpha et bĂȘta globales. Lâidentification
des causes de lâĂ©cart constatĂ© entre les valeurs obtenues lors des comptages et la somme
des activités de chacun des radionucléides pris séparément en est la raison principale.
Par ailleurs ces essais permettent aux laboratoires accrĂ©ditĂ©s ou en cours dâaccrĂ©ditation
de rĂ©aliser un exercice prĂ©paratoire en amont de ceux organisĂ©s par lâIRSN pour la
délivrance des agréments. à partir des valeurs de référence des différents radionucléides
contenus dans les échantillons, déterminées par un laboratoire primaire de métrologie, les
moyennes sur les rĂ©sultats obtenus par les laboratoires sont calculĂ©es et comparĂ©es Ă
celles-ci. Lâexploitation des rĂ©sultats a permis de mettre en Ă©vidence la difficultĂ©
dâobtenir une valeur de rĂ©fĂ©rence de comptage pour la dĂ©termination dâune activitĂ© globale
alpha et béta. La prédominance des conditions opératoires et des paramÚtres de mesure dans
lâobtention du rĂ©sultat final en est la raison majeure. La dĂ©marche poursuivie pour la
dĂ©termination de la valeur assignĂ©e de comptage assortie de son incertitude, Ă©tablie Ă
partir de documents de référence (normes, guides...) est présentée de maniÚre détaillée.
La synthÚse des différents essais a permis de dégager des recommandations, notamment en
termes dâĂ©talonnage et de prĂ©paration de la source, qui permettent dâamĂ©liorer
sensiblement la justesse et la fidélité de la méthode
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