Space Detectors for Gamma Rays (100 MeV - 100 GeV): from EGRET to Fermi LAT

The design of spaceborne high-energy (E>100 MeV) gamma-ray detectors depends on two principal factors: (1) the basic physics of detecting and measuring the properties of the gamma rays; and (2) the constraints of operating such a detector in space for an extended period. Improvements in technology have enabled major advances in detector performance, as illustrated by two successful instruments, EGRET on the Compton Gamma Ray Observatory and LAT on the Fermi Gamma-ray Space Telescope.Comment: 11 pages, 7 figures, submitted to Comptes Rendus Physiqu

Périodes de niveaux excités du calcium 40 et de l'iode 132

Cet article présente la mesure de la période, T1/2 = (2,15 ± 0,08) ns du premier niveau excité de 40Ca. Les mesures de coïncidences différées dans 132I ont permis de fixer l'ordre d'émission des deux rayons gamma de 52 keV et 232 keV ; les périodes sont égales à T1/2 = (0,96 ± 0,04) ns pour le niveau à 52 keV et à T1/2 = (1,42 ± 0,05) ns pour le niveau à 284 keV. Ces valeurs, et des mesures du coefficient de conversion interne α K, permettent d'attribuer les ordres multipolaires M1 + E2 et E2 respectivement pour les transitions de 52 et 232 keV

Une plateforme pour l'analyse de matériaux par faisceaux d'ions à ARRONAX : Etude de l'effet d'humidité sur les échantillons

International audienceQuantification of soil pollution with method based on X-ray detection like X-Ray Fluorescence(XRF) suffers of multiple bias (moisture, surface state) especially when it's used for insituanalysis using portable-XRF. In order to study the effect of moisture on the results of ananalysis performed using X-Ray, we have performed studies using high energy PIXE/PIGE atthe ARRONAX. Samples were made of sand of different type. High energy PIXE/PIGE allowsus to avoid bias from surface state and to focus on moisture effect. It also allows to assessthe chemical composition of the sample. Results show a different behavior for each elementpresent in volcanic sand.</p

Screening of Bi-parental and Mutant Clones of Sugarcane Saccharum officinarum L. for Resistance to Smut Disease

Six newly developed clones of sugarcane (Saccharum officinarum L.) clones obtained from gamma irradiated progenies (KRS/96/007, KRS/96/002, KRS/96/001) and from bi-parental crosses (SRS/96/305, SRS/96/210 and SRS/96/004) were used in the study of their level of smut disease resistance. The results of the application of the standard smut disease scale of sugarcane showed that all the clones from bi-parental crosses and only one clone (KRS/96/002) from gamma irradiated progenies were highly resistant to smut disease of sugarcane with zero incidence of the disease. Diseased plants were observed on the remaining two clones from gamma irradiated progenies (KRS/96/007 and KRS/96/001), but the percentage of infection was very low (1.1%) and they were therefore also rated as resistant clones

The production of cosmic gamma rays in interstellar and intergalactic cosmic-ray collisions. 4 - Gamma-ray production from cosmic proton-antiproton interactions

Production of cosmic gamma rays by annihilation of antimatte

Ground-based detectors in very-high-energy gamma-ray astronomy

Following the discovery of the cosmic rays by Victor Hess in 1912, more than 70 years and numerous technological developments were needed before an unambiguous detection of the first very-high-energy gamma-ray source in 1989 was made. Since this discovery the field on very-high-energy gamma-ray astronomy experienced a true revolution: A second, then a third generation of instruments were built, observing the atmospheric cascades from the ground, either through the atmospheric Cherenkov light they comprise, or via the direct detection of the charged particles they carry. Present arrays, 100 times more sensitive than the pioneering experiments, have detected a large number of astrophysical sources of various types, thus opening a new window on the non-thermal Universe. New, even more sensitive instruments are currently being built; these will allow us to explore further this fascinating domain. In this article we describe the detection techniques, the history of the field and the prospects for the future of ground-based very-high-energy gamma-ray astronomy.Comment: 21 pages, 13 figure

The future of gamma-ray astronomy

The field of gamma-ray astronomy has experienced impressive progress over the last decade. Thanks to the advent of a new generation of imaging air Cherenkov telescopes (H.E.S.S., MAGIC, VERITAS) and thanks to the launch of the Fermi-LAT satellite, several thousand gamma-ray sources are known today, revealing an unexpected ubiquity of particle acceleration processes in the Universe. Major scientific challenges are still ahead, such as the identification of the nature of Dark Matter, the discovery and understanding of the sources of cosmic rays, or the comprehension of the particle acceleration processes that are at work in the various objects. This paper presents some of the instruments and mission concepts that will address these challenges over the next decades.Comment: To be published in Comptes Rendus Physique (2016