Search results for "GAMMA-RAY"
showing 10 items of 374 documents
Possible detection of a radio event correlated with a γ-ray burst
1977
COSMIC bursts of electromagnetic radiation, both isolated and in connection with other impulsive astrophysical phenomena, have been sought for many years1, with only one suggestive positive result2, until, in 1973, the discovery of γ-ray bursts3 of cosmic origin prompted a new series of observations4. In 1975 we started a systematic search for electromagnetic bursts at v.h.f. and u.h.f. The system, based at Medicina (Bologna, Italy), is semi-automatic and assures highly efficient data collection. Simultaneous observations at different frequencies facilitate the evaluation of disturbances of local origin and, hopefully, their isolation. Regular observations started in July 1976, and we repor…
X-ray and gamma-ray astronomy with NTD germanium-based microcalorimeters
2002
We report on the performance of our NTD-Ge microcalorimeters. To date, the spectral resolution for x-ray and gamma-ray lines from radioactive sources and laboratory plasmas is 4.8 eV in the entire 1 - 6 keV band and 52 eV at 60 keV. Technical details responsible for this performance are presented as well as an innovative electro-thermal approach for enhancing count-rate capability.
High Energy, High Resolution X-Ray Spectroscopy: Microcalorimeters For Nuclear Line Astrophysics
2005
We introduce focusing optics and microcalorimeter spectroscopy to nuclear line emission astrophysics with a balloon payload concept called, B‐MINE. It is designed to probe the deepest regions of a supernova explosion by detecting 44Ti emission at 68 keV with spatial and spectral resolutions that are sufficient to determine the velocity distribution of the 44Ti emitting region. B‐MINE has a thin plastic foil telescope multilayered to maximize the reflectivity in a 20 keV band centered at 68 keV and a microcalorimeter array optimized for the same energy band. This combination provides a reduced background, an energy resolution of 50 eV and a 3σ sensitivity in 106 s of 6 × 10−8 ph cm−2 s−1 at …
ERRATUM: "Search for High-Energy Muon Neutrinos from the "Naked-Eye" GRB 080319B with the Icecube Neutrino Telescope" (2009, ApJ, 701, 1721)
2009
We have noticed some mistakes in formulae (A2) and (A5) in the appendix of our paper. The errors are not present in the code used in the analysis and hence none of the plots or results is affected. The correct formulae are below.
Simbol-X Mirror Module Thermal Shields: I-Design and X-Ray Transmission
2009
The Simbol‐X mission is designed to fly in formation flight configuration. As a consequence, the telescope has both ends open to space, and thermal shielding at telescope entrance and exit is required to maintain temperature uniformity throughout the mirrors. Both mesh and meshless solutions are presently under study for the shields. We discuss the design and the X‐ray transmission.
Design and implementation of electronics and data acquisition system for Ultra-Fast Flash Observatory
2013
The Ultra-Fast Flash Observatory (UFFO) Pathfinder for Gamma-Ray Bursts (GRBs) consists of two telescopes. The UFFO Burst Alert & Trigger Telescope (UBAT) handles the detection and localization of GRBs, and the Slewing Mirror Telescope (SMT) conducts the measurement of the UV/optical afterglow. UBAT is equipped with an X-ray detector, analog and digital signal readout electronics that detects X-rays from GRBs and determines the location. SMT is equipped with a stepping motor and the associated electronics to rotate the slewing mirror targeting the GRBs identified by UBAT. First the slewing mirror points to a GRB, then SMT obtains the optical image of the GRB using the intensified CCD an…
Background Rejection of Charged Particles in the Simbol-X Telescope: Preliminary Study of Protons Scattering
2009
X-ray telescopes equipped with focusing optics in high eccentric orbit, as e.g. Newton-XMM and Chandra, showed a degradation of the detector performance and an important increase of the noise due to soft protons with energy between a few tens of keV and a few MeV, that are focused on the detector through the mirror module. It should be noted that the focusing of the protons by Wolter optics was an unexpected phenomenon. In Simbol-X a magnetic diverter will be implemented to deflect protons, in order to reduce the flux of charged particles impinging upon the focal plane. Obviously the design of the diverter should take into consideration the protons distribution at the exit of the mirror mod…
Accreting Pulsars: Mixing-up Accretion Phases in Transitional Systems
2018
In the last 20 years our understanding of the millisecond pulsar population changed dramatically. Thanks to the large effective area and good time resolution of the NASA X-ray observatory Rossi X-ray Timing Explorer, we discovered that neutron stars in Low Mass X-ray Binaries (LMXBs) spins at frequencies between 200 and 750 Hz, and indirectly confirmed the recycling scenario, according to which neutron stars are spun up to millisecond periods during the LMXB-phase. In the meantime, the continuous discovery of rotation-powered millisecond pulsars in binary systems in the radio and gamma-ray band (mainly with the Fermi Large Area Telescope) allowed us to classify these sources into two "spide…
Alpha-Photon Coincidence Spectroscopy Along Element 115 Decay Chains
2014
Produced in the reaction 48Ca+243Am, thirty correlated α-decay chains were observed in an experiment conducted at the GSI Helmholzzentrum fur Schwerionenforschung, Darmstadt, Germany. The decay chains are basically consistent with previous findings and are considered to originate from isotopes of element 115 with mass numbers 287, 288, and 289. A set-up aiming specifically for high-resolution charged particle and photon coincidence spectroscopy was placed behind the gas-filled separator TASCA. For the first time, γ rays as well as X-ray candidates were observed in prompt coincidence with the α-decay chains of element 115.
GRB 070311: a direct link between the prompt emission and the afterglow
2007
We present prompt gamma-ray, early NIR/optical, late optical and X-ray observations of the peculiar GRB 070311 discovered by INTEGRAL, in order to gain clues on the mechanisms responsible for the prompt gamma-ray pulse as well as for the early and late multi-band afterglow of GRB 070311. We fitted with empirical functions the gamma-ray and optical light curves and scaled the result to the late time X-rays. The H-band light curve taken by REM shows two pulses peaking 80 and 140 s after the peak of the gamma-ray burst and possibly accompanied by a faint gamma-ray tail. Remarkably, the late optical and X-ray afterglow underwent a major rebrightening between 3x10^4 and 2x10^5 s after the burst …