SWS-Detector Glitch Effect Correction

We describe how the ISO-SWS (Infrared Space Observatory – Short Wavelength Spectrometer) software packages detect various glitch events i.e. high energy particle hits effecting the SWS detectors. A rough classification of glitch types is given. The events cause an instantaneous change in the slope of the SWS detector read outs followed by a distortion of the further samples, so called glitch tails. As a consequence the S/N ratio and photometric accuracy are reduced.Different strategies, how to remove the resulting distortion of the detectorread-out-ramp after a hit, are presented. The methods of the basic SWS software packages, the Pipeline and Interactive Analysis, will be discussed. The Pipeline has to treat glitch effects automatically. The Interactive Analysis system provides the user with a comfortable Graphical User Interface (GUI) for Trend Analysis, detailed analysis of certain glitches and the testing of new algorithms.     

Instruments of RT-2 experiment onboard CORONAS-PHOTON and their test and evaluation IV: background simulations using GEANT-4 toolkit

Hard X-ray detectors in space are prone to background signals due to the ubiquitous cosmic rays and cosmic diffuse background radiation that continuously bombards the satellites which carry the detectors. In general, the background intensity depends on the space environment as well as the material surrounding the detectors. Understanding the behavior of the background noise in the detector is very important to extract the precise source information from the detector data. In this paper, we carry out Monte Carlo simulations using the GEANT-4 toolkit to estimate the prompt background noise measured with the detectors of the RT-2 Experiment onboard the CORONAS-PHOTON satellite.     

Cosmic-Ray Variations During the Two Greatest Bursts of Solar Activity in the 23rd Solar Cycle

During two extreme bursts of solar activity in March–April 2001 and October–November 2003, the ground-based neutron monitor network recorded a series of outstanding events distinguished by their magnitude and unusual peculiarities. The important changes that lead to increased activity initiated not with the sunspot appearance, but with the large-scale solar magnetic field reconfiguration. A series of strong and moderate magnetic storms and powerful proton events (including ground-level enhancements, GLE) were registered during these periods. The largest and most productive in the 23rd solar cycle, active region 486, generated a significant series of solar flares among which the 4 November 2003 flare (X28/3B) was the most powerful X-ray solar event ever observed. The fastest arrival of the interplanetary disturbance from the Sun (after August 1972) and the highest solar wind velocity and IMF intensity were recorded during these events. Within 1 week, three GLEs of solar cosmic rays were registered by the neutron monitor network (28 and 29 October and 2 November 2003). In this work, we perform a tentative analysis of a number of the effects seen in cosmic rays during these two periods, using the neutron monitor network and other relevant data.     

Monte Carlo study of detector concepts for the MAX Laue lens gamma-ray telescope

MAX is a proposed Laue lens gamma-ray telescope taking advantage of Bragg diffraction in crystals to concentrate incident photons onto a distant detector. The Laue lens and the detector are carried by two separate satellites flying in formation. Significant effort is being devoted to studying different types of crystals that may be suitable for focusing gamma rays in two 100 keV wide energy bands centered on two lines which constitute the prime astrophysical interest of the MAX mission: the 511 keV positron annihilation line, and the broadened 847 keV line from the decay of ⁵⁶Co copiously produced in Type Ia supernovae. However, to optimize the performance of MAX, it is also necessary to optimize the detector used to collect the source photons concentrated by the lens. We address this need by applying proven Monte Carlo and event reconstruction packages to predict the performance of MAX for three different Ge detector concepts: a standard coaxial detector, a stack of segmented detectors, and a Compton camera consisting of a stack of strip detectors. Each of these exhibits distinct advantages and disadvantages regarding fundamental instrumental characteristics such as detection efficiency or background rejection, which ultimately determine achievable sensitivities. We conclude that the Compton camera is the most promising detector for MAX in particular, and for Laue lens gamma-ray telecopes in general.     

Evolution of ground-based gamma-ray astronomy from the early days to the Cherenkov Telescope Arrays

Most of what we know of cosmic gamma rays has come from spacecraft, but at energies above tens of GeV it has become possible to make observations with ground-based detectors of enormously greater collecting area. In recent years one such detector type, the cluster of imaging air Cherenkov telescopes, has reached a very productive state, whilst several alternative approaches have been explored, including converted solar power collectors and novel high-altitude particle shower detectors which promised to extend the energy range covered. Key examples of development from 1952 to 2011 are followed, noting the problems and discoveries that stimulated the current work, explaining the logic of the alternative approaches that were taken. The merits of the current major Cherenkov observatories and of other viable detectors are examined and compared, with examples of the astrophysical information they are beginning to provide. The detectors are still evolving, as we still do not understand the processes onto which the gamma rays provide a window. These include the acceleration of Galactic cosmic rays (in particular, the wide-band spectra of radiation from some individual supernova remnants are still hard to interpret), the highly relativistic and variable jets from active galactic nuclei, and aspects of the electrodynamics of pulsars. Larger groups of Cherenkov telescopes still offer the possibility of an increase in power of the technique for resolvable Galactic sources especially.     

Capabilities of a giant hybrid air shower detector

Recent reports of superhigh energy cosmic rays beyond the expected spectral cutoff have intensified interest in the unknown origin of the highest energy cosmic rays. There is a need for a much larger data base of more precisely measured air showers. This requires new sensitive detectors of enormous aperture. Combining a ground array of particle counters with an optical detector of atmospheric fluorescence yields a detector of outstanding capability. Such a hybrid detector provides far more accurate measurements of energies, arrival directions, and primary particle atomic masses than can be achieved by either type of detector separately.     

Calibration of particle detectors for secondary cosmic rays using gamma-ray beams from thunderclouds

After observation of hundreds of Thunderstorm Ground Enhancements (TGEs) we measure energy spectra of particles originated in clouds and directed towards Earth. We use these “beams” for calibration of cosmic ray detectors located beneath the clouds at an altitude of 3200 m at Mount Aragats in Armenia. The calibrations of particle detectors with fluxes of TGE gamma rays are in good agreement with simulation results and allow estimation of the energy thresholds and efficiencies of numerous particle detectors used for studying galactic and solar cosmic rays.     

Detection of atmospheric Cherenkov radiation using solar heliostat mirrors

There is considerable interest world-wide in developing large area atmospheric Cherenkov detectors for ground-based gamma-ray astronomy. This interest stems, in large part, from the fact that the gamma-ray energy region between 20 and 250 GeV is unexplored by any experiment. Atmospheric Cherenkov detectors offer a possible way to explore this region, but large photon collection areas are needed to achieve low energy thresholds. We are developing an experiment using the heliostat mirrors of a solar power plant as the primary collecting element. As part of this development, we built a detector using four heliostat mirrors, a secondary Fresnel lens, and a fast photon detection system. In November 1994, we used this detector to record atmospheric Cherenkov radiation produced by cosmic ray particles showering in the atmosphere. The detected rate of cosmic ray events was consistent with an energy threshold near 1 TeV. The data presented here represent the first detection of atmospheric Cherenkov radiation using solar heliostats viewed from a central tower.     

Pionic photons and neutrinos from cosmic ray accelerators

Identifying the accelerators that produce the Galactic and extragalactic cosmic rays has been a priority mission of several generations of high energy gamma ray and neutrino telescopes; success has been elusive so far. Detecting the gamma-ray and neutrino fluxes associated with cosmic rays reaches a new watershed with the completion of IceCube, the first neutrino detector with sensitivity to the anticipated fluxes, and the construction of CTA, a ground-based gamma ray detector that will map and study candidate sources with unprecedented precision. In this paper, we revisit the prospects for revealing the sources of the cosmic rays by a multiwavelength approach; after reviewing the methods, we discuss supernova remnants, gamma ray bursts, active galaxies and GZK neutrinos in some detail.     

Energetic particles from the sun

This paper discusses solar cosmic ray phenomena and related topics from the solar physical point of view. Basic physics of the solar atmosphere and solar flare phenomena are, therefore, considered in some detail. Since solar cosmic rays are usually produced by solar flares, we must first understand the processes and mechanism of solar flares, especially the so-called proton flares, in order to understand the acceleration mechanism of solar cosmic rays and their behaviour in both the solar atmosphere and interplanetary space. For this reason, detailed discussion is given on various phenomena associated with solar flares, proton flare characteristics, and the mechanism of solar flares.Since the discovery of solar cosmic rays by Forbush, the interplanetary space has been thought of as medium in which solar cosmic rays propagate. In this paper, the propagation of solar cosmic rays in this space is, therefore, discussed briefly by referring to the observed magnetic properties of this space. Finally, some problems related to the physics of galactic cosmic rays are discussed.Astrophysics and Space Science Review Paper.     

X-ray emission from solar flares

Solar X-ray Spectrometer (SOXS), the first space-borne solar astronomy experiment of India was designed to improve our current understanding of X-ray emission from the Sun in general and solar flares in particular. SOXS mission is composed of two solid state detectors, viz., Si and CZT semiconductors capable of observing the full disk Sun in X-ray energy range of 4–56 keV. The X-ray spectra of solar flares obtained by the Si detector in the 4–25 keV range show evidence of Fe and Fe/Ni line emission and multi-thermal plasma. The evolution of the break energy point that separates the thermal and non-thermal processes reveals increase with increasing flare plasma temperature. Small scale flare activities observed by both the detectors are found to be suitable to heat the active region corona; however their location appears to be in the transition region.     

The SWAP EUV Imaging Telescope. Part II: In-flight Performance and Calibration

The Sun Watcher with Active Pixel System detector and Image Processing (SWAP) telescope was launched on 2 November 2009 onboard the ESA PROBA2 technological mission and has acquired images of the solar corona every one to two minutes for more than two years. The most important technological developments included in SWAP are a radiation-resistant CMOS-APS detector and a novel onboard data-prioritization scheme. Although such detectors have been used previously in space, they have never been used for long-term scientific observations on orbit. Thus SWAP requires a careful calibration to guarantee the science return of the instrument. Since launch we have regularly monitored the evolution of SWAP’s detector response in-flight to characterize both its performance and degradation over the course of the mission. These measurements are also used to reduce detector noise in calibrated images (by subtracting dark-current). Because accurate measurements of detector dark-current require large telescope off-points, we also monitored straylight levels in the instrument to ensure that these calibration measurements are not contaminated by residual signal from the Sun. Here we present the results of these tests and examine the variation of instrumental response and noise as a function of both time and temperature throughout the mission.     

Introduction to Large High Altitude Air Shower Observatory (LHAASO)

Since the century discovery of cosmic ray, the origin of cosmic ray is always a mystery. The study on the origin of high-energy cosmic ray is in an interdiscipline between the very high-energy (VHE) gamma-ray astronomy and the cosmic ray physics. The Large High Altitude Air Shower Observatory (LHAASO) is a unique and new generation cosmic-ray station with the advantages of high altitude, all-weather, and large-scale. It takes the function of hybrid technology to detect cosmic rays and to upgrade greatly the resolving power between gamma rays and cosmic rays. The LHAASO is expected to make the full-sky survey to find new gamma-ray sources, to obtain the highest sensitivity of gamma-ray detection at the high energy band of > 30 TeV, and to make the very high precision measurement on the component energy spectra of cosmic rays in a broad energy range of 5 orders of magnitude, in order to provide the evidence for revealing the mystery of the origin of cosmic ray. This paper describes the detector structure, performance superiority and scientific motivation of the LHAASO.     

Neutrino astronomy: An update

Detecting neutrinos associated with the still enigmatic sources of cosmic rays has reached a new watershed with the completion of IceCube, the first detector with sensitivity to the anticipated fluxes. In this review, we will briefly revisit the rationale for constructing kilometer-scale neutrino detectors and summarize the status of the field.     

Cosmic Ray Effects on the ISOCAM Long Wave Detector

The ISOCAM detector is subjected to transient effects induced bycosmic rays, the so-called glitches. This paper is focused onthe ISOCAM long wave detector. The predicted glitch rates havebeen re-evaluated by taking into account secondary particlesproduction in the materials surrounding the LW detector. We showin this preliminary study that the difference between thepreviously predicted glitch rate and the observed rate may beexplained by secondary particles.     

Stellar and solar flares

Some ideas are developed concerning solar flares which have been presented earlier by the author (Schatzman, 1966a). Emphasis is laid on the problem of energy transport; from the energy supply to the region of the optical flare, on the storage of low energy cosmic ray particles in a magnetic bottle before the beginning of the optical flare, and the mechanism which triggers both the optical flare, and the production of high-energy cosmic rays. The relation between solar and stellar flares is considered.Lecture given at Goddard Space Flight Center, November 4, 1966.     

Preliminary Results of High-Energy Cosmic Ray Muons as Observed by a Small Multiwire Detector Operated at High Cutoff Rigidity

Solar disturbances modulate primary cosmic rays on different time scales. Studying cosmic ray variation is an important subject that attracts scientists from different disciplines. We have constructed and installed (in Riyadh, Saudi Arabia, Rc =14.4 GV) a three-layer small (20 × 20 cm²) MultiWire Chamber (MWC) telescope to study cosmic ray variations and investigate their influence on various atmospheric and environmental processes. Preliminary results obtained from the developed detector are given. The influence of both atmospheric pressure and temperature was studied. Both the temperature and pressure coefficients were calculated and were consistent with those previously obtained. Short-term cosmic ray periodicities, such as the 27-day period, and its two harmonics, have been identified. Sporadic variations caused by some solar activity processes have been inspected. The obtained results from this detector have been compared to the existing 1 m² scintillator detector, as well as to some of the neutron monitors, showing comparable results.     

Simulated performance of dedicated Ge-strip Compton telescopes as γ-lens focal plane instrumentation

With focusing of gamma rays in the nuclear-line energy regime starting to establish itself as a feasible and very promising approach for high-sensitivity γ-ray (line) studies of individual sources, optimizing the focal plane instrumentation for γ-ray lens telescopes is a prime concern. Germanium detectors offer the best energy resolution available at ∼2 keV FWHM at 1 MeV and thus constitute the detector of choice for a spectroscopy mission in the MeV energy range. Using a Compton detector focal plane has three advantages over monolithic detectors: additional knowledge about (Compton) events enhances background rejection capabilities, the inherently finely pixellated detector naturally allows the selection of events according to the focal spot size and position, and Compton detectors are inherently sensitive to γ-ray polarization. We use the extensive simulation and analysis package assembled for the ACT vision mission study to explore achievable sensitivities for different Ge Compton focal plane configurations as a first step towards determining an optimum configuration.CBW thanks the Townes Fellowship at UCB and NASA Grant NNG05WC28G for Support.     

The HUS solar flare and cosmic gamma-ray burst detector aboard the ULYSSES spacecraft

The HUS-Ulysses team has prepared an instrument aboard the ULYSSES spacecraft consisting of 2 CsI detectors and 2 Si surface barrier detectors for measuring X-rays in the range 5–200 keV up to 8 ms resolution. The prime objectives are the study of solar flares and of cosmic gamma-ray bursts. The ULYSSES mission will leave the ecliptic during the next solar cycle. The solar data can be used in conjunction with other experiments to measure the directivity of the emission and for correlative studies. The cosmic gamma-ray burst data will improve source localizations, allowing sensitive searches for counterparts. The energy range and the 4 field of view is well suited to the detection of the soft gamma-ray repeaters.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain