I. L. Rasmussen

JEM-X: The X-ray monitor aboard INTEGRAL ?

The JEM-X monitor provides X-ray spectra and imaging with arcminute angular resolution in the 3 to 35 keV band. The good angular resolution and the low energy response of JEM-X plays an important role in the identification of gamma ray sources and in the analysis and scientific interpretation of the combined X-ray and gamma ray data. JEM-X is a coded aperture instrument consisting of two identical, coaligned telescopes. Each of the detectors has a sensitive area of 500 cm 2 , and views the sky through its own coded aperture mask. The two coded masks are inverted with respect to each other and provides an angular resolution of 3 0 across an eective field of view of about 10 diameter.

On cosmic-ray cut-off terminology

SummaryThe study of cosmic-ray access to locations within the geomagnetic field has evolved over the past fifty years. Cosmic-ray cut-off terminology, originally developed to describe particle access and cut-off rigidities, has not evolved with the scientific advances in the field, and misunderstandings and misapplications of historical work have occurred. This paper is an attempt to remedy this situation by clarifying the areas in which changes have occurred and by providing a cross reference between the historical terms and those terms now in use for innovative cosmic-ray studies which are underway in several laboratories.

The Absolute Flux of Protons and Helium at the Top of the Atmosphere Using IMAX

The cosmic-ray proton and helium spectra from 0.2 GeV nucleon^(-1) to about 200 GeV nucleon^(-1) have been measured with the balloon-borne experiment Isotope Matter-Antimatter Experiment (IMAX) launched from Lynn Lake, Manitoba, Canada, in 1992. IMAX was designed to search for antiprotons and light isotopes using a superconducting magnet spectrometer together with scintillators, a time-of-flight system, and Cherenkov detectors. Using redundant detectors, an extensive examination of the instrument efficiency was carried out. We present here the absolute spectra of protons and helium corrected to the top of the atmosphere and to interstellar space. If demodulated with a solar modulation parameter of Φ = 750 MV, the measured interstellar spectra between 20 and 200 GV can be represented by a power law in rigidity, with (1.42 ± 0.21) × 10^4R^(-2.71±0.04) (m^2 GV s sr)^(-1) for protons and (3.15 ± 1.03) × 10^3R^(-2.79±0.08) (m^2 GV s sr)^(-1) for helium.

JEM-X science analysis software

The science analysis of the data from JEM-X on INTEGRAL is performed through a number of levels including corrections, good time selection, imaging and source finding, spectrum and light-curve extraction. These levels consist of individual executables and the running of the complete analysis is controlled by a script where parameters for detailed settings are introduced. The end products are FITS files with a format compatible with standard analysis packages such as XSPEC.

The Cosmic-Ray 3He/4He Ratio from 200 MeV per Nucleon−1 to 3.7 GeV per Nucleon−1

The abundances of cosmic-ray helium isotopes between 0.2 and 3.7 GeV nucleon^(-1) were measured by the Isotope Matter Antimatter Experiment (IMAX) during a flight from Lynn Lake, Manitoba, Canada on 1992 July 16-17. The IMAX balloon-borne magnetic spectrometer realized a direct measurement of the charge, the velocity, and the rigidity of cosmic rays using plastic scintillators, a high-resolution time-of-flight system, and two silica-aerogel Cerenkov counters in conjunction with a drift chamber/multiwire proportional chamber tracking system. About 75,000 helium isotopes are identified by their mass using the velocity versus magnetic rigidity technique. The measured ^3He/^4He ratios are corrected to the top of the atmosphere, and a comparison with previous data is given. The observed isotopic composition is found to be generally consistent with the predictions of a standard leaky box model of cosmic-ray transport in the Galaxy.

JEM-X inflight performance

We summarize the inflight performance of JEM-X, the X-ray monitor on the INTEGRAL mission during the initial ten months of operations. The JEM-X instruments have now been tuned to stable operational conditions. The performance is found to be close to the pre-launch expectations. The ground calibrations and the inflight calibration data permit to determine the instruments characteristics to fully support the scientific data analysis.

The HEAO-3 Cosmic Ray Isotope spectrometer

This paper describes the Cosmic Ray Isotope instrument launched aboard the HEAO-3 satellite on September 20, 1979. The primary purpose of the experiment is to measure the isotopic composition of cosmic ray nuclei from Be-7 to Fe-58 over the energy range 0.5 to 7 GeV/nucleon. In addition charge spectra will be measured between beryllium and tin over the energy range 0.5 to 25 GeV/nucleon. The charge and isotope abundances measured by the experiment provide essential information needed to further our understanding of the origin and propagation of high energy cosmic rays. The instrument consists of 5 Cerenkov counters, a 4 element neon flash tube hodoscope and a time-of-flight system. The determination of charge and energy for each particle is based on the multiple Cerenkov technique and the mass determination will be based upon a statistical analysis of particle trajectories in the geomagnetic field.

A measurement of cosmic ray deuterium from 0.5–2.9 GeV/nucleon

The rare isotopes ^(2)H and ^(3)He in cosmic rays are believed to originate mainly from the interaction of high energy protons and helium with the galactic interstellar medium. The unique propagation history of these rare isotopes provides important constraints on galactic cosmic ray source spectra and on models for their propagation within the Galaxy. Hydrogen and helium isotopes were measured with the balloon-borne experiment, IMAX, which flew from Lynn Lake, Manitoba in 1992. The energy spectrum of deuterium between 0.5 and 3.2 GeV/nucleon measured by the IMAX experiment as well as previously published results of ^(3)He from the same instrument will be compared with predictions of cosmic ray galactic propagation models. The observed composition of the light isotopes is found to be generally consistent with the predictions of the standard Leaky Box Model derived to fit observations of heavier nuclei

Calibration facility and preflight characterization of the photometer in the Infrared Space Observatory

A calibration facility simulating the optical and cryogenic environment of the Infrared Space Observatory (ISO) satellite has been built for characterizing the ISO photometer (ISOPHOT). This facility uses a commercially calibrated 900-K blackbody radiation source and optics at room temperature to provide an f /15 beam to the instrument, which is contained in a LHe cryostat. The low-level infrared flux levels of the ISO are obtained by using a light-sealed instrument chamber and cold attenuation filters. The infrared flux can be calculated using the known blackbody emission and the cold calibrated transmission spectra of the filters. The calibration facility further provides a scanning mechanism, a light modulator, and filters for polarization measurements and wavelength calibrations of the ISOPHOT spectrometer channels. Electrical support equipment for the instrument operation and software for data archiving and analysis have been customized for this project. The test program comprised a standardized acceptance test for the entire instrument and special tests addressing individual instrument properties. The data obtained contain the photometric sensitivities of ISOPHOT, optimized instrument settings, reference data for the integrated system tests, and inputs for the ongoing mission planning.

X-ray observations of the Crab Pulsar and Nebula with JEM-X on INTEGRAL ?

The Crab pulsar is the best studied rotation powered pulsar. We report the results obtained in the 3-35 keV energy band with the X-ray monitor, JEM-X, on ESAs recently launched-ray mission, INTEGRAL.