A. Emanuele

THE HIGH ENERGY X-RAY EXPERIMENT PDS ON BOARD THE SAX SATELLITE

The high energy X-ray experiment PDS (Phoswich Detection System) is one of the four narrow field instruments on board the SAX satellite. The experiment will be dedicated to temporal and spectral studies of celestial X-ray sources in the 15–300 keV energy band. The PDS detector is composed of 4 actively shielded NaI(Tl)/CsI(Na) phoswich scintillators with a field of view of 1°.4 (FWHM). The total geometric area is 800 cm2. The design of the instrument is made with the goal to achieve an energy resolution better than 17% at 60 keV and a 3 σ flux sensitivity for an observation time of 105 s of about 2 milliCrab in one energy band 40 keV wide centered at 100 keV. The expected 3 σ sensitivity of the PDS to cyclotron lines is about 5×10−5 photons/cm2 s at 60 keV in 105 s. The CsI(Na) lateral shields of the PDS will also be utilized as a gamma-ray burst monitor. Details of the experiment design are described and expected performance is given.

High pressure MWPC for hard X-ray astronomy

Abstract The second generation of detectors for hard X-ray astronomy essentially requires large area detectors and efficient background discrimination. A conventional scheme is to use an array of NaI scintillator crystals with a large number of photomultipliers, a light collection system and individual guard counters for charged particle rejection. High pressure proportional counters can provide an alternative instrument with comparatively higher performance in terms of effective area and background discrimination at lower cost and weight. A 900 cm 2 detector, with a thin aluminium window (0.16 g/cm 2 ) and a 4 atm xenon filling has been developed and tested on a balloon flight.

The Phoswich Detection System PDS on board the SAX satellite

SummaryThe Phoswich Detection System (PDS) is one of the four narrow-field instruments on board the SAX satellite. The experiment will be dedicated to temporal and spectral studies of celestial X-ray sources in the 15÷300 keV energy band. The PDS detector is composed of 4 actively shielded NaI(TI)/CsI(Na) phoswich scintillators and has a field of view of 1.4o (FWHM). The total geometric area is 800 cm2. The instrument is designed with the goal to achieve an energy resolution better than 17% at 60 keV and a 3σ flux sensitivity for an observation time of 105 s of about 1×10−6 photons cm−2 s−1 in an energy band 40 keV wide centred at 100 keV. This sensitivity corresponds to about 2 milliCrab flux units in the same energy range. The expected 3σ sensitivity of the PDS to cyclotron emission lines is about 3×10−5 photons cm−2 s−1 at 60 keV in 105 s. The CsI(Na) lateral shields of the PDS will also be used as a gamma-ray burst monitor. In this report we give a detailed description of the experiment design and we discuss the expected in-flight performances of the PDS.

Performance of LAPEX and its spectroscopic capabilities in the 20--300 keV energy band to observe SN1987a

Recent observations of SN1987a both in the 1–10 keV and in the 10–350 keV energy range detected X‐ray emission from the source with a very hard spectrum, a power law with α∼1.4, and a flux of ∼10 mCrab at 30 keV. We describe the performances of the LAPEX experiment for observation of SN1987a. In the 20–300 keV operative energy band of LAPEX, the following goals can be achieved: detection of emission lines due to Co57 (122 keV) and Ti44 (67.9 and 78.4 keV), elements that could be produced in the supernova explosion; measurement of the comptonized spectrum from the expanding ejecta; investigation on possible coherent pulsations due to a newly born pulsar down to timescales of ∼0.1 ms. In the following, a thorough description of the payload and of its performances will be given.