Abstract. The two Wide Field Cameras (WFCs) currently flying on the Italian/Dutch X-ray satellite BeppoSAX, image the X-ray sky in the energy range of 1.8 − 28 keV. The field of view is 20• , the angular resolution is 5 arcmin and the energy resolution is 20% at 6 keV, while the source location accuracy will generally be better than one arcmin. All values are at Full Width Half Maximum. The design is based on the coded mask principle where mask and detector both have sizes of about 25.6×25.6 cm 2 . The detector is a Multi Wire Proportional Counter with a position resolution which is better than 0.5 mm for energies below 10 keV. The mask pattern is based on a so called triadic residue set with elements of 1 mm 2 of which 33% are transparent for X-rays. The limiting sensitivity of the WFCs is a few mCrab in 10 5 s. The design and performance of the instrument is described here along with some calibration results and the principle of the image reconstruction.The WFCs represent the latest generation of coded mask X-ray cameras. Their unrivalled field of view, combined with appropriate spatial and temporal resolution and modest energy resolution make the instruments very well suited to perform extensive studies of large areas of the sky and to study transient X-ray phenomena.

No abstract

The current noise at the output of a microcalorimeter with a voltage biased superconducting transition edge thermometer is studied in detail. In addition to the two well-known noise sources: thermal fluctuation noise from the heat link to the bath and Johnson noise from the resistive thermometer, a third noise source strongly correlated with the steepness of the thermometer is required to fit the measured noise spectra. Thermal fluctuation noise, originating in the thermometer itself, fully explains the additional noise. A simple model provides quantitative agreement between the observed and calculated noise spectra for all bias points in the superconducting transition.

We characterised a TES-based X-ray microcalorimeter in an adiabatic demagnetisation refrigerator (ADR) using synchrotron radiation. The detector response and energy resolution was measured at the beam-line in the PTB radiometry laboratory at the electron storage ring BESSY II in the range from 200 to 1800 eV. We present and discuss the results of the energy resolution measurements as a function of energy, beam intensity and detector working point. The measured energy resolution ranges between 1.5 to 2.1 eV in the investigated energy range and is weakly dependent on the detector set point. A first analysis shows a countrate capability, without considerable loss of performance, of about 500 counts per second.

No abstract