Seminars Archive

High resolution, high count rate x-rays spectroscopy with state of the art silicon detectors

Abstract
New cylindrical silicon drift detectors have been designed, fabricated and tested. They comprise an integrated on-chip amplifier system with continuous reset, on-chip voltage divider, electron accumulation layer stabilizer, large area, homogeneous radiation entrance window and a drain for surface generated leakage current . At count rates as high as 1.000.000 counts per sec and per cm^2, they still show excellent spectroscopic behaviour at room temperature operation in single photon detection mode. The energy resolution at room temperature is 180~eV at 6~keV X-ray energy and 140~eV at -20 C, being achieved with Peltier coolers. Those systems were operated at synchrotron light sources (ESRF, HASYLAB and NLS) , as X-ray fluorescence spectrometers in scanning electron microscopes and as ultra low noise photodiodes. For the European X-ray Multi-Mirror mission (XMM) and the German X-ray satellite ABRIXAS fully depleted pn-CCDs have been fabricated, enabling high speed, low noise, position resolving X-ray spectroscopy. The detector was designed and fabricated with a homogeneously sensitive area of 36 cm^2 . At 150~K it has a noise of 4 rms only, with a readout time of the total focal plane array of 4 ms . The maximum count rate for single photon counting was 100.000 cps under flat field conditions. In the integration mode about 10^8 cps can be detected at 6~keV. Its position resolution is in the order of 100 micron. The quantum efficiency is higher than 90% from Carbon K X-rays (272 eV) up to 10~keV. The operation of those detectors is alrea dy foreseen at synchrotron light sources. All systems are fabricated in planar technology having the detector and amplifiers monolythically integrated on high resistivity silicon.