We developed a camera with a 264 × 264 pixel pnCCD of 48 μm size (thickness 450 μm) for X-ray and optical
applications. It has a high quantum efficiency and can be operated up to 400 / 1000 Hz (noise≈ 2:5 ē ENC
/ ≈4:0 ē ENC). High-speed astronomical observations can be performed with low light levels. Results of test
measurements will be presented. The camera is well suitable for ground based preparation measurements for
future X-ray missions. For X-ray single photons, the spatial position can be determined with significant sub-pixel
Measurement campaigns of the Max-Planck Advanced Study Group (ASG) in cooperation with the Center for
Free Electron Laser Science (CFEL) at DESY-FLASH and SLAC-LCLS have established pnCCDs as universal
photon imaging spectrometers in the energy range from 90 eV to 2 keV. In the CFEL-ASG multi purpose
chamber (CAMP), pnCCD detector modules are an integral part of the design with the ability to detect photons
at very small scattering angles. In order to fully exploit the spectroscopic and intensity imaging capability of
pnCCDs, it is essentially important to translate the unprocessed raw data into units of photon counts for any
given position on the detection area.
We have studied the performance of pnCCDs in FEL experiments and laboratory test setups for the range
of signal intensities from a few X-ray photons per signal frame to 100 or more photons with an energy of 2 keV
per pixel. Based on these measurement results, we were able to characterize the response of pnCCDs over the
experimentally relevant photon energy and intensity range. The obtained calibration results are directly relevant
for the physics data analysis. The accumulated knowledge of the detector performance was implemented in
guidelines for detector calibration methods which are suitable for the specific requirements in photon science
experiments at Free Electron Lasers.
We discuss the achievable accuracy of photon energy and photon count measurements before and after the
application of calibration data. Charge spreading due to illumination of small spots with high photon rates is
discussed with respect to the charge handling capacity of a pixel and the effect of the charge spreading process
on the resulting signal patterns.
Quantum key distribution (QKD)1 is the first method of quantum information science that will find its way into our everyday life. It employs fundamental laws of quantum physics to ensure provably secure symmetric key generation between two parties. The key can then be used to encrypt and decrypt sensitive data with unconditional security. Here, we report on a free space QKD implementation over a distance of 480 m using strongly attenuated laser pulses. It is designed to work continuously without human interaction. Until now, it produces quantum keys unattended at night for more than 12 hours with a sifted key rate of more than 50 kbit/s on average and a quantum bit error rate between 3% and 5%.