The European Photon Imaging Camera (EPIC) consortium has provided the focal plane instruments for the three X-ray mirror systems on XMM-Newton. Two cameras with a reflecting grating spectrometer in the optical path are equipped with MOS type CCDs as focal plane detectors (Turner 2001), the telescope with the full photon flux operates the novel pn-CCD as an imaging X-ray spectrometer. The pn-CCD camera system was developed under the leadership of the Max-Planck-Institut fur extraterrestrische Physik (MPE), Garching. The concept of the pn-CCD is described as well as the dierent operational modes of the camera system. The electrical, mechanical and thermal design of the focal plane and camera is briefly treated. The in-orbit performance is described in terms of energy resolution, quantum eciency, time resolution, long term stability and charged particle background. Special emphasis is given to the radiation hardening of the devices and the measured and expected degradation due to radiation damage of ionizing particles in the rst 9 months of in orbit operation.

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The European Photon Imaging Camera on XMM-Newton: The pn-CCD camera

Fourth generation accelerator-based light sources, such as VUV and X-ray Free Electron Lasers (FEL), deliver ultra-brilliant (∼1012–1013 photons per bunch) coherent radiation in femtosecond (∼10–100 fs) pulses and, thus, require novel focal plane instrumentation in order to fully exploit their unique capabilities. As an additional challenge for detection devices, existing (FLASH, Hamburg) and future FELs (LCLS, Menlo Park; SCSS, Hyogo and the European XFEL, Hamburg) cover a broad range of photon energies from the EUV to the X-ray regime with significantly different bandwidths and pulse structures reaching up to MHz micro-bunch repetition rates. Moreover, hundreds up to trillions of fragment particles, ions, electrons or scattered photons can emerge when a single light flash impinges on matter with intensities up to 1022 W/cm2. In order to meet these challenges, the Max Planck Advanced Study Group (ASG) within the Center for Free Electron Laser Science (CFEL) has designed the CFEL-ASG MultiPurpose (CAMP) chamber. It is equipped with specially developed photon and charged particle detection devices dedicated to cover large solid-angles. A variety of different targets are supported, such as atomic, (aligned) molecular and cluster jets, particle injectors for bio-samples or fixed target arrangements. CAMP houses 4π solid-angle ion and electron momentum imaging spectrometers (“reaction microscope”, REMI, or “velocity map imaging”, VMI) in a unique combination with novel, large-area, broadband (50 eV–25 keV), high-dynamic-range, single-photon-counting and imaging X-ray detectors based on the pnCCDs. This instrumentation allows a new class of coherent diffraction experiments in which both electron and ion emission from the target may be simultaneously monitored. This permits the investigation of dynamic processes in this new regime of ultra-intense, high-energy radiation—matter interaction. After an introduction into the salient features of the CAMP chamber and the properties of the redesigned REMI/VMI spectrometers, the new 1024×1024 pixel format pnCCD imaging detector system will be described in detail. Results of tests of four smaller format (256×512) devices of identical performance, conducted at FLASH and BESSY, will be presented and the concept as well as the anticipated properties of the full, large-scale system will be elucidated. The data obtained at both radiation sources illustrate the unprecedented performance of the X-ray detectors, which have a voxel size of 75×75×450 μm3 and a typical read-out noise of 2.5 electrons (rms) at an operating temperature of −50 °C.

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Large-format, high-speed, X-ray pnCCDs combined with electron and ion imaging spectrometers in a multipurpose chamber for experiments at 4th generation light sources

A new type of radiation detector, a p-type modified electrode germanium diode, is presented. It is shown that the prototype displays, for the first time, a combination of features (mass, energy threshold and background expectation) required for a measurement of coherent neutrino–nucleus scattering in a nuclear reactor experiment. First results are presented from its calibration using sub-kiloelectronvolt nuclear recoils similar to those expected from reactor antineutrinos or light WIMPs (weakly interacting massive particles) beyond the reach of present detectors. The device hybridizes the mass and energy resolution of a conventional HPGe coaxial gamma spectrometer with the low electronic noise and threshold of a small x-ray semiconductor detector, also displaying an intrinsic ability to distinguish multiple-site from single-site particle interactions. The present performance of the prototype and possible further improvements are discussed, as well as other applications for this new type of device in neutrino and astroparticle physics (double-beta decay, neutrino magnetic moment and novel WIMP searches).

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Large-mass ultralow noise germanium detectors: performance and applications in neutrino and astroparticle physics

Charge-coupled device (CCD) area x-ray detector technology is reviewed. CCD detectors consist of a serial chain of signal components, such as phosphors, fiber optics or lenses, image intensifiers and the CCD which serve to convert the x-ray energy to light or electron-hole pairs and to record the spatially resolved image. The various combinations of components that have been used to make CCD detectors are described and the properties of each of the critical components are discussed. Calibration and correction procedures required for accurate data collection are described. The review closes with a brief description of future directions for solid-state area x-ray detectors.

Charge-coupled device area x-ray detectors

Silicon Drift Detectors (SDDs) combine a large sensitive area with a small value of the output capacitance and are therefore well suited for high resolution, high count rate X-ray spectroscopy. The low leakage current level obtained by the elaborated processing technology makes it possible to operate them at room temperature or with moderate cooling. A brief description of the device principle is followed by the presentation of first results of a new production of large area SDDs with external electronics. Performance and applications of the already established SDDs with on-chip amplification are summarised. Various shapes of Multichannel Drift Detectors are introduced as well as their use in new experiments like X-ray holography and in new systems like an Anger camera for γ-ray imaging.

Silicon drift detectors for high count rate X-ray spectroscopy at room temperature

A new detector-amplification principle proposed by Kemmer and Lutz in 1986 has been experimentally verified. Outstanding features of this device are the built-in amplification, the signal charge storage capability and the possibility of repeated non-destructive readout. The device was used for detection of X-rays from a 241 Am and from Am and from an 55 Fe source. Very low noise figures ( σ =30 electrons corresponding to an energy resolution of FWHM = 250 eV at 6 keV energy) have been obtained at room temperature. Various applications of the structure either as detector or as purely electronic element are possible. One of the most intriguing is the use as a pixel detector with random access non-destructive readout. This device may be operated at very low power, as only reading (of one single pixel at a time), not storing, consumes power. Further options of the device are fast clearing, gating and variation of the pixel size during readout. The latter property can be used to drastically increase the readout speed compared to more standard two dimensional devices as e.g. CCD detectors, as one may restrict the high density readout to regions of interest determined beforehand by a coarse scan of the whole detector. An alternative use of the device is as an analog or digital memory, or as a simple transistor with drastically reduced parasitic capacitances. Possible further developments are the combination with a novel three dimensional analog storage device which may either be used as a detector with built-in storage of several charge images or as a three dimensional analog memory.

Experimental confirmation of a new semiconductor detector principle

Based on the drift chamber principle a low capacity diode has been built with one large area p+n junction at the front, and p+ and n+ patterns at the rear. The capacitance of the device is only 1.5 pF at an area of 1 cm2 and a thickness of 280 μm. The energy resolution for Am α-particles is 13.5 keV, the optical sensitivity is homogeneous over the whole area, and the charge collection times lie between 10 and 300 ns.

Low capacity drift diode

A novel biasing concept made it possible to implement capacitive coupling in a double-sided silicon strip detector system with a relatively simple production process. Capacitive coupling eliminates the problem of electronic readout saturation caused by leaky strips. This advantage is of particular value for the n-side, where a current caused by differences in the input voltage levels of the readout electronics could make any measurements impossible. Double-sided readout increases the position information and is advantageous for use in detector systems where compactness and minimization of scattering material are important. Static measurements have confirmed all the principal performance properties of the device. Further tests were performed in the readout electronics environment of the ALEPH minivertex detector under laboratory and operating conditions in a test beam at the CERN SPS and have confirmed the detector's performance. >

A double-sided silicon strip detector with capacitive readout and a new method of integrated bias coupling

An advanced large-area silicon photodiode and X-ray detector, called the spiral drift detector, was designed, produced, and tested. The detector has a very small capacitance of about 0.1 pF and a leakage current under 1 nA at room temperature. All electrons generated at the silicon-silicon oxide interface are collected on a guard rather than contributing to the detector leakage current. The decrease of the leakage current reduces the parallel noise of the detector. This decrease and the very small capacitance of the detector anode with a capacitively matched preamplifier may improve the energy resolution of spiral drift detectors operating at room temperature to about 50 electrons RMS. This resolution is in the range attainable at present only by cooled semiconductor detectors. >

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Spiral silicon drift detectors

MAXI (MPI/AIT X-ray Imager) is part of a proposal submitted to the European Space Agency (ESA) as focal plane instrumentation of the X-ray Multi Mirror Mission (XMM). Within a collaboration of 13 European institutes we have proposed a fully depleted (sensitive) pn CCD of 280 μm thickness with a homogeneous sensitive area of 36 cm2 and a pixel size of 150×150 μm2 which is well matched with the telescope's angular resolution of 30 arcsec translating to a position resolution of approximately 1 mm in the focal plane. The X-ray sensitivity will be higher than 90% from 250 eV up to 10 keV, the readout time in the full frame mode of the complete focal plane will be 2 ms with a readout noise of better than 5 e− (rms). Prototypes of all individual components of the camera system have been fabricated and tested. The camera concept will be presented. The measured transfer properties of the CCD and the on-chip electronics will be treated. Taking into account the coupling of the on-chip amplifier to the following front-end electronics the expected performance will be derived.

U. Prechtel

Papers

Experimental confirmation of a new semiconductor detector principle

Low capacity drift diode

A double-sided silicon strip detector with capacitive readout and a new method of integrated bias coupling

Spiral silicon drift detectors

The MPI/AIT X-ray imager (MAXI) — High speed pn CCDs for X-ray detection