Search

Abstract: The new DSSC (DEPFET sensor with signal compression) detector system is being developed in order to fulfil the requirements of the future XFEL in Hamburg. The instrument will be able to record X-ray images with a maximum frame rate of 5MHz and to achieve a high dynamic range. The system is based on a silicon pixel sensor with a new designed non-linear-DEPFET as a central amplifier structure. The detector chip is bump-bonded to mixed signal readout ASICs that provide full parallel readout and temporary data storage. The signals coming from the detector are processed by an analog filter, immediately digitized by 8-ENOB ADCs and locally stored in a custom designed memory. The ASICs are designed in 130nm CMOS technology. During the time gap of 99ms of the XFEL machine, the digital data are sent off the focal plane to a DAQ electronics that acts as an interface to the back-end of the whole instrument. The pixel sensor has been designed so as to combine high energy resolution at low signal charge with high dynamic range. This has been motivated by the desire to be able to be sensitive to single low energy photons and, at the same time, to measure at other positions of the detector signals corresponding to up to 104 photons of 1keV. In order to fit this dynamic range into a reasonable output signal swing, achieving at the same time single photon resolution, a strongly non-linear characteristic is required. The new proposed DEPFET provides the required dynamic range compression at the sensor level, considerably facilitating the task of the electronics. At the same time the DEPFET charge handling capacitance is enormously increased with respect to standard DEPFETs. The sensor matrix will comprise pixels of hexagonal shape with a side-length of . The simultaneous implementation of the 5MHz frame rate, of the single low-energy photon resolution and of the high dynamic range goes beyond all the existing instruments and requires the development of new concepts and technologies. [Copyright &y& Elsevier]

Abstract: We describe the hard X-ray scanning microscope planned for the new synchrotron radiation source PETRA III at DESY in Hamburg, Germany. It is based on nanofocusing refractive X-ray lenses and is designed for two-dimensional mapping and scanning tomography. It supports X-ray fluorescence and (coherent) diffraction contrast, yielding elemental and structural information from inside the sample. Spatial resolutions down to well below 50nm are aimed for in direct space. A further increase in spatial resolution is expected by applying ptychographic scanning schemes. The optical scheme with a two-stage focusing optic is described. [Copyright &y& Elsevier]

Abstract: Photoelectron spectroscopy at high kinetic energy is a research field that receives an increasing interest due to the possibility of studying bulk properties of materials and deeply buried interfaces. Recently the high kinetic energy electron (HIKE) spectroscopy facility at BESSY in Berlin has become operative at the bending magnet beamline KMC-1. The first results show very good performance. Electron spectra have been recorded using X-ray energies from 2keV up to 12keV. Using back-scattering conditions in the crystal monochromator, very high-resolution has been achieved for photon energies around 2, 6 and 8keV. In the latter case, spectra with a resolving power from the monochromator of ⩾80000 have been achieved and it has been possible to perform electron spectroscopy with resolving power of ⩾60000, yielding a total instrument resolution of about 150meV as determined directly from spectra. This paper describes the facility and reports some of the first results. [Copyright &y& Elsevier]

Microbeam radiotherapy is a novel type of radiotherapy in which narrow beams of radiation (typically less than 500 μ m) are spatially fractionated, delivering a non-uniform distribution to the target tumour volume. Due to the very high dose gradients and very small beams involved, new dosimetric techniques are required for translation into clinical practise. Current real-time beam monitoring is typically performed using 1 dimensional silicon strip detectors or wire chambers, with 2D beam information measured offline using radiochromic film (requiring a minimum of 24 h to self-develop). Using an Xstrahl SARRP X-ray​ irradiation device with a bespoke microbeam collimator at the Technical University of Munich, Germany, the newly developed vM1212 detector was exposed to a variety of microbeams (220 kV, nominal slit widths 0– 100 μ m) for evaluation of in vivo real time verification. The performance of the detector was assessed by changing the collimator slit width (and thus microbeam FWHM) mid-irradiation. Microbeam FWHMs of 130– 190 μ m could be measured in this manner in addition to temporally monitoring other basic parameters such as the radiation intensity. More advanced parameters could be calculated as the tungsten slits within the microbeam collimator opened and closed such as the rate of change of FWHM; the peak–valley-dose-ratio (PVDR); and the sub-pixel movement of each microbeam peak. This work demonstrates the potential of radiation hard CMOS sensors in radiotherapy for in vivo real-time monitoring of X-ray microbeams FWHM, intensity and position. [ABSTRACT FROM AUTHOR]