46 research outputs found
Sub-Electron noise measurements on RNDR Devices
No full textIn this work we demonstrate theoretically and experimentally the capability to reduce the readout noise of an optical and X-ray photon detector based on the semiconductor DEPFET device below a level of only 0.3e(-) ENC (equivalent noise charge). The readout method used is called "Repetitive Non Destructive Readout" (RNDR) and was realised by placing two single DEPFET-devices next to each other and by coupling their charge storing region by an additional gate. By transferring the stored charge from one DEPFET to the other and vice versa the same charge can be measured non-destructively and arbitrarily often. Taking the average value of a large number n of these measurements, the noise is reduced by 1/root n. The main advantage of such a detector is to greatly reduce the influence of the 1/f noise to the readout noise. The theoretically and experimentally achievable resolution for different operating parameters (leakage current, readout noise, number and duration of readouts) was investigated by Monte-Carlo simulations and verified on a real RNDR minimatrix (pixelarray). Single optical photon detection with high quantum efficiency and, even more fascinating, the possibility to distinguish between different numbers of photons e. g. 100 from 101 is presented in measurements
DEPFET detector-amplifier structure: Properties, achievements and new developments, concepts and applications
No full textThe DEPFET detector-amplifier structure invented 1985 by J. Kemmer and G. Lutz possesses several unique properties which make it extremely interesting as readout element in semiconductor detectors and in particular as building block of semiconductor pixel detectors.DEPFET Detectors of various kinds have been built at the MPI Semiconductor Laboratory in Munich with its high quality double sided silicon processing line. These devices include DEPFET pixel detectors to be used in two X-ray astronomy missions and a RNDR (Repeated Non Destructive Readout) structure which allowed to measure the signal charge with a precision of a quarter of the elementary charge. A common property of these detectors is the simultaneous measurement of position and energy of X-ray photons (Spectroscopic Imaging).Presented for the first time are pixel devices which allow selection of signal charges arriving in a predefined time interval. Charges produced outside this gate interval are lead to a sink electrode. Furthermore the selected charge can be stored for delayed readout. These devices are for example well suited for application in the field of adaptive optics. Another new concept is that of a DEPFET with stongly nonlinear device characteristics that allows to combine high resolution charge measurement with large dynamic range. It will be used for application at the new X-ray sources, the free electron laser XFEL
Compton electrons' tracking within a single silicon layer with controlled-drift detectors
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ASTEROID: a new 64 channel ASIC for source follower based readout of the MIXS DEPFET arrays on BepiColombo
No full textASTEROID is a new 64 channel ASIC developed to read out a DEPFET macropixel array. This sensor will be part of the MIXS instrument that will be used in the ESA's BepiColombo Mercury exploration mission. The detector will operate in an environment with high density of solar proton flux that will cause severe radiation damage and an increase of leakage current during mission lifetime. Given the relatively high value of the leakage current, a high speed readout and a proper cooling of the detector is needed in order to achieve the required energy resolution. The contribution of the readout electronics to the noise should be smaller than 10 electrons r.m.s. The foreseen pixel arrays are optimized for source follower readout. In this operating mode of the DEPFETs, the readout electronics is AC-coupled. This allows easy coping with non homogeneity of the pixel matrix and - most of all - an easy compensation of threshold voltage shifts of the DEPFET devices due to radiation damage. In order to achieve the low noise value required at short processing time, ASTEROID implements a trapezoidal weighting function, which represents the time-limited optimum filter for white series noise. This is the major electronics noise source at the foreseen readout speed. Measurements on a first prototype of the ASIC have shown the very satisfactory resolution of 147 eV on Mn-K alpha peak of Fe-55 with a readout time of approximately 1.2 mu s, that would lead, considering the settling time of the DEPFET, to a total processing time of 4.2 mu s. We present the experimental results of a first prototype that includes 4 analog channels and a new digital section for the generation of the timing signals of the circuit. This digital section is based on radiation-hardened dual-port memory cells and registers and has already been implemented to serve all the 64 channels foreseen for the final version of the ASIC
XEUS wide-field imager: first experimental results with the X-ray active pixel sensor DEPFET
No full textA new type of Active Pixel Sensor is proposed which will be capable to meet the requirements of the wide field imager
of ESAs future X-ray mission XEUS: the simultaneous energy and position resolved detection of X-rays at high count
rate on a large format sensor. The Active Pixel Sensor is based on the integrated detector-amplifier structure DEpleted
P-channel Field Effect Transistor (DEPFET). The device operates on a fully depleted bulk and provides internal signal
amplification at the position of the charge generation. A very low value of the overall output capacitance leads to
extremely low read noise. In the matrix arrangement of an Active Pixel Sensor the single DEPFET pixels can be
randomly accessed for readout, and various flexible readout modes are possible. In contrast to CCDs the DEPFET-based
Active Pixel Sensor avoids the transfer of signal charges over long distances within the detector bulk, and related
problems of transfer loss or out-of-time-events cannot occur. An interesting feature is the non-destructive nature of the
DEPFET readout which can be used for the reduction of the low-frequency noise contribution by repetitive readings of
the signal information. The device principle of the DEPFET based pixel sensor is explained. First results of single
DEPFET measurements are presented
A new XRF spectrometer based on a ring-shaped multi-element silicon drift detector and on X-ray capillary optics
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