High-Z sensors in combination with charge-integrating, pixelated FEL detectors (#2054)
D. Greiffenberg1, A. Bergamaschi1, M. Brueckner1, E. Froejdh1, R. Dinapoli1, D. Mezza1, A. Mozzanica1, M. Ramilli1, S. Redford1, M. Ruat1, M. Andrä1, X. Shi1, G. Tinti1, J. Zhang1
1 Paul Scherrer Institut, SLS Detector Group, Villigen, Aargau, Switzerland
The Detector Group of the Swiss Light Source (SLS) at the Paul-Scherrer-Institute (PSI) has a long history of developing detectors for the needs of synchrotron sources. The advent of XFELs (like SwissFEL, which is constructed at PSI) has triggered the development of charge-integrating detectors with a high dynamic range of up to 104 . 12.4 keV photons per pixel. This high dynamic range per pixel has to be achieved without sacrificing single photon resolution in case of few incoming photons. Additionally the noise performance has to be better than the Poissonian fluctuations of the source at each point of the dynamic range to ensure the same data quality as single photon counting detectors. The SLS Detector Group has developed a novel method called dynamic gain switching, which is adapting the gain of each pixel to the incoming photon flux by dynamically adding additional capacitors into the feedback loop of the charge sensitive preamplifier. Meanwhile, several pixelated readout chips employing this technology have been developed, amongst others JUNGFRAU consisting of 256 x 256 pixels with a pixel pitch of 75 x 75 um2.
In parallel, the use of high-Z sensors (GaAs and CdTe) has been investigated in order to extend the usable range of photon energies of our detectors. Charge-integrating detectors offer interesting insights into the sensor properties as each pixel provides a direct measure of the collected charge of a well-defined area as output.
Over the last year during several beamtimes have been done (Swiss Light Source (SLS) and ESRF) to test the usability of high-Z sensor materials (GaAs and CdTe) in combination with our charge integrating readout chips. The experiments focused on how the detector system reacts to fast changes of the beam intensity as would occur at synchrotron/FEL experiments. First results of test systems will be shown.
Keywords: Pixel detector, JUNGFRAU, CdTe, GaAs, HighZ
Investigation of multi-threshold imaging with a CdTe-Medipix3RX (#2422)
S. Procz1, F. Fischer1, A. Fauler1, E. Hamann2, M. Fiederle1, 2
1 FMF University Freiburg, Freiburg, Germany
The high spatial resolution and high efficiency of photon counting detectors with semiconductor sensor materials like Si, GaAs or CdTe are able to improve the quality of medical examination methods. The energy-resolving capability of some photon counting detectors can deliver advanced information for medical investigations and further improve the image quality.
The pixelated photon counting semiconductor detector Medipix3RX features up to eight adjustable energy thresholds which allow simultaneous counting of incoming photons with dedicated energy for energy selective colored X-ray imaging. X-ray images acquired with such detectors provide additional material information over images acquired using conventional X-ray films or current-integrating detectors.
The estimated benefits from using multi channel energy selective X-ray imaging for bio-medical imaging are:
The combination of a Medipix3RX ASIC (55x55 µm² pixel pitch and 256x256 pixels) with a CdTe sensor was characterized for the energy threshold width, threshold stability, gain match and sensitivity for changes in the leakage current. Also energy selective colored X-ray of different objects were acquired in order to investigate the influence of energy selective X-ray imaging on image information and on image quality.
Keywords: Medipix spectroscopic imaging CdTe equalization
Palmtop Size Fully 3D Voxel Detector with 0.26 Mega Voxels and USB readout for Particle Tracking, Radiation Monitoring and Imaging (#3712)
J. Jakubek1, M. Jakubek1, P. Soukup1, D. Turecek1, S. Pospisil2
1 ADVACAM, Prague, Please choose ..., Czech Republic
The images of traces of various particle species recorded with old-style cloud or bubble chamber detectors are still used in most textbooks since they are very illustrative and explanatory. It was an old dream of many physicists to have a compact semiconductor based detector providing similar functionality. In this work we present a solution close to this goal: The palmtop size, miniaturized silicon tracker of potentially any number of layers of hybrid particle counting detectors in very tight (contact) geometry alternating semiconductor sensors and thin CMOS readout chips. The properties of such structure composed of 4 layers of Timepix detectors (4 x 256 x 256 voxels, each of 55 x 55 x 300 µm3) will be shown. Each layer consists of 300 µm thick silicon sensor bump-bonded to Timepix readout chip with thickness reduced to 100 µm. Very compact and tight design enables very broad field-of-view of almost 2π. Each detector voxel can be operated in Counting, Energy and/or Time-of-Arrival mode. The energy mode enables precise track reconstruction thanks to the charge sharing effect among pixels of each layer. The counting mode is useful for X-ray imaging. The total thickness of all four silicon sensors is 1.2 mm which improves detection efficiency for X-rays. The time mode is advantageous for techniques exploiting coincidence/anticoincidence or for Time-of-flight applications. Many results of device tests with various sources including X-rays, gamma rays (Am-241, Eu-152, Cs-137, Co-60), electrons, protons and cosmic rays will be shown. The first results with similar device but based on Timepix3 chip will be shown as well.
Keywords: Particle tracking, Timepix, Timepix3, Voxel detector, Pixel detector
CdZnTe Based Systems for Pixelated Imaging (#3406)
B. W. Harris1
1 eV Products division, Kromek USA, Applications and Device Design Department, Saxonburg, Pennsylvania, United States of America
on behalf of eV Products Inc./Kromek USA
CdZnTe based pixelated imaging systems developed at eV Products are described. New results are presented which demonstrate the functionality, utility, and limitations thereof.
Keywords: CdZnTe, pixelated, imaging, czt, SPECT, camera