Advances in Si detector speed, and novel applications.
Single Electron per Pixel Counting with Fully Depleted Chage Coupled Devices (#2436)
M. Sofo Haro1
1 Balseiro Institute, Bariloche Atomic Center / CNEA-CONICET, Bariloche, Rio Negro, Argentina
Scientific grade Charge Coupled Devices (CCDs) show attractive capabilities for the detection of particles with small energy deposition in matter. Here we present new developments on a novel readout technology known as Skipper-CCD that uses a readout stage that allows for multiple non-destructive sampling of the charge packets. These multiple samples can be averaged reducing the RMS of the noise with the square root of the number of samples taken. By averaging 4000 samples per pixel we are able to reach an unprecedented deep sub-electron noise of 0.06 e- RMS. This is the first time that discrete sub-electron readout noise has been achieved reproducibly over millions of pixels on a stable, large-area detector (A~7cm^2). We discuss the design aspects, clocking and electronic readout noise optimization of the device. As an immediate application of this technology we present the SENSEI experiment (Sub-Electron Noise SkipperCCD Experimental Instrument), a Direct-Detection dark matter search through the electron recoil channel. In addition to ultra low threshold particle detection, this device has a wide range of applications on celestial and laboratory spectroscopy, exoplanets searches and life science
Keywords: CCD, Low Noise, skipper ccd, single photon
Developments in the Production of Ultra-Fast Silicon Detectors (#3104)
M. Ferrero1, N. Cartiglia1, R. Arcidiacono3, 4, M. Boscardin5, G. Paternoster5, L. Pancheri3, M. Mandurrino1, F. Cenna1, A. Staiano1, R. Cirio2, 1, R. Sacchi2, 1, V. Monaco2, 1, G. - F. Dalla Betta3, S. Giordanengo1, A. Vignani1, F. Siviero2, V. Sola1, O. H. Ali2, M. Costa2, F. Ficorella5
1 INFN, Torino, Italy
The production of radiation hard Ultra-Fast Silicon Detectors (UFSD) represents a very important step in the development of the capapility of developing a tracker able to measure time and position of MIP particles. In this contribution we present the new production of UFSD at the Fondazione Bruno Kessler (Trento) where several radiation hardness techniques have been used. The production includes several different choices of dopant for the gain layer: Boron, Gallium, Boron and Carbon, and Gallium and Carbon. In the presentation we will show how these different choices determine the UFSD timing performance, and the result on radiation resistance.
Keywords: silicon, LGAD, UFSD, radiation hardness, timing
High speed imaging and spectroscopy of X-rays with deep subpixel (spatial) resolution (#2101)
L. Strueder1, 2, P. Holl1, S. Ihle3, D. Kalok1, D. Steigenhöfer3, H. Ryll1, R. Hartmann1
1 PNSensor, Innovative Radiation Detectors, Munich, Germany
We undertook an experimental study on optimizing the position accuracy of pnCCDs for single X-ray photon measurements. Even with low energy photons around 1 keV a position accuracy 20 times smaller than the actual pixel size of 48 μm was achieved. With a very low readout noise it is possible to reconstruct the original point of interaction since signal charges from a single photon interaction spread into more than one pixel. We found that a) making a decision on which pixels to use for the reconstruction and b) choosing a centroiding algorithm for carrying out the reconstruction were particularly crucial. For a) we introduce a new and superior method using a two-step analysis with an adaptive pattern. For b) we present a Center-of-Gravity method with a Gaussian correction taking into account the shape of the signal charge cloud. Our results show that with the appropriate analysis an uncertainty of the position measurement of better than 2.55 μm (rms) for 1320 eV photons is possible. The experimental verification was performed with an X-ray microscope at the BESSY synchrotron, delivering an X-ray spot on the pnCCD of 0.8 µm, scanning over a 3x3 pixel array with a step size of 3 µm. For 5.9 keV X-rays the simulated position accuracy is 0.88 µm. It turned out that the energy resolution is best when using the algorithms for the optimum spatial accuracy. This way a Fano limited spectroscopic silicon detector, read out with 1.000 frames per second and more than 4k x 4k resolution points was realized.
Keywords: X-ray imaging, X-ray spectroscopy, focal plane detector
EDET DH80K- A DEPFET based Ultra High Speed Camera System for TEM Direct Electron Imaging (#3178)
J. Treis1, L. Andricek1, I. Dourki2, S. Epp2, D. Gitaric2, C. Koffmane1, S. Krivokuca1, D. Miller2, J. Ninkovic1, I. Peric3, M. Predikaka1, E. Prinker1, R. H. Richter1, G. Schaller1, F. Schopper1, E. Tafelmayer1, A. Wassatsch1, F. Westermeier2, C. Zirr1
1 MPG Semiconductor Laboratory, Munich, Bavaria, Germany
We present a camera system for high time-resolved direct electron imaging on a TEM furnished with a pulsed electron source allowing to observe dynamic processes in real space with unprecedented spatial and temporal resolution. For optimized spatial resolution, the sensors use a SOI based detector substrate with 50 to 30 micron thickness. The high intensity of the electron source requires a nonlinear detector response to match the required high dynamic range. Detectors based on the DEPFET device were chosen, a detector concept with inherently high signal-to-noise level and high speed readout capability, whose response function was adapted to the requirement. In the focal plane, the area is covered by arrays of 512 x 512 pixels of 60 x 60 square micron size and a total area of about 3 x 3 cm2. Readout is coordinated by dedicated control ASICs and done in 4-row parallel rolling-shutter mode. The customized multichannel readout ASICs read a DEPFET row in 100 ns, so an entire pixel array is processed in 12.8 microseconds, i.e. a maximum source pulse frequency of 80 kHz. The readout ASICs directly digitize the pixel data with 8 bit, and the data is serialized and buffered by custom ICs with enough memory to buffer all data of a burst of 100 frames. In this way, stroboscopic movies can be recorded at a time resolution of 13 microseconds. The subsequent DAQ components permit a burst rate of > 10 bursts per second. For maximum integration density, the ASICs are bump bonded to the substrate of the detector array itself, which is provided with the corresponding metal track system to form an all-silicon-module (ASM). Each ASM is combined with mechanical support, electrical services and readout electronics. This so-called tile module is a completely independent subsystem. The focal plane will consist of four tile modules integrated on a common baseplate optimized for low background and thermal management within a customized vacuum box fitting all prevalent TEM types.
Keywords: DEPFET, TEM, Direct Electron Detection, High Speed, High Precision
iMPACT: innovative pCT scanner tracker and calorimeter prototyping (#2839)
P. Giubilato2, 1, S. Mattiazzo2, 3, N. Pozzobon2, 3, B. Di Ruzza2, 3, D. Pantano2, 3, M. Tessaro3, F. Baruffaldi2
1 CERN, EP division, Meyrin, Switzerland
This contribution describes the first results obtained within the iMPACT project, which aims to build a novel proton Computed Tomography (pCT) scanner for the energy range of 200-300 MeV. The scanner is designed to improve the current state of the art in proton tracking at all levels: speed, spatial resolution and material budget. Like present state-of-the-art systems, the iMPACT proton scanner consists of a tracker and a calorimeter.
The calorimeter is implemented as a range calorimeter, composed by planes made of scintillator fingers read by individual SiPM. Each plane has the scintillator fingers orthogonally oriented respect the ones in the adjacent planes, thus allowing to reconstruct the raw particle position. We will illustrate the result of testing the prototypes fingers and planes with protons of medical energy (200 to 300 MeV) at the TIFPA beamline at the ATREP center in Trento, and discuss the readout solutions adopted to meet the target overall speed.
The tracker concept, which will employ Monolithic Active Pixel Sensors (MAPS), has been prototyped using currently available ALPIDE sensor, a MAPS developed by the ALICE collaboration, which has been characterized in the same beamline used for the calorimeter. Illustration of the results obtained by using MAPS for tracking protons of medical energy (highly ionizing) and the effects of the sensor back-bias will be the focus of the second part of the contribution.
Reported beam-test data will highlight how the technological choices made can meet the target performance of the proposed state-of-the-art pCT system.
Keywords: pCT, MAPS, hadron therapy, calorimetry
Si/CdTe semiconductor Compton cameras with electron-tracking based imaging (#2069)
S. Watanabe1, 2, H. Yoneda1, 2, S. Saito1, 3, H. Ikeda1, T. Takahashi1, 2, S. Takeda4, 1
1 Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, Sagamihara, Kanagawa, Japan
We have developed novel Si/CdTe semiconductor Compton cameras, which have a capability to detect recoil electron trajectories. One approach for further effective Compton imaging is to detect directions of Compton recoil electrons, and, this information leads to fully Compton event reconstruction. In order to detect electron trajectories and determine directions of recoil electrons, finer position resolution is required. In addition to having a fine position resolution, the detector should have a capability to provide a trigger timing with a resolution of about one micro second for a Compton coincidence. To achieve such detectors, we have been developing Si-CMOS hybrid detectors. In the Si-CMOS hybrid detector, a double-sided Si device is used. On one side of the device, 20 micron pitch pixel electrodes are formed, and are bump-bonded to a CMOS signal processing circuit. On the other side, strip electrodes are implemented, and, are connected to readout LSIs developed for strip detectors. The CMOS signal processing circuit can detect the electron trajectories, and, a trigger timing can be obtained from the strip side. Energy deposit information is obtained from the both sides. We constructed a prototype Si/CdTe Compton camera using the Si-CMOS hybrid detector and a CdTe double-sided strip detector, and, we demonstrated fully Compton reconstruction with the prototype. We confirmed that noises in Compton reconstruction images are distinctly reduced by using the recoil electron information. In this paper, we describe the concept of the newly developed Si detectors for Compton cameras, which can detect electron trajectories, and present the results from the prototype Compton camera. We also discuss sub-mm spatial resolution imaging for a near field by using the Compton camera.
Keywords: Compton camera, Si semiconductor detector, CdTe semiconductor detector, electron-tracking