Search

Belle II DEPFET, PXD, and SVD Collaborations: et al., The Belle II experiment comes with a substantial upgrade of the Belle detector and will operate at the SuperKEKB energy-asymmetric ee collider with energies tuned to ϒ(4S) resonance s=10.588 GeV. The accelerator has successfully completed the first phase of commissioning in 2016 and the first electron–positron collisions in Belle II took place in April 2018. Belle II features a newly designed silicon vertex detector based on DEPFET pixel and double-sided strip layers. Currently, a subset of the vertex detector is installed (Phase 2 of the experiment). Installation of the full detector (Phase 3) will be completed by the end of 2018. This paper describes the Phase 2 arrangement of the Belle II silicon vertex detector, with focus on the interconnection of detectors and their integration with the software framework of Belle II. Alignment issues are discussed based on detector simulations and first acquired data., This work is supported by MSCA-RISE, European Union project JENNIFER (EU grant n. 644294), MEXT, Japan, WPI, and JSPS (Japan); ARC (Australia); BMWFW (Austria); MSMT, Czech Republic, GAUK 404316 (Czech Republic); AIDA-2020 (Germany); DAE, India and DST (India); INFN (Italy); NRF-2016K1A3A7A09005605 and RSRI (Korea); MNiSW (Poland); Federal Ministry of Education and Research (BMBF, Germany); and MINECO, Spain grant FPA2015-71292-C2-1-P (Spain).

Belle-II DEPFET and PXD Collaboration: et al., The Belle II experiment at the SuperKEKB energy-asymmetric e+ e- collider has completed a series of substantial upgrades and started collecting data in 2019. The experiment is expected to accumulate a data set of 50 ab−1 to explore new physics beyond the Standard Model at the intensity frontier. The pixel detector (PXD) of Belle II plays a key role in vertex determination. It has been developed using the DEpleted P-channel Field Effect Transistor (DEPFET) technology, which combines low power consumption in the active pixel area and low intrinsic noise with a very small material budget. In this paper, commissioning and performance of the PXD measured with first collision data are presented., This work is supported by MEXT, Japan, WPI, Japan, and JSPS (Japan); MSMT, GAUK 404316, MSCA-RISE project JENNIFER-2 (EU grant n. 822070) (Czech Republic); Federal Ministry of Education and Research (BMBF, Germany) and MINECO, Spain grant FPA2015-71292-C2-1-P (Spain).

Belle-II DEPFET and PXD Collaboration: et al., A DEpleted P-channel Field Effect Transistor (DEPFET) based pixel detector was developed for the Belle II VerteX Detector (VXD). It is designed to achieve a good impact parameter resolution better than 15𝜇m at the very high luminosity conditions of this experiment. In the first half of 2018 four final production modules have been deployed in the commissioning run of the detector and their performance is discussed., This work is supported by MEXT, WPI, and JSPS (Japan); MSMT, GAUK 404316, MSCA-RISE project JENNIFER (EU grant n. 644294) (Czech Republic); Federal Ministry of Education and Research (BMBF, Germany) and MINECO grant FPA2015-71292-C2-1-P (Spain).

Silicon Photomultipliers (SiPMs) are a promising candidate for replacing conventional photomultiplier tubes (PMTs) in many applications, thanks to ongoing developments and advances in their technology. Conventional SiPMs are generally an array of avalanche photo diodes, operated in Geiger mode and read out in parallel, thus leading to the necessity of a high ohmic quenching resistor. This resistor enables passive quenching and is usually located on top of the array, limiting the fill factor of the device. In this paper, a novel detector concept with a bulk integrated quenching resistor will be recapped. In addition, due to other advantages of this novel detector design, a new concept, in which these devices will be utilized as tracking detectors for particle physics applications will be introduced, as well as first simulation studies and experimental measurements of this new approach.

In the upgrade of the Belle detector at KEK (Tsukuba, Japan) the two innermost layers of the vertex detector will be realized by a pixel detector (PXD) consisting of DEPFET (DEpleted P-channel Field Effect Transistor) matrices. As the position of the detector will be very close to the beam pipe, it will suffer from intense radiation levels. The main radiation background is the luminosity related 4-fermion final state radiation, which damages the silicon bulk material and the silicon dioxide from the gate contacts. With the dose expected at Belle II, the DEPFET suffers mainly from additional leakage current and increase in noise. In addition, defects in the silicon dioxide change transistor parameters, e.g. the threshold voltage. We will show results on the hardness factor of electrons after a 10 MeV electron irradiation which was performed in the dose and energy range relevant for the PXD. In addition, we present X-ray irradiations of DEPFET equivalent test structures and compare radiation hardness for different oxide parameters in the prototype production.

We present a new high resolution X-ray imager based on a pnCCD detector and a polycapillary optics. The properties of the pnCCD like high quantum efficiency, high energy resolution and radiation hardness are maintained, while color corrected polycapillary lenses are used to direct the fluorescence photons from every spot on a sample to a corresponding pixel on the detector. The camera is sensitive to photons from 3 to 40 keV with still 30% quantum efficiency at 20 keV. The pnCCD is operated in split frame mode allowing a high frame rate of 400 Hz with an energy resolution of 152 eV for Mn K α (5.9 keV) at 450 kcps. In single-photon counting mode (SPC), the time, energy and position of every fluorescence photon is recorded for every frame. A dedicated software enables the visualization of the elements distribution in real time without the need of post-processing the data. A description of the key components including detector, X-ray optics and camera is given. First experiments show the capability of the camera to perform fast full-field X-Ray Fluorescence (FF-XRF) for element analysis. The imaging performance with a magnifying optics (3×) has also been successfully tested.

Focal plane instrumentation based on DEPFET Macropixel devices, being a combination of the Detector– Amplifier structure DEPFET with a silicon drift chamber (SDD), has been proposed for the MIXS (Mercury Imaging X-ray Spectrometer) instrument on ESA’s Mercury exploration mission BepiColombo. MIXS images X-ray fluorescent radiation from the Mercury surface with a lightweight X-ray mirror system on the focal plane detector to measure the spatially resolved element abundance in Mercury’s crust. The sensor needs to have an energy resolution better than 200 eV FWHM at 1 keV and is required to cover an energy range from 0.5 to 10 keV, for a pixel size of 300 � 300 mm 2. Main challenges for the instrument are radiation damage and the difficult thermal environment in the mercury orbit. The production of the first batch of flight devices has been finished at the MPI semiconductor laboratory. Prototype modules have been assembled to verify the electrical properties of the devices; selected results are presented here. The prototype devices, Macropixel prototypes for the SIMBOL-X focal plane, are electrically fully compatible, but have a pixel size of 0.5 � 0.5 mm 2 . Excellent homogeneity and near

The company PNSensor and the MPI Semiconductor Laboratory are developing and have produced first prototypes of pnCCDs with an avalanche readout which aim at single photon sensitivity in the visible wavelength range. This resolution is provided by an avalanche diode integrated in the readout chain of every CCD column. The diode features a new topology and can collect signal electrons from the CCDs’ depleted buried channel. The pixel-structure has been derived from pnCCDs and was optimized for lowest leakage current and for compatibility with the avalanche structures. All advantages of the pnCCDs are maintained, including high quantum efficiency (between 80% and 100%), high frame rate (up to 1000 frames/s) and low leakage current. Possible applications are in the field of High Time Resolution Astrophysics (HTRA). There, fast imaging of faint objects in the visible, such as, e.g. close binary stars or fast rotating neutron stars, requires single photon sensitivity and high frame rates. We present results from proof-of-principle tests carried out on first laboratory prototypes of such devices.

To expand the detection efficiency Silicon Drift Detectors (SDDs) with various customized radiation entrance windows, optimized detector areas and geometries have been developed. Optimum values for energy resolution, peak to background ratio (P/B) and high count rate capability support the development. Detailed results on sensors optimized for light element detection down to Boron or even lower will be reported. New developments for detecting medium and high X-ray energies by increasing the effective detector thickness will be presented. Gamma-ray detectors consisting of a SDD coupled to scintillators like CsI(Tl) and LaBr3(Ce) have been examined. Results of the energy resolution for the 137Cs 662 keV line and the light yield (LY) of such detector systems will be reported.

The Depleted Field Effect Transistor (DEPFET) detector–amplifier structure forms the basis of a variety of detectors being developed at the MPI semiconductor laboratory. These detectors are foreseen to be used in astronomy and particle physics as well as other fields of science. The detector developments are described together with some intended applications. They comprise the X-ray astronomy missions XEUS and SIMBOL-X as well as the vertex detector of the planned International Linear Collider (ILC). All detectors are produced in the MPI semiconductor laboratory that has a complete silicon technology available.

A special type of charge-coupled device, the pnCCD, has been developed in the nineties as focal-plane detector for the X-ray astronomy mission XMM-Newton of the European Space Agency. The pnCCD detector has been in operation since the satellite launch in 1999. It is performing up to date spectroscopy of X-rays in combination with imaging and high time resolution. The excellent performance of the flight camera is still maintained; in particular, the energy resolution has been nearly constant since launch. In order to satisfy the requirements of future X-ray astronomy missions as well as those of ground-based experiments, a new type of pnCCD has been developed. The ‘frame store pnCCD’ shows various optimizations in device design and fabrication process. Devices with up to 256×512 pixels have been fabricated in 2004 and recently tested. Simultaneously, a programmable analog signal processor for the readout of the CCD signals, the DUO CAMEX, has been developed. The readout noise of the new detector has a value of 2 electrons ENC which is less than half of the figure of the XMM-Newton pnCCD. We measured an energy resolution that is close to the theoretical limit given by the Fano noise. In particular the low-energy response of the new devices was substantially improved. The quantum efficiency for X-rays is at least 90% in the entire energy band from 0.3 keV up to 11 keV. This is due to the ultra-thin photon entrance window as well as the full depletion of the 450 μm thick back-illuminated pnCCD. The position resolution is better than the pixel sizes of 75 μm×75 μm or 51 μm×51 μm because the signal charge is spread over up to four pixels which allows a more accurate event position determination. ‘Out of time’ events are substantially reduced to the order of 0.1% by operating the pnCCD in frame store mode. Higher operating temperatures, e.g. −20 °C, are possible due to the smaller thermally generated dark-current level of the new devices and the operation at higher frame rates. Low power consumption applications like for the ROSITA X-ray astronomy mission with low frame rates of, e.g. 20 images/s, as well as high frame rate applications, e.g. 200 images/s, are possible with the same device.

The performance requirements of vertex detectors for future linear collider experiments is very challenging especially for the detector's innermost sensor layers. The DEPleted Field Effect Transistor (DEPFET) combining detector and amplifier operation is capable to meet these requirements. A silicon technology is presented which allows production of large sensor arrays consisting of linear DEPFET detector structures. The envisaged pixel array offers a low noise and low power operation. To ensure a high radiation length a thinning technology based on direct wafer bonding is proposed.

Future x-ray observatories, such as the proposed ATHENA+ mission, will investigate bright and rapidly evolving radiation sources. To reach the scientific goals, high speed, spatial resolving sensors with excellent spectroscopic performance are mandatory. Well suited for this task are matrices of Depleted P-channel Field Effect Transistors (DEPFETs). DEPFETs provide intrinsic signal amplification, 100 percent fill factor, charge storage capability and a low read noise. Previous studies of DEPFET matrices of 256 × 256 pixels demonstrated an excellent energy resolution of 126 eV FWHM at 5.9 keV (compared to the theoretical Fano limit 120 eV). Usually these matrices are read out on demand, using e.g. the ASTEROID ASIC. Because the DEPFET is always sensitive, charge collected during the readout, causes so called misfits, which increase the background. For low frame rates this can be neglected. However, for fast timings, as suggested for ATHENA+, this effect reduces the spectral performance. We will present measurements on DEPFET macropixel structures, read out using a semi-Gaussian shaper, which demonstrate the excellent spectroscopic performance of these devices. Furthermore we will investigate the effect of misfits on the spectral background of DEPFET devices read out on demand. These measurements show the necessity to suppress misfits when the devices are operated for fast timing modes. As will be shown this can be done using so called gateable DEPFETs. The general advantage of gateable DEPFETs at fast timings, in terms of peak-to-background ratio will be demonstrated.

Development of high quantum efficiency photon detectors is needed for many low light level (LLL) applications. Recently a new type of photodetector was introduced, the so-called Silicon PhotoMultiplier (SiPM). Its good characteristics (fast response, high gain and single photon resolution capability) make SiPM suitable for many applications. Yet its quantum efficiency is still not satisfactory ( 40 % ) for LLL applications. A new detector concept is presented that promises very high ( > 80 % ) quantum efficiency in a wide wavelength range (300–1000 nm). Combining the drift diode with an avalanche structure placed on the opposite side of the large-area radiation entrance window on the fully depleted bulk, one obtains a large-area device that focuses the photoelectron onto a small “point-like” avalanche region. Engineering of the shallow radiation entrance window provides high quantum efficiency in the desired wavelength range. Such a device can be used as a building block for a “silicon photomultiplier”. Extensive simulations have demonstrated the validity of this concept. A production of test devices for the optimization and characterization of avalanche regions and technology parameters has been carried out. The first results from this “proof of principle” production are presented.

The International X-ray Observatory (IXO) will be a joint X-ray observatory mission by ESA, NASA and JAXA. It will have a large effective area (3 m 2 at 1.25 keV) grazing incidence mirror system with good angular resolution (5 arcsec at 0.1–10 keV) and will feature a comprehensive suite of scientific instruments: an X-ray Microcalorimeter Spectrometer, a High Time Resolution Spectrometer, an X-ray Polarimeter, an X-ray Grating Spectrometer, a Hard X-ray Imager and a Wide-Field Imager. The Wide Field Imager (WFI) has a field-of-view of 18 ft � 18 ft. It will be sensitive between 0.1 and 15 keV, offer the full angular resolution of the mirrors and good energy resolution. The WFI will be implemented as a 6 in. wafer-scale monolithical array of 1024 � 1024 pixels of 100 � 100mm 2 size. The DEpleted P-channel Field-Effect Transistors (DEPFET) forming the individual pixels are devices combining the functionalities of both detector and amplifier. Signal electrons are collected in a potential well below the transistor’s gate, modulating the transistor current. Even when the device is powered off, the signal charge is collected and kept in the potential well below the gate until it is explicitly cleared. This makes flexible and fast readout modes possible.

Minimization of the total detector capacitance due the small area readout node on one hand and to the integration of the front-end FET directly onto the detector (see Fig. 1a) on the other hand, combined with an ultra-low leakage current process makes the SDD with integrated FET an excellent energy resolving device with measured energy resolution down to 123 eV for Mn-Kα line at moderate temperatures (easily reached with Peltier cooling, e.g. -20°C) and very short shaping times 0.5 to 1 μs. These are performance values which can not be achieved by any other EDS detector.

The need of high quality spectroscopic semiconductor imaging detectors in X-ray astronomy was the principal driving force in founding the MPI Semiconductor Laboratory. Detectors developed in this laboratory are based on new function principles and are processed in the silicon detector processing line established within the laboratory. We describe the development of pnCCDs as already used in the XMM-Newton European X-ray observatory and foreseen for eROSITA, the DEPFET based pixel detector for XEUS and a new development which makes it possible to measure charge with a precision below one elementary charge. A noise value of 0.25 electron r.m.s. has already been reached.

The Belle II detector is a system currently under upgrade at the B-factory SuperKEKB in Tsukuba, Japan. The main novelty is the introduction of an additional position sensitive sub-detector in the vertex detector, between the beam pipe and the strip detector system. The sensor of choice for the Belle II Pixel Detector is the Depleted p-channel Field Effect Transistor (DEPFET) sensor. In this paper the latest production of sensors and prototypes performed at the semiconductor Laboratory of the Max Planck Society, i.e. the PXD9 and the Electrical Multi-Chip Module (EMCM), are described. Wafer-level characterisation methods and techniques for faults in the metal system are also reported.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

For the future X-ray astronomy project Advanced Telescope for High ENergy Astrophysics plus (ATHENA+) wafer-scale DEpleted P-channel Field Effect Transistor (DEPFET) detectors are proposed as Focal Plane Array (FPA) for the Wide Field Imager (WFI). Prototype structures with different pixel layouts, each consisting of 64 x 64 pixels, were fabricated to study four different DEPFET designs. We report on the results of the electrical characterization of the different DEPFET designs. The transistor properties of the DEPFET structures are investigated in order to determine whether the design intentions are reflected in the transistor characteristics. In addition yield and homogeneity of the prototypes can be studied on die, wafer and batch level for further improvement of the production technology with regard to wafer-scale devices. These electrical characterization measurements prove to be a reliable tool to pre-select the best detector dies for further integration into full detector systems.

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008

Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

The semiconductor laboratory of the Max-Planck-Institutes for physics and for extraterrestrial physics develops and fabricates silicon sensors for scientific experiments in astronomy and highenergy physics, as well as for industrial applications. Among them are state-of-the-art detectors for X-ray imaging and spectroscopy. Their common features are the integration of the readout electronics on the detector chip and a fully depleted bulk with a non-structured thin entrance window, guaranteeing excellent energy resolution and high quantum efficiency over a wide energy range. Fully depleted and backside illuminated Charge Coupled Devices (pn-CCDs) have been developed and are operated successfully as focal plane detector of the XMM-Newton satellite. They have a sensitive area of 6 x 6 cm≤ with a pixel size of 150 x 150 µm≤, an equivalent noise charge of 4 el. rms. operating at 150 K, and an ultra-fast full frame readout time of 4.5 msec. The integrated detector-preamplifier structure DEPFET (DEpleted P-channel Field Effect Transistor) is the basic element of an Active Pixel Sensor (APS) with random accessible pixels, flexible readout modes, and the potential for repetitive non-destructive readout with subelectron resolution. Spectroscopy measurements of single DEPFET structures demonstrate an unequalled electronic noise of 2.2 el. rms at room temperature.