In September 2008 the SLIM5 collaboration submitted a low material budget silicon demonstrator to test with 12
GeV/
c protons, at the PS-T9 test-beam at CERN. Two different detectors were placed as ...DUTs inside a high-resolution and fast-readout beam telescope. The first DUT was a high resistivity double sided silicon detector, with short strips (“striplets”) and with reduced thickness, at
45
∘
angle to the detector's edge, readout by the data-driven FSSR2 chip. The other one was a 4k-Pixel Matrix of Deep N Well MAPS, developed in a 130
nm CMOS Technology, providing digital sparsified readout. In the following, I present the striplets and also the beam telescope characteristics, with some details about the frontend readout (based on the FSSR2 chip) and some preliminary results of the data-analysis.
We report on further developments of our proposed design approach for a full in-pixel signal processing chain of deep N-well monolithic active pixel sensor, by exploiting the triple well option of a ...CMOS 130
nm process. Two different geometries of the collecting electrode (namely “Apsel 3
T
1
M
1” and “Apsel 3
T
1
M
2”) was implemented to compare their charge collection efficiency. The results of the characterization of the various versions of pixel matrices with a pion beam of 120
GeV/
c at the SPS H6 CERN facility will be presented. The performances of an “Apsel 3
T
1” chip irradiated with a dose up to 10
Mrad (Co
60) was also measured. Comparison will be presented among the irradiated and the new chip showing the impact of radiation damages on tracking efficiencies.
The high rate data acquisition system for the SLIM5 beam test Fabbri, L.; Bruschi, M.; Di Sipio, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
In September 2008 the Slim5 collaboration submitted a low material budget silicon demonstrator to test with protons at the PS beam at CERN. The beam test setup was composed of a four double sided ...microstrip reference telescope and different detectors (DUTs) placed inside: a 4k-Pixel Matrix of Deep N Well MAPS, developed in a 130
nm CMOS Technology and a high resistivity double sided silicon detector, with short strips at
45
∘
angle to the detectors edge, read out by the FSSR2 chip. All the systems were self-triggered and read out by a fast DAQ system. In the poster the beam test setup as the data acquisition and the trigger system are explained and the data acquisition performances are shown.
The Belle II experiment is evaluating an upgrade program aiming at the time frame 2026–2027 for the installation of the upgraded detectors, to improve the detector performance and robustness against ...beam-induced backgrounds. The VTX concept, a fully-pixelated system based on depleted monolithic active pixel sensors, has been developed as a replacement of the current pixel-and-strip vertex detector. A simulation framework for the VTX has been developed and integrated with the standard Belle II simulation, facilitating the comparison among different layouts. Simulation results (such as tracking efficiency and vertex resolution) on benchmark physics channels are presented, showing a significant improvement with respect to the current detector.
Development of graphene-based ionizing radiation sensors Batignani, G.; Bettarini, S.; Borghi, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2019, Letnik:
936
Journal Article
Recenzirano
We present the first steps to develop radiation sensors based on the graphene field effect transistor technology. Such a sensor exploits the ambipolar behavior of graphene near its Dirac point and it ...is not dependent on collecting charges, but it senses ionizing radiation trough the change in conductivity of the graphene layer induced by changes of the electric field. We designed the layout of the sensors with the help of Sentaurs TCAD. We simulated static operations and the dynamic response to radiation and calculated the source–drain current through the graphene layer with a quasi-analytical model. The transistors were produced at the National Enterprise for nanoScience and nanoTechnology by depositing high quality graphene on silicon chips manufactured by the Fondazione Bruno Kessler foundry. To reduce the high contact resistance between graphene and aluminum contacts caused by oxidation of the aluminum surface, we used gold/chromium interfaces. We investigated the sensors behavior by mean of electrical measurements, extracting the graphene properties, such as mobility and doping. We observed modulation of the source–drain current, determined the Dirac point and found the optimal voltage levels to be sensitive to pulsed IR laser light and β-particles.
•Investigation of n-doped substrate as base to develop graphene-based pixel sensors.•Design and production of GFET pixel sensor for the detection of MIPs.•Simulation of static operations and the dynamic response with Sentaurus TCAD.•Identification of technology challenges and incompatibilities.•Replacement of standard aluminum contacts with gold contacts.
The silicon vertex detector of the Belle II experiment Gabrielli, A.; Adamczyk, K.; Aihara, H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2024, Letnik:
1064
Journal Article
Recenzirano
The silicon vertex detector (SVD) is a four-layer double-sided strip detector installed at the heart of the Belle II experiment, taking data at the high-luminosity B-Factory SuperKEKB since 2019. SVD ...has been operating smoothly and reliably, showing a stable and above-99% hit efficiency, and a large signal-to-noise ratio in all sensors. In June 2022 the data-taking of the Belle II experiment was stopped for the Long Shutdown 1, primarily required to complete the vertex detector (VXD) with the inner two-layer DEPFET detector and to upgrade several components of the accelerator. This article reports on the excellent performance of SVD in terms of the signal-to-noise ratio, the hit position resolution, as well as the hit-time resolution. We briefly describe the challenges and delicate phases of the VXD re-installation and the SVD status for operation starting in early 2024. In SVD layer 3, which is closest to the interaction point, the average occupancy has been less 0.5%, well below the estimated limit for acceptable tracking performance. However, higher machine backgrounds are expected at increased luminosity, and so also increased hit occupancy. To enhance the robustness of offline software in a high-background environment, new algorithms of background suppression using the excellent SVD hit-time information have been developed, which allows a significant reduction of the fake rate, while preserving the tracking efficiency.
With the increasing luminosity also the radiation levels are expected to increase, with possible deterioration of the sensor performance. The SVD integrated dose is estimated by the correlation of the SVD occupancy with the dose rate measured by the diamonds of the radiation monitor and beam-abort system.
The effects of radiation damage are starting and in good agreement with our expectations. So far, no harmful impact due to the radiation damage on the detector performance has been observed.
The Silicon Vertex Detector of the Belle II experiment Zani, L.; Adamczyk, K.; Aggarwal, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2022, Letnik:
1038
Journal Article
Recenzirano
Odprti dostop
Since the start of data taking in spring 2019 at the SuperKEKB collider (KEK, Japan) the Belle II Silicon Vertex Detector (SVD) has been operating reliably and with high efficiency, while providing ...high quality data: high signal-to-noise ratio, greater than 99% hit efficiency, and precise spatial resolution. These attributes, combined with stability over time, result in good tracking efficiency. Currently the occupancy, dominated by beam-background hits, is quite low (about 0.5 % in the innermost layer), causing no problems to the SVD data reconstruction. In view of the operation at higher luminosity foreseen in the next years, specific strategies aiming to preserve the tracking performance have been developed and tested on data. The time stability of the trigger allows reducing sampling of the strip-amplifier waveform. The good hit-time resolution can be exploited to further improve the robustness against the higher level of beam background. First effects of radiation damage on strip noise, sensor currents and depletion voltage have been measured: they do not have any detrimental effect on the performance of the detector. Furthermore, no damage to the SVD is observed after sudden and intense bursts of radiation due to beam losses.
The Silicon Vertex Detector of the Belle II experiment Uematsu, Y.; Adamczyk, K.; Aggarwal, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2022, Letnik:
1033
Journal Article
Recenzirano
Odprti dostop
The Silicon Vertex Detector (SVD) is a part of the vertex detector in the Belle II experiment at the SuperKEKB collider (KEK, Japan). Since the start of data taking in spring 2019, the SVD has been ...operating stably and reliably with a high signal-to-noise ratio and hit efficiency, achieving good spatial resolution and high track reconstruction efficiency. The hit occupancy, which mostly comes from the beam-related background, is currently about 0.5% in the innermost layer, causing no impact on the SVD performance. In anticipation of the operation at higher luminosity in the following years, two strategies to sustain the tracking performance in future high beam background conditions have been developed and tested on data. One is to reduce the number of signal waveform samples to decrease dead time, data size, and occupancy. The other is to utilize the good hit-time resolution to reject the beam background hits. We also measured the radiation effects on the full depletion voltage, sensor current, and strip noise caused during the first two and a half years of operation. The results show no detrimental effect on the SVD performance.
The Silicon Vertex Detector (SVD), with its four double-sided silicon strip sensor layers, is one of the two vertex sub-detectors of Belle II operating at SuperKEKB collider (KEK, Japan). Since 2019 ...and the start of the data taking, the SVD has demonstrated a reliable and highly efficient operation, even running in an environment with harsh beam backgrounds that are induced by the world’s highest instantaneous luminosity.
In order to provide the best quality track reconstruction with an efficient pattern recognition and track fit, and to correctly propagate the uncertainty on the hit’s position to the track parameters, it is crucial to precisely estimate the resolution of the cluster position measurement. Several methods for estimating the position resolution directly from the data will be discussed.
The paper describes a mixed-mode ASIC composed of a fast readout architecture that interfaces with a matrix of 4096 Monolithic Active Pixel Sensors (MAPS). The matrix has 128 columns and 32 rows of ...pixels and is divided into 256 regions of 4 times 4 pixels, named macro-pixels (MPs). The chip is an upgrade of a smaller version having 256 pixels that was designed and tested. The two chips were designed via STM 130 nm CMOS technology. The pixel dimension is 50 by 50 mum 2 . The work is aimed at improving the design of MAPS detectors with an on-chip fast sparsification system, for particle tracking, to match the requirements of future high-energy physics experiments. The readout architecture implemented is data driven to extend the flexibility of the system, to be also used in first level triggers on tracks in vertex detectors. Simulations indicate that the readout system can cope with an average hit rate up to 100 MHz/cm 2 if a master clock of 80 MHz is used, while maintaining an overall efficiency over 99%.
