A mixed-signal ASIC for timing and energy measurements with radiation detectors is described. The chip embeds 64 channels, each of which features a charge-sensitive amplifier followed by a ...dual-shaper coupled to low-offset discriminators. A versatile back-end, incorporating low-power Time to Digital Converters and Wilkinson Analog to Digital Converters with derandomizing buffers allows to encode both the time of arrival and the charge of the input signal. The ASIC is designed for a maximum detector capacitance of 100 pF and an event rate in excess of 60 kHz per channel. A peak detector samples the input signal with an excellent linearity in the range 5÷55 fC. Charge digitization with Time-over-Threshold is also supported to extend the dynamic range. Fabricated in a 110 nm CMOS process, the chip dissipates 10 mW/channel. The ASIC was primarily developed to readout the cylindrical GEM detector of the BESIII experiment. For its characteristics it can serve however a broad class of radiation sensors, including silicon microstrip detectors.
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•Range monitoring is necessary to fully exploit hadrontherapy advantages.•The Monte Carlo (MC) simulation tool for the INSIDE in-beam PET scanner is described.•The Monte Carlo tool ...provides images directly comparable with the experimental ones.•The comparison with in vivo experimental data validates the tool reliability.•The simulation information is already reliable after the first half of the treatment.
Hadrontherapy is a method for treating cancer with very targeted dose distributions and enhanced radiobiological effects. To fully exploit these advantages, in vivo range monitoring systems are required. These devices measure, preferably during the treatment, the secondary radiation generated by the beam-tissue interactions. However, since correlation of the secondary radiation distribution with the dose is not straightforward, Monte Carlo (MC) simulations are very important for treatment quality assessment.
The INSIDE project constructed an in-beam PET scanner to detect signals generated by the positron-emitting isotopes resulting from projectile-target fragmentation. In addition, a FLUKA-based simulation tool was developed to predict the corresponding reference PET images using a detailed scanner model.
The INSIDE in-beam PET was used to monitor two consecutive proton treatment sessions on a patient at the Italian Center for Oncological Hadrontherapy (CNAO). The reconstructed PET images were updated every 10 s providing a near real-time quality assessment. By half-way through the treatment, the statistics of the measured PET images were already significant enough to be compared with the simulations with average differences in the activity range less than 2.5 mm along the beam direction. Without taking into account any preferential direction, differences within 1 mm were found.
In this paper, the INSIDE MC simulation tool is described and the results of the first in vivo agreement evaluation are reported. These results have justified a clinical trial, in which the MC simulation tool will be used on a daily basis to study the compliance tolerances between the measured and simulated PET images.
The CERN RD53 collaboration was founded to tackle the extraordinary challenges associated with the design of pixel readout chips for the innermost layers of particle trackers at future high energy ...physics experiments. Around 20 institutions are involved in the collaboration, which has the support of both ATLAS and CMS experiments. The goals of the collaboration include the comprehensive understanding of radiation effects in the 65 nm technology, the development of tools and methodology to efficiently design large complex mixed signal chips and, ultimately, the development of a full size readout chip featuring a 400 × 400 pixel array with 50μm pitch. In August 2017, the collaboration submitted the large scale chip RD53A, integrating a matrix of 400 × 192 pixels and embodying three different analog front-end designs. This work discusses the characteristic of the RD53A chip, with some emphasis on the analog processors, and presents the first test results on the pixel array.
•High particle rates and radiation levels will be reached at the HL-LHC.•New pixel chips for the phase II upgrades of CMS and ATLAS are required.•The RD53A chip has been designed in the framework of the RD53 Collaboration.•Three analog front-ends flavors are integrated in RD53A.•The paper presents the main preliminary results coming from RD53A characterization.
Micro Pattern Gas Detectors (MPGD) are the new frontier in gas trackers. Among this kind of devices, the Gas Electron Multiplier (GEM) chambers are widely used. The experimental signals acquired with ...the detector must obviously be reconstructed and analysed. In this contribution, a new offline software to perform reconstruction, alignment and analysis on the data collected with APV-25 and TIGER ASICs will be presented. GRAAL (Gem Reconstruction And Analysis Library) is able to measure the performance of a MPGD detector with a strip segmented anode (presently). The code is divided in three parts: reconstruction, where the hits are digitized and clusterized; tracking, where a procedure fits the points from the tracking system and uses that information to align the chamber with rotations and shifts; analysis, where the performance is evaluated (e.g. efficiency, spatial resolution,etc.). The user must set the geometry of the setup and then the program returns automatically the analysis results, taking care of different conditions of gas mixture, electric field, magnetic field, geometries, strip orientation, dead strip, misalignment and many others.
Triple-GEM detectors are a well known technology in high energy physics. In order to have a complete understanding of their behavior, in parallel with on beam testing, a Monte Carlo code has to be ...developed to simulate their response to the passage of particles. The software must take into account all the physical processes involved from the primary ionization up to the signal formation, e.g. the avalanche multiplication and the effect of the diffusion on the electrons. In the case of gas detectors, existing software such as Garfield already perform a very detailed simulation but are CPU time consuming. A description of a reliable but faster simulation is presented here: it uses a parametric description of the variables of interest obtained by suitable preliminary Garfield simulations and tuned to the test beam data. It can reproduce the real values of the charge measured by the strip, needed to reconstruct the position with the Charge Centroid method. In addition, particular attention was put to the simulation of the timing information, which permits to apply also the micro-Time Projection Chamber position reconstruction, for the first time on a triple-GEM. A comparison between simulation and experimental values of some sentinel variables in different conditions of magnetic field, high voltage settings and incident angle will be shown.
A new inner tracker based on a cylindrical gas electron-multiplier detector is under development to replace the current inner drift chamber of the BES III spectrometer. The BES III experiment is ...carried out at the BEPC II e
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collider in Beijing at center-of-mass energies in the tau-charm region with a design luminosity of 1.0
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. The new inner tracker consists of three cylindrical layers of triple GEM surrounding the interaction point, covering 93% of solid angle. To fulfill physics requirements, a spatial resolution of 130 μm must be achieved. Both planar and cylindrical prototypes have been built and tested. A custom ASIC using UMC 110-nm technology has been designed to provide charge and time measurements—the first prototype is in testing. Notable and innovative aspects of the new inner tracker and the performance of the detector prototypes and readout ASIC are reported here.
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