Silicon Microstrip Sensors Research Articles

Characterization of Tracking Modules Based on DSSD Sensors at the SC-1000 Accelerator for the BM@N Project

The results of studying characteristics of modules based on double-sided microstrip silicon sensors, which are designed to create the wide-aperture Silicon Tracking System for the BM@N facility, are presented. The main module features are the use of fast readout electronics based on the STS-XYTER chip and the application of ultralight (0.23% X0) aluminum microcables for transmitting analog signals from the sensor strips to the input channels of the readout electronics. The results of testing different configurations of tracking modules on the extracted beam of protons at the SC-1000 accelerator in the PNPI are presented. The stable operation of readout electronics is demonstrated at loads close to the maximum values of 360 kHz s–1 cm–2. The signal-to-noise ratio was no less than 23. The measured coordinate resolution of the modules within the beam telescope was 17 ± 0.4 μm, and the detector efficiency of recording for protons with energy of 1 GeV was no less than 99%.

The high count-rate self-triggering Silicon Tracking System of the CBM experiment at FAIR: Design, series assembly, upgrade options

The Compressed Baryonic Matter (CBM) experiment is a stationary target spectrometer with hadron and lepton identification. It is under construction at the Facility for Antiproton and Ion Research (FAIR) that is being realized next to the GSI grounds in Darmstadt, Germany. CBM will investigate QCD matter at highest, up to supernova core-collaps baryonic densities (Ablyazimov et al., 2017). This will be done in collisions of nuclear beams with targets at center of mass energies sNN=2.9–4.9 GeV. Because of the long beam extraction technique employed at FAIR’s SIS100 synchrotron, CBM’s data collection can be based on streaming time-stamped detector data into a compute farm. Event determination and physics analysis are performed there online, allowing for collision rates up to 10 MHz. CBM’s core tracking detector is the Silicon Tracking System, operating 8 tracking stations based on double-sided silicon microstrip sensors and self-triggering front-end electronics in a 1 Tm dipole magnetic field (Heuser et al., 2013).

From 3D to 5D tracking: SMX ASIC-based double-sided micro-strip detectors for comprehensive space, time, and energy measurements

We present the recent development of a lightweight detector capable of accurate spatial, timing, and amplitude resolution of charged particles. The technology is based on double-sided double-metal p+ – n – n+ micro-strip silicon sensors, ultra-light long aluminum-polyimide micro-cables for the analogue signal transfer, and a custom-developed SMX read-out ASIC capable of measurement of the time (Δt ≲ 5 ns) and amplitude. Dense detector integration enables a material budget > 0.3 % X 0. A sophisticated powering and grounding scheme keeps the noise under control.In addition to its primary application in Silicon Tracking System of the future CBM experiment in Darmstadt, our detector will be utilized in other research applications.

Jitter Measurements of 1 cm2 LGADs for Space Experiments

This work explores the possibility of using Low Gain Avalanche Diodes (LGADs) for tracker-based experiments studying Charged Cosmic Rays (CCRs) in space. While conventional silicon microstrip sensors provide only spatial information about the charged particle passing through the tracker, LGADs have the potential to provide additional timing information with a resolution in the order of tens of picoseconds. For the first time, it has been demonstrated that an LGAD with an active area of approximately 1 cm2 can achieve a jitter of less than 40 ps. A comparison of design and gain layers is carried out to understand which provides the best time resolution. For this purpose, laboratory measurements of sensors’ electrical properties and gain using LED and an Infrared laser, as well as their jitter, were performed.

ATLAS ITk strip detector for the Phase-II Upgrade

The inner detector of the present ATLAS experiment has been designed and developed to function in the environment of the present Large Hadron Collider (LHC). At the ATLAS Phase-II Upgrade, the particle densities and radiation levels will exceed current levels by a factor of ten. The instantaneous luminosity is expected to reach unprecedented values, resulting in up to 200 proton-proton interactions in a typical bunch crossing. The new detectors must be faster and they need to be more highly segmented. The sensors used also need to be far more resistant to radiation, and they require much greater power delivery to the front-end systems. At the same time, they cannot introduce excess material which could undermine tracking performance. For those reasons, the inner tracker of the ATLAS detector was redesigned and will be rebuilt completely. The ATLAS Upgrade Inner Tracker (ITk) consists of several layers of silicon particle detectors. The innermost layers will be composed of silicon pixel sensors, and the outer layers will consist of silicon microstrip sensors. This contribution focuses on the strip region of the ITk. The central part of the strip tracker (barrel) will be composed of rectangular short (∼2.5 cm) and long (∼5 cm) strip sensors. The forward regions of the strip tracker (end-caps) consist of six disks per side, with trapezoidal shaped sensors of various lengths and strip pitches. After the completion of final design reviews in key areas, such as Sensors, Modules, Front-End electronics, and ASICs, a large scale prototyping program has been completed in all areas successfully. We present an overview of the Strip System and highlight the final design choices of sensors, module designs and ASICs. We will summarise results achieved during prototyping and the current status of pre-production and production on various detector components, with an emphasis on QA and QC procedures.

Functional characterization of modules for the Silicon Tracking System of the CBM experiment

The CBM experiment is a fixed-target heavy-ion physics experiment at the future FAIR facility, designed to explore the QCD phase diagram at high baryon-net densities and moderate temperatures. To address its complex physics program, the experiment is conceived to operate at beam–target interaction rates up to 10 MHz with self-triggered front-end electronics and free-streaming readout architecture. The Silicon Tracking System (STS) of CBM is the main charged-particle tracker, capable of delivering time-stamped hits for online tracking and event building, and momentum measurement inside a superconducting dipole magnet. The functional unit of the STS is the detector module, a device assembled from a double-sided silicon microstrip sensor connected via a stack of microcables to a pair of front-end boards carrying the readout electronics. The assembly and successful operation of STS modules, produced with close-to-final components, was an important milestone achieved in recent years. The systematic study of the modules’ performance is also necessary for optimizing the assembly procedure and ensuring high production yield. This work reports a series of tests, which aim to evaluate the module’s operation and establish the basic criteria for quality control. It summarizes the procedures and results of different measurements performed with the modules, starting with noise estimation and charge amplitude calibration, resulting in the linearization of the channel’s ADC and a homogeneous threshold distribution. Those results were verified using a radioactive source. Additionally, first conclusions concerning the assembly yield in terms of number of functional channels were obtained. These studies represent a fundamental step towards the series production readiness for the final STS detector.

Assembly Device for Supermodules of Silicon Tracking System of the BM@N Experiment

The silicon tracking system of the BM@N experiment consists of four stations based on double-sided microstrip silicon sensors. The sensors make it possible to obtain a spatial resolution for tracks of secondary charged particles up to 17 μm. Two ASIC boards, the input channels of which are connected to the strips with ultralight (0.23% X0) aluminum flex cables, are used to readout and process signals from both sides of the sensor. Such an assembly is called a module. Silicon sensors are mounted on lightweight carbon-fiber support trusses in a way that the dead zones at the edges are overlapped due to the tiled layout. The frontend electronics are housed in metal containers with a heat sink system located at the rare ends of the carbon-fiber support truss. A set of modules attached to the carbon-fiber support truss with two containers with readout electronics at the ends is called a supermodule. The accuracy of the sensor positioning in the station plane plays a crucial role in limiting the degrees of freedom of the parameters determined by the software during the final alignment of the tracking system elements. A special device that allows mounting sensors on a carbon fiber truss with an accuracy of up to 15 µm on a 1200 mm base is developed to assemble supermodules. The results of testing the device are given.

Test and characterisation of STS/MuCh-XYTER and integration with multiple detectors of CBM-MuCh detector systems

Compressed Baryonic Matter (CBM) is a fixed target experiment at the upcoming Facility for Anti-proton and Ion Research in Germany, having collision rates up to 10 MHz. Due to the proximity of the target and secondaries produced in absorbers, Muon Chambers (MuCh) of the CBM experiment will face a very high particle hit rate of up to 400 kHz/cm2 in its first two stations. To cope with these particle rates, a Gas Electron Multiplier (GEM) detector will be used for the first two stations while, due to relatively lower particle rates, the last two stations will use a low resistivity Bakelite Resistive Plate Chamber (RPC) detector. The electronics of these two MuCh detectors need different dynamic ranges.A Silicon Tracking Station (STS) system made of 300 μm thick silicon micro-strip sensors will be installed upstream of the MuCh detector system. The sensors will be read out through multi-line micro-cables with fast electronics. The micro-strip sensors will be double-sided with a stereo angle of 7.5°, a strip width of 58 μm, and strip lengths between 20 and 120 mm requiring high-density readout.To meet the high rate and high density requirements of MuCh and STS, respectively, a specialized 128-channel readout ASIC with a dual-gain feature is designed. This is a highly configurable ASIC with about 30,000 configurable register bits which control various bias and threshold settings of the ASIC. To integrate this ASIC with both the detector systems, detailed testing and characterization of the ASIC are required.Due to the high number of configurable registers and several operating conditions, characterizing this ASIC is very challenging. This paper describes the optimization procedures of several configurable bias parameters in detail and also explains how this ASIC is integrated with both GEM and RPC detectors of the MuCh system.

ATLAS ITk strip sensor quality control procedures and testing site qualification

The high-luminosity upgrade of the Large Hadron Collider, scheduled to become operational in 2029, requires the replacement of the ATLAS Inner Detector with a new all-silicon Inner Tracker. Radiation hard n+-in-p micro-strip silicon sensors were developed by the ATLAS Inner Tracker strip collaboration and are produced by Hamamatsu Photonics K.K. Production of the total amount of 22000 strip sensors has started in 2020 and will continue until 2025. The ATLAS strip sensor collaboration has the responsibility to monitor the quality of the fabricated devices by performing detailed measurements of individual sensor characteristics and by comparing the obtained results with the tests done by the manufacturer. Dedicated Quality Control procedures were developed to check whether the delivered large-format sensors adhere to the ATLAS specifications. The institutes performing the Quality Control testing of the pre-production and production ATLAS ITk strip sensors had to initially be qualified for multiple high-throughput tests by successfully completing the Site Qualification process. The Quality Control procedures and the qualification process are described in this paper.

Characterization of 150 μm thick silicon microstrip prototype for the FOOT experiment

The goals of the FOOT (FragmentatiOn Of Target) experiment are to measure the proton double differential fragmentation cross-section on H, C, O targets at beam energies of interest for hadrontherapy (50–250 MeV for protons and 50–400 MeV/u for carbon ions), and also at higher energy, up to 1 GeV/u for radioprotection in space. Given the short range of the fragments, an inverse kinematic approach has been chosen, requiring precise tracking capabilities for charged particles. One of the subsystems designed for the experiment will be the MSD (Microstrip Silicon Detector), consisting of three x-y measurement planes, each one made by two single sided silicon microstrip sensors. In this document, we will present a detailed description of the first MSD prototype assembly, developed by INFN Perugia group and the subsequent characterization of the detector performance. The prototype is a wide area(∼ 100 cm2) single sensor, 150 μm thick to reduce material budget and fragmentation probability along the beam path, with 50 μm strip pitch and 2 floating strip readout approach. The pitch adapter to connect strips with the readout channels of the ASIC has been implemented directly on the silicon surface. Beside the interest for the FOOT experiment, the results in terms of cluster signal, signal-to-noise ratio, dynamic range of the readout chips, as well as long-term stability studies in terms of noise, are relevant also for other experiments where the use of thin sensors is crucial.

Optical inspection of the silicon micro-strip sensors for the CBM experiment employing artificial intelligence

Optical inspection of 1191 silicon micro-strip sensors was performed using a custom made optical inspection setup, employing a machine-learning based approach for the defect analysis and subsequent quality assurance. Furthermore, metrological control of the sensor’s surface was performed. In this manuscript, we present the analysis of various sensor surface defects. Among these are implant breaks, p-stop breaks, aluminium strip opens, aluminium strip shorts, surface scratches, double metallization layer defects, passivation layer defects, bias resistor defects as well as dust particle identification. The defect detection was done using the application of Convolutional Deep Neural Networks (CDNNs). From this, defective strips and defect clusters were identified, as well as a 2D map of the defects using their geometrical positions on the sensor was performed. Based on the total number of defects found on the sensor’s surface, a method for the estimation of sensor’s overall quality grade and quality score was proposed.

EASY: Educational Alibava System

EASY, a plug-and-play educational system, is portable, compact and a complete system for micro-strip sensor characterization. Ideal for making basic or complex experiments. It is based on the Classic Alibava System [1], largely used within the CERN community to test micro-strip detectors for particle experiments. The system can be configured to work with pulsed laser light or radioactive sources. The aim of this system is to illustrate students in the operation of a silicon strip detectors The components of the EASY systems are the Control Unit and the Sensor Unit. The Control Unit is the heart of the system communicating with the Sensor Unit and the Computer software. It contains the Data Acquisition Control and it is also in charge of processing of the sensor data and trigger inputs. In addition, it contains an adjustable Hight Voltage unit for micro-strip sensor bias, with voltage and current display and includes the laser source. The Control Unit communicates with computer software via USB. The Sensor Unit accommodate a p-on-n silicon micro-strip sensor segmented in 128 strips. EASY comes with an activity book where the students, through 10 exercises, are introduced in the main concepts and functionalities of micro-strip silicon detectors, used in the actual particle physic experiments. The book also provides a full description of the EASY device and the data Acquisition system.

All-programmable low noise readout ASIC for silicon strip sensors in tracking detectors

The Programmable Read-out with Improved Noise-performance Charge Sensitive Amplifier (PRINCSA) is a prototype Application Specific Integrated Circuit (ASIC) designed for read-out of the silicon micro-strip sensors in the tracking detectors for Physics experiments. The main aim of this project was to minimize the overall system noise (Equivalent Noise Charge, ENC) and implement a range of programmable features to adjust the noise performance to varying conditions. The chip comprises three single-ended and three pseudo-differential channels that additionally allow for power supply interference reduction. All channels include a charge sensitive amplifier (CSA), a fast shaping amplifier for time measurements, and a slow shaping amplifier for amplitude measurements. The slow shaper’s architecture (in all channels) and its peaking time (in the single-ended channels) are configurable to test the capability of noise filtering for various dominant noise contributions (unipolar semi-Gaussian and complex conjugate poles filters). To further improve the power supply rejection ratio, additional on-chip filtering of the preamplifier biasing potential is included in every channel. For faster CSA baseline restoration, its feedback in all channels is equipped with a pulsed reset circuit. In this design, it is combined with a double-polarity Krummenacher circuit for leakage current compensation for both polarities of charge pulse and leakage current without compromising the large value of the CSA feedback resistance. The ASIC comprises a calibration circuit working in two operational modes: a standard double-polarity charge injection and a single-polarity charge injection (fast leading and slow falling edges of the calibration pulses) with programmable amplitude. The IC was fabricated in Q4 2018 using UMC CMOS 180 nm technology node.

Characterization of silicon microstrip sensors for space astronomy

Silicon microstrip detectors are widely used in experiments for space astronomy. Before the detector is assembled, extensive characterization of the silicon microstrip sensors is indispensable and challenging. This work electrically evaluates a series of sensor parameters, including the depletion voltage, bias resistance, metal strip resistance, total leakage current, strip leakage current, coupling capacitance, and interstrip capacitance. Two methods are used to accurately measure the strip leakage current, and the test results match each other well. In measuring the coupling capacitance, we extract the correct value based on a SPICE model and two-port network analysis. In addition, the expression of the measured bias resistance is deduced based on the SPICE model.

Operation of silicon microstrip detector with integrating readout for fast time-resolved experiments

New detector prototype is being developed for the “Plasma” scattering station of the VEPP-4M synchrotron radiation source at the Budker Institute of Nuclear Physics. The prototype is based on p-in-n silicon microstrip sensor with metal strips galvanicaly coupled to the p-implants. Each strip is connected to the input of low-noise integrator with 32 analogue memory cells. This approach allows to record time evolution of one-dimensional image of diffraction pattern with frame rate up to 10 MHz, spatial resolution of ∼130 μm (FWHM) and maximum photon flux of about 200 photons/channel.

Optimisation of a silicon microstrip telescope for UA9 crystal channeling studies

A charged particle telescope based on silicon microstrip sensors has been used for several years for data taking at high rates in the CERN H8 beam line using a range of different incident particles. The electronic readout and data acquisition system is based on that developed for the CMS Tracker, and provides almost deadtime-free operation at trigger rates of up to about 10 kHz. The telescope was designed to characterise crystals in channeling studies by the UA9 experiment with the primary objective to validate them for use in a future LHC beam collimation system, hence is optimised for measurement of a single particle in the outgoing arm. The telescope has also been used for other studies of fundamental phenomena associated with the channeling process and further LHC applications. Some of these require a different layout of the telescope, for example to achieve a larger angular acceptance to study longer channeling crystals, or modifications to sensor operating conditions because of the very large electric charge and consequent ionisation energy loss associated with heavy ions. The telescope and its performance are described. Possible improvements are discussed.

Prototype single-ended and pseudo-differential charge processing circuit for micro-strip silicon and gaseous sensors read-out

Detector read-out electronics for Physics Experiments as for example Compressed Baryonic Matter experiment at FAIR, Darmstadt, Germany, should meet tight requirements concerning noise (ENC < 1000 e− rms to guarantee event reconstruction), power consumption (< 10 mW/channel) and average input hit frequency of 250 kHit/s/channel. The ICs design should take into account not only the charge processing parameters but also the impact of the environmental and system-level conditions like radiation, noisy power supply, and temperature to ensure reliable and stable operation during an experiment in a system built with tens of thousands of devices. The operation with gaseous detectors requires particularly effective protection of the inputs against electrostatic discharge. The ESD protection circuit (in particular based on MOS transistors), together with the sensor itself, or AC-coupling capacitors (after irradiation) can be however a source of additional leakage current flowing into the first stage of charge processing chain and affecting the performance. The read-out electronics (in particular first stage—charge sensitive amplifier, CSA) and detector-related noise can be mitigated using proper filtration and signal shaping. However, noise introduced by external sources, like power supply interference, can not be limited only via proper shaping and filtration. When LC filtering is not possible (due to high magnetic fields), it may be beneficial to use differential or pseudo-differential signal processing. The purpose of this work was to test several ideas to improve noise performance and to make the architecture of charge processing chain configurable to better adapt to different target radiation imaging applications. The ASIC comprises four single-ended and four pseudo-differential signal processing channels. In both types of channels configurable slow shaper configuration is used—it is switchable CR-RC2 type shaper and complex conjugate poles 3rd order shaper. CSA feedback in single-ended architecture can be selected between MOS transistor working in a linear region and double-polarity Krummenacher circuit for leakage current compensation capability. The chip was designed and fabricated in Q4 2018 using 180 nm process. Front-end single-ended and differential channels occupy the area from 950 × 60 μm2 up to 1150 × 125 μm2 and consume 5 mW up to 12 mW of power respectively. The work presents design and measurements results.

The Silicon Tracking System of the CBM Experiment at FAIR

The Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR) aims to study the properties of nuclear matter at high net-baryon densities and moderate temperatures.The Silicon Tracking System (STS) is the key detector to reconstruct with a high efficiency up to 1000 charged particle trajectories created in heavy-ion collisions at interaction rates of up to 10 MHz. It will determine the momentum of the particles with a momentum resolution Δp/p ≈ 1-2% which requires ultra-low detector material budget of 0.3-1% X0 per layer. The detector comprise eight layers of double-sided silicon micro-strip sensors and will be placed inside the 1 Tm superconducting magnet which limits the space available, which in turn requires advanced cooling approaches and mechanical design with precise tracking layers alignment. The micro-strip sensors have to be radiation hard and checked for their quality optically and electrically before the assembly.This contribution gives an overview of the STS and presents the status of its component quality control and assembly procedures.

The Silicon Tracking System of the CBM Experiment at FAIR

The Compressed Baryonic Matter (CBM) experiment at FAIR (Darmstadt, Germany) is designed to study the dense nuclear matter in a fixed target configuration with heavy ion beams up to kinetic energies of 11 AGeV for Au+Au collision. The charged particle tracking with below 2% momentum resolution will be performed by the Silicon Tracking System (STS) located in the aperture of a dipole magnet. The detector will be able to reconstruct secondary decay vertices of rare probes, e.g., multistrange hyperons, with 50 мm spatial resolution in the heavy-ion collision environment with up to 1000 charged particle per inelastic interaction at the 10 MHz collision rate. This task requires a highly granular fast detector with radiation tolerance enough to withstand a particle fluence of up to 1014 neq/cm2 1-MeV equivalent accumulated over several years of operation. The system comprises 8 tracking stations based on double-sided silicon microstrip sensors with 58 мm pitch and strips oriented at 7.5∘ stereo angle. The analog signals are read out via stacked microcables (up to 50 cm long) by the front-end electronics based on the STS-XYTER ASIC with self-triggering architecture. Detector modules with this structure will have a material budget between 0.3% and 1.5% radiation length increasing towards the periphery. First detector modules and ladders built from pre-final components have been operated in the demonstrator experiment mCBM at GSI-SIS18 (FAIR Phase-0) providing a test stand for the performance evaluation and system integration. The results of mSTS detector commissioning and the performance in the beam will be presented.

The HEPD detector on board CSES satellite: in-flight performance

In this paper we will present a description of the High Energy Particle Detector (HEPD) onboard the China Seismo Electromagnetic Satellite (CSES) and its (preliminary) performance in flight.CSES mission aims at monitoring electromagnetic field, plasma and particles perturbations of atmosphere and inner Van Allen belts caused by solar and terrestrial phenomena and to the study of the low energy component of the cosmic rays.The satellite was launched from the Jiuquan Satellite Launch Center located in west of inner Mongolia on February 2nd, 2018 and is now orbiting in nominal condition. It hosts several instruments onboard: two magnetometers, an electrical field detector, a plasma analyser, a Langmuir probe and two particle detectors.The high energy particle detector (HEPD), designed and built by the Italian Limadou collaboration, is able to separate electrons and protons and identify nuclei up to Iron. HEPD provides good energy resolution and high angular resolution for electrons (3-100 MeV) and proton (30-200 MeV). The instrument consists of: 2 planes of double-side silicon microstrip sensors placed on the top of the instrument (direction of particle); 2 two layers of plastic scintillators (trigger) and a calorimeter (constituted by other 16 scintillators and a layer of LYSO sensors). A scintillator veto system completes the instrument. The commissioning of the HEPD and the other instruments on board was successfully completed in July 2018.