Tracker Modules Research Articles

How the discovery of Cold Noise delayed the production of ATLAS ITk strip tracker modules by a year

The construction of the ATLAS strip tracker barrel will require the assembly of 12,000 barrel detector modules over the course of 3.5 years. In 2022, during the module pre-production phase, modules were found to display clusters of noisy channels outside required specifications when tested at operating temperatures (-35°C), called “Cold Noise”. Extensive investigations into the cause and mechanism of Cold Noise interrupted pre-production and occupied most barrel module assembly sites. This contribution presents an overview of the year-long investigations into Cold Noise, the final identification of the underlying mechanism and necessary changes for the transition to production.

The quality control programme for ITk strip tracker module assembly

The assembly of the ATLAS Inner Tracker requires the construction of 19,000 silicon strip sensor detector modules in eight different geometries. Modules will be assembled and tested at 31 institutes on four continents from sensors, readout chips, and flexes. In order to adhere to the module specifications defined for sufficient tracking performance, a rigorous programme of quality control (QC) was established to cover components at every stage of assembly. This contribution presents an overview of the QC programme for ITk strip tracker modules, issues encountered during the pre-production phase (5% of the production volume), and their solutions.

Agri-Horti-PV Research System in North Rhine-Westphalia Including PV Trackers and Integrated Rainwater Harvesting

We present a new Agri-Horti-PV system installed at the end of 2021 in the brown coal area of North Rhine-Westphalia near Jülich, Germany. The system contains different PV installations: Standard south oriented PV modules with a rainwater harvesting set up and east-west tracker modules, of which one is equipped with a rainwater harvesting setup. For the investigation of plant growth under the PV panels and on the reference areas without PV installations a novel rail system allowing for automatic camera movement is integrated in the Agri-Horti-PV park. Using the camera setup plant growth measurements with high spatio-temporal resolution will be possible. The scientific investigations of crop growth and the influence of variable shading conditions controlled by the tracking system started in the growth season of 2022. Here we present the technical details of the system as well as first results of an experiment carried out with faba beans, assessing impact of the Horti-PV system on growth dynamics and leaf morphology.

The mass production of silicon sensors for the Phase-2 CMS Outer Tracker

The high luminosity upgrade of the Large Hadron Collider (HL-LHC) will create a more challenging and demanding environment for the operation of the CMS detector. The peak instantaneous luminosity of the HL-LHC machine will reach 5–7 × 1034 cm-2s-1, which by the end of its lifetime will have delivered up to 4000 fb-1. To cope with these conditions the CMS Tracker will be fully replaced with a more advanced system. The new sub-detector is divided into an Outer Tracker, instrumented by short strips and macro pixels, and a more granular Inner Tracker using pixelated sensors. This report will describe some features of the new Outer Tracker silicon sensors and modules, provide results indicating the quality of the sensors produced to date, as well as the robustness of the sensors against environmental factors such as relative humidity.

The JUNO experiment Top Tracker

The main task of the Top Tracker detector of the neutrino reactor experiment Jiangmen Underground Neutrino Observatory (JUNO) is to reconstruct and extrapolate atmospheric muon tracks down to the central detector. This muon tracker will help to evaluate the contribution of the cosmogenic background to the signal. The Top Tracker is located above JUNO’s water Cherenkov Detector and Central Detector, covering about 60% of the surface above them. The JUNO Top Tracker is constituted by the decommissioned OPERA experiment Target Tracker modules. The technology used consists in walls of two planes of plastic scintillator strips, one per transverse direction. Wavelength shifting fibres collect the light signal emitted by the scintillator strips and guide it to both ends where it is read by multianode photomultiplier tubes. Compared to the OPERA Target Tracker, the JUNO Top Tracker uses new electronics able to cope with the high rate produced by the high rock radioactivity compared to the one in Gran Sasso underground laboratory. This paper will present the new electronics and mechanical structure developed for the Top Tracker of JUNO along with its expected performance based on the current detector simulation.

Drone Detection and Surveillance

This paper presents a deep learning-based solution for detecting and identifying drones to address security concerns. By leveraging A9G-based GPS tracker modules, the system achieves real-time tracking and differentiation between authorized and unauthorized drones. The proposed model demonstrates high performance with an F-1 score of 93.63%, precision of 96.2%, mAp of 95%, recall of 91.2%, and accuracy of 95.5%. Authorized drone locations can be communicated via SMS for prompt action if an unauthorized drone is detected.

Alignment of the Alpha Magnetic Spectrometer (AMS) in space

The Alpha Magnetic Spectrometer (AMS) is a precision particle physics detector operating at an altitude of sim 410 km aboard the International Space Station. The AMS silicon tracker, together with the permanent magnet, measures the rigidity (momentum/charge) of cosmic rays in the range from sim 0.5 GV to several TV. In order to have accurate rigidity measurements, the positions of more than 2000 tracker modules have to be determined at the micron level by an alignment procedure. The tracker was first aligned using the 400 GeV/c proton test beam at CERN and then re-aligned using cosmic-ray events after being launched into space. A unique method to align the permanent magnetic spectrometer for a space experiment is presented. The developed underlying mathematical algorithm is discussed in detail.

Performance of CMS Tracker Alignment during LHC Run 2 and Commissioning towards Run 3

The CMS experiment’s innermost detector, the tracker, is designed to accurately measure the momentum of charged particles and reconstruct the primary vertices. As the operating conditions during data-taking change frequently, movements may occur in the substructures of the tracker, thereby necessitating regular updating of the detector geometry to describe the position, orientation, and curvature of the tracker modules. The process of determining the new geometry parameters is called tracker alignment. Tracker alignment is performed numerous times throughout the data-taking period using reconstructed tracks from collisions and cosmic rays data and further fine-tuned once the data collection is completed. The strategies for and the performance of the tracker alignment during Run 2 (2016-2018) will be presented, emphasising the ultimate accuracy achieved with the legacy reprocessing. The data-driven techniques used to derive the alignment parameters and the methods used to validate the alignment performance will be reviewed. Finally, the preparations of CMS towards tracker alignment during Run 3 (2022-2025)–in particular, the very first alignment performed after the LHC Long Shutdown 2, with cosmic ray muons and collision data at GeV–will be discussed.

Prototyping and qualification of 2S modules for the CMS Outer Tracker upgrade at the HL-LHC

In preparation for the High Luminosity LHC, the entire tracker detector of the CMS experiment will be exchanged as part of the Phase-2 Upgrade. The new Outer Tracker will comprise approximately 13,000 silicon sensor modules, of which 7608 are “2S modules” consisting of two parallel mounted silicon strip sensors, and 5592 are “PS modules” consisting of one pixel and one strip sensor in a single module. These modules provide tracking information to the level 1 trigger by correlating the hit information of both sensor layers, allowing discrimination of particle tracks by their transverse momentum. To guarantee successful operation during data-taking, the production of the outer tracker modules has to fulfill strict requirements. This note will discuss the assembly procedures as well as some key results of the electronic, thermal and vibration tests performed at CERN for qualifying the 2S module design and for preparing the module assembly procedures.

SoC-FPGA based data acquisition system for position sensitive silicon detectors

The System-on-a-Chip Field-Programmable Gate Array (SoC-FPGA) based Data Acquisition System (DAQ) is an autonomous measurement system for the Silicon beam profilometer, the Silicon beam tracker and Silicon modules test benches at the Baryonic Matter at Nuclotron (BM@N) experiment. The DAQ system provides detector signals digitization, storage and transfer of packaged data to a computer, processing and visualization of decoded information. The system is composed of the multichannel Front-end Electronics (FEE), the SoC-FPGA based Control Unit Carried Board equipped with two 8 channels analog-to-digital converters (ADCs), the Control and Analysis Software (C&A Software). The paper presents the DAQ system structure, the SoC-FPGA design, and the Silicon beam tracker test results.

Study, implementation and testing of radiation tolerant design for testability solutions for CMS OT FE ASICs

The MPA and SSA development is approaching the production phase with an approximate volume of more than 200k ASICs, corresponding to 1200 wafers. The limited manufacturing yield requires testing strategies able to identify defective units and guarantee the correct functionality of the tracker modules. This contribution presents innovative methods to replace the currently used functional tests for the digital part of the ASICs, showing limited testing accuracy and long testing time. The proposed solution exploits the concept of structural test and new testing algorithms such as Automatic Test Pattern Generation (ATPG) for general digital logic and March for memory elements. Design for Testability (DFT) hardware is integrated on chip to test SRAM memories, peripheral logic and MPA pixel array, providing internal control and observation points for the implementation of the those algorithms. Particular attention is given to power increase, timing and placement impact as well as radiation tolerance of the introduced circuitry, which must be fully transparent during the normal operation of the chip. A faster and more accurate testing approach is presented, from design methodology to implementation choices and silicon results, for a reliable and cost effective testing procedure.

Magnetic triggering — time-resolved characterisation of silicon strip modules in the presence of switching DC-DC converters

Modules for the ATLAS Inner Tracker (ITk) strip tracker include a DC-DC converter circuit glued directly to the silicon sensor which converts the 11 V supplied to the module to the 1.5 V required for the operation of the readout chips. The DC-DC converter unit, consisting of a copper solenoid and custom ASIC, is located directly above the silicon strip sensor and therefore needs to be shielded to protect the sensor from EMI noise created during the operation of the circuit. Despite dedicated shielding, consisting of an aluminium shield box with continuous solder seams encompassing the surface components and a copper layer in the PCB beneath it, module channels connected to sensor strips located beneath the converter circuit were found to show a noise increase. While the DC-DC converter unit causing the underlying EMI noise operates at a frequency of 2 MHz, module characterisation measurements for ITk strip tracker modules are typically performed asynchronously to the DC-DC switching and are therefore averaged over the full range of time bins with respect to the converter frequency. In order to investigate the time dependence of the noise injection relative to the DC-DC switching frequency, a dedicated setup to understand the time-resolved performance change in modules was developed. By using a magnetic field probe to measure the field leaking through the shield box and triggering on its rising edge, data taking could be synchronised with the DC-DC switching. This paper illustrates the concept and setup of such time-resolved performance measurements using magnetic triggering and presents results for the observed effects on signal and noise for ATLAS ITk strip modules from both laboratory and beam tests.

Implementation of a Low-Cost Flight Tracking System for High-Altitude Ballooning

High-altitude balloons (HABs) are typically tracked via Global Positioning System (GPS) data sent via real-time radio-based communication systems such as the Automatic Packet Reporting System (APRS). Prefabricated APRS-compatible tracker modules have made it trivial to transmit GPS coordinates and payload parameters in compliance with the requisite AX.25 protocol. However, in order to receive and track APRS signals, conventional methodologies call for the use of a very-high-frequency (VHF) receiver to demodulate signals transmitted on the APRS frequencies, along with a compatible antenna and custom methodology for visualizing the HAB’s location on a map. The entire assembly is typically costly, cumbersome, and may require an Internet connection in order to obtain real-time visualization of the HAB’s location. This paper describes a low-cost, handheld system based on open-source software that operates independently of an Internet connection. The miniaturized system is suited to tracking done either from a vehicle or on foot, and it is cost-effective enough to be within the means of nearly any HAB user. The paper also discusses preliminary test results and further applications.

Commissioning and simulation of CHROMIE, a high-rate test beam telescope

The upgrade of the LHC to the High-Luminosity LHC (HL-LHC) is expected to increase the current instantaneous luminosity by a factor of 5 to 7, providing the opportunity to study rare processes and measure precisely the standard model parameters. To cope with the increase in pile-up (up to 200), particle density and radiation, CMS will build new silicon tracking devices with higher granularity (to reduce occupancy) and improved radiation hardness. During the R&D period tests performed under beam are a powerful way to develop and examine the behavior of silicon sensors in realistic conditions. The telescopes used up to now have a slow readout (less than 10 kHz) for the needs of the CMS experiment, since the new outer-tracker modules have an effective return-to-zero time of 25 ns (corresponding to a 40 MHz frequency) and a trigger rate of 750 kHz. In order to test the CMS Tracker modules under the LHC nominal rate, a pixel telescope named CHROMIE (CMS High Rate telescOpe MachInE) is designed, built and commissioned at CERN for beam tests with prototype modules for the CMS Phase-2 Tracker upgrade. In this article the design of CHROMIE, the calibration of its modules, and its timing and synchronization aspects are presented, along with the first beam test results. In addition, the tracking algorithm developed for CHROMIE and a preliminary Geant4 simulation study of the telescope under beam are discussed.

LOSA-X: Expandable 3D Motion Tracking System

This paper presents a novel, low-cost, expandable 3D motion tracking system with the ability to adapt to dynamic background illumination. The proposed system consists of multiple tracker modules equipped with a linear optical sensor arrays and a 9-DOF inertial measurement unit for position and orientation tracking of a wireless IR-LED illuminated active marker. This paper presents an extended Kalman filter-based sensor fusion architecture for combining data acquired from multiple trackers and marker for enhanced accuracy and operational range. The marker system adaptively adjusts the LED intensity to optimize energy consumption and measurement accuracy. The proposed system’s ability to extract background illumination allows it to be robust toward differences in scene illuminations, both static and dynamic. Detailed hardware design and performance evaluation through experimentation have been discussed in this paper.

Detection based long term tracking in correlation filter trackers

Correlation filter based object tracking has recently gained popularity due to continuous improvements in the tracking accuracy and robustness. However, these trackers are limited by the model drift problem due to wrong target appearances learned from an incorrectly tracked frame. The model drift increases as more frames are processed and restricts the ability of long term tracking in correlation filter trackers. The proposed method introduces tracking resumption in correlation trackers using a detector mechanism that re-initializes the tracker upon a target loss identified using an adaptive threshold. Online training of both the tracker and detector modules incorporates temporal information into the proposed framework, making it robust to appearance changes of the object. The tracker and detector stages complement each other in correcting the false appearances learned from any frame, thereby mitigating the model-drift problem. A similarity matching technique estimates the final target location. Extensive experimental analysis on benchmark datasets indicate that the proposed tracker is well suited for robust long-term tracking and is superior to other state of the art methods both qualitatively and quantitatively.

A Single-Phase Dual-Stage PV-Grid System with Active Filtering

<p>Integrating photovoltaic based electricity into the grid and power quality improvement have become two major issues in electrical system. Formerly, these can be solved by using two converter systems separately, a PV-Grid System and an active power filter. But recent technology uses only a converter system to do both function. An existed shunt active power filter (SAPF) can be modified to form a dual-stage PV-Grid with active filtering capability. In this paper, a PV-Grid System that is capable to transfer all power generated by PV modules and reduce harmonic contents is proposed. The system was formed by connecting a boost chopper as a Maximum Power Point Tracker and PV modules to the DC-link capacitor of a single-phase SAPF. It just needed a current transducer and also required simpler control circuits. A voltage controller was needed to achieve power equilibrium while a current controller was needed to make the grid current sinusoidal with unity power factor. To verify the analysis, simulations and experiments were done.</p>

Parametric performance analysis of a concentrated photovoltaic co-generation system equipped with a thermal storage tank

This article presents a parametric study of a concentrated photovoltaic co-generation (CPVC) system with an attached thermal storage tank. The CPVC system utilized dual-axis tracker and multiple solar energy collector (SEC) modules and forced cooling system. Each SEC module comprised 16 triple-junction solar cells, copper tube absorbers, and 16 Fresnel lenses were aligned against each solar cell. This study investigated all possible parameters that can affect the CPVC system performance, including the collector area, solar irradiation, inlet temperature, and mass flow rate. The surface area of the collector and the thermal power were increased by increasing the number of SEC modules connected in series; however, the electrical power output decreased from the first to the fourth SEC module consecutively. At the measured optimal flow rate, mixing and thermal diffusion in the storage tank were decreased, and the total power generation from the CPVC system was increased. Variations in the thermal and electrical power outputs were also observed when the focal length of the Fresnel lens was changed. This parametric analysis enables the CPVC system to obtain the desired output by varying the combination of operational and geometrical parameters.

Hybrid circuit prototypes for the CMS Tracker upgrade front-end electronics

New high-density interconnect hybrid circuits are under development for the CMS tracker modules at the HL-LHC. These hybrids will provide module connectivity between flip-chip front-end ASICs, strip sensors and a service board for the data transmission and powering. Rigid organic-based substrate prototypes and also a flexible hybrid design have been built, containing up to eight front-end flip chip ASICs. A description of the function of the hybrid circuit in the tracker, the first prototype designs, results of some electrical and mechanical properties from the prototypes, and examples of the integration of the hybrids into detector modules are presented.

The flight of the GAPS prototype experiment

The General AntiParticle Spectrometer experiment (GAPS) is foreseen to carry out a dark matter search using low-energy cosmic ray antideuterons at stratospheric altitudes with a novel detection approach. A prototype flight from Taiki, Japan was carried out in June 2012 to prove the performance of the GAPS instrument subsystems (Lithium-drifted Silicon tracker and time-of-flight) and the thermal cooling concept as well as to measure background levels. The flight was a success and the stable flight operation of the GAPS detector concept was proven. During the flight about 106 charged particle triggers were recorded, extensive X-ray calibrations of the individual tracker modules were performed by using an onboard X-ray tube, and the background level of atmospheric and cosmic X-rays was measured. The behavior of the tracker performance as a function of temperature was investigated. The tracks of charged particle events were reconstructed and used to study the tracking resolution, the detection efficiency of the tracker, and coherent X-ray backgrounds. A timing calibration of the time-of-flight subsystem was performed to measure the particle velocity. The flux as a function of flight altitude and as a function of velocity was extracted taking into account systematic instrumental effects. The developed analysis techniques will form the basis for future flights.