Detectors for High-Energy Physics

High energy physics demands advanced detection technologies capable of operating in extreme environments with unprecedented precision.

Our group develops next-generation silicon detectors for future collider experiments, including monolithic sensors for lepton colliders, radiation-hard hybrid and monolithic designs, and fast-timing sensors such as LGADs.

We also adapt HEP technologies – such as Timepix-based readouts – for visible light detection in novel imaging applications.

Our work spans sensor design, TCAD and Allpix simulations, and extensive testbeam campaigns.

We collaborate closely with universities, industrial partners, and CERN through the DRD3 initiative, and contribute to inner tracker development and testing for the ePIC detector at the Electron-Ion Collider.

Next-generation colliders such as the High Luminosity LHC require detectors capable of fast timing and sustained operation under extreme radiation. Silicon Carbide (SiC), a wide-bandgap semiconductor, is well-suited to these demands due to its high charge carrier mobility, thermal stability, and superior radiation hardness. Our research focuses on developing SiC-based particle sensors for charged particle tracking and UV photon detection in harsh environments.

Specifically, we investigate Low Gain Avalanche Detectors (LGADs) implemented in 4H-SiC. LGADs feature a doped gain layer that introduces moderate internal signal amplification, enabling excellent time resolution (<50 ps) in silicon-based devices. By adapting this architecture to SiC, we aim to combine fast timing with enhanced longevity and radiation tolerance.

We are involved in the full development chain: simulating electric field profiles in TCAD, optimizing fabrication of the gain layer in SiC, and performing laboratory and beamline characterization. Initial prototypes demonstrate timing resolutions on the order of tens of picoseconds, with significantly improved radiation hardness over silicon counterparts. This work paves the way for timing detectors capable of withstanding the operational challenges posed by future high-luminosity experiments.

KEY TASKS

Radiation-hard SiC LGAD design and fabrication: we engineer 4H-SiC wafers and model their gain layers in TCAD to realise thin (30-100 µm) low-gain avalanche detectors that survive >10¹⁶ n eq cm⁻² while preserving internal gain.

Precision timing & irradiation studies: prototype sensors are characterised with laser and test-beam setups, targeting sub-50 ps timing precision, then re-measured after high-fluence irradiation campaigns to map performance versus dose.

We are actively developing monolithic pixel detectors, where both the sensing element and readout electronics are integrated into a single silicon die using CMOS imaging technology. Compared to traditional hybrid detectors, Monolithic Active Pixel Sensors (MAPS) offer lower material budget, reduced cost, and the potential for very fine pixel pitch with in-pixel processing.

Our group contributes to the full design chain – including front-end architecture, digital logic, and sensor layout – as well as simulation and characterization of prototypes.

We are key contributors to the OCTOPUS project (“Optimized CMOS Technology fOr Precision in Ultra-thin Silicon”), part of CERN’s DRD3 initiative. OCTOPUS aims to develop high-performance MAPS for future lepton colliders like FCC-ee, targeting ultra-thin sensors (<50µm), fine spatial resolution (~3µm), precise timing (~5ns), low power consumption (<50mW/cm²), and minimal dead area. We are designing 65nm CMOS sensors optimized for these specifications, addressing the extreme demands of next-generation vertex detectors.

KEY TASKS

Ultra-thin 65 nm TPSCo CMOS pixels: we work on design of <20 µm-pitch pixels that handle analogue-to-digital conversion of signal integrate charge collection, amplification and 5 ns time-stamps in a single chip thinned to less than 50 µm, minimising material for future lepton-collider vertex layers.

Simulations and beam validation: we work on lab and beam test verification of the produced detectors, focusing on spatial and timing precision and we also use Allpix² to verify the performance.

The Electron-Ion Collider (EIC) at Brookhaven National Laboratory will probe the structure of nuclear matter by colliding electrons with protons and nuclei. Its primary detector, ePIC, features a cutting-edge silicon tracking system designed for high-resolution tracking in a challenging, high-rate environment. Our group is contributing to the development and testing of the silicon vertex and tracking detectors, with a focus on the innermost layers.

The ePIC Silicon Vertex Tracker (SVT) employs ultra-thin MAPS sensors in a 65nm CMOS process, derived from ALICE ITS3 technology. These wafer-scale sensors are thinned to below 50μm and bent around the beam pipe to form a low-mass, cylindrical vertex detector. This curved design minimizes material and multiple scattering, enabling precise vertex reconstruction. We are involved in laboratory characterization using probe stations, as well as beam test campaigns for evaluating prototype performance and adapting it for the new system.

KEY TASKS

Sensor characterization: we are involved in the laboratory testing of the CE-65 sensor prototype developed in the 65nm TPSCo CMOS process, which is also used for ALICE ITS3 and ePIC. The CE-65 focuses on the characterisation of the analogue charge collection properties of this technology. We carry out laboratory irradiation using an Fe-55 source, participate in test beam campaigns, and work on the analysis of the data from these irradiations.

Preparation of the production wafer probing setup for sensors: our group is contributing to the preparation of the production testing setup for MAPS sensors intended for the ePIC inner tracking detector, using an automated 12-inch probe station.

Development of the general software framework for sensor testing: the framework includes a user interface, communication protocol, hardware and control agents for operating the test equipment, and a database for storing measurement results.

Irradiation testing: we arrange irradiation of sensors and ancillary circuits using a Cobalt-60 source and a proton beam to determine their radiation hardness.

Beyond high-energy physics, we adapt developed pixel detector technologies to other scientific domains. A key example is our work with the Timepix3 readout chips developed by the CERN-lead Medipix/Timepix collaborations. These ASICs operate in event-driven mode, enabling nanosecond-resolved detection of individual photons or charged particles with high spatial and temporal precision. They can be used with a variety of sensor types including optical silicon sensors.

In velocity-map imaging (VMI) for atomic and molecular physics, Timepix and Timepix3 enable 3D reconstruction of ion velocities by recording both hit position and precise time-of-arrival per event using fast optical flashes produced by ions. The time-of-flight with respect to the laser pulse allows then to detemine the ion mass. The Timepix3 ASIC, with its ~1.6ns timestamping resolution and high-rate, data-driven readout, is particularly well suited for single-shot experiments involving ultrafast dynamics.

We are also investigating Timepix applications in neutrino and rare-event detectors, where fast and low-noise optical photon detection is critical. Unlike traditional photomultiplier tubes, Timepix allows high-resolution spatial and temporal discrimination of multiple photons within the same sensor plane—opening new possibilities for optical readout in large-scale detectors.

Beyond these, we explore the use of Timepix in direct electron beam imaging for microscopy, where thin radiative layers or a Cherenkov radiator convert high-energy electrons into detectable light or secondary electrons. This enables precise mapping of beam profiles or intensity distributions with high spatial fidelity, expanding Timepix utility into accelerator diagnostics and materials science.

KEY TASKS

Nanosecond-resolved optical VMI cameras for ion imaging: by coupling MCPs to Timepix3 ASICs (TPX3Cam) we capture single-shot velocity-map images at MHz repetition rates, recording both hit positions and 1.6 ns time-stamps for full 3-D momentum reconstruction.

Optical readout of large volume detectors: ionization created by neutrino interactions in a large 3D volume detectors can be collected and amplified in a 2D gaseous detector. We are investigating schemes of optical readout of such detectors using the optical Timepix3 camera, which has adjustable field of view and simultaneously provides x,y,t information for 3D track reconstruction.

Electron microscopy: we are testing novel approaches to electron detection in transmission electron microscopy by recording Cherenkov photons emitted by electrons in a sapphire radiator. Fast optical camera with ns resolution based on Timepix3 allows to reconstruct position and timing of electrons with good precision avoiding placing electronics into the direct electron beam.