Ultra fast semiconductor sensors for precision timing and tracking applications

• Grant number: 25/03411-9
• Support Opportunities: Regular Research Grants
• Start date: July 01, 2025
• End date: May 31, 2027
• Field of knowledge: Physical Sciences and Mathematics - Physics - Elementary Particle Physics and Fields
• Mobility Program: SPRINT - Projetos de pesquisa - Mobilidade
• Principal Investigator: Marco Aurelio Lisboa Leite
• Grantee: Marco Aurelio Lisboa Leite
• Principal researcher abroad: Mei Zhao
• Institution abroad: Institute of High Energy Physics, Chinese Academy of Sciences, China
• Principal researcher abroad: Zhijun Liang
• Institution abroad: Institute of High Energy Physics, Chinese Academy of Sciences, China
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 20/04867-2 - High energy physics and instrumentation with the LHC-CERN, AP.ESP

Abstract

To answer the quest for high precision measurements in a high luminosity environment at the Large Hadron Collider (LHC), a comprehensive upgrade of the detector and associated systems was devised and are on-going, and a key element is the ability to perform the tracking of particles in four dimensions (4D). This new idea will enable the experiments to mitigate the pileup arriving from more than 200 simultaneous collisions per bunch crossing, -which happens at every 25 ns - by adding precision timing information to the track-vertex association during the event reconstruction. However, this timing must be measured with a precision of a few tens of picoseconds, a feat only recently achieved by the development of the state-of-the-art ultra-fast silicon detectors, whose most prominent example is found in the Low Gain Avalanche Diodes (LGAD). However, one limitation of the LGADs is the size of the device readout pad, which must be many times larger than the gain layer thickness (in the order of 1 or 2 micrometers) in order to keep the electrical field uniform, limiting the sensitive pads of sensor arrays to millimetric sizes. To overcome the current constraint from LGAD geometry, new topologies of Resistive LGADS, AC-coupled LGADs and trench-isolated (TI) LGADs have recently been proposed. Recent prototypes of these devices have achieved spatial resolution of 10 micrometers or less, while retaining the excellent timing characteristics of LGADs. Having precise picosecond timing sensors with a few micrometres spatial resolution will enable the experiments proposed for the future colliders to perform particle identification across all the rapidity coverage. Moreover, one very important spin-off from the LGAD development is the potential use for time-resolved synchrotron applications. The internal gain of LGADs enables them to detect very low X-rays energies (1 keV or less) while still keeping an excellent signal-to-noise ratio. The beam structure of the fourth generation synchrotrons (like the Sirius in São Paulo and HEPS in Beijing) are very short (picosecond) high repetition rate (500MHz) photon pulses, enabling these machines to reach a very high brilliance for the soft X-rays region. Detecting these photons requires sensors with a few picosecond timing response, internal charge amplification and micrometric spatial segmentation, challenges that are exactly aligned with the LGAD developments for HL-LHC and beyond. In this area, there is already a strong collaboration between the Sirius and USP groups in São Paulo and HEPS and IHEP groups in Beijing, in a multidisciplinary effort for instrumentation development that will provide the members of this collaboration access to leading-edge national scientific facilities, which is further enhanced by CERN through the recently formed DRD3 collaboration, in which the groups of this proposal participate. The developments of this project will have an impact on the ATLAS HGTD project supported by the current FAPESP project, as the experience gained in the fabrication and process, simulation tools and data analysis can very well be used for the HGTD integration and commissioning phase. Moreover, the study of sensors for new synchrotron light sources is also one of the main goals of the associated special project at USP and also a main topic of interest for the IHEP group in their collaboration with HEPS. (AU)