Periodic Reporting for period 3 - MONOLITH (Monolithic Multi-Junction Picosecond Avalanche Detector for future physics experiments and applications)
Reporting period: 2023-07-01 to 2024-12-31
Particle-physics and other fields of basic and applied science necessitate the production of thin sensors capable to provide excellent measurement of both position and time.
This project introduces a novel silicon-sensor structure, the patented monolithic Picosecond Avalanche Detector (PicoAD), devised to provide simultaneously picosecond timing and high spatial resolution, thus overcoming the intrinsic limits of present sensors. The remarkable performance simulated for this new sensor, combined with the simplified assembly process and reduced production cost offered by the monolithic implementation in standard CMOS processes, represent the required breakthrough. The PicoAD will offer a sustainable solution for the next generation of experiments at hadron colliders, in nuclear physics and for space-borne experiments in cosmic-ray physics and solar physics. Besides the primary goal of basic science, it will represent a technology that will enable a large spectrum of high-tech applications that benefits of picosecond-level Time-Of-Flight measurements.
The innovative monolithic detector introduced here will also offer a starting point for further progress in the field of light detection, for example to produce more performing Lidars or reduce the dose exposition of patients during X-ray medical imaging.
This project introduces a novel silicon-sensor structure, the patented monolithic Picosecond Avalanche Detector (PicoAD), devised to provide simultaneously picosecond timing and high spatial resolution, thus overcoming the intrinsic limits of present sensors. The remarkable performance simulated for this new sensor, combined with the simplified assembly process and reduced production cost offered by the monolithic implementation in standard CMOS processes, represent the required breakthrough. The PicoAD will offer a sustainable solution for the next generation of experiments at hadron colliders, in nuclear physics and for space-borne experiments in cosmic-ray physics and solar physics. Besides the primary goal of basic science, it will represent a technology that will enable a large spectrum of high-tech applications that benefits of picosecond-level Time-Of-Flight measurements.
The innovative monolithic detector introduced here will also offer a starting point for further progress in the field of light detection, for example to produce more performing Lidars or reduce the dose exposition of patients during X-ray medical imaging.
The first monolithic chip prototype containing the multi PN-junction PicoAD (patented) sensor and very fast and low-noise electronics was produced. The sensor is fully functional. It was extensively tested at the UNIGE cleanroom facilities using radioactive sources and in a beam line at CERN. An average time resolution of (17 ± 1) ps (13ps at the center of the pixel and 25ps in the inter-pixel region where the signal is shared between 2 or 3 pixels) has been measured, which represents an excellent first result.
In parallel, a standalone chip containing a TDC (electronics circuitry for time measurement) realised according to a novel design developed and patented by the team demonstrated to be able to measure time with picosecond precision as needed for the MONOLITH project.
A second PicoAD prototype was produced in 2022, which features improved sensor and electronics.
A first version with a sensor without internal gain layer provided full efficiency and time resolutions down to 20 ps. Several samples were irradiated in a cyclotron up to proton fluence of 10^16 new/cm2. The detector works even at this huge fluence; testbeam measurements proved that time resolution rises from 20ps (unirradiated) to 45ps (10^16 new/cm2), with a small increase of the sensor bias voltage from 200 V to 300 V.
Prior to the production of a PicoAD version with this new electronics, detailed simulations were performed to establish the exact layering of the silicon wafer to be realised. Several flavours of the PicoAD were produced, with the absorption epilayer of 3 and 5 µm, the drift epilayer of 15 and 25 µm, and four different implant doses for the gain layer. The detectors work. So far, the performance of the PicoAD version with 5µm+15µm layers and the highest implant dose was measured in a testbeam at CERN. The detector is fully efficient and provides a time resolution of 12 ps.
In parallel, a standalone chip containing a TDC (electronics circuitry for time measurement) realised according to a novel design developed and patented by the team demonstrated to be able to measure time with picosecond precision as needed for the MONOLITH project.
A second PicoAD prototype was produced in 2022, which features improved sensor and electronics.
A first version with a sensor without internal gain layer provided full efficiency and time resolutions down to 20 ps. Several samples were irradiated in a cyclotron up to proton fluence of 10^16 new/cm2. The detector works even at this huge fluence; testbeam measurements proved that time resolution rises from 20ps (unirradiated) to 45ps (10^16 new/cm2), with a small increase of the sensor bias voltage from 200 V to 300 V.
Prior to the production of a PicoAD version with this new electronics, detailed simulations were performed to establish the exact layering of the silicon wafer to be realised. Several flavours of the PicoAD were produced, with the absorption epilayer of 3 and 5 µm, the drift epilayer of 15 and 25 µm, and four different implant doses for the gain layer. The detectors work. So far, the performance of the PicoAD version with 5µm+15µm layers and the highest implant dose was measured in a testbeam at CERN. The detector is fully efficient and provides a time resolution of 12 ps.
The project aims at providing a low-noise, low-power and ultra-fast electronics able to process signals with picosecond resolution.
This electronics will be produced in standard CMOS processes and implemented in the same wafer of a very fast sensor (patented) in a "monolithic" implementation, therefore allowing for simplified assembly process and reduced production cost.
The sensor and the electronics will be radiation tolerant, in order to be used in particle and nuclear physics experiments as well as in medical and space applications.
This electronics will be produced in standard CMOS processes and implemented in the same wafer of a very fast sensor (patented) in a "monolithic" implementation, therefore allowing for simplified assembly process and reduced production cost.
The sensor and the electronics will be radiation tolerant, in order to be used in particle and nuclear physics experiments as well as in medical and space applications.