• Nuclear, Particle, Astroparticle and Cosmology (NUPAC) Seminars

April 14, 2026 2:00 PM
PAIS 3205

Host:

Svende Braun

Presenter:

Simone Mazza (UCSC)

Low-Gain Avalanche Detectors (LGADs) are silicon detectors with modest internal gain (up to ~50) that allow the sensor to be very thin (20 - 50 um). LGADs are characterized by an extremely good time resolution (down to 17ps), a fast rise time (~500ps), and a very high repetition rate (~1ns full charge collection). These devices are relatively new (<10 years since the first prototype) but will be perfect candidates in several near-future applications thanks to their properties.

For the application of this technology to near-future experiments such as e+e- Higgs factories, EPIC, or smaller experiments (e.g., the PIONEER experiment), the first issue to be addressed is the intrinsic low granularity of LGADs and the large power consumption of readout chips for precise timing. For these applications, the pile-up density is low, and the radiation damage is not an issue. AC-coupled LGADs, where the readout metal is AC-coupled through an insulating oxide layer, could solve both issues at the same time thanks to the 100% fill factor and charge-sharing capabilities. Charge sharing between electrodes allows a hit position resolution that is well below the pitch/srqt(12) of standard pixel detectors. At the same time, it relaxes the channel density and power consumption requirements of readout chips. Furthermore, recent results with very thin (20 um) AC-LGADs show exceptional timing resolution.

Furthermore, the first prototypes of LGADs produced a few years ago within the collaborations did not show sufficient radiation hardness. However, LGADs with radiation hardness up to a fluence of 2.5E15 Neq/cm² were developed in the last 5 years thanks to a focused R&D effort. This successful development paves the path for next-generation machines (e.g., FCC-hh) that will require radiation tolerance an order (or more) of magnitude greater and, at the same time, require better timing and position resolution. The cited requirements are in a high pile-up environment that is not suitable for AC-LGADs, which is the most advanced high-granularity LGAD prototype.

Several new LGAD prototypes are geared towards satisfying all of these requirements, as well as radiation hardness. This contribution will give a brief overview of them and the path forward in their development. In the same scope, electronics and integration development are necessary to reduce the power dissipation requirement and increase the channel density. Finally, the need for blue-sky (not tied to experimental application) R&D for timing detectors will be highlighted.