Development of Pixelated Capacitive-Coupled LGAD (ACLGADpix) Detectors

Abstract

The Low-Gain Avalanche Diode (LGAD) is a semiconductor detector capable of achieving excellent timing resolution (~20 ps) for minimum ionizing particles (MIPs). To realize a pixelated detector with both high timing precision and spatial resolution, we have been developing Capacitive-Coupled LGADs (ACLGADs) for future collider experiments, such as the latter phase of the High-Luminosity LHC. We have successfully fabricated a pixelated ACLGAD (ACLGADpix) with a 100 $μ$m %\times% 100 $μ$m pixel pitch, maintaining uniform timing performance across the active area. In this presentation, we will report recent measurement results from ACLGADpix prototypes using beta rays, an infrared laser, and a 3 GeV electron beam. We will also discuss potential readout electronics for future collider applications.

Figures (6)

• Figure 1: Comparison of the structures of a conventional segmented LGAD (top) and an AC-LGAD (bottom). In the AC-LGAD, the gain layer is continuous over the full active area and the signal is read out through AC-coupled segmented electrodes.
• Figure 2: Experimental setup for the $^{90}$Sr beta-ray measurement. An MCP-PMT is used as the timing reference.
• Figure 3: Timing resolution measured with a $^{90}$Sr beta-ray source for a 20 $\text{\textmu m}$-thick, 100 $\text{\textmu m}$-pitch AC-LGAD pixel sensor.
• Figure 4: Detection-efficiency map for a 100 $\text{\textmu m}$-pitch AC-LGAD pixel sensor measured at the KEK AR test beam line.
• Figure 5: Residual distributions in the $x$ and $y$ directions for the pixelated AC-LGAD detector.