Time Trap: A Detector with Picosecond Precision ⚡ экспресс
For future experiments, radiation-hard detectors with high spatial and temporal resolution are needed. Previously developed resistive LGADs (Low Gain Avalanche Diode) with AC coupling achieved a time resolution of 38 ps and spatial resolution of 15 µm at a pixel pitch of 450 µm, but exhibited non-uniform response across the surface. To solve this problem, a version with DC-coupled contacts was created. Modeling in Synopsys Sentaurus TCAD formed the basis for the design of the first batch, produced by Fondazione Bruno Kessler in November 2024. The paper presents simulation results and a brief overview of the development of AC prototypes. The new approach aims to improve the uniformity and reliability of detectors for future colliders.
In particle accelerators, where matter is smashed into elementary constituents, detectors need filigree precision. Engineers have built a device that resembles a uniformly stretched drumhead: each particle strike produces an instant and clear signal. This allows them to record time with an accuracy of 38 picoseconds, and coordinates down to 15 micrometers.
Early versions suffered from uneven sensitivity: some areas 'sounded' loud, others barely audible. The culprit was an insulating layer that, like a thick glove, muffled and distorted the signal. The unexpected solution turned out to be simple: the contact was made direct (DC coupling), without an insulating interlayer. So the 'glove' was removed, and the membrane rang out equally pure across its entire surface.
These detectors will become the eyes of next-generation facilities. Scientists will use them to test the Standard Model for cracks, looking for the tiniest deviations. The improved sharpness will help spot rare events and, perhaps, uncover new forces that govern the Universe.
🎯 A picosecond is one trillionth of a second. In 38 picoseconds, light travels about 1.14 centimeters—slightly more than the width of your pinky finger.
🎬 Perhaps one day, a network of such detectors will form the basis of a ‘chronovisor’ that records events with picosecond detail.