Time Trap: A Detector with Picosecond Precision ✛ ✎

Original: "Design and optimisation of radiation resistant AC- and DC-coupled resistive LGADs"
arXiv:2505.05642 · 2025-05-08 · arXiv non-exclusive · independent analysis · 1 min
New detector pinpoints the time and location of a particle hit with exquisite precision: 38 picoseconds and 15 micrometers.

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.

38 picoseconds is the time it takes light to travel just over a centimeter. In other words, the detector can distinguish events separated by the width of a fingernail.

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.

Now the detector resembles a perfect musical instrument: the slightest touch of a particle resonates instantly and uniformly, allowing scientists to rhythmically track the birth and death of subatomic particles.

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.

Scientists
Emmy NoetherBernhard RiemannJoseph WeberKarl SchwarzschildKip ThorneRainer Weiss
Concepts
gallium arsenide lidar remote sensing precision photometry