Physicists Spot Double Crystal Channeling for the First Time

By Amit Malewar Published: August 30, 2025

Collected at: https://www.techexplorist.com/physicists-spot-double-crystal-channeling-first-time/100810/

The Standard Model is akin to an instruction manual for understanding how tiny particles behave. It’s brilliant, but not complete. It doesn’t explain why there’s more matter than antimatter, what dark matter is, or other cosmic mysteries.

To uncover what’s missing, scientists measure particles with extreme precision. Then they compare those results to what the Standard Model predicts. If the numbers don’t match, it’s a clue, like finding a puzzle piece that doesn’t fit. That mismatch could point to new physics and help us build a better, fuller picture of how the Universe truly works.

Imagine a particle that’s like the proton’s cooler, heavier cousin—it’s called the Lambda-c-plus (Λc⁺). It’s made of three quarks: one up, one down, and one charm. But here’s the twist: this particle lives for less than a trillionth of a second. Blink, and it’s gone.

Because it vanishes so quickly, studying it is like trying to photograph a lightning bolt with a slow camera. Yet scientists are racing to measure its properties, especially its magnetic and electric dipole moments, which are like tiny fingerprints of how it interacts with forces.

Why does this matter? In the past, measuring dipole moments has helped confirm big physics theories, and sometimes, revealed surprises that didn’t fit the rulebook. That’s precisely what physicists are hoping for with charm baryons: a tiny mismatch that could point to new physics hiding in plain sight.

Physicists have come up with a clever new way to study charm baryons, short-lived particles that vanish almost instantly after being created. These particles hold clues to deeper physics, but measuring their properties is incredibly difficult because they decay in less than a trillionth of a second.

To tackle this, researchers are using a setup involving a fixed target and two bent crystals. Typically, scientists utilize magnetic fields to bend particle paths and measure properties such as electric and magnetic dipole moments. However, charm baryons decay so rapidly that traditional methods are ineffective.

That’s where crystals come in. Inside a crystal, atoms are arranged in a precise 3D grid, forming tiny channels. If a bent crystal is placed in the path of charged particles, those particles can slip into these channels and get deflected, like marbles rolling through grooves. This allows scientists to bend their paths sharply enough, in a very short distance, to measure their properties before they disappear.

In the TWOCRYST experiment at CERN’s LHC, scientists are testing a smart new setup to study short-lived particles called charm baryons. The system uses two bent silicon crystals to guide and measure these elusive particles.

Here’s how it works: The first crystal is placed near the edge of the proton beam, where stray protons, called the secondary halo, usually get absorbed. Instead of letting them go to waste, this crystal redirects them toward a tungsten target, where they collide and produce charm baryons.

Then comes the second crystal. It bends the paths of the newly created particles just enough so that their electric and magnetic dipole moments, tiny but essential properties, can be measured by a special detector.

TWOCRYST is a proof-of-principle experiment, meaning it’s designed to test whether this whole idea actually works. After just two years of planning, the setup was installed at the LHC earlier this year.

“The experimental setup is a simplified version of a full-fledged experiment, consisting of two bent silicon crystals, a target, and two 2D detectors (a pixel tracker and a fibre tracker),” explains TWOCRYST study leader Pascal Hermes. “One goal is to verify if the particles can be deflected through both crystals in sequence – the so-called ‘double channelling’.”

In June 2025, TWOCRYST achieved a significant milestone: the first-ever observation of double-channelled particles at the LHC, and at an injection energy of 450 GeV, no less. This means particles were successfully bent by two crystals in sequence, a feat never before accomplished at such high energies.

This double channelling is crucial because it allows researchers to study charm baryons like the Λc⁺ with unprecedented precision. These particles decay in less than a trillionth of a second, making traditional magnetic field methods ineffective. But bent crystals can induce strong deflections in a tiny space, making dipole moment measurements feasible.

The team is now gearing up for tests at multi-TeV energies, pushing the boundaries even further. The goal? To see if enough deflected charm baryons can be collected to justify scaling up to a full-blown experiment.

Even if TWOCRYST doesn’t evolve into a full-scale project, it’s already reshaping how we think about beam control and fixed-target experiments.

Journal Reference:

1. L. Bandiera et al, Performance of short and long bent crystals for the TWOCRYST experiment at the Large Hadron Collider, arXiv (2025). DOI: 10.48550/arxiv.2505.14365