Standard Models are like a manual that explains how small particles behave. The Standard Model is brilliant but it’s not finished. The book doesn’t answer questions like why matter and antimatter are more abundant than each other, dark matter, or any of the cosmic mysteries.
Scientists measure particles extremely precisely to discover what is missing. They then compare the results with what Standard Model predicted. It’s like a missing puzzle piece when the numbers do not match. This mismatch may point us to a new form of physics, and give us a more complete picture about how the Universe works.
Imagine that there is a particle called Lambda-cplus (Lc+) which resembles the heavier, cooler cousin of the proton. The particle is made up of three quarks, namely one up, one downward, and one charm. Here’s a twist: This particle only lives for less that a trillionth second. It’s as if you blink, it is gone.
It is impossible to study it because it disappears so fast. This would be like trying photographing a bolt of lightning with a very slow camera. Scientists are racing to determine its properties. They are particularly interested in its electric and magnetic dipole moments. These are tiny fingerprints that show how the object interacts with other forces.
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What is the significance of this? Measuring dipole moments in the past has confirmed big physics theory and revealed some surprises. Charm baryons could be the answer to physicists’ hopes for a small mismatch, which would reveal new physics.
Scientists developed a new method to study short-lived charm baryons. These particles vanish instantly once they are created. The particles are a key to understanding deeper physics. However, measuring the properties of these particles is extremely difficult due to their rapid decay.
Schematics for the TWOCRYST experiment set-up at the time of the first measurements, 21-22 June 2025. First crystal placed on the LHC main beam edge at injection energy of 450 GeV. Target was not included. The first crystal deflected beam particles onto the surface the second crystal where they were deflected again (“double-channelling”). The data from the two detectors on the right shows distinct spots that correspond to particles with single and double channels. Image: Joao Vitori dos Santos, on behalf of TWOCRYST.
Researchers are using two crystals bent in a curved shape to tackle the problem. Scientists typically use magnetic fields to bend particles and measure dipole moments such as the electric or magnetic. Charm baryons degrade so quickly that conventional methods do not work.
Crystals are the answer. In a crystal’s interior, the atoms form a 3D grid that is arranged into tiny channels. When a crystal bend is in the way of charged particles they can slide into the channels, and be deflected like marbles moving through grooves. Scientists can bend the paths of charged particles in such a way that they are deflected, like marbles rolling through grooves.
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Scientists are using a clever new set-up to test a short-lived particle called charm baryons in the TWOCRYST experiments at CERN’s LHC. Two bent silicon crystals are used to measure and guide these particles.
This is how it works. The first crystal, which we call the secondary halo in the picture, gets placed at the edge of a proton beam where the stray particles are usually absorbed. This crystal does not let them waste away, but instead directs them towards a target made of tungsten, where they will collide to produce charm baryons.
Next comes the second stone. The second crystal bends the path of newly formed particles, allowing their dipole moments – tiny, but vital properties – to be measured with a special detector.
The TWOCRYST experiment is designed as a “proof-of-principle” test, which means it will be used to see if the whole concept works. The setup at the LHC was completed earlier this year after only two years planning.
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The experimental setup is an abridged version of the full-fledged experiments, which consists of two silicon crystals bent in a certain direction, a single target and two 2D detectors. (A pixel tracker, and fibre tracker) Pascal Hermes, the study’s leader Pascal Hermes. The goal of the experiment is to see if particles can deflect through two crystals simultaneously – a process called ‘double-channelling.’
TWOCRYST reached a major milestone in June 2025: it was the first time that particles were observed with two channels at the LHC. This observation took place at 450 GeV injection energy. It means that particles have been bent successfully by two crystals, an accomplishment never achieved before at such high energy.
Double channelling allows for unprecedented precision in the study of charm baryons such as Lc+. The decay of these particles is less than one trillionth second. This makes traditional magnetic field techniques ineffective. However, bent crystals are able to induce large deflections within a small space. This makes dipole moments measurements possible.
Now, the team is preparing for multi-TeV tests to push even more boundaries. What is the goal? The goal?
TWOCRYST is already changing the way we view beam control experiments and those with fixed targets, even if it doesn’t become a large-scale project.
Journal Reference
- L. Bandiera, et. al., Performance of long and short bent crystals at the Large Hadron Collider for the TWOCRYST experimental, arXiv (20025). DOI: 10.48550/arxiv.2505.14365
