Anti-Matter Trapped: CERN Scientists at ALPHA Trap Anti-Matter For Record 1000 Seconds

Some people might liken it to the situation described in Dan Brown’s novel Angels and Demons. CERN scientists trapped ┬ádangerously slippery anti-matter for a record 1000 seconds (or 17 minutes), a huge achievement in terms of anti-matter confinement.

This remarkable feat was achieved by scientists working on the Anti-hydrogen Laser Physics Apparatus (ALPHA). 1000 seconds is a huge improvement (almost 4 orders of magnitude greater) than the previous best, of 172 millisecond (i.e. 0.172 s). This new trapping ability will allow physicists to design new experiments that take a closer look at the properties of anti-matter. Theoretically, anti-hydrogen should occupy the same quantum energy levels as normal hydrogen, but this has never been theoretically confirmed. Also this will settle many long standing problems like Baryon Asymmetry and give insights into CP violation, or even CPT violation. There is also hope of cooling these anti-atoms to temperatures low enough so that gravitational effects become significant.

ALPHA Facility
An Overview of the ALPHA facility

Confining neutral (or even charged) particles cannot be done using electric fields. Magnetic fields are used. A Penning trap is used to produce and hold the anti-hydrogen produced. These are then held in a magnetic field with a three-dimensional minimum. (See figure)

Simulation as to how a magnetic trap potential looks. (Made by author using Wolfram Mathematica)
This shows the basic layout. Notice the streams of positrons and anti-protons fired from the two sides, which form anti-hydrogen. A magnetic field of 1T (which is HUGE) is applied by means of an external solenoidal coil (not shown here). Silicon detector line the wall of the trap. (Courtesy: Arxiv paper)
This shows the cross-section of the field profile. (A): A longitudinal cross-section is taken. The bright lines represent field of a certain strength. (B): The transverse cross-section is taken. (Courtesy: Arxiv paper)

It is clear that deeper the well (see the second figure from the top), lesser is the probability of the atoms escaping. The ALPHA collaboration has gone up to 309 atoms from a measly 38 that it started off with. Most anti-hydrogen atoms were in their ground state as expected.

An exciting question is whether anti-matter is attracted or repelled by gravity i.e. whether it should fall up or down. (By all means, physicists expect it to fall down! Nature is not that asymmetric. However, enough anti-matter has not been observed to fall down or up.)

We’ll just have to wait and watch.

Published by

Debjyoti Bardhan

Is a science geek, currently pursuing some sort of a degree (called a PhD) in Physics at TIFR, Mumbai. An enthusiastic but useless amateur photographer, his most favourite activity is simply lazing around. He is interested in all things interesting and scientific.