The Large Hadron Collider (LHC) at CERN is where the miraculous meets the impractical. In addition to probing the secrets of the Universe at the subatomic level, it also has potential for a variety of medical applications. Unfortunately, with a circumference of 27 km (16.7 mi) the LHC is so unwieldy that it would be about as practical as using Big Ben for a wristwatch. In the hopes of creating something a bit more useful for the medical fraternity, CERN engineers have come up with a miniature linear accelerator (mini-Linac) that, at 2 m (6.5 ft) long, is small enough to be set up in hospitals for medical imaging and radiotherapy applications.

Designed primarily for medical applications, the mini-Linac is based on the Linac4 accelerator, which is a large accelerator that is set to become part of the the CERN accelerator complex in 2020 and will be used to boost negative hydrogen ions to high energies.

The mini-Linac is a radiofrequency quadrupole (RFQ), which is a common form of accelerator component used at the start of all proton accelerator chains to produce high-intensity beams. CERN says that the trick was to double mini-Linac's operating frequency to a never-before achieved level, so its length could be shortened. This required new beam dynamics, and new ideas about the radiofrequency and mechanical aspects.

The device itself is made up of four 50-cm (19.6-in)-long modules, the first of which has already been completed. According to Serge Mathot of the CERN engineering department, this first segment represents a very important milestone because it validates both the concept and all stages of the device's construction.

In operation, the mini-Linac can create low-speed, low-intensity beams that are grouped at the frequency of 750 MHz and have an energy of 5 MeV at a range of 2 m. This allows it to act as an injector for high-frequency, compact linear accelerators for treating cancer with protons, or as a source of alpha particles for advanced radiotherapy.

CERN says that the compact, lightweight device can also be used to create a wide range of radioisotopes on the spot in hospitals, so there's no need to worry about transporting them and all the security and logistical problems that involves. In addition. It can also be more easily transported for field applications, such as analyzing archeological finds.

CERN is currently working on completing assembly of the four modules, which is scheduled for completion early next year.