Particle accelerators in some cases can provide effective treatment for cancer and other oncological diseases, but, as a rule, accelerators capable of accelerating particles to high energy are huge, complex, and expensive installations. The SLAC accelerator, for example, has a length of 3.2 kilometers, and in the largest and most powerful accelerator, the Large Hadron Collider, protons move inside a 27-kilometer ring tunnel. However, scientists at Stanford University were able to “compress” particle acceleration technology so that the accelerator they created fits on a semiconductor chip, which, in theory, should contribute to the widest use of this device in the near future.
In conventional accelerators, particles are fed into vacuum channels, where they accelerate to extremely high speeds. In the SLAC accelerator, all this is done using microwave emitters, and the collider uses huge electromagnets with superconducting windings.
Work aimed at miniaturizing particle acceleration technologies has been underway for quite some time. At one time, specialists at the European Organization for Nuclear Research CERN managed to create a working prototype of the accelerator, about 2 meters in size. And now, as mentioned above, scientists from Stanford University and the SLAC laboratory managed to fit an entire accelerator on the surface of a silicon semiconductor chip.
In this accelerator-on-chip, electrons are emitted into the vacuum channel, which has a length of 30 micrometers, which is less than the thickness of a human hair. Instead of microwave emitters or electromagnets, the new accelerator does its job with the help of infrared light coming through silicon channels and optical fibers. An infrared laser emits pulses with a frequency of 100 thousand times per second, light photons hit the electrons at a right angle, which causes them to accelerate in the right direction.
In its current form, the accelerator-on-chip is not yet ready for practical use, it is only a device designed to confirm the operability of miniature particle acceleration technologies. At the moment, the accelerator is capable of providing a flow of electrons with an energy of 0.915 keV (kiloelectron-volts), which is a thousand times weaker than necessary for the use of the accelerator for research and medical purposes.
But by the end of the year, Stanford scientists aimed at “taking the bar” at 1 MeV (megaelectron-volt). At the same time, everything will be done very simply, the length of the acceleration channel will be increased by 1000 times and the energy of accelerated electrons will increase by the same amount. An accelerator with an extended channel will grow in size, but it will still fit on the surface of the chip, 2.5 centimeters long.
When researchers create a new accelerator-on-a-chip, it will immediately find practical application. The accelerator chip can be inserted directly into the patient’s body in the right place, and the stream of high-energy electrons produced by it will be directed precisely to the malignant region and will begin to affect cancer cells without touching the adjacent healthy tissue cells.