Protons, muons, neutrinos and other particles are moving beyond the realm of physics to help in a...
Researchers are increasingly turning to protons, neutrons, muons and neutrinos as tools for precisely targeting tricky tumors, probing fossils and volcanoes and revealing the hidden structures of Earth, among an ever expanding list of applications.
Doctors can tune beams of protons to precisely destroy specific targets, usually cancerous tumors, without harming nearby organs-unlike x-rays and gamma rays, which have historically been the go-to beams for cancer therapy.
Proton beams, on the other hand, do comparatively little damage to tissue in front of a tumor and none to tissue behind it, thanks to the way protons lose energy as they pass through material, including the human body.
Researchers are investigating radiation therapy that relies on electrically charged carbon atoms, which contain six protons and six neutrons, making them much more massive than individual protons.
Neutrons are similar in mass to protons but lack electric charge.
Neutrons have a history of use in cancer treatment but have lost ground to proton beams since the 1990s.
The leading sources of imaging neutrons include nuclear reactors and particle accelerators, which aim high-energy protons at targets to knock neutrons loose from atoms of heavy metals such as tungsten or mercury.
The rays are primarily protons that come from the sun or originate in deep space.
The first practical application of particles from cosmic rays dates back to the 1950s, when Australian engineers rolled a muon detector along a tunnel that would eventually guide water to the power station associated with the Guthega Dam in New South Wales.
Neutrinos probe far deeper than muons because they lack electric charge; they are not swerved off their paths by electrically charged protons and electrons in atoms.