An electron is a different elementary particle than a neutron, with lighter mass and a negative charge. In neutron therapy, a beam of neutrons is targeted at a tumor that has been injected with the chemical boron, a nonradioactive isotope. The neutrons cause the boron nuclei to split, releasing alpha particles that damage surrounding cells. The path length of alpha particles is the diameter of a few cells, much shorter than the path length of electrons. Gamma rays often wander around in the healthy tissue, Grimes says.
Neutrons don t go very far once they hit matter.
Neutron beams used in these kinds of experiments are created with a machine called an accelerator. What makes the university s accelerator unique are recent technological additions that allow it to measure the speed and number of neutrons with new levels of precision. In 1981, a 100-foot culvert was built into the side of a hill next to the university s accelerator laboratory. The culvert allows researchers to meas ure how long it takes neutrons to travel a certain distance. Using this technology, researchers can determine the correct amount of neutrons and the speed of neutrons needed to treat certain types of cancers and tumors, Grimes says.