Spallation

In nuclear physics, spallation is the process in which a heavy nucleus emits numerous nucleons as a result of being hit by a high-energy particle, thus greatly reducing its atomic weight.

Spallation can occur when a tensile stress wave propagates through a material and can be observed in flat plate impact tests.

This fragment known as "spall" acts as a secondary projectile with velocities that can be as high as one third of the stress wave speed on the material.

Laser induced spallation is a recent experimental technique developed to understand the adhesion of thin films with substrates.

Due to the non-contact application of load, this technique is very well suited to spall ultra-thin films (1 micrometre in thickness or less).

Nuclear spallation from the impact of cosmic rays occurs naturally in Earth's atmosphere and on the surfaces of bodies in space such as meteorites and the Moon.

Evidence of cosmic ray spallation is seen on outer surfaces of bodies and gives a means of measuring the length of time of exposure.

Cosmogenic isotopes of aluminium, beryllium, chlorine, iodine and neon, formed by spallation of terrestrial elements under cosmic ray bombardment, have been detected on Earth.

Nimrod was uncompetitive for particle physics so it was replaced with a new synchrotron, initially using the original injectors, but which produces a highly intense pulsed beam of protons.