A beam dump, also known as a beam block, a beam stop, or a beam trap, is a device designed to absorb the energy of

photon A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are Massless particle, massless ...

s or other

particles In the physical sciences, a particle (or corpuscule in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, from ...

within an energetic beam.

Types of beam dumps

Beam blocks

Beam blocks are simple optical elements that absorb a beam of light using a material with strong

absorption Absorption may refer to: Chemistry and biology *Absorption (biology), digestion **Absorption (small intestine) *Absorption (chemistry), diffusion of particles of gas or liquid into liquid or solid materials * Absorption (skin), a route by which ...

and low

reflectance The reflectance of the surface of a material is its effectiveness in Reflection (physics), reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the respon ...

. Materials commonly used for beam blocks include certain types of

acrylic paint Acrylic paint is a fast-drying paint made of pigment suspended in acrylic polymer emulsion and plasticizers, silicone oils, defoamers, stabilizers, or metal soaps. Most acrylic paints are water-based, but become water-resistant when dry. De ...

carbon nanotubes A scanning tunneling microscopy image of a single-walled carbon nanotube Rotating single-walled zigzag carbon nanotube A carbon nanotube (CNT) is a tube made of carbon with diameters typically measured in nanometers. ''Single-wall carbon nan ...

anodized Anodizing is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts. The process is called ''anodizing'' because the part to be treated forms the anode electrode of an elect ...

aluminum, and nickel-phosphate coatings.

Beam traps

Beam traps are used when it is important that there is no reflectance. Beam traps can incorporate materials used for beam blocks in their design to further reduce the possibility of reflectance.

Charged-particle beam dumps

The purpose of a charged-particle beam dump is to safely absorb a beam of charged particles such as

electrons The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary partic ...

protons A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron m ...

, nuclei, or

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

s. This is necessary when, for example, a circular

particle accelerator A particle accelerator is a machine that uses electromagnetic fields to propel electric charge, charged particles to very high speeds and energies, and to contain them in well-defined particle beam, beams. Large accelerators are used for fun ...

has to be shut down. Dealing with the heat deposited can be an issue, since the energies of the beams to be absorbed can run into the

megajoules The joule ( , ; symbol: J) is the unit of energy in the International System of Units (SI). It is equal to the amount of work done when a force of 1 newton displaces a mass through a distance of 1 metre in the direction of the force applied ...

. An example of a charged-particle beam dump is the one used by CERN for the

Super Proton Synchrotron The Super Proton Synchrotron (SPS) is a particle accelerator of the synchrotron type at CERN. It is housed in a circular tunnel, in circumference, straddling the border of France and Switzerland near Geneva, Switzerland. History The SPS was d ...

. Currently, the SPS uses a beam dump that consists of graphite, molybdenum, and tungsten surrounded by concrete, marble, and cast-iron shielding.{{Cite web , title=LS2 Report: New SPS beam dump takes shape , url=https://home.cern/news/news/accelerators/ls2-report-new-sps-beam-dump-takes-shape , website=CERN , language=en , access-date=2020-05-17

References

Accelerator physics Optical devices Laser applications