The Directional Recoil Identification from Tracks (DRIFT) detector is a low pressure negative ion

time projection chamber In physics, a time projection chamber (TPC) is a type of particle detector that uses a combination of electric fields and magnetic fields together with a sensitive volume of gas or liquid to perform a three-dimensional reconstruction of a particle ...

(NITPC) designed to detect

weakly interacting massive particles Weakly interacting massive particles (WIMPs) are hypothetical particles that are one of the proposed candidates for dark matter. There exists no formal definition of a WIMP, but broadly, it is an elementary particle which interacts via gravity an ...

(WIMPs) - a prime

dark matter In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravity, gravitational effects that cannot be explained by general relat ...

candidate. There are currently two DRIFT detectors in operation. DRIFT-IId, which is located 1100m underground in the Boulby Underground Laboratory at the

Boulby Mine The Boulby Mine is an underground mining operation with surface facilities located just south-east of the village of Boulby, on the north-east coast of the North York Moors, east of Loftus, North Yorkshire. It is operated by Cleveland Potash L ...

North Yorkshire North Yorkshire is a Ceremonial counties of England, ceremonial county in Northern England.The Unitary authorities of England, unitary authority areas of City of York, York and North Yorkshire (district), North Yorkshire are in Yorkshire and t ...

, England, and DRIFT-IIe, which is located on the surface at

Occidental College Occidental College (informally Oxy) is a private liberal arts college in Los Angeles, California, United States. Founded in 1887 as a coeducational college by clergy and members of the Presbyterian Church, it became non-sectarian in 1910. It is ...

Los Angeles Los Angeles, often referred to by its initials L.A., is the List of municipalities in California, most populous city in the U.S. state of California, and the commercial, Financial District, Los Angeles, financial, and Culture of Los Angeles, ...

. The DRIFT collaboration ultimately aims to develop and operate an underground array of DRIFT detectors for observing and reconstructing WIMP-induced nuclear recoil tracks with enough precision to provide a signature of the

dark matter halo In modern models of physical cosmology, a dark matter halo is a basic unit of cosmological structure. It is a hypothetical region that has decoupled from cosmic expansion and contains gravitationally bound matter. A single dark matter halo ma ...

WIMP detection

There are numerous experiments worldwide attempting to detect the energy deposition that is expected to occur when a WIMP directly collides with an atom of ordinary matter. Ultra sensitive experiments are required to detect the low energy and extremely rare interaction that is predicted to occur between a WIMP and the nucleus of an atom in a target material. The DRIFT detectors vary from the majority of WIMP detectors in their use of a low pressure gas as a target material. The low pressure gas means that an interaction within the detector causes an

ionisation Ionization or ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule i ...

track of measurable length compared to the point like interactions seen in detectors with solid or liquid target materials. Such ionisation tracks can be reconstructed in three dimensions to determine not only the type of particle that caused it, but from which direction the particle came. This directional sensitivity has the potential to prove the existence of WIMPs by their distinct directional signature.

Detection technology

The DRIFT detector's target material is a 1 m³ cubical

drift chamber A wire chamber or multi-wire proportional chamber is a type of proportional counter that detects charged particles and photons and can give positional information on their trajectory, by tracking the trails of gaseous ionization. was located via ...

filled with a low pressure mixture of

carbon disulfide Carbon disulfide (also spelled as carbon disulphide) is an inorganic compound with the chemical formula and structure . It is also considered as the anhydride of thiocarbonic acid. It is a colorless, flammable, neurotoxic liquid that is used as ...

(CS₂) and

carbon tetrafluoride Tetrafluoromethane, also known as carbon tetrafluoride or R-14, is the simplest perfluorocarbon (Carbon, CFluorine, F4). As its IUPAC name indicates, tetrafluoromethane is the perfluorinated counterpart to the hydrocarbon methane. It can also be c ...

(CF₄) gases (, respectively). It is predicted that WIMPs will occasionally collide with the nucleus of a sulfur or carbon atom in the carbon disulfide gas causing the nucleus to recoil. An energetic recoiling nucleus will ionise gas particles creating a path of free electrons. These free electrons readily attach to the

electronegative Electronegativity, symbolized as , is the tendency for an atom of a given chemical element to attract shared electrons (or electron density) when forming a chemical bond. An atom's electronegativity is affected by both its atomic number and the d ...

CS₂ molecules creating a track of ions. The gas volume is divided in half by a

cathode A cathode is the electrode from which a conventional current leaves a polarized electrical device such as a lead-acid battery. This definition can be recalled by using the mnemonic ''CCD'' for ''Cathode Current Departs''. Conventional curren ...

at , which produces a static electric field that causes these negative ions to drift, whilst maintaining the track structure, to the MWPC planes at two ends of the detector. Addition of of oxygen to the gas mixture has been the key to full fiducialisation of sensitive volume of the DRIFT detector.

Results

DRIFT-IId published Spin-dependent limits in 2012.

References

External links

DRIFT web siteDRIFT-I on display at the Science Museum, London
{{coord, 54.5534, -0.8245, region:GB, display=title Experiments for dark matter search Research institutes in North Yorkshire