DEAP
Encyclopedia
DEAP is a direct dark matter
search experiment using liquid argon
as target material. DEAP utilizes background discrimination based on the characteristic scintillation
pulse shape in argon. A first-generation detector (DEAP-1) with a 7 kg target mass has been operated at Queen's University to test the available pulse-shape discrimination at low recoil energies in liquid argon, and has been moved to SNOLAB
in October 2007. Discrimination of beta and gamma events from nuclear recoils in the energy region of interest (near 20 keV of electron energy) is required to be better than 1 in 108 to sufficiently suppress backgrounds in the DEAP-1 detector. A larger detector with a 3600 kg active mass is planned for construction beginning in 2008, and will have sensitivity to WIMP-nucleon scattering cross-sections as low as 10−46 cm².
In DEAP, as the light output is characteristic to the type of event, be it either a nuclear recoil event or a gamma event, the interaction of each event can be uniquely determined.
DEAP-1 utilizes 7 kg of liquid argon as a target for WIMP interactions. Two photomultiplier tubes
are used to detect the scintillation light produced by a particle interacting with the argon. As the scintillation light produced is of low wavelength (120 nm) a wavelength shifting film is used to broaden the wavelength so that it falls within the visible spectrum (440 nm) enabling it to pass through ordinary windows without any losses and be detected by the PMTs.
project, which detects neutrinos, another weakly interacting particle
.
, the first generation detector, DEAP-1, after demonstrating good pulse shape discrimination of backgrounds on the surface, has begun operation in SNOLAB. The deep underground location reduces unwanted cosmogenic signals ("background") and allows a more sensitive dark matter search. A run of 18 months is planned, during which the 1 ton DEAP-3 detector is being constructed.
Collaborators are from Queen's University
, Carleton University
, Case Western Reserve University
, Los Alamos National Laboratory
, SNOLAB
, TRIUMF
, University of Alberta
, University of New Mexico
, University of North Carolina
, and Yale University
.
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...
search experiment using liquid argon
Argon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...
as target material. DEAP utilizes background discrimination based on the characteristic scintillation
Scintillation
Scintillation can refer to:*Scintillation , atmospheric effects which influence astronomical observations*Interplanetary scintillation, fluctuations of radio waves caused by the solar wind...
pulse shape in argon. A first-generation detector (DEAP-1) with a 7 kg target mass has been operated at Queen's University to test the available pulse-shape discrimination at low recoil energies in liquid argon, and has been moved to SNOLAB
Snolab
SNOLAB is a Canadian underground physics laboratory at a depth of 2 km in Sudbury, Ontario in Vale's Creighton nickel mine. The original Sudbury Neutrino Observatory experiment has ended, but the facilities have been expanded into a permanent underground laboratory.SNOLAB is the world's...
in October 2007. Discrimination of beta and gamma events from nuclear recoils in the energy region of interest (near 20 keV of electron energy) is required to be better than 1 in 108 to sufficiently suppress backgrounds in the DEAP-1 detector. A larger detector with a 3600 kg active mass is planned for construction beginning in 2008, and will have sensitivity to WIMP-nucleon scattering cross-sections as low as 10−46 cm².
Scintillation properties and background suppression
In order to uncover the faint signature of an interacting dark matter particle, the detector is sensitive to low energy interactions, and as such, the signal from the WIMP interaction is hidden within a large collection of events. These events are known as background events. The WIMP signal must be uniquely filtered from these events.In DEAP, as the light output is characteristic to the type of event, be it either a nuclear recoil event or a gamma event, the interaction of each event can be uniquely determined.
Detector description
The first stage of the DEAP project, DEAP-1, was designed in order to characterize several properties of liquid argon, demonstrate the pulse shape discrimination of liquid argon and refine engineering.DEAP-1 utilizes 7 kg of liquid argon as a target for WIMP interactions. Two photomultiplier tubes
PMT
PMT may refer to:* Parent Management Training* Photomultiplier tube, an extremely sensitive light detector* Program Map Table, program specific information in an MPEG transport stream* Place–manner–time*Post-glacial marine transgression*Pearl milk tea...
are used to detect the scintillation light produced by a particle interacting with the argon. As the scintillation light produced is of low wavelength (120 nm) a wavelength shifting film is used to broaden the wavelength so that it falls within the visible spectrum (440 nm) enabling it to pass through ordinary windows without any losses and be detected by the PMTs.
Status
The DEAP project is currently in research and development. A large, well-experienced international collaboration from Canadian and US universities and laboratories are jointly working toward a large tonne-scale detector. The collaboration benefits largely from the experience many of the members and institutions gained on the SNOSnö
"Snö" is a song by Iranian-Swedish singer-songwriter Laleh recorded with the London Symphony Orchestra for the film Arn - The Knight Templar. It was released on December 19, 2007 as her ninth single and was later placed on her third studio album, Me and Simon...
project, which detects neutrinos, another weakly interacting particle
Weak interaction
Weak interaction , is one of the four fundamental forces of nature, alongside the strong nuclear force, electromagnetism, and gravity. It is responsible for the radioactive decay of subatomic particles and initiates the process known as hydrogen fusion in stars...
.
, the first generation detector, DEAP-1, after demonstrating good pulse shape discrimination of backgrounds on the surface, has begun operation in SNOLAB. The deep underground location reduces unwanted cosmogenic signals ("background") and allows a more sensitive dark matter search. A run of 18 months is planned, during which the 1 ton DEAP-3 detector is being constructed.
Collaborators are from Queen's University
Queen's University
Queen's University, , is a public research university located in Kingston, Ontario, Canada. Founded on 16 October 1841, the university pre-dates the founding of Canada by 26 years. Queen's holds more more than of land throughout Ontario as well as Herstmonceux Castle in East Sussex, England...
, Carleton University
Carleton University
Carleton University is a comprehensive university located in the capital of Canada, Ottawa, Ontario. The enabling legislation is The Carleton University Act, 1952, S.O. 1952. Founded as a small college in 1942, Carleton now offers over 65 programs in a diverse range of disciplines. Carleton has...
, Case Western Reserve University
Case Western Reserve University
Case Western Reserve University is a private research university located in Cleveland, Ohio, USA...
, Los Alamos National Laboratory
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...
, SNOLAB
Snolab
SNOLAB is a Canadian underground physics laboratory at a depth of 2 km in Sudbury, Ontario in Vale's Creighton nickel mine. The original Sudbury Neutrino Observatory experiment has ended, but the facilities have been expanded into a permanent underground laboratory.SNOLAB is the world's...
, TRIUMF
TRIUMF
TRIUMF is Canada’s national laboratory for particle and nuclear physics. Its headquarters are located on the south campus of the University of British Columbia in Vancouver, British Columbia. TRIUMF houses the world's largest cyclotron, source of 500 MeV protons, which was named an IEEE Milestone...
, University of Alberta
University of Alberta
The University of Alberta is a public research university located in Edmonton, Alberta, Canada. Founded in 1908 by Alexander Cameron Rutherford, the first premier of Alberta and Henry Marshall Tory, its first president, it is widely recognized as one of the best universities in Canada...
, University of New Mexico
University of New Mexico
The University of New Mexico at Albuquerque is a public research university located in Albuquerque, New Mexico, in the United States. It is the state's flagship research institution...
, University of North Carolina
University of North Carolina
Chartered in 1789, the University of North Carolina was one of the first public universities in the United States and the only one to graduate students in the eighteenth century...
, and Yale University
Yale University
Yale University is a private, Ivy League university located in New Haven, Connecticut, United States. Founded in 1701 in the Colony of Connecticut, the university is the third-oldest institution of higher education in the United States...
.