PICASSO (dark matter)
Encyclopedia
The PICASSO experiment is an experiment searching for direct evidence of dark matter
. It is located at SNOLAB
in Canada, and consist of an international collaboration with members from the Université de Montréal
, Queen's University
, Indiana University South Bend
and Czech Technical University in Prague
, University of Alberta
, Laurentian University
and BTI, Chalk River, Ontario. It uses bubble detectors with Freon as the active mass. PICASSO is predominantly sensitive to spin
-dependent interactions of Weakly Interacting Massive Particles (WIMPs) with fluorine
atoms.
but since only the small droplets can undergo a phase transition at a time, the detector can stay active for much longer periods than a classic bubble chamber. When enough energy is deposited in a droplet by ionizing radiation the superheated droplet undergoes a phase transition
and becomes a gas bubble. The PICASSO detectors contain Freon droplets with an average diameter of . The bubble development in the detector is accompanied by an acoustic shock wave that is picked up by piezo-electric sensors. The main advantage of the bubble detector technique is that the detector is almost insensitive to background radiation
. The detector sensitivity can be adjusted by changing the temperature of the droplets. Freon-loaded detectors are typically operated at temperatures between and .
The validity of the bubble detector concept has been shown in several publications. There is another similar experiment using this technique in Europe called SIMPLE
.
/LIBRA
annual modulation effect in terms of spin dependent interactions.
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...
. It is located at 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 Canada, and consist of an international collaboration with members from the Université de Montréal
Université de Montréal
The Université de Montréal is a public francophone research university in Montreal, Quebec, Canada. It comprises thirteen faculties, more than sixty departments and two affiliated schools: the École Polytechnique and HEC Montréal...
, 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...
, Indiana University South Bend
Indiana University South Bend
Indiana University South Bend is the third largest campus of the Indiana University system. It is popularly known as IUSB or IU South Bend. It is located in South Bend, Indiana, in St. Joseph County, Indiana.-History:...
and Czech Technical University in Prague
Czech Technical University in Prague
Czech Technical University in Prague is one of the largest universities in the Czech Republic, and the oldest institute of technology in Central Europe....
, 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...
, Laurentian University
Laurentian University
Laurentian University , was incorporated on March 28, 1960, is a mid-sized bilingual university in Greater Sudbury, Ontario, Canada....
and BTI, Chalk River, Ontario. It uses bubble detectors with Freon as the active mass. PICASSO is predominantly sensitive to spin
Spin (physics)
In quantum mechanics and particle physics, spin is a fundamental characteristic property of elementary particles, composite particles , and atomic nuclei.It is worth noting that the intrinsic property of subatomic particles called spin and discussed in this article, is related in some small ways,...
-dependent interactions of Weakly Interacting Massive Particles (WIMPs) with fluorine
Fluorine
Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...
atoms.
Principle
A bubble detector is a radiation sensitive device that uses small droplets of superheated liquid that are suspended in a gel matrix. It uses the principle of a bubble chamberBubble chamber
A bubble chamber is a vessel filled with a superheated transparent liquid used to detect electrically charged particles moving through it. It was invented in 1952 by Donald A. Glaser, for which he was awarded the 1960 Nobel Prize in Physics...
but since only the small droplets can undergo a phase transition at a time, the detector can stay active for much longer periods than a classic bubble chamber. When enough energy is deposited in a droplet by ionizing radiation the superheated droplet undergoes a phase transition
Phase transition
A phase transition is the transformation of a thermodynamic system from one phase or state of matter to another.A phase of a thermodynamic system and the states of matter have uniform physical properties....
and becomes a gas bubble. The PICASSO detectors contain Freon droplets with an average diameter of . The bubble development in the detector is accompanied by an acoustic shock wave that is picked up by piezo-electric sensors. The main advantage of the bubble detector technique is that the detector is almost insensitive to background radiation
Background radiation
Background radiation is the ionizing radiation constantly present in the natural environment of the Earth, which is emitted by natural and artificial sources.-Overview:Both Natural and human-made background radiation varies by location....
. The detector sensitivity can be adjusted by changing the temperature of the droplets. Freon-loaded detectors are typically operated at temperatures between and .
The validity of the bubble detector concept has been shown in several publications. There is another similar experiment using this technique in Europe called SIMPLE
SIMPLE (dark matter)
SIMPLE is an experiment search for direct evidence of dark matter. It is located in a 61 m3 cavern at the 500 level of the Laboratoire Souterrain à Bas Bruit near Apt in southern France...
.
Results
PICASSO reports results (November 2009) for spin-dependent WIMP interactions on 19F. No dark matter signal has been found, but for WIMP masses of new stringent limits have been obtained on the spin-dependent cross section for WIMP scattering on 19F of (90% CL). This result has been converted into a cross section limit for WIMP interactions on protons of (90% CL). The obtained limits restrict recent interpretations of the DAMADAMA
DAMA is a not-for-profit, vendor-independent, international association of technical and business professionals dedicated to advancing the concepts and practices of information resource management and data resource management .DAMA's primary purpose is to promote the understanding, development...
/LIBRA
Libra
-Science and technology:* Libra , a star constellation in the sky* Libra , an ancient Roman unit of weight* Libra , a public search engine for academic papers and literature* Libra , a media cataloguing software...
annual modulation effect in terms of spin dependent interactions.
See also
- Dark matterDark matterIn 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...
- Weakly Interacting Massive Particle (WIMP)
- Massive compact halo objectMassive compact halo objectMassive astrophysical compact halo object, or MACHO, is a general name for any kind of astronomical body that might explain the apparent presence of dark matter in galaxy halos. A MACHO is a body composed of normal baryonic matter, which emits little or no radiation and drifts through interstellar...
MACHO - Higgs bosonHiggs bosonThe Higgs boson is a hypothetical massive elementary particle that is predicted to exist by the Standard Model of particle physics. Its existence is postulated as a means of resolving inconsistencies in the Standard Model...
- Micro black holeMicro black holeMicro black holes are tiny black holes, also called quantum mechanical black holes or mini black holes, for which quantum mechanical effects play an important role....
- Robust associations of massive baryonic objectsRobust Associations of Massive Baryonic ObjectsIn astronomy, a RAMBO or robust association of massive baryonic objects is a dark cluster made of brown dwarfs or white dwarfs.-Introduction:RAMBOs were proposed by Moore and Silk in 1995...
RAMBO