SIMPLE (dark matter)
Encyclopedia
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 (LSBB) near Apt
in southern France
. The experiment is predominantly sensitive to spin
-dependent interactions of weakly interacting massive particles (or WIMPs).
SIMPLE is an international collaboration with members from Portugal
, France
, and the United States
.
droplet detectors (SDDs), a suspension of 1–2% superheated liquid C2ClF5 droplets (~30 μm radius) in a viscoelastic 900 ml gel matrix, which undergo transitions to the gas phase upon energy deposition by incident radiation. The refrigerant
, freon, is used as the active mass.
In effect, each droplet behaves as a miniature bubble chamber
. Once a nucleation
has occurred, the acoustic shock wave is picked up by microphones. Each acquired signal is then fully discriminated in terms of acoustic external noise, gel-associated noise and most recently particle discrimination
. The detectors are typically operated at ~200 kPa and ~280 K
. Due to the construction technique, SSDs are almost insensitive to background radiation
, and their sensitivity can be adjusted by controlling the temperature and pressure of each device.
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 in a 61 m3 cavern at the 500 level of the Laboratoire Souterrain à Bas Bruit (LSBB) near Apt
Apt, Vaucluse
Apt is a commune in the Vaucluse department in the Provence-Alpes-Côte d'Azur region in southeastern France.It lies on the left bank of the Calavon, east of Avignon...
in southern France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
. The experiment 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 (or WIMPs).
SIMPLE is an international collaboration with members from Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, and the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
Design
The SIMPLE detector is based on superheatedSuperheating
In physics, superheating is the phenomenon in which a liquid is heated to a temperature higher than its boiling point, without boiling...
droplet detectors (SDDs), a suspension of 1–2% superheated liquid C2ClF5 droplets (~30 μm radius) in a viscoelastic 900 ml gel matrix, which undergo transitions to the gas phase upon energy deposition by incident radiation. The refrigerant
Refrigerant
A refrigerant is a substance used in a heat cycle usually including, for enhanced efficiency, a reversible phase change from a liquid to a gas. Traditionally, fluorocarbons, especially chlorofluorocarbons, were used as refrigerants, but they are being phased out because of their ozone depletion...
, freon, is used as the active mass.
In effect, each droplet behaves as a miniature bubble chamber
Bubble 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...
. Once a nucleation
Nucleation
Nucleation is the extremely localized budding of a distinct thermodynamic phase. Some examples of phases that may form by way of nucleation in liquids are gaseous bubbles, crystals or glassy regions. Creation of liquid droplets in saturated vapor is also characterized by nucleation...
has occurred, the acoustic shock wave is picked up by microphones. Each acquired signal is then fully discriminated in terms of acoustic external noise, gel-associated noise and most recently particle discrimination
Particle identification
Particle identification is the process of using information left by a particle passing through a particle detector to identify the type of particle. Particle identification reduces backgrounds and improves measurement resolutions, and is essential to many analyses at particle detectors.-Charged...
. The detectors are typically operated at ~200 kPa and ~280 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
. Due to the construction technique, SSDs are 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....
, and their sensitivity can be adjusted by controlling the temperature and pressure of each device.
See also
- PICASSOPICASSO (dark matter)The PICASSO ' experiment is an experiment searching for direct evidence of dark matter...
, a similar experiment using the same detection technique