The construction of the LExan Bubble Chamber, LEBC, was approved by the

CERN The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in a northwestern suburb of Gene ...

Research Board on 16 November 1978. Bubble chambers are similar to cloud chambers, both in application and in basic principle. A chamber is normally made by filling a large cylinder with a liquid heated to just below its

boiling point The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding envir ...

. As particles enter the chamber, a

piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tig ...

suddenly decreases its pressure, and the liquid enters into a superheated, metastable phase. Charged particles create an ionization track, around which the liquid vaporizes, forming microscopic

bubble Bubble, Bubbles or The Bubble may refer to: Common uses * Bubble (physics), a globule of one substance in another, usually gas in a liquid ** Soap bubble * Economic bubble, a situation where asset prices are much higher than underlying fundame ...

s. Bubble density around a track is proportional to a particle's energy loss. Bubbles grow in size as the chamber expands, until they are large enough to be seen or photographed. Several cameras are mounted around it, allowing a three-dimensional image of an event to be captured. LEBC was 20 centimetres in diameter and contained one litre of liquid hydrogen. It was designed to look for charmed particles, a type of particles that are so unstable that they usually

decay Decay may refer to: Science and technology * Bit decay, in computing * Software decay, in computing * Distance decay, in geography * Decay time (fall time), in electronics Biology * Decomposition of organic matter * Tooth decay (dental caries) ...

too quickly to be detected in big bubble chambers. The bubbles in a small chamber like LEBC were about ten times smaller compared to the bubbles in the large chambers. Hence, LEBC had a higher probability of detecting short tracks. LEBC was used for several

CERN experiments The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in a northwestern suburb of Gene ...

Geneva Geneva ( ; french: Genève ) frp, Genèva ; german: link=no, Genf ; it, Ginevra ; rm, Genevra is the List of cities in Switzerland, second-most populous city in Switzerland (after Zürich) and the most populous city of Romandy, the French-speaki ...

, among others NA13, NA16 and

NA27 (''The New Testament in Greek'') is a critical edition of the New Testament in its original Koine Greek, forming the basis of most modern Bible translations and biblical criticism. It is also known as the Nestle–Aland edition after its mos ...

, before it was transported to

Fermilab Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operat ...

outside

Chicago (''City in a Garden''); I Will , image_map = , map_caption = Interactive Map of Chicago , coordinates = , coordinates_footnotes = , subdivision_type = Country , subdivision_name ...

where it was used for experiment E743. The NA13 experiment was performed by exposing LEBC without any down-stream particle

spectrometer A spectrometer () is a scientific instrument used to separate and measure spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomenon where the ...

. While for the NA16 experiment, LEBC was placed at the vertex position of the European Hybrid Spectrometer (EHS) that provided momentum analysis, particle identification and gamma detection for secondaries emerging from the hydrogen interactions.

References

{{CERN Bubble chambers operated at CERN

See also

References