A bubble chamber is a vessel filled with a superheated transparent liquid (most often liquid hydrogen) 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. Supposedly, Glaser was inspired by the bubbles in a glass of beer; however, in a 2006 talk, he refuted this story, although saying that while beer was not the inspiration for the bubble chamber, he did experiments using beer to fill early prototypes.
In physics, superheating is the phenomenon in which a liquid is heated to a temperature higher than its boiling point, without boiling. This is a so-called metastable state or metastate, where boiling might occur at any time, induced by external or internal effects. Superheating is achieved by heating a homogeneous substance in a clean container, free of nucleation sites, while taking care not to disturb the liquid.
A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter, and is the only state with a definite volume but no fixed shape. A liquid is made up of tiny vibrating particles of matter, such as atoms, held together by intermolecular bonds. Water is, by far, the most common liquid on Earth. Like a gas, a liquid is able to flow and take the shape of a container. Most liquids resist compression, although others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly constant density. A distinctive property of the liquid state is surface tension, leading to wetting phenomena.
Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.
While bubble chambers were extensively used in the past, they have now mostly been supplanted by wire chambers and spark chambers. Notable bubble chambers include the Big European Bubble Chamber (BEBC) and Gargamelle.
A 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.
A spark chamber is a particle detector: a device used in particle physics for detecting electrically charged particles. They were most widely used as research tools from the 1930s to the 1960s and have since been superseded by other technologies such as drift chambers and silicon detectors. Today, working spark chambers are mostly found in science museums and educational organisations, where they are used to demonstrate aspects of particle physics and astrophysics.
The Big European Bubble Chamber (BEBC) is a large size detector formerly used to study particle physics at CERN. The chamber body, a stainless-steel vessel, was filled with 35 cubic metres of superheated liquid hydrogen, liquid deuterium or a neon-hydrogen mixture, whose sensitivity was regulated by means of a movable piston weighing 2 tons. The liquids at typical operation temperatures around 27 K were placed under overpressure of about 5 atm. The piston expansion, synchronized with the charged particle beam crossing the chamber volume, caused a rapid pressure drop with in consequence the liquid reaching its boiling point During each expansion, charged particles ionized the atoms of the liquid as they passed through it and the energy deposited by them initiated boiling along their path leaving trails of tiny bubbles. These bubbles tracks were photographed by the five cameras mounted on top of the chamber. The stereo photographs were subsequently scanned and all events finally evaluated by a team of scientists. After each expansion, the pressure was increased again to stop the boiling. The bubble chamber was then ready again for a new cycle of particles beam exposure.
The bubble chamber is similar to a cloud chamber, both in application and in basic principle. It is normally made by filling a large cylinder with a liquid heated to just below its boiling point. As particles enter the chamber, a piston 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 bubbles. Bubble density around a track is proportional to a particle's energy loss.
A cloud chamber, also known as a Wilson cloud chamber, is a particle detector used for visualizing the passage of ionizing radiation.
The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid and the liquid changes into a vapor.
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.
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. Bubble chambers with resolutions down to a few micrometers (μm) have been operated.
The entire chamber is subject to a constant magnetic field, which causes charged particles to travel in helical paths whose radius is determined by their charge-to-mass ratios and their velocities. Since the magnitude of the charge of all known charged, long-lived subatomic particles is the same as that of an electron, their radius of curvature must be proportional to their momentum. Thus, by measuring their radius of curvature, their momentum can be determined.
A helix, plural helixes or helices, is a type of smooth space curve, i.e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a fixed line called the axis. Examples of helices are coil springs and the handrails of spiral staircases. A "filled-in" helix – for example, a "spiral" (helical) ramp – is called a helicoid. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, and many proteins have helical substructures, known as alpha helices. The word helix comes from the Greek word ἕλιξ, "twisted, curved".
The electron is a subatomic particle, symbol
, whose electric charge is negative one elementary charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. The electron has a mass that is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum (spin) of a half-integer value, expressed in units of the reduced Planck constant, ħ. As it is a fermion, no two electrons can occupy the same quantum state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of both particles and waves: they can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a longer de Broglie wavelength for a given energy.
In Newtonian mechanics, linear momentum, translational momentum, or simply momentum is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction in three-dimensional space. If m is an object's mass and v is the velocity, then the momentum is
Notable discoveries made by bubble chamber include the discovery of weak neutral currents at Gargamelle in 1973,which established the soundness of the electroweak theory and led to the discovery of the W and Z bosons in 1983 (at the UA1 and UA2 experiments). Recently, bubble chambers have been used in research on Weakly interacting massive particles (WIMP)s, at SIMPLE, COUPP, PICASSO and more recently, PICO.
Weak neutral current interactions are one of the ways in which subatomic particles can interact by means of the weak force. These interactions are mediated by the
boson. The discovery of weak neutral currents was a significant step toward the unification of electromagnetism and the weak force into the electroweak force, and led to the discovery of the W and Z bosons.
Gargamelle was a heavy liquid bubble chamber detector in operation at CERN between 1970 and 1979. It was designed to detect neutrinos and antineutrinos, which were produced with a beam from the Proton Synchrotron (PS) between 1970 and 1976, before the detector was moved to the Super Proton Synchrotron (SPS). In 1979 an irreparable crack was discovered in the bubble chamber, and the detector was decommissioned. It is currently part of the microcosm exhibition at CERN, open to the public.
The W and Z bosons are together known as the weak or more generally as the intermediate vector bosons. These elementary particles mediate the weak interaction; the respective symbols are
. The W bosons have either a positive or negative electric charge of 1 elementary charge and are each other's antiparticles. The Z boson is electrically neutral and is its own antiparticle. The three particles have a spin of 1. The W bosons have a magnetic moment, but the Z has none. All three of these particles are very short-lived, with a half-life of about 3×10−25 s. Their experimental discovery was a triumph for what is now known as the Standard Model of particle physics.
Although bubble chambers were very successful in the past, they are of limited use in modern very-high-energy experiments for a variety of reasons:
Due to these issues, bubble chambers have largely been replaced by wire chambers, which allow particle energies to be measured at the same time. Another alternative technique is the spark chamber.
Donald Arthur Glaser was an American physicist, neurobiologist, and the winner of the 1960 Nobel Prize in Physics for his invention of the bubble chamber used in subatomic particle physics.
Jack Steinberger is an American physicist who, along with Leon M. Lederman and Melvin Schwartz, received the 1988 Nobel Prize in Physics for the discovery of the muon neutrino.
The UA1 experiment was a high-energy physics experiment that ran at CERN's Proton-Antiproton Collider, a modification of the one-beam Super Proton Synchrotron (SPS). The data was recorded between 1981 and 1990. The joint discovery of the W and Z bosons by this experiment and the UA2 experiment in 1983 led to the Nobel Prize for physics being awarded to Carlo Rubbia and Simon van der Meer in 1984. Peter Kalmus and John Dowell, from the UK groups working on the project, were jointly awarded the 1988 Rutherford Medal and Prize from the Institute of Physics for their outstanding roles in the discovery of the W and Z particles.
The Collider Detector at Fermilab (CDF) experimental collaboration studies high energy particle collisions at the Tevatron, the world's former highest-energy particle accelerator. The goal is to discover the identity and properties of the particles that make up the universe and to understand the forces and interactions between those particles.
The Proton Synchrotron (PS) is a particle accelerator at CERN. It is CERN's first synchrotron, beginning its operation in 1959. For a brief period the PS was the world's highest energy particle accelerator. It has since served as a pre-accelerator for the Intersecting Storage Rings (ISR) and the Super Proton Synchrotron (SPS), and is currently part of the Large Hadron Collider (LHC) accelerator complex. In addition to protons, PS has accelerated alpha particles, oxygen and sulphur nuclei, electrons, positrons and antiprotons.
SNOLAB is a Canadian underground physics laboratory at a depth of 2 km in Vale's Creighton nickel mine in Sudbury, Ontario. The original Sudbury Neutrino Observatory (SNO) experiment has ended, but the facilities have been expanded into a permanent underground laboratory.
PICO is an experiment searching for direct evidence of dark matter using a bubble chamber of chlorofluorocarbon (Freon) as the active mass. It is located at SNOLAB in Canada.
The Holographic Lexan Bubble Chamber, HOLEBC, was a hydrogen bubble chamber.
The Berne Infinitesimal Bubble Chamber, BIBC, was almost pocket size, 6.5 centimetres across and with a visible volume containing about a wine glass of heavy liquid.
The 81 cm Saclay Bubble Chamber was a liquid hydrogen bubble chamber built at Saclay, in collaboration with the École Polytechnique (Orsay), to study particle physics. The team led by Bernard Gregory completed the construction of the chamber in 1960 and later it was moved to CERN and installed at the Proton Synchrotron(PS).
The construction of the LExan Bubble Chamber, LEBC, was approved by the CERN Research Board on 16 November 1978.
The 30 cm Bubble Chamber, prototyped as a 10 cm Bubble Chamber, was a particle detector used to study high-energy physics at CERN.
André Lagarrigue (1924 – 14 January 1975) was a French particle physicist. Being the initiator of the Gargamelle experiment at CERN, his work was of paramount importance in the discovery of neutral currents — the first experimental indication of the existence of the Z0 boson. This major discovery was a step towards verification of the electroweak theory, today a pillar of the Standard Model.
The Super Proton–Antiproton Synchrotron was a particle accelerator that operated at CERN from 1981 to 1991. To operate as a proton-antiproton collider the Super Proton Synchrotron (SPS) underwent substantial modifications, altering it from a one beam synchrotron to a two-beam collider. The main experiments at the accelerator were UA1 and UA2, where the W and Z boson were discovered in 1983. Carlo Rubbia and Simon van der Meer received the 1984 Nobel Prize in Physics for their decisive contribution to the SppS-project, which led to the discovery of the W and Z bosons. Other experiments conducted at the SppS were UA4, UA5 and UA8.