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The Antihydrogen Trap (ATRAP) collaboration at the
ATRAP was a collaboration between physicists around the world with the goal of creating and experimenting with antihydrogen. ATRAP accumulates positrons emitted from a radioactive 22Na source.
There are two effective ways to slow down the fast positrons by inelastic processes. The ATRAP collaboration initially chose a different method to ATHENA (AD-1).
Since this method of positron accumulation was not particularly efficient, ATRAP switched to a Surko-type buffer gas accumulator as is now standard in experiments requiring large numbers of positrons. This has led to the storage of the largest ever number of positrons in an Ioffe trap.
ATRAP has been terminated. ATRAP had an Ioffe trap, which attempted to store the electrically neutral antihydrogen using a magnetic quadrupole field. This was potentially possible because the magnetic moment of antihydrogen is non-zero.
ATRAP
experiment on INSPRE-HEP Particle experiments CERN experiments
Antiproton Decelerator
The Antiproton Decelerator (AD) is a storage ring at the CERN laboratory near Geneva. It was built from the Antiproton Collector (AC) to be a successor to the Low Energy Antiproton Ring (LEAR) and started operation in the year 2000. Antiprotons ...
facility at 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 Meyrin, western suburb of Gene ...
, Geneva, was responsible for the AD-2 experiment. It was a continuation of the TRAP collaboration, which started taking data for the TRAP experiment (also known as the PS196 experiment) in 1985. The TRAP experiment pioneered cold antiproton
The antiproton, , (pronounced ''p-bar'') is the antiparticle of the proton. Antiprotons are stable, but they are typically short-lived, since any collision with a proton will cause both particles to be annihilated in a burst of energy.
The exis ...
s, cold positron
The positron or antielectron is the particle with an electric charge of +1''elementary charge, e'', a Spin (physics), spin of 1/2 (the same as the electron), and the same Electron rest mass, mass as an electron. It is the antiparticle (antimatt ...
s, and first made the ingredients of cold antihydrogen
Antihydrogen () is the antimatter counterpart of hydrogen. Whereas the common hydrogen atom is composed of an electron and proton, the antihydrogen atom is made up of a positron and antiproton. Scientists hope that studying antihydrogen may sh ...
to interact. Later ATRAP members pioneered accurate hydrogen
Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...
spectroscopy
Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum.
Spectro ...
and observed the first hot antihydrogen atoms.
Experimental setup
ATRAP was a collaboration between physicists around the world with the goal of creating and experimenting with antihydrogen. ATRAP accumulates positrons emitted from a radioactive 22Na source.
There are two effective ways to slow down the fast positrons by inelastic processes. The ATRAP collaboration initially chose a different method to ATHENA (AD-1).
Slowing down and trapping positron
The positrons which were emitted by the 22Na were first slowed down with a 10 μm thick titanium foil and then passed through a 2 μm thick tungsten crystal. Within the crystal there is a possibility that a positively charged positron and a negatively charged electron form a Rydbergpositronium
Positronium (Ps) is a system consisting of an electron and its antimatter, anti-particle, a positron, bound together into an exotic atom, specifically an onium. Unlike hydrogen, the system has no protons. The system is unstable: the two part ...
atom. In this process, the positrons lose much of their energy so that it is no longer necessary (as in ATHENA) to decelerate further with collisions in gas. When the loosely bound Rydberg positronium atom reaches the Penning trap at the end of the apparatus, it is ionized
Ionization or ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule i ...
and the positron is caught in the trap.
Since this method of positron accumulation was not particularly efficient, ATRAP switched to a Surko-type buffer gas accumulator as is now standard in experiments requiring large numbers of positrons. This has led to the storage of the largest ever number of positrons in an Ioffe trap.
ATRAP has been terminated. ATRAP had an Ioffe trap, which attempted to store the electrically neutral antihydrogen using a magnetic quadrupole field. This was potentially possible because the magnetic moment of antihydrogen is non-zero. Laser spectroscopy
Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum.
Spectrosc ...
was intended to be performed on antihydrogen stored in the Ioffe trap, however no publication was ever made.
ATRAP collaboration
The ATRAP collaboration comprised the following institutions:References
{{ReflistExternal links
* Record foATRAP
experiment on INSPRE-HEP Particle experiments CERN experiments