1982 The Low Energy Anti Proton Ring example essay topic

Introduction - What is antimatter? When you look at yourself in the mirror you see the opposite to you, what if this person really existed? Physicists would call the other you an Anti you. This is basically what antimatter is. It is the exact opposite of matter it has the same mass and theoretically the same properties except that every charge is reversed.

In 1905 Albert Einstein wrote down the infamous equation E = mc 2 in other words matter is a concentrated form of energy. It also states that if enough energy is put in then matter could be formed. This is proved true by particle accelerators in that when a particle hits a stationary block of material going at about speed of light its energy is converted into matter but the question is: What sort of matter is produced? The energy is not converted into any kind of matter a certain amount of energy gives a certain particle, for example a proton, or electron. These two particles have a charge and so, since the universe is overall, neutral, a particle of opposite and equal charge must be produced as well.

This is like cutting a shape out of paper you have the shape (matter) and the hole (antimatter). When you put them back together you have the complete sheet again and this is the energy. The Beginning In 1928 Paul Dirac combined the theories of Quantum Theory and Special Relativity to produce an equation that described the behavior of the electron. Although this equation won him the Noble prize it also caused a few headaches of its own; just as the equation x 2 = 16 has two solutions (x = 4 and x = -4) so too did his equation one for an electron with positive energy and one for an electron with negative. In classical physics, however, the energy of a particle must always be positive. Dirac personally interpretation of this was that for every particle there must be an exactly matching particle just with an opposite charge.

Dirac even speculated on the existence of a completely new universe made of antimatter. In 1932 his theories on the existence of antimatter were proved. The First Viewing of Antimatter The first evidence the positron or anti electron was found by Carl Anderson, a young professor at the California Institute of Technology. He witnessed a particle is moving the 'wrong direction' in a magnetic field.

The direction of the particle indicated that it was positive but the track was too faint for it to be a proton. By the way it curved its mass was establish as that of an electron. Anderson is quoted to have said' Curiously enough, despite the strong admonitions of Dr Millikan that upward-moving cosmic ray particles were rare, this indeed was an example of one of those very rare upward-moving cosmic ray particles' The later discovered were in fact as he thought anti-electrons or positrons. For a long time cosmic rays remained the only source of antimatter and the antiproton had to wait 20 years before technology was such that they could achieve it The Search for an Antiproton.

The proton is much heavier than the electron and thus in order to accelerate it up to a speed of a few tens of MeV a very powerful machine is needed. In 1930, Ernest Lawrence had invented such a machine, the cyclotron. Initially he was driven by the desire to discover the antiproton, however this began accelerator era, and with it was born the new science of 'High Energy Physic. ' In 1954 Lawrence built the Bevatron at Berkeley, California (BeV is now known as a GeV). The Bevatron could collide two protons together at an energy of 6.2 GeV, this was expected to be the optimum for producing anti-protons.

Meanwhile a team of physicists, headed by Emilio Segre', designed and built a special detector to see the anti-protons. At this time most of the USA led the way. The machines needed were just too big and expensive for any European country to build. However in 1954, European physicists decided to create in Geneva, Switzerland, a central, European laboratory, that they called CERN (Conseil Europ " een pour la Recherche Nucl " e aire - European Council for Nuclear research). Since then, CERN has become a major player in most technical and scientific developments in High Energy Physics. In October 1955 High energy particle physics hit the head lines and not for the last times.

New York Times: "New Atom Particle Found; Termed a Negative Proton". With this discovery of the anti-proton a further proof of the essential symmetry of nature, between matter and antimatter was established. A year later and the anti-neutron had been discovered by another team, the accelerator era was well on its way. And on to Anti nuclei... With matter electrons, protons and neutrons bind together to produce atoms so could the same be true of anti electrons, antiprotons and antineutrons? It would be natural to say yes.

Dirac implied that matter and antimatter were symmetrical the time had finally come to find out if antimatter and matter were opposite or symmetrical. The production of antihydrogen had opened the door to a systematic exploration of the proprieties of antimatter and to the test of fundamental physical principles. Would the anti-protons and anti-neutrons join just as the protons and neutrons did to for an anti-nucleus? In 1965 the answer to this question finally arrived with the observation of an anti-neutron (one anti-proton bonded to one anti-neutron) This goal was achieved simultaneously by Anti onino Zichichiand his team using the Proton Synchrotron at CERN, and Leon Lederman, using the Alternating Gradient Synchrotron (AGS) accelerator at the Brookhaven National Laboratory, New York.

And Anti-atoms... In order to attach electrons to the anti-protons they had to be slowed down otherwise they wouldn't join together. This was only managed quite recently because first a decelerator had to be created. CERN built such a machine called, the Low Energy Antiproton Ring (LEAR). While the anti-protons are moving at smaller speeds physicist can try to force a positron to an anti-proton, thus producing an anti-hydrogen atom. At the end of 1995 a team of Italian and German physicists managed to produce 9 anti atoms.

Yet again high energy particle physics made the headlines. The achievement suggested that the anti-hydrogen atom could play a role in the study of the anti-world similar to that played by the hydrogen atom in over more than a century of scientific history. Hydrogen makes up three quarters of our universe, and much of what we know about the cosmos has been discovered by studying ordinary hydrogen. But does anti-hydrogen behave exactly like ordinary hydrogen? In order to answer this question a machine had to be made that could mass produce antihydrogen thus the Anti-proton Decelerator (AD) was made. Slower Matter.

There are a lot of interesting things to be done with low energy anti-protons, and low energy is the only way to directly test the presumed symmetry between matter and antimatter. Slow anti-protons can be captured in real "traps", and their properties compared to those of protons. Full pieces of anti-matter, anti-atoms can be made out of positrons and anti-protons at low speeds. CERN is the only laboratory which chose specifically to invest in this research line.

In 1980 it started to build a new machine, able to "decelerate" the anti-protons produced and stored by its existing rings. In 1982 the Low Energy Anti-proton Ring (LEAR) appeared: it could decelerate the anti-protons coming from the PS to different intermediate energies, down to a few MeV (still amazing fast by our standards). Several important scientific achievements were made possible by LEAR, one of them being the assembly of the first pieces of anti-matter as mentioned above. LEAR was closed at the end of 1996, but CERN had already foreseen an alternative and powerful way to continue on this research topic: the Anti-proton Decelerator (AD).

The Anti-proton Decelerator, A self-contained anti-particle factory! The Anti-proton Decelerator is a very special machine compared to what already exists at CERN and other laboratories around the world. Before its construction an "anti-particle factory" consisted of a chain of several accelerators, each one performing one of the steps needed to produce anti-particles. The AD performs all the tasks that the Anti-proton Collector (the ring in which the anti-protons were collected), Anti-proton Accelerator (this produces accumulate high energy anti-protons), and LEAR. Therefore the AD will produce, collect, cool, decelerate and eventually extract anti-protons for the experiments. The AD ring is approximately a circle with a circumference of 188 m.

It consists of a vacuum pipe surrounded by a long sequence of vacuum pumps, magnets, radio-frequency cavities, high voltage instruments and electronic circuits. What are the parts for? 1. The anti-protons circulate inside the vacuum pipe. It is a vacuum to avoid the anti-matter annihilating by bumping in to matter. To ensure that the vacuum is optimal vacuum pumps work full time.

2. Magnets as well are placed all around. There are two types of magnets used. The dipoles (which have a North and a South pole, like the well-known horseshoe magnet) change the direction of movement and make sure the particles stay within their circular track.

They are also called "bending magnets". The Quadrupole's (which have four poles) are used as 'lenses'. They 'focus' the beam to make sure that it is smaller than the size of the vacuum pipe. 3.

Magnetic fields can change the direction and size of the beam, but not its energy. For this you need an electric field. This is provided by radio-frequency cavities that produce high voltages in synchronicity with the rotation of particles around the ring. 4. Several other instruments are needed to perform more specific tasks: two cooling systems "squeeze" the beam in size and energy. One injection and one ejection system let the beam in and out of the machine.

How does the AD work? Anti-particles don't just appear out of thin air they have to be created from energy. This energy is obtained by protons that have been previously accelerated in the PS. These protons are smashed into a block of metal, called a target. Copper or Iridium targets are most often used, mainly because they are easy to cool, but anything would do. The abrupt stopping of such energetic particles releases a huge amount of energy into a small volume.

This heats up to such temperatures that matter-antimatter particles are spontaneously created. Only one collision out of a million causes an antiproton-proton pair to be formed. But given the fact that about 10 trillion protons hit the target every minute, this still makes a good 10 million antiprotons heading towards the AD. The newly created antiprotons are not all heading in the same direction or even at the same speed, they are produced almost at the speed of light, but not all of them have exactly the same energy. Bending and focussing magnets make sure they stay on the right track and in the middle of the vacuum pipe, while they begin to race around in the ring or else they smash into the side and annihilate. At each turn, the strong electric fields inside the radio-frequency cavities start the deceleration of the antiprotons.

Unfortunately, this deceleration 'helps' the travel in different direction and if nothing is done to cure that, all antiprotons will be lost when they eventually collide with the vacuum pipe. To avoid this, two methods are used: 'stochastic' and 'electron cooling'. Stochastic (or 'random') cooling works best at high speeds (around the speed of light, c), and electron cooling works better at low speed (at about 10-30% of c). Their goal is to decrease energy spread and the random movements of the antiproton beam. Finally, when the antiparticles speed is down to about 10% of the speed of light, the antiprotons squeezed group (called a "bunch") is ready to be ejected. This is one "deceleration cycle" and it has only lasted about a minute.

And they " re out! A strong 'kicker' magnet is fired in less than a millionth of a second. This is like giving the antiprotons a very big kick in the bum with a very big shoe. At the next turn, all antiprotons are following a new path.

This leads them into the beam pipes of the extraction line. There, additional dipole and quadrupole magnets steer the beam into one of the three experiments. o ASACUSA " Atomic Spectroscopy and Collisions using Slow Antiprotons"; o ATHENA "Antihydrogen Production and Precision Experiments" o ATRAP "Cold Antihydrogen for Precise Laser Spectroscopy". ASACUSA, on the other hand, will synthesize "exotic" atoms. Atoms made of both matter and antimatter. In which an electron is replaced by an antiproton. Precise laser spectroscopy of these exotic atoms is expected to reveal lots of information on the behavior of atomic systems.

ATHENA and ATRAP's goal is to produce antihydrogen in traps, by combining antiprotons delivered by the AD with positrons emitted by a radioactive source. The first antihydrogen observed was moving close to the speed of light and destroyed immediately after detection. On the 19th September 2002 the dream to produce a large number of antihydrogen atoms was realised. ATHENA produces thousands of cold anti-atoms at the AD in CERN. Finally these particles which have been discussed for many years can be test and the answer to whether or not matter and antimatter or opposite or symmetrical can be answered. the opening lines of Star Trek by Gene Roddenberry. Cern, Live from Cern web.