21 September 2011

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Understanding Antimatter – Everything about Antimatter Part One -

Understanding Antimatter – Everything about Antimatter Part One -

Do you know that the light which we see is like seeing the events which happened in past.

When you and me, never existed that time some stars gave the light and light started to travel and when few are young and few are old now we can see that light.

Thus we can say that Telescope is the time machine.

Like this there are many concepts.

What is matter?
In short matter is everything which you can touch including you and me.
Everything is made up of particles. There are three basic types, electrons, protons and neutrons.

More Reading –
Understanding Matter what is Matter?


History of Antimatter –

1905 –
Albert Einstein unveiled his theory of Special Relativity, explaining the relationship between space and time, and between energy and mass in his
famous equation E=mc2.

As experiments were going on Scientist found that sometimes light behaved as a wave and sometimes like stream of tiny particles.

What is special Relativity?
Special Relativity
The theory that the laws of nature are the same for all observers in uncelebrated motion and the speed of light is independent of the motion of its source.
Einstein postulated that the time interval between two events was longer for an observer in whose frame of reference the events occur in different places than for the observer for whom they occur at the same place.

Quantum –
Max Planck proposed that each light wave must come in a little packet, which he called a "quantum": this way light was not just a wave or just a particle, but a bit of both.

1920 –
Quantum Theory –
Erwin Schrodinger and Werner Heisenberg had invented the new quantum theory of physics. But it only worked for particles moving slowly, and not for those at high (or "relativistic") velocity, close to the speed of light.

Beginning 1928 – Paul Dirac solved the problem of quantum theory.
The history of antimatter begins with a young physicist named Paul Dirac.
he wrote down an equation, which combined quantum theory and special relativity, to describe the behavior of the electron. Dirac's equation won him a Nobel Prize in 1933.

Science is always challenging when you solve one problem it creates another problem same happened with the equation which Paul Dirac wrote.

x2=4 can have two possible solutions (x=2 OR x=-2), so Dirac's equation could have two solutions, one for an electron with positive energy, and one for an electron with negative energy.
But in classical physics the energy of a particle must always be a positive number.

Dirac interpreted this as for every particle that exists there is a corresponding antiparticle, exactly matching the particle but with opposite charge.
For the electron, for instance, there should be an "antielectron"

In his Nobel Lecture, Dirac speculated on the existence of a completely new Universe made out of antimatter.
Now scientist started to look for antimatter.

1930 to 1936 – Discovery of Antimatter

Nobel Prize winner Victor Hess discovered natural source of high energy particles: cosmic rays.
Cosmic rays are very high energy particles that come from outer space and as they hit the Earth's atmosphere they produce huge showers of lower energy particles

Meaning of cloud chamber –
Cloud Chamber A detector filled with a gas close to its condensation point, where the ionizing particles' trajectories materialize in the form of tracks made of droplets.

In 1932 Carl Anderson, a young professor at the California Institute of Technology, was studying showers of cosmic particles in a cloud chamber and saw a track left by "something positively charged, and with the same mass as an electron".
After nearly one year of effort and observation, he decided the tracks were actually antielectrons, each produced alongside an electron from the impact of cosmic rays in the cloud chamber. He called the antielectron a "positron", for its positive charge.

Confirmed soon after by Occhialini and Blackett, the discovery gave Anderson the Nobel Prize in 1936 and proved the existence of antiparticles as predicted by Dirac.

In 1930, Ernest Lawrence (Nobel Prizewinner in 1939) had invented the cyclotron, a machine that eventually could accelerate a particle like a proton up to an energy of a few tens of MeV. Initially driven by the effort to discover the antiproton, the accelerator era had begun, and with it the new science of "High Energy Physics" was born.

eV,MeV,GeV meaning –

The electron-Volt (eV) is the energy unit which corresponds to the acceleration of a particle having the charge of the electron through a voltage difference of one Volt.

Its multiples the mega-electron-Volt (MeV) and giga-electron-Volt (GeV) respectively amount to one million and one billion electron-volts.

It was Lawrence that, in 1954, built the Bevatron at Berkeley, California (BeV, at the time, was what we now call GeV).

The Bevatron could collide two protons together at an energy of 6.2 GeV, expected to be the optimum for producing antiprotons. Meanwhile a team of physicists, headed by Emilio Segre', designed and built a special detector to see the antiprotons.

In October 1955 the big news hit the front page of the New York Times: "New Atom Particle Found; Termed a Negative Proton". With the discovery of the antiproton, Segre' and his group of collaborators (O. Chamberlain, C. Wiegand and T. Ypsilantis) had succeeded in a further proof of the essential symmetry of nature, between matter and antimatter.
Segre' and Chamberlain were awarded the Nobel Prize in 1959. Only a year later, a second team working at the Bevatron (B. Cork, O. Piccione, W. Wenzel and G. Lambertson) announced the discovery of the antineutron.

Now scientist came to know that all 3 particles have an antiparticle.
1. Electron – anti electron
2. protons – anti proton
3. neutrons – anti neutron

All above particles when bound together equals matter.

Then when all anti electron, anti proton and anti neutron boutnd together it will equal to anti matter.

Matter = Electron + Proton + Neutron

Anti matter = anti electron + anti proton + anti neutron

antiparticles, bound together in anti atoms are the basic units of antimatter.

Now again scientist faced new questions
1. are matter and antimatter exactly equal and opposite, or symmetric, as Dirac had implied?

2. how do subatomic antiparticles behave when they come together?
3. Would an antiproton and an antineutron stick together to form an anti nucleus just as protons and neutrons stick together to form an atom's nucleus?

The answer to the antinuclei question was found in 1965 with the observation of the antideuteron, a nucleus of antimatter made out of an antiproton plus an antineutron (while a deuteron, the nucleus of the deuterium atom, is made of a proton plus a neutron).

The goal was simultaneously achieved by two teams of physicists, one led by Antonino Zichichi, using the Proton Synchrotron at CERN, and the other led by Leon Lederman, using the Alternating Gradient Synchrotron (AGS) accelerator at the Brookhaven National Laboratory, New York.

1995: from antiparticles to antimatter

After making antinuclei, naturally the next question was:
can antielectrons stick to antinuclei to make antiatoms?

In fact the answer was only revealed quite recently, thanks to a very special machine, unique to CERN, the Low Energy Antiproton Ring (LEAR).

Contrary to an accelerator, LEAR actually "slowed down" antiprotons.

Physicists could then try to force a positron (or antielectron) to stick to an antiproton, making an antihydrogen atom, a real antimatter atom.

Towards the end of 1995, the first such antiatoms were produced at CERN by a team of German and Italian physicists.

Although only 9 antiatoms were made, the news was so thrilling that it made the front page of many of the world's newspapers.

The achievement suggested that the antihydrogen atom could play a role in the study of the antiworld 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 antihydrogen behave exactly like ordinary hydrogen ?

To answer this question CERN decided to build a new experimental facility: the Antiproton Decelerator (AD).

the Antiproton Decelerator (or AD), is operational at CERN . It can produce the low energy antiprotons needed for a range of studies, including the synthesis of antihydrogen atoms - the creation of antimatter.

End of Part One -

Continue –

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Wednesday, September 21, 2011

Source - http://press.web.cern.ch

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Amrit September 21, 2011  

Awesome description