# Elementary Particles - Page 1 of 3

Calculus

Relativity and quantum mechanics, as preceding mentioned, changed almost all of the physical conceptions that existed prior to them. They were extremely important fields that gave rise to other new fields in physics that haven't been explored before. They weren't explored before, mainly, because of two main reasons:

1. Theoretical laws and conceptions, in general, were a lot confused with each other and not understood thoroughly.

2. The technology present at that time was so basic that it couldn't withstand the experiments, experimental physicists needed in order to confirm theoretical predictions.

The field of elementary particle physics was motivated because these two reasons were, in a large part, demolished. Theoretical physics had a firm ground, thanks to relativity and quantum mechanics. Technology was vastly improving by engineers throughout the world, especially in England and the United States. One of the keys to these advances was the beginning of designing particle accelerators.

## PARTICLE ACCELERATORS

In general, an electrostatic field can accelerate charged particles. This is done by placing electrodes with a large potential difference at each end of an evacuated tube. There are several kinds of particle accelerators; each one of them has a particular maximum acceleration. The kinds of accelerators are:

• Van De Graff Accelerator
• Cyclotron
• Linear Accelerator (LINAC)
• Betatron
• Synchrotron
• Storage Ring Collider Accelerators

### Van De Graff Accelerator

We begin our discussion with the Van De Graff accelerator. The Van De Graff accelerator uses a Van De Graff generator, named after its American inventor. It builds up a potential difference between two electrodes by carrying electromagnetic charges on a moving belt. At the time they were developed, they were able to accelerate protons at charges of a few thousands of eVs (electron volts). Nowadays, however, they reach energies as high as 15 MeV (15 million electron volts). One eV is the energy an electron acquires when accelerated across a potential difference of 1 volt.

### Linear Accelerator

In 1929, Ernest Lawrence, a young physics professor at Berkley, came up with an innovative idea. His idea was based on a system designed by Norwegian engineer Rolf Wideröe. In Wideröe scheme, a charged particle would proceed down the center of a series of metal tubes that are separated by short gaps. As soon as the charged particle reaches the gap, the tube in front of it would be given the opposite electrical charge; thus attracting the incoming charged particle and speeding it up. Therefore, at each gap, the particle would accelerate. Today, this is known as a Linear accelerator (LINAC). The largest LINAC in the world is at Stanford University; it's 3.2 km long and is capable of accelerating electrons up to 50 GeV (50 billion or giga, electron volts). There was, however, one big problem in Wideröe's scheme: pushing particles up to very high energies would require an extremely long line of tubes. Here, Lawrence came into the scene. He realized that Wideöe's idea could still be applied; however, instead of being a straight line of tubes, the process could be made circular. This would force the particle to pass across the same accelerating gap again and again. This was based on an established principle in physics which states that a charged particle moving through a magnetic field experiences a sideways force that causes it to begin to rotate in a circular fashion.

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