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R. N. Mohapatra
and is called the uncertainty principle of quantum mechanics. This principle
enunciated by Werner Heisenberg in 1927 says that neither the location of
a particle nor its speed can be simultaneously determined with unlimited
accuracy. The limit to this accuracy is set by a tiny number known as Planck’s
constant. This implies a complementarity between speed and distance, i.e. the
faster you travel, the shorter distance you can probe. This principle has served
the physicists well. The idea is to speed up the protons and electrons and collide
them against various kinds of particles including protons and electrons, and
find new things that result from the break-up of particles in such a collision.
How do you accelerate a sub-atomic particle? If the particle has electric
charges like the electron and proton, one can use the electric field to speed
them up by the electric force they experience in an electric field. One then
needs a machine which can do it in an efficient way. The first such machine was
built by Cockroft and Walton who accelerated protons using 200 kV capacitor
plates. The two capacitor plates had opposite charges and had an electric field
between them which accelerated the charged particles. Then came Robert Van
de Graaf who built the so-called Van de Graaf generator which could generate
higher voltages (up to 750 kV) and could accelerate the protons to even higher
speeds. Soon it became clear that to go further, one needed bigger space. That
became a difficulty which needed to be overcome. To proceed further with
such accelerating machines, the scientists had to find a way to use smaller
electric fields and do it in the limited space of the laboratory.
The first such compact accelerator that speeds up the sub-atomic particles
like the electron and proton was the cyclotron, which is a circular machine
invented by Ernest O. Lawrence in 1929. It was a major step forward. Ernest
O. Lawrence was born to Norwegian parents and after his Ph.D. from Yale
university contributed to the making of the atom bombs in Los Alamos. His
idea was to make charged particles go round in spirals as they gain more and
more speed within a confined space. The new ideas used here were first to
realize that moving charged particle move in circular paths in a magnetic field.
This was used to make the circular beams of charged particles. They were then
allowed to pass through gaps between two semicircular “dishes” which had
an electric field. The electric field came from the two faces of the gap being
electrically connected to the two terminals of an alternating current source.
The electric field accelerates them in opposite directions in each gap, if the
time it takes for the charged particle from one gap to the other is such that,
it matches the half period of the alternating current. This would effectively
add to the previous speed. A steady magnetic field makes the beam go around
in a circle as just noted. Thus it made very clever use of alternating currents
(oscillating fields) and magnetic fields to build beams of highly energetic
R. N. Mohapatra
and is called the uncertainty principle of quantum mechanics. This principle
enunciated by Werner Heisenberg in 1927 says that neither the location of
a particle nor its speed can be simultaneously determined with unlimited
accuracy. The limit to this accuracy is set by a tiny number known as Planck’s
constant. This implies a complementarity between speed and distance, i.e. the
faster you travel, the shorter distance you can probe. This principle has served
the physicists well. The idea is to speed up the protons and electrons and collide
them against various kinds of particles including protons and electrons, and
find new things that result from the break-up of particles in such a collision.
How do you accelerate a sub-atomic particle? If the particle has electric
charges like the electron and proton, one can use the electric field to speed
them up by the electric force they experience in an electric field. One then
needs a machine which can do it in an efficient way. The first such machine was
built by Cockroft and Walton who accelerated protons using 200 kV capacitor
plates. The two capacitor plates had opposite charges and had an electric field
between them which accelerated the charged particles. Then came Robert Van
de Graaf who built the so-called Van de Graaf generator which could generate
higher voltages (up to 750 kV) and could accelerate the protons to even higher
speeds. Soon it became clear that to go further, one needed bigger space. That
became a difficulty which needed to be overcome. To proceed further with
such accelerating machines, the scientists had to find a way to use smaller
electric fields and do it in the limited space of the laboratory.
The first such compact accelerator that speeds up the sub-atomic particles
like the electron and proton was the cyclotron, which is a circular machine
invented by Ernest O. Lawrence in 1929. It was a major step forward. Ernest
O. Lawrence was born to Norwegian parents and after his Ph.D. from Yale
university contributed to the making of the atom bombs in Los Alamos. His
idea was to make charged particles go round in spirals as they gain more and
more speed within a confined space. The new ideas used here were first to
realize that moving charged particle move in circular paths in a magnetic field.
This was used to make the circular beams of charged particles. They were then
allowed to pass through gaps between two semicircular “dishes” which had
an electric field. The electric field came from the two faces of the gap being
electrically connected to the two terminals of an alternating current source.
The electric field accelerates them in opposite directions in each gap, if the
time it takes for the charged particle from one gap to the other is such that,
it matches the half period of the alternating current. This would effectively
add to the previous speed. A steady magnetic field makes the beam go around
in a circle as just noted. Thus it made very clever use of alternating currents
(oscillating fields) and magnetic fields to build beams of highly energetic