Elementary Particles
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energy of 26 GeV and then to an energy of about 270 GeV in a super proton
synchrotron. The same synchrotrons are used for speeding-up protons as well,
and providing a beam of 240 GeV protons. Since the protons and the antiprotons
are oppositely charged, they move in opposite directions in the synchrotrons.
It was in the collision of 270 collision of 2w70 GeV proton antiproton
beams at CERN that the W and Z bosons were produced recently; and identified
by their characteristic decays. These bosons, which are essential for the
propagation of unified weak-electromagnetic interaction, were found to have a
mass of m W ≈ 81 GeV and m Z ≈ 95 GeV. This has been an important step in the
confirmation of the theory of unified weak-electromagnetic interaction.
Finally, it may be noted that colliding-beam experiments have also been
performed with electron and positron beams, which have provided important
information about the properties of weak-electromagnetic interaction and of
elementary particles.
Scintillation Counters and Semiconductor Counters
Elementary particles are observed by the traces left by their electromagnetic
interaction with matter. In scintillation counters, charged particles passing
through the substance (known as a scintillator) of the counter, excite the atoms.
These atoms emit visible light on returning to their normal state. This light is
supplied to photomultipliers which then give information about the charged
particles.
In semiconductor counters, a charged particle passing through a junction
layer with an applied potential, gives rise to electrons and holes. The electric
pulse generated by them gives information about the number of charge carriers
and hence about the particle which created them.
Wilson Cloud Chamber and Diffusion Chamber
In the Wilson cloud chamber (1912), the track of a charged particle becomes
visible due to the condensation of the supersaturated vapour of a liquid, on the
ions formed in the track. The supersaturated condition is obtained by the sudden
expansion of a mixture consisting of a noncondensing gas (such as helium,
argon, nitrogen) and water vapour, ethyl alcohol, etc. The track produced by the
condensation of the vapour can be photo-graphed from different angles to
reproduce a three dimensional picture. It may be noted that the sensitivity of
the state of supersaturation lasts only for a short period so that the instrument is
operated in cycles.
The diffusion chamber works along the same lines as the cloud chamber
except that the state of super saturation is produced as a result of diffusions of
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energy of 26 GeV and then to an energy of about 270 GeV in a super proton
synchrotron. The same synchrotrons are used for speeding-up protons as well,
and providing a beam of 240 GeV protons. Since the protons and the antiprotons
are oppositely charged, they move in opposite directions in the synchrotrons.
It was in the collision of 270 collision of 2w70 GeV proton antiproton
beams at CERN that the W and Z bosons were produced recently; and identified
by their characteristic decays. These bosons, which are essential for the
propagation of unified weak-electromagnetic interaction, were found to have a
mass of m W ≈ 81 GeV and m Z ≈ 95 GeV. This has been an important step in the
confirmation of the theory of unified weak-electromagnetic interaction.
Finally, it may be noted that colliding-beam experiments have also been
performed with electron and positron beams, which have provided important
information about the properties of weak-electromagnetic interaction and of
elementary particles.
Scintillation Counters and Semiconductor Counters
Elementary particles are observed by the traces left by their electromagnetic
interaction with matter. In scintillation counters, charged particles passing
through the substance (known as a scintillator) of the counter, excite the atoms.
These atoms emit visible light on returning to their normal state. This light is
supplied to photomultipliers which then give information about the charged
particles.
In semiconductor counters, a charged particle passing through a junction
layer with an applied potential, gives rise to electrons and holes. The electric
pulse generated by them gives information about the number of charge carriers
and hence about the particle which created them.
Wilson Cloud Chamber and Diffusion Chamber
In the Wilson cloud chamber (1912), the track of a charged particle becomes
visible due to the condensation of the supersaturated vapour of a liquid, on the
ions formed in the track. The supersaturated condition is obtained by the sudden
expansion of a mixture consisting of a noncondensing gas (such as helium,
argon, nitrogen) and water vapour, ethyl alcohol, etc. The track produced by the
condensation of the vapour can be photo-graphed from different angles to
reproduce a three dimensional picture. It may be noted that the sensitivity of
the state of supersaturation lasts only for a short period so that the instrument is
operated in cycles.
The diffusion chamber works along the same lines as the cloud chamber
except that the state of super saturation is produced as a result of diffusions of