Electron-Positron Colliders vs Proton-Proton Colliders
Circular Proton-Proton Colliders
- Colliders that allow higher energies and are suitable for
discoveries of distinct new phenomena
- Protons have a large mass compared to that of electrons and can be
accelerated in a circular accelerator
up to higher energies without synchrotron radiation loss.
There is a proton-proton collider project called LHC in Europe,
aiming at an energy above 10TeV.
Hadron colliders such as LHC are good at quickly surveying energy
frontiers, though the signals have to be distinct from the huge
background inherent in the collisions of
strongly interacting composite particles such as protons.
In addition, the collision energies of the constituents are
uncontrollable, which complicates the experiments thereat.
Nevertheless, when the signal is clean, hadron colliders can be
very effective as has been demonstrated at CERN by discovering
the W and Z particles.
Circular Electron-Positron Colliders
- Circular electron-positron colliders can
hardly compete with hadron colliders in terms of energy.
They are, however, suitable for precision measurements
and therefore stringent tests of fundamental principles.
- Electrons and positrons are pointlike particles
which interact with each other through electroweak force and
therefore their collision energy is well controlled and
the background is small. Because of this we can detect essentially
all the new phenomena up to the total energy of the two beams.
It is, however, practically impossible to achieve an energy
comparable to that of LHC with a circular electron-positron
collider such as TRISTAN or LEP
due to the synchrotron radiation loss which increases as
the fourth power of the beam energy.
Linear Electron-Positron Colliders
To next page,
To previous page,
To table of contents
- Linear electron-positron colliders
provide an effective collision
energy of constituents similar
to that of proton-proton colliders:
The effective collision energy of a 10TeV proton-proton collider
is equivalent to that of a 1TeV electron-positron collider.
Moreover, being electron-positron colliders, they allow us to detect
essentially all the new phenomena up to the kinematical limit and
provide opportunities to study them in detail.
- The linear collider is a new kind of collider which consist of
an electron linac and a positron linac opposing to each other.
The collider has no curved sections downstream of damping rings
and are therefore free from
the energy limitation due to synchrotron radiation.
JLC will enable us to study various new phenomena unambiguously and
will lead us to pin down underlying new physics.
It should be also emphasized that the polarized electron beam is
essential to controlling reaction types to be studied.
firstname.lastname@example.org Feb 09, 1995