Transcript How Are Electric And Magnetic Fields Used To Steer

How Are Electric And Magnetic
Fields Used To Steer
Particles In The
Large Hadron Collider?
Effect of a Uniform Electric Field on
the Motion of Charged Particles
In an electrical field the motion of a charged particle will experience
a constant upwards force with a constant vertical acceleration and a
constant horizontal velocity. Because the field is uniform meaning
the lines in the field will remain the same throughout the field –
parallel and equispaced.
Electric Field Strength:
Uniform Electric Field Strength:
E = electric field strength
V = the pd between the plates
F = force acting in Newton’s
d = the distance separating the
plates.
q = the charge in coulombs
Units of E: NC-1 or Vm-1
Units of E: NC-1 or Vm-1
Effect of a Uniform Magnetic Field
on the Motion of Charged Particles
When a charged particle enters a magnetic field it will be forced to
change direction. If it stays in the field it will continue to change
direction and will move in a circle. The force produced will provide
the centripetal force on the moving particle.
Force on a charged particle in a magnetic field equation:
F = B q v sin θ
F = force (N)
B = magnetic field strength (T)
q = charge on the particle (C)
v = velocity of the particle (m/s)
(Angle θ is between the direction of the beam and the magnetic field direction)
Motion of Charged Particles
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Charged particles such as electrons or protons are accelerated by an
electric field to speeds almost equal to the speed of light. They are made to
collide with one another and in such collisions some of the kinetic energy is
turned into matter - new particles are created.
The simplest particle accelerator is the electron gun. The electrons are
produced by heating a cathode. The electrons 'boil' off from the cathode and
are accelerated towards an anode with a small hole in it. Many of the
electrons pass through the hole forming an electron ray (cathode ray). The
energy of the electrons is found using Energy = eV.
Linear Accelerometers
Cyclotrons
• The length limitation can be overcome by making the charged
particles follow a circular path. In a cyclotron charged particles are
accelerated across the gap between two 'D' shaped electrodes.
Meanwhile a perpendicular magnetic field moves the particles in a
circle. The radius of the circle increases after each successive
acceleration, so the path spirals out from the source at the centre to
the target on the outside.
Large Hadron Collider
• The collider refers to a single aspect of the
project. The collider itself weighs 38,000 tonnes
and spans a full circle that is 27km long or 16.5
miles. The collider sits 100m under and around
Geneva on the French/Swiss border.
• The LHC is supported by engineers and
scientists across the globe but the UK has a
lead role in the project as their engineers and
scientists are involved with all main
experiments.
• The LHC accelerates two beams of atomic particles in opposite directions around the 27km collider.
When the particle beams reach their maximum speed the LHC allows them to ‘collide’ at 4 points on their
circular journey.
• Thousands of new particles are produced when particles collide and detectors, placed around the
collision points, allow scientists to identify these new particles by tracking their behaviour.
The detectors are able to follow the millions of collisions and new particles produced every second and
identify the distinctive behaviour of interesting new particles from among the many thousands that are of
little interest.
• As the energy produced in the collisions increases researchers are able to peer deeper into the
fundamental structure of the Universe and further back in its history. In these extreme conditions unknown
atomic particles may appear.