CHARGE PARTICLE ACCELERATOR

3. What is Particle Accelerator?
 A Particle accelerator is a device used for
increasing the kinetic energy of electrically
charged particles.
 The accelerators are the important
instruments in conducting research
concerning particles such as mesons, anti-proton,
and anti-neutron.

4.  Van de Graff generator
 Cyclotron
 Synchrocyclotron
 Betatron
 Electron-Synchrotron
 Alternating Synchrotron
 Linear Accelerator

6.  E.O Lawrence and M.S Livingston invented
this Device at Berkeley (united state) in1931.
 Cyclotron is the earliest and simplest
accelerator, and also called the magnetic
resonance oscillator.
 Cyclotron is used to accelerate Positive
Charged particles.

7.  Cyclotrons produce very high energy Charge
Particles.
 E.O Lawrence awarded a noble prize for the
development of the cyclotron.

8.  In Electric Field a charged particle is
accelerated.
 In Magnetic field a charged particle can be
turned around.
 In magnetic field the magnetic force acts as a
centripetal force.
 Cyclotrons accelerate Charged particle beam
using a high alternating voltage oscillator
which is applied between two "D“ shaped
electrodes (also called "Dees")

10.  The cyclotron consists of two flat semicircular
metallic boxes D1 and D2 called the Dees on
account of their shape like the letter D.
 The two Dees are separated by a narrow gap.
 The Dees are connected to the terminals of a
high frequency oscillator, so that a potential
of several million cycle per second is applied
between the Dees, which act as an electrode.

11.  Oscillator establishes an alternating electric field
in the gap between the Dees, i.e. the electric field
is once directed towards D1 and then towards D2
Thus D1 and D2 become alternating positive and
negative at the same rate.
 A source is placed at the center of the Dees
which supplies a positive ion to accelerate.
 These Dees are mounted inside a vacuum
chamber; the chamber is mounted horizontally
between the pole pieces (N&S) of a huge
electromagnet capable of producing a vertical
field.

12. Adnan Shahzada M.Sc Physics,
University of Peshawar

15.  The positive ions emitted from the source will be
accelerated in the gap towards the Dee which is
negative at that time.
 Let it be D2 Since, there is no electric field inside
the Dees, the positive ion move with constant
velocity along circles of constant radius under
the influence of magnetic field which is
perpendicular the Dees.
 If the ions emerge from D2 , the polarity of the
applied potential is reversed, the positive ions
will again face the negative Dee and thus will be
again accelerated by the Electric in the gap.

17.  Since, there velocity is increased, they will now
move through along D1 Circular arc of greater
radius.
 Here, the time passage to complete the semi –
circle in the D1 remains the same as in D2.
 In this way the positive ions move faster and faster
moving in ever – expanding circles until they reach
the outer edge of the Dees, where they are
deflected by deflector flat and strike the target.
 Here it should be remembered that the time
required for the positive ions to make one
complete turn within Dees is equal to the time
period of the oscillator.

18. Radius
The magnetic force acting on the charge particle is
given by
As this force acts as centripetal force, so we have
Above equation represents the radius of the circular
path followed by the charged particle inside the
magnetic field

19. Note: Radius at each turn increase due to increase
in velocity, therefore it behaves like the spiral.
Angular velocity
Above equation represents the angular velocity

20. Frequency
Above equation represents the frequency of
circulating charge
Time Period
This is the required time period of circulating
charge.

21. Note: From the calculation we came to know that
the Frequency and Time period are independent
of radius.
Kinetic Energy
This is the required kinetic energy of the
circulating ion.

22.  It cannot accelerate neutron, because neutron
do not have any charge.
 It cannot accelerate electron because of its
small mass.

23.  Cyclotron is used to bombard nuclei with
energetic particles and observe the nuclear
reactions.
 Cyclotron is used for different radioactive
tests in hospitals for diagnosis. Like in the
treatment of Cancer.

24.  Introduction to Atomic and Nuclear Physics By
Henry Semat and John R. Albright
 Introduction to Nuclear Physics By Kenneth S.
Krane
 Introduction to Nuclear physics by Irving
kaplan
Thanks