Electromagnetic Ion Cyclotron Waves at Proton Cyclotron Harmonics
Cyclotron Produced Radionuclides
Transcript of Cyclotron Produced Radionuclides
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CyclotronProduced
Radionuclides
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The majority of radionuclide are artificially
produced in Cyclotron and Reactor.
Some short lived radionuclide are available
from radionuclide generators in which long
lived parents are loaded and decay to short
lived daughters.
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Cyclotron
Cyclotron is known as particle accelerator to
accelerate charged particle to a very high
speed.
It uses crossed magnetic and electric fields
at right angles.
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Construction of cyclotron
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Construction of cyclotron
It consists of two hollowsemicircular Dees sonamed because of theirD-shape.
The plane of Dees is theplane of revolution ofcharged particle,preferably a planemidway in the Dees.
The Dees are constructedof conducting materiallike copper -> in order
1. to function as electrodes
for applying alternatingelectrical potential usingelectrical source knownas electrical oscillator
2. to shield moving
charged particle fromelectric field within theDees.
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Construction of cyclotron
The Dees are kept face to face diametricallyopposite at a small distance known as thegap.
Electric field operates only in the gap tochange speed of the charged particle.
The electric field does not accelerate charged
particle when it is moving along semicircularpath within the Dees as it is shielded fromelectrical field.
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Construction of cyclotron
There is an exit channel at the perimeter ofone of Dees which finally guides theaccelerated charged particle towards a target.
The whole set up of Dees is placed betweentwo poles of a powerful magnetic such that itsfield is perpendicular to the plane of Dees andhence perpendicular to the plane of motion.
This system of Dees is placed in evacuatedconfinement.
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Working
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Working principle
The charged particle (say a positively charged
proton) is released near mid point of the face
of one of the Dees.
Being in the electric field from one Dee to
another, it is accelerated by the electric force
in the direction of electric field.
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Working principle
As the particle enters the adjoining Dee, themagnetic force, being perpendicular to it,renders the charged particle to move along a
semicircular path within the Dee. By the time, it emerges again in the narrow
gap separating the two Dees, the electricalpolarity of Dees changes so that the particle isagain accelerated again with an increase inspeed
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Frequency of alternating voltage
supply
Numbers of changes in
directions are equal to
numbers of revolutions.
This means thatfrequency of electric
oscillator should be
equal to frequency of
revolutions.
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CyclotronProduced Radionuclides
These acceleratedparticles can posses afew keV to BeV ofkinetic energydepending on thedesign of cyclotron.
The charged particle aredeflected by a deflectorthrough window (w)outside the cyclotron toform an external beam.
In a cyclotron chargedparticles (S) such asprotons, deuterons,alpha particles ,He-particles are used
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Contd
When the targets of
stable elements are
irradiated by placing
them in the external
beam of the accelerated
particles .
The accelerated particles
interact with the targetnuclei and nuclear
reactions take place.
In nuclear reaction, the
incident particle may
leave the nucleus after
interaction with a
nucleon (i.e , protons and
neutrons) , leaving some
energy in it , or it may be
completely absorbed by
the nucleus depending on
the energy of the
incident particle.
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Contd
In either case , a nucleuswith excitation energy isformed and the excitationenergy is disposed of byemission of nucleons.
Depending on the energydeposited by the incidentparticle several nucleonare emitted randomly
from the irradiated targetnucleus leading to theformation of differentnuclides.
As the energy of theirradiated particle isincreased , more nucleonsare emitted and muchwider variety of nuclidesis produced.
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Medical cyclotrons
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Cyclotron produced radionuclides are
usually neutron deficient and therefore decay
by emission or electron capture.