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ACKNOWLEDGEMENT

1. I express my deep gratitude toMrs. Juhi mam, Army Public School,

MHOW for her useful guidance.2. I also take opportunity to thank

Mr.kashyap, phy. Lab assistant for his

great help.

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DECLARATION

I hereby declare that with the exception of

guidance and suggestion received from my

superior and HOD of physics department ArmyPublic School, MHOW, this investigatory project is

my unaided work. It was carried out in physics

Lab.

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CERTIFICATE

This is to certify that Master Abdul Sohel worked

on the determination of minimum quantity ofmaterial required.

The candidate has completed his work under the

supervision of the teacher incharge. This project

may be considered as the fulfilment of the

examination by CBSE Board, New Delhi for class

XIIth year(2012-2013).

Date: Signature of HOD

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Cyclotron

A cyclotron is a type of particle accelerator in

which charged particles accelerate outwards

from the center along a spiral path. Theparticles are held to a spiral trajectory by a

static magnetic field and accelerated by a

rapidly varying (radio frequency) electric field.

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Principle of operationCyclotrons accelerate charged particle beams using ahigh

frequencyalternatingvoltagewhich is applied between two

"D"-shaped electrodes (also called "dees"). An additional

static magnetic field is applied in perpendicular direction to

the electrode plane, enabling particles to re-encounter the

accelerating voltage many times at the same phase. To

achieve this, the voltage frequency must match the particle's

cyclotron resonancefrequency

,

with therelativistic massm and its charge q. This frequency is

given by equality ofcentripetal forceand magnetic Lorentz

force. The particles, injected near the centre of the magnetic

field, increase theirkinetic energyonly when recirculating

through the gap between the electrodes; thus they travel

outwards along a spiral path.

Their radius will increase until the particles hit a target at the

perimeter of the vacuum chamber, or leave the cyclotronusing a beam tube, enabling their use e.g. for particle therapy.

Various materials may be used for a target, and the collisions

will create secondary particles which may be guided outside

of the cyclotron and into instruments for analysis.

http://en.wikipedia.org/wiki/High_frequencyhttp://en.wikipedia.org/wiki/High_frequencyhttp://en.wikipedia.org/wiki/High_frequencyhttp://en.wikipedia.org/wiki/High_frequencyhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Cyclotron_resonancehttp://en.wikipedia.org/wiki/Cyclotron_resonancehttp://en.wikipedia.org/wiki/Relativistic_masshttp://en.wikipedia.org/wiki/Relativistic_masshttp://en.wikipedia.org/wiki/Relativistic_masshttp://en.wikipedia.org/wiki/Centripetal_forcehttp://en.wikipedia.org/wiki/Centripetal_forcehttp://en.wikipedia.org/wiki/Centripetal_forcehttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Centripetal_forcehttp://en.wikipedia.org/wiki/Relativistic_masshttp://en.wikipedia.org/wiki/Cyclotron_resonancehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/High_frequencyhttp://en.wikipedia.org/wiki/High_frequency

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SynchrocyclotronA synchrocyclotron is a cyclotron in which the frequency of

the driving RF electric field is varied to compensate for

relativistic effects as the particles' velocity begins to approach

the speed of light. This is in contrast to the classical cyclotron,

where the frequency was held constant, thus leading to the

synchrocyclotron operation frequency being

,

where is the classical cyclotron frequency and again is

the relative velocity of the particle beam.

The rest mass of an electron is 511 keV/c2, so the frequency

correction is 1% for a magnetic vacuum tube with a

5.11 keV/c2 direct current accelerating voltage. The proton

mass is nearly two thousand times the electron mass, so the

1% correction energy is about 9 MeV, which is sufficient to

induce nuclear reactions.

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Isochronous cyclotronAn alternative to the synchrocyclotron is the isochronous cyclotron, which has a

magnetic field that increases with radius, rather than with time. Isochronous

cyclotrons are capable of producing much greater beam current thansynchrocyclotrons, but require azimuthal variations in the field strength to

provide astrong focusingeffect and keep the particles captured in their spiraltrajectory.

Recalling the relativisticgyroradius

and the relativistic cyclotron frequency , one can choose to be

proportional to the Lorentz factor, . This results in the relation

which again only depends on the velocity , like in the non-relativistic case.Also, the cyclotron frequency is constant in this case.

The transverse de-focusing effect of this radial field gradient is compensated by

ridges on the magnet faces which vary the field azimuthally as well. This allows

particles to be accelerated continuously, on every period of theradio frequency

(RF), rather than in bursts as in most other accelerator types. This principle thatalternating field gradients have a net focusing effect is calledstrong focusing. It

was obscurely known theoretically long before it was put into practice.[7]

Examples of isochronous cyclotrons abound; in fact almost all modern

cyclotrons use azimuthally-varying fields. The TRIUMF cyclotron mentioned

below is the largest with an outer orbit radius of 7.9 metres, extracting protons

at up to 510 MeV, which is 3/4 of the speed of light. The PSI cyclotron reacheshigher energy but is smaller because of using a higher magnetic field.

http://en.wikipedia.org/wiki/Strong_focusinghttp://en.wikipedia.org/wiki/Strong_focusinghttp://en.wikipedia.org/wiki/Strong_focusinghttp://en.wikipedia.org/wiki/Gyroradiushttp://en.wikipedia.org/wiki/Gyroradiushttp://en.wikipedia.org/wiki/Gyroradiushttp://en.wikipedia.org/wiki/Radio_frequencyhttp://en.wikipedia.org/wiki/Radio_frequencyhttp://en.wikipedia.org/wiki/Radio_frequencyhttp://en.wikipedia.org/wiki/Strong_focusinghttp://en.wikipedia.org/wiki/Strong_focusinghttp://en.wikipedia.org/wiki/Strong_focusinghttp://en.wikipedia.org/wiki/Cyclotron#cite_note-lhthomas-7http://en.wikipedia.org/wiki/Cyclotron#cite_note-lhthomas-7http://en.wikipedia.org/wiki/Cyclotron#cite_note-lhthomas-7http://en.wikipedia.org/wiki/Cyclotron#cite_note-lhthomas-7http://en.wikipedia.org/wiki/Strong_focusinghttp://en.wikipedia.org/wiki/Radio_frequencyhttp://en.wikipedia.org/wiki/Gyroradiushttp://en.wikipedia.org/wiki/Strong_focusing

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UsageFor several decades, cyclotrons were the best source of high-

energy beams fornuclear physicsexperiments; several

cyclotrons are still in use for this type of research. The results

enable the calculation of various properties, such as the meanspacing between atoms and the creation of various collision

products. Subsequent chemical and particle analysis of the

target material may give insight intonuclear transmutationof

the elements used in the target.

Cyclotrons can be used inparticle therapyto treatcancer. Ion

beams from cyclotrons can be used, as inproton therapy, to

penetrate the body and kill tumors byradiation damage, whileminimizing damage to healthy tissue along their path.

Cyclotron beams can be used to bombard other atoms to

produce short-livedpositron-emitting isotopes suitable for

PET imaging.

More recently cyclotrons currently installed at hospitals for

particle therapy have been retrofitted to enable them toproducetechnetium-99.[8]Technetium-99 is a diagnostic

isotope in short supply due to difficulties at Canada'sChalk

Riverfacility.

http://en.wikipedia.org/wiki/Nuclear_physicshttp://en.wikipedia.org/wiki/Nuclear_physicshttp://en.wikipedia.org/wiki/Nuclear_physicshttp://en.wikipedia.org/wiki/Nuclear_transmutationhttp://en.wikipedia.org/wiki/Nuclear_transmutationhttp://en.wikipedia.org/wiki/Nuclear_transmutationhttp://en.wikipedia.org/wiki/Particle_therapyhttp://en.wikipedia.org/wiki/Particle_therapyhttp://en.wikipedia.org/wiki/Particle_therapyhttp://en.wikipedia.org/wiki/Cancerhttp://en.wikipedia.org/wiki/Cancerhttp://en.wikipedia.org/wiki/Cancerhttp://en.wikipedia.org/wiki/Proton_therapyhttp://en.wikipedia.org/wiki/Proton_therapyhttp://en.wikipedia.org/wiki/Proton_therapyhttp://en.wikipedia.org/wiki/Radiation_poisoninghttp://en.wikipedia.org/wiki/Radiation_poisoninghttp://en.wikipedia.org/wiki/Radiation_poisoninghttp://en.wikipedia.org/wiki/Positronhttp://en.wikipedia.org/wiki/Positronhttp://en.wikipedia.org/wiki/PET_imaginghttp://en.wikipedia.org/wiki/PET_imaginghttp://en.wikipedia.org/wiki/Technetium-99http://en.wikipedia.org/wiki/Technetium-99http://en.wikipedia.org/wiki/Cyclotron#cite_note-8http://en.wikipedia.org/wiki/Cyclotron#cite_note-8http://en.wikipedia.org/wiki/Cyclotron#cite_note-8http://en.wikipedia.org/wiki/Chalk_River_Laboratorieshttp://en.wikipedia.org/wiki/Chalk_River_Laboratorieshttp://en.wikipedia.org/wiki/Chalk_River_Laboratorieshttp://en.wikipedia.org/wiki/Chalk_River_Laboratorieshttp://en.wikipedia.org/wiki/Chalk_River_Laboratorieshttp://en.wikipedia.org/wiki/Chalk_River_Laboratorieshttp://en.wikipedia.org/wiki/Cyclotron#cite_note-8http://en.wikipedia.org/wiki/Technetium-99http://en.wikipedia.org/wiki/PET_imaginghttp://en.wikipedia.org/wiki/Positronhttp://en.wikipedia.org/wiki/Radiation_poisoninghttp://en.wikipedia.org/wiki/Proton_therapyhttp://en.wikipedia.org/wiki/Cancerhttp://en.wikipedia.org/wiki/Particle_therapyhttp://en.wikipedia.org/wiki/Nuclear_transmutationhttp://en.wikipedia.org/wiki/Nuclear_physics

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Advantages and limitations

The cyclotron was an improvement over thelinear

accelerators(linacs) that were available when it was invented,

being more cost- and space-effective due to the iterated

interaction of the particles with the accelerating field. In the

1920s, it was not possible to generate the high power, high-frequency radio waves which are used in modern linacs

(generated byklystrons). As such, impractically long linac

structures were required for higher-energy particles. The

compactness of the cyclotron reduces other costs as well, such

as foundations, radiation shielding, and the enclosing

building.

Cyclotrons have a single electrical driver, which saves both

money and power. Furthermore, cyclotrons are able to

produce a continuous stream of particles at the target, so the

average power passed from a particle beam into a target is

relatively high.

The magnet portion of a 27" cyclotron. The gray object is the

upper pole piece, routing the magnetic field in two loops

through a similar part below. The white canisters held

conductive coils to generate the magnetic field. The D

electrodes are contained in a vacuum chamber that was

inserted in the central field gap.

http://en.wikipedia.org/wiki/Linear_acceleratorhttp://en.wikipedia.org/wiki/Linear_acceleratorhttp://en.wikipedia.org/wiki/Linear_acceleratorhttp://en.wikipedia.org/wiki/Linear_acceleratorhttp://en.wikipedia.org/wiki/Klystronhttp://en.wikipedia.org/wiki/Klystronhttp://en.wikipedia.org/wiki/Klystronhttp://en.wikipedia.org/wiki/Linear_acceleratorhttp://en.wikipedia.org/wiki/Linear_accelerator

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Thespiralpath of the cyclotron beam can only "sync up" with

klystron-type (constant frequency) voltage sources if the

accelerated particles are approximately obeyingNewton's

Laws of Motion. If the particles become fast enough thatrelativisticeffects become important, the beam becomes out

of phase with the oscillating electric field, and cannot receive

any additional acceleration. The classical cyclotron is

therefore only capable of accelerating particles up to a few

percent of the speed of light. To accommodate increased mass

the magnetic field may be modified by appropriately shaping

the pole pieces as in theisochronous cyclotrons, operating in apulsed mode and changing the frequency applied to the dees

as in thesynchrocyclotrons, either of which is limited by the

diminishing cost effectiveness of making larger machines.

Cost limitations have been overcome by employing the more

complexsynchrotronor modern, klystron-driven linear

accelerators, both of which have the advantage of scalability,

offering more power within an improved cost structure as the

machines are made larger.

http://en.wikipedia.org/wiki/Spiralhttp://en.wikipedia.org/wiki/Spiralhttp://en.wikipedia.org/wiki/Spiralhttp://en.wikipedia.org/wiki/Newton%27s_Laws_of_Motionhttp://en.wikipedia.org/wiki/Newton%27s_Laws_of_Motionhttp://en.wikipedia.org/wiki/Newton%27s_Laws_of_Motionhttp://en.wikipedia.org/wiki/Newton%27s_Laws_of_Motionhttp://en.wikipedia.org/wiki/Special_Relativityhttp://en.wikipedia.org/wiki/Special_Relativityhttp://en.wikipedia.org/wiki/Isochronous_cyclotronhttp://en.wikipedia.org/wiki/Isochronous_cyclotronhttp://en.wikipedia.org/wiki/Isochronous_cyclotronhttp://en.wikipedia.org/wiki/Synchrocyclotronhttp://en.wikipedia.org/wiki/Synchrocyclotronhttp://en.wikipedia.org/wiki/Synchrocyclotronhttp://en.wikipedia.org/wiki/Synchrotronhttp://en.wikipedia.org/wiki/Synchrotronhttp://en.wikipedia.org/wiki/Synchrotronhttp://en.wikipedia.org/wiki/Synchrotronhttp://en.wikipedia.org/wiki/Synchrocyclotronhttp://en.wikipedia.org/wiki/Isochronous_cyclotronhttp://en.wikipedia.org/wiki/Special_Relativityhttp://en.wikipedia.org/wiki/Newton%27s_Laws_of_Motionhttp://en.wikipedia.org/wiki/Newton%27s_Laws_of_Motionhttp://en.wikipedia.org/wiki/Spiral

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Notable examples

TRIUMF, Canada's national laboratory for nuclear andparticle physics, houses one of the world's largest cyclotrons.

The 18 m diameter, 4,000 tonne main magnet produces a field

of 0.46 T while a 23 MHz 94 kV electric field is used to

accelerate the 300 A beam. Its large size is partly a result of

using negative hydrogen ions rather than protons. The

advantage is that extraction is simpler; multi-energy, multi-

beams can be extracted by inserting thin carbon stripping foilsat appropriate radii. The disadvantage is that the magnetic

field is limited: a magnetic field larger than about 0.5 tesla can

prematurely strip the loosely-bound second electron.

TRIUMF is run by a consortium of sixteen Canadian

universities and is located at the University of British

Columbia, Vancouver, Canada.

The world's largest cyclotron is at the RIKEN laboratory inJapan. Called the SRC, for Superconducting Ring Cyclotron,

it has 6 separated superconducting sectors, and is 19 m in

diameter and 8 m high. Built to accelerate heavy ions, its

maximum magnetic field is 3.8 tesla, yielding a bending

ability of 8 tesla-metres. The total weight of the cyclotron is

8,300 tonnes. It has accelerated uranium ions to 345 MeV per

atomic mass unit.[

http://en.wikipedia.org/wiki/Cyclotron#cite_note-9http://en.wikipedia.org/wiki/Cyclotron#cite_note-9http://en.wikipedia.org/wiki/Cyclotron#cite_note-9http://en.wikipedia.org/wiki/Cyclotron#cite_note-9

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contents

ACKNOWLEDGEMENT DECLARATION CERTIFICATE CYCLOTRON PRINCIPLE OF OPERATION SYNCHROCYCLOTRON ISOCHRONOUS CYCLOTRON ADVANTAGES AND LIMITATIONS NOTABLE EXAMPLES

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