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A. Cianchi Particle Accelerators For Science And Interdisciplinary Applications

Particle accelerators

Alessandro Cianchi

2A. Cianchi Particle Accelerators For Science And Interdisciplinary Applications

Particle accelerators: instructions

48 hrs lectures (16:00 Monday T8bis,11:00 Tuesday T8bis)

No lecture 8,9,15,16 April All the documentation is available via web in pdf @ http://didattica.uniroma2.it/informazioni/index/insegna

mento/180277-Particle-Accelerators-For-Science-And-Interdisciplinary-Applications

Point of view: Physics We will face all the fundamental principles of particle

accelerators But we’ll focus also on the ingoing activities at the

next door


LNF: the next door

A tour of the accelerators @LNF is included in the course (Jun 3rd likely)

Staff = 350Associates = 181Visitors = 463TOTAL 994


Final test

Oral examination

Any problem? [email protected]

People interested in email update please send me an email to make an address book


Basic Syllabus I

Introduction to the importance of the accelerators The history line: Electrostatic accelerators Electrodynamics accelerators:

Cyclotron Betatron Microtron Synchrotron Colliders

Linear optics in the accelerators Equation of motion Transverse dynamics Betatron oscillation Emittance: definition, meaning, measurement The beam envelope equation Resonance and instabilities


Basic Syllabus II

Longitudinal dynamics Phase stability Equation of motion

The Synchrotron radiation The physics of Synchrotron radiation Transverse and longitudinal dynamics with radiation Light sources FEL

Accelerating structures RF Cavity Principal parameter The future: the plasma acceleration


Background requested

Basic Electromagnetism, Maxwell equations Did you like Electromagnetism? Good! Did you experience problems? It’s time to make peace!

Special relativity


Melting pot


What is an accelerator?

It is a device that transfers energy to charged particle by electromagnetic or electrostatic fields. The particles are injected at initial energy of Ti and they arrive to final energy Tf.

Source Accelerator Target

Ti Tf


What are accelerators used for?

Understanding the fundamental building blocks of nature and the forces that act upon them (nuclear and particle physics)


Investigate the matter

Understanding the structure and dynamics ofmaterials and their properties (physics, chemistry,biology, medicine) via neutron spallation source oSynchrotron and FEL light sources


X radiation with fs pulse length

Investigation of the molecular dynamics, chemicalreaction time resolved. Wide range of applicationsfrom physics to pharmacy


Inverse Compton Scattering


Medical application of ions

Medical treatment of tumors and cancers, using the properties of the Bragg peak


Big machines for medical treatment

CNAO is the first center in Italy for tumor treatment using ions produced in a particle accelerator


Production of medical isotopes

Small size machine devoted to the production of short half-life radioactive isotopes


Applications

Accelerators (compact cyclotrons or linacs) are used to produce radioisotopes for medical imaging.


Ion implantation

Electrostatic accelerators are used to deposit ions in semiconductors.


Electron beam processing

In the US, potential markets for industrialelectron beams total $50 billion per year.

33% Wire cable tubing 32% Ink curing 17% shrink film 7% service 5% tyres 6% other

When polymers are cross-linked, canbecome:

• stable against heat,• increased tensile strength, resistance tocracking• heat shrinking properties etc


Sterilization

Manufacturers of medical disposables have to kill every germ on syringes, bandages, surgical tools and other gear, without altering the material itself.

E-beam sterilization works best on simple, low density products.

Advantages: takes only a few seconds (gamma irradiation can take hours)

Disadvantages: limited penetration depth, works best on simple, low density products (syringes)


Food irradiation

‘Cold pasteurisation’ or ‘electronic pasteurisation’

Uses electrons (from an accelerator) or X-rays producedusing an accelerator.

The words ‘irradiated’ or ‘treated with ionizing radiation’ must appear on the label packaging.


Spallation sources


Stresses in Airbus A380 Wing

Aircraft manufacturer Airbus has used neutrons since 2006

Research into aluminum alloy weld integrity for aircrew programs

Residual stresses from welding cause weaknesses and the possibility of cracks

Neutrons look deep inside engineering components to measure stress fields


Fast neutron for semiconductor industry

Atmospheric neutrons collide with microchips and upset microelectronic devices every few seconds

300 x greater effect at high altitude

Neutrons enables manufacturers to mitigate against the problem of cosmicradiation

Increased confidence in the quality and safety of aerospaceelectronic systems


Driver for fission reactor

MYRRHA as in Multi-purpose hYbrid Research Reactor for High-tech Applications

MYRRHA is the very first prototype of a nuclear reactor driven by a particle accelerator in the world.

Distinctive feature: as an external source of neutrons, this particle accelerator maintains the nuclear fission chain reaction.

It is referred to as a subcritical reactor: the core does not contain enough fissile material to spontaneously maintain the chain reaction.


Water treatment


Cargo scan

Cargo containers scanned at ports and bordercrossings

Accelerator-based sources of Xrays can be far more penetrating (6MV) than Co-60 sources.

Container must be scanned in 30 seconds.


Accelerators can study art

This painting “Patch of grass” by Vincent Van Gogh was the first one analyzed by a particleaccelerator

Used X-ray fluorescencetechnique the distribution of Hg and Sb pigment allowed a reconstruction of underlying image


Accelerators can help spot art forgeries

Ion Beam Analysis shows us the chemical composition of pigments used in paint

This allows art historians to compare them with paints available to artists like Leonardo da Vinci


Accelerators in archaeology

The interior of samples can be studied usingaccelerators withoutdestroying them

Pomery from Armenia, dating back to 1300 BC, is set up for synchrotron experiment


Accelerators can make food taste better

Cadbury used X-rays from a particleaccelerator to study how cocoa crystallises

Of the six possible crystal forms, the fifth (form V) produces the best quality chocolate


And also…

The everyone’s accelerator is…

33A. Cianchi

Particle accelerators in the world

Accelerators 1994 2014Industrial >4500 27 000

Electron accelerators >300 keV 1500 ∼5000

Electron accelerators <300 keV >1000 ∼8000

Ion implanters and ion analysis >2000 ∼12 000

Neutron generators ∼2000

Science ∼1000 ∼1200

Medicine ∼4200 ∼14 000

Electron accelerators ∼4000 ∼13 000

Proton and ion accelerators 17 ∼59

Production of radioisotopes ∼200 ∼1100

TOTAL >9700 42 000Source: Chernyaev, A. P., and S. M. Varzar. "Particle accelerators in modern world." Physics of Atomic Nuclei 77.10 (2014): 1203-1215.

34A. Cianchi

Next time someone asks you what accelerators are for

“A beam of the right particles with the right energy at the right intensity can shrink a tumor, produce cleaner energy, spot suspicious cargo, make a better radial tire, clean up dirty drinking water, map a protein, study a nuclear explosion, design a new drug, make a heat-resistant automotive cable, diagnose a disease, reduce nuclear waste, detect an art forgery, implant ions in a semiconductor, prospect for oil, date an archaeological find, package a Thanksgiving turkey or…

…discover the secrets of the universe.”

-Accelerators for Americas FutureReport, pp. 4, DoE, USA, 2011


Units

1 eV: energy of a particle di charge e, initially at rest, after the acceleration by a potential of 1 V

1 eV= 1.60219 10-19 J

1 keV = 103 eV ; 1 MeV = 106 eV 1 GeV = 109 eV; 1 TeV = 1012 eV

Energy of a proton in the LHC: 7 TeV =1.12 x 10-6J the same energy of a body of mass = 1 mg moving

at speed = 1.5 m /s (a mosquito!)


Energy and momentum

Protons are accelerated to a kinetic energy of 200 MeV

Calculate their total energy, their momentum and their velocity in our units


The needs of high energy particles

An accelerator is nothing else than a microscopy

λ =hp

Wavelength of the α– particles used by Rutherford (1911) in the discovery of the atomic nucleus:

m 107.6)s m105.1()kg106.6(

s J 10626.6v

151-727

34−

−

−

×≈×××

×≈=

α

λm

h

0.05 c~ resolving power

of Rutherford’sexperiment

α−particlemass


Probe for micro cosmos

Resolving power

Optical microscopes Visible Light ~ 10−6 m

Electron microscopes Low energy electron ~ 10−10 m

Radioactive sources α particles ~ 10−14 m

Accelerators High energy electron, protons ~ 10−19 m

Another key point is the production of new particles at even higher energy


Time machine


Energy

Colliding beamStationary target


Problem

At LHC there are two colliding beams of 7 TeV If we consider a fixed target experiment how much

must be the energy of the moving beam to achieve the same energy in the center of mass?


Magnetic and electric rigidity

B orthogonal to the particle trajectory

y

x


Only magnetic field to bend the beam

Electron 1 GeV moving on y=0, B=1 T

Calculate the magnetic rigidity, the radius of curvature and the electric field needed to have the same radius of curvature


Energy scale

“Starting from the 1930s, the energy has increased-- by about a factor of 10 every six to eight years… this spectacular achievement has resulted from a succession of technologies rather than from construction of bigger and better machines of a given type.” W. K. H. Panofsky, 1997.


Accelerator history

A. Cianchi Particle Accelerators For Science And Interdisciplinary Applications

Particle accelerators

The Electrostatic Accelerators


References

K. Wille “The Physics of Particle Accelerator”, Oxford University press pag 1-29

H. Wiedeman “Particle accelerator physics” volume 1, chapter 3

Just for your knowledge:

A. Sessler, E. Wilson, “ENGINES OF DISCOVERY”, World Scientific


Principle of operation


Current in electrostatic accelerators

Ohmic: proportional to voltage

Residual ion current: saturates rapidly (also beam)

Corona: negligible for small voltages

Current grows exponentially for high voltages causing spark discharge and voltage breakdown


Paschen’s law

When the pressure increases, the collision probability increases, but the path between two collisions decreases, so also the energy transferred to an electron is decreased.

When the pressure is very low, the path between two collision is quite large, but the probability of a collision is relatively smaller.


Cockroft Walton

Cockroft and Walton were able to accelerate protons to hundreds of keV.

In 1932 they bombarded Lithium with 700 keV protons and transmuted it into Helium and other elements.

This was the first time that a particle accelerator had been use to trigger a nuclear reaction.

Cockroft and Walton were awarded the Nobel prize in 1951.


Voltage Duplicator

During the first quarter cycle the diode D1 is in conduction and the capacitor C1 is charging

During the second quarter cycle the C1 is already charged and nothing changes

During the third quarter cycle the diode D2 is in conduction and the capacitor C2 is charging

During the fourth quarter cycle the C2 is already charged and nothing changes


Cockroft Walton @LNF


Cockcroft Walton @ FERMILAB


Van de Graaff

In a Van de Graaff generator charges are mechanically carried by a conveyor belt from a low potential source to a high potential collector.

Van de Graaff generator can reach several MV and are still used in DC accelerators

~2MV in air Up to 20+ MV in SF6!


Using Van de Graaff


Public science in the ‘30s


Pigeon droppings

Under normal operation, because the electrodes were very smooth and almost perfect spheres, Van de Graf generators did not normally spark.

However, the installation at Round Hill (MIT) was in an open-air hanger, frequented by pigeons, and here we see the effect of pigeon droppings.


WMU


Tandem

Reverse ion charge state in middle of Van de Graaffallows over twice the energy gain

The stripper is usually a gas Source is at ground


Example

Br ion in a Tandem with V0 = 20 MV.

Br ( A = 79 ) charge Z = -1. The beam is accelerated to 20 MeV From the stripper, Ar (density l ≈ 1μg/cm2 ), the beam comes

out with a spectrum of charge with a maximum around Z+≈ 7, and it arrives to Z+ ≈ 10.

Filtering the Z+= 10 ions, these are again accelerated to the energy

E= (1 + Z ) qVo = 220 MeV ( 220/79 = 2.8 MeV/nucleon = 2.8 MeV/A).


Tandem @ LNS


Atomic Mass Spectroscopy

Resolve 1 atom of 14C over 1015 of other Carbon atoms!


Dating old documents

AMS was used to date ashes found in Newfoundland in a European-type settlement. These ashes were dated back to the XIth century.

A Viking map featuring Newfoundland was shown to be older than Columbus’ trip to America. AMS has contributed to establish that North America was visited by Vikings well before other European nations


Limits of electrostatics accelerators

The maximum achievable voltage is limited by discharge

A further disadvantage of accelerating particles with high voltages is that either the source of the particles or the measuring instruments (or even both) have to be at high voltage, which makes any operation rather awkward and even dangerous.


Advantages of Electrostatic Machines

Voltage may be very precisely controlled allows a detailed study of nuclear reactions and in particular narrow resonances in energy

Another interesting application is in the extensive study of the reactions that take place in stars, rather low energy by nuclear physics standards, and therefore requiring exacting work. In 1983 a Nobel Prize was awarded to William Fowler, of Caltech, for his “theoretical and experimental studies of the nuclear reactions of importance in the formation of the chemical elements in the universe”

Experimental work that was all carried out on electrostatic machines.

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