75 Years
of
Particle Accelerators
Andrew M. Sessler
Lawrence Berkeley National Laboratory
Berkeley, CA 94720
Accelerators started with some theoretical work in the
early 1920s, with the first accelerator producing nuclear
reaction in 1931. Thus it is exactly 75 years of history
we shall be reviewing.
Motivation
The first motivation was from Ernest Rutherford who
desired to produce nuclear reactions with accelerated
nucleons.
For many decades the motivation was to get to ever
higher beam energies. At the same time, and especially
when colliding beams became important, there was a desire
to get to ever higher beam current.
In the last three decades there has been motivation from the
many applications of accelerators, such as producing
X-ray beams, medical needs, ion implantation, spallation
sources, and on and on.
Table of Contents
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
Electrostatic Machines
Cyclotrons
Linacs
Betatrons
Synchrotrons
Colliders
Synchrotron Radiation Sources
Cancer Therapy Machines
The Future
Concluding Remarks
I. Electrostatic Accelerators
I.1
I.2
Voltage Multiplying Columns and
Moving Belts
Tandems
I.1 Voltage Multiplying Columns
The first accelerator that produced a nuclear
reaction was the voltage multiplying column that
Cockcroft and Walton built from 1930 to 1932. A
small voltage was applied to condensers in
parallel, and then by a spark gap, they were fired
in series and produced a large voltage.
At about the same time Van de Graaff developed
moving belts that turned mechanical energy into
electrostatic energy.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
The original Cockcroft-Walton
installation
at
the
Cavendish
Laboratory in Cambridge. Walton is
sitting in the observation cubicle
(experimental area) immediately
below the acceleration tube.
The Cockcroft-Walton preaccelerator, built in the late 1960s,
at the National Accelerator
Laboratory in Batavia, Illinois.
Van de Graaff's very
large accelerator built
at MIT's Round Hill
Experiment Station in
the early 1930s.
Under normal operation, because
the electrodes were very smooth
and almost perfect spheres, Van
de Graaff generators did not
normally spark. However, the
installation at Round Hill was in
an open-air hanger, frequented by
pigeons, and here we see the
effect of pigeon droppings.
I.3 Tandems
It was soon appreciate that a negative ion (say H-) could
be accelerated by a positive electrostatic column,
stripped of its electron (to say H+) and accelerated again
so that one obtained twice the energy that previously had
been obtained. These “swindletrons”, so-named by Luis
Alvarez, later called tandems, are now in common use and,
generally, are commercially made.
A tandem
accelerator at
ORNL, built by the
National
Electrostatics
Corporation. The
high-voltage
generator, is
located inside a
100-ft-high, 33-ftdiameter pressure
vessel.
II. Cyclotrons
II.1
II.2
II.3
II.4
Lawrence and the Early Cyclotrons
Transverse Focusing and Phase Focusing
Calutrons
FFAG and Spiral Sector Cyclotrons
Major Nuclear Advances of the
1930s (My opinion)
1. Accelerator produced nuclear reactions, Cockcroft and
Walton, England, (1932), Nobel Prize 1951
2. Accelerator produced radioactivity, F. Joliot and Irene
Joliot-Curie, France, Nobel Prize 1935
3. Slow neutron reactions, Fermi, Italy, Nobel Prize 1938
4. Nuclear fission, Otto Hahn, (1939), Germany, Nobel
Prize 1944 (today Strassmann would be included; and a
separate prize given to Lise Meitner and Otto Frisch)
None of these advances were in Berkeley. Unfortunately, there
was too much focus on machine development. However, for
just that, Lawrence received the Nobel Prize in 1939 (today,
Stan Livingston would be included).
Celebrating our 75 th Anniversary
E.O.Lawrence in 1930
The First Cyclotron
Five inches in diameter.
The Original Rad Lab
Located on the Campus near Le Conte
Hall
.
II.1 Lawrence and the Early
Cyclotrons
As we all know, Lawrence invented and made a
succession of cyclotrons. Perhaps his greatest
contribution was, however, the creation of a
laboratory where physicists, engineers, biologist
worked together to achieve far more that any one
discipline could accomplish.
Cyclotrons are still built for nuclear physics and
medical purposes, but not for high-energy physics
reasons.
A picture of the 11-inch cyclotron built by Lawrence and
his graduate students, David Sloan and M. Stanley
Livingston, during 1931.
The 60 Inch Cyclotron
Donald Cooksey and E.O. Lawrence
The 60-inch cyclotron. The picture was taken in 1939.
II.2 Transverse Focusing and Phase
Focusing
The transverse focusing of particles was developed,
by Stan Livingston and was crucial in making the very
first cyclotron work. (He also realized how to remove
the accelerating field foils and thus increase cyclotron
intensity by orders of magnitude.)
Longitudinal, or phase focusing was developed in 1944,
independently by Ed McMillan and Vladimir Veksler.
The concept made the 184-inch work, and has been used
in essentially all accelerators since that time.
The magnet of the 184-inch cyclotron.
II.3 Calutrons
The concept of electromagnetic separation of the
isotopes of uranium, U238 and U235, only the later,
which is only 1/2% of natural uranium, being fissionable,
was developed by E.O.Lawrence. A first demonstration
was made on the not-yet-completed 184’’, and soon
Oak Ridge with 1000 calutrons was established.
Although all the material for the Hiroshima bomb was
electromagnetically separated, that method has not been
used since WWII and, as we all know, centrifuges are
now the method of choice.
The "C" shaped alpha
calutron tank. Here an
early version is shown.
II.4 FFAG
In the early 1950’s, just after the development of
strong focusing (described in the next section), it
was realized by the Midwestern Research Group
(MURA), that it was possible to have many configurations
of an accelerator, and some of these configurations were
advantageous for various purposes. In particular they
developed the concept of fixed field (fixed in time)
alternating gradient (FFAG) accelerators.
Spiral ridge cyclotrons have been extensively employed
for nuclear physics studies (88”) and, today, various other
applications of FFAG are being considered.
The “Mark 2”. A spiral sector FFAG built by the MURA
Group in Wisconsin from 1956 to 1959.
TRIUMF, the world's largest cyclotron at Canada's National
Laboratory for Particle and Nuclear Physics. (520 MeV). The
machine started in 1974 and is still in operation (now for rare isotope
acceleration).
III. Linear Accelerators
III.1 Proton and Heavy Ion Linacs
III.2 Induction Linacs
III.3 Electron Linacs
III.1Proton and Heavy Ion Linacs
Luis Alvarez was the first one to maker a linear
accelerator that only involved a single frequency.
In the 60’s radio frequency RFQs were invented in
the Soviet Union by V. A. Teplyakov, with actual
construction pioneered by a group at Los Alamos
An accelerating tank of the first, Alvarez, linac built
just after WWII.
The Materials Testing Accelerator (MTA), built, in the early 1950s,
at a site that would later become the Lawrence Livermore
Laboratory. The purpose of the machine was to produce nuclear
material, but it never produced any (due to uncontrollable sparking).
The inside of a Radio Frequency Quadrupole. The RFQ has
replaced the very large Cockroft-Waltons as injectors in to
synchrotrons.
III.2Induction Linacs
First invented, at Livermore, for magnetic confined
fusion. Used for the Electron Ring Accelerator at LBL.Then
used to study nuclear weapon implosions at LLNL and
LANL. And, also, the basis of LBL work on heavy ion
fusion (but that program has been terminated by the US
Government).
The world’s first induction accelerator, Astron, built at the
Lawrence Livermore Laboratory in the late 1950s and early 1960s
by Nick Christofilos.
The induction accelerator,
FXR, built, at Lawrence
Livermore, in order to study the
behavior of the implosion
process in nuclear weapons.The
facility was completed in 1982.
The Dual Axis Radiological Hydrodynamic Test Facility (DARHT)
at the Los Alamos National Laboratory, New Mexico. This device is
devoted to examining nuclear weapons from two axes rather than just
one. This reveals departures from cylindrical symmetry which is a
sign of aging which can seriously affect performance.
III.3 Electron Linacs
The high powered klysron was invented, during WWII, by
The Varian Brothers and Ed Ginzton. Using it, Bill Hansen
invented the electron linac. A succession of machines at
Stanford culminated in the two-mile accelerator, SLAC,
led by WKH Panofsky. That machine made many important
high-energy physics discoveries and then became the
injector for PEP and PEP II, and now has become the
LCLS.
The SLAC site.
IV. Betatrons
Very few betatrons are built these days, but at the time,
around the 1940’s, they were very important for they
provided the only way to accelerate electrons to higher
energies than could be obtained with electrostatic machines.
Many physicists had tried to make circular electrons
accelerators, but they all failed until Don Kerst was
able to make a betatron by careful attention to the details
of particle orbit dynamics. One of his early machines
was used at Los Alamos during WWII.
One of the first betatrons, built in the early 1940s. The
so-called 20 inch machine at the University of Illinois.
A picture of the 100 MeV betatron (completed in the early
1940s) at the G.E. Research Laboratory in Schenectady
after Kerst had returned to the University of Illinois.
A modern, very compact betatron, commercially
produced. It is used to produce x-rays to look for defects in
large forgings, steel beams, ship’s hulls, pressure vessels,
engine blocks, bridges, etc.
V. Synchrotrons
V.1 First Synchrotrons
V.2 Strong Focusing
Made possible by the synchrotron (RF) concept,
the concept of strong focusing, and the concept of
cascading synchrotrons. First proposed, even prior to
the invention of strong focusing, by the Australian,
Macus Oliphant. They were first built after WWII
and all modern accelerators are based upon the
synchrotron principle.
V.1 First Synchrotrons
Late in World War II the Woolwich Arsenal Research Laboratory
in the UK had bought a betatron to "X-ray" unexploded bombs in
the streets of London. Frank Goward converted the betatron into
the first “proof of principal” synchrotron.
This 300 MeV electron synchroton at the General Electric Co.
at Schenectady, built in the late 1940s. The photograph shows a
beam of synchrotron radiation emerging.
Although the first Proton Synchrotron to be planned, this 1 GeV
machine at Birmingham University, achieved its design goal only in
1953.
The 3 GeV Cosmotron was the first proton synchrotron
to be brought into operation.
Overview of the Berkeley Bevatron during its
construction in the early 1950s. One can just see the man
on the left.
V.2 Strong Focusing
The invention of strong focusing, in the
early 1950’s, by Ernie Courant, Hartland
Snyder and Stan Livingston, revolutionized
accelerator design in that it allowed small
apertures (unlike the Bevatron whose aperture was
large enough to contain a jeep, with its windshield
down).
The concept was independently discovered by
Nick Christofilos.
The CERN site in April 1957 during construction of the 26
GeV Proton-Synchrotron (PS).
An artists impression of the AGS before its construction
in the 1950s.
Fermilab’s superconducting Tevatron can just be seen
below the red and blue room temperature magnets of the
400 GeV main ring.
VI.Colliders
VI.1 Early Colliders
VI.2 Proton – Antiproton Colliders
VI.3 The Large Hadron Collider (LHC)
and the Heavy-Ion Collider (RHIC)
VI.1 Early Colliders
In the 1950’s a number of places, MURA,
Novosibirsk, CERN, Stanford, Frascati, and
Orsay, developed the technology of colliding
beams. Bruno Touschek, Gersh Budker and
Don Kerst were the people who made this
happen.
Colliders are now the devices employed to
reach the highest energies.
The electron-electron storage rings (early 1960s), at the
High Energy Physics Laboratory (HEPL) on the
Stanford Campus.
The first electronpositron storage ring,
AdA. (About 1960)
Built and operated at
Frascati, Italy and later
moved to take
advantage of a more
powerful source of
positrons in France.
ADONE, the first of the large electron-positron storage
rings. Operation commenced in 1969.
Superconducting RF cavities at the CERN Large Electron
Positron Collider (LEP).
The CERN Electron
Storage and
Accumulation Ring
(CESAR) was built, in
the 1960’s, as a studymodel for the ISR
(Intersecting Storage
Rings).
The first proton-proton
collider, the CERN
Intersecting Storage Rings
(ISR), during the 1970’s.
One can see the massive
rings and one of the
intersection points.
VI.2 Proton – Antiproton Colliders
It was the invention of stochastic cooling, by
van de Meer, that made proton-anti-proton
colliders possible
In 1977 the magnets of the “g-2” experiment were modified
and used to build the proton-antiproton storage ring: ICE
(the Initial Cooling Experiment). The ring verified the
stochastic cooling method, and allowed CERN to discover
the W and Z.
The anti-proton source, the “p-bar” source, built in the
1990’s at Fermilab. The reduction in phase space density,
the proper measure of the effectiveness of the cooling, is
by more than a factor of 1011.
VI.3 The Large Hadron Collider (LHC)
and the Heavy-Ion Collider (RHIC)
The LHC, at CERN, is soon to be completed.
It is the primary tool to which high-energy physicists
are looking. The hope is to discover the
Higgs particle. The machine is 28 km
in circumference.
RHICis in operation at Brookhaven, a
development of studies started in Berkeley,
on the Bevalac, in the late1970’s.
Nuclear matter under extreme conditions of very high
density and very high temperature similar to the
conditions in the original Big Bang. A collision of a
nucleus of gold with a nucleus of gold. The temperature
rises to 2 trillion degrees Kelvin and as many as 10,000
particles are born in the resulting fireball.
VII. Synchrotron Radiation
Sources
VII.1 Synchrotron X-RaySources
VII.2 Linear Coherent Light Source and
the European Union X-Ray Free
Electron Laser
VII.1 Synchrotron X-Ray Sources
At first (about 1970’s), accelerators built for
high-energy physics were used parasitically,
but soon machines were specially built for this
important application. There are more than 50
synchrotron radiation facilities in the world.
In the US there are machines in Brookhaven
(NSLS), Argonne (APS), SLAC: SPEAR and
the LCLS, and at LBL (ALS).
This intricate structure of a complex protein molecule
structure has been determined by reconstructing scattered
synchrotron radiation.
An aerial picture of the European Synchrotron
Radiation Facility (ESRF) located in Grenoble,
France. Construction was initiated in 1988 and the
doors were open for users in 1994.
Aerial view of Spring 8, a synchrotron light source
located in Japan. Construction was initiated in 1991 and
“first light” was seen in 1997.
The King of Jordan
discussing with
scientists the Sesame
Project, which will be
located in Jordan and
available to all
scientists.
VII.2 Linear Coherent Light Source
and the European Union
X-Ray Free Electron Laser
FELs, invented in the late 1970’s at Stanford are now
becoming the basis of major facilities in the USA (SLAC)
and Europe (DESY).They promise intense coherent
Radiation. The present projects expect to reach radiation of
1 Angstrom (0.1 nano-meters, 10killo-volt radiation)
The DESY Free Electron Laser magnetic wiggler. It produces
laser light in the ultra-violet and x-ray regions of the spectrum.
The SLAC site showing its two-mile long linear
accelerator, the two arms of the SLC linear collider, and
the large ring of PEPII. This is where the LCLS will be
located.
A schematic of a possible fourth generation light
source. This is the proposed facility LUX, as envisioned
by a team at LBL, but upon which we were told (strongly)
to stop work.
VIII. Cancer Therapy Machines
First treatment by the Lawrence's of their mother.
Stone in the late 30’ and neutrons. (Sad story)
Linacs for x-rays built by Siemans and Varian in the US
Hadron therapy (Bragg peak) suggested by
Bob Wilson in 1946. Pioneered in Berkeley and Harvard.
Now 5 facilities in US; many more to come.
Heavy ions carefully developed at the Bevalac in the
70’s. From basic biology to patient treatment.
First dedicated facility in Japan. None in US, but more
being built in Japan and some in Europe.
Most patients, however, are treated by by X-rays
A modern system for treating a patient with x-rays produced by a
high energy electron beam. The system, built by Varian, shows the
very precise controls for positioning of a patient. The whole device
is mounted on a gantry. As the gantry is rotated, so is the accelerator
and the resulting x-rays, so that the radiation can be delivered to the
tumor from all directions.
A drawing showing the Japanese (two) proton ion synchrotron,
HIMAC. The pulse of ions is synchronized with the respiration of
the patient so as to minimize the effect of organ movement.
IX.The Future
1 The International Linear Collider (ILC)
2 Spallation Neutron Source
3 Rare Isotope Accelerator and FAIR
4 Neutrino Super Beams, Neutrino Factories
and Muon Colliders
5 Accelerators for Heavy Ion Fusion
6 Proton Drivers for Power Reactors
7 Lasers and Plasmas
1. The International Linear Collider
(ILC)
The next high-energy physics facility. Cost estimate
is due at the end of the year (clearly in the
few billion dollar range).World-wide effort. A major
report has strongly requested that the USA bid for
location in the USA. (With LEP, HERA, the
KEK B-Factory, and LHC the past couple of decades
have been tough. If the ILC is not located in the USA
there won’t be any HEP facility in our country as
both the Tevatron and PEPII are scheduled to be
terminated in this decade.
The X-Band Test Accelerator at SLAC. Here one of the approaches
to an International Linear Collider was tested by actually building a
section of a collider. It is not the approach of choice.
The damping ring built at KEK, Japan, in order to study the
process of making a beam of very tiny dimensions as would be
needed for the International Linear Collider.
TESLA technology: these
superconducting accelerator
structures are built of
niobium, and are the crucial
components of the
International Linear
Collider.
2. Spallation Neutron Sources
A joint effort of LBL, BNL, LANL, J-Lab and Oak Ridge.
Located at Oak Ridge. A similar facility is under
construction in Japan, with advanced plans in China and
plans (for a long time) in Europe.
An overview of the Spallation Neutron Source (SNS) site at
Oak Ridge National Laboratory showing the various
components of the facility.
A diagram showing the CERN approach to a linear collider. The
two main linacs are driven by 30 GHz radio frequency power
derived from a drive beam of low energy but high intensity that
will be prepared in a series of rings.
A three dimensional -- blown apart -- drawing showing
how a Time Projection Chamber (TPC) works.
A picture of the UA2 detector at CERN. One can easily imagine
that the detectors about a modern storage ring are as complicated,
and about as expensive as the accelerator itself.
An “exploded” diagram of the ATLAS detector,
presently under constrtuction, for the LHC.
3. Rare Isotope Accelerator and
FAIR
Thinking and plans in the US (Argonne and
Michigan State), but they have been told to stop,
but I think it is getting reversed.
(First priority in nuclear physics)
Meanwhile, Germany has started FAIR.
The Rare Isotope Accelerator (RIA) scheme. The heart of the
facility is composed of a driver accelerator capable of accelerating
every element of the periodic table up to at least 400 MeV/nucleon.
Rare isotopes will be produced in a number of dedicated production
targets and will be used at rest for experiments, or they can be
accelerated to energies below or near the Coulomb barrier.
4. Neutrino Super Beams, Neutrino
Factories, and Muon Colliders
Solar Neutrino Problem
Super K
K toK
Gran Saso
Minos and NUMI
Super Beams
Neutrino Factories
Muon Colliders
Here we show the very
large underground detector,
Kamiokande, located in the
mountains of Japan. Many
very important results have
come from this facility that
first took data in 1996. The
facility was instrumental in
solving “the solar neutrino
problem. After a serious
accident the facility was
fully restored in 2005 and
this year the SuperKamiokande, SK-III will
be completed.
A diagram of the muon cooling experiment MICE being carried out
at the Rutherford-Appleton Laboratories in England.
5. Accelerators for Heavy Ion Fusion
Started in 1974
Two programs:
Europe: Use of RF linac and accumulating rings.
USA: Use an induction linac.
Both approaches should work. Both have been stopped for
lack of government support. The USA program was
terminated a year of so ago, as we clearly don’t need to do
R&D on new energy sources.
An artist’s view of a heavy ion inertial fusion facility. Although the
facility is large, it is made of components that all appear to be
feasible to construct and operate.
6. Proton Drivers for Power Reactors
The idea is to have a sub-critical nuclear power reactor
(hence very safe) and drive the reactor into criticality with
neutrons produced by protons as in a spallation source. Also,
there is the possibility of both burning thorium and burning
up long-lived fission products.
Actively being studied in Japan, Russia, Europe, and in the
USA there has been some small activity. Now, perhaps, with
The Global Nuclear Energy Partnership, there will be more.
A linac scheme for driving a reactor. These devices can turn
thorium into a reactor fuel, power a reactor safely, and burn up
long-lived fission products.
7. Lasers and Plasmas
The idea of using a plasma as an accelerating
media was proposed in 1979 by John Dawson
and Toji Tajima. Since, then, there has been a
great deal of activity, with UCLA, LBL,
Rutherford-Appleton, and others, being places
of great activity. High gradient, and major
acceleration, has been achieved.
The SLAC End Station which was used to study the very fine final
focus required for the International Linear Collider. It is in this area,
and using the very intense beam developed for the earlier study, that
the experiments on wake-field acceleration were carried out.
X. Concluding Remarks
Accelerator Milestones
Cockcroft-Waltons (England)
Van de Graaffs (MIT)
Cyclotrons (Berkeley)
Betatrons (Illinois)
Synchrotrons (Soviet Union and Berkeley)
Strong Focusing (Brookhaven)
FFAG (Mid-West)
Proton Linacs (Berkeley)
Electron Linacs (Stanford)
Heavy Ion Accelerators (Berkeley)
Induction Linacs (Livermore, Berkeley)
Space Charge Effects (Many places, but also Berkeley)
Cooling: Stochastic and Electron (CERN and
Soviet Union)
X. Concluding Remarks
Accelerator Milestones (Cont)
Colliding Beams of Protons (Mid-West)
Colliding Beams of Electrons (Stanford, Italy, Soviet Union)
Colliding Beams of Protons and Anti-Protons (CERN)
RFQs (Soviet Union and Los Alamos)
FELs (Stanford)
Photo-cathodes (Los Alamos)
Medical Applications (Berkeley)
SC Magnets (Fermilab, Brookhaven, CERN, Berkeley)
SC RF (Stanford, Cornell, CERN, J-Lab, KEK)
Light Sources and Insertion Devices (Stanford, Berkeley)
X. Conclusion
I have sketched for you some of the likely future
projects of accelerator physics future. Perhaps, the
development of accelerators was a passing moment in the
history of mankind, but it is much more likely to be an
activity that will continue, producing devices not only for
physics, but for an ever increasing catalogue applications
enriching our everyday lives.
Thank you for your attention.