The Beginning of Nuclear Science

Poised on the threshold of a new century, scientists in the late 1800’s made discoveries which would change the course of science, history and medicine in the 20th Century.

Henri Becquerel

Marie and Pierre Curie

What is an accelerator?What is an accelerator?

If a charged particle goes through an electricfield it gets accelerated. The amount of accelerationdepends on the strength of the electric field.

A simple vacuum tube accelerator

Scientists/engineers tried to put more and more voltage across a gap to make an electron field to accelerate a particle to 1 million electron volts (MeV). When they couldn’t get any higher, they tried to put a bunch of gapstogether, so that the particle would get successively accelerated.

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.

The Cockcroft-Walton pre-accelerator, 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-) couldbe 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 hadbeen 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-ft-diameter pressure vessel.

Ernest Orlando Lawrence

Ernest Orlando Lawrence invented the first cyclotron in 1929-31 in a small laboratory on the Berkeley campus. This was the foundation of the “Radiation Laboratory”.

Lawrence at the controls of the 27”Cyclotron, about 1938.

Lawrence’s first cyclotron, a few inches in diameter

Lawrence’s breakthrough

Lawrence took the idea of successive accelerations from Wideroe and suggested “rolling up” the linear accelerator into a circle.

Lawrence’s 11” cyclotron reached the sought-after goal of 1 MeV acceleration.

How a cyclotron works

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.

The magnet of the 184-inch cyclotron.

The 88-Inch Cyclotron Facility

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).

Lawrence only thought he invented the cyclotron

From a stone in a 200 BC Greek“hospital” in Asia Minor (modernTurkey)

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.

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.

The 3 GeV Cosmotron was the first proton synchrotron to be brought into operation.

The CERN site in April 1957 during construction of the 26 GeV Proton-Synchrotron (PS).

Fermilab’s superconducting Tevatron can just be seen below the red and blue room temperature magnets of the 400 GeV main ring.

The first electron-positron 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.

Superconducting RF cavities at the CERN Large Electron Positron Collider (LEP).

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.

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.

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 thisimportant application. There are more than 50synchrotron 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.

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 USHadron 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 morebeing 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.

Proton Therapy Facility at MDA

Why Protons?

Gammasphere - the world’s most powerfuldetector array to measure gamma rays

A beam particle hitsa target nucleus insideGammasphere

The two nuclei fuse to make a hot “compoundnucleus” which can beelongated and rotating

The compound nucleuscools down by emittingneutrons and protons

The rotating nucleusemits gamma rays whichare detected in Gammasphere