At the start of the 20th century, Ernest Rutherford laid the foundations of nuclear physics. He discovered radioactive half-life, came up with his atomic model and also proved that radioactivity involved the transmutation of one element to another. Rutherford, in a way, had clearly indicated that the atomic nucleus was the next big thing for the experimental physicist.
If elaborate circuits with innumerable components were the biggest challenge in the 1950s, developing means to accelerate charged particles to high velocities was the most formidable task that confronted scientists in the 1920s.
So when Ernest Orlando Lawrence got his PhD in Physics, he was naturally drawn towards this problem of bombarding the atom’s nucleus.
After securing a faculty position with the University of California in 1928, Lawrence was able to dedicate much of his time to the question of obtaining energy in the range of millions of electron volts in the laboratory.
He was soon able to figure out that his problem was two-pronged, namely, producing the high voltages and developing accelerating tubes capable of handling these voltages.
In 1929, Lawrence stumbled upon an article by Rolf Wideroe in a German electrical engineering journal. Using Professor G. Ising’s idea, Wideroe described multiple acceleration of positive ions in a linear accelerator using alternating electric fields.
Not being fluent in German, Lawrence studied the diagrams and realised that the accelerators would have to be impractically long if they were to produce his desired energy levels.
But knowing that a magnetic field would deflect charged particles into a curved path and that he could boost their energy in steps as the particles spiralled an electrode, Lawrence designed a cyclotron that would solve their problem.
This circular machine, which would fit into a room, would allow particles to spiral around, gaining energy and speed, before shooting out of the device on to a collector with tremendous force.
Even though the cyclotron was theoretically ready, the first model — only four inches in diameter — was made only in 1930. Cyclotrons got successively larger and the million electron volt barrier was breached as early as 1931.
The next milestone was the 60-inch cyclotron that came into existence on this day in 1939. This cyclotron was not only used to create seven elements unknown in nature, but was also put to therapeutic use.
Lawrence found that the cyclotron particle beam could be used to treat cancer and along with his brother John, a physician, successfully treated their mother for cancer using a neutron beam.
Lawrence’s cyclotron had far reaching implications for science and the way in which it is done. It not only launched the modern-era of high-energy physics, but also paved the way for Big Science — organised scientific work that depended on large-scale projects that had to be funded by corporations, governments or even groups of national governments.
