Thank you for downloading this episode of In Our Time for more details about In Our Time

and for our terms of use, please go to bbc.co.uk slash radio4.

I hope you enjoy the program.

Hello. In 1932 in the Cambridge Laboratory, James Chadwick discovered the neutron, one of

the building blocks of the atomic nucleus. It was a crucial stage in the development of

nuclear physics. Scientists quickly saw that neutrons were ideal for firing into an atom's

nucleus. That made the nucleus disintegrate and released huge amounts of energy. The

popular term was splitting the atom and it captured the public imagination. All the more

so when in the following decade it led to the atomic bomb. In the last 70 years, further

study of the neutron has shown its applications in medicine, industry, energy and technology.

A deeper understanding of the neutrons reveals fascinating details of the origins of life,

of all matter and of the universe. With me to discuss the neutron are Val Gibson, Professor

of High Energy Physics at the University of Cambridge and Fellow of Trinity College, Andrew

Harrison, Chief Executive Officer of Diamond Light Source and Professor In Chemistry at

the University of Edinburgh and Frank Close, Professor Emeritus of Physics at the University

of Oxford. To start with you Frank Close, what is a neutron?

The neutron is one of the two basic constituents of the atomic nucleus. Along with the proton,

the proton is positively charged and its electrical charge provides the electrical forces that

hold atoms together and ultimately enables chemistry and biology to happen. The neutron

is electrically neutral hence its name. So it doesn't affect chemistry but in the nucleus

it's an essential component. It gives the nucleus its structure and to have a sound

bite it's the spark that lights the nuclear fire in that by using neutrons you can liberate

...