Melvyn Bragg and guests discuss the neutron, one of the particles found in an atom's nucleus. Building on the work of Ernest Rutherford, the British physicist James Chadwick won the Nobel Prize for Physics for his discovery of the neutron in 1932. Neutrons play a fundamental role in the universe and their discovery was at the heart of developments in nuclear physics in the first half of the 20th century. With Val Gibson Professor of High Energy Physics at the University of Cambridge and fellow of Trinity CollegeAndrew Harrison Chief Executive Officer of Diamond Light Source and Professor in Chemistry at the University of EdinburghAndFrank Close Professor Emeritus of Physics at the University of Oxford.