The fissile material was Plutonium. It was in the shape of 2 hemispheres with a central core of Berillium and Polonium - the initiator. The initiator's job was to produce some neutrons to start the nuclear chain reaction in the surrounding sphere of Pu. The Pu is sub critical as assembled, but the high explosive lenses surrounding it are used to squash it into a critical sphere along with getting the initiator to work. Surrounding the Pu core is a thick layer of unrefined Uranium. This is very high density material - a forerunner of depleted Uranium? Natural Uranium has about 0.7% of the fissile isotope. Depleted uranium has less. It is a very dense material - about 70% more dense than lead. Used in weapons, radioactive material transport. Outside the unrefined uranium is an aluminium shell called the tamper. It along with the Uranium shell are there to prevent a large drop of pressure behind the explosive lenses. I think this is to make the action of the explosion on the core more predictable.

The explosive lenses are in the shape of a football - a truncated icosahedron.

The first live test was called Trinity. It took place at the Almogordo test range about 200 miles away from Los Alomos. The area was flat and so could be viewed from a great distance. The trigger was pulled from 10,000 yards away. Viewers - scientists and others - were positioned about 20 miles away.

The blast fused the sand in the area into glass called Trinitite. This was worn as jewelery soon after and could cause skin burns.

The thermonuclear bomb was called the Super. A patent for this was first produced by Von Neumann and Fuchs. Fuchs was a Soviet spy and gave all the secrets to the Russians. This inspired them to start their own full scale thermonuclear weapons programme.

Teller designed the first successful thermonuclear bomb.

The Russians Detonated the Tsar Bomba in the Siberian Arctic. The TNT equivalent of this bomb has a volume of a cube of dynamite with a 310 metre side.