PHYSICS

Cryogenics - the subject of many films: SRDE developed several techniques from the topical and fascinating subject of cryogenics in their research programme in Maser amplifiers.

SRDE also researched the technology that has been developed for use in MRI (Magnetic Resonance Imaging) machines, used in today's hospitals to see inside the human body.

In the early 1950's the possibility of detecting non-magnetic mines by using the nuclear magnetic resonance of protons was researched. Various types of coils to produce a strong steady magnetic field and a weaker probing radio frequency wave were tried for "magnetic resonance imaging".the buried mine. Another aspect of detecting buried objects was the use of the free procession of protons in a water sample to detect any anomaly in the value of the earth’s magnetic field.

A programme of work in the new field of Quantum Electronics, brought about by the discovery of the Maser (Microwave Amplification by Stimulated Emission of Radiation) by scientists in the U.S. was undertaken. Part of this work was to produce maser action at the microwave frequencies used in communications and this required an understanding of the Quantum Physics of Paramagnetic Crystals, a field of study which had been extensively researched by scientists at the Clarendon Laboratory, Oxford University. The Three-Level Maser was used for amplifying weak signals in satellite communication links. The Two-Level Maser with a swept magnetic field provided low noise amplification of pulsed microwave radiation at millimetre wavelengths.

The Ammonia Maser obtained from the excited states of the ammonia molecule was developed as an ‘Atomic Clock’ and subsequently installed in Australia.

The Basic Physics Division was also concerned with the generation of optical radiation by Laser Action in Ruby crystals and Neodymium doped glass rods. A novel method of detecting infra-red was devised using Quantum Counter action in rare-earth crystals. The division also had a Cryogenic facility with a Collins helium liquifier and a liquid nitrogen machine.

Projects in the Work Programme included: