In memoriam.

One of Canada's pioneers in the nuclear field died in hospital in Ottawa on July 9, 2007 at the age of 82. Bob Brown, personally modest and unassuming, was very well known internationally for his contributions to the outstanding research conducted at the Chalk River Laboratories over the latter half of the 20th century. Born in Richmond, QC, he received his post-secondary education at Bishop's and McGill, earning a PhD in polymerization kinetics.

Bob joined the NRC staff at the Chalk River Laboratories very early in 1951, and was seconded to work with a small group headed by W. E Grummitt, FCIC, measuring atmospheric fallout from nuclear weapons testing (American, Russian, and eventually Chinese).

Following the American thermonuclear tests, Bob rapidly became a world leader in the separation, purification, and measurement of atmospheric tritium. This isotope of hydrogen proved to be an invaluable tool in all aspects of hydrology, and Bob was at the forefront of these developments. His graph of tritium in Ottawa rain, year by year, from 1951 onwards for several decades, has been reprinted in numerous papers and books. From 1970 to 1973, he was seconded to the International Atomic Energy Agency in Vienna, heading up the hydrology unit there. On his return to Canada, Bob became a specialist in environmental isotopes with a particular focus on 3H and 14C in air, water, flora, and fauna. Bob had a leading role in the 1986 and 1987 field experiments at Chalk River in which he studied the short-range environmental dispersion and oxidation of a release of tritiated hydrogen to the atmosphere.

In the latter half of the 1980s, Bob began collaborations aimed at applying the capabilities of the TASCC facility to the new technique of accelerator mass spectrometry, starting with the measurement of [sup.14]C in meteorites, and continuing with the development of techniques for measuring [sup.36]Cl.

His lifelong enjoyment of skiing, both downhill and cross-country, continued well into retirement. He served for many years on the Deep River Library Board, and most recently had been handling the position of treasurer for the Deep River and District Community Foundation. He will be much missed.