Andrew Holmes-Siedle



Dr. Andrew Gordon Holmes-Siedle was born in 1929, in Hove, Sussex, England, to a pair of dentists: Bertram Adolphe and Rosa Edwards (Harse) Holmes-Siedle. He spent most of his career as an applied physicist who worked in the field of radiation detection through solid-state devices.

After graduating from Xaverian College in Brighton and serving in the Royal Air Force after World War II, Holmes-Siedle received a B.A. from Trinity College, Dublin, in 1954. He pursued a scholarly career in organic chemistry at Cambridge University, receiving the Ph.D. in 1958. In the middle of the program, Holmes-Siedle married Monica Taylor, who was studying for her M.D. in pediatrics, in 1956. He conducted postdoctoral chemical research at the university’s Chemical Laboratories from 1958 to 1960, studying the transfer of energy in biological and chemical systems. This work culminated in his co-authored publication of the first comprehensive study of the haem peroxidase enzyme and its related catalysts, Peroxidase: the Properties and Uses of a Versatile Enzyme and of some Related Catalysts (London: Butterworth, 1964).

By then, however, Holmes-Siedle had departed academe for industry, and organic chemistry for applied physics. In 1960 he joined the Advanced Projects Group of Hawker-Siddeley Aviation at Kingston-upon-Thames as a project engineer making preliminary design studies of communication satellite systems and lunar vehicles. In these system studies he specialized in the effects of environment on components and humans, the simulation of the space environment, and telemetering of scientific data, specifically the effects of solar and nuclear test radiation on communication satellites. This became the field in which Holmes-Siedle spent the rest of his career as an industry and academic research physicist, entrepreneur, and educator of co-workers, colleagues, customers, and students.

In 1962, RCA made him and three colleagues "the job offer of a lifetime" to join the Physical Research Group of its Astro-Electronics Division in East Windsor, New Jersey, USA. Settling with his family of five on Carter Road in nearby Princeton, Holmes-Siedle researched radiation damage to and the scientific instrumentation of satellites. This involved experimental research on radiation effects in materials; analysis of the space radiation environment and its effect on human systems; irradiation of satellite components and systems designed for National Aeronautics and Space Administration (NASA) satellite projects; definition of radiation effects criteria for RCA spacecraft; and engineering studies and research on space radiation detectors. By 1967, Dr. Holmes-Siedle was appointed coordinator of Astro's Radiation Physics group and the division's representative for this information across the corporation.

RCA had initially hired him to reduce radiation effects on silicon solar cells for the Relay communications satellites, but Holmes-Siedle was soon developing testing programs for components designed to survive harsh radiation environments and operate for long periods. He spent considerable time handling the consequences of the Starfish Prime atmospheric nuclear test in July 1962 that created a new radiation belt of high-energy sub-atomic particles around the Earth. This ruined at least six orbiting satellites, including AT&T's Telstar, and posed a new challenge for making durable satellites. Holmes-Siedle's team's success with shielding Relay I in 1963 led to a NASA contract with RCA to study radiation effects on the company's new Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). When MOSFETs were integrated in complementary circuits (CMOS), they operated at very low power, an obvious advantage in space. When dosed with ionizing radiation, moreover, their insulating oxide layer stored an electric charge relative to the amount of radiation. With a radiation-sensitive MOSFET, the RADFET, Holmes-Siedle had the basis for a small integrating radiation dosimeter subject to the declining cost curve of Gordon Moore's law.

Despite the prospects for many applications in space and on Earth that Holmes-Siedle foresaw, RCA's Solid-State Division had other priorities. However, Holmes-Siedle had been a visiting scientist with Princeton University's Aerospace Engineering Department, won a NASA award and an IR-100 award, and become a regular presenter at the National Space Radiation Effects Conference (NSREC). This proved "to be a great network, a source of information and, as it still is, a friendly multinational club." He and his family returned to England in 1972 when the University of Reading's Strategic Research Centre offered him a fellowship where he could pursue his interest in improving RADFET dosimetry for people as well as equipment. There he published in 1974 his conception of a MOSFET-based space-charge dosimeter that promised significant improvements in radiation sensitivity, and which was first used in the Explorer 55 satellite in 1975. Other spacecraft followed. Starting that year, Holmes-Siedle began consulting for the Institute of Physics' Fulmer Research Institute (later Laboratories) on industrial sensors and radiation effects testing for the European Space Agency (ESA), the United Kingdom's Atomic Energy Authority and the U.K. Ministry of Defence. This activity overlapped with his entrepreneurship in founding the family-owned REM Instruments in Oxford (later REM Oxford) in 1980. REM was an acronym for "Radiation Experiments and Monitors" despite occasional assertions that it stood for "Rapid Eye Movement." More tangibly, Holmes-Siedle formed it to fit RADFET dosimeters with the appropriate packaging, wiring, and controller or reader for applications ranging from spacecraft to oncological research.

As the Fulmer was broken up in the early 1990s, Holmes-Siedle further diversified his activities. In 1991 he applied for what became U. S. Patent 5,319,193, a "light activated transducer," in 1994. Together with Leonard "Len" Adams of the ESA, he synthesized a series of reports they had written for the Handbook of Radiation Effects, published in 1993 and revised in a second edition nine years later. Brunel University's Physics Department became his institutional base, where he started the Centre for Radiation Damage Studies as an honorary professor and advisor on doctoral students' dissertations. He focused research on testing detectors' utility in astronomy, space instrumentation, and high energy physics facilities, working with the Conseil Européen pour la Recherche Nucléaire (CERN) and other organizations in Europe and North America seeking insight on the issues of radiation measurement. Through REM Oxford, he also worked with Harvard University Medical School and the Istituto Nazionale per la Ricerca sul Cancro, the National Institute for Cancer Research in Genoa, Italy. In 2020 RADFET dosimeters are standard equipment in monitoring radiotherapies for cancer patients.

Dr. Holmes-Siedle published over sixty articles along with his two books, attracting nearly 2,500 citations by May 2020. He was a Fellow of the Institute of Physics and the British Interplanetary Society; a senior member of IEEE and a member of the Radiation Effects Committee of the IEEE Nuclear and Plasma Sciences Society from its establishment in 1964, receiving its Radiation Effects Award in 2001. Outside of his professional commitments, Holmes-Siedle maintained an interest in the piano, cricket, and history, starting with his family's.

Further Reading

[Siedle Saga: Andrew Holmes Siedle]

[Chapters of the TIROS-DMSP Tale; see his excerpted email recollections in Chapters 4 and 7]

[RCA Engineer articles (4) by Holmes-Siedle, A. G.]