Abstract
ABSTRACTHessel de Vries contributed to radiocarbon (14C) dating for only one short decade. Yet, his development of proportional CO2 counting greatly facilitated 14C measurements, improved their reproducibility, and lowered both the amount of carbon needed for a measurement and the 14C detection limit by at least a factor ten. Validating Libby’s 14C method by checking its basic assumptions with improved sensitivity, de Vries documented relatively minor violations. Natural variations in atmospheric 14C concentrations, found in tree rings, marked the start of 14C tree-ring calibration. Variable differences in 14C concentration between the atmosphere and aquatic reservoirs revealed reservoir ages, leading to further studies. De Vries applied analogue modeling to gain a better understanding of the influence of cosmogenic 14C production and the global carbon cycle, inclusive CO2 exchange across the air-water boundary, on atmospheric 14C concentrations. In close collaboration with colleagues in archaeology and geology, de Vries documented climate fluctuations and archaeological developments over the last 50,000+ years and placed them on a common 14C time scale.
Highlights
Hessel de Vries, born in 1916, was the son of a schoolteacher
Van Giffen sought a second opinion and contacted in 1950 his colleague, physicist Hessel de Vries who had worked with proportional counters
De Vries was immersed in biophysical research, van Giffen persuaded him to develop radiocarbon dating in Groningen
Summary
Hessel de Vries, born in 1916, was the son of a schoolteacher. He started studying physics at the University of Groningen, the Netherlands, in 1934 and obtained his PhD (cum laude) in 1942. His thesis was in the field of neutron physics, titled “De Resonantieniveaux van Zilver, Zink, Koper en Aluminium voor het Invangen van Neutronen” (“The Resonance Levels of Silver, Zinc, Copper, and Aluminum for Neutron Capture”) He continued at the University of Groningen as a lecturer and, later, in 1954 as full professor in biophysics. As is clear in his 1943 paper “The Quantum Character of Light and its Bearing upon Threshold of Vision, the Differential Sensitivity and Visual Acuity of the Eye,” de Vries (1943) sought to understand the basic physics governing the world around and in us He hypothesized that the thermal motion of molecules in the eye may supply the extra energy needed by small light quanta to pass the energy threshold for registration.
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