George Samuel Hurst

George Samuel Hurst (October 13, 1927 – July 4, 2010) was a health physicist, scientist, inventor, educator and innovator. He developed the omnipresent touchscreen technology and single atom theory. Hurst spent his career at Oak Ridge National Laboratory where he was involved with: neutron survey meters; alpha survey meters; ionizing radiation dosimetry; gas ionization studies; Nevada Test Site gamma and neutron radiation measurements; vacuum ultraviolet (VUV) radiation and the Jesse effect; time-of-flight investigations; electron swarm measurements; study of atomic bomb survivors from Hiroshima and Nagasaki; radiation accident investigations; radiation dosimetry projects for NASA; microdosimetry; one-atom detection and single atom detection; solar neutrino experiments; magnetic monopole detectors; resonance ionization spectroscopy (RIS); and, sputter-initiated resonance ionization spectroscopy (SIRIS).

Hurst was born on October 13, 1927 in the rural town of Ponza, Bell County, Kentucky located near Pineville, Kentucky. His father was James H. Hurst and mother was Myrtle Wright Hurst. As a boy, he had a keen interest in Thomas Edison. Hurst grew up on the family farm and came from a large family with two brothers and two sisters. In 2010, he died of a brain aneurism and was buried at Oak Ridge Memorial Park.

Hurst attended high school at Bell County High School in Pineville, Kentucky. At the age of 15, he enrolled in Berea College. In 1947, Hurst received a B.A. degree in physics and a minor in mathematics from Berea College. He attended the University of Kentucky and graduated in 1948 with the M.S. degree in physics. During registration at UK, he met Rufus Ritchie. Ritchie became a longtime friend and the two worked on several projects together. After graduation, they both went to ORNL. In 1959, Hurst was awarded a Ph.D. in physics from the University of Tennessee.

In 1948, Hurst was recruited by Karl Z. Morgan and landed a research position at Oak Ridge National Laboratory (ORNL) in the Health Physics Division. His starting salary was $325 per month. He made significant contributions in the development of radiation detectors and instrumentation, neutron dosimetry and spectroscopy, and field sample analysis. While working at Oak Ridge, he earned a PhD in physics from the University of Tennessee in 1959. In 1966, Hurst accepted a position at the University of Kentucky as Professor of Physics.

From 1948 to 1950, Hurst worked with Ritchie to develop a fast neutron survey meter and fast neutron dosimetry. The fast neutron dosimetry work continued throughout the 1950s with the added interest in tissue dose. In 1952, the team of Hurst, D.J. Knowles and C. Yochem worked to develop a thermal neutron survey instrument. Hurst and F.M. Glass developed a method of pulse integration by utilizing the binary scaling unit. Hurst explored fast neutron dosimetry and tissue-equivalent phantoms. His team that included J.A. Harter, P.N. Hensley and W.A. Mills studied neutron flux and tissue dose with fission threshold detectors. Around 1955, Hurst teamed with A.C. Upton, F.P. Conte and W.A. Mills to look at the relative biological effectiveness (RBE) that involved mixed radiation fields for acute lethality in various animal models. Additional studies with A.C. Upton, K.W. Christenberry, G.S. Melville, and J. Furth utilized mixed radiation fields to produce lens opacity in various animal models. In 1956 and again in 1980, Hurst utilized threshold detectors to measure neutron spectra in order to determine tissue dose. In 1961, Hurst led a group that performed measurements of the absorbed dose of neutrons, and of mixed radiation field of neutrons and gamma rays. This resulted in the publication of Handbook 75 for the National Bureau of Standards.

In 1950, Hurst and his team developed a portable alpha survey meter.

In 1953, an interest in the ion pair energy production from 5 MeV alpha particles led to nearly 2 decades of research, during which time Hurst studied alpha particle ionizations and excitations in various gases and gas mixtures.

Hurst and the team of L.J. Deal and H.H. Rossi performed gamma and neutron radiation measurements at the Nevada Test Site during Operation Upshot–Knothole for the Atomic Energy Commission. For Operation PLUMBBOB, Hurst was again asked to participate along with Ritchie at the Nevada Test Site to collect radiation dosimetry data for human exposures during the tests.

The Jesse effect, named after William P. Jesse, may best be described as the increase in ionization produced in a gas by alpha, beta, or gamma ionizing radiations when a small concentration of a gas with a lower ionization potential is present. Hurst utilized noble gases to examine vacuum ultraviolet radiation (VUV) and the Jesse effect. For these efforts, Hurst sought the assistance of Thurmond E. Stewart, James E. Parks, H. Lee Weidner, M. Payne and C. Klots. Hurst performed additional VUV studies separately on Helium, Argon, and Krypton.

In the 1960s, Hurst along with L.B. O'Kelly, E.B. Wagner, J.A. Stockdale, James E. Parks, and F.J. Davis investigated time-of-flight electron transport in gases. The group utilized ethylene, water vapor and hydrogen to study and determine time-of-flight electron diffusion coefficients and electron drift velocities for these gases. Hurst led efforts to investigate time-of-flight of electron transport in atomic and molecular gases.

In the mid 1960s, Hurst pursued researches that involved electron swarm measurement, swarm‐beam techniques and swarm drift to determine electron capture cross sections in heavy water, chlorobenzene, bromobenzene, ethylene and ethylene mixtures.

In the 1950s, Hurst went to Japan with colleagues and students Rufus Ritchie, Nello Pace, and Robert E. Smith to conduct studies for the Atomic Bomb Casualty Commission. The team studied the delayed and latent effects with an emphasis on the mortality and morbidity rates among the atomic bomb survivors of Hiroshima and Nagasaki.

The expertise and experience of Hurst were often called upon for matters that involved radiation accidents.

The IAEA asked for and received assistance from Hurst to investigate the Vinča reactor criticality accident that occurred on 15 October 1958 at Vinča, Yugoslavia.

In 1965, Hurst prepared a special publication for NASA for radiation dosimetry applications to be utilized for data collection that involved radiation in space. Then in 1986, a technical report was prepared for NASA that looked at the feasibility of a solar neutrino experiment.