Richard Raymond Carlson

Richard Raymond Carlson, professor emeritus in the University of Iowa’s department of physics and astronomy, died on 24 October 2001 in Iowa City of complications resulting from diabetes.

Dick was born on 15 September 1923 in Chicago, Illinois. He received his BS in physics in 1945 at the University of Chicago and conducted his MS and PhD research in what is now called the Enrico Fermi Institute for Nuclear Studies. He earned his MS in physics in 1949 and completed his physics PhD in 1951 under the direction of Sam Allison. Dick’s thesis, “The Energy Release on the Break-up of ⁸Be and the Energy Spectrum of the Alpha Particles Thus Released,” was one of the first studies of the structure of intermediate-mass nuclei.

Dick joined the physics and astronomy department at Iowa in 1951 as an assistant professor. There, for the next 10 years, he carried out nuclear structure studies, mostly precision measurements of y rays that were produced by proton beams from a 4-MV Van de Graaff accelerator and a high-current (100 µA), 500-kV Cockcroft–Walton accelerator. During the 1950s, he did research at Oak Ridge National Laboratory, Los Alamos Scientific Laboratory (now Los Alamos National Laboratory), and, as a Guggenheim fellow, Oxford University. In the course of his research at those labs, he learned new experimental techniques that he introduced to the nuclear program at Iowa.

In 1961, with a lithium-ion source in the old Van de Graaff at Iowa, Dick began research on the reactions of lithium ions on light nuclei. These studies were the first to use a general-purpose digital computer to record data from multiple detectors. Such multidimensional data acquisition was essential for effective use of position-sensitive silicon detectors, which were developed at Iowa for use with the lithium-beam experiments. Now, position-sensitive detectors are standard equipment in nuclear physics and elementary particle laboratories.

In 1964, Dick replaced the old Iowa Van de Graaff with a new 6-MV Van de Graaff (funded by NSF). He designed a carbon-foil mechanism that he inserted into the accelerating tube. As the singly charged lithium beams from the ion source passed through the carbon foil, one or two additional electrons were knocked off to produce Li²⁺ or Li³⁺ ions at a point about one-third of the way through the accelerating tube. With this feature, the 6-MV accelerator could put out beams of lithium ions with energies up to 13 MeV. For the next decade, Dick carried out a highly fruitful study of the reactions of lithium-ion beams.

For a number of years, Dick was the university’s representative on the governing board of the Midwestern Universities Research Association, the precursor to Fermilab. Around 1980, health problems forced Dick to cut back on his experimental research activities. He then concentrated on finding optical-model potentials to describe lithium-ion scattering. He retained an active interest in the lithium-ion program until his retirement in 1994. He stayed in Iowa City after his retirement and remained available for consultation.

Dick also had broader concerns. For example, he was one of the eight University of Iowa physicists who, in 1961, signed a letter to the Iowa City Press Citizen that addressed the practicality of fallout shelters. The letter, written in response to a popular series of articles titled “You Can Survive Atomic Attack” (by Nobel laureate Willard Libby), played an important role in helping the public understand a complicated technical issue, and was reprinted in many newspapers.

Dick was an excellent and dedicated teacher. He designed a curriculum for engineering students that is still in use today. His students particularly remember his qualities as a teacher and mentor. His lectures were crisp and provided a lively entrée into nuclear physics. He encouraged his research students to be creative and independent, but offered just the right amount of guidance and wisdom so they could successfully complete their projects.