Phyllis S. Freier (19 January 1921, Minneapolis – 18 December 1992, St. Paul) was an American astrophysicist and a

Fellow, American Association for the Advancement of Science Fellowship of the American Association for the Advancement of Science (FAAAS) is an honor accorded by the American Association for the Advancement of Science (AAAS) to distinguished persons who are members of the Association. Fellows are elected ...

and a Fellow, American Physical Society''.'' Freier also served on

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

committees. As a graduate student she presented evidence for the existence of elements heavier than

helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...

cosmic radiation Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...

. Her work was published in ''Physical Review'' in 1948 with co-authors

Edward J. Lofgren Edward Joseph Lofgren (January 18, 1914 – September 6, 2016) was an American physicist in the early days of nuclear physics and elementary particle research at the Lawrence Berkeley Laboratory (LBL). He was born in Chicago. He was an important fig ...

, Edward P. Ney, and

Frank Oppenheimer Frank Friedman Oppenheimer (August 14, 1912 – February 3, 1985) was an American particle physicist, cattle rancher, professor of physics at the University of Colorado, and the founder of the Exploratorium in San Francisco. A younger brother ...

Early life and education

Phyllis St. Cyr was born in

Minneapolis, Minnesota Minneapolis () is the largest city in Minnesota, United States, and the county seat of Hennepin County. The city is abundant in water, with thirteen lakes, wetlands, the Mississippi River, creeks and waterfalls. Minneapolis has its origins ...

, on January 21, 1921. She received her B.S. in 1942, her M.A. in 1944, and finally her Ph.D. in 1950 from the

University of Minnesota, Minneapolis The University of Minnesota, formally the University of Minnesota, Twin Cities, (UMN Twin Cities, the U of M, or Minnesota) is a public university, public Land-grant university, land-grant research university in the Minneapolis–Saint Paul, Tw ...

. St. Cyr married fellow physicist George Freier after receiving her M.A.

Career

During World War II, Freier was employed as a

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate caus ...

at the

Naval Ordnance Laboratory The Naval Ordnance Laboratory (NOL) was a facility in the White Oak area of Montgomery County, Maryland. It is now used as the headquarters of the U.S. Food and Drug Administration. Origins The U.S. Navy Mine Unit, later the Mine Laboratory at t ...

from 1944 to 1945. Following the war, she continued her graduate studies in physics at the University of Minnesota. Freier worked on her doctoral research with Edward Ney and Frank Oppenheimer, using high altitude balloons to study cosmic radiation. In 1948, this research led to Freier becoming the first person to see tracks in nuclear emulsions, proving that nuclei of heavy elements were included in cosmic radiation. After completing her Ph.D., Freier was a research associate at the

from 1950 to 1970. She stayed at that university and from 1970 to 1975 she was an associate professor, and from 1975-1992 she was a professor of physics. In 1988, Freier was recognized by the University of Minnesota with a distinguished teaching award for her outstanding contributions to the education of physics undergraduates. She taught for eighteen years where she originated the application of student textbook learning to the laboratory settings.

Research contributions

More specifically, Freier was an internationally reputable cosmic-ray physicist. Her expertise was the application of nuclear emulsions to astrophysics and physics. At the

University of Minnesota The University of Minnesota, formally the University of Minnesota, Twin Cities, (UMN Twin Cities, the U of M, or Minnesota) is a public university, public Land-grant university, land-grant research university in the Minneapolis–Saint Paul, Tw ...

, she and her colleagues discovered the presence of heavy nuclei in cosmic radiation, which remains one of the key discoveries in astrophysics. In addition to her contribution as graduate student, mentioned above, she also published other significant contributions in the fields of particle physics, geophysics, and astrophysics that covered nuclear

emission spectra The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted due to an electron making a atomic electron transition, transition from a high energy state to a lower energy st ...

cosmic ray Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...

s, and applying

nuclear emulsion A nuclear emulsion plate is a type of particle detector first used in nuclear and particle physics experiments in the early decades of the 20th century. https://cds.cern.ch/record/1728791/files/vol6-issue5-p083-e.pdf''The Study of Elementary Partic ...

Death

Freier died at home in St. Paul, Minnesota on December 18, 1992 from

Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms becom ...

Legacy

*"Primary Cosmic Radiation," Phys. Rev. 74:1818-1827 (1948) with E.J. Lofgren, E.P. Ney, and F. Oppenheimer *"Emulsion Measurements of Solar Alpha Particles and Protons," ''J. Geophys. Res.'' 68:1605-1629 (1963) *"The Helium Nuclei of the Primary Cosmic Radiation as Studied over a Solar Cycle of Activity, Interpreted in Terms of the Electric Field Modulation," ''Space Science Reviews'' 4:313-371 (1965) with C.J. Waddington *"The Cascading of Cosmic Ray Nuclei in Various Media," ''Astrophys. and Space Sci.'' 38:419-436 (1975)with C.J. Waddington. *"Nucleus-Nucleus Collisions and Interpretation of Cosmic Ray Cascades above 100 TeV," ''Phys. Rev. D ''Vol. 25, No. 9, 1 May (1982) with T.K. Gaisser, Todor Stanev, and C.J. Waddington. *"The Interactions of Energetic Gold Nuclei in Nuclear Emulsions," ''Nucl. Tracks ''9:107-111 (1984) with C.J. Waddington. *"Central Collisions 14.6, 60, and 200 GeV/Nucleon ¹⁶O Nuclei in Nuclear Emulsion," ''Phys. Rev. Lett. ''60:405 (1988)with L.M. Barbier, R. Holynski, W.V. Jones, A. Jurak, A. Olszewski, O.E. Pruet, C.J. Waddington, J.P. Wefel, B. Wilczynska, H. Wilczynski, W. Wolter, and B. Wosiek.

Honors

Fellow,

American Association for the Advancement of Science The American Association for the Advancement of Science (AAAS) is an American international non-profit organization with the stated goals of promoting cooperation among scientists, defending scientific freedom, encouraging scientific respons ...

Fellow,

American Physical Society The American Physical Society (APS) is a not-for-profit membership organization of professionals in physics and related disciplines, comprising nearly fifty divisions, sections, and other units. Its mission is the advancement and diffusion of k ...

Horace T. Morse-Minnesota Alumni Association Award

References

{{DEFAULTSORT:Freier, Phyllis S American astrophysicists 1921 births 1992 deaths American women physicists University of Minnesota alumni University of Minnesota faculty 20th-century American physicists 20th-century American women scientists Cosmic ray physicists American women academics