Phyllis S. Freier

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Phyllis S. Freier
Phyllis St. Cyr

DiedDecember 18, 1992(1992-12-18) (aged 71)
Alma materUniversity of Minnesota, Minneapolis (B.S., M.A., Ph.D.)
SpouseGeorge Freier
Scientific career
InstitutionsUniversity of Minnesota, Minneapolis

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 and a Fellow, American Physical Society. Freier also served on NASA committees.[1] As a graduate student she presented evidence for the existence of elements heavier than helium in cosmic radiation. Her work was published in Physical Review in 1948 with co-authors Edward J. Lofgren, Edward P. Ney, and Frank Oppenheimer.[2][3][1]

Early life and education[edit]

Phyllis St. Cyr was born in Minneapolis, Minnesota, 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. St. Cyr married fellow physicist George Freier after receiving her M.A.[4]


During World War II, Freier was employed as a physicist at the Naval Ordnance Laboratory 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.[5] After completing her Ph.D., Freier was a Research Associate at the University of Minnesota, Minneapolis 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.[2][1]

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.[6]

Research contributions[edit]

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, she and her colleagues discovered the presence of heavy nuclei in cosmic radiation, which remains one of the key discoveries in astrophysics.[1]

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, cosmic rays, and applying nuclear emulsions.[2][7]


Freier died at home in St. Paul, Minnesota on December 18, 1992 from Parkinson's disease.[1]


  • "Primary Cosmic Radiation," Phys. Rev. 74:1818-1827 (1948) with E.J. Lofgren, E.P. Ney, and F. Oppenheimer[5][8]
  • "Emulsion Measurements of Solar Alpha Particles and Protons," J. Geophys. Res. 68:1605-1629 (1963) [8]
  • "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 [8][9]
  • "The Cascading of Cosmic Ray Nuclei in Various Media," Astrophys. and Space Sci.  38:419-436 (1975)with C.J. Waddington.[8]
  • "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.[8]
  • "The Interactions of Energetic Gold Nuclei in Nuclear Emulsions," Nucl. Tracks  9:107-111 (1984) with C.J. Waddington.[8]
  • "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.[8]


Fellow, American Association for the Advancement of Science[8] Fellow, American Physical Society[8]

Horace T. Morse-Minnesota Alumni Association Award [6]


  1. ^ a b c d e Waddington, C. Jake (1993). "Phyllis S. Freier (Obituary)". Physics Today. 46 (12): 65. Bibcode:1993PhT....46l..65B. doi:10.1063/1.2809138.
  2. ^ a b c Professor C. J. Waddington. "Phyllis S. Freier 1921-1992". Contributions of 20th Century Women to Physics. CWP at UCLA. Retrieved 2013-01-21.
  3. ^ Freier, Phyllis; Lofgren, E.; Ney, E.; Oppenheimer, F.; Bradt, H.; Peters, B. (1948). "Evidence for Heavy Nuclei in the Primary Cosmic Radiation". Physical Review. 74 (2): 213. Bibcode:1948PhRv...74..213F. doi:10.1103/PhysRev.74.213.
  4. ^ "Collection: Phyllis St. Cyr Freier Papers | University of Minnesota Archival Collections Guides". Retrieved 2020-03-06.
  5. ^ a b Freier, Phyllis; Lofgren, E. J.; Ney, E. P.; Oppenheimer, F.; Bradt, H. L.; Peters, B. (1948-07-15). "Evidence for Heavy Nuclei in the Primary Cosmic Radiation". Physical Review. 74 (2): 213–217. Bibcode:1948PhRv...74..213F. doi:10.1103/PhysRev.74.213.
  6. ^ a b Association, University of Minnesota Alumni (1988). "Minnesota Magazine, May 1988 - August 1988. Vol.87 No.5- No.6". {{cite journal}}: Cite journal requires |journal= (help)
  7. ^ Freier, Phyllis S.; Waddington, C. J. (December 1975). "The cascading of cosmic-ray nuclei in various media". Astrophysics and Space Science. 38 (2): 419–436. Bibcode:1975Ap&SS..38..419F. doi:10.1007/BF00647143. S2CID 123490596.
  8. ^ a b c d e f g h i "CWP at // Phyllis Freier". Retrieved 2019-03-08.
  9. ^ Freier, P. S.; Waddington, C. J. (1965-05-01). "The helium nuclei of the primary cosmic radiation as studied over a solar cycle of activity, interpreted in terms of electric field modulation". Space Science Reviews. 4 (3): 313–372. Bibcode:1965SSRv....4..313F. doi:10.1007/BF00210708. ISSN 1572-9672. S2CID 118429946.