Elizabeth Riddle Graves

Elizabeth Riddle Graves (25 January 1916[citation needed] – 6 January 1972) was a pioneer in the physics of neutrons and the detection and measurement of fast neutrons. During World War II, she worked in the Metallurgical Laboratory and at the Los Alamos Laboratory, becoming a group leader there after the war. She was probably the highest ranking of the Los Alamos women scientists.[1]

Elizabeth Riddle Graves
Elizabeth Riddle Graves.jpg
Elizabeth R. Graves's Los Alamos identity card
Born(1916-01-23)January 23, 1916
DiedJanuary 6, 1972(1972-01-06) (aged 55)
CitizenshipUnited States of America
Alma materUniversity of Chicago
Known forPhysics of neutrons
Scientific career
InstitutionsLos Alamos Scientific Laboratory
ThesisEnergy Released from Be 9 (d, α) Li 7 and the Production of Li 7 (1940)
Doctoral advisorSamuel K. Allison[citation needed]

Life and EducationEdit

Elizabeth Riddle was born in Nashville, Tennessee, on 23 January 1916 to James Marion Riddle from South Carolina and Georgia Clymetra Boykin from Arkansas. She had two brothers, James Marion Riddle Jr. and John Burwell Boykin Riddle. Around 1921, the Riddle family moved to Chicago, Illinois.[2]

Riddle entered the University of Chicago, where she was known as "Diz".[3] She earned her Bachelor of Science degree in physics in 1936,[4] and developed a keen interest in the physics of neutrons, particularly the detection and measurement of fast neutrons.[5] She earned her PhD in 1940, writing her thesis on the "Energy Released from Be 9 (d, α) Li 7 and the Production of Li 7" under the supervision of Samuel K. Allison.[4][6]

While there, she met and married Alvin C. Graves, a fellow physics major.[7] Jobs were hard to find during the Great Depression. Alvin remained at the University of Chicago as a research fellow and an assistant professor until 1939, when he moved to the University of Texas,[7] but Elizabeth was unable to secure a job there as well due to its anti-nepotism rules, which tended to discriminate against women.[3]

The Manhattan ProjectEdit

In 1942 Alvin was invited back to the University of Chicago by Arthur H. Compton to join the Manhattan Project's Metallurgical Laboratory. [7] Elizabeth found employment there as well, working with Enrico Fermi on the calculations involved in determining the feasibility of a nuclear chain reaction, which eventually led to the development of Chicago Pile-1, the world's first nuclear reactor.[4]

In 1943 they joined the Manhattan Project's Los Alamos Laboratory in New Mexico. She was one of the few scientists who knew about fast neutron scattering, which was crucial to nuclear weapon design, and who knew how to operate the Cockcroft–Walton accelerator that had been brought from the University of Illinois.[3]

Employed as a "scientist," which was a high ranking role in the project as compared to "associate scientist" or "junior scientist," Dr. Graves worked as a member of R-division. She contributed greatly to the Project, including measuring cross-sections pertaining to nuclear reactions, measuring neutron multiplication effects in uranium metal, and investigating the different neutron scattering properties of tamper materials considered for use in atomic weapons.[8]

At the time of the Trinity nuclear test in 1945, Elizabeth was seven months pregnant with her first child. They therefore requested that they be assigned to a post far from the blast. They listened to Allison's countdown to the explosion on the radio, and using Geiger counters, they monitored the test's radioactive fallout, which took until the afternoon to reach them. Elizabeth finished an experiment while in labor, timing her contractions with a stopwatch.[3] The child was a healthy daughter, Marilyn Edith.[7] Alvin and Elizabeth had two more children, Alvin Palmer and Elizabeth Anne.[4]


They remained in Los Alamos after the war. Elizabeth became a group leader in the experimental physics division in 1950, and researched neutron interactions with matter and material.[4][9] She died of cancer at Bataan Memorial Hospital in Albuquerque, New Mexico,[4] on 6 January 1972, and was buried at Guaje Pines Cemetery, Los Alamos, Los Alamos County, New Mexico.[10][11]

Select PublicationsEdit


  • Low voltage 14 MeV neutron source.[12]

Dissertation and ThesisEdit

  • Energy Released from Be 9 (d, α) Li 7 and the Production of Li 7. 1940.[6]


The α-particles from Be9(d,α)Li7 have been investigated with a variable air pressure absorption cell, ionization chamber and linear amplifier. It has been established that there are two groups of α-particles differing at 760 mm pressure and 15°C by 3.08±0.10 mm range reduced to zero bombarding voltage. The groups have been shown to be associated with the production of Li7 in the ground state and in an excited state. At 239 kv bombarding voltage, the excited state is formed 1.7 times as often as the ground state. The energy balance, Q, associated with the production of the ground state has been determined to be 7.093±0.022 Mev. The energy of the excited level has been determined to be 494±16 kev. The total yield curve for α-particles has been investigated from 235 kv to 390 kv bombarding voltage. The measured value for the energy of the excited level in Li7 is discussed in connection with values from other reactions in which Li7 is an end product and with γ-ray measurements of the level.[6]


1930s - 1940sEdit

  • Allison, Samuel K., Graves, Elizabeth R., Skaggs, Lester S., & Smith Jr, Nicholas M. (1939). A Precise Measurement of the Mass Difference Be 9 4—Be 8 4; The Stability of Be 8 4. Physical Review. 55(1): 107.
  • Allison, S. K., Graves, E. R., & Skaggs, L. S. (1940). Alpha-Particle Groups from the Disintegration of Beryllium by Deuterons. Physical Review. 57(2): 158.
  • Graves, A. C., Graves, E. R., Coon, J. H., & Manley, J. H. (January 1946). Cross Section of D (D, P) H-3 Reaction. Physical Review. 70(1-2): 101.
  • Manley, J. H., Coon, J. H., & Graves, E. R. (January 1946). Cross Section of D (D, N) He-3 Reaction. Physical Review. 70(1-2): 101.
  • Graves, E. R., & Coon, J. H. (January 1946). Disintegrations of Neon and Argon by dd Neutrons. Physical Review. 70(1-2): 101.
  • Manley, J. H., Agnew, H. M., Barschall, H. H., Bright, W. C., Coon, J. H., Graves, E. R., Jorgensen, T. & Waldman, B. (1946). Elastic Backscattering of d− d Neutrons. Physical Review. 70(9-10): 602.
  • Barschall, Henry Herman, Battat, M. E., Bright, W. C., Graves, E. R., Jorgensen, T., & Manley, J. H. (1947). Measurement of Transport and Inelastic Scattering Cross Sections for Fast Neutrons. II. Experimental Results. Physical Review. 72(10): 881.
  • Graves, E. R. (1949). Mayer. Physical Review. 76(1): 183.
  • Graves, E. R., Rodrigues, A. A., Goldblatt, M., & Meyer, D. I. (1949). Preparation and use of tritium and deuterium targets. Review of Scientific Instruments. 20(8): 579-582.am

1950s - 1960sEdit

  • Coon, J. H., Graves, E. R., & Barschall, H. H. (1952). Total Cross Sections for 14-MeV Neutrons. Los Alamos Scientific Laboratory of the University of California.
  • Graves, E. R., & Rosen, L. (January 1952). Energy Spectrum of Neutrons from the Interaction of 14-Mev Neutrons with C, Al, Fe, Cu, Zn, Ag, Cd, Sn, Au, Pb, and Bi. Physical Review. 87(1): 239.
  • Coon, J. H., Graves, E. R., & Barschall, H. H. (1952). Total Cross Sections for 14-Mev Neutrons. Physical Review. 88(3): 562.
  • Phillips, D. D., Davis, R. W., & Graves, E. R. (1952). Inelastic Collision Cross Sections for 14-Mev Neutrons. Physical Review. 88(3): 600.
  • Forbes, S. G., Graves, E. R., & Little, R. N. (1953). Low Voltage 14‐Mev Neutron Source. Review of Scientific Instruments. 24(6): 424-427.
  • Graves, E. R., & Rosen, Louis. (1953). Distribution in Energy of the Neutrons from the Interaction of 14-MeV Neutrons with some Elements. Physical Review. 89(2): 343.
  • Graves, E. R., & Davis, Roland W. (1955). Cross sections for nonelastic interactions of 14-Mev neutrons with various elements. Physical Review. 97(5): 1205.
  • Battat, M. E., & Graves, E. R. (1955). Gamma Rays from 14-Mev Neutron Bombardment of C 12. Physical Review. 97(5): 1266.
  • McDole, C. J., Graves, E. R., & Davis, R. W. (1955). Calibration of a Mock Fission Neutron Source by Indium Resonance Mapping of the Standard Graphite Pile (No. LA-1982). Los Alamos Scientific Lab., New Mexico.
  • Seagrave, J. D., Graves, E. R., Hipwood, S. J., & McDole, C. J. (1958). D (d, n) 3 He and T (d, n) 4 He Neutron Source Handbook. Los Alamos Scientific Laboratory Lams, 2162.
  • Graves, E. R. (1963). Howard Eberline Neutron Survey Instrument PNC-1 Evaluation and Recommendation for Use. (No. LA-2860). Los Alamos Scientific Lab., New Mexico.
  • Davis, R. W., & Graves, E. R. (1969). The Radiation Instrument Calibration Facility at the Los Alamos Scientific Laboratory. (No. LA—4090). Los Alamos Scientific Lab., New Mexico.
  • Davis, R., & Graves, E. (1969). The Radiation Instrument Calibration Facility at the Los Alamos Scientific Laboratory. (Construction and calibration of radiation survey instruments).


  1. ^ Personnel Roster, circa 1944-1945, Collection A-84-019, Box 4-8, LANL Archives.
  2. ^ "United States Census, 1930". FamilySearch. Retrieved 15 August 2015. Elizabeth B Riddle in household of James M Riddle, Chicago (Districts 0751-1000), Cook, Illinois, United States; citing enumeration district (ED) 0765, sheet 12A, family 145, line 4, NARA microfilm publication T626 (Washington D.C.: National Archives and Records Administration, 2002), roll 449; FHL microfilm 2,340,184.
  3. ^ a b c d Howes, Ruth H.; Herzenberg, Caroline L. (1999). Their Day in the Sun: Women of the Manhattan Project. Temple University. pp. 48–50. ISBN 978-0-585-38881-6. OCLC 49569088.
  4. ^ a b c d e f Ogilvie, Marilyn; Harvey, Joy (2000). The Biographical dictionary of women in science : pioneering lives from ancient times to the mid-20th century. New York: Routledge. pp. 522–523. ISBN 9780415920407. OCLC 803021974.
  5. ^ "Elizabeth R. Graves". Physics Today. 25 (4 p=67): 67. April 1972. doi:10.1063/1.3070831.
  6. ^ a b c Graves, Elizabeth Riddle (May 1940). "Energy Release from Be9(d,α)Li7 and the Production of Li7". Physical Review. 57 (10): 855–862. Bibcode:1940PhRv...57..855G. doi:10.1103/PhysRev.57.855.
  7. ^ a b c d Becker, Bill (19 April 1952). "The Man Who Sets Off Atomic Bombs". The Saturday Evening Post. pp. 32–33, 185–188.
  8. ^ "Elizabeth R. Graves". Physics Today. 25 (4): 67. April 1972. doi:10.1063/1.3070831. ISSN 0031-9228.
  9. ^ Coyne, Colleen (29 April 2013). "Female Scientists, the Military, and Informing Policy". Bowling Green State University. Retrieved 18 May 2016.
  10. ^ "Elizabeth Riddle Graves". Family Search. Retrieved 15 August 2015.
  11. ^ "Elizabeth Riddle Graves". Find a Grave. Retrieved 18 May 2016.
  12. ^ Graves, E. R., & Little Jr, Robert N. (1959). U.S. Patent 2,906,903. Washington, DC: U.S. Patent and Trademark Office.