| Elizabeth Riddle Graves | |
| Birth Date: | 23 January 1916 |
| Birth Place: | Nashville, Tennessee, US |
| Death Place: | Albuquerque, New Mexico, US |
| Field: | Physics |
| Work Institution: | Los Alamos Scientific Laboratory |
| Alma Mater: | University of Chicago |
| Doctoral Advisor: | Samuel K. Allison |
| Thesis Title: | Energy Released from Be 9 (d, α) Li 7 and the Production of Li 7 |
| Thesis Year: | 1940 |
| Known For: | Physics of neutrons |
Elizabeth Riddle Graves (23 January 1916 – 6 January 1972) was an American nuclear physicist who pioneered the physics of neutrons and the detection and measurement of fast neutrons. She served at the Manhattan Project's Metallurgical Laboratory and the Los Alamos Laboratory during World War II. After the war, she became a group leader in the experimental physics division at Los Alamos.
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.[1]
Graves entered the University of Chicago, where she was known as "Diz".[2] She earned her Bachelor of Science degree in physics in 1936, and developed a keen interest in the physics of neutrons, particularly the detection and measurement of fast neutrons.[3]
While there, she met and married Alvin C. Graves, a fellow physics major.[4] In 1939, Alvin took a position at the University of Texas, but Elizabeth was unable to secure a job there as well due to its anti-nepotism rules, which tended to discriminate against women.
Graves earned her PhD at the University of Chicago 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.[5]
In 1942, Graves joined the Manhattan Project's Metallurgical Laboratory, 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.[5]
In 1943, Elizabeth Graves joined the Manhattan Project's Los Alamos Laboratory in New Mexico. Alvin Graves, who was recruited first, insisted that Elizabeth be allowed to work at Los Alamos as a condition of his participation in the project. According to Howes and Herzenberg in 2003, even if Alvin had not insisted, Elizabeth "probably would have been recruited anyway". 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.
Employed as a "scientist", which was a high-ranking role in the project as compared to "associate scientist" or "junior scientist", 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.[6] [7] She worked on selecting a neutron reflector to "surround the core of the atomic bomb".
At the time of the Trinity nuclear test in 1945, Graves was seven months pregnant with her first child. The Graves family 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. Graves finished an experiment while in labor, timing her contractions with a stopwatch. The child was a healthy daughter, Marilyn Edith. Elizabeth and Alvin had two more children, Alvin Palmer and Elizabeth Anne.[5]
Elizabeth and Alvin Graves remained at Los Alamos after the war.
On 21 May 1946, Alvin was in the room with seven other men when Canadian physicist Louis Slotin accidentally slipped and filled the room with a "blue ionization glow" during a demonstration of what became known as the demon core. Slotin knew he had absorbed a fatal dose of radiation, and Alvin Graves was standing the closest to Slotin when the incident occurred. Louis Slotin asked Elizabeth Graves to calculate whether or not a human could survive that dosage of radiation, referring to her husband, without telling her about the accident. Elizabeth was a self-proclaimed stoic, but "she froze when she learned who the subject of her calculation was". Alvin developed acute radiation sickness and was hospitalized for several weeks.[8] He survived but had chronic neurological and vision problems.
In 1950, Graves became a group leader in the experimental physics division at Los Alamos, and researched neutron interactions with matter and material.[9]
Graves died of cancer at age 55 on 6 January 1972, at Bataan Memorial Hospital in Albuquerque, New Mexico. She was buried at Guaje Pines Cemetery, Los Alamos, Los Alamos County, New Mexico.[10] [11] Alvin had died in 1965 of a heart attack.[12]
Colleagues described her as a "very" hard worker and someone who was "very good at her job". Graves was a self-proclaimed Stoic, and reportedly once described the atomic bombing of Hiroshima as being no worse than (an attack by) napalm. Despite having what was described as a conventional outlook, she was an independent thinker and was able to assert her point of view when she thought it necessary.
Graves was said to have a sense of humor. One story told by her colleagues was that she once had a bet with them that she could persuade a "very proper" European physicist to go through a door before her (as was customary for males to allow a woman through a door before them). She won the bet by telling the man that she had ripped her dress and "that modesty dictated that he go first".[13]