A computing collage


By Whitney Spivey| February 19, 2021

Women have always been a crucial part of the Laboratory workforce—because of their contributions to national security and also because they’ve helped the Lab evolve into a more inclusive place to work.

IN 1944, chemist Lilli Hornig conducted plutonium research at Project Y—the Los Alamos, New Mexico, branch of the Manhattan Project—where she was physically segregated from her male colleagues. “I worked in a cubbyhole … I was really just cut off from everything else,” she told a Laboratory historian many years later. “I don’t know if that was because we were women or because we were doing work that we had to be segregated, but I suspect the former because it wasn’t the only place that it happened to me.”

Hornig felt that many men at that time were “not fond of women scientists generally” and often treated them as assistants rather than equals. “I was being asked to produce the readings, the data would go to someone else,” she remembered. “If I asked questions, that was all right … but I never engaged anybody in what we could call a technical discussion, and I resented that very much … I was unhappy, and that was the working situation.”

Jane Hamilton Hall and her husband, David Hall. Los Alamos National Laboratory

Although common, this working situation was not true for all women at Los Alamos in the early days. In 1943, for example, nuclear physicist Jane Hamilton Hall received a raise “to bring her salary in line with those of comparable physicists,” according to her division leader. In 1946, Hall’s performance review states that she was “not of secondary importance” on a project that she worked on with her husband. Hall went on to become the Laboratory’s first female assistant director.

During the Manhattan Project, 640 women worked at Los Alamos—about 11 percent of the total workforce. Today, women comprise 34.9 percent of the Lab’s workforce—3,311 of 9,493 employees. Women hold nearly a third of management positions, and women are 20.4 percent of the professional research and development workforce.

The following timeline highlights notable women at the Laboratory and their achievements, as well as changes in federal legislation and the workplace that continue to make Los Alamos a great (but always improving) place for women to work.

Frances Dunne

1943: Dorothy McKibbin was a 45-year-old single mother and bookkeeper when J. Robert Oppenheimer hired her to be the first point of contact for Manhattan Project scientists before they headed “up the hill” from Santa Fe to Los Alamos. Known as the “first lady of Los Alamos,” McKibbin was stationed in a nondescript adobe building at 109 E. Palace Avenue in Santa Fe, a position she held until the office closed in 1963.

1943: The first Women’s Army Corps (WAC) detachment arrived in Los Alamos on August 24, 1943. A significant portion—about 40 percent—of women employed at Los Alamos through the end of the Manhattan Project were members of the WAC and were commonly referred to as “WACs”. At its peak in August of 1945, the Los Alamos detachment had about 260 WACs. Many worked as medical staff, cooks, and librarians; others took on roles traditionally held by men, such as drivers, supply clerks, researchers, and scientists. The detachment was deactivated on October 19, 1946.

1943: Librarian Charlotte Serber was the only female group leader of the Manhattan Project. As such, she organized and protected secret documents in a space that featured a document room, a vault, and a ditto (copying) machine. In addition to its official purpose, Serber later said the library was a “center for gossip” and a “hangout” space.

1943: Physicist Elda Anderson joined the Laboratory after earning a doctorate from the University of Wisconsin–Madison. Working in the cyclotron group at Los Alamos, Anderson focused mainly on spectroscopy and neutron cross-section measurements. Her work led her to produce the Lab’s first sample of nearly pure uranium-235.

1943: In the spring of 1943, Mary Frankel arrived at Los Alamos. With degrees in psychology and mathematics, Frankel became a junior scientist in the Computation group. She became an expert in using numerical methods to solve physical equations and was in charge of setting up the problems for the staff to run on desk calculators.

Dorothy McKibbin Los Alamos National Laboratory

1943: In the 1940s, a “computer” was a person—usually a woman—whose job it was to perform calculations by hand, sometimes with the aid of a mechanical calculator. Women with degrees in mathematics and the sciences often took jobs as computers because of discrimination in their fields. Many of the women who became computers were vastly overqualified for their positions. At Los Alamos, approximately 20 computers worked in the Computation group by the end of the summer of 1943.

1944: A Manhattan Project WAC, Jane Heydorn arrived in Los Alamos in 1944 and began work as a telephone operator, monitoring calls for leaks of classified information. She later developed bomb-testing equipment as an electronics technician and then went on to operate Clementine, the world’s first fast-neutron nuclear reactor.

1944: Explosives technician Frances Dunne was recruited to work at Los Alamos in 1944 and was part of the assembly crew for the Trinity test the following year. The only woman in the Explosives Assembly group, her small hands and manual dexterity were key because she could adjust weapons parts more easily than her male counterparts. 

1945: Nuclear physicist Elizabeth “Diz” Riddle Graves came to Los Alamos with her husband, Al Graves. Her primary work involved selecting a neutron reflector to surround the core of an implosion device. On July 16, 1945, Graves, then seven months pregnant, watched the Trinity test from a cabin 40 miles away. Five years later, she became a group leader in the Experimental Physics Division, where she researched neutron interactions with matter and material.

1945: Beverly Wellnitz was a group secretary who quickly determined the technical staff members she supported could benefit from access to the work of their predecessors. Of her own initiative, she began meticulously processing and cataloging all the trackable classified documents passing across her desk. Today, these documents are referred to as the Wellnitz Vault and the highly respected Wellnitz Collection. 

Maria Goeppert Mayer
Maria Goeppert Mayer Los Alamos National Laboratory

1945: By May, Norma Gross was one of about 30 women included in the Lab’s estimated 1,700 technical or scientific staff. Gross, a trained chemist with a master’s degree, was stationed in Los Alamos as part of the WAC. Gross worked in the Chemistry and Metallurgy (CMR) Division, which conducted experiments that studied shockwave behavior to support the design of the Fat Man bomb. After the war ended, Gross was honorably discharged from the WAC, and the Lab hired her as an associate scientist in CMR.

1945: German-born American theoretical physicist Maria Goeppert Mayer came to Los Alamos in 1945 to work with Edward Teller on the development of the atomic bomb. After World War II, Goeppert Mayer continued working with Teller at the University of Chicago and eventually developed a mathematical model for the structure of nuclear shells, for which she was awarded the Nobel Prize in Physics in 1963.

1946: Floy Agnes “Aggie” Naranjo Lee, a member of New Mexico’s Santa Clara Pueblo, worked as a technician in the hematology lab at Los Alamos. She collected and examined blood samples from Manhattan Project scientists, including Louis Slotin after he was exposed to a fatal dose of radiation in 1946. After the war ended, Enrico Fermi, with whom she played tennis, encouraged Lee to continue her studies at the University of Chicago. She eventually earned a doctorate in biology and went on to work at Argonne National Laboratory. In a Voices of the Manhattan Project interview, Lee described how Manhattan Project officials told the local public a cover story that Los Alamos was a “hideout for pregnant WACs. Santa Fe loved that story—they believed it,” she said.

Mary Tsingou Los Alamos National Laboratory


1951: After earning a mathematics degree in 1931, Marjorie Devaney came to Los Alamos because it was one of the few places in the world with an electric computer. She joined the MANIAC (Mathematical Analyzer, Numerical Integrator, and Computer) group of the Theoretical Division as one of the MANIAC’s first programmers, then called “coders.” She went on to have a 40-year-long career at the Laboratory.

1951: Not long after she earned a doctorate in physics at the age of 21, Arianna Rosenbluth began working at Los Alamos in 1951. There, she verified analytic calculations for Ivy Mike—the first full-scale test of a thermonuclear bomb. Her ability to program early computers opened the door for a collaboration with physicists Marshall Rosenbluth (her husband), Nicholas Metropolis, Edward Teller, and mathematician Augusta Teller. Together they came up with the Metropolis algorithm, a technique for generating random samplings that is a foundation of understanding large quantities of data.  

1955: Los Alamos scientists Enrico Fermi, John Pasta, and Stanislaw Ulam published “Studies of Nonlinear Problems,” which detailed the methods and results of a mathematical physics problem run on the MANIAC, the Laboratory’s first electronic computer. The problem, which launched the field of nonlinear science, was originally called the Fermi-Pasta-Ulam Problem, despite the fact that mathematician Mary Tsingou’s programming of the MANIAC was imperative to the work. In 2008, members of the physics community renamed it the Fermi Pasta-Ulam-Tsingou Problem to reflect Tsingou’s involvement.

1955: After working for the Manhattan Project in Hanford, Washington, nuclear physicist Jane Hamilton Hall joined the Laboratory in 1945. She and her husband, David, worked together on Clementine, the world’s first fast reactor. In 1955, she became the Lab’s first female assistant director, and in 1966, President Lyndon Johnson appointed her to the General Advisory Committee of the Atomic Energy Commission. For more on Jane Hall, see the October 2018 issue of this magazine or listen to the National Security Science podcast.

Julia Hardin

1963: Congress passed the Equal Pay Act, which promised equal pay for equal work, regardless of the race, color, religion, national origin, or sex of the worker. The Equal Pay Act was the first U.S. legislation targeted to eliminate gender-based pay inequities, thereby ushering in a new norm of gender equality in the workplace.

1964: African American biochemist Julia Hardin joined the Laboratory in 1964 to research and study mutations—genetic changes—that occur in DNA when it is exposed to radiation. “There was a big effort then to recruit blacks, and for the first time in my life it became obvious to me that I was a statistic,” she said in 1984. “I’ve probably been a statistic here in Los Alamos, but I’ve never felt like one. With a personality and attitude like mine, you overcome color and people become people.” Hardin later became the director of the Historically Black Colleges and Universities Education Program, and recruited many African American science and engineering students for summer internships at the Laboratory. 

1964: The Federal Civil Rights Act passed, including Title VII, which guaranteed equal opportunity (no discrimination) in employment. The Civil Rights Act also created the Equal Employment Opportunity Commission to enforce workplace equality.

1965: President Lyndon Johnson’s Executive Order 11246 prohibited sex discrimination by government contractors and required affirmative action plans for hiring women. The order also required contractors to “take affirmative action to ensure that applicants are employed, and that employees are treated during employment, without regard to their race, color, religion, sex or national origin.”

1967: President Lyndon Johnson issued Executive Order 11375, which expanded affirmative action policies to cover discrimination based on sex. As a result, federal agencies and contractors must take active measures to ensure that women, as well as minorities, have the same employment and educational opportunities as men.

woman in glasses
Darleane Hoffman Los Alamos National Laboratory


1973: August 26 became Women’s Equality Day. The date was selected to commemorate the 1920 certification of the 19th Amendment to the Constitution, which granted women the right to vote. The day recognizes women’s continuing efforts toward equal rights for all citizens.

1978: The Pregnancy Discrimination Act banned employment discrimination against pregnant women. The act also mandated that employers provide the same benefits to women at any stage of pregnancy, delivery, or recovery from delivery when they are medically unable to work as to all other employees with temporarily disabling conditions.

1979: Chemist Darleane Hoffman came to Los Alamos with her husband, a physicist, in 1953. “There is often some initial shock when I am introduced, and Dr. D.C. Hoffman turns out to be a woman,” she told The Atom magazine in 1974. “But so often, I think it is not so much discrimination as the bald fact that too many girls are trained from grade school in the belief that there are certain suitable occupations for women and that they should aspire no further. I think it is appropriate for girls to develop appropriate images so they don’t think of women scientists as freaks. You can follow a scientific career and still have a home and family.” In 1979, Hoffman became the first woman to lead a scientific division—the Chemistry and Nuclear Chemistry Division—and in 1993, while working Lawrence Berkeley National Laboratory, she helped confirm the existence of element 106, seaborgium. In 2014, she was honored with the Los Alamos Medal, the highest award given by the Laboratory.

Tinitia Oliver

1980: President Jimmy Carter designated March 2–8 as National Women’s History Week. “From the first settlers who came to our shores, from the first American Indian families who befriended them, men and women have worked together to build this nation,” Carter said in his message to the nation. “Too often the women were unsung and sometimes their contributions went unnoticed. But the achievements, leadership, courage, strength, and love of the women who built America was as vital as that of the men whose names we know so well.”

1987: Congress declared the entire month of March as National Women’s History Month. A special presidential proclamation is issued every March that honors the achievements of American women.

1987: Tinitia Oliver started at Los Alamos in 1987 as a radiation control technician and has since worked as a maintenance coordinator, team leader, and currently as a work execution manager. Oliver oversees seven craft superintendents, and together they manage the craft teams—carpenters, painters, electricians, pipefitters, mechanics, laborers, insulators, and sheet metal workers—who maintain Lab facilities.

Earle Marie Hanson
Glenn Seaborg and Earle Marie Hanson. Earle Marie Hanson


1993: The Family and Medical Leave Act (FMLA) went into effect for large employers, who must grant a maximum of 12 weeks of unpaid, job‑protected leave to expecting employees for the birth or adoption of a child. Not only did the FMLA Act protect women’s jobs should they decide to have a baby, it also left the FMLA open to men should they want to take leave or remain home to care for a spouse, child, or parent with a serious illness.

1995: Jill Trewhella was named the first female Laboratory Fellow in 1995 after coming to Los Alamos in 1984 to launch a biological neutron-scattering program. Fellows are limited to 2 percent of the Laboratory’s technical staff. Upon naming her leader of the Lab’s Bioscience Division in 2000, Lab Director John Browne said, “Jill is one of those unique scientists who come along only about once every decade, who combine their passion for science with their excellence in research and their leadership skills to make a true difference in an organization.” Other female Lab Fellows are Michelle Thomsen (1997), Merri Wood-Schultz (2001), Bette Korber (2002), Carol Burns (2003), Jane Nordholt (2006), Joyce Guzik (2006), Antoinette Taylor (2009), Brenda Dingus (2011), Cheryl Kuske (2013), Jaqueline Kiplinger (2014), Jennifer Hollingsworth (2016), Dana Dattelbaum (2019), Anna Hayes (2019), Laura Smilowitz (2019), and Vania Jordanova (2020).

1999: Earle Marie Hanson joined the Laboratory in 1976 after receiving a doctorate in chemistry from the Massachusetts Institute of Technology. She made many significant contributions to weapons engineering and, from 1999–2003, served as the first female division leader of an engineering division—the Engineering Science Applications Division—where she oversaw approximately 900 full-time employees.

Bette Korber

2003: Program manager Carolyn Mangeng studied energy and environmental assessments, military systems, and nuclear weapons before serving as deputy associate director of the Nuclear Weapons directorate from 2002–2003, during which time she had specific oversight of stockpile management activities. She became Los Alamos’ first female deputy Laboratory director (acting) in 2003 and worked as the deputy associate director for Environmental Programs before her retirement in 2006.

2004: Theoretical biologist and Laboratory Fellow Bette Korber has spent her career understanding viral evolution and vaccine design. In 2004, she received the E. O. Lawrence Award—the Department of Energy’s highest scientific honor—for her studies delineating the genetic characteristics of the human immunodeficiency virus. Several of her vaccine designs have shown significant promise in animal studies and are currently being evaluated in human clinical trials. In 2021, Korber was awarded the Los Alamos Medal, in part for her immediate and impactful response to the coronavirus pandemic. Korber and her team identified a mutated form of the virus that quickly became the dominant form worldwide.

2005: Biophysicist Karissa Sanbonmatsu is a transgender woman who researches how DNA is reprogrammed during life, how genes are switched on and off, and how gigantic RNA molecules affect the switches. In 2012, Sanbonmatsu and her team published the first structure of such a molecule. In 2005, Sanbonmatsu became the first woman at the Laboratory to receive the Presidential Early Career Award in Science and Engineering. The award, established by President Bill Clinton in 1996, is the highest honor bestowed by the United States government on science and engineering professionals in the early stages of their independent research careers. Additional winners from Los Alamos include: Jennifer Martinez (2007), Evgenya Simakov (2010), Amy Clarke (2011), and Abigail Hunter (2018).

2007: My Hang Huynh received an E. O. Lawrence Award from the Department of Energy for her exceptional work in chemistry. Huynh was also named a MacArthur Fellow for her development of novel techniques for synthesizing highly energetic compounds, such as explosives, that substitute benign elements for environmentally toxic heavy metals and improve the safety of workers and military personnel who handle these materials.

My Hang Huynh
My Hang Huynh Los Alamos National Laboratory


2010: The Affordable Health Care Act was signed into law. Under this law, private health insurance companies must provide birth control without co-pays or deductibles. The law also requires private insurance companies to cover preventive services.

2012: In 2012, Patti Buntain was named the first female manager of a life extension program (LEP) at Los Alamos. (LEPs address aging and performance issues in nuclear weapons; Buntain was involved with the B61 gravity bomb LEP.) Buntain earned a degree in mechanical engineering from the University of New Mexico and has held several positions in the Laboratory’s Weapons programs. In 2014, she received the Order of the Nucleus Award from the U.S. Air Force, which is given to individuals who have made a significant contribution to the Air Force nuclear enterprise.

2013: Chemistry Division Leader Carol Burns was named Deputy Principal Associate Director for the Science, Technology, and Engineering (STE) directorate. Today, Burns is the executive officer of the STE directorate. Burns was raised in Los Alamos and said her appreciation for “the eminent women we see throughout the history of Los Alamos” started with her schoolmates’ moms who were employed at the Lab.

2013: Physicist Susan Seestrom joined the Lab in 1986 as a nuclear physicist and eventually became the first woman leader of the Physics Division and the Weapons Physics directorate. In 2013, she was the first woman to become a Senior Fellow at the Laboratory. Seestrom is also the first (and only) woman to chair the Nuclear Science Advisory Committee for both the Department of Energy and the National Science Foundation.

2016: The Laboratory was named for the first of several times as a top-50 employer for Latina women by Latina Style magazine. “If you had told me as a young Hispanic girl growing up in Northern New Mexico that I would one day serve in an important role for a world-renowned institution in support of the national security mission, I would have thought it unattainable,” says Human Resource’s Leah Sanchez. “Los Alamos National Laboratory provided me that opportunity.” 

Carol Burns (left) and Carolyn Zerkle (center) joined other women ADs on a panel moderated by Director Charlie McMillan in September 2016. Los Alamos National Laboratory

2017: In an ongoing effort to support employee health and wellness, Mamava pods, which provide privacy for nursing mothers, were installed at locations across the Laborator y. Los Alamos was the first place in New Mexico to install a Mamava pod, which is essentially a prefabricated unit equipped with electrical outlets, USB ports, benches, tabletops, motion-activated lighting and vents. The Fair Labor Standards Act states that large employers are required to provide adequate time and space for nursing employees to express milk.

2018: A dedicated phone number was created to report sexual harassment at the Laboratory, and a Sexual Harassment Officer was appointed to facilitate the investigation process. Shortly after becoming Laboratory director, Terry Wallace reiterated the Laboratory’s zero-tolerance sexual harassment policy and encouraged anyone experiencing harassment in the workplace to speak up. “Under no circumstances should anyone be made to feel like they are at risk for reporting something that never should have happened in the first place,” he said.

2018: Carolyn Zerkle became the Laboratory’s executive director on January 1, 2018. Previously, Zerkle was the associate director for the Business Innovation directorate, a new organization at the Lab that combined business services and information technology to enhance efficiency and bolster quality and speed of service. “I really think we’re seeing this seismic shift—not only at the Laboratory, but throughout the country,” she says. “We’re seeing positions where, previously, women weren’t represented in any real way to seeing them in sizeable numbers and in positions of power and authority. It’s heartening to witness and is a trajectory that I think will continue.”

2018: As the Lab’s first female principal associate director, Nancy Jo Nicholas led Laboratory programs with a special focus on developing and applying the scientific and engineering capabilities to address complex national and global security threats. “I’m surrounded by strong, intelligent, and dedicated women at the Lab all the time,” she says. “To see women rise to leadership positions seems really natural to me, and I’m glad I can be part of it.” Nicholas is currently the associate Laboratory director for Global Security.

Frances Chadwick Los Alamos National Laboratory

2018: When Triad National Security, LLC, took over the Lab contract in November, Frances Chadwick became the Laboratory’s staff director. In this role, she manages the organizations that report to the director’s office—Legal, Communications and External Affairs, Audit and Ethics, Counterintelligence, and the Office of National Security and International Studies.

2018: Laboratory employees who become new mothers receive paid maternity leave. (Previously, they were required to use sick time and go on disability.)

2018: Los Alamos became the first national laboratory to join Gender Champions in Nuclear Policy, which brings together heads of organizations working in nuclear policy who are committed to breaking down gender barriers and making gender equality a working reality in their spheres of influence.

2019: The Director’s Diversity Council is formed. The council, which comprises the chairs from the Laboratory’s various employee resource groups (including Atomic Women and the Women’s Employee Resource Group), meets quarterly with senior leadership. “We try to make diversity part of how we manage the Lab,” Chadwick explains.

2019: Paid parental leave is now available to parents (women and men) when they have a baby or adopt a child. “Bringing a new child into your life is an important event,” said Laboratory Director Thom Mason. “Recognizing that you need time to bond with your new family member, I am pleased to introduce a new paid parental leave benefit. This valuable benefit is being introduced to help address the needs of our workforce and to make Los Alamos National Laboratory one of the best places to work.”

Dana Dattelbaum

2020: Human resources generalist Barbara Lynn was appointed to the Public Safety and Law Enforcement subcommittee of the New Mexico Governor’s Council for Racial Justice. The council was formed by New Mexico Governor Michelle Lujan Grisham to monitor state institutions and as they take action to end systemic racism, and to ensure that all people receive fair and equal treatment and opportunities. Lynn is a former director of the Office of Equal Opportunity Services at Los Alamos.

2021: The Laboratory enhanced its benefits program to cover preauthorized infertility treatments. “Employees have expressed interest in this benefit for years, and we are excited to now provide it with no significant impact to rates,” says Melinda Olswang, Human Resources Benefits group leader.

2021: In January, Dana Dattelbaum received an E. O. Lawrence Award for her contributions to the Department of Energy’s national security and nonproliferation missions. Dattelbaum was honored for her “transformative scientific and intellectual achievements,” including providing physical insights into shock and detonation physics, developing the equations of state of a spectrum of energetics and polymers, and providing critical data for hydrodynamic simulations essential to the nuclear weapons program.