Alfred Otto Carl Nier (May 28, 1911 – May 16, 1994) was an American

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 cau ...

who pioneered the development of

mass spectrometry Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used ...

. He was the first to use mass spectrometry to isolate

uranium-235 Uranium-235 ( or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exists in nat ...

which was used to demonstrate that ²³⁵U could undergo fission and developed the sector mass spectrometer configuration now known as Nier-Johnson geometry.

Early life and education

He was born in

St. Paul, Minnesota Saint Paul (often abbreviated St. Paul) is the capital city of the U.S. state of Minnesota and the county seat of Ramsey County. As of the 2020 census, the city had a population of 311,527, making it Minnesota's second-most populous city a ...

on May 28, 1911. Nier showed an early ability in

mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...

and

science Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...

, coupled with an aptitude for craft and mechanical work. Nier's

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

immigrant Immigration is the international movement of people to a destination country of which they are not usual residents or where they do not possess nationality in order to settle as permanent residents. Commuters, tourists, and other short- ...

parents had little education or financial resources but their determination for his development meant that he was able to attend the nearby

University of Minnesota The University of Minnesota Twin Cities (historically known as University of Minnesota) is a public university, public Land-grant university, land-grant research university in the Minneapolis–Saint Paul, Twin Cities of Minneapolis and Saint ...

. Though he graduated in

electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems that use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the l ...

in 1931, the lack of engineering jobs during the

Great Depression The Great Depression was a severe global economic downturn from 1929 to 1939. The period was characterized by high rates of unemployment and poverty, drastic reductions in industrial production and international trade, and widespread bank and ...

encouraged him to take up graduate study in

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

Career

Harvard

In 1936, his spectroscopic skills won him a fellowship and substantial grant at

Harvard University Harvard University is a Private university, private Ivy League research university in Cambridge, Massachusetts, United States. Founded in 1636 and named for its first benefactor, the History of the Puritans in North America, Puritan clergyma ...

. His work there led to the 1938 publication of measurements of the relative abundance of the

isotope Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...

s of

uranium Uranium is a chemical element; it has chemical symbol, symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Ura ...

, measurements that were used by Fritz Houtermans and Arthur Holmes in the 1940s to estimate the age of the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

The Manhattan Project

Nier returned to Minnesota in 1938 to be near his ageing parents. In 1940, on the request of

Enrico Fermi Enrico Fermi (; 29 September 1901 – 28 November 1954) was an Italian and naturalized American physicist, renowned for being the creator of the world's first artificial nuclear reactor, the Chicago Pile-1, and a member of the Manhattan Project ...

, he and a few students, including Edward Ney, prepared a pure sample of

using an early mass spectrograph designed by Nier, for John R. Dunning's team at

Columbia University Columbia University in the City of New York, commonly referred to as Columbia University, is a Private university, private Ivy League research university in New York City. Established in 1754 as King's College on the grounds of Trinity Churc ...

. On the day of its receipt (it was sent by US Postal Mail), Dunning's team was able to demonstrate that uranium-235 was the

responsible for

nuclear fission Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactiv ...

, rather than the more abundant

uranium-238 Uranium-238 ( or U-238) is the most common isotope of uranium found in nature, with a relative abundance of 99%. Unlike uranium-235, it is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. However, it i ...

. Confirmation of this suspected fact was a critical step in the development of the

atomic bomb A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission or atomic bomb) or a combination of fission and fusion reactions (thermonuclear weapon), producing a nuclear expl ...

. From 1943 to 1945, Nier worked with

Kellex Corporation The Kellex Corporation was a wholly owned subsidiary of M. W. Kellogg Company. Kellex was formed in 1942 so that Kellogg's operations relating to the Manhattan Project could be kept separate and secret. "Kell" stood for "Kellogg" and "X" for sec ...

Manhattan, New York City Manhattan ( ) is the most densely populated and geographically smallest of the five boroughs of New York City. Coextensive with New York County, Manhattan is the smallest county by area in the U.S. state of New York. Located almost entire ...

on the design and development of efficient and effective mass spectrographs for use in the

Manhattan Project The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada. From 1942 to 1946, the ...

to build the atomic bomb in

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. During the war most of the spectrographs used for monitoring uranium separations were designed by Nier.

Later work

After the war, he returned to Minnesota where he worked on

geochronology Geochronology is the science of Chronological dating, determining the age of rock (geology), rocks, fossils, and sediments using signatures inherent in the rocks themselves. Absolute geochronology can be accomplished through radioactive isotopes, ...

, the upper

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

space science Space is a three-dimensional continuum containing positions and directions. In classical physics, physical space is often conceived in three linear dimensions. Modern physicists usually consider it, with time, to be part of a boundless ...

and

noble gas The noble gases (historically the inert gases, sometimes referred to as aerogens) are the members of Group (periodic table), group 18 of the periodic table: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn) and, in some ...

es. Nier designed the miniature mass spectrometers used by the Viking Landers to sample the atmosphere of Mars.

Death

Active to the end of his life, he died on May 16, 1994, two weeks after being paralysed in a motor accident.

Honors

Nier was a member of the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, NGO, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the ...

, the

American Philosophical Society The American Philosophical Society (APS) is an American scholarly organization and learned society founded in 1743 in Philadelphia that promotes knowledge in the humanities and natural sciences through research, professional meetings, publicat ...

, the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (The Academy) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and other ...

, and a foreign scientific member of the

Max Planck Society The Max Planck Society for the Advancement of Science (; abbreviated MPG) is a formally independent non-governmental and non-profit association of German research institutes. Founded in 1911 as the Kaiser Wilhelm Society, it was renamed to the M ...

. The Martian crater Nier and the mineral nierite (tiny

silicon nitride Silicon nitride is a chemical compound of the elements silicon and nitrogen. (''Trisilicon tetranitride'') is the most thermodynamically stable and commercially important of the silicon nitrides, and the term ″''Silicon nitride''″ commonly re ...

inclusions in

meteorite A meteorite is a rock (geology), rock that originated in outer space and has fallen to the surface of a planet or Natural satellite, moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical ...

s) were named after him. The

Nier Prize The Nier Prize is named after Alfred O. C. Nier. It is awarded annually by the Meteoritical Society The Meteoritical Society is a non-profit scholarly organization founded in 1933 to promote research and education in planetary science with emph ...

is awarded annually by the

Meteoritical Society The Meteoritical Society is a non-profit scholarly organization founded in 1933 to promote research and education in planetary science with emphasis on studies of meteorites and other extraterrestrial materials that further our understanding of th ...

and recognizes outstanding research in meteoritics and closely allied fields by young scientists.

References

External links

1965 Audio Interview with Alfred Nier by Stephane Groueff
Voices of the Manhattan Project
Annotated Bibliography for Alfred O.C. Nier from the Alsos Digital Library for Nuclear Issues
* * * * {{DEFAULTSORT:Nier, Alfred O. C. 1911 births 1994 deaths University of Minnesota College of Science and Engineering alumni Harvard Fellows Nier, Alfred, O. C. 20th-century American physicists Mass spectrometrists Fellows of the American Physical Society Members of the United States National Academy of Sciences Thomson Medal recipients Members of the Royal Swedish Academy of Sciences Recipients of the V. M. Goldschmidt Award Members of the American Philosophical Society