Gerald Gabrielse is an
American physicist. He is the Board of Trustees Professor of Physics and director of the Center for Fundamental Physics at
Northwestern University, and Emeritus George Vasmer Leverett Professor of Physics at
Harvard University. He is primarily known for his experiments
trapping and investigating
antimatter, measuring the electron
g-factor,[1] and measuring the
electron electric dipole moment.[2] He has been described as "a leader in super-precise measurements of fundamental particles and the study of anti-matter."[3]
Gabrielse was a pioneer in the field of low energy
antiproton and
antihydrogen physics by proposing the trapping of antiprotons from a
storage ring, cooling them in collisions with trapped electrons,[8] and the use of these to form low energy antihydrogen atoms.[9] He led the TRAP team that realized the first antiproton trapping,[10] the first electron cooling of trapped antiprotons, and the accumulation of antiprotons in a 4 Kelvin apparatus.[11] The demonstrations and methods made possible an effort that grew to involve 4 international collaborations of physicists working at CERN's
Antiproton Decelerator. In 1999, Gabrielse's TRAP team made the most precise test of the
Standard Model's fundamental
CPT theorem by comparing the
charge-to-mass ratio of a single trapped antiproton with that of a
proton to a precision of 9 parts in 1011.[12] The precision of the resulting confirmation of the Standard Model prediction exceeded that of earlier comparisons by nearly a factor of 106.
Gabrielse now leads the
ATRAP team at
CERN, one of the two teams that first produced slow antihydrogen atoms and suspended them in a
magnetic trap.[13][14] Both TRAP and ATRAP teams used trapped antiprotons within a nested
Penning trap device to produce antihydrogen atoms slow enough to be trapped in a magnetic trap. The team made the first one-particle comparison of the magnetic moments of a single proton and a single antiproton.[15][16] Their comparison, to a precision of 5 parts per million, was 680 times more precision than previous measurements.[17]
Precision measurement
Gabrielse's group has been known to perform the most precise measurements of the
electron magnetic moment by using a single trapped electron. These measurements are the most precise measurements of any single particle and are among the most stringent tests of the
Standard Model.[18] Using the theory of
quantum electrodynamics, a measurement of the electron magnetic moment can also be interpreted as a measurement of the
fine structure constant.[19] In 2006, the group made its first measurement with an uncertainty of 0.76 parts per trillion,[20] which was 15 times more precise than a measurement that had stood for about 20 years.[21] This measurement was improved two years later by a factor of 2.[22] In 2023, the team improved upon the 2008 uncertainty by another factor of 2.[1]
In 2014, Gabrielse, as part of the ACME collaboration with
John Doyle at Harvard and
David DeMille at
Yale, measured the
electron electric dipole moment to over an order of magnitude over the previous measurement using a beam of
thorium monoxide,[23] a result which had implications for the viability of
supersymmetry.[24] In 2018, the ACME collaboration improved upon this upper limit by another order of magnitude.[25]
Other research contributions
Gabrielse was also one of the discoverers of the Brown-Gabrielse invariance theorem,[26] relating the free space cyclotron frequency to the measureable eigenfrequencies of an imperfect Penning trap. The theorem's applications include precise measurements of magnetic moments and precise
mass spectrometry.[27] It also makes
sideband mass spectrometry possible, a standard tool of nuclear physics.[28]
Gabrielse has also invented a self-shielding
superconductingsolenoid that uses flux conservation and a carefully chosen geometry of coupled coils to cancel strong field fluctuations due to external sources. The device was responsible for the success of the precise comparison of antiproton and proton, and also enables
magnetic resonance imaging (MRI) systems to locate changing magnetic fields from external sources, such as elevators.[29]
Religious views
Gabrielse identifies himself as a scientist who is
Reformed Christian. In an interview, he said:
I do not believe that science and the Bible are in conflict. However, it is possible to misunderstand the Bible and to misunderstand science. It is important to figure out what of each might be misunderstood.[30]
He has also delivered lectures on the relation between science and religion. In 2006 Gabrielse delivered a lecture titled "God of Antimatter" in the
Faraday Institute for Science and Religion in
Emmanuel College, Cambridge, discussing his research into antimatter as well as his personal experience with Christianity.[31] He was awarded the
Trotter Prize in 2013.[32]
Trivia
On an episode of
Late Night with Conan O'Brien that aired on February 21, 2007,
Jim Carrey and
Conan O'Brien humorously discussed content from a paper entitled, "Stochastic Phase-Switching of a Parametrically-Driven Electron in a Penning Trap".[33] Gerald Gabrielse said that it was 'perhaps the most obscure paper I've ever written'.[34]
Working at CERN, Gabrielse trapped the first antiprotons in 1986.
Dan Brown's subsequent novel Angels & Demons, and
the movie made from it, use antimatter trapped at CERN as an important plot point.[35]
^Brown, Lowell S.; Gabrielse, Gerald (1982-04-01). "Precision spectroscopy of a charged particle in an imperfect Penning trap". Physical Review A. 25 (4): 2423–2425.
Bibcode:
1982PhRvA..25.2423B.
doi:
10.1103/PhysRevA.25.2423.
^Gabrielse, G. (2009-01-15). "The true cyclotron frequency for particles and ions in a Penning trap". International Journal of Mass Spectrometry. 279 (2–3): 107–112.
Bibcode:
2009IJMSp.279..107G.
doi:
10.1016/j.ijms.2008.10.015.