Stuart Freedman
Stuart Jay Freedman | |
---|---|
Born | neutrino physics, nuclear physics, weak interaction physics | January 13, 1944
Institutions | Lawrence Berkeley National Laboratory, University of California, Berkeley |
Thesis | Experimental Test of Local Hidden-Variable Theories (1972) |
Doctoral advisor | Eugene Commins |
Stuart Jay Freedman (January 13, 1944 – November 10, 2012) was an American physicist, known for his experiment testing
He held positions at
Early life and education
Freedman was born in Los Angeles on 13 January 1944. He attended high school there before moving north to attend the University of California, Berkeley. After beginning studies as a theorist under Prof. Charles Zemach, he switched to experimental atomic physics under the guidance of Prof.
Career
Freedman's thesis experiment
From this auspicious start, Freedman carried out a series of experiments in atomic, nuclear, and particle physics testing the most fundamental theories and principles.
In a 1975 experiment with Frank Calaprice and collaborators,[6] Freedman studied the beta decay of polarized 19Ne, looking for the presence of second class weak currents, that is, currents forbidden by G-parity.
While the Higgs boson was ultimately discovered at CERN in 2012, the mass range for initial searches for the Higgs boson was completely unconstrained. A very light Higgs boson could be emitted by 4He in the 0+ excited state at 20 MeV and observed in its decay to e+e-. Freedman and collaborators found no such effect,[7] excluding Higgs masses between 3 and 14 MeV.
The ratio of the axial to vector coupling of the neutron in beta decay is a fundamental parameter and the measurement [8] of gA/gV=1.262±0.005 made at Grenoble in 1985 by Freedman and collaborators set a new standard for precision.
Freedman was known for the care he took in carrying out experiments and became an effective antidote for spectacular, improbable results. Reports of narrow lines in e+e- coincidences in heavy ion collisions prompted Freedman and collaborators to seek an observation of the effect. The result was entirely negative.[9]
Perhaps more dramatic were reports that there was a neutrino with mass 17 keV. The mixing of this neutrino with conventional massless or very light neutrinos would modify the beta-decay spectrum. Freedman's team found no such neutrino.[10] Moreover, the effectiveness of the technique was confirmed by adding some 14C whose decay would mimic that of the hypothesized heavy neutrino.
The discovery of neutrino oscillations and its implication that neutrinos are massive are among the most important advances in particle physics in the late twentieth century. The detailed evaluation of the
In memory of his contributions, the American Physical Society (APS) established an award in his name, the Stuart Jay Freedman Award in Experimental Nuclear Physics.[14] He was elected a Fellow of the APS in 1984 for "important studies of weak interactions phenomena in nuclei."[15]
References
- ^ "Stuart J. Freeman". American Institute of Physics.
- ^ inSPIRE
- ^ S.J. Freedman and J.F. Clauser, Phys. Rev. Lett. 28, 938 (1972)
- ^ J.F. Clauser; M.A. Horne; A. Shimony; R.A. Holt Phys. Rev. Lett., 23,880 (1969)
- ^ "Nobel Prize in Physics 2022" (PDF).
- ^ F.P. Calaprice et al., Phys. Rev. Lett., 35, 1566 (1975)
- ^ S.J. Freedman, et al., Phys. Rev. Lett., 52, 240 (1983)
- ^ P. Bopp et al.,Phys. Rev. Lett.56, 919 (1985)
- ^ T.F. Wang et al., Phys. Rev. C36, 2136 (1987).
- ^ J.L. Mortara et al., Phys. Rev. Lett., 70, 394 (1993).
- ^ KamLAND Collaboration, Phys. Rev. Lett.90, 021802 (2003)
- ^ KamLAND Collaboration, Phys. Rev. Lett.,94, 081801 (2005)
- ^ KamLAND Collaboration, Phys. Rev. Lett.,100, 221803 (2008)
- ^ "Stuart Jay Freedman Award in Experimental Nuclear Physics". Retrieved March 22, 2018.
- ^ "APS Fellow Archive". American Physical Society. (search on year 1984 and institution University of California, Berkeley)