Patrick Sandars

Patrick George Henry Sandars , also Pat Sandars , often cited PGH Sandars , (born March 29, 1935 in London , † April 26, 2013 ) was a British physicist who dealt with experimental atomic physics.

Life

Sandars grew up in Oxted , Surrey and attended Wellington College in Berkshire. From 1953 he studied physics in Oxford (Balliol College). In 1959 he was at the University of California, Berkeley before returning to Oxford.

From 1963 to 1977 he was a Fellow of Balliol College in Oxford and, from 1978 to his retirement in 1999, Professor of Experimental Physics at the Clarendon Laboratory . He was also Vice Chancellor of the General Board of Faculties at Oxford.

Sandars was Stephen Hawking's tutor at Oxford.

plant

He undertook laser spectroscopy experiments to observe effects from nuclear physics and elementary particle physics (parity violation) in atomic physics. His atomic physical measurements of parity violation became known in the late 1970s. Polarized laser light was sent through a gas made of ionized bismuth atoms and the rotation of the plane of polarization was measured (due to the parity-violating effect of the weak interaction, a small rotation of around radians was expected). The influence of the weak interaction, which causes the parity violation, was made possible by the fact that the electrons are temporarily also in the nucleus, where they interact with the nucleons via neutral currents (exchange of a Z boson) (the probability of being in the nucleus increases with heavier elements increased, but the calculation was also more difficult). A similar experiment was done in Seattle, and in 1976 both groups published their negative result (they did not find any rotation as predicted by the Salam-Weinberg model). However, the possibility remained that errors were made in the underlying assumptions and calculations (including those relating to the atomic wave functions) that predicted the magnitude of the rotation. On the part of the high-energy physicists, however, a parity violation according to the Salam-Weinberg theory of the electroweak interaction through neutral currents was confirmed in neutrino scattering experiments at Fermilab (HPWF collaboration) in 1976. In 1977 Sandars again presented the results of the experiments that were carried out, which contradicted the Salam-Weinberg theory, so that a modification of the Salam-Weinberg theory was also considered by the particle physicists. In 1978, the Salam-Weinberg model was confirmed by a high-energy scattering experiment of polarized electrons on nucleons (E122, a collaboration between SLAC and Yale University under Charles Prescott ). Simultaneously in 1978 a Soviet physicist group in Novosibirsk around LM Barkov repeated the atomic physics experiments and found a rotation after the prediction of the Salam-Weinberg model (without any details being known in the West). ${\displaystyle 1{,}5\cdot 10^{-7}}$

Confirmation of the parity violation according to the standard model in atomic physics followed a little later, by Steven Chu (1979) on thallium and in 1982 by Marie-Anne Bouchiat on cesium. In 1987 Sandars and colleagues confirmed the parity violation in his bismuth experiment (rotation of the polarization plane) and in 1991 in thallium.

Since the 1960s he has been looking for permanent electrical dipole moments of elementary particles in atomic physics that would violate time-reversal invariance (see electrical dipole moment of the neutron ). No such has been found to date.

Fonts

• The electrical dipole moment of an atom, Phys. Lett., Vol. 14, 1965, p. 194
• Enhancement factor for the electric dipole moment of the valence electron in an alkali atom, Phys. Lett., Vol. 22, 1966, p. 290
• The Search for Violation of P or T Invariance in Atoms or Molecules, in GW Putlitz, EW Weber, A. Winnacker, Atomic Physics 4, Plenum Press 1975, pp. 71-92
• What can we learn about Elementary Particles from Atomic Physics?, Physikalische Blätter, Volume 32, December 1976, pp. 663-669 (plenary lecture at the DPG conference), online
• with PEG Baird, MWSM Brincombe, GJ Roberts, DC Soreide, EN Fortson, LL Lewis, EG Lindahl: Search for parity non-conserving optical rotation in atomic bismuth, Nature, Volume 264, 1976, pp. 528-529
• with MWSM Brincombe, CE Loving: Calculation of parity non-conserving optical rotation in atomic bismuth, Phys. Lett. B, Volume 9, 1976, L 237-L240
• Relativistic many-body perturbation theory of parity non-conservation in heavy atoms, J. of Physics B, Volume 10, 1977, p. 2983
• with PEG Baird, SM Brimicombe, RG Hunt, GJ Roberts, DN Stacey: Search for parity noncoserving optical rotation in atomic bismuth, Phys. Rev. Lett., Vol. 39, 1977, pp. 798-801
• with DW Rein, RA Hegstrom: Parity Nonconserving Energy Difference Between Mirror Image Molecules, Phys. Lett. A, Vol. 71, 1979, pp. 499-502
• Parity Non-Conservation in Atoms and Molecules, in: Exotic Atoms 79, Fundamental Interactions and Structure of Matter, Ettore Majorana International Science Series, 4, 1980, pp. 57-76
• Many Body Aspects of Parity Non-conservation in Heavy Atoms, Physica Scripta, Volume 21, 1980, p. 284
• The Atomic theory of P and T violation, in: Seattle 1984 Proc. Atomic Physics, pp. 225-245
• Parity and time-reversal violation in atoms and molecules, Physica Scripta, Volume 36, 1987, pp. 904-910
• P and / or T violation, Physica Scripta, T 46, 1993, p. 16
• Electric dipole moments of charged particles, Contemporary Physics, Volume 42, 2001, pp. 97-111
• with Norval Fortson, Stephen Barr: The search for a permanent electric dipole moment, Physics Today, June 2003

Web links

• Obituary in Oxford Mail

Individual evidence

1. ↑ This important finding came from Marie-Anne Bouchiat and Claude Bouchiat in 1974
2. ^ Andrew Pickering, Constructing quarks, a sociological history of particle physics, University of Chicago Press 1986, p. 296ff
3. ↑ MJ Macpherson, Sandars u. a., Parity-Nonconserving Optical Rotation at 876 nm in Bismuth, Europhys. Lett., Vol. 4, 1987, pp. 811-816