Valentine L. Telegdi
Wolf Prize Laureate in Physics 1991
Valentine L. Telegdi
Affiliation at the time of the award:
Swiss Federal Institute of Technology (ETH), Switzerland
“for their separate seminal contributions to nuclear and particle physics, particularly those concerning the weak interactions involving leptons”.
Goldhaber’s and Telegdi’s studies in nuclear physics and the weak interactions are characterized by their incisive quality as well as the elegance of their conceptual formulation and execution.
Valentine Telegdi began his research in the field of photo-excitation and disintegration of light nuclei but later centered his experimental studies on the physics of the muons.
(1) He demonstrated parity violation in the decay sequence
π+→ μ+ + vμ , μ+ → e+ + ve + ve
in nuclear emulsions and was well on his way to a definitive result when Wu, Ambler et al. announced their results for parity violation in beta decay in 1957.
(2) Hi s extensive work on muon capture by nuclei determined the form of the weak interaction in considerable detail.
(3) In 1981 he achieved a long held ambition to accurately measure the helicity of the muon-neutrino in the reaction
µ¯ + 12C → 12B + vμ
the muonic analog of the Goldhaber, Srodzins and Sunyar experiment described earlier.
Through this experiment together with those included under
(4) he demonstrated the universal character of the weak interactions; namely that the interactions describing
µ¯ + p → n + vμ
e¯ + p → n + ve
have the same form.
(5) He studied the atom, “muonium” and measured its hyperfine structure with a precision sufficient to determine the fine structure constant
α( = e2 / hc )
comparable with its determination from other independent studies.
(6) He introduced a new method for the determination of the magnetic moment of the muon by obtaining by direct experiment the value of g – 2 for the muon. With others he used this method to obtain the muon magnetic moment to an accuracy of 10-5 .
He is well known for his elegant experiments on neutral kaons which tested our understanding of the mixing between the Ko and Ko states of opposite strangeness in the physically observed short lived KoS and long lived KoL, states.
(7) He was the first to observe in 1958 that a long lived beam having positive strangeness at the source produced absorptive reactions characteristic of negative strangeness in nuclear emulsions, providing direct qualitative evidence for the mixed-strangeness property of KoL.
(8) In another remarkable experiment he observed the KoL → KoS regeneration by electrons which yielded a mean electromagnetic radius for neutral kaons.
(9) Finally we select from his many experiments involving nuclear beta decay those from which he derived an upper limit on the magnitude of the second class beta ray interaction current.