The Physics Prize Committee has unanimously selected the following two candidates to equally share the Wolf Prize for 1991:
Maurice Goldhaber
Brookhaven National Laboratory
New York, N.Y., U.S.A.
Valentine L. Telegdi
Swiss Federal Institute of Technology (ETH)
Zurich, 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.
Among Professor Maurice Goldhaber’s investigations we especially mention: (1) the photodisintegration of the deuteron with Chadwick (1935), (2) the dipole vibrations of the nucleus with Teller (1948) which explained the giant electric dipole resonances in nuclei and which was the first of a number of collective motions of the nucleus which have been subsequently observed, (3) the classification of nuclear isomers and their elucidation via the shell model (1951), (4) the measurement of the helicity of the electron neutrino with Grodzins and Sunyar (1958) emitted in K capture leading to the formation of an excited state of 152Sm which decays electromagnetically to its ground state and (5) he entertained the possibility in 1978 - 1979 that the proton may decay with a very long lifetime and became a driving force in the attempt to observe it experimentally.
Each of these examples has been of great importance to the development of nuclear and weak interaction physics. The measurement of the helicity of the neutrino demonstrated unequivocally the nature of the weak interactions in nuclei. It was a particularly beautiful experiment as it directly connected the helicity of the neutrino with the observable helicity of the photon emitted in the decay of the excited state of 152Sm.
Goldhaber has always had an active interest in the status of the symmetries and selection rules of the fundamental interactions. An example is the proton decay experiment. As of 1989, this study showed that the decay rate was less than 10 -33/proton years. This research result excluded a number of 'Grand Unified Theories', which proposed to unify the quark and lepton degrees of freedom.
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 (2) he demonstrated the universal character of the weak interactions; namely that the interactions describing
µ¯ + p → n + vμ
and
e¯ + p → n + ve
have the same form.
(4) 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. (5) 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. (6) 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. (7) In another remarkable experiment he observed the KoL → KoS regeneration by electrons which yielded a mean electromagnetic radius for neutral kaons.
(8) 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.