Mottelson (Mottelson), Benjamin R.( The American-Danish physicist, Nobel Prize in Physics, 1975)
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Biography Mottelson (Mottelson), Benjamin R.
genus. July 9, 1926
American-Danish physicist Benjamin Roy Mottelson was born in Chicago in a family Goodman Mottelson, engineer, and Georgia (nee Bloom), Ben Mottelson. The second of three children, a boy growing up in a lively intellectual atmosphere of the family. He went to school in La Grange (Illinois) and finished it during the Second World War. Being assigned to the Navy, he went through officer training at Purdue University, to which, and returned after the war. Being bachelor in 1947, he enrolled at Harvard University, where he completed dissertation work in physics under the leadership of Julius C. Schwinger, and in 1950, Mr.. received his doctorate.
In the same year, Harvard has awarded M. fellowships for travel abroad, which enabled him to conduct research at the Institute for Theoretical Physics in Copenhagen. He continued his work in this institute in future, getting a scholarship at the beginning of the Atomic Energy Commission, the U.S., and then from CERN (European Organization for Nuclear Research). In 1957, since the founding Nordic Institute for Theoretical Atomic Physics (Nordita) in Copenhagen, he became a professor there, and in 1981. Aage Bohr was replaced as director of Nordita.
Since the beginning of work at the Institute for Theoretical Physics, M. worked closely with Aage Bohr in the development problems of nuclear theory. Bohr (one of six sons Niels Bohr) shortly before he returned from Columbia University, where he worked with James Rainwater. The latter had already made a significant contribution to the theory of the structure of atomic nuclei, with many of the problems he had discussed extensively with Bohr. Using new ideas. Bohr and M. developed a comprehensive theory of behavior of the kernel, which they called the collective model.
. At that time, scientists have tried to explain the behavior of large numbers of protons and neutrons (collectively known as nucleons) in a large nucleus with the help of two theoretical models according to the droplet model, . proposed by Niels Bohr in 1936, . nucleus is much like a drop of liquid, . that fluctuates and alters the shape,
. Trickle model can explain the division of the nucleus, but also lead to impotence in explaining its other properties. According to the shell model, proposed in 1949. Maria Goeppert-Mayer, and I. Hans D. Jensen, it is assumed that the nucleons move inside the nucleus to the independent concentric orbits, or shells, in many ways similar to how electrons move in an atom. According to their theory, the force acting on one nucleon, the sum of the forces generated by all the nucleons of the nucleus. Goeppert-Mayer and Jensen put forward the hypothesis that the field of the collective strength of the spherically symmetric. However, experimental data have shown that the distribution of electrical charge of some of the nuclei has a spherical configuration, which it would have to be under the shell model.
. Rainwater had the idea that centrifugal force could cause deformation of the orbits, so that the entire configuration would take dyneobraznuyu form, he published the idea in 1950, Mr.
. Hypothesis Rainwater is well aligned with those things over which thought Aage Bohr, and on their return to Copenhagen at the end of that year, Bohr began to develop a substantive theory of behavior of the kernel. Two years later he published together with M. joint model of the nucleus, based on the idea Rainwater. This model was the synthesis of liquid-like behavior of the kernel, described droplet model, and orbitalnonuklonnyh properties inherent in the shell model.
. According to the model of Bohr - Mottelson, the combined effect of nucleons leads to the fact that the surface of the nucleus behaves like the surface of a liquid drop
. At the same time, the orbital structure of the nucleus may be deformed, which leads to vibrations and rotations of the surface. If the outer envelope of the nucleus has a complete set of nucleons, according to Bohr and M., the nucleus has a spherical shape, when the outer shell is not filled, the kernel takes the form dyneobraznuyu. They found that deformed nuclei have a number of new modes of vibration and rotation, including surface waves and fashion 'breathing', under which the oscillations of the size of the nucleus. Previous models have failed to predict these phenomena, because they do not take into account the interaction between the nucleons.
The collective model of Bohr and allowed M. predict the properties of deformed nuclei and confirm these predictions experimentally. When the same experiments done by other physicists, have also confirmed their theory, the two scientists reported their findings in 1953. Following the publication of the collective model M. Bohr continued to further develop its nuclear theory.
In 1975. M. shared the Nobel Prize in physics with Bohr and James Rainwater "for the discovery of the relationship between collective motion and the motion of a particle in atomic nuclei and the establishment on the basis of this connection, the theory of the structure of atomic nuclei '. Advanced the theory of the collective, said at the presentation of the winners, Sven Johansson, a member of the Royal Swedish Academy of Sciences, M. Bohr 'gave new impetus to theoretical studies, but, most importantly, they have facilitated numerous experiments to test their theoretical predictions'. The result, said Johansson was the 'in-depth understanding of nuclear structure. For example, they showed ... that the nucleons tend to form pairs. As a consequence, nuclear matter has properties resembling the properties of superconductors. "
In 1948, Mr.. M. married Nancy Jane Reno, have three children. In 1971, Mr.. they took Danish citizenship. Wife M. died of cancer in 1975, shortly before M. was awarded the Nobel Prize. Known as a man of exceptional intelligence and ability, M. in his spare time rides a bike, swimming and music, but most of his life he devoted reflections on the atomic nucleus and its behavior.
In addition to the Nobel Prize, M. has an honorary degree from Purdue University and the University of Heidelberg.