"Present difficulties in the theory of hyperfine structure", in Convegno di Fisica Nucleare.

GOUDSMIT, Samuel. "Present difficulties in the theory of hyperfine structure", in Convegno di Fisica Nucleare, Ottobre 1931,  Rome: Reale Academia d'Italia, 1932, with the Goudsmit on pp. 33-49 in the publication of 173, (1)pp. 10"x 7", Unopened. Original wrappers. There is some fair amount of dusting to the covers and some very minor chipping to the spine top and bottom; the binding is strong and the text is crisp. This is a solid VG copy. [++] Attendees to this conference were outstanding, including: Richardson, Millikan, Meitner, Stern, Debye, Compton, Curie, Anton, Brill, Fermi, and Goudsmit. [++] Pauli thought that his idea of the most elusive particle in existence the neutron/neutrino could not be detected; in this paper Goudsmit helped prove Pauli right on the neutrino and wrong on being-able-to-detect-it. According to Laurie Brown, Goldsmit said: "It was Maurice Goldhaber who some time ago pointed out that I was the first to put Pauli's idea on paper and in print"--Laurie Brown in "Physics Today", "The Idea of the Neutrino", 1978. The later-named "neutrino" would be detected by Reines and Cowan at the P Reactor at Savannah River on 14 June 1956, in one of the great experiments in 20th century physics.[++] At the request of Fermi, Goudsmit himself explains the background and Pauli's integral appearance at the meeting in Pasadena in 1931 on page 41 of this paper: "At a meeting at Pasadena in June 1931 [which G attended], Pauli expressed the idea that there might exist a third type of elementary particle besides protons and. electrons, namely "neutrons". ."  Pauli theorized that an undetected particle was carrying away the observed difference between the energy, momentum, and angular momentum of the initial and final particles [++] ("Pauli originally named his proposed light particle a neutron. When James Chadwick discovered a much more massive nuclear particle in 1932 and also named it a neutron, this left the two particles with the same name. Enrico Fermi, who developed the theory of beta decay, introduced the term neutrino in 1934.")--Science online, on the "neutrino."[++] Pauli did not publish on theory, though he did send a rather famous circular/letter to colleagues (addressing them as "dear radioactives" (!)): "But I don't feel secure enough to publish anything about this idea, so I first turn confidently to you, dear radioactives, with a question as to the situation concerning experimental proof of such a neutron, if it has something like about 10 times the penetrating capacity of a BETA-ray."[++] Goudsmit continues on page 41: "These neutrons should have an angular momentum ½ h/2pi and also a magnetic moment, but no charge. They are kept in the nucleus by magnetic forces and are emitted. together with BETA-rays in radioactive disintegration. This, according to Pauli, might remove present difficulties in nuclear structure and at the same time in the explanation of the BETA-ray spectrum, in which it seems that the law of conservation of energy is not fulfilled. If one would find experimentally that there is also no conservation of momentum, it would make it very probable that another particle is emitted at the same time with the BETA-particle. The mass of these neutrons has to be very much smaller than that of the proton, otherwise one would have detected the change in atomic weight after BETA-emission." [++] According to Laurie Brown, when Goudsmit was giving his paper and mentioned the word "neutron" Pauli who had been late in getting to the conference appeared for the first time in the lecture hall like "magic"! [++] Lastly, there is a GREAT group photo of the attendees as frontis.