Neutron spectrometry

AUG 01, 1967

If you count particles as a function of energy, your methods, instruments and purposes can differ greatly depending on whether you are looking for emissions, absorptions or scatterings. Neutron counting started with Chadwick and has become a variegated science.

DOI: 10.1063/1.3034425

Lawrence Cranberg

PROBLEMS OF SPECTROMETRY are by definition those of plotting particles of diverse energies in a two‐dimensional array that shows numbers of particles as a function of energy. The prototype was discovered and solved in the 17th century by Isaac Newton when he accomplished the decomposition of white light into a spectrum with a refracting prism. The 19th century brought extension of the problem to electrically charged particles, and it was solved by exploiting the energy and momentum dependence of charged‐particle motions in electric and magnetic fields. James Chadwick’s discovery of the neutron in 1932 presented the problem in still another form, in which the particles are, like photons, electrically neutral, but, unlike photons, they interact only with the nuclear constituents of matter. It is not surprising, therefore, that the problems of neutron spectrometry exhibit distinctive peculiarities and difficulties. Let us discuss some aspects of the problem as seen from the perspective of recent developments.

This article is only available in PDF format

References

1. J. Chadwick, Nature 129, 312 (1932).https://doi.org/NATUAS
2. J. R. Risser, J. E. Price, C. M. Class, Phys. Rev. 105, 1288 (1957).https://doi.org/PHRVAO
3. J. R. Dunning, G. B. Pegram, G. A. Fink, D. P. Mitchell, E. Segrè, Phys. Rev. 48, 704 (1935); https://doi.org/PHRVAO
L. W. Alvarez, Phys. Rev. 54, 609 (1938).https://doi.org/PHRVAO
4. B. Jennings, J. Weddell, I. Alexeff, R. L. Hellens, Phys. Rev. 98, 582 (1955).https://doi.org/PHRVAO
5. A. Langsdorf, “Neutron Collimation and Shielding for Experimental Purposes,” Chap. IVE in Fast Neutron Physics (J. B. Marion, J. L. Fowler, eds.) Interscience, New York (1960).
6. G. K. O’Neill, Phys. Rev. 95, 1235 (1954).https://doi.org/PHRVAO
7. L. Cranberg, “Neutrons from the Li7(p,n)Be7 Reaction,” Los Alamos Scientific Laboratory Report LA‐1654 (1954).
8. L. Cranberg, p. 43 in Proceedings of the First International Conference on the Peaceful Uses of Atomic Energy, Vol. 4, United Nations, New York (1956).
9. R. C. Mobley, Phys. Rev. 88, 360 (1952). https://doi.org/PHRVAO
R. J. Van de Graaff, paper presented at the Denver meeting of American Physical Society, June 30, 1952;
L. Cranberg, R. A. Fernald, S. Hahn, E. F. Shrader, Nucl. Inst. and Meth. 12, 335 (1961).https://doi.org/NUIMAL
10. J. Kjellman, A. Nilsson, Nucl. Phys. 32, 177 (1962).https://doi.org/NUPHA7
11. L. Cranberg, C. D. Zafiratos, T. A. Oliphant, J. S. Levin, Phys. Rev. in press.

More about the authors

Lawrence Cranberg, University of Virginia.