An Experiment on Nuclear Alignment: the Anisotropy of γ-Radiation from Oriented Cobalt-60 Nuclei


RADIATIONS from radioactive nuclei oriented at random are isotropic; but if the nuclei are even partially aligned, an anisotropic distribution should in general be found provided I is greater than ½, as shown by Spiers1. In order to align nuclei, one makes use of the energy differences between the various orientations of the nuclear spin. By cooling to low enough temperatures, the lower levels will be preferentially populated, and in suitable systems this corresponds to a spatial alignment. In general, these energy differences are so small that temperatures obtainable only by adiabatic demagnetization must be used.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Spiers, J. A., Nature, 161, 807 (1948); Directional Effects in Radioactivity (National Research Council of Canada, Chalk River, 1949).

  2. 2

    For example, Simon, F. E., C.R. Cong. sur le Magnetisme, Strasbourg, 3, 1 (1939).

  3. 3

    Pound, R. V., Phys. Rev., 76, 1410 (1949).

  4. 4

    Gorter, C. J., Physica, 14, 504 (1948).

  5. 5

    Rose, M. E., Phys. Rev., 75, 213 (1949).

  6. 6

    Bleaney, B., Proc. Phys. Soc., A, 64, 315 (1951).

  7. 7

    Bleaney, B., Phil. Mag., 42, 441 (1951).

  8. 8

    Gorter, C. J., de Klerk, D., Poppema, O. J., Steenland, M. J., and de Vries, Hl., Physica, 15, 679 (1949).

  9. 9

    Benzie, R. J., and Cooke, A. H., Nature, 164, 837 (1949).

  10. 10

    Bowers, K. D., (unpublished).

  11. 11

    Steenberg, N. R., (unpublished).

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

DANIELS, J., GRACE, M. & ROBINSON, F. An Experiment on Nuclear Alignment: the Anisotropy of γ-Radiation from Oriented Cobalt-60 Nuclei. Nature 168, 780–781 (1951).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.