Data recorded in a world-wide investigation of relationships between the spatial distribution of cosmic ray intensity and the magnetic field of the earth have been compared with the predictions of geomagnetic theory. Measurementg obtained with a neutron monitor in the U.S. Navy Hydrographic Office Airborne Geomagnetic Survey-Project MAGNET are well organized in terms of new calculations of vertical threshold magnetic rigidities by Quenby and Wenk, who have taken into account the effects of the dipole and non-dipole parts of the field as well as the penumbral correction. Except for the observations over one region in the North Atlantic, a plot of nucleonic intensity versus threshold rigidity reveals that all the points fall within a narrow band,

Observations of the intensity of the nucleonic component have been obtained with an airborne neutron monitor aboard the U.S. Naval Oceanographic Of[ice Project Magnet aircrs/t in a worldwide survey extending from the equator to the north and south geomagnetic poles. The data were reduced to a standard pressure altitude (500 mm of Hg), and the effects of temporal variations were removed by a normalization procedure involving four groundbased neutron monitor stations distributed over a wide range of latitude. Representation of the results in the form of an isocosm map revealed general agreement with the Quenby and Wenk calculations of threshold rigidities. Discrepancies are attributable to the inexactness of the approximation adopted for taking into account the effects of the penumbra. The location of the cosmic-ray equator, determined at seven points, was in accordance with calculations using the sixth-order expansion of the geomagnetic potential. The variation in intensity along the equator was in agreement with earlier results obtained during a different phase of the solar cycle. Measurements in the arctic and antarctic regions reveal that, during a period of extreme solar cycle modulation, the intensities in the northern and southern polax caps were equal within less than 0.5%. The latitude dependence of the atmospheric attenuation length of the nucleonic component, L, was determined from observations of the dependence of intensity upon altitude. In the plateau region, the mean value of L was 136.1 ñ 0• g/cm •. L increased by about 11% over the range of threshold rigidity from 2.5 to 16 Gv. The absorption mean free path, X,, deduced from L, was 160 g/cm • in the plateau region. Calculations based on currently accepted models of nuclear collision and of the process of nucleon propagation through the atmosphere yielded a value for the interaction length, X•, of about 80 g/cm •. This increased to 85 g/cm • when the effects of charge exchange were considered.

The results given here were presented at Rehovoth 8 and support the accepted conclusion of full polarization. The method of double scattering previously described 11 is particularly suitable for comparing the degree of polarization of beta rays from different beta emitters. Because of the simplicity and the high degree of symmetry of the apparatus there is less opportunity for systematic errors than in other more complicated TABLE I. Experimental left-right asymmetries. Second scatterer Sn foil, 1.3 X10~3 cm Au foil, 1.3 X10-* cm Asymmetry observed with P 32 source (4.2±0.7)% (8.7±0.7)% Asymmetry observed with Au 198 source (5.9=b0.8)% (8.6=1=1.0)%methods. The beta rays are scattered first by a thick aluminum foil to change the longitudinal polarization to one with a substantial transverse component. The left-right asymmetry is then measured in a second scattering perpendicular to the plane of the first scattering. Foils of aluminum, tin, and gold were used for the second scatterer. Beta-ray energies were limited roughly to the region of 250 kev by a simple pulseheight discriminator. Measurements were made using sources of Au 198 and P 32 , the latter being known to have full polarization from previous results. 12 The magnitudes and the Z-dependences of the asymmetries are consistent with what is expected from polarized beta rays. Although the absolute magnitude of the polarization can be calculated from these data only after complicated corrections for experimental effects, the relative values of the asymmetries should give a reliable result for the relative polarization. These indicate that the degree of polarization is the same in Au 198 and P 32 . Thus, if the previous result of full polarization is accepted for P 32 , the same is true for Au 198 .

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the 325-kev state in V 51 , we find: (1) The E2-M1 mixing ratio of the 325-kev gamma ray of V 51 has the value 6(E2/M1) =+0.37±0.04; (2) a spin assignment of 7/2-is absolutely ruled out for this state; and (3) a lower limit of I /x I ^ 0.8 nm can be set for the magnetic moment of Cr 51 .The evidence which shows that Cr +++ does not go into lattice sites in CMN is derived from experiments in which we attempted to grow several percent chromium into cerium magnesium nitrate and lanthanum magnesium nitrate. In these experiments, the double nitrate crystals were grown from solutions containing relatively high concentrations of Cr +++ . The crystals obtained were analyzed spectroscopically for chromium with the result that portions of crystals that were cloudy and slightly blue contained small amounts (-0.1%) of chromium. However, those portions of crystals which were optically clear and colorless contained no detectable traces of chromium. We conclude that Cr +++ does not substitute in lattice positions, but is probably incorporated into the crystal in ''brine holes" as growth proceeds.Considerable development may be necessary This note constitutes a preliminary report of some results of an experiment conducted aboard the satellite Explorer VII (1959 Iota) to investigate possible time variations in the flux of heavy nuclei (Z ^ 6) in the primary cosmic radiation. In particular, a detailed analysis of data recorded during two different periods in the lifetime of the experiment has provided values of the exponent, y, in the integral magnetic rigidity spectrum expressed in the form: N(>pc/Ze) =k(pc/Ze)~y.(1)The energy spectra of the multiply-charged primary cosmic rays have previously been determined either by means of the latitude effect, or before this technique can be used to obtain reliable values of nuclear moments. It should be immediately useful, however, for investigating other nuclear properties. In particular, nuclei of elements in the 4d, 5d, and 5/ transition series should be within the scope of the method.We thank George Shalimoff for performing the analyses of the double nitrate crystals. Phys. Rev. 12£, 2108 (1960). 6 G. M. Temmer and N. P. Heydenburg, Phys. Rev. 104, 967 (1956). 7 A. W. Sunyar and M. Deutsch, private communication quoted by D. Strominger, J. M. Hollander, and G. To Seaborg, Revs. Modern Phys. 3C», 585 (1958).on the basis of observations at a single location. 1 The former method involves the comparison of flux measurements obtained at different times with nuclear emulsions or counter arrangements flown at several places. Uncertainties in the geomagnetic cutoff energies, 2 the possible effects of time variations, and various other considerations add to the scatter in the results arising solely from statistical fluctuations. Determinations based upon energy measurements on individual nuclei observed during a single balloon flight, while consistent with those utilizing the latitude effect, also display a considerable spread, and neither approach is particularly amenable to providing informa...