Progress of the Directional Survey of Cosmic-Ray Intensities and Its Application to the Analysis of the Primary Cosmic Radiation

Since the 1934 report, asymmetries have been studied by the coincidence counter method at several stations in Mexico and in Colorado so that the completed survey now includes data at high (4300 m), low (sea level) and intermediate elevations at the geomagnetic equator, in the intermediate latitudes $\lambda {29}^{\circ }$, and in the high latitude $\lambda {50}^{\circ }$ besides additional data at an intermediate elevation in latitude $\lambda {36}^{\circ }$. For the measurements an automatic multi-directional intensity comparator has been developed. Using the results of the theoretical investigations of Lemaitre, Vallarta and Bouckaert the measured asymmetries have been reduced to relative specific intensities (per unit range of $x$) of the unbalanced positive component and it is found that this varies with the atmospheric path length $h$ sec $z$, according to an exponential law. The observed intensities, taking account of absorption, have been used in conjunction with the results of LVB to compute the longitude and latitude effects to be expected from the positives alone. The latitude effect thus computed is greater than that observed between Peru and Panama but the computed longitude effect is, in general, too small. It is possible that the anomaly is to be explained by the departures of the horizontal intensity from the values which would pertain if the earth's field were accurately that of a simple doublet. The work has been done under grants from the Carnegie Institution of Washington, administered by its Cosmic-Ray Committee.