Index of content:
Volume 15, Issue 5, May 1944
15(1944); http://dx.doi.org/10.1063/1.1770247View Description Hide Description
Two types of Geiger‐Müller counters which count the particles in a solid angle slightly less than 4π are described. The use of thin metal windows permits their use with low energy β‐particles. They are useful for small point sources or in determining the radioactivity of thin foils. Details of the construction are presented. A differential vacuum system for filling thin‐window 4π counters is described.
15(1944); http://dx.doi.org/10.1063/1.1770248View Description Hide Description
With only minor modifications, the direct‐fusion technique, as previously developed for emanation measurements, can also be employed to liberate helium from terrestrial materials. The rock gases are purified, and the helium is measured quantitatively with a sensitive McLeod gauge. In geological age studies of igneous rocks and ``non‐radioactive'' minerals, the helium contents ranged from 0.25×10−5 to 65×10−5 with modal and median values of 1.8×10−5 cc He (at 0°C and 76 cm Hg) per gram.
- LABORATORY AND SHOP NOTE
15(1944); http://dx.doi.org/10.1063/1.1770250View Description Hide Description