James R. Arnold

The Existence of Multiply Charged Molecular Ions of HBr, HCl, and DCl

Experimental evidence is presented for the DCl+1, HCl+1, DCl+2, and HBr+2 molecular ions, using a modified Consolidated‐Nier mass spectrometer. Although Cl+3, Br+3, and A+3 were observed, no evidence was obtained for H1,2Cl+Z, or HBr+Z above Z=2. This result contradicts the recent calculations of Magee and Gurnee2 that HBr+3 and HBr+4 would be stable toward dissociation. Finally a crude calculation is done assuming hydrogen 1s atomic orbitals which agrees amusingly with the experiments.

Radioactive Fall-out

Believing that the government has to conduct a most carefully planned and thoroughly implemented program of nuclear education on the facts of survival, Dr. Lapp continues his analysis of the hazard of radioactive fall-out. He plans to discuss the military implications in a coming issue.

THE HYDROGEN-COBALT BOMB

Is it technically feasible to construct a weapon which could disperse lethal radioactive dust over the face of the earth? Dr. Szilards assertions that the hydrogen bomb could be rigged to produce this effect were made over a University of Chicago Round Table broadcast in February and reprinted in the April 1950 Bulletin. Similar statements were made by Dr. Einstein and Dr. Harrison Brown. In this article, Dr. Arnold, a research associate and member of the teaching staff at the Institute for Nuclear Studies, University of Chicago, examines Dr. Szilards calculations.

The Scintillation Counter. I. The Existence of Plateaus

A method has been developed whereby inorganic phosphors can be mounted on a photo‐multiplier tube in thin films. The ZnS:Ag phosphor is quite satisfactory for use in conjunction with the 931A photo‐tube. Plateaus have been established similar to those associated with Geiger‐Muller counter tubes and the associated circuits.

The Chemist's Moon.

During the Apollo exploration program, chemical mapping of about 20 per cent of the Moon was done from lunar orbit by means of instrumentation on the Apollo Command Module, which remained in orbit while two of the crewmen were on the lunar surface. Important clues to the origin and evolution of the Moon have been found from these orbital observations, but a great deal more remains to be done in mapping the 80 per cent of the Moons surface that Apollo did not cover. Even so, remarks the author, “we lunatics have found the last few years more rewarding than even we had imagined.” Dr. Arnold is professor of chemistry at the University of California, San Diego.

Tracing Nuclear Explosions

The ways in which explosions are identified are largely a matter of secret information. However, we offer the following article as a partial illustration of how convincing the available data can be. We are grateful to the editors of Nucleonics for permission to use the figures and make a summary-review of this article, which appeared in the August 1952 issue of that journal.