Accession Number:

AD0435618

Title:

A SENSITIVE VIBRATION MAGNETOMETER,

Descriptive Note:

Corporate Author:

AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS

Personal Author(s):

Report Date:

1964-01-01

Pagination or Media Count:

29.0

Abstract:

A vibrating sample magnetometer capable of measuring magnetic moments as small as 2 x 10 -6th power emu that is, gauss-cm to the 3th power has been put into operation. The instrument is basically of the Foner type, consisting of a speaker-driven rod holding the sample at one end. For measurements between 4.2 and 77 K, the sample is located in the inner part of a double dewar system the signal coils are rigidly mounted and immersed in the liquid nitrogen of the outer dewar. By immersion of the coils in liquid nitrogen, the thermal noise voltage is reduced by a factor of seven below that at 300 K, and a sensitivity of 2x10 -6th power emu is therby achieved. For temperatures between 77 and 600 K, cryogenic coil techniques require an increase in sample to coil distance that more than offsets the improvement due to reduced thermal noise. Co achieve high sample temperatures and maintain the coils at as low a temperature and as close to the sample as possible, a lava coil holder is used in which pre-cooled gas can be passed around the coils. Samples are mounted on the ends of 1.55-mm diameter ceramic rods sample temperatures are measured by thermocouples located directly adjacent to the sample in the gas flow. For the temperature region from 77 to 600 K, the instrument sensitivity is reduced to 10 -to the -5th power emu. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE