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quae
fallout pattern, activity characteristics, particle size, and radiochemical content of each,
Study was also made of the rate of fallout
during the first 6-+ hr following each shot.
Mike-shot samples of 0.54 sq in ranged from 109 to 1023
disintegrations/min, equivalent to as high as 2,750 c/sq ft.
The fallout
from Mike Shot continued for at least 6 hr within 15 mi of ground zero, but
was heaviest during the first 30 min after detonation.
shot decay slope was -2.1 for the period from Hy +
The average Mike-
190 hr to Hy + 500 hr.
More than 90% of all the Mike-shot fallout studies consisted of particles
less than ly in diameter, but about 94% of the radioactive particles studied
were larger than 10.
Less than 1% of all the solid particles counted by
light-microscope methods were radioactive, indicating that little respiratory
hazard existed.
’
Activities of the King-shot samples were lower by a factor of
103 to 109.
These activities ranged up to 9.2 x 107+
¢/sq ft.
The
average King-shot decay slope was -0.65 for the period R + 150 hr to 150
hr to By + 450 hr.
A preliminary report of this work appeared as CRLIR-ll2.
CRLR - 218
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A SIMPLIFIED PROCEDURE FOR REFILLING GEIGER-MUELLER TUBES.
Henry A. Garon, 11 June 1953.
UNCLASSIFIED
(U)
A relatively simple method has been devised for refilling
discarded Geiger-Mueller tubes and preparing them for re-use.
New tubes
have average lives of 107 counts and are relatively expensive as compared
with the refilled tubes which have life expectancies of between 1 x 108 and
5 x 108 counts.
The processes of mica-window replacement, tube evaucation and
refilling, and tube sealing and testing are described in detail.
The
mixture found to be optimum for tube wfilling is a 24 to 1 ratio of helium
gas to absolute ethyl alcohol vapor (total pressure within the tube:
25 em of Hg).
Refilled tubes with replaced mica windows were found to
operate satisfactorily at an altitude of 8,000 ft. Theoretically, such
tubes shculd perform satisfactorily up to 30,000 ft.