DETERMINATION OF THE BACKGROUND WHILE MEASURING ACTIVITIES OF THE ORDER OF 10$sup -11$ TO 10$sup -13$ CURIE

Journal Article · Thu Nov 01 04:00:00 EST 1962 · At. Energ. (USSR)

OSTI ID:4720450

Artem'ev, V V

Activity measurements must be occasionally carried out in presence of a background radiation with a higher value than the radiation under study. Such cases are encountered in geological prospecting, biological and medical experiments with isotopes having half life periods longer than 10 years, requiring instruments with sensisitivities exceeding the 10/sup -13/ to 10/sup - 14/ curie range. Measurement of activities from 10/sup -11/ to 10/sup -13/ curie with an error of less than 1% requires tens of hours during which the background may vary radically because of the variations of cosmic rays and solar flares. In radiochemical dating studies the background usually consists of a constant component due to natural radioactive materials such as KID, and decay products of the U and Th series, and of a variable component primarily controlled by the cosmic radiation. Multiple scattering and absorption events cause a spreading of the spectral lines in neighboring portions of the spectrum of the background radiation; the changes in the second component may be determined by decomposing the count rate. The method was used successfully in mass determinations of C/sup 14/ in geological and archeological samples. The C sample was used to prepare ethyl benzene in which scintillating compounds, such as 2,5 diphenyl oxazol and 1,4-STAdi2,5 phenyl oxazolyl! benzene were dissolved, measuring the activity by means of a scintillation counter and a photomultiplier. (TTT)

• Research Organization: Originating Research Org. not identified
• NSA Number: NSA-17-009209
• OSTI ID: 4720450
• Journal Information: At. Energ. (USSR), Journal Name: At. Energ. (USSR) Vol. Vol: 13
• Country of Publication: Country unknown/Code not available
• Language: Russian

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