DECAY OF POTASSIUM BY K-CAPTURE

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000600340270-4
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 3
• Document Creation Date: December 22, 2016
• Document Release Date: August 16, 2011
• Sequence Number: 270
• Publication Date: September 5, 1950
• Content Type: REPORT

Sanitized Copy Approved for Release 2011/08/17: CIA-RDP80-00809A000600340270-4
CLASSIFICATION CONFIDENTIAL CUFF"
INFORMATION FROM.
Sanitized Copy Approved for Release 2011/08/17: CIA-RDP80-00809A000600340270-4
COUNTRY USSR DATE OF
INFORMATION 1948
SUBJECT Scientific - Physics, transmutation of
potassium to argon
HOW DATE DIST. ,S' Sep 1950
WHERE
PUBLISHED Moscow NO. OF PAGES 3
DATE
PUBLISHED Mar/Apr 1949
SUPPLEMENT TO
LANGUAGE Russian REPORT NO.
Ttl1I YOCY'MINT COITAlII INFORMATION "FICTION 719 NATIONAL MITI $9
or no tltllus ITATII 017110 no Mumps, or IIPIOMOI ACT IS
U. I. C.. R 1 M1 RR, Ao AIOIIU. III YIANI01U100 CI TYY OIVILAT1OI
Or ID CTNT0011 IN ANY NARROW TO Al YNAtlTNORIRto P11101 to PRO?
IIIITIo MY AS. r ?NOOUCTiOM OF TO YORO IS PR01I11Tt0.
Izves
19 9
CENTRAL INTELLIGENCE AGENCY, REPORT
Digest)
Comparing the energetic aspects of various types of transitions, G. S. Si-
soo (1) arrived at the conclusion that if the mic??.le member of a group of three
isobars of the type,ZA, (Z +.1)A, and (Z + 2)A is radioactive and decays under
electron emission, it almost invariably may also be expected to decay under K-
capture. ff this were not the case, the isobar ZA could undergo transformation
by beta-decay into the middle isobar (Z + 1) and would not exist as a stable
atom (2).
Among naturally occurring elements, the isobars A4, K , andCa12~00 comply
with Siaoo's conditions. K40 is radioactive and decays with the emission of a
beta particlg. According to Sisoo's rule, decay of KL~Lnn9~ by K-capture under for-
mation of A.0 ought to be expected. This is confirmed"by the diagram plotting
the logarithms of Clarke numbers flarke number indicates in %reight percent
the relative occurrence of any element on earth] expressing the occurrence of
noble gases. While the values for all other noble gases fit into a curve that
is parallel to the basic band containing the majority of elements which com-
pose the earth's crust, the point representing argon is approximately three
times higher than the rest of the curve. This indicates the presence of a con-
-stgat source of argon formation somewhere in the earth's crust. The decay of
K by K-capture of an orbital electron is not readily susceptible to direct
experi6ent4? proof, because the nucleus emits only a neutrino, and no charged
particles are formed in the process.
The following method works, however. The space which becomes free in the
K-shell. is occupied by one of the orbital electrons, as a result of which char-
acteristic X-rays (principally K-quanta) are emitted, The new nucleus, which
 Sanitized Copy Approved for Release 2011/08/17: CIA-RDP80-00809A000600340270-4
is formed by capturing an electron, has a charge which is lower by one unit,
so that the shell alters in such a manner that it conforms to the new charge.
Consequently, the X-rays must constitute characteristic radiation of the re-
sulting rather than initial nucleus, i.e., characterize Al11,,9 rather than po-
tassium. Existence of this type of soft X-rays has been c2tablished by
Thompson and Rowland (3) in the case of potassium salts and has been inves-
tigated more fully by Bleuer and Gabriel (4), As has been suggested by
Academician V. G. Khlopin and Professor E. K. Gerling (5), a direct deter-
mination of argon in potassium minerals and an investigation of its isotopic
composition may also serve as a proof of the fact that K-capture by K40 re-
sults in argon. It is obvious that the transmutation is isobaric and that
only A40 forms from K40, while the ordinary light isotopes of argon (A38 and
A36) which compose atmospheric argon must be absent in potassium minerals.
Several tenths of a cubic centimeter of argon are necessary for a mass-
spectrographic examination, and this quantity of argon car only be obtained
from geologically old potassium minerals. For this reason we used sylvinite
from the Solikamsk deposits, which are 200 x 10 years old. The argon con-
tent in this material being 0.5 cubic centimeter per kilogram, an adequate
quantity of argon could be obtained from several kilograms of sylvinite by
dissolving the latter in water and boiling the solution in vacuum.
The dried argon was investigated on a mass spectrometer of the Niehr
type (6), the construction of watch was given by M. G. Meshcheryckov. The
ionic currents were measured by the charging method on a Lutz-Edelman elec-
trometer. The mass-spectrometric determinations showed that the argon ob-
tained from sylvinite is actually composed almost exclusively of the iso-
tope having the mass 40, the isotope of mass 36, which on the average occurs
to the extent of 0.30 percent in atmospheric argon, being practically absent.
Consequently, the argon occurring in sylvinite cannot possibly be of atmos-
pheric origin, and the decay of potassium by K-capture has been proven.
The quantity of argon found in sylvinite is approximately one-thirtieth
of that calculated on the basis of the decay constant for K-capture, which
in this case amounts to 1.9 x 10-9/year according to Bleuer and Gabriel.
The difference between the experimental value and the calculated value can
only be explained by assuming that the sylvinite is of secondary origin and
thgt it is therefore younger than the age of the surrounding deposits (200 x
106 years). According to Yu. V. Morachevskiy (7), sylvinite was formed from
carnallite in a sore recent geological period. On the other hand, the value
for the constant of potassium decay by K-capture may not be quite exact.
A simple calculation shows that all the argon with mass 40 which is on
tained in the atmosphere must have formed in a period of less than 1 x 10?
years, if Bleuer and Gabriel's constant is assumed to be correct. Provided
that the value for the constant of decay by K-capture is exact and that a re-
liable method for the determination of argon is applied, the formation of
argon frua potassium and its presence in minerals can to used as a basis for
determining the age of minerals.
BIBLIOGRAPHY
1. G. S. Sisoo, Physics, Vol IV, v 467 (1937)
2. A. P. Grinberg, Uspekhi Yhimii (Progress of Chemistry), 2-3 (1942)
3. Thompson and Rowland, Nature, Vol CLII, p 103 (1943)
4. E. Bleuer and M. Gabriel, Helvetica Physics. Acts, Vol XX, pp 67-72 (1947)
Sanitized Copy Approved for Release 2011/08/17: CIA-RDP80-00809A000600340270-4
 Sanitized Copy Approved for Release 2011/08/17: CIA-RDP80-00809A000600340270-4
CDHCIDER11 a
5. V. G. Khlopin and E. K. Gerling, paper presented at the geological meeting
in 1947
6. A. Niehr, Physical Reviews, Vol XLIX, p 272 (1936)
7. Yu. V. Horachevskiy, Essays in the Field of Geochemistry. The Kama Salt
L,-,.,Deposits. Trudy VIG (Works of the All-Union Institute of Geology), 1939
CONFIDENTIAL
Sanitized Copy Approved for Release 2011/08/17: CIA-RDP80-00809AO00600340270-4