On the existence of a calcium isotope with an 8.5 day period

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Material Information

Title:
On the existence of a calcium isotope with an 8.5 day period
Series Title:
United States. Atomic Energy Commission. MDDC ;
Physical Description:
2 p. : ill. ; 27 cm.
Language:
English
Creator:
Overstreet, Roy
Jacobson, Louis
University of California
U.S. Atomic Energy Commission
Publisher:
Technical Information Division, Oak Ridge Operations
Place of Publication:
Oak Ridge, Tenn
Publication Date:

Subjects

Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliography references.
Statement of Responsibility:
by Roy Overstreet and Louis Jacobson.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 005023648
oclc - 277230215
System ID:
AA00008527:00001

Full Text
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UNITED STATES
ATOMIC ENERGY COMMISSION
OAK RIDGE
TENNESSEE








ON THE EXISTENCE OF A CALCIUM ISOTOPE WITH AN 8.5 DAY PERIOD


by


Roy Overstreet


Louis Jacobson


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for use within the Atomic Energy Commission.


Inquiries for additional copies


lestions regarding reproduction by recipients of this document may be referred


cuments Distribution Subsection,


Publication Section,


Technical Information


atomic Energy Commission, P. O. Box E, Oak Ridge, Tennessee.


as a declassified document may differ materially from the original classified
by reason of deletions necessary to accomplish declassification, this copy does
tute authority for declassification of classified copies of a similar document
y bear the same title and authors.


Date of Manuscript: Nove


Document Declassified: M


mber, 1946


lay 12,


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MDDC 938


ON THE EXISTENCE OF


A CALCIUM ISOTOPE WITH AN 8.5 DAY PERIOD


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Walke, Thompson, and
reported an isotope with an
It was prepared in greatest
ons. Also, very low yields
fast neutrons. The authors
ting primarily X rays (3500
energy (1.1 Mev).

An attempt to produce
particles. Although the rep
small, it was thought that si
Mev deuterons to make feas
reactions were tried:


Holt( 1), in a study of the
8.5 day half-life which t
yield by the bombardme
of. the isotope were prep
conclude that Ca41 deca
ev) but some gamma ra


radioactive isotopes
hey have given the as
nt of calcium metal w
ared by bombarding c
ys to K41 by K-electr
vs and conversion ele


of calcium, have
signment of Ca 41.
ith 8 Mev deuter-
alcium oxide with
on capture emit-
ctrons of high


has been made in this laboratory using higher energy
d fraction of gamma rays and conversion electrons is
iently high yields of the isotope could be obtained with 20
its use as a tracer in biological work. The following


a. Ca4'


CaCl2 was bomba
No activity with a half
about .05 Mev (limit o3
0.3 p c of long-lived a
This result was unexpi
K41 (d, p) K42 at these


(d, p)


Ca41 :


rded with 20 Mev deuterons to the extent of 4
-life in the neighborhood of 8.5 days and elec
f the electroscope) was found in the calcium
activity (> 60 days) was found which presumat
ected in view of the fact that high yields are
? energies (107 pc per micro-ampere-hour).


b. K4


KCl was
Thirty-six h
activity. Th
activity coul
calcium frac
scope and a


10 micro-ampere-hours.
:tron energy greater than
fraction. Approximately
ly was due to Ca .
obtained for the reaction


2w"


bombarded with 20 Mlev deuterons to the extent of 135


ours
e thi
d be
tion
GM


; afte
ickne
dete
was
couni


r the
ss of
cted u
exam
ter (w


bombardment ,the
the sample was 0
ipon placing the s:
ined with negative
indow thickness =


purified
.75 milli
ample in
Results
2 mgs.


calcium fracti
ams per squ
Je an ionizati
p means of a
r cm2i. As


micro-ampere-hours.
on was examined for
are centimeter. No
on chamber. Also,the
thin window electro-
a final check, an X-ray


film was


placed over the


sample for several days.


No darkening was


observed.


c. A40


(a, 3nm


Argonr
Smicro-am
copper wi]
produced.
in suroris


gas
pere-
re exi
The
inlyv


(2.5 liters) was bombarded with 40 Mev alpha particles t
hours. The radioactive products were collected on a neg
tending into the gas. No measurable amount of radioactive
only activity found on the wire was due to K". This is<
sood vield bv means of the reaction A4 (f.pn)K42 The


o the
native
re cal
otope
vield


extent of 20
ly charged
cium was
was produced
was BOnc





.


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In each of the above preparations appropriate inert carriers were added and calciu
wvas finally isolated as the oxalate. As a special precaution, barium and strontium preci:
stations were made in all cases. All precipitations were repeated several times in the
presence of hold-back carriers in order to insure-clean separations. Activities were
measured with a Lauritzen electroscope. The air-gap plus the electroscope window was
equivalent to 4 mgs per cm2 of aluminum.


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On the basis of the experiments described, it must be co
tope exists that emits beta or gamma rays or energetic convert
life must be considerably less than one day or longer than one
an isotope that decays by means of K-electron capture to the g
nucleus K41, thus emitting only very soft X rays (3500 ev) and
tectable electrons, also seems to be ruled out. On the basis of
from the (d, p) reaction, an 8.5 day Ca41 should have been prod


ment in a yield
by the instrume
-1.5 mg Al per


included that if a Ca41 iso-
rsion electrons, its half-
year. The possibility of
round state of the product
no gamma rays or de-
Sthe observed yield of Ca4


5


luced by the same bombard-


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of-300 pc. This amount of activity presumably would have been detected
nts used, in view of the fact that 3500 ev X rays have a half-thickness of
cm2 or-6 mg air per cm2.
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