Radioactivity of Cu⁶⁰

MISSING IMAGE

Material Information

Title:
Radioactivity of Cu⁶⁰
Series Title:
United States. Atomic Energy Commission. MDDC ;
Alternate title:
Radioactivity of Cu-60
Physical Description:
6 p. : ill. ; 27 cm.
Language:
English
Creator:
Leith, C. E
Bratenahl, A
Moyer, B. J
University of California
U.S. Atomic Energy Commission
Publisher:
Technical Information Division, Atomic Energy Commission
Place of Publication:
Oak Ridge, Tenn
Publication Date:

Subjects

Subjects / Keywords:
Copper -- Analysis   ( lcsh )
Copper -- Isotopes   ( lcsh )
Radioisotopes -- Measurement   ( lcsh )
Radioactive substances   ( lcsh )
Cyclotrons   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
technical report   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references.
Restriction:
"Date Declassified: July 9, 1947."
Statement of Responsibility:
by C.E. Leith, A. Bratenahl, and B.J. Moyer.
General Note:
Manhattan District Declassified Code.
General Note:
"Date of Manuscript: Unknown."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 005023876
oclc - 277770428
System ID:
AA00009296:00001


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Published for use within the Atomic Energy Commission. Inquiries for additional copies
and any questions regarding reproduction by recipients of this document may be referred
to the Documents Distribution Subsection, Publication Section, Technical Information
Branch, Atomic Energy Commission, P. 0. Box E, Oak Ridge, Tennessee.

Inasmuch as a declassified document may differ materially from the original classified
document by reason of deletions necessary to accomplish declassification, this copy does
not constitute authority for declassification of classified copies of a similar document
which may bear the same title and authors.


Date of Manuscript: Unknown

Document Declassified: July 9, 1947

This document consists of 6 pages.


u S DEPOS y L'


U S DEPOSITORY


UNITED STATES
ATOMIC ENERGY COMMISSION
OAK RIDGE
TENNESSEE






RADIOACTIVITY OF Cu60

by

C. E. Leith
A. Bratenahl
B. J. Moyer





University of California


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RADIOACTIVITY OF Cu60
0'

By C. E. Leith, A. Bratenahl and B. J. Moyer


INTRODUCTION

A positron activity with a half-life of 24.6 .3 minutes has been assigned to Cu60
If radiation associated with this decay has an energy of 1.50 .05 Mev, and the upper
limit positron energy is 2.50 .25 Mev.

PRODUCTION

This activity has been produced in three ways, using separated isotopes of Ni. These
are listed with the cyclotron and particle energies used, as follows:

Ni60 (p,n) 37" frequency modulated cyclotron 5-15 Mev p

60" cyclotron 9 Mev p (18 Mev H2 )

Ni60 (d,7n) 60' cyclotron 18 Mev d

Ni58 (a ,pn) 60' cyclotron 36 Mev d


In the 37 "frequency modulated cyclotron, the Ni60 sample was mounted on a probe;
hence it could be bombarded at an arbitrary distance from the cyclotron center. The
threshold energy observed for the Ni60(p,n) reaction was 5 Mev.

DECAY MEASUREMENT

The decay of the activity was observed, using an ionization chamber and Ryerson-
Lindemann electrometer. By exciting the activity with 5.5 Mev protons the decay was meas-
ured through six half-lives with no evidence of a foreign activity.

TYPE OF RADIATION

That the particles emitted were positrons was determined by bending them in a magnet-
ic field into a counter. Penetrating f radiation was also observed.

ASSIGNMENT OF ISCTOPE

Chemical separation of normal nickel targets after bombardment with 15 Mev protons
into Cu, Ni, and Co fractions showed in each case that more than 99 per cent of the 24.6 min
activity followed the Cu separation chemistry.

The 20 mg Ni target was dissolved in 1 mc of boiling concentrated HNO3, which was then
3,


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driven off by several additions of HCt. 5 mg of Co and 5 mg of Cu as chlorides were added
as carriers. Cu was reduced to cuprous state with .5 ml NH4HSO3 and Cu SCN was precipi-
tated with .5 ml of 10 per cent NH4SCN to be removed by centrifuging. The Cu SCN precipi-
tate was washed twice with a solution of 1 ml 10 per cent NH4 SCN and 5 drops NH4 H803 in
100 ml water. The washed precipitate was dissolved in concentrated HNO3 and dried on a
platinum disc for counting. This separation was accomplished within one hour of the end of
the bombardment.

Mass separation in a calutron accomplished within one hour of the end of A p bombarl-
ment showed without question that this activity belonged to Cu60 .

1 ENERGY MEASUREMENT

The energy of "1 radiation was measured by absorption in lead, using the absorption of
Co60, 1.1 and 1.3 Mev 7 radiation for calibration of the geometry. The geometry was simi-
lar to that of Cork and Pidd.1 The active sample was surrounded by at least 2 inches of
lead, except down a collimating hole 8 inches long in lead. The counter tube was 40 inches from
the sample and the lead absorbers were placed directly in front of the collimating hole.
The effective absorption coefficient in lead of the two cascade -y's of Co60 was .640
.010 cm-l, in good agreement with results of Cork and Pidd. The absorption coefficient 1i
lead for the l radiation of Cu60Ni60 was .546 .013 cm-1, corresponding to an energy of
1.50 .5 Mev.

DISINTEGRATION SCHEME

From consideration of the positron energy expected on the basis of (p,n) threshold
energy, it may be that the p + spectrum is complex, consisting of two groups with energies
of 1.0 and 2.5, the 1.5 Mev 1 following the 1.0 Mev P +i Thus the disintegration scheme
would be

2.5
1.5 -

0 i60 Cu60





PREVIOUSLY REPORTED ACTIVITIES

The 81 sec and 7.9 min positron activities produced by proton bombardment of Ni ob-
served by Delsasso et al., 2 and tentatively assigned to either Cu58 or Cu60, correspond

1 Physical Review 66, 227 '(1944)


2 Physical Review 55, 113, (1939)







58
to 81 sec and 10 min activities observed after bombarding Ni with protons in the 37 inch
cyclotron. These are tentatively assigned to Cu59 and Cu58, respectively, on the basis of
threshold and excitation considerations. The longer life was shown to be a Cu activity by
chemical separation.

The 3.4 hour half-life activity assigned 3 to Ca61 was verified by being produced in a
Ni61 (p,n) reaction.

The 10.5 min half-life activity assigned4 to Cu62 was also verified, but the half-life
was found to be 10.1 .1 min in measurements made through 6 half-lives.

Acknowledgement is due to Dr. E. H. Huffman and Robert Lilly, of the Radiation Lab-
oratory, for the chemical separations. The mass separations on the calutron were perform-
ed by Keith Pierce.

































3 Ridenour and HendersonPhysical Review52 889, (1937)


4 Heyn, Physica 4, 1224, (1937)


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HALF THICKNESS :.500": 1.27 CM


2 3 4
PB THICKNESS IN INCHES


ABSORPTION OF CU60 Io

IN LEAD


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2500


1000 1500 2000
AL THICKNESS IN MG/CM2


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1000 --- MDDC


HALF LIFE v 24.6 MINUTES


DECAY OF ACTIVITY IN
Ni60 AFTER BOMBARDMENT
WITH 5.5 MEV. PROTONS


TIME IN MINUTES







UNIVERSITY OF FLORIDA

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