Fission of bismuth, lead, thallium, platinum and tantalum with high energy particles

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Material Information

Title:
Fission of bismuth, lead, thallium, platinum and tantalum with high energy particles
Series Title:
United States. Atomic Energy Commission. MDDC ;
Physical Description:
4 p. : ill. ; 27 cm.
Language:
English
Creator:
Perlman, I
Goeckermann, R. H
Templeton, D. H
Howland, J. J
University of California, Berkeley
U.S. Atomic Energy Commission
Publisher:
Technical Information Division, Atomic Energy Commission
Place of Publication:
Oak Ridge, Tenn
Publication Date:

Subjects

Subjects / Keywords:
Nuclear fission   ( lcsh )
Cyclotrons   ( lcsh )
Bismuth   ( lcsh )
Lead   ( lcsh )
Thallium   ( lcsh )
Platinum   ( lcsh )
Tantalum   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
technical report   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Bibliography: p. 4.
Restriction:
"Date Declassified: June 12, 1947"
Statement of Responsibility:
by I. Perlman ... et al..
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 - 005024218
oclc - 277770321
System ID:
AA00009350:00001


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MDDC 1048


UNITED STATES
ATOMIC ENERGY COMMISSION
OAK RIDGE
TENNESSEE



FISSION OF BISMUTH, LEAD, THALLIUM, PLATINUM
AID TANTALUM WITH HIGH ENERGY PARTICLES

by


I. Perlman
R. H. Goeckermann
D. H. Templeton
J. J. Howland


University of California




SPublished for use within the Atomic Energy Commission. Inquiries for
additional copies and eay questions regarding reproduction by recipients
of this document may be referred to the Technical Information Division,
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
S for declassification of classified copies of a similar document which
S my bear the same title and authors.


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Date of Maniscript: Unknown

Document Declassified: June 12, 1947

his document consists of 4 pages


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This document is a direct reproduction, by photo offset, of the copy in
the files of the Technical Information Division. This method of repro-
duction is being used temporarily as an emergency expedient in order
to effect earliest possible distribution of the information contained
therein. As soon as the expansion of the TID composing unit and of the
Oak Ridge printing plant, now under way, is completed, MDDC's will be
issued in an attractive permanent form.




























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MDDC 1048


Fission of Bismuth, Lead, Thallium, Platinum
and Tantalum with High Energy Particles

I. Perlman, R. H. Goeckermann, D. H. Templeton and J. J. Howland
Radiation Laboratory and Department of Chemistry
University of California, Berkeley, California

CLASSi ICATiOi CA,.ELL.ED
Hay 16, 1947 For tne Atomic Energy Commiscson 6-/-Y7

Deciaemification ofll'car
The 184-inch Berkeley frequency-modulated cyclotron produces

deuterons, helium ions and neutrons of energies up to 200, 400, and 100
Nev respectively. Nuclear fission in elements covering the range of

atomic numbers 83 (bismuth) to 73 (tantalum) has been observer with one

or more of the above projectiles. Fission was determined by chemical

identification of radioactive fission products.

Although a number of the fission products characteristic of slow

neutron fission of uranium are found, the fission reaction on these

light elements with high energy particles differs in some important

respects. There is no evidence for well-defined assymetric cleavage

with a deep valley at the midpoint of the yield curve as is the case

with slow neutron fission. Another difference is the appearance in

good yield of light isotopes of a given element, and undoubtedly the

formation of stable isotopes as primary fission products is not

unusual. For example, the shielded isotope Bre8 is formed in comparefl

yield to Brse with 400 Mev helium ions and 200 Mev deuterons on
bismuth while the relative yields are 1 to 10' for these isotopes in
(1)
the slow neutron fission of uranium. In .the bombardment of bismuth

and lead with 400 Mev helium ions no measurable amount of Ba'O4
(formed in highest yield with slow neutrons on uranium) was found


-1-






-DDC I108


(2)
but an activity which is probably Ba1ss was noted. This isotope is

not found at all in the fission of uranium with slow neutrons as it

falls well down among the lightest stable isotopes of barium.

It has not been possible, thus far, to compare accurately yields

from different bombardments because of the inability to determine the

beam strength. However, certain trends appear to be definite: The

probability of the fission reaction for a given projectile drops off

as the target atomic number decreases from bismuth to tantalum. That

for a given target element the fission yield decreases as the projec-

tile energy decreases is indicated by the decrease in yield of bromine'"

activities from bismuth fission as the deuteron energy is varied from

200 to 50 Mev. The distribution of fission products changes in varying

the projectile energy since the ratio of Bre to Bro was 2 for 200

Mev deuteron on bismuth and 100 for 50 Mev deuterons on bismuth.

Table 1 shows fission products found from the reaction of 400

Mev helium ions with bismuth and the relative yields of these isotopes

The radioactive properties checked reasonably well those previously
(1,2)
reported for these isotopes. The yields are expressed in

arbitrary units. It is of interest that Balo0 was not present in

detectable amount.


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MDDC 1048


Table 1

Relative Yields of Fission Products
from 400 Nev Helium Ions on Bismuth


Ga" 7

Bras

Brea

Sre 1 ye

yeo


22

150

390

540

1400


The conditions of

fission was observed in


MOg9

Rulos Rh10S
-10 4


Balas


480

240

8

34


irradiation that were tried and under which

all cases are summarized in Table 2.


Table 2

Summary of Irradiations in which Fission

Target Projectile

Bi a

Bi d

Bi n

Pb a

Pb d

Pb n

T1 a

T1 d

Pt a

Ta a


was Observed

Energy(Hev)

400

200,150,90,70,50

100

400

200

100

400

200

400

400






KDDC 1048


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It is of interest to 4epeculate on the mechanism of the fission

in view of the high degree of excitation of the compound nucleus.

Since the probability of fission would increase with a greater charge/
(3)
mass ratio and since it is known that large numbers of neutrons may

be ejected from such highly excited nuclei, it seems likely that the

actual fission reaction is preceded, on the average, by the boiling-

off of a large number of neutrons. Some experimental evidence sup-

porting this view is the appearance of light isotopes for a given

element in a few cases and the finding that the most probable fission

results in products the sum of whose masses lies well below that of

the target mass number. However, the same observations would result

if the fission reaction would occur first with the fragments still in

highly excited states after dissipation of their kinetic energy.

The co-operation of Prof. R. L. Thornton, Dr. D. C. Sewell and

all those whose operation of the 184-inch cyclotron made these irradia-

tions possible is gratefully acknowledged. We wish to thank

Professor E. 0. Lawrence for continued interest and Professor G. T.

Seaborg for helpful discussions regarding this work.







1) Plutonium Project compilation of nuclei formed in fission.
J. Am. Chem. Soc. 68, 2411(1946).
2) G. T. Seaborg "Table of Ifotopos" Rev. Mod. Phys. 16. 1(1944)
3) B. B. Cunningham, H. H. Hopkins,-M. Lindner, D. R. Miller,
P. R. O'Connor, I. Pcrlman, G. T. Seaborg and R. C. Thompson,
Paper to be given before Stanford University meeting of the
American Physical Society, July 11-12, 1947.




















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