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Clawifimtion C!INVWI to UNCLASSIFIED

by nv:!mrity of the U. S, .’.! w:? Emr

I%?A?- LL#4?&-== /z7iz”L)

13y i;iiwORT LIBRA.Q

‘3

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C\C-14REPORT COLLECTION 3-2~”s~ !REPRoDucT\oN COPY

RANGES IN AIR OF PLUTONIUM FISSION FRAGWW3S AS A

FUNCTION OF I’HEIR IWSS

R=Writt en by:

s. Ihitcc?ff

J. Ao Miokd

h

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mcL@EQ ‘

,,

-—-————— .-.. ——

“-— .- *

~_&Ms Ii’?.A.IRm ?.LUVONHR!FISSION FRAG;’xNT2AS A -.— -- . . ....— —.

d. tie“ Ytikel.~d Se Katcoff

It is ,possibleto effect a partial separation of fi.sd.onproducts

by taking’advantage of the variation in the range of fission i’ragjientsas a

i’unctionof theSr mass~ The same phenonmmn can be ueed to determine the

miAf38 numbers of pWViOU$& UIMSS&ASd fission prOdMts~ In the experiments

r’eportedhere the ranges in air of seven plutonium fission products have

been determined”and mass numbers have been asaigmd to two of.thcse~ The

straggling h the range,hw been determined for each @f these also.

The apparatus”consists of a beryllium tube about 8 inch-38long

and one inch in d’iamet= which contains a flat plutonium foil (about 001

mg/cmz thick) at one end. Starting at about 4 inches from the plutoniu~:

there is a-series of M+ zapon films (about 7#g/cm2 thick) spaced 2/&-i.nch

apart. The tube is ordinarily evacuated to an air pressure of 12.0 cmllg

and then irradiated in a high neutron flux at the center of the MS ALamos

l*waterboilert10 The zapon films

in the mass range being.studied,

era stopped in the region of the

nearest film where they remain.

~_ -------- After irradiation each

-“ “-‘–

are so situated that all fission fragments

which do not strike the walls of the tube,

zapon films, They then diffuse to the

Neaiilyall of the stopping material is air.

zapon fih (except the first and last) is

radiochexnicallyanalyzed for “afew fission .productso ‘TheactivStie8 fm.md

on each film arc cor.rcctedto the same solid angle and then plotted against

f

.

di8t~ce Of dry air traversed by the fragments, as in FigO ~0 The dist~ce

gew~- “—–, .

—m

‘4 5-~~~ \ t.~corrected to 76.o cm ligpressure, to 15° C, snd account is taken of the

g%l==~ ,.

.J~m \

I =====

-—. - UNCLASSIJIW . _–___ ..—

-— A

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..,=. UNCLASSIFIED .

ijhicknessof’zapon tz-aversed. By integrating the area under these curves,

Lntemal range curves are ootained, as in Fig. 2. The straight portions

oi t.he8eare e.xtrapola%edto zexo activity to give extrapo@ted ranges.

so far, 11fission products in the heavy group have been irrvesti-

~ated~ The extrapolated ranges md width at hti- height of the di.ffereni:,ifi r~e curves are listed in the fol16wing table~’ ‘i’hez’eeultsfor

S5 m Ba139 arc considerably distorted because of diffusion of its 41.

sec. xe ancestor throiigh,or around, the zapon illm; therefore, tfiey

are omitted from the table.

Extrapolated

Fmnge

Straggling

93 h 1+.2 h 7713

~b12’7

2.317

cm —

13.>2% u.,% u.>%

6(? m I lb3 m

2.232 I 2.210

2.2.$ d

J40

=---- .. ...”

2 u108

look%

133 ad 43 mT~ The results for 60 m ‘l%

13/+

were obtained by analyzing for

their 22 h I and Y+ m I daughters, respectively,

In Fig. 3, the range8 are plotted against tho mass numbers. A .

straight IMe has been drawn through the points, in the absence of a better

approximation. Mames 132 and 134 were previously una8si@ed, but it is

now obvious from Fig. 3 that they should be assigned to 77 h Te and f+3m Te,

respectively. The results reported here should be considered only as $entati.vebecause the experiments are still in progress.

.

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