time after detonation asd follows 0 aimpl- relationsiip,
Fortier, tis ratio
at any give.. tine after detonation has net teen fircly esta_lisced,
One
report™ sugcests the following data:
Time after detonation
Beta/cacce
72 hours
157/21
268 hours
56/1
These dais were o: taived from a cloud sample, ratcer t.an actual fallout
material, a.d were a measure of surface dose o: @ plaque using a "dosincter~
type tetn-ray surface fonisation chamer,"
The metrod of collection surrests the possiility that the thicikness
of material on the plaqies may be less’ than t-at to :e expected from the
amount ef fallout trat would be of eoncern wien estimating proum ilities of
beta turcs.
1s would reasvlt 42 a differest anmular dipiricutios of the
vetas Influencing t:e -eta dose rate in the direction of a higuer value for
the plaques,
Anot-er reportl indicates a beta to gama ratio of 130 to 1 based on
tieoretical comviations.
A trird report® surgests @ redically lower ratio;
however, there ma: be some dou! t as to its conclusions since tre fovisation
cham er csed to measure gamzas only, t.ad a wall thickness of 1 mm eof sacelite
sy
TN
which *,,, excluded a small part of the total rama dose presest, as well as
@ large, tut unknown, fraction of the beta.*
(‘the renee of 0,35 Mev tetas is
about 200 mc/en® or approximately 1 oa of bacelite.)
For our disoussicn here,
we will assume a wpirface beta to gama ratio of 150 to 2,
{AYO
“Were
In estinsting t:e |-eta dose to the basal laver of tie epidermis, one ma;
refcr to tre work of “enrigues3.
He exposed t e skin of ester tr tte pirs
ef 1~20, Selentific Tirector's Report, Annex 6.5, “Interpretation of survejencicr fata.: co
i "An Fstimate of the Relative Yasard of ‘eta and Garra iadintion from Fission Products".
Sullivan, Filliam f, N°DL. April 19L9, CONFIL-NCIAL
2 UNP-37. Project L.7 "Garma~ eta Patio in the Fost-s ot Contaminated Arca", Jane 1953.
CONFTT ONUIAL-RU TRICTID Pata.
_
3 "Effect of Beta Rea.s on the Skin As A Punch
aay :e 'neres, Intensits, and Duratio: of
‘ OE/alA
Radiatiow,
Henriques, T.).
Laboratory invesfipatio..
2 ©
Vol. 1, Mo, 2,
Sumner 1952.