eam
Wie oon Ae a tA aby beae de
heat Ah alive oy Tift’ ae ene oO
This detector response to cosmic ray
was also estimated.
secondaries as a function of altitude is shown in Figure 3.
Figure 3 along with our gamma dose rate calibration of
che
ilrought
sly dry
> area.
spectrum “energy” in the band 0.15 MeV to 3.4 Mev (43.0
BeV/ (ur/hr)) indicates that the response from cosmic rays is
less than 0.5 ur/hr gamma equivalent up to 6,000 feet.
The
crystal response appears to increase more rapidly with
increasing altitude than does the cosmic ray ionization
intensity, especially at higher altitudes.”
This may be due
id
loisture
ct of
dose
to a transition effect.
The electrons and photons are
passing from a medium of low Z (air) to one of much greater
‘e
Z
(NaI)
resulting in a rapid buildup of electrons and
The crystal
response in the energy region 0.15 MeV to 3.4 MeV is probably
due more to photon interactions while the total ionization
/photons of lower energy in the crystal.’
aad
> Major
vith
st all
oF Swi A
aoe
energy bands used in determining natural component dose rates
ie 1965
These
1 dose
~
intensity is more dependent on charged particle interactions.
Since in the lower atmosphere the flux of photons increases
more rapidly with altitude than does the flux of charged
particles, we would expect the crystal response to increase
Lf more rapidly with altitude than the cosmic ray ionization
; intensity.
‘tion of
> lakes
-S are
Direct total dose rate measurements were also made over
these lakes with our high pressure ionization chambers.
/ These results are also given in Table V.
ind at
ila
ments
rentine
imma activity.
in the
1 Or
» more
m gamma
Since the total spectrum "energy" has been shown to be ©
relatively independent of cosmic ray intensity up to fairly
‘high altitudes,
quantity at
the gamma dose rate derived
a land
from this
site can be multiplied by our well
(known ionization chamber gamma calibration factor and
subtracted from the total ionization chamber reading to
Provide additional data of ionization chamber cosmic ray
/ response versus altitude.
The spectrometric and ionization chamber results given
in Figure 3 and Table V along with some independent
pectra
pCalculations of cosmic ray intensity at certain pressuremtributors
altitudes, calculations of the cosmic ray response per unit
" our
dose rate of the ionization chambers, and data of other
ge
investigators have allowed us to infer the variation of
ose
cosmic ray ionization intensity versus altitude from which
tal
the HASL inferred cosmic ray dose rates of Table IV and V
g were obtained.
c ray
This variation with altitude of cosmic ray
.
;
.
;
;
three
# ionizati
is discusse
in detail in a separate paper. 5
le gamma
on
d
ll