M
MSTGATIU W TH!R ASOMRTIM OF AT*MAA
MDON TWICE XnIfRAL $CORCES
by
coMia-A
Os&ga"
aSlw aeMke
DoIm= or
25
JMW4
IMAOMMMte
A--141
iets
AJ
t
or
Ig I
*#*.......
nL.......
OWMAM12,
Osrtfit by ... n
by
r*~~o.
ailns, Deprbtn
Gintit*n0
O rtsate Sttaenfl
TAB
OF 0 O7T3T
PagS
IliTROIDUCTION
+.
-.......-.........
ACKNO InMONTS
..................
9
e..............
THEORETICAL ?RVDICTIOU OF ALPHiA-RAY EMISSIi "'OV A
,..................10
SOLID SURFAE
Notation
.....
General
......
..
10
q....'....s..
...
11
. 4.........*.....
Alpha.4Ray 1'ission Prom A Solid Surface
General Equation For 1tiassion
.....
13
*........
Absoption of Alpha-Rays In The Sourn
APPARATUS
Chamber
.............
NTS
. 2
................
,
Baclegon
0
0
27
*.... ...........................
Evalution
*...............
U.r......t.
28
...................
31
Linarity of RednVtIon of Area and Coutt .,.
Calibration of The Comnting Appratas
RESULTS
.n.
Coprison of Observd
wagnetit*
38
39
43
*.............o...#...................#..e...
Emission from
25
27
.,.a.........,.s..,.......vt..
General
Prosoren
19
e....e.
............
Photographic Recording
16
19
***
Eleetremeter CareUlt
MEASURNE
.....
*....,,.....................*..
loisation
12
.,..
a
Predicted
...............
*
43
Rm~sln rom Other Source Mtria
SUM
..
.
.
BImLOotmf ...........................
.
.
4,5.*
O
.........
4
MZTOF TABLES
Page
Table J#
Radioactive series.
Table 2.
Total alpha ounta on the full aouroa
area
Table 3,
2
..............
.........
,..
Total alpha count determinations,
redued to on-fourth of total area
Table 4.
Total alpha count determinations,
Soaroe
...
,
Soarce
redunod to onemhaSf of total area
Table 5.
34
....
*.,,*...
37
40
Sumnatics of deoteotable ranges of alpha
emitters in uranium I# aotino-uranium, and
44
Table 6.
ftnsion measuremmente on galons and
45
Table 7.
Table
,
Coutation of .Ad for standard triassic
diabase from whmioal analysis .........
46
COcparien of ealulated and observed
alpha emalaione
.
.....
48
e.....
. ZQU2ME
Figure
Uraniua I disintegration series
.......
4
figure 2.
AMtia-wair :I $integration serlee
4
Figure
Thorium disintegration series
5
1,
S.
Figure
...........
Gometry for alpha.*ray emission froM a
solid surfaw
Figure
5,
Fr
o6
...................
Sation ehamber sa
P--54 bridge ofrcuit
12
eleotraemotor ttbe.
20
25
Figure 7.
7iguro 8.
Figur
9.
Coliodian blank activity determination.
tn-mfourth
area 4ata
..............
Gaifllratln ot lisation oamber
Pago
38
41
Dependense of alpha. emission of equivalent valut of Ra In equilibrium in uraniam
.
50
series aufEt
for thiok sowes.
1 a
A
AUl tareset4a aterias aeatala at teast smafl
uimownt at tnrswietmat satuafly rattnttn
aleent amg ag f~a
tisriau. tae 2
wrents
sns
aotive aris" tertir
2,
U lemuto -t
wit
Utr
as
netia-tan,
the
nm
0"AS eVvqt
vaaesa
anataata, Nttes.~m wsbftn a
et ri
natraly ad1eets t Ptaatu -a
aittaet
a
beesg
rage
t l.8
ats
tare rtau
a. atea
iaagratin
se aiso
feta
are neak
wile aortmia ata alpha-raya with
air ontmtera (2.4).
ativity at sems
bass 1
tuon *wins to It*
ise hw
ta alpha
esaegat La toa wnvestig.
a"
rtity (Na).
,w2 d
Table to
Ratetlve Srln
Vesa Atomis
No*.
o*
ut
284
0.36%) 20
234
210
210
222
2*
03
UII
Ra
Rn
RaA
Ras
Rai
A* ( 0.06%) 214
Ra'" (9,91%) 217
210
RoD
210
Rag
as'
210
Rap?
an
RaG (Pbae6)
206
92
90
S1
91
92
90
862
98
0
81
U1I
251
2?
223
219
815
AoB
211
AsO
211
A08. ( 0.3%) 0?7
ALO* (99.7%) 211
AeD
207
a
as
at
07
91
Diotatpgat&on
Gatant
2.65
4,085 z
j (r)
p(T)
()
3*.3.
3.09
320
4*06
468
cC
6091
00
oft)
0(09
0i
ois
(pY)
cpX
'Pr
4600
8*15 a 103
9.92 aH-0
1*61
2 0*4
575 a 10*
2,9
3.10 x 10-17
3.57
6.86 X 10-1
1,84 a-4,24 a 10-7
4,29
6,46
im
4.0
02
trO-
4586 x 1t-?
1.015 x $a-2
287 x 109.6 x 0
2.8za 10 13
18:
10*1
2.0* x 1a-6
.7 x 10*
4.31 a 104
3,86 a 10-4
OIt
e')
04
64
8
A
3.84
92
R 0 nnge of
( )
(Y
lange
in air
a.s
'0
as
AMU
Ur
Pa
A*
MAO (n9)
A6K ( 1%)
AOZ
An
AcA
Radlatin
Tga x 10o-
5 05 x 10-6
7.16 x 1-7
0,1768
3,47 S 102
3,21 a 1004
6.35 a t0-3
3.
a102
2.46
I
10-a
lpharay in oentiatwrs of dry air a t 1500
760 M 4g.
A adi lnt tran
enstanto praetion transformet
par $00st,
s
weak raiatian.
S 5
Table ,.
leet
Rtdtln
Mass
No,
-
Soeree (enntnUnd)
Atcms
X,
Reite
tie
Rae
in air
Disinterat tn
conatant
A
ase
fT
20
Rag
mahe20nop
sThg
ThE
tz
.0
ase
fto
0$
Ra
90
20
2
"12
fl(Ppggg)
e260
Y
T
98to.e
#8
280
ma
MI
90
px
88
86
CK
as
S
as
84
S0e
d
A YS
o, p
C.
h.OCI
4r00
4M2
.0
6.00
4,73
10*19
3,00 x 19
3.14 z 1005
1)1 a 10
2.20 x 100*
14273z10-2
4,s2
uxo
a 104
1.9(40
uoo x4 107
s
en af alpha-ray in setistows of dry air at
A * £teiterata eestant,
Pration tranfaWed per
U01.c, 0"o nwg.
flnea 1, 2 and s, *bow the
shos for wet
tively,
ietentegration
o1 setinooraaia,
and tborium respoefto omistsm at am alphacay from an atomic nucleus
will laer the stale
ef the element by 4, at
reduce
its eaprgo by R# lasing asns rnitual element 2 below the
pwenut in the peritie table. The aminion of a betapartial. results in an
periodie table,
fns,
eaamt whih Is one highr on the
the parent atom of uranium I (01)
gives an entire .srins of *lats
deseending in a*tate
weights, ad daring Its tiaintegration gives off eight
alpha particles and sixt beta partieles. Th. final ate
-o
4
-
Ul
2380
uz
234-
Ux
230-
to
Li 226 -
o
RA
222
RN
2 218
RAA
0
0(
<214
R A B .0
.<*
R
A
RA
R AC
210 -
--
RADR
206
R AF
+--
RAG (STALE)
81
82
83
84
85
87
86
88
89
92
91
90
NUMBER
ATOMIC
Figure 3. Uranim I Disintegration Series
AcU,
235
AcK --.
3223 0219 -
AcX
AN
0215-
207
RDAc
Ac..
x227 -
211-
PA
UY*-*
231-
*AcA
AcC
Ac8 * -AcC
Ac C'
I
81
*
/
AcD
I
82
(STABLE)
I
i
83
84
85
i
86
ATOMIC
Figure 2.
87
I
I
88
89
i
90
91
02
NUMBE R
Actino--Uranium Disintegration Series
S5-
I
J
i
i
I
I
i
i TN
232?--
MTH
MsTHN
228
j
I
I
i
TRDTH
0 224
.
e THX
w
c220
U
2 216
212
-
THBOe--e
THC%
208
TD
SI
81
II
eTHC'
tSTABLU
1
83
as
82
82
I 4'
64
64
I
86
85
as
ATOMIC
as
87I
87
I
88
88
89I
I
90
89
NUMBE R
3.e ?4yitM DisiNtvration Series
t lead (Re)
results la an isotpe
of 206 ad statre ade
of OR.
element aetlam-uraium ealt
with an atmie night
Slmlealy, the parent
sevn al&a particles ad four
bete-partloes, and the parent element thorilum emits si
alpha pr tteles ad tow beta partielse during their 4isIntegration to Wnlr finea stable produets,
If
the
sants of the thre radosotive series
form a part of or cet
as minor i
ities in a mineral
whose erystal struetoe has remained intact for a long time,
the series will hae
is,
reached a state of equilibrits,
That
any mn of the transient daughter elements of uranium I,
actino-aien ,a14 or thorium will be Prasrt in the wiwNral
in an momst that will han
as many atoo
e being f
per unit t"M as
deinteuratinag
The tIme nesessory fr
sdL.
praoteal eqilibriam to be estabitshea i o,000,000
peas
I sI ias eMd a leser nest for the astino-
for the urmn
uranium and thorium eries,
A
atbe on tethfe of
*ear&ing the raduettive
content of minerals ad reeks have been deseribed in the
nuaten han been used antaniw-
open Iiteature.
geg
17 for meaurWM*ut
ot beta ant gams
P-i, R3), at
i
activity (3-I, 3-.
iaIsation ebaber
vltage
54, PI,
geoloi4 a applietian
tilty
0-3, 345, U-I).
(Eel,
5is4,
for alpha
The prinoipal
-of a20letr physes have been out-
lined by GoAkan ($48),
In this reseeref the objetiv. ves to extend and
simplify the mthsl of thin smree total alpha-ray eeunting
developed by Pimemy and Evan
(R-2).
In this methed the tis
pemitted to eased 15 sienna,
(PL)
and Evans ad Godman
anese of the sourO is not
so that all alpha partioles
having ranges in air greater than 2 eantiastera will be
able to leav
the *wa
to be detestable.
dise with enough resual velocity
Finely petaerd saples are deposited
on an aluminum dis with aleohol and the measureants are
made by an apparatus aIiler in prineiple to the one used
in thi resee
.
The measuramnts are made in teaas of
aIpha-sownte per ho
p w uifligvam at sownv.
tagr of using a thin
oues is that the internal absorp-
tion eoretion of the souren t
portnoe,. Th dsatentane
only of
The Avn.
eond *rder ja
at ten motbod are the time
required to prepare the sovre fa MaSUrements sawo*
thickness earrestions, and a lower eoting rate tha
given by a thick sour",
that
Thn last tester is tportant in
geologial appitcations since the alpha-ray ativity of mnst
of the materials Is Smll.
It ws
felt that there is a parti4ar need in
geology for siple, rggd eqai*Wt
to umegnre the total
alpha activity of minraal and rinks, whieh would require
a minima of interpretatia and timn per measuresent.
It
was believed that a thick **roe sounter would be advantageous in these repefe, one a simple and aoourate set of
rules had been evolved for the sorreotion of the absorption
of alphaneays in the soire material*
Particularly, it
was desired that the Draggoleenan absorption rule, which
in outlined later, be tested for accuracy and be used if
possible.
In order to test the theory of alpharay emission
from a solid surfaea, the actual emission of alpha-rays
was measured from samples of knan urenitua and thorinn eonv
-e8
tent.
in cfles to owpenstate for bsskground eors and to
be positiV
that the
Or galn, $
i
oneaewnts inoluded no sonstant Use
t06
saOpfoo -. Oemeansued having sraniua
values from 0*17 X 10*4 to 3.08 x 10S*gram uranium pew
gram of sours,
to 6.7
sad thria
values of loss thin 0.1 z 104
X 1f" grM thetMa par giM of
final owrnlation of
vity of the ampt,
for the oquigenenoa
thorium to uranim
n
cthmor,
Thua, tUS
wed minlaen to atnAl radiontte
s ia the fqm of a
Pw
eurn..
MJaton
urne
materials of difforant
ratios wore tested to se0 if any unpro
soribed state resulted.
,9
*
The wits.fer gme ta
maest thne to the
bated femlO
P.
this nre
t~s
nnehaeatri-
sh eA theAi,
PnftS
3. Belayrsssmeslv natfbstt th
Te equiteent
et a wtbaeA~tiwtty labsr.atscy at the
givens me
?ntese
4 A
ad
of this wesmoh,
nreft of this ttsst,
AMktsrnVe instruotta and- sug-
goetnma on the otenut thery.
arIno
retessor Rzwley
valuable saggtias
eritletsme dwing the eure
at an the orgmal
assehastt
sapprted by the
seolaginlmtesty of Awina
ha ale
mineral
S f1417rl sait is mt
asSt ws dniwgds by fet
lastitate of mhe.Mo
S1m
at
uassplen used la this msaoroh.
twam his
his
Wp. R. M. Tripp,
with a thinastour
alpha
asunter e t*ePd nesvrfl valuable suggestions to
this re
- 10 -
T7EOR1T0OAL PRZDIOTION OF AIPRAWRAY =
,ISSI0N
PROM A S0LW SORfAME
Notationj
of
warne, in equan eantimetera.
A
are
Ul
enntration of parent .lment uranium I in gram
sowe in .q4ifIbrium with uranium I a
pW gra
atit-wuraftum .r tsee
tomeentratio
Th 0
of parent element thoriun in Gra
per
gam of sourse in oquilibriuawith thorim series.
I
A spnifie rate of prodaetin of alphawrays having the
in alpha-ways per snsean ranr R arwntatere
and peW pablo snitintear of *oure.
Nlu
*
spnsiO rate of pention of alpha-rays In the
warne, when only the 6Ien at uranium I is present,
Ng, NAo
N
uranim,
t
g4
nu
a
and thorium roepeetively,
mean range of a speoifte alpha-ray In air-onntimters,
or entimster of dry air at 1500. atnd 760- o fg.
S
U
n
of produetion of alpha-rays within
rate
awe, by the parent oemnts uranium I, aetino-
weights of uranium I, aattneouranium,
,e0ele
ad RILaM respotively,
alphaay emission from the surfane of a solid In
alpha-rays per smmmd per square oentiseter.
alpha-ray
eisina due to the easunt uranium I.
alpha-ray emission due to alpha-rays frM
nM, ni
and thor ium series
the uranium I, aetino-ur anu,
respeotivelys
OwL
total alphar-ay emission froe.
soid surfa* due to
the thren radieOti
series, In alphaarys per
seed per square centimeter.
1?
d
nflty Ot
S.
r
A
in graee* pIn $abiO GentiMeter#
a minimm reeitual alpha-ry ra
La aealntee
whit nabe detnted with wtal: 4- by theo
instrument.
. isintegatm
/\
A
Aa
onstent of a radienftltv cleit,
freatia tranetonmt per ***ad,
uzAMA
deatoration Ostante of uraIUm
set
antsm, and tbwia reepee tiely.
tio of thn alphwaray rage
raege in air,
6.06 X WO0
AVegatro.#
A method of
In the sours
I
to its
muber
prdIeting the alpha-ray amissimn from
a pollhed reok amtnaae
xevered by an aboarb
presented by flamny anA Swans (P)
*
has been
The StatiStia*l prOba
lem of deseedaing asetiflty by ecenting has been treated
by Adae ( A-I), whto ftom
al
1t4 1 Mtty of disintegpattne
stuying the fluettatias
flnstatious due to man*VoS
of nany he
and *ONer (3-4), after
of observatione
conluded that the probable errs' of eSt hourly obseratin
houd
beo
ns
4rntly fri the square
of the fgg4Aaale
%ft
In general the alpha-ray emission from a aolid
surfaes *igb be predicted as follows;
in refereno to Figure 4,
A
_A
the dtftsreattal vflme
dydA ndte
y
ItydA alpha-
rays per second in all
WA
G sOMfy tor alphaMe7 esAsuun tream a
sOIt surteae,
Figure 4.
metors in the swrn,
4irnotions having a
Mean range R air-Oentit
mters or/( R oentiF
Iy&A alphaerays per mond are
omitted in the half spas upwards,
The counting equIpMnt will respond to only those
alpha-rag
having reidual ranges greater ths r alr-
eentimetrs,
cannot *am
centimetern,
thbu,
the alpha-rays cpable of being counted
from a dpth in the sawn* greater than
Thermfot
(R - r)
, the nber of alpha-rays per sooeSi
per square centIMetow renting the surface A-At from depth
-. eosdy
-j-(
00....,s.......()
where
aceS.
The naber nog
alpb&ways esitttg per semend per aquare
oaentlmtr of surface due to the nL61
elemnt U1 In the
somrea neglnsting *doe offoets im
*fa
Pee
oetains li
b
of the aranin 1,
actinoarenim, and thwium series, as is the ease for
geologie materials, the alphaeny emission wonld be a stuena
tien of the number of alphawrays contributed by each elew
ment of the three series.
Th naber Nt of alpha-rays
per seeA per eubto oentimeter produeed when only the
element fanrua
i o prset
in the
ar,
is
6 .06 x 10EE23 AM&
"fl
erw "
ie nmer al
*VI
ealphe-rayo pr eeeno pr
*quan
4 ... (4)
wttia
motors pe IeIkby tI gram pr gra ot so%"'e iapable of
%g./44
i
Aqutica 3
U fet
being 4.tntt
a I3 3.00
the sow"
r)}
Is sunttiinlat
equiliriaa the tbeti tatabUe
*....(b)
e to have resahe -
amiessin due to the uraiua I
sarie en be gIVen by Emasing the rages of the S apeelfis
alph-rays Of te series.
the
nmb
per eselA per squrat eetintw ftam the entire
series is
%A4Z1
the,
QSU1
h DatASr of tiphares
series en be slalarly deriveta
rays per snont
elmeat ter
per sMbe
is
(% a r)}
of alphares
rsnla I
.
from the entire tharim
The nuber no of alpha.
stimtw
predueS
by the patent
1506,06
Sa
1023_A
I~
or
# Th a &
I
LtmoTh
The numobe
fth of alpha-wrays detestable
X 4
we
***1)
**ooed por
square centimeter frm the 6 alpha eitters of the thoriua
series is
Adf
x 103
2*03 fEo ~
******mE
Wier (R-t) has found that the ratio of the alpha-ray atte
vity of the stine-aranian series to that of the uranim I
serias is 0,048
tasering to an isotope ratio of I to 159
for the two parents,
Thus# the number a" of alphs per
second per squa". nntlmter due to the actino-uraniwa
series is
n*
Or nae
0,046 Zk
4 x 103
0,14 V I2RA. ,)
the total number n
0,,,,
,(g)
detectable alpharays per
seond per square oentimater of surfase is the *ua due to
the bSn radiosetive series.
Combining Equatione 6, 8,
anA 9.-
a0
x 20 {I [306Z
+
U.oa2ia,.
% - r) + 0.4ZiR
-
>d}
- r)]
........---....
l0)
en be furthnr simplified by evalaating
Iquatian 10
the detestable rages 21 -- r) for each of the radioactive
series,
The vale of the range R in air at 150 oentigrade
and 780 millbeters of mercury for each element of the
three radioasti
sies
is fend in Table 5.
Taking
P * 0.5 afraentlmetes as obtained frs. results of Evans
and Goodman (2-2),p Equation 10 baeomes
A
z
10j.841 U? + 26.60
Th
........ (1l)
whieh is the final equation giving the prediated. number of
alpba-rays per
sen
per square centimeter of surface that
should be detectable by this equipment.
Aksgstan
g Aphaegr
Jgjae Seoinq
It will be observed that the emission from the
surface of a solid i. dependent upondA , which might be
considered as the absorption factor of the souree to alpha.
rays.
Direst saasuremnta of/
ae not prantsal.
However,
Ad e*a, be approxmtatet from the bragg--leemen
the Valu
rule (B3), which states that the absorption of alphawr aye
in a
odium onalsting of a single alont
to the square rot
/ a,
*
of the atata
is proportional
weight of that element, or
w,i/Zwei
When applied to minerals or materials consiating of two or
more elements,
where da R 0.001226 p/a3
and 760 m fg.
density of dry air at 150 c
d
density of a single elemnto
d
density of mineral or aggregate.
z
stoatsM
y
S
fraction of first element in compound.
atomic fraction of second element in compound.
*0.* ate.
W18 ** ge
S
MtgzttiW 1z6%
atomie night of first eleent.
2 a stoats weight Of second element.
8to sum of the atoio fraction times the
*qawe root of the atomie nights of the
chemieAl constituents of dry air,
*
lsesawn (C0*P), found that the stopping power of an
atom is proportional to its atomie number raised to the
two-thirds power within the limits of small velocity varia-
tion,
The Bragglnsmn rul
lead to allar
and the flasson rule bot
results for many elsmnts.
l9W
APPARtAIUS
A single alpha-ray travelling one sentImter in air,
at the ed of it.
path will produee a chargr of approximately
It the ehargr Is passed through a high
3 a 10014 eoulamb.
resistane a masurable potential dIfference will develop
aeross
the resistance. This potential applied to the grid
of an eetrale
ter tube, spectally designed for low grid
surrent, will
aste a current pale that can be detected
by a senltive ballistic galvnometer.
The Umionsation ohsaer used in this work was dasigned by P?
(see pig. 3).
K# Nurley for thiek saure alpha-ray counting
It has a steel cylinder wall one-half eenti-
noter thick, is f3 eentimeters in diameter, and 10 centiasters deep,
The steel oylinder is based and capped with
sheet brass and saled to prevent leakage of outsi4e air
into the chamber*
The base of the chamber, which is placed
on an open wooden stand, has an opening of 1
eentimeters
diameter into which a copper source plate fits snugly.
source plate base is
The
aM in positin by a threaded axle
and ciap ating as a jac*.
The spur" plate Is A popper disc
-
0
20 -
10CM
SCALE
3p
To
VACUUM
Figure 5.
PUMP
Ionizatiomi Chamber and Electromneter Tube
14,3 centimeters to tineter, or with an area of 160 square
*entimtms, is insulated from the base plate by seas of
a bakelite dins one-half eentinter thifk, romed two millimters deep to serve both as a reeses for the copper dine
ant as a retaining %WU for the samplo,
te souroe plate ia
maintained at a potential of plus 45 volts, while the base
plate Is g
together with the other oxternai parts of
the shaOMer
In the chmber a spee grit of
opper winr
is
maintained at a fltentlat of plus 45 volts with respect to
the ehamber walls and colleeting gig, to drive the ions
from the ni
emission
may frm the eollecting grid ant
these from the senoeamission toward the collecting grid.
The eontrol git
of a gene*l Slc trio ?P-64 electrometer
tube is directly onnooted to the olleeting grid, which Is
placed parallel to the scude
mste
from it,
a
a ietatnee of one enti-
This grid is entristed of parallel copper
wires one centimeter apart and
te circular to conform to
the geometry of the sureo.
the boo .f the lienation chamber Is provided
with an intlet at* entlot for nitrogen gas.
Nitrogen gas,
preferably stored for one month or lenger to avoid radon
ontamination, is ciroulated tirogh the *nber at ateo-
- 22 -
spherie pressure,
The nitrogen flow is regulated at a rate
ush that the clamber pressure rise is negligible, and that
the flow is sufficient to eelnte eateld
air fram the
chember,
The
ollecting grid In the lonisation ohaber leads
through a inaite plug into a vaeu
tight brass cylinder
housing the PP44 tube as shown In Figure So
resistanee to ground is 800,000 negeesa
has an outlet, with a
mn
Iary
is eenneted to a vema pump,
The grid-leak
The brass cylfnder
ter and stop-oosk,
whiah
It is neessry to keep the
resister in a Ta"uem at all times to
prtevui ersgs fnm seflieting an the resistor and tube,
The brass eylAter 1 shielded fre eleotroagnetio disturbses by a
qutsite Ira 41Mwd.r
Th balaneew
elreult of DWbridge and Brown
(Del) was used with slight modiisatias as show in
Pigure 0,
The et1ralt is essentially a Wheatatone bridge
with a b4Iiatis gslvaom~mter serving as a null indieator.
An Aryton shunt is placed across the galvanameter to vary
its sensitivity,
freN
A uupply voltage of 12 volts is drawn
low diseharge type of storage batteries housed in
-43
FiLgure 69
PP.454 Bridgb Or1Pidt
t
w
a
00Molmil
IV",
Pnlamnat awret
7Iemnat
tltage
Plat* Owrent
*Plato Voltage
Swaeen arid OurrIt
RSISfl VALU S
TALM"0
*Swen Grid Voltage
Qontwfl GrI Voltags
Mutual cOatain
Suappy Voltage
90 ma
2*5 Y
26v
/A
so
tub./v
% 64
1M O
*frm lw potatial aut of
tlassent
Rl
R2
s 300,000 megoeb
alm var.
3 * 50
* 50 om ar.
14 a 10 ohm var,
R6 * 76 ehm var,
a 8 oe var*
00hm
bo
a5000 *oe
Rg * 4000 eta
fig * 300 bsa var.
Ry
RIL3
R14
R13
R15
* 0)0 oea tar.
a 10,000 elmo
* 5000 olm
'8000 Os
* 2000 oho
-
shielded containers,
gol
It is laportant that all exposed
parts and wires of the ounting apparatus be ahtlt34.
Approximate values for weesstanes and voltage
drops in the etreUlt are give in Pire
64
Setting. for
the balne point vary ftr sob iaivtgual aleotrseater
tube,
All potentials given we MeaSured frm the low
potential eSe of the filament,
The sireuit is desigd
to make the plate current tedependent of smail ehanges of
battery voltage.
S-romm mom
d prese
r
baantau g the cireuit
s ae flleesi
U. St up elriuit as indieated in Figure 6
Adjust 4g s that tilnt
mates g0 milipern,
the ery I
a
t aa1mlmito Onto
*, g, gR
S. Uing a potentiseter n*aure the plate
potential, amn
tipo nta, ocatro grid potential,
e IrO
at plate entrent. v the plate current
to bem
pSO
it anM
be tooleased to this
yalue %winesiag t* filant
current ant at ta aa
to maintain e06
tim a1ging respeetiV reit
tUbs voltages st keeping tO galventamter cm scale. it
the plate
enersw 0 e0 tlnse to be less the 60 mieroampere
seem whe the tileant
rrat Is
milliampne
above
rated vale
the tllat
emissoen it to law and should be
Senuts (S-I) reoumment
iaNreeseg by aea
Oppiseatia of 6 to
volts srmes the filament for an
4. O
erve galv
nter Lefleetlans as a function
It a misim 'is not
or .ilament, en
t hnVaryin Rg
reasen, nes# galvaneter senativity to explore defleetian against filament earnat over geater ranes. Change
fllament current l steps of 0.5 milL ampea waiting
e25*M
three uInutes between readings for thermal .quflibrim to
be s&Otbad
go g8, ng .g first in 3 ela step
then in 04
Oba, stepa ad repeat ntfl, teirMt
inma
'Is ebtaint,
Ut the baes
mAltt
o", n nt 'I" I the Opaatng
rang
of the
ina0.11mn
111ee
whne#-1asa1
na repeat ebeervttenIe
t
6, TrIMase Ot
g, Rg and Ri have UttU
.fttnt on the Oireult at
give ed
plate
at grp potentalso, t mao be used, hoeW
to "ter
Galvaa
iOally,
-be
teflefteere
reeowdt
phetographe
A ballistie galvancmter ea a vtbratie-preqt
eting was
a
Light tight by
nrsbiang &0oelfe
ataight filament lap MnunteS on a earriga
slowly by a seew
was moved
thratdriven by a tsleohren zotor,
The
light frm the lap reflected frem thq marror suspension
of the galvanantur
dae
to the
esorting emrs.
to the teleekron moter
n the light
mierAwwiteh was planed at the nt o
galvaMstew mirrr with a roa leng0
need and the rfleted
To prevent
serftg,
its traverse.
a
A
of -n Meter wa
Uight was peasd trough a eardboard
housing to a boelsental slit
of 0.6 sflliseter on the face
of the resording earners honing.
The needing ,baera need has been described by
Sna
swans (Pal),
drum*
Yats sOMra *onaisted of a laminated estAr
ieuws wits an* It Lobeb In diamter mounted an a
stool shaft t
g
fa,
and goreg to a WeI
osar aligning ball bearings
metor.
Six inch breadde eenleien
photographe paper was usedtp The recordig desa was housetd
in a sasunite box.
seh pulse prodtuied by an alphaMpartIle
sharp deflAotla
galveneuter rtn
of the gavnwmetw,
to the a00
gav
a
the tesa of the
position w
abaractor-
istisally expmnential and was ontrolled by th value of
the gridtleak nesater,
!he reoew4 therefore, was a series
of sharp risiag and testying pulses, the naser
eould be onated to detertmm
of whiah
the eftivity of the sapI,
The speed of tin 24ht soeue and the camera druM
enld be entrolled at varos Inown rates by proper gear
ratios,
Th* camera drum was driven at one revolution per
hour and the light sowrne teaerse t the wdth of the drum
in In boaro,
ing,
making possIbIe It hours of ocntinUuus reeorA-
mbUR
T
Rae esperimantal pcoblnm in essene nao te
aeeu-
rate MaSUMnt of alpha amslon into a halt space from
a sit material of kpha
astiflty, The aalupptia
wa
ae etly verified, that the deteetabl.
siesta Ire a flat sarfae at & palmisd
te sene as pdteS frtm a hypnthetlal
face of the material
pla
Aetually thn
stn
material was
pIso
frm
so1
esl
a polibed
surfae was net testede largrly due to the etatement
by Evans atd
(0-B), that polishing apparently
Intredne eantles
emery, wetanably owing to heating
snd wmesansel dIwturbenesof the skin Apt during ph6lskt
lng, The nasured emission was then to be correlated with
the actual
knom activity as a test of the Dragg-fleeman
bserptia
rU
applied to materiale of couples atruc-
the saleetim Of material for this work was governed
by the availability In qmntity of samples that had been
aeonrstely analysed for uranium and thefin cOntent, and
that hwA a range of aetivitles and warying theiua to ureia
" 28 o
ratio*,
ad
ed a
0n
Sampin of magptite jawaIft
(F-4) for g
analysed by awly
"logiage masuranants were saint-
fUlfflliug the reqrento,
These aaUles had betn
analyswl by seperate radAn And thran maosuramnts404).
All of the waotitos used were pure mineral separates ground
to pass 3 mesh and retaned by 180 mesh soreens,
The use of a mene-miralle soure
interpretaticn of the sbrptin
aided the
of the alpha-rays,
The
testing of the thery was held primltpafly to masuremnte
of samplas of the single mineral magetite varying in stU
vity, as it was felt that a sl g1e *am aseunately tosted
would be better than nevrl cases poorly tested,
The ap-.
pliaabfltty of the mthad to other mnerals was then
checked ter the high density uairal, galena
anM multi-
aineraitto sample reprasented by a ground dibam,
This
latter was en of the atandard rook saples prepared by the
Burrnu of Standards and enalyed for radioativity by several
laboratories (0-2),
The aborption of that pftla
of baea
n
alpha-
rays acing fram the area evered by the source had to be
evaluated indireetly,
13ab rcnt rune using the copper
. 2a
seuaeplae
ant auboequetly with a rather
witboat a nwaree
rttntively l
Sa*mite sample (02)
t stade
eMMf
aUate
that a relatIvely largeOf
reamet
thee opper anteeu plate mid that the true sadbar
as satuefly about Mo alpha-se ate per iee whn
nas covetge
90 sAph&*4*wte per hor
hebaeagr
the plate
or .prozaflely
ttM
entirely by a .. pU,
elsn
without a sample,
Thi
h4gh
c oud have been rotund by pre-unaurew
mento of the steel aMt bras, but materials at the tinm
mse not retdily available,
ns th sao1tiity of a ftll plate acute
(10
it
cenimtl ) yte1et a ernnt en4eeding 200 per how
bean diffoint to rnlve
the
teleusl
phtewahit 006* This nnseesttt
eneient sterl
palmse
.qn"m
n the
a saanch far a
of low alpha Stvity that could be
usS as a blank to radise the area of the source a knmon
amnt.
tartan
abet mterials mute oeparet for alpin-
astivity against damite ad it was fon
natural subtane Ino
of
as motals, glan, hard rubber a
asbastos were too setive to be usable.
leat-t wed more paeiss,
that produs
eat ener
lesat aotivity of the ample triad.
OhsMal
distil-
I"al liite had the
bweme
abnwmal
fleafetotns mw e eporlanoed with lutite
galvnoma
during the balaming of the eteotrmntar irnit ad during
This offeet ne probably due to the high restatsAs
rims.
aoh
of lueite allowing the aattn
edges.
0oattng the
oentet
.ntirely eUlsinate ifl
that a blank of material with
reasonably low resitivity woui
A matertal was aoqgt
feee of an almiman tie,
that caMd
aghty andi e
of such a tbksn
to ab"arb
Chemloafly preparet
&
The swfae of tin dine was oleaned
was allenst to flow a
oufrace, After the "oledlon
triad the emSmS
along the elgos was removed with aseoene.
to
be appLied to the
to be low in alpha activity and 4ssept-
able for this purpose,
ta
be nnessary.
alpha-rage ftm the tin.
eolledian was f
probably due te n
tin IOie e4ge. with "Aquaae
Tms, it was cOnolde
mot of te
ie diffioulty# but did not
th reaso no
inability to oampletely surfo.
tag',
ad edges with niMWr
urfate
ol1 'Aqustag" n*Ilim0v goat Ot
along contaot
wface the almdmm
dis
vr
the
$oliodioc
It ws
tine sry
with a oaating that was
suffilently thiek to alpha-raya during the initial application sine
it was not possible to use susesivi layers.
A seating Ot 0A*
fluster
was used ant found to be suffi-
otently Ithik to abarb all alpha-rays due to the a
n
di...
An indireet method of determining the alpha-soativity
of the ealldia
disc will be dessribed later.
A further
W 51
-
ocnideration of the accuracy of this calibration demanded
thtat the alpha-aetivity af the collodion di.
stant, E
eme cano was takoa to avoid contaminetLon or
eamted blank when
chipping of the colledie
storing,
aen
rain
,alng and
After the dins had been In use for a umnth Ab
surface was reeated with fresh coLUedIan and it was femS
that no differn"
in alpha awtivity resmlted.
was conoluded that thrOUg
Thus it
proper *ato the activity of thi
blank will remix constant for a reasonable length of tim*e.
The
magetite was placed in the eour*e plate and
zarefully sraped 10ol.
end after eaeh doeter
Bankground rms we
ticn,
made betore
Each sample was rn
for 12
hours and all baokeganmd runs for 10 b~tts.
Probable errors wore
uted from the root neon
square of the roeaduAle r from tin aritkmetic man of the
hourly counts and are expressed in torus of the probable
error
E of the
M tr
Pa S t 0ne74S
a unit observations
of
+e+a
obeu+t*o
heen Is the number of heow* of observattn
tae
1
takanL, ,
SIne the tta
ne up of the sm
alpha activity ot a sSOple is
of a* tivities due to the eleats
of
thn uranitu 1, satneuaiuusand thrIum series it WOO
ecnvetat to aen t the total
eseunt to a stn4e
aOtivtty rAIN.
lier (11w4) gn
0040 * 0(00S as th3
atiO of the sativity ot Ihe astUneweAte
tO the urentaM
series, when radientiv. equilibria aits,
tbat, the
total activity 4u. t th three reaioetiwveries an be
capresset in term" of an equivalent rutium plus thria
emntet. this sa een be evaluated fren Squatin 10 by
Oputing the absolute thsio
C emisin in the haU
span obn th
absorption fatr/fA
* I = wa
fron qyatit 10 the alpha euiBSmt aIg per sweo
Tus,
per
square eatister wtfl tr
gg + OfU
A1. a g(CQIt
the traites I estat
radie
t24 + uomCR%
U? en be
}
I0A
oeverted to sn equivalent
estent R&grs per gra of aoxee, when in equilt
brium, by the
UV
esrsn
A-
OwI'
-- It*a 02*6 a IS a.......
e$5.
f UZ in Iquation 14 the absolute
fubtitUating this value
will be
tipha enta
a't
a0289 x 1012 Ra + 0,02968 x 100 Th .. *,(16)
*
Thus, if I denotn the fraction of total alpha-rays whieh
are due to the uranivu I and aet ino-uraniua seies, ar
(14) as tI
fraction due to the thoresa series, the fraetin
L
M.
#
o*a *.4,w....1#.n1.(l7)
0.000 R& + 0.00000 Th
tins the total
pha
unt
ill
give the alpha oount due to
the uranina I and atin*urania series a1 *ne,
Mii
12
Reta ral=
stat
Th a Uamwemi
eentent in IC 1 2 gSra
in 10
In this *ase
gr= per gran
of
per grao of
mag mgmg#eemmt
The first group of anaIs** wie
made using the
fNil eurme area of 100 square sentimtere,
Twive nagn-
tite amples were measured for total alpha aetivity art tho
results are tabulated in Table 2,
he to lack of resolution
9w
ol6'o0
69
Salo 0
05
IL
'9
9*8 T n'Lzt
U
t
-to
>
T 0-61
lot
'9
11
at
WCo
it'o
56
is*o
Ga'o
6*
at
OI
0-1
96X
#6
#6
01
ot-o
oirt
00
'I
,JL
*Oka
aty
p1
61*O0D
WO
as
3'
it
O. O
s6'x
*19
it
1
#900
~6
'S
a,
8L *0
&to
*
O~' tilt
9-1
6*
&'
Rollo
0006
L'-01
0
0.t1t) 4)000
Sro
4Lo0
a00
IVt
o'S
a
t
'-U
(*a
at'
(a)
(L)
(9)
(6)
flhy *"A"
(1)
(a)
(t)
T1aa el
foeO
f
qITy
WtagS
a
*IgW
e 36 4
of sin4.
alpha-ents
hiSb baali
above BOO *aott per har amd a
ad# te full sownm
of low aetiutg (ptly
was lmited to saplea
0.30 a
1Cr12 gs p a per
gram of sone)
The total 4,phs
osmnt mluded the aetivity dn
to the ohmmbaw bakpgrwmtt and the sours,
as listed In oolnma 4# Table 2 *s
served bmekgreuA with ellaon
lng a magnetit
snalysts,
thp lu
an avmaep of te obblank
t
T-he bakground
prlooding and tollow*
bnkroad was nade up of
the activity of the coflodion
blank~ An tatiract aathed was used to determine the aflTity
attnlhuted to tin eaodion as follaws,
the total alpha
count was arrse
gon
s
the coflo1ec blan)
by an
h
bawdb
msagat te
nidn
resulting total ount low
t eqal to the alpha esnt due to the oolled ion
blank# A plot of these *ants Against the knon activity
In a umWber Ot dffe
t aples
gave a sme* Intereapt equal
to the atovity of the oefletlaa
in ceder to utfltse
me aetessaWy to
the aa,
anPlas of hghew activity it
rens the area of the souree,
To reduoes
a 90 degree esfer, sehined aoarately, was
removed from anoete blank disc, and the thre-quarters
reimainig
of tin Also
as eated with ollodien.
This
method of reduing the ara wee used to maintain Simaer
S36
a
eastry tow the emisnson Outward frem the oirmferential
edge.
Proeures
full soure.
er
identieal to thee
uned with the
Th results are tabulated in Table 3* Colma
5 shows the total alpha eents per hour emittet froe the
soures after eerneeting fWor hambe
sorreoting for oldian
hour due to the uranutt
lited In solm 7.
aflhvity,
beelrgovnt, but before
alpha sounta per
11
series alone per grm of soure is
the vnuns obtained In solma 7 arn
plotted In Pigura 7, ulieh daclose that the alpha sounts
per hour for an ursnzm value are tow by C alpha **unts
per bow* This vain of 5 alpha asunto per hour is attributed to one-fourth of the total edlodlio
aetivity sine
for these deter.
only soe-fourth of the area was removd
Thus, thn ativity due to tie fIll colled in
minatloas.
dies Is 20 alpha onmte per hour or 0,125 alphe per hour
entUeter.
per square
Linear
t
b et
n At AMa 40",0U0
The full aoures*masuronants gareaveated for
the 0ooledion activity (Tb.
thrm
sontribut
3 and 0 wo
S#Oelnae 5 aM 0) and the
removed (ol umn
).
Samples
ub
analysed fur both the full source and the
t
6e
*Vg/pO j So utwt squ pnoO et@vq *stld t/T 4os
14
6(
Ott
.
90'11
116*0
0S
6z
lea
rt
6'ini
68*0
£1
9 1'11t
c0*m1
(L1 6-0
T 1'06
a*t; £ *ts
It
Li
6o
19*0
'*1 o*,'91
a'
lt
AT
10
'it
'o
oo
EO
I
11#0
sease
atung
gfi
Sets.. a "SO$ A
6ens.
s/no
a"
wazeo
(I)
01
6L
oL6'o
IL
6's I
t'ta
at
36*0
oi
0*60
Wtsoo
'I
Slob
94oAno0uft
i
LL
at
E9'
s
L6*6o
196-0
011
I
it
'I
IL
ot"
Saes a
esta(6 A)
(4)
(1)
wezS tee
(9)
()
'etc *'in
(EL
(U)
p szfa4-fe0 * POMP*% 0eS0
-So
at
(1)
09/10
SitMOT
K3 IV
* 14
(i)
£ent&
sine WqOW 1n04
ntese
-a
-
~
-~-
100
c75
0
x
.
z
20
0
< 21
Figure
7.
Collodion Blank Activity Determination
One-fourth Area Data.
mget 2%urvw~uo wfldwn
nnS,*twn .'4 uD mnunOv
*g9 .atn
pit (6 VuulPo)
PfljTdT;tbU @40s
eS*4m3;; eom
pane
UT wmnaxd *&TV eIT"soa 0i4
atUo "ano
qsad htunoo sqd~w g ;c
o;uum Li A
mAnn'4 uaTp
ecanaw z4Ja;."nOa mq; 'Lawnug~l 0-9 .wnu UT wncrrd (93
umntoo) Usirn e' a" Weaoq Jed **=Wo wqdt 0$ jO 44Ta;~tn
punoS#.vq x0foEe
8
*'tqfl U '4V
'naw
nwMO
vwu*#s'sq*#4 JOJ PflflAfl
1XVn trt mg,04 '04na
sejuo
W%~ eJzo
ooew o% q4ja Lnjaeul; pwnzw wn*otqvwnp
je .xeqwnu oq, ;wq;4 i'rn mq!
ivrn s""q (g nlq'i) wisop
PUg' '3 01
WMr
Lleuzxo
4flSWU
pn*irq~..
tutu
aw"T
SKJ jo 't
RU;A T
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nt
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it
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t'o
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s fs-e
swa wqfly inn
-me;suutwnn %
at
x' IN' wi~v
as/s
ot
v"t
(9)
sT Teinn
(1)
ta
Er300
O
0
I.
w
0.
<n
F-200
z
D
0
U
0.
.J
<
100
0.3
0.4
0.5
RA X 10-12
Figure 8.
0.6
0.7
0.8
0.9
1.0
1.1
GRAM PER GRAM EQUIVALENT
CIalibration of Ionization Chamber
.42.
thet 00 X 10442
dra rudis per
be higher then tby
snmpon. T
It
of souree tedd
gem
shutd1 far the given vaia
*n amn of this dirop
my "l be d* to erranas
ftr the
ay is not kwnk#
alae
to
for the saples
but
* 43*
-
Y
sn alpha sistaen as given by th. slope of the
Our" in FlUMe
& sheet
wthis
e%of
prdioted eiasten fram antite,
ounts ag per sna
u series alam
0
The nuMbe
of alpha
per square sentmter doe to tan urat
was obtalnt frm quation 11
f(4
The maluef
the theoret Jel
a 0041 x 10$ V1
faw
.....
,.
... (l8)
tite (W$4 4 ) as derivat by the
2008 x 10*
taregmkleeea wale (see Nquatian 12) .
per sble mtiaste,
The trani
gr-
sntent U! gam per
gract sOf UP" was sangSt to the equivalent radius content
by the ecversia
VI a 2,84 x 10$
sannmtia of the reage f&
serIes ar. gives in Table 5,
(
the wrets
xa 3i-2).
The
I and aetsoenaanism.
Uag thse Valus, a full
scuree plate of aagnetIts centaisIng 1,0 x 10-12 gram
redImr pew
am of
seis should emit
sesw in
3i
eqIn aflia with the uraniws
alpha-rays per howe.
From the curve
is Figure 0 it to sees that the aetual nission was
ggs
9
#04 99O 4 04 U 0
*(I-)
so 04" SuIqnusq ot Sipsenw peSqSln so'U pas 4qs
owa
*oyv
1se W0"pen;.me O..
-seisn ft eua ecu t
a
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a l
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*se
14
f g tva
e45e
ania 4t
23|m
-tril
dgt-ig&
RaKing ohksed the
tor the singl, mineral
ragg-flnman rule withia 4%
aetite,
a test was made on the
high denIty uinersl, galla, art on a mineral agprgate,
diabase, as a rhook an the general applicabilIty of the rule.
A eampe at gaiena ant a saMple of tranSs
diabae
analysed by separate radon amt thorn masurmnte
measured under tin esu
results ar
Table 0.
conditions as the
mntit.
The
tabulated in Table 6.
bisssion Neasurements on Salena and Diabase Samples
*Rbe-*J AT
Saqlau Anj
ala
e
40
o' /9%w
4/
Ooor.
Dun,
040 (0.1
Diabase 100
0.18
T
*t
P
NoRt
for
USeries
1St,2 A 1,5
66
66
0.974
64
2.4 31,T * 1,8
61
101
0w396
40
tea
alpt^ mtssion for the galena and
diabase was computed frem Zquation 18, using the same method
as was wed for maneite.
A''e
cmputed by th
galena (PbS),
The absorption of the SOuree,
Braggrlenn
is 430 x i-3
ra
rule (quation 12) for
per oubis centineto, The
Table 7.
Comptation of /V d for Sttandard Triansie Diabase
nal Analysts,
from Oh
(1)
Ches.
Genetttuent
(2)
(8)
Prac tional
Cnntra-
tion
+ yaw2'
(4)
WIl
(1) x (5)
SlOg
05206
60,06
4,81
2#41
A1203
0,1875
101,94
4,67
0.73
P0203
02
PNO
0.0124
159.70
8,44
0.08
71,85
8.71
0#45
4,56.
030
4,60
0.10
5488
0,08
0,000
Mao
0,1106
C00
-.08
0.0219
E20
0*0068
5g0
0.0000
18.016
Te02
Others
0.0115
79,90
40192
&*6
a
386
0.02
5-,74
0,07
0.0080
a 4.82
*fd.
*
Q
4ta
WA
Se squatin
12,
1.64 X, ar 3 Sw/*oa
W47 vasEieftf 4 for thi
tadrard triassie diabase was camputed
from its ehaisal analysas as shon
n TabUe 7.
It was
ibtu that the difterent a nsala in the 4tabae had almost
the saw etivity, (How),
problem.
whih greatly sImplified the
Diffisultios wofd ares in ease
where the ati.
vity was emoontrated in minerals with aborption differing
fraf the mea.
The method used in Table 7 for the emputation of
f 4 fO
nots'*ieb
lazle
reagrswfates is laborious. A simpler
is suffitlently accurate, is to use the aveqr
age mineral oasn~ittst of the aeurot,
A Rosial analysIs
of the
abasn shwamed that the reek was cmposed of folds.'
par 46%,
promsm fl%, and minor minerals (magntite, etc.)
4%,
Computatione oft4
using the average mineral compo-
sition of the diabase gives -a result in agreement with the
value computed from the cemical analysis of the rock as
a whole.
The theoretieal ulph
emission of the magnetite,
galena, and diahass is givn in Table S.
It is seen, thus
that the thia*eet Of predicted and obserted emission in
etch ease is withIn 41,
The results obtained indieate that
thick sOnee emission *an be reliably interpreted in a wide
range of ma$erials,
if the absorptice of the material is
taken into account according to the simple approximation
fli4S
OGasparleen of aOlnulatet
Sample
aw
9.A5
t.08 a Icr 3
0.40
4. 30 x
0.16
140
1. 54 xIr03
1.0
Galena
Diabase
103
"&#iA a 0.911 x 103 fa
for
tot
2.04 z 10-
1.14 x 10"i
0.5
Walscion,
* Cal. a
vi
g/
160
40
Magnet ite
and Obervd Alpha
10-4
400eies
as.*
ort
V keies
316
49-
teate
In this wart,
flgew# 9 is a plot of alpha cants
par hoW per
qanr aatntor
of /4 rangin
fra
autor,
fins thiak oures for values
1.0 to 500 x 10*
rs
per subio eatle
$2.01
Li
Q.
1.50-
o
o/
00
0.$0
U
Figure
0.2
0.3
0.4
0.6
0.7
0.8
0.9
1.1
1.2
0
0.1
9.
Deoendence of aloha emission of equivalent value of Ra in
equilibrium with urani-um series on/f d for thick sources.
RA X 10'
120.5
1.0
GRAM PER GRAM EQUIVALENT
1.3
1A
-
- 51
SUMM
A low-voltage ionisation ohamber for aounting
alpha-rays from solid sourses was used to test the thnorettoally predicted absorption in sources thick compared
with the range of alpha-rays.
Eagnetite samples which had
been previously analysed for uraniu, artd thorium content
were need as standards to determine the alpha emission as
a function of the activity of the soure,
It was found
that the absorption earretion was reliably provided by a
of A d for the aioue that was suggested by Drag
valu
and
leman, namely
dasame2a*iii
f44k
+ 7+12 1 +
Za
whores
a density of mineral or aggregate.
da X density of dry air at MAr 0 and 760 a Hg.
2 sui of the atomie fraction x the square root
of the atouie wight of eonstituents of dry air.
x a atooic fraction of first element in compound.
y a atomic fraction of seornd element in compound.
*..*....
etc.
- 52 0
x atomic weight of first element,
W2 a atosie weight of
econd elemnt.
et@,
p......
Three materIes were testeds
Eagnetite, fvd a 2.08 z 10 ogs/em5
A t : 4.30 x 10r 3 pa/em 5
Glna,
Diabes
* 4 * 1.54 x
34 ga/e 5
In eaca #ase the Observed emission agreed with the predited
emission within 4%.
Thn measuremente required an eacurate knowledge
of the true bekgrA
analysis.
rof the ionisation ohamber during sash
Due to the large area used for the seuree the
baokgrounM aetivity oentrlbuted by this area ocu34 not be
neglected.
When using thifl
from thia ar*
soures all alpha activity
is the aetivity due to the radioactive con-
tent of the soure.
An aluninum disc oSted with coiledian,
Which was found to be of relatively low activity, was used
as a blank saure for baekground dleerminations,
The con-
tribution of alpha counts by the olladion blank to the
total bavound was determined indireetly by measuring a
number of samples of different activity and extrapolating
the calibration curv, to ser,
The ionisation cebar was constructed with a
to
ntinatter. It was touat that
mane ana of 200qu s
ta
ne
.'aM be tflem& enu for materia* OntaInIg
p gte irentm
u.se the Z4O z
of the ltivl4nl
alpha
s*to per hat
fhue
hal
mnUt
fse h4geo
nd o eqtt
gpa
se
4, t
dies enters,
of area rndtintt
nGMt seo in
gfa
Cnim
muree,
valUes Vt noa
The netuntia
*I** to *ea
that this
It wa fat
i4ps e1 four or swo time
Mro
sttive tU
the
seMud be eanreS.
neater ne teat to be
*e ame
in
propntaaAl redUAtia
of eetivity of the Sal anne
to operate aNA #we
latl n
mos
of atout fl.
by eUttAng tn bourn
0 ewpia
boutte. Is thsJ ng
lit
ients
the n"
useossary to
pe
Sw to the look er "
*qRILWJA with Ito wn,
nos ntfly
3-
ta-eune
SA
seantrs
of
54 a
-
R3hLIOGRAPIY
(A -1)
1. Jr., (g58)
*AM spplltiso Of
abilutts to the ounting of alpha-prtiele,
Phyw. Rnv., vol. 44, pp. 8M1 - 653.
(5O 1)
tsass
0., (14) "00#tribatla
n
m
2,
ut WS1Aetivity in aninat sftset
*~ Geol. So.,
Am*, Ball,. ve, 55 pp. 13* a 1864.
(8 - 2) R
e, ft. V., (191) *A n tabl of values of the
geneal physteal onatants", ReV. Pod. Pihys
vol
(3
3)
2)
a
* 23
20
kaga W, ., and Keenan, IRo, (1905) "Alphaparticles of radium, and their loss of rang# passing thret
rins
a
m and aoleoule", Phifes,
Mag., vol. 10, pp. 318 - 334,
(0
(Q
u
1) OorkQ.M. (1948) "Radioattwity ant Nualear
P0*,
was
.,
A*,
Owrtin, 1., P7,, e~a
0.~ bvarik, A.?F. teit,
-
8.
01
Pgt,
Go S., andftas,
AfW,
"Aetivt standard* t,
pp. 02 s 65*O
(D - 1)
(z
-
R.
D.,
Sol*.,
(M9O)
vol* 238,
Dufridge, L. A*, and Sromi, H, (193Z) "t An improved
D, 0. ."p111ag
enutt*, ReV. Sol. Instruenats,
"ol. 4, pp. $3* - 5W,
1) uvana, D, (19M5) 'Appatas for the deteruinaties of fate quantithes of radiUm, vae#. and
thoron in salds. Uque
and gases', Ren, 0St.
I
pp*
.112.
(1%V2)
twins, . . ~
da
0., (144) Alphabeltup mes4frod'tersniag geologi* age."
Plya. Ren,, vol. 4l , pp. 214
22.
(1
van, A. D., and 4ootmau,
of roeeks", Geol. So. Ame,
490.
5)
(B - 4)
twans, R, D., GoodM*
and Urry, W, D., (19$9)
0, (1941) "Radioaotivity
Bull,, vol. 52, pp, 49g, Ke#vil, N. B., Lane, A, C.
Ineralbration and ccc-
S55
s
pariaon in two labratortes ot aasurements ineldaet
to the detaenatntla of the gooleegal ag. of
rooks" PaY*. ReVl , Vol 56, pp. 931 - 946,
(3
- 5)
Da R. De, and )ugu*el,
(1936) "Inlront
g my naitivity of tube counters and the
measumnts of the theriws ontent of ordinary
natorials, Rv, Sol, Inastrvnnt., vol. To pp.
r. A.,
41 - 449.
(E a 6) Evans, R, D., and usher, i. V., (1934) "The nature
of statistLal flue tations with applications to
osmio rays", Phys# Rev*, vol. 46, pp. 14 " 151,
(F o- 1)
Finoy, 0, D, and StVns, I. D, (1938) 'The radioactivity of solids determinod by alpha-ray oount-ing", Phyb. Rev., vol. 48, ppo 503 - 511.
(0 - 1)
Geler, 1,
(0 - 2)
lason, J. L.,
nasber', PlIls
(0
a
3)
and Mareden, S., (1913) "The law* of
dflexen of alpha partieles through large angles"
Phflna Mag4,v vol. 25, pp. 604 - 623.
(1922),
"Stopping powr
and atomis
Rag,, vol. 43, pp. 477 w 481.
oIano 0, (194)) "(Mologloal applI*ations of
noslaar physics", Jour
of Applied fhys., vol. 13,
pp. 276 - 289,
(0
- 4)
(1
1)
(a - 2)
0o
,4, and Ivan*s R. D,, (1941) "Age measreomenta radioaetivity , Geolo SO*. As., Bull,
vol. 52, pp. 491 O 544,
4
Harper, 0. 14, and Salaman, E., (1930) Wnsurments an the rangs of alpha-partiles*, Royal So*,
Laten, Pr,, wvol 1n A, pp. 175 - 18.
.
eten,
%, Lnd
Lewenee,
range of the alpha-partiole
Rev,, vol. 6, pp. 46 - 47*
G. C.,
(1937) "The
from thoriu*,
Phys.
(K - 3)
Kweny, 0.,- ad ?anath, F. A., (1938) *A Manual of
RadiootlvIwty", Oxford University Press, London,
(a
Holloirq,
G#., and LIvingoton, K. S, (1938)
J"R . and speeific ionization of alpha-particles'
Py.
ev., voL. 64, pp. 18 -57
a
4)
a
56 -
(- 5) Holes, A., and raneth, P. A#,
(1938)
"Helivzn-.
ratios of rooks and minerals", Royal So,., London,
Pr., vol. 154 A, pp. 123 - 150.
(H - 6)
Hurler, P, M., and Goodman, C., (1943)
"Helinn
age mesuremnts I. prliminary magnetita tez'",
Go
See, AA, Bull,, vol. 54, pp. 305 - 324#
(H
-
7) Harley, ,. ., and Goodman, C0., (1941) "HeliUim
retention in sann rock uinerals", GOol. So*, Am.
Bull., vo4 62, pp. 545 - 560.
(K
a
1)
Kovarik, A ?., and Adams,
r.
I., (1938) "The
disintegration onstant of thorium and the branahing ratio of Th 0", Phya. Rev., vol. 54, pp* 41$ a
421.
(S - 1)
W, P
(1934) "Radioactivity of neodymium
and saariun , Phys. Rev., vol. 46, pp, 196 a 204,
Libby,
(N a 1) Nier, A. 0,1 (1939) "The isotopic oonstitution of
uranium end halfalife of urAnt Isotopes', PhVs,
Rev., t1. 55, pp. 10 - 153.
(
- 1)
(R
(R
1)
a
Pontoeorro, B., (1942) "Radioactivity analysis of
oil well
nUs," GeOphysies, vol. 7, pp* 90 0
Rasetti, F., (1936) "UIMesnts of Nuclear PhysicO",
Prentie Hall, New 7ork a pp. 116 - 117.
2) Rayton,
'to Mo,
and Wiln., T, R., ,(1987) 'A Wilson
loud ohamber Investigation of the alpha-partlolea
from uraniu', Phs. Rev., vol. 51, pp. 818 a 825.
(A - 3)
useel, W, L, (1944) 'The total gamma-ray activity
of sodlmentwy rooks as indlatod by Geiger Counter
deterxinatIons", Geophysets, vol. 9, pp. 180- 2160
(n
Rutherford,
a
4)
E4, (1911)
"The scattering of alpha
and bets partiCles by natter and struoture of the
atom", Philos, Mag., vol. 21, pp. 669 - 688.
(R - 5) Rutberford, E4, rynn illias, G. ., Lewis, 7, 8B.,
and Bowden, Bo 1., (193) 'Analysis of alpha-rays
by an annular magnetic field", Royal So*. London,
Pr,, vol. 1M9 A, pp. 617 - 67.
a 574
(3 a I)
(i
- 1)
Spencer, R., at Schulz, L, (1945) *Behao6r of
a balanood D 0. amplidr", Rev. Sai, Instruments,
vol. 14, pp. 10 - 14.
Urry, W. D,,
(1936)
"Determination of the thorium
and radium oontant of rooks", Jour. of Chew. Phys.,
vol. 4, pp. 34-" 48,