|_. B. LIPSON
Feb. 22, 1949.
2,462,270
METHOD AND APPARATUS FOR PHYSICOCHEMICAL ANALYSIS
Filed Sept. '7,‘ 1943
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F I G. 3.
INVENTOR
2,462,270
Patented Feb. 22, 1949
‘UNITED ‘STATES PATENT OFFICE‘
2,462,270
METHOD AND APPARATUS FOR rnYsIoo
CHEMICAL ANALYSIS
Leonard B. Lipson, Arlington County, Va.
Application September '7, 1943-, Serial No. 501,499
7 Claims. (Cl. 250—83.6)
1
2
tron bombardment chamber comprising a pref
erably rectilinear box I having walls formed of
This invention relates in general to certain new ‘
and useful improvements in methods and appara
tus for physico-chemical analysis and more par
ticularly for the determination of hydrogenous
materials in soil samples and the like.
an inner relatively thick wooden ply or layer 2 and
an outer ply or layer 3 of cadmium foil, cadmium
plated metal, or other radiation absorbing ma
terial, the top wall t being centrally provided with
aperture 4. Interiorly the box I is substantially
Soil and similar substances containing minute
quantities of hydrogenous materials cannot be
accurately analysed by ordinary schemes of
chemical analysis in the absence of time-consum
ing attenuated procedures. It has been experi
mentally established, however, that materialsv
which contain hydrogenous substances produce
measurable nuclear reactions when bombarded
10
by neutrons. Neutron particles are not deceler
ated or otherwise materially a?ected by heavy in
15 practically all of the neutrons which would other
?lled with paraflin wax p recessed to provide a
tion between external size of the chamber A and
the size of the sample well 5, is such that there
will be a substantially thick mass of paraffin
surrounding the sample well 5, and consequently
organic molecules but even minute amounts of "
hydrogen atoms, however combined or chemically
associated, will slow down the neutron particles. -
The number of such slow neutrons bears a statis
tically direct ratio to the amount of hydrogenous I:20
material present. Thus by bombarding a sample
with fast neutrons and measuring the quantity
of slow neutrons resulting from inelastic colli
sion with hydrogen nuclei it is possible to de
termine within desirable limits of precision, the
- amount of hydrogenous material present.
central rectangular sample well 5 extending up
wardly and opening to the aperture 4. The rela
2.5
Such
analytical procedure has been found to be entirely
reliable and de?nitive as well as being exceed
ingly rapid, simple, and e?icient.
It is therefore a principal object of the present .
invention to provide a ‘simple rapid and de?nitive
method for the analytical determination of hy
drogenous substances and apparatus for carrying
wise escape from the chamber are absorbed. The
few highly energized neutrons which succeed in
passing through the para?in are, of course, ab.
sorbed in the cadmium foil layer 3.
‘
"
Extending laterally from one of the vertical
walls of the sample well 5 is a tapered recess 6
provided at its apex with a preferably brass cap- ‘
sule 1 containing a beryllium-polonium mixture
or other suitable material constituting a source
of fast neutrons. Extending laterally from the
opposite wall of the sample well '5 is a short con
necting passage or channel 8 preferably having
the same cross sectional shape and area as the
opening of the tapered recess 6, and communicat
ing with a somewhat larger compartment 9, one
of the side walls of which is provided with a rela
tively large removable section 10 held in posi
tion by means of screws H or other suitable
fastening elements.
Suitably mounted within the compartment 9 is
It is also an object of the present invention to 35 a neutron counter tube 12 having suitable leads
provide compact and economical apparatus for
l3, l3’ extending through the walls of the box I.
bombarding a sample containing- hydrogenous
For this purpose I employ a self-extinguishing
material with fast neutrons and measuring the
tube of the Geiger-Mueller type suitably charged
resultant quantity of slow neutrons. In the
with a nuclear reactant, that is to say, a substance
v40
drawings (one sheet)
containing atoms of low atomic number capable
Figure 1 is a lengthwise sectional view of a
of emitting alpha particles of relatively high
chamber for bombarding a sample with fast neu
energy when bombarded by neutrons. I have
trons and detecting the resultant quantity of slow
found that boron tri?uoride is a preferable type
of nuclear reactant.
45
Figure 2 is a diagrammatic representation of a
Shaped for snug ?tting disposition within the
preferred form of apparatus for the analytical
upper portion of the sample well 5 is a closure
determination ofhydrogenous substances in ac
plug l4 consisting of a two-ply wood-cadmium
cordance with the method of the present inven-v
member [5 matching the wall in thickness and
tion.
materials and provided at its outer face with a
Figure 3 is a diagrammatic representation of an 50 semi-circular handle "5. On its under face the
alternative form of indicating mechanism asso
member I5 is provided with a, para?‘in wax plug
ciated with and forming part of my present in
I1 having a length su?icient to extend down
vention.
through the sample well 5 almost to the level of
Referring now in more detail and by reference
the upper marginsof the tapered recess 6 and
out the same.
neutrons.
.
,
characters to the drawings, A designates a neu 55
the channel 8. Sized for removable disposition
within the sample well 5 is a rectilinear sample
container I 8 formed preferably of brass or other
suitable neutron-transparent material, all as best
seen in Figure 1.
The lead 13 issuing from the chamber A is
connected to one input lead of a high-gain linear
ampli?er, B and to ground. ‘The lead I3’ is
4
terms of ratios. Once the particular ratios and
other constants for a given piece of apparatus
have been established against absolute standards
and the apparatus accordingly calibrated it is
thereafter possible to interpret readings or re
cordings so as to obtain accurate and positive
analytical results. It will of course be recognized
that the methods andalpparatus of the present
connected through ‘the resistor 'l'9?toea source of
finve‘ntl‘oni-areviapplicableito it wideirange of ana
high voltage and‘ is also connected‘t'hroug‘h‘the 10 lytic'al problems‘. However, there are certain
capacitor 20 to the other input lead of the linear
types of analyses to which such apparatus and
ampli?er B.
This source of high voltage is main
tained below the threshold voltageof-the‘ counter
tube l2 so that such tube 12 will countdnly‘h‘eu
trons and will not be affectedby extraneousrae
diations such as cosmic rays, gamma rays and
the like. The output leads'of‘theilineariamplie
‘methods are uniquely well suited, such as for
example, the-analysis of soil samples in geophys
- ical “exploration.
In the course of exploring a particular section
of the earth’s surface to determine the character
"an'dty-pe df‘petroleum deposits Which may exist
?er B are connected to the input leads-ofjthe
in theunderlying strata it has become a recog
multi-vibrator C and the output leads of ‘the lat
nized technique to takes]. multiplicity of soil sam
ter are in turn connected to an electro-me 20. ples at uniformly spaced selected points over the
fchanical recorder ‘D preferably of ‘the recording
typefan as ‘shown in Figure 2.
" fI'f‘d‘es‘ired an instantaneousrecording‘system
'a‘re‘a'in ‘a ‘sort of ‘grid-work pattern. Thesam~
stances is carefully‘mulled or ground to a sub
lines of subterranean .oil deposits.
pies are‘thena'nalyz'e'd to determine the presence
of
hydrocarbon materials for the reason ",7 that
‘may ‘be employed - by substituting,‘ along " the line
"there'is a direct‘rélation'between the‘fquai'itit‘y'of
‘It-TI; in the‘ circuit shown in Figure 2, a pulse 25 hydrocarbon materials and ‘the presence of se
'int‘égra'tor‘E and ‘any suitable type of direct‘read
troleum products in the ‘underlying strata; In
‘ing instantaneous recorder F connected as shown
fact ‘it has been ‘round that 'by taking a fairly
diagrammatically in'Figure 3. '
large number of samples and plotting the ‘relative
‘In performing an analysis a sample of soil or
quantities of‘hydrocarbons "present'in the various
‘other ‘material "containing hydrogenous sub 80 samples ‘it is-possible ‘to delineate the boundary
'
stantiallyvmiiform state of ?neness and dried un
Although these principles and geophysical vre
der carefully controlled moderate temperature so
lationships have been established in practice,
as'tofr'e'move'alltraces of ‘moisture. It'is essen
suchgeophysical surveys and explorations have
‘tial' that the‘ sample be thoroughly dried inasmuch 35 been hampered by dii?culties in available-ana
as water‘ is‘itself an hydrogenous substance'and
'lytical methods and apparatus with which the soil
‘would "introduce substantial errors int'o ' the ana
samples canfbe analysed. The hydrocarboncon
lytical result. Either before or ‘after drying‘th‘e
tent of any 'given sample is very minute and
sample is packed ?rmly but not tightly into-the
beyond the limits of accuracy or ordinary labora
sample container i 8. ‘Because of the danger of 40 tory ‘methods of chemical analysis. ‘Inaddition
contaminating the sample with water vapor
to this the hydrocarbons which are present take
picked up from the atmosphere, it is preferable
the form of complex wax-like polymerization
that the sample be packed into the container E8
lproducts, which are not readily susceptible ‘to
prior- to ,drying. ,Whe'n ,dry the sample ‘is
analysis ‘by the usual l-acidimetric-alkilimetric or
weighed and then placed within the sample 45 oxidation-reduction
‘methods. Finally a survey,
well 5.‘ "
of
a
relatively
small
section of territory will
(The stream of fast neutrons issuing from ‘the
result in many hundreds of samples so as to
neutron source 7 will} pass through the sample
require rather extensive analytical facilities if- the
and, depending upon the presence of hydroge
samples must be analys'ed‘by usual routine meth
nous material, a certain number of the neutrons
ods. For 'this'reason such geophysical explora
will be slowed down and the composite stream
tion and vsurveys "are ‘extremely costly and rela~
of fast’ andslow neutrons ,will pass through the
tively slow.
,
‘
,
_
channel '8 into the compartment 9. ‘The neu
‘The
methods
and
apparatus
of
the
present
in
trons will register upon the counter tube i2 and
vention however make it possible to run geo
create impulses which will pass'throug'h the‘lin
physical surveys of the type above described
ear ampli?er B, the multi-Vibrator C andibe re
quickly and- at comparatively small cost. Be—
corded by the recorder D. Itnis of course obvious
cause
of the rapidity, and accuracy, with which
that where the instantaneous recording‘system
results maybe obtained ‘it is [possible to send a
shownrin Figure 3 is used the impulses from the
survey crevvdnto the ?eld‘to take samples over
counter will be visually noted rather than per.
manently recorded. By reason of the fact that
the statistical probability of a nuclear reaction
between a neutron and the atoms of the nuclear
reactant such as the boron atoms of boron tri
an initial gridpattern in ‘which the samples are
widely spaced and thus “.“rc'iugh-in”1v the geophys
ical characteristics o'ffth'e area.‘v Ther‘eupon, the
crew while still in the ?eld vcan be directed to
certain- selected areasiin which a ?nergrid-worlé
?uoride, .for instance, is, many thousand times '05 pattern
will'b'e employed 'an'dia greater number
greater in the case of slow neutrons than in the
of
more
closely spaced samples taken.
this
case of ,fast neutrons, ‘thenumber of fast neu
secondary phase ofithe operation the 's'peedk’an'cl
trons which will aifect the counter tube 12 "will
simplicity of the present methods and apparatus
represent only a few-thousandths of one percent.
arezhighly important. Not only_will-the, results
However, the apparatusfmust be. initially cali
of
the ‘survey be known Jalinost .‘as soon asthe
brated against carefully standardized samples
sampling crew is finished'faking'thésamfples‘but
since each‘neutron source lwillliproduce a neutron
any striking ‘deviations wiii's'how'up. "'rhesegde
stream, "of unique intensity. Furthermore the
viationsmay result from actual geophysical'idio»
counting ‘of. neutrons ‘isstatistic‘al rather ’ than
metres. or: iiiaymésjiilt?forn "some
absolute and therefore'is measurable only ‘in 76 syn'crasie's
error in 'sampletalhng. “In either‘ case‘ it‘i‘s'p'osl
2,462,270
5
sible to have new samples taken in such instance
so that the results may be checked or corrected
without the great expense of sending men back
into the ?eld many weeks after the original survey
6
?lled box having a chamber for receiving a sam-‘
ple to be analyzed, a recess opening into the
chamber, a source of fast neutrons within the
recess, a channel extending outwardly from the
opposite side of the chamber with respect to the
recess, a compartment communicating with the}
channel, means in the compartment for convert
methods and apparatus of my present invention
ing into electrical impulses, the slow neutrons re
in the analysis of soil samples as an incident of
sulting from the reaction between the fast neu
geophysical exploration has been described above ' trons and the hydrogenous material, a high gain
10
it should nevertheless be understood that such
linear‘ ampli?er connected to said means for
use is merely illustrative and that my invention
strengthening said impulses, a multi-vibrator
is not limited strictly to the geophysical ?eld but
connected to the ampli?er for lengthening said
is applicable with equal speed and precision to
impulses, and means connected to the multi—
practically any type of analytical situation where
vibrator for recording said impulses.
it is necessary to determine the amount of hydrog 15
6. Analytical apparatus for the determination
has been run.
Although the previously described use of the
enous material present in a sample and various
changes and modi?cations may be made where
of the amount of hydrogenous material in a Se
lected sample, comprising in combination, a wax
different types of hydrogenous materials or dif
?lled box having a chamber for receiving a
ferent operating conditions are encountered
sample to be analyzed, a recess opening into the
without departing from the spirit of my inven 20 chamber, a source of fast neutrons within the
tion.
recess, a channel extending outwardly from the
Having thus described my invention, what I
opposite side of the chamber with respect to the
claim and desire to secure by these Letters Patent
recess, a compartment communicating with the
is as follows:
_
channel, means in the compartment for convert
1. The method of determining the amount of 25 ing into electrical impulses, the slow neutrons
hydrogenous material in a selected sample which
resulting from the reaction between the fast neu~
comprises completelydrying the sample, inter
trons and the hydrogenous material, a high gain
posing the dried sample in a path of fast neu
linear ampli?er connected to said means for
trons, and measuring the reaction between fast
strengthening said impulses, a multi-vibrator
neutrons and the hydrogenous material in the 30 connected to the ampli?er for lengthening said
sample by imposing the slow neutrons‘ resulting
impulses, and an electro-mechanical recorder for
from such reaction upon a Geiger-Muller counter.
recording said impulses.
2. Analytical apparatus for the determination
of the amount of hydrogenous material in a se
lected sample, comprising in combination a wax
?lled box having an internal chamber for receiv
ing a sample to be analyzed, a lateral recess
opening into the chamber, a source of fast neu
trons within the recess, and means for counting
7. Analytical apparatus for the determination
of the amount of hydrogenous material in a se
lected sample, comprising in combination, a wax
?lled box having a chamber for receiving a
sample to be analyzed, a recess opening into the
chamber, a- source of fast neutrons within the
recess, a channel extending outwardly from the
the number of slow neutrons resulting from the 40 opposite side of the chamber with respect to the
reaction between the fast neutrons and the hy
drogenous material.
recess, a compartment communicating with the
channel, means in the compartment for convert
ing into electrical impulses, the slow neutrons
of the amount of hydrogenous material in a se
resulting from the reaction between the fast neu
lected sample, comprising in combination, a wax 45 trons and the hydrogenous material, a high gain
?lled box provided with an outer layer formed
linear ampli?er connected to said means for
of radiation-absorptive material and having an
strengthening said impulses, a multi-vibrator
internal chamber for receiving a sample to be
connected to the ampli?er for lengthening said
analyzed, a lateral recess opening into the cham
impulses, a pulse integrator connected to the
3. Analytical apparatus for the determination
ber, a source of fast neutrons within the recess,
and means for counting the number of slow
neutrons resulting from the reaction between the
fast neutrons and the hydrogenous material.
multi-vibrator, and an instantaneous‘ recorder
connected to the pulse integrator for indicating
said impulses.
LEONARD B. LIPSON.
4. Analytical apparatus for the determination
of the amount of hydrogenous material in a se 55
lected sample, comprising in combination, a wax
?lled box having a chamber for receiving a
sample to be analyzed, a recess opening into the
chamber, a source of fast neutrons within the
recess, a channel extending outwardly from the 60
opposite side of the chamber with respect to the
recess, a compartment communicating with the
channel, means in the compartment for convert
ing into electrical impulses, the slow neutrons
resulting from the reaction between the fast neu 65
trons and the hydrogenous material, and means
for recording said electrical impulses.
5. Analytical apparatus for the determination
of the amount of hydrogenous material in a se
lected sample, comprising in combination, a. wax 70
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The following references are of record in the
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