Chapter XXXI
Radioactive Decay
The ejection
of space or time displacement by an atom which becomes unstable for one
of the reasons that have been outlined will be identified as radioactivity
or radioactive decay, and the adjective radioactive
will be applied to any element or isotope of an element which is in the
unstable condition. As has been brought out, there are two distinct kinds
of instability. Those elements whose mass exceeds 236, either in rotational
mass alone or in rotational mass plus the vibrational mass added by magnetic
ionization, are beyond the over-all stability limit and must reduce their
respective masses below 236. In a fixed environment this cannot be accomplished
by modification of the vibrational mass alone, since the ratio of vibrational
to rotational mass is determined by the prevailing magnetic ionization
level. The radioactivity resulting from this cause therefore involves
the actual ejection of mass and the transformation of the element into
an element of lower atomic number. The most common process is the emission
of a helium atom, or alpha particle, which gives it the name alpha
decay.
The second type
of instability is due to a ratio of vibrational to rotational mass which
is outside the stable zone. In this case ejection of mass is not necessary;
the required adjustment of the ratio can be accomplished by addition or
emission of electric rotational displacement, which converts vibrational
mass into rotational mass or vice versa and thereby transforms the unstable
isotope into another isotope within or closer to the zone of stability.
The most common process of this kind is the emission of a beta particle,
an electron or positron, and the term beta decay is applied.
In this work
the alpha and beta designations will be used in a more general sense.
All processes which result from instability due to exceeding the 236 mass
limit (that is, all processes which involve the ejection of primary mass)
will be classified as alpha radioactivity and all processes which modify
only the ratio of vibrational mass to rotational mass will be classed
as beta radioactivity. If it is necessary to identify the individual process
such terms as ß+ decay, etc., will be employed.
On first consideration
it might appear that the observed characteristics of radioactivity are
incompatible with the origin of this phenomenon as deduced from the Fundamental
Postulates and outlined in the foregoing discussion. This derivation clearly
requires radioactivity to be an explosive type of action, initiated as
soon as an aggregate reaches the limit of stability and continuing as
a single event until the atomic transformation is complete. The observed
radioactivity, on the other hand, apparently consists of a series of independent
events occurring at random within an aggregate and in many instances extending
over a very long interval of time. The explanation of this seeming inconsistency
is simple, but it will be more convenient to introduce it at a later stage
of the discussion, and for the present we will turn to a consideration
of the details of the basic radioactive processes.
In analyzing
these processes, which are few in number and relatively simple, the essential
requirement is to distinguish clearly between the rotational and vibrational
mass. For convenience we will adopt a notation in the form 6-1, where
the first number represents the rotational mass and the second the vibrational
mass. The example cited is the isotope Li7. A negative mass
will be indicated by parentheses as in the expression 2-(1), which is
the isotope H¹ This system is similar to the notation used for the rotational
displacements, but there should be no confusion since one is a two-number
expression while the other is a three-number expression.
The neutron mass
has the same single unit value (one-half unit on the natural scale) which
characterizes the vibrational mass and like the latter it is purely magnetic.
it is therefore interchangeable with the vibrational mass. The mass symbol
for the neutron is 0-1. The relationship between the neutron and the rotational
vibration of an atom is the magnetic equivalent of the relation of the
uncharged electron to the electric charge of an ion, as discussed in connection
with the subject of electrolysis.
The first of
the basic transition processes which we will consider is the direct addition
or subtraction of pure rotational mass. Since each unit of rotational
displacement is equal to two units of atomic mass the effect of this process
is to increase or decrease the rotational mass by 2n units. The
rotational combination with n = 1 is the H² isotope, which is unstable
under terrestrial conditions, and the ejected particle is normally the
first stable combination, in which n = 2. Emission of this particle,
the He4 isotope, 4-0, results in a change such as
O16
-> C12 + He4
16-0 -> 12-0 + 4-0
In any location
where the magnetic ionization level is zero and the H² isotope is consequently
stable, the emission of H² undoubtedly takes precedence since the smaller
unit has the greater probability, and in such an environment a forced
disintegration of the O16 isotope proceeds in this manner:
O16
-> N14 + H²
16-0 -> 14-0 + 2-0
Since rotational
vibration exists only in conjunction with rotation, units of vibrational
mass cannot be added or subtracted directly except by a change of the
magnetic ionization level, but the equivalence of the neutron mass and
the vibrational mass makes it possible to accomplish this objective by
adding or withdrawing neutrons. Thus we may start with the mass 2 hydrogen
isotope, the deuteron, and by adding a neutron obtain the mass 3 isotope.
H² + n¹ ->
H³
2-0 + 0-1 -> 2-1
Similarly the
ejection of a neutron leaves the mass 1 isotope as the residual product.
H² - n¹ ->
H¹
2-0 - 0-1 -> 2-(1)
Inasmuch as the
rotational vibration is a displacement of the same kind and direction
as the magnetic rotational displacement itself, the only factor which
permits it to exist as an independent vibrational entity rather than becoming
merely a component of the total rotation is the lack of motion in the
electric dimension. Addition of displacement in the electric dimension
therefore has the effect of converting vibrational mass to rotational
mass. One unit of electric time displacement is required for each rotational
displacement unit, the equivalent of two units of atomic mass. Addition
of one unit of electric time displacement thus results in the conversion
of two units of atomic mass from the vibrational to the rotational basis.
This can take place either by the addition of a positron or by ejection
of the inverse particle, the electron, as in the reactions
H³ + e+
-> He³
2-1 + e+ -> 4-(1)
H³ - e-
-> He³
2-1 - e- -> 4-(1)
Elimination of
one unit of electric time displacement by addition of an electron or removal
of a positron reverses this process, increasing the vibrational mass by
two units and decreasing the rotational mass accordingly.
These are the
basic growth and decay processes. The actual course of events in any particular
case depends on the situation; it may involve only one such process, it
may consist of several successive events of the same kind, or different
basic processes may combine to bring about the required result. In natural
beta radioactivity a single beta emission is normally sufficient as the
unstable isotopes are seldom very far outside the zone of beta stability
and alpha stability is not involved. In natural alpha radioactivity, on
the other hand, the amount of mass which must be ejected usually amounts
to the equivalent of several alpha particles. The loss of this rotational
mass by successive alpha emissions necessitates beta emissions to restore
the equilibrium between rotational and vibrational mass. As an example
we may trace thb various steps involved in the radioactive decay of uranium.
Beginning with
U238 which is just over the borderline of stability and has
the relatively long half-life of 4.5 x 109 years, the first
event is an alpha emission.
U238 -> Th234
+ He4
184-54 -> 180-54 + 4-0
This puts the
vibrational mass outside the zone of stability and two successive beta
emissions follow promptly, bringing the atom back to another isotope of
uranium.
Th234
-> Pa234 + e-
180-54 -> 182-52 + e-
Pa234
-> U234 + e-
182-52 -> 184-50 + e-
Two successive
alpha emissions now take place, with a considerable length of time between
stages, since both U234 and the intermediate product Th230
are relatively stable. These events bring us to radium, the best known
of all the radioactive elements.
U234
-> Th230 + He4
184-50 -> 180-50 + 4-0
Th230
-> Ra226 + He4
180-50 -> 176-50 + 4-0
After another
somewhat shorter time interval a rapid succession of decay events begins.
Half-life periods in this zone range from days down as low as seconds.
Three more alpha emissions start this sequence.
Ra226
-> Rn212 + He4
176-50 -> 172-50 + 4-0
Rn222
-> Po218 + He4
172-50 -> 168-50 + 4-0
Po218
-> Pb214 + He4
168-50 -> 164-50 + 4-0
By this time
the vibrational mass of 50 units is well above the zone of stability,
the center of which is theoretically 43 units at this point. The next
emission is therefore an e- particle.
Pb214
-> Bi214 + e-
164-50 -> 166-48 + e-
This isotope
is still above the stable zone and another beta emission is in order,
but a further alpha emission is also imminent, and the next step may take
either direction.
Bi214
-> Po214 + e-
166-48 -> 168-46 + e-
or Bi214
-> Tl110 + He4
166-48 -> 162-48 + 4-0
In either case
this emission is followed by one of the alternate kind and the net result
of the two successive events is the same regardless of which step is taken
first.
Po214
-> Pb210 + He4
168-46 -> 164-46 + 4-0
or Tl210
-> Pb210 + e-
162-48 -> 164-46 + e-
After some delay
due to a 22 year half-life of Pb210, successive emissions of
two electrons and one alpha particle occur.
Pb210
-> Bi210 + e-
164-46 -> 166-44 + e-
Bi210
-> Po210 + e-
166-44 -> 168-42 + e-
Po210
-> Pb206 + He4
168-42 -> 164-42 + 4-0
The lead isotope
Pb206 is within the stability limits both with respect to total
mass (alpha) and with respect to the vibration-rotation ratio (beta) and
the radioactivity therefore ends at this point.
The unstable
isotopes which are responsible for natural radioactivity in the local
environment originate in two ways: by past or present inflow of matter
from regions where the magnetic ionization level is zero, and by atomic
transformations initiated by high energy particles such as those in the
cosmic rays. In those regions where the formation of matter takes place
on a major scale all of the 117 possible elements originate in the proportions
established by probability considerations. As long as the magnetic ionization
level is zero these elements are all stable and there is no spontaneous
alpha radioactivity. If this matter is then transferred to a region of
higher magnetic ionization, such as the earth in its present condition,
the stability limit in terms of atomic number drops because of the addition
of vibrational mass originating from the magnetic vibrational motion,
and radioactivity is initiated.
Whether the earth
acquired the unit magnetic ionization level at the same time that it assumed
its present status as a planet or reached this level at some earlier or
later date is not definitely indicated by the information now available.
There is some evidence which suggests that this change took place in a
considerably earlier era, but in any event the situation with respect
to the radioactive elements is essentially the same. They originated in
a region of zero magnetic ionization and either remained in that region
while the magnetic ionization increased, or in some manner, the nature
of which is immaterial for present purposes, were transferred to their
present location, where they have become radioactive for the reasons stated.
The other source
of natural radioactivity is atomic rearrangement resulting from interaction
of the material atoms with particles of other types, principally the cosmic
rays and their derivatives. In such reactions stable isotopes of one kind
or another are converted into related unstable isotopes and the latter
then become sources of radioactivity, mostly of the beta type. The observed
reactions of this kind can be duplicated experimentally, together with
a great variety of similar transformations which presumably also occur
naturally but have been observed only under the more favorable experimental
conditions. We may therefore combine our consideration of natural beta
radioactivity, the so-called artificial radioactivity, and the other experimentally
induced transformations into an examination of atomic transformations
in general.
In essence these
transformations, regardless of the number and type of particles involved,
are no different from the simple addition and decay reactions previously
discussed, and the most convenient method of describing these more complex
events is to treat them as successive processes in which the reacting
particles first join in an addition reaction and then subsequently eject
one or more particles from the combination. According to some of the theories
currently in vogue this is the way in which the transformation actually
takes place. This seems rather improbable, at least as a general rule,
but for present purposes it is immaterial whether or not the symbolic
representation conforms to physical reality and we will leave this question
in abeyance. The formation of the isotope P30 from aluminum,
the reaction which led to the discovery of artificial radioactivity, may
be represented as
Al27
+ He4 -> P30 + n¹
26-1 + 4-0 -> 30-1 -> 30-0 + 0-1
Here the rotational
motions of two separate particles combine and the total motion is then
redistributed in a different pattern. The two phases of the reaction are
independent; that is, any combination which adds up 30-1 can produce P30
+ n¹, and conversely there are many ways in which the 30-1 resultant of
the combination Al27 + He4 can be broken down. The
final product may therefore be some such combination as Si30
+ H¹ rather than P30 + n¹. It is even possible that the decay
process may restore the original mass distribution Al27 + He4,
although energy considerations normally favor a change of some kind.
The usual method
of conducting these transformation experiments is to accelerate a small
material or sub-material unit to a very high velocity and cause it to
impinge on a target. In general the degree of fragmentation of the target
atoms depends upon the relative stability of these atoms and the kinetic
energy of the incident particles. For example, if we use hydrogen atoms
against an aluminum target at a relatively low energy level we will get
results similar to those produced in the helium-aluminum reactions previously
described. Typical equations are
Al27
+ H¹ -> Mg24 + He4
26-1 + 2-(1) -> 28-0 -> 24-0 + 4-0
Al27
+ H¹ -> Si27 + n¹
26-1 + 2-(1) -> 28-0 -> 28-(1) + 0-1
Greater energies
cause further fragmentation and result in such re-arrangements as
Al27
+ H¹ -> Na24 + 3H¹ + n¹
26-1 + 2-(1) -> 28-0 -> 22-2 + 6-(3) + 0-1
This general
principle that the degree of fragmentation is a function of the energy
of the incident particles has an important bearing on the relative probabilities
of various reactions at very high temperatures and will have further consideration
later.
In the extreme
situation where the target atom is heavy and inherently unstable the fragments
may be relatively large and the process is known as fission.
The difference between this fission process and the transformation reactions
previously described is merely a matter of degree, and the same relationships
apply.
Although it is
possible in some instances to transform one stable isotope into another,
the more general rule is that if the original reactants are stable the
major product is unstable and therefore radioactive. The P30
isotope, for instance, is below the stability zone; that is, it is deficient
in vibrational mass. It therefore decays by positron emission to form
a stable silicon isotope.
P30
-> Si30 + e+
30-0 -> 28-2 + e+
In the fission
reactions of the heavy elements the products often have substantial amounts
of excess vibrational mass, and in these cases successivee-
emissions result in decay chains in which the unstable atoms
move step by step toward stability. One of the relatively long chains
of this kind that has been identified is the following:
Xe140
-> Cs140 -> Ba140 -> La140 ->
Ce140
108-32 (19) -> 110-30 (19) -> 112-28 (20) -> 114-26 (21) ->
116-24 (22)
The figures in
parentheses refer to the vibrational mass corresponding to the center
of stability as calculated for each element from equation 137. The original
fission product Xe140 has 13 excess vibrational units and is
thus far outside the stability zone. Emission of electrons converts successive
2-unit increments of vibrational mass to rotational mass, and on reaching
Ce140 the excess has been reduced to two units. This is within
the stability margin and the radioactivity therefore ceases at this point.
The foregoing
description of the atomic transformation processes has been confined to
the essential element of the transformation, the redistribution of the
primary mass, and the collateral effects have either been ignored or left
for later treatment. In the latter category are the mass-energy relationships,
which will be considered shortly. The electric charges carried by some
of the reaction products are not particularly significant as they are
merely an alternate means of absorbing some of the reaction energy which
would otherwise go into translatory motion. Even this effect is only a
temporary one as the charges are soon converted into kinetic energy. Absorption
of energy by neutrinos is likewise a collateral and transient phenomenon
which has no direct bearing on the primary process. Unlike the cosmic
ray neutrinos, which are actually produced in the decay processes, the
neutrinos which carry off part of the excess energy resulting from atomic
transformations are pre-existing particles within the material aggregate.
When translational energy is liberated at any particular point it can
be acquired by any unit which is present; not only time units, atoms or
sub-material particles, but also space units, electrons or neutrinos if
rotating, photons if not rotating.
The atomic transformations
which have been discussed thus far are primarily exchange reactions, in
which some of the motion of one of the participants is transferred to
the other, or fragmentation reactions, in which one or both of the participants
are broken up into smaller units. Another class of transformations of
prime importance in the general mechanism of the universe is the addition
reaction which was mentioned briefly in the discussion of the basic processes
by which the atomic rotational systems are modified.
Direct combination
of two multi-unit atoms is not impossible, but it is difficult to accomplish.
Because of the inverse gravitational action in the time region there is
a strong force of repulsion between the two structures when they approach
each other. Furthermore, each atom is a combination of motions in different
dimensions and even if the two atoms have sufficient relative velocity
to overcome the repulsion and make effective contact they cannot join
unless the displacements in the different dimensions reach the proper
conditions for combination simultaneously. The product of a reaction involving
n units of this kind therefore normally consists of n or
more particles, and this type of reaction is not available as an atom
building process, except to the extent that the mass of the larger component
can be increased without reducing the total number of particles, as in
the reaction
C13
+ He4 -> O16 + n¹
12-1 + 4-0 -> 16-1 -> 16-0 + 0-1
Where the hydrogen
atom is employed as the incident particle the situation is much more favorable
for combination, since hydrogen has only one net unit of displacement
and only one dimension of combination is involved. We therefore encounter
many reactions such as
Al27
+ H¹ -> Si28
26-1 + 2-(1) -> 28-0
The 1-1-1 particle
which is equivalent to hydrogen is still better adapted to participation
in these addition reactions and it is possible that some of the transformations
attributed to hydrogen are actually the work of this anonymous and rather
elusive particle. The atom builder par excellence, however, is the neutral
member of the 1-1 family, the neutron. This particle is essentially nothing
more than a unit of magnetic rotational time displacement, and as such
it adds readily to any material or sub-material combination. A well-known
example is
U238
+ n¹ -> U239
194-54 + 0-1 -> 184-55
Neutron absorption
is a spontaneous process requiring nothing more than contact with the
material atom, and the large kinetic energies commonly used with other
bombarding particles are unnecessary. In many instances slow neutrons
are actually more effective than fast neutrons, since they spend more
time in the vicinity of the target atom. The source of the "raw material"
for atom building will be discussed at length in a later section. At that
time it will be shown that this building material is preferentially produced
in the form of neutrons, and neutrons are therefore available in large
numbers in those regions in which they are stable; that is, in regions
of zero magnetic ionization. It will also be brought out in the same discussion
that the primary units from which the neutrons are produced originate
uniformly throughout space, and although the presence of matter has some
bearing on the conversion into neutrons the greater part of this activity
takes place where most of the primary units are produced; that is, in
the vast expanse of inter-galactic and inter-stellar space. It follows
that this open space is the primary atom-building region, the location
in which most of the light elements are assembled.
A secondary atom-building
process is simultaneously operating in the regions where the magnetic
ionization is greater than zero. Here the neutron is outside the zone
of stability and the equivalent stable particles, the neutrino and the
positron, are formed instead. The positrons, although inherently stable,
are short-lived as they are so easily absorbed into the rotating systems
of the atoms. The neutrinos are normally magnetically charged as produced
and they add to the constantly growing neutrino concentration which determines
the magnetic temperature. Unlike the neutron, therefore, the neutrino-positron
pair makes no immediate contribution to the mass of the system. Sooner
or later, however, the continual additions to the neutrino population
bring the magnetic temperature up to the next higher ionization level.
Magnetic displacement is then transferred from neutrinos to atoms, increasing
the rotational mass of the latter, until the equilibrium point as defined
by equation 137 is attained. The atom building in these regions is therefore
a delayed-action process rather than an immediate event comparable to
the absorption of a neutron into the existing atomic system.
The relative
abundance of each element in the original product is a question of probability.
Conversion of the neutron to hydrogen is a relatively simple matter but
anything further requires the making of the proper kind of contacts in
a region in which the particle density is so low that contacts of any
kind are few and far between. The great majority of the atoms therefore
never get beyond the hydrogen stage. As would be expected from probability
considerations, helium is in second place. Beyond this point the atomic
rotation enters a stage of greater complexity and the individual characteristics
of the elements affect the probabilities to some extent, but in relatively
young matter we can expect to find a rather small proportion of heavy
elements and a general trend toward a decrease in relative abundance as
the atomic number increases.
Following this
very early diffuse stage of the existence of matter comes a further long
period of time spent in various stages of aggregation. Here neutrons are
still plentiful as long as the magnetic ionization level remains at zero,
and while the production of hydrogen is small compared to that occurring
in open space, the building of heavier elements from the lighter ones
goes on continuously. The proportion of heavy elements therefore increases
with the age of the material aggregate. Although the relative abundance
of the different elements is still determined by probability, the abundance
curve is more irregular because the distribution of the total rotational
displacement between the electric and magnetic rotations at the higher
levels introduces some complexities. We have no satisfactory means of
determining the relative proportions of the elements in the younger aggregates
but we can get a good idea of the situation by examining the terrestrial
abundances, which are representative of a somewhat later stage of development,
as indicated by the unit magnetic ionization level.
Let us consider
the 2B group of elements, for example. The first three of these elements,
sodium, magnesium, and aluminum, are formed by successive additions of
electric displacement to the 2-2 magnetic rotational base, and all three
are among the moderately plentiful elements in the earth's crust. Silicon,
the next element, is likewise produced by a similar addition and the probability
of its formation does not differ materially from that of each of the three
preceding elements. Another such addition, however, would bring the displacement
to 2-2-5, which is unstable, and in order to form the stable equivalent
3-2-(3) the magnetic displacement must be increased by one unit in one
dimension. The probability of accomplishing this result is considerably
less than that of adding an electric displacement unit and the step from
silicon to phosphorus is consequently more difficult than those immediately
preceding. The total amount of silicon in existence therefore builds up
to the point where the lower probability of the next addition reaction
is offset by the larger quantity available to participate in the reaction.
As a result silicon is one of the most abundant of the post-helium elements.
The situation
with respect to carbon, the equivalent element of the next lower group,
is not clear, as the relative proportions in which the light elements
are found under terrestrial conditions are not very significant in application
to the universe as a whole, and the stars give conflicting testimony.
At the midpoint of the next higher group is the iron-cobalt-nickel trio
of elements, and iron, the predominant member of this closely related
trio, conforms very definitely to the theoretical expectation, being even
more abundant than silicon.
When we turn
to the corresponding elements of the 3B group, ruthenium, rhodium, and
palladium, we find a totally different condition. Instead of being relatively
abundant, as would be expected from their position in the atomic series
just ahead of another increase in the magnetic displacement, these elements
are rare. This does not necessarily mean that the relative probability
effect due to the magnetic displacement step is absent, as all of the
neighboring elements are likewise rare. In fact, all elements beyond the
iron-nickel group exist only in comparatively minute quantities. Estimates
indicate that the combined amount of all of these elements in existence
is less than one percent of the existing amount of iron.
It does not appear
possible to explain this situation in terms of the probability concepts.
A fairly substantial decrease in abundance compared to iron would be in
order if the age of the local system were such as to put the peak of probability
somewhere in the vicinity of iron, but this should still leave the ruthenium
group among the relatively common elements. The nearly complete elimination
of the heavy elements, including this group which should theoretically
be quite plentiful, requires the existence of some much more powerful
factor: either (1) an almost insurmountable obstacle to the formation
of elements beyond the iron group, or (2) a process which destroys these
elements after they are produced.
There is no indication
of the existence of any serious obstacle which interferes with the formation
of the heavier elements. Laboratory experiments indicate that neutron
absorption and other growth processes are just as applicable to the heavy
elements as the light ones. The building-up of the very heavy elements
is endothermic, but this should not be a serious obstacle, and in any
event it does not apply below Group 4A and it therefore has no bearing
on the scarcity of the 3B and lower division 3A elements. The peculiar
distribution of abundances therefore seems to require the existence of
a destructive process which prevents the accumulation of any substantial
quantities of the heavy elements even though they are produced in normal
amounts. In the next section it will be shown that an independent line
of reasoning based on the existence of a limiting value of thermal energy
also leads to the same conclusion.
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