Adam When?

    Thus far in our study of the secular evidence that relates to the age of the earth, we have seen that the oceans potentially offer great help in tying together the secular and sacred records. Not only do they reveal, from many standpoints, the impossibility of an earth with an age of billions of years, but they point rather dramatically to the truth that the earth is only thousands of years old. Thus, the evidence produced from a study of the oceans meshes consistently with the trustworthy record of the Bible which gives us a date of 11,013 B.C. for the creation of our earth.

    What about other dating methods? Do they show an earth age of four and a half billion years? Do they demonstrate that man is at least two million years old? We should examine at least one of the major dating methods to discover some of the reasons for the discrepancies that exist between the Bible and ocean data on the one hand, and the radiometric dating method on the other.

    Within the last few decades, scientists have discovered what appears to be a tremendous tool which has been used in an attempt to reconstruct the timetable of the past. This tool is derived form a study of radioactive isotopes. Many of the elements of which this planet is composed exist in forms of different atomic weights. These forms are called isotopes K³⁹, K⁴⁰, and K⁴¹. Some of these isotopes are unstable. Over a period of years some of the unstable atoms lose particles by radioactive decay and change into other elements. The most abundant isotope of potassium is K³⁹ and it does not change. The least abundant is K⁴⁰ and it is unstable both with respect to beta emission and electron capture. Each atom of potassium of atomic weight 40 will be transmuted either by emission of a beta particle to become an atom of calcium (Ca⁴⁰) or by electron capture to become an atom of

argon (Ar⁴⁰). Thus, the relative abundance of K⁴⁰ is decreasing and that of Ca⁴⁰ and Ar⁴⁰ is increasing with time. By careful analysis, the rate of this change or decay can be measured. In the case of K⁴⁰, 1290 million years will be required for half of the atoms of K⁴⁰ in existence today to become atoms of Ca⁴⁰ or Ar⁴⁰. The half life of K⁴⁰ is, therefore, 1290 x 10⁶ years.

    By making certain assumptions regarding the mineralogic and petrologic factors, the geologic environment, and other conditions that existed at the time of the formation of the specimen being studied, it is possible to apply the knowledge of its half life to arrive at an estimate of its age, that is, at least the age from the last crystallization of the rock. Not only potassium but uranium, lead, rubidium, and other elements can be used in this kind of age dating. As a consequence of this age dating possibility, scientists have decided that the earth must be about four and a half billion years old.


Are Radioactive Dating Assumptions Correct?

    There are major drawbacks to this method of dating. First of all, we lack knowledge concerning the validity of all the assumption made about the conditions that existed on the earth during the initial span of time since its beginning. Therefore, dates derived from radioactive decay measurements could be in serious error. Moreover we lack other reliable dating methods that are tested and proven accurate by which we can check our radioactive dates. For example, we have already seen how the ocean evidence gives us a conclusion that is much different from an earth age of some billions of years. If we did have another reliable method and found a lack of concordance, we could modify our assumptions until we knew we were using the radioactive evidence properly. We shall presently see how this can be done with radioactive carbon. Finally, while we may arrive at approximately concordant dates using different isotope methods to date the same rock, we cannot know for sure whether these concordant dates are a result of having found an accurate age or if they are a result of some ancient phenomena that synchronized the atomic clocks. For example Richard Armstrong writes:

On all micas both K-Ar and Rb-Sr dates may be determined. This provides a useful check although it is known that even concordant results are not necessarily a significant measure of age.1

Potassium-Argon Dating Reveals Many Anomalies

    Potassium-argon dating is a method which can be used to illustrate the potential for arriving at incurred dates because of lack of knowledge concerning the conditions that existed at the time the rock under study was formed. These isotopes have been used in dating rocks supposedly as young as a few hundred thousand years or as old as several billions years. The assumption must be made, in using this dating method, that at the time the rock was formed, any initial Argon⁴⁰ gas which would come from the atmosphere was entirely driven off. Thus, any Argon⁴⁰ found in the rock presently must be assumed to be a result of potassium decay since the rock was crystallized from a molten condition. Richard Armstrong writes of this but also indicates a problem that is raised because of this assumption.

One of the basic conditions for K-Ar dating is that the mineral phase dated contained no primary Ar40 at the time of its origin. This is never strictly true. In the natural environment, particularly at great depths within the crust, excess Ar40 is present in whatever fluid phases exist. During remobilization of an ancient metamorphic terrane quite high Ar pressures might develop. No mineral phase ever crystallizes absolutely free of contamination from its environment; this contamination may occur on an atomic scale with foreign atoms being accidentally trapped in the crystal lattice, or as bulk contaminination in the form of solid and fluid inclusions. It is only logical to accept that a finite Ar40 background must exist for every mineral. The practical question is to what extent this background affects mineral dates.2

    A practical result of this problem of original Ar⁴⁰ can be very significant in young rocks. G. H. Curtis³ writes of tufts of the Eifel volcanic districts of Germany that gave an age at least two million years greater than it should be based on ages of tufts below it. This, incidentally, is the kind of material and the dating method used by Dr. Leakey in arriving at dates of the earliest man in Oldevai Gorge in Africa.

    David Fisher et al. reports concerning dating of basalt on the sea floor by K-Ar dating, state that, “We have observed large amounts of Ar⁴⁰ in some rocks, leading to anomalously high ages…”⁴ C. S. Noble and J. J. Naughton report that some lavas which are very young, probably less than 200 years old, showed ages as high as 21 x 10⁶ years when dated by potassium argon. He adds:

. . . in some instances volcanic rocks erupted into the deep ocean, do in fact inherit radiogenic argon and helium, and when dated may yield unrealistic old ages.5

Tektites and Potassium-Argon Dating

    Another problem that can be offered is related to the dating of tektites. In many places in the world small pieces of glass shaped like buttons have been found. These are called tektites. Scientists have been quite intrigued by these tektites, wondering if they are of moon or of meteorite origin, or if they are indeed of this planet. They are found especially in four rather large strewn field at several locations on the earth. The largest strewn field are in Australia where tektites are found over almost the entire continent. These Australian tektites are called australians.

    Scientists have become thoroughly acquainted with tektites: their shape, chemical composition, extent of appearance in a strewn field, and other factors. They discovered that they do have a potassium content as well as an Argon⁴⁰ content. Because of their chemical nature and non-granular structure, there is every appearance that they were formed at high temperature and were extremely resistive to contamination. They are, therefore, apparently ideally suited to dating by the K-Ar method. Indeed, the tektites of most of the fields appear to show an age by the K-Ar method which is in reasonable agreement with the geological strata in which they were found. Thus, the tektites found in Texas, which is another of the strewn fields, show a K-Ar age of about 35 million years, and are found in strata that has been dated by other methods to be 35 to 55 million years of age.

    The problem is raised with the tektites of Australia, the australites. These date quite uniformly over the entire continent of Australia at about 700,000 years. Unfortunately, however, they are found in strata that is recent. Baker concludes they were emplaced not over 6000 years ago and not under 3000 years ago.⁶ Moreover, some of their physical characteristic also indicate recent emplacement. No scientist to the present time has suggested a rationale for an older strata than some 5000 years.

    Here then is a major problem. Tektites are quite common; so many tests on them can be made. All signs indicate high formation temperatures and, therefore, probably good accuracy when this method of dating is used. But the emplacement conditions indicate

they were formed about 5,000 years ago. If the Argon⁴⁰ found in them was that which remained at formation it would then cast suspicion on the dates of all tektites in view of the similarities that exist between all tektites, and if the dating of tektites by K-Ar is invalid, then all dating by K-Ar is suspect. This in turn would cast doubt on those dating methods showing concordant dates with K-Ar, and invalidate the present application of these methods.

    This problem has been outlined at length to indicate that all is not conclusive as far as dating is concerned. An accountant is as concerned about a few cents in his balances which cannot be reconciled as he is about a large sum of money. The few cents of error could be an indication of offsets of several thousand dollars. So the individual problems in radioactive time measurements could be an indication of presently unknown information that could lead to an altogether different conclusion regarding these dating methods.


Cosmic Rays And Isotopes

    Robert L. Whitlaw raises another serious problem in relationship to K-Ar dating. He points out that atmospheric argon today is 99.6% Ar⁴⁰, 0.337% Ar³⁶, and 0.063% Ar³⁸, all the isotopes being stable. He continues that the assumption is made that:

If the . . . argon taken in a rock sample contained an infusion of atmospheric argon, it would show up by the presence of Argon36, since the argon that decayed from potassium in the specimen would be pure Ar40 . . . . This being so, it becomes a simple matter to measure the quantity of Ar36 in the specimen, multiply it by 295.6 (i.e. the Ar40/Ar36 ratio in the air) to determine the amount of Ar40 that came in from the atmosphere and finally to subtract this amount from the total Ar40 found.

    The remainder would be the Ar⁴⁰ formed from potassium alone. He goes on to suggest that this line of reasoning will work only if the ratio of Ar³⁶ to Ar⁴⁰ in the atmosphere has remained constant over the eons of time. Whereas there is no data to support this constant ratio, there is an indication that Ar³⁶ is produced by the action of cosmic rays, thus indicating an increase in atmosphere Ar³⁶ with time. He states:

It can be shown that Ar36 is a probable product of cosmic radiation bombarding the earth’s outer atmosphere, just as is radiocarbon.

Several nuclear reaction sequences leading to Ar36 in the presence of free energetic neutrons and photons can be shown.7

    His suggestion that Ar³⁶ is a product of cosmic ray flux is reinforced by statements by other scientists. J. R. Arnold and M. Honda write:

The meteorites are targets containing a record of the cosmic-ray bombardment to which they have been subjected.8

    E. Vilisek and H. Wanke report Ar³⁶ is produced by cosmic rays. They indicate:

The cosmic ray exposure age of a meteorite can be calculated if one knows the concentration of a stable cosmic-ray produced isotope as well as the decay rate of a corresponding radioactive isotope at the time of the meteorite’s fall. Such favorable pairs are H3, Na22/ Cl36/Ar36, Ar39/Ar36, K40/K41, and others.9

    P. R. Goel and T. P. Kohman add their comments to the idea of Argon³⁶ being produced by cosmic rays.

The reaction products of cosmic-ray interactions in meteoroids include both stable and radioactive nuclides. The concentration of a stable cosmogonic nuclide, which accumulates during the whole exposure, represents the total dosage that the specimen has received. Wanke has shown that in large iron meteorites, significantly different values of the Ar36/Cl36 cosmic-ray exposures age are found among different specimens of a given fall, the difference being mainly due to the widely different Ar36 contents. This shows that different portions of the meteoroid have been exposed to cosmic radiation for different durations of time.10

    This problem of the origin of isotopes by the action of cosmic ray is a very serious one if these isotopes are to be used for dating purposes. We shall presently see substantial evidence suggesting that cosmic ray activity began only 13,000 years ago. This would then throw into complete disarray any dating method that utilized cosmic ray-produced isotopes as the potassium-argon method does and which assumes that cosmic activity had continued for millions of years.

    There is one radioactive isotope, however, that is in a class by itself. This is by virtue of the fact it has a half life of only 5730 years and because it is found not only in inorganic materials but also in

organic materials. The short half life makes possible the dating of materials in historical time where many checks can be made by completely independent dating methods of known accuracy. Moreover, the dating of organic materials permits the dating of a wide range of specimens such as wood and bones, as well as inorganic rock. This is known as radiocarbon dating. We shall now examine this in great detail.


Earth’s Radiocarbon Timepiece

    Within the last two decades, scientists have discovered this fascinating and apparently reliable tool for the dating of organisms which have died within the last several millenniums. Natural carbon occurs in several isotopes, the most plentiful of which is carbon 12. It is found especially as the carbon in carbon dioxide of the air which we breath and as the dissolved carbonates in ocean water, as well as the carbonic the fossil fuels and sedimentary rock carbonates. While C12 is stable, the carbon isotope C14 disintegrates into C12 with a half life of 5730 years Wherever C12 is found in living organisms, C14 atoms can be found with it in the approximate same proportion as it occurs worldwide, dissolved in the ocean, in living organisms, in the biosphere and in CO³ of the atmosphere. This ratio is known as the specific radio ability of carbon which we will designate as "I." When a living organism such as a tree, a shell fish, or an animal dies it ceases to be apart of the exchange reservoir of carbon. No longer does its “I” value conform to that of the rest of the world. From the moment of death the C14 atoms begin to disintegrate at a constant rate so that 5730 years later only one half of the C14 atoms remain and its new “I” value is one half of that at the time of death. rams, it is possible to measure the “I” value of any specimen that died hundreds or thousands of years earlier and make an accurate estimate of the year of death.

    Among a number of assumption, two very important ones must be made. The first is that the "I" value in the world can be known at the time the specimen died, and secondly, that the specimen itself has not been contaminated subsequent to death.

    Since no one living centuries or millenniums ago took measurements, scientists have always assumed that the “I” value has

remained reasonably constant over the last several tens of thousands of years. And because specimens dated by Carbon 14 could be date checked by tree rings, written history, and other ways, there appeared rather close agreement between the conclusions of Carbon 14 dating and these other methods.

    As more and more specimens have been dates, however, scientists discovered that C14 is not the all-purpose dating tool many hoped it would be. They discovered that even within the last 2250 years, discrepancies of 100 years or more were possible.¹¹

    Earlier than about 250 B.C., however, C14 dating begins to get increasingly inaccurate. Going back as far as 4000 B.C. the true date of a specimen is generally known to be older by several hundred years than the data established by C14 dating. The formula for this discrepancy has been shown to be roughly:¹²

T = 1.4R - 1100 (Equation 1)

where T is the true age and R is the radiocarbon age. Thus, a specimen which is shown to be 4000 years old by radiocarbon dating is probably closer to 4500 years old, in actuality.¹³

    These corrections and refinements have not invalidated C 14 as a dating tool, but have shown the necessity for more care in evaluating result, and more study to attempt to understand the changes in “I” value over the past millenniums. This brief summary is given to outline some of the known limitations and strengths of the C14 dating method. Because we have established, by Biblical reckoning, 11,013 B.C. as the oldest possible date for living organisms to have existed upon this earth, the results of carbon 14 dating are especially interesting. Dates of thirty or forty thousand years have been discovered by C14 dating. For example, at the Heifers Outwash on the shores of the Caspian Sea, carbon samples have been tested which show human occupancy some 43,000 years ago. Even if this were in error by thirty or forty percent, a date far older than 11,000 B.C. would result. How can this be squared with the Biblical record?

    We found in the previous chapters that the Biblical record is the trustworthy record. Therefore, results from the radiocarbon dating method must be carefully analyzed when used to date objects that approach an age of 13,000 years. We, therefore, might suggest one good reason why radiocarbon dating, as it is presently used,

apparently leads us to untrustworthy conclusions for very early dating. That reason is that there is evidence that the worldwide C14 reservoir is still increasing. If it is indeed increasing, the whole carbon 14 method of age dating requires re-evaluation, for this could change in substantial fashion the ages derived from this dating method. Moreover, this could also point to a very young earth.

    C14 is produced by the action of cosmic ray activity. Thermal neutrons formed by these cosmic rap enter the earth’s atmosphere and react with N 14 to form the radioactive isotope of carbon C14. Cosmic rays are formed from energy sources such as the sun, stars, and possibly supernova explosions which occur every 30 years or so.¹⁴ Scientists assume that these energy sources have been around for a long period of time and have probably produced fairly constant comic ray activity during the last several tens of thousands of years. Thus, a state of equilibrium should exist so that the carbon 14 reservoir or inventory remains fairly constant. The total new carbon 14 being formed at any moment of time ought to just equal the carbon 14 ceasing to exist because of its half life of 5730 years. Slight variations are to be expected because of sun spot activity but in general equilibrium should exist.

    Equilibrium does not exist, however. Even before 1955, Dr. Willard Libby, the first man who discovered and developed the radiocarbon dating method, records data that suggest this fact. He indicates in his book, Radiocarbon Dating, that the “I” value based on the assume rate of formation of new C14 equals 18.8 disintegrations per minute or gram.¹⁵ His estimates of the actual figure for worldwide distribution of biological materials is about 15.3. Thus, his figures indicate that the amount of carbon 14 disintegrating at any time all over the world appears to be about 81% of the new C14 being formed (15.3/18.8 = .81). Other scientists have puzzled over this curious situation and have come to no satisfactory explanation for it. R. L. Lingenfelter writes that there is a strong indication that the present natural production rate of C14 atoms exceeds the natural decay rate by as much as 25%.¹⁶ This is the phenomena that would exist if the Carbon 14 reservoir were about 75% full. The most recent figure for the ratio of the disintegrating rate to that of the rate of formation is about 72%. H. E. Suess writes that the most recent figure for the production rate of new C14 is that of Lingenfelter where the value given is 2.5 + .5 dps per cm². The decay rate given in the same reference is 108.5 dpm/cm² which equals 1.8 dps per cm². Thus, the

ratio of the decay rate to the profusion rate is 1.8/ 2.5 or 72%.¹⁷ This indicates that the C14 reservoir is about 72% full.¹⁸

The Radiocarbon Reservoir Is Still Filling

    The evidence suggesting the worldwide C14 reservoir or inventory is only partly full is surely strange if cosmic ray activity which produces the C14 is a long term phenomena. A number of possibilities might be suggested.

1. During the past 13,000 years cosmic ray activity was severely reduced causing the C14 reservoir to be depleted. This possibility is rather remote. While there have been short time fluctuations in cosmic ray activity due to sun spots and other solar activity, the sun and stars appear by all the available evidence to have shone with about their present brilliance and energy since the beginning or at least for the last hundreds of thousands of years if the beginning is truly back that far in time. 2. Something is wrong with the values obtained for the C14 production rate and decay rate. This, of course, is always a possibility. However, this all important question has been under examination for more than fifteen years now and analyses have been made by competent scientists. Significantly, the results are always on the side of the decay rate being substantially lower than the production rate. While major error is always a possibility, it does not appear at all probable. 3. A catastrophe occurred within the last 10,000 years which buried substantial C14. This is a distinct possibility in view of the Biblical account of the flood. We would then expect the C14 buildup to be resumed after this catastrophe in accordance with the following equation for the production of a radioactive substance: N =  R ––  λ (1 - eλT) (Equation 2) Where R is the rate of formation of active atoms, λ N is the disintegration rate, and X is the characteristic decay constant for the species.19

4. Another possibility is that cosmic ray activity did not begin until 13,000 years ago. The Bible indicates that man was created 11,013 B.C. on the sixth creation day. Since there is much Biblical reason to believe the six days were each 24 hours long and the Bible records that the sun and stars began to shine the fourth day, they also would have an age of about 13,000 years. Since the sun, moon, and stars were visible on the earth, one would logically expect that when God made them to shine upon the earth, He also caused the light and energy-cosmic rays included to fill space and become immediately available to the earth. This is an interesting possibility. If we explore this a bit we discover that in 13,000 years, beginning from a zero reservoir of C14, the build-up would be such that today the inventory would be 79.4% full. This is found from the equation:     D = 100(1 - e-λ) = 100(1 - 2-T/5730)    (Equation 3) where “D” is the decay rate expressed as a percentage of the formation rate, and “T” equals the time in years since disintegration began or since the beginning of C14 production. The assumption that no C14 was created before the six days is supported by the fact that Genesis 1:2 records that there was darkness over the fact of the deep. Light was not brought into being until the first day (Genesis 1:3), which eventually became regulated by the sun, moon, and stars on the fourth day. The darkness suggests a lack of cosmic ray activity even as the presence of the light bearers on the fourth day suggest a full-orbed cosmic ray program from that day forward. Moreover, C14 is not found in the earth’s interior. This in itself is not conclusive, for if the earth is indeed millions of years old, any C14 created at the beginning would have completely disintegrated. But if the earth is 13,000 years old, the absence of C14 in the earth’s interior strongly suggests that C14 was not included as a part of the original creation. 5. Possibly the true state of affairs is a combination of these last two possibilities. The production of C14 perhaps began some 13,000 years ago, and a percentage of it was buried by the blood. This is suggested by the relationship of the 79.4% reservoir based on uniform build-up for 13,000 years, as compared with the

actual reservoir size of approximately 72%. Even this is not conclusive, however, and we must look in greater detail at other evidence related to C14 dating to discover more precisely what actually happened.

    In any event, the partially filled reservoir that does exist indicates that we may not assume that the specific activity of carbon has been constant in the past, and all C14 ages which cannot be independently checked against other dependable dating methods cannot be assumed to be correct. In general a reservoir that is filling would appear to give dates far older than the true dates if there was constancy in the C12 inventory. Thus, we receive a possible insight into the reason for the existence of C14 dates which are far older than 11,000 B.C. Moreover, we sense a real correlation between the partially filled C14 reservoir of today and the Bible information which points to an earth 13,000 years old. The C14 dating method may be the bridge that will bring the scientific evidence into the Biblical framework.

    Thus, we have seen that radiometric dating methods are not at all trustworthy as a means of establishing a timetable for the earth’s existence. The necessity of viewing the available evidence in the light of unverifiable assumptions negates any possibility of trustworthy conclusions. The anomalies that are ever present emphasize the tenuous nature of conclusions derived by these dating methods.

    Moreover, an examination of the Carbon 14 dating method has not only shown one important reason why ages derived from this dating method are much too old as compared with the true ages shown in the Bible, but it has also shown that this method, if properly used, potentially provides very close agreement with the Bible.

    Other dating methods could well be examined, but to do so is beyond the scope of this book. For a further discussion of the question of the unreliability of radioactive dating methods such as uranium- thorium-lead and rubidium-strontium methods, the reader is encouraged to read Chapters 1 to 4 of the book by Melvin A. Cook “Prehistory and Earth Models” (London, Max Parrish, 1966), and “The Genesis Flood” (Morris and Whitcomb, Presbyterian and Reformed, 1965, pages 333-385).

    Let us press on with our study. Can we utilize the dependable characteristics of the carbon 14 evidence together with the absolute truth of the Bible to obtain more information regarding past climatic conditions? In the next chapter, we shall attempt this difficult assignment.

NOTES:


    ¹Richard L. Armstrong, “K-Ar Dating of Plutonic and Volcanic Rocks in Orogenic Belts,” Potassium-Argon Dating, O. A. Schaeffer and J. Zahringer (ed.), Springer-Verland, New York, Inc., 1966, p. 120.

    ²Ibid., p. 120.

    ³G. H. Curtis, “Problem of Contamination in Obtaining Accurate Dates,” Potassium-Argon Dating, p. 155.

    ⁴David Fisher, et al., “Ages of Pacific Deep Sea Basalts, and Spreading of the Sea Floor,” Science, June 7, 1968, p. 1106.

    ⁵C. S. Noble and J. J. Naughton, “Deep-Ocean Basalts, Inert Gas Content & Uncertainties in Age Dating,” Science, Oct. 11, 1968, p. 265.

    ⁶O. A. Schaeffer, “Tektites,” Potassium-Argon Dating, Springer-Verland, New York, 1966, p. 166.

    ⁷Robert L. Whitlaw, “Radiocarbon Confirms Biblical Creation,” Creation Research Society Quarterly, Sept., 1968, p. 82.

    ⁸J. R. Arnold and M. Honda, “Record of Cosmic-Ray Intensity in the Meteorites,” Journal of Geophysical Research, Oct., 1961, p. 3519.

    ⁹E. Vilisek and H. Wanke, “Cosmic-Ray Exposure Ages and Terrestrial Ages of Stone & Meteorites Derived from Cl³⁶ and Ar³⁹ Measurements,” in Radioactive Dating, by International Atomic Energy Agency, Vienna, 1963, p. 383.

    ¹⁰P. S. Goel and T. P. Kohman, “Exposure History of Meteorites from Cosmogenic Cl³⁶, “Radioactive Dating, 1963, p. 415.

    ¹¹Hans E. Suess and Minze Stuiver. “On the Relationship Between Radiocarbon Dates and True Sample Dates,” in Radiocarbon, the American Journal of Science, Yale University, New Haven, Conn., Vol. 8, 1966, p. 537.

    ¹²Ibid., p. 539.

    ¹³Please see Appendix IX for a brief discussion of tree-ring dating as it relates to the Biblical chronology.

    ¹⁴V. L. Ginsburg, “The Astrophysics of Cosmic Rays,” Scientific American, Feb., 1969, p. 61.

    ¹⁵W. F. Libby, Radiocarbon Dating (Chicago, University of Chicago Press, 1955), p. 7.

    ¹⁶R. E. Lingenfelter, “Production of Carbon 14 by Cosmic-Ray Neutrons,” in Review of Geophysics, 1963, p. 61.

    ¹⁷H. E. Suess, “Secular Variations of the Cosmic-Ray Produced Carbon 14 in the Atmosphere and their Interpretations,” in Journal of Geophysical Research, Vol. 70, 1965, p. 5946.

    ¹⁸Please see Appendix X for a further discussion of Lingenfelter’s conclusion in 1970 that the decay-production ratio is close to unity.

    ¹⁹Gerhart Friedlander and Joseph W. Kennedy, Nuclear and Radio Chemistry (John Wiley & Sons, New York, 1st ed., 2nd printing, 1956), p. 132.