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378) Cavitational effect on radioactivity

Ludwik Kowalski

Montclair State University, New Jersey, USA
September 30, 2009

What follows was part of the previous unit #377. But the unit became too long and I decided to split it into two. This is the second half; the first half is still in unit 377

1) Fission versus fusion
Responding to a solicitation, I wrote a short essay (about 800 words) entitled "Nuclear fission, discovery of" for Salem Press. They will probably publish the essay in the book entitled  "The Thirties in America."  Unfortunately, I am not allowed to share the draft at this time. What I would like to do instead is to compose a longer essay entitled  "Fission versus fusion," or something like this. Here are some  observations; ; they were also posted at the private Internet list for CMNS researchers.

A) Nuclear fission, discovered in 1938, was quickly confirmed in several laboratories. Hahn and Strassmann's paper was published in January of 1939; the mechanism of the reaction was understood weeks later (by Lise Meitner, who coined the name "fission" and predicted about 200 MeV by event). This was at once confirmed experimentally (by Frish in Denmark, by Joloit Curie in France, and by Fermi in the US). The preexisting-accepted theory of Niels Bohr (the liquid drop model) was at once used to explain why fission is possible in the most massive nuclei, such as uranium  (high values of Z^2/A). The discoveries of secondary neutrons, first by Joliot Curie and then by Fermi, were also made in January of 1939.  The discovery that fission induced by slow neutrons takes place only in U-235 was also made in 1939 (Fermi and his collaborators). That opened the path to well-known applications, first military and then civilian. Spontaneous fission was discovered in 1940 (by Petrzhak in USSR). Note that these discoveries were made at universities, years before government-sponsored programs were created.

B) Basic nuclear physics facts behind hot fusion (exothermic nature of reactions, their cross sections etc.) have also been known for very long time, mostly from research conducted with low energy accelerators. The preexisting-accepted theory was able to explain the energy dependence of cross sections. Progress from knowing and understanding to the first practical application (hydrogen bomb) took about five years. But progress toward civilian practical applications (hot fusion reactors) continues to be very slow.

C) Discovery of excess heat, attributed to a nuclear reaction, took place twenty years ago. A large number of other CMNR discoveries, such as emission of nuclear particles and transmutation, were announced since that time.  But the world is still waiting for a protocol yielding a "reproducible on demand" demonstration of a strong nuclear effect due to a chemical effect. The word "strong" is important because two kinds of nuclear forces are “strong” and “weak.” Strong forces are associated with nuclear reactions while weak forces are associated with beta decays. One kind of beta decay, capture of electrons from an atomic K orbit, does depend, to some extent, on the chemical composition.

D) What used to be called "cold fusion" is now called "condensed matter nuclear science" (CMNS). Other widely known names are “low energy nuclear reaction” (LENR) and “chemically assisted nuclear reaction” (CANR). New names specifically refer to “nuclear reactions,” such as emission of neutrons, protons, and alpha particles.

2) Importance of reproducibility: chicken-and-egg dilemma
Reproducibility on demand is essential in all scientific fields, especially in fields expected to influence technological applications. How can a proposed CMNR theory be validated? A theory is expected to make specific verifiable predictions. How can predictions be verified without phenomena being reproducible?

The CMNS field has been controversial since the discovery of “cold fusion” was announced; it is still waiting for a generally accepted theory. There are many interesting CMNR reports, as described in numerous postings at this website, and in papers posted at Some discoveries are spectacular. What the field needs, however is at least one experimental protocol yielding reproducible-on-demand results. This is essential. The discovery of “cold fusion” was announced two decades ago but experimentalists are still waiting for an accepted theory to guide them. Theoreticians, on the other hand, are still waiting for reproducible (reliable) experimental results to validate logical conclusions. CMNR investigators are fully aware of this chicken-and-egg dilemma. How can this vicious circle be broken? How can it be explained?

Responding to what I posted at the CMNS list, Dennis Cravens reminded us that theories do not have to have reproducible on demand effects. He wrote: “. . . For example, there are theoretical models of super nova and sun spots that do not require ‘on demand’ effects to be verified or established. All that is required is that the observations obey predictions whenever they happen.  . . . “ Another CMNS researcher gave the cancer treatments as an example. These are valid observations. But most technological applications, especially those used in generation of electricity, and in transportation, are based on reproducible phenomena. Cancer treatments would probably produce nearly the same results if all patients were nearly identical.

3) Speeding up the radiactive decay of thorium?
Another CMNS researcher informed the list about a recent claim (1) that the rate of decay of alpha-radioactive 228Th was speeded up “by a whopping factor of 10,000." This claim was not independently confirmed in other laboratories. But shortcomings of the report were described in (2). The authors of (1) wrote, in the abstract:

“We show that cavitation of a solution of thorium-228 in water induces its transformation at a rate 10^4 times faster than the natural radioactive decay would do. This result agrees with the alteration of the secular equilibrium of thorium-234 obtained by a Russian team via explosion of titanium foils in water and solutions.” They refer to Urutskoev and other researchers who reported “nuclear reactions induced by pressure waves.”

I agree with (2) that a better experiment can now be designed. Here is my message about this, posted on the CMNS list: ”I just finished reading additional two papers (Cardone responding to Ericsson's criticism, and Ericsson responding to Cordone's response). Valid points are presented by both sides. The time seems to be perfect for designing a better experiment to verify validity of the initial claim of Cardone (and those who conducted similar experiments before). I would be happy to collaborate with someone who has experience with cavitation processing. My experience in working with nuclear detectors, most recently with CR-39, might be useful. Let me know.”

In an earlier message I wrote: “Authors of the critical paper (Ericsson et al.) are probably not aware of many puzzling CMNS results. By the way, they did not try to replicate the Cardone's results; they described the shortcomings of the procedure, etc. Replication experiments conducted in different laboratories would tell us how reproducible the result of Cordone et al. are. Most people do not like to replicate experiments performed by others; they prefer to test their own ideas. This is one of the reasons that progress toward recognition of CMNR is very slow. Do you agree?”

I read two additional papers (Cardone responding to Ericsson and Ericsson responding to the response). The fact that all four papers were published in Physics Letters, a prestigous mainstream journal, is significant. They also published the Kitamura et al. article this year. Does it mean the end of discrimination is approaching? I hope so.

4) More about speeding up the radioactive decay of thorium.
At first I thought that CR-39 played an essential role in backing the claim made in (1). But I changed my mind, after reading the paper again. I have a bunch of comments and questions about this.

a) Sizes of photographed areas (in their Figure 1) are not specified and track densities are not given. Why is it so?

b) The authors wrote that radiation from Th-228 was recognized on the basis ” unmistakable ‘star-shaped’ look of some tracks.” This would indeed be the case if Th-228 was in a solid. But thorium dissolved in a liquid should not produce such stars.

c) The explanation has to do with the fact that emission of an alpha particle from Th-228 is followed by delayed emission of additional four alpha particles (from Ra-224, Rn-220, Po-216, and, most often Po-212) separated in time. The second alpha particle, from Ra-224, can be emitted five or ten days after the first particle. In a liquid source (thorium salt dissolved in water) separation in time also implies separation in space. That is why no “star-shaped” tracks are expected in a CR-39 kept in the liquid. Ra-224 atom will usually decay far away from where it was produced. But this is not true for a solid source. In a solid source sequentially emitted particles most often originate from the same point. That is why alpha particle tracks often form multi-prong star-like patterns in nuclear emuslsions. Why was at least one star-like pattern not shown in (1)? Circles in Figure 1 are not at all informative. Are they more informative in the printed article than on my screen? I do not know. In any case, referees should have asked for at least one better resolution photo.

d) The authors write that “the ratio of the number of traces and the number of solutions is therefore 3/4 for the reference solutions and 3/8 for the cavitated ones.” This is not clear to me. What is clear, however, is that three tools available to support the claim--only one half of thorium remains in the vessel after 90 minutes of cavitation--were highly appropriate. The first tool was the magnetic spectrometer, the second tool was the NaI gamma spectrometer, and the third tool was CR-39. The magnetic spectrometer results were presented clearly. The gamma ray spectrometer results (showing that cavitation reduces the radioactivity of the solution by the factor of two) were not shown at all. The CR-39 results were not presented clearly, as far as I am concerned. A clear presentation would consist of track densities (or the total numbers of tracks) on all photos shown in Figure 1.

e) My recollection is that seven strong peaks are clearly identifiable in the gamma decay of natural thorium in equilibrium with its daughters. A change in the shape of the spectrum could provide information about which daughter, if any, is destroyed more efficiently by cavitation.

f) According to my rough estimate (see point 5 below), the pit density, due to Th-228 dissolved in water (at the 0.03 ppb concentration), would be between 12500 and 2500 tracks per square centimeter, after the exposure lasting 90 minutes. This is much higher than what is usually found on unexposed chips; typical radon and cosmic rays densities are close to 10 tr/cm^2.

g) The authors wrote that the ratio between the half-life of Th-228 (1.9 years) and duration of cavitation (90 minutes) is 10^4. This is correct. In the next sentence they conclude: “this means that cavitation brought about the reduction of Th-228 at a rate 10^4 times faster than the natural radioactive decay would do.” I am puzzled; what additional information was used to justify the conclusion? Was the answer obvious to referees? Note that the factor 10000 is the ratio of rates at which Th-228 disappers (via natural versus artificially induced decay). It is deduced from the fact that one half of the initially present Th-228 is destroyed during 90 minutes of cavitation.

5) Appendix (Estimation of a blank chip track density)
Consider 1 cm^3 of the 0.03 ppb water solution (of Th-228 atoms) on top of the 1 cm^2 surface of CR-39. How many tracks to expect, after 90 hours ? The exact answer can be obtained by a Monte-Carlo code. A simple estimate, see below, is also possible. I will assume, to simplify calculations, that only Th-228 is able to form track. In other words, I will ignore alpha particles emitted from daughters of this isotope.

a) 1 cm^3 of water contains 3.3*10^22 molecules; the number of Th-228 atoms in it is:

(0.03/10^9)*(3.3*10^22)=10^12 atoms.

b) The range of alpha particles in water is about 40 microns, or 4*10^-3 cm. Only some alpha particles emitted from the 40-micron layer of solution will be able to create pits on the CR-39 surface. Others will be either absorbed in water or be intercepted at a too large angle.

c) How many Th-228 atoms are in the 40 micron layer? The answer is


d) The activity A (alpha particles per minutes), of the layer is N*L, where L is the probability of decay per unit time.

L is given by ln(2)/T=0.69/T, where T is the half-life. For Th-228 T=1.9 years, or 10^6 minutes. The probability of decay per unit time is thus

L=0.69/10^6=6.9 *10^-7 per minute

e) The activity A of the layer (alphas per minute) is

A=N*L=(4*10^9)*(6.9*10^-7)=2760 alphas per minute

The number of alpha emitted in 90 minutes is close to 250000. Suppose that only 5% of these particles are able to produce tracks. This is probably a reasonable assumption. In that case the pit density would be 12500 tracks/cm^2. The density would be 2500 tracks/cm^2 if only 1% of alpha particles emitted from the 40 micron layer were able to produce tracks. And it would be 250 tr/cm^2 if the fraction were only 0.1%. [P.S. reflecting about this again, I think that 0.1% is more realistic than 1%. Fortunately, even 0.1 % would be OK, from the point of view of feasibility.

6) Reading the first criticism of Cardone (1) by Ericsson (2)
a) The following observation of Ericsson et al. is worth thinking about. They wrote: “if the decay of 228Th is actually accelerated as (possibly) claimed during the cavitation, and such decay can be registered by the CR39 detectors, then the detectors monitoring the cavitated solutions should not show fewer but four orders of magnitude more events.” That would not be true if detectors were placed into the vessel before cavitation or after cavitation (not during cavitation). Track densities after cavitation would be two times lower than before cavitation, for the same exposure time. I agree with (2) that the reported ability to identify decays taking place during cavitation is highly questionable.

7) Reading the first reply of Cardone (3) to Ericsson et al.
a) Cardone et al. think that “the main shortcomings of the criticism by the Swedish authors are due to their omitting of inserting our experiment in the wider research stream of piezonuclear reactions, and to the statistical analysis they used, which does not comply with the rules generally accepted for samples with small numbers.” Relevance of earlier studies, in particular to investigations of Russian scientists, was well described in (1). That is why I would also not discuss it in an article written to criticize the methodology used in (1). That would only be important if the same mistakes were made by other authors.

b) Referring to their gamma counter results, Cordane et al. conclude that they are dealing with processes in which transformations of elements take place “without significant emission of gamma radiation.” That is a very important clarification. It means that absence of gamma rays is not a valid argument against absence of nuclear reactions. But it has nothing to do gamma rays emitted from the solution, either before or after cavitation. A gamma spectometer would show what fraction of radioactive isotopes is destroyed, and which gamma emitter are destroyed more effectively. The authors of (1) are correct that they are not the first to claim reality of nuclear processes without emission of gamma rays.

c) Photos in reference (3), unlike those in reference (1), show readable scale lines near the corners. Now I know that photographed areas were 2.9 by 2.2 mm. The left photo shows that white dots, presumably tracks of alpha particles, are localized in a nearly circular area whose diameter is about 2 mm. That is not what I would expect to see on the surface of a CR-39 immersed in an alpha-radioactive liquid. Why is the distribution of tracks not uniform? I wish the etching conditions of CR-39 were specified (solution, its molarity, its temperature, and the duration of etching). This would help me to decide whether or not white dots are tracks due to alpha particles. My experience in working with CR-39 detectors suggests that thin and long lines are not tracks of alpha particles. I have no idea how to explain chain-like clusters shown in the left side photo. The right side photo (the chip was outside the vessel) does not exhibit such clusters.

d) A little later the authors refer to the “inhomogeneity of the initial concentrations of all used (both cavitated and reference) samples.” Why a thorium salt dissolved in water would not be distributed uniformly in the solution? Unfortunately, no information about non-uniformity is provided. Does it have anything to do with the nature of the thorium salt? If so then what was its main composition? What was its purity? Where was it obtained?

8) After reading the second reply of Ericsson (4) to Cardone (3)
a) It is clear to me now that the question about non uniformity of the thorium distribution is related to the first comment in reference (4)--how do the authors of (1) know that samples of the same initial volume contain the same initial amount of thorium? A large systematic error can indeed be made when the distribution of thorium is not uniform, for example, then the liquid is not stirred. My impression was that cavitation is like stirring.

b) The authors of (4) also feel that not enough information was presented about CR-39 methodology.

c) My impression, in looking at the two pictures in (3), was that the left one is in the water containing thorium while the right one is in the air, outside the chamber. But I was apparently wrong; the caption is clear that the left one is in water. All the questions I asked were about the left picture (see point 7 above). Now the situation is even more obscured. Why so many tracks were found in CR-39 immersed in the ultra-pure water?

d) I agree with (4) that arguments presented in (1) and (3) are not very convincing, and the experimental procedure can be improved. Only one of three available tools, the magnetic mass spectrometer, was used to directly support the extraordinary claim? Why was the gamma rays spectrometer not used at all to compare levels of radioactivity before and after cavitation? Why so little information was presented the CR-39 results?

e) A better experiment is worth performing, to obtain a definite yes-or-no answer about the claim made by Cardone et al., and by Russian investigators who they quote. The important point is that Ericsson et al. did not perform any experiments; they only stated that results could possibly be due to trivial mistakes. Possible mistakes are not demonstrated mistakes. The topic is too important to declare the article be worthless. Yes, it would be better if Cardone et all were more experienced, and if referees were more demanding. But that does not exclude a possibility that the claim is valid.

f) Let me share a trivial mistake suspected by Fabrice David, a French CMNR researcher. In a message posted at our private Internet list he wrote about a possibility that Th-228, in the experiment of Cardone et al., is redistributed rather than destroyed. He wrote: “sonication induces cavitation, and cavitation induces reactive chemical species like ozone or hydrogen peroxide. Thus, thorium can change its oxidation state, and (perhaps) stick to the glass surface.” That would indeed produce the results reported in (1). Fortunately, CR-39 chips can be used to verify whether or not thorium that is no longer in the solution is on the glass, or in another suspected region, such the cavitaror.

g) The following statement from (1) puzzled me. “We measured the ionizing radiation in the empty Duran vessel both before and after cavitation. The radiation measurements were carried out by means of two Geiger counters with mica windows (one of which equipped with an aluminum filter 3 mm thick), and of a thallium activated, sodium iodine gamma-spectrometer. The results turned out always compatible with the background level.” Why did they measure radiation inside an empty vessel; I would measure it in the vessel with the solution, first before and then after cavitational treatment (in order to show that the level radioactivity was significately reduced by cavitation). Is it possible that they were thinking about a possibility mentioned by Fabrice? Nothing of that kind is mentioned in (1) and (3).

h) The authors of (1) do not provide information about what mass was selected to measure the decrease in the concentration of thorium. Were the measurements based on the mass 228 peak only or were they based on several peaks? My guess is that only one peak was selected. The gamma spectrometer should display several energy peaks, some due to Th-228, others due its daughters. It is very unfortunate, that no gamma radiation spectra were shown in (1). Such spectra, as indicated above, could provide very valuable information about changes resulting from cavitation.

The CR-39 will record alpha particles from both Th-228 and its daughters (assuming Th-232 does not contribute to what is observed.) For that reason the measured reduction of radioactivity, resulting from cavitation, might depend on which of the three methods is used. All three methods, however, should produce the the same result if transmutations induced by cavitation are not isotope-specific.

i) There is a lot to learn about the claimed effect, after it is shown to be reproducible on demand. Unfortunately, I have zero experience with cavitators. Otherwise, I would have used all three instruments described in (1), actually a much older version of a mass spectrometer (not with a laser beam). Assuming cavitators are not too expensive, I am suggesting that reproducibility on demand is tested by using CR-39 detectors only. In that way many researchers, even students, could participate in gathering information about reproducibility.


1) F. Cardone et al. / Physics Letters A 373 (2009) pages 1956–1958
2) G. Ericsson et al. / Physics Letters A 373 (2009) pages 3795–3796
3) F. Cardone et al. / Physics Letters A 373 (2009) pages 3797–3800
4) G. Ericsson et al. / in press (2009)

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