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sonofusion, Taleyarkhan, Putterman, Suslick, Purdue University

332) Krivit’s Sonofusion Report

Ludwik Kowalski; 7/10/2007
Department of Mathematical Sciences
Montclair State University, Upper Montclair, NJ, 07043

Nonscientific factors, such as political and economic considerations, negative emotions, such as jalousie and vindictively, or desire to dominate, often influence scientific debates. Opposition to Galileo was ideological rather than scientific. The same can be said about opposition to the theory of relativity (Germany in late 1930s), and about opposition to genetics (Soviet Union in late 1940s). These are examples of well known, and highly organized, campaigns. Less known are contemporary feuds in various disciplines and sub-disciplines. A friend, Jed Rothwell, who created a wonderful Internet-based library of CMNS papers, wrote to me: “There is a lot of jealousy, rivalry and irrationality in this [CMNS] field, which is one of the reasons it has made so little progress. It is unfortunate.“ I believe Jed; he was following evolution of the CMNS field for much longer than I did. Jed’s e-mail message came several days before the 23rd issue of The New Energy Times was published:

Item 8 of that issue contains a link to an interesting report of Steven W. Krivit. The report is devoted to an ongoing feud in another field. Krivit is a professional journalist specializing in scientific reporting, and the editor of The New Energy Times. In the Introduction he wrote: “Society’s general understanding is that scientists are objective, dispassionate, dedicated to serving the greater good of society, and held to a high standard of ethics.” But then he describes situations which are quite different from what is generally expected. The feud he describes involves a nuclear engineer Rusi Taleyarkhan, Purdue University (where he is a tenured professor), his scientific opponents and some journalists.

In an overall comment about this ongoing feud (item 2 in the above URL), Christopher Purvis wrote “Purdue failed in that duty of care by leaving Taleyarkhan to represent himself among some of the most aggressive and manipulative international journalists, where, through no fault of his own, he quickly got out of his depth and walked into the trap they had prepared for him with the hired help of rival researchers.” I have seen references to that episode but I did not read publications of involved scientists. I plan to read them; this unit is a place holder for future entries about sonofusion. For the time being I just want to share one observation.

Sonoluminscence and cold fusion: a common denominator
Taleyarkhan’s claim is about sonofusion -- hot fusion taking place inside collapsing bubbles. In that sense the topic is very different from cold fusion claims. What do these two claims have in common? Both Fleischmann and Taleyarkhan made the same deplorable mistake. That mistake is partially responsible for subsequent rejections of what has been published. It would be better if claims were formulated in terms of what was actually discovered and not in terms of speculative implications. Fleischmann discovered non-chemical excess heat. It was a mistake to speculate that a nuclear process is responsible for excess heat, it was a mistake to accept the term cold fusion. The consequences are well known; instead of focusing on replications people started to discuss speculations, such as tunneling effect and emission of neutrons. Fleischmann should have refused to discuss nuclear physics concepts until reality of excess heat were recognized by most scientists.

Likewise, Taleyarkhan’s claim should have been limited to what he actually discovered, generation of neutrons and production of tritium. He should have refused to discuss sonofusion until reality of nuclear particles was accepted by most scientists. If he did this then subsequent debate would focus on detection of nuclear particles and not on wheather or not they are emitted from collapsing bubbles. Emission of nuclear particles would be interesting even if they were not emitted from collapsing bubbles. PuttermanŐs emphasis on short time coincidences (between light and neutrons) was perfectly logical in the context of sonofusion but it would not be prematurely debated outside of that conext. Likewise, emphasis on coulomb barrier was perfectly logical in the context of cold fusion but it would not be prematurely debated in the context of excess heat. Decoupling facts from speculations would be initially beneficial in each of these fields.

Yes, tendencies to interpret experimental facts in terms of accepted theories is natural and desirable. Science is much more than factology. But waiting for general acceptance of new experimental facts, and refusing to speculate about theories, would likely be more effective, in a long run. Speculations about models should be based on will established facts while predictions about facts should be based on well established theories. And what to do in situations in which nothing is well established? In such cases it is probably better to address unexplained facts before addressing possible explanations. The issue of Fleischmann’s excess heat, and the issue of Taleyarkhan excess neutrons, would probably be resolved long time ago if debates about explanations were postponed.

Appended on 7/12/07:
The first step toward sonofusion was discovery of sonoluminescence -- production of heat and light in tiny bubbles. Generation of heat in a rapidly compressed gas has been studied for more that a century; it led to many practical applications, such as ignition in a Diesel engine. In the case of small bubbles the temperature increases are often so high that substances are ionized and light is emitted. This was discovered by two German scientists in 1930’s. But can the temperature be high enough to allow thermonuclear reactions? This question was asked in 1982, by an American scientist Hugh Flynn. The answer, according to Rusi Taleyarkhan (R.T.), is positive, as demonstrated by him in 2002, and in more recent experiments. But his claims have been challenged by several scientists. R.T. came to US from India, obtained his Ph.D. degree in nuclear engineering, and worked at Oak Ridge National Laboratory for may years. Then he became a tenured professor at Pardue University. Here is how his first sonofusion report was described in CERN Courrier (Apr 23, 2002):

“. . . This is the latest apparent manifestation of sonoluminescence, whereby light is emitted by bubbles collapsing in a liquid excited by sound. Observations of the light suggest that implosions provoked by high-frequency sound could create extremely high temperatures and pressures - high enough, perhaps, to lead to conditions that could fuse two atomic nuclei. The researchers used neutrons to induce the formation of bubbles in liquid acetone in which the hydrogen atoms had been replaced by deuterium. Sonoluminescence resulted in the observation of light accompanied by neutrons. Tiny quantities of tritium were also detected. The researchers hypothesized that nuclear fusion had occurred, since the neutrons had different energies from those used to induce bubble formation, and tritium is an expected byproduct. When the experiments were repeated with hydrogenous acetone no tritium or neutrons were observed.”

It is important to emphasize the basic difference between sonofusion and the so-called “cold fusion.” The former is not different from the well known thermonuclear reactions, as in hydrogen bombs, except for the method by which bursts of high temperatures are generated in tiny bubbles. The later, on the other hand, are said to be due to unknown nuclear processes. The controversy about sonofusion has to do with generation of stellar-like temperature in collapsing bubbles; the controversy about cold fusion has to do uncharted areas of basic physics. The 2002 claim, for reality of sonofusion was based on production of tritium and on emission of neutrons, above the expected background level. These are two basic signatures of known thermonuclear reactions. But, as recognized by the first opponents of the sonofusion claim, D. Shapira and D. Saltmarsh, the neutron to tritium ratio in sonofusion was very different from what it is in known thermonuclear reactions. If sonofusion were real, they wrote, then it would be a totally new nuclear process. But these scientists from Oak Ridge National Laboratory did not believe that sonofusion was real. They, and other opponents, suspect that neither neutrons nor tritons, observed by R.T., were produced in compressed bubbles. An auxiliary neutron source, and tritium contamination, were said to be responsible for the reported results.

This morning I wrote the first two papers of R.T. and his coworkers:

(1) “ Evidence for Nuclear Emissions during Acoustic Cavitation,” Science , Vol. 295 , No. 5561, pp. 1868-1873 , March 8 , 2002.
(2) “Additional Evidence for Nuclear Emissions during Acoustic Cavitation”, Phys.Rev.E , Vol. 69 ,No. 036109 , March , 2004.

They are full of interesting details. Unfortunately, I am not sufficiently qualified to comment on everything. But I do understand some things. How was generation of tritium established? By counting electric pulses due to decay of tritium in a pre-calibrated liquid scintillation counter. One cubic centimeter of deuterated acetone could be removed from their cell and added to the liquid scintillator, ecolyte. Here are their results:

a) before sonofusion experiment (this is the background) -- about 53 counts/min.
b) after 7 hours of sonofusion --about 60 counts/min.
c)after 12 hours of sonofusion --about 69 counts/min.

Standard deviation associated with expected random errors were close to 2.5 counts/min. Yes, the amount of tritium does seem to increase with duration of an experiment but the rate at which accumulation of tritium increases is not impressively high. What is impressive, however, is the fact that no accumulation of tritium was observed when deuterated acetone was replaced by common acetone, or when deuterated acetone was exposed to seeding neutrons without acoustical waves. Numbers alone would be much more impressive if the rate of tritium production were several times larger.

According to R.T., sonofusion is greatly enhanced when acetone is constantly ionized by an external source of 14 MeV neutrons. These neutrons are delivered in pulses of short duration (about 10 microsecond). Each pulse arrives at a moment at which the applied acoustical wave is at the minimum. The bubbles collapse about 27 microseconds and that is when sonofusion takes place. Neutrons of 2.45 MeV are expected from the D-D fusion and that what said to be discovered by R.T. It is important not to confuse neutrons from sonofusion with neutrons from the 14 MeV source (a linear accelerator). The 27 microsecond delay seems to be sufficient for this. But this was not taken for granted by some critics. Statistical evidence for emission of neutrons is more convincing than evidence for emission of tritons, as illustrated in Figures 4a and 4b (see the second paper above). It is about 300 counts, when the acoustical wave is on, versus about 5 counts when the acoustical wave is off. In both cases the cell was exposed to the pulsating beam of 14 MeV neutrons. The hot fusion neutrons were detected with a scintillator counter that was blocking gamma rays. This was possible because shapes of electric pulses due to gamma rays were different from shapes due to neutrons. Actually, separation of gamma rays from neutron was not necessary to demonstrate presence of a nuclear effect. In a more recent experiment of R.T., described in

(3) “Nuclear emissions during self-nucleated acoustic cavitation,” Phys. Rev. Letters, Vol. 96, 034301, Jan. 27, 2006,

two additional kinds of detectors (BF3 and CR-39) were used to confirm presence of neutrons. But the most important innovation of the 2006 experiment was elimination of 14 MeV neutrons. This was done to show that 14 MeV neutrons could not possibly be responsible for hot fusion neutrons. Ionization of acetone, in the new experiment, was performed by alpha particles. To accomplish this a small amount of natural uranium salt was dissolved in acetone.

Inserted 7/14/07):
I also read two critical comments of this new experiment, one by B. Narango (a research associate of S. Putterman) and by a Russian Scientist, A. Lipson. Both comments, and rebuttals by R.T. can be found in

(4) “Comment on ‘Nuclear Emissions During Self-Nucleated Acoustic Cavitation,’“ Physical Review Letters, Vol. 97, p. 149403, (Oct. 6, 2006)

Narango analyzed the energy spectrum of neutrons, under assumed experimental configuration, and arrived to a conclusion that it was practically the same as that of Cf-252. Was he thinking about a possibility that a Cf-252 was present somewhere in the laboratory? If so then experiments with ordinary acetone would show about as many neutrons as experiments with deuterated acetone. But 2.45 MeV neutrons, according to R.T., were present only when deuterated acetone was used. Responding to Narango, R.T. showed that energy spectra of detected neutrons from his Cf-252 source and from his sonofusion cell were not identical. Even more convincing argument, against presence of a Cf-252 source, was the comparison of energy spectra of gamma rays.

In Chapter 5 of his report, S. Krivit, tells us how the Cf-252 issue emerged, about half a year before Norango‘s paper was published, and how it was interpreted. It is important to be aware that neutron spectroscopy is a complicated business. Suppose that mono-energetic neutrons of 3 MeV are emitted. A plastic scintillation detector, exposed to these neutrons, will show energies of protons that neutrons create in plastic. These protons will have all energies from zero to 3 MeV. The shape of the recorded energy spectrum will depend on the size of the detector, on its shape, on its relative location with respect to the source, etc. etc. That is why neither the spectrum due to Cf-252 neutrons, nor the spectrum of neutrons attributed to sonofusion resemble the spectra of original spectra of neutrons from these sources.

Comments made by A. Lipson were about possible mistakes made in estimation of neutron detection efficiencies. Such mistakes, if real, would lower the neutron emission rate significantly. Was the rebuttal provided by R.T. (about e.m. noise) convincing? I think it was. But I am not sure.

Most people, including R.T.., seem to believe that sonofusion in deuterated acetone is the well known thermonuclear D-D reaction. But the R.T..’s data are not consistent with that interpretation. As noticed by D. Shapira and M. Saltmarsh, in

“Nuclear fusion in collapsing bubbles -- Is it there? . . . ” Phys. Rev. Lett., vol 89, p 104302 (2002),

the reported neutrons to tritons ratio in sonofusion and in thermonuclear reactions differ by four orders of magnitude. In other words, R.T.. observed about 10,000 less neutrons than would be expected for the reported amount of tritium. I do not remember this issue being addressed in subsequent discussion. That would not be important if the claim was limited to unexplained emission of neutrons and tritons. But the issue becomes essential when these particles are said to be produced in thermonuclear D-D reactions. In my opinion, arguments for reality of a nuclear activity are more convincing than arguments for the sonofusion nature of that activity. Let me add that according to Y.T. Didenko and K.S. Suslick, in

“Energy efficiency of formation of photons, radicals and ions during single-bubble cavitation,” Nature, vol 418, p. 394, July, 2002

Collapsing bubbles containing polyatomic molecules cannot possibly be heated to stellar temperatures. They wrote: “The temperatures reached during cavitation will be substantially limited by the endothermic chemical reactions of the polyatomic molecules inside the collapsing bubble. We therefore expect that the extraordinary conditions necessary to initiate nuclear fusion will be exceedingly difficult to obtain in any liquid with a significant vapor pressure. However, the possibility of such events in very low volatility liquids (for example, some polar organic liquids, molten salts or liquid metals) cannot be ruled out. The present results show that endothermic sonochemical reactions within a collapsing bubble are a major limitation on the conditions produced during cavitation.” This argument would also be totally irrelevant if the claim made by R.T. was limited to emission of nuclear particles.

The same observation can be made about very fast coincidences, between emission of light and emission of nuclear particles, requested by S. Putterman (see page 36 of Krivit’s report). Confirming such coincidences would indeed be a very convincing argument for sonofusion. Experiment of that nature, however, is not simple, and probably very difficult to interpret, especially if no dominant coincidence peak is found in the time spectrum. But such experiment is totally unnecessary in the context of a claim that does not include sonofusion. It would be better if attempts to confirm a nuclear activity were decoupled from attempts to confirm specific mechanisms, such as sonofusion or cold fusion.

Another overview of the sonofusion situation can be found in:

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