Process and plant for the production of endothermic and exothermic piezonuclear reactions by means of ultrasounds and the cavitation of substances

Technical field of the invention

The present invention relates to a process and associated plant for the production of endothermic and exothermic piezonuclear reactions by means of ultrasounds and the cavitation of substances. What is meant by piezonuclear reactions are reactions obtained by means of the use of ultrasounds introduced into a suitable liquid substance for the purposes of developing the cavitation phenomenon within it.

Background

Ever since the 20th century exothermic reactions of the type-

(neutron + nucleus) -» (end products + energy) (I) have been known, such as, for example : n + B — » Li + α + energy and endothermic reactions of the type:

(energy + nucleus A + nucleus B) -> (end products) (II) such as, for example: energy + Fe + Fe → Te or

(energy + neutron + nucleus) -> (end products) (III) such as, for example '• energy + n + U ²³⁸ → Nt ²³⁹ + β → Pt ²³⁹ + β

Normally, exothermic reactions are not used, not only for reasons of safety, but also because they are not very economic and are difficult to produce, in that nuclear reactors have to be used as the source of neutrons. However, a nuclear reactor to be used for these purposes would have to be modified in its architecture and this would reduce its thermal efficiency for the purposes of energy production.

A way of realising a process that makes it possible to obtain neutrons in doses which are not dangerous for living beings by means of the use of ultrasounds and cavitation has now been found and these neutrons can be advantageously used in an efficient manner to produce the above-mentioned reactions, and particularly for reaction (I).

Endothermic reactions are commonly used to obtain the transmutation of substances by means of neutron radiation and to obtain isotopes which are not otherwise available, using nuclear reactors as sources of neutrons.

A way of realising a process that makes it possible to obtain neutrons in doses which are not dangerous for living beings by means of the use of ultrasounds and cavitation has now been found and these neutrons can be advantageously used in an efficient manner to produce materials by means of exo- and endothermic reactions starting from different initial materials, but without using nuclear reactors, thus avoiding the safety problems that their use entails.

Summary of the invention

An object of the present invention is therefore the realisation of a process and the setting-up of a system for the production of usable materials and energy, such as, for example, - though not exclusively, - mechanical energy, possibly advantageously transformable into electrical energy. The energy is produced by means of neutron-nucleus nuclear reactions in which the neutrons that trigger said exothermic reactions are produced by means of ultrasounds and cavitation, without the contribution of ionising radiation. Said neutron-nucleus nuclear reactions produced by means of ultrasounds and cavitation are also called piezonuclear reactions, where what is meant by "piezonuclear" is the phenomenon of generating nuclear reactions catalysed by pressure waves and what is meant by the term "catalysed" is that suitable values of power, frequency and duration of application of the pressure waves may exceed the Minkowskian energy threshold

of the nuclear forces.

Another object of the present invention is the realisation of a process and the setting-up of a plant for the production of materials by means of neutron irradiation, or, that is to say, by submitting a given material to a flow of neutrons obtained with the piezonuclear process. The neutron irradiation produces neutron-nucleus nuclear reactions that modify the material initially present in the working liquid to produce the end material required; said reactions, which can be exo- or endothermic, are produced by means of ultrasounds and cavitation, without the contribution of ionising radiation.

Yet another object of the present invention is an ultrasonic reactor for the generation of energy and matter by means of the use of neutrons generated by sonication and cavitation.

A further object of the present invention is a passive control system of the functioning of the sonotrode/working liquid complex based on the measurement of the emission of neutrons, thus also constituting an indicator of the energy released during the process.

Further objects of the invention will emerge clearly from the description here below.

Brief description of the figures

The present invention will be described, referring, as regards the electromechanical part, to the drawings in the figures attached hereto.

Figure 1 presents a cross -sectional view of the main part of the device for the production of ultrasounds and of the sonotrodeJ

Figure 2 presents a partial cross-sectional schematic view of a cooling system for the sonotrode in Figure V,

Figure 3 presents a schematic view of the apparatus for the production of neutrons using the ultrasound generator schematically illustrated in Figures 1 and 2.

Figure 4 presents a schematic view of a small-scale plant according to the invention.

Figure 5 presents a schematic view of a large-scale plant according to the invention.

Figure 6 presents in graph form the results of the experiments conducted according to the present invention.

Figure 7 presents the graph for the binding energy per nucleone.

Figure 8 shows overall, on the χ-axis, the different power, energy and percentage amplitude values and, on the y-axis, the different concentration values that correlate the results shown in each of the graphs in Figures 8A, 8B, 8C, 8A', 8B', and 8C, which, on the χ-axis, give the time in minutes and, on the yaxis, the neutron dose produced in nSv units (nanoSie verts). Thus, Figure 8 is to be regarded as an overview of the individual detailed views in Figures 8A, 8B, 8C and Figures 8 A', 8B' and 8 C The overview in Figure 8 demonstrates the reproducibility of the results and the governability of the process according to the invention.

Figure 9 schematically illustrates an ultrasonic reactor for the production of energy and matter.

Figure 10 schematically illustrates a passive control system for the functioning of the sonotrode/working liquid complex.

Detailed description of the invention

The processes usable according to the present invention are based on the setting-up of a process and the associated implementation device for the production of neutrons starting from materials in the liquid phase, both in solution and in dispersion, such as, for example, ferric- ion-based compounds, to which can be added suitable substances as indicated here below in detail, which, by reacting with the neutrons, produce energy and can transform themselves into different substances from the initial ones.

The process for the generation of neutrons takes place by applying ultrasounds and cavitation to the working liquid (hereinafter also called the primary working liquid) in such a way as to bring about the implosion of the gas bubbles (generally air) naturally present in the liquid phase, and thus the neutrons are produced in an exclusively acoustic manner without the contribution of external ionising radiation.

The ultrasounds can be generated by means of devices which are well known, suitably modified as indicated here below.

The ultrasound devices known in the current state of the art are those used for welding which comprise a stack of piezoelectric transducers consisting of stacked disks made of ceramic material.

These devices for ultrasonic welding are used for various purposes, including the welding of plastic sheets and the like, and are normally constructed in such a way as to operate for the very short period of time necessary to heat the plastic and bring about its partial localised melting and thus its welding (WO2007/011272).

The subsequent activation of the ultrasonic welding device occurs after a number of seconds, which are needed to enable the operator to position a new workpiece. According to this mode of operation, the

piezoelectric transducers have time to cool prior to the following work cycle, i.e. they operate with a very short duty cycle.

This aspect is important in that the piezoelectric materials that convert electrical energy into ultrasonic mechanical energy present variations in their characteristics as a function of their temperature, which increases as a result of dissipative effects during their operation. Effectively, the entire complex of the welding apparatus, comprising the piezoelectric disks and the sonotrode, must not operate beyond the resonance frequency proper to the complex as a whole.

It should be pointed out that variations in temperature cause corresponding variations in resonance frequency and this is damaging since the maximum energy transfer from the electrical source to the sonotrode, and thus to the material subjected to sonication, is optimised only when working at the resonance frequency of the complex as a whole.

While this is of only marginal importance in the case of ultrasonic welding machines that have a very short duty cycle, it is very important when the welding apparatus-sonotrode complex has to operate continuously for lengthy time periods, of as long as 90 minutes or more, as required in the process according to the invention.

The resonance frequency drift due to the increase in temperature could be compensated for by varying the frequency of the electrical excitation energy, but this would entail an excessively complicated construction of the electrical energy and ultrasound frequency generator.

In this connection, it should be noted that the power values involved are relatively high, ranging typically up to 8 kWatt or more, generally from 10 to 2000 Watt, preferably from 50 to 500 Watt, and more preferably from 100 to 150 Watt.

It should also be noted that excessive heating of the ceramic piezoelectric elements could lead to temperatures being reached which, as a result of the Curie effect, could induce loss of polarization of the ceramic material and, practically speaking, its destruction from the point of view of piezoelectric activity.

The solution to this problem has been found by designing and developing the ultrasonic transducer device according to the invention, particularly with reference to the attached drawings in Figures 1-3.

With reference to Figure 1, the ultrasonic transducer device comprises a sonotrode 100, generally of cylindrical shape, and preferably, as in this case, truncated-cone-shaped, or more preferably with an exponential profile.

The shape of the tip of the sonotrode is not particularly important, but its size, in terms of diameter, must reproduce the diameter of at least the first or second Bessel harmonic of the pressure wave at the tip, after passing through the body of the sonotrode.

The sonotrode is preferably made of metal such as, for example, titanium or iron, or metal alloys, including anticavitation alloys or steel, such as, for example, AISI 304 steel, and subjected to forced polishing or lapping.

This part is to be immersed, as will be seen later, in the working liquid according to the invention.

The sonotrode 100 is mechanically coupled at 108b to a shaped coupling element or booster 101, generically truncated-cone-shaped, which can be made of metals or metal alloys, e.g. steel, and which serves to increase the amplitude of the ultrasonic mechanical oscillations.

The components 100 and 101 are coupled mechanically to one another and to the complex of conductor elements 103 and piezoelectric elements 104, at 108b and 108a, respectively. The conductor elements 103 are made of commercial-type electrical conductor materials, connected electrically in parallel, preferably in the form of disks. The piezoelectric elements 104 are made of ceramic material, again of commercial type, and again preferably in the form of disks. The elements 103 and 104 are organised in pairs in reciprocal mechanical contact with one another. The pairs can be more than one, preferably two and in any event a function of the final cavitation effect on the working liquid. The pairs are also connected, in a way which is in itself known, to the connecting elements 105 for the supply of alternating current electrical energy to produce acoustic or ultrasonic waves with oscillations that verify the frequencies yielded by the equation known in physics as the Rayleigh-Plesset equation, which guarantees that the cavitation threshold is exceeded, preferably in the range from 10 to 30 kHz, within which the device is supplied in order to obtain the resonance of the entire electromechanical transducer-booster-sonotrode complex.

The elements 103, 104 and 105 are encased in housing 102 and perform the function of converting the electrical energy to acoustic or ultrasonic mechanical energy.

The housing 102 is preferably substantially hermetically sealed and has two connections 106 and 107, for the inflow and outflow, respectively, of the coolant, preferably air,

108a and 108b are securing elements, for example in the form of screws, to secure element 100 to element 101 and to secure the latter to the rest of the complex. 109 indicates the air-gap in which the coolant flows, while 110 is the surface interposed between the piezoelectric and conductor element stack and the booster.

With reference to Figure 2, a first particular embodiment of the cooling device for the booster 101 and the sonotrode 100 is illustrated.

Said cooling system comprises a duct 203 in which a coolant is introduced, preferably compressed air pre-cooled and dehumidified after compression. The duct 203 is connected at 203a, 203b and 203c to annular hollow elements generically indicated as 204 that surround sonotrode 100 at a distance from its external surface such as to effectively dispose of the heat generated during operation, so that the sonotrode is always in resonance conditions within the frequency range at which it is used.

The annular elements 204 are equipped with slits in their circumference 204a, 204b, and 204c for the purposes of directing the coolant against sonotrode 100. It should be noted that this system is particularly effective in the case of the use of compressed air applied via duct 203, which, on emerging via the slits 204a, 204b and 204c, undergoes an adiabatic expansion that further lowers the temperature of the air, thus enhancing the cooling efficiency.

The sonotrode cooling circuit and that of the converter can be connected in such a way as to constitute a single cooling system.

With reference to Figure 3, a preferred embodiment will now be described, consisting in an experimental apparatus for verifying the effect of the production of neutrons by ultrasound-induced cavitation.

As can be noted in Figure 3, a first support base 301 is provided to support the first neutron detector 303c.

302 indicates a second support structure for a cavitation chamber 304, containing the working liquid 305 in which the cavitation is produced and the nuclear reaction takes place. Additional neutron detectors are indicated by 303a and 303b.

The neutron detectors 303a, 303b and 303c are typically of the passive type, preferably thermodynamic neutron detectors of the

supersaturated-liquid type, e.g. selected from those available commercially under the name "Defender XL ^® " manufactured by BTI (Bubble Technologies Industries) with head office and production plant in Canada. The Defender detectors are capable of detecting fast neutrons in the energy range of approximately 10 keV to approximately 5 MeV.

305 indicates the working liquid subjected to cavitation.

306 indicates the air cooling device applied, for this embodiment, to the booster complex 310 and the sonotrode 311.

307 indicates the connection of device 306 to the cooling air entry duct.

308 indicates the alternating frequency supply line, preferably in the frequency range from 10 to 30 kHz.

309 indicates the converter of electrical oscillations to mechanical oscillations, containing piezoelectric ceramic elements with intercalated electrical conductor elements (not shown).

310 indicates the booster and 311 the sonotrode with its truncated- cone profile.

312 indicates a first Geiger detector for measuring alpha and beta ionising radiation.

313 indicates a second Geiger detector for measuring gamma ionising radiation.

The sonotrode complex 311 plus cavitation chamber 304 is defined as the piezonuclear reactor, where what is meant by "piezonuclear" is the phenomenon of generating nuclear reactions catalyzed by pressure waves and what is meant by "catalyzed" is that by combining the values of the power, frequency and duration of application of the

pressure waves one can exceed the Minkowskian energy threshold of the nuclear forces, thus producing nuclear radiation.

The power, frequency and duration values can vary, independently and with the device illustrated, preferably in the following ranges ^: from 10 Watt to 25 kWatt, from 10 to 30 kHz, and from 10 to 100 minutes.

The process for the generation of neutrons according to the invention uses the previously described apparatus to generate a particular class of piezonuclear reactions, i.e. those by which, through cavitation, the atomic number of the element or elements treated is modified through leptonic and hadronic interactions beyond the Minkowskian thresholds. It has been verified, in fact, that, with the acoustic waves according to the invention, it is possible to produce conditions for which, in the material subjected to insonation or sonication, the so-called Lorentz invariance for nuclear interactions is no longer valid.

For any atomic nucleus other than hydrogen the hadronic and leptonic interactions respectively govern its stability and instability. Lorentz invariance measures whether the microscopic space of the phenomena is flat, like the Minkowski space," when said variance is not valid, the microscopic space is not flat and the Minkowskian threshold, beyond which the phenomena generated with the process according to the invention are produced, is exceeded. These conditions are realised when the ratio between the nuclear reaction time and the stimulation time by means of the electric force is equal to the ratio between the reaction energy of the Minkowskian nuclear threshold and the electrical energy of action as specified here below.

Existence of an energy threshold for piezonuclear reactions due to cavitation as a result of the Lorentz invariance breakdown for nuclear interaction

For energies E>E ₀ strong = 3.675 • 10 ¹¹ eV we have breakdown of the local Lorentz invariance for strong nuclear interaction, and therefore we are in conditions of temporal and spatial deformation.

For the temporal deformation we have : dthad/dte.m. ⁼ Eo, strong/E

With a five-dimensional rationale, if energy is the effective fifth dimension for the description of the phenomena, then the preceding relation can be interpreted as an equality between two velocities. One is the velocity of administration (action) to the energy atoms by means of electrical interaction, and the other the velocity of response (reaction) with the strong interaction of the nuclei.

Wstrong — Eo,strong/dthad ⁼ E/dte.m. — We.m.

In order that the strong nuclear reaction should reach the breakdown threshold of the local Lorentz invariance, the time taken for collapse of the generic cavitation bubble to occur, for a given electrical energy E, must be such as to furnish an energy velocity W _e .m. equal to the nuclear velocity.

Let dthad be the nuclear reaction time given by dthad = yδt with δt = h/rtin Yukawa time (nuclear year).

To have an estimate of dthad at the Eo,strong energy threshold we can use y = Eo,strong/m _π (being y = E/m time variation coefficient in Minkowskian conditions for E < Eo.strong).

Substituting in the previous relation we have '■

Dthad = (h/m _π ² ) Eo.strong

h = 4.136-10 ¹⁵ eV sec m _n = (mn + mno)/2 = 1.373-10 ⁸ eV

For electrical action energy we have ^:

E = dte.m. Eo.strong (m _π ² /Eθ,strong h) = dt _e . _m . Wstrong it may be noted that since:

We have, for Wstrong:

Wstrong = m _π ² /h = 4.8-10 ³⁰ eV sec ^"1 = 7.6-10 ¹¹ Watt

Consider now that dt _e . _m . is the time of collapse of a microbubble of radius R up to nuclear dimensions, being r = 10 as a result of the effect of the electrical repulsion of the water atoms subjected to the ultrasonic pressure wave. The collapse may occur at the velocity of the sound in distilled water v=v _s =1.4-10 ³ na/sec or at the velocity of the shock wave v=v _S w=4 v _s . Since the wavelength of the ultrasound waves is much greater than the diameter of the microbubbles considered, in any case it will be dte.m. = R/v.

Therefore, for threshold energy Ethreshoid we have:

Ethreshold = (R/v) ^• (m _π ² /h).

The two tables that follow summarise the Ethreshoid values on varying the radius of the microbubbles subjected to collapse for the two possible collapse velocities v _s and v _S w, performing the calculation with the previous relation.

V = Vs

R bubble (metres) 10-6 2-10 ^"6 4-10 ^"6

E threshold (J) 5-10 ² 103 2-10 ⁸

V = V _8W = 4 V ₈

R bubble (metres) 10-6 4-10- ^β 8-10 ^"6

E threshold (J) 10 ² 5 10 ² 2-10 ³

To have stable nuclear reactions and consequently emission of a stable flow of radiation, the system, composed of distilled water containing a substance in solution, must be constantly supplied with an energy E > Ethreshoid to trigger piezonuclear reactions in the Lorentz invariance breakdown condition.

Using a cavitator that absorbs 2000 Watt and is capable of stably furnishing from a minimum of 100 Watt to a maximum of 2000 Watt, we can explore a bubble collapse from 1 μm to 8 μm, considering both

Vs and Vsw = 4 v _s as the collapse velocity.

However, previous experiments conducted with energies of the order of a hundred joules have shown evidence of occurrence of nuclear reactions. This may suggest preferring the shock wave velocity as the collapse velocity and thus the model of the symmetrical spherical shock wave velocity generated around the bubble by the flat ultrasound pressure wave.

Nothing can be said with regard to the total mass of water and compound to be subjected to cavitation, or equally with regard to the amplitude of the ultrasonic wave.

These are phenomenological parameters that have to be determined empirically.

It is obvious that with greater energy supplied there will be correspondingly greater amplitudes and with less energy available for cavitation and bubble collapse there will be correspondingly greater masses subjected to ultrasounds.

The existence of the threshold Ethreshoid for such reactions is a direct consequence of the existence of the E _0;S trong threshold for the hadronic interaction such that for E > Eo.strong the reactions take place in deformed space and time conditions, i.e. non-flat and non- Minkowskian.

This circumstance affords the possibility of discriminating between signals received from the nuclear reactions that have occurred; in fact,

the spatio-temporal deformation for E > Eo.strong absorbs energy at the expense of the nuclear process.

If the nuclear reactions resulting from the reactions between interactive nuclei in the cavitation are constituted by neutrons, they leave the nuclei that have undergone the interaction in an excited rotational state due to conservation of the angular momentum, so that these neutrons are accompanied by a simultaneous emission of gamma radiation due to the de-excitation of the nuclei towards states of lesser energy.

However, if the nuclei have undergone interaction in non-Minkowskian conditions, then the excess energy is part of the energy absorbed by the spatio-temporal deformation, and thus the neutronic radiation is not accompanied by gamma radiation.

The two circumstances of exceeding the energy threshold E > Eo.strong and the emission of neutrons in the absence of gamma emissions produce the complete signal of piezonuclear reactions as a result of the cavitation collapse of gas bubbles in H2O in non-Minkowskian conditions.

The nuclei taking part in the reactions in non-Minkowskian conditions are those of the substances in solution or in suspension in the working liquid, typically H2O, entrained by the surface tension of the bubbles that collapse.

To compare this latter action, it is sufficient to verify that for the distilled H2O subjected to cavitation there is no emission of neutrons without emission of gamma rays even when operating at the threshold

Ethreshold ⁼ E.

By measuring the radiation produced by the piezonuclear reactions generated in the cavitation conditions at or above the threshold it will be possible to determine the radioactive calorimetry of the process produced.

From the theoretical description outlined above we go over now to the description of the process whereby neutrons are emitted as a result of insonation or sonication applied to a working liquid.

The process according to the invention comprises the following stages ^:

• providing a stable working liquid, containing material which, on being subjected to cavitation, produces neutron emissions, where what is meant by a stable working liquid is a liquid free from unstable nuclides, such as thorium or other radioactive elements;

• application, within a vessel or cavitation chamber or reactor containing said working liquid, of acoustic and/or ultrasonic waves, by means of a device for generating said waves, for times and with powers and frequencies such as to exceed the Minkowskian energy threshold;

• allowing the acoustic or ultrasonic waves to pass through the working liquid and operate in such a way that, on impacting against walls of the reactor, they return to the generator, maintaining themselves in phase,'

• collection, by means which are in themselves known, of neutrons generated for subsequent uses.

In particular, the cavitation chamber contains the liquid phase in which material is dissolved or dispersed, so that the working liquid is stable, as defined above. To this solution or dispersion which constitutes the working liquid the cavitation is applied by means of the device according to the invention. The working liquid is preferably an aqueous solution containing compounds capable of forming a solution or even a dispersion with it. The compounds that can be used may be of any type, i.e. one can use any compound or substance which is capable of being retained by the surface tension of the bubbles naturally present in the working liquid, this compound or substance being capable of being dissolved in solution or in the form of a fine

dispersion of solid particulate matter. Preferably, the compounds are compounds which are easily dissolved or dispersed in the working liquid, e.g. water, preferably the compounds are selected from those of elements with atomic mass number ranging from 6 to 250, or from 12 to 200, or from 16 to 150, or from 35 to 75 (see Figure 7). Particularly preferred are iron and its salts, particularly iron nitrates or chlorides.

The expert in the field, on the basis of his or her own knowledge and the indications provided in the present description, is capable of identifying the operating conditions to implement the process with different materials and solutions. The process can, in fact, be applied to other soluble elements and other types of solvents, in addition to water and iron salts.

The concentration is not a binding parameter; it has been verified, however, that the greater the concentration of the solution, the greater will be the dose of neutrons produced, as illustrated in the graphs in Figure 8, on progressing from 0 ppp to 10 ppm of iron. On the χ-axis of each of the graphs (Figures 8A, 8B, 8C, 8A', 8B', 8C) is indicated the time in minutes, and on the yaxis the dose of neutrons produced in nSv units (nanosie verts).

Once the cavitation chamber has been filled with the solution or the dispersion in which the process is carried out, the sonotrode is immersed in it. The immersion of the tip in the solution will be chosen in such a way as to achieve maximum efficiency transmission of the ultrasounds for the purposes of the neutron production process. In general, the greater the immersion of the sonotrode in the solution, the greater will be the transfer of ultrasonic power.

For the purposes of achieving efficiency of the process it is also advisable to bear in mind the distance of the walls of the reactor from the sonotrode and particularly the conformation of the bottom of the latter. It is, in fact, advisable that the conformation of the bottom of the reactor should be such as to maximize the reflection of the pressure

waves emitted by the sonotrode. It is also advisable to choose the immersion of the sonotrode with care so that, in the central part of the reactor, i.e. the area between the immersed end of the sonotrode and the bottom of the cavitation chamber, the direct waves emitted by the sonotrode and those reflected by the bottom should be in phase, so as to maximise the efficiency of the cavitation phenomena that produce the neutron emissions. All these parameters can be easily optimised by the expert in the sector, in that the verification of the "in phase" condition between the direct and reflected waves is an experimental verification with which he or she will be very familiar. For example, the immersion varies in the range of ratios from 1/5 to 1/10 of the maximum dimension of the cavitation chamber in relation to the length of the sonotrode. In a preferred embodiment of the invention, the length of the sonotrode will be substantially equal to that of the cavitation chamber.

Once the tip of the sonotrode has been positioned correctly within the reactor, a compressor will be activated to circulate the air in the cooling circuit and convey it, once cooled, into the converter and around the booster and sonotrode so as to maintain a constant resonance frequency of the converter-sonotrode-booster system.

The amplitude of the ultrasonic vibration with which one wishes to irradiate the solution is then set, and is generally indicated in percentage terms.

The amplitude, which may range from 10 to 50 μm, preferably from 20 to 30 μm, can be selected on the front panel of the generator and may range from a minimum of 50% of the maximum amplitude of the phenomenon to 100%. In typical immersion conditions, the transfer of power in the solution may range from 10 to 1000 Watt, preferably from 50 to 500 Watt, and more preferably from 100 to 150 Watt. Once the amplitude has been set, cavitation of the solution is initiated. The duration of the cavitation, which is a function of reaching the Minkowskian limit of the nuclear interactions, ranging from 50 to 500

GeV, will be, for example, of the order of 60 minutes or more, preferably 100 minutes or more.

The temperature at which the cavitation is initiated is the temperature at which the solution is in the liquid phase. In the case of aqueous liquids, the temperature will be in the 0-80 ⁰ C range.

The neutron radiation thus produced is composed both of slow neutrons and epithermal and fast neutrons and, when appropriately directed with devices which are in themselves known, can also be used for industrial purposes, as described here below, particularly for the generation of energy and the production of materials by means of neutron/nucleus reactions.

For the exploitation of the neutrons generated according to the process described above, generally material dissolved or dispersed in a liquid phase is used. Particularly preferred is an aqueous solution containing iron, such as, for example, iron nitrate or iron chloride, to which are added substances containing the elements whose nuclei are useful for the exothermic and endothermic reactions induced by the neutrons. These substances, with which the expert in the field is familiar, consist preferably in the elements to the right and left of the iron in the graph of the energy binding per nucleone shown in Figure 7. Said elements to the right and left can be bound to the iron in a chemically stable way in standard temperature and pressure conditions (27 ⁰ C; 1 atm.) to yield soluble compounds or compounds in an easily dispersible form in the liquid medium in the same standard conditions.

For the exothermic reactions that generate energy in useful quantities (that is to say, at least three times greater than the energy consumed to generate the process), the substances particularly preferred are selected from among the chemical compounds containing elements selected from the group consisting of boron, chloride, carbon, silicon, potassium and mixtures thereof, for example, borides, borates, carbonates, silicates, chlorides, chlorates, elements containing iron,

and other metal elements such as alkaline and alkaline-earth elements, preferably used in combination with iron ions in solution or in aqueous dispersions. Examples of such compounds are: boric acid in combination with iron chlorides or nitrates.' sodium bicarbonate in combination with iron chlorides or nitrates; potassium chloride in combination with iron chlorides or nitrates; and mixtures of said compounds. For the purposes of the production of energy these compounds will hereinafter also be referred to as the "active medium".

For the endo- and exothermic reactions that do not produce useful quantities of energy, any chemical compound containing metals and metalloids and which is solubilised or dispersed in a liquid can give rise to transformation reactions of the matter of the compounds themselves, and such transformations are determined by the request of the user, which involves the choice of the relative neutron dose to be used.

The exploitation of the reactions (I), (II) and (III) indicated above depends on the reaction impact sections of the neutrons at different energies generated by the piezonuclear processes.

The device that will be illustrated here below and is shown in Figure 9 exploits the above-mentioned cavitation processes and makes it possible to realise direct reactions without the intermediation of the neutron, for example, for producing rare elements, such as tellurium, which can be obtained by means of a type (III) endothermic reaction.

The expert in the field, through his or her own knowledge and the indications provided by the present description, is capable of identifying the operating conditions to conduct the process with different materials and solutions. The process, in fact, can be applied to other soluble or dispersible elements or compounds and to other types of solvents in addition to water and iron salts.

The neutronic radiation produced by applying sonication to the active medium can be modulated in the condition ranges described above for the purposes of obtaining lowenergy thermal neutrons and epithernαal and fast neutrons of higher energy; therefore, in its entire spectrum, it is useful for inducing exo- and endothermic reactions of the neutron- nucleus type, suitable for producing modification of matter in the cavitation chamber.

In the event one wishes to give precedence to the production of energy, which is certainly the most interesting from the application point of view, [see reaction (I)] exothermic reactions will be used which release energy in useful quantities, selecting the most appropriate active medium, for example, one of those as indicated above, and the systems described here below.

The inventor, when carrying out the neutron emission experiments, observed, in particular, two important unexpected phenomena. The phenomena observed were those of evaporation at low temperature and production of new matter as compared to the matter initially present in the working liquid. In particular, he noted the generation of ammonia, when, in the cavitated liquid, the chemical element "nitrogen" was present as nitrogen gas, a component of the air dissolved in said working liquid. The inventor therefore deduced that the generation of neutrons by sonication and cavitation of a working liquid is accompanied not only by production (or absorption of energy), but also by the modification of matter, as a function of the nature of the liquid to which the sonication and cavitation are applied.

It is important to note that ammonia is currently produced by means of the following direct reaction^

3 H2 + N ₂ → 2 NH3 (Haber process)

The process is conducted in the presence of catalysts, at high pressure and temperature, typically 20 MPa and 400-500 ⁰ C. The reaction is

exothermic. Suitable catalysts are those based on osmium, ruthenium, uranium or iron: generally, iron is used, and the catalyst is prepared starting from magnetite (FeO, Fe2θs).

The consumption of energy and the difficulties associated with the traditional processes of this type are very evident.

A layout of a plant for advantageously exploiting the energy of the reactions produced by the neutrons obtained through the application of ultrasounds to substances in solution or dispersion is schematically illustrated in Figures 4 and 5 described here below.

With particular reference to Figure 4, the plant illustrated comprises a storage tank 410 containing, for example, water and an active medium as described above

Liquid 411 from the storage tank 410 is conveyed via the duct 413 to an insonation or sonication ultrasound device comprising at least one cavitator 416 with the production of cavitation effects that generate neutrons that trigger the exothermic nuclear reactions capable of bringing the working liquid to evaporation under pressure in a cavitation chamber 414 equipped with a sealed cap 417. The vapours thus produced under pressure are conveyed by the duct 419 and used to drive a turbine 420 or other means of conversion of thermal energy to mechanical energy, and then the mechanical energy or electrical energy produced with conventional alternators is used directly, the cycle being completed by a condenser of the vapour that has done its work.

It has been experimentally verified that the liquid condensed from the vapour may be appreciably different from the liquid initially present in the cavitation chamber, in that it is not composed exclusively of the starting liquid, but contains one or more end products of the neutron- nucleus reactions taking place in the liquid reaction medium due to the application of insonation or sonication. These end products may

themselves constitute useful material for commercial exploitation purposes.

From the experiments conducted no radioactivity has been found to be present above the natural background value for starting substances subjected to ultrasounds and sonication. A detector specifically constructed for checking for any presence of ionising radiation is described in Figure 10 and can be used in conjunction with any neutron generation system according to the present invention.

With reference to Figures 4 and 5, which schematically illustrate small- and large-scale systems for the production of energy by means of a device suitable for producing piezonuclear reactions by means of one or more sonotrodes, a storage tank 410 is shown, containing a liquid 411 with an active medium, storage tank 410 being used in conjunction with a pressurising device 412 suitable for pressurising the system for the recovery of energy in the from of vapour.

By means of a pipe or duct 413 which leads from the storage tank 410, the liquid is conveyed to a cavitation chamber 414 up to a level 415 such as to allow suitable immersion of the sonotrode or sonotrodes used.

In the liquid 411, substantially at the height of the level indicated by 415, at least one sonotrode 416 is partly immersed, contained in a sealed housing 417.

As can be noted in Figure 4, the sonotrode 416 is only partly immersed in the liquid 411 contained in the cavitation chamber 414, the depth of immersion being a function of the degree of control of the production of vapour which one wishes to achieve. The only expedient needed is that the tip of the sonotrode should always remain at least partially in contact with the liquid and that it should never be completely uncovered, for fear of damaging the device.

In the upper part 418 of the cavitation chamber is collected pressurised vapour generated by the nuclear reactions. This vapour is conveyed, always under pressure and via the duct 419, to a turbine 420 to yield mechanical energy, and is then recovered in 421 by means of condensation devices of known type.

The shaft 422 of the turbine directly supplies mechanical energy or may be coupled to an alternator or other type of electrical generator for utilisation.

Figure 5 schematically illustrates a large-scale plant.

The plant in Figure 5 is a plant for the production of electrical energy. 525 indicates a set of compressors for the basic pressurising of the working liquid, equivalent to the element 412 in Figure 4. A second element of the system consists in the tank 511, connected to the compressors via the pipes 523 and to the compression chamber 514 via the pipes 513. The apparatus comprising the sonotrode or sonotrodes is not shown. The vapour generated in the cavitation chamber 514 is transported, via the forced duct 519, to the turbine and to the alternator, not shown, housed in chamber 526, which in turn is connected to the electricity mains via the cables 527.

In the plant according to the invention, the neutrons produced in the cavitation chamber 414 or 514 generate nuclear reactions without any emission of ionising radiation, contrary to what happens in nuclear reactors of the fission type and in the experimental nuclear fusion systems. The neutrons thus generated can be used in the reactions (I), (II) and (III) indicated above.

The plants according to the invention are designed for the generation of exothermic reactions suitable for the production of vapour, and thus of energy useful for civil purposes without any generation of ionising radiation dangerous for living beings, which would make it mandatory to use heavy, expensive shields, with the risk of serious hazards for the

operators and the environment.

The plants according to the invention can therefore replace the traditional nuclear reactors, in that they constitute equivalent systems, nevertheless, by exploiting completely different reaction mechanisms, they present the advantage of not using highly radioactive substances such as uranium or plutonium, do not generate ionising radiation and are capable of avoiding the production of radioactive waste, yet do the work of a nuclear reactor, that is to say, producing useful energy.

When the plants according to the invention are made to operate in such a way as not to produce useful energy, they can be used to obtain modified matter, in the sense that they can produce different materials from those initially introduced into the cavitation chamber, and this by virtue of the piezonuclear reactions and the neutrons released by them, , as mentioned above.

Another preferred embodiment of the invention is illustrated in Figure 9 and will hereinafter be referred to overall as an ultrasonic reactor.

The reactor in Figure 9 exploits the two most evident and unexpected phenomena observed by the inventor in the course of the neutron emission experiments. As mentioned above, the two phenomena observed were low-temperature evaporation and the production of matter, specifically ammonia.

The layout of the reactor is, of course, purely indicative, but it is important to stress that, in the event that one wishes to use it for the production of electrical current, it can be designed in such a way as to be completely compatible with the general plant and systems existing in the present thermoelectric power stations so as to constitute a substitute for the boiler units; it can therefore be installed in an already existing production plant, imagining it as a closed body with simple points for the traditional external connections (turbines,

capacitors, pumps, etc.). In practice, the part of the reactor illustrated in Figure 9 that lies within the dashed rectangle can replace the boiler of a conventional thermoelectric power station. In addition, the reactor also permits the generation of useful and usable matter, much in the same way as a chemical synthesis plant would do.

The reactor in Figure 9 was conceived in a modular mode and comprises a primary reactor operationally connected to a secondary reactor. The primary reactor, substantially equivalent to the device illustrated in Figure 3, inside which are generated the neutrons that can be used in the secondary reactor, comprises a cavitation chamber and sonotrode and a primary working liquid. The secondary reactor comprises a second chamber containing a secondary working liquid into which the neutrons generated in the primary reactor are conveyed for further use.

In the embodiment illustrated in Figure 9, the primary reactor 91O e housed inside the secondary reactor 920 with the aid of elastic means 921 designed to absorb the vibrations produced by the sonotrode 901, so as to reduce, where possible, the power absorbed by the entire apparatus when operating at full regime.

In greater detail, the ultrasonic reactor 900, illustrated schematically in Figure 9, is circumscribed within the dashed rectangle. It comprises a primary reactor 910 and a secondary reactor 920. The primary reactor 910 comprises at least one ultrasound generator (not shown) containing at least one sonotrode 901 connected to it (connections not shown) and immersed in the primary working liquid 902 located in the cavitation chamber 912. A fundamental requisite for the efficient operation of the reactor is that the tip of the sonotrode 901 should always remain immersed in the liquid medium; for this purpose, the reactor is equipped with consumed liquid replenishment systems and suitable level sensors (not shown). The primary working liquid 902 typically contains compounds in solution or suspension, particularly iron chlorides, as mentioned above. The primary reactor 910 is housed

within a sealed system (not shown) for recovery of the vapour generated during the piezonuclear reactions. The primary reactor 910 is partly immersed in the secondary reactor 920, from which it is separated by elastic means 921, one end of which rests on the walls of the cavitation chamber 912 and the opposite end on the walls of the tank 922 of the secondary reactor 920. Said elastic means 921 increase the efficiency whereby the sonotrode 901 transfers the ultrasounds to the working liquid 902 of the primary reactor 910.

The secondary reactor 920 comprises a tank 922 containing the secondary working liquid 903. Said secondary working liquid 903 is preferably a liquid containing one or more boron-based compounds in solution (also as gas), or in suspension or dispersion,' particularly preferred are boric acid and its salts.

According to an alternative construction of the reactor 900, the secondary reactor 920 is replaced by a neutronic-dosimetry passive control device, which may have the same set-up as the secondary reactor 920 described above, but in which is present at least one element containing boron-based particulate material, for example, boric acid or a borate in granule form or some other type of boron-based solid particulate matter. This device constitutes the passive control system for the operation of the reactor and measures the amount of energy released in the primary reactor 910.

The reactor system 900 also comprises a set of circuits, in the form of interdependent ducts, designed to transport the energy and/or the matter developed in the primary and secondary reactors to the outside. Among the system elements necessary for operation and with which the expert in the sector will be familiar, such as pumps, turbines, exchangers, valves, flowmeters, level sensors, pressurising systems, etc., Figure 9 shows a first turbine or set of turbines, also called the first power unit 904, a second turbine or set of turbines, also called the second power unit 905, a plurality of valves 906, and one or more condenser/heat exchanger units 907.

The first circuit A comprises one or more ducts 914 originating from the primary reactor 910, passing into the secondary reactor 920 and leading to the collector 911, from which they emerge as ducts 915 that lead to the first power unit 904.

The second circuit B comprises one or more ducts 916 originating from the first power unit 904, which pass through the secondary reactor 920 and emerge from it either by means of the duct or ducts 916' which lead to the second power unit 905, or, according to an alternative not shown, connect up with the duct 915 of the first circuit A via the collector 911.

From the second power unit 905 come out one or more ducts 917 which lead into unit 907, external to the ultrasonic reactor 900, from which one or more ducts 918 exit and lead to the primary reactor 910.

The circuits A and B may be constructed with independent lines between them that connect up in collector 911.

From the operational point of view, the first circuit A collects the cold vapour generated in the primary reactor 910, and coveys it via the duct 914 through the secondary reactor 920 where the thermal energy of the nuclear reactions generated there, with the aid of pressurising devices (not shown), transform it into pressurised vapour which is then conveyed via the duct 915 to the power unit 904 for energy exploitation.

The vapour exiting from the power unit 904, which is of the low- thermal-energy type, is conveyed via the duct 916 into the secondary reactor 920 (circuit B), where it regains energy and returns to being pressurised vapour thanks to the neutronic reactions generated in said secondary reactor and to possible pressurising devices (not shown). From the secondary reactor 920, via the duct 916', the pressurised vapour is conveyed to the power unit 905 for industrial exploitation. In

this power unit 905, too, as in the previous power unit 904, the vapour emerges at low thermal energy and is conveyed by the duct 917 into the unit 907 where it gives up further thermal energy. The function of the unit 907 is to recover, through heat exchange, fluids that are still useful for the system, which, for example, can be conveyed, via the ducts 918 and 918', to supply the primary reactor 910, thus contributing towards maintaining the liquid level in the cavitation chamber. The ducts 918 and 918' are thermally insulated or external to the reactor 920.

The collecting circuit C comprises one or more ducts 919, possibly thermally insulated or external to the reactor 920, which originate from the primary reactor 910 leading to the unit 907 and exiting to the outside. Said circuit C collects the substances (including ammonia) produced by sonication in the primary reactor 910. In a preferred embodiment not shown, the ammonia generated is in the form of ammonium ions which, via the duct 919, are conveyed into a suitable vessel 923 containing a base, e.g., NaOH, and is then conveyed to the unit 907 with the function of a heat-exchanger fluid. At the exit point from the condenser 907, this product can be stored for industrial purposes.

A first supply circuit equipped with ducts 908 comes from the outside and supplies the secondary reactor 920 with working liquid.

A second supply circuit equipped with ducts 909 comes from the outside and supplies the primary reactor 910 with working liquid, typically water possibly containing iron chlorides. In the variant illustrated in Figure 9 said duct 909 is connected to the duct 918 leading from the unit 907 and conveys the recovery liquid to the primary reactor.

A third supply circuit equipped with ducts 913 (optional) conveys liquid, typically water, from the outside to the secondary reactor 920 where it is transformed into pressurised vapour by means of energy

released by the nuclear reactions, said pressurised vapour being conveyed via the collector 911 to the first circuit A or to the second circuit B and ultimately arriving at the respective power units 904 and 905.

The unit 907 receives the entry of the fluid from the power unit 905 via the duct 917 and, after lowering its temperature, conveys it, via the duct 918, 918', to the primary reactor 910.

The following reactions take place in the primary reactor 910:

• generation of neutrons by means of piezonuclear reactions produced by ultrasounds and cavitation;

• generation of cold vapour (not produced by boiling phenomena) by means of piezonuclear reactions produced by utrasounds and cavitation,"

• generation of matter different from that initially present in the reactor, obtained both by piezonuclear reactions and by sonochemical reactions, the latter being produced by the sonication of the primary working liquid 902. By sonication the inventor has obtained the production of ammonia in ammonium ion form.

Thus, to sum up, neutrons, cold vapour and new substances are obtained in the primary reactor 910.

We should also recall that the slow neutrons (so-called thermal neutrons) with energy ranging from 0.25 eV to 2.5 eV remain inside the primary reactor 910 and are capable of transforming matter, whereas the epithermal and fast neutrons are capable of exiting from the primary reactor, to be conveyed possibly to the secondary reactor 920, and can be used to generate exothermic nuclear reactions capable of supplying useful thermal energy and matter.

The secondary reactor 920, as mentioned above, receives the neutrons produced in the primary reactor 910 and generates exo- or endothermic nuclear reactions as a function of the nature and type of the working liquid 903. In the case of boron- and iron-based compounds, the reactions are exothermic reactions that release industrially exploitable thermal energy.

Figure 10 schematically illustrates a passive control device for the operation of the sonotrode/working liquid complex, developed in the course of the experimentation conducted by the inventor and illustrated above. The device can be advantageously used in conjunction with the device in Figure 3 or with the systems in Figures 4, 5 or 9.

The device schematically illustrated in Figure 10 comprises a first sealing element, or upper cap 111, and a second sealing element, or lower cap 112, of a container equipped with walls 113, illustrated here with cylindrical symmetry. The lower sealing element 112 bears a support 114, shaped in its upper part so as to lodge in and be solid with an element 115, preferably of prismatic shape, consisting of, or bearing a sensitive plate, selected, for example, from those known as CR 39 or LR 115, marketed by FGM Ambiente, Milan.

The container, preferably made of PVC, closed at the top and bottom, is filled with a neutron-detecting material, typically granular boric acid (typical mean granule size: 0.5 mm). Said material is suitable for transforming the neutrons that impact against it into specific ionising radiation detectable by the sensitive plate. The conversion takes place according to the following reaction:

a

The device in Figure 10 can be used in conjunction with the cavitation chamber and can be used not only for detecting and quantifying its efficiency in the production of neutrons, but also for comparing its

functioning with that of a classic nuclear reactor and thus for determining the size of a possible secondary reactor, such as, for example, the one illustrated in Figure 9, in relation to that of the primary reactor.

The advantages of the process according to the invention are the following^

• the neutron radiation dose generated is not dangerous and certainly not lethal for living beings;

• the generation of neutrons occurs without the need to supply high-energy nuclear reactions from outside, but only by using sound waves J

• the generation of neutrons occurs in the absence of production of ionising radiation (gamma radiation); verification, as described above, can be done by means of suitable detectors such as Geiger counters or CR39 polycarbonate plates, also with the device described above and illustrated in Figure 10; energy radiation ranging from 40 keV to 4 MeV can be measured;

• the neutron radiation is produced in an atmospheric environment and the bubbles that intervene in the phenomena generating this radiation are those naturally present in the liquid used; the material used, contained in the cavitation chamber, is not radioactive, and generates neutrons only under the effect of the pressure waves and when this effect ceases the emission of neutrons also ceases and the material remains non-radioactive, with the evident advantage of greater safety for the operators;

• the apparatus according to the invention constitutes a substitute for the fission nuclear reactor, producing similar results, which can be exploited by the existing nuclear industry with the

additional advantage of having to consume at the point of origin only non-radioactive substances and electromechanical energy.

Moreover, according to the invention a new energy production process is also obtained without excessive consumption of raw materials and without using high-tech structures and avoiding the excessive risks related to the release of spurious radiation. In addition, the generation of new matter can be obtained.

Further advantages of the process according to the invention are the following-

• the generation of neutrons occurs without the need to supply high-energy nuclear reactions from outside, but only by using sound waves;

• the generation of neutrons occurs in the absence of production of ionising radiation, particularly gamma radiation! verification was achieved by means of suitable detectors (Geiger counters, CR39 polycarbonate plates);

• the neutron radiation is produced in an atmospheric environment and the bubbles that intervene in the phenomena generating this radiation are those naturally present in the liquid used!

• the neutrons generated, for example, have an energy in the 100 keV to 15 MeV range and the doses produced, though useful for inducing reactions that modify materials, are neither lethal nor damaging for living beings.

The following examples are given to illustrate the invention and are not to be regarded as limitative of its scope.

Example 1

The process consists in the cavitation, by means of the machine described in Figures 1-3, of 250 or 500 ml of an aqueous solution containing iron.

An empty bottle is taken, which acts as a cavitation chamber, with a capacity of 250 ml, made of pyrex or duran according to the concentration of the solution one wishes to cavitate; a given amount of a standard solution of 1000 ppm of iron chloride in hydrochloric acid or of a standard solution of 1000 ppm of iron in nitric acid is added, and the total is brought up to 250 ml with double -distilled deionised water.

Experiments were conducted with solutions containing 0 ppm, or 1 ppm, or 10 ppm of Fe ³⁺ (Figures 8A, 8B, 8C and 8A', 8B', 8C). In the first case, the amount of standard is equal to 250 μl, brought up to 250 ml with double -distilled deionised water, while in the second the amount of standard is equal to 2500 μl, brought up to 250 ml with double-distilled deionised water. In the case of a 1 ppm concentration in the solution, 4.5 10" ⁶ moles of iron are present, while in the case of a 10 ppm concentration, the number of moles present in solution is obviously 4.5-10' ⁵ .

Once the bottle has been filled, the sonotrode is immersed in the solution. Immersion of the tip in the solution will be chosen in such a way as to achieve maximum efficiency of transmission of the ultrasounds for the purposes of the neutron production process. It should be noted that, in general, the greater the immersion of the sonotrode in the solution, the greater will be the transfer of ultrasonic power. However, it is necessary in this case to bear in mind the presence of the walls of the bottle and particularly the bottom of the latter. The bottle was chosen in such a way that the bottom was the most appropriate for reflection of the pressure waves emitted by the sonotrode. In this sense, then, it is necessary to choose the immersion of the sonotrode with care so that, in the central part

of the bottle, i.e. the area between the end of the sonotrode and the bottom of the bottle, the direct waves emitted by the sonotrode and those reflected by the bottom should be in phase, so as to maximise the efficiency of the cavitation phenomena causing the emission of neutrons. Immersion depths of the sonotrode ranging from 1 centimetre to 10 centimetres were used.

Once the tip of the sonotrode has been positioned correctly within the bottle, with the immersion selected, a compressor is activated which begins to circulate the air in the circuit that cools it, and the air, once cooled, is then conveyed into the converter and around the booster and sonotrode.

The ultrasonic vibration amplitude with which one wishes to irradiate the solution is then set on the generator. The amplitude, selected on the front panel of the generator, was set at 50% and 70% of the maximum amplitude (equal to 30 μm). In the above-mentioned immersion conditions, the transfer of power into the solution was 100 Watt and 130 Watt, with energies of 0.54 MJoule and 0.70 MJoule. Once the amplitude has been set, the cavitation of the solution is initiated. The duration of the cavitation is 90 minutes during which the neutrons are measured by means of thermodynamic neutron detectors consisting of a fluid in conditions near to boiling, which, if struck by neutrons in an energy range from 10 KeV to 15 MeV, comes to the boil and thus forms bubbles clearly visible to the naked eye in the detector. The number of bubbles is proportional to the neutron dose emitted. The formation of the bubbles, and thus the increase in their number may occur either linearly or non-linearly over time. Five neutron detectors of the above-mentioned type were used, some of which are not visible in Figures 5-14, and two of which are placed horizontally adjacent to the bottle in positions diametrically opposite the cavitation. The third detector is placed horizontally beneath the bottle along a line parallel to the plane in which the first two detectors lie. This detector is perpendicular to the axis of the sonotrode. The last two detectors are placed vertically and thus

parallel to the sonotrode at a distance of about 10 centimetres. They are surrounded by 2.5 centimetres of material sensitive to the neutrons, particularly boron powder (a neutron absorber) for one and carbon powder (a neutron moderator) for the other. Thus, the first two detectors are not shielded, i.e. no kind of absorber or moderator is present between the internal area of the bottle where the cavitation takes place (in actual fact, 1 centimetre of water is present which acts as a moderator and the glass of the bottle which, in contrast, is transparent to the neutrons); the third detector is shielded by a 10-centimetre-thick layer of water, and the fourth and fifth detectors, as already mentioned, are shielded by boron and carbon. It should be pointed out that the bubbles present in the detectors are not due to the ultrasounds for various reasons. In the first place, if they were due to ultrasounds, the bubbles in the detectors would be concentrated in a limited volume of the detector as close as possible to the source of the ultrasounds, whereas they are distributed throughout the entire volume.

Secondly, if the ultrasounds were the cause of the bubbles in the neutron detectors, the latter should be present in all the experiments conducted. On the contrary, bubbles were present only in the experiments in which the solution contained iron, whereas, in the tests with other elements, there was no evidence of bubbles in detectors ten times less sensitive to neutrons, but equally sensitive to ultrasounds.

From comparison of the results obtained in the various experiments performed with different concentrations and different amplitudes, that is to say different powers, it emerges that the neutron dose produced increases with the increase both in the amplitude of the ultrasonic pressure wave, given the same concentration, and with the increase in concentration, given the same amplitude. The duration of all the experiments was 90 minutes.