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21
Rakhimov R.Kh., Makhsudov A.U., Zufarov M.A.
NUCLEAR-RADIOACTIVE REACTIONS IN EARTH CRUST THE GENERATOR OF EARTHQUAKE HARBINGERS
Rakhimov Rustam Kh., doctor of technical Sciences, head of laboratory № 1, Institute of materials science «Physics-sun», Uzbekistan Academy of sciences. Tashkent, Uzbekistan. E-mail: rustam-shsul@yandex.com
Makhsudov Asatulla U., elder science researcher Physical-Technical Institute, «Physics-Sun», Uzbekistan Academy of sciences. Tashkent, Uzbekistan. E-mail: asaduz50@rambler.ru
Zufarov Mars A., elder science researcher Physical-Technical Institute, «Physics-Sun», Uzbekistan Academy of sciences. Tashkent, Uzbekistan. E-mail: asaduz50@rambler.ru
Abstract. The article offers a method to predict earthquakes based on recording earthquake harbingers that are variations of neutron fluxes and intensity of charged particles of the earth's crust. The obtained result indicates a possibility to determine an earthquake 10 hours and even longer in advance with an indication of the epicenter. Different earthquake precursors forming fluxes of neutrons and charged particles in nuclear and radioactive reactions with the earth's crust are mentioned herein.
Items: fission, neutron flux, charged particles, seismic activity, energy, detector.
ИОНИЗАЦИОННЫЕ РЕАКЦИИ ПРЕДВЕСТНИКОВ ЗЕМЛЕТРЯСЕНИЯ В ЗЕМНОЙ КОРЕ
Рахимов Рустам Хакимович, д-р техн. наук, зав. лабораторией № 1 Института материаловедения НПО «Физика-Солнце» АН РУз. Ташкент, Узбекистан. E-mail: rustam-shsul@yandex.com
Максудов Асатулла Урманович, старший научный сотрудник Физико-технического института НПО «Физика-Солнце» АН РУз. Ташкент, Узбекистан. Е-mail: asaduz50@rambler.ru
Зуфаров Марс Ахмедович, старший научный сотрудник Физико-технического института НПО «Физика-Солнце» АН РУз. Ташкент, Узбекистан. Е-mail: asaduz50@rambler.ru
Аннотация. В работе предложен метод прогнозирования землетрясений, основанный на регистрации предвестников землетрясений-вариации потоков нейтронов и интенсивности заряженных частиц земной коры. Полученный результат указывает на возможность за 10 и более часов определить землетрясения с указанием направления ее эпицентра. Приводятся различные предвестники землетрясения образующие потоки нейтронов и заряженных частиц в ядерно-радиоактивных реакциях с атомами земного вещества.
Ключевые слова: распад, нейтронный поток, заряженные частицы, сейсмоактивность, энергия, детектор.
Introduction
Before any earthquake occurs, vast space and territory participate in the epicenter where precursors are registered in different geophysical and geochemical parameters that could be used to possibly create prediction methods. Along with accumulated mechanical deformational energy in a seismically active zone radioactive gases are forced out and they are spread intensively in the region. Nuclear fission along with emission of heavily ionizing particles (protons, alpha particles and neurons) takesplace. One of the main participants of this phenomenon is a radioactive Radon 222Rn, a-emitting gashaving a half-life of 3.825 days with energies of 5.49 MeV. Its isotope Thoron (220Rn)with short half life of 54.4 seconds is a faster short-lived, though more intensive source of a-particles with energies of 6.29 MeV [1].Thus, their a-fissionoccurs,which in reaction with atomic nuclei delivers neutron flux from charged particles. Duringseismicactivityofearth-layerstheseparticlesdeviate from balanced state and their flux increase before the earthquake. At the time of multi-scattering
and reacting with earth substance nuclei, the particles reach the earth surface and are found during the recording.
The average Radon level in a quiescent state is constant and the decrease of its concentration caused by fission and scattering from massif into the air is further compensated by new generation in earth layers during radioactive disintegration of Uranium (Radium) elements. The value and dynamics of emission of radioactive gases and fluxes of ionizing particles is defined by the natural radioactivity of elements and isotopes in the ground.
Intensity variation of delivered neutron fluxes and charged particles are being studies as precursors of the earthquake. We have offered a nuclear physical method of predicting earthquakes based on recording variations of neutron and charged particle fluxes. An experimental device has been designed to study temporary variations of neutron fluxes and intensity of charged particles. The device records signals predicting and specifying direction of the epicenter in 2n geometry and has been placed in the socle block of the building to reduce cosmic
rays contribution by 2.3 times. The device operates on a tracker mode and starts recording signals from detectors as soon as neutrons and charged particles fluxes ascend. Their fluxes increase by tens of times 2-3 days prior to earth temblors with the maximum of recorded signals practically corresponding with the earthquake periods [4, 5]. In 2016 upon modernization of the device, on 8th of July before the earthquake in Kyrgyzstan (M4.4) a 600 relative unit signal was recorded. On 23rd of August prior to the earthquake in Japan (M5.7) the signal was ~450 relative units along with determination of the epicenter location [6, 7] in the Eurasian region with the magnitude above 3.
Radon emanation
.'• '. ••• •.'• '.'• '••' '• •'.'.'. .oré'-.' ; '.'. ;
Target research spectrum
Radon behavior: all area
Radium distribution: radium layer thickness adjusted
Leveling-off radon emanation: adjusted by normalization factor
Fig. 1. Schematic representation of a grain and the influence of irradiation. The outer skin is removed by etching to remove the effect of a-radiation [2].
We believe that the ascertained correlation of a sharp signal variation coming from the earth particles points at the possibility to predict earthquakes with determining of the epicenter direction. A network of minimum three devices placed in a triangle
Nuclear fission
Y
within 250-300 km from each other is needed to determine and compile the epicenter location and coordinates precisely. At the moment such devices are being installed in Fergana and Samarkand cities.
Radon is considered a quick response gas to deformation of earth layers. The reared other products received after reactions of nuclear and radioactive elements that also participate in generation of ionizing radiation particles.
Nuclear and radioactive sources of ionizing particles
The discovery of a- and P-radioactivity has started contemporary nuclear physics. Thirty natural a-active nuclei in chain decay are known that belong to uranium, thorium, actinic and radium series.
The nuclear emission is usually understood as particle fluxes, such as electrons, protons, a-particles, neutrons, photons, fission fragments and etc. These particles interact with electrons, atoms, earth environment nuclei in the result of Coulomb, electromagnet and nuclear forces interaction. Considering that the interactions could be elastic and inelastic, the number of different processes of nuclear active reactions will be very significant.
As a probing candidate of the inner layers of the earth's crust, it is necessary to adopt a change in the intensity of the neutron flux and charged particles, which deviate from the equilibrium state to earthquakes.
When a a-particle interacts with the atom nuclei in the earth's crust, a neutron flux is produced. The formation of a neutron can occur at any energy of a-particles, though below the energy emitted by the nucleus. For most elements, the energy does not exceed 2 MeV; however most of the neutrons experiencing inelastic scattering have energies below 5-6 MeV. At high energy due to inelastic scattering, the light and heavy elements of the atoms of terrestrial matter lead to a significant slowdown of the primary neutrons, and these nuclei become effective in the reactions with the neutrons.
In interaction with the earth's crust matter, neutrons exhibit a variety of energy-dependent properties caused by neutron-nuclear reactions, and nuclear transformations in the scattering or absorption of neutrons. Nuclear reactions with the absorption of neutrons lead to the formation of protons, a- particles, isotopes in the excited state, and other secondary particles. The a-particle (of He4 nuclei) interacting the earth's crust atoms forms four times as many electrons as protons moving at the same velocity. Thus, accumulatively, an electric current arises in the earth's crust that further can be considered an earthquake precursor.
Alpha particle radiation
X Daughter nucleus
Daughter nucleus
Parent nucleus
ir nucleus
Fig. 2. Radioactive nucleus fission and formation of X-isotopes followed by neutron release
Alpha particle (Helium nucleus)
When a-particles interact with the nuclei of the He3, Li6, B10C12 atoms in the earth's crust, neutrons are emitted and further direct reactions occur along with appearance of charged particles that are recorded and their energies can be measured, since the energies of protons and a-particles (or other charged particles) are related to neutron energy. In such reactions, the neutrons are subjected to fission of radioactive nuclei, with the formation of unstable nuclei and the escape of charged particles. All disintegrated nuclei are unstable with respect to a-de-cay. In a-decay, a finite nucleus can be formed in ground and excited states with a higher energy than in the main group, and then the a-decay occurs from the excited state.
Heavy nuclei of terrestrial matter elements at reactions of a-decay with energy of about 6-7 MeV are accompanied by heavy charged particles. These particles also occur in inelastic collisions and they cause ionization and excitation of atoms. At high energies, nuclear interactions contribute to the loss of energy of charged particles. After each collision of charged particles with terrestrial matteratoms, they lose a small amount of energy, so a continuous process of deceleration takes place. Multiple scattering of charged particles on the nuclei of terrestrial matter leads to dispersion in the directions of their motion, but all particles propagate rectilinearly.
In fact, there are no neutron-radioactive nuclei. When radioactive sources of neutrons are discussed, the formation of neutrons at half-decay in the reactions of radioactive nuclei emitting a-particles or y-quanta is the subject matter. The residual nucleus receives kinetic energy subject to the angle of neutron emission relative to the motion of the a-particle and it interacts with the earth's crust atoms, passing the distance from the place of origin to the point where the reaction has occurred. In this case, neutrons with energies from several keV to 10-12 MeV [8] are emitted. The average energy of neutrons as they move away from the source systematically decreases.
Fig. 3. Alpha-decay of the uranium nucleus and formation of an isotope
Direct neutron radiation cannot be detected as it is an indirectly ionizing radiation. Recording is possible only on the basis of two types of neutron interaction with elastic scattering nuclei, as a result of ionization in a nuclear reaction: either a recoil nucleus in which charged particles emitted instantaneously by nuclear reaction products appears, or as radionuclide radiation. The neutrons themselves are fairly arbitrarily divided into thermal neutrons, determined by the average temperature at 20 °C, with an average energy of 0.025 eV. Resonant neutrons having a resonance interaction with the substance nuclei around 0.4-1 keV. Intermediate energies neutrons having 1 keV to hundreds of keV and, finally fast neutrons that considered havingenergy above 0.5 MeV.
Rakhimov R.Kh., Makhsudov A.U., Zufarov M.A.
Since nuclear fission in the terrestrial matter is caused even by low-energy neutrons, it occurs both in nuclear-cascade processes and electron-nuclear showers. During the formation of electron-nuclear showers, protons and neutrons of comparatively low energies are knocked out of atomic nuclei. Further, protons with relatively small energies in the earth's crust form nuclear disintegrations followed by forcing secondary protons and neutrons with lower energies out. Protons waste a considerable part of their energy also on the ionization of the earth's substance atoms, partially causing at the same time new splitting of the charged particles. Neutrons decelerate in elastic collisions and, at the end, are captured by the atom nuclei in the earth's crust, causing nuclear disintegrations.
Relatively high energies of fast neutrons in case of elastic scattering on heavy nuclei of the earth's crust atoms cause direct neutron-nuclear reactions and neutrons do not decelerate. In such reactions, protons with energies from 1 to 10 MeV appear as do neutrons with energies from 5 to 27 MeV [8]. These protons spend a considerable portion of the energy on ionization of the elements nuclei from the earth's crust and generate showers of charged particles. The neutrons, having interacted with the earth's crust matter, undergo the process of scattering. They make hundreds of collisions leading to the transfer of their energy to the atom nuclei of terrestrial matter. Due to the scattering, neutrons of low energies are accumulated with a further sharp release of energies takes place and they become thermal. Neutrons in the deceleration are likely to lose and acquire energies. And the neutrons themselves decay through 900 seconds having formed charged particles (proton, electron and neutrino).
The earth's crust still has three types of natural beta decays of unstable nuclei that accompany the production of energetic charged particles; electron radiation, positron radiation, and atomic electron capture. As a result of the first two, energetic charged particles appear. Due to the small mass of electrons, the length of their path is greater than the one of heavy particles with the same energy. In the P-decay of unstable nuclei the emitted particles can take on any energy values throughout the area of their presence. In this case, the nucleus remains in an excited statethat leads to the appearance of gamma quanta emitted by this excited nucleus. In P-decay, the final nucleus can be strongly excited and in this case it emits neutrons and protons, not y-quanta.
Beta particle
Fig. 4. Beta decay of unstable nucleus and birth of daughter nucleus
Various interactions of electromagnetic radiation with electrons, atoms and nuclei of the earth's crust occur along with neutron radiation. However, the loss of energy for heavy charged particles due to electromagnetic radiation is not significant. High energy electrons having interacted with the nuclei of the atomic cortex further emit Bremsstrahlungquanta, which in its turn form pairs. Each of the particles of this pair emits a new quantum, and so it continues until the energy of the particles falls to the minimum value of the fission threshold, creating a shower (Fig. 5a).
Fig. 5. Photon fission while interacting with the earth's crust atoms (a); a similar situation occurs with photons with the following classification (b)
In the radioactive decay chains nuclear reactions of a flying particle of the earth's core gets excited, and gamma radiation is produced. The nature of attenuation of y-radiation is always small and y-quanta can pass without any collision with large strata of terrestrial matter. Further particle motion in terrestrial matter brings to the increase of their number, creating an ava-lanchethat afterwards is going to decrease and decay. The core of the earth's crust having absorbed y-quanta will then enter the excited state. If the nucleus excitation energy is higher than the fission or the nucleus excitation threshold is higher than the proton binding energy of the proton, or a a-particle, (in nuclear fission or neutron capture, etc.), y-radiation occurs and charged particles are emitted [7]. In the result of y-rays from neutron capture no charged particles are formed, with the following formation of the unstable isotopes with radiation capture of the neutron. All stages of the y-radiation reaction that take place, as well as other reactions repeat.
1. A photon can take an electron out of an atom having passed to it all its energy.
2. Interacting photon transfers part of its energy to the electron.
3. High-energy photon in the field of the atom nucleus can form an electron-positron pairhaving passed all its energy to the electron and the positron.
4. Having interacted with the atom nucleus, a charged particle can sharply decelerate and emit Bremsstrah-lungquanta.
In the process of y-quanta deceleration upon interaction with electrons and atoms of the earth's crust, the y-quantum is absorbed, or scattered. The process of the y-quanta passage in terrestrial matter is very complex and differs from the exponential law. The number of y-rays emitted during the reaction with the atoms of the earth's crust can be more than 103 times greater than the number of neutrons. If the proton energy in collisions with light nuclei of the earth's layer can be ~10 MeV, the total energy carried away by y-quanta from the excited nucleus can be substantially higher. At high energies of the produced photons in nuclear reactions with medium and heavy atoms of terrestrial matter, photo neutrons are produced. The excitation energy can rest in the range 5-10 MeV, and the excited isotope decays with the emission of several y-quanta. When the nucleus fission occurs, in addition to the fission fragments, average 2-3 neutrons per fission and 5-7 y-rays with an average energy of about 1 MeV emit [8].
In this case, there are delayed neutrons and y-radiation, which are emitted by unstable fission fragments. The main neutrons are instantaneous (99%) and negligibly lagging. Such delayed neutrons are also emitted by the products of fission of Radon by a half-life from 0.4 to 55.6 seconds.
When y-quanta rays are absorbed and when their energy is higher than the effective fission threshold, the nuclear fission occurs leading to the following reactions: Bremsstrahlung occurs in the result of the interaction of charged particles with the nuclei of the earth's crust that changes their energies and the motion direction for the particles. Due to elastic Bremsstrahlung collisions with nuclei the scattering angles for fission fragments are larger than for protons and a particle. Fission fragments with high ionization density are always accompanied by recoil nuclei at the beginning of the run.By the end of the run; this value becomes 100 or more times greater.
In the composition of the electrons and photons, produced following the interaction with terrestrial matter, heavier particles of different energies appear. If the particle in matter moves with much less velocity than the speed of light, its ionization will be stronger. Therefore, heavy charged particles in the distance of their motion ionizemore than the atoms of terrestrial matter. Heavy particles can cause more than 2.0 • 105 ion pairs per act of shock in ionization, since shocks of a smaller magnitude are mainly caused by a particles [9]. The charged particle decelerates gradually due to the loss of energy to detach electrons from the atoms or to excite atoms.
^/ww
Gamma Rays Parent nucleus Daughter nucleus
Fig. 6. Gamma radiation of a non-stable nucleus of beta decay and formation of a daughter nucleus
When a charged particle collides with an electron of a sufficiently small impact parameter, an electron can receive such energy that it will itself cause ionization of other atoms.
The ultimate case of the electron formation of a very low energy would be the usual ionization of the atoms of matter. And when the fast electrons in the earth matter decelerate, in addition to the y-radiation, the internal state of the nucleus changes, short-wave electromagnetic radiation arises. Such electromagnetic radiations accumulatively are also considered to be earthquake harbingers and very sensitive devices are required in order to record them.
Electron
Tungsten nucleus
Fig. 7. X-ray radiation in the interaction of an electron with an unstable nucleus
Following an electronic collision with atoms of terrestrial matter, a cascade process occurs that spreads from the trajectory of the particle, thus establishing a positively charged zone. Then there a process of atomic cascade collisions takes place that is caused by the «explosion of a charge» leaving charged particles, creating an ionization chain of the plasma type. Such interactions between particles and atoms in the medium occur mainly in a very short period of time.
In its turn it reduces energy losses regardless the type of moving particles. The majority of the interactions between charged particles with the crust nuclei are inelastic leading to the excitation of the nuclei and nuclear reactions. The role of inelastic scattering and nuclear reactions is the weakening of the flux of charged particles with low energies. At high particle energies, the contributions of elastic and inelastic interactions with nuclei become the same.
The penetrating vertical intensity of low energy particles of cosmic origin in the depth of 5 m of the Earth's atmosphere decreases 18 times, while in the depth proportional to this thickness of the terrestrial ground, the low energy particles decrease only twice. It means that the velocity of the particle in the substance is 9 times higher and it travels longer than in the air space [10]. Penetrating from the place of the generated neutrons into the thickness of matter, the maximum of the spectrum shifts to the area of lower energies. At the depth of 15 g/cm2, the maximum is a few hundred kilo electron volts. And the spectra of fast neutrons at propagation depths of more than 20 g/cm2 practically remain unchanged, while the enrichment of the spectrum by high-energy neutrons is observed in the water [8].
All these cases in nature cause formation and propagation of the products resulted upon reactions with the nuclei of the Earth's atoms, and further release of radioactive gases resulting in seismic activity. The technique of nuclear physics has linked many known studies related to neutrons and charged particles, obtaining high reaction energies, photodisintegration, exotic decay methods, constituting cascade development systems for various reactions. If degassing processes are associated with seismic processes, the products from the decay of these radioactive gases and their interactions in various nuclear reactions with the atoms of the earth's soil, and the generated particles from them are the most accurate earthquakes harbingers.
Rakhimov R.Kh., Makhsudov A.U, Zufarov M.A. Conclusion
Nuclear physics obtains the information on the properties of elementary particles in the process of studying the interactions of nuclei with nuclei or the decay reactions of radioactive nuclei, measuring their products. It is not always possible to separate macro and micro causes of nuclear-radioactive and other reactions occurring in the earth's crust. The anomalies of the variations of hydro geodynamic, geophysical, geochemical, etc., parameters accompanying and reflecting precisely this process are caused by the local earthquake preparation process. Increased seismic activity of terrestrial plates squeezes, shrinks and deforms radioactive gas products. And this is the beginning of the upcoming eventaccompanied by (a-, P-, y-) decays, and a chain reaction begins. The nuclear reactions with the nuclei and other element atoms in terrestrial matter occur with neutron being emitted, then the charged particles are forced out and their fluxes change. The electric current, electromagnetic radiation and electric field, fluxes of neutron and charged particles and many other phenomena are generated and manifest themselves as precursors before the earthquake.
The main characteristics of the interactions in which neutrons and charged particles of different energies are produced practically coincide with the data obtained from the device. This conclusion does not contradict the data on the generation of gamma quanta in the above mentioned reactions that create the formation of charged particles. Anomalous variations of these precursor parameters are in good correlation within 2-3 days proceeding the moment of the earthquake, in advance and during the seismic activity.
The presented results from the device remain promising, and further studies of the problem of forecasting earthquakes are still required. Further research, monitoring of data for statistics, careful analysis and physical interpretation, presence of radioactive element sources, the existence of various plates of the earth's crust, etc. are required.
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