RADIATION ACOUSTICS

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RADIATION ACOUSTICS

L. Lyamshev

To cite this version:

L. Lyamshev. RADIATION ACOUSTICS. Journal de Physique Colloques, 1990, 51 (C2), pp.C2-1- C2-7. �10.1051/jphyscol:1990201�. �jpa-00230369�

COLLOQUE DE PHYSIQUE

Colloque C2, supplement au n°2, Tome 51, Fevrier 1990 C2-1 ler Congres Frangals d'Acoustique 1990

RftDIftTION ACOUSTICS

L . M . LYAMSHEV

W.N. Andreev Acoustical Institute of the Academy of Sciences of the USSR, Shvernik Str.4, 117036, Moscow B-36, U.S.S.R.

Résume - Acoustique de radiation est une nouvelle branche de l'acoustique, l'étude des effets de l'acoustique de radiation est a sa base. Ces effets sont le résultat de l'interaction du rayonnement pénétrante avec une matière. On examine l'excitation du son par le rayonnement pénétrant module ou impulsif (faisceaux de électrons, des protones, des ions etc., 7-rayonnement) et par des particules fondamentales de haute énergétique. On discute les applications possibles des effets de l'acoustique de radiation en contrôle non destructif et pour la détection des particules fondamentales de haute énergétique.

Abstract - Radiation acoustics is a new branch of acoustics. Its' fundamentals are lying in the research of acoustical effects due to the interaction of a radiation with matter. The sound excitation in liquids and solids by modulated or pulsed particle beams (electron, proton, ion beams, 7-radiation and single high-energy elementary particles) and some practical applications are discussed.

1 - WHAT IS A RADIATION ACOUSTICS?

Radiation acoustics is a new branch of acoustics, developing on the boundary of acoustics, nuclear physics, elementary particles and high-energy physics.

Its' fundamentals are lying in the research of acoustical effects due to the interaction of penetrating radiation, e.g. electron, proton, ion beams, X-rays and 7-radiation, beams of neutral particles and single high-energy particles with matter. The research of sound excitation by laser radiation (or by the photon beams) can be classified as radiation acoustics too, though this is an independent branch already.

The study of radiation-acoustical effects leads to the new opportunities in the penetrating radiation research (acoustical detection, radiation-acoustical dosimetry), study of the physical parameters of matter (radiation-acoustical microscopy and others), in a solution of some applied problems of nondestructive testing (radiation-acoustical testing of nonhomogenous media), and also for the targeted radiation-acoustical influence on physical and chemical structure of the matter.

The research of radiation acoustical effects were stimulated by the progress of the elementary particles and high energy physics. Physics of elementary particles made a great progress in the recent decades. With the help of powerful accelerators the particles of giant energies of tens and hundreds GeV were obtained. There was discovered a huge number of elementary particles that are liable to sometimes surprising interactions and mutual transformations.

The accelerators, destined at first for fundamental research in the field of particle physics, are wider and wider applied now in medicine, biology, technology, material testing and in radiation-acoustical research and technology.In the high-energy physics the units of measurement are: 1 TeV = 103 GeV = 106 MeV = 109 KeV = 1 01 2 eV = 1.6 erg. The number of the particles in the beam of modern accelerators is 10 - 10

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1990201

C2-2 COLLOQUE DE PHYSIQUE

2

-

FROM THE OPTOAaOUSTICAL EPFECT M

THE

RADIATION ACOUSTICS.

The fundamentals of the radiation acoustics are linked to the discovem of the optoacoustical effect - the sound excitation in a closed gas-filled chamber due to the passage through it of a modulated light beam (modulated photon beam; A. Bell, 1880). In his paper A. Bell discussed the possibility of construction of a radiophone - a gadget for producing sound by an arbitrary type of radiation /I /

.

The first research on radiation acoustics was performed in 1950 - 1960. Y.

Buckingham (1953), M. I. Kaganov, I. M. Lifshits and L. V. Tanatarov (1956) showed that due to the electron, uniformely moving with supersonic speed in a solid, the Cherenkov radiation of sound (phonons) is excited /2,3/.

G. A. Askari jan (1 957) considered the radiation of ultra- and hypersound waves by charged particles in a dense media due to the local superheating and microcavities birth on the particle tracks /4/. R. White (1963) studied the sound generation by a low energy electron beam in a solid, and B. Beron and R.

Hofstadter (1 969 ) observed the mechanical oscillations in ceramic piezotransducers due to the passage through them of relativistic electrons /5,6/.

In the USSR multiple research of sound excitation in condensed media by electron and proton beams and elementary particles were perfomed by V. D.

Volovik, A. I. Kalinichenko, V. T. murik and others in 1970-ies, and by L.

I. Lyamshev and B. I. Chelnokov in 1980-ies /7,8/.

3

-

THE PHYSICAL N B T m OF SOUND GENERBTION BY PINEFRATIMG RADIATION

!The mechanisms of sound generation by penetrating radiation are connected usually with the physical processes leading to the conversion of radiation energy to the acoustical energy. These mechanisms depend on the type of radiation, target material and energy discharge conditions. The mechanisms of sound generation are multiple and are not equivalent in their efficiency /9/.

Themradiational mechanism. Heat discharge is one of the most universal physical phenomena due to the absorbtion of penetrating radiation. Thermal energy can partly transform to the acoustical energy in different ways. If the density of energy discharge is moderate and there 1s no phase transitions in the medium the main contribution to the process of sound generation is due to the thermal expansion of the medium. This is the so called thermoradiational or thermoelastic mechanism of sound generation. The distinctive feature of this mechanism is that basic characteristics of acoustical fields in this case can be described in the setting of linear model. Thanks to that a very effective theory of themoradiational sound generation was developed /lo/.

The theory of thermoradiational sound generation is in good consent with the experimental results. In the setting of this theory the results for the early experiments could be explained. It follows out of the theory, for instance, that the sound pressure amplitude p(r) in a liquid due to the action of harmonically modulated penetrating radiation beam (ralativistic electron beam, 7-radiation, X-rays, laser radiation etc.) is proportional to the power of penetrating radiation 811. The acoustical field of radiation acoustical source

in a liquid is also a function of observation angle.

o m a W exp(lkr) pk COB(@) k a' p ( r ) = -

T ^r

^CC2

⁺

^{lc2 cos2 8 exp}

^[

^{7 sin2 0}

⁾

W = z a2 I,

I

- intensity of radiation beam, - beam radius, w - sound frequency,

m

- modulation coefficient, k = u/C; Cp, CI, C, p, - specific heat capacity, thermal expansion coefficient, sound velocity, radiation absorbtion coefficient-of a liquid, 8 - observation angle, (the angle between the radiation beam incidence direction and the obsevation point direction). The

theoretical results are confirmed experimentally (see Pig. 1

,

² )

.

It foll'ows out of the theory for example that due to the absobtion of high-speed charged particles (electrons or positrons) in a metal, in a case when the duration of particle pulse is much less than characteristic acoustic

time (this time is defined as a ratio of the beam diameter or the radiation length of the particle to the longitudinal sound wave' velocity) and the thickness of the target much more than the particles radiation length (the

Fig.1 - Sound pressure amplitude on the axis of laser-acoustical source in water versus the power of laser radiation /11/.

Pig.2 - Sound pressure versus the observation angle in a case of laser excitation of sound in water /11/.

Phe solid line - theory,

o

- experiment.

radiation unit of length), the amplitude of acoustical signal is proportional to the energy of the particles in a beam. The acoustical signal due to the action of penetrating radiation short pulse on a liquid is for determined by the expression

a E p ( r , t ) =

-

8 a C x 2 r

p s

x

[

^exp

^(-7)

^{~ r i c}

[ ^-

2

I3 = r a2

I$,

6 - penetrating radiation pulse duration, _S =

W $ ,

a Sin 8 Cos 8 2 O0

%a= c %P=

.

^{Brfc (s) = Jexp (-t2) dt,}

7

= (t -

r/c)/%

0

The efficiency of penetrating radiation energy into sound is proportional to Cr- the intensity of radiation. It means that with the increase of the beam diameter and constant particles' energy the amplitude of the acoustical signal would change inversly proportional to the square of beam's diameter.These derivations from the theory are in good consent with the experimental results represented for instance in one of the early papers /12/ (see Fig.3-5). The experiments were performed on the linear accelerator of the Physico-Technical Institute of the Ukrainian Academy of Sciences (USSR). In the experiments on the aluminium plates the electron beam with diameter of 1.0 - 4.0 cm and with the beam current pulse duration of s and energy of 5 - 40 MeV was used.

Two cases were investigated: when the plate thickness is much less or much more than the radiational unit of length.

It follows out of the theory that the radiation-acoustical source signal amplitude dependence, measured in a near wave field follows the curve of alteration of absorbtion of particles in a substance (see Fig.6, 7). This fact is confirmed experimentally.

The scene of sound generation is much more complicated under the high densities of energy discharge of penetrating radiation in a medium. The processes in this case are of nonlinear nature. Under such conditions the effects stipulated by the heated volume expansion velocity increase

C2-4 COLLOQUE DE PHYSIQUE

Fig. 4.

A 40

20

0

Fig:3

-

The acoustical signal amplitude versus the relativistic electron beam radius (a case of a thin aluminum plate).

-

au.

6

-0-

-

- 0 4

w , * ,

Fig.4 - The acoustia signal amplitude versus the energg of electrons (a case of a thick aluminum plate).

I 2 3 4 d,cm

A

a . ~ . Fig.3.

4

I

Fig.5 - The acoustical signal amplitude versus the energy of protons in water /8/.

Fig.6 - The acoustic signal amplitude versus the hydrophone position along the proton beam axis in water /8/.

Fig.7 - The ionization by a-particles versus their remainder run length /13/.

(hydrodinamic nonlinearity) and also by the, alteration of thermodinamic parameters of the substance during the process of action of penetrating radiation (thermal nonlinearity) turm to be essential. In a case of further growth of thermal energy discharge density more complex processes of sound generation connected with the phase transitions develop. These physical processes could be observed in cases of so called '*bubble mechanism" of sound generation by penetrating radiation and shock wave formation mechanism.

'Bubble mechanism" of sound generation. The excitation of sound in a liquid by ionizing radiation is possible due to the formation, oscillations and explosion of microbubbles on the particle tracks /4.14/. Incidentally acoustical signal would simulate the thermal (thermoradiational) mechanism of sound generation signal but much more powerful. Under normal experimental

conditions (i.e. atmospheric pressure, room temperature and stable liquids) the bubble mechanism of sound generation would apparentlz show itself only in a case when the penetrating radiation consists out of heavy particles, e.g.

nuclear fission fragments. The theory of bubble mechanism sound generation 1s far from completion.

Shock wave ^formation mechanism. In some cases the passage of penetrating radiation through substance, e.g. the passage of the fission fragments through a liquid, could be accompanied by the formation of shock waves along all of the fission fragments track /15/. -om the other side the 6-electrons originating from the passage of ionizing particles through liquid, form the overheated microregions (thermal peaks) in it. Explosive expansion of them also generates a shock wave /16/. The shock wave formation is an essentially nonlinear phenomenon and the theory of similar processes is not completed yet.

It's interesting to note that due to the entry of a single high-energy particle in the atmosphere an extended air shower consisting mainly out of electrons could form. When a cosmic high-energy particle generates a shower of secondary particles in a water, the density of radiant centers have to be higher than in the atmosphere. The calculations show that in water, e.g. in mountain lakes, it is apparently possibtg now to detect the extended air shower with the particles' energy of 10 - I 017 eV.

The dlnamic me~harzl~m. The impulse transfer from the quanta of penetrating radiation to atoms of a condensed medium takes place besides the thermal discharge in the medium. This effect accompanied by sound excitation is galled the dinamic mechanism of sound generation. Its' efficiency however is 10 less than that of the thermoradiational mechanism.

Cherenkov IUechaniSm of sound generation. A particle moving with the velocity exceeding the velocity of waves' propagation in a medium radiates such waves (Cherenkov radiation). A neutral particle moving for instance in a metal radiates longitudinal sound waves, spectral intensity of which is proportional to the third degree of sound frequency. A charged particle generates longitudinal and transversal waves in a metal. The Cherenkov mechanism gives a perceptible contribution to the sound generation in a hypersound range.

Other mechanism6 of sound generation. For instance the microstriction in the ion field due to the medium ionization by penetrating (ionizing) radiation occurs that leads to the microstrictiondl compression. It can play a noticeable role in a case of thermoradiational generation of sound by a charged particle when the thermal expansion coefficient of the medium is small. Specifically it was discovered experimentally that the sound pulse caused by a beam of charged particles in water turns to zero and changes polarity not under

T

= 4*C (the temperature when the thermal expansion coefficient of water turns to zero) but under T =5 . ~ O C . Apparently in these conditions the compensation of thermal expansion by strictional compression occurs /10,17/ (see Fig.8, 9).

2

50

.

y o . ^{a !} i

' 2 .

²

0 .

Fig.8 - The temperature dependence of the amplitude of the acoustical signal for the proton beam in water.

C2-6 COLLOQUE DE PHYSIQUE

Fig.9 - The temperature dependence of the amplitude of the acoustical signal for the electron beam in water.

The solid line on Pig.8, 9 is proportional to the temperature dependence of the thermal expansion coefficient of water.

4 -

THE

RADIBTION ACOUSTICS APPLICATIONS.

I. RadtattmZ acousto-thermal mtcroscopy.

The electron-acoustic (W) and electron-thermal ( E T M ) microscopy are used for obtaining of information on the structural micrononhomogeneties in microelectronic and integrated optics circuits. They are based on the detection of acoustical oscillations or thermal waves in a sample under investigation caused by the action of the sound frequency modulated electron beam. In these methods the focused beam moves along the surface of a sample.

The signal from an acoustical or thermal wave receiver goes to the monitor sinchronously with beam's motion. The main advantage of E U and EIPM is a possibility to "see* under a sample surf ace /I 8,19/.

It was shown by L. M. Lyamshev and B. I. Chelnokov (1 983) that E2M and BdlYI resources could be extended by the employment of other types of penetrating radiation (e.g. ion or proton beams, X-rays, etc.).The resolution of such a microscope is determined mainly by the dimensions of the focused beam that are characterized by the de Broglie wavelength /20/. The construction in Japan of the first ion-acoustical microscope was reported in 1986 /21/.

2. AcousttcaZ detection o$ ~ - h t g h ptZcZes. - ~ ~

Despite the construction of the new generation accelerators the investigation of high-energy particles generated by the Iqnatural accelerators1' in the interior of the galaxieg is actual still. The observations and calculations show that the energy of these "cosmic" particles is much higher than that co~ld be12btained on the accelerators even in the far future (something about 10 - 10 TeV). The further progress in the super-high-energy particle physics is impossible without the employment of a new detection technique. The elaboration of a radiation-acoustical technique seems actual.

In 1960 the idea of application of neutrino for the investigation of astronomical objects was formulated by academician M. A. Markov. It was he who suggested the neutrino deep underwater detection method

,

which was later put in the basis of the tremendous project of underwater super-high-energy neutrino and muon detector /22/. In this project, called DUMAND (Deep Underwater Muon Agd Yeutrino Detection), the construction of a detector with dimensions of 10 m on the 5 km depth in the ocean is planned. In 1976 G. A.

dskarijan and B. A. Dolgoshein (USSR) and T. Bowen independently proposed to employ in the DUMAND project the idea of acoustical neutrino detection and made primary calculations (on the base of thermoradiational mechanism) that showed its' feasibility /23,24/.

3. 17Ee radiation-acwttcaZ mechrrpzism w t m m & - uo$ z noise germatton in the calm ocean.

Apparently it was V. I. Il'ichev who for the first time formulated the idea of a possible contribution of the cosmic radiation into the ocean noise field.

The calculations of characteristics of the sources of noise observed in the ocean, of energetic parameters of cosmic radiation and possible transduction mechanisms of cosmic radiation energy to acoustical energy, the measurements of noise in a calm ocean and especially in high-frequency region showed that the hypothesis of the "cosmicfp nature of noise in a calm ocean is apparently real (L. M. Lyamshev, B. I. Chelnokov, A. V. Furduev, 1987) /25/.

4. Neutrino geoacoustics.

In 1983 A. Rujula, S. Glashow, R. Wilson and G. Charpak (USA) suggested the application for geological research of thermoacoustical signal generated by a neutrino beam in a rock /26/. The neutrino beam formed by accelerator propagated in a preset direction passes a sufficient distance Earth. The receivers placed along its' path on Earth surface detect acoustic signals generated by the beam that are carrying the information about rock characteristics and structure along their path. These authors made calculations of a proton ring accelerator parameters for the proton beam energy of 10 TeV, which can be considered as an accelerator prototype for

neutrino-acoustical sounding of Earth. This accelerator called by them HGeotronlQ or l*Tevatmnl* can be characterized by the fact that its' radius have to be about 10 lan and the cost - several billions dollars.

5.

Heutrino-acmt €cat

timopcqYqj

01

^the ocean.

Now an idea discussed and applied in praatice of the acoustical tomography of the ocean, when the ocean or its* region is sounded by acoustical signal under different angles and from different points. Then with the help of computers the sections are built

,

that characterize the structures (vortexes) in the ocean and their changeability. The naturdL developement of this idea can be the neutrino-acoustical tomography of the Earth and specifically the neutrino-acoustical tomography of the ocean. The future application of neutrino beams as sound sources may open new perspectives in the ocean research.

RxmmCES

/I / Bell, A.G., Phylos. Mag. and J. Soi. 1 I (1881 ) 51 0.

/2/ Buckingham, M.J., Proc. Roy. Soc. 66 (1953) 601.

/3/ Kaganov, M.I., Lifshits, I.M. and Tanatarov, L.I., Zhurn. Experim. i Teor.

Piz. (USSR) 37 (1956) 232

/4/ Bskarijan, G.A., Atomnaga Energiya (USSR) 3 (1957) 152 /5/ White, R.M., Journ. of Appl. Phys. 34 (1963) 2123

/6/ Beron. B.L. and Hofstadter. R.. Phvs. Rev. Lett. 23 (19691 184

/7/ ~aliubovskii. I. I., Rdlinichehko, A. I. and ~ a z u r i i t . B T "The Introduction to Radiation Acoustics1*. Rharkov. Rharkov State University

(USSR) (1986) 167 p.

-

/8/ "Radiation AcousticsN,ed. by L.M. Lyamshev, Moscow, Nauka (USSR) (1987) 133 P.

/9/ Lyamshev, L.M. and Chelnokov, B.I.

,

in: "Radiation Acoustios"

,

^Moscow,

Nauka (USSR) (7981) 8

/I O/ mamshev, L.M. and Chelnokov

,

B. I.

,

in: "Radiation Acousticsu, Moscow, Nauka (USSR) (1987 58

/I I / Muir, T.G., Culbertson, C.R., CQnch, J.R., JASA 59 (1976) 735

/12/ Borshkovskii, I.A., Volovok, V.D. et al.,Zhurn. Experim. i Teor. Fie.

(USSR) 63 (1972) 1337

/13/ "Experimental Nuclear Phgsics", ed. by E. Segre, N.Y., Undon 1 (1 953) /14/ Volovik, V.D., Petrenko, V.V. and Popov, G.F., Pis'ma v Zhurn. Tehn. Fiz.

(USSR) 3 (1977 459

/15/ Gol'danskii, V.I., Lantsburg, B.Ya. and Yampol'skii, P.A., Pis'ma v Zhurn. Experim. i Teor. Pi%. !USSR) 21 (1976) 365

/16/ Anoshin, I.A., Zhurn. Tehn. FLZ. (USSR) 47 (1 977) 2186 /17/ Hunter, S.D., Jones, S.D. et al., JASA 69 (1981) 1567

/18/ Brmndis, B.B. and Rosencwaig, A., Appl. Phys. Lett. 37 (1980) 98 /79/ Cargill

,

G.S., Nature 286 (1980) 691

/20/ Lyamshev, L.M. and Chelnokov. B . I . . Bkust. Zhurn. (USSR) 30 (1984) 564 /21/ Tateno, H., Ono, I. et al., Jap. Journ. of Appl. Phgs. 25 Suppl. 25-1

(1qa6)

.----.

I =

/22/ Markov, M.A., Proc. 10 Interm. Conf. on High Bnergy Phys., Rochester (1960) 579

/23/ Bskarijan, G.A. and Dolgoshein, B.A., Preprint FIAN SSSR No. 160 _(USSR) (1976) 22 P.

/24/ Bowen, T., Proc, 1976 DUMAND, Summer Workshop, Honolulu, Sept. 6-19, Batavia: PNdL (1 977) 523

/25/ Lyamshev, L.M. et 61, in: "Radiation Acoustiasl'

,

Moscow, Nauka (USSR) (1987) 46

/26/ Rujula, A., Glashow, S., Wilson, R. and Charpak, G., Prepr. HWP-83/A019