Neutron Bragg diffraction on a thick Ge single crystal excited by ultrasound

Raitman, E.; Gavrilov, V. N.; Mjasischev, D.; Hoser, A.; Stüβer, N.; Arulraj, A.

doi:10.1016/j.nimb.2010.08.004

Cited by 2 publications

(7 citation statements)

References 13 publications

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“…At the same time, BFS peak shifts to the profile middle. This result coincides with those obtained previously in [11] for thick Ge single crystal. But Figure 2(a), Figure 2(b) demonstrate not only a smooth intensity growth of the FFS peak and BFS peak shift to the profile centre, but also the presence of spatial intensities oscillations in the crystal inside and common broadening of intensity spatial profiles with V g increasing.…”

Section: Main Results and Discussionsupporting

confidence: 93%

“…It was shown recently [11] that for thick crystal at the same time with the main Bragg's peak increasing, acoustic wave amplitude growing, and the back-face peak become asymmetric and tend to disappearance as the peak.…”

Section: Main Results and Discussionmentioning

confidence: 99%

“…Since US effectively changes the initial dispersion surface due to the creation of new energy gap δq on the dispersion surface ( ) 0 q K Hw δ = ∆ [11] [19] and hence the new "sound" extinction length (11) also appears: τ is the extinction length for non-excited crystal. Thus, US increase the depth of neutron penetration in the crystal interior without significant attenuation of the incident beam intensity in the all Hw range.…”

Section: Main Results and Discussionmentioning

confidence: 99%

“…The ultrasound (US) influence on the neutron and X-ray Bragg diffraction has been investigated much less than in the Laue case, probably because of its complicated theoretical description, in spite of the fact that most of the monochromators installed on the neutron and X-ray spectrometers operate in Bragg's scattering geometry. Recently it was shown [11] that in a thick Ge single crystal undergoing US excitation the Bragg back-face peak becomes asymmetric and tends to disappear. Such a back-face scattering was observed for the first time and successfully described within frameworks of the modified dynamic theory of neutron scattering.…”

Section: Introductionmentioning

confidence: 99%

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Neutron Back- and Front-Face Bragg Diffraction on a Thin Si Single Crystal Excited by Ultrasound

Raitman¹,

Gavrilov²,

Mjasischev³

et al. 2015

JMP

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In this research project, we measured and analyzed the spatial distribution of neutron beam Bragg diffracted from the front-and back-faces of thin Si single crystal undergoing on ultrasound excitation. For the perfect crystal, it is shown that when the acoustic wave amplitude is increased, the front-face peak position remains unchanged and its value grows linearly. The values of ultrasound wave amplitude were determined. The back-face peak becomes asymmetric and tends to disappear. New types of Pendellösung fringes in the center of the diffraction profiles were observed at the first time. It is supposed that in the perfect crystal this effect may be due to the appearance of the new "sonic" extinction length, depending on the amplitude of the ultrasonic wave. Thus, it leads to the new interference interactions between neutron wave and ultrasonic phonons. It is established that within the framework of the dynamical theory of the neutron scattering, some asymptotic models valid for the case of Laue geometry as well as Kato's quasi-classical approximation can be applied in the case of Bragg geometry also. Good agreement between experimental data and the theory has been obtained.

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Section: Main Results and Discussionsupporting

confidence: 93%

Section: Main Results and Discussionmentioning

confidence: 99%

Section: Main Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Neutron Back- and Front-Face Bragg Diffraction on a Thin Si Single Crystal Excited by Ultrasound

Raitman¹,

Gavrilov²,

Mjasischev³

et al. 2015

JMP

Self Cite

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show abstract

“…Recently, the intensities of neutron Bragg diffraction from the front and back faces of a thick, perfect Ge single crystal undergoing ultrasound excitation have been measured and calculated theoretically (Raitman et al, 2010). It was shown that, simultaneously with the AW amplitude increasing, the main Bragg peaks grow and the back-face peaks become asymmetric and tend to disappear.…”

Section: Introductionmentioning

confidence: 99%

Propagation of neutron spherical waves through a thick, vibrating Ge single crystal

et al. 2013

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The results of experimental and theoretical studies into the influence of ultrasound on the propagation of neutron waves in a thick Ge crystal are presented. The neutron intensity profiles were measured for the case of Laue diffraction inside the Borrmann fan. At low amplitudes of ultrasonic waves interference effects (diffraction intensity beatings) were observed. The observations were possible because of the uniform acoustic-field distribution through the whole bulk of the crystal. As distinct from the classical Shull experiments, wide analysing slits or position-sensitive detectors were used. To explain the results obtained, a modified theory for the spatial distribution of neutron diffraction intensities in the presence of acoustic excitation of the crystal is proposed. A good agreement between experiment and theory is obtained. At high amplitudes of ultrasonic waves the transition to kinematic scattering was not observed, despite the large strains in the crystalline lattice created by ultrasound. This could be connected with the formation of a superlattice having a standing wave period. A strong rise in the diffraction intensity and a sharp constriction of the neutron beam at the centre of the Borrmann fan were observed. This new effect could be used for the creation of ultrasound-controlled monochromators.

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Neutron Bragg diffraction on a thick Ge single crystal excited by ultrasound

Cited by 2 publications

References 13 publications

Neutron Back- and Front-Face Bragg Diffraction on a Thin Si Single Crystal Excited by Ultrasound

Neutron Back- and Front-Face Bragg Diffraction on a Thin Si Single Crystal Excited by Ultrasound

Propagation of neutron spherical waves through a thick, vibrating Ge single crystal

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