Data reduction and analysis for the graphite crystal X-ray spectrometer and polarimeter experiment flown aboard OSO-8 spacecraft

Science.gov (United States)

Novick, R.

1980-01-01

The documentation and software programs developed for the reception, initial processing (quickbook), and production analysis of data obtained by solar X-ray spectroscopy, stellar spectroscopy, and X-ray polarimetry experiments on OSO-8 are listed. The effectiveness and sensitivity of the Bragg crystal scattering instruments used are assessed. The polarization data polarimetric data obtained shows that some X-ray sources are polarized and that a larger polarimeter of this type is required to perform the measurements necessary to fully understand the physics of X-ray sources. The scanning Bragg crystal spectrometer was ideally suited for studying rapidly changing solar conditions. Observations of the Crab Nebula and pulsar, Cyg X-1, Cyg X-2, Cyg X-3, Sco X-1, Cen X-3, and Her X-1 are discussed as well as of 4U1656-53 and 4U1820-30. Evidence was obtained for iron line emission from Cyg X-3.

Time-dependent Bragg diffraction and short-pulse reflection by one-dimensional photonic crystals

International Nuclear Information System (INIS)

André, Jean-Michel; Jonnard, Philippe

2015-01-01

The time-dependence of the Bragg diffraction by one-dimensional photonic crystals and its influence on the short pulse reflection are studied in the framework of the coupled-wave theory. The indicial response of the photonic crystal is calculated and it appears that it presents a time-delay effect with a transient time conditioned by the extinction length. A numerical simulation is presented for a Bragg mirror in the x-ray domain and a pulse envelope modelled by a sine-squared shape. The potential consequences of the time-delay effect in time-dependent optics of short-pulses are emphasized. (paper)

A large-acceptance Bragg curve spectrometer with a longitudinal electric field and a segmented anode

International Nuclear Information System (INIS)

Farrar, K.A.; Hasan, A.T.; Prosser, F.W.; Sanders, S.J.; Henderson, D.J.

1994-01-01

A large-acceptance Bragg curve spectrometer with a longitudinal electron collection field and a segmented anode has been constructed and tested. The effects on the charge resolution of the entrance angle and entrance position of the incident particle have been studied. Simulations have been done in order to isolate the contribution to the overall detector performance of the signal-shaping electronics from that of the intrinsic design of the detector. ((orig.))

Broadband time-resolved elliptical crystal spectrometer for X-ray spectroscopic measurements in laser-produced plasmas

International Nuclear Information System (INIS)

Wang Rui-Rong; Jia Guo; Fang Zhi-Heng; Wang Wei; Meng Xiang-Fu; Xie Zhi-Yong; Zhang Fan

2014-01-01

The X-ray spectrometer used in high-energy-density plasma experiments generally requires both broad X-ray energy coverage and high temporal, spatial, and spectral resolutions for overcoming the difficulties imposed by the X-ray background, debris, and mechanical shocks. By using an elliptical crystal together with a streak camera, we resolve this issue at the SG-II laser facility. The carefully designed elliptical crystal has a broad spectral coverage with high resolution, strong rejection of the diffuse and/or fluorescent background radiation, and negligible source broadening for extended sources. The spectra that are Bragg reflected (23° < θ < 38°) from the crystal are focused onto a streak camera slit 18 mm long and about 80 μm wide, to obtain a time-resolved spectrum. With experimental measurements, we demonstrate that the quartz(1011) elliptical analyzer at the SG-II laser facility has a single-shot spectral range of (4.64–6.45) keV, a typical spectral resolution of E/ΔE = 560, and an enhanced focusing power in the spectral dimension. For titanium (Ti) data, the lines of interest show a distribution as a function of time and the temporal variations of the He-α and Li-like Ti satellite lines and their spatial profiles show intensity peak red shifts. The spectrometer sensitivity is illustrated with a temporal resolution of better than 25 ps, which satisfies the near-term requirements of high-energy-density physics experiments. (atomic and molecular physics)

A Novel Spectrometer for Measuring Laser-Produced Plasma X-Ray in Inertial Confinement Fusion

Directory of Open Access Journals (Sweden)

Zhu Gang

2012-01-01

Full Text Available In the experimental investigations of inertial confinement fusion, the laser-produced high-temperature plasma contains very abundant information, such as the electron temperature and density, ionization. In order to diagnose laser-plasma distribution in space and evolution in time, an elliptical curved crystal spectrometer has been developed and applied to diagnose X-ray of laser-produced plasma in 0.2~2.46 nm region. According to the theory of Bragg diffraction, four kinds of crystal including LiF, PET, MiCa, and KAP were chosen as dispersive elements. The distance of crystal lattice varies from 0.4 to 2.6 nm. Bragg angle is in the range of 30°~67.5°, and the spectral detection angle is in 55.4°~134°. The curved crystal spectrometer mainly consists of elliptical curved crystal analyzer, vacuum configuration, aligning device, spectral detectors and three-dimensional microadjustment devices. The spectrographic experiment was carried out on the XG-2 laser facility. Emission spectrum of Al plasmas, Ti plasma, and Au plasmas have been successfully recorded by using X-ray CCD camera. It is demonstrated experimentally that the measured wavelength is accorded with the theoretical value.

HYSPEC: A crystal time-of-flight hybrid spectrometer for the spallation neutron source with polarization capabilities

International Nuclear Information System (INIS)

Shapiro, S.M.; Zaliznyak, I.A.; Passell, L.; Ghosh, V.J.; Leonhardt, W.J.; Hagen, M.E.

2006-01-01

The hybrid spectrometer (HYSPEC) is a unique direct geometry inelastic scattering instrument under construction at the spallation neutron source (SNS). It combines the intensity enhancement features of focusing Bragg crystals with time-of-flight energy analysis. It will be located at beam-line 14B, which views a coupled liquid hydrogen moderator. A neutron beam from the moderator will travel along a curved guide, through a Fermi chopper and will then be focused onto a sample in an external building, 39 m from the source. In this configuration the intensity at the sample position is more than an order of magnitude larger than for other planned inelastic instrument. A movable detector bank 4.5 m from the sample will cover an angular range of 60 deg. in the horizontal plane and 15 deg. in the vertical direction. An important feature of HYSPEC is the ability to do neutron polarization analysis experiments. A Heusler crystal, which polarizes the neutron beam, can be used as the focusing crystal and a series of bender analyzers will analyze the polarization of the scattered beam

Simulation of path delay multiplexing-based Fourier transform spectrometer for fiber Bragg grating interrogation.

Science.gov (United States)

Chelliah, Pandian; Sahoo, Trilochan; Singh, Sheela; Sujatha, Annie

2015-10-20

A Fourier transform spectrometer (FTS) used for interrogating a fiber Bragg grating (FBG) consists of a scanning-type interferometer. The FTS has a broad wavelength range of operation and good multiplexing capability. However, it has poor wavelength resolution and interrogation speed. We propose a modification to the FTS using path delay multiplexing to improve the same. Using this method, spatial resolution and interrogation time can be improved by n times by using n path delays. In this paper, simulation results for n=2, 5 are shown.

A magnetically tunable non-Bragg defect mode in a corrugated waveguide filled with liquid crystals

Science.gov (United States)

Zhang, Lu; Fan, Ya-Xian; Liu, Huan; Han, Xu; Lu, Wen-Qiang; Tao, Zhi-Yong

2018-04-01

A magnetically tunable, non-Bragg defect mode (NBDM) was created in the terahertz frequency range by inserting a defect in the middle of a periodically corrugated waveguide filled with liquid crystals (LCs). In the periodic waveguide, non-Bragg gaps beyond the Bragg ones, which appear in the transmission spectra, are created by different transverse mode resonances. The transmission spectra of the waveguide containing a defect showed that a defect mode was present inside the non-Bragg gap. The NBDM has quite different features compared to the Bragg defect mode, which includes more complex, high-order guided wave modes. In our study, we filled the corrugated waveguide with LCs to realize the tunability of the NBDM. The simulated results showed that the NBDM in a corrugated waveguide filled with LCs can be used in filters, sensors, switches, and other terahertz integrated devices.

Perturbative modeling of Bragg-grating-based biosensors in photonic-crystal fibers

DEFF Research Database (Denmark)

Burani, Nicola; Lægsgaard, Jesper

2005-01-01

We present a modeling study carried out to support the design of a novel, to our knowledge, kind of photonic-crystal fiber (PCF)-based sensor. This device, based on a PCF Bragg grating, detects the presence of selected single-stranded DNA molecules, hybridized to a biofilm in the air holes of the...

A multi-analyzer crystal spectrometer (MAX) for pulsed neutron sources

International Nuclear Information System (INIS)

Tajima, K.; Ishikawa, Y.; Kanai, K.; Windsor, C.G.; Tomiyoshi, S.

1982-03-01

The paper describes the principle and initial performance of a multi-analyzer crystal spectrometer (MAX) recently installed at the KENS spallation neutron source at Tsukuba. The spectrometer is able to make time of flight scans along a desired direction in reciprocal space, covering a wide range of the energy transfers corresponding to the fifteen analyzer crystals. The constant Q or constant E modes of operation can be performed. The spectrometer is particularly suited for studying collective excitations such as phonons and magnons to high energy transfers using single crystal samples. (author)

TFTR horizontal high-resolution Bragg x-ray spectrometer

International Nuclear Information System (INIS)

Hill, K.W.; Bitter, M.; Tavernier, M.

1984-11-01

A bent quartz crystal spectrometer of the Johann type with a spectral resolution of lambda/Δlambda = 10,000 to 25,000 is used on TFTR to determine central plasma parameters from the spectra of heliumlike and lithiumlike metal impurity ions (Ti, Cr, Fe, and Ni). The spectra are observed along a central radial chord and are recorded by a position sensitive multiwire proportional counter with a spatial resolution of 250. Standard delay-line time-difference readout is employed. The data are histogrammed and stored in 64k of memory providing 128 time groups of 512-channel spectra. The central ion temperature and the toroidal plasma rotation are inferred from the Doppler broadening and Doppler shift of the K lines. The central electron temperature, the distribution of ionization states, and dielectronic recombination rates are obtained from satellite-to-resonance line ratios. The performance of the spectrometer is demonstrated by measurements of the Ti XXI K radiation

Synchrotron Bragg diffraction imaging characterization of synthetic diamond crystals for optical and electronic power device applications.

Science.gov (United States)

Tran Thi, Thu Nhi; Morse, J; Caliste, D; Fernandez, B; Eon, D; Härtwig, J; Barbay, C; Mer-Calfati, C; Tranchant, N; Arnault, J C; Lafford, T A; Baruchel, J

2017-04-01

Bragg diffraction imaging enables the quality of synthetic single-crystal diamond substrates and their overgrown, mostly doped, diamond layers to be characterized. This is very important for improving diamond-based devices produced for X-ray optics and power electronics applications. The usual first step for this characterization is white-beam X-ray diffraction topography, which is a simple and fast method to identify the extended defects (dislocations, growth sectors, boundaries, stacking faults, overall curvature etc. ) within the crystal. This allows easy and quick comparison of the crystal quality of diamond plates available from various commercial suppliers. When needed, rocking curve imaging (RCI) is also employed, which is the quantitative counterpart of monochromatic Bragg diffraction imaging. RCI enables the local determination of both the effective misorientation, which results from lattice parameter variation and the local lattice tilt, and the local Bragg position. Maps derived from these parameters are used to measure the magnitude of the distortions associated with polishing damage and the depth of this damage within the volume of the crystal. For overgrown layers, these maps also reveal the distortion induced by the incorporation of impurities such as boron, or the lattice parameter variations associated with the presence of growth-incorporated nitrogen. These techniques are described, and their capabilities for studying the quality of diamond substrates and overgrown layers, and the surface damage caused by mechanical polishing, are illustrated by examples.

Imaging spectrometer using a liquid crystal tunable filter

Science.gov (United States)

Chrien, Thomas G.; Chovit, Christopher; Miller, Peter J.

1993-09-01

A demonstration imaging spectrometer using a liquid crystal tunable filter (LCTF) was built and tested on a hot air balloon platform. The LCTF is a tunable polarization interference or Lyot filter. The LCTF enables a small, light weight, low power, band sequential imaging spectrometer design. An overview of the prototype system is given along with a description of balloon experiment results. System model performance predictions are given for a future LCTF based imaging spectrometer design. System design considerations of LCTF imaging spectrometers are discussed.

Bragg crystal spectroscopy on the OSO 8 satellite

Science.gov (United States)

Long, K. S.; Chanan, G. A.; Helfand, D. J.; Ku, W. H.-M.; Novick, R.

1979-01-01

Results are reported for high-resolution OSO 8 Bragg-crystal spectroscopy of a variety of cosmic X-ray sources in the energy range from 2 to 10 keV. A continuous spectrum of Sco X-1 is examined, and results of a search for narrow line emission due to iron near 6.7 keV are presented for 32 galactic X-ray sources, including Sco X-1, Cyg X-3, and Cen X-3. It is noted that the strongest evidence for iron line emission has been obtained for Cyg X-3 and that evidence for an iron line feature has also been found in the spectrum of Cen X-3.

High-resolution compact Johann crystal spectrometer with the Livermore electron beam ion trap

International Nuclear Information System (INIS)

Robbins, D.L.; Chen, H.; Beiersdorfer, P.; Faenov, A.Ya.; Pikuz, T.A.; May, M.J.; Dunn, J.; Smith, A.J.

2004-01-01

A compact high-resolution (λ/Δλ≅10 000) spherically bent crystal spectrometer in the Johann geometry was recently installed and tested on the Lawrence Livermore National Laboratory SuperEBIT electron beam ion trap. The curvature of the mica (002) crystal grating allows for higher collection efficiency compared to the flat and cylindrically bent crystal spectrometers commonly used on the Livermore electron beam ion traps. The spectrometer's Johann configuration enables orientation of its dispersion plane to be parallel to the electron beam propagation. Used in concert with a crystal spectrometer, whose dispersion plane is perpendicular to the electron beam propagation, the polarization of x-ray emission lines can be measured

Field analysis of TE and TM modes in photonic crystal Bragg fibers by transmission matrix method

Directory of Open Access Journals (Sweden)

M Hosseini Farzad

2010-03-01

Full Text Available In this article, we considered the field analysis in photonic crystal Bragg fibers. We apply the method of transmission matrix to calculater the dispersion curves, the longitudinal wave number over wave number versus incident wavelength, and the field distributions of TE and TM modes in the Bragg fiber. Our analysis shows that the field of guided modes is confined in the core and can exist only in particular wavelength bands corresponding to the band-gap of the periodic structure of the clad. From another point of view, light confinement is due to Bragg reflection from high-and low-refractive index layers of the clad. Also, the diagram of average angular frequency with respect to average longitudinal wave number is plotted so that the band gap regions of the clad are clearly observed.

The bent crystal diffraction spectrometer at the BR2 reactor in Mol

Science.gov (United States)

Kaerts, E.; Jacobs, L.; Vandenput, G.; Van Assche, P. H. M.

1988-05-01

The DuMond-type bent crystal diffraction spectrometer installed at the BR2 reactor in Mol is presented. The spectrometer is mainly designed to study nuclear γ-transitions following thermal neutron capture. It covers the energy interval 25 ≦ Eγ ≦ 1500 keV. Instead of the traditionally used quartz crystals, a highly perfect silicium crystal is chosen as analysing crystal. Diffraction occurs from the (220) plane. The "quasi-mosaic" width, introduced by bending the crystal, is as small as 0.2″. The integrated reflecting power R of the bent crystal stays constant up to 1.5 MeV in first, 680 keV in second and 300 keV in third diffraction order. For higher photon energies, only an E-1 energy dependence is observed in second and third diffraction order. Consequently, besides improving the energy resolution, the use of these silicium crystals substantially increases the spectrometer efficiency and extends the high energy limit of bent crystal diffraction spectrometers. The diffraction angles are measured with a symmetrical interferometer system which covers an angular range of -6° to +6° with a precision of about 0.01″. Minimum diffraction line widths of 0.9″ have been measured, corresponding to an energy resolution ΔE = 1.35 × 10 -6E2n-1 keV -1. The dominant contribution to the observed line widths arises from the finite extent of the source.

Magnetic Nanoparticle-Assisted Tunable Optical Patterns from Spherical Cholesteric Liquid Crystal Bragg Reflectors

Directory of Open Access Journals (Sweden)

Yali Lin

2017-11-01

Full Text Available Cholesteric liquid crystals (CLCs exhibit selective Bragg reflections of circularly polarized (CP light owing to their spontaneous self-assembly abilities into periodic helical structures. Photonic cross-communication patterns could be generated toward potential security applications by spherical cholesteric liquid crystal (CLC structures. To endow these optical patterns with tunability, we fabricated spherical CLC Bragg reflectors in the shape of microshells by glass-capillary microfluidics. Water-soluble magnetofluid with Fe3O4 nanoparticles incorporated in the inner aqueous core of CLC shells is responsible for the non-invasive transportable capability. With the aid of an external magnetic field, the reflection interactions between neighboring microshells and microdroplets were identified by varying the mutual distance in a group of magnetically transportable and unmovable spherical CLC structures. The temperature-dependent optical reflection patterns were investigated in close-packed hexagonal arrangements of seven CLC microdroplets and microshells with inverse helicity handedness. Moreover, we demonstrated that the magnetic field-assisted assembly of microshells array into geometric figures of uppercase English letters “L” and “C” was successfully achieved. We hope that these findings can provide good application prospects for security pattern designs.

Magnetic Nanoparticle-Assisted Tunable Optical Patterns from Spherical Cholesteric Liquid Crystal Bragg Reflectors.

Science.gov (United States)

Lin, Yali; Yang, Yujie; Shan, Yuwei; Gong, Lingli; Chen, Jingzhi; Li, Sensen; Chen, Lujian

2017-11-08

Cholesteric liquid crystals (CLCs) exhibit selective Bragg reflections of circularly polarized (CP) light owing to their spontaneous self-assembly abilities into periodic helical structures. Photonic cross-communication patterns could be generated toward potential security applications by spherical cholesteric liquid crystal (CLC) structures. To endow these optical patterns with tunability, we fabricated spherical CLC Bragg reflectors in the shape of microshells by glass-capillary microfluidics. Water-soluble magnetofluid with Fe₃O₄ nanoparticles incorporated in the inner aqueous core of CLC shells is responsible for the non-invasive transportable capability. With the aid of an external magnetic field, the reflection interactions between neighboring microshells and microdroplets were identified by varying the mutual distance in a group of magnetically transportable and unmovable spherical CLC structures. The temperature-dependent optical reflection patterns were investigated in close-packed hexagonal arrangements of seven CLC microdroplets and microshells with inverse helicity handedness. Moreover, we demonstrated that the magnetic field-assisted assembly of microshells array into geometric figures of uppercase English letters "L" and "C" was successfully achieved. We hope that these findings can provide good application prospects for security pattern designs.

Synchrotron Bragg diffraction imaging characterization of synthetic diamond crystals for optical and electronic power device applications1 1

Science.gov (United States)

Tran Thi, Thu Nhi; Morse, J.; Caliste, D.; Fernandez, B.; Eon, D.; Härtwig, J.; Mer-Calfati, C.; Tranchant, N.; Arnault, J. C.; Lafford, T. A.; Baruchel, J.

2017-01-01

Bragg diffraction imaging enables the quality of synthetic single-crystal diamond substrates and their overgrown, mostly doped, diamond layers to be characterized. This is very important for improving diamond-based devices produced for X-ray optics and power electronics applications. The usual first step for this characterization is white-beam X-ray diffraction topography, which is a simple and fast method to identify the extended defects (dislocations, growth sectors, boundaries, stacking faults, overall curvature etc.) within the crystal. This allows easy and quick comparison of the crystal quality of diamond plates available from various commercial suppliers. When needed, rocking curve imaging (RCI) is also employed, which is the quantitative counterpart of monochromatic Bragg diffraction imaging. RCI enables the local determination of both the effective misorientation, which results from lattice parameter variation and the local lattice tilt, and the local Bragg position. Maps derived from these parameters are used to measure the magnitude of the distortions associated with polishing damage and the depth of this damage within the volume of the crystal. For overgrown layers, these maps also reveal the distortion induced by the incorporation of impurities such as boron, or the lattice parameter variations associated with the presence of growth-incorporated nitrogen. These techniques are described, and their capabilities for studying the quality of diamond substrates and overgrown layers, and the surface damage caused by mechanical polishing, are illustrated by examples. PMID:28381981

Lead tungstate crystal of the ALICE Photon Spectrometer (PHOS)

CERN Document Server

Patrice Loïez

2002-01-01

A consignment of 500 lead tungstate crystals arrived at CERN from the northern Russian town of Apatity in May. Destined for the ALICE heavy-ion experiment in preparation for the Large Hadron Collider, each crystal is an 18 cm long rod with a 2.2 cm square section, and weighs some 750 g. A total of 17 000 crystals will make up the experiment's photon spectrometer.

Experimental study on slow flexural waves around the defect modes in a phononic crystal beam using fiber Bragg gratings

Energy Technology Data Exchange (ETDEWEB)

Chuang, Kuo-Chih, E-mail: chuangkc@zju.edu.cn; Zhang, Zhi-Qiang; Wang, Hua-Xin

2016-12-09

Highlights: • Slow waves around the defect modes in a phononic crystal beam are validated. • A fiber Bragg grating displacement sensing system can measure the defect mode. • The defect mode is analyzed by a transfer matrix method with a supercell technique. - Abstract: This work experimentally studies influences of the point defect modes on the group velocity of flexural waves in a phononic crystal Timoshenko beam. Using the transfer matrix method with a supercell technique, the band structures and the group velocities around the defect modes are theoretically obtained. Particularly, to demonstrate the existence of the localized defect modes inside the band gaps, a high-sensitivity fiber Bragg grating sensing system is set up and the displacement transmittance is measured. Slow propagation of flexural waves via defect coupling in the phononic crystal beam is then experimentally demonstrated with Hanning windowed tone burst excitations.

Interaction of the Bragg gap with polaritonic gap in opal photonic crystals

Science.gov (United States)

Nayer, Eradat; Sivachenko, Andrey Yu; Li, Sergey; Raikh, Mikhail E.; Valy Vardeny, Z.

2001-03-01

Photonic crystals (PC) are a class of artificial structures with a periodic dielectric function. PCs can be a laboratory for testing fundamental processes involving interactions of radiation with matter in novel conditions. We have studied the optical properties of opal PCs that are infiltrated with highly polarizable media such as j-aggregates of cyanine dyes. Opals are self- assembled structures of silica (SiO_2) spheres. We report our studies on clarifying the relationship between a polaritonic gap and a photonic stop band (Bragg gap) when they resonantly coexist in the same structure. Infiltration of opal with polarizable molecules combines the polaritonic and Bragg diffractive effects. Both effects exist independently when the Bragg (at ω=ω_B) and polaritonic (at ω=ω_T) resonances are well separated in frequency. A completely different situation occurs when ωT =ω_B. Such a condition was achieved in opals that were infiltrated with J-aggregates of cyanine dyes that have large Rabi frequency. Our measurements show some dramatic changes in the shape of the reflectivity plateaus, which are due to the interplay between the photonic band gap and the polaritonic gap. The experimental results on reflectivity and its dependence on the light propagation angle and concentration of the cyanie dyes are in agreement with the theoretical calculations. (The work was supported in part by Army Research office DAAD19-00-1-0406.)

Bragg reflection program

International Nuclear Information System (INIS)

Lynn, J.W.

This user's guide to the Bragg Reflection Program (BRP) is in the nature of an informal report. The general purpose of BRP is to scan a series of Bragg reflections automatically in order to obtain profiles and integrated intensities. The program is used in conjunction with the SUPERVISOR and READ packages, and the procedures for using it are similar to those for the Triple-Axis Control program. All the general features of the system, SUPERVISOR and READ packages as described in the Spectrometer Control Systems User's Guide are preserved. The presentation assumes that the reader is familiar with these. Sections are given on the READ package, execution and use, error messages, and output. A few sample problems are shown. (1 figure) (U.S.)

Diamond double-crystal monochromator in Bragg geometry installed on BL-11XU at SPring-8

CERN Document Server

Marushita, M; Fukuda, T; Takahasi, M; Inami, T; Katayama, Y; Shiwaku, H; Mizuki, J

2001-01-01

We present here the feature of the diamond double-crystal monochromator in Bragg geometry installed on a standard undulator beamline at SPring-8. The crystal was manufactured by Sumitomo Electric Industries, Ltd., whose size was 8.6 mm (w) x3.5 mm (l) x0.35 mm (t) for the first crystal and 10 mm (w) x4.7 mm (l) x0.39 mm (t) for the second. The feature of the monochromator was tested by rocking curve measurements as a function of the total power and of the energy that impinged on the crystal. As a result, no significant increase of the full-width at half-maximum was observed up to a total power of 330 W on the first crystal. We discuss the experimental results with the comparison to the calculated FWHM with use of the beamline parameters.

Design parameters of transmission curved crystal spectrometer for hard X-ray diagnoses

International Nuclear Information System (INIS)

Qian Feng; Cao Leifeng; Zhou Weimin; Zhao Zongqing; Gu Yuqiu; Yan Yonghong; Wei Lai; Xiao Shali

2013-01-01

The high resolving measurement of hard X-ray spectra generated in laser-produced plasma is usually performed using a cylindrically curved crystal spectrometer. In this paper, theoretical analysis and numerical simulation are performed to investigate the dependence of the energy range and resolving power on various design parameters, including crystal bending radius, source to crystal standoff distance, source size, location of the detector, etc. The investigation provides a means to design and develop cylindrically transmission curved crystal spectrometer which is used in hard X-ray diagnostics. The results show that crystal bending radius has a great influence on energy range of spectra and resolving power, and the separation between the spectral lines increases with the distance behind the focal circle faster than the line width, resulting in increased resolving power with distance. (authors)

X-ray spectroscopic study of high-temperature plasmas by curved crystal spectrometer

International Nuclear Information System (INIS)

Morita, Shigeru.

1983-07-01

Extensive studies have been carried out on the structure of X-ray spectra from the highly stripped ions of first transition elements and their behavior in high temperature plasma, using a high resolution crystal spectrometer. Calculation was made on the design and the use of a curved crystal spectrometer for plasma diagnostics. A Johann type crystal spectrometer for measuring X-ray lines was constructed on the basis of the calculation. The characteristics of curved crystals of LiF, Ge and quartz used for the measurement of Kα lines from first transition elements were investigated. Vacuum sparks have been formed for producing high temperature plasma which emits X-ray lines from highly stripped ions. Two different structures of vacuum spark plasma were shown, that is, thermalized point plasma and extended plasma associated with non-thermal electrons. The X-ray lines from the extended plasma, those associated with the K shell from the point plasma and the Kα lines of Ti through Zn from the point plasma have been observed. (Kako, I.)

Single crystal spectrometer FOX at KENS

International Nuclear Information System (INIS)

Takahashi, M.

2001-01-01

Single crystal spectrometer FOX installed at H1 thermal neutron line on KENS has been renewed recently for the measurement of very weak scattering. We have installed a multidetector system of 36 linearly placed 3 He detectors with collimators instead of former four-circle diffractometer and scintillator detectors. Though the system is quite simple, a large two-dimensional reciprocal space is observed effectively with high S/N rate on new FOX. (author)

Qualification of a high-efficiency, gated spectrometer for x-ray Thomson scattering on the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Döppner, T.; Kritcher, A. L.; Bachmann, B.; Burns, S.; Hawreliak, J.; House, A.; Landen, O. L.; LePape, S.; Ma, T.; Pak, A.; Swift, D. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Neumayer, P. [Gesellschaft für Schwerionenphysik, 64291 Darmstadt (Germany); Kraus, D. [University of California, Berkeley, California 94720 (United States); Falcone, R. W. [University of California, Berkeley, California 94720 (United States); Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Glenzer, S. H. [SLAC National Accelerator Laboratory, Menlo Park, California 94309 (United States)

2014-11-15

We have designed, built, and successfully fielded a highly efficient and gated Bragg crystal spectrometer for x-ray Thomson scattering measurements on the National Ignition Facility (NIF). It utilizes a cylindrically curved Highly Oriented Pyrolytic Graphite crystal. Its spectral range of 7.4–10 keV is optimized for scattering experiments using a Zn He-α x-ray probe at 9.0 keV or Mo K-shell line emission around 18 keV in second diffraction order. The spectrometer has been designed as a diagnostic instrument manipulator-based instrument for the NIF target chamber at the Lawrence Livermore National Laboratory, USA. Here, we report on details of the spectrometer snout, its novel debris shield configuration and an in situ spectral calibration experiment with a Brass foil target, which demonstrated a spectral resolution of E/ΔE = 220 at 9.8 keV.

Development of a high resolution x-ray spectrometer for the National Ignition Facility (NIF).

Science.gov (United States)

Hill, K W; Bitter, M; Delgado-Aparicio, L; Efthimion, P C; Ellis, R; Gao, L; Maddox, J; Pablant, N A; Schneider, M B; Chen, H; Ayers, S; Kauffman, R L; MacPhee, A G; Beiersdorfer, P; Bettencourt, R; Ma, T; Nora, R C; Scott, H A; Thorn, D B; Kilkenny, J D; Nelson, D; Shoup, M; Maron, Y

2016-11-01

A high resolution (E/ΔE = 1200-1800) Bragg crystal x-ray spectrometer is being developed to measure plasma parameters in National Ignition Facility experiments. The instrument will be a diagnostic instrument manipulator positioned cassette designed mainly to infer electron density in compressed capsules from Stark broadening of the helium-β (1s 2 -1s3p) lines of krypton and electron temperature from the relative intensities of dielectronic satellites. Two conically shaped crystals will diffract and focus (1) the Kr Heβ complex and (2) the Heα (1s 2 -1s2p) and Lyα (1s-2p) complexes onto a streak camera photocathode for time resolved measurement, and a third cylindrical or conical crystal will focus the full Heα to Heβ spectral range onto an image plate to provide a time integrated calibration spectrum. Calculations of source x-ray intensity, spectrometer throughput, and spectral resolution are presented. Details of the conical-crystal focusing properties as well as the status of the instrumental design are also presented.

Analysis and implementation of a space resolving spherical crystal spectrometer for x-ray Thomson scattering experiments.

Science.gov (United States)

Harding, E C; Ao, T; Bailey, J E; Loisel, G; Sinars, D B; Geissel, M; Rochau, G A; Smith, I C

2015-04-01

The application of a space-resolving spectrometer to X-ray Thomson Scattering (XRTS) experiments has the potential to advance the study of warm dense matter. This has motivated the design of a spherical crystal spectrometer, which is a doubly focusing geometry with an overall high sensitivity and the capability of providing high-resolution, space-resolved spectra. A detailed analysis of the image fluence and crystal throughput in this geometry is carried out and analytical estimates of these quantities are presented. This analysis informed the design of a new spectrometer intended for future XRTS experiments on the Z-machine. The new spectrometer collects 6 keV x-rays with a spherically bent Ge (422) crystal and focuses the collected x-rays onto the Rowland circle. The spectrometer was built and then tested with a foam target. The resulting high-quality spectra prove that a spherical spectrometer is a viable diagnostic for XRTS experiments.

Pulsed single-photon spectrometer by frequency-to-time mapping using chirped fiber Bragg gratings.

Science.gov (United States)

Davis, Alex O C; Saulnier, Paul M; Karpiński, Michał; Smith, Brian J

2017-05-29

A fiber-integrated spectrometer for single-photon pulses outside the telecommunications wavelength range based upon frequency-to-time mapping, implemented by chromatic group delay dispersion (GDD), and precise temporally-resolved single-photon counting, is presented. A chirped fiber Bragg grating provides low-loss GDD, mapping the frequency distribution of an input pulse onto the temporal envelope of the output pulse. Time-resolved detection with fast single-photon-counting modules enables monitoring of a wavelength range from 825 nm to 835 nm with nearly uniform efficiency at 55 pm resolution (24 GHz at 830 nm). To demonstrate the versatility of this technique, spectral interference of heralded single photons and the joint spectral intensity distribution of a photon-pair source are measured. This approach to single-photon-level spectral measurements provides a route to realize applications of time-frequency quantum optics at visible and near-infrared wavelengths, where multiple spectral channels must be simultaneously monitored.

Ultrafast Optical Signal Processing with Bragg Structures

Directory of Open Access Journals (Sweden)

Yikun Liu

2017-05-01

Full Text Available The phase, amplitude, speed, and polarization, in addition to many other properties of light, can be modulated by photonic Bragg structures. In conjunction with nonlinearity and quantum effects, a variety of ensuing micro- or nano-photonic applications can be realized. This paper reviews various optical phenomena in several exemplary 1D Bragg gratings. Important examples are resonantly absorbing photonic structures, chirped Bragg grating, and cholesteric liquid crystals; their unique operation capabilities and key issues are considered in detail. These Bragg structures are expected to be used in wide-spread applications involving light field modulations, especially in the rapidly advancing field of ultrafast optical signal processing.

The Simulation of Bragg-Case Section Images of Dislocations and Inclusions in Aspect of Identification of Defects in SiC Crystals

International Nuclear Information System (INIS)

Balcer, T.; Wierzchowski, W.; Wieteska, K.

2010-01-01

The numerical simulation has been applied for studying of Bragg-case section topographic images of dislocation and rod-like inclusions. The validity of simple approximation of extinction contrast was confirmed in the case of screw dislocations in silicon carbide crystals. A procedure for approximate calculation of the strain field of rod-like inclusion was constructed, consisting of adding the contributions from a very large number of point-like inclusions uniformly distributed inside the assumed volume of the inclusion. The procedure ensured a reasonable similarity between the simulated topographs and experimental Bragg-case section topographic images of some pipe-formed cavities in silicon carbide crystals. The method is useful for some other materials, e.g. it enabled to compute realistic simulation of plane-wave topographs of the rod-like inclusions in YAG. (authors)

Crystal mosaic spread determination by slow neutron scattering

International Nuclear Information System (INIS)

Adib, M.; Naguib, K.; Abdel Kawy, A.; Ashry, A.; Abbas, Y.; Wahba, M.; Maayouf, M.A.

1988-01-01

A method has been established for determination of the crystal mosaic spread. The method is based on recording all neutron-reflected, under bragg condition, from a certain crystal plane. A computer code was developed especially in order to fit the measured wavelength's distribution of the reflected neutrons with the calculated one, assuming that the crystal mosaic spread has a Gaussian shape. The code accounts for the parameters of the time of flight spectrometer used during the present measurements, as well as divergence of the incident neutron beam. The developed method has been applied for determination of the mosaic spread of both zinc and pyrolytic graphite (P.G.) crystals. The mosaic spread values deduced from the present measurements, are 10'+-6' and 3.60 0 +-0.16 0 respectively for Zn and P.G. crystals

Ultra-thin distributed Bragg reflectors via stacked single-crystal silicon nanomembranes

Energy Technology Data Exchange (ETDEWEB)

Cho, Minkyu; Seo, Jung-Hun; Lee, Jaeseong; Mi, Hongyi; Kim, Munho; Ma, Zhenqiang, E-mail: mazq@engr.wisc.edu [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Zhao, Deyin; Zhou, Weidong [Nanophotonics Lab, Department of Electrical Engineering, University of Texas at Arlington, Arlington, Texas 76019 (United States); Yin, Xin; Wang, Xudong [Department of Material Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2015-05-04

In this paper, we report ultra-thin distributed Bragg reflectors (DBRs) via stacked single-crystal silicon (Si) nanomembranes (NMs). Mesh hole-free single-crystal Si NMs were released from a Si-on-insulator substrate and transferred to quartz and Si substrates. Thermal oxidation was applied to the transferred Si NM to form high-quality SiO{sub 2} and thus a Si/SiO{sub 2} pair with uniform and precisely controlled thicknesses. The Si/SiO{sub 2} layers, as smooth as epitaxial grown layers, minimize scattering loss at the interface and in between the layers. As a result, a reflection of 99.8% at the wavelength range from 1350 nm to 1650 nm can be measured from a 2.5-pair DBR on a quartz substrate and 3-pair DBR on a Si substrate with thickness of 0.87 μm and 1.14 μm, respectively. The high reflection, ultra-thin DBRs developed here, which can be applied to almost any devices and materials, holds potential for application in high performance optoelectronic devices and photonics applications.

Focusing, adjustable spectrometer with temporal resolution for the Sandia Z facility

International Nuclear Information System (INIS)

Sinars, D. B.; Wenger, D. F.; Keller, K. L.; Rochau, G. A.; Porter, J. L.

2006-01-01

Spherically bent focusing spectrometers with one- or two-dimensional spatial resolution (FSSR) are commonly used to obtain spectra with λ/Δλ>1000 from laser and exploding-wire plasmas. The focal properties of such spectrometers make them ideally suited for coupling with x-ray streak cameras when imaging small sources. We discuss the design of a streaked FSSR system intended to measure time-resolved emission spectra with time resolutions 2000 for source sizes ∼1 mm. The narrow spectral range (∼0.04 nm) can be adjusted between tests by varying the central Bragg angle (35 deg. -55 deg.) range and/or by exchanging the crystal type. The high spectral resolution is ideal for detailed line shape measurements. An example configuration for studying H- and He-like Ar emission is presented

Data processing for elliptical crystal spectrometer used in Z-pinch diagnostic

International Nuclear Information System (INIS)

Li Jing; Xie Weiping; Huang Xianbin; Yang Libing; Cai Hongchun; Xiao Shali

2010-01-01

Elliptical crystal spectrometers are key instruments to detect the line spectra of soft X-rays in Z-pinch diagnostics. This paper deals with the data processing for an elliptical crystal spectrometer. Taking the diagnostic results obtained in a neon gas-puff Z-pinch experiment as an example, the detailed processes, such as changing the optical density to X-ray intensity according a calibrated film response curve, determining the X-ray energy of the measured spectrum using the energy and the order number of scanned point of identified spectral lines, and correcting the intensity of spectrum using the formula given by Henke are discussed. In the Henke's formula, the effect of nonuniform dispersion, integrated reflectivity of crystals and transmission of X-ray filters are considered. The final unfolding results are presented, including the relative intensities of several neon K-shell lines (H α , He α and He β , etc.) given by Lorentz fitting. The relative errors of the spectral intensities are also briefly discussed. (authors)

Excitation of surface electromagnetic waves in a graphene-based Bragg grating.

Science.gov (United States)

Sreekanth, Kandammathe Valiyaveedu; Zeng, Shuwen; Shang, Jingzhi; Yong, Ken-Tye; Yu, Ting

2012-01-01

Here, we report the fabrication of a graphene-based Bragg grating (one-dimensional photonic crystal) and experimentally demonstrate the excitation of surface electromagnetic waves in the periodic structure using prism coupling technique. Surface electromagnetic waves are non-radiative electromagnetic modes that appear on the surface of semi-infinite 1D photonic crystal. In order to fabricate the graphene-based Bragg grating, alternating layers of high (graphene) and low (PMMA) refractive index materials have been used. The reflectivity plot shows a deepest, narrow dip after total internal reflection angle corresponds to the surface electromagnetic mode propagating at the Bragg grating/air boundary. The proposed graphene based Bragg grating can find a variety of potential surface electromagnetic wave applications such as sensors, fluorescence emission enhancement, modulators, etc.

A cadmium-zinc-telluride crystal array spectrometer

International Nuclear Information System (INIS)

McHugh, H. R.; Quam, W.; DeVore, T.; Vogle, R.; Weslowski, J.

2003-01-01

This paper describes a gamma detector employing an array of eight cadmium-zinc-telluride (CZT) crystals configured as a high resolution gamma ray spectrometer. This detector is part of a more complex instrument that identifies the isotope,displays this information, and records the gamma spectrum. Various alarms and other operator features are incorporated in this battery operated rugged instrument. The CZT detector is the key component of this instrument and will be described in detail in this paper. We have made extensive spectral measurements of the usual laboratory gamma sources, common medical isotopes, and various Special Nuclear Materials (SNM) with this detector. Some of these data will be presented as spectra. We will also present energy resolution and detection efficiency for the basic 8-crystal array. Additional data will also be presented for a 32-crystal array. The basic 8-crystal array development was completed two years ago, and the system electronic design has been imp roved recently. This has resulted in significantly improved noise performance. We expect to have a much smaller detector package, using 8 crystals, in a few months. This package will use flip-chip packaging to reduce the electronics physical size by a factor of 5

Broadband crystal spectrometer for the non-active and active phases of JET

International Nuclear Information System (INIS)

Engelhardt, W.; Fink, J.; Fussmann, G.; Krause, H.; Schilling, H.B.; Schumacher, U.

1982-03-01

The design study treats the possibilities of quantitatively measuring the Soft X-ray spectrum of JET with a double crystal spectrometer device in parallel mode. This spectrometer type is much suited for broad band soft X-ray spectroscopy, also - due to its folded optical pathway - during D-T operation of JET; the expected detector count rates are far above the background level. Methods to fulfill the important condition of parallel orientation of the two crystals, to shield the device against neutrons and gamma rays, to obtain spectral resolution sufficient for spectral line profile measurements and to upgrade the device for continuous spatial scanning of the JET plasma are presented. (orig.)

A short working distance multiple crystal x-ray spectrometer

Science.gov (United States)

Dickinson, B.; Seidler, G.T.; Webb, Z.W.; Bradley, J.A.; Nagle, K.P.; Heald, S.M.; Gordon, R.A.; Chou, I.-Ming

2008-01-01

For x-ray spot sizes of a few tens of microns or smaller, a millimeter-sized flat analyzer crystal placed ???1 cm from the sample will exhibit high energy resolution while subtending a collection solid angle comparable to that of a typical spherically bent crystal analyzer (SBCA) at much larger working distances. Based on this observation and a nonfocusing geometry for the analyzer optic, we have constructed and tested a short working distance (SWD) multicrystal x-ray spectrometer. This prototype instrument has a maximum effective collection solid angle of 0.14 sr, comparable to that of 17 SBCA at 1 m working distance. We find good agreement with prior work for measurements of the Mn K?? x-ray emission and resonant inelastic x-ray scattering for MnO, and also for measurements of the x-ray absorption near-edge structure for Dy metal using L??2 partial-fluorescence yield detection. We discuss future applications at third- and fourth-generation light sources. For concentrated samples, the extremely large collection angle of SWD spectrometers will permit collection of high-resolution x-ray emission spectra with a single pulse of the Linac Coherent Light Source. The range of applications of SWD spectrometers and traditional multi-SBCA instruments has some overlap, but also is significantly complementary. ?? 2008 American Institute of Physics.

X-ray crystal spectrometer upgrade for ITER-like wall experiments at JET

Energy Technology Data Exchange (ETDEWEB)

Shumack, A. E., E-mail: amy.shumack@ccfe.ac.uk [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); FOM Institute DIFFER, P.O. Box 1207, NL-3430 BE Nieuwegein (Netherlands); Rzadkiewicz, J. [National Centre for Nuclear Research, Andrzeja Sołtana 7, 05-400 Otwock (Poland); Chernyshova, M.; Czarski, T.; Karpinski, L. [Institute of Plasma Physics and Laser Microfusion, Hery 23, 01-497 Warsaw (Poland); Jakubowska, K. [Institute of Plasma Physics and Laser Microfusion, Hery 23, 01-497 Warsaw (Poland); Université Bordeaux, CNRS, CEA, CELIA, UMR 5107, F-33405 Talence (France); Scholz, M. [Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Kraków (Poland); Byszuk, A.; Cieszewski, R.; Kasprowicz, G.; Pozniak, K.; Wojenski, A.; Zabolotny, W. [Institute of Electronic Systems, Warsaw University of Technology, 00-665 Warsaw (Poland); Dominik, W. [Faculty of Physics, Institute of Experimental Physics, Warsaw University, 00-681 Warsaw (Poland); Conway, N. J.; Dalley, S.; Tyrrell, S.; Zastrow, K.-D. [JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Figueiredo, J. [EFDA-CSU, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Associação EURATOM/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Av Rovisco Pais, 1049-001 Lisbon (Portugal); and others

2014-11-15

The high resolution X-Ray crystal spectrometer at the JET tokamak has been upgraded with the main goal of measuring the tungsten impurity concentration. This is important for understanding impurity accumulation in the plasma after installation of the JET ITER-like wall (main chamber: Be, divertor: W). This contribution provides details of the upgraded spectrometer with a focus on the aspects important for spectral analysis and plasma parameter calculation. In particular, we describe the determination of the spectrometer sensitivity: important for impurity concentration determination.

Objective Crystal Spectrometer (OXS) for the Spectrum-X-γ satellite

DEFF Research Database (Denmark)

Christensen, Finn Erland; Byrnak, B.P.; Hornstrup, Allan

1990-01-01

The status of the Objective Crystal Spectrometer (OXS) to be flown on the Soviet Spectrum-X-Gamma satellite together with the X-ray investigation of two of the three natural crystals (LiF(220), Ge(111) and RAP(001) which are chosen as the baseline option are presented. An important result...... on the LiF(220) and Ge(111) surfaces is presented. This design allows simultaneous spectroscopy in two energy bands each centered on cosmically interesting line emission regions. X-ray reflectivity measurements demonstrate that the crystal surface can be made sufficiently smooth for the application...

High-resolution bent-crystal spectrometer for the ultra-soft x-ray region

International Nuclear Information System (INIS)

Beiersdorfer, P.; von Goeler, S.; Bitter, M.; Hill, K.W.; Hulse, R.A.; Walling, R.S.

1988-10-01

A multichannel vacuum Brag-crystal spectrometer has been developed for high-resolution measurements of the line emission from tokamak plasmas in the wavelength region between 4 and 25 /angstrom/. The spectrometer employs a bent crystal in Johann geometry and a microchannel-plate intensified photodiode array. The instrument is capable of measuring high-resolution spectra (λ/Δλ ∼ 3000) with fast time resolution (4 msec per spectrum) and good spatial resolution (3 cm). The spectral bandwidth is Δλ/λ 0 = 8/angstrom/. A simple tilt mechanism allows access to different wavelength intervals. In order to illustrate the utility of the new spectrometer, time- and space-resolved measurements of the n = 3 to n = 2 spectrum of selenium from the Princeton Large Torus tokamak plasmas are presented. The data are used to determine the plasma transport parameters and to infer the radial distribution of fluorinelike, neonlike, and sodiumlike ions of selenium in the plasma. The new ultra-soft x-ray spectrometer has thus enabled us to demonstrate the utility of high-resolution L-shell spectroscopy of neonlike ions as a fusion diagnostic. 43 refs., 23 figs

Qualification study of LiF flight crystals for the objective crystal spectrometer on the SPECTRUM-X-GAMMA satellite

DEFF Research Database (Denmark)

Christensen, Finn Erland; Rasmussen, I.; Schnopper, Herbert W.

1992-01-01

The Objective Crystal Spectrometer (OXS) on the SPECTRUM-X-GAMMA satellite will carry these types of natural crystals LiF(220), Ge(111) and RAP(001). They will be used to study, among others, the H- and the He-like emission from the cosmically important elements Fe, S, Ar and O. More than 300 Li...

Three-dimensional Bragg diffraction in growth-disordered opals

Science.gov (United States)

Baryshev, A. V.; Kaplyanskii, Alexander A.; Kosobukin, Vladimir A.; Limonov, M. F.; Samusev, K. B.; Usvyat, D. E.

2003-06-01

After artificial opals as well as opal-based infilled and inverted composites are considered to be promising representatives of photonic crystal materials. Earlier, photonic stop gaps in opals were studied mainly in transmission or specular reflection geometries corresponding to "one-dimensional" Bragg diffraction. On the contrary, this work was aimed at observing the typical patterns of optical Bragg diffraction in which phenomenon opal crystal structure acts as a three-dimensional diffraction grating. Although our experiments were performed for artificial opals possessing unavoidable imperfections a well-pronounced diffraction peaks were observed characteristic of a crystal structure. Each of the diffraction maxima reveals a photonic stop gap in the specified direction, while the spectral width of the peak is a measure of the photonic stop gap width.

Improving a high-efficiency, gated spectrometer for x-ray Thomson scattering experiments at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Döppner, T., E-mail: doeppner1@llnl.gov; Bachmann, B.; Emig, J.; Hardy, M.; Kalantar, D. H.; Kritcher, A. L.; Landen, O. L.; Ma, T.; Wood, R. D. [Lawrence Livermore National Laboratory, Livermore, California 94720 (United States); Kraus, D.; Saunders, A. M. [University of California, Berkeley, California 94720 (United States); Neumayer, P. [Gesellschaft für Schwerionenphysik, Darmstadt (Germany); Falcone, R. W. [University of California, Berkeley, California 94720 (United States); Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Fletcher, L. B. [SLAC National Accelerator Laboratory, Menlo Park, California 94720 (United States)

2016-11-15

We are developing x-ray Thomson scattering for applications in implosion experiments at the National Ignition Facility. In particular we have designed and fielded MACS, a high-efficiency, gated x-ray spectrometer at 7.5–10 keV [T. Döppner et al., Rev. Sci. Instrum. 85, 11D617 (2014)]. Here we report on two new Bragg crystals based on Highly Oriented Pyrolytic Graphite (HOPG), a flat crystal and a dual-section cylindrically curved crystal. We have performed in situ calibration measurements using a brass foil target, and we used the flat HOPG crystal to measure Mo K-shell emission at 18 keV in 2nd order diffraction. Such high photon energy line emission will be required to penetrate and probe ultra-high-density plasmas or plasmas of mid-Z elements.

Thermal neutron spectra measurements in IEAR-1 Reactor, by using a crystal spectrometer

International Nuclear Information System (INIS)

Fulfaro, R.; Figueiredo Neto, A.M.; Stasiulevicius, E.; Vinhas, L.A.

1975-01-01

The thermal neutron spectrum of the IEN Argonauta reactor has been measured in the wavelength from 0.7 to 1.9A, using a neutron crystal spectrometer. An aluminium single crystal, in transmission, was used as monochromator. The aluminium crystal reflectivity employed in the analysis of the data was calculated for the first five permitted orders. An effective absorption coefficient of the crystal was used to perform the calculations instead of the macroscopic cross section of the element

Lead-Tungstate Crystal of the ALICE Photon Spectrometer (PHOS)

CERN Multimedia

2003-01-01

The photon spectrometer (PHOS) is designed to measure the temperature of collisions by detecting photons emerging from them. It will be made of lead tungstate crystals like these. When high-energy photons strike lead tungstate, they make it glow, or scintillate, and this glow can be measured. Lead tungstate is extremely dense (denser than iron), stopping most photons that reach it.

Birefringence Bragg Binary (3B) grating, quasi-Bragg grating and immersion gratings

Science.gov (United States)

Ebizuka, Noboru; Morita, Shin-ya; Yamagata, Yutaka; Sasaki, Minoru; Bianco, Andorea; Tanabe, Ayano; Hashimoto, Nobuyuki; Hirahara, Yasuhiro; Aoki, Wako

2014-07-01

A volume phase holographic (VPH) grating achieves high angular dispersion and very high diffraction efficiency for the first diffraction order and for S or P polarization. However the VPH grating could not achieve high diffraction efficiency for non-polarized light at a large diffraction angle because properties of diffraction efficiencies for S and P polarizations are different. Furthermore diffraction efficiency of the VPH grating extinguishes toward a higher diffraction order. A birefringence binary Bragg (3B) grating is a thick transmission grating with optically anisotropic material such as lithium niobate or liquid crystal. The 3B grating achieves diffraction efficiency up to 100% for non-polarized light by tuning of refractive indices for S and P polarizations, even in higher diffraction orders. We fabricated 3B grating with liquid crystal and evaluated the performance of the liquid crystal grating. A quasi-Bragg (QB) grating, which consists long rectangle mirrors aligned in parallel precisely such as a window shade, also achieves high diffraction efficiency toward higher orders. We fabricated QB grating by laminating of silica glass substrates and glued by pressure fusion of gold films. A quasi-Bragg immersion (QBI) grating has smooth mirror hypotenuse and reflector array inside the hypotenuse, instead of step-like grooves of a conventional immersion grating. An incident beam of the QBI grating reflects obliquely at a reflector, then reflects vertically at the mirror surface and reflects again at the same reflector. We are going to fabricate QBI gratings by laminating of mirror plates as similar to fabrication of the QB grating. We will also fabricate silicon and germanium immersion gratings with conventional step-like grooves by means of the latest diamond machining methods. We introduce characteristics and performance of these gratings.

High-energy e- /e+ spectrometer via coherent interaction in a bent crystal

Science.gov (United States)

Bagli, Enrico; Guidi, Vincenzo; Howard, Alexander

2018-01-01

We propose a novel spectrometer based on the crystal channeling effect capable of discriminating between positive and negative particles well beyond the TeV energy scale. The atomic order of a crystalline structure generates an electrostatic field built up by all the atoms in the crystals, which confines charged particle trajectories between neighbouring atomic planes. Through such an interaction in a tiny curved crystal, the same dynamical action on the highest energy particles as that of a huge superconducting magnet is achieved. Depending on the charge sign, points of equilibrium of the oscillatory motion under channeling lie between or on atomic planes for positive and negative particles, respectively, forcing positive particles to stably oscillate far from the planes, while negative ones repeatedly cross them. The different interaction rate with atomic planes causes a tremendous discrepancy between the deflection efficiency of positive and negative particles under channeling. We suggest the use of interactions between charged particles and oriented bent crystals as a novel non-cryogenic passive charge spectrometer to aid the search for dark matter in the Universe in satellite-borne experiment. The limited angular acceptance makes this technique particularly suited for directional local sources of energetic charged particles.

Energy dispersive X-ray fluorescence analysis with Bragg polarized Mo radiation. Energiedispersive Roentgenfluoreszenzanalyse mit Bragg-polarisierter Mo Strahlung

Energy Technology Data Exchange (ETDEWEB)

Gloeckl, H

1983-01-01

The aim of introducing energy dispersive analysis into X-ray fluorescence analysis is to suppress background from the Bremsstrahlung spectrum and the characteristic radiation without an undue reduction of the signal. The variant under consideration uses linearly polarization radiation obtained after a Bragg reflection,under delta = 90/sup 0/. In an introductory part, Bragg reflection, fluorescence and strong radiation are considered quantitatively with respect to counting statistics and detection limits. In the experimental part two combinations are describe, of a Ta crystal with a Cr tube and of a Mo crystal with a Mo tube. Details of adjustment, sample preparation and calibration and detection limits are given. The pros and cons of the Ta/Cr and the Mo/Mo are contrasted and proposals for further improvements are given.

Bragg reflection transmission filters for variable resolution monochromators

International Nuclear Information System (INIS)

Chapman, D.

1989-01-01

There are various methods for improving the angular and spectral resolution of monochromator and analyzer systems. The novel system described here, though limited to higher x-ray energies (>20keV), is based on a dynamical effect occurring on the transmitted beam with a thin perfect crystal plate set in the Bragg reflection case. In the case of Bragg reflection from a perfect crystal, the incident beam is rapidly attenuated as it penetrates the crystal in the range of reflection. This extinction length is of the order of microns. The attenuation length, which determines the amount of normal transmission through the plate is generally much longer. Thus, in the range of the Bragg reflection the attenuation of the transmitted beam can change by several orders of magnitude with a small change in energy or angle. This thin crystal plate cuts a notch in the transmitted beam with a width equal to its Darwin width, thus acting as a transmission filter. When used in a non-dispersive mode with other monochromator crystals, the filter when set at the Bragg angle will reflect the entire Darwin width of the incident beam and transmit the wings of the incident beam distribution. When the element is offset in angle by some fraction of the Darwin width, the filter becomes useful in adjusting the angular width of the transmitted beam and removing a wing. Used in pairs with a symmetric offset, the filters can be used to continuously adjust the intrinsic angular divergence of the beam with good wing reduction. Instances where such filters may be useful are in improving the angular resolution of a small angle scattering camera. These filters may be added to a Bonse-Hart camera with one pair on the incident beam to reduce the intrinsic beam divergence and a second pair on the analyzer arm to improve the analyzer resolution. 2 refs., 3 Figs

VOXES: a high precision X-ray spectrometer for diffused sources with HAPG crystals in the 2–20 keV range

Science.gov (United States)

Scordo, A.; Curceanu, C.; Miliucci, M.; Shi, H.; Sirghi, F.; Zmeskal, J.

2018-04-01

Bragg spectroscopy is one of the best established experimental methods for high energy resolution X-ray measurements and has been widely used in several fields, going from fundamental physics to quantum mechanics tests, synchrotron radiation and X-FEL applications, astronomy, medicine and industry. However, this technique is limited to the measurement of photons produced from well collimated or point-like sources and becomes quite inefficient for photons coming from extended and diffused sources like those, for example, emitted in the exotic atoms radiative transitions. The VOXES project's goal is to realise a prototype of a high resolution and high precision X-ray spectrometer, using Highly Annealed Pyrolitic Graphite (HAPG) crystals in the Von Hamos configuration, working also for extended sources. The aim is to deliver a cost effective system having an energy resolution at the level of eV for X-ray energies from about 2 keV up to tens of keV, able to perform sub-eV precision measurements with non point-like sources. In this paper, the working principle of VOXES, together with first results, are presented.

Bragg transmission phase plates for the production of circularly polarized x-rays

International Nuclear Information System (INIS)

Lang, J.C.; Srajer, G.

1994-01-01

A thin-crystal Si (400) Bragg transmission x-ray phase plate has been constructed for the production of 5 to 12 keV circularly polarized x-rays. Using multiple beam diffraction from a GaAs crystal, a direct measurement of the degree of circular polarization as a function of off-Bragg position was made. These measurements indicated nearly complete circular polarization (|P c | ≥ 0.95) and full helicity reversal on opposite sides of the rocking curve

FIBER LASER CONSTRUCTION AND THEORY INCLUDING FIBER BRAGG GRATINGS Photonic Crystal Fibers (PCFs) and applications of gas filled PCFs

Energy Technology Data Exchange (ETDEWEB)

Sutton, Jacob O. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-03-08

The principles used in fiber lasers have been around for a while but it is only within the past few years that fiber lasers have become commercially available and used in high power laser applications. This paper will focus on the basic design principles of fiber lasers, including fiber Bragg gratings, principles of operation, and forms of non-linear effects. It will describe the type and associated doping of the fiber used and difficult designs used to guide energy from the pump to the active medium. Topics covered include fiber laser design, fiber Bragg gratings, materials used, differences in quantum energy loss, thermo-optical effects, stimulated Raman scattering, Brillouin scattering, photonic crystal fibers and applications of gas filled Photonic Crystal Fibers (PCFs). Thanks to fiber lasers, the energy required to produce high power lasers has greatly dropped and as such we can now produce kW power using a standard 120V 15A circuit. High power laser applications are always requiring more power. The fiber laser can now deliver the greater power that these applications demand. Future applications requiring more power than can be combined using standard materials or configurations will need to be developed to overcome the high energy density and high non-linear optical scattering effects present during high power operations.

Error Measurements in an Acousto-Optic Tunable Filter Fiber Bragg Grating Sensor System

Science.gov (United States)

1994-05-01

for an ideal AOTF, at 833 and 838 nm using a TeO2 crystal ............................ 33 Figure 3.12. Frequency characteristics of Equation (3.43...multiple channels in an AOTF requires the presence of multiple RF frequencies to establish the complex grating. Since the crystal used in the AOTF ( TeO2 ) is...in germano- silicate glass . This index modulation, Bragg grating, acts as an optical band rejection filter for those wavelengths that meet the Bragg

Storage of cold and thermal neutrons with perfect crystals at the pulsed source

International Nuclear Information System (INIS)

Jericha, E.

1996-12-01

The possibility of storing cold neutrons by sequential Bragg reflections between two parallel perfect crystal plates in backscattering geometry has been implemented as the parasitic instrument VESTA at the pulsed neutron source ISIS. Filling the neutrons into and releasing them from the storage cavity is accomplished by applying a short-pulsed magnetic field at the crystal plates. The method takes advantage of the conservation of the axial component of the neutron wave vector after Bragg reflection and its Zeeman shift in a magnetic field. The setup at ISIS is presented where a monochromatic neutron beam with wavelength 6.27 A and 2.9 x 10 4 n/scm 2 flux is taken out of the neutron guide leading to the IRIS backscattering spectrometer by a pyrolytic graphite crystal monochromator. The longest storage period obtained with the setup was 2.655 s which corresponds to 1574 consecutive Bragg reflections and a distance traveled of 1675 n. The measurements are analyzed by heuristic methods developed for neutron storage experiments. The apparatus is seen as a passive resonator system and characteristics like stored neutron intensity, the efficiency of the storage process, the probability to remain in the system, the mirror reflectivity, the dispersion of the stored distribution, the penetration depth of a neutron into a crystal mirror and the figure of merit of the resonator system are discussed. Monte Carlo simulations of the extracted beam and of the stored neutron distribution were performed to deepen the understanding of the experimental results. (author)

Geometrical and wave-optical effects on the performance of a bent-crystal dispersive X-ray spectrometer

International Nuclear Information System (INIS)

Sutter, J.P.; Amboage, M.; Hayama, S.; Diaz-Moreno, S.

2010-01-01

The X-ray focusing properties of a bent single crystal diffracting in Bragg geometry are discussed. First, it is assumed that a polychromatic point source is focused to a point image. The elliptical arc that the crystal must trace and the aberrations caused by bending the crystal cylindrically are derived from the ray paths. For a source of finite size, the magnification is found to vary over the crystal's length, so that rays of different wavelength produce images of different size. More realistic treatments of penetration and diffraction are performed with spherical monochromatic incident waves, using Takagi-Taupin calculations to create the diffracted wave and the Fresnel integral to trace the diffracted wave's evolution. Such 'wave-optical' calculations on a symmetric Si (1 1 1) crystal with 7 keV X-rays predict beam sizes different from those found in ray traces. Optimal sample and detector placement therefore requires wave effects to be considered.

Bragg rotor spectrometer for tokamak diagnostics

International Nuclear Information System (INIS)

Barnsley, R.; Evans, K.D.; Peacock, N.J.

1986-01-01

This paper discusses high thru'put broad band (1-24 angstrom) x-ray spectrometer having absolute calibration for wavelength and intensity and demonstrated on the DITE tokamak. This instrument has a self-contained vacuum system which allows full spatial scans of the DITE plasma. Data acquisition and drive mechanism for the rotor and filter selection are operated remotely from a SADA. Results are presented of fast spectral surveys and λ-lock time-evolution of impurity emission during neutral beam injection. Spatial scans of the absolute impurity concentrations are derived

Design and construction of a triple-axis crystal neutron spectrometer and performance testing by means of measurements of dispersion relations in copper

International Nuclear Information System (INIS)

Fuhrmann, C.

1979-01-01

The Triple-Axis Crystal Neutron Spectrometer is the best instrument for the study of lattice dynamics, when the neutron inelastic scattering technique is used. Design, construction and operation of a triple-axis crystal neutron spectrometer, whose construction was recently finished at IEA are described. The design principles employed are directed to mechanical simplicity, facility of construction and flexibility in operation, with no adapted components to industrial applications were used in the construction. The operational characteristics of the spectrometer, such as the neutron wavelenght of the incoming beam and the resolution have been determined. With the purpose to check the performance of IEA Triple-Axis Crystal Neutron Spectrometer, dispersion relation curves for copper, at room temperature, have been measured. The frequency of phonons propagating along three major symmetry directions have been determined. The measurements were carried out operating the Triple-Axis Spectrometer in the 'sup(→)Q-constant' mode. An excelent agreement could be observed between the results obtained in the present experiment and the data for copper presented in the literature. This comparison indicates that the IEA Triple-Axis Crystal Neutron Spectrometer is in good operational conditions and is able to perform original experiments. Details on the experimental procedures for the case of a Triple-Axis Spectrometer operating in 'sup(→)Q-constant' mode are also presented. (Author) [pt

Optical Fiber Thermometer Based on Fiber Bragg Gratings

Science.gov (United States)

Rosli, Ekbal Bin; Mohd. Noor, Uzer

2018-03-01

Fiber Bragg grating has generated much interest in use as sensors to measure strain, temperature, and other physical parameters. It also the most common component used to develop this sensor with the advantages of simple, intrinsic sensing elements, electrically passive operation, EMI immunity, high sensitivity, compact size and potentially low cost [6]. This paper reports the design of an optical fiber thermometer based on fiber Bragg gratings. The system was developed for detecting temperature and strain by monitoring the shift of Bragg wavelength. The shifting of Bragg wavelength is used to indicate the temperature and strain due to the change in the surrounding temperature and strain. When the temperature and strain reach the exact wavelength level of the system, the temperature and strain value will display on the Arduino liquid crystal display (LCD). The optical fiber will provide the broadband light source and after passing the FBG the Bragg wavelength into the optical spectrum analyzer (OSA). The system is based on FBG as a physical quantity sensor. The temperatures measured is taken from the water bath and that of the strain is provided by amount of slotted mass used. The outcome of this project is to characterize the Bragg wavelength shifting from the fiber Bragg grating output. As the conclusion, this project provides an efficient optical fiber thermometer in measuring temperature and strain in order to replace the use of conventional electrical instruments.

Analysis of rocking curve measurements of LiF flight crystals for the objective crystal spectrometer on SPECTRUM-X-GAMMA

DEFF Research Database (Denmark)

Halm, I.; Wiebicke, H.-J.; Geppert, U.R.M.E.

1993-01-01

The Objective Crystal Spectrometer on the SPECTRUM-X-GAMMA satellite will use three types of natural crystals LiF(220), Si(111), RAP(001), and a multilayer structure providing high-resolution X- ray spectroscopy of Fe, S, O, and C line regions of bright cosmic X-ray sources. 330 - 360 LiF(220......) crystals of dimensions approximately 23 × 63 mm2 are required to cover one side of a large (1000 × 600 mm2) panel, which is to be mounted in front of one of two high throughput X- ray telescopes. Rocking curves of 441 LiF(220) crystals measured by using an expanded Cu - Kα2 beam were analyzed to select...... the main parameters of the rocking curve averaged over all crystals can be improved at least by a factor of 1.6 both in full width half maximum and peak reflectivity....

Measurements of the total neutron cross-sections of poly- and mono-germanium crystals at neutron energies below 1 eV

International Nuclear Information System (INIS)

Maayouf, R.M.A.; Abdel-Kawy, A.; Abbas, Y.; Habib, N.; Adib, M.; Hamouda, I.

1983-12-01

Total neutron cross-section measurements have been performed for poly and mono-germanium crystals in the energy range from 2 meV-1eV. The measurements were performed using two TOF and a double axis crystal spectrometer installed at the ET-RR-1 reactor. The obtained neutron cross-sections were analyzed using the single level Breit-Wigner formula. The coherent scattering amplitude was determined from the Bragg reflections observed in the total neutron cross-section of Ge and the analysis of its neutron diffraction pattern. The incoherent and thermal diffuse scattering cross-sections of Ge were estimated from the analysis of the total cross-section data obtained for Ge mono-crystal

Mirror and Bragg reflections of neutrons at a nuclear resonance: [Final technical report

International Nuclear Information System (INIS)

Batigun, C.M.; Brugger, R.M.

1987-01-01

These experiments have observed the mirror reflection and Bragg diffraction of neutrons at the energy of a low lying nuclear resonance of 115 In. The reflector was a mirror of In metal with the resonance at 1.457 eV. The mirror reflection for different angles of incidence has been measured and sets of data showing the relative reflectivities have been obtained. For the Bragg diffraction, the crystal was a wafer of InP and several examples of Bragg reflections near 1.455 eV were measured. 4 refs., 12 figs

Instrumentations in x-ray plasma polarization spectroscopy. Crystal spectrometer, polarimeter and detectors for astronomical observations

Energy Technology Data Exchange (ETDEWEB)

Baronova, Elena O.; Stepanenko, Mikhail M. [RRC Kurchatov Institute, Nuclear Fusion Institute, Moscow (Russian Federation); Jakubowski, Lech [Soltan Institute for Nuclear Studies, Swierk-Otwock (Poland); Tsunemi, Hiroshi [Osaka Univ., Graduate School of Science, Osaka (Japan)

2002-08-01

This report discusses the various problems which are encountered when a crystal spectrometer is used for the purpose of observing polarized x-ray lines. A polarimeter is proposed based on the novel idea of using two series of equivalent atomic planes in a single crystal. The present status of the astronomical x-ray detection techniques are described with emphasis on two dimensional detectors which are polarization sensitive. (author)

Photodiode read-out of the ALICE photon spectrometer $PbWO_{4}$ crystals

CERN Document Server

Man'ko, V I; Sibiryak, Yu; Volkov, M; Klovning, A; Maeland, O A; Odland, O H; Rongved, R; Skaali, B

1999-01-01

Proposal of abstract for LEB99, Snowmass, Colorado, 20-24 September 1999The PHOton Spectrometer of the ALICE experiment is an electromagnetic calorimeter of high granularity consisting of 17280 lead-tungstate (PWO) crystals of dimensions 22x22x180 mm3, read out by large-area PIN-diodes with very low-noise front-end electronics. The crystal assembly is operated at -25C to increase the PWO light yield. A 16.1x17.1 mm2 photodiode, optimized for the PWO emissio spectrum at 400-500 nm, has been developed. The 20x20 mm2 preamplifier PCB is attached to the back side of the diode ceramic frame. The charge sensitive preamplifier is built in discrete logic with two input JFETs for optimum matching with the ~150pF PIN-diode. A prototype shaper has been designed and built in discrete logic. For a detector matrix of 64 units the measured ENCs are between 450-550e at -25C. Beam tests demonstrate that the required energy resolution is reached.Summary:The PHOton Spectrometer of the ALICE experiment is an electromagnetic calo...

Post-flare coronal arches observed with the SMM/XRP flat crystal spectrometer

Science.gov (United States)

Hick, Paul; Svestka, Zdenek; Smith, Kermit L.; Strong, Keith T.

1987-01-01

Postflare coronal arch observations made with the SMM Flat Crystal Spectrometer on January 20-23, 1985 are discussed. Results suggest that the arch revival following the dynamic flare of 23:50 UT on January 1 was of the type noted on November 6-8 and June 4, 1980 by the SMM Hard X-ray Imaging Spectrometer (HXIS). Activity different from that of the HXIS observations was found starting at about 23 UT on January 22, with no trigger of the revival being identified, and with the activity being restricted to the coronal regions (without any related disturbance in the chromosphere). The development of the arch enhancement in the corona was shown to be slower than is expected for a flare-associated revival.

Resolution of VISION, a crystal-analyzer spectrometer

International Nuclear Information System (INIS)

Seeger, Philip A.; Daemen, Luke L.; Larese, John Z.

2009-01-01

We present both analytic and Monte Carlo calculations of the resolution of VISION, which is a crystal-analyzer spectrometer based on the TOSCA design. The analyzer crystal in VISION is configured to focus in time, radial, and transverse directions ('triple focused'). Previously published analytical results have two serious flaws in the handling of the statistics, which gave misleading results. First, Gaussian distributions were assumed for all resolution components, so that full-width-half-maximum could be used. Not only is this a very poor approximation for most terms, it is also completely unnecessary because standard deviations can be combined in quadrature for any shape distribution (except Lorentzian). The second flaw was the choice of variables that are not independent, so that significant correlations were ignored. An example of the effect of including correlations is that the mosaic spread of the analyzer crystals does not contribute to the resolution in first order. Monte Carlo simulation is not limited to first order, and we find a mild optimum value for mosaic spread. A complete set of six independent variables is: neutron emission time, incident flight-path variation (due to moderator tilt), sample thickness, mean path in the analyzer (due to multiple reflections), sample-to-detector radial distance, and detector thickness. We treat separately the resolution contributions from histogramming and rebinning during data acquisition and reduction, and describe a scheme for VISION that minimizes the effect on resolution. We compare the contributions of the six variables to the total resolution, both analytically and by Monte Carlo simulations of a complete VISION model using the Neutron Instrument Simulation Package (NISP).

A convenient tuning method for NMR/NQR spectrometers by using piezoelectric resonance from quartz crystals

International Nuclear Information System (INIS)

Yoon, J.G.; Yu, I.S.; Kwun, S.I.

1986-01-01

We observe that the cw or pulse NMR/NQR spectrometer tuning can be easily and conveniently adjusted by utilizing the piezoelectric resonance signal from quartz crystal sample. For an illustration some properties of the resonance signal are shown. (Author)

Optical Effects Accompanying the Dynamical Bragg Diffraction in Linear 1D Photonic Crystals Based on Porous Silicon

Directory of Open Access Journals (Sweden)

Anton Maydykovskiy

2014-10-01

Full Text Available We survey our recent results on the observation and studies of the effects accompanying the dynamical Bragg diffraction in one-dimensional photonic crystals (PhC. Contrary to the kinematic Bragg diffraction, the dynamical one considers a continuous interaction between the waves travelling within a spatially-periodic structure and is the most pronounced in the so called Laue geometry, leading to a number of exciting phenomena. In the described experiments, we study the PhC based on porous silicon or porous quartz, made by the electrochemical etching of crystalline silicon with the consequent thermal annealing. Importantly, these PhC are approximately hundreds of microns thick and contain a few hundreds of periods, so that the experiments in the Laue diffraction scheme are available. We discuss the effect of the temporal splitting of femtosecond laser pulses and show that the effect is quite sensitive to the polarization and the phase of a femtosecond laser pulse. We also show the experimental realization of the Pendular effect in porous quartz PhC and demonstrate the experimental conditions for the total spatial switching of the output radiation between the transmitted and diffracted directions. All described effects are of high interest for the control over the light propagation based on PhC structures.

A high resolution reflecting crystal spectrometer to measure 3 keV pionic hydrogen and deuterium X-rays

International Nuclear Information System (INIS)

Badertscher, A.; Bogdan, M.; Goudsmit, P.F.A.; Knecht, L.; Leisi, H.J.; Schroeder, H.C.; Sigg, D.; Zhao, Z.G.; Chatellard, D.; Egger, J.P.; Jeannet, E.; Aschenauer, E.C.; Gabathuler, K.; Simons, L.M.; Rusi El Hassani, A.J.

1993-01-01

A reflecting crystal spectrometer consisting of three cylindrically bent quartz (110) crystals is described. It was designed to measure the 3 keV K β X-rays from pionic hydrogen and deuterium. Charge coupled devices (CCDs) were used as X-ray detectors. Projecting the reflexes of all three crystals on one common focus, an instrumental energy resolution below 1 eV was obtained at an energy of 2.9 keV. (orig.)

Automatic control unit for A neutron diffraction crystal spectrometer

Energy Technology Data Exchange (ETDEWEB)

Adib, M.; Abbas, Y.; Mostafa, M.; Hamouda, I.

1982-01-01

An automatic transistorized unit has been designed and constructed to control the operation of the double axis crystal spectrometer installed in front of one of the horizontal channels of the ET-RR-1 reactor. The function of the automatic unit is to store the diffracted neutrons at a certain angle with respect to the direction of the incident neutron beam in a selected channel of a 1024-multichannel analyzer for a certain preadjusted time period. AT the end of this time period the unit rotates the spectrometer's arm to another angle, selects the next channel of the MCA and provides the measurement of the diffracted neutron for the same time period. Such a sequence is repeated automatically over all angles required for the neutron diffraction pattern of the sample under investigation. As a result, the stored information at the MCA provides the neutron diffraction pattern as a function of channel number, where each channel corresponds to a certain scattering angle. The stored distribution at MCA can be obtained through the analyzer read out unit. The designed automatic unit has the possibility of providing the neutron diffraction pattern using a 6-digit scaler and a printer.

Fusion engineering. Vol. 2

International Nuclear Information System (INIS)

Young, N.E.; Pinter, G.R.; Spinos, F.R.

1983-01-01

An x-ray crystal spectrometer is scheduled for installation in the Tokamak Fusion Test Reactor in 1984 coinciding with the TFTR deuterium operation phase. This spectrometer is designed to measure the spectra of hydrogen-like and helium-like impurities in the plasma. Ion temperatures electron temperatures, electron density and the distribution of impurity charge states are obtained from the x-ray detector count ratios. The velocity of the toroidal rotation of the plasma is also discerned using this device. The x-ray crystal spectrometer is based on the Bragg diffraction of x-rays from a curved crystal impinging on a multiwire proportional counter. Only those x-rays that satisfy the Bragg relationship (lambda =2d sin theta) will be diffracted and strike the proportional counter. This paper is limited to a discussion of the physical characteristics of the spectrometer and the methods devised to satisfy the operational aspects of such a device

Crystal-diffraction spectrometer of increased efficiency

International Nuclear Information System (INIS)

Saukov, A.I.; Gornitsyn, G.A.; Morozov, N.A.

1985-01-01

The geometry of the spectrometer is illustrated in this paper. An attempt is made to achieve optimal design of the spectrometer by finding the coefficient of reflection of the gamma radiation from the various Ge planes. In these experiments, the Du Mond design was used in the spectrometer. Illustrations are provided to explain dependence of the relative efficiency upon the energy of the gamma quanta

On the design of the NIF Continuum Spectrometer

Science.gov (United States)

Thorn, D. B.; MacPhee, A.; Ayers, J.; Galbraith, J.; Hardy, C. M.; Izumi, N.; Bradley, D. K.; Pickworth, L. A.; Bachmann, B.; Kozioziemski, B.; Landen, O.; Clark, D.; Schneider, M. B.; Hill, K. W.; Bitter, M.; Nagel, S.; Bell, P. M.; Person, S.; Khater, H. Y.; Smith, C.; Kilkenny, J.

2017-08-01

In inertial confinement fusion (ICF) experiments on the National Ignition Facility (NIF), measurements of average ion temperature using DT neutron time of flight broadening and of DD neutrons do not show the same apparent temperature. Some of this may be due to time and space dependent temperature profiles in the imploding capsule which are not taken into account in the analysis. As such, we are attempting to measure the electron temperature by recording the free-free electron-ion scattering-spectrum from the tail of the Maxwellian temperature distribution. This will be accomplished with the new NIF Continuum Spectrometer (ConSpec) which spans the x-ray range of 20 keV to 30 keV (where any opacity corrections from the remaining mass of the ablator shell are negligible) and will be sensitive to temperatures between ˜ 3 keV and 6 keV. The optical design of the ConSpec is designed to be adaptable to an x-ray streak camera to record time resolved free-free electron continuum spectra for direct measurement of the dT/dt evolution across the burn width of a DT plasma. The spectrometer is a conically bent Bragg crystal in a focusing geometry that allows for the dispersion plane to be perpendicular to the spectrometer axis. Additionally, to address the spatial temperature dependence, both time integrated and time resolved pinhole and penumbral imaging will be provided along the same polar angle. The optical and mechanical design of the instrument is presented along with estimates for the dispersion, solid angle, photometric sensitivity, and performance.

Fiber-MZI-based FBG sensor interrogation: comparative study with a CCD spectrometer.

Science.gov (United States)

Das, Bhargab; Chandra, Vikash

2016-10-10

We present an experimental comparative study of the two most commonly used fiber Bragg grating (FBG) sensor interrogation techniques: a charge-coupled device (CCD) spectrometer and a fiber Mach-Zehnder interferometer (F-MZI). Although the interferometric interrogation technique is historically known to offer the highest sensitivity measurements, very little information exists regarding how it compares with the current commercially available spectral-characteristics-based interrogation systems. It is experimentally established here that the performance of a modern-day CCD spectrometer interrogator is very close to a F-MZI interrogator with the capability of measuring Bragg wavelength shifts with sub-picometer-level accuracy. The results presented in this research study can further be used as a guideline for choosing between the two FBG sensor interrogator types for small-amplitude dynamic perturbation measurements down to nano-level strain.

Multilayer x-ray mirrors for the objective crystal spectrometer on the Spectrum Roentgen Gamma satellite

DEFF Research Database (Denmark)

Louis, E.; Spiller, E.; Abdali, S.

1995-01-01

with Kr+- and Ar+- ions of 300, 500, and 1000 eV. We examined the effect of different polishing parameters on the smoothening of the Co- and Ni-layers. The in-situ reflectivity of lambda equals 3.16 nm during deposition and the ex-situ grazing incidence reflectivity of Cu-K(alpha ) radiation (lambda...... multiplied by 6 cm2 Si (111) crystals for the Objective Crystal Spectrometer on the Russian Spectrum Rontgen Gamma satellite. The coatings on the flight crystals have a period Lambda of 3.95 plus or minus 0.02 nm and a reflectivity of more than 8% averaged over s- and p-polarization over the entire...

Influence of external actions on the Bragg-Laue diffraction of X-Rays

CERN Document Server

Gasparyan, L G; Grigoryan, A G

2000-01-01

The Bragg-Laue diffraction in finite size crystals under the influence of external actions (ultrasound, temperature gradient) is investigated experimentally. It is established that external actions ''charge for the worse'' the crystal quality, which leads to the broadening of the rocking curves and to the sharp decrease of intensity in the center of the reflection angular range.

Development of variable-magnification X-ray Bragg optics.

Science.gov (United States)

Hirano, Keiichi; Yamashita, Yoshiki; Takahashi, Yumiko; Sugiyama, Hiroshi

2015-07-01

A novel X-ray Bragg optics is proposed for variable-magnification of an X-ray beam. This X-ray Bragg optics is composed of two magnifiers in a crossed arrangement, and the magnification factor, M, is controlled through the azimuth angle of each magnifier. The basic properties of the X-ray optics such as the magnification factor, image transformation matrix and intrinsic acceptance angle are described based on the dynamical theory of X-ray diffraction. The feasibility of the variable-magnification X-ray Bragg optics was verified at the vertical-wiggler beamline BL-14B of the Photon Factory. For X-ray Bragg magnifiers, Si(220) crystals with an asymmetric angle of 14° were used. The magnification factor was calculated to be tunable between 0.1 and 10.0 at a wavelength of 0.112 nm. At various magnification factors (M ≥ 1.0), X-ray images of a nylon mesh were observed with an air-cooled X-ray CCD camera. Image deformation caused by the optics could be corrected by using a 2 × 2 transformation matrix and bilinear interpolation method. Not only absorption-contrast but also edge-contrast due to Fresnel diffraction was observed in the magnified images.

Chromatic X-ray magnifying method and apparatus by Bragg reflective planes on the surface of Abbe sphere

Science.gov (United States)

Thoe, Robert S.

1991-01-01

Method and apparatus for producing sharp, chromatic, magnified images of X-ray emitting objects, are provided. The apparatus, which constitutes an X-ray microscope or telescope, comprises a connected collection of Bragg reflecting planes, comprised of either a bent crystal or a synthetic multilayer structure, disposed on and adjacent to a locus determined by a spherical surface. The individual Bragg planes are spatially oriented to Bragg reflect radiation from the object location toward the image location. This is accomplished by making the Bragg planes spatially coincident with the surfaces of either a nested series of prolate ellipsoids of revolution, or a nested series of spheres. The spacing between the Bragg reflecting planes can be tailored to control the wavelengths and the amount of the X-radiation that is Bragg reflected to form the X-ray image.

An automatic control unit for A neutron diffraction crystal spectrometer

International Nuclear Information System (INIS)

Adib, M.; Abbas, Y.; Mostafa, M.; Hamouda, I.

1982-01-01

An automatic transistorized unit has been designed and constructed to control the operation of the double axis crystal spectrometer installed in front of one of the horizontal channels of the ET-RR-1 reactor. The function of the automatic unit is to store the diffracted neutrons at a certain angle with respect to the direction of the incident neutron beam in a selected channel of a 1024-multichannel analyzer for a certain preadjusted time period. AT the end of this time period the unit rotates the spectrometer's arm to another angle, selects the next channel of the MCA and provides the measurement of the diffracted neutron for the same time period. Such a sequence is repeated automatically over all angles required for the neutron diffraction pattern of the sample under investigation. As a result, the stored information at the MCA provides the neutron diffraction pattern as a function of channel number, where each channel corresponds to a certain scattering angle. The stored distribution at MCA can be obtained through the analyzer read out unit. The designed automatic unit has the possibility of providing the neutron diffraction pattern using a 6-digit scaler and a printer

Measuring conditions for second order X-ray Bragg-spectrometry

International Nuclear Information System (INIS)

Dellith, J; Scheffel, A; Wendt, M

2014-01-01

The KL 2,3 (α) 1,2 -lines of 19 K, the L 3 M 4,5 (α) 1,2 -lines of 48 Cd, and the M 5 N 6,7 (α) 1,2 -lines of 92 U are lines of comparable energy in the region of approximately 3 keV. In none of these cases were we able to resolve the three doublets when recording the spectra in first order Bragg spectrometry using a PET crystal as the dispersing element. For the purpose of enhancing the resolving power of the spectrometer, the three α spectra were recorded in second order reflection, thereby transferring the lines into another spectral region dominated by X-ray quanta of half the energy. In order to achieve high net peak intensities as well as a high peak-to-background ratio and, consequently, a high level of detection capability, the discriminator settings should be optimized quite carefully. In this manner, we were able to resolve the three α doublets and estimate α 2 /α 1 intensity ratios. Inexplicably, current monographs, e.g., by Goldstein et al, do not contain any indications about the rational use of high order spectrometry. Only a few rather old monographs contain some hints in this regard

William Henry Bragg, man and scientist, Nobel Laureate and First Professor of Physics, University of Adelaide 1886-1909.

Science.gov (United States)

Patterson, John; George, Robert

2018-03-01

In London, November 1915, a telegram was received at the home of William Henry Bragg from the secretary of the Academy of Science in Stockholm announcing the award of the Nobel Prize in Physics for "the analysis of crystal structures by means of X-rays". A second similar telegram was addressed to his 25 year old son William Lawrence Bragg (Jenkin, 2008). This article commemorates the centenary of that event and the unveiling of a bust of Sir William Bragg alongside that of his son, Sir Lawrence Bragg, on North Terrace in Adelaide where he spent 23 years of his early career. Copyright © 2018. Published by Elsevier Ltd.

Applications of Silicon-on-Insulator Photonic Crystal Structures in Miniature Spectrometer Designs

Science.gov (United States)

Gao, Boshen

Optical spectroscopy is one of the most important fundamental scientific techniques. It has been widely adopted in physics, chemistry, biology, medicine and many other research fields. However, the size and weight of a spectrometer as well as the difficulty to align and maintain it have long limited spectroscopy to be a laboratory-only procedure. With the recent advancement in semiconductor electronics and photonics, miniaturized spectrometers have been introduced to complete many tasks in daily life where mobility and portability are necessary. This thesis focuses on the study of several photonic crystal (PC) nano-structures potentially suitable for miniaturized on-chip spectrometer designs. Chapter 1 briefly introduces the concept of PCs and their band structures. By analyzing the band structure, the origin of the superprism effect is explained. Defect-based PC nano-cavities are also discussed, as well as a type of coupled cavity waveguides (CCW) composed of PC nano-cavities. Chapter 2 is devoted to the optimization of a flat-band superprism structure for spectroscopy application using numerical simulations. Chapter 3 reports a fabricated broad-band superprism and the experimental characterization of its wavelength resolving performance. In chapter 4, the idea of composing a miniature spectrometer based on a single tunable PC nano-cavity is proposed. The rest of this chapter discusses the experimental study of this design. Chapter 5 examines the slow-light performance of a CCW and discusses its potential application in slow-light interferometry. Chapter 6 serves as a conclusion of this thesis and proposes directions for possible future work to follow up.

Soft X-ray Calibration of the Co/C Multilayer Mirrors for the Objective Crystal Spectrometer on the Spectrum Röntgen-Gamma Satellite

DEFF Research Database (Denmark)

Abdali, Salim; Tarrio, C.; Christensen, Finn Erland

1996-01-01

The objective crystal spectrometer (OXS) on the forthcoming Spectrum-Roentgen-Gamma satellite is designed to carry three kinds of crystals: LiF(220), Si(111) and RAP(001), placed in front of the SODART telescope. Thirty six super polished (RMS roughness

Bragg Curve Spectroscopy

International Nuclear Information System (INIS)

Gruhn, C.R.

1981-05-01

An alternative utilization is presented for the gaseous ionization chamber in the detection of energetic heavy ions, which is called Bragg Curve Spectroscopy (BCS). Conceptually, BCS involves using the maximum data available from the Bragg curve of the stopping heavy ion (HI) for purposes of identifying the particle and measuring its energy. A detector has been designed that measures the Bragg curve with high precision. From the Bragg curve the range from the length of the track, the total energy from the integral of the specific ionization over the track, the dE/dx from the specific ionization at the beginning of the track, and the Bragg peak from the maximum of the specific ionization of the HI are determined. This last signal measures the atomic number, Z, of the HI unambiguously

Parametric x-ray FEL operating with external Bragg reflectors

International Nuclear Information System (INIS)

Baryshevsky, V.G.; Batrakov, K.G.; Dubovskaya, I.Ya.

1995-01-01

In the crystal X-ray FELs using channeling and parametric quasi-Cherenkov mechanisms of spontaneous radiation were considered as versions of FEL allowing, in principle, to obtain coherent X-ray source. In this case a crystal is both radiator and resonator for X-rays emitted by a particle beam passing through crystal. However, it is well-known that a beam current density required for lasing is extremely high in X-ray spectral range for any radiation mechanisms and it is very important to find a way to lower its magnitude. The application of three-dimensional distributed feedback formed by dynamical diffraction of emitted photons permitted to reduce starting beam current density 10 2 -10 4 times up to 10 9 . One of ways to lower the starting current is the formation of multi-wave distributed feedback the another one is the application of external reflectors. The thing is that lasing regime was shown to be produced at frequencies in the vicinity of degeneration point for roots of dispersion equation describing radiation modes excited in an active medium (crystal plus particle beam). Unfortunately, in case of parametric quasi-Cherenkov FEL this region coincides with the region of strong self-absorption of radiation inside a crystal. That fact, obviously, increases the starting beam current. In this report we have shown that the application of external Bragg reflectors gives the possibility to lower radiation self-absorption inside a crystal by modifying radiation modes excited in the active medium under consideration. The corresponding dispersion equation and the expression for excited modes are derived. The generation equation determining starting conditions for lasing is obtained. Using these expressions we have shown that the application of external Bragg reflectors permits to reduce starting beam current density more than 10 times

Crystal clear the autobiographies of Sir Lawrence and Lady Bragg

CERN Document Server

Thomson, Patience

2015-01-01

The main body of this book contains the hitherto unpublished autobiographies of both William Lawrence Bragg, an innovative scientist who won the Nobel Prize for Physics in 1915, and his wife, Alice, a Mayor of Cambridge and National Chairman of Marriage Guidance. Their autobiographies give unusual insights into the lives and times of two distinguished people and the real personalities behind their public appearance.

Realisation of a novel crystal bender for a fast double crystal monochromator

CERN Document Server

Zaeper, R; Wollmann, R; Luetzenkirchen-Hecht, D; Frahm, R

2001-01-01

A novel crystal bender for an X-ray undulator beamline as part of a fast double crystal monochromator development for full EXAFS energy range was characterized. Rocking curves of the monochromator crystal system were recorded under different heat loads and bending forces of the indirectly cooled first Si(1 1 1) crystal. The monochromator development implements new piezo-driven tilt tables with wide angular range to adjust the crystals' Bragg angles and a high pressure actuated bender mechanism for the first crystal.

Investigation of multiple Bragg reflections at a constant neutron wavelength and their possible separation

International Nuclear Information System (INIS)

Mikula, P; Vrána, M; Šaroun, J; Em, V; Seong, B S

2012-01-01

Multiple Bragg reflections (MBR) realized in one bent-perfect crystal (BPC) slab by sets of different lattice planes behave differently in comparison to the case of perfect nondeformed or mosaic crystal. Individual sets of lattice planes are mutually in dispersive diffraction geometry and the kinematical approach can be applied on this MBR process. It has been found that contrary to the perfect nondeformed or mosaic crystal, individual reflections participating in the MBR process can be spatially separated.

Diffuse X-ray scattering near the Bragg reflection of P-doped Czochralski silicon

International Nuclear Information System (INIS)

Stojanoff, V.; Pimentel, C.A.F.

1983-01-01

Bragg line profile and high resolution diffuse X-ray scattering measurements around the (400) reciprocal lattice point of dislocation-free Czochralski Si single crystals P-doped have shown defects of interstitial nature with typical size about 1000 A. (Author) [pt

Clear as Crystal: The Story of the Braggs--How X-Ray Crystallography Has Contributed to Science

Science.gov (United States)

George, Robert; Patterson, John

2014-01-01

Here is a brief history of the work of two of Australia's most famous scientists, Sir William Bragg and his son Sir Lawrence Bragg. Jointly awarded the Nobel Prize in 1915 for their groundbreaking research into the use of X-rays to study the chemical structure and function of molecules, they have contributed to our heritage and to science at an…

Characterization of Crystallographic Structures Using Bragg-Edge Neutron Imaging at the Spallation Neutron Source

Directory of Open Access Journals (Sweden)

Gian Song

2017-12-01

Full Text Available Over the past decade, wavelength-dependent neutron radiography, also known as Bragg-edge imaging, has been employed as a non-destructive bulk characterization method due to its sensitivity to coherent elastic neutron scattering that is associated with crystalline structures. Several analysis approaches have been developed to quantitatively determine crystalline orientation, lattice strain, and phase distribution. In this study, we report a systematic investigation of the crystal structures of metallic materials (such as selected textureless powder samples and additively manufactured (AM Inconel 718 samples, using Bragg-edge imaging at the Oak Ridge National Laboratory (ORNL Spallation Neutron Source (SNS. Firstly, we have implemented a phenomenological Gaussian-based fitting in a Python-based computer called iBeatles. Secondly, we have developed a model-based approach to analyze Bragg-edge transmission spectra, which allows quantitative determination of the crystallographic attributes. Moreover, neutron diffraction measurements were carried out to validate the Bragg-edge analytical methods. These results demonstrate that the microstructural complexity (in this case, texture plays a key role in determining the crystallographic parameters (lattice constant or interplanar spacing, which implies that the Bragg-edge image analysis methods must be carefully selected based on the material structures.

Wake monochromator in asymmetric and symmetric Bragg and Laue geometry for self-seeding the European X-ray FEL

International Nuclear Information System (INIS)

Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni; Serkez, Svitozar; Tolkiehn, Martin

2013-01-01

We discuss the use of self-seeding schemes with wake monochromators to produce TW power, fully coherent pulses for applications at the dedicated bio-imaging beamline at the European X-ray FEL, a concept for an upgrade of the facility beyond the baseline previously proposed by the authors. We exploit the asymmetric and symmetric Bragg and Laue reflections (sigma polarization) in diamond crystal. Optimization of the bio-imaging beamline is performed with extensive start-to-end simulations, which also take into account effects such as the spatio-temporal coupling caused by the wake monochromator. The spatial shift is maximal in the range for small Bragg angles. A geometry with Bragg angles close to π/2 would be a more advantageous option from this viewpoint, albeit with decrease of the spectral tunability. We show that it will be possible to cover the photon energy range from 3 keV to 13 keV by using four different planes of the same crystal with one rotational degree of freedom.

Wake monochromator in asymmetric and symmetric Bragg and Laue geometry for self-seeding the European X-ray FEL

Energy Technology Data Exchange (ETDEWEB)

Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni; Serkez, Svitozar; Tolkiehn, Martin [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2013-01-15

We discuss the use of self-seeding schemes with wake monochromators to produce TW power, fully coherent pulses for applications at the dedicated bio-imaging beamline at the European X-ray FEL, a concept for an upgrade of the facility beyond the baseline previously proposed by the authors. We exploit the asymmetric and symmetric Bragg and Laue reflections (sigma polarization) in diamond crystal. Optimization of the bio-imaging beamline is performed with extensive start-to-end simulations, which also take into account effects such as the spatio-temporal coupling caused by the wake monochromator. The spatial shift is maximal in the range for small Bragg angles. A geometry with Bragg angles close to {pi}/2 would be a more advantageous option from this viewpoint, albeit with decrease of the spectral tunability. We show that it will be possible to cover the photon energy range from 3 keV to 13 keV by using four different planes of the same crystal with one rotational degree of freedom.

Vibrating crystals as possible neutron monochromators

International Nuclear Information System (INIS)

Stoica, A.D.; Popovici, M.

1983-09-01

The Bragg reflection of neutrons of vibratinq perfect crystals is considered. The additional possibilities offered by the Doppler effect for shaping neutron beams in the k-space are discussed. A simple model for computing the vibrating crystal reflectivity is proposed. (author)

[A high resolution projection electron spectrometers]: Final report 1978-1987

International Nuclear Information System (INIS)

1988-01-01

The main emphasis of the work has been to study inner shell ionization processes. The signatures have been K x-rays or K Auger transitions. We have worked with semiconductor or Bragg x-ray spectrometers. Toward the end of the contract we concentrated on projectile electron spectroscopy. These topics and other atomic physics projects are described briefly in this progress report

RITA: The reinvented triple axis spectrometer

Energy Technology Data Exchange (ETDEWEB)

Mason, T.E. [Toronto Univ., ON (Canada). Dept. of Physics; Clausen, K.N.; Aeppli, G.; McMorrow, D.R.; Kjems, J.K. [Risoe National Lab., Roskilde (Denmark)

1995-11-01

Risoe National Laboratory was reported to be in the process of developing a new spectrometer design, RITA, based on the triple axis design. The spectrometer will attempt to incorporate more recent innovations such as multilayer supermirrors and microstrip proportional counters into a rethinking of the triple-axis spectrometer. By optimizing the beam optics, using supermirrors and extending the analyser to map regions of (Q, {omega}) space using an array of independently controllable pyrolytic graphite crystals focussed on an area detector, it was hoped that the efficiency of single-crystal inelastic experiments could be increased by as much as a factor of 20. 7 figs., 20 refs.

Dynamical neutron diffraction by curved crystals in the Laue geometry

International Nuclear Information System (INIS)

Albertini, G.; Melone, S.; Lagomarsino, S.; Mazkedian, S.; Puliti, P.; Rustichelli, F.

1977-01-01

The Taupin dynamical theory of X-ray diffraction by deformed crystals which was previously extended to the neutron diffraction by curved crystals in the Bragg geometry, is applied to calculate neutron diffraction patterns in the Laue geometry. The theoretical results are compared with experimental data on curved silicon crystals. The agreement is quite satisfactory. In the second part a simple model recently presented to describe neutron diffraction properties in the Bragg case is extended to the Laue case. The predictions of such a model are in satisfactory agreement with the rigorous theory and the experimental results. (author)

Broadband sound blocking in phononic crystals with rotationally symmetric inclusions.

Science.gov (United States)

Lee, Joong Seok; Yoo, Sungmin; Ahn, Young Kwan; Kim, Yoon Young

2015-09-01

This paper investigates the feasibility of broadband sound blocking with rotationally symmetric extensible inclusions introduced in phononic crystals. By varying the size of four equally shaped inclusions gradually, the phononic crystal experiences remarkable changes in its band-stop properties, such as shifting/widening of multiple Bragg bandgaps and evolution to resonance gaps. Necessary extensions of the inclusions to block sound effectively can be determined for given incident frequencies by evaluating power transmission characteristics. By arraying finite dissimilar unit cells, the resulting phononic crystal exhibits broadband sound blocking from combinational effects of multiple Bragg scattering and local resonances even with small-numbered cells.

Wavelength calibration of x-ray imaging crystal spectrometer on Joint Texas Experimental Tokamak

International Nuclear Information System (INIS)

Yan, W.; Chen, Z. Y.; Jin, W.; Huang, D. W.; Ding, Y. H.; Li, J. C.; Zhang, X. Q.; Zhuang, G.; Lee, S. G.; Shi, Y. J.

2014-01-01

The wavelength calibration of x-ray imaging crystal spectrometer is a key issue for the measurements of plasma rotation. For the lack of available standard radiation source near 3.95 Å and there is no other diagnostics to measure the core rotation for inter-calibration, an indirect method by using tokamak plasma itself has been applied on joint Texas experimental tokamak. It is found that the core toroidal rotation velocity is not zero during locked mode phase. This is consistent with the observation of small oscillations on soft x-ray signals and electron cyclotron emission during locked-mode phase

Bragg Curve, Biological Bragg Curve and Biological Issues in Space Radiation Protection with Shielding

Science.gov (United States)

Honglu, Wu; Cucinotta, F.A.; Durante, M.; Lin, Z.; Rusek, A.

2006-01-01

The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the major protection to astronauts from harmful exposure. Unlike low-LET gamma or X-rays, the presence of shielding does not always reduce the radiation risks for energetic charged particle exposure. Since the dose delivered by the charged particle increases sharply as the particle approaches the end of its range, a position known as the Bragg peak, the Bragg curve does not necessarily represent the biological damage along the particle traversal since biological effects are influenced by the track structure of both primary and secondary particles. Therefore, the biological Bragg curve is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. To achieve a Bragg curve distribution, we exposed cells to energetic heavy ions with the beam geometry parallel to a monolayer of fibroblasts. Qualitative analyses of gamma-H2AX fluorescence, a known marker of DSBs, indicated increased clustering of DNA damage before the Bragg peak, enhanced homogenous distribution at the peak, and provided visual evidence of high linear energy transfer (LET) particle traversal of cells beyond the Bragg peak. A quantitative biological response curve generated for micronuclei (MN) induction across the Bragg curve did not reveal an increased yield of MN at the location of the Bragg peak. However, the ratio of mono-to bi-nucleated cells, which indicates inhibition in cell progression, increased at the Bragg peak location. These results, along with other biological concerns, show that space radiation protection with shielding can be a complicated issue.

Self-consistent electrodynamic scattering in the symmetric Bragg case

International Nuclear Information System (INIS)

Campos, H.S.

1988-01-01

We have analyzed the symmetric Bragg case, introducing a model of self consistent scattering for two elliptically polarized beams. The crystal is taken as a set of mathematical planes, each of them defined by a surface density of dipoles. We have considered the mesofield and the epifield differently from that of the Ewald's theory and, we assumed a plane of dipoles and the associated fields as a self consistent scattering unit. The exact analytical treatment when applied to any two neighbouring planes, results in a general and self consistent Bragg's equation, in terms of the amplitude and phase variations. The generalized solution for the set of N planes was obtained after introducing an absorption factor in the incident radiation, in two ways: (i) the analytical one, through a rule of field similarity, which says that the incidence occurs in both faces of the all crystal planes and also, through a matricial development with the Chebyshev polynomials; (ii) using the numerical solution we calculated, iteratively, the reflectivity, the reflection phase, the transmissivity, the transmission phase and the energy. The results are showed through reflection and transmission curves, which are characteristics as from kinematical as dynamical theories. The conservation of the energy results from the Ewald's self consistency principle is used. In the absorption case, the results show that it is not the only cause for the asymmetric form in the reflection curves. The model contains basic elements for a unified, microscope, self consistent, vectorial and exact formulation for interpretating the X ray diffraction in perfect crystals. (author)

Synchrotron radiation focusing by a Bragg--Fresnel lens

International Nuclear Information System (INIS)

Aristov, V.V.; Basov, Y.A.; Snigirev, A.A.

1989-01-01

Since the discovery of x rays and until the present time the possibilities of their controlling and focusing have been widely discussed. In the hard spectrum region (λ∼1 A) the main focusing schemes are the following: geometrical focusing based on incoherent interaction of wave packets reflected by different regions of bending crystals and coherent (dynamic) focusing performed at the cost of the effect of refraction index angular dispersion near the exact Bragg angle value -θ B . A main disadvantage of geometrical focusing is low spatial resolution (∼0.1 mm) and temperature stability. In the case of coherent focusing a main disadvantage is a narrow angular aperture (∼10 sec. of arc) at spatial resolution (∼1--10 μm). Recently, advances in the development of diffraction physics and microstructuring technology open up possibilities for fabricating effective focusing x-ray optical elements---Bragg--Fresnel lenses (BFL)---with high spatial resolution (∼0.1 μm) at a wide angular aperture and high temperature stability. The present paper describes the main principles of Bragg--Fresnel optics (BFO). It presents the results on the synchrotron experiment and on observation of focusing. In this work the peculiarities of BFL diffraction contrast formation are investigated and image transmission using a BFL is performed. Possibilities of developing x-ray optical schemes of ultrahigh resolution on the basis of BFL elements are also discussed

Liquid filling of photonic crystal fibres for grating writing

DEFF Research Database (Denmark)

Sørensen, Henrik Rokkjær; Canning, John; Lægsgaard, Jesper

2007-01-01

liquid filling of photonic crystal fibres reduces the scattering from air–glass interfaces during Bragg grating writing in many layered photonic crystal fibres. Within experimental uncertainty, the grating index modulation of a grating written in germanium-doped photonic crystal fibre with 10 rings...

Fabrication of Au- and Ag–SiO{sub 2} inverse opals having both localized surface plasmon resonance and Bragg diffraction

Energy Technology Data Exchange (ETDEWEB)

Erola, Markus O.A.; Philip, Anish; Ahmed, Tanzir; Suvanto, Sari; Pakkanen, Tuula T., E-mail: Tuula.Pakkanen@uef.fi

2015-10-15

The inverse opal films of SiO{sub 2} containing metal nanoparticles can have both the localized surface plasmon resonance (LSPR) of metal nanoparticles and the Bragg diffraction of inverse opal crystals of SiO{sub 2}, which are very useful properties for applications, such as tunable photonic structures, catalysts and sensors. However, effective processes for fabrication of these films from colloidal particles have rarely been reported. In our study, two methods for preparation of inverse opal films of SiO{sub 2} with three different crystal sizes and containing gold or silver nanoparticles (NPs) via self-assembly using electrostatic interactions and capillary forces are reported. The Bragg diffraction of inverse opal films of SiO{sub 2} in the presence and absence of the template was measured and predicted on the basis of with UV–vis spectroscopy and scanning electron microscopy. The preparation methods used provided good-quality inverse opal SiO{sub 2} films containing highly dispersed, plasmonic AuNPs or AgNPs and having both Bragg diffractions and LSPRs. - Graphical abstract: For syntheses of SiO{sub 2} inverse opals containing Au/Ag nanoparticles two approaches and three template sizes were employed. Self-assembly of template molecules and metal nanoparticles occurred using electrostatic interactions and capillary forces. Both the Bragg diffraction of the photonic crystal and the localized surface plasmon resonance of Au/Ag nanoparticles were detected. - Highlights: • Fabrication methods of silica inverse opals containing metal nanoparticles studied. • Three template sizes used to produce SiO{sub 2} inverse opals with Au/Ag nanoparticles. • PS templates with Au nanoparticles adsorbed used in formation of inverse opals. • Ag particles infiltrated in inverse opals with capillary and electrostatic forces. • Bragg diffractions of IOs and surface plasmon resonances of nanoparticles observed.

Monolithic all-PM femtosecond Yb-fiber laser stabilized with a narrow-band fiber Bragg grating and pulse-compressed in a hollow-core photonic crystal fiber

DEFF Research Database (Denmark)

Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

2008-01-01

. The laser output is compressed in a spliced-on hollow-core PM photonic crystal fiber, thus providing direct end-of-the-fiber delivery of pulses of around 370 fs duration and 4 nJ energy with high mode quality. Tuning the pump power of the end amplifier of the laser allows for the control of output pulse......We report on an environmentally stable self-starting monolithic (i.e. without any free-space coupling) all-polarization-maintaining (PM) femtosecond Yb-fiber laser, stabilized against Q-switching by a narrow-band fiber Bragg grating and modelocked using a semiconductor saturable absorber mirror...

Evaluation of HOPG mounting possibilities for multiplexing spectrometers

Energy Technology Data Exchange (ETDEWEB)

Groitl, Felix, E-mail: felix.groitl@psi.ch [Laboratory for Quantum Magnetism, École Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland); Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen (Switzerland); Bartkowiak, Marek [Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, 5232 Villigen (Switzerland); Bergmann, Ryan M. [Division Large Research Facilities, Paul Scherrer Institut, 5232 Villigen (Switzerland); Birk, Jonas Okkels [Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen (Switzerland); Department of Physics, Technical University of Denmark (DTU), 2800 Kgs. Lyngby (Denmark); Markó, Márton [Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen (Switzerland); Wigner Research Centre for Physics, Neutron Spectroscopy Department, 1525 Budapest (Hungary); Bollhalder, Alex; Graf, Dieter [Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, 5232 Villigen (Switzerland); Niedermayer, Christof [Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen (Switzerland); Rüegg, Christian [Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen (Switzerland); Department of Quantum Matter Physics, University of Geneva, 1211 Geneva (Switzerland); Rønnow, Henrik M. [Laboratory for Quantum Magnetism, École Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland); Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen (Denmark)

2017-06-21

Four different methods for mounting HOPG analyzer crystals on Si holders have been evaluated in the design process of the new multiplexing spectrometer CAMEA. Contrary to neutron optics used in standard spectrometers, the new instrument concept employs a series of analyzer segments behind each other where the neutrons have to pass through the bonding compound of the different analyzer crystals. The different methods, namely screws, shellac, indium soldering and clips, have been evaluated with regards to background, transmission, cooling, activation and handling. The results presented here will give valuable input for future CAMEA-type spectrometers currently planned and designed at various neutron sources.

Evaluation of HOPG mounting possibilities for multiplexing spectrometers

International Nuclear Information System (INIS)

Groitl, Felix; Bartkowiak, Marek; Bergmann, Ryan M.; Birk, Jonas Okkels; Markó, Márton; Bollhalder, Alex; Graf, Dieter; Niedermayer, Christof; Rüegg, Christian; Rønnow, Henrik M.

2017-01-01

Four different methods for mounting HOPG analyzer crystals on Si holders have been evaluated in the design process of the new multiplexing spectrometer CAMEA. Contrary to neutron optics used in standard spectrometers, the new instrument concept employs a series of analyzer segments behind each other where the neutrons have to pass through the bonding compound of the different analyzer crystals. The different methods, namely screws, shellac, indium soldering and clips, have been evaluated with regards to background, transmission, cooling, activation and handling. The results presented here will give valuable input for future CAMEA-type spectrometers currently planned and designed at various neutron sources.

Time-dependent Bragg diffraction by multilayer gratings

International Nuclear Information System (INIS)

André, Jean-Michel; Jonnard, Philippe

2016-01-01

Time-dependent Bragg diffraction by multilayer gratings working by reflection or by transmission is investigated. The study is performed by generalizing the time-dependent coupled-wave theory previously developed for one-dimensional photonic crystals (André J-M and Jonnard P 2015 J. Opt. 17 085609) and also by extending the Takagi–Taupin approach of the dynamical theory of diffraction. The indicial response is calculated. It presents a time delay with a transient time that is a function of the extinction length for reflection geometry and of the extinction length combined with the thickness of the grating for transmission geometry. (paper)

Proton beam spatial distribution and Bragg peak imaging by photoluminescence of color centers in lithium fluoride crystals at the TOP-IMPLART linear accelerator

Science.gov (United States)

Piccinini, M.; Ronsivalle, C.; Ampollini, A.; Bazzano, G.; Picardi, L.; Nenzi, P.; Trinca, E.; Vadrucci, M.; Bonfigli, F.; Nichelatti, E.; Vincenti, M. A.; Montereali, R. M.

2017-11-01

Solid-state radiation detectors based on the photoluminescence of stable point defects in lithium fluoride crystals have been used for advanced diagnostics during the commissioning of the segment up to 27 MeV of the TOP-IMPLART proton linear accelerator for proton therapy applications, under development at ENEA C.R. Frascati, Italy. The LiF detectors high intrinsic spatial resolution and wide dynamic range allow obtaining two-dimensional images of the beam transverse intensity distribution and also identifying the Bragg peak position with micrometric precision by using a conventional optical fluorescence microscope. Results of the proton beam characterization, among which, the estimation of beam energy components and dynamics, are reported and discussed for different operating conditions of the accelerator.

Ring-patterned plasmonic photonic crystal thermal light source for miniaturized near-infrared spectrometers

Science.gov (United States)

Labib, Shady R.; Elsayed, Ahmed A.; Sabry, Yasser M.; Khalil, Diaa

2018-02-01

There is a growing number of spectroscopy applications in the near-infrared (NIR) range including gas sensing, food analysis, pharmaceutical and industrial applications that requires highly efficient, more compact and low-cost miniaturized spectrometers. One of the key components for such systems is the wideband light source that can be fabricated using Silicon technology and hence integrated with other components on the same chip. In this work, we report a ring-patterned plasmonic photonic crystal (PC) thermal light source for miniaturized near-infrared spectrometers. The design is based on silicon and tuned to achieve wavelength selectivity in the emitted spectrum. The design is optimized by using Rigorous Coupled-Wave Analysis (RCWA) simulation, which is used to compute the power reflectance and transmittance that are used to predict the emissivity of the structure. The design consists of a PC of silicon rings coated with platinum. The period of the structure is about 2 μm and the silicon is highly-doped with n-type doping level in the order of 1019-1020 cm-3 to enhance the free-carrier absorption. The ring etching depth, diameter and shell thickness are optimized to increase its emissivity within a specific wavelength range of interest. The simulation results show an emissivity exceeding 0.9 in the NIR range up to 2.5 μm, while the emissivity is decreased significantly for longer wavelengths suppressing the emission out of the range of interest, and hence increasing the efficiency for the source. The reported results open the door for black body radiation engineering in integrated silicon sources for spectrometer miniaturization.

Bragg grating rogue wave

Energy Technology Data Exchange (ETDEWEB)

Degasperis, Antonio [Dipartimento di Fisica, “Sapienza” Università di Roma, P.le A. Moro 2, 00185 Roma (Italy); Wabnitz, Stefan, E-mail: stefan.wabnitz@unibs.it [Dipartimento di Ingegneria dell' Informazione, Università degli Studi di Brescia and INO-CNR, via Branze 38, 25123 Brescia (Italy); Aceves, Alejandro B. [Southern Methodist University, Dallas (United States)

2015-06-12

We derive the rogue wave solution of the classical massive Thirring model, that describes nonlinear optical pulse propagation in Bragg gratings. Combining electromagnetically induced transparency with Bragg scattering four-wave mixing may lead to extreme waves at extremely low powers.

The construction of a high resolution crystal backscattering spectrometer HERMES I

Energy Technology Data Exchange (ETDEWEB)

Larese, J.Z.

1998-11-01

There is a need in the United States for a state-of-the-art, cold-neutron, crystal backscattering spectrometer (CBS) designed to investigate the structure and dynamics of condensed matter systems by the simultaneous utilization of long wavelength elastic diffraction and high-energy-resolution inelastic scattering. Cold neutron spectroscopy with CBS-type instruments has already made many important contributions to the study of atomic and molecular diffusion in biomaterials, polymers, semiconductors, liquid crystals, superionic conductors and the like. Such instruments have also been invaluable for ultra high resolution investigations of the low-lying quantum tunneling processes that provide direct insight into the dynamical response of solids at the lowest energies. Until relatively recently, however, all such instruments were located at steady-state reactors. This proposal describes HERMES I (High Energy Resolution Machines I) a CBS intended for installation at the LANSCE pulsed neutron facility of Los Alamos National Laboratory. As explained in detail in the main text, the authors propose to construct an updated, high-performance CBS which incorporates neutron techniques developed during the decade since IRIS was built, i.e., improved supermirror technology, a larger area crystal analyzer and high efficiency wire gas detectors. The instrument is designed in such a way as to be readily adaptable to future upgrades. HERMES I, they believe, will substantially expand the range and flexibility of neutron investigations in the United States and open new and potentially fruitful directions for condensed matter exploration. This document describes a implementation plan with a direct cost range between $4.5 to 5.6 M and scheduled duration of 39--45 months for identified alternatives.

The construction of a high resolution crystal backscattering spectrometer HERMES I

International Nuclear Information System (INIS)

Larese, J.Z.

1998-01-01

There is a need in the United States for a state-of-the-art, cold-neutron, crystal backscattering spectrometer (CBS) designed to investigate the structure and dynamics of condensed matter systems by the simultaneous utilization of long wavelength elastic diffraction and high-energy-resolution inelastic scattering. Cold neutron spectroscopy with CBS-type instruments has already made many important contributions to the study of atomic and molecular diffusion in biomaterials, polymers, semiconductors, liquid crystals, superionic conductors and the like. Such instruments have also been invaluable for ultra high resolution investigations of the low-lying quantum tunneling processes that provide direct insight into the dynamical response of solids at the lowest energies. Until relatively recently, however, all such instruments were located at steady-state reactors. This proposal describes HERMES I (High Energy Resolution Machines I) a CBS intended for installation at the LANSCE pulsed neutron facility of Los Alamos National Laboratory. As explained in detail in the main text, the authors propose to construct an updated, high-performance CBS which incorporates neutron techniques developed during the decade since IRIS was built, i.e., improved supermirror technology, a larger area crystal analyzer and high efficiency wire gas detectors. The instrument is designed in such a way as to be readily adaptable to future upgrades. HERMES I, they believe, will substantially expand the range and flexibility of neutron investigations in the United States and open new and potentially fruitful directions for condensed matter exploration. This document describes a implementation plan with a direct cost range between $4.5 to 5.6 M and scheduled duration of 39--45 months for identified alternatives

Synchrotron X-ray diffraction using triple-axis spectrometry

International Nuclear Information System (INIS)

Als-Nielsen, J.

1980-12-01

High resolution X-ray diffraction studies of (i) monolayers of the noble gases Kr and Ar physiosorbed on graphite (ii) smectic A fluctuations in the nematic and the smectic A phases of liquid crystals are described. The apparatus used is a triple axis spectrometer situated at the storage ring DORIS at Hasylab, DESY, Hamburg. A monochromatic, well collimated beam is extracted from the synchrotron radiation spectrum by Bragg reflection from perfect Si or Ge crystals. The direction of the beam scattered from the sample is determined by Bragg reflection from a perfect Si or Ge crystal. High intensities even with resolution extending beyond the wavelength of visible light can be obtained. (Auth.)

Observation of sagittal X-ray diffraction by surface acoustic waves in Bragg geometry.

Science.gov (United States)

Vadilonga, Simone; Zizak, Ivo; Roshchupkin, Dmitry; Evgenii, Emelin; Petsiuk, Andrei; Leitenberger, Wolfram; Erko, Alexei

2017-04-01

X-ray Bragg diffraction in sagittal geometry on a Y-cut langasite crystal (La 3 Ga 5 SiO 14 ) modulated by Λ = 3 µm Rayleigh surface acoustic waves was studied at the BESSY II synchrotron radiation facility. Owing to the crystal lattice modulation by the surface acoustic wave diffraction, satellites appear. Their intensity and angular separation depend on the amplitude and wavelength of the ultrasonic superlattice. Experimental results are compared with the corresponding theoretical model that exploits the kinematical diffraction theory. This experiment shows that the propagation of the surface acoustic waves creates a dynamical diffraction grating on the crystal surface, and this can be used for space-time modulation of an X-ray beam.

Switchable Bragg gratings

DEFF Research Database (Denmark)

Marckmann, Carl Johan

2003-01-01

Research Center (MIC) at the Technical University of Denmark. The Bragg gratings were fabricated at COM using UV irradiation of the planar waveguides using the phase mask method. The induction of a frozen-in DC electric field into the samples was performed by thermal poling of the Bragg gratings...... layers, it becam possible to investigate the symmetry properties of the third-order nonlinearities. Contrary to the expectations for an amorphous material, the measurements indicated an almost polarization independent third-order nonlinearity - the most probable explanation being electrostriction......The subject of this ph.d. thesis was the development of an electrically switchable Bragg grating made in an optical waveguide using thermal poling to be applied within optical telecommunication systems. The planar waveguides used in this thesis were fabricated at the Micro- and Nanotechnology...

Fabrication et applications des reseaux de Bragg ultra-longs

Science.gov (United States)

Gagne, Mathieu

quality ultra long fiber Bragg gratings. High quality theory matching ultra long fiber Bragg gratings up to 1 meter long are obtained for the first time. The possibility of fabricating high quality ultra long fiber Bragg grating of more than 10 cm (approximately the maximal phase mask length) opens a variety of new applications otherwise impossible with short fiber Bragg grating technology. Ultra long fiber Bragg gratings have unique characteristics such as high reflectivity, high dispersion and ultra narrow bandwidth. Those characteristics can be used to do advanced signal processing, non linear propagation experiments, distributed feedback fiber lasers and dispersion compensator for telecommunication or optical tomography. The second objective of this project is to use these ultra-long fiber Bragg gratings as an optical cavity for fiber lasers. Alot of research in the past years have been concentrated on those lasers, particularly on distributed feedback fiber lasers where the gratings spans all the gain media. A new random fiber laser configuration is presented. It is based on passive or active insertion of phase shifts along the Bragg grating to obtained a phenomenon called light localization which is the optical equivalent of Anderson localization. This complex wave phenomenon has the unique property to mimic the reflection of a uniform photonic crystal with the random diffusion of light among the elements of a random media. Being commonly obtained in fine powders which must respect a certain set of rules, the realization of 1D structures is vastly simplified in optical fibers. Two random fiber laser schemes based on light localization, one using erbium dopant and the other one Raman scattering, are demonstrated for the first time and compared to traditional distributed feedback fiber lasers.

Bragg gratings in Topas

DEFF Research Database (Denmark)

Zhang, C.; Webb, D.J.; Kalli, K.

We report for the first time fibre Bragg grating inscription in microstructured optical fibre fabricated from Topas® cyclic olefin copolymer. The temperature sensitivity of the grating was studied revealing a positive Bragg wavelength shift of approximately 0.8 nmK-1,the largest sensitivity yet...

Gamma ray detecting device using dislocation-free crystal

International Nuclear Information System (INIS)

Vali, V.; Chang, D.B.

1991-01-01

This patent describes a γ-ray detector. It comprises: a dislocation-free single crystal having an input surface and a transmission surface at opposite ends thereof; an active shield surrounding the crystal and functioning as an anticoincidence counter; and γ-ray detector means disposed adjacent the transmission surface of the crystal for receiving and detecting γ-rays of a predetermined wavelength incident on the input surface of the crystal at a specific Bragg angle and transmitted through the crystal

Compact and cost-effective multi-channel optical spectrometer for fine FBG sensing in IoT technology

Science.gov (United States)

Konishi, Tsuyoshi; Yamasaki, Yu

2018-02-01

Optical fiber sensor networks have attracted much attention in IoT technology and a fiber Bragg grating is one of key sensor devices there because of their advantages in a high affinity for optical fiber networks, compactness, immunity to electromagnetic interference and so on. Nevertheless, its sensitivity is not always satisfactory so as to be usable together with widespread cost-effective multi-channel spectrometers. In this paper, we introduce a new cost-effective approach for a portable multi-channel spectrometer with high spectral resolution and demonstrates some preliminary experimental results for fine FBG sensing.

A New Method for Simultaneous Measurement of the Integrated Reflectivity of Crystals at Multiple Orders of Reflection and Comparison with New Theoretical Calculations

International Nuclear Information System (INIS)

Lee, S.G.; Bak, J.G.; Jung, Y.S.; Bitter, M.; Hill, K.W.; Hoelzer, G.; Wehrhan, O.; Foerster, E.

2003-01-01

This paper describes a new method for the simultaneous measurement of the integrated reflectivity of a crystal for multiple orders of reflection at a predefined Bragg angle. The technique is demonstrated with a mica crystal for Bragg angles of 43 o , 47 o , and 50 o . The measured integrated reflectivity for Bragg reflections up to the 24th order is compared with new theoretical predictions, which are also presented in this paper

Dosimetry and LET spectrometry in C 290 MeV/n and Ne 400 MeV/n HIMAC ion beam by different TLD's, TED based LET spectrometers, and Si energy-deposition spectrometer

International Nuclear Information System (INIS)

Spurny, F.; Brabcova, K.; Jadrnickova, I.; Uchihori, Y.; Kitamura, H.; Yasuda, N.; Molokanov, A. G.

2009-01-01

The sets of track etched detectors based (TED) spectrometer's of the linear energy transfer (LET) have been, together with two types of thermoluminescent detectors (TLD)and MDU- Liulin energy deposition spectrometer exposed in the C 290 MeV/n and Ne 400 MeV/n ion beams at the HlMAC installation at NIRS, Chiba, Japan. The experiment has been performed in the frame of NPI project 20P241 agreed by HlMAC P AC at the beginning of 2008 year. Up to now, moxstle only results obtained in C-ion beam have been treated and analyzed. Sets of TED spectrometer's and TLD detectors have been exposed in 19 depths in the C-ion beam with expected LET values of primary particles from 13 keV/μm in water, through the Bragg peak area up to two depth behind the Bragg peak. The contribution of fragments to total number of events, and to the energy absorbed in Si has been determined, when possible separately for different fragments. In all cases also total contribution of fragments (and other secondary particles) to the total number of energy deposition events and to the absorbed dose has been estimated. LET and energy deposition spectra obtained will be compared together , a good agreement of data has bee stated. Some of results have been also compared with those obtained by calculation by means of PHITS code. (authors)

Fiber Optic Sensors for Health Monitoring of Morphing Airframes. Part 2; Chemical Sensing Using Optical Fibers with Bragg Gratings

Science.gov (United States)

Wood, Karen; Brown, Timothy; Rogowski, Robert; Jensen, Brian

2000-01-01

Part 1 of this two part series described the fabrication and calibration of Bragg gratings written into a single mode optical fiber for use in strain and temperature monitoring. Part 2 of the series describes the use of identical fibers and additional multimode fibers, both with and without Bragg gratings, to perform near infrared spectroscopy. The demodulation system being developed at NASA Langley Research Center currently requires the use of a single mode optical fiber. Attempts to use this single mode fiber for spectroscopic analysis are problematic given its small core diameter, resulting in low signal intensity. Nonetheless, we have conducted a preliminary investigation using a single mode fiber in conjunction with an infrared spectrometer to obtain spectra of a high-performance epoxy resin system. Spectra were obtained using single mode fibers that contained Bragg gratings; however, the peaks of interest were barely discernible above the noise. The goal of this research is to provide a multipurpose sensor in a single optical fiber capable of measuring a variety of chemical and physical properties.

Structural matching of ferroelectric domains and associated distortion in potassium titanyl phosphate crystals

CERN Document Server

Pernot-Rejmankova, P; Cloetens, P; Lyford, T; Baruchel, J

2003-01-01

The surface deformation and atomic-level distortions associated with crystal structural matching at ferroelectric inversion domain walls are investigated in periodically poled potassium titanyl phosphate (KTP) crystals. A deformation, of the order of 10 sup - sup 8 m in scale and having the periodicity of the domains, is observed at the surfaces by optical interferometry. It is discussed in terms of the piezoelectric effect. The matching of the crystal structures at the domain walls is studied by combining the hard x-ray Fresnel phase-imaging technique with Bragg diffraction imaging methods ('Bragg-Fresnel imaging') and using synchrotron radiation. Quantitative analysis of the contrast of the Bragg-Fresnel images recorded as a function of the propagation distance is demonstrated to allow the determination of how the domains are matched at the atomic (unit cell) level, even though the spatial resolution of the images is on the scale of micrometres. The atom P(1) is determined as the linking atom for connecting...

Novel method of dual fiber Bragg gratings integrated in fiber ring laser for biochemical sensors

Science.gov (United States)

Bui, H.; Pham, T. B.; Nguyen, V. A.; Pham, V. D.; Do, T. C.; Nguyen, T. V.; Hoang, T. H. C.; Le, H. T.; Pham, V. H.

2018-05-01

Optical sensors have been shown to be very effective for measuring the toxic content in liquid and air environments. Optical sensors, which operate based on the wavelength shift of the optical signals, require an expensive spectrometer. In this paper, we propose a new configuration of the optical sensor device for measuring wavelength shift without using a spectrometer. This configuration has a large potential for application in biochemical sensing techniques, and comes with a low cost. This configuration uses dual fiber Bragg gratings (FBGs) integrated in a fiber ring laser structure of erbium-doped fiber, in which one FBG is used as a reference to sweep over the applicable spectrum of the etched-Bragg grating. The etched-FBG as a sensing probe is suitable for bio- and/or chemical sensors. The sensitivity and accuracy of the sensor system can be improved by the narrow linewidth of emission spectra from the laser, the best limit of detection of this sensor is 1.5  ×  10‑4 RIU (RIU: refractive index unit), as achieved by the optical sensor using a high resolution spectrometer. This sensor system has been experimentally investigated to detect different types of organic compounds, gasoline, mixing ratios of organic solvents in gasoline, and nitrate concentration in water samples. The experimental results show that this sensing method could determine different mixing ratios of organic solvents with good repeatability, high accuracy, and rapid response: e.g. for ethanol and/or methanol in gasoline RON 92 (RON: research octane number) of 0%–14% v/v, and nitrate in water samples at a low concentration range of 0–50 ppm. These results suggest that the proposed configuration can construct low-cost and accurate biochemical sensors.

Evaluation of HOPG mounting possibilities for multiplexing spectrometers

DEFF Research Database (Denmark)

Groitl, Felix; Bartkowiak, Marek; Bergmann, Ryan M.

2017-01-01

Four different methods for mounting HOPG analyzer crystals on Si holders have been evaluated in the design process of the new multiplexing spectrometer CAMEA. Contrary to neutron optics used in standard spectrometers, the new instrument concept employs a series of analyzer segments behind each...

Crystal and source characterization for the Crystal Backlighter Imager capability at the National Ignition Facility

Science.gov (United States)

Krauland, C. M.; Hall, G. N.; Buscho, J. G.; Hibbard, R.; McCarville, T. J.; Lowe-Webb, R.; Ayers, S. L.; Kalantar, D.; Kohut, T.; Kemp, G. E.; Bradley, D. K.; Bell, P.; Landen, O. L.; Brewster, T. N.; Piston, K.

2017-10-01

The Crystal Backlighter Imager (CBI) is a very narrow bandwidth ( 10 eV) x-ray radiography system that uses Bragg reflection from a spherically-curved crystal at near normal incidence. This diagnostic has the capability to image late in an ICF implosion because it only requires the brightness of the backlighter to be larger than the capsule self-emission in that narrow bandwidth. While the limited bandwidth is advantageous for this reason, it also requires that the effective energy of the backlighter atomic line is known to 1 eV accuracy for proper crystal alignment. Any Doppler shift in the line energy must be understood for the imaging system to work. The work presented details characterization experiments done at the Jupiter Laser Facility with a Si (8 6 2) crystal that will be used with a Selenium backlighter in the NIF CBI diagnostic. We used the spherically-bent crystals to image a small ( 200 µm) He α source generated by the Janus laser on a Se foil. Scanning Bragg angles over multiple shots allowed us to map out the spectral line intensity distribution for optimal alignment in NIF. A subsequent Doppler shift measurement using CBI on NIF will also be presented with complementary HYDRA modeling for both experiments. Prepared by LLNL under Contract DE-AC52-07NA27344 and by General Atomics under Contract DE-NA0001808.

The discovery of X-ray diffraction by crystals and its great impact on science

International Nuclear Information System (INIS)

Mai Zhenhong

2012-01-01

In April 1912, Friedrich, Knipping and Laue discovered X-ray diffraction in a CuSO 4 crystal. Later, Laue derived the famous Laue equations which explain the diffraction phenomenon. For this, Laue was awarded a Nobel Prize for Physics in 1914. In 1912 W. H. Bragg and W. L. Bragg received news of Laue 's discovery, and from X-ray diffraction experiments in a ZnS crystal they derived the famous Bragg equation. For this work, father and son were together awarded the Nobel Prize for Physics in 1915, To commemorate the 100th anniversary of the discovery of X-ray diffraction, this article reviews the important contributions of the early pioneers and their historic impact on science and technology worldwide. (author)

Investigation of Bragg reflections in α NbDsub(x) under hydrostatic pressure by γ ray diffraction

International Nuclear Information System (INIS)

Blaschko, O.; Klemencic, R.; Weinzierl, P.; Eder, O.J.

1978-01-01

Bragg reflections of NbDsub(x) single crystals in the α phase were studied under hydrostatic pressure using γ ray diffraction. The integrated intensity of the (211) reflection decreases by - 1.5 +- 0.2%/kbar and - 0.7 +- 0.1%/kbar in NbDsub(0.04) and NbDsub(0.02) respectively. The (200), (110) and (222) reflections show no change of intensity under hydrostatic pressure. In a pure Nb crystal no decrease of the intensity of the (211) reflection was found under hydrostatic pressure. (author)

The BTeV main spectrometer

International Nuclear Information System (INIS)

Sheldon, P.D.

2001-01-01

BTeV is a second generation B-factory experiment that will use a double-arm, forward spectrometer in the C0 experimental hall at the Fermilab Tevatron. I will describe the motivation and design of the 'main spectrometer', consisting of a ring-imaging Cherenkov system for charged particle identification, an electromagnetic calorimeter of lead-tungstate crystals, a proportional tube muon system with magnetized filtering steel, and a straw-tube and silicon strip charged particle tracking system

Low energy x-ray spectrometer

International Nuclear Information System (INIS)

Woodruff, W.R.

1981-01-01

A subkilovolt spectrometer has been produced to permit high-energy-resolution, time-dependent x-ray intensity measurements. The diffracting element is a curved mica (d = 9.95A) crystal. To preclude higher order (n > 1) diffractions, a carbon x-ray mirror that reflects only photons with energies less than approx. 1.1 keV is utilized ahead of the diffracting element. The nominal energy range of interest is 800 to 900 eV. The diffracted photons are detected by a gold-surface photoelectric diode designed to have a very good frequency response, and whose current is recorded on an oscilloscope. A thin, aluminium light barrier is placed between the diffracting crystal and the photoelectric diode detector to keep any uv generated on or scattered by the crystal from illuminating the detector. High spectral energy resolution is provided by many photocathodes between 8- and 50-eV wide placed serially along the diffracted x-ray beam at the detector position. The spectrometer was calibrated for energy and energy dispersion using the Ni Lα 1 2 lines produced in the LLNL IONAC accelerator and in third order using a molybdenum target x-ray tube. For the latter calibration the carbon mirror was replaced by one surfaced with rhodium to raise the cut-off energy to about 3 keV. The carbon mirror reflection dependence on energy was measured using one of our Henke x-ray sources. The curved mica crystal diffraction efficiency was measured on our Low-Energy x-ray (LEX) machine. The spectrometer performs well although some changes in the way the x-ray mirror is held are desirable. 16 figures

Anisotropic light diffraction in crystals with a large acoustic-energy walk-off

Science.gov (United States)

Balakshy, V. I.; Voloshin, A. S.; Molchanov, V. Ya.

2014-11-01

The influence of energy walk-off in an acoustic beam on the characteristic of anisotropic Bragg diffraction of light has been investigated by the example of paratellurite crystal. The angular and frequency characteristics of acousto-optic diffraction have been calculated in wide ranges of ultrasound frequencies and Bragg angles using the modified Raman-Nath equations. It is shown that the walk-off of an acoustic beam may change (either widen or narrow) significantly the frequency and angular ranges. The calculation results have been experimentally checked on an acousto-optic cell made of 10.5°-cut paratellurite crystal.

Optical power-based interrogation of plasmonic tilted fiber Bragg grating biosensors

Science.gov (United States)

González-Vila, Á.; Lopez-Aldaba, A.; Kinet, D.; Mégret, P.; Lopez-Amo, M.; Caucheteur, C.

2017-04-01

Two interrogation techniques for plasmonic tilted fiber Bragg grating sensors are reported and experimentally tested. Typical interrogation methods are usually based on tracking the wavelength shift of the most sensitive cladding mode, but for biosensing applications, spectrometer-based methods can be replaced by more efficient solutions. The proposed techniques thus rely on the measurement of the induced changes in optical power. The first one consists of a properly polarized tunable laser source set to emit at the wavelength of the sensor most sensitive mode and an optical power meter to measure the transmitted response. For the second method, a uniform fiber Bragg grating is photo-inscribed beyond the sensor in such a way that its central wavelength matches the sensor most sensitive mode, acting as an optical filter. Using a LED source, light reflected backwards by this grating is partially attenuated when passing through the sensor due to plasmon wave excitation and the power changes are quantified once again with an optical power meter. A performance analysis of the techniques is carried out and they both result competitive interrogation solutions. The work thus focuses on the development of cost-effective alternatives for monitoring this kind of biosensors in practical situations.

Fano resonance in anodic aluminum oxide based photonic crystals.

Science.gov (United States)

Shang, Guo Liang; Fei, Guang Tao; Zhang, Yao; Yan, Peng; Xu, Shao Hui; Ouyang, Hao Miao; Zhang, Li De

2014-01-08

Anodic aluminum oxide based photonic crystals with periodic porous structure have been prepared using voltage compensation method. The as-prepared sample showed an ultra-narrow photonic bandgap. Asymmetric line-shape profiles of the photonic bandgaps have been observed, which is attributed to Fano resonance between the photonic bandgap state of photonic crystal and continuum scattering state of porous structure. And the exhibited Fano resonance shows more clearly when the sample is saturated ethanol gas than air-filled. Further theoretical analysis by transfer matrix method verified these results. These findings provide a better understanding on the nature of photonic bandgaps of photonic crystals made up of porous materials, in which the porous structures not only exist as layers of effective-refractive-index material providing Bragg scattering, but also provide a continuum light scattering state to interact with Bragg scattering state to show an asymmetric line-shape profile.

Anisotropic Light Diffraction by Ultrasound in Crystals with Strong Acoustic Anisotropy

Science.gov (United States)

Voloshin, Andrey S.; Balakshy, Vladimir I.

In modern acousto-optics, crystalline materials are used predominantly for manufacturing acousto-optic instruments. Among these materials, such crystals as paratellurite, tellurium, calomel, TAS and some others occupy a prominent place, which are distinguished by exceptionally large anisotropy of acoustic properties. In this work, the influence of acoustic beam energy walk-off on characteristics of Bragg diffraction of light is studied by the example of tellurium crystal. It is shown that the walk-off can substantially change angular and frequency ranges, resulting in their narrowing or broadening subject to position of the operating point in the Bragg angle frequency characteristic. Coefficients of broadening are introduced for characterization of this effect.

Effect of antimony nano-scale surface-structures on a GaSb/AlAsSb distributed Bragg reflector

International Nuclear Information System (INIS)

Husaini, S.; Shima, D.; Ahirwar, P.; Rotter, T. J.; Hains, C. P.; Dang, T.; Bedford, R. G.; Balakrishnan, G.

2013-01-01

Effects of antimony crystallization on the surface of GaSb during low temperature molecular beam epitaxy growth are investigated. The geometry of these structures is studied via transmission electron and atomic force microscopies, which show the surface metal forms triangular-shaped, elongated nano-wires with a structured orientation composed entirely of crystalline antimony. By depositing antimony on a GaSb/AlAsSb distributed Bragg reflector, the field is localized within the antimony layer. Polarization dependent transmission measurements are carried out on these nano-structures deposited on a GaSb/AlAsSb distributed Bragg reflector. It is shown that the antimony-based structures at the surface favor transmission of light polarized perpendicular to the wires.

FOCUS: neutron time-of-flight spectrometer at SINQ: recent progress

Energy Technology Data Exchange (ETDEWEB)

Janssen, S.; Mesot, J.; Holitzner, L. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Hempelmann, R. [Saarbruecken Univ. (Germany)

1997-09-01

At the Swiss neutron spallation source SINQ a time-of-flight spectrometer for cold neutrons is under construction. The design foresees a Hybrid solution combining a Fermi chopper with a doubly focusing crystal monochromator. During 1996 important progress has been made concerning the main spectrometer components such as the spectrometer housing and the detector system. (author) 2 figs., 3 refs.

Detection of Ammonia-Oxidizing Bacteria (AOB) Using a Porous Silicon Optical Biosensor Based on a Multilayered Double Bragg Mirror Structure.

Science.gov (United States)

Zhang, Hongyan; Lv, Jie; Jia, Zhenhong

2018-01-01

We successfully demonstrate a porous silicon (PS) double Bragg mirror by electrochemical etching at room temperature as a deoxyribonucleic acid (DNA) label-free biosensor for detecting ammonia-oxidizing bacteria (AOB). Compared to various other one-dimension photonic crystal configurations of PS, the double Bragg mirror structure is quite easy to prepare and exhibits interesting optical properties. The width of high reflectivity stop band of the PS double Bragg mirror is about 761 nm with a sharp and deep resonance peak at 1328 nm in the reflectance spectrum, which gives a high sensitivity and distinguishability for sensing performance. The detection sensitivity of such a double Bragg mirror structure is illustrated through the investigation of AOB DNA hybridization in the PS pores. The redshifts of the reflectance spectra show a good linear relationship with both complete complementary and partial complementary DNA. The lowest detection limit for complete complementary DNA is 27.1 nM and the detection limit of the biosensor for partial complementary DNA is 35.0 nM, which provides the feasibility and effectiveness for the detection of AOB in a real environment. The PS double Bragg mirror structure is attractive for widespread biosensing applications and provides great potential for the development of optical applications.

Phenomena of non-thermal electrons from the X-ray imaging crystal spectrometer on J-TEXT tokamak

International Nuclear Information System (INIS)

Yan, W.; Chen, Z.Y.; Jin, W.; Huang, D.W.; Lee, S.G.; Shi, Y.J.; Tong, R.H.; Wang, S.Y.; Wei, Y.N.; Ma, T.K.; Zhuang, G.

2016-01-01

Highlights: • Some lines from X-ray imaging crystal spectrometer (XICS) can be enhanced by non-thermal electrons, such as q, r satellite lines and z lines. • Analyze the non-thermal phenomena can reduce the error of electron temperature deduced from the intensity ratio of different lines of the He-like argon spectra from XICS. • XICS can be a tool to measure the non-thermal phenomena from these enhanced lines. - Abstract: A high spectra resolution X-ray imaging crystal spectrometer has been implemented on J-TEXT Tokamak for the measurements of K_α spectra of helium-like argon and its satellite lines. The wavelength range of K_α spectra of helium-like argon is from 3.9494 Å to 3.9944 Å that includes the resonance line w, intercombination lines x and y, forbidden line z and numerous satellite lines, referenced using standard Gabriel notation. In low-density discharge, the intensity of q, r satellite lines and z lines can be significantly enhanced by non-thermal electrons. Non-thermal electrons are produced due to the low plasma density. The high hard X-ray flux from NaI detector and significant downshift electron cyclotron emissions from energetic runaway electrons also indicated that there is a large population of runaway electrons in the low-density discharge. The non-thermal part of electrons can affect the excitation/transition equilibrium or ionization/recombination equilibrium. The q line is mainly produced by inner-shell excitation of lithium-like argon, and the r line is partially produced by inner-shell excitation of lithium-like argon and dielectronic recombination of helium-like argon.

Phenomena of non-thermal electrons from the X-ray imaging crystal spectrometer on J-TEXT tokamak

Energy Technology Data Exchange (ETDEWEB)

Yan, W. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan (China); Chen, Z.Y., E-mail: zychen@hust.edu.cn [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan (China); Jin, W. [Center of Interface Dynamics for Sustainability, China Academy of Engineering Physics, Chengdu 610200, Sichuan (China); Huang, D.W. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan (China); Lee, S.G.; Shi, Y.J. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Tong, R.H.; Wang, S.Y.; Wei, Y.N.; Ma, T.K.; Zhuang, G. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan (China)

2016-11-01

Highlights: • Some lines from X-ray imaging crystal spectrometer (XICS) can be enhanced by non-thermal electrons, such as q, r satellite lines and z lines. • Analyze the non-thermal phenomena can reduce the error of electron temperature deduced from the intensity ratio of different lines of the He-like argon spectra from XICS. • XICS can be a tool to measure the non-thermal phenomena from these enhanced lines. - Abstract: A high spectra resolution X-ray imaging crystal spectrometer has been implemented on J-TEXT Tokamak for the measurements of K{sub α} spectra of helium-like argon and its satellite lines. The wavelength range of K{sub α} spectra of helium-like argon is from 3.9494 Å to 3.9944 Å that includes the resonance line w, intercombination lines x and y, forbidden line z and numerous satellite lines, referenced using standard Gabriel notation. In low-density discharge, the intensity of q, r satellite lines and z lines can be significantly enhanced by non-thermal electrons. Non-thermal electrons are produced due to the low plasma density. The high hard X-ray flux from NaI detector and significant downshift electron cyclotron emissions from energetic runaway electrons also indicated that there is a large population of runaway electrons in the low-density discharge. The non-thermal part of electrons can affect the excitation/transition equilibrium or ionization/recombination equilibrium. The q line is mainly produced by inner-shell excitation of lithium-like argon, and the r line is partially produced by inner-shell excitation of lithium-like argon and dielectronic recombination of helium-like argon.

Bragg diffraction of fermions at optical potentials

International Nuclear Information System (INIS)

Deh, Benjamin

2008-01-01

This thesis describes the Bragg diffraction of ultracold fermions at an optical potential. A moving optical lattice was created, by overlaying two slightly detuned lasers. Atoms can be diffracted at this lattice if the detuning fulfills the Bragg condition for resting atoms. This Bragg diffraction is analyzed systematically in this thesis. To this end Rabi oscillations between the diffraction states were driven, as well in the weakly interacting Bragg regime, as in the strongly interacting Kapitza-Dirac regime. Simulations, based on a driven two-, respectively multilevel-system describe the observed effects rather well. Furthermore, the temporal evolution of the diffracted states in the magnetic trapping potential was studied. The anharmonicity of the trap in use and the scattering cross section for p-wave collisions in a 6 Li system was determined from the movement of these states. Moreover the momentum distribution of the fermions was measured with Bragg spectroscopy and first signs of Fermi degeneracy were found. Finally an interferometer with fermions was build, exhibiting a coherence time of more than 100 μs. With this, the possibility for measurement and manipulation of ultracold fermions with Bragg diffraction could bee shown. (orig.)

A neural network for the Bragg synthetic curves recognition.; Una red neuronal para el reconocimiento de curvas de Bragg sinteticas

Energy Technology Data Exchange (ETDEWEB)

Reynoso V, M R; Vega C, J J; Fernandez A, J; Belmont M, E; Policroniades R, R; Moreno B, E [Instituto Nacional de Investigaciones Nucleares, Salazar, Edo. de Mexico. (Mexico)

1997-12-31

A ionization chamber was employed named Bragg curve spectroscopy. The Bragg peak amplitude is a monotone growing function of Z, which permits to identify elements through their measurement. A better technique for this measurement is to improve the use of neural networks with the purpose of the identification of the Bragg curve. (Author).

Polymer optical fiber bragg grating sensors

DEFF Research Database (Denmark)

Stefani, Alessio; Yuan, Scott Wu; Andresen, Søren

2010-01-01

Fiber-optical accelerometers based on polymer optical fiber Bragg gratings are reported. We have written fiber Bragg gratings for 1550 nm and 850 nm operations, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

Wave-dispersive x-ray spectrometer for simultaneous acquisition of several characteristic lines based on strongly and accurately shaped Ge crystal

International Nuclear Information System (INIS)

Hayashi, Kouichi; Nakajima, Kazuo; Fujiwara, Kozo; Nishikata, Susumu

2008-01-01

Si and Ge are widely used as analyzing crystals for x-rays. Drastic and accurate shaping of Si or Ge gives significant advance in the x-ray field, although covalently bonded Si or Ge crystals have long been believed to be not deformable to various shapes. Recently, we developed a deformation technique for obtaining strongly and accurately shaped Si or Ge wafers of high crystal quality, and the use of the deformed wafer made it possible to produce fine-focused x-rays. In the present study, we prepared a cylindrical Ge wafer with a radius of curvature of 50 mm, and acquired fluorescent x-rays simultaneously from four elements by combining the cylindrical Ge wafer with a position-sensitive detector. The energy resolution of the x-ray fluorescence spectrum was as good as that obtained using a flat single crystal, and its gain was over 100. The demonstration of the simultaneous acquisition of high-resolution x-ray fluorescence spectra indicated various possibilities of x-ray spectrometry, such as one-shot x-ray spectroscopy and highly efficient wave-dispersive x-ray spectrometers

Evaluation of the ROTAX spectrometer

International Nuclear Information System (INIS)

Tietze-Jaensch, H.; Schmidt, W.; Geick, R.

1997-01-01

After installation of the new-type rotating crystal analyser spectrometer ROTAX at ISIS, we report on practical experience and describe its current status. The rotating analyser technique works feasibly and reliably and provides an ultimate scan flexibility on a pulsed time-of-flight neutron spectrometer. The spinning analyser achieves a mulitplex advantage factor of ca. 50 without compromising the resolution of the instrument. Despite these instrument merits its individual beam position at ISIS has only an unsatisfactorily weak flux, thus hindering this instrument yet to become fully competitive with other high-performance neutron spectrometers based at high-flux reactors. However, we strongly recommend a ROTAX-type instrument to be emphasized when the instrumentation suite of the future European spallation source ESS will come under scrutiny. (orig.)

Fundamental losses in planar Bragg waveguides

NARCIS (Netherlands)

Vinogradov, A. V.; Mitrofanov, A. N.; Popov, A. V.; Fedin, M. A.

2007-01-01

This paper considers a planar Bragg waveguide. The guided modes and their dissipation due to the fundamental absorption are described. In the interacting-wave approximation, an analytical relation between the characteristics of the modes and parameters of the Bragg-waveguide geometry was

Fibre Bragg grating for flood embankment monitoring

Science.gov (United States)

Markowski, Konrad; Nevar, Stanislau; Dworzanski, Adam; Hackiewicz, Krzysztof; Jedrzejewski, Kazimierz

2014-11-01

In this article we present the preliminary studies for the flood embankment monitoring system based on the fibre Bragg gratings. The idea of the system is presented. The Bragg resonance shift is transformed to the change of the power detected by the standard InGaAs photodiode. The discrimination of the received power was executed by another fibre Bragg grating with different parameters. The project of the fully functional system is presented as well.

First observation of new effects at the set-up for searching for a neutron electric dipole moment by a crystal-diffraction method

CERN Document Server

Fedorov, V V; Semenikhin, S Y; Voronin, V V

2002-01-01

First observation of new effects was carried out using the set-up created for searching for a neutron electric dipole moment (EDM) by a crystal-diffraction method. For the first time the neutron dynamical Laue diffraction for the Bragg angles close to a right angle (up to 87 ) was studied, using the direct diffraction beam and a thick (propor to 3.5-cm) crystal. The effect of an essential time delay of diffracting neutrons inside the crystal for Bragg angles close to 90 was experimentally observed, using a time-of-flight method. The phenomenon of neutron-beam depolarization was first experimentally observed for the case of Laue diffraction in a noncentrosymmetric alpha-quartz crystal. It is experimentally proved that the interplanar electric field, affecting a neutron in a crystal, maintains its value up to Bragg angles equal to 87 . These results confirm the opportunity to increase by more than an order of magnitude the sensitivity of the method to the neutron EDM, using the diffraction angles close to 90 , ...

High intensity line source for x-ray spectrometer calibration

International Nuclear Information System (INIS)

Thoe, R.S.

1986-06-01

A high intensity electron-impact x-ray source using a one-dimensional Pierce lens has been built for the purpose of calibrating a bent crystal x-ray spectrometer. This source focuses up to 100 mA of 20-keV electrons to a line on a liquid-cooled anode. The line (which can serve as a virtual slit for the spectrometer) measures approximately 800 μ x 2 cm. The source is portable and therefore adaptable to numerous types of spectrometer applications. One particular application, the calibration of a high resolution (r = 10 4 ) time-resolved cyrstal spectrometer, will be discussed in detail

Measurement of the electron and ion temperatures by the x-ray imaging crystal spectrometer on joint Texas experimental tokamak

Energy Technology Data Exchange (ETDEWEB)

Yan, W.; Chen, Z. Y., E-mail: zychen@hust.edu.cn; Huang, D. W.; Tong, R. H.; Wang, S. Y.; Wei, Y. N.; Ma, T. K.; Zhuang, G. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan (China); Jin, W. [Center of Interface Dynamics for Sustainability, China Academy of Engineering Physics, Chengdu, Sichuan 610200 (China); Lee, S. G. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Shi, Y. J. [Department of Nuclear Engineering, Seoul National University, Seoul 08826 (Korea, Republic of)

2016-11-15

An x-ray imaging crystal spectrometer has been developed on joint Texas experimental tokamak for the measurement of electron and ion temperatures from the K{sub α} spectra of helium-like argon and its satellite lines. A two-dimensional multi-wire proportional counter has been applied to detect the spectra. The electron and ion temperatures have been obtained from the Voigt fitting with the spectra of helium-like argon ions. The profiles of electron and ion temperatures show the dependence on electron density in ohmic plasmas.

Observations of the X-ray nova A0620-00 with the Ariel V crystal spectrometer/polarimeter

International Nuclear Information System (INIS)

Griffiths, R.E.; Rickets, M.J.; Cooke, B.A.

1976-01-01

The X-ray nova A0620-00 has been studied with the Ariel V crystal spectrometer/polarimeter for the presence of X-ray lines and polarization. Upper limits are obtained for the Si XIV, S XV and S XVI lines to a level of less than 2 eV at 3 sigma for the sulphur lines and 3.6 eV for Si XIV. No linear polarization is observed to a level of 2 per cent at 2.6 keV. These results are interpreted in terms of an accretion disk model for the source, in which the electron scattering depth tausub(es) approximately 20, and constraints are given on the disk geometry. (author)

Design, construction and characterization of the acoustic-optical spectrometers for radioastromomic applications

International Nuclear Information System (INIS)

Garde, M.J.; Aramburu, C.; Benito, D.E.; Sebastian, J.L.

1997-01-01

This paper describes the study, design, construction and experimental characterization of the acoustic-optical spectrometer of 58 MHz bandwidth and effective resolution of 108 kHz that is being used with the 14 m antenna of the Centro Astronomico de Yebes (CAY). The use of the quasi-tangent interaction described in this paper increases the bandwidth by a factor of 2''1/2 with 3 dB at the center and edges of the frequency bandwidth. The greater bandwidth leads to a better bandwidth frequency resolution ratio, therefore, the system is equally well suited for the resolution of both narrow and wide spectral lines. The spectrometer presents a linear response over the full dynamic range of 20 dB. Frequency deviation from linear behaviour, due to the non-linear interaction in the Bragg modular, is corrected and a linear frequency response within one tenth of a channel (10 kHz) over the full bandwidth is obtained. The excellent stability of the spectrometer allows for longer integration times, therefore saving real observation time. (Author) 13 refs

Femtosecond pulse laser notch shaping via fiber Bragg grating for the excitation source on the coherent anti-Stokes Raman spectroscopy

Science.gov (United States)

Oh, Seung Ryeol; Kwon, Won Sik; Kim, Jin Hwan; Kim, Kyung-Soo; Kim, Soohyun

2015-03-01

Single-pulse coherently controlled nonlinear Raman spectroscopy is the simplest method among the coherent anti-Stokes Raman spectroscopy systems. In recent research, it has been proven that notch-shaped femtosecond pulse laser can be used to collect the coherent anti-Stokes Raman signals. In this study, we applied a fiber Bragg grating to the notch filtering component on the femtosecond pulse lasers. The experiment was performed incorporating a titanium sapphire femtosecond pulse laser source with a 100 mm length of 780-HP fiber which is inscribed 30 mm of Bragg grating. The fiber Bragg grating has 785 nm Bragg wavelength with 0.9 nm bandwidth. We proved that if the pulse lasers have above a certain level of positive group delay dispersion, it is sufficient to propagate in the fiber Bragg grating without any spectral distortion. After passing through the fiber Bragg grating, the pulse laser is reflected on the chirped mirror for 40 times to make the transform-limited pulse. Finally, the pulse time duration was 37 fs, average power was 50mW, and showed an adequate notch shape. Furthermore, the simulation of third order polarization signal is performed using MATLAB tools and the simulation result shows that spectral characteristic and time duration of the pulse is sufficient to use as an excitation source for single-pulse coherent anti-Stokes Raman spectroscopy. In conclusion, the proposed method is more simple and cost-effective than the methods of previous research which use grating pairs and resonant photonic crystal slab.

Bragg-Fresnel optics: New field of applications

Energy Technology Data Exchange (ETDEWEB)

Snigirev, A. [ESRF, Grenoble (France)

1997-02-01

Bragg-Fresnel Optics shows excellent compatibility with the third generation synchrotron radiation sources such as ESRF and is capable of obtaining monochromatic submicron focal spots with 10{sup 8}-10{sup 9} photons/sec in an energy bandwidth of 10{sup -4}-10{sup -6} and in a photon energy range between 2-100 keV. New types of Bragg-Fresnel lenses like modified, ion implanted, bent and acoustically modulated were tested. Microprobe techniques like microdiffraction and microfluorescence based on Bragg-Fresnel optics were realised at the ESRF beamlines. Excellent parameters of the X-ray beam at the ESRF in terms of low emittance and quite small angular source size allow for Bragg-Fresnel optics to occupy new fields of applications such as high resolution diffraction, holography, interferometry and phase contrast imaging.

Temperature-modified photonic bandgap in colloidal photonic crystals fabricated by vinyl functionalized silica spheres

International Nuclear Information System (INIS)

Deng Tiansong; Zhang Junyan; Zhu Kongtao; Zhang Qifeng; Wu Jinlei

2011-01-01

Graphical abstract: A thermal annealing procedure was described for fine modifying the photonic bandgap properties of colloidal photonic crystals, which were self-assembled from vinyl-functionalized silica spheres by a gravity sedimentation process. Highlights: → We described a thermal annealing procedure for fine modifying the photonic bandgap properties of colloidal photonic crystals. → The position of its stop band had more than 25% blue shift by annealing the sample from 60 to 600 deg. C. → The annealing temperature and the Bragg peak values have a linear relationship in the 120-440 deg. C range. → The effects provide a simple and controllable method for modifying the photonic bandgap properties of colloidal photonic crystals. - Abstract: A thermal annealing procedure for fine modifying the photonic bandgap properties of colloidal photonic crystals was described. The colloidal photonic crystals were assembled from monodisperse vinyl functionalized silica spheres by a gravity sedimentation process. The samples diffract light following Bragg's law combined with Snell's law. By annealing the sample at temperatures in the range of 60-600 deg. C, the position of its stop band shifted from 943 to 706 nm. It had more than 25% blue shift. In addition, the annealing temperature and the Bragg peak values have a linear relationship in the 120-440 deg. C range. Fourier transform infrared (FT-IR) spectra and thermo-gravimetric analysis (TGA) curves of vinyl functionalized silica spheres confirmed the above results. The effects provide a simple and controllable method for modifying the photonic bandgap properties of colloidal photonic crystals.

Design, Build & Test of a Double Crystal Monochromator for Beamlines I09 & I23 at the Diamond Light Source

Science.gov (United States)

Kelly, J.; Lee, T.; Alcock, S.; Patel, H.

2013-03-01

A high stability Double Crystal Monochromator has been developed at The Diamond Light Source for beamlines I09 and I23. The design specification was a cryogenic, fixed exit, energy scanning monochromator, operating over an energy range of 2.1 - 25 keV using a Si(111) crystal set. The novel design concepts are the direct drive, air bearing Bragg axis, low strain crystal mounts and the cooling scheme. The instrument exhibited superb stability and repeatability on the B16 Test Beamline. A 20 keV Si(555), 1.4 μrad rocking curve was demonstrated. The DCM showed good stability without any evidence of vibration or Bragg angle nonlinearity.

Ultra compact spectrometer apparatus and method using photonic crystals

Science.gov (United States)

Ting, David Z. (Inventor); Hill, Cory J. (Inventor); Bandara, Sumith V. (Inventor); Gunapala, Sarath D. (Inventor)

2009-01-01

The present invention is directed to methods of photonic crystal formation, and to methods and apparatus for using such photonic crystals, particularly in conjunction with detector arrays. Photonic crystal parameters and detector array parameters are compared to optimize the selection and orientation of a photonic crystal shape. A photonic crystal is operatively positioned relative to a plurality of light sensors. The light sensors can be separated by a pitch distance and positioned within one half of the pitch distance of an exit surface of the photonic crystals.

Dramatic improvement of crystal quality for low-temperature-grown rabbit muscle aldolase

International Nuclear Information System (INIS)

Park, HaJeung; Rangarajan, Erumbi S.; Sygusch, Jurgen; Izard, Tina

2010-01-01

Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination. Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA–LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice

Cascaded Bragg scattering in fiber optics.

Science.gov (United States)

Xu, Y Q; Erkintalo, M; Genty, G; Murdoch, S G

2013-01-15

We report on a theoretical and experimental study of cascaded Bragg scattering in fiber optics. We show that the usual energy-momentum conservation of Bragg scattering can be considerably relaxed via cascade-induced phase-matching. Experimentally we demonstrate frequency translation over six- and 11-fold cascades, in excellent agreement with derived phase-matching conditions.

One module of the ALICE photon spectrometer

CERN Multimedia

Maximilien Brice

2006-01-01

The first module for the ALICE photon spectrometer has been completed. Each of the five modules will contain 3584 lead-tungstate crystals, a material as transparent as ordinary silica glass but with nearly four times the density. When a high-energy particle passes through one of these crystals it will scintillate, allowing the energy of electrons, positrons and photons to be measured through the 17 920 detection channels.

Fast Formation of Opal-like Columnar Colloidal Crystals

NARCIS (Netherlands)

van der Beek, D.; Radstake, P.B.; Petukhov, A.V.; Lekkerkerker, H.N.W.

2007-01-01

We demonstrate that highly polydisperse colloidal gibbsite platelets easily form an opal-like columnar crystal with striking iridescent Bragg reflections. The formation process can be accelerated by orders of magnitude under a centrifugation force of 900g without arresting the system in a disordered

Viscoelastic modes in chiral liquid crystals

Indian Academy of Sciences (India)

amit@fs.rri.local.net (Amit Kumar Agarwal)

our studies on the viscoelastic modes of some chiral liquid crystals using dynamic light scattering. We discuss viscoelastic ... In the vicinity of the direct beam for a sample aligned in the Bragg mode and. 297 ... experimental investigations on these modes. Duke and Du ..... scattering volume is not true in practice. In an actual ...

Dramatic improvement of crystal quality for low-­temperature-grown rabbit muscle aldolase

OpenAIRE

Park, HaJeung; Rangarajan, Erumbi S.; Sygusch, Jurgen; Izard, Tina

2010-01-01

Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination.

A neural network for the Bragg synthetic curves recognition

International Nuclear Information System (INIS)

Reynoso V, M.R.; Vega C, J.J.; Fernandez A, J.; Belmont M, E.; Policroniades R, R.; Moreno B, E.

1996-01-01

A ionization chamber was employed named Bragg curve spectroscopy. The Bragg peak amplitude is a monotone growing function of Z, which permits to identify elements through their measurement. A better technique for this measurement is to improve the use of neural networks with the purpose of the identification of the Bragg curve. (Author)

Neutron forward diffraction by single crystal prisms

Indian Academy of Sciences (India)

We have derived analytic expressions for the deflection as well as transmitted fraction of monochromatic neutrons forward diffracted by a single crystal prism. In the vicinity of a Bragg reflection, the neutron deflection deviates sharply from that for an amorphous prism, exhibiting three orders of magnitude greater sensitivity to ...

Precision mechanical structure of an ultra-high-resolution spectrometer for inelastic X-ray scattering instrument

Science.gov (United States)

Shu, Deming; Shvydko, Yuri; Stoupin, Stanislav A.; Khachatryan, Ruben; Goetze, Kurt A.; Roberts, Timothy

2015-04-14

A method and an ultrahigh-resolution spectrometer including a precision mechanical structure for positioning inelastic X-ray scattering optics are provided. The spectrometer includes an X-ray monochromator and an X-ray analyzer, each including X-ray optics of a collimating (C) crystal, a pair of dispersing (D) element crystals, anomalous transmission filter (F) and a wavelength (W) selector crystal. A respective precision mechanical structure is provided with the X-ray monochromator and the X-ray analyzer. The precision mechanical structure includes a base plate, such as an aluminum base plate; positioning stages for D-crystal alignment; positioning stages with an incline sensor for C/F/W-crystal alignment, and the positioning stages including flexure-based high-stiffness structure.

Tunable waveguide and cavity in a phononic crystal plate by controlling whispering-gallery modes in hollow pillars

DEFF Research Database (Denmark)

Jin, Yabin; Fernez, Nicolas; Pennec, Yan

2016-01-01

We investigate the properties of a phononic crystal plate with hollow pillars and introduce the existence of whispering-gallery modes (WGMs). We show that by tuning the inner radius of the hollow pillar, these modes can merge inside both Bragg and low frequency band gaps, deserving phononic crystal...... and acoustic metamaterial applications. These modes can be used as narrow pass bands for which the quality factor can be greatly enhanced by the introduction of an additional cylinder between the hollow cylinder and the plate. We discuss some functionalities of these confined WGM in both Bragg and low...

Determination of three-dimensional interfacial strain - A novel method of probing interface structure with X-ray Bragg-surface diffraction

International Nuclear Information System (INIS)

Sun, W.-C.; Chu, C.-H.; Chang, H.-C.; Wu, B.-K.; Chen, Y.-R.; Cheng, C.-W.; Chiu, M.-S.; Shen, Y.-C.; Wu, H.-H.; Hung, Y.-S.; Chang, S.-L.; Hong, M.-H.; Tang, M.-T.; Stetsko, Yu.P.

2007-01-01

A new X-ray diffraction technique is developed to probe structural variations at the interfaces between epitaxy thin films and single-crystal substrates. The technique utilizes three-wave Bragg-surface diffraction, where a symmetric Bragg reflection and an asymmetric surface reflection are involved. The propagation of the latter along the interfaces conveys structural information about the interfacial region between the substrate and epi-layers. The sample systems of Au/GaAs(001) are subject to the three-wave diffraction investigation using synchrotron radiation. The GaAs three-wave Bragg-surface diffractions (006)/(11-bar3) and (006)/(1-bar1-bar3), are employed. The images of the surface diffracted waves are recorded with an image plate. The obtained images show relative positions of diffraction spots near the image of the interfacial boundary, which give the variation of lattice constant along the surface normal and in-plane directions. With the aid of grazing-incidence diffraction, three-dimensional mapping of strain field at the interfaces is possible. Details about this diffraction technique and the analysis procedures are discussed

MEMS Bragg grating force sensor

DEFF Research Database (Denmark)

Reck, Kasper; Thomsen, Erik Vilain; Hansen, Ole

2011-01-01

We present modeling, design, fabrication and characterization of a new type of all-optical frequency modulated MEMS force sensor based on a mechanically amplified double clamped waveguide beam structure with integrated Bragg grating. The sensor is ideally suited for force measurements in harsh...... environments and for remote and distributed sensing and has a measured sensitivity of -14 nm/N, which is several times higher than what is obtained in conventional fiber Bragg grating force sensors. © 2011 Optical Society of America....

Design, Build and Test of a Double Crystal Monochromator for Beamlines I09 and I23 at the Diamond Light Source

International Nuclear Information System (INIS)

Kelly, J; Lee, T; Alcock, S; Patel, H

2013-01-01

A high stability Double Crystal Monochromator has been developed at The Diamond Light Source for beamlines I09 and I23. The design specification was a cryogenic, fixed exit, energy scanning monochromator, operating over an energy range of 2.1 – 25 keV using a Si(111) crystal set. The novel design concepts are the direct drive, air bearing Bragg axis, low strain crystal mounts and the cooling scheme. The instrument exhibited superb stability and repeatability on the B16 Test Beamline. A 20 keV Si(555), 1.4 μrad rocking curve was demonstrated. The DCM showed good stability without any evidence of vibration or Bragg angle nonlinearity.

Frequency shift of the Bragg and Non-Bragg backscattering from periodic water wave

Science.gov (United States)

Wen, Biyang; Li, Ke

2016-08-01

Doppler effect is used to measure the relative speed of a moving target with respect to the radar, and is also used to interpret the frequency shift of the backscattering from the ocean wave according to the water-wave phase velocity. The widely known relationship between the Doppler shift and the water-wave phase velocity was deduced from the scattering measurements data collected from actual sea surface, and has not been verified under man-made conditions. Here we show that this ob- served frequency shift of the scattering data from the Bragg and Non-Bragg water wave is not the Doppler shift corresponding to the water-wave phase velocity as commonly believed, but is the water-wave frequency and its integral multiple frequency. The power spectrum of the backscatter from the periodic water wave consists of serials discrete peaks, which is equally spaced by water wave frequency. Only when the water-wave length is the integer multiples of the Bragg wave, and the radar range resolution is infinite, does the frequency shift of the backscattering mathematically equal the Doppler shift according to the water-wave phase velocity.

A theoretical approach to dynamical diffraction of X-rays in the Bragg case with the Green's function method

International Nuclear Information System (INIS)

Ishida, Hidenobu

2015-01-01

The dynamical diffraction theory of X-rays for a distorted crystal with the Green's function method is applied to the Bragg case. The transmitted and diffracted crystal waves are represented as the solutions of the integral equations using the Green's function. For a perfect crystal, the most exact form of the solution of the equations is given by the Green's function and its derivatives, and the waves are analytically expressed by using them. The results can be applied in a general case where the amplitude modulation of the incident wave is not negligibly small compared with the wave vector. If the amplitude modulation is small, those results are reduced essentially to the same as those given by Takagi's theory. (author)

Design, construction and description of a triple axis neutron crystal spectrometer

International Nuclear Information System (INIS)

Fulfaro, R.; Vinhas, L.A.; Fuhrmann, C.; Liguori Neto, R.; Parente, C.B.R.

1977-01-01

Integrating the neutron inelastic scattering plan in IEA (Sao Paulo, Brazil) it was completely designed and constructed there, a triple axis neutron spectrometer. The details about construction and design of the spectrometer are described. Basic principles about the experimental method which utilizes neutron coherent inelastic scattering in order to determine the relation dispersion between frequency and wave vector of the crystalline vibrations, are presented [pt

Mosaic crystal algorithm for Monte Carlo simulations

CERN Document Server

Seeger, P A

2002-01-01

An algorithm is presented for calculating reflectivity, absorption, and scattering of mosaic crystals in Monte Carlo simulations of neutron instruments. The algorithm uses multi-step transport through the crystal with an exact solution of the Darwin equations at each step. It relies on the kinematical model for Bragg reflection (with parameters adjusted to reproduce experimental data). For computation of thermal effects (the Debye-Waller factor and coherent inelastic scattering), an expansion of the Debye integral as a rapidly converging series of exponential terms is also presented. Any crystal geometry and plane orientation may be treated. The algorithm has been incorporated into the neutron instrument simulation package NISP. (orig.)

Horizontal Ampoule Growth and Characterization of Mercuric Iodide at Controlled Gas Pressures for X-Ray and Gamma Ray Spectrometers

International Nuclear Information System (INIS)

Douglas, S.; McGregor Elsa; Ariesanti Bridget Corcoran

2004-01-01

The project developed a new method for producing high quality mercuric iodide crystals of x-ray and gamma spectrometers. Included are characterization of mercuric iodide crystal properties as a function of growth environment and fabrication and demonstration of room-temperature-operated high-resolution mercuric iodide spectrometers

Development of a High Resolution X-Ray Imaging Crystal Spectrometer for Measurement of Ion-Temperature and Rotation-Velocity Profiles in Fusion Energy Research Plasmas

International Nuclear Information System (INIS)

Hill, K.W.; Bitter, M.L.; Broennimann, Ch.; Eikenberry, E.F.; Ince-Cushman, A.; Lee, S.G.; Rice, J.E.; Scott, S.; Barnsley, R.

2008-01-01

A new imaging high resolution x-ray crystal spectrometer (XCS) has been developed to measure continuous profiles of ion temperature and rotation velocity in fusion plasmas. Following proof-of-principle tests on the Alcator C-Mod tokamak and the NSTX spherical tokamak, and successful testing of a new silicon, pixilated detector with 1MHz count rate capability per pixel, an imaging XCS is being designed to measure full profiles of T i and ν φ on C-Mod. The imaging XCS design has also been adopted for ITER. Ion-temperature uncertainty and minimum measurable rotation velocity are calculated for the C-Mod spectrometer. The affects of x-ray and nuclear-radiation background on the measurement uncertainties are calculated to predict performance on ITER

Spin spectrometer at the holified heavy-ion research facility and some planned experiments

International Nuclear Information System (INIS)

Sarantites, D.G.; Jaaskelainen, M.; Hood, J.T.; Woodward, R.; Barker, J.H.; Hensley, D.C.; Halbert, M.L.; Chan, Y.D.

1980-01-01

The 4π multidetector γ-ray spectrometer at the Holified Heavy-ion Research Facility (HHIRF) is described in some detail. The following important features of this spectrometer are discussed: (a) the geometric arrangement, (b) the actual performance of the individual detector elements, (c) the associated electronics and data acquisition system, and (d) the response of the system to input γ-cascades including the effect of crystal-to-crystal scattering and the response to neutrons. The first few experiments to be performed are briefly described

Dimensional crossover in Bragg scattering from an optical lattice

International Nuclear Information System (INIS)

Slama, S.; Cube, C. von; Ludewig, A.; Kohler, M.; Zimmermann, C.; Courteille, Ph.W.

2005-01-01

We study Bragg scattering at one-dimensional (1D) optical lattices. Cold atoms are confined by the optical dipole force at the antinodes of a standing wave generated inside a laser-driven high-finesse cavity. The atoms arrange themselves into a chain of pancake-shaped layers located at the antinodes of the standing wave. Laser light incident on this chain is partially Bragg reflected. We observe an angular dependence of this Bragg reflection which is different from what is known from crystalline solids. In solids, the scattering layers can be taken to be infinitely spread (three-dimensional limit). This is not generally true for an optical lattice consistent of a 1D linear chain of pointlike scattering sites. By an explicit structure factor calculation, we derive a generalized Bragg condition, which is valid in the intermediate regime. This enables us to determine the aspect ratio of the atomic lattice from the angular dependance of the Bragg scattered light

Stitching Type Large Aperture Depolarizer for Gas Monitoring Imaging Spectrometer

Science.gov (United States)

Liu, X.; Li, M.; An, N.; Zhang, T.; Cao, G.; Cheng, S.

2018-04-01

To increase the accuracy of radiation measurement for gas monitoring imaging spectrometer, it is necessary to achieve high levels of depolarization of the incoming beam. The preferred method in space instrument is to introduce the depolarizer into the optical system. It is a combination device of birefringence crystal wedges. Limited to the actual diameter of the crystal, the traditional depolarizer cannot be used in the large aperture imaging spectrometer (greater than 100 mm). In this paper, a stitching type depolarizer is presented. The design theory and numerical calculation model for dual babinet depolarizer were built. As required radiometric accuracies of the imaging spectrometer with 250 mm × 46 mm aperture, a stitching type dual babinet depolarizer was design in detail. Based on designing the optimum structural parmeters the tolerance of wedge angle refractive index, and central thickness were given. The analysis results show that the maximum residual polarization degree of output light from depolarizer is less than 2 %. The design requirements of polarization sensitivity is satisfied.

Bent crystal X-ray optics for the diagnosis and applications of laser-produced plasmas

International Nuclear Information System (INIS)

Loetzsch, Robert

2012-01-01

The present thesis discussed several aspects of X-ray optics based on bent crystals and a number of applications of these optics. First, a deeper insight into the reflection properties of elastically bent perfect crystal optics was gained by the consideration of all deformation effects. It was shown that the reflection properties depend on the lateral position on the crystal, an effect that was not addressed before, neither experimentally nor theoretically. To investigate this effect, an apparatus for the measurement of Bragg angles of bent crystals with high angular resolution was built. It was measured that the lattice plane distances of two-dimensionally bent crystals vary laterally by up to 10 -4 . This effect has to be considered in high resolution X-ray spectroscopy and imaging with these bent crystals. It can explain discrepancies in theoretical and experimental spectrometer resolution with spherically bent crystals. Besides these principal investigations, in this thesis a number of X-ray optics were presented that demonstrate the application potential of bent crystal optics. This includes two optics that are used in the field of applications of laser-produced plasmas as high repeating hard X-ray sources. It was shown that an X-ray spectrometer based on full cylinder rings of highly oriented pyrolytic graphite is capable to record the rather weak single shot pulses from a high repeating 1 er-plasma X-ray source. This is possible due to the high collection efficiency of the instrument of up to 5.10 -4 . Furthermore, X-ray optics based on toroidally bent crystals that make it possible to spectrally select a bandwidth of ∝1 eV and focus the ultrashort X-ray pulses from such a laser-plasma source, were designed, prepared and characterized. It was shown that these bent crystals provide the calculated integrated reflectivity, the predicted bandwidth and focus to spot sizes smaller than 60 μm. A novel application of toroidally bent crystals was pointed out: a

Development of a high resolution, high sensitivity cylindrical crystal spectrometer for line shape diagnostics of x-rays emitted from hot plasmas. Progress report, August 1, 1977--July 31, 1978

International Nuclear Information System (INIS)

Taylor, P.O.; Schnopper, H.

1978-05-01

This report oulines progress towards development of a high resolution, high throughput, curved crystal spectrometer suitable for line shape diagnostics of x-rays emitted from hot plasmas. The instrument is designed to interface with the MIT Tokamak (Alcator) with the initial aim of studying the prominent MoL lines which occur in the x-ray spectrum. However, it will have the versatility to function over an energy range of at least 1.5 keV to 7 keV allowing determination of temperature, charge state and density distributions for important impurity ions. The spectrometer employs a large, cylindrically bent crystal which focuses the dispersed x-rays along the cylinder axis where they are recorded by a position sensitive proportional counter. Thus, a wide energy range of the spectrum can be recorded simultaneously and sensitively from a short duration plasma. Computer control of data acquisition and analysis will allow real-time diagnostics

Polymer Stabilization of Liquid-Crystal Blue Phase II toward Photonic Crystals.

Science.gov (United States)

Jo, Seong-Yong; Jeon, Sung-Wook; Kim, Byeong-Cheon; Bae, Jae-Hyun; Araoka, Fumito; Choi, Suk-Won

2017-03-15

The temperature ranges where a pure simple-cubic blue phase (BPII) emerges are quite narrow compared to the body-centered-cubic BP (BPI) such that the polymer stabilization of BPII is much more difficult. Hence, a polymer-stabilized BPII possessing a wide temperature range has been scarcely reported. Here, we fabricate a polymer-stabilized BPII over a temperature range of 50 °C including room temperature. The fabricated polymer-stabilized BPII is confirmed via polarized optical microscopy, Bragg reflection, and Kossel diagram observations. Furthermore, we demonstrate reflective BP liquid-crystal devices utilizing the reflectance-voltage performance as a potential application of the polymer-stabilized BPII. Our work demonstrates the possibility of practical application of the polymer-stabilized BPII to photonic crystals.

Single-Crystal Diffraction from Two-Dimensional Block Copolymer Arrays

International Nuclear Information System (INIS)

Stein, G. E.; Kramer, E. J.; Li, X.; Wang, J.

2007-01-01

The structure of oriented 2D block copolymer single crystals is characterized by grazing-incidence small-angle x-ray diffraction, demonstrating long-range sixfold orientational order. From line shape analysis of the higher-order Bragg diffraction peaks, we determine that translational order decays algebraically with a decay exponent η=0.2, consistent with the Kosterlitz-Thouless-Halperin-Nelson-Young theory for a 2D crystal with a shear modulus μ=2x10 -4 N/m

Correct interpretation of diffraction properties of quartz crystals for X-ray optics applications

Energy Technology Data Exchange (ETDEWEB)

Huang, Xian-Rong; Gog, Thomas; Kim, Jungho; Kasman, Elina; Said, Ayman H.; Casa, Diego M.; Wieczorek, Michael; Hönnicke, Marcelo G.; Assoufid, Lahsen

2018-02-01

Quartz has hundreds of strong Bragg reflections that may offer a great number of choices for making fixed-angle X-ray analyzers and polarizers at virtually any hard X-ray energies with selectable resolution. However, quartz crystals, unlike silicon and germanium, are chiral and may thus appear in two different forms of handedness that are mirror images. Furthermore, because of the threefold rotational symmetry along thecaxis, the {h₁h₂h₃L} and {h₂h₁h₃L} Bragg reflections may have quite different Darwin bandwidth, reflectivity and angular acceptance, although they have the same Bragg angle. The design of X-ray optics from quartz crystals therefore requires unambiguous determination of the orientation, handedness and polarity of the crystals. The Laue method and single-axis diffraction technique can provide such information, but the variety of conventions used in the literature to describe quartz structures has caused widespread confusion. The current studies give detailed guidelines for design and fabrication of quartz X-ray optics, with special emphasis on the correct interpretation of Laue patterns in terms of the crystallography and diffraction properties of quartz. Meanwhile, the quartz crystals examined were confirmed by X-ray topography to have acceptably low densities of dislocations and other defects, which is the foundation for developing high-resolution quartz-based X-ray optics.

On the wavelength dependence of the reflectivity of one-dimensionally distorted crystals

International Nuclear Information System (INIS)

Guigay, J.P.

1986-01-01

Scaling properties of the integrated reflectivity of non-absorbing perfect or ideally imperfect crystals as a function of wavelength, in the symmetrical Laue and Bragg cases, are shown also to be valid for distorted crystals where the gradient of the lattice phase factor is perpendicular to the crystal surfaces. This result is obtained by an analysis of the Taupin-Takagi equations. Some previous experiments (test of a proposal for extinction-free measurements of F M /F N in polarized neutron scattering by magnetic crystals, and neutron diffraction from curved and non-curved crystals) are discussed from this point of view. (orig.)

Optical fibre Bragg gratings at harmonics of the Bragg wavelength and their sensing properties

International Nuclear Information System (INIS)

Collins, Stephen F; Sidiroglou, Fotios; Bal, Harpreet K; Baxter, Greg W; Wade, Scott A

2013-01-01

Spectral features in optical fibre Bragg gratings (FBGs) at various harmonics of the Bragg wavelength arise due to saturation of the writing process. Additionally, phase-mask-produced FBGs possess a complex refractive index pattern, producing an extra periodicity equal to the phase-mask periodicity that supplements the desired periodicity of half that of the phase-mask, as shown via differential interference contrast microscopy. Some spectral peaks or dips occur as doublets with a wavelength spacing that depends upon fibre alignment relative to the phase mask. These spectral properties are of importance, as they allow the realization of alternative FBG sensors of various measurands. (paper)

Development of a synthetic single crystal diamond dosimeter for dose measurement of clinical proton beams

Science.gov (United States)

Moignier, Cyril; Tromson, Dominique; de Marzi, Ludovic; Marsolat, Fanny; García Hernández, Juan Carlos; Agelou, Mathieu; Pomorski, Michal; Woo, Romuald; Bourbotte, Jean-Michel; Moignau, Fabien; Lazaro, Delphine; Mazal, Alejandro

2017-07-01

The scope of this work was to develop a synthetic single crystal diamond dosimeter (SCDD-Pro) for accurate relative dose measurements of clinical proton beams in water. Monte Carlo simulations were carried out based on the MCNPX code in order to investigate and reduce the dose curve perturbation caused by the SCDD-Pro. In particular, various diamond thicknesses were simulated to evaluate the influence of the active volume thickness (e AV) as well as the influence of the addition of a front silver resin (250 µm in thickness in front of the diamond crystal) on depth-dose curves. The simulations indicated that the diamond crystal alone, with a small e AV of just 5 µm, already affects the dose at Bragg peak position (Bragg peak dose) by more than 2% with respect to the Bragg peak dose deposited in water. The optimal design that resulted from the Monte Carlo simulations consists of a diamond crystal of 1 mm in width and 150 µm in thickness with the front silver resin, enclosed by a water-equivalent packaging. This design leads to a deviation between the Bragg peak dose from the full detector modeling and the Bragg peak dose deposited in water of less than 1.2%. Based on those optimizations, an SCDD-Pro prototype was built and evaluated in broad passive scattering proton beams. The experimental evaluation led to probed SCDD-Pro repeatability, dose rate dependence and linearity, that were better than 0.2%, 0.4% (in the 1.0-5.5 Gy min-1 range) and 0.4% (for dose higher than 0.05 Gy), respectively. The depth-dose curves in the 90-160 MeV energy range, measured with the SCDD-Pro without applying any correction, were in good agreement with those measured using a commercial IBA PPC05 plane-parallel ionization chamber, differing by less than 1.6%. The experimental results confirmed that this SCDD-Pro is suitable for measurements with standard electrometers and that the depth-dose curve perturbation is negligible, with no energy dependence and no significant dose rate

Thermal diffuse scattering in time-of-flight neutron diffraction studied on SBN single crystals

International Nuclear Information System (INIS)

Prokert, F.; Savenko, B.N.; Balagurov, A.M.

1994-01-01

At time-of-flight (TOF) diffractometer D N-2, installed at the pulsed reactor IBR-2 in Dubna, Sr x Ba 1-x Nb 2 O 6 mixed single crystals (SBN-x) of different compositions (0.50 < x< 0.75) were investigated between 15 and 773 K. The diffraction patterns were found to be strongly influenced by the thermal diffuse scattering (TDS). The appearance of the TDS from the long wavelength acoustic models of vibration in single crystals is characterized by the ratio of the velocity of sound to the velocity of neutron. Due to the nature of the TOF Laue diffraction technique used on D N-2, the TDS around Bragg peaks has rather a complex profile. An understanding of the TDS close to Bragg peaks is essential in allowing the extraction of the diffuse scattering occurring at the diffuse ferroelectric phase transition in SBN crystals. 11 refs.; 9 figs.; 1 tab. (author)

Cross-section of single-crystal materials used as thermal neutron filters

International Nuclear Information System (INIS)

Adib, M.

2005-01-01

Transmission properties of several single crystal materials important for neutron scattering instrumentation are presented. A computer codes are developed which permit the calculation of thermal diffuse and Bragg-scattering cross-sections of silicon., and sapphire as a function of material's constants, temperature and neutron energy, E, in the range 0.1 MeV .A discussion of the use of their single-crystal as a thermal neutron filter in terms of the optimum crystal thickness, mosaic spread, temperature, cutting plane and tuning for efficient transmission of thermal-reactor neutrons is given

High-resolution studies of momentum distributions using perfect crystal gamma diffractometry

International Nuclear Information System (INIS)

Krexner, G.; Bischof, G.; Jentschel, M.; Boerner, H.

2006-01-01

Full text: Positron annihilation spectroscopy has turned out to be highly successful in the investigation of Fermi surfaces, electronic structures and various kinds of defects. On the other hand, algorithms based on density functional theory have made enormous progress in recent years and calculations for the contributions of both delocalized and core electrons in a rapidly increasing number of systems is either already feasible today or to be expected in the near future. By comparison, over the last decades there has been little improvement in the experimental limitations which are still set by the energy resolution of germanium detectors (slightly above 1 keV for annihilation photons close to 500 keV) and the angular resolution in ACAR studies (superior by about one order of magnitude). In addition, coincidence techniques are hampered by low count rates. An alternative is suggested by the fact that, in principle, Bragg diffraction techniques using perfect single crystals provide a way for the precise determination of wavelengths corresponding to energies in the MeV range. The single crystal analyzer instrument PN3 at the Institute Laue-Langevin (Grenoble, France) offers the unique possibility to determine the energy of annihilation photons with an accuracy close to about 1 eV, i.e. an improvement of up to three orders of magnitude in comparison to conventional semiconductor detectors. We discuss possible applications of this spectrometer in high-resolution studies of momentum distributions for both delocalized and core electrons. (author)

Broadening of the x-ray emission line due to the instrumental function of the double-crystal spectrometer

International Nuclear Information System (INIS)

Tochio, T.; Ito, Y.; Omote, K.

2002-01-01

The influence of the instrumental function on the Cu Kα 1 emission line was investigated for the case of a double-crystal spectrometer. The magnitude of broadening for both Si(220) and Si(440) was calculated for a Lorentzian emission line with the width of 1-5 eV; the broadening for Si(220) is 0.12-0.18 eV while that for Si(440) is only 0.015-0.043 eV. The former is too large to be neglected, so the correction for the instrumental function is important. The spectrum affected by the instrumental function seems to keep the shape of Lorentzian though its width is larger. The fact indicates that the Lorentzian fitting analysis is effective if the appropriate correction for width is done

Spatial filtering with photonic crystals

Energy Technology Data Exchange (ETDEWEB)

Maigyte, Lina [Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Rambla Sant Nebridi 22, Terrassa 08222 (Spain); Staliunas, Kestutis [Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Rambla Sant Nebridi 22, Terrassa 08222 (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys 23, Barcelona 08010 (Spain)

2015-03-15

Photonic crystals are well known for their celebrated photonic band-gaps—the forbidden frequency ranges, for which the light waves cannot propagate through the structure. The frequency (or chromatic) band-gaps of photonic crystals can be utilized for frequency filtering. In analogy to the chromatic band-gaps and the frequency filtering, the angular band-gaps and the angular (spatial) filtering are also possible in photonic crystals. In this article, we review the recent advances of the spatial filtering using the photonic crystals in different propagation regimes and for different geometries. We review the most evident configuration of filtering in Bragg regime (with the back-reflection—i.e., in the configuration with band-gaps) as well as in Laue regime (with forward deflection—i.e., in the configuration without band-gaps). We explore the spatial filtering in crystals with different symmetries, including axisymmetric crystals; we discuss the role of chirping, i.e., the dependence of the longitudinal period along the structure. We also review the experimental techniques to fabricate the photonic crystals and numerical techniques to explore the spatial filtering. Finally, we discuss several implementations of such filters for intracavity spatial filtering.

The charm of protein crystals--Structural biology at a glance in the International Year of Crystallography

International Nuclear Information System (INIS)

Su Xiaodong; Cao Qin

2014-01-01

Crystallography is a typical intellectual endeavor that has spanned human history for centuries. Through the persistent efforts of generations of scientists, crystallography has been transformed from a mathematical hypothesis to actual physical reality, mainly thanks to X-ray diffraction technology. 2014 is celebrated as the International Year of Crystallography (IYCr-2014), to commemorate that about 100 years ago, when Max von Laue in Germany and the father-and-son Braggs (William Henry Bragg and William Lawrence Bragg) in England pioneered the use of X-rays to determine the atomic structure of crystals; for this pioneering work they were awarded Nobel prizes for physics in the years of 1914 and 1915. This article is dedicated to the IYCr to describe the use of protein crystals, an application that has developed into protein crystallography and subsequently structural biology. In our overview of the history and future prospects of this field, we discuss in detail one example of caspase-6, to demonstrate how protein crystallography can help us understand the structure-function relationship of important proteins. (authors)

STITCHING TYPE LARGE APERTURE DEPOLARIZER FOR GAS MONITORING IMAGING SPECTROMETER

Directory of Open Access Journals (Sweden)

X. Liu

2018-04-01

Full Text Available To increase the accuracy of radiation measurement for gas monitoring imaging spectrometer, it is necessary to achieve high levels of depolarization of the incoming beam. The preferred method in space instrument is to introduce the depolarizer into the optical system. It is a combination device of birefringence crystal wedges. Limited to the actual diameter of the crystal, the traditional depolarizer cannot be used in the large aperture imaging spectrometer (greater than 100 mm. In this paper, a stitching type depolarizer is presented. The design theory and numerical calculation model for dual babinet depolarizer were built. As required radiometric accuracies of the imaging spectrometer with 250 mm × 46 mm aperture, a stitching type dual babinet depolarizer was design in detail. Based on designing the optimum structural parmeters，the tolerance of wedge angle，refractive index, and central thickness were given. The analysis results show that the maximum residual polarization degree of output light from depolarizer is less than 2 %. The design requirements of polarization sensitivity is satisfied.

William Barlow and the Determination of Atomic Arrangement in Crystals.

Science.gov (United States)

Mauskopf, Seymour H

2015-04-01

William Barlow (1845-1934) was an important if unconventional scientist, known for having developed the 'closest-packing' atomic models of crystal structure. He resumed an early nineteenth-century tradition of utilizing crystallographical and chemical data to determine atomic arrangements in crystals. This essay recounts Barlow's career and scientific activity in three parts: (a) His place in the tradition of determining atomic arrangement in context of this earlier tradition and of contemporaneous developments of crystallography and chemistry, (b) his unconventional career, and (c) the 'success' of his program to determine atomic arrangements in crystals and its influence on the work of William Lawrence Bragg.

Spectrometric properties of crystals for low-energy x-ray diagnostics

International Nuclear Information System (INIS)

Barrus, D.m.; Blake, R.L.; Felthauser, H.; Fenimore, E.E.

1981-01-01

Quantitative diagnostics of fusion and astrophysical plasmas require knowledge of crystal spectrometric properties. To provide more reliable and versatile diagnostics of plasma conditions, increasingly accurate knowledge of crystal spectrometric properties is becoming necessary. A summary is presented of the following accurately measured parameters for the crystals KAP, RbAP, TlAP, NH 4 AP, NaAP, ADP, and EDDT: the interplanar spacing of atoms; the angle correction for normal and anomalous dispersion that is required for application of the Bragg formula; the thermal expansion coefficient near room temperature for commonly used planes; and the integrated coefficient of reflection

Dynamic strain measurement of hydraulic system pipeline using fibre Bragg grating sensors

Directory of Open Access Journals (Sweden)

Qiang Wang

2016-04-01

Full Text Available Fatigue failure is a serious problem in hydraulic piping systems installed in the machinery and equipment working in harsh operational conditions. To alleviate this problem, health monitoring of pipes can be conducted by measuring and analysing vibration-induced strain. Fibre Bragg grating is considered as a promising sensing approach for dynamic load monitoring. In this article, dynamic strain measurements based on fibre Bragg grating sensors for small-bore metal pipes have been investigated. The quasi-distributed strain sensing of fibre Bragg grating sensors is introduced. Two comparison experiments were carried out under vibration and impact loads among the methods of electrical strain gauge, piezoelectric accelerometer and fibre Bragg grating sensor. Experimental results indicate that fibre Bragg grating sensor possesses an outstanding ability to resist electromagnetic interference compared with strain gauge. The natural frequency measurement results, captured by fibre Bragg grating sensor, agree well with the modal analysis results obtained from finite element analysis. In addition, the attached fibre Bragg grating sensor brings a smaller impact on the dynamic characteristics of the measured pipe than the accelerometer due to its small size and lightweight. Fibre Bragg grating sensors have great potential for the quasi-distributed measurement of dynamic strain for the dynamic characteristic research and health monitoring of hydraulic system pipeline.

Laser sensor with Bragg gratings of fiber optics to physics parameter measuring

International Nuclear Information System (INIS)

Vazquez, R.; Garcia, C.; May, M.; Camas, J.

2009-01-01

We present the operation of a fiber laser sensor made by an Erbium Doped Fiber pumped at 980nm, an 4.23 km passive fiber and two fiber Bragg gratings placed at the ends of the laser cavity. Under normal conditions, the Bragg gratings have different reflection wavelengths and laser emission is not generated. The two Bragg gratings can be placed at the same reflection wavelength when the Bragg grating with the lowest reflective wavelength increases their temperature which can be used as a sensor element. The laser generation thus shows that the Bragg grating is increasing their temperature. We used a Peltier cell for to change gradually the temperature. (Author)

Corrugated grating on organic multilayer Bragg reflector

Science.gov (United States)

Jaquet, Sylvain; Scharf, Toralf; Herzig, Hans Peter

2007-08-01

Polymeric multilayer Bragg structures are combined with diffractive gratings to produce artificial visual color effects. A particular effect is expected due to the angular reflection dependence of the multilayer Bragg structure and the dispersion caused by the grating. The combined effects can also be used to design particular filter functions and various resonant structures. The multilayer Bragg structure is fabricated by spin-coating of two different low-cost polymer materials in solution on a cleaned glass substrate. These polymers have a refractive index difference of about 0.15 and permit multilayer coatings without interlayer problems. Master gratings of different periods are realized by laser beam interference and replicated gratings are superimposed on the multilayer structure by soft embossing in a UV curing glue. The fabrication process requires only polymer materials. The obtained devices are stable and robust. Angular dependent reflection spectrums for the visible are measured. These results show that it is possible to obtain unexpected reflection effects. A rich variety of color spectra can be generated, which is not possible with a single grating. This can be explained by the coupling of transmission of grating orders and the Bragg reflection band. A simple model permits to explain some of the spectral vs angular dependence of reflected light.

Influence of optical fiber location behind an apodized phase mask on Bragg grating reflection efficiencies at Bragg wavelength and its harmonics

Science.gov (United States)

Osuch, Tomasz; Jaroszewicz, Zbigniew

2017-01-01

An apodized fiber Bragg grating formation using a phase mask with variable duty cycle is numerically analyzed. In particular, an impact of position of an optical fiber behind the phase mask with Gaussian apodization profile on Bragg grating reflection efficiencies at Bragg wavelength and its harmonics is extensively studied. It is shown that reflection efficiency of each harmonic strongly depends on the optical fiber location with respect to the adjacent Talbot planes during the grating inscription. An analytical formula for calculation such periodical changes of reflection strength is proposed. It is also proved, that the smaller optical fiber diameter the higher fluctuations of reflectivity for particular harmonic occur. Results presented for such general case (i.e. phase mask with variable duty cycle with all non-zero diffraction orders) directly correspond to less complex structures, such as uniform phase masks and those with variable groove depth. They are also useful in optimization of Bragg wavelength and harmonic reflection efficiencies as well as in deep understanding of apodized FBG formation using aforementioned phase masks.

X-ray streak crystal spectography

International Nuclear Information System (INIS)

Kauffman, R.L.; Brown, T.; Medecki, H.

1983-01-01

We have built an x-ray streaked crystal spectrograph for making time-resolved x-ray spectral measurements. This instrument can access Bragg angles from 11 0 to 38 0 and x-ray spectra from 200 eV to greater than 10 keV. We have demonstrated resolving powers, E/δE > 200 at 1 keV and time resolution less than 20 psec. A description of the instrument and an example of the data is given

Neutron transmission of single-crystal sapphire filters

International Nuclear Information System (INIS)

Adib, M.; Kilany, M.; Habib, N.; Fathallah, M.

2005-01-01

An additive formula is given that permits the calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-sections as a function of sapphire temperature and crystal parameters. We have developed a computer program that allows calculations of the thermal neutron transmission for the sapphire rhombohedral structure and its equivalent trigonal structure. The calculated total cross-section values and effective attenuation coefficient for single-crystalline sapphire at different temperatures are compared with measured values. Overall agreement is indicated between the formula fits and experimental data. We discuss the use of sapphire single crystal as a thermal neutron filter in terms of the optimum crystal thickness, mosaic spread, temperature, cutting plane and tuning for efficient transmission of thermal-reactor neutrons. (author)

Neutron transmission of single-crystal sapphire filters

International Nuclear Information System (INIS)

Adib, M.; Kilany, M.; Habib, N.; Fathallah, M.

2004-01-01

A simple additive formula is given that permits the calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-sections as a function of sapphire temperature and crystal parameters. We have developed a computer program that allows calculations of the thermal neutron transmission for the sapphire rhombohedral structure and its equivalent trigonal structure. The calculated total cross-section values and effective attenuation coefficient for mono-crystalline sapphire at different temperatures are compared with measured values. Overall agreement is indicated between the formula fits and experimental data. We discuss the use of sapphire single-crystal as a thermal neutron filter in terms of the optimum crystal thickness, mosaic spread, temperature, cutting plane and tuning for efficient transmission of thermal-reactor neutrons

Silicon graphene Bragg gratings.

Science.gov (United States)

Capmany, José; Domenech, David; Muñoz, Pascual

2014-03-10

We propose the use of interleaved graphene sections on top of a silicon waveguide to implement tunable Bragg gratings. The filter central wavelength and bandwidth can be controlled changing the chemical potential of the graphene sections. Apodization techniques are also presented.

Miniature Photonic Spectrometers and Filters for Astrophysics and Space Science

Science.gov (United States)

Veilleux, Sylvain

This project seeks to apply our recent breakthroughs in astrophotonics - photonics applied to astronomical instrumentation - to replace the large lenses, mirrors, and gratings of conventional astronomical spectrographs with optoelectronic components borrowed from the multi-billion dollar telecommunication industry. This will reduce the mass and volume of these instruments by two to three orders of magnitudes, shorten delivery times, lower the risk, and cut the cost proportionally. Photonic instruments are also more amenable to complex light manipulation and massive multiplexing, cheaper to mass produce, easier to control, much less susceptible to vibrations and flexures, and have higher throughput. The proposed effort directly addresses one of the technology gaps identified in the 2016 Cosmic Origins Technology Report, namely the need to develop "high-performance spectral dispersion components / devices." Using private funding, we have developed photonic near-infrared (1.4 - 1.6 microns) spectrometers where the dispersing optics are replaced by miniature ( 1 cubiccentimeter) arrayed waveguide gratings imprinted using buried silicon nitride (``nanocore'') technology, the leading solution for low-loss waveguides. We have also developed highly sophisticated photonics filters using complex waveguide Bragg gratings, produced on the same platform technology as the photonic spectrometers and equally small. These prototypes have been fabricated and tested using the state-of-the-art facilities of the Maryland NanoCenter and AstroPhotonics Lab, and the results of these tests have been published in refereed publications and conference proceedings. APRA funding is now needed to develop the next generation of photonics spectrometers and filters for astrophysics and space science applications. We will (1) broaden the wavelength range to 1 - 1.7 microns, (2) increase the spectral resolving power of our photonic spectrometers from R 1500 to 3000, (3) experiment with the aspect

X-ray spectrometer having 12 000 resolving power at 8 keV energy

Science.gov (United States)

Seely, John F.; Hudson, Lawrence T.; Henins, Albert; Feldman, Uri

2017-10-01

An x-ray spectrometer employing a thin (50 μm) silicon transmission crystal was used to record high-resolution Cu Kα spectra from a laboratory x-ray source. The diffraction was from the (331) planes that were at an angle of 13.26° to the crystal surface. The components of the spectral lines resulting from single-vacancy (1s) and double-vacancy (1s and 3d) transitions were observed. After accounting for the natural lifetime widths from reference double-crystal spectra and the spatial resolution of the image plate detector, the intrinsic broadening of the transmission crystal was measured to be as small as 0.67 eV and the resolving power 12 000, the highest resolving power achieved by a compact (0.5 m long) spectrometer employing a single transmission crystal operating in the hard x-ray region. By recording spectra with variable source-to-crystal distances and comparing to the calculated widths from various geometrical broadening mechanisms, the primary contributions to the intrinsic crystal broadening were found to be the source height at small distances and the crystal apertured height at large distances. By reducing these two effects, using a smaller source size and vignetting the crystal height, the intrinsic crystal broadening is then limited by the crystal thickness and the rocking curve width and would be 0.4 eV at 8 keV energy (20 000 resolving power).

High-resolution 2-D Bragg diffraction reveal heterogeneous domain transformation behavior in a bulk relaxor ferroelectric

Energy Technology Data Exchange (ETDEWEB)

Pramanick, Abhijit, E-mail: apramani@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Kowloon (Hong Kong); Stoica, Alexandru D.; An, Ke [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2016-08-29

In-situ measurement of fine-structure of neutron Bragg diffraction peaks from a relaxor single-crystal using a time-of-flight instrument reveals highly heterogeneous mesoscale domain transformation behavior under applied electric fields. It is observed that only ∼25% of domains undergo reorientation or phase transition contributing to large average strains, while at least 40% remain invariant and exhibit microstrains. Such insights could be central for designing new relaxor materials with better performance and longevity. The current experimental technique can also be applied to resolve complex mesoscale phenomena in other functional materials.

All-Silica Hollow-Core Microstructured Bragg Fibers for Biosensor Application

DEFF Research Database (Denmark)

Passaro, Davide; Foroni, Matteo; Poli, Federica

2008-01-01

The possibility to exploit all-silica hollow-core-microstructured Bragg fibers to realize a biosensor useful to detect the DNA hybridization process has been investigated. A Bragg fiber recently fabricated has been considered for the analysis performed by means of a full-vector modal solver based...... layer on the inner surface of the fiber holes can modify the fundamental mode properties. The numerical analysis results have successfully demonstrated the DNA bio-sensor feasibility in hollow-core Bragg fibers....

The Philippine spectrometer

International Nuclear Information System (INIS)

Juliano, J.O.

1965-01-01

A notable project for international collaboration, in which participants from Indonesia, Korea, Thailand, China and the Philippines are working together, has been launched in the Philippines with Indian assistance under the aegis of the Agency. This is a regional training and research programme using a neutron crystal spectrometer, which has been established since January 1965 at the Philippine Atomic Research Centre in Diliman, Quezon City, Philippines. It is called the IPA Project after the signatories to a five year trilateral agreement, namely, the Government of India,the Republic of the Philippines, and the International Atomic Energy Agency. The programme is administered by a Joint Committee composed of one representative each of the Philippines, India and the Agency. The objective of this cooperative venture is to establish a research centre on neutron diffraction in which scientists and technicians from any Member State of IAEA in South Asia, South-East Asia and Pacific, or Far East regions could come to participate in research and training. Studies in solid state physics, such a s the structure determination of alloys and organic crystals, studies on the orientation of magnetic moments in the lattice of magnetic substances, and other problems based on elastic and inelastic scattering of neutrons are undertaken. There are a number of research reactors in this region where neutron spectrometers can be utilized and the recent establishment of this cooperative international research and training programme has been a timely one for this area of the world. Indeed, a number of other countries have shown a strong growing interest in the development of the project

X-ray diffraction at Bragg angles around π/2

International Nuclear Information System (INIS)

Mayolo, C.M.G. de.

1991-01-01

X-ray diffraction at Bragg angles around π/2 is studied from the theoretical and experimental points of view. The proposed corrections to the dynamical theory in the θ β ≅ π/2 cases, has been reviewed showing the equivalence between two formalisms leading to a corrected expression for the dependence of the angular parameter y with the angle of incidence. An expression for y valid in the conventional and θ β ≅ π/2 cases has been obtained. A general expression for Bragg law and for energy resolution after a Bragg diffraction was also deduced. (author)

Flexible Bragg reflection waveguide devices fabricated on a plastic substrate

Science.gov (United States)

Kim, Kyung-Jo; Yi, Jeong-Ah; Oh, Min-Cheol; Noh, Young-Ouk; Lee, Hyung-Jong

2007-09-01

Bragg reflecting waveguide devices are fabricated on a flexible substrate by using a post lift-off process in order to provide highly uniform grating patterns on a wide range. In this process, the flexible substrate spin-coated on silicon wafer is released after the final fabrication process of chip dicing. The fabricated flexible Bragg reflector shows very sharp transmission spectrum with 3-dB bandwidth of 0.1 nm and 10-dB bandwidth of 0.4 nm, which proves the Bragg reflector has excellent uniformity. To achieve athermal operation of the flexible Bragg reflector, thermal expansion property of the plastic substrate is controlled by the thickness of two polymer materials constructing the plastic substrate. The flexible substrate with 0.7-μm SU-8 layers sandwiching 100-μm NOA61 layer provides an optimized thermal expansion property to compensate the thermo-optic effect of the waveguide made of ZPU polymer. The temperature dependence of the Bragg reflector is decreased to -0.011 nm/°C through the incorporation of the plastic substrate.

Extinction in finite perfect crystals: Case of a sphere

International Nuclear Information System (INIS)

Al Haddad, M.; Becker, P.

1990-01-01

The extinction factor in finite perfect crystals is calculated from pure dynamical theory. In particular, a detailed solution is proposed for a sphere, in which case the extinction factor depends on the Bragg angle θ and the parameter (R/Λ), where R is the radius of the crystal and Λ the extinction length. An approximate solution based on the Laue geometry is proposed and corrections to take care of the complex boundary conditions are presented. An expression easily usable in refinement programs is proposed that fits the exact value to better than 1%. (orig.)

Resolution of a triple axis spectrometer

DEFF Research Database (Denmark)

Nielsen, Mourits; Bjerrum Møller, Hans

1969-01-01

A new method for obtaining the resolution function for a triple-axis neutron spectrometer is described, involving a combination of direct measurement and analytical calculation. All factors which contribute to the finite resolution of the instrument may be taken into account, and Gaussian...... or experimentally determined probability distributions may be used. The application to the study of the dispersion relation for excitations in a crystal is outlined...

α-rays induced background in ultra low level counting with Ge spectrometers

International Nuclear Information System (INIS)

Hubert, P.; Dassie, D.; Larrieu, P.; Leccia, F.; Mennrath, P.; Chevallier, J.; Chevallier, A.; Morales, A.; Nunez-Lagoz, R.; Morales, J.; Villar, J.A.

1986-01-01

Background spectra of several spectrometers have been recorded in a deep underground laboratory located in the Frejus tunnel. The results show that an α ray induced background from the 210 Pb decay is observed. A possible explanation could be related to the adsorption of the Rn gas on the surfaces of the Ge crystal and/or other parts during the assembly of the spectrometer. (orig.)

FOCUS: time-of-flight spectrometer for cold neutrons at SINQ

Energy Technology Data Exchange (ETDEWEB)

Janssen, S; Mesot, J [Lab. for Neutron Scattering ETH Zurich, Zurich (Switzerland) and Paul Scherrer Institute, Villigen (Switzerland); Hempelmann, R [Saarbruecken Univ., Physical Chemistry, Saarbruecken (Germany)

1996-11-01

The physical layout of the Time-Of-Flight spectrometer at the new spallation source SINQ is presented. The concept shows up a hybrid-TOF combining a Fermi-chopper with a crystal monochromator. The demand of a versatile and flexible instrument for several applications is taken into account by the option of switching from time-focusing to monochromatic focusing mode such that the spectrometer can be optimised for both quasielastic and inelastic scattering applications. (author) 5 figs., 2 tabs., 16 refs.

Enhancement of Spontaneous Erbium Emission near the Photonic Band Edge of Distributed Bragg Reflectors Based on a-Si:H/a-SiOx:H

International Nuclear Information System (INIS)

Medvedev, A.V.; Feoktistov, N.A.; Pevtsov, A.B.; Golubev, V.G.

2005-01-01

Results obtained in an experimental study of spontaneous emission from erbium ions in a spectral range corresponding to the lower photonic band edge of distributed Bragg reflectors (1D photonic crystals) are presented. The photonic crystals were constituted of alternating quarter-wave a-Si:H and a-SiO x :H layers grown by PECVD. Erbium was introduced into the a-Si:H layers by magnetron sputtering of an erbium target in the course of structure growth. The change observed in the intensity of spontaneous emission is due to the nonmonotonic behavior of the density of optical modes near the photonic band edge

Disorder in Protein Crystals.

Science.gov (United States)

Clarage, James Braun, II

1990-01-01

Methods have been developed for analyzing the diffuse x-ray scattering in the halos about a crystal's Bragg reflections as a means of determining correlations in atomic displacements in protein crystals. The diffuse intensity distribution for rhombohedral insulin, tetragonal lysozyme, and triclinic lysozyme crystals was best simulated in terms of exponential displacement correlation functions. About 90% of the disorder can be accounted for by internal movements correlated with a decay distance of about 6A; the remaining 10% corresponds to intermolecular movements that decay in a distance the order of size of the protein molecule. The results demonstrate that protein crystals fit into neither the Einstein nor the Debye paradigms for thermally fluctuating crystalline solids. Unlike the Einstein model, there are correlations in the atomic displacements, but these correlations decay more steeply with distance than predicted by the Debye-Waller model for an elastic solid. The observed displacement correlations are liquid -like in the sense that they decay exponentially with the distance between atoms, just as positional correlations in a liquid. This liquid-like disorder is similar to the disorder observed in 2-D crystals of polystyrene latex spheres, and similar systems where repulsive interactions dominate; hence, these colloidal crystals appear to provide a better analogy for the dynamics of protein crystals than perfectly elastic lattices.

Upgrade of the compact neutron spectrometer for high flux environments

Science.gov (United States)

Osipenko, M.; Bellucci, A.; Ceriale, V.; Corsini, D.; Gariano, G.; Gatti, F.; Girolami, M.; Minutoli, S.; Panza, F.; Pillon, M.; Ripani, M.; Trucchi, D. M.

2018-03-01

In this paper new version of the 6Li-based neutron spectrometer for high flux environments is described. The new spectrometer was built with commercial single crystal Chemical Vapour Deposition diamonds of electronic grade. These crystals feature better charge collection as well as higher radiation hardness. New metal contacts approaching ohmic conditions were deposited on the diamonds suppressing build-up of space charge observed in the previous prototypes. New passive preamplification of the signal at detector side was implemented to improve its resolution. This preamplification is based on the RF transformer not sensitive to high neutron flux. The compact mechanical design allowed to reduce detector size to a tube of 1 cm diameter and 13 cm long. The spectrometer was tested in the thermal column of TRIGA reactor and at the DD neutron generator. The test results indicate an energy resolution of 300 keV (FWHM), reduced to 72 keV (RMS) excluding energy loss, and coincidence timing resolution of 160 ps (FWHM). The measured data are in agreement with Geant4 simulations except for larger energy loss tail presumably related to imperfections of metal contacts and glue expansion.

Dependence of image quality on energy spread for a Bragg diffraction based radiography system

International Nuclear Information System (INIS)

Baldelli, P.; Bacci, A.; Bottigli, U.; Ferrario, M.; Gambaccini, M.; Giulietti, D.; Golosio, B.; Maroli, C.; Oliva, P.; Petrillo, V.; Serafini, L.; Stumbo, S.; Taibi, A.; Tomassini, P.; Vaccarezza, C.

2007-01-01

The aim of this work is to investigate the relationship between contrast and energy resolution of a quasi-monochromatic X-ray system based on Bragg diffraction on a mosaic crystal. Three different energies have been considered: 18, 22 and 26 keV. A commercial phantom containing large and small area details and a digital detector have been used. Results show that for large area details and for a certain value of energy, the energy spread of the incident X-ray beams produces a small reduction of the contrast, while for small area details the high reduction of the contrast is principally due to the spatial resolution properties of the system

The Text of the Agreement for conducting under the Auspices of the Agency. A Regional Joint Training and Research Programme using a Neutron Crystal Spectrometer

International Nuclear Information System (INIS)

1964-01-01

On 11 June 1964 the Board of Governors approved an Agreement for conducting, under the auspices of the Agency, a regional joint training and research programme using a neutron crystal spectrometer. The text of that Agreement is reproduced in this document for the information of all Members. The entry into force of the Agreement in accordance with Section 17 thereof, as well as later acceptances by additional Governments, will be notified to Members in addenda to this document

The Text of the Agreement for conducting under the Auspices of the Agency. A Regional Joint Training and Research Programme using a Neutron Crystal Spectrometer

Energy Technology Data Exchange (ETDEWEB)

NONE

1964-07-22

On 11 June 1964 the Board of Governors approved an Agreement for conducting, under the auspices of the Agency, a regional joint training and research programme using a neutron crystal spectrometer. The text of that Agreement is reproduced in this document for the information of all Members. The entry into force of the Agreement in accordance with Section 17 thereof, as well as later acceptances by additional Governments, will be notified to Members in addenda to this document.

Experimental demonstration of a ferroelectric liquid crystal tunable filter for fast demodulation of FBG sensors

Science.gov (United States)

Mathews, Sunish; Semenova, Yuliya; Rajan, Ginu; Farrell, Gerald

2009-05-01

A discretely tunable Surface-Stabilized Ferroelectric Liquid Crystal based Lyot Filter, with tuning speeds in the order of microseconds, is demonstrated experimentally as a channel dropper for the demodulation of multiple Fibre Bragg Grating sensors. The 3-stage Lyot Filter designed and experimentally verified can be used together with the high-speed ratiometric wavelength measurement system employing a fibre bend loss edge filter. Such systems can be used for the demodulation of distributed Fibre Bragg Grating sensors employed in applications such as structural monitoring, industrial sensing and haptic telerobotic surgical systems.

A program for the derivation of crystal unit cell parameters from X-ray powder diffraction measurements

International Nuclear Information System (INIS)

Ferguson, I.F.; Rogerson, A.H.

1984-01-01

The program, FIRESTAR, determines the dimensions of a crystallographic unit cell from a set of X-ray powder diffraction measurements corresponding to a set of Bragg reflections, provided that the crystal system applicable is known and the Bragg reflections have been indexed. The program includes a range of possible extrapolation functions, and the data may be weighted. Provision is made for detecting and rejecting a single 'bad' measurement, and then rejecting measurements which lie outside an error limit set in the input data. (orig.)

Ultrafast optical switching of three-dimensional Si inverse opal photonic band gap crystals

NARCIS (Netherlands)

Euser, T.G.; Wei, Hong; Kalkman, Jeroen; Jun, Yoonho; Polman, Albert; Norris, David J.; Vos, Willem L.

2007-01-01

We present ultrafast optical switching experiments on three-dimensional photonic band gap crystals. Switching the Si inverse opal is achieved by optically exciting free carriers by a two-photon process. We probe reflectivity in the frequency range of second order Bragg diffraction where the photonic

Bragg polaritons in a ZnSe-based unfolded microcavity at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Sebald, K.; Rahman, SK. S.; Cornelius, M.; Kaya, T.; Gutowski, J. [Semiconductor Optics, Institute of Solid State Physics, University of Bremen, 28334 Bremen (Germany); Klein, T.; Gust, A.; Hommel, D. [Semiconductor Epitaxy, Institute of Solid State Physics, University of Bremen, 28334 Bremen (Germany); Klembt, S. [Institut Néel, Université Grenoble Alpes and CNRS, B.P. 166, 38042 Grenoble (France)

2016-03-21

In this contribution, we present strong coupling of ZnSe quantum well excitons to Bragg modes resulting in the formation of Bragg polariton eigenstates, characterized by a small effective mass in comparison to a conventional microcavity. We observe an anticrossing of the excitonic and the photonic component in our sample being a clear signature for the strong-coupling regime. The anticrossing is investigated by changing the detuning between the excitonic components and the Bragg mode. We find anticrossings between the first Bragg mode and the heavy- as well as light-hole exciton, respectively, resulting in three polariton branches. The observed Bragg-polariton branches are in good agreement with theoretical calculations. The strong indication for the existence of strong coupling is traceable up to a temperature of 200 K, with a Rabi-splitting energy of 24 meV and 13 meV for the Bragg mode with the heavy- and light-hole exciton, respectively. These findings demonstrate the advantages of this sample configuration for ZnSe-based devices for the strong coupling regime.

Measurement of core plasma temperature and rotation on W7-X made available by the x-ray imaging crystal spectrometer (XICS)

Energy Technology Data Exchange (ETDEWEB)

Pablant, N A; Bitter, M; Burhenn, R; Delgado-Aparicio, L; Ellis, R; Gates, D; Goto, M; Hill, K W; Langenberg, A; Lazerson, S; Mardenfeld, M; Morita, S; Neilson, G H; Oishi, T; Pedersen, T S

2014-07-01

A new x-ray imaging crystal spectrometer diagnostic (XICS) is currently being built for installation on W7-X. This diagnostic will contribute to the study of ion and electron thermal transport and the evolution of the radial electric field by providing high resolution temperature and rotation measurements under many plasma conditions, including ECH heated plasmas. Installation is expected before the first experimental campaign (OP1.1), making an important set of measurements available for the first W7-X plasmas. This diagnostic will also work in concert with the HR-XCS diagnostic to provide an excellent diagnostic set for core impurity transport on W7-X.

Crystal growth, spectroscopic and laser properties of Tm:LuAG crystal

Science.gov (United States)

Xu, X. D.; Wang, X. D.; Lin, Z. F.; Cheng, Y.; Li, D. Z.; Cheng, S. S.; Wu, F.; Zhao, Z. W.; Gao, C. Q.; Gao, M. W.; Xu, J.

2009-11-01

Tm:Lu3Al5O12 (Tm:LuAG) crystal was grown by the Czochralski method. The segregation coefficient was measured by Inductively Coupled Plasma Atomic Emission Spectrometer. The cell parameters were analyzed with X-ray powder diffraction experiments. The absorption and fluorescence spectra of Tm:LuAG crystal at room temperature were investigated. With a 20 W fiber-coupled diode laser as pump source, the continuous-wave (CW) laser action of Tm:LuAG crystal was demonstrated. The maximum output power at 2020 nm was obtained to be 3.04 W, and the slope efficiency was 25.3%.

Piezoelectric Ca{sub 3}NbGa{sub 3}Si{sub 2}O{sub 14} crystal: crystal growth, piezoelectric and acoustic properties

Energy Technology Data Exchange (ETDEWEB)

Roshchupkin, Dmitry; Emelin, Evgenii [Russian Academy of Sciences, Institute of Microelectronics Technology and High-Purity Materials, Chernogolovka, Moscow District (Russian Federation); National University of Science and Technology MISiS, Moscow (Russian Federation); Ortega, Luc [Univ. Paris-Sud, CNRS, UMR 8502, Laboratoire de Physique des Solides, Orsay Cedex (France); Plotitcyna, Olga; Irzhak, Dmitry [Russian Academy of Sciences, Institute of Microelectronics Technology and High-Purity Materials, Chernogolovka, Moscow District (Russian Federation); Erko, Alexei; Zizak, Ivo; Vadilonga, Simone [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Institute for Nanometre Optics and Technology, Berlin (Germany); Buzanov, Oleg [FOMOS Materials Co., Moscow (Russian Federation); Leitenberger, Wolfram [Universitaet Potsdam Institut fuer Physik, Potsdam (Germany)

2016-08-15

Ca{sub 3}NbGa{sub 3}Si{sub 2}O{sub 14} (CNGS), a five-component crystal of lanthanum-gallium silicate group, was grown by the Czochralski method. The parameters of the elementary unit cell of the crystal were measured by powder diffraction. The independent piezoelectric strain coefficients d{sub 11} and d{sub 14} were determined by the triple-axis X-ray diffraction in the Bragg and Laue geometries. Excitation and propagation of surface acoustic waves (SAW) were studied by high-resolution X-ray diffraction at BESSY II synchrotron radiation source. The velocity of SAW propagation and power flow angles in the Y-, X- and yxl/+36 {sup circle} -cuts of the CNGS crystal were determined from the analysis of the diffraction spectra. The CNGS crystal was found practically isotropic by its acoustic properties. (orig.)

Nb3Sn single crystals, polycrystals and multifilamentary wires: common and different features in the magnetic response

International Nuclear Information System (INIS)

Adesso, M G; Uglietti, D; Fluekiger, R; Polichetti, M; Pace, S

2006-01-01

The magnetic response of different Nb 3 Sn samples has been investigated studying the temperature dependence of both the 1st and 3rd harmonics of the AC magnetic susceptibility, in presence of a DC field up to 19 T. In single crystal and in polycrystalline samples, the occurrence of a Peak Effect was observed within DC magnetic fields ranging from 3 T to about 13 T. It corresponds to a transition in the vortex lattice between the Bragg Glass phase and a disordered phase. This transition has been also detected at higher magnetic fields in both the samples, thanks to the 3rd harmonics measurements. In contrast to single crystals and polycrystals, no Peak Effect and no indications about the Bragg/disordered phase transition have been detected in the analysed multifilamentary wires

One-dimensional magnetophotonic crystals with magnetooptical double layers

International Nuclear Information System (INIS)

Berzhansky, V. N.; Shaposhnikov, A. N.; Prokopov, A. R.; Karavainikov, A. V.; Mikhailova, T. V.; Lukienko, I. N.; Kharchenko, Yu. N.; Golub, V. O.; Salyuk, O. Yu.; Belotelov, V. I.

2016-01-01

One-dimensional magnetophotonic microcavity crystals with nongarnet dielectric mirrors are created and investigated. The defect layers in the magnetophotonic crystals are represented by two bismuth-substituted yttrium iron garnet Bi:YIG layers with various bismuth contents in order to achieve a high magnetooptical response of the crystals. The parameters of the magnetophotonic crystal layers are optimized by numerical solution of the Maxwell equations by the transfer matrix method to achieve high values of Faraday rotation angle Θ F and magnetooptical Q factor. The calculated and experimental data agree well with each other. The maximum values of Θ F =–20.6°, Q = 8.1° at a gain t = 16 are obtained for magnetophotonic crystals with m = 7 pairs of layers in Bragg mirrors, and the parameters obtained for crystals with m = 4 and t = 8.5 are Θ F =–12.5° and Q = 14.3°. It is shown that, together with all-garnet and multimicrocavities magnetophotonic crystals, such structures have high magnetooptical characteristics.

One-dimensional magnetophotonic crystals with magnetooptical double layers

Energy Technology Data Exchange (ETDEWEB)

Berzhansky, V. N., E-mail: v.n.berzhansky@gmail.com; Shaposhnikov, A. N.; Prokopov, A. R.; Karavainikov, A. V.; Mikhailova, T. V. [V.I. Vernadsky Crimean Federal University (Russian Federation); Lukienko, I. N.; Kharchenko, Yu. N., E-mail: kharcenko@ilt.kharkov.ua [National Academy of Sciences of Ukraine, Verkin Institute for Low Temperature Physics and Engineering (Ukraine); Golub, V. O., E-mail: v-o-golub@yahoo.com; Salyuk, O. Yu. [National Academy of Sciences of Ukraine, Institute of Magnetism (Ukraine); Belotelov, V. I., E-mail: belotelov@physics.msu.ru [Russian Quantum Center (Russian Federation)

2016-11-15

One-dimensional magnetophotonic microcavity crystals with nongarnet dielectric mirrors are created and investigated. The defect layers in the magnetophotonic crystals are represented by two bismuth-substituted yttrium iron garnet Bi:YIG layers with various bismuth contents in order to achieve a high magnetooptical response of the crystals. The parameters of the magnetophotonic crystal layers are optimized by numerical solution of the Maxwell equations by the transfer matrix method to achieve high values of Faraday rotation angle Θ{sub F} and magnetooptical Q factor. The calculated and experimental data agree well with each other. The maximum values of Θ{sub F} =–20.6°, Q = 8.1° at a gain t = 16 are obtained for magnetophotonic crystals with m = 7 pairs of layers in Bragg mirrors, and the parameters obtained for crystals with m = 4 and t = 8.5 are Θ{sub F} =–12.5° and Q = 14.3°. It is shown that, together with all-garnet and multimicrocavities magnetophotonic crystals, such structures have high magnetooptical characteristics.

Optical fibre Bragg grating recorded in TOPAS cyclic olefin copolymer

DEFF Research Database (Denmark)

Johnson, I.P.; Yuan, Scott Wu; Stefani, Alessio

2011-01-01

A report is presented on the inscription of a fibre Bragg grating into a microstructured polymer optical fibre fabricated from TOPAS cyclic olefin copolymer. This material offers two important advantages over poly (methyl methacrylate), which up to now has formed the basis for polymer fibre Bragg...

Novel thermal annealing methodology for permanent tuning polymer optical fiber Bragg gratings to longer wavelengths.

Science.gov (United States)

Pospori, A; Marques, C A F; Sagias, G; Lamela-Rivera, H; Webb, D J

2018-01-22

The Bragg wavelength of a polymer optical fiber Bragg grating can be permanently shifted by utilizing the thermal annealing method. In all the reported fiber annealing cases, the authors were able to tune the Bragg wavelength only to shorter wavelengths, since the polymer fiber shrinks in length during the annealing process. This article demonstrates a novel thermal annealing methodology for permanently tuning polymer optical fiber Bragg gratings to any desirable spectral position, including longer wavelengths. Stretching the polymer optical fiber during the annealing process, the period of Bragg grating, which is directly related with the Bragg wavelength, can become permanently longer. The methodology presented in this article can be used to multiplex polymer optical fiber Bragg gratings at any desirable spectral position utilizing only one phase-mask for their photo-inscription, reducing thus their fabrication cost in an industrial setting.

Experimental Report: ORNL Proposal ID IPTS 8937

Energy Technology Data Exchange (ETDEWEB)

Mirmelstein, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2014-02-03

Neutron scattering experiment was performed using fine-resolution Fermi chopper spectrometer “SEQUOIA” installed at the Spallation Neutron Source, ORNL. Although this spectrometer is designed to measure inelastic neutron scattering spectra, during experiments a signal of elastic scattering is also recorded. The coherent nuclear component of this elastic scattering provides Bragg diffraction pattern of a sample, i.e., CeNi single crystal in our case. Therefore, it is possible to follow the CeNi structural variations as a function of pressure and to register structural phase transition. Measurements were performed at the temperature of 15 K under pressure of zero (ambient pressure at 15 K), 400, 800, and 2200 bars.

Studies of soft x-ray emission during solar flares

International Nuclear Information System (INIS)

Anandaram, M.N.

1973-01-01

Solar flare soft x-ray emission from 0.5 A to 8.5 A was observed during 1967-68 by Bragg crystal (LiF and EDDT) spectrometers aboard the OSO-4 satellite and also by NRL broad-band ionization detectors aboard the OGO-4 satellite. In this work, instrumental parameters for the LiF crystal spectrometer based on experimental values have been determined and used in the data analysis. The total continuum emission in the 0.5 to 3 A and the 1 to 8 A broad band segments has been determined from OGO-4 data for 21 flares. In doing this, a simple and approximate method of converting the total emission based on the gray body approximation (in which the OGO-4 data are reported) to one based on the thermal continuum spectrum has been developed. (author)

Bragg gratings: Optical microchip sensors

Science.gov (United States)

Watts, Sam

2010-07-01

A direct UV writing technique that can create multiple Bragg gratings and waveguides in a planar silica-on-silicon chip is enabling sensing applications ranging from individual disposable sensors for biotechnology through to multiplexed sensor networks in pharmaceutical manufacturing.

Hard X-ray diffraction enhanced imaging only using two crystals

Institute of Scientific and Technical Information of China (English)

LI Gang; WANG Nan; WU Ziyu

2004-01-01

Different configurations for the monochromator crystals and the analyzer crystals have been used in hard X-ray diffraction enhanced imaging (DEI) methods to overcome the complex task to adjust each of them to the ideal position. Here we present a very compact DEI configuration, and preliminary results of experiments performed at the Beijing Synchrotron Radiation Facility (BSRF) using only two crystals: the first one acting as monochromator and the second one as analyzer in the Bragg geometry. Refraction contrast images characterized by high contrast and spatial resolution are obtained and compared with absorption images. Differences among these images will be outlined and discussed emphasizing the potential capabilities of this very simple layout that guarantees a high transmission efficiency.

Zeonex Microstructured Polymer Optical Fibre Bragg Grating Sensor

DEFF Research Database (Denmark)

Woyessa, Getinet; Fasano, Andrea; Markos, Christos

2016-01-01

We fabricated an endlessly single mode and humidity insensitive Zeonex microstructured polymer optical fibre (mPOF) for fibre Bragg grating (FBG) temperature and strain sensors. We inscribed and characterise FBGs in Zeonex mPOF for the first time.......We fabricated an endlessly single mode and humidity insensitive Zeonex microstructured polymer optical fibre (mPOF) for fibre Bragg grating (FBG) temperature and strain sensors. We inscribed and characterise FBGs in Zeonex mPOF for the first time....

A study of point defect aggregates in #betta#-irradiated LiF single crystals

International Nuclear Information System (INIS)

Frugoli, P.A.; Pimentel, C.A.F.

1982-11-01

Diffuse X-ray scattering near the Bragg Reflection and Bragg profile analaysis have been made in #betta#-irradiated LiF single crystal X-ray diffractometer. An estimate of the half-width of the diffraction patterns was done and preferential alteration in the profile parameters was observed. Clusters with mean parameter sizes from hundreds to thousands of angstroms were observed but each sample has presented a set of average size values. The nature of clusters was found to be dependent on the #betta#-dose: vacancy at low dose (approximately 10 MRad) and interstitial at high dose (approximately 50 MRad). Some process of coalescence at 50 MRad seems to occur. (Author) [pt

Chemical state analysis of oxide thin films using a high resolution double crystal X-ray fluorescence spectrometer

International Nuclear Information System (INIS)

Masuda, Hirohisa; Morinaga, Kenji; Ohta, Yoshio.

1995-01-01

The chemical state analysis of r.f.-sputtered amorphous oxide thin films was determined by a high resolution X-ray fluorescence spectrometer with double crystals. The polymerization degree of silicate anions in the silicate film was as same as a target (α-Quartz). The oxygen coordination number of Al 3+ ions in the aluminate film was different from a target (α-Al 2 O 3 ), and it was a mixture of 4 and 6 in a spinel-like structure. In CaO-SiO 2 and CaO-Al 2 O 3 films, when the film thickness is thin at the beginning of sputtering, the composition of films are in the shortage of CaO. But when the film thickness become thicker, the composition of films become as same as the target. From the results above, the chemical state of films and their variations with film thickness can be clarified by using the apparatus. (author)

Neutron Transmission of Single-crystal Sapphire Filters

Science.gov (United States)

Adib, M.; Kilany, M.; Habib, N.; Fathallah, M.

2005-05-01

An additive formula is given that permits the calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-sections as a function of sapphire temperature and crystal parameters. We have developed a computer program that allows calculations of the thermal neutron transmission for the sapphire rhombohedral structure and its equivalent trigonal structure. The calculated total cross-section values and effective attenuation coefficient for single-crystalline sapphire at different temperatures are compared with measured values. Overall agreement is indicated between the formula and experimental data. We discuss the use of sapphire single crystal as a thermal neutron filter in terms of the optimum cystal thickness, mosaic spread, temperature, cutting plane and tuning for efficient transmission of thermal-reactor neutrons.

Guiding Properties of Silica/Air Hollow-Core Bragg Fibers

DEFF Research Database (Denmark)

Foroni, Matteo; Passaro, Davide; Poli, Federica

2008-01-01

The guiding properties of realistic silica/air hollow-core Bragg fibers have been investigated by calculating the dispersion curves, the confinement loss spectrum and the field distribution of the guided modes through a full-vector modal solver based on the finite element method. In particular, t...... the different possible applications, the feasibility of a DNA bio-sensor based on a hollow-core Bragg fiber has been demonstrated....

Bragg solitons in systems with separated nonuniform Bragg grating and nonlinearity

Science.gov (United States)

Ahmed, Tanvir; Atai, Javid

2017-09-01

The existence and stability of quiescent Bragg grating solitons are systematically investigated in a dual-core fiber, where one of the cores is uniform and has Kerr nonlinearity while the other one is linear and incorporates a Bragg grating with dispersive reflectivity. Three spectral gaps are identified in the system, in which both lower and upper band gaps overlap with one branch of the continuous spectrum; therefore, these are not genuine band gaps. However, the central band gap is a genuine band gap. Soliton solutions are found in the lower and upper gaps only. It is found that in certain parameter ranges, the solitons develop side lobes. To analyze the side lobes, we have derived exact analytical expressions for the tails of solitons that are in excellent agreement with the numerical solutions. We have analyzed the stability of solitons in the system by means of systematic numerical simulations. We have found vast stable regions in the upper and lower gaps. The effect and interplay of dispersive reflectivity, the group velocity difference, and the grating-induced coupling on the stability of solitons are investigated. A key finding is that a stronger grating-induced coupling coefficient counteracts the stabilization effect of dispersive reflectivity.

Development of gamma spectrometer using silicon photomultiplier (SiPM)

International Nuclear Information System (INIS)

Kim, Chan Kyu

2011-02-01

Gamma spectroscopy is used to determine the identity and quantity of gamma-emitters in nuclear physics, geochemistry and astrophysics. The scintillation detectors are being used as a gamma spectrometer generally, because of their higher gamma-ray detection efficiency and cheaper price than germanium semi-conductor detectors. A typical scintillation detector is composed of a scintillator, a window, and a photodetector. The photomultiplier (PM) tube has been the most widely used as a photodetector because of its advantages like high sensitivity, high signal-to-noise ratio, and wide dynamic range. Recently, the Silicon Photomultiplier (SiPM) is being studied as a substitute of PM tube. The SiPM has almost same performance compared to PM tube but it has additional advantages; low operating voltage, small volume, and cheap production cost. In this research, the gamma spectrometer using SiPM instead of PM tube is developed. The use of SiPM as a photodetector makes the gamma spectrometer smaller, cheaper, easier to use. For photon transport and collection from the large area scintillator to the small area SiPM, a light guide is applied in this gamma spectrometer system. Before fabrication of light guide, DETECT simulation is performed to study and prospect characteristics of light guide structure. And actual light guides are fabricated on the basis of this simulation result. Poly(methyl methacrylate) (PMMA) is chosen as material of light guide, 5 sample light guides are fabricated in different lengths and coatings. As a scintillator crystal, same NaI(Tl) crystal is chosen. For measurement and analysis of gamma spectrometer system, 3 gamma spectrometer systems are composed: PM tube-based system, PM tube-based system with the light guide, SiPM-based system with the light guide. Through comparison between the results of each gamma spectrometer, the performances of gamma spectrometer system are analyzed by each component. Measurement results of the second system is well

Attenuation of thermal neutrons by an imperfect single crystal

Energy Technology Data Exchange (ETDEWEB)

Naguib, K.; Adib, M. [National Research Centre, Cairo (Egypt). Reactor and Neutron Physics Dept.

1996-06-14

A semi-empirical formula is given which allows one to calculate the total thermal cross section of an imperfect single crystal as a function of crystal constants, temperature and neutron energy E, in the energy range between 3 meV and 10 eV. The formula also includes the contribution of the parasitic Bragg scattering to the total cross section that takes into account the crystal mosaic spread value and its orientation with respect to the neutron beam direction. A computer program (ISCANF) was developed to calculate the total attenuation of neutrons using the proposed formula. The ISCANF program was applied to investigate the neutron attenuation through a copper single crystal. The calculated values of the neutron transmission through the imperfect copper single crystal were fitted to the measured ones in the energy range 3-40 meV at different crystal orientations. The result of fitting shows that use of the computer program ISCANF allows one to predict the behaviour of the total cross section of an imperfect copper single crystal for the whole energy range. (author).

Attenuation of thermal neutrons by an imperfect single crystal

Science.gov (United States)

Naguib, K.; Adib, M.

1996-06-01

A semi-empirical formula is given which allows one to calculate the total thermal cross section of an imperfect single crystal as a function of crystal constants, temperature and neutron energy E, in the energy range between 3 meV and 10 eV. The formula also includes the contribution of the parasitic Bragg scattering to the total cross section that takes into account the crystal mosaic spread value and its orientation with respect to the neutron beam direction. A computer program (ISCANF) was developed to calculate the total attenuation of neutrons using the proposed formula. The ISCANF program was applied to investigate the neutron attenuation through a copper single crystal. The calculated values of the neutron transmission through the imperfect copper single crystal were fitted to the measured ones in the energy range 3 - 40 meV at different crystal orientations. The result of fitting shows that use of the computer program ISCANF allows one to predict the behaviour of the total cross section of an imperfect copper single crystal for the whole energy range.

Pemodelan Tapis Fabry-perot pada Serat Optik dengan Menggunakan Fiber Bragg Grating

OpenAIRE

Pramuliawati, Septi; ', Saktioto; ', Defrianto

2015-01-01

Fabry-perot filter was successfully developed by a uniform Fiber Bragg Grating in fiber optic. A characterization of Bragg Grating was analyzed by using computational model with second-order of Transfer Matrix Method based on Coupled Mode Theory. The reflectivity, length of grating, and bandwidth were parametrics to determine the performance of single Bragg Grating. The transmission spectrum showed the longer grating is designed, the larger the reflectivity was produced, so that the transmiss...

Strong exciton-photon coupling in organic single crystal microcavity with high molecular orientation

Energy Technology Data Exchange (ETDEWEB)

Goto, Kaname [Department of Electronics, Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Yamashita, Kenichi, E-mail: yamasita@kit.ac.jp [Faculty of Electrical Engineering and Electronics, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan); Yanagi, Hisao [Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Yamao, Takeshi; Hotta, Shu [Faculty of Materials Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan)

2016-08-08

Strong exciton-photon coupling has been observed in a highly oriented organic single crystal microcavity. This microcavity consists of a thiophene/phenylene co-oligomer (TPCO) single crystal laminated on a high-reflection distributed Bragg reflector. In the TPCO crystal, molecular transition dipole was strongly polarized along a certain horizontal directions with respect to the main crystal plane. This dipole polarization causes significantly large anisotropies in the exciton transition and optical constants. Especially the anisotropic exciton transition was found to provide the strong enhancement in the coupling with the cavity mode, which was demonstrated by a Rabi splitting energy as large as ∼100 meV even in the “half-vertical cavity surface emitting lasing” microcavity structure.

Strong exciton-photon coupling in organic single crystal microcavity with high molecular orientation

Science.gov (United States)

Goto, Kaname; Yamashita, Kenichi; Yanagi, Hisao; Yamao, Takeshi; Hotta, Shu

2016-08-01

Strong exciton-photon coupling has been observed in a highly oriented organic single crystal microcavity. This microcavity consists of a thiophene/phenylene co-oligomer (TPCO) single crystal laminated on a high-reflection distributed Bragg reflector. In the TPCO crystal, molecular transition dipole was strongly polarized along a certain horizontal directions with respect to the main crystal plane. This dipole polarization causes significantly large anisotropies in the exciton transition and optical constants. Especially the anisotropic exciton transition was found to provide the strong enhancement in the coupling with the cavity mode, which was demonstrated by a Rabi splitting energy as large as ˜100 meV even in the "half-vertical cavity surface emitting lasing" microcavity structure.

Strong exciton-photon coupling in organic single crystal microcavity with high molecular orientation

International Nuclear Information System (INIS)

Goto, Kaname; Yamashita, Kenichi; Yanagi, Hisao; Yamao, Takeshi; Hotta, Shu

2016-01-01

Strong exciton-photon coupling has been observed in a highly oriented organic single crystal microcavity. This microcavity consists of a thiophene/phenylene co-oligomer (TPCO) single crystal laminated on a high-reflection distributed Bragg reflector. In the TPCO crystal, molecular transition dipole was strongly polarized along a certain horizontal directions with respect to the main crystal plane. This dipole polarization causes significantly large anisotropies in the exciton transition and optical constants. Especially the anisotropic exciton transition was found to provide the strong enhancement in the coupling with the cavity mode, which was demonstrated by a Rabi splitting energy as large as ∼100 meV even in the “half-vertical cavity surface emitting lasing” microcavity structure.

Femtosecond X-ray diffraction from two-dimensional protein crystals

Directory of Open Access Journals (Sweden)

Matthias Frank

2014-03-01

Full Text Available X-ray diffraction patterns from two-dimensional (2-D protein crystals obtained using femtosecond X-ray pulses from an X-ray free-electron laser (XFEL are presented. To date, it has not been possible to acquire transmission X-ray diffraction patterns from individual 2-D protein crystals due to radiation damage. However, the intense and ultrafast pulses generated by an XFEL permit a new method of collecting diffraction data before the sample is destroyed. Utilizing a diffract-before-destroy approach at the Linac Coherent Light Source, Bragg diffraction was acquired to better than 8.5 Å resolution for two different 2-D protein crystal samples each less than 10 nm thick and maintained at room temperature. These proof-of-principle results show promise for structural analysis of both soluble and membrane proteins arranged as 2-D crystals without requiring cryogenic conditions or the formation of three-dimensional crystals.

Quasi-Bragg diffraction of atoms

NARCIS (Netherlands)

Domen, K.F.E.M.; Jansen, M.A.H.M.; Leeuwen, van K.A.H.

2006-01-01

We report on a novel atomic beamsplitter. It combines the advantages of Bragg scattering (transfer possible into a single, very high diffraction order due to adiabatic conservation of ‘transverse kinetic energy’) with the convenience of tuning the splitting angle simply by adjusting a magnetic

Time-Resolved Soft X-ray Diffraction Reveals Transient Structural Distortions of Ternary Liquid Crystals

Directory of Open Access Journals (Sweden)

Klaus Mann

2009-11-01

Full Text Available Home-based soft X-ray time-resolved scattering experiments with nanosecond time resolution (10 ns and nanometer spatial resolution were carried out at a table top soft X-ray plasma source (2.2–5.2 nm. The investigated system was the lyotropic liquid crystal C16E7/paraffin/glycerol/formamide/IR 5. Usually, major changes in physical, chemical, and/or optical properties of the sample occur as a result of structural changes and shrinking morphology. Here, these effects occur as a consequence of the energy absorption in the sample upon optical laser excitation in the IR regime. The liquid crystal shows changes in the structural response within few hundred nanoseconds showing a time decay of 182 ns. A decrease of the Bragg peak diffracted intensity of 30% and a coherent macroscopic movement of the Bragg reflection are found as a response to the optical pump. The Bragg reflection movement is established to be isotropic and diffusion controlled (1 μs. Structural processes are analyzed in the Patterson analysis framework of the time-varying diffraction peaks revealing that the inter-lamellar distance increases by 2.7 Å resulting in an elongation of the coherently expanding lamella crystallite. The present studies emphasize the possibility of applying TR-SXRD techniques for studying the mechanical dynamics of nanosystems.

Bragg diffraction of fermions at optical potentials; Braggbeugung von Fermionen an optischen Potentialen

Energy Technology Data Exchange (ETDEWEB)

Deh, Benjamin

2008-10-27

This thesis describes the Bragg diffraction of ultracold fermions at an optical potential. A moving optical lattice was created, by overlaying two slightly detuned lasers. Atoms can be diffracted at this lattice if the detuning fulfills the Bragg condition for resting atoms. This Bragg diffraction is analyzed systematically in this thesis. To this end Rabi oscillations between the diffraction states were driven, as well in the weakly interacting Bragg regime, as in the strongly interacting Kapitza-Dirac regime. Simulations, based on a driven two-, respectively multilevel-system describe the observed effects rather well. Furthermore, the temporal evolution of the diffracted states in the magnetic trapping potential was studied. The anharmonicity of the trap in use and the scattering cross section for p-wave collisions in a {sup 6}Li system was determined from the movement of these states. Moreover the momentum distribution of the fermions was measured with Bragg spectroscopy and first signs of Fermi degeneracy were found. Finally an interferometer with fermions was build, exhibiting a coherence time of more than 100 {mu}s. With this, the possibility for measurement and manipulation of ultracold fermions with Bragg diffraction could bee shown. (orig.)

Increasing the lasing efficiency in cholesteric liquid-crystal photonic structures

Energy Technology Data Exchange (ETDEWEB)

Palto, S. P., E-mail: palto@online.ru; Shtykov, N M; Barnik, M I; Umanskii, B A [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

2010-03-15

Two types of lasing in cholesteric liquid crystals (LCs) in the range of luminescence of laser dye molecules have been investigated. The first type belongs to the Bragg modes at the photonic band edge, which propagate along the normal to the LC layer. The second type of lasing is related to the modes leaking into the substrate and propagating at small angles to the LC layer. It is shown that the Bragg lasing efficiency can be significantly increased under wide-aperture optical pumping. The method proposed for increasing the lasing efficiency is based on suppressing the excitation of leaky laser modes using partially absorbing thin films as the coatings for LC-orienting substrates. Both experimental results and the theoretical model of the effect using the numerical simulation data are discussed.

Performance and evaluation for a single crystal gamma spectrometer in environmental laboratory

International Nuclear Information System (INIS)

Pan Jingquan

1991-01-01

The performance of a Ge(Li) spectrometer system for measuring low-level environmental γ0ray samples is presented. It has a resolution of 2 keV, and an efficiency of 30% relative to 3 by 3 inch NaI (Tl) for the 1332 keV γ-ray of 60 Co. The integral background counts of γ-ray photons is 140 ± 2 cpm in the energy range from 12 to 2000 keV. Based on applications of measuring different types of samples, it is proved that the performance of the Ge(Li) γ-spectrometer system with a 10 cm thickness lead shield, coordinating a good experimental method, will be enough for environmental sample analyses in environmental laboratory

Moiré phase-shifted fiber Bragg gratings in polymer optical fibers

DEFF Research Database (Denmark)

Min, Rui; Marques, Carlos; Bang, Ole

2018-01-01

We demonstrate a simple way to fabricate phase-shifted fiber Bragg grating in polymer optical fibers as a narrowband transmission filter for a variety of applications at telecom wavelengths. The filters have been fabricated by overlapping two uniform fiber Bragg gratings with slightly different...

Design and UV writing of advanced Bragg gratings in optical fibers

DEFF Research Database (Denmark)

Plougmann, Nikolai

2004-01-01

: · Development of a novel polarization control method for UV writing of advanced Bragg gratings with arbitrary refractive index modulation profile including multiple pi-phase shifts. · Development of a novel efficient technique for Bragg grating design which allows calculating an index modulation profile...

Electric-field-induced internal deformation in piezoelectric BiB{sub 3}O{sub 6} crystals

Energy Technology Data Exchange (ETDEWEB)

Schmidt, O.; Gorfman, S.; Pietsch, U. [Solid State Physics Department, University of Siegen (Germany)

2008-11-15

For the first time electric-field-induced atomic displacements (internal strains) in non-ferroelectric polar BiB{sub 3}O{sub 6} single crystal plates (point symmetry 2) were investigated using X-ray diffraction technique. The intensity variations of selected Bragg reflections were collected for three different orientations of the applied external electric field vector with respect to the crystal lattice and used for calculating the microscopic structural response of BiB{sub 3}O{sub 6}. Due to the limited number of the reflections providing measurable changes in Bragg intensities we restricted ourselves in analyzing the shift of the B{sub 3}O{sub 6} sublattice relative to the Bi one. In addition, we considered the deformation of the Bi-O, B(1)-O and B(2)-O bond lengths and identified the [B(2)O{sub 3}] group as the most sensitive structural unit to an external electric perturbation. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Performance of a beam-multiplexing diamond crystal monochromator at the Linac Coherent Light Source

International Nuclear Information System (INIS)

Zhu, Diling; Feng, Yiping; Lemke, Henrik T.; Fritz, David M.; Chollet, Matthieu; Glownia, J. M.; Alonso-Mori, Roberto; Sikorski, Marcin; Song, Sanghoon; Williams, Garth J.; Messerschmidt, Marc; Boutet, Sébastien; Robert, Aymeric; Stoupin, Stanislav; Shvyd'ko, Yuri V.; Terentyev, Sergey A.; Blank, Vladimir D.; Driel, Tim B. van

2014-01-01

A double-crystal diamond monochromator was recently implemented at the Linac Coherent Light Source. It enables splitting pulses generated by the free electron laser in the hard x-ray regime and thus allows the simultaneous operations of two instruments. Both monochromator crystals are High-Pressure High-Temperature grown type-IIa diamond crystal plates with the (111) orientation. The first crystal has a thickness of ∼100 μm to allow high reflectivity within the Bragg bandwidth and good transmission for the other wavelengths for downstream use. The second crystal is about 300 μm thick and makes the exit beam of the monochromator parallel to the incoming beam with an offset of 600 mm. Here we present details on the monochromator design and its performance

A comparative study of LaBr3(Ce(3+)) and CeBr3 based gamma-ray spectrometers for planetary remote sensing applications.

Science.gov (United States)

Kozyrev, A; Mitrofanov, I; Owens, A; Quarati, F; Benkhoff, J; Bakhtin, B; Fedosov, F; Golovin, D; Litvak, M; Malakhov, A; Mokrousov, M; Nuzhdin, I; Sanin, A; Tretyakov, V; Vostrukhin, A; Timoshenko, G; Shvetsov, V; Granja, C; Slavicek, T; Pospisil, S

2016-08-01

The recent availability of large volume cerium bromide crystals raises the possibility of substantially improving gamma-ray spectrometer limiting flux sensitivities over current systems based on the lanthanum tri-halides, e.g., lanthanum bromide and lanthanum chloride, especially for remote sensing, low-level counting applications or any type of measurement characterized by poor signal to noise ratios. The Russian Space Research Institute has developed and manufactured a highly sensitive gamma-ray spectrometer for remote sensing observations of the planet Mercury from the Mercury Polar Orbiter (MPO), which forms part of ESA's BepiColombo mission. The Flight Model (FM) gamma-ray spectrometer is based on a 3-in. single crystal of LaBr3(Ce(3+)) produced in a separate crystal development programme specifically for this mission. During the spectrometers development, manufacturing, and qualification phases, large crystals of CeBr3 became available in a subsequent phase of the same crystal development programme. Consequently, the Flight Spare Model (FSM) gamma-ray spectrometer was retrofitted with a 3-in. CeBr3 crystal and qualified for space. Except for the crystals, the two systems are essentially identical. In this paper, we report on a comparative assessment of the two systems, in terms of their respective spectral properties, as well as their suitability for use in planetary mission with respect to radiation tolerance and their propensity for activation. We also contrast their performance with a Ge detector representative of that flown on MESSENGER and show that: (a) both LaBr3(Ce(3+)) and CeBr3 provide superior detection systems over HPGe in the context of minimally resourced spacecraft and (b) CeBr3 is a more attractive system than LaBr3(Ce(3+)) in terms of sensitivities at lower gamma fluxes. Based on the tests, the FM has now been replaced by the FSM on the BepiColombo spacecraft. Thus, CeBr3 now forms the central gamma-ray detection element on the MPO spacecraft.

Portable scintillation gamma-spectrometer for field measurement of radioactivity in extensive objects

International Nuclear Information System (INIS)

Besshejko, O.A.; Vishnevskij, I.N.; Denisenko, R.V.; Malyuk, I.A.; Petrosyan, Eh.E.; Karpenko, S.A.; Prijmak, V.N.

2011-01-01

The portable scintillated gamma-spectrometer for field measurement of radioactivity in the volume objects was designed. The crystal CdWO 4 that has weak dependence of light yield from temperature in combination with PMT was applied as the gamma-rays detector. The design of the device provides the possibility for measuring radioactivity of the extensive objects in 4π-geometry without background measurements. In this case the value of the efficiency needed for specific activity calculation in close approximation depends only from crystal geometry and density of measuring object and may be set as the device parameter without efficiency calibration procedure during the operation. The spectrometer does not have an auxiliary radio-active source and connecting cables in the composition. The smartphone operated under Windows Mobile is used as the control module. Bluetooth connection provides data exchange between smartphone and measurement head.

A new analysis method using Bragg curve spectroscopy for a Multi-purpose Active-target Particle Telescope for radiation monitoring

Energy Technology Data Exchange (ETDEWEB)

Losekamm, M.J., E-mail: m.losekamm@tum.de; Milde, M., E-mail: michi.milde@tum.de; Pöschl, T., E-mail: thomas.poeschl@ph.tum.de; Greenwald, D.; Paul, S.

2017-02-11

Traditional radiation detectors can either measure the total radiation dose omnidirectionally (dosimeters), or determine the incoming particles characteristics within a narrow field of view (spectrometers). Instantaneous measurements of anisotropic fluxes thus require several detectors, resulting in bulky setups. The Multi-purpose Active-target Particle Telescope (MAPT), employing a new detection principle, is designed to measure particle fluxes omnidirectionally and be simultaneously a dosimeter and spectrometer. It consists of an active core of scintillating fibers whose light output is measured by silicon photomultipliers, and fits into a cube with an edge length of 10 cm. It identifies particles using extended Bragg curve spectroscopy, with sensitivity to charged particles with kinetic energies above 25 MeV. MAPT's unique layout results in a geometrical acceptance of approximately 800 cm{sup 2} sr and an angular resolution of less than 6°, which can be improved by track-fitting procedures. In a beam test of a simplified prototype, the energy resolution was found to be less than 1 MeV for protons with energies between 30 and 70 MeV. Possible applications of MAPT include the monitoring of radiation environments in spacecraft and beam monitoring in medical facilities.

Fabrication of Terahertz Wave Resonators with Alumina Diamond Photonic Crystals for Frequency Amplification in Water Solvents

International Nuclear Information System (INIS)

Ohta, N; Niki, T; Kirihara, S

2011-01-01

Terahertz wave resonators composed of alumina photonic crystals with diamond lattice structures were designed and fabricated by using micro stereolithography. These three dimensional periodic structures can reflect perfectly electromagnetic waves through Bragg diffraction. A micro glass cell including water solutions was put between the photonic crystals as a novel resonance sensor with terahertz frequency range. The localized and amplified waves in the resonators were measured by a spectroscopy, and visualized by theoretical simulations.

First results from the MAPS spectrometer at ISIS

International Nuclear Information System (INIS)

Frost, C.D.; Perring, T.G.

2001-01-01

The scientific commissioning of MAPS, the new state-of-the-art neutron scattering instrument at ISIS, has just begun. The design of MAPS has been optimised for studies of coherent excitations in single-crystals. The principal innovation is the use of position sensitive detectors that provide close to continuos coverage over a large solid angle detector array in the forward direction. The technical description of the spectrometer is presented, and examples from the first scientific experiments are used to illustrate how the position sensitive detectors coupled with easy-to-use visualisation software is already beginning to have an impact in the measurement of excitations in single crystals. (author)

First results from the MAPS spectrometer at ISIS

Energy Technology Data Exchange (ETDEWEB)

Frost, C.D.; Perring, T.G. [ISIS Facility, CLRC Rutherford Appleton Laboratory, Didcot, Oxon (United Kingdom)

2001-03-01

The scientific commissioning of MAPS, the new state-of-the-art neutron scattering instrument at ISIS, has just begun. The design of MAPS has been optimised for studies of coherent excitations in single-crystals. The principal innovation is the use of position sensitive detectors that provide close to continuos coverage over a large solid angle detector array in the forward direction. The technical description of the spectrometer is presented, and examples from the first scientific experiments are used to illustrate how the position sensitive detectors coupled with easy-to-use visualisation software is already beginning to have an impact in the measurement of excitations in single crystals. (author)

Influence of Non-uniform Temperature Field on Spectra of Fibre Bragg Grating

International Nuclear Information System (INIS)

Yan, Zhou; Xing-Fang, He; Xiao-Yong, Fang; Jie, Yuan; Li-Qun, Yin; Mao-Sheng, Cao

2009-01-01

We simulate the spectrum characteristics of fibre Bragg grating (FBG) with non-uniform temperature using the transmission matrix method, and the results are analysed. It is found that firstly the modulated coefficient of average refractive index is a very important parameter that influences the spectrum characteristic of the fibre Bragg grating, and secondly the spectrum curves are different in different temperature fields at the same parameter. Hence, we can determine the metrical temperature by analysing the spectrum of fibre Bragg grating

XFEL OSCILLATOR SIMULATION INCLUDING ANGLE-DEPENDENT CRYSTAL REFLECTIVITY

International Nuclear Information System (INIS)

Fawley, William; Lindberg, Ryan; Kim, K.-J.; Shvyd'ko, Yuri

2010-01-01

The oscillator package within the GINGER FEL simulation code has now been extended to include angle-dependent reflectivity properties of Bragg crystals. Previously, the package was modified to include frequencydependent reflectivity in order to model x-ray FEL oscillators from start-up from shot noise through to saturation. We present a summary of the algorithms used for modeling the crystal reflectivity and radiation propagation outside the undulator, discussing various numerical issues relevant to the domain of high Fresnel number and efficient Hankel transforms. We give some sample XFEL-O simulation results obtained with the angle-dependent reflectivity model, with particular attention directed to the longitudinal and transverse coherence of the radiation output.

A novel method for length of chirped fiber Bragg grating sensor

Science.gov (United States)

Li, Zhenwei; Wei, Peng; Liu, Taolin

2018-03-01

Length of chirped fiber Bragg grating sensor is very important for detonation velocity. Different from other ways, we proposed a novel method based on the optical frequency domain reflection theory to measure the length of chirped fiber grating sensor in non-contact condition. This method adopts a tunable laser source to provide wavelength scanning laser, which covers the Full Width at Half Maximum of spectrum of the chirped fiber Bragg grating sensor. A Michelson interferometer is used to produce optical interference signal. Finally, the grating's length is attainable by distance domain signal. In theory, length resolution of chirped fiber Bragg grating sensor could be 0.02 mm. We perform a series of length measurement experiments for chirped fiber grating sensor, including comparison experiments with hot-tip method. And the experiment results show that the novel method could accurately measure the length of chirped fiber Bragg grating sensors, and the length differences between the optical frequency domain reflection method and the hot-tip probe method are very small.

The XRF spectrometer and the selection of analysis conditions (instrumental variables)

International Nuclear Information System (INIS)

Willis, J.P.

2002-01-01

Full text: This presentation will begin with a brief discussion of EDXRF and flat- and curved-crystal WDXRF spectrometers, contrasting the major differences between the three types. The remainder of the presentation will contain a detailed overview of the choice and settings of the many instrumental variables contained in a modern WDXRF spectrometer, and will discuss critically the choices facing the analyst in setting up a WDXRF spectrometer for different elements and applications. In particular it will discuss the choice of tube target (when a choice is possible), the kV and mA settings, tube filters, collimator masks, collimators, analyzing crystals, secondary collimators, detectors, pulse height selection, X-ray path medium (air, nitrogen, vacuum or helium), counting times for peak and background positions and their effect on counting statistics and lower limit of detection (LLD). The use of Figure of Merit (FOM) calculations to objectively choose the best combination of instrumental variables also will be discussed. This presentation will be followed by a shorter session on a subsequent day entitled - A Selection of XRF Conditions - Practical Session, where participants will be given the opportunity to discuss in groups the selection of the best instrumental variables for three very diverse applications. Copyright (2002) Australian X-ray Analytical Association Inc

Properties of a large NaI(Tl) spectrometer for the energy measurement of high-energy gamma rays on the Gamma Ray Observatory

International Nuclear Information System (INIS)

Hughes, E.B.; Finman, L.C.; Hofstadter, R.; Lepetich, J.E.; Lin, Y.C.; Mattox, J.R.; Nolan, P.L.; Parks, R.; Walker, A.H.

1986-01-01

A large NaI(T1) spectrometer is expected to play a crucial role in the measurement of the energy spectra from an all-sky survey of high-energy celestial gamma rays on the Gamma Ray Observatory. The crystal size and requirements of space flight have resulted in a novel crystal-packaging and optics combination. The structure of this spectrometer and the operating characteristics determined in a test program using high energy positrons are described

Bragg-edge neutron transmission strain tomography for in situ loadings

Energy Technology Data Exchange (ETDEWEB)

Wensrich, C.M., E-mail: christopher.wensrich@newcastle.edu.au [School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); Hendriks, J.N.; Gregg, A. [School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); Meylan, M.H. [School of Mathematical and Physical Sciences, The University of Newcastle, Callaghan, NSW 2308 (Australia); Luzin, V. [Bragg Institute, Australian Nuclear Science and Technology Organisation (ANSTO), Kirrawee, NSW 2232 (Australia); Tremsin, A.S. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

2016-09-15

An approach for tomographic reconstruction of three-dimensional strain distributions from Bragg-edge neutron transmission strain images is outlined and investigated. This algorithm is based on the link between Bragg-edge strain measurements and the Longitudinal Ray Transform, which has been shown to be sensitive only to boundary displacement. By exploiting this observation we provide a method for reconstructing boundary displacement from sets of Bragg-edge strain images. In the case where these displacements are strictly the result of externally applied tractions, corresponding internal strain fields can then be found through traditional linear-static finite element methods. This approach is tested on synthetic data in two-dimensions, where the rate of convergence in the presence of measurement noise and beam attenuation is examined.

Improvement of soybean variety 'Bragg' through mutagenesis

Energy Technology Data Exchange (ETDEWEB)

Bhatnagar, P S; Prabhakar,; Tiwari, S P; Sandhu, J S [National Research Centre for Soybean, Indore (India)

1989-01-01

Full text: Variety 'Bragg' (Jackson x D49-2491) of soybean (Glycine max. (L.) Merrill) was found to be high yielding and widely adaptable throughout India. Its yield stability, however, is unsatisfactory, probably due to low germinability necessitating use of higher seed rate. With the main objective to rectify this defect, mutagenesis involving chemical as well as physical mutagens was used. Dry seeds were treated with EMS or MMS (0.2, 0.4 and 0.6%), or gamma rays (15, 20 and 25 kR) with and without additional exposure to UV (2 hrs at 260 nm) in 1982. In M{sub 2}, a mutation frequency ranging from 2.24 to 22.85% was observed. Screening of M{sub 2} and of subsequent generations yielded a broad spectrum of mutations. Some of the mutants are agronomically useful. Among them, mutant 'T{sub 2}14' resulting from 25 kR gamma rays + UV, was found to possess better germinability (+15%), earliness (5 days) and high yield during both rainy and post-rainy seasons in 1986 and 1987, when compared with the parent variety 'Bragg'. The mutant has smaller seed-size (TGW 125 g) than the parent (145 g). In soybean, large-seeded varieties were reported to have poorer seed germinability. Thus, the better germinability of the mutant might be related to its reduced seed size. Seeds of the mutant show a light brown colour of the hilum in contrast to the black hilum of 'Bragg'. In other characters the mutant is similar to 'Bragg'. The mutant should have potential for commercial cultivation in India. For confirmation of its agronomically superior performance, it is undergoing national evaluation in multilocational trials under 'All India Co-ordinated Research Project on Soybean (ICAR)'. The strain has been named 'NRC-2'. (author)

Improvement of soybean variety 'Bragg' through mutagenesis

International Nuclear Information System (INIS)

Bhatnagar, P.S.; Prabhakar; Tiwari, S.P.; Sandhu, J.S.

1989-01-01

Full text: Variety 'Bragg' (Jackson x D49-2491) of soybean (Glycine max. (L.) Merrill) was found to be high yielding and widely adaptable throughout India. Its yield stability, however, is unsatisfactory, probably due to low germinability necessitating use of higher seed rate. With the main objective to rectify this defect, mutagenesis involving chemical as well as physical mutagens was used. Dry seeds were treated with EMS or MMS (0.2, 0.4 and 0.6%), or gamma rays (15, 20 and 25 kR) with and without additional exposure to UV (2 hrs at 260 nm) in 1982. In M 2 , a mutation frequency ranging from 2.24 to 22.85% was observed. Screening of M 2 and of subsequent generations yielded a broad spectrum of mutations. Some of the mutants are agronomically useful. Among them, mutant 'T 2 14' resulting from 25 kR gamma rays + UV, was found to possess better germinability (+15%), earliness (5 days) and high yield during both rainy and post-rainy seasons in 1986 and 1987, when compared with the parent variety 'Bragg'. The mutant has smaller seed-size (TGW 125 g) than the parent (145 g). In soybean, large-seeded varieties were reported to have poorer seed germinability. Thus, the better germinability of the mutant might be related to its reduced seed size. Seeds of the mutant show a light brown colour of the hilum in contrast to the black hilum of 'Bragg'. In other characters the mutant is similar to 'Bragg'. The mutant should have potential for commercial cultivation in India. For confirmation of its agronomically superior performance, it is undergoing national evaluation in multilocational trials under 'All India Co-ordinated Research Project on Soybean (ICAR)'. The strain has been named 'NRC-2'. (author)

Focusing Double Bent Crystal (DBC) diffractometer for medium-resolution small-angle. Neutron scattering (SANS) experiments

International Nuclear Information System (INIS)

Mikula, P.; Wagner, V.; Scherm, R.

1991-01-01

A new modification of a focusing SANS instrument where at least the first crystal is set for diffraction in the asymmetric transmission geometry is presented. Unlike an earlier version which employed both crystals in the symmetric Bragg-case geometry, the new modification permits one simultaneously to exploit the effects of natural wavelength focusing and space condensation of the diffracted beam due to asymmetric diffraction. This DBC instrument seems to be suitable for use with beams with a large cross section at the first crystal and for SANS experiments on samples with a small width (few mm). (orig.)

Response of fiber Bragg gratings to longitudinal ultrasonic waves.

Science.gov (United States)

Minardo, Aldo; Cusano, Andrea; Bernini, Romeo; Zeni, Luigi; Giordano, Michele

2005-02-01

In the last years, fiber optic sensors have been widely exploited for several sensing applications, including static and dynamic strain measurements up to acoustic detection. Among these, fiber Bragg grating sensors have been indicated as the ideal candidate for practical structural health monitoring in light of their unique advantages over conventional sensing devices. Although this class of sensors has been successfully tested for static and low-frequency measurements, the identification of sensor performances for high-frequency detection, including acoustic emission and ultrasonic investigations, is required. To this aim, the analysis of feasibilty on the use of fiber Bragg grating sensors as ultrasonic detectors has been carried out. In particular, the response of fiber Bragg gratings subjected to the longitudinal ultrasonic (US) field has been theoretically and numerically investigated. Ultrasonic field interaction has been modeled, taking into account the direct deformation of the grating pitch combined with changes in local refractive index due to the elasto-optic effect. Numerical results, obtained for both uniform and Gaussian-apodized fiber Bragg gratings, show that the grating spectrum is strongly influenced by the US field in terms of shape and central wavelength. In particular, a key parameter affecting the grating response is the ratio between the US wavelength and the grating length. Normal operation characterized by changes in wavelength of undistorted Bragg peak is possible only for US wavelengths longer than the grating length. For US wavelengths approaching the grating length, the wavelength change is accompanied by subpeaks formation and main peak amplitude modulation. This effect can be attributed to the nonuniformity of the US perturbation along the grating length. At very high US frequencies, the grating is not sensitive any longer. The results of this analysis provide useful tools for the design of grating-based ultrasound sensors for

Improving neutron spectrometer performances through spatial and focusing effects: Investigation of spatial correlation focusing influence on the resolution in diffraction and phonon scattering experiments

International Nuclear Information System (INIS)

Popovici, M.

1986-09-01

A consistent treatment of the optics of three-axis spectrometers with curved perfect crystals, the gradient of lattice spacing accounted for, is presented. The mosaic crystal case is treated within the same computational scheme. From the computational point of view, the perfect crystals case is not the zero mosaic spread limit of the mosaic crystals case. The estimation of the residual line-widths in conditions of reciprocal-space focusing allows the discussion of the possibilities and limitations of using spatial correlation effects for improving spectrometer performances. A computer programme is presented which makes it possible to calculate both analytically and numerically the optimal arrangements and the deviations of the optimal parameter values. The optimization of parameters not involved in the analytically expressed reciprocal-space focusing conditions is also possible with this programme. The experimental results presented in this paper show that both the line-widths and the absolute intensities can also be described with reasonable accuracy for the perfect curved crystals case. It is shown experimentally that even at low-flux reactors one can obtain with the aid of perfect curved crystals good resolutions at measurable intensities which are generally higher than those obtainable in conventional spectrometers with flat mosaic crystals

Neutron transmission measurements of zinc and lead single crystals

International Nuclear Information System (INIS)

Adib, M.; Abdel-Kawy, A.

1988-01-01

Neutron transmission measurements of zinc and lead single crystals have been carried out in a neutron wavelength band from 0.03 to 0.55 nm at different orientations of the crystal with regard to the beam direction. The measurements were performed using both time-of-flight and fixed-angle scattering spectrometers installed in front of the ET-RR-1 reactor horizontal channels. It was found that the position of the observed dips in the neutron transmission measurements corresponded to the reflections from the (h k l) planes of the hexagonal zinc single crystal which was cut along the (0 0 2) plane, while in the case of lead, the single crystal was cut perpendicular to the (3 1 1) plane. The reflectivity from the (0 0 2) plane of zinc was determined using both transmission and reflection methods. The maximum reflectivity was found to be 55% when the zinc crystal was orientated at 45 0 to the beam direction. The wavelength spread of the observed reflectivity curve was found to be in agreement with the calculated one, taking into consideration the spectrometer's resolution and the crystal mosaic spread. (author)

Structure determination of disordered organic molecules on surfaces from the Bragg spots of low-energy electron diffraction and total energy calculations

International Nuclear Information System (INIS)

Poon, H.C.; Weinert, M.; Saldin, D.K.; Stacchiola, D.; Zheng, T.; Tysoe, W.T.

2004-01-01

We show that an analysis of the intensity versus energy variation of Bragg spots due to low-energy electron diffraction from a disordered overlayer of molecules on a crystal surface allows a much more convenient method of determining the local adsorption geometries of such molecules than previously analyzed weak diffuse diffraction patterns. For the case of methanol on Pd(111), we show that the geometry determined by this means from experimental diffraction data is in excellent agreement with the predictions of density functional total energy calculations

Stereotactic Bragg peak proton radiosurgery method

International Nuclear Information System (INIS)

Kjellberg, R.N.

1979-01-01

A brief description of the technical aspects of a stereotactic Bragg peak proton radiosurgical method for the head is presented. The preparatory radiographic studies are outlined and the stereotactic instrument and positioning of the patient are described. The instrument is so calibrated that after corrections for soft tissue and bone thickness, the Bragg peak superimposes upon the intracranial target. The head is rotated at specific intervals to allow predetermined portals of access for the beam path, all of which converge on the intracranial target. Normally, portals are arranged to oppose and overlap from both sides of the head. Using a number of beams (in sequence) on both sides of the head, the target dose is far greater than the path dose. The procedure normally takes 3/2-2 hours, following which the patient can walk away. (Auth./C.F.)

Precision mechanical design of an ultrahigh-resolution inelastic x-ray scattering spectrometer system with CDFDW optics at the APS

International Nuclear Information System (INIS)

Shu, D; Stoupin, S; Khachatryan, R; Goetze, K A; Roberts, T; Shvyd'ko, Y; Mundboth, K; Collins, S

2013-01-01

There are many scientific applications, especially involving topics related to the equilibrium atomic-scale dynamics of condensed matter, that require both a narrower and a steeper resolution function and access to a broader dynamic range than are currently available. To meet these important scientific needs, a prototype of a novel ultrahigh-resolution inelastic x-ray scattering spectrometer system has been designed and constructed at undulator-based beamline 30-ID at the Advanced Photon Source, Argonne National Laboratory. This prototype is designed to meet challenging mechanical and optical specifications for performing so-called CDFDW angular-dispersive x-ray crystal optics, which include a central ultra-thin CFW crystal and a pair of dispersing elements. The abbreviation CDFDW stands for: C – collimating crystal, D – dispersing-element crystal (two D-crystals are used in each CDFDW), F – anomalous transmission filter, and W – wavelength-selector crystal [1]. The mechanical design of the ultrahigh-resolution inelastic x-ray scattering spectrometer, as well as the preliminary test results of its precision positioning performance are presented in this paper.

Some effects that influence the measurement of a nuclear resonance by using of a crystal spectrometer. Alguns efeitos que influenciam a medida de uma ressonancia nuclear com um espctrometro de cristal

Energy Technology Data Exchange (ETDEWEB)

Stasiulevicius, R [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)

1993-10-01

This work describes the neutron transmission experiments aimed at evaluating the thermal resonance of [sup 176] Lu by using a crystal spectrometer located next to an irradiation channel of the IEA-R1 reactor. The iridium resonance was used to calibrate the experimental data. The effects of several phenomena affecting the measurements were also accounted for. Finally, the results were compared to values from the literature. (author).

X-Ray Reflectivity from the Surface of a Liquid Crystal:

DEFF Research Database (Denmark)

Pershan, P.S.; Als-Nielsen, Jens Aage

1984-01-01

X-ray reflectivity from the surface of a nematic liquid crystal is interpreted as the coherent superposition of Fresnel reflection from the surface and Bragg reflection from smectic order induced by the surface. Angular dependence of the Fresnel effect yields information on surface structure....... Measurement of the intensity of diffuse critical scattering relative to the Fresnel reflection yields the absolute value of the critical part of the density-density correlation function....

Polymer Optical Fibre Bragg Grating Humidity Sensor at 100ºC

DEFF Research Database (Denmark)

Woyessa, Getinet; Fasano, Andrea; Markos, Christos

2016-01-01

We have demonstrated a polymer optical fibre Bragg grating humidity sensor that can be operated up to 100ºC. The sensor has been fabricated from a polycarbonate (PC) microstructured polymer optical fibre Bragg grating (mPOFBG). PC mPOFBG gave a relative humidity (RH) sensitivity of 6.95±0.83 pm...

Portable scintillation gamma-spectrometer for field measurement of radioactivity in extensive objects

Directory of Open Access Journals (Sweden)

O. A. Bezshyyko

2011-12-01

Full Text Available The portable scintillated gamma-spectrometer for field measurement of radioactivity in the volume objects was designed. The crystal CdWO4 that has weak dependence of light yield from temperature in combination with PMT was applied as the gamma-rays detector. The design of the device provides the possibility for measuring radioactivity of the extensive objects in 4-geometry without background measurements. In this case the value of the efficiency needed for specific activity calculation in close approximation depends only from crystal geometry and density of measuring object and may be set as the device parameter without efficiency calibration procedure during the operation. The spectrometer does not have an auxiliary radio-active source and connecting cables in the composition. The smartphone operated under Windows Mobile is used as the control module. Bluetooth connection provides data exchange between smartphone and measurement head.

Growth and characterization of air annealing Tb-doped YAG:Ce single crystal for white-light-emitting diode

International Nuclear Information System (INIS)

Gong, Maogao; Xiang, Weidong; Liang, Xiaojuan; Zhong, Jiasong; Chen, Daqin; Huang, Jun; Gu, Guorui; Yang, Cheng; Xiang, Run

2015-01-01

Highlights: • We report preparation of transparent Ce,Tb:YAG single crystal by Czochralski method. • The effect of annealing on Ce,Tb:YAG single crystal had been investigated. • The Ce,Tb:YAG single crystal after annealing exhibited better optical performance. • The Ce,Tb:YAG single crystal could be used as an ideal candidate for WLED. - Abstract: We report the preparation of transparent Ce and Tb co-doped Y 3 Al 5 O 12 single crystal by the Czochralski method. The characterization of the resulting single crystal was accomplished by using X-ray powder diffractometer, scanning electron microscopy and energy dispersive X-ray spectroscopy. Absorption peak of the single crystal at about 460 nm has been obtained from ultraviolet–visible absorption spectrometer and their intensity is changed with different annealing condition. Its optical properties also have been investigated using fluorescence spectrometer. What’s more, its photoelectric parameters were studied by LED fast spectrometer. The constructed single crystal based white-light-emitting diode exhibits a high luminous efficiency of 140.89 lm/W, and a correlated color temperature of 4176 K as well as a color rendering index of 56.7, which reveal the prominent feasibility of the present single crystal material in white-light-emitting diode application

Growth and characterization of air annealing Tb-doped YAG:Ce single crystal for white-light-emitting diode

Energy Technology Data Exchange (ETDEWEB)

Gong, Maogao [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China); Xiang, Weidong, E-mail: xiangweidong001@126.com [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China); Liang, Xiaojuan [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China); Zhong, Jiasong; Chen, Daqin [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Huang, Jun; Gu, Guorui; Yang, Cheng; Xiang, Run [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China)

2015-08-05

Highlights: • We report preparation of transparent Ce,Tb:YAG single crystal by Czochralski method. • The effect of annealing on Ce,Tb:YAG single crystal had been investigated. • The Ce,Tb:YAG single crystal after annealing exhibited better optical performance. • The Ce,Tb:YAG single crystal could be used as an ideal candidate for WLED. - Abstract: We report the preparation of transparent Ce and Tb co-doped Y{sub 3}Al{sub 5}O{sub 12} single crystal by the Czochralski method. The characterization of the resulting single crystal was accomplished by using X-ray powder diffractometer, scanning electron microscopy and energy dispersive X-ray spectroscopy. Absorption peak of the single crystal at about 460 nm has been obtained from ultraviolet–visible absorption spectrometer and their intensity is changed with different annealing condition. Its optical properties also have been investigated using fluorescence spectrometer. What’s more, its photoelectric parameters were studied by LED fast spectrometer. The constructed single crystal based white-light-emitting diode exhibits a high luminous efficiency of 140.89 lm/W, and a correlated color temperature of 4176 K as well as a color rendering index of 56.7, which reveal the prominent feasibility of the present single crystal material in white-light-emitting diode application.

Scattering of x-ray from crystal surfaces

International Nuclear Information System (INIS)

Andrews, S.R.; Cowley, R.A.

1985-01-01

X-ray measurements performed on a variety of materials demonstrate that it is possible to observe diffuse scattering that originates in the abrupt change of density at a crystal surface. Such a discontinuity gives rise, in general, to rods of scattering in reciprocal space which are most intense close to the Bragg peaks tau and are well defined for sufficiently smooth surfaces. For wave-vector transfer Q=tau+q the q-dependence of the intensity of scattering gives information on the topographic structure of the crystal surface. Experimental results on crystals of GaAs and KTaO 3 , with surfaces prepared in various ways, were obtained using conventional x-ray techniques with a rotating anode source and can be described by a continuum model of the surface. There are discrepancies between the predictions of the models and the experimental results and the suggest that further experiments are needed to achieve a more complete understanding. (author)

Excitations in opal photonic crystals infiltrated with polarizable media

Science.gov (United States)

Eradat, Nayer; Sivachenko, A. Y.; Raikh, Mikhail E.; Vardeny, Z. Valy; Zakhidov, Anvar A.; Li, S.; Baughman, Ray H.

2002-12-01

Photonic crystals (PC) are a class of artificial structures with a periodic dielectric function. PCs can be a laboratory for testing fundamental processes involving interactions of radiation with matter in novel conditions. We have studied the optical properties of opal PCs that are infiltrated with highly polarizable media such as j-aggregates of cyanine dyes. Opals are self-assembled structures of silica spheres. We report our studies on clarifying the relationship between a polaritonic gap and a photonic stop band (Bragg gap) when they resonantly coexist in the same structure. Infiltration of opal with polarizable molecules combines the polaritonic and Bragg diffractive effects. Both effects exist independently when the Bragg (at ω = ωB) and polaritonic (ω = ωT) resonances are well separated in frequency. A completely different situation occurs when ωT ~ωB. Such a condition was achieved in opals that were infiltrated with J-aggregates of cyanine dyes that have large Rabi frequency. Our measurements show some dramatic changes in the shape of the reflectivity plateaus, which are due to the interplay between the photonic band gap and the polaritonic gap. The experimental results on reflectivity and its dependence on the light propagation angle and concentration of the cyanie dyes are in agreement with the theoretical calculations.

Modification to an Auger Electron Spectroscopy system for measuring segregation in a bi-crystal

CSIR Research Space (South Africa)

Jafta, CJ

2013-03-01

Full Text Available . Parameters like temperature measurement, crystal history and spectrometer variables are all adding to the complexity of directly comparing the segregation behaviour from one crystal to another. This investigation makes use of a Cu bi-crystal, modifications...

Fiber Bragg Grating Sensor for Detection of Nitrate Concentration in Water

Directory of Open Access Journals (Sweden)

A. S. LALASANGI

2011-02-01

Full Text Available The concentrations of chemical species in drinking water are of great interest. We demonstrated etched fiber Bragg grating (FBG as a concentration sensor for nitrate by analyzing the Bragg wavelength shift with concentration of chemical solution. The FBG is fabricated by phase mask technique on single mode Ge-B co-doped photosensitive fiber. Sensitivity of FBGs to the surrounding solution concentration can be enhanced by reducing diameter of the cladding with 40 % HF solution. The maximum sensitivity achieved is 1.322 ´ 10-3 nm/ppm. The overall shift of Bragg wavelength is of the order of 6.611 ´ 10-2 nm for 10 to 50 ppm concentration.

Temperature dependence of active photonic band gap in bragg-spaced quantum wells

Energy Technology Data Exchange (ETDEWEB)

Hu Zhiqiang; Wang Tao; Yu Chunchao; Xu Wei, E-mail: huzhiqianghzq@163.com [Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China)

2011-02-01

A novel all-optical polarization switch of active photonic band gap structure based on non-resonant optical Stark effect bragg-spaced quantum wells was investigated and it could be compatible with the optical communication system. The theory is based on InGaAsP/InP Bragg-spaced quantum wells (BSQWs). Mainly through the design of the InGaAsP well layer component and InP barrier thickness to make the quantum-period cycle meet the bragg condition and the bragg frequency is equal to re-hole exciton resonance frequency. When a spectrally narrow control pulse is tuned within the forbidden gap, such BSQWs have been shown to exhibit large optical nonlinearities and ps recovery times, which can form T hz switch. However, the exciton binding energy of InGaAsP will be automatically separate at room temperature, so the effect of all-optical polarization switching of active photonic band gap bragg structure quantum wells can only be studied at low temperature. By a large number of experiments, we tested part of the material parameters of BSQWs in the temperature range 10-300K. On this basis, the InGaAsP and InP refractive index changes with wavelength, InP thermal expansion coefficient are studied and a relationship equation is established. Experimental results show that the bragg reflection spectra with temperature mainly is effected by InP refractive index changes with temperature. Our theoretical study and experiment are an instruction as a reference in the designs and experiments of future practical optical switches.

Temperature dependence of active photonic band gap in bragg-spaced quantum wells

International Nuclear Information System (INIS)

Hu Zhiqiang; Wang Tao; Yu Chunchao; Xu Wei

2011-01-01

A novel all-optical polarization switch of active photonic band gap structure based on non-resonant optical Stark effect bragg-spaced quantum wells was investigated and it could be compatible with the optical communication system. The theory is based on InGaAsP/InP Bragg-spaced quantum wells (BSQWs). Mainly through the design of the InGaAsP well layer component and InP barrier thickness to make the quantum-period cycle meet the bragg condition and the bragg frequency is equal to re-hole exciton resonance frequency. When a spectrally narrow control pulse is tuned within the forbidden gap, such BSQWs have been shown to exhibit large optical nonlinearities and ps recovery times, which can form T hz switch. However, the exciton binding energy of InGaAsP will be automatically separate at room temperature, so the effect of all-optical polarization switching of active photonic band gap bragg structure quantum wells can only be studied at low temperature. By a large number of experiments, we tested part of the material parameters of BSQWs in the temperature range 10-300K. On this basis, the InGaAsP and InP refractive index changes with wavelength, InP thermal expansion coefficient are studied and a relationship equation is established. Experimental results show that the bragg reflection spectra with temperature mainly is effected by InP refractive index changes with temperature. Our theoretical study and experiment are an instruction as a reference in the designs and experiments of future practical optical switches.

Au-Spec: An Integrated Spectrometer for Terahertz Space Spectroscopy

Science.gov (United States)

Moseley, Samuel

Under APRA funding, we have developed a fully integrated R~64 submillimeter spectrometer. Using only single crystal Si and superconductors, our fabrication process is designed with the goal of minimizing loss in the spectrometer. High performance designs have been developed for all the required elements of the spectrometer. For example the slot antenna, power divider microstip delay lines, absorbers, and M icrowave Kinetic Inductance detectors (MKIDs) have been designed and buit, and the performance of a system operating at R~ 64 has been demonstrated. We l propose to develop and test a spectrometer with R~300. This device can be produced to sufficient accuracy with known fabrication tolerances. After the successful demonstration of the R~300 instrument, the devices will be ready for application in balloon or airborne applications.We will measure loss in the transmission lines to establish the limits of resolving power in such a materials system and will develop a phase adjuster to allow a diffraction limited delay network at the full resolution allowed by loss in the materials. We will demonstrate the performance of this system with R~1000 by the end of the proposed program. Arrays of such integrated spectrometers are ideal building blocks for a high redshift survey instrument, and its compact size may allow significant science to be done on Explorer Class Missions.

Calibration of a High Resolution X-ray Spectrometer for High-Energy-Density Plasmas on NIF

Science.gov (United States)

Kraus, B.; Gao, L.; Hill, K. W.; Bitter, M.; Efthimion, P.; Schneider, M. B.; Chen, H.; Ayers, J.; Beiersdorfer, P.; Liedahl, D.; Macphee, A. G.; Thorn, D. B.; Bettencourt, R.; Kauffman, R.; Le, H.; Nelson, D.

2017-10-01

A high-resolution, DIM-based (Diagnostic Instrument Manipulator) x-ray crystal spectrometer has been calibrated for and deployed at the National Ignition Facility (NIF) to diagnose plasma conditions and mix in ignition capsules near stagnation times. Two conical crystals in the Hall geometry focus rays from the Kr He- α, Ly- α, and He- β complexes onto a streak camera for time-resolved spectra, in order to measure electron density and temperature by observing Stark broadening and relative intensities of dielectronic satellites. Signals from these two crystals are correlated with a third crystal that time-integrates the intervening energy range. The spectrometer has been absolutely calibrated using a microfocus x-ray source, an array of CCD and single-photon-counting detectors, and K- and L-absorption edge filters. Measurements of the integrated reflectivity, energy range, and energy resolution for each crystal will be presented. The implications of the calibration on signal levels from NIF implosions and x-ray filter choices will be discussed. This work was performed under the auspices of the U.S. DoE by Princeton Plasma Physics Laboratory under contract DE-AC02-09CH11466 and by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

Electrically tuned photoluminescence in large pitch cholesteric liquid crystal

International Nuclear Information System (INIS)

Middha, Manju; Kumar, Rishi; Raina, K. K.

2014-01-01

Cholesteric liquid crystals are known as 1-D photonic band gap materials due to their periodic helical supramolecular structure and larger birefringence. Depending upon the helical twisted pitch length, they give the characteristic contrast due to selective Bragg reflections when viewed through the polarizing optical microscope and hence affect the electro-optic properties. So the optimization of chiral dopant concentration in nematic liquid crystal leads to control the transmission of polarized light through the microscope. Hence transmission based polarizing optical microscope is used for the characterization of helical pitch length in the optical texture. The unwinding of helical pitch was observed with the application of electric field which affects the intensity of photoluminescence

Dramatic Improvement of Crystal Quality for Low-temperature-grown Rabbit Muscle Aldolase

Energy Technology Data Exchange (ETDEWEB)

Park, H.; Rangarajan, E; Sygusch, J; Izard, T

2010-01-01

Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA-LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 {angstrom} Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA-LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice.

Dramatic improvement of crystal quality for low-temperature-grown rabbit muscle aldolase.

Science.gov (United States)

Park, Hajeung; Rangarajan, Erumbi S; Sygusch, Jurgen; Izard, Tina

2010-05-01

Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA-LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 A Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA-LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice.

In situ study of annealing-induced strain relaxation in diamond nanoparticles using Bragg coherent diffraction imaging

Directory of Open Access Journals (Sweden)

S. O. Hruszkewycz

2017-02-01

Full Text Available We observed changes in morphology and internal strain state of commercial diamond nanocrystals during high-temperature annealing. Three nanodiamonds were measured with Bragg coherent x-ray diffraction imaging, yielding three-dimensional strain-sensitive images as a function of time/temperature. Up to temperatures of 800 °C, crystals with Gaussian strain distributions with a full-width-at-half-maximum of less than 8×10−4 were largely unchanged, and annealing-induced strain relaxation was observed in a nanodiamond with maximum lattice distortions above this threshold. X-ray measurements found changes in nanodiamond morphology at temperatures above 600 °C that are consistent with graphitization of the surface, a result verified with ensemble Raman measurements.

Improved yield of high resolution mercuric iodide gamma-ray spectrometers

International Nuclear Information System (INIS)

Gerrish, V.; van den Berg, L.

1990-01-01

Mercuric iodide (HgI 2 ) exhibits properties which make it attractive for use as a solid state nuclear radiation detector. The wide bandgap (E g = 2.1 eV) and low dark current allow room temperature operation, while the high atomic number provides a large gamma-ray cross section. However, poor hole transport has been a major limitation in the routine fabrication of high-resolution spectrometers using this material. This paper presents the results of gamma-ray response and charge transport parameter measurements conducted during the past year at EG ampersand G/EM on 96 HgI 2 spectrometers. The gamma-ray response measurements reveal that detector quality is correlated with the starting material used in the crystal growth. In particular, an increased yield of high-resolution spectrometers was obtained from HgI 2 which was synthesized by precipitation from an aqueous solution, as opposed to using material from commercial vendors. Data are also presented which suggest that better spectrometer performance is tied to improved hole transport. Finally, some initial results on a study of detector uniformity reveal spatial variations which may explain why the correlation between hole transport parameters and spectrometer performance is sometimes violated. 6 refs., 3 figs

Linear and circular polarized tunable slow light in Bragg-spaced graphene layers

Energy Technology Data Exchange (ETDEWEB)

Liu, Jiang-Tao, E-mail: jtliu@semi.ac.cn [Nanoscale Science and Technology Laboratory, Institute for Advanced Study, Nanchang University, Nanchang 330031 (China); Department of Physics, Nanchang University, Nanchang 330031 (China); Liu, Nian-Hua [Nanoscale Science and Technology Laboratory, Institute for Advanced Study, Nanchang University, Nanchang 330031 (China); Department of Physics, Nanchang University, Nanchang 330031 (China); Wang, Hai [Department of Physics, Capital Normal University, Beijing 100037 (China); Wang, Tong-Biao [Department of Physics, Nanchang University, Nanchang 330031 (China); Li, Xiao-Jing [College of Physics and Energy, Fujian Normal University, Fuzhou 350007 (China)

2014-11-01

The light pulse delay in Bragg-spaced graphene layers (BSGs) combined with a magnetic field is investigated theoretically. BSGs can slow down the group velocity of light more effectively than traditional Bragg-spaced quantum wells due to the large binding energy and strong dipole oscillator strength of the magnetic-exciton of graphene. The group velocity can be tuned by varying the pulse frequency, the Bragg frequency, and the magnetic field. Especially, by tuning the occupation number of the Landau level the group velocity in BSGs shows strong tunable circular dichroism. Our findings could have applications in photonic integrated circuits and quantum computation.

System Construction for the Measurement of Bragg Grating Characteristics in Optical Fibers

Science.gov (United States)

West, Douglas P.

1995-01-01

Bragg gratings are used to measure strain in optical fibers. To measure strain they are sometimes used as a smart structure. They must be characterized after they are written to determine their spectral response. This paper deals with the test setup to characterize Bragg grating spectral responses.Bragg gratings are a photo-induced phenomena in optical fibers. The gratings can be used to measure strain by measuring the shift in wavelength. They placed the fibers into a smart structure to measure the stress and strain produced on support columns placed in bridges. As the cable is subjected to strain the grating causes a shift to a longer wavelength if the fiber is stretched and a shift to a shorter wavelength shift if the fiber is compacted. Our applications involve using the fibers to measure stress and strain on airborne systems. There are many ways to write Bragg gratings into optical fibers. Our focus is on side writing the grating. Our capabilities are limited in the production rate of the gratings. The Bragg grating is written into a fiber and becomes a permanent fixture. We are writing the grating to be centered at 1300 nm because that is the standard phase mask wavelength.

Polarized neutron scattering on HYSPEC: the HYbrid SPECtrometer at SNS

OpenAIRE

Zaliznyak, Igor A; Savici, Andrei T.; Garlea, V. Ovidiu; Winn, Barry; Filges, Uwe; Schneeloch, John; Tranquada, John M.; Gu, Genda; Wang, Aifeng; Petrovic, Cedomir

2016-01-01

We describe some of the first polarized neutron scattering measurements performed at HYSPEC spectrometer at the Spallation Neutron Source, Oak Ridge National Laboratory. We discuss details of the instrument setup and the experimental procedures in the mode with full polarization analysis. Examples of polarized neutron diffraction and polarized inelastic neutron data obtained on single crystal samples are presented.

High frequency time modulation of neutrons by LiNbO3 crystals with surface acoustic waves excited under the diffraction condition

International Nuclear Information System (INIS)

Takahashi, Toshio; Granzer, E.; Kikuta, Seishi; Tomimitsu, Hiroshi; Doi, Kenji.

1985-01-01

High frequency time modulation of neutrons was investigated by using Y-cut LiNbO 3 crystals with surface acoustic waves excited. A double crystal arrangement of (+, -) parallel setting was used for 030 symmetric Bragg-case reflections. Synchronized standing waves with a resonance frequency of 14.26 MHz were excited on the both crystals. Variation of the diffracted intensity with phase difference between two standing waves was studied. The result showed an intensity change of diffracted neutrons with twice the resonance frequency. (author)

Electro-optic imaging Fourier transform spectrometer

Science.gov (United States)

Chao, Tien-Hsin (Inventor); Znod, Hanying (Inventor)

2009-01-01

An Electro-Optic Imaging Fourier Transform Spectrometer (EOIFTS) for Hyperspectral Imaging is described. The EOIFTS includes an input polarizer, an output polarizer, and a plurality of birefringent phase elements. The relative orientations of the polarizers and birefringent phase elements can be changed mechanically or via a controller, using ferroelectric liquid crystals, to substantially measure the spectral Fourier components of light propagating through the EIOFTS. When achromatic switches are used as an integral part of the birefringent phase elements, the EIOFTS becomes suitable for broadband applications, with over 1 micron infrared bandwidth.

Wavevector and energy resolution of the polarized diffuse scattering spectrometer D7

Energy Technology Data Exchange (ETDEWEB)

Fennell, T., E-mail: tom.fennell@psi.ch [Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Mangin-Thro, L., E-mail: mangin-throl@ill.fr [Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156 - 38042 Grenoble Cedex 9 (France); Mutka, H., E-mail: mutka@ill.fr [Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156 - 38042 Grenoble Cedex 9 (France); Nilsen, G.J., E-mail: goran.nilsen@stfc.ac.uk [ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot OX11 0QX (United Kingdom); Wildes, A.R., E-mail: wildes@ill.fr [Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156 - 38042 Grenoble Cedex 9 (France)

2017-06-11

The instrumental divergence parameters and resolution for the D7 neutron diffuse scattering spectrometer at the Institut Laue-Langevin, France, are presented. The resolution parameters are calibrated against measurements of powders, single crystals, and the incoherent scattering from vanadium. We find that the powder diffraction resolution is well described by the Cagliotti function, the single crystal resolution function can be parameterized using the Cooper-Nathans formalism, and that in time-of-flight mode the energy resolution is consistent with monochromatic focussing.

Sensitivity of triple-crystal X-ray diffractometers to microdefects in silicon

International Nuclear Information System (INIS)

Molodkin, V.B.; Olikhovskii, S.I.; Len, E.G.; Kislovskii, E.N.; Kladko, V.P.; Reshetnyk, O.V.; Vladimirova, T.P.; Sheludchenko, B.V.

2009-01-01

The dynamical theory, which describes both diffraction profiles and reciprocal space maps measured from imperfect crystals with account for instrumental factors of triple-crystal diffractometer (TCD), has been developed for adequate quantitative characterization of microdefects. Analytical expressions for coherent and diffuse scattering (DS) intensities measured by TCD in the Bragg diffraction geometry have been derived by using the generalized statistical dynamical theory of X-ray scattering in real single crystals with randomly distributed defects. The DS intensity distributions from single crystals containing clusters and dislocation loops have been described by explicit analytical expressions. Particularly, these expressions take into account anisotropy of displacement fields around defects with discrete orientations. Characteristics of microdefect structures in silicon single crystals grown by Czochralsky- and float-zone methods have been determined by analyzing the measured TCD profiles and reciprocal space maps. The sensitivities of reciprocal space maps and diffraction profiles to defect characteristics have been compared. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Fiber-optical accelerometers based on polymer optical fiber Bragg gratings

DEFF Research Database (Denmark)

Yuan, Scott Wu; Stefani, Alessio; Bang, Ole

2010-01-01

Fiber-optical accelerometers based on polymer optical fiber Bragg gratings (FBGs) are reported. We have written 3mm FBGs for 1550nm operation, characterized their temperature and strain response, and tested their performance in a prototype accelerometer.......Fiber-optical accelerometers based on polymer optical fiber Bragg gratings (FBGs) are reported. We have written 3mm FBGs for 1550nm operation, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

Experimental Search for Solar Axions via Coherent Primakoff Conversion in a Germanium Spectrometer

CERN Document Server

Avignone, F T; Brodzinski, R; Collar, J I; Creswick, R J; Di Gregorio, D E; Farach, H A; Gattone, A O; Guérard, C K; Hasenbalg, F; Huck, H; Miley, H S; Morales, A; Morales, J; Nussinov, S; De Solorzano, A O; Reeves, J H; Villar, J; Zioutas, Konstantin

1998-01-01

Results are reported of an experimental search for the unique, rapidly varying temporal pattern of solar axions coherently converting into photons via the Primakoff effect in a single crystal germanium detector. This conversion is predicted when axions are incident at a Bragg angle with a crystalline plane. The analysis of approximately 1.94 kg.yr of data from the 1 kg DEMOS detector in Sierra Grande, Argentina, yields a new laboratory bound on axion-photon coupling of $g_{a\\gamma \\gamma} < 2.7\\cdot 10^{-9}$ GeV$^{-1}$, independent of axion mass up to ~ 1 keV.

Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystals

International Nuclear Information System (INIS)

Haugh, M. J.; Jacoby, K. D.; Wu, M.; Loisel, G. P.

2014-01-01

This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories in Albuquerque, New Mexico. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a double crystal diffractometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed

Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystals

Energy Technology Data Exchange (ETDEWEB)

Haugh, M. J., E-mail: haughmj@nv.doe.gov; Jacoby, K. D. [National Security Technologies, LLC, Livermore, California 94550 (United States); Wu, M.; Loisel, G. P. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)

2014-11-15

This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories in Albuquerque, New Mexico. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a double crystal diffractometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.

UV writing of advanced Bragg gratings in optical waveguides

DEFF Research Database (Denmark)

Jensen, Jesper Bo Damm

2002-01-01

of the novel polarization control method for UV writing of Bragg gratings with advanced apodization profiles including phase shifts. The principle of the polarization control method relies on a spatial separation of the s- and p-polarized components of a linearly polarized UV beam corresponding to half......, Technical University of Denmark. During fabrication the planar waveguides were annealed in an oxygen rich atmosphere. This reduces the photosensitivity to a negligible level and Bragg gratings cannot be written within reasonable time unless the waveguides are sensitized by deuterium loading. Samples were...

Long-term radiation damage to a spaceborne germanium spectrometer

CERN Document Server

Kurczynski, P; Hull, E L; Palmer, D; Harris, M J; Seifert, H; Teegarden, B J; Gehrels, N; Cline, T L; Ramaty, R; Sheppard, D; Madden, N W; Luke, P N; Cork, C P; Landis, D A; Malone, D F; Hurley, K

1999-01-01

The Transient Gamma-Ray Spectrometer aboard the Wind spacecraft in deep space has observed gamma-ray bursts and solar events for four years. The germanium detector in the instrument has gradually deteriorated from exposure to the approx 10 sup 8 p/cm sup 2 /yr(>100 MeV) cosmic-ray flux. Low-energy tailing and loss of efficiency, attributed to hole trapping and conversion of the germanium from n- to p-type as a result of crystal damage, were observed. Raising the detector bias voltage ameliorated both difficulties and restored the spectrometer to working operation. Together, these observations extend our understanding of the effects of radiation damage to include the previously unsuccessfully studied regime of long-term operation in space. (author)

A comparative study of LaBr{sub 3}(Ce{sup 3+}) and CeBr{sub 3} based gamma-ray spectrometers for planetary remote sensing applications

Energy Technology Data Exchange (ETDEWEB)

Kozyrev, A., E-mail: kozyrev@mx.iki.rssi.ru; Mitrofanov, I.; Bakhtin, B.; Fedosov, F.; Golovin, D.; Litvak, M.; Malakhov, A.; Mokrousov, M.; Nuzhdin, I.; Sanin, A.; Tretyakov, V.; Vostrukhin, A. [Space Research Institute of the Russian Academy of Sciences (IKI), 84/32 Profsoyuznaya St., Moscow 117997 (Russian Federation); Owens, A.; Benkhoff, J. [European Space Agency, ESTEC, Keplerlaan, 2200 AG Noordwijk (Netherlands); Quarati, F. [AP, RST, FAME, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Gonitec BV, J. Bildersstraat 60, 2596 EJ Den Haag (Netherlands); Timoshenko, G.; Shvetsov, V. [Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980 (Russian Federation); Granja, C.; Slavicek, T.; Pospisil, S. [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, 12800 Prague 2 (Czech Republic)

2016-08-15

The recent availability of large volume cerium bromide crystals raises the possibility of substantially improving gamma-ray spectrometer limiting flux sensitivities over current systems based on the lanthanum tri-halides, e.g., lanthanum bromide and lanthanum chloride, especially for remote sensing, low-level counting applications or any type of measurement characterized by poor signal to noise ratios. The Russian Space Research Institute has developed and manufactured a highly sensitive gamma-ray spectrometer for remote sensing observations of the planet Mercury from the Mercury Polar Orbiter (MPO), which forms part of ESA’s BepiColombo mission. The Flight Model (FM) gamma-ray spectrometer is based on a 3-in. single crystal of LaBr{sub 3}(Ce{sup 3+}) produced in a separate crystal development programme specifically for this mission. During the spectrometers development, manufacturing, and qualification phases, large crystals of CeBr{sub 3} became available in a subsequent phase of the same crystal development programme. Consequently, the Flight Spare Model (FSM) gamma-ray spectrometer was retrofitted with a 3-in. CeBr{sub 3} crystal and qualified for space. Except for the crystals, the two systems are essentially identical. In this paper, we report on a comparative assessment of the two systems, in terms of their respective spectral properties, as well as their suitability for use in planetary mission with respect to radiation tolerance and their propensity for activation. We also contrast their performance with a Ge detector representative of that flown on MESSENGER and show that: (a) both LaBr{sub 3}(Ce{sup 3+}) and CeBr{sub 3} provide superior detection systems over HPGe in the context of minimally resourced spacecraft and (b) CeBr{sub 3} is a more attractive system than LaBr{sub 3}(Ce{sup 3+}) in terms of sensitivities at lower gamma fluxes. Based on the tests, the FM has now been replaced by the FSM on the BepiColombo spacecraft. Thus, CeBr{sub 3} now forms

Interrogation of weak Bragg grating sensors based on dual-wavelength differential detection.

Science.gov (United States)

Cheng, Rui; Xia, Li

2016-11-15

It is shown that for weak Bragg gratings the logarithmic ratio of reflected intensities at any two wavelengths within the spectrum follows a linear relationship with the Bragg wavelength shift, with a slope proportional to their wavelength spacing. This finding is exploited to develop a flexible, efficient, and cheap interrogation solution of weak fiber Bragg grating (FBGs), especially ultra-short FBGs, in distributed sensing based on dual-wavelength differential detection. The concept is experimentally studied in both single and distributed sensing systems with ultra-short FBG sensors. The work may form the basis of new and promising FBG interrogation techniques based on detecting discrete rather than continuous spectra.

Ionoacoustic characterization of the proton Bragg peak with submillimeter accuracy

Energy Technology Data Exchange (ETDEWEB)

Assmann, W., E-mail: walter.assmann@lmu.de; Reinhardt, S.; Lehrack, S.; Edlich, A.; Thirolf, P. G.; Parodi, K. [Department for Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, Garching 85748 (Germany); Kellnberger, S.; Omar, M.; Ntziachristos, V. [Institute for Biological and Medical Imaging, Technische Universität München and Helmholtz Zentrum München, Ingolstädter Landstrasse 1, Neuherberg 85764 (Germany); Moser, M.; Dollinger, G. [Institute for Applied Physics and Measurement Technology, Universität der Bundeswehr, Werner-Heisenberg-Weg 39, Neubiberg 85577 (Germany)

2015-02-15

Purpose: Range verification in ion beam therapy relies to date on nuclear imaging techniques which require complex and costly detector systems. A different approach is the detection of thermoacoustic signals that are generated due to localized energy loss of ion beams in tissue (ionoacoustics). Aim of this work was to study experimentally the achievable position resolution of ionoacoustics under idealized conditions using high frequency ultrasonic transducers and a specifically selected probing beam. Methods: A water phantom was irradiated by a pulsed 20 MeV proton beam with varying pulse intensity and length. The acoustic signal of single proton pulses was measured by different PZT-based ultrasound detectors (3.5 and 10 MHz central frequencies). The proton dose distribution in water was calculated by Geant4 and used as input for simulation of the generated acoustic wave by the matlab toolbox k-WAVE. Results: In measurements from this study, a clear signal of the Bragg peak was observed for an energy deposition as low as 10{sup 12} eV. The signal amplitude showed a linear increase with particle number per pulse and thus, dose. Bragg peak position measurements were reproducible within ±30 μm and agreed with Geant4 simulations to better than 100 μm. The ionoacoustic signal pattern allowed for a detailed analysis of the Bragg peak and could be well reproduced by k-WAVE simulations. Conclusions: The authors have studied the ionoacoustic signal of the Bragg peak in experiments using a 20 MeV proton beam with its correspondingly localized energy deposition, demonstrating submillimeter position resolution and providing a deep insight in the correlation between the acoustic signal and Bragg peak shape. These results, together with earlier experiments and new simulations (including the results in this study) at higher energies, suggest ionoacoustics as a technique for range verification in particle therapy at locations, where the tumor can be localized by ultrasound

Trial fabrication of a secondary x-ray spectrometer with high energy resolution for use in x-ray resonant inelastic scattering experiments

International Nuclear Information System (INIS)

Iwazumi, Toshiaki

2004-01-01

An instrument was fabricated for use of x-ray resonant inelastic scattering with high-energy resolution in expectation of finding new physical phenomena in strongly correlated electron systems. In the scattering x-ray spectrometer, an asymmetric Johanson crystal spectrometer, which was deployed in an asymmetric Rowland configuration, was designed, fabricated and assessed. The performance expected theoretically for the Johanson spectrometer was recognized from experiments by use of synchrotron radiation. (Y. Kazumata)

Characterization of nova plasmas using an x-ray spectrometer with temporal and spatial resolution

International Nuclear Information System (INIS)

Back, C.A.; Kauffman, R.L.; Bell, P.; Kilkenny, J.D.

1994-05-01

Spectroscopic diagnostics have great potential to obtain high temperature measurements of plasmas created in ICF targets. The plasmas may be over 1 mm in size and therefore, one of the first steps in making accurate spectroscopic measurements has been to improve the resolution of the instrument. A spectrograph is now available for Nova experiments which takes advantage of gated technology by coupling a Bragg crystal to a microchannel plate that can record data over a 250 ps time frame. The crystal disperses the x-rays, while slits add the ability to image the plasmas in the perpendicular direction. The characteristics of this diagnostic, TSPEC, will be evaluated for laser-produced plasmas. Recent data will be presented from colliding plasmas and large-scale hohlraums which indicate that imaging can greatly enhance the ability to diagnose these plasmas

Compact, rugged in-chamber transmission spectrometers (7-28 keV) for the Sandia Z facility.

Science.gov (United States)

Sinars, D B; Wenger, D F; Pikuz, S A; Jones, B; Geissel, M; Hansen, S B; Coverdale, C A; Ampleford, D J; Cuneo, M E; McPherson, L A; Rochau, G A

2011-06-01

We describe a pair of time-integrated transmission spectrometers that are designed to survey 7-28 keV (1.9 to 0.43 Å) x-ray photons produced by experiments on the Sandia Z pulsed power facility. Each spectrometer uses a quartz 10-11 crystal in a Cauchois geometry with a slit to provide spatial resolution along one dimension. The spectrometers are located in the harsh environment of the Z vacuum chamber, which necessitates that their design be compact and rugged. Example data from calibration tests and Z experiments are shown that illustrate the utility of the instruments. © 2011 American Institute of Physics

GIOVE, a shallow laboratory Ge-spectrometer with 100 μBq/kg sensitivity

Energy Technology Data Exchange (ETDEWEB)

Heusser, G.; Weber, M.; Denz, T.; Hakenmueller, J.; Hofacker, R.; Lackner, R.; Lindner, M.; Maneschg, W.; Reisfelder, M.; Simgen, H.; Schreiner, J.; Stolzenburg, D.; Strecker, H.; Westermann, J. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)

2013-08-08

A new germanium gamma spectrometer called GIOVE (Germanium spectrometer with Inner and Outer Veto) has been set up at the underground/shallow laboratory (15 m w.e.) of MPI-K. Its double plastic scintillator veto system and neutron moderation interlayer lower the background by more than one order of magnitude compared to the other existing spectrometer at this facility. The integral (40-2700 keV) background rate of about 290 counts (day kg){sup −1} is just a factor 4 to 8 above that of the GeMPI spectrometers operated at LNGS (3800 m w.e.) and thus proves that even under shallow overburden sub mBq/kg sensitivities are achievable. Extended material screening and neutron attenuation studies preceded the final design of the spectrometer. The technical realization of the spectrometer is described in detail with special emphasis on the inner veto system. For its optimisation a simulation model was developed for light collection on small low activity PMT’s under various geometrical conditions. Radon suppression is accomplished by employing a gas tight sample container and a nitrogen flushed glove-box system with an airlock. The active volume of the crystal was modelled by absorption scanning measurements and Monte Carlo simulations. The complete shield is implemented in a Geant4 based simulation framework.

Mode splitting effect in FEMs with oversized Bragg resonators

Energy Technology Data Exchange (ETDEWEB)

Peskov, N. Yu.; Sergeev, A. S. [Institute of Applied Physics Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Kaminsky, A. K.; Perelstein, E. A.; Sedykh, S. N. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Kuzikov, S. V. [Institute of Applied Physics Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Nizhegorodsky State University, Nizhny Novgorod (Russian Federation)

2016-07-15

Splitting of the fundamental mode in an oversized Bragg resonator with a step of the corrugation phase, which operates over the feedback loop involving the waveguide waves of different transverse structures, was found to be the result of mutual influence of the neighboring zones of the Bragg scattering. Theoretical description of this effect was developed within the framework of the advanced (four-wave) coupled-wave approach. It is shown that mode splitting reduces the selective properties, restricts the output power, and decreases the stability of the narrow-band operating regime in the free-electron maser (FEM) oscillators based on such resonators. The results of the theoretical analysis were confirmed by 3D simulations and “cold” microwave tests. Experimental data on Bragg resonators with different parameters in a 30-GHz FEM are presented. The possibility of reducing the mode splitting by profiling the corrugation parameters is shown. The use of the mode splitting effect for the output power enhancement by passive compression of the double-frequency pulse generated in the FEM with such a resonator is discussed.

Dramatic improvement of crystal quality for low-­temperature-grown rabbit muscle aldolase

Science.gov (United States)

Park, HaJeung; Rangarajan, Erumbi S.; Sygusch, Jurgen; Izard, Tina

2010-01-01

Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA–LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice. PMID:20445268

An EXAFS spectrometer on beam line 10B at the Photon Factory

International Nuclear Information System (INIS)

Oyanagi, Hiroyuki; Matsushita, Tadashi; Ito, Masahisa; Kuroda, Haruo.

1984-03-01

An EXAFS spectrometer installed on the beam line 10B at the Photon Factory is designed to cover the photon energy between 4 and 30 keV. Utilizing either a channel-cut or two flat silicon crystals as a monochromator, a beam intensity between 10 8 and 10 9 photons/sec is obtained at 9 keV with a resolution of 1 eV. The performance of the spectrometer, such as a signal-to-noise ratio or an energy resolution is demonstrated with examples of K edge absorption spectra of bromine, germanium, gallium arsenide, and zinc selenide. (author)

A BaF2 crystal array for high energy -ray measurements

Indian Academy of Sciences (India)

A very well-known such array is called two-arm-photon- spectrometer (TAPS) [1]. It consists of large (25 cm long) hexagonal BaF¾ crystals ar- ranged in packs of 64 crystals. ... light which may not reach the photomultiplier tube. A sketch of the ...

PROTECTIVE COATINGS OF FIBER BRAGG GRATING FOR MINIMIZING OF MECHANICAL IMPACT ON ITS WAVELENGTH CHARACTERISTICS

Directory of Open Access Journals (Sweden)

A. S. Munko

2015-03-01

Full Text Available The paper deals with the scheme for the study of the Bragg wavelength shift dependence on the applied tensile force. Samples of fiber Bragg gratings with different coatings have been studied: the restored acrylate coating, the heatshrinkable fusion splice protection sleeve without metal rod, the heat-shrinkable fusion splice protection sleeve with a metal rod, the metal capillary, polyvinylchloride tube. For different coatings of diffractive structure, dependences of wavelength shift for the Bragg grating resonance have been obtained on the tensile strength applied to the ends of an optical fiber. It was determined that the studied FBG coatings give the possibility to reduce the mechanical impact on the Bragg wavelength shift for 1.1-15 times as compared to an uncoated waveguide. The most effective version of coated fiber Bragg grating is the heatshrinkable fusion splice protection sleeve with a metal rod. When the force (equal to 6 N is applied to the 100 mm optical fiber area with the inscribed diffractive structure, the Bragg wavelength shift is 7.5 nm for the unprotected sample and 0.5 nm for the one coated with the heat-shrinkable fusion splice protection sleeve.

Polarized neutron scattering on HYSPEC: the HYbrid SPECtrometer at SNS

Energy Technology Data Exchange (ETDEWEB)

Zaliznyak, Igor [Brookhaven National Laboratory (BNL); Savici, Andrei T [ORNL; Garlea, Vasile O [ORNL; Winn, Barry L [ORNL; Schneelock, John [Brookhaven National Laboratory (BNL); Tranquada, John M. [Brookhaven National Laboratory (BNL); Gu, G. D. [Brookhaven National Laboratory (BNL); Wang, Aifeng [Brookhaven National Laboratory (BNL); Petrovic, C [Brookhaven National Laboratory (BNL)

2017-01-01

We describe some of the first polarized neutron scattering measurements performed at HYSPEC spectrometer at the Spallation Neutron Source, Oak Ridge National Laboratory. We discuss details of the instrument setup and the experimental procedures in the mode with the full polarization analysis. Examples of the polarized neutron diffraction and the polarized inelastic neutron data obtained on single crystal samples are presented.

Observation of multiple Bragg reflections of neutrons in bent perfect crystals

Czech Academy of Sciences Publication Activity Database

Mikula, Pavol; Vrána, Miroslav; Šaroun, Jan; Seong, B. S.; Moon, MK.

2011-01-01

Roč. 634, č. 1 (2011), S108-S111 ISSN 0168-9002. [International Workshop on Neutron Optics. Grenoble, 17.03.2010-19.03.2010] R&D Projects: GA ČR GAP204/10/0654 Institutional research plan: CEZ:AV0Z10480505 Keywords : Neutron diffraction * Bent perfect crystal * Multiple reflections Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.207, year: 2011

Experimental investigation of photonic band gap in one-dimensional photonic crystals with metamaterials

International Nuclear Information System (INIS)

Chen, Yihang; Wang, Xinggang; Yong, Zehui; Zhang, Yunjuan; Chen, Zefeng; He, Lianxing; Lee, P.F.; Chan, Helen L.W.; Leung, Chi Wah; Wang, Yu

2012-01-01

Composite right/left-handed transmission lines with lumped element series capacitors and shunt inductors are used to experimentally realize the one-dimensional photonic crystals composed of single-negative metamaterials. The simulated and experimental results show that a special photonic band gap corresponding to zero-effective-phase (zero-φ eff ) may appear in the microwave regime. In contrast to the Bragg gap, by changing the length ratio of the two component materials, the width and depth of the zero-φ eff gap can be conveniently adjusted while keeping the center frequency constant. Furthermore, the zero-φ eff gap vanishes when both the phase-matching and impedance-matching conditions are satisfied simultaneously. These transmission line structures provide a good way for realizing microwave devices based on the zero-φ eff gap. -- Highlights: ► 1D photonic crystals with metamaterials were investigated experimentally. ► Both Bragg gap and zero-φ eff gap were observed in the microwave regime. ► The width and depth of the zero-φ eff gap were experimentally adjusted. ► Zero-φ eff gap was observed to be close when two match conditions were satisfied.

Experimental investigation of photonic band gap in one-dimensional photonic crystals with metamaterials

Energy Technology Data Exchange (ETDEWEB)

Chen, Yihang, E-mail: eon.chen@yahoo.com.cn [Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong (China); Laboratory of Quantum Information Technology, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou (China); Wang, Xinggang [Laboratory of Quantum Information Technology, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou (China); Yong, Zehui; Zhang, Yunjuan [Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong (China); Chen, Zefeng [Laboratory of Quantum Information Technology, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou (China); He, Lianxing; Lee, P.F.; Chan, Helen L.W.; Leung, Chi Wah [Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong (China); Wang, Yu, E-mail: apywang@inet.polyu.edu.hk [Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong (China)

2012-03-19

Composite right/left-handed transmission lines with lumped element series capacitors and shunt inductors are used to experimentally realize the one-dimensional photonic crystals composed of single-negative metamaterials. The simulated and experimental results show that a special photonic band gap corresponding to zero-effective-phase (zero-φ{sub eff}) may appear in the microwave regime. In contrast to the Bragg gap, by changing the length ratio of the two component materials, the width and depth of the zero-φ{sub eff} gap can be conveniently adjusted while keeping the center frequency constant. Furthermore, the zero-φ{sub eff} gap vanishes when both the phase-matching and impedance-matching conditions are satisfied simultaneously. These transmission line structures provide a good way for realizing microwave devices based on the zero-φ{sub eff} gap. -- Highlights: ► 1D photonic crystals with metamaterials were investigated experimentally. ► Both Bragg gap and zero-φ{sub eff} gap were observed in the microwave regime. ► The width and depth of the zero-φ{sub eff} gap were experimentally adjusted. ► Zero-φ{sub eff} gap was observed to be close when two match conditions were satisfied.

On the interpretation of total current spectroscopy (TCS) spectra from MoS2 crystals

International Nuclear Information System (INIS)

Mohamed, M.H.; Moeller, P.J.

1981-01-01

Total Current Spectroscopy (TCS) spectra from MoS 2 (0001) face for three different angles of incidence of the primary beam with respect to the c-axis as well as TCS spectrum from an edge surface cut perpendicularly to the (001) face of a molybdenite crystal are given. Energy positions of the TCS structure are found to be independent of the variations in the angle of incidence of the primary beam and also of the change of crystal face. From this it is concluded that the fine structure in the TCS spectra from molybdenite crystal for the primary energies studied is due to electron-electron scattering and not to Bragg interference effects. (author)

Optical properties of mesoporous photonic crystals, filled with dielectrics, ferroelectrics and piezoelectrics

Directory of Open Access Journals (Sweden)

V. S. Gorelik

2017-12-01

Full Text Available At present, it is very important to create new types of mirrors, nonlinear light frequency transformers and optical filters with controlled optical properties. In this connection, it is of great interest to study photonic crystals. Their dielectric permittivity varies periodically in space with a period permitting Bragg diffraction of light. In this paper, we have investigated the optical properties of mesoporous three-dimensional (3D opal-type and one-dimensional (1D anodic alumina photonic crystals, filled with different dielectrics, ferroelectrics and piezoelectrics. We have compared the optical properties of initial mesoporous photonic crystals and filled with different substances. The possibility of mesoporous photonic crystals using selective narrow-band light filters in Raman scattering experiments and nonlinear mirrors has been analyzed. The electromagnetic field enhancing in the case of exciting light frequency close to the stop band edges has been established. The optical harmonics and subharmonics generation in mesoporous crystals, filled with ferroelectrics and piezoelectrics was proposed.

Fast neutron spectrometer with pulse shape discrimination

International Nuclear Information System (INIS)

Verbitsky, S.S.

1978-01-01

A fast neutron spectrometer with a stilbene single crystal designed to operate at high pulsed count rate has been described. Making use of identification and rejection of events, accompanied by pile-up, allowed to increase permissible count rates by an order of magnitude. The results of energy dependence of signal amplitude and shape relative anisotropy in stilbene in the range 4-10 and 2-8 MeV respectively have been presented. Taking into account anisotropy of the detector-scintillation properties allowed to improve particle discrimination. (Auth.)

Security System Responsive to Optical Fiber Having Bragg Grating

Science.gov (United States)

Gary, Charles K. (Inventor); Ozcan, Meric (Inventor)

1997-01-01

An optically responsive electronic lock is disclosed comprising an optical fiber serving as a key and having Bragg gratings placed therein. Further, an identification system is disclosed which has the optical fiber serving as means for tagging and identifying an object. The key or tagged object is inserted into a respective receptacle and the Bragg gratings cause the optical fiber to reflect a predetermined frequency spectra pattern of incident light which is detected by a decoder and compared against a predetermined spectrum to determine if an electrical signal is generated to either operate the lock or light a display of an authentication panel.

Pulsed laser photoacoustic spectrometer for study of solid materials

International Nuclear Information System (INIS)

Patel, N.D.; Kartha, V.B.

1991-01-01

The technique of photoacoustic spectroscopy has wide applications bacause it is extremely sensitive, and can be used to obtain spectra in wide spectral range for solids, liquids, gases, solutions, crystals etc. which may be usually difficult by conventional methods. For studying a variety of materials, a pulsed laser photoacoustic spectrometer has been set up in the laboratory. The report discusses the design and performance of the instrument. Some of the spectra of materials like Nd 2 O 9 powder, Nd-YAG crystal, CoCl 2 6H 2 O etc. are shown. A detailed discussion on assignment of the spectra of Nd-YAG is also presented. (author). 4 refs., 5 figs., 1 tab

Opal-based photonic crystal with double photonic bandgap structure

Science.gov (United States)

Romanov, S. G.; Yates, H. M.; Pemble, M. E.; DeLa Rue, R. M.

2000-09-01

The interior surfaces of one part of a piece of artificial opal have been coated with GaP so that the remaining part of the opal crystal remains empty, thus forming a photonic heterostructure. Two Bragg resonances have been observed in the optical transmission and reflectance spectra. These two resonances were found to behave differently with changes in the polarization of the incident light and the angle of propagation of the light with respect to the (111) planes of opal. Depolarization of the light was observed to occur most effectively at frequencies within the stop-bands, apparently due to the re-coupling of the propagating electromagnetic wave to a different system of eigenmodes when it crosses the interface separating two parts of the double photonic crystal.

Fabrication of locally micro-structured fiber Bragg gratings by fs-laser machining

Science.gov (United States)

Dutz, Franz J.; Stephan, Valentin; Marchi, Gabriele; Koch, Alexander W.; Roths, Johannes; Huber, Heinz P.

2018-06-01

Here, we describe a method for producing locally micro-structured fiber Bragg gratings (LMFGB) by fs-laser machining. This technique enables the precise and reproducible ablation of cladding material to create circumferential grooves inside the claddings of optical fibers. From initial ablation experiments we acquired optimized process parameters. The fabricated grooves were located in the middle of uniform type I fiber Bragg gratings. LMFBGs with four different groove widths of 48, 85, 135 and 205 μ { {m}} were produced. The grooves exhibited constant depths of about 30 μ {m} and steep sidewall angles. With the combination of micro-structures and fiber Bragg gratings, fiber optic sensor elements with enhanced functionalities can be achieved.

Performance of a three-axes crystal spectrometer at IEA-Sao Paulo, Brazil: measurements of dispersion relations in copper

International Nuclear Information System (INIS)

Fuhrmann, C.; Fulfaro, R.; Vinhas, L.A.

1978-01-01

With the purpose to check the performance of IEA Triple Axis Spectrometer of which construction was recently finished, dispersion relation curves for copper at room temperature have been messured. The frequencies of phonons propagating along the three major simmetry directions [xi00] [xixi0] and [xixixi] have been determined. The measurements were carried out operating the Triple Axis Spectrometer in the 'Q constant' mode at neutron energy loss. An excellent agreement could be observed between the results obtained in the present experiment and the accurate data for copper presented in the litterature. In such way, we can conclude that the IEA Triple Axis Spectrometer is in good operational conditions and able to perform original experiments. In this report an outline of the theory of the spectrometer operation and details on the experimental procedures for the case of a Triple Axis Spectrometer operating in the 'Q constant' mode are also presented [pt

Bragg's Law diffraction simulations for electron backscatter diffraction analysis

International Nuclear Information System (INIS)

Kacher, Josh; Landon, Colin; Adams, Brent L.; Fullwood, David

2009-01-01

In 2006, Angus Wilkinson introduced a cross-correlation-based electron backscatter diffraction (EBSD) texture analysis system capable of measuring lattice rotations and elastic strains to high resolution. A variation of the cross-correlation method is introduced using Bragg's Law-based simulated EBSD patterns as strain free reference patterns that facilitates the use of the cross-correlation method with polycrystalline materials. The lattice state is found by comparing simulated patterns to collected patterns at a number of regions on the pattern using the cross-correlation function and calculating the deformation from the measured shifts of each region. A new pattern can be simulated at the deformed state, and the process can be iterated a number of times to converge on the absolute lattice state. By analyzing an iteratively rotated single crystal silicon sample and recovering the rotation, this method is shown to have an angular resolution of ∼0.04 o and an elastic strain resolution of ∼7e-4. As an example of applications, elastic strain and curvature measurements are used to estimate the dislocation density in a single grain of a compressed polycrystalline Mg-based AZ91 alloy.

Uniform Fiber Bragg Grating modeling and simulation used matrix transfer method

OpenAIRE

IKHLEF, Abdallah; HEDARA, Rachida; CHIKH-BLED, Mohamed

2012-01-01

This paper presents the modeling and simulation of an optical fiber Bragg grating for maximum reflectivity, minimum side lobe. Gating length represents as one of the critical parameters in contributing to a high performance fiber Bragg grating. The reflection spectra and side lobes strength were analyzed with different lengths .The side lobes have been suppressed using raised cosine apodization while maintaining the peak reflectivity. Such simulations are based on ...

Nuclear Bragg diffraction using synchrotron radiation

International Nuclear Information System (INIS)

Rueffer, R.; Gerdau, E.; Grote, M.; Hollatz, R.; Roehlsberger, R.; Rueter, H.D.; Sturhahn, W.

1990-01-01

Nuclear Bragg diffraction with synchrotron radiation as source will become a powerful new X-ray source in the A-region. This source exceeds by now the brilliance of conventional Moessbauer sources giving hyperfine spectroscopy further momentum. As examples applications to yttrium iron garnet (YIG) and iron borate will be discussed. (author)

Dynamical theoretical model of the high-resolution double-crystal x-ray diffractometry of imperfect single crystals with microdefects

International Nuclear Information System (INIS)

Molodkin, V. B.; Olikhovskii, S. I.; Kislovskii, E. N.; Vladimirova, T. P.; Skakunova, E. S.; Seredenko, R. F.; Sheludchenko, B. V.

2008-01-01

The dynamical diffraction model has been developed for the quantitative description of rocking curves (RCs) measured in the Bragg diffraction geometry from single crystals containing homogeneously distributed microdefects of several types and with arbitrary sizes. The analytical expressions for coherent and diffuse RC components, which take self-consistently multiple-scattering effects into account and depend explicitly on microdefect characteristics (radius, concentration, strength, etc.), have been derived with taking into account the instrumental factors. The developed model has been applied to determine the characteristics of oxygen precipitates and dislocation loops in silicon crystals grown by Czochralsky and float-zone methods using RCs measured by the high-resolution double-crystal x-ray diffractometer. It has been shown, particularly, that completely dynamical consideration of Huang as well as Stockes-Wilson diffuse scattering (DS) in both diffuse RC component and coefficient of extinction of coherent RC component due to DS, together with taking asymmetry and thermal DS effects into account, provides the possibility to distinguish contributions into RC from defects of different types, which have equal or commensurable effective radii

New optical scheme for differential measurements of diffraction reflection intensity on X-radiation sliding incidence

International Nuclear Information System (INIS)

Golovin, A.L.; Mas', E.T.

1989-01-01

An X-ray optical scheme for differential measurements of X-ray diffraction under sliding incidence conditions is proposed and an attachment design realizng this scheme, using standard equipment, is described. The main feature of the scheme is the following: collimation according to the Bragg angle is carried out for the reflected beam rather than the incident one. Goniometers can be used from DRON, TRS, GS-5 and other spectrometers. The goniometer head carrying the sample is standard, it is a part of the DRON, TRS and DTS. The crystal analyzer is fixed on the attachment. The angular position of the crystal monochromator is controlled by an inductive sensor. The experimental differential curves of X-ray diffraction under conditions of sliding incidence, taken for a silicon crystal having the 111 orientation, are given as well

MERLIN, a new high count rate spectrometer at ISIS

International Nuclear Information System (INIS)

Bewley, R.I.; Eccleston, R.S.; McEwen, K.A.; Hayden, S.M.; Dove, M.T.; Bennington, S.M.; Treadgold, J.R.; Coleman, R.L.S.

2006-01-01

MERLIN is designed to be a high intensity, medium energy resolution spectrometer. As such, it will complement the high-resolution MAPS spectrometer at ISIS. MERLIN will utilise all the latest advances in technology with a supermirror guide to enhance flux as well as 3 m long position-sensitive detectors in a vacuum making it ideal for single-crystal users. The detector bank will cover a massive π steradians of solid angle with an angular range from -45 o to +135 o degrees in the horizontal plane and ±30 o degrees in the vertical plane. This will allow large swathes of Q,ω space to be accessed in a single run. The instrument will be ready for commissioning in February 2006. This paper presents details of design and performance of this new instrument

Quantitative analysis of directional spontaneous emission spectra from light sources in photonic crystals

International Nuclear Information System (INIS)

Nikolaev, Ivan S.; Lodahl, Peter; Vos, Willem L.

2005-01-01

We have performed angle-resolved measurements of spontaneous-emission spectra from laser dyes and quantum dots in opal and inverse opal photonic crystals. Pronounced directional dependencies of the emission spectra are observed: angular ranges of strongly reduced emission adjoin with angular ranges of enhanced emission. It appears that emission from embedded light sources is affected both by the periodicity and by the structural imperfections of the crystals: the photons are Bragg diffracted by lattice planes and scattered by unavoidable structural disorder. Using a model comprising diffuse light transport and photonic band structure, we quantitatively explain the directional emission spectra. This work provides detailed understanding of the transport of spontaneously emitted light in real photonic crystals, which is essential in the interpretation of quantum optics in photonic-band-gap crystals and for applications wherein directional emission and total emission power are controlled

Ultra-large bandwidth hollow-core guiding in all-silica bragg fibers with nano-supports

DEFF Research Database (Denmark)

Vienne, Guillaume; Xu, Yong; Jakobsen, Christian

2004-01-01

We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding in t...... in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature. With only three rings of silica cladding layers, these Bragg fibers achieve propagation loss of the order of 1 dB/m....

Induction of Micronuclei in Human Fibroblasts across the Bragg Curve of Energetic Si and Fe Ions

Science.gov (United States)

Wu, H.; Rusek, A.; Hada, M.

2006-01-01

The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the major protection to astronauts from harmful exposure. Unlike low-LET gamma or X-rays, the presence of shielding does not always reduce the radiation risks for energetic charged particle exposure. Since the dose delivered by the charged particle increases sharply as the particle approaches the end of its range, a position known as the Bragg peak, the Bragg curve does not necessarily represent the biological damage along the particle traversal since biological effects are influenced by the track structure of both primary and secondary particles. Therefore, the biological Bragg curve is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. We studied micronuclei (MN) induction across the Bragg curve of Si and Fe ions at incident energies of 300 MeV/nucleon and 1 GeV/nucleon. A quantitative biological response curve did not reveal an increased yield of MN at the location of the Bragg peak. However, the ratio of mono- to bi-nucleated cells, which indicates inhibition in cell progression, increased at the Bragg peak location. These results confirm the hypothesis that severely damaged cells at the Bragg peak are likely to go through reproduction death.

Deep ultraviolet distributed Bragg reflectors based on graded composition AlGaN alloys

Energy Technology Data Exchange (ETDEWEB)

Brummer, Gordie, E-mail: gbrummer@bu.edu [Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215 (United States); Photonics Center, Boston University, Boston, Massachusetts 02215 (United States); Nothern, Denis [Photonics Center, Boston University, Boston, Massachusetts 02215 (United States); Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215 (United States); Nikiforov, A. Yu. [Photonics Center, Boston University, Boston, Massachusetts 02215 (United States); Moustakas, T. D., E-mail: tdm@bu.edu [Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215 (United States); Photonics Center, Boston University, Boston, Massachusetts 02215 (United States); Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215 (United States)

2015-06-01

Distributed Bragg reflectors (DBRs) with peak reflectivity at approximately 280 nm, based on compositionally graded Al{sub x}Ga{sub 1−x}N alloys, were grown on 6H-SiC substrates by plasma-assisted molecular beam epitaxy. DBRs with square, sinusoidal, triangular, and sawtooth composition profiles were designed with the transfer matrix method. The crystal structure of these DBRs was studied with high-resolution x-ray diffraction of the (1{sup ¯}015) reciprocal lattice point. The periodicity of the DBR profiles was confirmed with cross-sectional Z-contrast scanning transmission electron microscopy. The peak reflectance of these DBRs with 15.5 periods varies from 77% to 56% with corresponding full width at half maximum of 17–14 nm. Coupled mode analysis was used to explain the dependence of the reflectivity characteristics on the profile of the graded composition.

Characterization of a new modular decay total absorption gamma-ray spectrometer (DTAS) for FAIR

International Nuclear Information System (INIS)

Montaner Pizá, A.; Taín, J. L.; Agramunt, J.; Algora, A.; Guadilla, V.; Marín, E.; Rice, S.; Rubio, B.

2013-01-01

Beta-decay studies are one of the main goals of the DEcay SPECtroscopy experiment (DESPEC) to be installed at the future Facility for Antiproton and Ion Research (FAIR). DESPEC aims at the study of nuclear structure of exotic nuclei. A new modular Decay Total Absorption gamma-ray Spectrometer (DTAS) is being built at IFIC and is specially adapted to studies at fragmentation facilities such as the Super Fragment Separator (Super-FRS) at FAIR. The designed spectrometer is composed of 16 identical NaI(Tl) scintillation crystals. This work focuses on the characterization of these independent modules, as an initial step for the characterization of the full spectrometer. Monte Carlo simulations have been performed in order to understand the detector response.

An optical fiber Bragg grating and piezoelectric ceramic voltage sensor

Science.gov (United States)

Yang, Qing; He, Yanxiao; Sun, Shangpeng; Luo, Mandan; Han, Rui

2017-10-01

Voltage measurement is essential in many fields like power grids, telecommunications, metallurgy, railways, and oil production. A voltage-sensing unit, consisting of fiber Bragg gratings (FBGs) and piezoelectric ceramics, based on which an optical over-voltage sensor was proposed and fabricated in this paper. No demodulation devices like spectrometer or Fabry-Perot filter were needed to gain the voltage signal, and a relatively large sensing frequency range was acquired in this paper; thus, the cost of the sensing system is more acceptable in engineering application. The voltage to be measured was directly applied to the piezoelectric ceramic, and deformation of the ceramics and the grating would be caused because of the inverse piezoelectric effect. With a reference grating, the output light intensity change will be caused by the FBG center wavelength change; thus, the relationship between the applied voltage and the output light intensity was established. Validation of the sensor was accomplished in the frequency range from 50 Hz to 20 kHz and switching impulse waves with a test platform; good linearity of the input-output characteristic was achieved. A temperature validation test was completed, showing that the sensor maintains good temperature stability. Experimental results show that the optical over-voltage sensor can be used for voltage monitoring, and if applied with a voltage divider, the sensor can be used to measure high voltage.

An optical fiber Bragg grating and piezoelectric ceramic voltage sensor.

Science.gov (United States)

Yang, Qing; He, Yanxiao; Sun, Shangpeng; Luo, Mandan; Han, Rui

2017-10-01

Voltage measurement is essential in many fields like power grids, telecommunications, metallurgy, railways, and oil production. A voltage-sensing unit, consisting of fiber Bragg gratings (FBGs) and piezoelectric ceramics, based on which an optical over-voltage sensor was proposed and fabricated in this paper. No demodulation devices like spectrometer or Fabry-Perot filter were needed to gain the voltage signal, and a relatively large sensing frequency range was acquired in this paper; thus, the cost of the sensing system is more acceptable in engineering application. The voltage to be measured was directly applied to the piezoelectric ceramic, and deformation of the ceramics and the grating would be caused because of the inverse piezoelectric effect. With a reference grating, the output light intensity change will be caused by the FBG center wavelength change; thus, the relationship between the applied voltage and the output light intensity was established. Validation of the sensor was accomplished in the frequency range from 50 Hz to 20 kHz and switching impulse waves with a test platform; good linearity of the input-output characteristic was achieved. A temperature validation test was completed, showing that the sensor maintains good temperature stability. Experimental results show that the optical over-voltage sensor can be used for voltage monitoring, and if applied with a voltage divider, the sensor can be used to measure high voltage.

Variation of Bragg curve characteristic induced by changing the position of inhomogeneous material: Geant4 simulation study

Energy Technology Data Exchange (ETDEWEB)

Park, So-Hyun; Jung, Won-Gyun; Suh, Tae-Suk [Catholic University, Seoul (Korea, Republic of); Jang, Hong-Seok; Choi, Byeong-Oak [Seoul St. Mary' s Hospital, Seoul (Korea, Republic of); Rah, Jeong-Eun; Park, Sun-Gyong; Lee, Se-Byeong [National Cancer Center, Ilsan (Korea, Republic of)

2011-02-15

When proton beam passes through the human body, the stopping power and the depth-dose distribution of the proton are influenced by the relative location among adjacent materials or the difference in material conditions. Our study demonstrates the effect of inhomogeneous materials placed in the Plateau and Bragg peak regions of the Bragg curve in water. We evaluated the Bragg peak position, range, penumbra and integrated doses by using the Geant4 simulation toolkit. The positions of inhomogeneities were selected as the proximal 36% and 50% points of the maximum dose, which indicates the location at entrance regions of the Plateau and the Bragg peak, respectively. Bone (density {rho} = 1.85 g/cm{sup 3}) and adipose tissue (density {rho} = 0.92 g/cm{sup 3}) were selected as inhomogeneous materials. The thickness of each material was varied by 0.1 cm between 0.1 cm and 1.0 cm. In addition, the initial energy of the proton beam was changed in 30 MeV steps between 108 MeV and 220 MeV. The effects of inhomogeneous conditions were performed for various parameters: Bragg peak position, range, penumbra width, full width at half maximum and dose of Bragg curve. A dose perturbation was observed in the region of the Bragg peak and inhomogeneous material, especially, When the bone equivalent material was inserted within the Bragg curve. However, there were no significant variations in the other parameters, except for the dose perturbation depending on the inserted location of each material. This study shows the characteristic changes in the Bragg curve due to inhomogeneous materials.

Bragg peak proton beam treatment of arteriovenous malformations of the brain

International Nuclear Information System (INIS)

Kjellberg, R.N.; Poletti, C.E.; Roberson, G.H.; Adams, R.D.

1978-01-01

This report describes 27 patients treated for arteriovenous malformations of the brain by the Bragg Peak proton beam method during the past 12 years. The authors are led to a measure of confidence that Bragg Peak proton therapy can be provided without lethal risk attributed to the procedure. In 21 patients no neurological change has occurred, two patients experienced neurological improvement and four have developed new neurological abnormalities considered complications of the therapy. (Auth.)

Investigation of a novel x-ray tube for the calibration of the x-ray crystal spectrometer in the KSTAR machine

International Nuclear Information System (INIS)

Bak, J.G.; Lee, S.G.

2007-01-01

A novel x-ray tube with a line filament has been developed for the in-situ calibration of the x-ray crystal spectrometer (XCS) in the KSTAR machine. The characteristics of the x-ray tube are investigated from the x-ray images obtained by using a pinhole and a CCD detector. It is found that the image has the width of about 0.1 mm, which is much improved as compared with the previous experimental results. In addition, there is a uniform region around the center of the image within its full length of 13.5 mm. This work may lead to the development of a novel x-ray tube with a line focus, which is required for the calibration of the XCS. Experimental results from the investigation of the x-ray tube are presented and the technical issues in a design of the in-situ calibration system using the x-ray tube for the KSTAR XCS are discussed. (author)

Recent progress in the chopper spectrometer, INC

International Nuclear Information System (INIS)

Itoh, Shinichi; Arai, Masatoshi; Kawai, Masayoshi

2001-01-01

A guide tube comprising supermirrors, of which the critical wavenumber is three times as large as that of natural nickel, was installed in the primary flight path of the chopper spectrometer, INC, at KENS. Also, the characteristics of the ambient-temperature H 2 O moderator, which INC is facing, was changed by renewal construction of the neutron source at KENS. We discuss here an improvement in the performance of INC by a comparison with the previous performance. We also report on the development on a goniometer for single-crystal experiments at low temperatures. (author)

Development of a Gamma Spectrometer using a Large NaI Scintillator and SiPMs

International Nuclear Information System (INIS)

Kim, Chankyu; Yoo, Hyunjun; Kim, Yewon and others

2014-01-01

A typical scintillation gamma spectrometer is composed of a NaI(Tl) scintillation crystal and a PM tube. From last years, a Silicon Photomultiplier (SiPM) is being developed and expanding its application area as a substitute of PM tube due to its advantages like low operating voltage, small volume, and cheap production cost, MR compatibility. This approach could make gamma spectrometer smaller, cheaper, easier to use, and these advantage are quite suitable to original purpose of scintillation gamma spectrometer. Gamma spectrometry and gamma spectrometer is used to analyze gamma source in nuclear science, geochemistry, and astrophysics. In this research, gamma spectrometer which uses SiPMs instead of PM tube is proposed. The proposed gamma spectrometer has advantages of low cost, small volume, low operation voltage; but it has disadvantages of performances. To reduce this loss in performances, a light guide of effective structure is required. (Material, reflection type, tapering angle) For design of the light guide, DETECT simulation was performed. And through DETECT simulation, the characteristics of light guide could be prospected. Actual light guide was manufactured on the basis of this simulation result. Using the light guide, gamma spectrometer system was composed and tested. In the test result, gamma spectrometer using SiPM shows degraded energy resolution. The reason of this degradation is being analyzed and the test system is under modification

Determining the diffraction properties of a cylindrically bent KAP(001) crystal from 1 to 5 keV

Energy Technology Data Exchange (ETDEWEB)

Haugh, Michael [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Lee, Joshua [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Jacoby, Kenneth [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Christensen, C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Loisel, G. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States), Livermore Operations

2015-08-31

Various crystals are used for the dispersive component of X-ray spectrometers. The crystals are usually bent to meet the desired measurement needs, such as focusing. The bending can change the crystal diffraction properties, thus altering the spectrometer throughput and resolving power. This work concerns measuring the diffraction properties of a potassium acid phthalate (001) [KAP(001)] crystal bent into a circular cylinder segment. The measurement methods using a diode source and a synchrotron source are described. The multi-lamellar model for calculating the diffraction properties of a bent crystal is described. The measurement results are compared to the multi-lamellar model and show qualitative agreement. The measurements show how to make the multi-lamellar calculations a useful estimate. A method is given to make useful estimates of the diffraction properties of the KAP(001) crystal bent into a circular cylinder segment.

Microfiber Bragg grating hydrogen sensor base on co-sputtered Pd/Ni composite film

Science.gov (United States)

Wang, Gaopeng; Yang, Minghong; Dai, Jixiang; Cheng, Cheng; Yuan, Yinqian

2015-07-01

A novel hydrogen sensor based on Pd/Ni co-sputtered coating on micro fiber Bragg grating (MFBG) is proposed and experimentally demonstrated. The microfiber is stretched uniformly and the Bragg grating is directly inscribed on the microfiber without hydrogen loading using 193 nm ArF excimer laser and a phase mask. Palladium and nickel coatings are co-sputtered on the micro fiber Bragg grating for hydrogen sensing. The MFBG hydrogen sensors are characterized concerning their response to the hydrogen, ambient temperature and ambient refractive index, respectively. The performance of the proposed MFBG hydrogen sensor is obviously enhanced, especially when compared to standard FBG hydrogen sensors.

Engineering a light-emitting planar defect within three-dimensional photonic crystals

Directory of Open Access Journals (Sweden)

Guiqiang Liu, Yan Chen and Zhiqing Ye

2009-01-01

Full Text Available Sandwich structures, constructed from a planar defect of rhodamine-B (RhB-doped titania (TiO2 and two photonic crystals, were synthesized via the self-assembly method combined with spin-coating. The modification of the spontaneous emission of RhB molecules in such structures was investigated experimentally. The spontaneous emission of RhB-doped TiO2 film with photonic crystals was reduced by a factor of 5.5 over a large bandwidth of 13% of the first-order Bragg diffraction frequency when compared with that of RhB-doped TiO2 film without photonic crystals. The angular dependence of the modification and the photoluminescence lifetime of RhB molecules demonstrate that the strong and wide suppression of the spontaneous emission of the RhB molecules is due to the presence of the photonic band gap.

Engineering a light-emitting planar defect within three-dimensional photonic crystals

Science.gov (United States)

Liu, Guiqiang; Chen, Yan; Ye, Zhiqing

2009-01-01

Sandwich structures, constructed from a planar defect of rhodamine-B (RhB)-doped titania (TiO2) and two photonic crystals, were synthesized via the self-assembly method combined with spin-coating. The modification of the spontaneous emission of RhB molecules in such structures was investigated experimentally. The spontaneous emission of RhB-doped TiO2 film with photonic crystals was reduced by a factor of 5.5 over a large bandwidth of 13% of the first-order Bragg diffraction frequency when compared with that of RhB-doped TiO2 film without photonic crystals. The angular dependence of the modification and the photoluminescence lifetime of RhB molecules demonstrate that the strong and wide suppression of the spontaneous emission of the RhB molecules is due to the presence of the photonic band gap. PMID:27877309

Development of low background germanium spectrometer for measurement of neutrino magnetic moment

CERN Document Server

Beda, A G; Starostin, A S

2000-01-01

The prospects for a search for neutrino magnetic moment down to (3-5)centre dot 10 sup - sup 1 sup 1 of the Bohr magneton with the use of low background Ge-NaI spectrometer built in ITEP are discussed. The lowest level of background for shallow setups was achieved in the preliminary test measurements of background. This result and estimations of additional sources of the background in a reactor experiment testify that using the low background Ge-NaI spectrometer with mass of Ge-crystal of 2 kg it is possible to achieve above objective, that will be one order of magnitude better than the present experimental limit.

Robust optic alignment in a tilt-free implementation of the Rowland circle spectrometer

Energy Technology Data Exchange (ETDEWEB)

Mortensen, Devon R., E-mail: devon@easyxafs.com [Department of Physics, University of Washington, Seattle, WA 98195-1560 (United States); easyXAFS, LLC, Seattle, WA 98122 (United States); Seidler, Gerald T., E-mail: seidler@uw.edu [Department of Physics, University of Washington, Seattle, WA 98195-1560 (United States)

2017-02-15

Highlights: • A Rowland circle spectrometer using spherically-bend crystal analyzers can be constructed and operated without the use of a two-axis tilt for analyzer alignment. • The resulting instrument allows immediate exchange of fully-tuned optics after a single, initial alignment. • This improvement will help enable the expansion of high-resolution x-ray expansion spectroscopy outside of synchrotron light sources. - Abstract: High-resolution x-ray emission spectroscopy (XES) has recently been demonstrated in the laboratory setting, achieving nearly synchrotron-level count rates despite the use of only conventional x-ray tube sources. This development holds high potential for expanding the reach of x-ray spectroscopies beyond the specialist community of synchrotron users, but comes with its own unique technical challenges for instrument performance and also, just as importantly, for ease of use by non-experts in x-ray science. Here, we address spectrometer design and operations in the context of the imperfect parallelness between the desired crystal plane and the wafer surface in spherically bent crystal analyser (SBCAs), an effect usually called “wafer miscut”. This introduces an ambiguous re-focusing error that typically requires a motorized two-axis tilt stage for fine alignment of the SBCA optic onto the ideal Rowland circle configuration. We instead demonstrate an asymmetric Rowland geometry that eliminates all need for motorized fine-tilt adjustment. We find rapid, extremely reproducible re-insertion of any aligned SBCA, i.e., without the need for any subsequent reoptimization. These improvements strongly benefit the ease of use of laboratory based spectrometers, taking them an important step closer to the level of turnkey operations needed for wide adoption outside of the existing specialist community.

Developments regarding the Bragg rule for stopping power and critical examination of its application to water

International Nuclear Information System (INIS)

Kamaratos, E.

1983-01-01

A critical comparison is made of various experimental findings regarding the Bragg additivity rule for stopping power. It appears that deviations from the Bragg additivity rule reported a long time ago and ascribed to chemical binding effects and phase effects are real, despite even recent statements of the contrary. Nevertheless, when the Bragg rule is applied to water, critical examination of very recent experimental results for the stopping power in the gaseous state of water, hydrogen and oxygen in this work suggest that the reported deviations from the Bragg additivity rule for the stopping power of gaseous water may be the result of experimental error. (orig.)

Experimental studies of dispersive double reflections excited in cylindrically bent perfect-crystal slabs at a constant neutron wavelength

Czech Academy of Sciences Publication Activity Database

Mikula, Pavol; Vrána, Miroslav; Šaroun, Jan; Davydov, Vadim; Em, V.; Seong, B. S.

2012-01-01

Roč. 45, č. 1 (2012), s. 98-105 ISSN 0021-8898 R&D Projects: GA ČR GAP204/10/0654 Institutional research plan: CEZ:AV0Z10480505 Keywords : RESIDUAL STRAIN-STRESS INSTRUMENT * MULTIPLE BRAGG-REFLECTIONS * SINGLE-CRYSTAL Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.343, year: 2012

Description of the atomic disorder (local order) in crystals by the mixed-symmetry method

Science.gov (United States)

Dudka, A. P.; Novikova, N. E.

2017-11-01

An approach to the description of local atomic disorder (short-range order) in single crystals by the mixed-symmetry method based on Bragg scattering data is proposed, and the corresponding software is developed. In defect-containing crystals, each atom in the unit cell can be described by its own symmetry space group. The expression for the calculated structural factor includes summation over different sets of symmetry operations for different atoms. To facilitate the search for new symmetry elements, an "atomic disorder expert" was developed, which estimates the significance of tested models. It is shown that the symmetry lowering for some atoms correlates with the existence of phase transitions (in langasite family crystals) and the anisotropy of physical properties (in rare-earth dodecaborides RB12).

Polymer waveguide Bragg grating Fabry–Perot filter using a nanoimprinting technique

International Nuclear Information System (INIS)

Binfeng, Yun; Guohua, Hu; Yiping, Cui

2014-01-01

A narrow band waveguide Fabry–Perot filter at 1550 nm, which is composed of two polymer waveguide Bragg gratings as reflectors, is presented. By using conventional lithography, a low-loss polymer channel waveguide was fabricated, and the submicron Bragg grating structure was transferred onto the waveguide surface using a nanoimprinting technique. The transmission spectrum of the device was measured, and the results show that there is a very narrow transmission peak, with a 3 dB bandwidth of 0.011 nm in the 0.38 nm rejection band of the waveguide Bragg grating. A quality factor of Q ≈ 1.41 × 10 5 is achieved. The insertion loss and the extinction ratio of the Fabry–Perot filter are about −12.5 dB and 17 dB, respectively. In addition, the measured transmission spectrum is in excellent accordance with the numerical simulation. (paper)

High-speed two-dimensional laser scanner based on Bragg gratings stored in photothermorefractive glass.

Science.gov (United States)

Yaqoob, Zahid; Arain, Muzammil A; Riza, Nabeel A

2003-09-10

A high-speed free-space wavelength-multiplexed optical scanner with high-speed wavelength selection coupled with narrowband volume Bragg gratings stored in photothermorefractive (PTR) glass is reported. The proposed scanner with no moving parts has a modular design with a wide angular scan range, accurate beam pointing, low scanner insertion loss, and two-dimensional beam scan capabilities. We present a complete analysis and design procedure for storing multiple tilted Bragg-grating structures in a single PTR glass volume (for normal incidence) in an optimal fashion. Because the scanner design is modular, many PTR glass volumes (each having multiple tilted Bragg-grating structures) can be stacked together, providing an efficient throughput with operations in both the visible and the infrared (IR) regions. A proof-of-concept experimental study is conducted with four Bragg gratings in independent PTR glass plates, and both visible and IR region scanner operations are demonstrated.

Degradation of the Bragg peak due to inhomogeneities.

Science.gov (United States)

Urie, M; Goitein, M; Holley, W R; Chen, G T

1986-01-01

The rapid fall-off of dose at the end of range of heavy charged particle beams has the potential in therapeutic applications of sparing critical structures just distal to the target volume. Here we explored the effects of highly inhomogeneous regions on this desirable depth-dose characteristic. The proton depth-dose distribution behind a lucite-air interface parallel to the beam was bimodal, indicating the presence of two groups of protons with different residual ranges, creating a step-like depth-dose distribution at the end of range. The residual ranges became more spread out as the interface was angled at 3 degrees, and still more at 6 degrees, to the direction of the beam. A second experiment showed little significant effect on the distal depth-dose of protons having passed through a mosaic of teflon and lucite. Anatomic studies demonstrated significant effects of complex fine inhomogeneities on the end of range characteristics. Monoenergetic protons passing through the petrous ridges and mastoid air cells in the base of skull showed a dramatic degradation of the distal Bragg peak. In beams with spread out Bragg peaks passing through regions of the base of skull, the distal fall-off from 90 to 20% dose was increased from its nominal 6 to well over 32 mm. Heavy ions showed a corresponding degradation in their ends of range. In the worst case in the base of skull region, a monoenergetic neon beam showed a broadening of the full width at half maximum of the Bragg peak to over 15 mm (compared with 4 mm in a homogeneous unit density medium). A similar effect was found with carbon ions in the abdomen, where the full width at half maximum of the Bragg peak (nominally 5.5 mm) was found to be greater than 25 mm behind gas-soft-tissue interfaces. We address the implications of these data for dose computation with heavy charged particles.

Spherical grating spectrometers

Science.gov (United States)

O'Donoghue, Darragh; Clemens, J. Christopher

2014-07-01

We describe designs for spectrometers employing convex dispersers. The Offner spectrometer was the first such instrument; it has almost exclusively been employed on satellite platforms, and has had little impact on ground-based instruments. We have learned how to fabricate curved Volume Phase Holographic (VPH) gratings and, in contrast to the planar gratings of traditional spectrometers, describe how such devices can be used in optical/infrared spectrometers designed specifically for curved diffraction gratings. Volume Phase Holographic gratings are highly efficient compared to conventional surface relief gratings; they have become the disperser of choice in optical / NIR spectrometers. The advantage of spectrometers with curved VPH dispersers is the very small number of optical elements used (the simplest comprising a grating and a spherical mirror), as well as illumination of mirrors off axis, resulting in greater efficiency and reduction in size. We describe a "Half Offner" spectrometer, an even simpler version of the Offner spectrometer. We present an entirely novel design, the Spherical Transmission Grating Spectrometer (STGS), and discuss exemplary applications, including a design for a double-beam spectrometer without any requirement for a dichroic. This paradigm change in spectrometer design offers an alternative to all-refractive astronomical spectrometer designs, using expensive, fragile lens elements fabricated from CaF2 or even more exotic materials. The unobscured mirror layout avoids a major drawback of the previous generation of catadioptric spectrometer designs. We describe laboratory measurements of the efficiency and image quality of a curved VPH grating in a STGS design, demonstrating, simultaneously, efficiency comparable to planar VPH gratings along with good image quality. The stage is now set for construction of a prototype instrument with impressive performance.

Neutron transmission through pyrolytic graphite crystals

Energy Technology Data Exchange (ETDEWEB)

Adib, M. [Reactor Physics Department NRC, Reactor Physics Division, Nuclear Research Center, Egyptian Atomic Energy Authority, Cairo 13759 (Egypt); Habib, N. [Reactor Physics Department NRC, Reactor Physics Division, Nuclear Research Center, Egyptian Atomic Energy Authority, Cairo 13759 (Egypt)]. E-mail: nadiahabib15@yahoo.com; Fathaalla, M. [Reactor Physics Department NRC, Reactor Physics Division, Nuclear Research Center, Egyptian Atomic Energy Authority, Cairo 13759 (Egypt)

2006-05-15

Calculation of the total cross-section, neutron transmission and removal coefficient of pyrolytic graphite (PG) for thermal neutron energies were carried out using an additive formula. The formula takes into account the variation of thermal diffuse and Bragg scattering cross-sections in terms of PG temperature and mosaic spread for neutron energies in the range 1 meV to 1 eV. A computer code PG has been developed which allow calculations for the graphite in its hexagonal close-packed structure, when its c-direction is parallel with incident neutron beam (parallel orientation). The calculated total neutron cross-sections for PG in parallel orientation at different mosaic spreads were compared with the measured values. An overall agreement is indicated between the formula fits and experimental data at room and liquid nitrogen temperatures. A feasibility study for use of PG crystals as second-order neutron filter is detailed in terms of mosaic spread, optimum thickness and temperature. The calculated removal coefficients of PG crystals show that such crystals are high efficiency second-order filter within neutron energy intervals (4-7 meV) and (10-15 meV)

Omnidirectional mirror based on Bragg stacks with a periodic gain-loss modulation

International Nuclear Information System (INIS)

Manzanares-Martinez, Jesus; Ham-Rodriguez, Carlos Ivan; Moctezuma-Enriquez, Damian; Manzanares-Martinez, Betsabe

2014-01-01

In this work we demonstrate that a Bragg Stack with a periodic gain-loss modulation can function as an Omnidirectional Mirror (OM) with complete reflection at any angle of incidence irrespective of the light polarization. The Bragg Stack is composed by the periodic variation of two layers with the same value of the real part of the refractive index (n r ) and a periodic modulation in the imaginary part (n i ). The origin of the band gaps is due to the interference of complex waves with propagating and evanescent fields in each layer. It is found that the band gaps are wider as the contrast n i /n r increases. We have found the ambient conditions to obtain an OM considering an auxiliary medium n ′ external to the Bragg Stack

Strain induced tunable wavelength filters based on flexible polymer waveguide Bragg reflector.

Science.gov (United States)

Kim, Kyung-Jo; Seo, Jun-Kyu; Oh, Min-Cheol

2008-02-04

A tunable wavelength filter is demonstrated by imposing a strain on a polymeric Bragg reflection waveguide fabricated on a flexible substrate. The highly elastic property of flexible polymer device enables much wider tuning than the silica fiber. To produce a uniform grating pattern on a flexible plastic substrate, a post lift-off process along with an absorbing layer is incorporated. The flexible Bragg reflector shows narrow bandwidth, which is convincing the uniformity of the grating structure fabricated on plastic film. By stretching the flexible polymer device, the Bragg reflection wavelength is tuned continuously up to 45 nm for the maximum strain of 31,690 muepsilon, which is determined by the elastic expansion limit of waveguide polymer. From the linear wavelength shift proportional to the strain, the photoelastic coefficient of the ZPU polymer is found.

Calculation Analysis of Calibration Factors of Airborne Gamma-ray Spectrometer

International Nuclear Information System (INIS)

Zhao Jun; Zhu Jinhui; Xie Honggang; He Qinglin

2009-01-01

To determine the calibration factors of an airborne gamma-ray spectrometer measuring large area gamma-ray emitting source at deferent flying height, a series of Monte Carlo simulations were drawn. Response energy spectrums of NaI crystals in airplane caused by nature-decay-series calibration-pads, and calibration factors on different heights above Cs-137 plane source, were obtained. The calculated results agreed with the experimental data well. (authors)

High force measurement sensitivity with fiber Bragg gratings fabricated in uniform-waist fiber tapers

International Nuclear Information System (INIS)

Wieduwilt, Torsten; Brückner, Sven; Bartelt, Hartmut

2011-01-01

Fiber Bragg gratings inscribed in the waist of tapered photosensitive fibers offer specific attractive properties for sensing applications. A small-diameter fiber reduces structural influences for imbedded fiber sensing elements. In the case of application as a force-sensing element for tensile forces, sensitivity scales inversely with the fiber cross-sectional area. It is therefore possible to increase force sensitivity by several orders of magnitude compared to Bragg grating sensors in conventionally sized fibers. Special requirements for such Bragg grating arrangements are discussed and experimental measurements for different fiber taper diameters down to 4 µm are presented

Moiré phase-shifted fiber Bragg gratings in polymer optical fibers

Science.gov (United States)

Min, Rui; Marques, Carlos; Bang, Ole; Ortega, Beatriz

2018-03-01

We demonstrate a simple way to fabricate phase-shifted fiber Bragg grating in polymer optical fibers as a narrowband transmission filter for a variety of applications at telecom wavelengths. The filters have been fabricated by overlapping two uniform fiber Bragg gratings with slightly different periods to create a Moiré grating with only two pulses (one pulse is 15 ns) of UV power. Experimental characterization of the filter is provided under different conditions where the strain and temperature sensitivities were measured.

Borehole instrument for scintillation gamma spectrometer

International Nuclear Information System (INIS)

Sinitsyn, A.Ya.; Gabitov, R.M.

1979-01-01

Described are a schematic diagram and main specifications of a borehole instrument with autostabilization of energy scale measure by gamma bench-mark of 137 Cs, intended for the application in a logging gamma spectrometer to determine separately the concentrations of nature radioactive elements. The instrument may be connected to the KOBDFM-2 cable of 600 m length. It contains a scintillation counter for gamma quanta consisting of 30x70 mm NaI(Tl) crystal and a FEU-85 photoamplifier, an input conforming stage, a diagram of threshold pulse formation and regulating high-voltage generator. The borehole instrument has been proved under laboratory and field conditions at 10-40 deg C

Bragg scattering of electromagnetic waves by microwave-produced plasma layers

Science.gov (United States)

Kuo, S. P.; Zhang, Y. S.

1990-01-01

A set of parallel plasma layers is generated by two intersecting microwave pulses in a chamber containing dry air at a pressure comparable to the upper atmosphere. The dependencies of breakdown conditions on the pressure and pulse length are examined. The results are shown to be consistent with the appearance of tail erosion of the microwave pulse caused by air breakdown. A Bragg scattering experiment, using the plasma layers as a Bragg reflector, is then performed. Both time domain and frequency domain measurements of wave scattering are conducted. The experimental results are found to agree very well with the theory.

Mode Dynamics in the Bragg FEL Based on Coupling of Propagating and Trapped Waves

CERN Document Server

Ginzburg, N S; Peskov, N Yu; Rozental, R M; Sergeev, A; Zaslavsky, V Yu

2005-01-01

A novel Bragg FEL scheme is discussed in which an electron beam synchronously interacts with a propagating wave, and the latter is coupled to a quasi cut-off mode. This coupling is realized by either helical or asimuthally symmetric corrugation of the waveguide walls. The quasi cut-off mode provides feedback in the system leading to self-excitation of the whole system while the efficiency in steady-state regime of generation is almost completely determined by the propagating mode, synchronous to the beam. Analysis based on averaged time domain approach as well as on direct PIC code simulation shows that the efficiency of such a device in the single mode single frequency regime can be rather high. The main advantage of the novel Bragg resonator is provision of higher selectivity over transverse index than traditional scheme of Bragg FEL. The cold microwave testing of the Bragg structure based on coupling of propagating and trapped waves in the Ka band demonstrated a good agreement with theoretical consideratio...

Optimizing structure in nanodiamonds using in-situ strain-sensitive Bragg coherent diffraction imaging.

Science.gov (United States)

Hruszkewycz, Stephan; Cha, Wonsuk; Ulvestad, Andrew; Fuoss, Paul; Heremans, F. Joseph; Harder, Ross; Andrich, Paolo; Anderson, Christopher; Awschalom, David

The nitrogen-vacancy center in diamond has attracted considerable attention for nanoscale sensing due to unique optical and spin properties. Many of these applications require diamond nanoparticles which contain large amounts of residual strain due to the detonation or milling process used in their fabrication. Here, we present experimental, in-situ observations of changes in morphology and internal strain state of commercial nanodiamonds during high-temperature annealing using Bragg coherent diffraction imaging to reconstruct a strain-sensitive 3D image of individual sub-micron-sized crystals. We find minimal structural changes to the nanodiamonds at temperatures less than 650 C, and that at higher temperatures up to 750 C, the diamond-structured volume fraction of nanocrystals tend to shrink. The degree of internal lattice distortions within nanodiamond particles also decreases during the anneal. Our findings potentially enable the design of efficient processing of commercial nanodiamonds into viable materials suitable for device design. We acknowledge support from U.S. DOE, Office of Science, BES, MSE.

Photonic bandgap narrowing in conical hollow core Bragg fibers

Energy Technology Data Exchange (ETDEWEB)

Ozturk, Fahri Emre; Yildirim, Adem; Kanik, Mehmet [UNAM-National Nanotechnology Research Center, Bilkent University, 06800 Ankara (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Bayindir, Mehmet, E-mail: bayindir@nano.org.tr [UNAM-National Nanotechnology Research Center, Bilkent University, 06800 Ankara (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Department of Physics, Bilkent University, 06800 Ankara (Turkey)

2014-08-18

We report the photonic bandgap engineering of Bragg fibers by controlling the thickness profile of the fiber during the thermal drawing. Conical hollow core Bragg fibers were produced by thermal drawing under a rapidly alternating load, which was applied by introducing steep changes to the fiber drawing speed. In conventional cylindrical Bragg fibers, light is guided by omnidirectional reflections from interior dielectric mirrors with a single quarter wave stack period. In conical fibers, the diameter reduction introduced a gradient of the quarter wave stack period along the length of the fiber. Therefore, the light guided within the fiber encountered slightly smaller dielectric layer thicknesses at each reflection, resulting in a progressive blueshift of the reflectance spectrum. As the reflectance spectrum shifts, longer wavelengths of the initial bandgap cease to be omnidirectionally reflected and exit through the cladding, which narrows the photonic bandgap. A narrow transmission bandwidth is particularly desirable in hollow waveguide mid-infrared sensing schemes, where broadband light is coupled to the fiber and the analyte vapor is introduced into the hollow core to measure infrared absorption. We carried out sensing simulations using the absorption spectrum of isopropyl alcohol vapor to demonstrate the importance of narrow bandgap fibers in chemical sensing applications.

Holographic recording in a doubly doped lithium niobate crystal with two wavelengths: a blue laser diode and a green laser

Science.gov (United States)

Komori, Yuichi; Ishii, Yukihiro

2010-08-01

A doubly-doped LiNbO3 (LN) crystal has been well used as a nonvolatile two-wavelength recording material. By using two levels of the crystal, two-kind holograms can be recorded on one crystal; a hologram is recorded with a 405-nm blue laser diode (LD) for a deep Mn level, and another hologram is with a 532-nm green laser for a shallow Fe level. The recording capacity doubles. A 780-nm LD is non-volatile reconstructing source since the LD line is insensitive to both levels. Multiplexed reconstructed images are demonstrated by using a sharp angular selectivity of a volume LN crystal keeping Bragg condition with spherical reconstructions.

Growth, spectral, dielectric and antimicrobial studies on 4-piperidinium carboxylamide picrate crystals

Science.gov (United States)

Dhanabal, T.; Tharanitharan, V.; Amirthaganesan, G.; Dhandapani, M.

2014-07-01

Single crystal of 4-piperidinium carboxylamide picrate was grown by slow evaporation solution growth technique at ambient temperature. The average dimensions of grown crystal were 0.7 × 0.3 × 0.2 cm3. The solubility of the compound was analyzed using methanol and acetone. Optical property of the compound was ascertained by UV-visible absorption spectral study. The sharp and well defined Bragg peaks observed in the powder X-ray diffraction pattern confirm its crystallinity. The different kinds of protons and carbons in the compound were confirmed by 1H and 13C NMR spectral analyses. The presence of various functional groups in the compound was assigned through polarized Raman spectral study. The mechanical property of the crystal was measured by Vicker's microhardness test and the compound was found to be soft material. The dielectric constant and dielectric loss of the crystal decrease with increase in frequency. The antibacterial and antifungal activities of the crystal were studied by disc diffusion method and found that the compound shows good inhibition efficiency against various bacteria and fungi species.

Photonic crystals with plasmonic patterns: novel type of the heterostructures for enhanced magneto-optical activity

International Nuclear Information System (INIS)

Khokhlov, N E; Belotelov, V I; Prokopov, A R; Shaposhnikov, A N; Berzhansky, V N; Kozhaev, M A; Andreev, S N; Zvezdin, A K; Ravishankar, Ajith P; Achanta, Venu Gopal; Bykov, D A

2015-01-01

A multilayer structure consisting of a magnetophotonic crystal with a rare-earth iron garnet microresonator layer and plasmonic grating deposited on it was fabricated and studied in order to combine functionalities of photonic and plasmonic crystals. The plasmonic pattern allows excitation of the hybrid plasmonic-waveguide modes localized in dielectric Bragg mirrors of the magnetophotonic crystal or waveguide modes inside its microresonator layer. These modes give rise to the additional resonances in the optical spectra of the structure and to the enhancement of the magneto-optical effects. The Faraday effect increases by about 50% at the microresonator modes while the transverse magneto-optical Kerr effect demonstrates pronounced peculiarities at both hybrid waveguide modes and microresonator modes and increases by several times with respect to the case of the bare magnetophotonic crystal without the metal grating. (paper)

Omnidirectional mirror based on Bragg stacks with a periodic gain-loss modulation

Energy Technology Data Exchange (ETDEWEB)

Manzanares-Martinez, Jesus; Ham-Rodriguez, Carlos Ivan [Departamento de Investigacion en Fisica, Universidad de Sonora, Apartado Postal 5-088, Hermosillo, Sonora 83000 (Mexico); Moctezuma-Enriquez, Damian, E-mail: foxonicos@gmail.com [Centro de Investigacion en Materiales Avanzados (CIMAV), Miguel de Cervantes 120, Chihuahua 31109 (Mexico); Manzanares-Martinez, Betsabe [Departamento de Fisica, Universidad de Sonora, Blvd. Luis Encinas y Rosales, Hermosillo, Sonora 83000 (Mexico)

2014-01-15

In this work we demonstrate that a Bragg Stack with a periodic gain-loss modulation can function as an Omnidirectional Mirror (OM) with complete reflection at any angle of incidence irrespective of the light polarization. The Bragg Stack is composed by the periodic variation of two layers with the same value of the real part of the refractive index (n{sub r}) and a periodic modulation in the imaginary part (n{sub i}). The origin of the band gaps is due to the interference of complex waves with propagating and evanescent fields in each layer. It is found that the band gaps are wider as the contrast n{sub i}/n{sub r} increases. We have found the ambient conditions to obtain an OM considering an auxiliary medium n{sup ′} external to the Bragg Stack.

Large-area photonic crystals

Science.gov (United States)

Ruhl, Tilmann; Spahn, Peter; Hellmann, Gotz P.; Winkler, Holger

2004-09-01

Materials with a periodically modulated refractive index, with periods on the scale of light wavelengths, are currently attracting much attention because of their unique optical properties which are caused by Bragg scattering of the visible light. In nature, 3d structures of this kind are found in the form of opals in which monodisperse silica spheres with submicron diameters form a face-centered-cubic (fcc) lattice. Artificial opals, with the same colloidal-crystalline fcc structure, have meanwhile been prepared by crystallizing spherical colloidal particles via sedimentation or drying of dispersions. In this report, colloidal crystalline films are introduced that were produced by a novel technique based on shear flow in the melts of specially designed submicroscopic silica-polymer core-shell hybrid spheres: when the melt of these spheres flows between the plates of a press, the spheres crystallize along the plates, layer by layer, and the silica cores assume the hexagonal order corresponding to the (111) plane of the fcc lattice. This process is fast and yields large-area films, thin or thick. To enhance the refractive index contrast in these films, the colloidal crystalline structure was inverted by etching out the silica cores with hydrofluoric acid. This type of an inverse opal, in which the fcc lattice is formed by mesopores, is referred to as a polymer-air photonic crystal.

Graphite analyser upgrade for the IRIS spectrometer at ISIS

International Nuclear Information System (INIS)

Campbell, S.I.; Telling, M.T.F.; Carlile, C.J.

1999-01-01

Complete text of publication follows. The pyrolytic graphite (PG) analyser bank on the IRIS high resolution inelastic spectrometer [1] at ISIS is to be upgraded. At present the analyser consists of 1350 graphite pieces (6 rows by 225 columns) cooled to 25K [2]. The new analyser array, however, will provide a three-fold increase in area and employ 4212 crystal pieces (18 rows by 234 columns). In addition, the graphite crystals will be cooled close to liquid helium temperature to further reduce thermal diffuse scattering (TDS) and improve the sensitivity of the spectrometer [2]. For an instrument such as IRIS, with its analyser in near back-scattering geometry, optical aberration and variation in the time-of-flight of the analysed neutrons is introduced as one moves out from the horizontal scattering plane. To minimise such effects, the profile of the analyser array has been redesigned. The concept behind the design of the new analyser bank and factors that effect the overall resolution of the instrument are discussed. Results of Monte Carlo simulations of the expected resolution and intensity of the complete instrument are presented and compared to the current instrument performance. (author) [1] C.J. Carlile et al, Physica B 182 (1992) 431-440.; [2] C.J. Carlile et al, Nuclear Instruments and Methods In Physics Research A 338 (1994) 78-82

Time and space domain separation of pulsed X-ray beams diffracted from vibrating crystals

Energy Technology Data Exchange (ETDEWEB)

Nosik, V. L., E-mail: v-nosik@yandex.ru, E-mail: nosik@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics,” (Russian Federation)

2016-11-15

It is known that a set of additional reflections (satellites) may arise on rocking curves in the case of X-ray diffraction in the Bragg geometry from crystals where high-frequency ultrasonic vibrations are excited. It is shown that, under certain conditions, the pulse wave fields of the satellites and main reflection may be intersected in space (playing the role of pump and probe beams) and in time (forming interference superlattices).

Measuring 137Cs, 40K and decay products of 226Ra and 232Th in samples of different nature by a multidetector spectrometer

International Nuclear Information System (INIS)

Antovic, N.M.; Popovic, V.; Vukotic, P.

2011-01-01

A coincidence method for measuring 137 Cs, 40 K, 226 Ra and 232 Th decay products activity in soil, vegetation and fish samples, was applied to the six-crystal gamma-coincidence spectrometer PRIPYAT-2M. In this way, some problems appeared in simultaneous measurement of 137 Cs, 226 Ra and 232 Th by NaI(Tl) detectors and the PRIPYAT-2M spectrometer were solved. The obtained results were agreeable with the HPGe spectrometer ones. (author)

Correlation spectrometer

Science.gov (United States)

Sinclair, Michael B [Albuquerque, NM; Pfeifer, Kent B [Los Lunas, NM; Flemming, Jeb H [Albuquerque, NM; Jones, Gary D [Tijeras, NM; Tigges, Chris P [Albuquerque, NM

2010-04-13

A correlation spectrometer can detect a large number of gaseous compounds, or chemical species, with a species-specific mask wheel. In this mode, the spectrometer is optimized for the direct measurement of individual target compounds. Additionally, the spectrometer can measure the transmission spectrum from a given sample of gas. In this mode, infrared light is passed through a gas sample and the infrared transmission signature of the gasses present is recorded and measured using Hadamard encoding techniques. The spectrometer can detect the transmission or emission spectra in any system where multiple species are present in a generally known volume.

Development and Performance Characteristics of Personal Gamma Spectrometer for Radiation Monitoring Applications

Directory of Open Access Journals (Sweden)

Hye Min Park

2016-06-01

Full Text Available In this study, a personal gamma (γ spectrometer was developed for use in applications in various fields, such as homeland security and environmental radiation monitoring systems. The prototype consisted of a 3 × 3 × 20 mm3 Ce-doped Gd–Al–Ga–garnet (Ce:GAGG crystal that was coupled to a Si photomultiplier (SiPM to measure γ radiation. The γ spectrometer could be accessed remotely via a mobile device. At room temperature, the implemented Ce:GAGG-SiPM spectrometer achieved energy resolutions of 13.5%, 6.9%, 5.8%, and 2.3% for 133Ba at 0.356 MeV, 22Na at 0.511 MeV, 137Cs at 0.662 MeV, and 60Co at 1.33 MeV, respectively. It consumed only about 2.7 W of power, had a mass of just 340 g (including the battery, and measured only 5.0 × 7.0 cm2.

X-ray diagnostics of He-like titanium with the bent crystal spectrometer on FTU

International Nuclear Information System (INIS)

Leigheb, M.

1999-01-01

X-ray spectra due to intrinsic Titanium are obtained on the FTU tokamak by using a space resolved bent crystal spectrometer. In a single discharge, spectra along five lines of sight with a maximum of 16 acquisitions at different times are recorded. Line identification is straightforward from previously published Ti spectra, and no wavelength disagreement (within the experimental errors) has been observed. To fit the spectra, three different methods are tested, each having as free parameters the background level, position (i.e. channel number of the peak) intensity and width of the resonance w line, and line intensity ratios of the satellites with respect to the resonance. Many information can be deduced from the results of the fit: ion and electron temperatures, He-like/Li-like ion charge ratio. Titanium density in the plasma core. Synthetic spectra built up with the values calculated by the fits are compared with the experimental data, and the temperature values are compared with the values from other diagnostics. The best agreement for ion and electron temperatures is obtained by simultaneous fitting of the resonance with 29 most prominent resolved and unresolved satellites; intensities of the dielectronic satellites have been calculated with the Boltzmann-Saha equation, while intensities of intercombination lines x and y and forbidden line z have been calculated with the Mewe's formula. For the dielectronic satellites as well as for intercombination lines, simulations are satisfactory, whereas for the forbidden line z the simulated lines are only 15-30% of the corresponding experimental values. A comparison of the resonance peak positions in different lines of sight allowed to exclude poloidal plasma rotation velocities > 2 10 4 m/s [it

Status of the development of a HPGe-BGO pair spectrometer for ELI-NP

Energy Technology Data Exchange (ETDEWEB)

Homm, Ilja; Ignatov, Alexander; Ilieva, Stoyanka; Kroell, Thorsten [Technische Universitaet Darmstadt, Darmstadt (Germany)

2016-07-01

At the moment, the new European research facility called ELI-NP (The Extreme Light Infrastructure - Nuclear Physics) is being built in Bucharest-Magurele, Romania. It is one of three parts of the ELI project and offers applications for the investigation of questions concerning nuclear physics. The 8 HPGe (High-Purity Germanium) CLOVER detectors of ELIADE (ELI-NP Array of DEtectors) with four crystals each and high resolution are important components for the gamma spectroscopic study of photonuclear reactions. These detectors are surrounded by standard anti-Compton shields (AC shield). We investigate the possibility to operate for two of the ELIADE CLOVERS an advanced version of an AC shield as escape γ-rays pair spectrometers to extend the high-resolution spectroscopy to photon energies of several MeV where the pair production process dominates. The main tasks in this work are to develop and test such an AC shield: a pair spectrometer with BGO and CsI(Tl) crystals with APD (avalanche photodiode) or SPM (silicon photomultiplier) readout. The results of prototype testing are reported.

High-resolution mapping of two-dimensional lattice distortions in ion-implanted crystals from X-ray diffractometry data

International Nuclear Information System (INIS)

Nikulin, A.Y.; Gureyev, T.E.; Stevenson, A.W.; Wilkins, S.W.; Hashizume, H.; Cookson, D.

1996-01-01

The triple-crystal synchrotron X-ray diffractometry data described in Nikulin, Stevenson, Hashizume, Wilkins, Foran, Cookson and Garrett (J. Appl. Cryst. 28, 57-60 (1995)) has been analyzed to map out two-dimensional (2D) lattice distortions in silicon (111) crystals implanted with B + ions of 100 keV energy through a periodic SiO 2 strip pattern. The lateral periodic structure produced a series of satellite reflections associated with the 111 Bragg peak. The 2D reconstruction incorporates the use of the Petrashen-Chukhovskii method, which retrieves the phases of the Bragg waves for these satellite reflections, together with that for the fundamental. The finite Fourier series is then synthesized with the relative phases determined. Localized distortions perpendicular to the surface arising from deposited B + ions in near-surface layers of the crystal are clearly displayed with spatial resolutions of 0.016 and 0.265 μm in the depth and lateral directions respectively. For a sample with the oxide layer removed from the surface, two equally plausible strain maps have been obtained by assigning relative phases to eleven satellites using a sequential trial method and a minimum-energy method. Failed map reconstructions for the oxide-covered sample are discussed in terms of the non-unique solutions of the Petrashen-Chukhovskii phase-recovery algorithm and the ambiguous phases determined for the satellites. 16 refs., 8 figs

Wavelength interrogation of fiber Bragg grating sensors using tapered hollow Bragg waveguides.

Science.gov (United States)

Potts, C; Allen, T W; Azar, A; Melnyk, A; Dennison, C R; DeCorby, R G

2014-10-15

We describe an integrated system for wavelength interrogation, which uses tapered hollow Bragg waveguides coupled to an image sensor. Spectral shifts are extracted from the wavelength dependence of the light radiated at mode cutoff. Wavelength shifts as small as ~10  pm were resolved by employing a simple peak detection algorithm. Si/SiO₂-based cladding mirrors enable a potential operational range of several hundred nanometers in the 1550 nm wavelength region for a taper length of ~1  mm. Interrogation of a strain-tuned grating was accomplished using a broadband amplified spontaneous emission (ASE) source, and potential for single-chip interrogation of multiplexed sensor arrays is demonstrated.

Interfacing an aspiration ion mobility spectrometer to a triple quadrupole mass spectrometer

International Nuclear Information System (INIS)

Adamov, Alexey; Viidanoja, Jyrki; Kaerpaenoja, Esko; Paakkanen, Heikki; Ketola, Raimo A.; Kostiainen, Risto; Sysoev, Alexey; Kotiaho, Tapio

2007-01-01

This article presents the combination of an aspiration-type ion mobility spectrometer with a mass spectrometer. The interface between the aspiration ion mobility spectrometer and the mass spectrometer was designed to allow for quick mounting of the aspiration ion mobility spectrometer onto a Sciex API-300 triple quadrupole mass spectrometer. The developed instrumentation is used for gathering fundamental information on aspiration ion mobility spectrometry. Performance of the instrument is demonstrated using 2,6-di-tert-butyl pyridine and dimethyl methylphosphonate

Probing Dynamics in Colloidal Crystals with Pump-Probe Experiments at LCLS: Methodology and Analysis

Directory of Open Access Journals (Sweden)

Nastasia Mukharamova

2017-05-01

Full Text Available We present results of the studies of dynamics in colloidal crystals performed by pump-probe experiments using an X-ray free-electron laser (XFEL. Colloidal crystals were pumped with an infrared laser at a wavelength of 800 nm with varying power and probed by XFEL pulses at an energy of 8 keV with a time delay up to 1000 ps. The positions of the Bragg peaks, and their radial and azimuthal widths were analyzed as a function of the time delay. The spectral analysis of the data did not reveal significant enhancement of frequencies expected in this experiment. This allowed us to conclude that the amplitude of vibrational modes excited in colloidal crystals was less than the systematic error caused by the noise level.

High-efficiency FEL with Bragg resonator driven by linear induction accelerator

Energy Technology Data Exchange (ETDEWEB)

Ginzburg, N S; Kaminskij, A A; Kaminskij, A K; Peskov, N Yu; Sedykh, S N; Sergeev, A P; Sergeev, A S [Russian Academy of Sciences, Nizhny Novgorod (Russian Federation). Inst. of Applied Physics

1997-12-31

A narrow-band high-efficiency FEL-oscillator with a Bragg resonator was constructed based on a linear induction accelerator which formed a 1 MeV, 200 A, 200 ns electron beam. At the frequency of 31 GHz, radiation with a power of 31 MW and efficiency of 25% was measured. A high efficiency and a narrow width of the spectrum were achieved owing to the selective properties of the Bragg resonator in combination with the high quality of the helical electron beam formed in the reversed guide field regime. (author). 3 figs., 3 refs.

Fiber Bragg Grating vibration sensor with DFB laser diode

Science.gov (United States)

Siska, Petr; Brozovic, Martin; Cubik, Jakub; Kepak, Stanislav; Vitasek, Jan; Koudelka, Petr; Latal, Jan; Vasinek, Vladimir

2012-01-01

The Fiber Bragg Grating (FBG) sensors are nowadays used in many applications. Thanks to its quite big sensitivity to a surrounding environment, they can be used for sensing of temperature, strain, vibration or pressure. A fiber Bragg grating vibration sensor, which is interrogated by a distributed feedback laser diode (DFB) is demonstrated in this article. The system is based on the intensity modulation of the narrow spectral bandwidth of the DFB laser, when the reflection spectrum of the FBG sensor is shifted due to the strain that is applied on it in form of vibrations caused by acoustic wave pressure from loud speaker. The sensor's response in frequency domain and strain is measured; also the factor of sensor pre-strain impact on its sensitivity is discussed.

Capacity of Wavelength and Time Division Multiplexing for Quasi-Distributed Measurement Using Fiber Bragg Gratings

Directory of Open Access Journals (Sweden)

Marcel Fajkus

2015-01-01

Full Text Available In this paper, an analysis of the use of wavelength and time division multiplexing techniques for quasi-distributed measurement in uniform fiber Bragg gratings is presented. To date, publications have concentrated on the determination of the maximum number of fiber Bragg gratings on one optical fiber using wavelength and time division multiplexing. In this paper, these techniques will be extended to determine the spectral width of wavelength division multiplexing in terms of the spectral width of the light emitting diode, the spectral width of the Bragg gratings, the measurement ranges of the individual sensors, and the guard band between two adjacent Bragg gratings. For time division multiplexing, a description of the time and power conditions are given. In particular the reflected power, first order crosstalk and chromatic dispersion have been considered. Finally, these relationships were applied to verify a design in a simulation using OptiSystem software.

Polydispersity effects in the crystallisation of hard-sphere colloidal samples

International Nuclear Information System (INIS)

Martin, S.; Bryant, G.

2002-01-01

Full text: Colloidal particles mimicking hard-sphere behaviour have been shown to undergo the freezing and melting transition as predicted from computer simulations. Due to the large size and slow movement of the colloidal particles, it is possible to measure the time dependence of the growth of the main Bragg reflection using laser light scattering. The new data presented here was taken on a newly built crystallisation spectrometer which averages the Bragg reflections over the whole Debye-Scherrer cone, where previous work has mostly been done with the detector fixed in one plane. This new apparatus allows us to observe the crystallisation process at earlier times, on lower density samples than had previously been possible. Measurements have been made on samples made from colloidal particles with radii 320nm and 247 nm and polydispersities of ∼6.9% and >8% respectively. The results have been compared with other results from particles with >4% polydispersity. The results show that increasing the polydispersity in the particles increases the time lag before significant crystal growth occurs, but polydispersity doesn't appear to directly affect the rate of crystal growth

A compact double crystal monochromator for electrochemistry beamline at PLS

CERN Document Server

Rah, S; Kim, G H

2001-01-01

A compact double crystal monochromator based on 16.5'' CF flange has been designed, fabricated and installed for electrochemistry beamline at Pohang light source. The Bragg angle range of the monochromator is 7-75 deg. The mechanical design is modified from typical Boomerang design [J.A. Golovchenko et al., Rev. Sci. Instrum. 52 (1981) 509; J.P. Kirkland, Nucl. Instr. and Meth. A291 (1990) 185] to have fixed beam offset and single driving axis for spectroscopy experiments. The parallelism error of the crystals is minimized to less than 6 mu rad for the range, by using a precision single axis linear guide, Also, the number of mechanical parts in the vacuum is minimized and 1.8x10 sup - sup 9 Torr of vacuum is achieved without baking.

IPNS time-of-flight single crystal diffractometer

International Nuclear Information System (INIS)

Schultz, A.J.; Teller, R.G.; Williams, J.M.

1983-01-01

The single crystal diffractometer (SCD) at the Argonne Intense Pulsed Neutron Source (IPNS) utilizes the time-of-flight (TOF) Laue technique to provide a three-dimensional sampling of reciprocal space during each pulse. The instrument contains a unique neutron position-sensitive 6 Li-glass scintillation detector with an active area of 30 x 30 cm. The three-dimensional nature of the data is very useful for fast, efficient measurement of Bragg intensities and for the studies of superlattice and diffuse scattering. The instrument was designed to achieve a resolution of 2% or better (R = δQ/Q) with 2 THETA > 60 0 and lambda > 0.7A

Continuous liquid level monitoring sensor system using fiber Bragg grating

Science.gov (United States)

Sengupta, Dipankar; Kishore, Putha

2014-01-01

The design and packaging of simple, small, and low cost sensor heads, used for continuous liquid level measurement using uniformly thinned (etched) optical fiber Bragg grating (FBG) are proposed. The sensor system consists of only an FBG and a simple detection system. The sensitivity of sensor is found to be 23 pm/cm of water column pressure. A linear optical fiber edge filter is designed and developed for the conversion of Bragg wavelength shift to its equivalent intensity. The result shows that relative power measured by a photo detector is linearly proportional to the liquid level. The obtained sensitivity of the sensor is nearly -15 mV/cm.

Inelastic neutron scattering experiments with the monochromatic imaging mode of the RITA-II spectrometer

International Nuclear Information System (INIS)

Bahl, C.R.H.; Lefmann, K.; Abrahamsen, A.B.; Ronnow, H.M.; Saxild, F.; Jensen, T.B.S.; Udby, L.; Andersen, N.H.; Christensen, N.B.; Jakobsen, H.S.; Larsen, T.; Haefliger, P.S.; Streule, S.; Niedermayer, Ch.

2006-01-01

Recently a monochromatic multiple data taking mode has been demonstrated for diffraction experiments using a RITA type cold neutron spectrometer with a multi-bladed analyser and a position-sensitive detector. Here, we show how this mode can be used in combination with a flexible radial collimator to perform real inelastic neutron scattering experiments. We present the results from inelastic powder, single crystal dispersion and single crystal constant energy mapping experiments. The advantages and complications of performing these experiments are discussed along with a comparison between the imaging mode and the traditional monochromatic focussing mode

Inelastic neutron scattering experiments with the monochromatic imaging mode of the RITA-II spectrometer

Energy Technology Data Exchange (ETDEWEB)

Bahl, C.R.H. [Department of Materials Research, Riso National Laboratory, Building 227, Frederiksborgvej 399, DK-4000 Roskilde (Denmark) and Department of Physics, Technical University of Denmark, DK-2800 Lyngby (Denmark)]. E-mail: christian.bahl@risoe.dk; Lefmann, K. [Department of Materials Research, Riso National Laboratory, Building 227, Frederiksborgvej 399, DK-4000 Roskilde (Denmark)]. E-mail: kim.lefmann@risoe.dk; Abrahamsen, A.B. [Department of Materials Research, Riso National Laboratory, Building 227, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Ronnow, H.M. [Laboratory for Neutron Scattering, Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Saxild, F. [Department of Materials Research, Riso National Laboratory, Building 227, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Jensen, T.B.S. [Department of Materials Research, Riso National Laboratory, Building 227, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Udby, L. [Department of Materials Research, Riso National Laboratory, Building 227, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Andersen, N.H. [Department of Materials Research, Riso National Laboratory, Building 227, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Christensen, N.B. [Department of Materials Research, Riso National Laboratory, Building 227, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Laboratory for Neutron Scattering, Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Jakobsen, H.S. [Niels Bohr Institute for Astronomy, Physics and Geophysics, University of Copenhagen, DK-2100 Copenhagen (Denmark); Larsen, T. [Niels Bohr Institute for Astronomy, Physics and Geophysics, University of Copenhagen, DK-2100 Copenhagen (Denmark); Haefliger, P.S. [Laboratory for Neutron Scattering, Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Streule, S.; Niedermayer, Ch. [Laboratory for Neutron Scattering, Paul Scherrer Institute, CH-5232 Villigen (Switzerland)

2006-05-15

Recently a monochromatic multiple data taking mode has been demonstrated for diffraction experiments using a RITA type cold neutron spectrometer with a multi-bladed analyser and a position-sensitive detector. Here, we show how this mode can be used in combination with a flexible radial collimator to perform real inelastic neutron scattering experiments. We present the results from inelastic powder, single crystal dispersion and single crystal constant energy mapping experiments. The advantages and complications of performing these experiments are discussed along with a comparison between the imaging mode and the traditional monochromatic focussing mode.

Optical fiber laser sensor with a cavity of 8.6 Km formed by two fiber Bragg gratings used as mirrors

Energy Technology Data Exchange (ETDEWEB)

May A, M.; Kuzin, E.A.; Vazquez S, R.A. [Instituto Nacional de Astrofisica, Optica y Electronica, A. P. 51 y 216, C.P. 72000 Puebla (Mexico); Basurto P, M.A. [Universidad Autonoma del Estado de Morelos, Av. Universidad No. 1001, Col. Chamilpa, C.P. 62210 Cuernavaca, Morelos (Mexico); Shlyagin, M.G.; Marquez B, I. [Centro de Investigacion Cientifica y de Ensenanza Superior de Ensenada, C.P. 22860 Ensenada, Baja California (Mexico)

2002-07-01

We report the operation of a fiber laser sensor made by an Erbium Doped Fiber pumped at 980 nm, an 8.67 km passive fiber and two fiber Bragg gratings placed at the ends of the laser cavity. Under normal conditions, the Bragg gratings have different reflection wavelengths and laser emission is not generated. The two Bragg gratings can be placed at the same reflection wavelength when the Bragg grating with the lowest reflective wavelength is strained which can be used as a sensor element. The laser generation thus shows that the Bragg grating is under strain. Furthermore, our configuration give us the possibility for knowing the distance between two Bragg gratings when the laser beating frequency is measured. A measurement precision better than 25 m in 8.67 Km is shown to be feasible. (Author)

Optical fiber laser sensor with a cavity of 8.6 Km formed by two fiber Bragg gratings used as mirrors

CERN Document Server

May, M; Vázquez, R A; Basurto, M A; Shlyagin, M G; Márquez, I

2002-01-01

We report the operation of a fiber laser sensor made by an Erbium Doped Fiber pumped at 980 nm, an 8.67 km passive fiber and two fiber Bragg gratings placed at the ends of the laser cavity. Under normal conditions, the Bragg gratings have different reflection wavelengths and laser emission is not generated. The two Bragg gratings can be placed at the same reflection wavelength when the Bragg grating with the lowest reflective wavelength is strained which can be used as a sensor element. The laser generation thus shows that the Bragg grating is under strain. Furthermore, our configuration give us the possibility for knowing the distance between two Bragg gratings when the laser beating frequency is measured. A measurement precision better than 25 m in 8.67 Km is shown to be feasible. (Author)

Resonantly scattering crystals and surfaces

International Nuclear Information System (INIS)

Gunn, J.M.F.; Mahon, P.J.

1990-12-01

We examine coherence effects from forming a crystal of resonant scatterers by generalising the Fano model for autoionising resonances in electron scattering from atoms to a lattice of such scatterers. (We have in mind the case of neutron scattering from nuclei.) We solve this problem to yield two branches to the dispersion relation for the neutron in general and three when the resonance coincides with a Brillouin Zone boundary. The 'width' of the resonance is enhanced over the isolated nucleus, the best candidate for observation being the 2eV 185 Re resonance near the Bragg condition. We use these results to calculate the reflection coefficient from a surface, revealing total external reflection near resonance. We discuss experimental feasibility in both the neutron and electron cases. (author)

Inelastic scattering of fast electrons by crystals

International Nuclear Information System (INIS)

Allen, L.J.; Josefsson, T.W.

1995-01-01

Generalized fundamental equations for electron diffraction in crystals, which include the effect of inelastic scattering described by a nonlocal interaction, are derived. An expression is obtained for the cross section for any specific type of inelastic scattering (e.g. inner-shell ionization, Rutherford backscattering). This result takes into account all other (background) inelastic scattering in the crystal leading to absorption from the dynamical Bragg-reflected beams, in practice mainly due to thermal diffuse scattering. There is a contribution to the cross section from all absorbed electrons, which form a diffuse background, as well as from the dynamical electrons. The approximations involved, assuming that the interactions leading to inelastic scattering can be described by a local potential are discussed, together with the corresponding expression for the cross section. It is demonstrated by means of an example for K-shell electron energy loss spectroscopy that nonlocal effects can be significant. 47 refs., 4 figs

Moessbauer determination of magnetic structure of Fe3BO6 crystal

International Nuclear Information System (INIS)

Kovalenko, P.P.; Labushkin, V.G.; Ovsepyan, A.K.; Sarkisov, Eh.R.; Smirnov, E.V.; Prokopov, A.R.; Seleznev, V.N.

1984-01-01

The magnetic structure of a Fe 3 BO 6 crystal belonging to space group Dsub(2h)sup(16)(Psub(nma)) is determined by the Moessbauer γ-radiation diffraction. The bragg reflection (700) of Moessbauer 14.4 keV γ-quanta from the Fe 3 BO 6 monocrystal has been studied experimentally. A high sensitivity of the interference of γ-quantum diffraction scattering on Fe nuclei being in crystallographically non-equivalent 8d- and 4s-positions to the type of magnetic ordering in the crystal is used for determination of the magnetic structure. Agreement of the experimental results with the theoretical calculations, conducted for types of magnetic ordering resolved by the symmetry of the crystal, permitted to reliably determine the magnetic structure of this compound. The results obtained confirm the data of neutrondiffraction studies on magnetic ordering in Fe 3 BO 6 . Advantages of the Moessbauer-diffraction study, as compared to the magnetic neutrondiffraction method, in particular, for investigation of crystals, in which the hyperfine magnetic fields on Fe nuclei have different values, are revealed and discussed in detail

Experimental demonstration of a Fano laser based on photonic crystals

DEFF Research Database (Denmark)

Yu, Yi; Semenova, Elizaveta; Yvind, Kresten

2017-01-01

Conventional semiconductor laser mirrors are based on Fresnel reflection [1], Bragg reflection [2, 3] or total internal reflection [4]. Here we demonstrate a new laser concept using photonic crystals (PhC), with a mirror based on Fano interference between a waveguide continuum and a discrete...... resonance of a nanocavity [5]. We show that the very narrowband feature of the Fano resonance [6] can lead to single mode lasing. In addition, when combined with optical nonlinearity, the highly dispersive feature of the Fano resonance can promote self-pulsations at gigahertz frequencies [7], which...

Icosahedral symmetry described by an incommensurately modulated crystal structure model

DEFF Research Database (Denmark)

Wolny, Janusz; Lebech, Bente

1986-01-01

A crystal structure model of an incommensurately modulated structure is presented. Although six different reciprocal vectors are used to describe the model, all calculations are done in three dimensions making calculation of the real-space structure trivial. Using this model, it is shown that both...... the positions of the bragg reflections and information about the relative intensities of these reflections are in full accordance with the diffraction patterns reported for microcrystals of the rapidly quenched Al86Mn14 alloy. It is also shown that at least the local structure possesses full icosahedral...

Self-Detection of Leaking Pipes by One-Dimensional Photonic Crystals

International Nuclear Information System (INIS)

Zhou Yan; Yin Li-Qun

2012-01-01

We report a new self-detection control system for leaking pipes by making use of the surface defects of 1D photonic crystals, where the key concept is analog to the Bragg fiber structure. The current low costs and coating techniques of SiO 2 are beneficial to the applications, and its error is below the standard requirement. The problem of leaking pipes can be resolved by devising a remote pipeline control system which combines a long-distance pipeline and a signal transmission system. (fundamental areas of phenomenology(including applications))

Time-of-flight neutron Bragg-edge transmission imaging of microstructures in bent steel plates

Energy Technology Data Exchange (ETDEWEB)

Su, Yuhua, E-mail: yuhua.su@j-parc.jp [J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195 (Japan); Oikawa, Kenichi; Harjo, Stefanus; Shinohara, Takenao; Kai, Tetsuya; Harada, Masahide; Hiroi, Kosuke [J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195 (Japan); Zhang, Shuoyuan; Parker, Joseph Don [Neutron R& D Division, CROSS-Tokai, 162-1 Shirakata, Tokai, Ibaraki 319-1106 (Japan); Sato, Hirotaka [Faculty of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Shiota, Yoshinori; Kiyanagi, Yoshiaki [Graduate School of Engineering, Nagoya University, Nagoya, Aichi 464-8603 (Japan); Tomota, Yo [Research Center for Strategic Materials, National Institute for Materials Science, Tsukuba 305-0047 (Japan)

2016-10-15

Neutron Bragg-edge transmission imaging makes it possible to quantitatively visualize the two-dimensional distribution of microstructure within a sample. In order to examine its application to engineering products, time-of-flight Bragg-edge transmission imaging experiments using a pulsed neutron source were performed for plastically bent plates composed of a ferritic steel and a duplex stainless steel. The non-homogeneous microstructure distributions, such as texture, crystalline size, phase volume fraction and residual elastic strain, were evaluated for the cross sections of the bent plates. The obtained results were compared with those by neutron diffraction and electron back scatter diffraction, showing that the Bragg-edge transmission imaging is powerful for engineering use.

Refractive index sensing based on higher-order mode reflection of a microfiber Bragg grating.

Science.gov (United States)

Zhang, Yu; Lin, Bo; Tjin, Swee Chuan; Zhang, Han; Wang, Guanghui; Shum, Ping; Zhang, Xinliang

2010-12-06

A fiber Bragg grating written in a photosensitive microfiber using KrF excimer laser via a uniform phase mask is demonstrated. We have successfully fabricated two Bragg gratings in microfibers having different diameters. In the reflection spectrum of a microfiber Bragg grating (MFBG), we observed two reflection peaks,which agrees with our numerical simulation results. Compared with the fundamental mode reflection, the higher-order reflection mode is more sensitive to the refractive index (RI) variation of the surrounding fluid due to its larger evanescent field. The measured maximum sensitivity is ~102 nm/RIU (RI unit) at an RI value of 1.378 in an MFBG with a diameter of 6 μm.

Using angular dispersion and anomalous transmission to shape ultramonochromatic x rays

Energy Technology Data Exchange (ETDEWEB)

Shvyd' ko, Yuri; Stoupin, Stanislav; Shu, Deming; Khachatryan, Ruben [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2011-11-15

Optical spectrometers, instruments that work with highly monochromatic light, are commonly rated by the spectral bandwidth, which defines the ability to resolve closely spaced spectral components. Another equally important feature is the spectral contrast, the ability to detect faint objects among these components. Here we demonstrate that a combined effect of angular dispersion (AD) and anomalous transmission (AT) of x rays in Bragg reflection from asymmetrically cut crystals can shape spectral distributions of x rays to profiles with high contrast and small bandwidths. The AD and AT x-ray optics is implemented as a five-reflection, three-crystal arrangement featuring a combination of the above-mentioned attributes so desirable for x-ray monochromators and analyzers: a spectral contrast of {approx_equal} 500, a bandwidth of {approx_equal} 0.46 meV, and a remarkably large angular acceptance of {approx_equal} 107 {mu}rad with 9.1 keV x rays. The new optics can become a foundation for the next-generation inelastic x-ray scattering spectrometers for studies of atomic dynamics.

Magnetic Order and Crystal Field Excitations in Er2Ru2O7: A Neutron Scattering Study

International Nuclear Information System (INIS)

Ehlers, Georg; Gardner, Jason

2009-01-01

The magnetic pyrochlore Er 2 Ru 2 O 7 has been studied with neutron scattering and susceptibility measurements down to a base temperature of 270 mK. For the low temperature phase in which the Er sublattice orders, new magnetic Bragg peaks are reported which can be indexed with integer (hkl) for a face centered cubic cell. Inelastic measurements reveal a wealth of crystal field levels of the Er ion and a copious amount of magnetic scattering below 15 meV. The three lowest groups of crystal field levels are at 6.7, 9.1 and 18.5 meV.

Investigation of the in-solution relaxation of polymer optical fibre Bragg gratings

DEFF Research Database (Denmark)

Fasano, Andrea; Woyessa, Getinet; Janting, Jakob

2016-01-01

We investigate the response of PMMA microstructured polymer optical fibre Bragg gratings whenimmersed in methanol/water solutions. Overall we observe a permanent blue-shift in Bragg gratingwavelength after solvent evaporation. The main contribution in the resonance wavelength shift probably...... arisesfrom a permanent change in the size of the fibre, as already reported for high-temperature annealing ofpolymer optical fibres. As a consequence of the solution concentration dependence of the glass transitiontemperature of polymers, different methanol/water solutions lead to various degrees of frozen...

Automated preparation method for colloidal crystal arrays of monodisperse and binary colloid mixtures by contact printing with a pintool plotter.

Science.gov (United States)

Burkert, Klaus; Neumann, Thomas; Wang, Jianjun; Jonas, Ulrich; Knoll, Wolfgang; Ottleben, Holger

2007-03-13

Photonic crystals and photonic band gap materials with periodic variation of the dielectric constant in the submicrometer range exhibit unique optical properties such as opalescence, optical stop bands, and photonic band gaps. As such, they represent attractive materials for the active elements in sensor arrays. Colloidal crystals, which are 3D gratings leading to Bragg diffraction, are one potential precursor of such optical materials. They have gained particular interest in many technological areas as a result of their specific properties and ease of fabrication. Although basic techniques for the preparation of regular patterns of colloidal crystals on structured substrates by self-assembly of mesoscopic particles are known, the efficient fabrication of colloidal crystal arrays by simple contact printing has not yet been reported. In this article, we present a spotting technique used to produce a microarray comprising up to 9600 single addressable sensor fields of colloidal crystal structures with dimensions down to 100 mum on a microfabricated substrate in different formats. Both monodisperse colloidal crystals and binary colloidal crystal systems were prepared by contact printing of polystyrene particles in aqueous suspension. The array morphology was characterized by optical light microscopy and scanning electron microscopy, which revealed regularly ordered crystalline structures for both systems. In the case of binary crystals, the influence of the concentration ratio of the large and small particles in the printing suspension on the obtained crystal structure was investigated. The optical properties of the colloidal crystal arrays were characterized by reflection spectroscopy. To examine the stop bands of the colloidal crystal arrays in a high-throughput fashion, an optical setup based on a CCD camera was realized that allowed the simultaneous readout of all of the reflection spectra of several thousand sensor fields per array in parallel. In agreement with

Embedding silica and polymer fibre Bragg gratings (FBG) in plastic 3D-printed sensing patches

DEFF Research Database (Denmark)

Zubel, Michal G.; Sugden, Kate; Webb, David J.

2016-01-01

This paper reports the first demonstration of a silica fibre Bragg grating (SOFBG) embedded in an FDM 3-D printed housing to yield a dual grating temperature-compensated strain sensor. We also report the first ever integration of polymer fibre Bragg grating (POFBG) within a 3-D printed sensing...

High-quality single crystal growth and magnetic property of Mn4Ta2O9

Science.gov (United States)

Cao, Yiming; Xu, Kun; Yang, Ya; Yang, Wangfan; Zhang, Yuanlei; Kang, Yanru; He, Xijia; Zheng, Anmin; Liu, Mian; Wei, Shengxian; Li, Zhe; Cao, Shixun

2018-06-01

A large-size single crystal of Mn4Ta2O9 with ∼3.5 mm in diameter and ∼65 mm in length was successfully grown for the first time by a newly designed one-step method based on the optical floating zone technique. Both the clear Laue spots and sharp XRD Bragg reflections suggest the high quality of the single crystal. In Mn4Ta2O9 single crystal, an antiferromagnetic phase transition was observed below Néel temperature 102 K along c axis, which is similar to the isostructural compound Mn4Nb2O9, but differs from the isostructural Co4Nb2O9. Relative dielectric constant at 30 kOe suggests that no magnetoelectric coupling exists in Mn4Ta2O9.

Dose ratio proton radiography using the proximal side of the Bragg peak

Energy Technology Data Exchange (ETDEWEB)

Doolan, P. J., E-mail: paul.doolan.09@ucl.ac.uk; Royle, G.; Gibson, A. [Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT (United Kingdom); Lu, H.-M. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States); Prieels, D.; Bentefour, E. H. [Ion Beam Applications (IBA), 3 Chemin du Cyclotron, Louvain la Neuve B-1348 (Belgium)

2015-04-15

Purpose: In recent years, there has been a movement toward single-detector proton radiography, due to its potential ease of implementation within the clinical environment. One such single-detector technique is the dose ratio method in which the dose maps from two pristine Bragg peaks are recorded beyond the patient. To date, this has only been investigated on the distal side of the lower energy Bragg peak, due to the sharp falloff. The authors investigate the limits and applicability of the dose ratio method on the proximal side of the lower energy Bragg peak, which has the potential to allow a much wider range of water-equivalent thicknesses (WET) to be imaged. Comparisons are made with the use of the distal side of the Bragg peak. Methods: Using the analytical approximation for the Bragg peak, the authors generated theoretical dose ratio curves for a range of energy pairs, and then determined how an uncertainty in the dose ratio would translate to a spread in the WET estimate. By defining this spread as the accuracy one could achieve in the WET estimate, the authors were able to generate lookup graphs of the range on the proximal side of the Bragg peak that one could reliably use. These were dependent on the energy pair, noise level in the dose ratio image and the required accuracy in the WET. Using these lookup graphs, the authors investigated the applicability of the technique for a range of patient treatment sites. The authors validated the theoretical approach with experimental measurements using a complementary metal oxide semiconductor active pixel sensor (CMOS APS), by imaging a small sapphire sphere in a high energy proton beam. Results: Provided the noise level in the dose ratio image was 1% or less, a larger spread of WETs could be imaged using the proximal side of the Bragg peak (max 5.31 cm) compared to the distal side (max 2.42 cm). In simulation, it was found that, for a pediatric brain, it is possible to use the technique to image a region with a

Absolute activity measurements with the windowless 4π-CsI(Tl)-sandwich spectrometer

International Nuclear Information System (INIS)

Denecke, B.

1994-01-01

The windowless 4π-CsI(Tl)-sandwich spectrometer consists of two scintillation crystals sandwiching radioactive sources deposited on thin plastic foils. This configuration has a solid angle very close to 4π sr. The detectors are sensitive to charged particles with energies > 15 keV and measure photons of 15-200 keV with a probability > 98%. Disintegration rates of samples of radionuclides with complex decay modes can be determined directly from the measured count rates with uncertainties below 0.3%. Radionuclide solutions of 57 Co, 109 Cd, 125 I, 152 Eu and 192 Ir were standardised, partly in the framework of international comparisons. A detailed description of the spectrometer and the measurement procedure is given. (orig.)

Absolute activity measurements with the windowless 4π-CsI(Tl)-sandwich spectrometer

Science.gov (United States)

Denecke, B.

1994-01-01

The windowless 4π-CsI(Tl)-sandwich spectrometer consists of two scintillation crystals sandwiching radioactive sources deposited on thin plastic foils. This configuration has a solid angle very close to 4π sr. The detectors are sensitive to charged particles with energies > 15 keV and measure photons of 15-200 keV with a probability > 98%. Disintegration rates of samples of radionuclides with complex decay modes can be determined directly from the measured count rates with uncertainties below 0.3%. Radionuclide solutions of 57Co, 109Cd, 125I, 152Eu and 192Ir were standardised, partly in the framework of international comparisons. A detailed description of the spectrometer and the measurement procedure is given.

Enhancement of the fluorescence intensity of DNA intercalators using nano-imprinted 2-dimensional photonic crystal

International Nuclear Information System (INIS)

Endo, Tatsuro; Ueda, China; Hisamoto, Hideaki; Kajita, Hiroshi; Okuda, Norimichi; Tanaka, Satoru

2013-01-01

We have fabricated polymer-based 2-dimensional photonic crystals that play a key role in enhancing the fluorescence of DNA intercalators. Highly ordered 2-dimensional photonic crystals possessing triangle-shaped and nm-sized hole arrays were fabricated on a 100 μm thick polymer film using nano-imprint lithography. Samples of double-stranded DNAs (sizes: 4361 and 48502 bp; concentration: 1 pM to 10 nM) were adsorbed on the surface of the 2-dimensional photonic crystal by electrostatic interactions and then treated with intercalators. It is found that the fluorescence intensity of the intercalator is enhanced by a factor of up to 10 compared to the enhancement in the absence of the 2-dimensional photonic crystal. Fluorescence intensity increases with increasing length and concentration of the DNAs. If the 2-dimensional photonic crystal is used as a Bragg reflection mirror, the enhancement of fluorescence intensity can be easily observed using a conventional spectrofluorometer. These results suggest that the printed photonic crystal offers a great potential for highly sensitive intercalator-based fluorescent detection of DNAs. (author)

Femtosecond laser pulse written Volume Bragg Gratings

Directory of Open Access Journals (Sweden)

Richter Daniel

2013-11-01

Full Text Available Femtosecond laser pulses can be applied for structuring a wide range of ransparent materials. Here we want to show how to use this ability to realize Volume-Bragg-Gratings in various- mainly non-photosensitive - glasses. We will further present the characteristics of the realized gratings and a few elected applications that have been realized.

Evaluation of Fiber Bragg Grating and Distributed Optical Fiber Temperature Sensors

International Nuclear Information System (INIS)

McCary, Kelly Marie

2017-01-01

Fiber optic temperature sensors were evaluated in the High Temperature Test Lab (HTTL) to determine the accuracy of the measurements at various temperatures. A distributed temperature sensor was evaluated up to 550C and a fiber Bragg grating sensor was evaluated up to 750C. HTTL measurements indicate that there is a drift in fiber Bragg sensor over time of approximately -10C with higher accuracy at temperatures above 300C. The distributed sensor produced some bad data points at and above 500C but produced measurements with less than 2% error at increasing temperatures up to 400C

Evaluation of Fiber Bragg Grating and Distributed Optical Fiber Temperature Sensors

Energy Technology Data Exchange (ETDEWEB)

McCary, Kelly Marie [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2017-04-01

Fiber optic temperature sensors were evaluated in the High Temperature Test Lab (HTTL) to determine the accuracy of the measurements at various temperatures. A distributed temperature sensor was evaluated up to 550C and a fiber Bragg grating sensor was evaluated up to 750C. HTTL measurements indicate that there is a drift in fiber Bragg sensor over time of approximately -10C with higher accuracy at temperatures above 300C. The distributed sensor produced some bad data points at and above 500C but produced measurements with less than 2% error at increasing temperatures up to 400C

Role of Absorbing Nanocrystal Cores in Soft Photonic Crystals: A Spectroscopy and SANS Study.

Science.gov (United States)

Rauh, Astrid; Carl, Nico; Schweins, Ralf; Karg, Matthias

2018-01-23

Periodic superstructures of plasmonic nanoparticles have attracted significant interest because they can support coupled plasmonic modes, making them interesting for plasmonic lasing, metamaterials, and as light-management structures in thin-film optoelectronic devices. We have recently shown that noble metal hydrogel core-shell colloids allow for the fabrication of highly ordered 2-dimensional plasmonic lattices that show surface lattice resonances as the result of plasmonic/diffractive coupling (Volk, K.; Fitzgerald, J. P. S.; Ruckdeschel, P.; Retsch, M.; König, T. A. F.; Karg, M. Reversible Tuning of Visible Wavelength Surface Lattice Resonances in Self-Assembled Hybrid Monolayers. Adv. Optical Mater. 2017, 5, 1600971, DOI: 10.1002/adom.201600971). In the present work, we study the photonic properties and structure of 3-dimensional crystalline superstructures of gold hydrogel core-shell colloids and their pitted counterparts without gold cores. We use far-field extinction spectroscopy to investigate the optical response of these superstructures. Narrow Bragg peaks are measured, independently of the presence or absence of the gold cores. All crystals show a significant reduction in low-wavelength scattering. This leads to a significant enhancement of the plasmonic properties of the samples prepared from gold-nanoparticle-containing core-shell colloids. Plasmonic/diffractive coupling is not evident, which we mostly attribute to the relatively small size of the gold cores limiting the effective coupling strength. Small-angle neutron scattering is applied to study the crystal structure. Bragg peaks of several orders clearly assignable to an fcc arrangement of the particles are observed for all crystalline samples in a broad range of volume fractions. Our results indicate that the nanocrystal cores do not influence the overall crystallization behavior or the crystal structure. These are important prerequisites for future studies on photonic materials built from core

Transmission of germanium poly- and monocrystals for thermal neutrons at different temperatures

International Nuclear Information System (INIS)

Adib, M.; Abdel-Kawy, A.; Eid, Y.; Maayouf, R.M.; Abbas, Y.; Habib, N.; Kilany, M.; Ashry, A.

1987-01-01

Neutron cross-sections of germanium poly- and monocrystals were measured with two time-of-flight and two double-axis crystal spectrometers. The results were analyzed using the single-level Breit-Wigner formula. The coherent scattering amplitude was determined from the Bragg reflections observed in the cross-section of a polycrystal and the analysis of the neutron diffraction pattern. The incoherent and the thermal diffuse scattering cross-section were estimated from the analysis of the total cross-section data obtained for a monocrystal at different temperatures in the energy range 2 meV to 1 eV. (orig./HP) [de

Transmission of germanium poly- and monocrystals for thermal neutrons at different temperatures

Energy Technology Data Exchange (ETDEWEB)

Adib, M.; Abdel-Kawy, A.; Eid, Y.; Maayouf, R.M.; Abbas, Y.; Habib, N.; Kilany, M.; Ashry, A.

Neutron cross-sections of germanium poly- and monocrystals were measured with two time-of-flight and two double-axis crystal spectrometers. The results were analyzed using the single-level Breit-Wigner formula. The coherent scattering amplitude was determined from the Bragg reflections observed in the cross-section of a polycrystal and the analysis of the neutron diffraction pattern. The incoherent and the thermal diffuse scattering cross-section were estimated from the analysis of the total cross-section data obtained for a monocrystal at different temperatures in the energy range 2 meV to 1 eV.

High precision wavelength measurements of X-ray lines emitted from TS-Tokamak plasmas

Energy Technology Data Exchange (ETDEWEB)

Platz, P. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Cornille, M.; Dubau, J. [Observatoire de Paris, 92 - Meudon (France)

1996-01-01

X-ray line spectra from highly charged impurity ions have been taken with a high-resolution Bragg-crystal spectrometer on the Tore Supra (TS) tokamak. By cross-checking the wavelengths of reference lines from the heliumlike ions Ti20 + (2.6 Angstroms) and Ar16 + (3.95 Angstroms) we first demonstrate that it is possible to measure wavelengths with a precision, {lambda}/{delta}{lambda}, of better than 50000. We than determine the wavelengths of n=3 to n=2 transitions of neonlike Ag37+ in the 4 Angstroms spectral range. (authors). 16 refs., 7 figs., 3 tabs.

Protonium X-ray spectroscopy

CERN Document Server

Gotta, D

1999-01-01

The Lyman and Balmer transitions from antiprotonic hydrogen and deuterium were studied extensively at the low-energy-antiproton ring LEAR at CERN in order to determine the strong interaction effects. A first series of experiments $9 was performed with semiconductor and gaseous X-ray detectors. In the last years of LEAR operation using a Bragg crystal spectrometer, strong interaction parameters in the 2p states of antiprotonic hydrogen and deuterium were measured $9 directly. The results of the measurements support the meson-exchange models describing the medium and long range part of the nucleon-antinucleon interaction. (39 refs).

Distributed Bragg grating frequency control in metallic nano lasers

NARCIS (Netherlands)

Marell, M.J.H.; Hill, M.T.

2010-01-01

We show that Bragg gratings can be readily incorporated into metallic nano-lasers which exploit waveguides with semiconductor cores, via modulation of the waveguide width. This provides a simple way to implement laser wavelength control.

Fiber Bragg Grating Sensor for Fault Detection in Radial and Network Transmission Lines

Directory of Open Access Journals (Sweden)

Mehdi Shadaram

2010-10-01

Full Text Available In this paper, a fiber optic based sensor capable of fault detection in both radial and network overhead transmission power line systems is investigated. Bragg wavelength shift is used to measure the fault current and detect fault in power systems. Magnetic fields generated by currents in the overhead transmission lines cause a strain in magnetostrictive material which is then detected by Fiber Bragg Grating (FBG. The Fiber Bragg interrogator senses the reflected FBG signals, and the Bragg wavelength shift is calculated and the signals are processed. A broadband light source in the control room scans the shift in the reflected signal. Any surge in the magnetic field relates to an increased fault current at a certain location. Also, fault location can be precisely defined with an artificial neural network (ANN algorithm. This algorithm can be easily coordinated with other protective devices. It is shown that the faults in the overhead transmission line cause a detectable wavelength shift on the reflected signal of FBG and can be used to detect and classify different kind of faults. The proposed method has been extensively tested by simulation and results confirm that the proposed scheme is able to detect different kinds of fault in both radial and network system.

Localized topological states in Bragg multihelicoidal fibers with twist defects

Science.gov (United States)

Alexeyev, C. N.; Lapin, B. P.; Milione, G.; Yavorsky, M. A.

2016-06-01

We have studied the influence of a twist defect in multihelicoidal Bragg fibers on the emerging of localized defect modes. We have shown that if such a fiber is excited with a Gaussian beam this leads to the appearance of a defect-localized topological state, whose topological charge coincides with the order of rotational symmetry of the fiber's refractive index. We have shown that this effect has a pronounced crossover behavior. We have also formulated a principle of creating the systems that can nestle defect-localized topologically charged modes. According to this principle, such systems have to possess topological activity, that is, the ability to change the topological charge of the incoming field, and operate in the Bragg regime.

Bragg's Law diffraction simulations for electron backscatter diffraction analysis

Energy Technology Data Exchange (ETDEWEB)

Kacher, Josh, E-mail: jkacherbyu@gmail.com [Department of Mechanical Engineering, Brigham Young University, 455B Crabtree Technology Building, Provo, UT 84602 (United States); Landon, Colin; Adams, Brent L.; Fullwood, David [Department of Mechanical Engineering, Brigham Young University, 455B Crabtree Technology Building, Provo, UT 84602 (United States)

2009-08-15

In 2006, Angus Wilkinson introduced a cross-correlation-based electron backscatter diffraction (EBSD) texture analysis system capable of measuring lattice rotations and elastic strains to high resolution. A variation of the cross-correlation method is introduced using Bragg's Law-based simulated EBSD patterns as strain free reference patterns that facilitates the use of the cross-correlation method with polycrystalline materials. The lattice state is found by comparing simulated patterns to collected patterns at a number of regions on the pattern using the cross-correlation function and calculating the deformation from the measured shifts of each region. A new pattern can be simulated at the deformed state, and the process can be iterated a number of times to converge on the absolute lattice state. By analyzing an iteratively rotated single crystal silicon sample and recovering the rotation, this method is shown to have an angular resolution of {approx}0.04{sup o} and an elastic strain resolution of {approx}7e-4. As an example of applications, elastic strain and curvature measurements are used to estimate the dislocation density in a single grain of a compressed polycrystalline Mg-based AZ91 alloy.

Monolithic spectrometer

Energy Technology Data Exchange (ETDEWEB)

Rajic, Slobodan (Knoxville, TN); Egert, Charles M. (Oak Ridge, TN); Kahl, William K. (Knoxville, TN); Snyder, Jr., William B. (Knoxville, TN); Evans, III, Boyd M. (Oak Ridge, TN); Marlar, Troy A. (Knoxville, TN); Cunningham, Joseph P. (Oak Ridge, TN)

1998-01-01

A monolithic spectrometer is disclosed for use in spectroscopy. The spectrometer is a single body of translucent material with positioned surfaces for the transmission, reflection and spectral analysis of light rays.

Femtosecond pulse laser-induced self-organized nanostructures on the surface of ZnO crystal

International Nuclear Information System (INIS)

Zhong Minjian; Guo Guanglei; Yang Junyi; Ma Ninghua; Ye Guo; Ma Hongliang; Guo Xiaodong; Li Ruxin

2008-01-01

This paper reports self-organized nanostructures observed on the surface of ZnO crystal after irradiation by a focused beam of a femtosecond Ti:sapphire laser with a repetition rate of 250 kHz. For a linearly polarized femtosecond laser, the periodic nanograting structure on the ablation crater surface was promoted. The period of self-organization structures is about 180 nm. The grating orientation is adjusted by the laser polarization direction. A long range Bragg-like grating is formed by moving the sample at a speed of 10 μm/s. For a circularly polarized laser beam, uniform spherical nanoparticles were formed as a result of Coulomb explosion during the interaction of near-infrared laser with ZnO crystal

Spin-wave dispersion of nanostructured magnonic crystals with periodic defects

Directory of Open Access Journals (Sweden)

V. L. Zhang

2016-11-01

Full Text Available The spin-wave dispersions in nanostructured magnonic crystals with periodic defects have been mapped by Brillouin light scattering. The otherwise perfect crystals are one-dimensional arrays of alternating 460nm-wide Ni80Fe20 stripes and 40nm-wide air gaps, where one in ten Ni80Fe20 stripes is a defect of width other than 460 nm. Experimentally, the defects are manifested as additional Brillouin peaks, lying within the first and second bandgaps of the perfect crystal, whose frequencies decrease with increasing defect stripe width. Finite-element calculations, based on a supercell comprising one defect and nine perfect Py stripes, show that the defect modes are localized about the defects, with the localization exhibiting an approximate U-shaped dependence on defect size. Calculations also reveal extra magnon branches and the opening of mini-bandgaps, within the allowed bands of the perfect crystal, arising from Bragg reflections at the boundaries of the shorter supercell Brillouin zone. Simulated magnetization profiles of the band-edge modes of the major and mini-bandgaps reveal their different symmetries and localization properties. The findings could find application in microwave magnonic devices like single-frequency passband spin-wave filters.

Preparation and Characterization of Bragg Fibers for Delivery of Laser Radiation at 1064 nm

Directory of Open Access Journals (Sweden)

V. Matejec

2013-04-01

Full Text Available Bragg fibers offer new performance for transmission of high laser energies over long distances. In this paper theoretical modeling, preparation and characterization of Bragg fibers for delivery laser radiation at 1064 nm are presented. Investigated Bragg fibers consist of the fiber core with a refractive index equal to that of silica which is surrounded by three pairs of circular layers. Each pair is composed of one layer with a high and one layer with a low refractive index and characterized by a refractive-index difference around 0.03. Propagation constants and radiation losses of the fundamental mode in such a structure were calculated on the basis of waveguide optics. Preforms of the Bragg fibers were prepared by the MCVD method using germanium dioxide, phosphorous pentoxide and fluorine as silica dopants. The fibers with a diameter of 170 m were drawn from the preforms. Refractive-index profiles, angular distributions of the output power and optical losses of the prepared fibers were measured. Results of testing the fibers for delivery radiation of a pulse Nd:YAG laser at 1064 nm are also shown.

CENTRAL WAVELENGTH ADJUSTMENT OF LIGHT EMITTING SOURCE IN INTERFEROMETRIC SENSORS BASED ON FIBER-OPTIC BRAGG GRATINGS

Directory of Open Access Journals (Sweden)

A. S. Aleynik

2015-09-01

Full Text Available The paper is focused on the investigation of fiber-optic interferometric sensor based on the array of fiber Bragg gratings. Reflection spectra displacement mechanism of the fiber Bragg gratings under the external temperature effects and the static pressure is described. The experiment has shown that reflection spectra displacement of Bragg gratings reduces the visibility of the interference pattern. A method of center wavelength adjustment is proposed for the optical radiation source in accord ance with the current Bragg gratings reflection spectra based on the impulse relative modulation of control signal for the Peltier element controller. The semiconductor vertical-cavity surface-emitting laser controlled by a pump driver is used as a light source. The method is implemented by the Peltier element controller regulating and stabilizing the light source temperature, and a programmable logic-integrated circuit monitoring the Peltier element controller. The experiment has proved that the proposed method rendered possible to regulate the light source temperature at a pitch of 0.05 K and adjust the optical radiation source center wavelength at a pitch of 0.05 nm. Experimental results have revealed that the central wavelength of the radiation adjustment at a pitch of 0.005 nm gives the possibility for the capacity of the array consisting of four opticalfiber sensors based on the fiber Bragg gratings. They are formed in one optical fiber under the Bragg grating temperature change from 0° C to 300° C and by the optical fiber mechanical stretching by the force up to 2 N.

Time-of-flight studies of multiple Bragg reflections in cylindrically bent perfect crystals

Czech Academy of Sciences Publication Activity Database

Mikula, Pavol; Furusaka, M.; Ohkubob, K.; Šaroun, Jan

2012-01-01

Roč. 45, č. 12 (2012), s. 1248-1253 ISSN 0021-8898 R&D Projects: GA AV ČR KJB100480901; GA ČR GAP204/10/0654 Institutional support: RVO:61389005 Keywords : neutron diffraction * time-of-flight method * multiple reflections * bent perfect crystals Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.343, year: 2012

Critical points in the Bragg glass phase of a weakly pinned crystal of ...

Indian Academy of Sciences (India)

the dynamical annealing of the disordered bundles of vortices injected through the sample edges towards the destined ... weakly pinned crystals of the systems like, 2H-NbSe2 and the cubic (C15) CeRu2. [12]. ... systems. This in turn im- ..... We show in figure 6 an updated version of the vortex phase diagram in the given.

Metrology for terahertz time-domain spectrometers

Science.gov (United States)

Molloy, John F.; Naftaly, Mira

2015-12-01

In recent years the terahertz time-domain spectrometer (THz TDS) [1] has emerged as a key measurement device for spectroscopic investigations in the frequency range of 0.1-5 THz. To date, almost every type of material has been studied using THz TDS, including semiconductors, ceramics, polymers, metal films, liquid crystals, glasses, pharmaceuticals, DNA molecules, proteins, gases, composites, foams, oils, and many others. Measurements with a TDS are made in the time domain; conversion from the time domain data to a frequency spectrum is achieved by applying the Fourier Transform, calculated numerically using the Fast Fourier Transform (FFT) algorithm. As in many other types of spectrometer, THz TDS requires that the sample data be referenced to similarly acquired data with no sample present. Unlike frequency-domain spectrometers which detect light intensity and measure absorption spectra, a TDS records both amplitude and phase information, and therefore yields both the absorption coefficient and the refractive index of the sample material. The analysis of the data from THz TDS relies on the assumptions that: a) the frequency scale is accurate; b) the measurement of THz field amplitude is linear; and c) that the presence of the sample does not affect the performance characteristics of the instrument. The frequency scale of a THz TDS is derived from the displacement of the delay line; via FFT, positioning errors may give rise to frequency errors that are difficult to quantify. The measurement of the field amplitude in a THz TDS is required to be linear with a dynamic range of the order of 10 000. And attention must be given to the sample positioning and handling in order to avoid sample-related errors.

Rational solitons in deep nonlinear optical Bragg grating

NARCIS (Netherlands)

Alatas, H.; Iskandar, A.A.; Tjia, M.O.; Valkering, T.P.

2006-01-01

We have examined the rational solitons in the Generalized Coupled Mode model for a deep nonlinear Bragg grating. These solitons are the degenerate forms of the ordinary solitons and appear at the transition lines in the parameter plane. A simple formulation is presented for the investigation of the

Attenuation of Reactor Gamma Radiation and Fast Neutrons Through Large Single-Crystal Materials

International Nuclear Information System (INIS)

Adib, M.

2009-01-01

A generalized formula is given which, for neutron energies in the range 10-4< E< 10 eV and gamma rays with average energy 2 MeV , permits calculation of the transmission properties of several single crystal materials important for neutron scattering instrumentation. A computer program Filter was developed which permits the calculation of attenuation of gamma radiation, nuclear capture, thermal diffuse and Bragg-scattering cross-sections as a function of materials constants, temperature and neutron energy. The applicability of the deduced formula along with the code checked from the obtained agreement between the calculated and experimental neutron transmission through various single-crystals A feasibility study for use of Si, Ge, Pb, Bi and sapphire is detailed in terms of optimum crystal thickness, mosaic spread and cutting plane for efficient transmission of thermal reactor neutrons and for rejection of the accompanying fast neutrons and gamma rays.

Bragg concentrators for hard (> 10keV) x-ray astronomy: Status report

DEFF Research Database (Denmark)

Pareschi, G.; Frontera, F.; Pasqualini, G.

1997-01-01

The use of focusing telescopes in hard X-ray (E > 10 keV) astronomy will provide better flux sensitivity and imaging performances with respect to the direct-viewing detectors, utilized until now. We present recent results obtained from our group regarding the possible use of Bragg-diffraction tec......The use of focusing telescopes in hard X-ray (E > 10 keV) astronomy will provide better flux sensitivity and imaging performances with respect to the direct-viewing detectors, utilized until now. We present recent results obtained from our group regarding the possible use of Bragg...

Bragg Grating Based Sensors in Microstructured Polymer Optical Fibers: Accelerometers and Microphones

DEFF Research Database (Denmark)

Stefani, Alessio

With the growing interest towards fiber Bragg grating sensors and the growing ability in manufacturing polymer optical fibers, the development of polymer fiber Bragg sensors has catched the attention of industries with the goal of developing high performance sensors. This thesis presents...... and in microstructured fibers made of PMMA and TOPAS is reported. The gratings have been written at both 1550 nm, to take advantage of components made for telecommunications, and 850 nm, to exploit the lower loss of polymers and the fast acquisition electronics at this wavelength. A technique for writing multiplexed...

Bandwidth-narrowed Bragg gratings inscribed in double-cladding fiber by femtosecond laser.

Science.gov (United States)

Shi, Jiawei; Li, Yuhua; Liu, Shuhui; Wang, Haiyan; Liu, Ningliang; Lu, Peixiang

2011-01-31

Bragg gratings with the bandwidth(FWHM) narrowed up to 79 pm were inscribed in double-cladding fiber with femtosecond radiation and a phase mask followed by an annealing treatment. With the annealing temperature below a critical value, the bandwidth of Bragg gratings induced by Type I-IR and Type II-IR index change was narrowed without the reduction of reflectivity. The bandwidth narrowing is due to the profile transformation of the refractive index modulation caused by the annealing treatment. This mechanism was verified by comparing bandwidth narrowing processes of FBGs written with different power densities.

Research on low-frequency band gap property of a hybrid phononic crystal

Science.gov (United States)

Dong, Yake; Yao, Hong; Du, Jun; Zhao, Jingbo; Chao, Ding; Wang, Benchi

2018-05-01

A hybrid phononic crystal has been investigated. The characteristic frequency of XY mode, transmission loss and displacement vector have been calculated by the finite element method. There are Bragg scattering band gap and local resonance band gap in the band structures. We studied the influence factors of band gap. There are many flat bands in the eigenfrequencies curve. There are many flat bands in the curve. The band gap covers a large range in low frequency. The band gaps cover more than 95% below 3000 Hz.

Magneto-Optic Field Coupling in Optical Fiber Bragg Gratings

Science.gov (United States)

Carman, Gregory P. (Inventor); Mohanchandra, Panduranga K. (Inventor); Emmons, Michael C. (Inventor); Richards, William Lance (Inventor)

2016-01-01

The invention is a magneto-optic coupled magnetic sensor that comprises a standard optical fiber Bragg grating system. The system includes an optical fiber with at least one Bragg grating therein. The optical fiber has at least an inner core and a cladding that surrounds the inner core. The optical fiber is part of an optical system that includes an interrogation device that provides a light wave through the optical fiber and a system to determine the change in the index of refraction of the optical fiber. The cladding of the optical fiber comprises at least a portion of which is made up of ferromagnetic particles so that the ferromagnetic particles are subject to the light wave provided by the interrogation system. When a magnetic field is present, the ferromagnetic particles change the optical properties of the sensor directly.

Reduction of Bragg-grating-induced coupling to cladding modes

DEFF Research Database (Denmark)

Berendt, Martin Ole; Bjarklev, Anders Overgaard; Soccolich, C.E.

1999-01-01

gratings in a depressed-cladding fiber are compared with simulations. The model gives good agreement with the measured transmission spectrum and accounts for the pronounced coupling to asymmetrical cladding modes, even when the grating is written with the smallest possible blaze. The asymmetry causing...... this is accounted for by the unavoidable attenuation of the UV light. It is found for the considered fiber designs that a high numerical-aperture fiber increases the spectral separation between the Bragg resonance and the onset of cladding-mode losses. A depressed-cladding fiber reduces the coupling strength......We discuss fiber designs that have been suggested for the reduction of Bragg-grating induced coupling to cladding modes. The discussion is based on a theoretical approach that includes the effect of asymmetry in the UV-induced index grating, made by UV-side writing. Experimental results from...

Planar Bragg Grating Sensors—Fabrication and Applications: A Review

Directory of Open Access Journals (Sweden)

I. J. G. Sparrow

2009-01-01

Full Text Available We discuss the background and technology of planar Bragg grating sensors, reviewing their development and describing the latest developments. The physical operating principles are discussed, relating device operation to user requirements. Recent performance of such devices includes a planar Bragg grating sensor design which allows refractive index resolution of 1.9×10−6 RIU and temperature resolution of 0.03∘C. This sensor design is incorporated into industrialised applications allowing the sensor to be used for real time sensing in intrinsically safe, high-pressure pipelines, or for insertion probe applications such as fermentation. Initial data demonstrating the ability to identify solvents and monitor long term industrial processes is presented. A brief review of the technology used to fabricate the sensors is given along with examples of the flexibility afforded by the technique.

Chirped fiber Bragg gratings written with ultrashort pulses and a tunable phase mask.

Science.gov (United States)

Voigtländer, Christian; Thomas, Jens; Wikszak, Elodie; Dannberg, Peter; Nolte, Stefan; Tünnermann, Andreas

2009-06-15

We report a fabrication technique for chirped fiber Bragg gratings (CFBGs) using a flexible setup based on a poly(methyl-methacrylate) phase mask. The period of the phase mask can be thermally tuned during the inscription process, allowing the grating period of uniform fiber Bragg gratings to be shifted about 7 nm by a temperature change of 74 K. In addition, CFBGs with bandwidths up to 2 nm are demonstrated in non-photosensitive fibers by IR femtosecond inscription.

Influence of miscut on crystal truncation rod scattering

International Nuclear Information System (INIS)

Munkholm, A.; Brennan, S.

1999-01-01

X-rays can be used to measure the roughness of a surface by the study of crystal truncation rod scattering. It is shown that for a simple cubic lattice the presence of a miscut surface with a regular step array has no effect on the scattered intensity of a single rod and that a distribution of terrace widths on the surface is shown to have the same effect as adding roughness to the surface. For a perfect crystal without miscut, the scattered intensity is the sum of the intensity from all the rods with the same in-plane momentum transfer. For all real crystals, the scattered intensity is better described as that from a single rod. It is shown that data-collection strategies must correctly account for the sample miscut or there is a potential for improperly measuring the rod intensity. This can result in an asymmetry in the rod intensity above and below the Bragg peak, which can be misinterpreted as being due to a relaxation of the surface. The calculations presented here are compared with data for silicon (001) wafers with 0.1 and 4 miscuts. (orig.)

Far-field coupling in nanobeam photonic crystal cavities

Energy Technology Data Exchange (ETDEWEB)

Rousseau, Ian, E-mail: ian.rousseau@epfl.ch; Sánchez-Arribas, Irene; Carlin, Jean-François; Butté, Raphaël; Grandjean, Nicolas [Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

2016-05-16

We optimized the far-field emission pattern of one-dimensional photonic crystal nanobeams by modulating the nanobeam width, forming a sidewall Bragg cross-grating far-field coupler. By setting the period of the cross-grating to twice the photonic crystal period, we showed using three-dimensional finite-difference time-domain simulations that the intensity extracted to the far-field could be improved by more than three orders of magnitude compared to the unmodified ideal cavity geometry. We then experimentally studied the evolution of the quality factor and far-field intensity as a function of cross-grating coupler amplitude. High quality factor (>4000) blue (λ = 455 nm) nanobeam photonic crystals were fabricated out of GaN thin films on silicon incorporating a single InGaN quantum well gain medium. Micro-photoluminescence spectroscopy of sets of twelve identical nanobeams revealed a nine-fold average increase in integrated far-field emission intensity and no change in average quality factor for the optimized structure compared to the unmodulated reference. These results are useful for research environments and future nanophotonic light-emitting applications where vertical in- and out-coupling of light to nanocavities is required.

From crystals to nanocrystals: Semiconductors and beyond

International Nuclear Information System (INIS)

Petkov, V.; Billinge, S.J.L.

2004-01-01

Knowledge of the atomic-scale structure is an important prerequisite to understand and predict the physical properties of materials. In the case of crystals it is obtained from the positions and the intensities of the Bragg peaks in the diffraction data. However, many materials of technological importance are not perfectly crystalline but contain significant disorder at the atomic scale. The diffraction patterns of such materials show only a few Bragg peaks, if any, and a pronounced diffuse component. This poses a real challenge to the usual techniques for structure characterization. The challenge can be met by employing the so-called atomic pair distribution function (PDF) technique. The atomic PDF gives the number of atoms in a spherical shell of unit thickness at a distance r from a reference atom. It peaks at characteristic distances separating pairs of atoms and thus describes the structure of materials. The atomic PDF technique can be applied with success to study the structure of complex materials with intrinsic positional and/or chemical disorder. Key to the success is that both Bragg and the diffuse component of diffraction data are collected over a wide range of wave vectors before converted into the corresponding PDF. This makes the PDF a structure-sensitive quantity reflecting both the average and local structure of materials. By employing new sources of radiation such as x-ray synchrotrons, diffraction data extended to at least 40 (angstrom) -1 can be collected even for materials composed of light, weakly scattering, atomic species and fine structural features differing in as little as 0.1 (angstrom) revealed. We hope that the examples shown here will motivate further development of the PDF technique as a routine tool in materials structure studies.

Tunable and reconfigurable microwave filter by use of a Bragg-grating-based acousto-optic superlattice modulator.

Science.gov (United States)

Delgado-Pinar, M; Mora, J; Díez, A; Andrés, M V; Ortega, B; Capmany, J

2005-01-01

We present an all-optical novel configuration for implementing multitap transversal filters by use of a broadband source sliced by fiber Bragg grating arrays generated by propagating an acoustic wave along a strong uniform fiber Bragg grating. The tunability and reconfigurability of the microwave filter are demonstrated.

Magnetic field sensor based on double-sided polished fibre-Bragg gratings