Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mangum, John S.; Chan, Lisa H.; Schmidt, Ute

Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In thismore » work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice.« less

Coherent multi-dimensional spectroscopy at optical frequencies in a single beam with optical readout

NASA Astrophysics Data System (ADS)

Seiler, Hélène; Palato, Samuel; Kambhampati, Patanjali

2017-09-01

Ultrafast coherent multi-dimensional spectroscopies form a powerful set of techniques to unravel complex processes, ranging from light-harvesting, chemical exchange in biological systems to many-body interactions in quantum-confined materials. Yet these spectroscopies remain complex to implement at the high frequencies of vibrational and electronic transitions, thereby limiting their widespread use. Here we demonstrate the feasibility of two-dimensional spectroscopy at optical frequencies in a single beam. Femtosecond optical pulses are spectrally broadened to a relevant bandwidth and subsequently shaped into phase coherent pulse trains. By suitably modulating the phases of the pulses within the beam, we show that it is possible to directly read out the relevant optical signals. This work shows that one needs neither complex beam geometries nor complex detection schemes in order to measure two-dimensional spectra at optical frequencies. Our setup provides not only a simplified experimental design over standard two-dimensional spectrometers but its optical readout also enables novel applications in microscopy.

High Resolution Λ Hypernuclear Spectroscopy with Electron Beams

NASA Astrophysics Data System (ADS)

Gogami, T.; Achenbach, P.; Ahmidouch, A.; Albayrak, I.; Androic, D.; Asaturyan, A.; Asaturyan, R.; Ates, O.; Baturin, P.; Badui, R.; Boeglin, W.; Bono, J.; Brash, E.; Carter, P.; Chen, C.; Chiba, A.; Christy, E.; Danagoulian, S.; De Leo, R.; Doi, D.; Elaasar, M.; Ent, R.; Fujii, Y.; Fujita, M.; Furic, M.; Gabrielyan, M.; Gan, L.; Garibaldi, F.; Gaskell, D.; Gasparian, A.; Hashimoto, O.; Horn, T.; Hu, B.; Hungerford, Ed. V.; Jones, M.; Kanda, H.; Kaneta, M.; Kato, S.; Kawai, M.; Kawama, D.; Khanal, H.; Kohl, M.; Liyanage, A.; Luo, W.; Maeda, K.; Margaryan, A.; Markowitz, P.; Maruta, T.; Matsumura, A.; Maxwell, V.; Mkrtchyan, A.; Mkrtchyan, H.; Nagao, S.; Nakamura, S. N.; Narayan, A.; Neville, C.; Niculescu, G.; Niculescu, M. I.; Nunez, A.; Nuruzzaman; Okayasu, Y.; Petkovic, T.; Pochodzalla, J.; Qiu, X.; Reinhold, J.; Rodriguez, V. M.; Samanta, C.; Sawatzky, B.; Seva, T.; Shichijo, A.; Tadevosyan, V.; Tang, L.; Taniya, N.; Tsukada, K.; Veilleux, M.; Vulcan, W.; Wesselmann, F. R.; Wood, S. A.; Yamamoto, T.; Ya, L.; Ye, Z.; Yokota, K.; Yuan, L.; Zhamkochyan, S.; Zhu, L.

JLab E05-115 which is an experiment for Λ hypernuclear spectroscopy with electron beams was carried out at Jefferson Lab (JLab) in 2009. In the experiment, Λ 7He, Λ 9Li, Λ 10Be, Λ 12B and Λ 52V were measured by new magnetic spectrometer systems (SPL+HES+HKS) which were necessary for spectroscopy with high energy resolution of sub-MeV (FWHM). This is the first attempt to measure a Λ hypernucleus with up to medium-heavy mass region by the (e,e' K + ) reaction, overcoming high rate and high multiplicity conditions due to electromagnetic background particles. An overview of the hypernuclear experiments at JLab Hall-C and preliminary binding energy spectrum of Λ 10Be are shown.

Rydberg Spectroscopy of Zeeman-Decelerated Beams of Metastable Helium Molecules

NASA Astrophysics Data System (ADS)

Jansen, Paul; Motsch, Michael; Sprecher, Daniel; Merkt, Frederic

2014-06-01

Having three and four electrons, respectively, He_2^+ and He_2 represent systems for which highly accurate ab-initio calculations might become feasible in the near future. With the goal of performing accurate measurements of the rovibrational energy-level structure of He_2^+ by Rydberg spectroscopy of He_2 and multichannel quantum-defect theory extrapolation techniques, we have produced samples of helium molecules in the a ^3Σu^+ state in supersonic beams with velocities tunable down to 100 m/s by combining a cryogenic supersonic-beam source with a multistage Zeeman decelerator. The molecules are formed at an initial velocity of 500 m/s by striking a discharge in the pulsed expansion of helium gas from a reservoir kept at a cryogenic temperature of 10 K. Using rotationally-resolved PFI-ZEKE (pulsed-field-ionization zero-kinetic-energy) photoelectron spectroscopy, we have probed the rotational-state distribution of the molecules produced in the discharge and found vibrational levels up to ν" = 2 and rotational levels up to N"=21 to be populated. The molecular beam is coupled to a multistage Zeeman decelerator that employs pulsed inhomogeneous magnetic fields to further reduce the beam velocity. By measuring the quantum-state distribution of the decelerated sample using photoelectron and photoionization spectroscopy we observed no rotational or vibrational state-selectivity of the deceleration process, but found that one of the three spin-rotation components of the He_2 a ^3Σu^+ rotational levels is eliminated. W.-C. Tung, M. Pavanello, L. Adamowicz, J. Chem. Phys. 136, 104309 (2012). D. Sprecher, J. Liu, T. Krähenmann, M. Schäfer, and F. Merkt, J. Chem. Phys. 140, 064304 (2014). M. Motsch, P. Jansen, J. A. Agner, H. Schmutz, and F. Merkt, arXiv:1401.7774. N. Vanhaecke, U. Meier, M. Andrist, B. H. Meier, and F. Merkt, Phys. Rev. A 75, 031402(R) (2007).

Precision atomic beam density characterization by diode laser absorption spectroscopy.

PubMed

Oxley, Paul; Wihbey, Joseph

2016-09-01

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 -5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm -3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Modeling and simulation of a beam emission spectroscopy diagnostic for the ITER prototype neutral beam injector.

PubMed

Barbisan, M; Zaniol, B; Pasqualotto, R

2014-11-01

A test facility for the development of the neutral beam injection system for ITER is under construction at Consorzio RFX. It will host two experiments: SPIDER, a 100 keV H(-)/D(-) ion RF source, and MITICA, a prototype of the full performance ITER injector (1 MV, 17 MW beam). A set of diagnostics will monitor the operation and allow to optimize the performance of the two prototypes. In particular, beam emission spectroscopy will measure the uniformity and the divergence of the fast particles beam exiting the ion source and travelling through the beam line components. This type of measurement is based on the collection of the Hα/Dα emission resulting from the interaction of the energetic particles with the background gas. A numerical model has been developed to simulate the spectrum of the collected emissions in order to design this diagnostic and to study its performance. The paper describes the model at the base of the simulations and presents the modeled Hα spectra in the case of MITICA experiment.

Auger electron spectroscopy at high spatial resolution and nA primary beam currents

NASA Technical Reports Server (NTRS)

Todd, G.; Poppa, H.; Moorhead, D.; Bales, M.

1975-01-01

An experimental Auger microprobe system is described which incorporates a field-emission electron gun and total beam currents in the nanoampere range. The distinguishing characteristics of this system include a large multistation UHV specimen chamber, pulse counting and fully digital Auger signal-processing techniques, and digital referencing methods to eliminate the effects of beam instabilities. Some preliminary results obtained with this system are described, and it is concluded that field-emission electron sources can be used for high-resolution Auger electron spectroscopy with primary-beam spots of less than 100 nm and beam currents of the order of 1 nA.

Precision atomic beam density characterization by diode laser absorption spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oxley, Paul; Wihbey, Joseph

2016-09-15

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident lasermore » light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10{sup −5} are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10{sup 4} atoms cm{sup −3}. The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.« less

High Resolution Spectroscopy of 1,2-Difluoroethane in a Molecular Beam: A Case Study of Vibrational Mode-Coupling

DTIC Science & Technology

1992-05-29

Spectroscopy of 1,2- Difluoroethane in a Molecular Beam: A Case Study of Vibrational Mode-Coupling by Steven W. Mork, C. Cameron Miller, and Laura A...and sale; its distribution is unlimited. 92-14657 l9lll l l l , II a HIGH RESOLUTION SPECTROSCOPY OF 1,2- DIFLUOROETHANE IN A MOLECULAR BEAM: A CASE...14853-1301 Abstract The high resolution infrared spectrum of 1,2- difluoroethane (DFE) in a molecular beam has been obtained over the 2978-2996 cm-1

Modeling and simulation of a beam emission spectroscopy diagnostic for the ITER prototype neutral beam injector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbisan, M., E-mail: marco.barbisan@igi.cnr.it; Zaniol, B.; Pasqualotto, R.

2014-11-15

A test facility for the development of the neutral beam injection system for ITER is under construction at Consorzio RFX. It will host two experiments: SPIDER, a 100 keV H{sup −}/D{sup −} ion RF source, and MITICA, a prototype of the full performance ITER injector (1 MV, 17 MW beam). A set of diagnostics will monitor the operation and allow to optimize the performance of the two prototypes. In particular, beam emission spectroscopy will measure the uniformity and the divergence of the fast particles beam exiting the ion source and travelling through the beam line components. This type of measurementmore » is based on the collection of the H{sub α}/D{sub α} emission resulting from the interaction of the energetic particles with the background gas. A numerical model has been developed to simulate the spectrum of the collected emissions in order to design this diagnostic and to study its performance. The paper describes the model at the base of the simulations and presents the modeled H{sub α} spectra in the case of MITICA experiment.« less

Evaluation of beam divergence of a negative hydrogen ion beam using Doppler shift spectroscopy diagnostics

NASA Astrophysics Data System (ADS)

Deka, A. J.; Bharathi, P.; Pandya, K.; Bandyopadhyay, M.; Bhuyan, M.; Yadav, R. K.; Tyagi, H.; Gahlaut, A.; Chakraborty, A.

2018-01-01

The Doppler Shift Spectroscopy (DSS) diagnostic is in the conceptual stage to estimate beam divergence, stripping losses, and beam uniformity of the 100 keV hydrogen Diagnostics Neutral Beam of International Thermonuclear Experimental Reactor. This DSS diagnostic is used to measure the above-mentioned parameters with an error of less than 10%. To aid the design calculations and to establish a methodology for estimation of the beam divergence, DSS measurements were carried out on the existing prototype ion source RF Operated Beam Source in India for Negative ion Research. Emissions of the fast-excited neutrals that are generated from the extracted negative ions were collected in the target tank, and the line broadening of these emissions were used for estimating beam divergence. The observed broadening is a convolution of broadenings due to beam divergence, collection optics, voltage ripple, beam focusing, and instrumental broadening. Hence, for estimating the beam divergence from the observed line broadening, a systematic line profile analysis was performed. To minimize the error in the divergence measurements, a study on error propagation in the beam divergence measurements was carried out and the error was estimated. The measurements of beam divergence were done at a constant RF power of 50 kW and a source pressure of 0.6 Pa by varying the extraction voltage from 4 kV to10 kV and the acceleration voltage from 10 kV to 15 kV. These measurements were then compared with the calorimetric divergence, and the results seemed to agree within 10%. A minimum beam divergence of ˜3° was obtained when the source was operated at an extraction voltage of ˜5 kV and at a ˜10 kV acceleration voltage, i.e., at a total applied voltage of 15 kV. This is in agreement with the values reported in experiments carried out on similar sources elsewhere.

Hypernuclear Spectroscopy with Electron Beam at JLab Hall C

NASA Astrophysics Data System (ADS)

Fujii, Y.; Chiba, A.; Doi, D.; Gogami, T.; Hashimoto, O.; Kanda, H.; Kaneta, M.; Kawama, D.; Maeda, K.; Maruta, T.; Matsumura, A.; Nagao, S.; Nakamura, S. N.; Shichijo, A.; Tamura, H.; Taniya, N.; Yamamoto, T.; Yokota, K.; Kato, S.; Sato, Y.; Takahashi, T.; Noumi, H.; Motoba, T.; Hiyama, E.; Albayrak, I.; Ates, O.; Chen, C.; Christy, M.; Keppel, C.; Kohl, M.; Li, Y.; Liyanage, A.; Tang, L.; Walton, T.; Ye, Z.; Yuan, L.; Zhu, L.; Baturin, P.; Boeglin, W.; Dhamija, S.; Markowitz, P.; Raue, B.; Reinhold, J.; Hungerford, Ed. V.; Ent, R.; Fenker, H.; Gaskell, D.; Horn, T.; Jones, M.; Smith, G.; Vulcan, W.; Wood, S. A.; Johnston, C.; Simicevic, N.; Wells, S.; Samanta, C.; Hu, B.; Shen, J.; Wang, W.; Zhang, X.; Zhang, Y.; Feng, J.; Fu, Y.; Zhou, J.; Zhou, S.; Jiang, Y.; Lu, H.; Yan, X.; Ye, Y.; Gan, L.; Ahmidouch, A.; Danagoulian, S.; Gasparian, A.; Elaasar, M.; Wesselmann, F. R.; Asaturyan, A.; Margaryan, A.; Mkrtchyan, A.; Mkrtchyan, H.; Tadevosyan, V.; Androic, D.; Furic, M.; Petkovic, T.; Seva, T.; Niculescu, G.; Niculescu, I.; López, V. M. Rodríguez; Cisbani, E.; Cusanno, F.; Garibaldi, F.; Uuciuoli, G. M.; de Leo, R.; Maronne, S.

2010-10-01

Hypernuclear spectroscopy with electron beam at JLab Hall C has been studied since 2000. The first experiment, JLab E89-009, demonstrated the possibility of the (e,e'K+) reaction for hypernuclear spectroscopy by achieving an energy resolution of better than 1 MeV (FWHM). The second experiment, JLab E01-011 employed a newly constructed high resolution kaon spectrometer and introduced a vertically tilted electron arm setup to avoid electrons from bremsstrahlung and Moeller scattering. The setup allowed us to have 10 times yield rate and 4 times better signal to accidental ratio with expected energy resolution of 400 keV (FWHM). The third experiment, JLab E05-11B will be performed in 2009 with employing newly constructed high resolution electron spectrometer and a new charge-separation magnet. With the fully customized third generation experimental setup, we can study a variety of targets up to medium-heavy ones such as 52Cr.

Hypernuclear Spectroscopy with Electron Beam at JLab Hall C

NASA Astrophysics Data System (ADS)

Fujii, Y.; Chiba, A.; Doi, D.; Gogami, T.; Hashimoto, O.; Kanda, H.; Kaneta, M.; Kawama, D.; Maeda, K.; Maruta, T.; Matsumura, A.; Nagao, S.; Nakamura, S. N.; Shichijo, A.; Tamura, H.; Taniya, N.; Yamamoto, T.; Yokota, K.; Kato, S.; Sato, Y.; Takahashi, T.; Noumi, H.; Motoba, T.; Hiyama, E.; Albayrak, I.; Ates, O.; Chen, C.; Christy, M.; Keppel, C.; Kohl, M.; Li, Y.; Liyanage, A.; Tang, L.; Walton, T.; Ye, Z.; Yuan, L.; Zhu, L.; Baturin, P.; Boeglin, W.; Dhamija, S.; Markowitz, P.; Raue, B.; Reinhold, J.; Hungerford, Ed. V.; Ent, R.; Fenker, H.; Gaskell, D.; Horn, T.; Jones, M.; Smith, G.; Vulcan, W.; Wood, S. A.; Johnston, C.; Simicevic, N.; Wells, S.; Samanta, C.; Hu, B.; Shen, J.; Wang, W.; Zhang, X.; Zhang, Y.; Feng, J.; Fu, Y.; Zhou, J.; Zhou, S.; Jiang, Y.; Lu, H.; Yan, X.; Ye, Y.; Gan, L.; Ahmidouch, A.; Danagoulian, S.; Gasparian, A.; Elaasar, M.; Wesselmann, F. R.; Asaturyan, A.; Margaryan, A.; Mkrtchyan, A.; Mkrtchyan, H.; Tadevosyan, V.; Androic, D.; Furic, M.; Petkovic, T.; Seva, T.; Niculescu, G.; Niculescu, I.; Rodríguez López, V. M.; Cisbani, E.; Cusanno, F.; Garibaldi, F.; Uuciuoli, G. M.; de Leo, R.; Maronne, S.

Hypernuclear spectroscopy with electron beam at JLab Hall C has been studied since 2000. The first experiment, JLab E89-009, demonstrated the possibility of the (e, e‧ K+) reaction for hypernuclear spectroscopy by achieving an energy resolution of better than 1 MeV (FWHM). The second experiment, JLab E01-011 employed a newly constructed high resolution kaon spectrometer and introduced a vertically tilted electron arm setup to avoid electrons from bremsstrahlung and Moeller scattering. The setup allowed us to have 10 times yield rate and 4 times better signal to accidental ratio with expected energy resolution of 400 keV (FWHM). The third experiment, JLab E05-115 will be performed in 2009 with employing newly constructed high resolution electron spectrometer and a new charge-separation magnet. With the fully customized third generation experimental setup, we can study a variety of targets up to medium-heavy ones such as 52Cr.

Ultra high resolution molecular beam cars spectroscopy with application to planetary atmospheric molecules

NASA Technical Reports Server (NTRS)

Byer, R. L.

1982-01-01

The measurement of high resolution pulsed and continuous wave (CW) coherent anti-Stokes Raman spectroscopy (CARS) measurements in pulsed and steady state supersonic expansions were demonstrated. Pulsed molecular beam sources were characterized, and saturation of a Raman transition and, for the first time, the Raman spectrum of a complex molecular cluster were observed. The observation of CW CARS spectra in a molecular expansion and the effects of transit time broadening is described. Supersonic expansion is established as a viable technique for high resolution Raman spectroscopy of cold molecules with resolutions of 100 MH2.

In-beam measurement of the hydrogen hyperfine splitting and prospects for antihydrogen spectroscopy

NASA Astrophysics Data System (ADS)

Diermaier, M.; Jepsen, C. B.; Kolbinger, B.; Malbrunot, C.; Massiczek, O.; Sauerzopf, C.; Simon, M. C.; Zmeskal, J.; Widmann, E.

2017-06-01

Antihydrogen, the lightest atom consisting purely of antimatter, is an ideal laboratory to study the CPT symmetry by comparison with hydrogen. With respect to absolute precision, transitions within the ground-state hyperfine structure (GS-HFS) are most appealing by virtue of their small energy separation. ASACUSA proposed employing a beam of cold antihydrogen atoms in a Rabi-type experiment, to determine the GS-HFS in a field-free region. Here we present a measurement of the zero-field hydrogen GS-HFS using the spectroscopy apparatus of ASACUSA's antihydrogen experiment. The measured value of νHF=1,420,405,748.4(3.4) (1.6) Hz with a relative precision of 2.7 × 10-9 constitutes the most precise determination of this quantity in a beam and verifies the developed spectroscopy methods for the antihydrogen HFS experiment to the p.p.b. level. Together with the recently presented observation of antihydrogen atoms 2.7 m downstream of the production region, the prerequisites for a measurement with antihydrogen are now available within the ASACUSA collaboration.

In-beam measurement of the hydrogen hyperfine splitting and prospects for antihydrogen spectroscopy.

PubMed

Diermaier, M; Jepsen, C B; Kolbinger, B; Malbrunot, C; Massiczek, O; Sauerzopf, C; Simon, M C; Zmeskal, J; Widmann, E

2017-06-12

Antihydrogen, the lightest atom consisting purely of antimatter, is an ideal laboratory to study the CPT symmetry by comparison with hydrogen. With respect to absolute precision, transitions within the ground-state hyperfine structure (GS-HFS) are most appealing by virtue of their small energy separation. ASACUSA proposed employing a beam of cold antihydrogen atoms in a Rabi-type experiment, to determine the GS-HFS in a field-free region. Here we present a measurement of the zero-field hydrogen GS-HFS using the spectroscopy apparatus of ASACUSA's antihydrogen experiment. The measured value of ν HF =1,420,405,748.4(3.4) (1.6) Hz with a relative precision of 2.7 × 10 -9 constitutes the most precise determination of this quantity in a beam and verifies the developed spectroscopy methods for the antihydrogen HFS experiment to the p.p.b. level. Together with the recently presented observation of antihydrogen atoms 2.7 m downstream of the production region, the prerequisites for a measurement with antihydrogen are now available within the ASACUSA collaboration.

In-beam measurement of the hydrogen hyperfine splitting and prospects for antihydrogen spectroscopy

PubMed Central

Diermaier, M.; Jepsen, C. B.; Kolbinger, B.; Malbrunot, C.; Massiczek, O.; Sauerzopf, C.; Simon, M. C.; Zmeskal, J.; Widmann, E.

2017-01-01

Antihydrogen, the lightest atom consisting purely of antimatter, is an ideal laboratory to study the CPT symmetry by comparison with hydrogen. With respect to absolute precision, transitions within the ground-state hyperfine structure (GS-HFS) are most appealing by virtue of their small energy separation. ASACUSA proposed employing a beam of cold antihydrogen atoms in a Rabi-type experiment, to determine the GS-HFS in a field-free region. Here we present a measurement of the zero-field hydrogen GS-HFS using the spectroscopy apparatus of ASACUSA's antihydrogen experiment. The measured value of νHF=1,420,405,748.4(3.4) (1.6) Hz with a relative precision of 2.7 × 10−9 constitutes the most precise determination of this quantity in a beam and verifies the developed spectroscopy methods for the antihydrogen HFS experiment to the p.p.b. level. Together with the recently presented observation of antihydrogen atoms 2.7 m downstream of the production region, the prerequisites for a measurement with antihydrogen are now available within the ASACUSA collaboration. PMID:28604657

Gamma-Ray Spectroscopy at TRIUMF-ISAC: the New Frontier of Radioactive Ion Beam Research

NASA Astrophysics Data System (ADS)

Ball, G. C.; Andreoiu, C.; Austin, R. A. E.; Bandyopadhyay, D.; Becker, J. A.; Bricault, P.; Brown, N.; Chan, S.; Churchman, R.; Colosimo, S.; Coombes, H.; Cross, D.; Demand, G.; Drake, T. E.; Dombsky, M.; Ettenauer, S.; Finlay, P.; Furse, D.; Garnsworthy, A.; Garrett, P. E.; Green, K. L.; Grinyer, G. F.; Hyland, B.; Hackman, G.; Kanungo, R.; Kulp, W. D.; Lassen, J.; Leach, K. G.; Leslie, J. R.; Mattoon, C.; Melconian, D.; Morton, A. C.; Pearson, C. J.; Phillips, A. A.; Rand, E.; Sarazin, F.; Svensson, C. E.; Sumithrarachchi, S.; Schumaker, M. A.; Triambak, S.; Waddington, J. C.; Walker, P. M.; Williams, S. J.; Wood, J. L.; Wong, J.; Zganjar, E. F.

2009-03-01

High-resolution gamma-ray spectroscopy is essential to fully exploit the unique scientific opportunities at the next generation radioactive ion beam facilities such as the TRIUMF Isotope Separator and Accelerator (ISAC). At ISAC the 8π spectrometer and its associated auxiliary detectors is optimize for β-decay studies while TIGRESS an array of segmented clover HPGe detectors has been designed for studies with accelerated beams. This paper gives a brief overview of these facilities and also presents recent examples of the diverse experimental program carried out at the 8π spectrometer.

Design of a beam emission spectroscopy diagnostic for negative ions radio frequency source SPIDER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaniol, B.; Pasqualotto, R.; Barbisan, M.

2012-04-15

A facility will be built in Padova (Italy) to develop, commission, and optimize the neutral beam injection system for ITER. The full scale prototype negative ion radio frequency source SPIDER, featuring up to 100 kV acceleration voltage, includes a full set of diagnostics, required for safe operation and to measure and optimize the beam performance. Among them, beam emission spectroscopy (BES) will be used to measure the line integrated beam uniformity, divergence, and neutralization losses inside the accelerator (stripping losses). In the absence of the neutralization stage, SPIDER beam is mainly composed by H{sup -} or D{sup -} particles, accordingmore » to the source filling gas. The capability of a spectroscopic diagnostic of an H{sup -} (D{sup -}) beam relies on the interaction of the beam particles with the background gas particles. The BES diagnostic will be able to acquire the H{sub {alpha}} (D{sub {alpha}}) spectrum from up to 40 lines of sight. The system is capable to resolve stripping losses down to 2 keV and to measure beam divergence with an accuracy of about 10%. The design of this diagnostic is reported, with discussion of the layout and its components, together with simulations of the expected performance.« less

Electrochemical impedance spectroscopy on nanostructured carbon electrodes grown by supersonic cluster beam deposition

NASA Astrophysics Data System (ADS)

Bettini, Luca Giacomo; Bardizza, Giorgio; Podestà, Alessandro; Milani, Paolo; Piseri, Paolo

2013-02-01

Nanostructured porous films of carbon with density of about 0.5 g/cm3 and 200 nm thickness were deposited at room temperature by supersonic cluster beam deposition (SCBD) from carbon clusters formed in the gas phase. Carbon film surface topography, determined by atomic force microscopy, reveals a surface roughness of 16 nm and a granular morphology arising from the low kinetic energy ballistic deposition regime. The material is characterized by a highly disordered carbon structure with predominant sp2 hybridization as evidenced by Raman spectroscopy. The interface properties of nanostructured carbon electrodes were investigated by cyclic voltammetry and electrochemical impedance spectroscopy employing KOH 1 M solution as aqueous electrolyte. An increase of the double layer capacitance is observed when the electrodes are heat treated in air or when a nanostructured nickel layer deposited by SCBD on top of a sputter deposited film of the same metal is employed as a current collector instead of a plain metallic film. This enhancement is consistent with an improved charge injection in the active material and is ascribed to the modification of the electrical contact at the interface between the carbon and the metal current collector. Specific capacitance values up to 120 F/g have been measured for the electrodes with nanostructured metal/carbon interface.

Fine Structure in Helium-like Fluorine by Fast-Beam Laser Spectroscopy

NASA Astrophysics Data System (ADS)

Myers, E. G.; Thompson, J. K.; Silver, J. D.

1998-05-01

With the aim of providing an additional precise test of higher-order corrections to high precision calculations of fine structure in helium and helium-like ions(T. Zhang, Z.-C. Yan and G.W.F. Drake, Phys. Rev. Lett. 77), 1715 (1996)., a measurement of the 2^3P_2,F - 2^3P_1,F' fine structure in ^19F^7+ is in progress. The method involves doppler-tuned laser spectroscopy using a CO2 laser on a foil-stripped fluorine ion beam. We aim to achieve a higher precision, compared to an earlier measurement(E.G. Myers, P. Kuske, H.J. Andrae, I.A. Armour, H.A. Klein, J.D. Silver, and E. Traebert, Phys. Rev. Lett. 47), 87 (1981)., by using laser beams parallel and anti-parallel to the ion beam, to obtain partial cancellation of the doppler shift(J.K. Thompson, D.J.H. Howie and E.G. Myers, Phys. Rev. A 57), 180 (1998).. A calculation of the hyperfine structure, allowing for relativistic, QED and nuclear size effects, will be required to obtain the ``hyperfine-free'' fine structure interval from the measurements.

Charge Exchange Recombination Spectroscopy Based on Diagnostic Neutral Beam in HT-7 Tokamak

NASA Astrophysics Data System (ADS)

Shi, Yuejiang; Fu, Jia; Li, Yingying; William, Rowan; Huang, He; Wang, Fudi; Gao, Huixian; Huang, Juann; Zhou, Qian; Liu, Sheng; Zhang, Jian; Li, Jun; Xie, Yuanlai; Liu, Zhimin; Huang, Yiyun; Hu, Chundong; Wan, Baonian

2010-02-01

Charge exchange recombination spectroscopy (CXRS) based on a diagnostic neutral beam (DNB) installed in the HT-7 tokamak is introduced. DNB can provide a 6 A extracted current at 50 kV for 0.1 s in hydrogen. It can penetrate into the core plasma in HT-7. The CXRS system is designed to observe charge exchange (CX) transitions in the visible spectrum. CX light from the beam is focused onto 10 optical fibers, which view the plasma from -5 cm to 20 cm. The CXRS system can measure the ion temperature as low as 0.1 keV. With CXRS, the local ion temperature profile in HT-7 was obtained for the first time.

Characterization of ion beam modified ceramic wear surfaces using Auger electron spectroscopy

NASA Technical Reports Server (NTRS)

Wei, W.; Lankford, J.

1987-01-01

An investigation of the surface chemistry and morphology of the wear surfaces of ceramic material surfaces modified by ion beam mixing has been conducted using Auger electron spectroscopy and secondary electron microscopy. Studies have been conducted on ceramic/ceramic friction and wear couples made up of TiC and NiMo-bonded TiC cermet pins run against Si3N4 and partially stabilized zirconia disc surfaces modified by the ion beam mixing of titanium and nickel, as well as ummodified ceramic/ceramic couples in order to determine the types of surface changes leading to the improved friction and wear behavior of the surface modified ceramics in simulated diesel environments. The results of the surface analyses indicate that the formation of a lubricating oxide layer of titanium and nickel, is responsible for the improvement in ceramic friction and wear behavior. The beneficial effect of this oxide layer depends on several factors, including the adherence of the surface modified layer or subsequently formed oxide layer to the disc substrate, the substrate materials, the conditions of ion beam mixing, and the environmental conditions.

Rapid analysis of the chemical composition of agricultural fibers using near infrared spectroscopy and pyrolysis molecular beam mass spectrometry

Treesearch

Stephen S. Kelley; Roger M. Rowell; Mark Davis; Cheryl K. Jurich; Rebecca Ibach

2004-01-01

The chemical composition of a variety of agricultural biomass samples was analyzed with near infrared spectroscopy and pyrolysis molecular beam mass spectroscopy. These samples were selected from a wide array of agricultural residue samples and included residues that had been subjected to a variety of di2erent treatments including solvent extractions and chemical...

Bigelow Expandable Activity Module (BEAM) Monitoring System

NASA Technical Reports Server (NTRS)

Wells, Nathan

2017-01-01

What is Bigelow Expandable Activity Module (BEAM)? The Bigelow Expandable Activity Module (BEAM) is an expandable habitat technology demonstration on ISS; increase human-rated inflatable structure Technology Readiness Level (TRL) to level 9. NASA managed ISS payload project in partnership with Bigelow Aerospace. Launched to ISS on Space X 8 (April 8th, 2016). Fully expanded on May 28th, 2016. Jeff Williams/Exp. 48 Commander first entered BEAM on June 5th, 2016.

In-Beam Gamma-ray Spectroscopy in the sdpf 37Ar Nucleus

NASA Astrophysics Data System (ADS)

Silveira, M. A. G.; Medina, N. H.; Seale, W. A.; Ribas, R. V.; de Oliveira, J. R. B.; Zilio, S.; Lenzi, S. M.; Napoli, D. R.; Marginean, N.; Vedova, F. Della; Farnea, E.; Ionescu-Bujor, M.; Iordachescu, A.

2007-10-01

The nucleus 37Ar has been studied with γ-ray spectroscopy in the 24Mg(16O,2pn) reaction at a beam energy of 70 MeV. Twenty two new excited states up to an excitation energy of 13 MeV have been observed. We compare the first negative and positive parity yrast states with large-scale-shell-model calculations using the Antoine code and the SDPF interaction, considering the excitation of the 1d5/2,2s1/2 and 1d3/2 nucleons to 1f7/2 and 2p3/2 in the sdpf valence space.

New Beam Scanning Device for Active Beam Delivery System (BDS) in Proton Therapy

NASA Astrophysics Data System (ADS)

Variale, V.; Mastromarco, M.; Colamaria, F.; Colella, D.

A new Beam Delivery System (BDS) has been studied in the framework of a new proton therapy project, called AMIDERHA. It is characterized by an active scanning system for target irradiation with a pencil beam. The project is based on the use of a Linac with variable final energy and the Robotized Patient Positioning System instead of the traditional gantry. As a consequence, in the active BDS of AMIDERHA a pencil beam scanning system with a relatively long Source to Axis Distance (SAD) can be used. In this contribution, the idea of using a unique new device capable of both horizontal and vertical beam scansion for the AMIDERHA active BDS will be presented and discussed. Furthermore, a preliminary design of that device will be shown, together with the results of simulations.

A design procedure for active control of beam vibrations

NASA Technical Reports Server (NTRS)

Dickerson, S. L.; Jarocki, G.

1983-01-01

The transverse vibrations of beams is discussed and a methodology for the design of an active damping device is given. The Bernoulli-Euler equation is used to derive a transcendental transfer function, which relates a torque applied at one end of the beam to the rotational position and velocity at that point. The active damping device consists of a wire, a linear actuator and a short torque arm attached to one end of the beam. The action of the actuator varies a tension in the wire and creates a torque which opposes the rotation of the beam and thus damps vibration. A design procedure for such an active damper is given. This procedure shows the relationships and trade-offs between the actuator stroke, power required, stress levels in the wire and beam and the geometry of the beam and wire. It is shown that by consideration of the frequency response at the beam natural frequencies, the aforementioned relationships can be greatly simplified. Similarly, a simple way of estimating the effective damping ratios and eigenvalue locations of actively controlled beams is presented.

High-power continuous-wave tunable 544- and 272-nm beams based on a diode-oscillator fiber-amplifier for calcium spectroscopy

NASA Astrophysics Data System (ADS)

Ko, Kwang-Hoon; Kim, Yonghee; Park, Hyunmin; Cha, Yong-Ho; Kim, Taek-Soo; Lee, Lim; Lim, Gwon; Han, Jaemin; Ko, Kwang-Hee; Jeong, Do-Young

2015-08-01

Continuous-wave single-frequency tunable 544- and 272-nm beams have been demonstrated by the second- and fourth-harmonic conversions of a 1088-nm fundamental beam from a diode-oscillator fiber-amplifier. The single-pass second-harmonic generation with a MgO-doped periodically poled stoichiometric LiTaO3 crystal and the external-cavity frequency-doubling technique with a bulk BBO crystal were employed to achieve an approximately 6-W 544-nm beam and a 1.5-W 272-nm beam, respectively. We characterized the second- and fourth-harmonic generations and discussed their applications to calcium spectroscopy.

Acoustic manipulation: Bessel beams and active carriers

NASA Astrophysics Data System (ADS)

Rajabi, Majid; Mojahed, Alireza

2017-10-01

In this paper, we address the interaction of zero-order acoustic Bessel beams as an acoustic manipulation tool, with an active spherical shell, as a carrier in drug, agent, or material delivery systems, in order to investigate the controllability of exerted acoustic radiation force as the driver. The active body is comprised of a spherical elastic shell stimulated in its monopole mode of vibrations with the same frequency as the incident wave field via an internally bonded and spatially uniformly excited piezoelectric actuator. The main aim of this work is to examine the performance of a nondiffracting and self-reconstructing zero-order Bessel beam to obtain the full manipulability condition of active carriers in comparison with the case of a plane wave field. The results unveil some unique potentials of the Bessel beams in the company of active carriers, with emphasis on the consumed power of the actuation system. This paper will widen the path toward the single-beam robust acoustic manipulation techniques and may lead to the prospect of combined tweezers and fields, with applications in delivery systems, microswimmers, and trapper designs.

A field programmable gate array-based time-resolved scaler for collinear laser spectroscopy with bunched radioactive potassium beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rossi, D. M., E-mail: rossi@nscl.msu.edu; Davis, M.; Ringle, R.

A new data acquisition system including a Field Programmable Gate Array (FPGA) based time-resolved scaler was developed for laser-induced fluorescence and beam bunch coincidence measurements. The FPGA scaler was tested in a collinear laser-spectroscopy experiment on radioactive {sup 37}K at the BEam COoler and LAser spectroscopy (BECOLA) facility at the National Superconducting Cyclotron Laboratory at Michigan State University. A 1.29 μs bunch width from the buncher and a bunch repetition rate of 2.5 Hz led to a background suppression factor of 3.1 × 10{sup 5} in resonant photon detection measurements. The hyperfine structure of {sup 37}K and its isotope shiftmore » relative to the stable {sup 39}K were determined using 5 × 10{sup 4} s{sup −1} {sup 37}K ions injected into the BECOLA beam line. The obtained hyperfine coupling constants A({sup 2}S{sub 1/2}) = 120.3(1.4) MHz, A({sup 2}P{sub 1/2}) = 15.2(1.1) MHz, and A({sup 2}P{sub 3/2}) = 1.4(8) MHz, and the isotope shift δν{sup 39,} {sup 37} = −264(3) MHz are consistent with the previously determined values, where available.« less

Compact, accurate description of diagnostic neutral beam propagation and attenuation in a high temperature plasma for charge exchange recombination spectroscopy analysis.

PubMed

Bespamyatnov, Igor O; Rowan, William L; Granetz, Robert S

2008-10-01

Charge exchange recombination spectroscopy on Alcator C-Mod relies on the use of the diagnostic neutral beam injector as a source of neutral particles which penetrate deep into the plasma. It employs the emission resulting from the interaction of the beam atoms with fully ionized impurity ions. To interpret the emission from a given point in the plasma as the density of emitting impurity ions, the density of beam atoms must be known. Here, an analysis of beam propagation is described which yields the beam density profile throughout the beam trajectory from the neutral beam injector to the core of the plasma. The analysis includes the effects of beam formation, attenuation in the neutral gas surrounding the plasma, and attenuation in the plasma. In the course of this work, a numerical simulation and an analytical approximation for beam divergence are developed. The description is made sufficiently compact to yield accurate results in a time consistent with between-shot analysis.

Ultrasensitive dual-beam absorption and gain spectroscopy: applications for near-infrared and visible diode laser sensors

NASA Astrophysics Data System (ADS)

Allen, Mark G.; Carleton, Karen L.; Davis, Steven J.; Kessler, William J.; Otis, Charles E.; Palombo, Daniel A.; Sonnenfroh, David M.

1995-06-01

A dual-beam detection strategy with automatic balancing is described for ultrasensitive spectroscopy. Absorbances of 2 \\times 10-7 Hz-1/2 in free-space configurations and 5 \\times 10-6 Hz -1/2 in fiber-coupled configurations are demonstrated. With the dual-beam technique, atmospherically broadened absorption transitions may be resolved with InGaAsP, AlGaAs, and AlGaInP single-longitudinal-mode diode lasers. Applications to trace measurements of NO2 , O2, and H2O are described by the use of simple, inexpensive laser and detector systems. Small signal gain measurements on optically pumped I2 with a sensitivity of 10-5 are also reported.

Spatially-resolved temperature diagnostic for supersonic flow using cross-beam Doppler-limited laser saturation spectroscopy

NASA Astrophysics Data System (ADS)

Phillips, Grady T.

Optical techniques for measuring the temperature in three-dimensional supersonic reactive flows have typically depended on lineshape measurements using single-beam laser absorption spectroscopy. However, absorption over extended path lengths in flows with symmetric, turbulent eddies can lead to systematically high extracted temperatures due to Doppler shifts resulting from flow along the absorption path. To eliminate these problems and provide full three-dimensional spatial resolution, two variants of laser saturation spectroscopy have been developed and demonstrated, for the first time, which utilize two crossed and nearly copropogating laser beams. Individual rotational lines in the visible I2 X 1Sigma 0+g → B 3pi 0+u transition were used to develop the two diagnostic to support research on the Chemical Oxygen-Iodine Laser (COIL), the weapon aboard the USAF Airborne Laser. Cross-Beam Saturation Absorption Spectroscopy (CBSAS) and Cross-Beam Inter-Modulated Fluorescence (CBIMF) were demonstrated as viable methods for recording the spectral signal of an I2 ro-vibrational line in a small three-dimensional volume using a tunable CW dye laser. Temperature is extracted by fitting the recorded signal with a theoretical signal constructed from the Doppler-broadened hyperfine components of the ro-vibrational line. The CBIMF technique proved successful for extracting the temperature of an I2-seeded, Ar gas flow within a small, Mach 2, Laval nozzle where the overlap volume of the two 1 mm diameter laser beams was 2.4 mm 3. At a test point downstream of the nozzle throat, the average temperature of 146 K +/- 1.5 K extracted from measurements of the I2 P(46) 17-1 spectral line compared favorably with the 138 K temperature calculated from isentropic, one-dimensional flow theory. CBIMF provides sufficient accuracy for characterizing the temperature of the gas flow in a COIL device, and could be applied to other areas of flow-field characterization and nozzle design. In

Laser Induced Breakdown Spectroscopy Based on Single Beam Splitting and Geometric Configuration for Effective Signal Enhancement

PubMed Central

Yang, Guang; Lin, Qingyu; Ding, Yu; Tian, Di; Duan, Yixiang

2015-01-01

A new laser induced breakdown spectroscopy (LIBS) based on single-beam-splitting (SBS) and proper optical geometric configuration has been initially explored in this work for effective signal enhancement. In order to improve the interaction efficiency of laser energy with the ablated material, a laser beam operated in pulse mode was divided into two streams to ablate/excite the target sample in different directions instead of the conventional one beam excitation in single pulse LIBS (SP-LIBS). In spatial configuration, the laser beam geometry plays an important role in the emission signal enhancement. Thus, an adjustable geometric configuration with variable incident angle between the two splitted laser beams was constructed for achieving maximum signal enhancement. With the optimized angles of 60° and 70° for Al and Cu atomic emission lines at 396.15 nm and 324.75 nm respectively, about 5.6- and 4.8-folds signal enhancements were achieved for aluminum alloy and copper alloy samples compared to SP-LIBS. Furthermore, the temporal analysis, in which the intensity of atomic lines in SP-LIBS decayed at least ten times faster than the SBS-LIBS, proved that the energy coupling efficiency of SBS-LIBS was significantly higher than that of SP-LIBS. PMID:25557721

Effect of analytical proton beam irradiation on lead-white pigments, characterized by EPR spectroscopy

NASA Astrophysics Data System (ADS)

Gourier, Didier; Binet, Laurent; Gonzalez, Victor; Vezin, Hervé; Touati, Nadia; Calligaro, Thomas

2018-01-01

Analytical techniques using proton beams with energy in the MeV range are commonly used to study archeological artefact and artistic objects. However ion beams can induce alteration of fragile materials, which is notably the case of easel paintings, limiting the use of these techniques. We used continuous wave EPR and pulse EPR spectroscopy to reveal the effect of 3 MeV proton irradiation on lead carbonates, which were extensively employed as white pigments from the antiquity to the 20th century. Two kinds of paramagnetic centers were identified in cerussite (PbCO3): the first one is CO3- radicals formed by hole trapping by CO32- ions, and the second one is NO32- radical resulting from electron trapping by NO3- impurities. Hydrocerussite (2PbCO3·Pb(OH)2) is the most darkened material under proton beam, however it exhibits no NO32- radicals and 20 times less CO3- radicals than cerussite. Consequently these paramagnetic centers are not directly responsible for the darkening of lead-white pigments. We proposed that their higher instability in hydrocerussite might be at the origin of the formation of color centers in this material.

Active Beam Shaping System and Method Using Sequential Deformable Mirrors

NASA Technical Reports Server (NTRS)

Pueyo, Laurent A. (Inventor); Norman, Colin A. (Inventor)

2015-01-01

An active optical beam shaping system includes a first deformable mirror arranged to at least partially intercept an entrance beam of light and to provide a first reflected beam of light, a second deformable mirror arranged to at least partially intercept the first reflected beam of light from the first deformable mirror and to provide a second reflected beam of light, and a signal processing and control system configured to communicate with the first and second deformable mirrors. The first deformable mirror, the second deformable mirror and the signal processing and control system together provide a large amplitude light modulation range to provide an actively shaped optical beam.

SPIDER beam dump as diagnostic of the particle beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaupa, M., E-mail: matteo.zaupa@igi.cnr.it; Sartori, E.; Consorzio RFX, Corso Stati Uniti 4, Padova 35127

The beam power produced by the negative ion source for the production of ion of deuterium extracted from RF plasma is mainly absorbed by the beam dump component which has been designed also for measuring the temperatures on the dumping panels for beam diagnostics. A finite element code has been developed to characterize, by thermo-hydraulic analysis, the sensitivity of the beam dump to the different beam parameters. The results prove the capability of diagnosing the beam divergence and the horizontal misalignment, while the entity of the halo fraction appears hardly detectable without considering the other foreseen diagnostics like tomography andmore » beam emission spectroscopy.« less

SPIDER beam dump as diagnostic of the particle beam

NASA Astrophysics Data System (ADS)

Zaupa, M.; Dalla Palma, M.; Sartori, E.; Brombin, M.; Pasqualotto, R.

2016-11-01

The beam power produced by the negative ion source for the production of ion of deuterium extracted from RF plasma is mainly absorbed by the beam dump component which has been designed also for measuring the temperatures on the dumping panels for beam diagnostics. A finite element code has been developed to characterize, by thermo-hydraulic analysis, the sensitivity of the beam dump to the different beam parameters. The results prove the capability of diagnosing the beam divergence and the horizontal misalignment, while the entity of the halo fraction appears hardly detectable without considering the other foreseen diagnostics like tomography and beam emission spectroscopy.

Electron Beam-Induced Writing of Nanoscale Iron Wires on a Functional Metal Oxide

PubMed Central

2013-01-01

Electron beam-induced surface activation (EBISA) has been used to grow wires of iron on rutile TiO2(110)-(1 × 1) in ultrahigh vacuum. The wires have a width down to ∼20 nm and hence have potential utility as interconnects on this dielectric substrate. Wire formation was achieved using an electron beam from a scanning electron microscope to activate the surface, which was subsequently exposed to Fe(CO)5. On the basis of scanning tunneling microscopy and Auger electron spectroscopy measurements, the activation mechanism involves electron beam-induced surface reduction and restructuring. PMID:24159366

Ultrafast third-harmonic spectroscopy of single nanoantennas fabricated using helium-ion beam lithography

NASA Astrophysics Data System (ADS)

Kollmann, H.; Esmann, M.; Becker, S. F.; Piao, X.; Huynh, C.; Kautschor, L.-O.; Bösker, G.; Vieker, H.; Beyer, A.; Gölzhäuser, A.; Park, N.; Silies, M.; Lienau, C.

2016-03-01

Metallic nanoantennas are able to spatially localize far-field electromagnetic waves on a few nanometer length scale in the form of surface plasmon excitations 1-3. Standard tools for fabricating bowtie and rod antennas with sub-20 nm feature sizes are Electron Beam Lithography or Ga-based Focused Ion Beam (FIB) Milling. These structures, however, often suffer from surface roughness and hence show only a limited optical polarization contrast and therefore a limited electric field localization. Here, we combine Ga- and He-ion based milling (HIM) for the fabrication of gold bowtie and rod antennas with gap sizes of less than 6 nm combined with a high aspect ratio. Using polarization-sensitive Third-Harmonic (TH) spectroscopy, we compare the nonlinear optical properties of single HIM-antennas with sub-6-nm gaps with those produced by standard Ga-based FIB. We find a pronounced enhancement of the total TH intensity of more than three in comparison to Ga-FIB antennas and a highly improved polarization contrast of the TH intensity of 250:1 for Heion produced antennas 4. These findings combined with Finite-Element Method calculations demonstrate a field enhancement of up to one hundred in the few-nanometer gap of the antenna. This makes He-ion beam milling a highly attractive and promising new tool for the fabrication of plasmonic nanoantennas with few-nanometer feature sizes.

Exploitation of high resolution beam spectroscopy diagnostics on MAST

NASA Astrophysics Data System (ADS)

Michael, Clive; Debock, Maarten; Conway, Neil; Akers, Rob; Appel, Lynton; Field, Anthony; Walsh, Mike; Wisse, Marco

2009-11-01

Recent developments in beam spectroscopy on MAST, including CXRS, MSE and a pilot FIDA system have revealed new information about phenomena such as ITBs, MHD instabilities, transport and fast particle physics. For example, ITBs in the ion temperature and toroidal rotation have been observed with the 64ch CXRS system, while reverse-shear q profiles have been observed with the recently commissioned 35ch MSE system. Thus, the synergy of these diagnostics helps us to understand, among other things, the role of magnetic and rotational shear on ITBs. MSE measurements have also helped to understand MHD phenomena such as locked modes (characterized by changes in toroidal momentum, revealed by CXRS), sawteeth, and internal reconnection events. Finally, the temporal/spatial resolution and SNR of the MSE system have been exploited. Interesting results include the detection of low frequency (˜2kHz) magnetic field fluctuations, characterization of the radial structure of higher frequency (<100kHz) broadband and coherent density (BES) fluctuations, and the identification of short scale length features (˜1.8cm) in the current profile near the edge pedestal.

The performance of the γ-ray tracking array GRETINA for γ-ray spectroscopy with fast beams of rare isotopes

DOE PAGES

Weisshaar, D.; Bazin, D.; Bender, P. C.; ...

2016-12-03

The gamma-ray tracking array GRETINA was coupled to the S800 magnetic spectrometer for spectroscopy with fast beams of rare isotopes at the National Superconducting Cyclotron Laboratory on the campus of Michigan State University. We describe the technical details of this powerful setup and report on GRETINA's performance achieved with source and in-beam measurements. The gamma-ray multiplicity encountered in experiments with fast beams is usually low, allowing for a simplified and efficient treatment of the data in the gamma-ray analysis in terms of Doppler reconstruction and spectral quality. Finally, the results reported in this work were obtained from GRETINA consisting ofmore » 8 detector modules hosting four high-purity germanium crystals each. Currently, GRETINA consists of 10 detector modules.« less

Sample exchange by beam scanning with applications to noncollinear pump-probe spectroscopy at kilohertz repetition rates.

PubMed

Spencer, Austin P; Hill, Robert J; Peters, William K; Baranov, Dmitry; Cho, Byungmoon; Huerta-Viga, Adriana; Carollo, Alexa R; Curtis, Anna C; Jonas, David M

2017-06-01

In laser spectroscopy, high photon flux can perturb the sample away from thermal equilibrium, altering its spectroscopic properties. Here, we describe an optical beam scanning apparatus that minimizes repetitive sample excitation while providing shot-to-shot sample exchange for samples such as cryostats, films, and air-tight cuvettes. In this apparatus, the beam crossing point is moved within the focal plane inside the sample by scanning both tilt angles of a flat mirror. A space-filling spiral scan pattern was designed that efficiently utilizes the sample area and mirror scanning bandwidth. Scanning beams along a spiral path is shown to increase the average number of laser shots that can be sampled before a spot on the sample cell is resampled by the laser to ∼1700 (out of the maximum possible 2500 for the sample area and laser spot size) while ensuring minimal shot-to-shot spatial overlap. Both an all-refractive version and an all-reflective version of the apparatus are demonstrated. The beam scanning apparatus does not measurably alter the time delay (less than the 0.4 fs measurement uncertainty), the laser focal spot size (less than the 2 μm measurement uncertainty), or the beam overlap (less than the 3.3% measurement uncertainty), leading to pump-probe and autocorrelation signal transients that accurately characterize the equilibrium sample.

Bayesian modelling of the emission spectrum of the Joint European Torus Lithium Beam Emission Spectroscopy system.

PubMed

Kwak, Sehyun; Svensson, J; Brix, M; Ghim, Y-C

2016-02-01

A Bayesian model of the emission spectrum of the JET lithium beam has been developed to infer the intensity of the Li I (2p-2s) line radiation and associated uncertainties. The detected spectrum for each channel of the lithium beam emission spectroscopy system is here modelled by a single Li line modified by an instrumental function, Bremsstrahlung background, instrumental offset, and interference filter curve. Both the instrumental function and the interference filter curve are modelled with non-parametric Gaussian processes. All free parameters of the model, the intensities of the Li line, Bremsstrahlung background, and instrumental offset, are inferred using Bayesian probability theory with a Gaussian likelihood for photon statistics and electronic background noise. The prior distributions of the free parameters are chosen as Gaussians. Given these assumptions, the intensity of the Li line and corresponding uncertainties are analytically available using a Bayesian linear inversion technique. The proposed approach makes it possible to extract the intensity of Li line without doing a separate background subtraction through modulation of the Li beam.

Heterodyne laser spectroscopy system

DOEpatents

Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

1990-01-01

A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency, and provides spectral analysis of a laser beam.

Modeling and design of a beam emission spectroscopy diagnostic for the negative ion source NIO1

NASA Astrophysics Data System (ADS)

Barbisan, M.; Zaniol, B.; Cavenago, M.; Pasqualotto, R.

2014-02-01

Consorzio RFX and INFN-LNL are building a flexible small ion source (Negative Ion Optimization 1, NIO1) capable of producing about 130 mA of H- ions accelerated at 60 KeV. Aim of the experiment is to test and develop the instrumentation for SPIDER and MITICA, the prototypes, respectively, of the negative ion sources and of the whole neutral beam injectors which will operate in the ITER experiment. As SPIDER and MITICA, NIO1 will be monitored with beam emission spectroscopy (BES), a non-invasive diagnostic based on the analysis of the spectrum of the Hα emission produced by the interaction of the energetic ions with the background gas. Aim of BES is to monitor direction, divergence, and uniformity of the ion beam. The precision of these measurements depends on a number of factors related to the physics of production and acceleration of the negative ions, to the geometry of the beam, and to the collection optics. These elements were considered in a set of codes developed to identify the configuration of the diagnostic which minimizes the measurement errors. The model was already used to design the BES diagnostic for SPIDER and MITICA. The paper presents the model and describes its application to design the BES diagnostic in NIO1.

Broadband two-dimensional electronic spectroscopy in an actively phase stabilized pump-probe configuration.

PubMed

Zhu, Weida; Wang, Rui; Zhang, Chunfeng; Wang, Guodong; Liu, Yunlong; Zhao, Wei; Dai, Xingcan; Wang, Xiaoyong; Cerullo, Giulio; Cundiff, Steven; Xiao, Min

2017-09-04

We introduce a novel configuration for two-dimensional electronic spectroscopy (2DES) that combines the partially collinear pump-probe geometry with active phase locking. We demonstrate the method on a solution sample of CdSe/ZnS nanocrystals by employing two non-collinear optical parametric amplifiers as the pump and probe sources. The two collinear pump pulse replicas are created using a Mach-Zehnder interferometer phase stabilized by active feedback electronics. Taking the advantage of separated paths of the two pump pulses in the interferometer, we improve the signal-to-noise ratio with double modulation of the individual pump beams. In addition, a quartz wedge pair manipulates the phase difference between the two pump pulses, enabling the recovery of the rephasing and non-rephasing signals. Our setup integrates many advantages of available 2DES techniques with robust phase stabilization, ultrafast time resolution, two-color operation, long delay scan, individual polarization manipulation and the ease of implementation.

Upgrade of beamline BL25SU for soft x-ray imaging and spectroscopy of solid using nano- and micro-focused beams at SPring-8

DOE Office of Scientific and Technical Information (OSTI.GOV)

Senba, Yasunori, E-mail: ysenba@spring8.or.jp; Ohashi, Haruhiko; Kotani, Yoshinori

2016-07-27

Substantial upgrades have been made to the beamline BL25SU at SPring-8 for soft X-ray imaging and spectroscopy of solid-state materials. The upgraded beamline consists of two branches: a micro-beam branch with high energy resolution, and a nano-beam branch with small angular divergence. The beamline has been available for use since October 2014, following a half year commissioning period. We present here the beamline performance parameters, including resolving power, photon flux, and focused beam size, which are consistent with designed specifications.

Heterodyne laser spectroscopy system

DOEpatents

Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

1989-01-01

A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency and the like, and provides spectral analysis of a laser beam.

Positron spectroscopy of 2D materials using an advanced high intensity positron beam

NASA Astrophysics Data System (ADS)

McDonald, A.; Chirayath, V.; Lim, Z.; Gladen, R.; Chrysler, M.; Fairchild, A.; Koymen, A.; Weiss, A.

An advanced high intensity variable energy positron beam(~1eV to 20keV) has been designed, tested and utilized for the first coincidence Doppler broadening (CDB) measurements on 6-8 layers graphene on polycrystalline Cu sample. The system is capable of simultaneous Positron annihilation induced Auger electron Spectroscopy (PAES) and CDB measurements giving it unparalleled sensitivity to chemical structure at external surfaces, interfaces and internal pore surfaces. The system has a 3m flight path up to a micro channel plate (MCP) for the Auger electrons emitted from the sample. This gives a superior energy resolution for PAES. A solid rare gas(Neon) moderator was used for the generation of the monoenergetic positron beam. The positrons were successfully transported to the sample chamber using axial magnetic field generated with a series of Helmholtz coils. We will discuss the PAES and coincidence Doppler broadening measurements on graphene -Cu sample and present an analysis of the gamma spectra which indicates that a fraction of the positrons implanted at energies 7-60eV can become trapped at the graphene/metal interface. This work was supported by NSF Grant No. DMR 1508719 and DMR 1338130.

Diagnostics of the ITER neutral beam test facility.

PubMed

Pasqualotto, R; Serianni, G; Sonato, P; Agostini, M; Brombin, M; Croci, G; Dalla Palma, M; De Muri, M; Gazza, E; Gorini, G; Pomaro, N; Rizzolo, A; Spolaore, M; Zaniol, B

2012-02-01

The ITER heating neutral beam (HNB) injector, based on negative ions accelerated at 1 MV, will be tested and optimized in the SPIDER source and MITICA full injector prototypes, using a set of diagnostics not available on the ITER HNB. The RF source, where the H(-)∕D(-) production is enhanced by cesium evaporation, will be monitored with thermocouples, electrostatic probes, optical emission spectroscopy, cavity ring down, and laser absorption spectroscopy. The beam is analyzed by cooling water calorimetry, a short pulse instrumented calorimeter, beam emission spectroscopy, visible tomography, and neutron imaging. Design of the diagnostic systems is presented.

Passive and active plasma deceleration for the compact disposal of electron beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonatto, A., E-mail: abonatto@lbl.gov; CAPES Foundation, Ministry of Education of Brazil, Brasília, DF 700040-020; Schroeder, C. B.

2015-08-15

Plasma-based decelerating schemes are investigated as compact alternatives for the disposal of high-energy beams (beam dumps). Analytical solutions for the energy loss of electron beams propagating in passive and active (laser-driven) schemes are derived. These solutions, along with numerical modeling, are used to investigate the evolution of the electron distribution, including energy chirp and total beam energy. In the active beam dump scheme, a laser-driver allows a more homogeneous beam energy extraction and drastically reduces the energy chirp observed in the passive scheme. These concepts could benefit applications requiring overall compactness, such as transportable light sources, or facilities operating atmore » high beam power.« less

Future directions for beam-foil spectroscopy

NASA Technical Reports Server (NTRS)

Bashkin, S.

1976-01-01

The beam-foil source has proved to be so useful for the study of atomic energy levels that it is almost trivial to propose a variety of new experiments involving new elements, higher energies, a broader wavelength range, shorter time intervals, pulsed beams, different targets, and new configurations in geometry or external fields. However, what is perhaps not so trivial is to propose experiments for which there is a specific purpose, experiments from which a novel kind of information might be expected. It is from this latter point of view that the author shall talk about experiments which seem to offer unusual opportunities to learn new things about atoms.

Isomer spectroscopy using RI beam

NASA Astrophysics Data System (ADS)

Odahara, Atsuko

2009-10-01

We have studied systematically high-spin oblate shape isomers in the N=83 isotones, which have revealed the characteristics of nuclear structure, such as the preserving pairing interactions at high-spin states, decrease of Z=64 proton shell gap energy as the decrease of proton number from 64 to 60 and so on. Recently, it became possible to search for isomers by the secondary fusion reaction at high-spin states in nuclei, which could not be populated by the stable beam and stable target, using RCNP RI beam line at Osaka University. RI beams enable us to study high-spin states in nuclei in wide mass region. By using the RI beams delivered by RIBF and the high-efficiency γ-ray detection system GRETINA, it will be possible to investigate nuclei far from the stability line. Single-particle energies and nucleon-nucleon interactions of these nuclei close to drip line are expected to be the test ground of nuclear models, such as shell structures. We have a plan to search for isomers with half lives of ˜μsec to ˜msec and to explore the decay mechanism of isomers in the proton-rich nuclei along N=Z line with 80< A<100. Moreover we try to search for nuclei beyond the proton drip line, which could be defined that isomeric states would be bound by the centrifugal potential although the ground states would be unbound against the proton emission. Isomers are expected to reveal the following characteristics of these nuclei. (1) Existence of isomers could prove the magicity of N=Z=50 and the large neutron-proton interaction, as one of the candidates of isomers is spin-gap isomer which is caused by the lowering of excitation energies resulting from the stretch coupling of spins of high-j (g9/2) holes of the ^100Sn core. (2) Isomers could prove the nuclear deformation which is caused by the evolution of shell structure. One of spin-gap isomers in ^94Ag was reported to have large prolate deformation. (3) This mass region is on the way of the rapid proton (rp) synthesis pass

High-resolution molecular-beam spectroscopy of NaCN and Na 13CN

NASA Astrophysics Data System (ADS)

van Vaals, J. J.; Meerts, W. Leo; Dymanus, A.

The sodium cyanide molecule was studied by molecular-beam electric-resonance spectroscopy in the microwave region. We used the seeded-beam technique to produce a supersonic beam with strong translational, rotational and vibrational cooling. In the frequency range 9.5-40 GHz we observed and identified for NaCN 186 and for Na 13CN 107 hyperfine transitions in 20 and 16 rotational transitions, respectively, all in the ground vibrational state. The rotational, the five quartic and three sextic centrifugal distortion constants of NaCN are: A″ = 57921.954(7) MHz; B″ = 8369.312(2) MHz, C″ = 7272.712(2) MHz. All quadrupole and several spin-rotation coupling constants for the hyperfine interaction were evaluated. The quadrupole coupling constants (in MHz) for NaCN are: eQq12(Na) = -5.344(5), eQq12 = 2.397(7). eQq12(N) = 2.148(4), eQq12(N) = -4.142(5). From these constants and those of Na 13CN we have determined the principal components of the quadrupole coupling tensor for potassium and nitrogen. The structure of sodium cyanide evaluated from the rotational constants of NaCN and Na 13CN was found to be T shaped, similar to the structure of KCN but completely different from the linear isocyanide configuration of LiNC. The effective structural parameters for sodium cyanide in the ground vibrational state are: rCN = 1.170(4) Å, rNaC = 2.379(15) Å, rN12N = 2.233(15) Å, in gratifying agreement with ab initio calculations. Both the geometrical structure and the hyperfine coupling justify the conclusion that the CN group in gaseous sodium cyanide approximately can be considered as a free CN - ion.

Electron-Beam Atomic Spectroscopy for In Situ Measurements of Melt Composition for Refractory Metals: Analysis of Fundamental Physics and Plasma Models

NASA Astrophysics Data System (ADS)

Gasper, Paul Joseph; Apelian, Diran

2015-04-01

Electron-beam (EB) melting is used for the processing of refractory metals, such as Ta, Nb, Mo, and W. These metals have high value and are critical to many industries, including the semiconductor, aerospace, and nuclear industries. EB melting can also purify secondary feedstock, enabling the recovery and recycling of these materials. Currently, there is no method for measuring melt composition in situ during EB melting. Optical emission spectroscopy of the plasma generated by EB impact with vapor above the melt, a technique here termed electron-beam atomic spectroscopy, can be used to measure melt composition in situ, allowing for analysis of melt dynamics, facilitating improvement of EB melting processes and aiding recycling and recovery of these critical and high-value metals. This paper reviews the physics of the plasma generation by EB impact by characterizing the densities and energies of electrons, ions, and neutrals, and describing the interactions between them. Then several plasma models are introduced and their suitability to this application analyzed. Lastly, a potential method for calibration-free composition measurement is described and the challenges for implementation addressed.

SU-E-J-49: Distal Edge Activity Fall Off Of Proton Therapy Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elmekawy, A; Ewell, L; Butuceanu, C

2014-06-01

Purpose: To characterize and quantify the distal edge activity fall off, created in a phantom by a proton therapy beam Method and Materials: A 30x30x10cm polymethylmethacrylate phantom was irradiated with a proton therapy beam using different ranges and beams. The irradiation volume is approximated by a right circular cylinder of diameter 7.6cm and varying lengths. After irradiation, the phantom was scanned via a Philips Gemini Big Bore™ PET-CT for isotope activation. Varian Eclipse™ treatment planning system as well as ImageJ™ were used to analyze the resulting PET and CT scans. The region of activity within the phantom was longitudinally measuredmore » as a function of PET slice number. Dose estimations were made via Monte Carlo (GATE) simulation. Results: For both the spread out Bragg peak (SOBP) and the mono-energetic pristine Bragg peak proton beams, the proximal activation rise was steep: average slope −0.735 (average intensity/slice number) ± 0.091 (standard deviation) for the pristine beams and −1.149 ± 0.117 for the SOBP beams. In contrast, the distal fall offs were dissimilar. The distal fall off in activity for the pristine beams was fit well by a linear curve: R{sup 2} (Pierson Product) was 0.9968, 0.9955 and 0.9909 for the 13.5, 17.0 and 21.0cm range beams respectively. The good fit allows for a slope comparison between the different ranges. The slope varied as a function of range from 1.021 for the 13.5cm beam to 0.8407 (average intensity/slice number) for the 21.0cm beam. This dependence can be characterized: −0.0234(average intensity/slice number/cm range). For the SOBP beams, the slopes were significantly less and were also less linear: average slope 0.2628 ± 0.0474, average R{sup 2}=0.9236. Conclusion: The distal activation fall off edge for pristine proton beams was linear and steep. The corresponding quantities for SOBP beams were shallower and less linear. Philips has provided support for this work.« less

Reactive molecular beam epitaxial growth and in situ photoemission spectroscopy study of iridate superlattices

NASA Astrophysics Data System (ADS)

Fan, C. C.; Liu, Z. T.; Cai, S. H.; Wang, Z.; Xiang, P.; Zhang, K. L.; Liu, W. L.; Liu, J. S.; Wang, P.; Zheng, Y.; Shen, D. W.; You, L. X.

2017-08-01

High-quality (001)-oriented perovskite [(SrIrO3)m/(SrTiO3)] superlattices (m=1/2, 1, 2, 3 and ∞ ) films have been grown on SrTiO3(001) epitaxially using reactive molecular beam epitaxy. Compared to previously reported superlattices synthesized by pulsed laser deposition, our superlattices exhibit superior crystalline, interface and surface structure, which have been confirmed by high-resolution X-ray diffraction, scanning transmission electron microscopy and atomic force microscopy, respectively. The transport measurements confirm a novel insulator-metal transition with the change of dimensionality in these superlattices, and our first systematic in situ photoemission spectroscopy study indicates that the increasing strength of effective correlations induced by reducing dimensionality would be the dominating origin of this transition.

Electron spectroscopy of the diamond surface

NASA Technical Reports Server (NTRS)

Pepper, S. V.

1981-01-01

The diamond surface is studied by ionization loss spectroscopy and Auger electron spectroscopy. For surfaces heated to temperatures not exceeding 900 C, the band gap was found to be devoid of empty states in the absence of electron beam effects. The incident electron beam generates empty states in the band gap and loss of structure in the valence band for these surfaces. A cross section of 1.4 x 10 to the -19th sq cm was obtained for this effect. For surfaces heated to temperatures exceeding 900 C the spectra were identical to those from surfaces modified by the electron beam. The diamond surface undergoes a thermal conversion in its electronic structure at about 900 C.

Electron beam injection during active experiments. I - Electromagnetic wave emissions

NASA Technical Reports Server (NTRS)

Winglee, R. M.; Kellogg, P. J.

1990-01-01

The wave emissions produced in Echo 7 experiment by active injections of electron beams were investigated to determine the properties of the electromagnetic and electrostatic fields for both the field-aligned and cross-field injection in such experiments and to evaluate the sources of free energy and relative efficiencies for the generation of the VLF and HF emissions. It is shown that, for typical beam energies in active experiments, electromagnetic effects do not substantially change the bulk properties of the beam, spacecraft charging, and plasma particle acceleration. Through simulations, beam-generated whistlers; fundamental z-mode and harmonic x-mode radiation; and electrostatic electron-cyclotron, upper-hybrid, Langmuir, and lower-hybrid waves were identified. The characteristics of the observed wave spectra were found to be sensitive to both the ratio of the electron plasma frequency to the cyclotron frequency and the angle of injection relative to the magnetic field.

Conformational study of 2-phenylethylamine by molecular-beam Fourier transform microwave spectroscopy.

PubMed

López, Juan C; Cortijo, Vanessa; Blanco, Susana; Alonso, Jose L

2007-08-28

The conformational preferences of the simplest amine neurotransmitter 2-phenylethylamine have been investigated using molecular beam Fourier transform microwave (MB-FTMW) spectroscopy. Two new conformers have been observed together with the two previously reported by Godfrey et al. [J. Am. Chem. Soc., 1995, 117, 8204]. The (14)N nuclear quadrupole hyperfine structure has been resolved for all four conformers. Comparison of the experimental rotational and quadrupole coupling constants with those calculated theoretically provides a conclusive test for the identification of all conformers. The two most stable conformers present a gauche (folded) disposition of the alkyl-amine chain and are stabilised by a weak NH...pi interaction between the amino group and the aromatic ring. The other two conformers show an anti (extended) arrangement of the alkyl-amine chain. Tunnelling splittings have been observed in the spectrum of one of the anti conformers. The post expansion relative abundances in the supersonic jet have been also investigated and related to the conformer energies.

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

NASA Astrophysics Data System (ADS)

Losekamm, M. J.; Milde, M.; Pöschl, T.; Greenwald, D.; Paul, S.

2017-02-01

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 cm2 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.

Carbon Beam Radio-Therapy and Research Activities at HIMAC

NASA Astrophysics Data System (ADS)

Kanazawa, Mitsutaka

2007-05-01

Radio-therapy with carbon ion beam has been carried out since 1994 at HIMAC (Heavy Ion Medical Accelerator in Chiba) in NIRS (National Institute of Radiological Sciences). Now, many types of tumors can be treated with carbon beam with excellent local controls of the tumors. Stimulated with good clinical results, requirement of the dedicated compact facility for carbon beam radio-therapy is increased. To realize this requirement, design study of the facility and the R&D's of the key components in this design are promoted by NIRS. According successful results of these activities, the dedicated compact facility will be realized in Gunma University. In this facility, the established irradiation method is expected to use, which is passive irradiation method with wobbler magnets and ridge filter. In this presentation, above R&D's will be presented together with clinical results and basic research activities at HIMAC.

Dual beam photoacoustic infrared spectroscopy of solids using an external cavity quantum cascade laser.

PubMed

Dehghany, M; Michaelian, K H

2012-06-01

Quantum cascade laser-based instrumentation for dual beam photoacoustic (PA) spectroscopy is described in this article. Experimental equipment includes a 4.55 μm (2141-2265 cm(-1)) continuous wave external cavity quantum cascade laser (EC-QCL), two gas-microphone PA cells, and two lock-in amplifiers. Correction for the time and wavenumber dependence of the laser output is effected through real-time division of the PA signals derived from the sample and reference channels. Source-compensated mid-infrared absorption spectra of carbon black powder and aromatic hydrocarbon solids were obtained to confirm the reliability of the method. Absorption maxima in the EC-QCL PA spectra of hydrocarbons are better defined than those in Fourier transform infrared spectra acquired under similar conditions, enabling the detection of several previously unknown bands.

Control of flexible beams using a free-free active truss

NASA Technical Reports Server (NTRS)

Clark, W. W.; Kimiavi, B.; Robertshaw, H. H.

1989-01-01

An analytical and experimental study involving controlling flexible beams using a free-free active truss is presented. This work extends previous work in controlling flexible continua with active trusses which were configured with fixed-free boundary conditions. The following describes the Lagrangian approach used to derive the equations of motion for the active truss and the beams attached to it. A partial-state feedback control law is derived for this system based on a full-state feedback Linear Quadratic Regulator method. The analytical model is examined via numerical simulations and the results are compared to a similar experimental apparatus described herein. The results show that control of a flexible continua is possible with a free-free active truss.

Synthesis and characterization of silver/diatomite nanocomposite by electron beam irradiation

NASA Astrophysics Data System (ADS)

Hanh, Truong Thi; Thu, Nguyen Thi; Quoc, Le Anh; Hien, Nguyen Quoc

2017-10-01

Silver nanoparticles (AgNPs) with diameter about 9 nm were deposited on diatomite by irradiation under electron beam of diatomite suspension containing 10 mM AgNO3 in 1% chitosan solution, at the dose of 20.2 kGy. The AgNPs/diatomite nanocomposite was characterized by UV-Vis spectroscopy, TEM image and energy dispersive X-ray spectroscopy (EDX). The antibacterial activity of the AgNPs/diatomite against E. coli and S. aureus was evaluated by reduction of bacterial colonies on spread plates and inhibition zone diameter on diffusion disks.

The development of enabling technologies for producing active interrogation beams.

PubMed

Kwan, Thomas J T; Morgado, Richard E; Wang, Tai-Sen F; Vodolaga, B; Terekhin, V; Onischenko, L M; Vorozhtsov, S B; Samsonov, E V; Vorozhtsov, A S; Alenitsky, Yu G; Perpelkin, E E; Glazov, A A; Novikov, D L; Parkhomchuk, V; Reva, V; Vostrikov, V; Mashinin, V A; Fedotov, S N; Minayev, S A

2010-10-01

A U.S./Russian collaboration of accelerator scientists was directed to the development of high averaged-current (∼1 mA) and high-quality (emittance ∼15 πmm mrad; energy spread ∼0.1%) 1.75 MeV proton beams to produce active interrogation beams that could be applied to counterterrorism. Several accelerator technologies were investigated. These included an electrostatic tandem accelerator of novel design, a compact cyclotron, and a storage ring with energy compensation and electron cooling. Production targets capable of withstanding the beam power levels were designed, fabricated, and tested. The cyclotron/storage-ring system was theoretically studied and computationally designed, and the electrostatic vacuum tandem accelerator at BINP was demonstrated for its potential in active interrogation of explosives and special nuclear materials.

Experimental characterization of active plasma lensing for electron beams

NASA Astrophysics Data System (ADS)

Pompili, R.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Bini, S.; Bisesto, F.; Brentegani, E.; Castorina, G.; Chiadroni, E.; Cianchi, A.; Croia, M.; Di Giovenale, D.; Ferrario, M.; Filippi, F.; Giribono, A.; Lollo, V.; Marocchino, A.; Marongiu, M.; Mostacci, A.; Di Pirro, G.; Romeo, S.; Rossi, A. R.; Scifo, J.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

2017-03-01

The active plasma lens represents a compact and affordable tool with radially symmetric focusing and field gradients up to several kT/m. In order to be used as a focusing device, its effects on the particle beam distribution must be well characterized. Here, we present the experimental results obtained by focusing an high-brightness electron beam by means of a 3 cm-long discharge-capillary pre-filled with Hydrogen gas. We achieved minimum spot sizes of 24 μ m (rms) showing that, during plasma lensing, the beam emittance increases due to nonlinearities in the focusing field. The results have been cross-checked with numerical simulations, showing an excellent agreement.

Active Plasma Lensing for Relativistic Laser-Plasma-Accelerated Electron Beams

DOE PAGES

van Tilborg, J.; Steinke, S.; Geddes, C. G. R.; ...

2015-10-28

The compact, tunable, radially symmetric focusing of electrons is critical to laser-plasma accelerator (LPA) applications. Experiments are presented demonstrating the use of a discharge-capillary active plasma lens to focus 100-MeV-level LPA beams. The lens can provide tunable field gradients in excess of 3000 T/m, enabling cm-scale focal lengths for GeV-level beam energies and allowing LPA-based electron beams and light sources to maintain their compact footprint. For a range of lens strengths, excellent agreement with simulation was obtained.

Ion beam activation for materials analysis: Methods and application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conlon, T.W.

1981-04-01

A number of ion beam methods for materials analysis have been developed using Harwell's high voltage accelerators and these are currently being exploited for applications 'in house' and in industry. Ion beam activation is a relatively new area which has exhibited exceptional growth over the last few years. Activation by ion beams to produce a single dominant radioisotope as a surface label (thin layer activation or TLA) is becoming a mature technology offering ever increasing sensitivity for surface loss measurement (currently better than 0.1 ..mu..m or 10/sup -7/ cm/sup 3/ depending on the method of measurement) and remote monitoring ofmore » inaccessible components during studies of wear/erosion/ corrosion/sputtering and the like. With the increasingly established credibility of the method has come the realisation that: (i) more complex and even multiple activation profiles can be used to extract more information on the characteristics of the surface loss process, (ii) that an analogous method can be used even on radiation sensitive materials through the newly established indirect recoil implantation process. (iii) that there is scope for treatment of truly immovable objects through the implantation of fission fragments, (iv) there is vast potential in the area of activation analysis. The current state of development of these methods which greatly extend the scope of conventional TLA will be briefly reviewed. Current applications of these and TLA in industry are discussed.« less

Preliminary Findings of the Brief Everyday Activities Measurement (BEAM) in Older Adults.

PubMed

Scharaga, E A; Holtzer, R

2015-11-01

Functional losses are common in healthy and cognitively impaired older adults. However, subtle declines in instrumental activities of daily living (IADLs) are not always detected in self-reports. Performance IADL measurements are financially and time burdensome, restricting their use in varied settings. To address these limitations, we developed the Brief Everyday Activities Measure (BEAM), a short (< 5 minutes) objective IADL measure that assesses medication and finance management. The BEAM was administered to 209 cognitively non-demented community-dwellers (ages 65 - 95 years). Participants completed standardized motor, neuropsychological, psychological, and self-report functional assessments. BEAM completion time ranged from 54.16 to 259.31 seconds. Interclass correlations (ICC) for total BEAM completion time was moderate (0.65, 95% CI [.43 -.78]). Accuracy for total BEAM performance was in the low-moderate range (Kappa = 0.38, p < .001, 95% CI [.18 -.54]). As predicted, lower accuracy and longer time to complete the BEAM were both associated with worse executive functions, attention, and processing speed. Medication and finance management can be efficiently assessed within five minutes. The BEAM may be a valuable screening tool to evaluate these functional abilities.

Electron spectroscopy analysis

NASA Technical Reports Server (NTRS)

Gregory, John C.

1992-01-01

The Surface Science Laboratories at the University of Alabama in Huntsville (UAH) are equipped with x-ray photoelectron spectroscopy (XPS or ESCA) and Auger electron spectroscopy (AES) facilities. These techniques provide information from the uppermost atomic layers of a sample, and are thus truly surface sensitive. XPS provides both elemental and chemical state information without restriction on the type of material that can be analyzed. The sample is placed into an ultra high vacuum (UHV) chamber and irradiated with x-rays which cause the ejection of photoelectrons from the sample surface. Since x-rays do not normally cause charging problems or beam damage, XPS is applicable to a wide range of samples including metals, polymers, catalysts, and fibers. AES uses a beam of high energy electrons as a surface probe. Following electronic rearrangements within excited atoms by this probe, Auger electrons characteristic of each element present are emitted from the sample. The main advantage of electron induced AES is that the electron beam can be focused down to a small diameter and localized analysis can be carried out. On the rastering of this beam synchronously with a video display using established scanning electron microscopy techniques, physical images and chemical distribution maps of the surface can be produced. Thus very small features, such as electronic circuit elements or corrosion pits in metals, can be investigated. Facilities are available on both XPS and AES instruments for depth-profiling of materials, using a beam of argon ions to sputter away consecutive layers of material to reveal sub-surface (and even semi-bulk) analyses.

Analysis of edge density fluctuation measured by trial KSTAR beam emission spectroscopy systema)

NASA Astrophysics Data System (ADS)

Nam, Y. U.; Zoletnik, S.; Lampert, M.; Kovácsik, Á.

2012-10-01

A beam emission spectroscopy (BES) system based on direct imaging avalanche photodiode (APD) camera has been designed for Korea Superconducting Tokamak Advanced Research (KSTAR) and a trial system has been constructed and installed for evaluating feasibility of the design. The system contains two cameras, one is an APD camera for BES measurement and another is a fast visible camera for position calibration. Two pneumatically actuated mirrors were positioned at front and rear of lens optics. The front mirror can switch the measurement between edge and core region of plasma and the rear mirror can switch between the APD and the visible camera. All systems worked properly and the measured photon flux was reasonable as expected from the simulation. While the measurement data from the trial system were limited, it revealed some interesting characteristics of KSTAR plasma suggesting future research works with fully installed BES system. The analysis result and the development plan will be presented in this paper.

Plasma Turbulence Imaging via Beam Emission Spectroscopy in the Core of the DIII-D Tokamak

NASA Astrophysics Data System (ADS)

McKee, George R.; Fonck, Raymond J.; Gupta, Deepak K.; Schlossberg, David J.; Shafer, Morgan W.; Boivin, Réjean L.; Solomon, Wayne

Beam Emission Spectroscopy (BES), a high-sensitivity, good spatial resolution imaging diagnostic system, has been deployed and recently upgraded and expanded at the DIII-D tokamak to better understand density fluctuations arising from plasma turbulence. The currently deployed system images density fluctuations over an approximately 5 × 7 cm region at the plasma mid-plane (radially scannable over 0.2 < r/a ≤ 1) with a 5 × 6 (radial × poloidal) grid of rectangular detection channels, with one microsecond time resolution. BES observes collisionally-induced, Doppler-shifted Dα fluorescence (λ = 652-655 nm) of injected deuterium neutral beam atoms. The diagnostic wavenumber sensitivity is approximately k⊥ < 2.5 cm-1, allowing measurement of longwavelength (k⊥ρI < 1) density fluctuations. The recent upgrade includes expanded fiber optics bundles, customdesigned high-transmission, sharp-edge interference filters, ultra fast collection optics, and enlarged photodiode detectors that together provide nearly an order of magnitude increase in sensitivity relative to an earlier generation BES system. The high sensitivity allows visualization of turbulence at normalized density fluctuation amplitudes of ‾n/n < 1%, typical of fluctuation levels in the core region. The imaging array allows for sampling over 2-3 turbulent eddy scale lengths, which captures the essential dynamics of eddy evolution, interaction and shearing.

Beam-plasma coupling physics in support of active experiments

NASA Astrophysics Data System (ADS)

Yakymenko, K.; Delzanno, G. L.; Roytershteyn, V.

2017-12-01

The recent development of compact relativistic accelerators might open up a new era of active experiments in space, driven by important scientific and national security applications. Examples include using electron beams to trace magnetic field lines and establish causality between physical processes occurring in the magnetosphere and those in the ionosphere. Another example is the use of electron beams to trigger waves in the near-Earth environment. Waves could induce pitch-angle scattering and precipitation of energetic electrons, acting as an effective radiation belt remediation scheme. In this work, we revisit the coupling between an electron beam and a magnetized plasma in the framework of linear cold-plasma theory. We show that coupling can occur through two different regimes. In the first, a non-relativistic beam radiates through whistler waves. This is well known, and was in fact the focus of many rockets and space-shuttle campaigns aimed at demonstrating whistler emissions in the eighties. In the second regime, the beam radiates through extraordinary (R-X) modes. Nonlinear simulations with a highly-accurate Vlasov code support the theoretical results qualitatively and demonstrate that the radiated power through R-X modes can be much larger than in the whistler regime. Test-particle simulations in the wave electromagnetic field will also be presented to assess the efficiency of these waves in inducing pitch-angle scattering via wave-particle interactions. Finally, the implications of these results for a rocket active experiment in the ionosphere and for a radiation belt remediation scheme will be discussed.

Size dependent bandgap of molecular beam epitaxy grown InN quantum dots measured by scanning tunneling spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Mahesh; Roul, Basanta; Central Research Laboratory, Bharat Electronics, Bangalore-560013

InN quantum dots (QDs) were grown on Si (111) by epitaxial Stranski-Krastanow growth mode using plasma-assisted molecular beam epitaxy. Single-crystalline wurtzite structure of InN QDs was verified by the x-ray diffraction and transmission electron microscopy. Scanning tunneling microscopy has been used to probe the structural aspects of QDs. A surface bandgap of InN QDs was estimated from scanning tunneling spectroscopy (STS) I-V curves and found that it is strongly dependent on the size of QDs. The observed size-dependent STS bandgap energy shifts with diameter and height were theoretical explained based on an effective mass approximation with finite-depth square-well potential model.

Active echolocation beam focusing in the false killer whale, Pseudorca crassidens.

PubMed

Kloepper, Laura N; Nachtigall, Paul E; Donahue, Megan J; Breese, Marlee

2012-04-15

The odontocete sound production system is highly complex and produces intense, directional signals that are thought to be focused by the melon and the air sacs. Because odontocete echolocation signals are variable and the emitted click frequency greatly affects the echolocation beam shape, investigations of beam focusing must account for frequency-related beam changes. In this study we tested whether the echolocation beam of a false killer whale changed depending on target difficulty and distance while also accounting for frequency-related changes in the echolocation beam. The data indicate that the false killer whale changes its beam size according to target distance and difficulty, which may be a strategy of maximizing the energy of the target echo. We propose that the animal is using a strategy of changing the focal region according to target distance and that this strategy is under active control.

Minimal-effort planning of active alignment processes for beam-shaping optics

NASA Astrophysics Data System (ADS)

Haag, Sebastian; Schranner, Matthias; Müller, Tobias; Zontar, Daniel; Schlette, Christian; Losch, Daniel; Brecher, Christian; Roßmann, Jürgen

2015-03-01

In science and industry, the alignment of beam-shaping optics is usually a manual procedure. Many industrial applications utilizing beam-shaping optical systems require more scalable production solutions and therefore effort has been invested in research regarding the automation of optics assembly. In previous works, the authors and other researchers have proven the feasibility of automated alignment of beam-shaping optics such as collimation lenses or homogenization optics. Nevertheless, the planning efforts as well as additional knowledge from the fields of automation and control required for such alignment processes are immense. This paper presents a novel approach of planning active alignment processes of beam-shaping optics with the focus of minimizing the planning efforts for active alignment. The approach utilizes optical simulation and the genetic programming paradigm from computer science for automatically extracting features from a simulated data basis with a high correlation coefficient regarding the individual degrees of freedom of alignment. The strategy is capable of finding active alignment strategies that can be executed by an automated assembly system. The paper presents a tool making the algorithm available to end-users and it discusses the results of planning the active alignment of the well-known assembly of a fast-axis collimator. The paper concludes with an outlook on the transferability to other use cases such as application specific intensity distributions which will benefit from reduced planning efforts.

Epitaxial pentacene films grown on the surface of ion-beam-processed gate dielectric layer

NASA Astrophysics Data System (ADS)

Chou, W. Y.; Kuo, C. W.; Cheng, H. L.; Mai, Y. S.; Tang, F. C.; Lin, S. T.; Yeh, C. Y.; Horng, J. B.; Chia, C. T.; Liao, C. C.; Shu, D. Y.

2006-06-01

The following research describes the process of fabrication of pentacene films with submicron thickness, deposited by thermal evaporation in high vacuum. The films were fabricated with the aforementioned conditions and their characteristics were analyzed using x-ray diffraction, scanning electron microscopy, polarized Raman spectroscopy, and photoluminescence. Organic thin-film transistors (OTFTs) were fabricated on an indium tin oxide coated glass substrate, using an active layer of ordered pentacene molecules, which were grown at room temperature. Pentacene film was aligned using the ion-beam aligned method, which is typically employed to align liquid crystals. Electrical measurements taken on a thin-film transistor indicated an increase in the saturation current by a factor of 15. Pentacene-based OTFTs with argon ion-beam-processed gate dielectric layers of silicon dioxide, in which the direction of the ion beam was perpendicular to the current flow, exhibited a mobility that was up to an order of magnitude greater than that of the controlled device without ion-beam process; current on/off ratios of approximately 106 were obtained. Polarized Raman spectroscopy investigation indicated that the surface of the gate dielectric layer, treated with argon ion beam, enhanced the intermolecular coupling of pentacene molecules. The study also proposes the explanation for the mechanism of carrier transportation in pentacene films.

Sub-millisecond electron density profile measurement at the JET tokamak with the fast lithium beam emission spectroscopy system

NASA Astrophysics Data System (ADS)

Réfy, D. I.; Brix, M.; Gomes, R.; Tál, B.; Zoletnik, S.; Dunai, D.; Kocsis, G.; Kálvin, S.; Szabolics, T.; JET Contributors

2018-04-01

Diagnostic alkali atom (e.g., lithium) beams are routinely used to diagnose magnetically confined plasmas, namely, to measure the plasma electron density profile in the edge and the scrape off layer region. A light splitting optics system was installed into the observation system of the lithium beam emission spectroscopy diagnostic at the Joint European Torus (JET) tokamak, which allows simultaneous measurement of the beam light emission with a spectrometer and a fast avalanche photodiode (APD) camera. The spectrometer measurement allows density profile reconstruction with ˜10 ms time resolution, absolute position calculation from the Doppler shift, spectral background subtraction as well as relative intensity calibration of the channels for each discharge. The APD system is capable of measuring light intensities on the microsecond time scale. However ˜100 μs integration is needed to have an acceptable signal to noise ratio due to moderate light levels. Fast modulation of the beam up to 30 kHz is implemented which allows background subtraction on the 100 μs time scale. The measurement covers the 0.9 < ρpol < 1.1 range with 6-10 mm optical resolution at the measurement location which translates to 3-5 mm radial resolution at the midplane due to flux expansion. An automated routine has been developed which performs the background subtraction, the relative calibration, and the comprehensive error calculation, runs a Bayesian density reconstruction code, and loads results to the JET database. The paper demonstrates the capability of the APD system by analyzing fast phenomena like pellet injection and edge localized modes.

Electron beam agrobionanotechnologies for agriculture and food industry enabled by electron accelerators

NASA Astrophysics Data System (ADS)

Pavlov, Y. S.; Revina, A. A.; Souvorova, O. V.; Voropaeva, N. L.; Chekmar, D. V.; Abkhalimov, E. V.; Zavyalov, M. A.; Filippovich, V. P.

2017-12-01

Electron beam (EB) radiation technologies have been employed to increase efficiency of biologically active nanochips developed for agricultural plants seed pre-treatment with purpose of enhancing crop yield and productivity. Iron-containing nanoparticles (NPs), synthesized in reverse micelles following known radiation-chemical technique, have served as a multifunctional biologically active and phytosanitary substance of the chips. Porous chip carriers activation has been performed by EB ionization (doze 20kGy) of the active carbons (AC) prepared from agricultural waste and by-products: Jerusalem artichoke (Helianthus tuberosus) straw, rape (Brassica napus L. ssp. oleifera Metzg) straw, camelina (Camelina sativa (L.) Crantz) straw, wheat (Triticum aestivum) straw. Three methods, UV-VIS spectrophotometry, Electron Paramagnetic Resonance (EPR) spectroscopy, cyclic voltammetry (CV) have been used for process control and characterization of radiation-activated and NPs-modified ACs. The results show a notable effect of ACs activation by electron beam radiation, evidenced by FeNPs-adsorption capacity increase. Studies of the impact of Fe NPs-containing nanochip technology on enhancement of seeds germination rate and seedlings vigour suggest that reported electron beam radiation treatment techniques of the ACs from selected agricultural residues may be advantageous for industrial application.

Enabling two-dimensional fourier transform electronic spectroscopy on quantum dots

NASA Astrophysics Data System (ADS)

Hill, Robert John, Jr.

Colloidal semiconductor nanocrystals exhibit unique properties not seen in their bulk counterparts. Quantum confinement of carriers causes a size-tunable bandgap, making them attractive candidates for solar cells. Fundamental understanding of their spectra and carrier dynamics is obscured by inhomogeneous broadening arising from the size distribution. Because quantum dots have long excited state lifetimes and are sensitive to both air and moisture, there are many potential artifacts in femtosecond experiments. Two-dimensional electronic spectroscopy promises insight into the photo-physics, but required key instrumental advances. Optics that can process a broad bandwidth without distortion are required for a two-dimensional optical spectrometer. To control pathlength differences for femtosecond time delays, hollow retro-reflectors are used on actively stabilized delay lines in interferometers. The fabrication of rigid, lightweight, precision hollow rooftop retroreflectors that allow beams to be stacked while preserving polarization is described. The rigidity and low mass enable active stabilization of an interferometer to within 0.6 nm rms displacement, while the return beam deviation is sufficient for Fourier transform spectroscopy with a frequency precision of better than 1 cm -1. Keeping samples oxygen and moisture free while providing fresh sample between laser shots is challenging in an interferometer. A low-vibration spinning sample cell was designed and built to keep samples oxygen free for days while allowing active stabilization of interferometer displacement to ˜1 nm. Combining these technologies has enabled 2D short-wave infrared spectroscopy on colloidal PbSe nanocrystals. 2D spectra demonstrate the advantages of this key instrumentation while providing valuable insight into the low-lying electronic states of colloidal quantum dots.

Characterisation of the properties of a negative hydrogen ion beam by several beam diagnostic techniques

NASA Astrophysics Data System (ADS)

Maurizio, R.; Fantz, U.; Bonomo, F.; Serianni, G.

2016-06-01

The beam properties of the BATMAN negative ion source, which is the prototype of one module of the source for the ITER neutral beam injection system, are characterised by means of three diagnostic techniques: beam emission spectroscopy (BES), the experimental calorimeter mini-STRIKE and a copper calorimeter. The main beam parameters—beam divergence, homogeneity and top-bottom asymmetries—are studied in different operational scenarios: with different magnetic filter field setups, source settings and with different gases (hydrogen or deuterium). Among all dependences, the influence of the magnetic field configuration on the beam and the evolution of the beam features during some conditioning days are investigated in detail. Data show that the stronger the filter field in the beam region, the higher the beam top-bottom asymmetry—likely a v× B effect. During the conditioning of the source, such vertical beam asymmetry increases as well, suggesting an inhomogeneous H -production at the first grid of the extraction system.

Raman spectroscopy applied to identify metabolites in urine of physically active subjects.

PubMed

Moreira, Letícia Parada; Silveira, Landulfo; da Silva, Alexandre Galvão; Fernandes, Adriana Barrinha; Pacheco, Marcos Tadeu Tavares; Rocco, Débora Dias Ferraretto Moura

2017-11-01

Raman spectroscopy is a rapid and non-destructive technique suitable for biological fluids analysis. In this work, dispersive Raman spectroscopy has been employed as a rapid and nondestructive technique to detect the metabolites in urine of physically active subjects before and after vigorous 30min pedaling or running compared to sedentary subjects. For so, urine samples from 9 subjects were obtained before and immediately after physical activities and submitted to Raman spectroscopy (830nm excitation, 250mW laser power, 20s integration time) and compared to urine from 5 sedentary subjects. The Raman spectra of urine from sedentary showed peaks related to urea, creatinine, ketone bodies, phosphate and other nitrogenous compounds. These metabolic biomarkers presented peaks with different intensities in the urine of physically active individuals after exercises compared to before, measured by the intensity of selected peaks the Raman spectra, which means different concentrations after training. These peaks presented different intensity values for each subject before physical activity, also behaving differently compared to the post-training: some subjects presented increase while others decrease the intensity. Raman spectroscopy may allow the development of a rapid and non-destructive test for metabolic evaluation of the physical training in active and trained subjects using urine samples, allowing nutrition adjustment with the sport's performance. Copyright © 2017 Elsevier B.V. All rights reserved.

Gold nano-particle formation from crystalline AuCN: Comparison of thermal, plasma- and ion-beam activated decomposition

NASA Astrophysics Data System (ADS)

Beck, Mihály T.; Bertóti, Imre; Mohai, Miklós; Németh, Péter; Jakab, Emma; Szabó, László; Szépvölgyi, János

2017-02-01

In this work, in addition to the conventional thermal process, two non-conventional ways, the plasma and ion beam activations are described for preparing gold nanoparticles from microcrystalline AuCN precursor. The phase formation at plasma and ion beam treatments was compared with that at thermal treatments and the products and transformations were characterized by thermogravimetry-mass-spectrometry (TG-MS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). TG-MS measurements in Ar atmosphere revealed that AuCN decomposition starts at 400 °C and completes at ≈700 °C with evolution of gaseous (CN)2. XPS and TEM show that in heat treatment at 450 °C for 1 h in Ar, loss of nitrogen and carbon occurs and small, 5-30 nm gold particles forms. Heating at 450 °C for 10 h in sealed ampoule, much larger, 60-200 nm size and well faceted Au particles develop together with a fibrous (CN)n polymer phase, and the Au crystallites are covered by a 3-5 nm thick polymer shell. Low pressure Ar plasma treatment at 300 eV energy results in 4-20 nm size Au particles and removes most of the nitrogen and part of carbon. During Ar+ ion bombardment with 2500 eV energy, 5-30 nm size Au crystallites form already in 10 min, with preferential loss of nitrogen and with increased amount of carbon residue. The results suggest that plasma and ion beam activation, acting similarly to thermal treatment, may be used to prepare Au nanoparticles from AuCN on selected surface areas either by depositing AuCN precursors on selected regions or by focusing the applied ionized radiation. Thus they may offer alternative ways for preparing tailor-made catalysts, electronic devices and sensors for different applications.

A high etendue spectrometer suitable for core charge eXchange recombination spectroscopy on ITER.

PubMed

Jaspers, R J E; Scheffer, M; Kappatou, A; van der Valk, N C J; Durkut, M; Snijders, B; Marchuk, O; Biel, W; Pokol, G I; Erdei, G; Zoletnik, S; Dunai, D

2012-10-01

A feasibility study for the use of core charge exchange recombination spectroscopy on ITER has shown that accurate measurements on the helium ash require a spectrometer with a high etendue of 1mm(2)sr to comply with the measurement requirements [S. Tugarinov et al., Rev. Sci. Instrum. 74, 2075 (2003)]. To this purpose such an instrument has been developed consisting of three separate wavelength channels (to measure simultaneously He/Be, C/Ne, and H/D/T together with the Doppler shifted direct emission of the diagnostic neutral beam, the beam emission (BES) signal), combining high dispersion (0.02 nm/pixel), sufficient resolution (0.2 nm), high efficiency (55%), and extended wavelength range (14 nm) at high etendue. The combined measurement of the BES along the same sightline within a third wavelength range provides the possibility for in situ calibration of the charge eXchange recombination spectroscopy signals. In addition, the option is included to use the same instrument for measurements of the fast fluctuations of the beam emission intensity up to 2 MHz, with the aim to study MHD activity.

Azimuthal velocity measurement in the ion beam of a gridded ion thruster using laser-induced fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Tsukizaki, Ryudo; Yamamoto, Yuta; Koda, Daiki; Yusuke, Yamashita; Nishiyama, Kazutaka; Kuninaka, Hitoshi

2018-01-01

This paper presents the first laboratory-based study to measure the azimuthal velocities of ions in the beam of a gridded ion thruster. Through the operation of gridded ion thrusters in space, it has been confirmed that these thrusters cause an unexpected roll torque about the ion beam axis. To reveal the physical mechanism that produces this torque, laser-induced fluorescence spectroscopy has been applied to a microwave ion thruster that was installed in Japanese asteroid probes. This technique can be used to measure the azimuthal velocity by estimating the Doppler shift of the Xe II 5p 4({}3{P}2)6p {}2{[3]}0 5/2 to Xe II 5p 4({}3{P}2)6s {}2[2] 3/2 transition at 834.659 nm. The measurement was conducted without a neutralizer cathode to avoid the possibility of the cathode affecting the trajectory of the ion beam. The measured velocity functions are the sum of the spectra of the high velocity beam ions and those of charge exchange ions. By deconvolving these spectra, the azimuthal velocities were successfully measured and were found to range from -700 to 620 m s-1 with an accuracy of ±25%. The measured azimuthal velocity profile was accurately reproduced by the simulated velocity profile obtained using a model, which includes the effects of the maximum possible misalignment of the accelerator grid with respect to the screen grid and the Lorentz force produced by the magnetic field leaked from the discharge chamber. A roll torque of 0.5 ± 0.1 μN m about the thrust axis was calculated from the velocity profile, which is lower than that reported in flight data, but additional mechanisms are suggested to explain this discrepancy.

Low-temperature, ultrahigh-vacuum tip-enhanced Raman spectroscopy combined with molecular beam epitaxy for in situ two-dimensional materials' studies

NASA Astrophysics Data System (ADS)

Sheng, Shaoxiang; Li, Wenbin; Gou, Jian; Cheng, Peng; Chen, Lan; Wu, Kehui

2018-05-01

Tip-enhanced Raman spectroscopy (TERS), which combines scanning probe microscopy with the Raman spectroscopy, is capable to access the local structure and chemical information simultaneously. However, the application of ambient TERS is limited by the unstable and poorly controllable experimental conditions. Here, we designed a high performance TERS system based on a low-temperature ultrahigh-vacuum scanning tunneling microscope (LT-UHV-STM) and combined with a molecular beam epitaxy (MBE) system. It can be used for growing two-dimensional (2D) materials and for in situ STM and TERS characterization. Using a 2D silicene sheet on the Ag(111) surface as a model system, we achieved an unprecedented 109 Raman single enhancement factor in combination with a TERS spatial resolution down to 0.5 nm. The results show that TERS combined with a MBE system can be a powerful tool to study low dimensional materials and surface science.

Fourteenth Exotic Beam Summer School EBSS 2015

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiedenhoever, Ingo

The Fourteenth Annual Exotic Beam Summer School EBSS 2015 was held August 2nd - August 7th, 2015, and belongs to the series of summer programs aimed at educating future workforce in nuclear physics-related areas, mostly about the challenges of radioactive ion beam physics. Through these schools the research community will be able to exploit fully the opportunities created by the exotic beam facilities. These facilities in the US include CARIBU at ANL, the NSCL and the future FRIB laboratory as well as smaller-scale university laboratories. The skill set needed by the future workforce is very diverse and a fundamental understandingmore » of theoretical, technical, computational and applied fields are all important. Therefore, the Exotic Beam Summer Schools follow a unique approach, in which the students not only receive lectures but also participate in hands-on activities. The lectures covered broad topics in both the experimental and theoretical physics of nuclei far from stability as well as radioactive ions production and applications. The afternoons provided opportunities for "hands-on" projects with experimental equipment and techniques useful in FRIB research. Five activities were performed in groups of eight students, rotating through the activities over the five afternoons of the school. The center of the activities was an experiment at the FSU tandem accelerator, measuring the angular distribution and cross section of the 12C(d,p) 13C transfer reaction, measured with a silicon telescope in a scattering chamber. The experimental data were analyzed by performing a DWBA calculation with the program DWUCK, and the resulting spectroscopic factors were compared to a shell model calculation. The other activities included target preparation, digital gamma-spectroscopy and modern neutron detection methods.« less

Method and apparatus for two-dimensional spectroscopy

DOEpatents

DeCamp, Matthew F.; Tokmakoff, Andrei

2010-10-12

Preferred embodiments of the invention provide for methods and systems of 2D spectroscopy using ultrafast, first light and second light beams and a CCD array detector. A cylindrically-focused second light beam interrogates a target that is optically interactive with a frequency-dispersed excitation (first light) pulse, whereupon the second light beam is frequency-dispersed at right angle orientation to its line of focus, so that the horizontal dimension encodes the spatial location of the second light pulse and the first light frequency, while the vertical dimension encodes the second light frequency. Differential spectra of the first and second light pulses result in a 2D frequency-frequency surface equivalent to double-resonance spectroscopy. Because the first light frequency is spatially encoded in the sample, an entire surface can be acquired in a single interaction of the first and second light pulses.

Laser light-scattering spectroscopy: a new application in the study of ciliary activity.

PubMed Central

Lee, W I; Verdugo, P

1976-01-01

A uniquely precise and simple method to study ciliary activity by laser light-scattering spectroscopy has been developed and validated. A concurrent study of the effect of Ca2+ on ciliary activity in vitro by laser scattering spectroscopy and high speed cinematography has demonstrated that this new method is simpler and as accurate and reproducible as the high speed film technique. PMID:963208

2D scrape-off layer turbulence measurement using Deuterium beam emission spectroscopy on KSTAR

NASA Astrophysics Data System (ADS)

Lampert, M.; Zoletnik, S.; Bak, J. G.; Nam, Y. U.; Kstar Team

2018-04-01

Intermittent events in the scrape-off layer (SOL) of magnetically confined plasmas, often called blobs and holes, contribute significantly to the particle and heat loss across the magnetic field lines. In this article, the results of the scrape-off layer and edge turbulence measurements are presented with the two-dimensional Deuterium Beam Emission Spectroscopy system (DBES) at KSTAR (Korea Superconducting Tokamak Advanced Research). The properties of blobs and holes are determined in an L-mode and an H-mode shot with statistical tools and conditional averaging. These results show the capabilities and limitations of the SOL turbulence measurement of a 2D BES system. The results from the BES study were compared with the analysis of probe measurements. It was found that while probes offer a better signal-to-noise ratio and can measure blobs down to 3 mm size, BES can monitor the two-dimensional dynamics of larger events continuously during full discharges, and the measurement is not limited to the SOL on KSTAR.

SERS-Active Nanoinjector for Intracellular Spectroscopy

NASA Astrophysics Data System (ADS)

Vitol, Elina; Orynbayeva, Zulfiya; Bouchard, Michael; Azizkhan-Clifford, Jane; Friedman, Gary; Gogotsi, Yury

2009-03-01

We developed a multifunctional nanopipette which allows simultaneous cell injection and intacellular surface-enhanced Raman spectroscopy (SERS) analysis. SERS spectra contain the characteristic frequencies of molecular bond vibrations. This is a unique method for studying cell biochemistry and physiology on a single organelle level. Unlike the fluorescence spectroscopy, it does not require any specific staining. The principle of SERS is based on very large electromagnetic field enhancement localized around a nano-rough metallic surface. Gold colloids are widely used SERS substrates. Previously, the colloidal nanoparticles were introduced into a cell by the mechanism of endocytosis. The disadvantage of this method is the uncontrollable aggregation and distribution of gold nanoparticles inside a cell which causes a significant uncertainty in the origin of the acquired data. At the same time, the nanoparticle uptake is irreversible. We present a SERS-active nanoinjector, coated with gold nanoparticles, which enables selective signal acquisition from any point-of-interest inside a cell. The nanoinjector provides a highly localized SERS signal with sub-nanometer resolution in real time.

Raman-Ramsey multizone spectroscopy in a pure rubidium vapor cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Failache, H.; Lenci, L.; Lezama, A.

2010-02-15

In view of application to a miniaturized spectroscopy system, we consider an optical setup that splits a laser beam into several parallel narrow light sheets allowing an effective beam expansion and consequently longer atom-light interaction times. We analyze the multizone coherent population trapping (MZCPT) spectroscopy of alkali-metal-vapor atoms, without buffer gas, in the presence of a split light beam. We show that the MZCPT signal is largely insensitive to intensity broadening. Experimentally observed spectra are in qualitative agreement with the predictions of a simplified model that describes each spectrum as an integral over the atomic velocity distribution of Ramsey multizonemore » spectra.« less

Using Deep UV Raman Spectroscopy to Identify In Situ Microbial Activity

NASA Astrophysics Data System (ADS)

Sapers, H. M.; Wanger, G.; Amend, J.; Orphan, V. J.; Bhartia, R.

2017-12-01

Microbial communities living in close association with lithic substrates play a critical role in biogeochemical cycles. Understanding the interactions between microorganisms and their abiotic substrates requires knowledge of microbial activity. Identifying active cells adhered to complex environmental substrates, especially in low biomass systems, remains a challenge. Stable isotope probing (SIP) provides a means to trace microbial activity in environmental systems. Active members of the community take up labeled substrates and incorporate the labels into biomolecules that can be detected through downstream analyses. Here we show for the first time that Deep UV (248 nm) Raman spectroscopy can differentiate microbial cells labeled with stable isotopes. Previous studies have used Raman spectroscopy with a 532 nm source to identify active bacterial cells by measuring a Raman shift between peaks corresponding to amino acids incorporating 13C compared to controls. However, excitation at 532 nm precludes detection on complex substrates due to high autofluorescence of native minerals. Excitation in the DUV range offers non-destructive imaging on mineral surfaces - retaining critical contextual information. We prepared cultures of E. coli grown in 50 atom% 13C glucose spotted onto Al wafers to test the ability of DUV Raman spectroscopy to differentiate labeled and unlabeled cells. For the first time, we are able to demonstrate a distinct and repeatable shift between cells grown in labeled media and unlabeled media when imaged on Al wafers with DUV Raman spectroscopy. The Raman spectra are dominated by the characteristic Raman bands of guanine. The dominant marker peak for guanine attributed to N7-C8 and C8-N9 ring stretching and C8-H in-plane bending, is visible at 1480 cm-1 in the unlabeled cells and is blue-shifted by 20 wavenumbers to 1461 cm-1 in the labeled cells. The ability of DUV Raman to effectively identify regions containing cells that have incorporated isotopic

"Reagent-free" L-asparaginase activity assay based on CD spectroscopy and conductometry.

PubMed

Kudryashova, Elena V; Sukhoverkov, Kirill V

2016-02-01

A new method to determine the catalytic parameters of L-asparaginase using circular dichroism spectroscopy (CD spectroscopy) has been developed. The assay is based on the difference in CD signal between the substrate (L-asparagine) and the product (L-aspartic acid) of enzymatic reaction. CD spectroscopy, being a direct method, enables continuous measurement, and thus differentiates from multistage and laborious approach based on Nessler's method, and overcomes limitations of conjugated enzymatic reaction methods. In this work, we show robust measurements of L-asparaginase activity in conjugates with PEG-chitosan copolymers, which otherwise would not have been possible. The main limitation associated with the CD method is that the analysis should be performed at substrate saturation conditions (V max regime). For K M measurement, the conductometry method is suggested, which can serve as a complimentary method to CD spectroscopy. The activity assay based on CD spectroscopy and conductometry was successfully implicated to examine the catalytic parameters of L-asparaginase conjugates with chitosan and its derivatives, and for optimization of the molecular architecture and composition of such conjugates for improving biocatalytic properties of the enzyme in the physiological conditions. The approach developed is potentially applicable to other enzymatic reactions where the spectroscopic properties of substrate and product do not enable direct measurement with absorption or fluorescence spectroscopy. This may include a number of amino acid or glycoside-transforming enzymes.

Analysis of activation and shutdown contact dose rate for EAST neutral beam port

NASA Astrophysics Data System (ADS)

Chen, Yuqing; Wang, Ji; Zhong, Guoqiang; Li, Jun; Wang, Jinfang; Xie, Yahong; Wu, Bin; Hu, Chundong

2017-12-01

For the safe operation and maintenance of neutral beam injector (NBI), specific activity and shutdown contact dose rate of the sample material SS316 are estimated around the experimental advanced superconducting tokamak (EAST) neutral beam port. Firstly, the neutron emission intensity is calculated by TRANSP code while the neutral beam is co-injected to EAST. Secondly, the neutron activation and shutdown contact dose rates for the neutral beam sample materials SS316 are derived by the Monte Carlo code MCNP and the inventory code FISPACT-2007. The simulations indicate that the primary radioactive nuclides of SS316 are 58Co and 54Mn. The peak contact dose rate is 8.52 × 10-6 Sv/h after EAST shutdown one second. That is under the International Thermonuclear Experimental Reactor (ITER) design values 1 × 10-5 Sv/h.

Near-infrared spectroscopy can reveal increases in brain activity related to animal-assisted therapy.

PubMed

Morita, Yuka; Ebara, Fumio; Morita, Yoshimitsu; Horikawa, Etsuo

2017-08-01

[Purpose] Previous studies have indicated that animal-assisted therapy can promote recovery of psychological, social, and physiological function in mental disorders. This study was designed as a pilot evaluation of the use of near-infrared spectroscopy to objectively identify changes in brain activity that could mediate the effect of animal-assisted therapy. [Subjects and Methods] The participants were 20 healthy students (10 males and 10 females; age 19-21 years) of the Faculty of Agriculture, Saga University. Participants were shown a picture of a Tokara goat or shack (control) while prefrontal cortical oxygenated haemoglobin levels (representing neural activity) were measured by near-infrared spectroscopy. [Results] The prefrontal cortical near-infrared spectroscopy signal was significantly higher during viewing of the animal picture than during a rest condition or during viewing of the control picture. [Conclusion] Our results suggest that near-infrared spectroscopy can be used to objectively identify brain activity changes during human mentation regarding animals; furthermore, these preliminary results suggest the efficacy of animal-assisted therapy could be related to increased activation of the prefrontal cortex.

A new, simple and precise method for measuring cyclotron proton beam energies using the activity vs. depth profile of zinc-65 in a thick target of stacked copper foils.

PubMed

Asad, A H; Chan, S; Cryer, D; Burrage, J W; Siddiqui, S A; Price, R I

2015-11-01

The proton beam energy of an isochronous 18MeV cyclotron was determined using a novel version of the stacked copper-foils technique. This simple method used stacked foils of natural copper forming 'thick' targets to produce Zn radioisotopes by the well-documented (p,x) monitor-reactions. Primary beam energy was calculated using the (65)Zn activity vs. depth profile in the target, with the results obtained using (62)Zn and (63)Zn (as comparators) in close agreement. Results from separate measurements using foil thicknesses of 100, 75, 50 or 25µm to form the stacks also concurred closely. Energy was determined by iterative least-squares comparison of the normalized measured activity profile in a target-stack with the equivalent calculated normalized profile, using 'energy' as the regression variable. The technique exploits the uniqueness of the shape of the activity vs. depth profile of the monitor isotope in the target stack for a specified incident energy. The energy using (65)Zn activity profiles and 50-μm foils alone was 18.03±0.02 [SD] MeV (95%CI=17.98-18.08), and 18.06±0.12MeV (95%CI=18.02-18.10; NS) when combining results from all isotopes and foil thicknesses. When the beam energy was re-measured using (65)Zn and 50-μm foils only, following a major upgrade of the ion sources and nonmagnetic beam controls the results were 18.11±0.05MeV (95%CI=18.00-18.23; NS compared with 'before'). Since measurement of only one Zn monitor isotope is required to determine the normalized activity profile this indirect yet precise technique does not require a direct beam-current measurement or a gamma-spectroscopy efficiency calibrated with standard sources, though a characteristic photopeak must be identified. It has some advantages over published methods using the ratio of cross sections of monitor reactions, including the ability to determine energies across a broader range and without need for customized beam degraders. Copyright © 2015 Elsevier Ltd. All rights

Apparatus Translates Crossed-Laser-Beam Probe Volume

NASA Technical Reports Server (NTRS)

Herring, Gregory C.; South, Bruce W.; Exton, Reginald J.

1994-01-01

Optomechanical apparatus translates probe volume of crossed-beam laser velocimeter or similar instrument while maintaining optical alignment of beams. Measures velocity, pressure, and temperature of flowing gas at several locations. Repeated tedious realignments no longer necessary. Designed to accommodate stimulated-Raman-gain spectrometer for noninvasive measurement of local conditions in flowing gas in supersonic wind tunnel. Applicable to other techniques like coherent anti-Stokes Raman spectroscopy involving use of laser beams crossed at small angles (10 degrees or less).

Turbulence imaging and applications using beam emission spectroscopy on DIII-D (invited)

NASA Astrophysics Data System (ADS)

McKee, G. R.; Fenzi, C.; Fonck, R. J.; Jakubowski, M.

2003-03-01

Two-dimensional measurements of density fluctuations are obtained in the radial and poloidal plane of the DIII-D tokamak with the Beam Emission Spectroscopy (BES) diagnostic system. The goals are to visualize the spatial structure and time evolution of turbulent eddies, as well as to obtain the 2D statistical properties of turbulence. The measurements are obtained with an array of localized BES spatial channels configured to image a midplane region of the plasma. 32 channels have been deployed, each with a spatial resolution of about 1 cm in the radial and poloidal directions, thus providing measurements of turbulence in the wave number range 0

Active tuning of vibration and wave propagation in elastic beams with periodically placed piezoelectric actuator/sensor pairs

NASA Astrophysics Data System (ADS)

Li, Fengming; Zhang, Chuanzeng; Liu, Chunchuan

2017-04-01

A novel strategy is proposed to actively tune the vibration and wave propagation properties in elastic beams. By periodically placing the piezoelectric actuator/sensor pairs along the beam axis, an active periodic beam structure which exhibits special vibration and wave propagation properties such as the frequency pass-bands and stop-bands (or band-gaps) is developed. Hamilton's principle is applied to establish the equations of motion of the sub-beam elements i.e. the unit-cells, bonded by the piezoelectric patches. A negative proportional feedback control strategy is employed to design the controllers which can provide a positive active stiffness to the beam for a positive feedback control gain, which can increase the stability of the structural system. By means of the added positive active stiffness, the periodicity or the band-gap property of the beam with periodically placed piezoelectric patches can be actively tuned. From the investigation, it is shown that better band-gap characteristics can be achieved by using the negative proportional feedback control. The band-gaps can be obviously broadened by properly increasing the control gain, and they can also be greatly enlarged by appropriately designing the structural sizes of the controllers. The control voltages applied on the piezoelectric actuators are in reasonable and controllable ranges, especially, they are very low in the band-gaps. Thus, the vibration and wave propagation behaviors of the elastic beam can be actively controlled by the periodically placed piezoelectric patches.

Modelling and Vibration Control of Beams with Partially Debonded Active Constrained Layer Damping Patch

NASA Astrophysics Data System (ADS)

SUN, D.; TONG, L.

2002-05-01

A detailed model for the beams with partially debonded active constraining damping (ACLD) treatment is presented. In this model, the transverse displacement of the constraining layer is considered to be non-identical to that of the host structure. In the perfect bonding region, the viscoelastic core is modelled to carry both peel and shear stresses, while in the debonding area, it is assumed that no peel and shear stresses be transferred between the host beam and the constraining layer. The adhesive layer between the piezoelectric sensor and the host beam is also considered in this model. In active control, the positive position feedback control is employed to control the first mode of the beam. Based on this model, the incompatibility of the transverse displacements of the active constraining layer and the host beam is investigated. The passive and active damping behaviors of the ACLD patch with different thicknesses, locations and lengths are examined. Moreover, the effects of debonding of the damping layer on both passive and active control are examined via a simulation example. The results show that the incompatibility of the transverse displacements is remarkable in the regions near the ends of the ACLD patch especially for the high order vibration modes. It is found that a thinner damping layer may lead to larger shear strain and consequently results in a larger passive and active damping. In addition to the thickness of the damping layer, its length and location are also key factors to the hybrid control. The numerical results unveil that edge debonding can lead to a reduction of both passive and active damping, and the hybrid damping may be more sensitive to the debonding of the damping layer than the passive damping.

Electron impact action spectroscopy of mass/charge selected macromolecular ions: Inner-shell excitation of ubiquitin protein

NASA Astrophysics Data System (ADS)

Ranković, Miloš Lj.; Giuliani, Alexandre; Milosavljević, Aleksandar R.

2016-02-01

We have performed inner-shell electron impact action spectroscopy of mass and charge selected macromolecular ions. For this purpose, we have coupled a focusing electron gun with a linear quadrupole ion trap mass spectrometer. This experiment represents a proof of principle that an energy-tunable electron beam can be used in combination with radio frequency traps as an activation method in tandem mass spectrometry (MS2) and allows performing action spectroscopy. Electron impact MS2 spectra of multiply protonated ubiquitin protein ion have been recorded at incident electron energies around the carbon 1 s excitation. Both MS2 and single ionization energy dependence spectra are compared with literature data obtained using the soft X-ray activation conditions.

Improved Beam Diagnostic Spatial Calibration Using In-Situ Measurements of Beam Emission

NASA Astrophysics Data System (ADS)

Chrystal, C.; Burrell, K. H.; Pace, D. C.; Grierson, B. A.; Pablant, N. A.

2014-10-01

A new technique has been developed for determining the measurement geometry of the charge exchange recombination spectroscopy diagnostic (CER) on DIII-D. This technique removes uncertainty in the measurement geometry related to the position of the neutral beams when they are injecting power. This has been accomplished by combining standard measurements that use in-vessel calibration targets with spectroscopic measurements of Doppler shifted and Stark split beam emission to fully describe the neutral beam positions and CER views. A least squares fitting routine determines the measurement geometry consistent with all the calibration data. The use of beam emission measurements allows the position of the neutral beams to be determined in-situ by the same views that makeup the CER diagnostic. Results indicate that changes in the measurement geometry are required to create a consistent set of calibration measurements. However, changes in quantities derived from the geometry, e.g. ion temperature gradient and poloidal rotation, are small. Work supported by the US DOE under DE-FG02-07ER54917, DE-FC02-04ER54698, and DE-AC02-09H11466.

Two-photon absorption spectroscopy using intense phase-chirped entangled beams

NASA Astrophysics Data System (ADS)

Svozilík, Jiří; Peřina, Jan; León-Montiel, Roberto de J.

2018-06-01

We numerically analyze the use of intense entangled twin beams for ultra-sensitive spectroscopic measurements in chemical and biological systems. The examined scheme makes use of intense frequency-modulated (chirped) entangled beams to successfully extract information about the intermediate material states that contribute to the two-photon excitation of an absorbing medium. Robustness of the presented method is examined with respect to the applied intervals of the frequency chirp.

Photothermal Beam Deflection Spectroscopy for the Determination of Thermal Diffusivity of Soils and Soil Aggregates

NASA Astrophysics Data System (ADS)

Proskurnin, M. A.; Korte, D.; Rogova, O. B.; Volkov, D. S.; Franko, M.

2018-07-01

Photothermal beam deflection spectroscopy (BDS) with a red He-Ne laser (632.8 nm, 35 mW) as an excitation beam source and a green He-Ne laser (543.1 nm, 2 mW) as a probe was used for estimating thermal diffusivity of several types of soil samples and individual soil aggregates with small surfaces (2 × 2 mm). It is shown that BDS can be used on demand for studies of changes in properties of soil entities of different hierarchical levels under the action of agrogenesis. It is presented that BDS clearly distinguishes between thermal diffusivities of different soil types: Sod-podzolic [Umbric Albeluvisols, Abruptic], 29 ± 3; Chernozem typical [Voronic Chernozems, Pachic], 9.9 ± 0.9; and Light Chestnut [Haplic Kastanozems, Chromic], 9.7 ± 0.9 cm2·h-1. Aggregates of chernozem soil show a significantly higher thermal diffusivity compared to the bulk soil. Thermal diffusivities of aggregates of Chernozem for virgin and bare fallow samples differ, 53 ± 4 cm2·h-1 and 45 ± 4 cm2·h-1, respectively. Micromonoliths of different Sod-podzolic soil horizons within the same profile (topsoil, depth 10-14 cm, and a parent rock with Fe illuviation, depth 180-185 cm) also show a significant difference, thermal diffusivities are 9.5 ± 0.8 cm2·h-1 and 27 ± 2 cm2·h-1, respectively. For soil micromonoliths, BDS is capable to distinguish the difference in thermal diffusivity resulting from the changes in the structure of aggregates.

Damage and annealing recovery of boron-implanted ultra-shallow junction: The correlation between beam current and surface configuration

NASA Astrophysics Data System (ADS)

Chang, Feng-Ming; Wu, Zong-Zhe; Lin, Yen-Fu; Kao, Li-Chi; Wu, Cheng-Ta; JangJian, Shiu-Ko; Chen, Yuan-Nian; Lo, Kuang Yao

2018-03-01

The condition of the beam current in the implantation process is a key issue in the damage rate and structural evolution in the sequent annealing process, especially for ultra-shallow layers. In this work, we develop a compensative optical method combined with UV Raman, X-ray photoelectron spectroscopy (XPS), and X-ray absorption near edge spectroscopy (XANES) to inspect the influence of the beam current in the implantation process. The optima condition of the beam current in the implantation process is determined by higher effective Si-B bond portion in UV Raman spectra and less the peak of B-B bond in XPS spectra which is caused by B cluster defects. Results of XANES indicate that the B oxide layer is formed on the surface of the ultra-shallow junction. The defects in the ultra-shallow junction after annealing are analyzed by novel optical analyses, which cannot be inspected by a traditional thermal wave and resistance measurement. This work exhibits the structural variation of the ultra-shallow junction via a variant beam current and provides a valuable metrology in examining the chemical states and the effective activation in the implantation technology.

Positron lifetime beam for defect studies in thin epitaxial semiconductor structures

NASA Astrophysics Data System (ADS)

Laakso, A.; Saarinen, K.; Hautojärvi, P.

2001-12-01

Positron annihilation spectroscopies are methods for direct identification of vacancy-type defects by measuring positron lifetime and Doppler broadening of annihilation radiation and providing information about open volume, concentration and atoms surrounding the defect. Both these techniques are easily applied to bulk samples. Only the Doppler broadening spectroscopy can be employed in thin epitaxial samples by utilizing low-energy positron beams. Here we describe the positron lifetime beam which will provide us with a method to measure lifetime in thin semiconductor layers.

Simultaneous Conoscopic Holography and Raman Spectroscopy

NASA Technical Reports Server (NTRS)

Schramm, Harry F.; Kaiser, Bruce

2005-01-01

A new instrument was developed for chemical characterization of surfaces that combines the analytical power of Raman spectroscopy with the three-dimensional topographic information provided by conoscopic holography. The figure schematically depicts the proposed hybrid instrument. The output of the conoscopic holographic portion of the instrument is a topographical map of the surface; the output of the Raman portion of the instrument is hyperspectral Raman data, from which the chemical and/or biological composition of the surface would be deduced. By virtue of the basic principles of design and operation of the instrument, the hyperspectral image data would be inherently spatially registered with the topographical data. In conoscopic holography, the object and reference beams of classical holography are replaced by the ordinary and extraordinary components generated by a single beam traveling through a birefringent, uniaxial crystal. In the basic conoscopic configuration, a laser light is projected onto a specimen and the resulting illuminated spot becomes a point source of diffuse light that propagates in every direction. The laser beam is rasterscanned in two dimensions (x and y) perpendicular to the beam axis (z), and at each x,y location, the pattern of interference between the ordinary and extraordinary rays is recorded. The recorded interferogram constitutes the conoscopic hologram. Of particular significance for the proposed instrument is that the conoscopic hologram contains information on the z coordinate (height) of the illuminated surface spot. Hence, a topographical map of the specimen is constructed point-by-point by rastering the laser beam in the x and y directions and correlating the x and y coordinates with the z information obtained from the interferograms. Conoscopic imaging is an established method, and conoscopic laboratory instruments for surface metrology are commercially available. In Raman spectroscopy of a surface, one measures the spectrum

The effect of optically active turbulence on Gaussian laser beams in the ocean

NASA Astrophysics Data System (ADS)

Nootz, G.; Matt, S.; Jarosz, E.; Hou, W.

2016-02-01

Motivated by the high resolution and data transfer potential, optical imaging and communication methods are intensely investigated for marine applications. The majority of research focuses on overcoming the strong scattering of light by particles present in the ocean. However when operating in very clear water the limiting factor for such applications can be the strongly forward biased scattering from optically active turbulent layers. For this presentation the effect of optically active turbulence on focused Gaussian beams has been studied in the field, in a controlled laboratory test tank, and by numerical simulations. For the field experiments a telescoping rigid underwater sensor structure (TRUSS) was deployed in the Bahamas equipped with a diffractive optics element projecting a matrix of beams towards a fast beam profiler. Image processing techniques are used to extract the beam wander and beam breathing. The results are compared to theoretical values for the optical turbulence strength derived from the measured temperature microstructure at the test side. Laboratory and simulated experiments are carried out in a physical and numerical Rayleigh-Benard convection turbulence tank of the same geometry. A focused Gaussian laser beam is propagated through the test tank and recorded with a camera from the back side of a diffuser. Similarly, a focused Gaussian beam is propagated numerically by means of split-step Fourier method through the simulated turbulence environment. Results will be presented for weak to moderate turbulence as they are most typical for oceanic conditions. Conclusions about the effect on optical imaging and communication applications will be discussed.

Capacitance spectroscopy on n-type GaNAs/GaAs embedded quantum structure solar cells

NASA Astrophysics Data System (ADS)

Venter, Danielle; Bollmann, Joachim; Elborg, Martin; Botha, J. R.; Venter, André

2018-04-01

In this study, both deep level transient spectroscopy (DLTS) and admittance spectroscopy (AS) have been used to study the properties of electrically active deep level centers present in GaNAs/GaAs quantum wells (QWs) embedded in p-i-n solar cells. The structures were grown by molecular beam epitaxy (MBE). In particular, the electrical properties of samples with Si (n-type) doping of the QWs were investigated. DLTS revealed four deep level centers in the material, whereas only three were detected by AS. NextNano++ simulation software was used to model the sample band-diagrams to provide reasoning for the origin of the signals produced by both techniques.

Present and future experiments using bright low-energy positron beams

NASA Astrophysics Data System (ADS)

Hugenschmidt, Christoph

2017-01-01

Bright slow positron beams enable not only experiments with drastically reduced measurement time and improved signal-to-noise ratio but also the realization of novel experimental techniques. In solid state physics and materials science positron beams are usually applied for the depth dependent analysis of vacancy-like defects and their chemical surrounding using positron lifetime and (coincident) Doppler broadening spectroscopy. For surface studies, annihilation induced Auger-electron spectroscopy allows the analysis of the elemental composition in the topmost atomic layer, and the atomic positions at the surface can be determined by positron diffraction with outstanding accuracy. In fundamental research low-energy positron beams are used for the production of e.g. cold positronium or positronium negative ions. All the aforementioned experiments benefit from the high intensity of present positron beam facilities. In this paper, we scrutinize the technical constraints limiting the achievable positron intensity and the available kinetic energy at the sample position. Current efforts and future developments towards the generation of high intensity spin-polarized slow positron beams paving the way for new positron experiments are discussed.

Plasma effects of active ion beam injections in the ionosphere at rocket altitudes

NASA Technical Reports Server (NTRS)

Arnoldy, R. L.; Cahill, L. J., Jr.; Kintner, P. M.; Moore, T. E.; Pollock, C. J.

1992-01-01

Data from ARCS rocket ion beam injection experiments are primarily discussed. There are three results from this series of active experiments that are of particular interest in space plasma physics. These are the transverse acceleration of ambient ions in the large beam volume, the scattering of beam ions near the release payload, and the possible acceleration of electrons very close to the plasma generator which produce intense high frequency waves. The ability of 100 ma ion beam injections into the upper E and F regions of the ionosphere to produce these phenomena appear to be related solely to the process by which the plasma release payload and the ion beam are neutralized. Since the electrons in the plasma release do not convect with the plasma ions, the neutralization of both the payload and beam must be accomplished by large field-aligned currents (milliamperes/square meter) which are very unstable to wave growth of various modes.

Recent advances in β-decay spectroscopy at CARIBU

NASA Astrophysics Data System (ADS)

Mitchell, A. J.; Copp, P.; Savard, G.; Lister, C. J.; Lane, G. J.; Carpenter, M. P.; Clark, J. A.; Zhu, S.; Ayangeakaa, A. D.; Bottoni, S.; Brown, T. B.; Chowdhury, P.; Chillery, T. W.; David, H. M.; Hartley, D. J.; Heckmaier, E.; Janssens, R. V. F.; Kolos, K.; Kondev, F. G.; Lauritsen, T.; McCutchan, E. A.; Norman, E. B.; Padgett, S.; Scielzo, N. D.; Seweryniak, D.; Smith, M. L.; Wilson, G. L.

2016-09-01

β-decay spectroscopy of nuclei far from stability can provide powerful insight into a broad variety of topics in nuclear science, ranging from exotic nuclear structure phenomena, stellar nucleosynthesis processes, and applied topics such as quantifying "decay heat" discrepancies for advanced nuclear fuel cycles. Neutronrich nuclei approaching the drip-line are difficult to access experimentally, leaving many key examples largely under studied. The CARIBU radioactive beam facility at Argonne National Laboratory exploits spontaneous fission of 252Cf in production of such beams. The X-Array and SATURN decay station have been commissioned to perform detailed decay spectroscopy of low-energy CARIBU beams. An extended science campaign was started during 2015; with projects investigating nuclear shape changes, collective octupole vibrations, β-delayed neutron emission, and decay-scheme properties which could explain the reactor antineutrino puzzle. In this article we review the current status of the setup, update on the first results and recent hardware upgrades, and look forward to future possibilities.

Nuclear structure study for the neutron-rich nuclei beyond 132Sn: In-beam gamma-ray spectroscopy of 136Sn and 132Cd

NASA Astrophysics Data System (ADS)

Wang, He; Aoi, Nori; Takeuchi, Satoshi; Matsushita, Masafumi; Doornenbal, Pieter; Motobayashi, Tohru; Steppenbeck, David; Yoneda, Kenichiro; Baba, Hidetada; Dombrádi, Zsolt; Kobayashi, Kota; Kondo, Yosuke; Lee, Jenny; Liu, Hong-Na; Minakata, Ryogo; Nishimura, Daiki; Otsu, Hideaki; Sakurai, Hiroyoshi; Sohler, Dora; Sun, Ye-Lei; Tian, Zheng-Yang; Tanaka, Ryuki; Vajta, Zsolt; Yang, Zai-Hong; Yamamoto, Tetsuya; Ye, Yan-Lin; Yokoyama, Rin

2018-05-01

The neutron-rich nuclei 136Sn and 132Cd have been studied in the purpose of nuclear structure for the nuclei beyond the doubly-magic nucleus 132Sn. The 2+1 → 0+ gs transitions were identified for these two nuclei using in-beam γ-ray spectroscopy in coincidence with one- and two-proton removal reactions, respectively, at the RIKEN Radioactive Isotope Beam Factory. The 2+ 1 state in 136Sn is found to be similar to that for 134Sn indicating the seniority scheme may also hold for the heavy tin isotopes beyond N = 82. For 132Cd, the 2+ 1 state provides the first spectroscopic information in the even-even nuclei locating in the region "southeast" of 132Sn and the result is discussed in terms of proton-neutron configuration mixing. In both these two nuclei, it was found that the valence neutrons play an essential role in their low-lying excitations.

Band offsets and growth mode of molecular beam epitaxy grown MgO (111) on GaN (0002) by x-ray photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Craft, H. S.; Collazo, R.; Losego, M. D.; Mita, S.; Sitar, Z.; Maria, J.-P.

2007-10-01

MgO is a proposed dielectric for use as a tunneling barrier in devices integrating GaN and ferroelectric oxides. In this study, we present data regarding the growth mode and band offsets of MgO grown epitaxially on GaN (0002) surfaces using molecular beam epitaxy. Using in situ x-ray photoelectron spectroscopy (XPS) and molecular beam epitaxy, we determine, from sequential growth experiments, that the growth of MgO proceeds via the Volmer-Weber (three-dimensional) mode, and full coalescence of the film does not occur until approximately 12nm of MgO has been deposited. The observation of a three-dimensional growth mode is in agreement with previously published data. For the valence band offset, we find a value of 1.2±0.2eV, which corresponds to a 3.2eV conduction band offset. XPS measurements suggest a chemically abrupt interface and no effect on band lineup due to the slow coalescence behavior.

Induction of antioxidant enzyme activity and lipid peroxidation level in ion-beam-bombarded rice seeds

NASA Astrophysics Data System (ADS)

Semsang, Nuananong; Yu, LiangDeng

2013-07-01

Low-energy ion beam bombardment has been used to mutate a wide variety of plant species. To explore the indirect effects of low-energy ion beam on biological damage due to the free radical production in plant cells, the increase in antioxidant enzyme activities and lipid peroxidation level was investigated in ion-bombarded rice seeds. Local rice seeds were bombarded with nitrogen or argon ion beams at energies of 29-60 keV and ion fluences of 1 × 1016 ions cm-2. The activities of the antioxidant enzymes; superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione S-transferase (GST) and lipid peroxidation level were assayed in the germinated rice seeds after ion bombardment. The results showed most of the enzyme activities and lipid peroxidation levels in both the argon and nitrogen bombarded samples were higher than those in the natural control. N-ion bombardment could induce higher levels of antioxidant enzyme activities in the rice samples than the Ar-ion bombardment. Additional effects due to the vacuum condition were found to affect activities of some antioxidant enzymes and lipid peroxidation level. This study demonstrates that ion beam bombardment and vacuum condition could induce the antioxidant enzyme activity and lipid peroxidation level which might be due to free radical production in the bombarded rice seeds.

Active buckling control of an imperfect beam-column with circular cross-section using piezo-elastic supports and integral LQR control

NASA Astrophysics Data System (ADS)

Schaeffner, Maximilian; Platz, Roland

2016-09-01

For slender beam-columns loaded by axial compressive forces, active buckling control provides a possibility to increase the maximum bearable axial load above that of a purely passive structure. In this paper, the potential of active buckling control of an imperfect beam-column with circular cross-section using piezo-elastic supports is investigated numerically. Imperfections are given by an initial deformation of the beam-column caused by a constant imperfection force. With the piezo-elastic supports, active bending moments in arbitrary directions orthogonal to the beam-column's longitudinal axis can be applied at both beam- column's ends. The imperfect beam-column is loaded by a gradually increasing axial compressive force resulting in a lateral deformation of the beam-column. First, a finite element model of the imperfect structure for numerical simulation of the active buckling control is presented. Second, an integral linear-quadratic regulator (LQR) that compensates the deformation via the piezo-elastic supports is derived for a reduced modal model of the ideal beam-column. With the proposed active buckling control it is possible to stabilize the imperfect beam-column in arbitrary lateral direction for axial loads above the theoretical critical buckling load and the maximum bearable load of the passive structure.

Electron impact action spectroscopy of mass/charge selected macromolecular ions: Inner-shell excitation of ubiquitin protein

DOE PAGES

Rankovic, Milos Lj.; Giuliani, Alexandre; Milosavljevic, Aleksandar R.

2016-02-11

In this study, we have performed inner-shell electron impact action spectroscopy of mass and charge selected macromolecular ions. For this purpose, we have coupled a focusing electron gun with a linear quadrupole ion trap mass spectrometer. This experiment represents a proof of principle that an energy-tunable electron beam can be used in combination with radio frequency traps as an activation method in tandem mass spectrometry (MS 2) and allows performing action spectroscopy. Electron impact MS 2 spectra of multiply protonated ubiquitin protein ion have been recorded at incident electron energies around the carbon 1s excitation. Both MS 2 and singlemore » ionization energy dependence spectra are compared with literature data obtained using the soft X-ray activation conditions.« less

Electron impact action spectroscopy of mass/charge selected macromolecular ions: Inner-shell excitation of ubiquitin protein

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rankovic, Milos Lj.; Giuliani, Alexandre; Milosavljevic, Aleksandar R.

In this study, we have performed inner-shell electron impact action spectroscopy of mass and charge selected macromolecular ions. For this purpose, we have coupled a focusing electron gun with a linear quadrupole ion trap mass spectrometer. This experiment represents a proof of principle that an energy-tunable electron beam can be used in combination with radio frequency traps as an activation method in tandem mass spectrometry (MS 2) and allows performing action spectroscopy. Electron impact MS 2 spectra of multiply protonated ubiquitin protein ion have been recorded at incident electron energies around the carbon 1s excitation. Both MS 2 and singlemore » ionization energy dependence spectra are compared with literature data obtained using the soft X-ray activation conditions.« less

Molecular-beam Studies of Primary Photochemical Processes

DOE R&D Accomplishments Database

Lee, Y. T.

1982-12-01

Application of the method of molecular-beam photofragmentation translational spectroscopy to the investigation of primary photochemical processes of polyatomic molecules is described. Examples will be given to illustrate how information concerning the energetics, dynamics, and mechanism of dissociation processes can be obtained from the precise measurements of angular and velocity distributions of products in an experiment in which a well-defined beam of molecules is crossed with a laser.

A highly sensitive electron spectrometer for crossed-beam collisional ionization: A retarding-type magnetic bottle analyzer and its application to collision-energy resolved Penning ionization electron spectroscopy

NASA Astrophysics Data System (ADS)

Yamakita, Yoshihiro; Tanaka, Hideyasu; Maruyama, Ryo; Yamakado, Hideo; Misaizu, Fuminori; Ohno, Koichi

2000-08-01

A highly sensitive electron energy analyzer which utilizes a "magnetic bottle" combined with a retarding electrostatic field has been developed for Penning ionization electron spectroscopy. A beam of metastable rare-gas atoms is crossed with a continuous supersonic sample beam in the source region of the analyzer. The emitted electrons are collected by an inhomogeneous magnetic field (the magnetic bottle effect) with a high efficiency of nearly 4π solid angle, which is more than 103 times higher than that of a conventional hemispherical analyzer. The kinetic energy of electrons is analyzed by scanning the retarding field in a flight tube of the analyzer in the presence of a weak magnetic field. The velocity of the metastable atoms can also be resolved by a time-of-flight method in the present instrument. Examples of Penning ionization electron energy spectra as a function of collision energy are presented for Ar and N2 with metastable He*(2 3S) atoms. This instrument has opened the possibility for extensive studies of Penning ionization electron spectroscopy for low-density species, such as clusters, ions, electronically excited species, unstable or transient species, and large molecules with low volatility.

Active-passive vibration absorber of beam-cart-seesaw system with piezoelectric transducers

NASA Astrophysics Data System (ADS)

Lin, J.; Huang, C. J.; Chang, Julian; Wang, S.-W.

2010-09-01

In contrast with fully controllable systems, a super articulated mechanical system (SAMS) is a controlled underactuated mechanical system in which the dimensions of the configuration space exceed the dimensions of the control input space. The objectives of the research are to develop a novel SAMS model which is called beam-cart-seesaw system, and renovate a novel approach for achieving a high performance active-passive piezoelectric vibration absorber for such system. The system consists of two mobile carts, which are coupled via rack and pinion mechanics to two parallel tracks mounted on pneumatic rodless cylinders. One cart carries an elastic beam, and the other cart acts as a counterbalance. One adjustable counterweight mass is also installed underneath the seesaw to serve as a passive damping mechanism to absorb impact and shock energy. The motion and control of a Bernoulli-Euler beam subjected to the modified cart/seesaw system are analyzed first. Moreover, gray relational grade is utilized to investigate the sensitivity of tuning the active proportional-integral-derivative (PID) controller to achieve desired vibration suppression performance. Consequently, it is shown that the active-passive vibration absorber can not only provide passive damping, but can also enhance the active action authority. The proposed software/hardware platform can also be profitable for the standardization of laboratory equipment, as well as for the development of entertainment tools.

Measurement of Activation Cross Sections Producing Short-Lived Nuclei with Pulsed Neutron Beam

NASA Astrophysics Data System (ADS)

Shimizu, Toshiaki; Arakita, Kazumasa; Miyazaki, Itaru; Shibata, Michihiro; Kawade, Kiyoshi; Hori, Jun-ichi; Ochiai, Kentaro; Nishitani, Takeo

2005-05-01

Activation cross sections for the (n, n') reaction were measured by means of the activation method at the neutron energies of 3.1 and 2.54 MeV by using a pulsed neutron beam. Target nuclei were 79Br, 90Zr, 197Au, and 207Pb, whose half-lives were between 0.8 and 8 s. The cross section for the 90Zr (n, n') 90mZr reaction was obtained for the first time in this energy range. The d-D neutrons were generated by bombarding a deuterated titanium target with a 350-keV d+ beam at the 80-degree beam line of the Fusion Neutronics Source at the Japan Atomic Energy Research Institute. In order to obtain reliable activation cross sections, careful attention was paid to correct the efficiency for a volume source, and the self-absorption of gamma rays in an irradiated sample. The systematics of the (n, n') reaction at the neutron energy of 3.1 MeV, which could be predicted within an accuracy of 50%, was proposed on the basis of our data.

In-beam γ-ray spectroscopy of excited states in 141Pm

NASA Astrophysics Data System (ADS)

Aryaeinejad, R.; Walker, P. M.; Firestone, R. B.; McHarris, Wm. C.

1985-12-01

The level structure of the N=80 nucleus 141Pm has been studied in-beam by the 142Nd(p,2nγ)141Pm reaction using a 25-MeV p beam and by the 141(α,4nγ)141Pm reaction using a 47-MeV α beam. γ-ray singles, γ-γ coincidence (both prompt and delayed), and angular distribution experiments were performed. We found 42 γ rays deexciting 28 states in 141Pm from the (p,2nγ) reaction and 34 γ rays deexciting 22 (generally higher-spin) states from the (α,4nγ) reaction, for a total of 35 known states in 141Pm. These in-beam experiments, taken together with the results from 141Smm+g decay, yield Jπ assignments for most of the states and have allowed us to deduce the configurations for many of the states. The structures are discussed in terms of single-quasiparticle shell-model and triaxial weak-coupled collective states and are compared with systematics for this nuclear region.

Active buckling control of a beam-column with circular cross-section using piezo-elastic supports and integral LQR control

NASA Astrophysics Data System (ADS)

Schaeffner, Maximilian; Götz, Benedict; Platz, Roland

2016-06-01

Buckling of slender beam-columns subject to axial compressive loads represents a critical design constraint for light-weight structures. Active buckling control provides a possibility to stabilize slender beam-columns by active lateral forces or bending moments. In this paper, the potential of active buckling control of an axially loaded beam-column with circular solid cross-section by piezo-elastic supports is investigated experimentally. In the piezo-elastic supports, lateral forces of piezoelectric stack actuators are transformed into bending moments acting in arbitrary directions at the beam-column ends. A mathematical model of the axially loaded beam-column is derived to design an integral linear quadratic regulator (LQR) that stabilizes the system. The effectiveness of the stabilization concept is investigated in an experimental test setup and compared with the uncontrolled system. With the proposed active buckling control it is possible to stabilize the beam-column in arbitrary lateral direction for axial loads up to the theoretical critical buckling load of the system.

A Neutral Beam for the Lithium Tokamak eXperiment Upgrade (LTX-U)

NASA Astrophysics Data System (ADS)

Merino, Enrique; Majeski, Richard; Kaita, Robert; Kozub, Thomas; Boyle, Dennis; Schmitt, John; Smirnov, Artem

2015-11-01

Neutral beam injection into tokamaks is a proven method of plasma heating and fueling. In LTX, high confinement discharges have been achieved with low-recycling lithium walls. To further improve plasma performance, a neutral beam (NB) will be installed as part of an upgrade to LTX (LTX-U). The NB will provide core plasma fueling with up to 700 kW of injected power. Requirements for accommodating the NB include the addition of injection and beam-dump ports onto the vessel and enhancement of the vacuum vessel pumping capability. Because the NB can also serve as a source of neutrals for charge-exchange recombination spectroscopy, ``active'' spectroscopic diagnostics will also be developed. An overview of these plans and other improvements for upgrading LTX to LTX-U will be presented. Supported by US DOE contracts DE-AC02-09CH11466 and DE-AC52-07NA27344.

Process analytical technology (PAT) in insect and mammalian cell culture processes: dielectric spectroscopy and focused beam reflectance measurement (FBRM).

PubMed

Druzinec, Damir; Weiss, Katja; Elseberg, Christiane; Salzig, Denise; Kraume, Matthias; Pörtner, Ralf; Czermak, Peter

2014-01-01

Modern bioprocesses demand for a careful definition of the critical process parameters (CPPs) already during the early stages of process development in order to ensure high-quality products and satisfactory yields. In this context, online monitoring tools can be applied to recognize unfavorable changes of CPPs during the production processes and to allow for early interventions in order to prevent losses of production batches due to quality issues. Process analytical technologies such as the dielectric spectroscopy or focused beam reflectance measurement (FBRM) are possible online monitoring tools, which can be applied to monitor cell growth as well as morphological changes. Since the dielectric spectroscopy only captures cells with intact cell membranes, even information about dead cells with ruptured or leaking cell membranes can be derived. The following chapter describes the application of dielectric spectroscopy on various virus-infected and non-infected cell lines with respect to adherent as well as suspension cultures in common stirred tank reactors. The adherent mammalian cell lines Vero (African green monkey kidney cells) and hMSC-TERT (telomerase-immortalized human mesenchymal stem cells) are thereby cultured on microcarrier, which provide the required growth surface and allow the cultivation of these cells even in dynamic culture systems. In turn, the insect-derived cell lines S2 and Sf21 are used as examples for cells typically cultured in suspension. Moreover, the FBRM technology as a further monitoring tool for cell culture applications has been included in this chapter using the example of Drosophila S2 insect cells.

Highly charged ion beams and their applications

NASA Astrophysics Data System (ADS)

Marler, Joan

2018-01-01

While much previous work with highly charged ions has been performed with the ions in the plasma state in which they were formed, beams of highly charged ions hold promise for exciting new experiments. Specifically low energy beams with a high degree of charge state purity are a prerequisite for momentum resolved cross section measurements and for efficient loading of highly charged ions into UHV traps for spectroscopy. The Clemson University facility is optimized for the delivery of such beams of highly charged ions with low kinetic energies. Near term experiments include energy resolved charge exchange with neutral targets.

Using RSpec in an introductory bright star spectroscopy lab activity

NASA Astrophysics Data System (ADS)

Howe, James; Sitar, David J.

2018-01-01

After presenting at the North Carolina Section of the American Association of Physics Teachers during the fall 2016 meeting, we were encouraged to turn our poster into a paper. This article describes the strengthening of a bright star spectroscopy lab activity for introductory astronomy lab students (AST1002) at Appalachian State University. Explanations of the tools and methods used in the activity are included, particularly the preparation of additional materials using RSpec and calibrated instrument response curves.

An actively Q-switched fiber laser with cylindrical vector beam generation

NASA Astrophysics Data System (ADS)

Zhang, Jiaojiao; Zhang, Zuxing; Cai, Yu; Wan, Hongdan; Wang, Zhiqiang; Zhang, Lin

2018-03-01

We demonstrate an actively Q-switched fiber laser with cylindrical vector beam (CVB) emission using a few-mode fiber Bragg grating as the mode selection component and an acousto-optic modulator to achieve Q-switching. To the best of our knowledge, this is the first such demonstration. Using a linear cavity configuration, an actively Q-switched CVB with a pulse width of about 64 ns, a pulse energy of 4.25 µJ and a repetition rate of 20 kHz has been obtained. Moreover, by tuning the polarization controllers radially and azimuthally, polarized Q-switched beams can be excited separately with a polarization purity of  >94.5%. This compact Q-switched fiber laser with ns CVB pulse output could find potential applications in the field of material processing, nonlinear optics and so on.

Cavity-locked ring down spectroscopy

DOEpatents

Zare, Richard N.; Paldus, Barbara A.; Harb, Charles C.; Spence, Thomas

2000-01-01

Distinct locking and sampling light beams are used in a cavity ring-down spectroscopy (CRDS) system to perform multiple ring-down measurements while the laser and ring-down cavity are continuously locked. The sampling and locking light beams have different frequencies, to ensure that the sampling and locking light are decoupled within the cavity. Preferably, the ring-down cavity is ring-shaped, the sampling light is s-polarized, and the locking light is p-polarized. Transmitted sampling light is used for ring-down measurements, while reflected locking light is used for locking in a Pound-Drever scheme.

Electron beam imaging and spectroscopy of plasmonic nanoantenna resonances

NASA Astrophysics Data System (ADS)

Vesseur, E. J. R.

2011-07-01

Nanoantennas are metal structures that provide strong optical coupling between a nanoscale volume and the far field. This coupling is mediated by surface plasmons, oscillations of the free electrons in the metal. Increasing the control over the resonant plasmonic field distribution opens up a wide range of applications of nanoantennas operating both in receiving and transmitting mode. This thesis presents how the dispersion and confinement of surface plasmons in nanoantennas are resolved and further engineered. Fabrication of nanostructures is done using focused ion beam milling (FIB) in metallic surfaces. We demonstrate that patterning in single-crystal substrates allows us to precisely control the geometry in which plasmons are confined. The nanoscale properties of the resonant plasmonic fields are resolved using a new technique developed in this thesis: angle- and polarization controlled cathodoluminescence (CL) imaging spectroscopy. The use of a tightly focused electron beam allows us to probe the optical antenna properties with deep subwavelength resolution. We show using this technique that nanoantennas consisting of 500-1200 nm long polycrystalline Au nanowires support standing plasmon waves. We directly observe the plasmon wavelengths which we use to derive the dispersion relation of guided nanowire plasmons. A 590-nm-long ridge-shaped nanoantenna was fabricated using FIB milling on a single-crystal Au substrate, demonstrating a level of control over the fabrication impossible with polycrystalline metals. CL experiments show that the ridge supports multiple-order resonances. The confinement of surface plasmons to the ridge is confirmed by boundary-element-method (BEM) calculations. The resonant modes in plasmonic whispering gallery cavities consisting of a FIB-fabricated circular groove are resolved. We find an excellent agreement between boundary element method calculations and the measured CL emission from the ring-shaped cavities. The calculations show

Analog detection for cavity lifetime spectroscopy

DOEpatents

Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

2001-05-15

An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

Analog detection for cavity lifetime spectroscopy

DOEpatents

Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

2003-01-01

An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

γ-ray spectroscopy of 209Tl

DOE PAGES

Amro, B. M. S.; Lister, C. J.; McCutchan, E. A.; ...

2017-01-30

Here, states in 209TI were populated using a multi-nucleon transfer reaction with a 136Xe beam impinging on a thick 208Pb target at E = 785 MeV. The beam was pulsed at 825 ns intervals in order to perform isomer decay spectroscopy. The known J π = 17/2 + isomer in 209TI was located at 1228(4) keV and measured to have a half-life of T 1/2 = 146(10) ns. A second isomer with J π = 13/2 + were found to have T 1/2 = 14(5) ns.

A suite of diagnostics to validate and optimize the prototype ITER neutral beam injector

NASA Astrophysics Data System (ADS)

Pasqualotto, R.; Agostini, M.; Barbisan, M.; Brombin, M.; Cavazzana, R.; Croci, G.; Dalla Palma, M.; Delogu, R. S.; De Muri, M.; Muraro, A.; Peruzzo, S.; Pimazzoni, A.; Pomaro, N.; Rebai, M.; Rizzolo, A.; Sartori, E.; Serianni, G.; Spagnolo, S.; Spolaore, M.; Tardocchi, M.; Zaniol, B.; Zaupa, M.

2017-10-01

The ITER project requires additional heating provided by two neutral beam injectors using 40 A negative deuterium ions accelerated at 1 MV. As the beam requirements have never been experimentally met, a test facility is under construction at Consorzio RFX, which hosts two experiments: SPIDER, full-size 100 kV ion source prototype, and MITICA, 1 MeV full-size ITER injector prototype. Since diagnostics in ITER injectors will be mainly limited to thermocouples, due to neutron and gamma radiation and to limited access, it is crucial to thoroughly investigate and characterize in more accessible experiments the key parameters of source plasma and beam, using several complementary diagnostics assisted by modelling. In SPIDER and MITICA the ion source parameters will be measured by optical emission spectroscopy, electrostatic probes, cavity ring down spectroscopy for H^- density and laser absorption spectroscopy for cesium density. Measurements over multiple lines-of-sight will provide the spatial distribution of the parameters over the source extension. The beam profile uniformity and its divergence are studied with beam emission spectroscopy, complemented by visible tomography and neutron imaging, which are novel techniques, while an instrumented calorimeter based on custom unidirectional carbon fiber composite tiles observed by infrared cameras will measure the beam footprint on short pulses with the highest spatial resolution. All heated components will be monitored with thermocouples: as these will likely be the only measurements available in ITER injectors, their capabilities will be investigated by comparison with other techniques. SPIDER and MITICA diagnostics are described in the present paper with a focus on their rationale, key solutions and most original and effective implementations.

The Young Astrophysicist: A Very Inexpensive Activity to Discuss Spectroscopy

ERIC Educational Resources Information Center

Brockington, Guilherme; Testoni, Leonardo André; Pietrocola, Maurício

2015-01-01

The continuing fascination of young people with celestial bodies leads them to pose challenging questions to their science teachers, such as how was the universe born? How were the stars formed? In this paper we present an extremely inexpensive but highly engaging activity to teach the basics of spectroscopy. Guided by the question "how do…

Proceedings of the 3rd US-Japan Workshop on Plasma Polarization Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beiersdorfer, P; Flyimoto, T

The third US-Japan Workshop on Plasma Polarization Spectroscopy was held at the Lawrence Livermore National Laboratory in Livermore, California, on June 18-21, 2001. The talks presented at this workshop are summarized in these proceedings. The papers cover both experimental investigation and applications of plasma polarization spectroscopy as well as the theoretical foundation and formalisms to understand and describe the polarization phenomena. The papers give an overview of the history of plasma polarization spectroscopy, derive the formal aspects of polarization spectroscopy, including the effects of electric and magnetic fields, discuss spectra perturbed by intense microwave fields, charge exchange, and dielectronic recombination,more » and present calculations of various collisional excitation and ionization cross sections and the modeling of plasma polarization spectroscopy phenomena. Experimental results are given from the WT-3 tokamak, the MST reverse field pinch, the Large Helical Device, the GAMMA 10 mirror machine, the Nevada Terrawatt Facility, the Livermore EBIT-II electron beam ion trap, and beam-foil spectroscopy. In addition, results were presented from studies of several laser-produced plasma experiments and new instrumental techniques were demonstrated.« less

Application Of Positron Beams For The Characterization Of Nano-scale Pores In Thin Films

NASA Astrophysics Data System (ADS)

Hirata, K.; Ito, K.; Kobayashi, Y.; Suzuki, R.; Ohdaira, T.; Eijt, S. W. H.; Schut, H.; van Veen, A.

2003-08-01

We applied three positron annihilation techniques, positron 3γ-annihilation spectroscopy, positron annihilation lifetime spectroscopy, and angular correlation of annihilation radiation, to the characterization of nano-scale pores in thin films by combining them with variable-energy positron beams. Characterization of pores in thin films is an important part of the research on various thin films of industrial importance. The results of our recent studies on pore characterization of thin films by positron beams will be reported here.

Working group report on beam plasmas, electronic propulsion, and active experiments using beams

NASA Technical Reports Server (NTRS)

Dawson, J. M.; Eastman, T.; Gabriel, S.; Hawkins, J.; Matossian, J.; Raitt, J.; Reeves, G.; Sasaki, S.; Szuszczewicz, E.; Winkler, J. R.

1986-01-01

The JPL Workshop addressed a number of plasma issues that bear on advanced spaceborne technology for the years 2000 and beyond. Primary interest was on the permanently manned space station with a focus on identifying environmentally related issues requiring early clarification by spaceborne plasma experimentation. The Beams Working Group focused on environmentally related threats that platform operations could have on the conduct and integrity of spaceborne beam experiments and vice versa. Considerations were to include particle beams and plumes. For purposes of definition it was agreed that the term particle beams described a directed flow of charged or neutral particles allowing single-particle trajectories to represent the characteristics of the beam and its propagation. On the other hand, the word plume was adopted to describe a multidimensional flow (or expansion) of a plasma or neutral gas cloud. Within the framework of these definitions, experiment categories included: (1) Neutral- and charged-particle beam propagation, with considerations extending to high powers and currents. (2) Evolution and dynamics of naturally occurring and man-made plasma and neutral gas clouds. In both categories, scientific interest focused on interactions with the ambient geoplasma and the evolution of particle densities, energy distribution functions, waves, and fields.

Efficient two-stage dual-beam noncollinear optical parametric amplifier

NASA Astrophysics Data System (ADS)

Cheng, Yu-Hsiang; Gao, Frank Y.; Poulin, Peter R.; Nelson, Keith A.

2018-06-01

We have constructed a noncollinear optical parametric amplifier with two signal beams amplified in the same nonlinear crystal. This dual-beam design is more energy-efficient than operating two amplifiers in parallel. The cross-talk between two beams has been characterized and discussed. We have also added a second amplification stage to enhance the output of one of the arms, which is then frequency-doubled for ultraviolet generation. This single device provides two tunable sources for ultrafast spectroscopy in the ultraviolet and visible region.

Gold nano-particle formation from crystalline AuCN: Comparison of thermal, plasma- and ion-beam activated decomposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beck, Mihály T.; Bertóti, Imre, E-mail: bertoti.imre@ttk.mta.hu; Mohai, Miklós

In this work, in addition to the conventional thermal process, two non-conventional ways, the plasma and ion beam activations are described for preparing gold nanoparticles from microcrystalline AuCN precursor. The phase formation at plasma and ion beam treatments was compared with that at thermal treatments and the products and transformations were characterized by thermogravimetry-mass-spectrometry (TG-MS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). TG-MS measurements in Ar atmosphere revealed that AuCN decomposition starts at 400 °C and completes at ≈700 °C with evolution of gaseous (CN){sub 2}. XPS and TEM show that in heat treatment at 450 °C formore » 1 h in Ar, loss of nitrogen and carbon occurs and small, 5–30 nm gold particles forms. Heating at 450 °C for 10 h in sealed ampoule, much larger, 60–200 nm size and well faceted Au particles develop together with a fibrous (CN){sub n} polymer phase, and the Au crystallites are covered by a 3–5 nm thick polymer shell. Low pressure Ar plasma treatment at 300 eV energy results in 4–20 nm size Au particles and removes most of the nitrogen and part of carbon. During Ar{sup +} ion bombardment with 2500 eV energy, 5–30 nm size Au crystallites form already in 10 min, with preferential loss of nitrogen and with increased amount of carbon residue. The results suggest that plasma and ion beam activation, acting similarly to thermal treatment, may be used to prepare Au nanoparticles from AuCN on selected surface areas either by depositing AuCN precursors on selected regions or by focusing the applied ionized radiation. Thus they may offer alternative ways for preparing tailor-made catalysts, electronic devices and sensors for different applications. - Graphical abstract: Proposed scheme of the decomposition mechanism of AuCN samples: heat treatment in Ar flow (a) and in sealed ampoule (b); Ar{sup +} ion treatment at 300 eV (c) and at 2500 eV (d). Cross section

Multi-aperture all-fiber active coherent beam combining for free-space optical communication receivers.

PubMed

Yang, Yan; Geng, Chao; Li, Feng; Huang, Guan; Li, Xinyang

2017-10-30

Multi-aperture receiver with optical combining architecture is an effective approach to overcome the turbulent atmosphere effect on the performance of the free-space optical (FSO) communications, in which how to combine the multiple laser beams received by the sub-apertures efficiently is one of the key technologies. In this paper, we focus on the combining module based on fiber couplers, and propose the all-fiber coherent beam combining (CBC) with two architectures by using active phase locking. To validate the feasibility of the proposed combining module, corresponding experiments and simulations on the CBC of four laser beams are carried out. The experimental results show that the phase differences among the input beams can be compensated and the combining efficiency can be stably promoted by active phase locking in CBC with both of the two architectures. The simulation results show that the combining efficiency fluctuates when turbulent atmosphere is considered, and the effectiveness of the combining module decreases as the turbulence increases. We believe that the combining module proposed in this paper has great potential, and the results can provide significant advices for researchers when building such a multi-aperture receiver with optical combining architecture for FSO commutation systems.

Positron beam studies of solids and surfaces: A summary

NASA Astrophysics Data System (ADS)

Coleman, P. G.

2006-02-01

A personal overview is given of the advances in positron beam studies of solids and surfaces presented at the 10th International Workshop on Positron Beams, held in Doha, Qatar, in March 2005. Solids studied include semiconductors, metals, alloys and insulators, as well as biophysical systems. Surface studies focussed on positron annihilation-induced Auger electron spectroscopy (PAES), but interesting applications of positron-surface interactions in fields as diverse as semiconductor technology and studies of the interstellar medium serve to illustrate once again the breadth of scientific endeavour covered by slow positron beam investigations.

Study on the effect of beam propagation through atmospheric turbulence on standoff nanosecond laser induced breakdown spectroscopy measurements.

PubMed

Laserna, J J; Reyes, R Fernández; González, R; Tobaria, L; Lucena, P

2009-06-08

We report on an experimental study of the effect of atmospheric turbulence on laser induced breakdown spectroscopy (LIBS) measurements. The characteristics of the atmosphere dictate specific performance constraints to this technology. Unlike classical laboratory LIBS systems where the distance to the sample is well known and characterized, LIBS systems working at several tens of meters to the target have specific atmospheric propagation conditions that cause the quality of the LIBS signals to be affected to a significant extent. Using a new LIBS based sensor system fitted with a nanosecond laser emitting at 1064 nm, propagation effects at distances of up to 120 m were investigated. The effects observed include wander and scintillation in the outgoing laser beam and in the return atomic emission signal. Plasmas were formed on aluminium targets. Average signal levels and signal fluctuations are measured so the effect of atmospheric turbulence on LIBS measurements is quantified.

In situ TEM Raman spectroscopy and laser-based materials modification.

PubMed

Allen, F I; Kim, E; Andresen, N C; Grigoropoulos, C P; Minor, A M

2017-07-01

We present a modular assembly that enables both in situ Raman spectroscopy and laser-based materials processing to be performed in a transmission electron microscope. The system comprises a lensed Raman probe mounted inside the microscope column in the specimen plane and a custom specimen holder with a vacuum feedthrough for a tapered optical fiber. The Raman probe incorporates both excitation and collection optics, and localized laser processing is performed using pulsed laser light delivered to the specimen via the tapered optical fiber. Precise positioning of the fiber is achieved using a nanomanipulation stage in combination with simultaneous electron-beam imaging of the tip-to-sample distance. Materials modification is monitored in real time by transmission electron microscopy. First results obtained using the assembly are presented for in situ pulsed laser ablation of MoS 2 combined with Raman spectroscopy, complimented by electron-beam diffraction and electron energy-loss spectroscopy. Copyright © 2016 Elsevier B.V. All rights reserved.

Engineering catalytic activity via ion beam bombardment of catalyst supports for vertically aligned carbon nanotube growth

NASA Astrophysics Data System (ADS)

Islam, A. E.; Nikolaev, P.; Amama, P. B.; Zakharov, D.; Sargent, G.; Saber, S.; Huffman, D.; Erford, M.; Semiatin, S. L.; Stach, E. A.; Maruyama, B.

2015-09-01

Carbon nanotube growth depends on the catalytic activity of metal nanoparticles on alumina or silica supports. The control on catalytic activity is generally achieved by variations in water concentration, carbon feed, and sample placement on a few types of alumina or silica catalyst supports obtained via thin film deposition. We have recently expanded the choice of catalyst supports by engineering inactive substrates like c-cut sapphire via ion beam bombardment. The deterministic control on the structure and chemistry of catalyst supports obtained by tuning the degree of beam-induced damage have enabled better regulation of the activity of Fe catalysts only in the ion beam bombarded areas and hence enabled controllable super growth of carbon nanotubes. A wide range of surface characterization techniques were used to monitor the catalytically active surface engineered via ion beam bombardment. The proposed method offers a versatile way to control carbon nanotube growth in patterned areas and also enhances the current understanding of the growth process. With the right choice of water concentration, carbon feed and sample placement, engineered catalyst supports may extend the carbon nanotube growth yield to a level that is even higher than the ones reported here, and thus offers promising applications of carbon nanotubes in electronics, heat exchanger, and energy storage.

Ultrafast two-dimensional lithium beam emission spectroscopy diagnostic on the EAST tokamak

NASA Astrophysics Data System (ADS)

Zoletnik, S.; Hu, G. H.; Tál, B.; Dunai, D.; Anda, G.; Asztalos, O.; Pokol, G. I.; Kálvin, S.; Németh, J.; Krizsanóczi, T.

2018-06-01

A diagnostic instrument is described for the Experimental Advanced Superconducting Tokamak (EAST) for the measurement of the edge plasma electron density profile and plasma turbulence properties. An accelerated neutral lithium beam is injected into the tokamak and the Doppler shifted 670.8 nm light emission of the Li2p-2s transition is detected. A novel compact setup is used, where the beam injection and observation take place from the same equatorial diagnostic port and radial-poloidal resolution is achieved with microsecond time resolution. The observation direction is optimized in order to achieve a sufficient Doppler shift of the beam light to be able to separate from the strong edge lithium line emission on this lithium coated device. A 250 kHz beam chopping technique is also demonstrated for the removal of background light. First results show the capability of measuring turbulence and its poloidal flow velocity in the scrape-off layer and edge region and the resolution of details of transient phenomena like edge localized modes with few microsecond time resolution.

Watching adsorption and electron beam induced decomposition on the model system Mo(CO)6/Cu(1 1 1) by X-ray absorption and photoemission spectroscopies

NASA Astrophysics Data System (ADS)

Paufert, Pierre; Fonda, Emiliano; Li, Zheshen; Domenichini, Bruno; Bourgeois, Sylvie

2013-11-01

An in-depth study of the first steps of electron beam assisted growth of Mo from molybdenum hexacarbonyl on Cu(1 1 1) has been carried out exploiting the complementarity of X-ray photoemission and X-ray absorption spectroscopies. Frank van der Merwe (2D) growth mode has been observed for the completion of the two first monolayers of adsorbed molecules through a simple physisorption process. Irradiation of the Mo(CO)6 deposit by 1 keV electron beam induces a modification of molybdenum coordination, the average number of C-neighbors decreasing from 6 to 3. Decomposed molecules remain on the surface after annealing at 520 K and organize themselves, the molybdenum atoms moving in Cu(1 1 1) surface fcc hollow sites. After annealing at 670 K, metallic molybdenum growth begins, if the total amount of adsorbed Mo atoms exceeds 1.2 monolayers.

Analysis of Chuanxiong Rhizoma and its active components by Fourier transform infrared spectroscopy combined with two-dimensional correlation infrared spectroscopy.

PubMed

Guo, Yizhen; Lv, Beiran; Wang, Jingjuan; Liu, Yang; Sun, Suqin; Xiao, Yao; Lu, Lina; Xiang, Li; Yang, Yanfang; Qu, Lei; Meng, Qinghong

2016-01-15

As complicated mixture systems, active components of Chuanxiong Rhizoma are very difficult to identify and discriminate. In this paper, the macroscopic IR fingerprint method including Fourier transform infrared spectroscopy (FT-IR), the second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2DCOS-IR), was applied to study and identify Chuanxiong raw materials and its different segmented production of HPD-100 macroporous resin. Chuanxiong Rhizoma is rich in sucrose. In the FT-IR spectra, water eluate is more similar to sucrose than the powder and the decoction. Their second derivative spectra amplified the differences and revealed the potentially characteristic IR absorption bands and combined with the correlation coefficient, concluding that 50% ethanol eluate had more ligustilide than other eluates. Finally, it can be found from 2DCOS-IR spectra that proteins were extracted by ethanol from Chuanxiong decoction by HPD-100 macroporous resin. It was demonstrated that the above three-step infrared spectroscopy could be applicable for quick, non-destructive and effective analysis and identification of very complicated and similar mixture systems of traditional Chinese medicines. Copyright © 2015 Elsevier B.V. All rights reserved.

Femtosecond MeV Electron Energy-Loss Spectroscopy

NASA Astrophysics Data System (ADS)

Li, R. K.; Wang, X. J.

2017-11-01

Pump-probe electron energy-loss spectroscopy (EELS) with femtosecond temporal resolution will be a transformative research tool for studying nonequilibrium chemistry and electronic dynamics of matter. In this paper, we propose a concept of femtosecond EELS utilizing mega-electron-volt electron beams from a radio-frequency (rf) photocathode source. The high acceleration gradient and high beam energy of the rf gun are critical to the generation of 10-fs electron beams, which enables an improvement of the temporal resolution by more than 1 order of magnitude beyond the state of the art. In our proposal, the "reference-beam technique" relaxes the energy stability requirement of the rf power source by roughly 2 orders of magnitude. The requirements for the electron-beam quality, photocathode, spectrometer, and detector are also discussed. Supported by particle-tracking simulations, we demonstrate the feasibility of achieving sub-electron-volt energy resolution and approximately 10-fs temporal resolution with existing or near-future hardware performance.

Laser-driven atomic-probe-beam diagnostics

NASA Astrophysics Data System (ADS)

Knyazev, B. A.; Greenly, J. B.; Hammer, D. A.

2000-12-01

A new laser-driven atomic-probe-beam diagnostic (LAD) is proposed for local, time-resolved measurements of electric field and ion dynamics in the accelerating gap of intense ion beam diodes. LAD adds new features to previous Stark-shift diagnostics which have been progressively developed in several laboratories, from passive observation of Stark effect on ion species or fast (charge-exchanged) neutrals present naturally in diodes, to active Stark atomic spectroscopy (ASAS) in which selected probe atoms were injected into the gap and excited to suitable states by resonant laser radiation. The LAD scheme is a further enhancement of ASAS in which the probe atoms are also used as a local (laser-ionized) ion source at an instant of time. Analysis of the ion energy and angular distribution after leaving the gap enables measurement, at the chosen ionization location in the gap, of both electrostatic potential and the development of ion divergence. Calculations show that all of these quantities can be measured with sub-mm and ns resolution. Using lithium or sodium probe atoms, fields from 0.1 to 10 MV/cm can be measured.

Noninvasive near-infrared topography of human brain activity using intensity modulation spectroscopy

NASA Astrophysics Data System (ADS)

Yamashita, Yuichi; Maki, Atsushi; Ito, Yoshitoshi; Watanabe, Eiju; Mayanagi, Yoshiaki; Koizumi, Hideaki

1996-04-01

We describe the functional topography of human brain activity due to motor stimulation by using near-infrared spectroscopy. Finger motion by each hand was used as the motor stimulation, and activity in the left fronto-central region of the brain was measured. A greater change in oxyhemoglobin concentration due to brain activity during the stimulation was obtained for the right hand than for the left hand. Localization of the activity was obtained by topographically mapping the measured changes for ten positions within the region.

Linear analysis of active-medium two-beam accelerator

NASA Astrophysics Data System (ADS)

Voin, Miron; Schächter, Levi

2015-07-01

We present detailed development of the linear theory of wakefield amplification by active medium and its possible application to a two-beam accelerator (TBA) is discussed. A relativistic train of triggering microbunches traveling along a vacuum channel in an active medium confined by a cylindrical waveguide excites Cherenkov wake in the medium. The wake is a superposition of azimuthally symmetric transverse magnetic modes propagating along a confining waveguide, with a phase velocity equal to the velocity of the triggering bunches. The structure may be designed in such a way that the frequency of one of the modes is close to active-medium resonant frequency, resulting in amplification of the former and domination of a single mode far behind the trigger bunches. Another electron bunch placed in proper phase with the amplified wakefield may be accelerated by the latter. Importantly, the energy for acceleration is provided by the active medium and not the drive bunch as in a traditional TBA. Based on a simplified model, we analyze extensively the impact of various parameters on the wakefield amplification process.

Three-beam double stimulated Raman scatterings: Cascading configuration

NASA Astrophysics Data System (ADS)

Rao, B. Jayachander; Cho, Minhaeng

2018-03-01

Two-beam stimulated Raman scattering (SRS) has been used in diverse label-free spectroscopy and imaging applications of live cells, biological tissues, and functional materials. Recently, we developed a theoretical framework for the three-beam double SRS processes that involve pump, Stokes, and depletion beams, where the pump-Stokes and pump-depletion SRS processes compete with each other. It was shown that the net Stokes gain signal can be suppressed by increasing the depletion beam intensity. The theoretical prediction has been experimentally confirmed recently. In the previous scheme for a selective suppression of one SRS by making it compete with another SRS, the two SRS processes occur in a parallel manner. However, there is another possibility of three-beam double SRS scheme that can be of use to suppress either Raman gain of the Stokes beam or Raman loss of the pump beam by depleting the Stokes photons with yet another SRS process induced by the pair of Stokes and another (second) Stokes beam. This three-beam double SRS process resembles a cascading energy transfer process from the pump beam to the first Stokes beam (SRS-1) and subsequently from the first Stokes beam to the second Stokes beam (SRS-2). Here, the two stimulated Raman gain-loss processes are associated with two different Raman-active vibrational modes of solute molecule. In the present theory, both the radiation and the molecules are treated quantum mechanically. We then show that the cascading-type three-beam double SRS can be described by coupled differential equations for the photon numbers of the pump and Stokes beams. From the approximate solutions as well as exact numerical calculation results for the coupled differential equations, a possibility of efficiently suppressing the stimulated Raman loss of the pump beam by increasing the second Stokes beam intensity is shown and discussed. To further prove a potential use of this scheme for developing a super-resolution SRS microscopy, we

High-Resolution, High-Throughput, Positive-Tone Patterning of Poly(ethylene glycol) by Helium Beam Exposure through Stencil Masks

PubMed Central

Cacao, Eliedonna E.; Nasrullah, Azeem; Sherlock, Tim; Kemper, Steven; Kourentzi, Katerina; Ruchhoeft, Paul; Stein, Gila E.; Willson, Richard C.

2013-01-01

In this work, a collimated helium beam was used to activate a thiol-poly(ethylene glycol) (SH-PEG) monolayer on gold to selectively capture proteins in the exposed regions. Protein patterns were formed at high throughput by exposing a stencil mask placed in proximity to the PEG-coated surface to a broad beam of helium particles, followed by incubation in a protein solution. Attenuated Total Reflectance–Fourier Transform Infrared Spectroscopy (ATR–FTIR) spectra showed that SH-PEG molecules remain attached to gold after exposure to beam doses of 1.5–60 µC/cm2 and incubation in PBS buffer for one hour, as evidenced by the presence of characteristic ether and methoxy peaks at 1120 cm−1 and 2870 cm−1, respectively. X-ray Photoelectron Spectroscopy (XPS) spectra showed that increasing beam doses destroy ether (C–O) bonds in PEG molecules as evidenced by the decrease in carbon C1s peak at 286.6 eV and increased alkyl (C–C) signal at 284.6 eV. XPS spectra also demonstrated protein capture on beam-exposed PEG regions through the appearance of a nitrogen N1s peak at 400 eV and carbon C1s peak at 288 eV binding energies, while the unexposed PEG areas remained protein-free. The characteristic activities of avidin and horseradish peroxidase were preserved after attachment on beam-exposed regions. Protein patterns created using a 35 µm mesh mask were visualized by localized formation of insoluble diformazan precipitates by alkaline phosphatase conversion of its substrate bromochloroindoyl phosphate-nitroblue tetrazolium (BCIP-NBT) and by avidin binding of biotinylated antibodies conjugated on 100 nm gold nanoparticles (AuNP). Patterns created using a mask with smaller 300 nm openings were detected by specific binding of 40 nm AuNP probes and by localized HRP-mediated deposition of silver nanoparticles. Corresponding BSA-passivated negative controls showed very few bound AuNP probes and little to no enzymatic formation of diformazan precipitates or silver

Method And System For Examining Biological Materials Using Low Power Cw Excitation Raman Spectroscopy.

DOEpatents

Alfano, Robert R.; Wang, Wubao

2003-05-06

A method and system for examining biological materials using low-power cw excitation Raman spectroscopy. A low-power continuous wave (cw) pump laser beam and a low-power cw Stokes (or anti-Stokes) probe laser beam simultaneously illuminate a biological material and traverse the biological material in collinearity. The pump beam, whose frequency is varied, is used to induce Raman emission from the biological material. The intensity of the probe beam, whose frequency is kept constant, is monitored as it leaves the biological material. When the difference between the pump and probe excitation frequencies is equal to a Raman vibrational mode frequency of the biological material, the weak probe signal becomes amplified by one or more orders of magnitude (typically up to about 10.sup.4 -10.sup.6) due to the Raman emission from the pump beam. In this manner, by monitoring the intensity of the probe beam emitted from the biological material as the pump beam is varied in frequency, one can obtain an excitation Raman spectrum for the biological material tested. The present invention may be applied to in the in vivo and/or in vitro diagnosis of diabetes, heart disease, hepatitis, cancers and other diseases by measuring the characteristic excitation Raman lines of blood glucose, cholesterol, serum glutamic oxalacetic transaminase (SGOT)/serum glutamic pyruvic transaminase (SGPT), tissues and other corresponding Raman-active body constituents, respectively.

Measurement of free radical kinetics in pulsed plasmas by UV and VUV absorption spectroscopy and by modulated beam mass spectrometry

NASA Astrophysics Data System (ADS)

Cunge, G.; Bodart, P.; Brihoum, M.; Boulard, F.; Chevolleau, T.; Sadeghi, N.

2012-04-01

This paper reviews recent progress in the development of time-resolved diagnostics to probe high-density pulsed plasma sources. We focus on time-resolved measurements of radicals' densities in the afterglow of pulsed discharges to provide useful information on production and loss mechanisms of free radicals. We show that broad-band absorption spectroscopy in the ultraviolet and vacuum ultraviolet spectral domain and threshold ionization modulated beam mass spectrometry are powerful techniques for the determination of the time variation of the radicals' densities in pulsed plasmas. The combination of these complementary techniques allows detection of most of the reactive species present in industrial etching plasmas, giving insights into the physico-chemistry reactions involving these species. As an example, we discuss briefly the radicals' kinetics in the afterglow of a SiCl4/Cl2/Ar discharge.

Tomographic Positron Annihilation Lifetime Spectroscopy

NASA Astrophysics Data System (ADS)

Wagner, A.; Anwand, W.; Butterling, M.; Fiedler, F.; Fritz, F.; Kempe, M.; Cowan, T. E.

2014-04-01

Positron annihilation lifetime spectroscopy serves as a perfect tool for studies of open-volume defects in solid materials such as vacancies, vacancy agglomerates, and dislocations. Moreover, structures in porous media can be investigated ranging from 0.3 nm to 30 nm employing the variation of the Positronium lifetime with the pore size. While lifetime measurements close to the material's surface can be performed at positron-beam installations bulk materials, fluids, bio-materials or composite structures cannot or only destructively accessed by positron beams. Targeting those problems, a new method of non-destructive positron annihilation lifetime spectroscopy has been developed which features even a 3-dimensional tomographic reconstruction of the spatial lifetime distribution. A beam of intense bremsstrahlung is provided by the superconducting electron linear accelerator ELBE (Electron Linear Accelerator with high Brilliance and low Emittance) at Helmholtz-Zentrum Dresden-Rossendorf. Since the generation of bremsstrahlung and the transport to the sample preserves the sharp timing of the electron beam, positrons generated inside the entire sample volume by pair production feature a sharp start time stamp for lifetime studies. In addition to the existing technique of in-situ production of positrons inside large (cm3) bulk samples using high-energy photons up to 16 MeV from bremsstrahlung production, granular position-sensitive photon detectors have been employed. The detector system will be described and results for experiments using samples with increasing complexity will be presented. The Lu2SiO5:Ce scintillation crystals allow resolving the total energy to 5.1 % (root-mean-square, RMS) and the annihilation lifetime to 225 ps (RMS). 3-dimensional annihilation lifetime maps have been created in an offline-analysis employing well-known techniques from PET.

Toward single mode, atomic size electron vortex beams.

PubMed

Krivanek, Ondrej L; Rusz, Jan; Idrobo, Juan-Carlos; Lovejoy, Tracy J; Dellby, Niklas

2014-06-01

We propose a practical method of producing a single mode electron vortex beam suitable for use in a scanning transmission electron microscope (STEM). The method involves using a holographic "fork" aperture to produce a row of beams of different orbital angular momenta, as is now well established, magnifying the row so that neighboring beams are separated by about 1 µm, selecting the desired beam with a narrow slit, and demagnifying the selected beam down to 1-2 Å in size. We show that the method can be implemented by adding two condenser lenses plus a selection slit to a straight-column cold-field emission STEM. It can also be carried out in an existing instrument, the monochromated Nion high-energy-resolution monochromated electron energy-loss spectroscopy-STEM, by using its monochromator in a novel way. We estimate that atom-sized vortex beams with ≥ 20 pA of current should be attainable at 100-200 keV in either instrument.

Actively coupled cavity ringdown spectroscopy with low-power broadband sources.

PubMed

Petermann, Christian; Fischer, Peer

2011-05-23

We demonstrate a coupling scheme for cavity enhanced absorption spectroscopy that makes use of an intracavity acousto-optical modulator to actively switch light into (and out of) a resonator. This allows cavity ringdown spectroscopy (CRDS) to be implemented with broadband nonlaser light sources with spectral power densities of less than 30μW/nm. Although the acousto-optical element reduces the ultimate detection limit by introducing additional losses, it permits absorptivities to be measured with a high dynamic range, especially in lossy environments. Absorption measurements for the forbidden transition of gaseous oxygen in air at ∼760nm are presented using a low-coherence cw-superluminescent diode. The same setup was electronically configured to cover absorption losses from 1.8×10^-8cm^-1 to 7.5% per roundtrip. This could be of interest in process analytical applications.

Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope.

PubMed

Li, Meng; Xu, Chunkai; Zhang, Panke; Li, Zhean; Chen, Xiangjun

2016-08-01

We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam.

Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Meng; Xu, Chunkai, E-mail: xuck@ustc.edu.cn, E-mail: xjun@ustc.edu.cn; Zhang, Panke

We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than themore » size of the incident electron beam.« less

Engineering catalytic activity via ion beam bombardment of catalyst supports for vertically aligned carbon nanotube growth

DOE PAGES

Islam, A. E.; Zakharov, D.; Stach, E. A.; ...

2015-09-16

Carbon nanotube growth depends on the catalytic activity of metal nanoparticles on alumina or silica supports. The control on catalytic activity is generally achieved by variations in water concentration, carbon feed, and sample placement on a few types of alumina or silica catalyst supports obtained via thin film deposition. We have recently expanded the choice of catalyst supports by engineering inactive substrates like c-cut sapphire via ion beam bombardment. The deterministic control on the structure and chemistry of catalyst supports obtained by tuning the degree of beam-induced damage have enabled better regulation of the activity of Fe catalysts only inmore » the ion beam bombarded areas and hence enabled controllable super growth of carbon nanotubes. A wide range of surface characterization techniques were used to monitor the catalytically active surface engineered via ion beam bombardment. The proposed method offers a versatile way to control carbon nanotube growth in patterned areas and also enhances the current understanding of the growth process. As a result, with the right choice of water concentration, carbon feed and sample placement, engineered catalyst supports may extend the carbon nanotube growth yield to a level that is even higher than the ones reported here, and thus offers promising applications of carbon nanotubes in electronics, heat exchanger, and energy storage.« less

Monolithic crystalline cladding microstructures for efficient light guiding and beam manipulation in passive and active regimes.

PubMed

Jia, Yuechen; Cheng, Chen; Vázquez de Aldana, Javier R; Castillo, Gabriel R; Rabes, Blanca del Rosal; Tan, Yang; Jaque, Daniel; Chen, Feng

2014-08-07

Miniature laser sources with on-demand beam features are desirable devices for a broad range of photonic applications. Lasing based on direct-pump of miniaturized waveguiding active structures offers a low-cost but intriguing solution for compact light-emitting devices. In this work, we demonstrate a novel family of three dimensional (3D) photonic microstructures monolithically integrated in a Nd:YAG laser crystal wafer. They are produced by the femtosecond laser writing, capable of simultaneous light waveguiding and beam manipulation. In these guiding systems, tailoring of laser modes by both passive/active beam splitting and ring-shaped transformation are achieved by an appropriate design of refractive index patterns. Integration of graphene thin-layer as saturable absorber in the 3D laser structures allows for efficient passive Q-switching of tailored laser radiations which may enable miniature waveguiding lasers for broader applications. Our results pave a way to construct complex integrated passive and active laser circuits in dielectric crystals by using femtosecond laser written monolithic photonic chips.

Status of the Beam Thermalization Area at the NSCL

NASA Astrophysics Data System (ADS)

Cooper, Kortney; Barquest, Bradley; Morrissey, David; Rodriguez, Jose Alberto; Schwarz, Stefan; Sumithrarachchi, Chandana; Kwarsick, Jeff; Savard, Guy

2013-10-01

Beam thermalization is a necessary process for the production of low-energy ion beams at projectile fragmentation facilities. Present beam thermalization techniques rely on passing high-energy ion beams through solid degraders followed by a gas cell where the remaining kinetic energy is dissipated through collisions with buffer gas atoms. Recently, the National Superconducting Cyclotron Laboratory (NSCL) upgraded its thermalization area with the implementation of new large acceptance beam lines and a large RF-gas catcher constructed by Argonne National Lab (ANL). Two high-energy beam lines were commissioned along with the installation and commissioning of this new device in late 2012. Low-energy radioactive ion beams have been successfully delivered to the Electron Beam Ion Trap (EBIT) charge breeder for the ReA3 reaccelerator, the SuN detector, the Low Energy Beam Ion Trap (LEBIT) penning trap, and the Beam Cooler and Laser Spectroscopy (BeCoLa) collinear laser beamline. Construction of a gas-filled reverse cyclotron dubbed the CycStopper is also underway. The status of the beam thermalization area will be presented and the overall efficiency of the system will be discussed.

Laser diagnostics of welding plasma by polarization spectroscopy.

PubMed

Lucas, Owen; Alwahabi, Zeyad T; Linton, Valerie; Meeuwissen, Karel

2007-05-01

The application of polarization spectroscopy (PS) to detect atomic species in an atmospheric pressure welding plasma has been demonstrated. PS spectra of Na atoms, seeded in the shielding gas flow of a gas tungsten arc welding (GTAW) plasma, are presented at different pump beam energies. The nature of the PS technique was found to be very efficient in suppressing the high background emission associated with the welding plasma. The PS spectral profiles appear to be Lorentzian and Lorentzian cubed for high and low pump beam energy, respectively. The effect of beam steering, due to the thermal gradient in the interaction plasma zone, was addressed. It was found that there is 2% unavoidable error in the detectable PS signal.

The ROSPHERE γ-ray spectroscopy array

NASA Astrophysics Data System (ADS)

Bucurescu, D.; Căta-Danil, I.; Ciocan, G.; Costache, C.; Deleanu, D.; Dima, R.; Filipescu, D.; Florea, N.; Ghiţă, D. G.; Glodariu, T.; Ivaşcu, M.; Lică, R.; Mărginean, N.; Mărginean, R.; Mihai, C.; Negret, A.; Niţă, C. R.; Olăcel, A.; Pascu, S.; Sava, T.; Stroe, L.; Şerban, A.; Şuvăilă, R.; Toma, S.; Zamfir, N. V.; Căta-Danil, G.; Gheorghe, I.; Mitu, I. O.; Suliman, G.; Ur, C. A.; Braunroth, T.; Dewald, A.; Fransen, C.; Bruce, A. M.; Podolyák, Zs.; Regan, P. H.; Roberts, O. J.

2016-11-01

The ROmanian array for SPectroscopy in HEavy ion REactions (ROSPHERE) has been designed as a multi-detector setup dedicated to γ-ray spectroscopy studies at the Bucharest 9 MV Tandem accelerator. Consisting of up to 25 detectors (either Compton suppressed HPGe detectors or fast LaBr3(Ce) scintillator detectors) together with a state of the art plunger device, ROSPHERE is a powerful tool for lifetime measurements using the Recoil Distance Doppler Shift (RDDS) and the in-beam Fast Electronic Scintillation Timing (FEST) methods. The array's geometry, detectors, electronics and data acquisition system are described. Selected results from the first experimental campaigns are also presented.

Nonlinear photothermal mid-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Totachawattana, Atcha; Erramilli, Shyamsunder; Sander, Michelle Y.

2016-10-01

Mid-infrared photothermal spectroscopy is a pump-probe technique for label-free and non-destructive sample characterization by targeting intrinsic vibrational modes. In this method, the mid-infrared pump beam excites a temperature-induced change in the refractive index of the sample. This laser-induced change in the refractive index is measured by a near-infrared probe laser using lock-in detection. At increased pump powers, emerging nonlinear phenomena not previously demonstrated in other mid-infrared techniques are observed. Nonlinear study of a 6 μm-thick 4-Octyl-4'-Cyanobiphenyl (8CB) liquid crystal sample is conducted by targeting the C=C stretching band at 1606 cm-1. At high pump powers, nonlinear signal enhancement and multiple pitchfork bifurcations of the spectral features are observed. An explanation of the nonlinear peak splitting is provided by the formation of bubbles in the sample at high pump powers. The discontinuous refractive index across the bubble interface results in a decrease in the forward scatter of the probe beam. This effect can be recorded as a bifurcation of the absorption peak in the photothermal spectrum. These nonlinear effects are not present in direct measurements of the mid-infrared beam. Evolution of the nonlinear photothermal spectrum of 8CB liquid crystal with increasing pump power shows enhancement of the absorption peak at 1606 cm-1. Multiple pitchfork bifurcations and spectral narrowing of the photothermal spectrum are demonstrated. This novel nonlinear regime presents potential for improved spectral resolution as well as a new regime for sample characterization in mid-infrared photothermal spectroscopy.

Measurement of activation of helium gas by 238U beam irradiation at about 11 A MeV

NASA Astrophysics Data System (ADS)

Akashio, A.; Tanaka, K.; Imao, H.; Uwamino, Y.

2017-09-01

A new helium-gas stripper system has been applied at the 11 A MeV uranium beam of the Radioactive Isotope Beam Factory of the RIKEN accelerator facility. Although the gas stripper is important for the heavy-ion accelerator facility, the residual radiation that is generated is a serious problem for maintenance work. The residual dose was evaluated by using three-layered activation samples of aluminium and bismuth. The γ-rays from produced radionuclides with in-flight fission of the 238U beam and from the material of the chamber activated by neutrons were observed by using a Ge detector and compared with the values calculated by using the Monte-Carlo simulation code PHITS.

Laser optogalvanic spectroscopy of molecules

NASA Technical Reports Server (NTRS)

Webster, C. R.; Rettner, C. T.

1983-01-01

In laser optogalvanic (LOG) spectroscopy, a tunable laser is used to probe the spectral characteristics of atomic or molecular species within an electrical discharge in a low pressure gas. Optogalvanic signals arise when the impedance of the discharge changes in response to the absorption of laser radiation. The technique may, therefore, be referred to as impedance spectroscopy. This change in impedance may be monitored as a change in the voltage across the discharge tube. LOG spectra are recorded by scanning the wavelength of a chopped CW dye laser while monitoring the discharge voltage with a lock-in amplifier. LOG signals are obtained if the laser wavelength matches a transition in a species present in the discharge (or flame), and if the absorption of energy in the laser beam alters the impedance of the discharge. Infrared LOG spectroscopy of molecules has been demonstrated and may prove to be the most productive application in the field of optogalvanic techniques.

Structure-Activity Relations In Enzymes: An Application Of IR-ATR Modulation Spectroscopy

NASA Astrophysics Data System (ADS)

Fringeli, Urs P.; Ahlstrom, Peter; Vincenz, Claudius; Fringeli, Marianna

1985-12-01

Relations between structure and specific activity in immobilized acetylcholinesterase (ACNE) have been studied by means of pH- and Ca++-modulation technique combined with attenuated total reflection (ATR) infrared (IR) spectroscopy and enzyme activity measurement. Periodic modulation of pH and Ca++-concentration enabled a periodic on-off switching of about 40% of the total enzyme activity. It was found that about 0.5 to 1% of the amino acids were involved in this process. These 15 to 30 amino acids assumed antiparallel pleated sheet structure in the inhibited state and random and/or helical structure in the activated state.

Method And System For Examining Biological Materials Using Low Power Cw Excitation Raman Spectroscopy.

DOEpatents

Alfano, Robert R.; Wang, Wubao

2000-11-21

A method and system for examining biological materials using low-power cw excitation Raman spectroscopy. In accordance with the teachings of the invention, a low-power continuous wave (cw) pump laser beam and a low-power cw Stokes (or anti-Stokes) probe laser beam simultaneously illuminate a biological material and traverse the biological material in collinearity. The pump beam, whose frequency is varied, is used to induce Raman emission from the biological material. The intensity of the probe beam, whose frequency is kept constant, is monitored as it leaves the biological material. When the difference between the pump and probe excitation frequencies is equal to a Raman vibrational mode frequency of the biological material, the weak probe signal becomes amplified by one or more orders of magnitude (typically up to about 10.sup.4 -10.sup.6) due to the Raman emission from the pump beam. In this manner, by monitoring the intensity of the probe beam emitted from the biological material as the pump beam is varied in frequency, one can obtain an excitation Raman spectrum for the biological material tested. The present invention may be applied to in the in vivo and/or in vitro diagnosis of diabetes, heart disease, hepatitis, cancers and other diseases by measuring the characteristic excitation Raman lines of blood glucose, cholesterol, serum glutamic oxalacetic transaminase (SGOT)/serum glutamic pyruvic tansaminase (SGPT), tissues and other corresponding Raman-active body constituents, respectively. For example, it may also be used to diagnose diseases associated with the concentration of Raman-active constituents in urine, lymph and saliva It may be used to identify cancer in the breast, cervix, uterus, ovaries and the like by measuring the fingerprint excitation Raman spectra of these tissues. It may also be used to reveal the growing of tumors or cancers by measuring the levels of nitric oxide in tissue.

Multiplex coherent raman spectroscopy detector and method

NASA Technical Reports Server (NTRS)

Joyner, Candace C. (Inventor); Patrick, Sheena T. (Inventor); Chen, Peter (Inventor); Guyer, Dean R. (Inventor)

2004-01-01

A multiplex coherent Raman spectrometer (10) and spectroscopy method rapidly detects and identifies individual components of a chemical mixture separated by a separation technique, such as gas chromatography. The spectrometer (10) and method accurately identify a variety of compounds because they produce the entire gas phase vibrational Raman spectrum of the unknown gas. This is accomplished by tilting a Raman cell (20) to produce a high-intensity, backward-stimulated, coherent Raman beam of 683 nm, which drives a degenerate optical parametric oscillator (28) to produce a broadband beam of 1100-1700 nm covering a range of more than 3000 wavenumber. This broadband beam is combined with a narrowband beam of 532 nm having a bandwidth of 0.003 wavenumbers and focused into a heated windowless cell (38) that receives gases separated by a gas chromatograph (40). The Raman radiation scattered from these gases is filtered and sent to a monochromator (50) with multichannel detection.

Multiplex coherent raman spectroscopy detector and method

DOEpatents

Chen, Peter; Joyner, Candace C.; Patrick, Sheena T.; Guyer, Dean R.

2004-06-08

A multiplex coherent Raman spectrometer (10) and spectroscopy method rapidly detects and identifies individual components of a chemical mixture separated by a separation technique, such as gas chromatography. The spectrometer (10) and method accurately identify a variety of compounds because they produce the entire gas phase vibrational Raman spectrum of the unknown gas. This is accomplished by tilting a Raman cell (20) to produce a high-intensity, backward-stimulated, coherent Raman beam of 683 nm, which drives a degenerate optical parametric oscillator (28) to produce a broadband beam of 1100-1700 nm covering a range of more than 3000 wavenumber. This broadband beam is combined with a narrowband beam of 532 nm having a bandwidth of 0.003 wavenumbers and focused into a heated windowless cell (38) that receives gases separated by a gas chromatograph (40). The Raman radiation scattered from these gases is filtered and sent to a monochromator (50) with multichannel detection.

Femtosecond MeV Electron Energy-Loss Spectroscopy

DOE PAGES

Li, R. K.; Wang, X. J.

2017-11-09

Pump-probe electron energy-loss spectroscopy (EELS) with femtosecond temporal resolution will be a transformative research tool for studying nonequilibrium chemistry and electronic dynamics of matter. Here in this article, we propose a concept of femtosecond EELS utilizing mega-electron-volt electron beams from a radio-frequency (rf) photocathode source. The high acceleration gradient and high beam energy of the rf gun are critical to the generation of 10-fs electron beams, which enables an improvement of the temporal resolution by more than 1 order of magnitude beyond the state of the art. In our proposal, the “referencebeam technique” relaxes the energy stability requirement of themore » rf power source by roughly 2 orders of magnitude. The requirements for the electron-beam quality, photocathode, spectrometer, and detector are also discussed. Supported by particle-tracking simulations, we demonstrate the feasibility of achieving subelectron- volt energy resolution and approximately 10-fs temporal resolution with existing or near-future hardware performance.« less

Femtosecond MeV Electron Energy-Loss Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, R. K.; Wang, X. J.

Pump-probe electron energy-loss spectroscopy (EELS) with femtosecond temporal resolution will be a transformative research tool for studying nonequilibrium chemistry and electronic dynamics of matter. Here in this article, we propose a concept of femtosecond EELS utilizing mega-electron-volt electron beams from a radio-frequency (rf) photocathode source. The high acceleration gradient and high beam energy of the rf gun are critical to the generation of 10-fs electron beams, which enables an improvement of the temporal resolution by more than 1 order of magnitude beyond the state of the art. In our proposal, the “referencebeam technique” relaxes the energy stability requirement of themore » rf power source by roughly 2 orders of magnitude. The requirements for the electron-beam quality, photocathode, spectrometer, and detector are also discussed. Supported by particle-tracking simulations, we demonstrate the feasibility of achieving subelectron- volt energy resolution and approximately 10-fs temporal resolution with existing or near-future hardware performance.« less

High resolution in-beam γ-ray spectroscopy

NASA Astrophysics Data System (ADS)

Kern, J.; Dousse, J.-Cl.; Gasser, M.; Perny, B.; Rhême, Ch.

1985-01-01

An in-beam curved crystal facility has been installed at the SIN variable energy cyclotron. Using the (110) planes of a 3.0 mm thick quartz lamina bent at 3.15 m, diffraction peaks typically 6 arcsec wide (FWHM) are obtained. The energy resolution is thus, for instance, 110 eV at 170 keV in 3rd order. Due to a sophisticated detector system and heavy shielding, the sensitivity of the instrument is quite good. The facility proves quite useful in (p,xnγ) reaction studies whenever the γ-ray spectrum is very complex, e.g. in the study of odd-odd deformed nuclei. Complicated multiplets appearing in the 176Yb(p,3nγ)174Lu spectrum could be successfully resolved. From the results we derive that the g-factors of the 142 d, Jπ=6- isomer, take anomalous values.

Physics opportunities with meson beams

DOE PAGES

Briscoe, William J.; Doring, Michael; Haberzettl, Helmut; ...

2015-10-20

Over the past two decades, meson photo- and electro-production data of unprecedented quality and quantity have been measured at electromagnetic facilities worldwide. By contrast, the meson-beam data for the same hadronic final states are mostly outdated and largely of poor quality, or even nonexistent, and thus provide inadequate input to help interpret, analyze, and exploit the full potential of the new electromagnetic data. To reap the full benefit of the high-precision electromagnetic data, new high-statistics data from measurements with meson beams, with good angle and energy coverage for a wide range of reactions, are critically needed to advance our knowledgemore » in baryon and meson spectroscopy and other related areas of hadron physics. To address this situation, a state of-the-art meson-beam facility needs to be constructed. Furthermore, the present paper summarizes unresolved issues in hadron physics and outlines the vast opportunities and advances that only become possible with such a facility.« less

Physics opportunities with meson beams

NASA Astrophysics Data System (ADS)

Briscoe, William J.; Döring, Michael; Haberzettl, Helmut; Manley, D. Mark; Naruki, Megumi; Strakovsky, Igor I.; Swanson, Eric S.

2015-10-01

Over the past two decades, meson photo- and electroproduction data of unprecedented quality and quantity have been measured at electromagnetic facilities worldwide. By contrast, the meson-beam data for the same hadronic final states are mostly outdated and largely of poor quality, or even non-existent, and thus provide inadequate input to help interpret, analyze, and exploit the full potential of the new electromagnetic data. To reap the full benefit of the high-precision electromagnetic data, new high-statistics data from measurements with meson beams, with good angle and energy coverage for a wide range of reactions, are critically needed to advance our knowledge in baryon and meson spectroscopy and other related areas of hadron physics. To address this situation, a state-of-the-art meson-beam facility needs to be constructed. The present paper summarizes unresolved issues in hadron physics and outlines the vast opportunities and advances that only become possible with such a facility.

Inferring deep-brain activity from cortical activity using functional near-infrared spectroscopy

PubMed Central

Liu, Ning; Cui, Xu; Bryant, Daniel M.; Glover, Gary H.; Reiss, Allan L.

2015-01-01

Functional near-infrared spectroscopy (fNIRS) is an increasingly popular technology for studying brain function because it is non-invasive, non-irradiating and relatively inexpensive. Further, fNIRS potentially allows measurement of hemodynamic activity with high temporal resolution (milliseconds) and in naturalistic settings. However, in comparison with other imaging modalities, namely fMRI, fNIRS has a significant drawback: limited sensitivity to hemodynamic changes in deep-brain regions. To overcome this limitation, we developed a computational method to infer deep-brain activity using fNIRS measurements of cortical activity. Using simultaneous fNIRS and fMRI, we measured brain activity in 17 participants as they completed three cognitive tasks. A support vector regression (SVR) learning algorithm was used to predict activity in twelve deep-brain regions using information from surface fNIRS measurements. We compared these predictions against actual fMRI-measured activity using Pearson’s correlation to quantify prediction performance. To provide a benchmark for comparison, we also used fMRI measurements of cortical activity to infer deep-brain activity. When using fMRI-measured activity from the entire cortex, we were able to predict deep-brain activity in the fusiform cortex with an average correlation coefficient of 0.80 and in all deep-brain regions with an average correlation coefficient of 0.67. The top 15% of predictions using fNIRS signal achieved an accuracy of 0.7. To our knowledge, this study is the first to investigate the feasibility of using cortical activity to infer deep-brain activity. This new method has the potential to extend fNIRS applications in cognitive and clinical neuroscience research. PMID:25798327

Determination of the composition of HgCdTe oxide films by neutron activation analysis

NASA Astrophysics Data System (ADS)

Gnade, B.; Simmons, A.; Little, D.; Strong, R.

1987-04-01

The composition of HgCdTe oxides grown by anodic oxidation in a standard KOH/ethylene glycol solution has been determined by neutron activation analysis (NAA). This technique is not hindered by the difficulties normally associated with methods using ion beams or electron beams. Neutron activation analysis has the advantage of being quantitative, and also NAA is not affected by the chemical composition of the matrix. The analysis of the KOH/ethylene glycol oxide film by neutron activation yields Hg:Cd:Te ratios of 0.534:0.19:1, in close agreement with Rutherford backscattering spectroscopy analysis (R.L. Strong et al., J. Vac. Sci. Technol. A4 (4) (1986) 1992).

Nanocrystalline SnO2 formation using energetic ion beam.

PubMed

Mohanty, T; Batra, Y; Tripathi, A; Kanjilal, D

2007-06-01

Nanocrystalline tin oxide (SnO2) thin films grown by RF magnetron sputtering technique were characterized by UV-Visible absorption spectroscopy and Photoluminescence spectroscopy. From atomic force microscopic (AFM) and Glancing angle X-ray diffraction (GAXRD) measurements, the radius of grains was found to be approximately 6+/-2 nm. The thin films were bombarded with 250 keV Xe2+ ion beam to observe the stability of nanophases against radiation. For ion bombarded films, optical absorption band edge is shifted towards red region. Atomic force microscopy studies show that the radius of the grains was increased to approximately 8 +/- 1 nm and the grains were nearly uniform in size. The size of the grains has been reduced after ion bombardment in the case of films grown on Si. During this process, defects such as vacancies, voids were generated in the films as well as in the substrates. Ion bombardment induces local temperature increase of thin films causing melting of films. Ion beam induced defects enhances the diffusion of atoms leading to uniformity in size of grains. The role of matrix on ion beam induced grain growth is discussed.

Monolithic crystalline cladding microstructures for efficient light guiding and beam manipulation in passive and active regimes

PubMed Central

Jia, Yuechen; Cheng, Chen; Vázquez de Aldana, Javier R.; Castillo, Gabriel R.; Rabes, Blanca del Rosal; Tan, Yang; Jaque, Daniel; Chen, Feng

2014-01-01

Miniature laser sources with on-demand beam features are desirable devices for a broad range of photonic applications. Lasing based on direct-pump of miniaturized waveguiding active structures offers a low-cost but intriguing solution for compact light-emitting devices. In this work, we demonstrate a novel family of three dimensional (3D) photonic microstructures monolithically integrated in a Nd:YAG laser crystal wafer. They are produced by the femtosecond laser writing, capable of simultaneous light waveguiding and beam manipulation. In these guiding systems, tailoring of laser modes by both passive/active beam splitting and ring-shaped transformation are achieved by an appropriate design of refractive index patterns. Integration of graphene thin-layer as saturable absorber in the 3D laser structures allows for efficient passive Q-switching of tailored laser radiations which may enable miniature waveguiding lasers for broader applications. Our results pave a way to construct complex integrated passive and active laser circuits in dielectric crystals by using femtosecond laser written monolithic photonic chips. PMID:25100561

Characterization of cross-section correction to charge exchange recombination spectroscopy rotation measurements using co- and counter-neutral-beam views.

PubMed

Solomon, W M; Burrell, K H; Feder, R; Nagy, A; Gohil, P; Groebner, R J

2008-10-01

Measurements of rotation using charge exchange recombination spectroscopy can be affected by the energy dependence of the charge exchange cross section. On DIII-D, the associated correction to the rotation can exceed 100 kms at high temperatures. In reactor-relevant low rotation conditions, the correction can be several times larger than the actual plasma rotation and therefore must be carefully validated. New chords have been added to the DIII-D CER diagnostic to view the counter-neutral-beam line. The addition of these views allows determination of the toroidal rotation without depending on detailed atomic physics calculations, while also allowing experimental characterization of the atomic physics. A database of rotation comparisons from the two views shows that the calculated cross-section correction can adequately describe the measurements, although there is a tendency for "overcorrection." In cases where accuracy better than about 15% is desired, relying on calculation of the cross-section correction may be insufficient.

A versatile and reconfigurable setup for all-terahertz time-resolved pump-probe spectroscopy.

PubMed

Elezzabi, A Y; Maraghechi, P

2012-05-01

A versatile optical setup for all-terahertz (THz) time resolved pump-probe spectroscopy was designed and tested. By utilizing a dual THz pulse generator emitter module, independent and synchronized THz radiation pump and probe pulses were produced, thus eliminating the need for THz beam splitters and the limitations associated with their implementation. The current THz setup allows for precise control of the electric fields splitting ratio between the THz radiation pump and probe pulses, as well as in-phase, out-of-phase, and polarization dependent pump-probe spectroscopy. Since the present THz pump-probe setup does not require specialized THz radiation optical components, such as phase shifters, polarization rotators, or wide bandwidth beam splitters, it can be easily implemented with minimal alterations to a conventional THz time domain spectroscopy system. The present setup is valuable for studying the time dynamics of THz coherent phenomena in solid-state, chemical, and biological systems.

High active nitrogen flux growth of GaN by plasma assisted molecular beam epitaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

McSkimming, Brian M., E-mail: mcskimming@engineering.ucsb.edu; Speck, James S.; Chaix, Catherine

2015-09-15

In the present study, the authors report on a modified Riber radio frequency (RF) nitrogen plasma source that provides active nitrogen fluxes more than 30 times higher than those commonly used for plasma assisted molecular beam epitaxy (PAMBE) growth of gallium nitride (GaN) and thus a significantly higher growth rate than has been previously reported. GaN films were grown using N{sub 2} gas flow rates between 5 and 25 sccm while varying the plasma source's RF forward power from 200 to 600 W. The highest growth rate, and therefore the highest active nitrogen flux, achieved was ∼7.6 μm/h. For optimized growth conditions,more » the surfaces displayed a clear step-terrace structure with an average RMS roughness (3 × 3 μm) on the order of 1 nm. Secondary ion mass spectroscopy impurity analysis demonstrates oxygen and hydrogen incorporation of 1 × 10{sup 16} and ∼5 × 10{sup 17}, respectively. In addition, the authors have achieved PAMBE growth of GaN at a substrate temperature more than 150 °C greater than our standard Ga rich GaN growth regime and ∼100 °C greater than any previously reported PAMBE growth of GaN. This growth temperature corresponds to GaN decomposition in vacuum of more than 20 nm/min; a regime previously unattainable with conventional nitrogen plasma sources. Arrhenius analysis of the decomposition rate shows that samples with a flux ratio below stoichiometry have an activation energy greater than decomposition of GaN in vacuum while samples grown at or above stoichiometry have decreased activation energy. The activation energy of decomposition for GaN in vacuum was previously determined to be ∼3.1 eV. For a Ga/N flux ratio of ∼1.5, this activation energy was found to be ∼2.8 eV, while for a Ga/N flux ratio of ∼0.5, it was found to be ∼7.9 eV.« less

Carbon ions beam therapy monitoring with the INSIDE in-beam PET.

PubMed

Pennazio, Francesco; Battistoni, Giuseppe; Bisogni, Maria Giuseppina; Camarlinghi, Niccolò; Ferrari, Alfredo; Ferrero, Veronica; Fiorina, Elisa; Morrocchi, Matteo; Sala, Paola R; Sportelli, Giancarlo; Wheadon, Richard; Cerello, Piergiorgio

2018-06-06

In-vivo range monitoring techniques are necessary in order to fully take advantage of the high dose gradients deliverable in hadrontherapy treatments. Positron Emission Tomography (PET) scanners can be used to monitor beam-induced activation in tissues and hence measure the range. The INSIDE (Innovative Solutions for In-beam DosimEtry in Hadrontherapy) in-beam PET scanner, installed at the Italian National Center of Oncological Hadrontherapy (CNAO, Pavia, Italy) synchrotron facility, has already been successfully tested in-vivo during a proton therapy treatment. We discuss here the system performance evaluation with carbon ion beams, in view of future in-vivo tests. The work is focused on the analysis of activity images obtained with therapeutic treatments delivered to polymethyl methacrylate (PMMA) phantoms, as well as on the test of an innovative and robust Monte Carlo simulation technique for the production of reliable prior activity maps. Images are reconstructed using different integration intervals, so as to monitor the activity evolution during and after the treatment. Three procedures to compare activity images are presented, namely Pearson Correlation Coefficient, Beam's Eye View and Overall View. Images of repeated irradiations of the same treatments are compared to assess the integration time necessary to provide reproducible images. The range agreement between simulated and experimental images is also evaluated, so as to validate the simulation capability to provide sound prior information. The results indicate that at treatment end, or at most 20 s afterwards, the range measurement is reliable within 1-2 mm, when comparing both different experimental sessions and data with simulations. In conclusion, this work shows that the INSIDE in-beam PET scanner performance is promising towards its in-vivo test with carbon ions. © 2018 Institute of Physics and Engineering in Medicine.

Active vibration control of a thin walled beam by neural networks and piezo-actuators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lecce, L.; Sorrentino, A.; Concilio, A.

1994-12-31

In turboprop aircraft, vibration of the fuselage frame (typically a thin-walled beam) has been identified as the main cause of interior noise. Passive methods, based essentially on the use of DVA (Dynamic Vibration Absorbers) have been shown to be not entirely satisfactory, due to the significant weight increase. The use of active control systems based on piezoceramic sensors and actuators integrated into the frame seems to be a valid alternative to attenuate interior noise. In this paper, the use of a MIMO feedforward active control system with piezoceramic actuators is proposed, in order to reduce the vertical vibration levels ofmore » a rectified, typical fuselage frame. A numerical FEM model of the rectified frame has been experimentally validated and has been used in order to evaluate the dynamic response of the beam, both with regard to piezoceramic actuators and to a point force, representing the primary disturbance. A neural network (NN) controller has been used to simultaneously compute amplitudes and phases of the control force for the 6 piezo actuators, so as to minimize the accelerometric responses acquired in 30 points of the beam (6 at each of 5 different transversal sections).« less

Auger electron spectroscopy, secondary ion mass spectroscopy and optical characterization of a-C-H and BN films

NASA Technical Reports Server (NTRS)

Pouch, J. J.; Alterovitz, S. A.; Warner, J. D.

1986-01-01

The amorphous dielectrics a-C:H and BN were deposited on III-V semiconductors. Optical band gaps as high as 3 eV were measured for a-C:H generated by C4H10 plasmas; a comparison was made with bad gaps obtained from films prepared by CH4 glow discharges. The ion beam deposited BN films exhibited amorphous behavior with band gaps on the order of 5 eV. Film compositions were studied by Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The optical properties were characterized by ellipsometry, UV/VIS absorption, and IR reflection and transmission. Etching rates of a-C:H subjected to O2 dicharges were determined.

A high-resolution Fourier Transform Spectrometer for planetary spectroscopy

NASA Technical Reports Server (NTRS)

Cruikshank, D. P.; Sinton, W. M.

1973-01-01

The employment of a high-resolution Fourier Transform Spectrometer (FTS) is described for planetary and other astronomical spectroscopy in conjunction with the 88-inch telescope at Mauna Kea Observatory. The FTS system is designed for a broad range of uses, including double-beam laboratory spectroscopy, infrared gas chromatography, and nuclear magnetic resonance spectroscopy. The data system is well-suited to astronomical applications because of its great speed in acquiring and transforming data, and because of the enormous storage capability of the magnetic tape unit supplied with the system. The basic instrument is outlined 2nd some of the initial results from the first attempted use on the Mauna Kea 88-inch telescope are reported.

Application of terahertz spectroscopy for characterization of biologically active organic molecules in natural environment

NASA Astrophysics Data System (ADS)

Karaliūnas, Mindaugas; Jakštas, Vytautas; Nasser, Kinan E.; Venckevičius, Rimvydas; Urbanowicz, Andrzej; Kašalynas, Irmantas; Valušis, Gintaras

2016-09-01

In this work, a comparative research of biologically active organic molecules in its natural environment using the terahertz (THz) time domain spectroscopy (TDS) and Fourier transform spectroscopy (FTS) systems is carried out. Absorption coefficient and refractive index of Nicotiana tabacum L. leaves containing nicotine, Cannabis sativa L. leaves containing tetrahydrocannabinol, and Humulu lupulus L. leaves containing α-acids, active organic molecules that obtain in natural environment, were measured in broad frequency range from 0.1 to 13 THz at room temperature. In the spectra of absorption coefficient the features were found to be unique for N. tabacum, C. sativa and H. lupulus. Moreover, those features can be exploited for identification of C. sativa sex and N. tabacum origin. The refractive index can be also used to characterize different species.

Photodissociation dynamics of the methyl perthiyl radical at 248 and 193 nm using fast-beam photofragment translational spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrison, Aaron W.; Ryazanov, Mikhail; Sullivan, Erin N.

2016-07-14

The photodissociation dynamics of the methyl perthiyl radical (CH{sub 3}SS) have been investigated using fast-beam coincidence translational spectroscopy. Methyl perthiyl radicals were produced by photodetachment of the CH{sub 3}SS{sup −} anion followed by photodissociation at 248 nm (5.0 eV) and 193 nm (6.4 eV). Photofragment mass distributions and translational energy distributions were measured at each dissociation wavelength. Experimental results show S atom loss as the dominant (96%) dissociation channel at 248 nm with a near parallel, anisotropic angular distribution and translational energy peaking near the maximal energy available to ground state CH{sub 3}S and S fragments, indicating that the dissociationmore » occurs along a repulsive excited state. At 193 nm, S atom loss remains the major fragmentation channel, although S{sub 2} loss becomes more competitive and constitutes 32% of the fragmentation. The translational energy distributions for both channels are very broad at this wavelength, suggesting the formation of the S{sub 2} and S atom products in several excited electronic states.« less

Fast crystallization of amorphous Gd{sub 2}Zr{sub 2}O{sub 7} induced by thermally activated electron-beam irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Zhangyi; Qi, Jianqi, E-mail: qijianqi@scu.edu.cn; Zhou, Li

2015-12-07

We investigate the ionization and displacement effects of an electron-beam (e-beam) on amorphous Gd{sub 2}Zr{sub 2}O{sub 7} synthesized by the co-precipitation and calcination methods. The as-received amorphous specimens were irradiated under electron beams at different energies (80 keV, 120 keV, and 2 MeV) and then characterized by X-ray diffraction and transmission electron microscopy. A metastable fluorite phase was observed in nanocrystalline Gd{sub 2}Zr{sub 2}O{sub 7} and is proposed to arise from the relatively lower surface and interface energy compared with the pyrochlore phase. Fast crystallization could be induced by 120 keV e-beam irradiation (beam current = 0.47 mA/cm{sup 2}). The crystallization occurred on the nanoscale upon ionizationmore » irradiation at 400 °C after a dose of less than 10{sup 17} electrons/cm{sup 2}. Under e-beam irradiation, the activation energy for the grain growth process was approximately 10 kJ/mol, but the activation energy was 135 kJ/mol by calcination in a furnace. The thermally activated ionization process was considered the fast crystallization mechanism.« less

In-air RBS measurements at the LAMFI external beam setup

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silva, T. F.; Added, N.; Moro, M. V.

2014-11-11

This work describes new developments in the external beam setup of the Laboratory of Material Analysis with Ion Beams of the University of São Paulo (LAMFI-USP). This setup was designed to be a versatile analytical station to analyze a broad range of samples. In recent developments, we seek the external beam Rutherford Backscattering Spectroscopy (RBS) analysis to complement the Particle Induced X-ray Emission (PIXE) measurements. This work presents the initial results of the external beam RBS analysis as well as recent developments to improve the energy resolution RBS measurements, in particular tests to seek for sources of resolution degradation. Thesemore » aspects are discussed and preliminary results of in-air RBS analysis of some test samples are presented.« less

Modeling activities on the negative-ion-based Neutral Beam Injectors of the Large Helical Device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agostinetti, P.; Antoni, V.; Chitarin, G.

2011-09-26

At the National Institute for Fusion Science (NIFS) large-scaled negative ion sources have been widely used for the Neutral Beam Injectors (NBIs) mounted on the Large Helical Device (LHD), which is the world-largest superconducting helical system. These injectors have achieved outstanding performances in terms of beam energy, negative-ion current and optics, and represent a reference for the development of heating and current drive NBIs for ITER.In the framework of the support activities for the ITER NBIs, the PRIMA test facility, which includes a RF-drive ion source with 100 keV accelerator (SPIDER) and a complete 1 MeV Neutral Beam system (MITICA)more » is under construction at Consorzio RFX in Padova.An experimental validation of the codes has been undertaken in order to prove the accuracy of the simulations and the soundness of the SPIDER and MITICA design. To this purpose, the whole set of codes have been applied to the LHD NBIs in a joint activity between Consorzio RFX and NIFS, with the goal of comparing and benchmarking the codes with the experimental data. A description of these modeling activities and a discussion of the main results obtained are reported in this paper.« less

Beam profile for the Herschel-SPIRE Fourier transform spectrometer.

PubMed

Makiwa, Gibion; Naylor, David A; Ferlet, Marc; Salji, Carl; Swinyard, Bruce; Polehampton, Edward; van der Wiel, Matthijs H D

2013-06-01

One of the instruments on board the Herschel Space Observatory is the Spectral and Photometric Imaging Receiver (SPIRE). SPIRE employs a Fourier transform spectrometer with feed-horn-coupled bolometers to provide imaging spectroscopy. To interpret the resultant spectral images requires knowledge of the wavelength-dependent beam, which in the case of SPIRE is complicated by the use of multimoded feed horns. In this paper we describe a series of observations and the analysis conducted to determine the wavelength dependence of the SPIRE spectrometer beam profile.

Hollow Electron Beam Collimation for HL-LHC - Effects on the Beam Core

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fitterer, M.; Stancari, G.; Valishev, A.

2017-06-13

Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the High Luminosity Large Hadron Collider (HL-LHC). To ensure the successful operation of the hollow beam collimator the unwanted effects on the beam core, which might arise from the operation with a pulsed electron beam, must be minimized. This paper gives a summary of the effect of hollow electron lenses on the beam core in terms of sources, provides estimates for HL-LHC and discusses the possible mitigation methods.

Structural properties of rutile TiO2 nanoparticles accumulated in a model of gastrointestinal epithelium elucidated by micro-beam x-ray absorption fine structure spectroscopy

NASA Astrophysics Data System (ADS)

Veronesi, G.; Brun, E.; Fayard, B.; Cotte, M.; Carrière, M.

2012-05-01

Micro-beam x-ray absorption fine structure spectroscopy was used to investigate rutile TiO2 nanoparticles internalized into gastrointestinal cells during their crossing of a gut model barrier. Nanoparticles diluted in culture medium tend to accumulate in cells after 48 h exposure; however, no spectral differences arise between particles in cellular and in acellular environments, as corroborated by quantitative analysis. This finding establishes that no modification of the lattice properties of the nanoparticles occurs upon interaction with the barrier. These measurements demonstrate the possibility of interrogating nanoparticles in situ within cells, suggesting a way to investigate their fate when incorporated in biological hosts.

Remote adjustable focus Raman spectroscopy probe

DOEpatents

Schmucker, John E.; Blasi, Raymond J.; Archer, William B.

1999-01-01

A remote adjustable focus Raman spectroscopy probe allows for analyzing Raman scattered light from a point of interest external probe. An environmental barrier including at least one window separates the probe from the point of interest. An optical tube is disposed adjacent to the environmental barrier and includes a long working length compound lens objective next to the window. A beam splitter and a mirror are at the other end. A mechanical means is used to translated the prove body in the X, Y, and Z directions resulting in a variable focus optical apparatus. Laser light is reflected by the beam splitter and directed toward the compound lens objective, then through the window and focused on the point of interest. Raman scattered light is then collected by the compound lens objective and directed through the beam splitter to a mirror. A device for analyzing the light, such as a monochrometer, is coupled to the mirror.

Buffer Gas Cooled Molecule Source for Cpmmw Spectroscopy

NASA Astrophysics Data System (ADS)

Zhou, Yan; Grimes, David; Barnum, Timothy J.; Klein, Ethan; Field, Robert W.

2014-06-01

We have built a new molecular beam source that implements 20 K Neon buffer gas cooling for the study of the spectra of small molecules. In particular, laser ablation of BaF2 pellets has been optimized to produce a molecular beam of BaF with a number density more than 100 times greater than what we have previously obtained from a typical Smalley-type photoablation supersonic beam source. Moreover, the forward beam velocity of 150 m/s in our apparatus represents an approximate 10-fold reduction, improving spectroscopic resolution from 500 kHz to better than 50 kHz at 100 GHz in a chirped-pulse millimeter-wave experiment in which resolution is limited by Doppler broadening. Novel improvements in our buffer gas source and advantages for CPmmW spectroscopy studies will be discussed. We thank David Patterson, John Barry, John Doyle, and David DeMille for help in the design of our source.

Matrix isolation sublimation: An apparatus for producing cryogenic beams of atoms and molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sacramento, R. L.; Alves, B. X.; Silva, B. A.

2015-07-15

We describe the apparatus to generate cryogenic beams of atoms and molecules based on matrix isolation sublimation. Isolation matrices of Ne and H{sub 2} are hosts for atomic and molecular species which are sublimated into vacuum at cryogenic temperatures. The resulting cryogenic beams are used for high-resolution laser spectroscopy. The technique also aims at loading atomic and molecular traps.

New opportunities in quasi elastic neutron scattering spectroscopy

NASA Astrophysics Data System (ADS)

Mezei, F.; Russina, M.

2001-07-01

The high energy resolution usually required in quasi elastic neutron scattering (QENS) spectroscopy is commonly achieved by the use of cold neutrons. This is one of the important research areas where the majority of current work is done on instruments on continuous reactor sources. One particular reason for this is the capability of continuous source time-of-flight spectrometers to use instrumental parameters optimally adapted for best data collection efficiency in each experiment. These parameters include the pulse repetition rate and the length of the pulses to achieve optimal balance between resolution and intensity. In addition, the disc chopper systems used provide perfect symmetrical line shapes with no tails and low background. Recent development of a set of novel techniques enhance the efficiency of cold neutron spectroscopy on existing and future spallation sources in a dramatic fashion. These techniques involve the use of extended pulse length, high intensity coupled moderators, disc chopper systems and advanced neutron optical beam delivery, and they will enable Lujan center at Los Alamos to surpass the best existing reactor instruments in time-of-flight QENS work by more than on order of magnitude in terms of beam flux on the sample. Other applications of the same techniques will allow us to combine advantages of backscattering spectroscopy on continuous and pulsed sources in order to deliver μeV resolution in a very broad energy transfer range.

Supersonic Molecular Beam Optical Stark Spectroscopy of MnH.

NASA Astrophysics Data System (ADS)

Gengler, Jamie; Ma, Tongmei; Harrison, Jeremy; Steimle, Timothy

2006-03-01

The large moment of inertia, large magnetic moment, and possible large permanent electric dipole moment of manganese monohydride, MnH, makes it a prime candidate for ultra-cold molecule production via Stark deceleration and magnetic trapping. Here we report the first molecular beam production of MnH and the analysis of the Stark effect in the (0,0) A^7 π -- X^ 7σ^+ band. The sample was prepared by laser ablation of solid Mn in an H2 supersonic expansion. The low rotational temperature (<50 K) and near natural linewidth resolution (˜50 MHz) facilitated analysis of the ^55Mn (I=5/2) and ^1H (I=1/2) hyperfine structure. A comparison of the derived field-free parameters with those obtained from sub- Doppler optical measurements will be made. Progress on the analysis of the Stark effect will be given. J.R. Bochinski, E.R. Hudson, H.J. Lewandowski, and J. Ye, Phys. Rev. A 70, 043410 (2004). S.Y.T. van de Meerakker, R.T. Jongma, H.L. Bethlem, and G. Meijer, Phys. Rev. A 64, 041401(R) (2001) report the first molecular beam production of MnH and the analysis of T.D. Varberg, J.A. Gray, R.W. Field, and A.J. Merer, J. Mol. Spec. 156, 296-318 (1992). I.E. Gordon, D.R.T. Appadoo, A. Shayesteh, K.A. Walker, and P.F. Bernath, J. Mol. Spec., 229, 145-149 (2005).

Measurement of key resonances for the 24Al(p ,γ )25Si reaction rate using in-beam γ -ray spectroscopy

NASA Astrophysics Data System (ADS)

Longfellow, B.; Gade, A.; Brown, B. A.; Richter, W. A.; Bazin, D.; Bender, P. C.; Bowry, M.; Elman, B.; Lunderberg, E.; Weisshaar, D.; Williams, S. J.

2018-05-01

Energy levels and branching ratios for the rp-process nucleus 25Si were determined from the reactions 9Be(26Si,25Si)X and 9Be(25Al,25Si)X using in-beam γ -ray spectroscopy with both high-efficiency and high-resolution detector arrays. Proton-unbound states at 3695(14) and 3802(11) keV were identified and assigned tentative spins and parities based on comparison to theory and the mirror nucleus. The 24Al(p ,γ )25Si reaction rate was calculated using the experimental states and states from charge-dependent USDA and USDB shell-model calculations with downward shifts of the 1 s1 /2 proton orbital to account for the observed Thomas-Ehrman shift, leading to a factor of 10-100 increase in rate for the temperature region of 0.22 GK as compared to a previous calculation. These shifts may be applicable to neighboring nuclei, impacting the proton capture rates in this region of the chart.

An Initial Study of the Injection of an Intense Relativistic Electron Beam into the Atmosphere.

DTIC Science & Technology

1981-03-04

resolved spectroscopy , thermoluminescent x-ray detectors ( TLDs ), and Schlieren photography. The freely propagating electron beam produced a luminous region...atmosphere and its detection with a TLD ...................................... 17 VIII. REFERENCES...atmospheric even though such stu- dies have application in a number of important areas of research including electron beam sustained lasers , 9 inertial

Method and system for near-field spectroscopy using targeted deposition of nanoparticles

NASA Technical Reports Server (NTRS)

Anderson, Mark S. (Inventor)

2012-01-01

There is provided in one embodiment of the invention a method for analyzing a sample material using surface enhanced spectroscopy. The method comprises the steps of imaging the sample material with an atomic force microscope (AFM) to select an area of interest for analysis, depositing nanoparticles onto the area of interest with an AFM tip, illuminating the deposited nanoparticles with a spectrometer excitation beam, and disengaging the AFM tip and acquiring a localized surface enhanced spectrum. The method may further comprise the step of using the AFM tip to modulate the spectrometer excitation beam above the deposited nanoparticles to obtain improved sensitivity data and higher spatial resolution data from the sample material. The invention further comprises in one embodiment a system for analyzing a sample material using surface enhanced spectroscopy.

Vibrational spectroscopy in the electron microscope.

PubMed

Krivanek, Ondrej L; Lovejoy, Tracy C; Dellby, Niklas; Aoki, Toshihiro; Carpenter, R W; Rez, Peter; Soignard, Emmanuel; Zhu, Jiangtao; Batson, Philip E; Lagos, Maureen J; Egerton, Ray F; Crozier, Peter A

2014-10-09

Vibrational spectroscopies using infrared radiation, Raman scattering, neutrons, low-energy electrons and inelastic electron tunnelling are powerful techniques that can analyse bonding arrangements, identify chemical compounds and probe many other important properties of materials. The spatial resolution of these spectroscopies is typically one micrometre or more, although it can reach a few tens of nanometres or even a few ångströms when enhanced by the presence of a sharp metallic tip. If vibrational spectroscopy could be combined with the spatial resolution and flexibility of the transmission electron microscope, it would open up the study of vibrational modes in many different types of nanostructures. Unfortunately, the energy resolution of electron energy loss spectroscopy performed in the electron microscope has until now been too poor to allow such a combination. Recent developments that have improved the attainable energy resolution of electron energy loss spectroscopy in a scanning transmission electron microscope to around ten millielectronvolts now allow vibrational spectroscopy to be carried out in the electron microscope. Here we describe the innovations responsible for the progress, and present examples of applications in inorganic and organic materials, including the detection of hydrogen. We also demonstrate that the vibrational signal has both high- and low-spatial-resolution components, that the first component can be used to map vibrational features at nanometre-level resolution, and that the second component can be used for analysis carried out with the beam positioned just outside the sample--that is, for 'aloof' spectroscopy that largely avoids radiation damage.

Indirect absorption spectroscopy using quantum cascade lasers: mid-infrared refractometry and photothermal spectroscopy.

PubMed

Pfeifer, Marcel; Ruf, Alexander; Fischer, Peer

2013-11-04

We record vibrational spectra with two indirect schemes that depend on the real part of the index of refraction: mid-infrared refractometry and photothermal spectroscopy. In the former, a quantum cascade laser (QCL) spot is imaged to determine the angles of total internal reflection, which yields the absorption line via a beam profile analysis. In the photothermal measurements, a tunable QCL excites vibrational resonances of a molecular monolayer, which heats the surrounding medium and changes its refractive index. This is observed with a probe laser in the visible. Sub-monolayer sensitivities are demonstrated.

Effect of Electron Beam Irradiation on Structural and Optical Properties of Cu-Doped In2O3 Films Prepared by RF Magnetron Sputtering

NASA Astrophysics Data System (ADS)

Krishnan, R. Reshmi; Sanjeev, Ganesh; Prabhu, Radhakrishna; Pillai, V. P. Mahadevan

2018-02-01

Undoped and Cu-doped In2O3 films were prepared by radiofrequency magnetron sputtering technique. The effects of Cu doping and high-energy electron beam irradiation on the structural and optical properties of as-prepared films were investigated using techniques such as x-ray diffraction, x-ray photoelectron spectroscopy (XPS), lateral scanning electron microscopic image analysis, energy-dispersive x-ray (EDX) spectroscopy, micro-Raman, and ultraviolet-visible (UV-vis) spectroscopy. Moderate doping of Cu in In2O3 enhanced the intensity of (222) peak, indicating alignment of crystalline grains along <111>. Electron beam irradiation promoted orientation of crystalline grains along <111> in undoped and moderately Cu-doped films. EDX spectroscopic and XPS analyses revealed incorporation of Cu2+ ions in the lattice. The transmittance of Cu-doped films decreased with e-beam irradiation. Systematic reduction of the bandgap energy with increase in Cu doping concentration was seen in unirradiated and electron-beam-irradiated films.

Effects of beam irregularity on uniform scanning

NASA Astrophysics Data System (ADS)

Kim, Chang Hyeuk; Jang, Sea duk; Yang, Tae-Keun

2016-09-01

An active scanning beam delivery method has many advantages in particle beam applications. For the beam is to be successfully delivered to the target volume by using the active scanning technique, the dose uniformity must be considered and should be at least 2.5% in the case of therapy application. During beam irradiation, many beam parameters affect the 2-dimensional uniformity at the target layer. A basic assumption in the beam irradiation planning stage is that the shape of the beam is symmetric and follows a Gaussian distribution. In this study, a pure Gaussian-shaped beam distribution was distorted by adding parasitic Gaussian distribution. An appropriate uniform scanning condition was deduced by using a quantitative analysis based on the gamma value of the distorted beam and 2-dimensional uniformities.

Deep levels in H-irradiated GaAs1-xNx (x < 0.01) grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Shafi, M.; Mari, R. H.; Khatab, A.; Henini, M.; Polimeni, A.; Capizzi, M.; Hopkinson, M.

2011-12-01

Dilute nitride GaAs1-xNx layers have been grown by molecular beam epitaxy with nitrogen concentration ranging from 0.2% to 0.8%. These samples have been studied before and after hydrogen irradiation by using standard deep level transient spectroscopy (DLTS) and high resolution Laplace DLTS techniques. The activation energy, capture cross section and density of the electron traps have been estimated and compared with results obtained in N-free as-grown and H-irradiated bulk GaAs.

Fan Beam Emission Tomography for Laminar Fires

NASA Technical Reports Server (NTRS)

Sivathanu, Yudaya; Lim, Jongmook; Feikema, Douglas

2003-01-01

Obtaining information on the instantaneous structure of turbulent and transient flames is important in a wide variety of applications such as fire safety, pollution reduction, flame spread studies, and model validation. Durao et al. has reviewed the different methods of obtaining structure information in reacting flows. These include Tunable Laser Absorption Spectroscopy, Fourier Transform Infrared Spectroscopy, and Emission Spectroscopy to mention a few. Most flames emit significant radiation signatures that are used in various applications such as fire detection, light-off detection, flame diagnostics, etc. Radiation signatures can be utilized to maximum advantage for determining structural information in turbulent flows. Emission spectroscopy is most advantageous in the infrared regions of the spectra, principally because these emission lines arise from transitions in the fundamental bands of stable species such as CO2 and H2O. Based on the above, the objective of this work was to develop a fan beam emission tomography system to obtain the local scalar properties such as temperature and mole fractions of major gas species from path integrated multi-wavelength infrared radiation measurements.

Semi-active control of a sandwich beam partially filled with magnetorheological elastomer

NASA Astrophysics Data System (ADS)

Dyniewicz, Bartłomiej; Bajkowski, Jacek M.; Bajer, Czesław I.

2015-08-01

The paper deals with the semi-active control of vibrations of structural elements. Elastomer composites with ferromagnetic particles that act as magnetorheological fluids are used. The damping coefficient and the shear modulus of the elastomer increases when it is exposed to an electro-magnetic field. The control of this process in time allows us to reduce vibrations more effectively than if the elastomer is permanently exposed to a magnetic field. First the analytical solution for the vibrations of a sandwich beam filled with an elastomer is given. Then the control problem is defined and applied to the analytical formula. The numerical solution of the minimization problem results in a periodic, perfectly rectangular control function if free vibrations are considered. Such a temporarily acting magnetic field is more efficient than a constantly acting one. The surplus reaches 20-50% or more, depending on the filling ratio of the elastomer. The resulting control was verified experimentally in the vibrations of a cantilever sandwich beam. The proposed semi-active control can be directly applied to engineering vibrating structural elements, for example helicopter rotors, aircraft wings, pads under machines, and vehicles.

Bigelow Expandable Activity Module (BEAM) - ISS Inflatable Module Technology Demonstration

NASA Technical Reports Server (NTRS)

Dasgupta, Rajib; Munday, Steve; Valle, Gerard D.

2014-01-01

INNOVATION: BEAM is a pathway project demonstrating the design, fabrication, test, certification, integration, operation, on-orbit performance, and disposal of the first ever man-rated space inflatable structure. The groundwork laid through the BEAM project will support developing and launching a larger inflatable space structure with even greater mass per volume (M/V) advantages need for longer space missions. OVERVIEW: Inflatable structures have been shown to have much lower mass per volume ratios (M/V) when compared with conventional space structures. BEAM is an expandable structure, launched in a packed state, and then expanded once on orbit. It is a temporary experimental module to be used for gathering structural, thermal, and radiation data while on orbit. BEAM will be launched on Space X-8, be extracted from the dragon trunk, and will attach to ISS at Node 3- Aft. BEAM performance will be monitored over a two-year period and then BEAM will be jettison using the SSRMS.

Bigelow BEAM Contract

NASA Image and Video Library

2013-01-16

NASA Deputy Administrator Lori Garver and President and founder of Bigelow Aerospace Robert T. Bigelow talk while standing next to the Bigelow Expandable Activity Module (BEAM) during a media briefing where is was announced that the BEAM expandable space habitat technology will be tested on the International Space Station, Wednesday, Jan. 16, 2013 in Las Vegas. BEAM is scheduled to arrive at the space station in 2015 for a two-year technology demonstration. Photo Credit: (NASA/Bill Ingalls)

Bigelow BEAM Contract

NASA Image and Video Library

2013-01-16

NASA Deputy Administrator Lori Garver and President and founder of Bigelow Aerospace Robert T. Bigelow talk while standing next to the Bigelow Expandable Activity Module (BEAM) during a media briefing where it is was announced that the BEAM expandable space habitat technology will be tested on the International Space Station, Wednesday, Jan. 16, 2013 in Las Vegas. BEAM is scheduled to arrive at the space station in 2015 for a two-year technology demonstration. Photo Credit: (NASA/Bill Ingalls)

Absolute ozone densities in a radio-frequency driven atmospheric pressure plasma using two-beam UV-LED absorption spectroscopy and numerical simulations

NASA Astrophysics Data System (ADS)

Wijaikhum, A.; Schröder, D.; Schröter, S.; Gibson, A. R.; Niemi, K.; Friderich, J.; Greb, A.; Schulz-von der Gathen, V.; O'Connell, D.; Gans, T.

2017-11-01

The efficient generation of reactive oxygen species (ROS) in cold atmospheric pressure plasma jets (APPJs) is an increasingly important topic, e.g. for the treatment of temperature sensitive biological samples in the field of plasma medicine. A 13.56 MHz radio-frequency (rf) driven APPJ device operated with helium feed gas and small admixtures of oxygen (up to 1%), generating a homogeneous glow-mode plasma at low gas temperatures, was investigated. Absolute densities of ozone, one of the most prominent ROS, were measured across the 11 mm wide discharge channel by means of broadband absorption spectroscopy using the Hartley band centred at λ = 255 nm. A two-beam setup with a reference beam in Mach-Zehnder configuration is employed for improved signal-to-noise ratio allowing high-sensitivity measurements in the investigated single-pass weak-absorbance regime. The results are correlated to gas temperature measurements, deduced from the rotational temperature of the N2 (C 3 {{{\\Pi }}}u+ \\to B 3 {{{\\Pi }}}g+, υ = 0 \\to 2) optical emission from introduced air impurities. The observed opposing trends of both quantities as a function of rf power input and oxygen admixture are analysed and explained in terms of a zero-dimensional plasma-chemical kinetics simulation. It is found that the gas temperature as well as the densities of O and O2(b{}1{{{Σ }}}g+) influence the absolute O3 densities when the rf power is varied.

Admittance spectroscopy or deep level transient spectroscopy: A contrasting juxtaposition

NASA Astrophysics Data System (ADS)

Bollmann, Joachim; Venter, Andre

2018-04-01

A comprehensive understanding of defects in semiconductors remains of primary importance. In this paper the effectiveness of two of the most commonly used semiconductor defect spectroscopy techniques, viz. deep level transient spectroscopy (DLTS) and admittance spectroscopy (AS) are reviewed. The analysis of defects present in commercially available SiC diodes shows that admittance spectroscopy allows the identification of deep traps with reduced measurement effort compared to deep Level Transient Spectroscopy (DLTS). Besides the N-donor, well-studied intrinsic defects were detected in these diodes. Determination of their activation energy and defect density, using the two techniques, confirm that the sensitivity of AS is comparable to that of DLTS while, due to its well defined peak shape, the spectroscopic resolution is superior. Additionally, admittance spectroscopy can analyze faster emission processes which make the study of shallow defects more practical and even that of shallow dopant levels, possible. A comparative summary for the relevant spectroscopic features of the two capacitance methods are presented.

Feasibility of Raman spectroscopy as PAT tool in active coating.

PubMed

Müller, Joshua; Knop, Klaus; Thies, Jochen; Uerpmann, Carsten; Kleinebudde, Peter

2010-02-01

Active coating is a specific application of film coating where the active ingredient is comprised in the coating layer. This implementation is a challenging operation regarding the achievement of desired amount of coating and coating uniformity. To guarantee the quality of such dosage forms it is desirable to develop a tool that is able to monitor the coating operation and detect the end of the process. Coating experiments were performed at which the model drug diprophylline is coated in a pan coater on placebo tablets and tablets containing the active ingredient itself. During the active coating Raman spectra were recorded in-line. The spectral measurements were correlated with the average weight gain and the amount of coated active ingredient at each time point. The developed chemometric model was tested by monitoring further coated batches. Furthermore, the effects of pan rotation speed and working distance on the acquired Raman signal and, hence, resulting effect of the chemometric model were examined. Besides coating on placebo cores it was possible to determine the amount of active ingredient in the film when coated onto cores containing the same active ingredient. In addition, the method is even applicable when varying the process parameters and measurement conditions within a restricted range. Raman spectroscopy is an appropriate process analytical technology too.

β-decay spectroscopy for the r-process nucleosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishimura, Shunji; Collaboration: RIBF Decay Collaborations

2014-05-09

Series of decay spectroscopy experiments, utilizing of high-purity Ge detectors and double-sided silicon-strip detectors, have been conducted to harvest the decay properties of very exotic nuclei relevant to the r-process nucleosynthesis at the RIBF. The decay properties such as β-decay half-lives, low-lying states, β-delayed neutron emissions, isomeric states, and possibly Q{sub β} of the very neutron-rich nuclei are to be measured to give significant constraints in the uncertainties of nuclear properties for the r-process nucleosynthesis. Recent results of βγ spectroscopy study using in-flight fission of {sup 238}U-beam will be presented together with our future perspectives.

In-beam γ-ray Spectroscopy of {sup 30}P via the {sup 28}Si({sup 3}He,pγ){sup 30}P Reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mcneice, E.; Setoodehnia, K.; Singh, B., E-mail: ndgroup@mcmaster.ca

2014-06-15

The level structure of {sup 30}P up to 8.25 MeV was investigated via in-beam γ-ray spectroscopy using the {sup 28}Si({sup 3}He,pγ){sup 30}P reaction at 9 MeV at the University of Tsukuba Tandem Accelerator Complex in Japan. An energy level scheme was deduced from γ-γ coincidence measurements. 47 new transitions have been observed from the previously known states (mostly resonances), thereby reducing the uncertainties in the excitation energies of 17 states from 3 to 10 keV to values of < 1 keV. Furthermore, spin assignments based on measurements of γ-ray angular distributions and γ-γ directional correlation of oriented nuclei (DCO ratios)more » were made for several observed levels of {sup 30}P.« less

Synthesis of nanocrystalline ZnO thin films by electron beam evaporation

NASA Astrophysics Data System (ADS)

Kondkar, V.; Rukade, D.; Bhattacharyya, V.

2018-05-01

Nanocrystalline ZnO thin films have potential for applications in variety of optoelectronic devices. In the present study, nanocrystalline thin films of ZnO are grown on fused silica substrate using electron beam (e-beam) evaporation technique. Phase identification is carried out using Glancing angle X-ray diffraction (GAXRD) and Raman spectroscopy. Ultraviolet-Visible (UV-Vis) spectroscopic analysis is carried out to calculate energy band gap of the ZnO film. Surface morphology of the film is investigated using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). Highly quality nanocrystalline thin films of hexagonal wurtzite ZnO are synthesized using e-beam evaporation technique.

Chemical and Structural Stability of Lithium-Ion Battery Electrode Materials under Electron Beam

DOE PAGES

Lin, Feng; Markus, Isaac M.; Doeff, Marca M.; ...

2014-07-16

Our investigation of chemical and structural dynamics in battery materials is essential to elucidation of structure-property relationships for rational design of advanced battery materials. Spatially resolved techniques, such as scanning/transmission electron microscopy (S/TEM), are widely applied to address this challenge. But, battery materials are susceptible to electron beam damage, complicating the data interpretation. In this study, we demonstrate that, under electron beam irradiation, the surface and bulk of battery materials undergo chemical and structural evolution equivalent to that observed during charge-discharge cycling. In a lithiated NiO nanosheet, a Li2CO3-containing surface reaction layer (SRL) was gradually decomposed during electron energy loss spectroscopy (EELS) acquisition. For cycled LiNi 0.4Mn 0.4Co 0.18Ti 0.02O 2 particles, repeated electron beam irradiation induced a phase transition from an Rmore » $$\\bar{3}$$m layered structure to an rock-salt structure, which is attributed to the stoichiometric lithium and oxygen removal from R$$\\bar{3}$$m 3a and 6c sites, respectively. Nevertheless, it is still feasible to preserve pristine chemical environments by minimizing electron beam damage, for example, in using fast electron imaging and spectroscopy. Finally, the present study provides examples of electron beam damage on lithium-ion battery materials and suggests that special attention is necessary to prevent misinterpretation of experimental results.« less

Quantitative determination of dimethicone in commercial tablets and capsules by Fourier transform infrared spectroscopy and antifoaming activity test.

PubMed

Torrado, G; García-Arieta, A; de los Ríos, F; Menéndez, J C; Torrado, S

1999-03-01

Fourier transform infrared (FTIR) spectroscopy and antifoaming activity test have been employed for the quantitative analysis of dimethicone. Linearity, accuracy and precision are presented for both methods. These methods have been also used to compare different dimethicone-containing proprietary medicines. FTIR spectroscopy has shown to be adequate for quantitation of dimethicone in commercial tablets and capsules in order to comply with USP requirements. The antifoaming activity test is able to detect incompatibilities between dimethicone and other constituents. The presence of certain enzymes in some medicinal products increases the defoaming properties of these formulations.

Double wedge prism based beam deflector for precise laser beam steering

NASA Astrophysics Data System (ADS)

Tyszka, Krzysztof; Dobosz, Marek; Bilaszewski, Tomasz

2018-02-01

Aiming to increase laser beam pointing stability required in interferometric measurements, we designed a laser beam deflector intended for active laser beam stabilization systems. The design is based on two wedge-prisms: the deflecting wedge driven by a tilting piezo-platform and the fixed wedge to compensate initial beam deflection. Our design allows linear beam steering, independently in the horizontal or vertical direction, with resolution of less than 1 μrad in a range of more than 100 μrad, and no initial deflection of the beam. Moreover, the ratio of the output beam deflection angle and the wedge tilt angle is less than 0.1; therefore, the noise influence is significantly reduced in comparison to standard mirror-based deflectors. The theoretical analyses support the designing process and can serve as a guide to wedge-prism selection. The experimental results are in agreement with theory and confirm the advantages of the presented double wedge system.

Soft X-ray spectroscopy of nanoparticles by velocity map imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kostko, O.; Xu, B.; Jacobs, M. I.

Velocity map imaging (VMI), a technique traditionally used to study chemical dynamics in the gas phase, is applied to study X-ray photoemission from aerosol nanoparticles. Soft X-rays from the Advanced Light Source synchrotron, probe a beam of nanoparticles, and the resulting photoelectrons are velocity mapped to obtain their kinetic energy distributions. A new design of the VMI spectrometer is described. The spectrometer is benchmarked by measuring vacuum ultraviolet photoemission from gas phase xenon and squalene nanoparticles followed by measurements using soft X-rays. It is demonstrated that the photoelectron distribution from X-ray irradiated squalene nanoparticles is dominated by secondary electrons. Bymore » scanning the photon energies and measuring the intensities of these secondary electrons, a near edge X-ray absorption fine structure (NEXAFS) spectrum is obtained. The NEXAFS technique is used to obtain spectra of aqueous nanoparticles at the oxygen K edge. By varying the position of the aqueous nanoparticle beam relative to the incident X-ray beam, evidence is presented such that the VMI technique allows for NEXAFS spectroscopy of water in different physical states. Finally, we discuss the possibility of applying VMI methods to probe liquids and solids via X-ray spectroscopy.« less

Soft X-ray spectroscopy of nanoparticles by velocity map imaging

DOE PAGES

Kostko, O.; Xu, B.; Jacobs, M. I.; ...

2017-05-05

Velocity map imaging (VMI), a technique traditionally used to study chemical dynamics in the gas phase, is applied to study X-ray photoemission from aerosol nanoparticles. Soft X-rays from the Advanced Light Source synchrotron, probe a beam of nanoparticles, and the resulting photoelectrons are velocity mapped to obtain their kinetic energy distributions. A new design of the VMI spectrometer is described. The spectrometer is benchmarked by measuring vacuum ultraviolet photoemission from gas phase xenon and squalene nanoparticles followed by measurements using soft X-rays. It is demonstrated that the photoelectron distribution from X-ray irradiated squalene nanoparticles is dominated by secondary electrons. Bymore » scanning the photon energies and measuring the intensities of these secondary electrons, a near edge X-ray absorption fine structure (NEXAFS) spectrum is obtained. The NEXAFS technique is used to obtain spectra of aqueous nanoparticles at the oxygen K edge. By varying the position of the aqueous nanoparticle beam relative to the incident X-ray beam, evidence is presented such that the VMI technique allows for NEXAFS spectroscopy of water in different physical states. Finally, we discuss the possibility of applying VMI methods to probe liquids and solids via X-ray spectroscopy.« less

Transport Measurements and Synchrotron-Based X-Ray Absorption Spectroscopy of Iron Silicon Germanide Grown by Molecular Beam Epitaxy

NASA Astrophysics Data System (ADS)

Elmarhoumi, Nader; Cottier, Ryan; Merchan, Greg; Roy, Amitava; Lohn, Chris; Geisler, Heike; Ventrice, Carl, Jr.; Golding, Terry

2009-03-01

Some of the iron-based metal silicide and germanide phases have been predicted to be direct band gap semiconductors. Therefore, they show promise for use as optoelectronic materials. We have used synchrotron-based x-ray absorption spectroscopy to study the structure of iron silicon germanide films grown by molecular beam epitaxy. A series of Fe(Si1-xGex)2 thin films (2000 -- 8000å) with a nominal Ge concentration of up to x = 0.04 have been grown. X-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) measurements have been performed on the films. The nearest neighbor co-ordination corresponding to the β-FeSi2 phase of iron silicide provides the best fit with the EXAFS data. Temperature dependent (20 < T < 350 K) magneto transport measurements were done on the Fe(Si1-xGex)2 thin films via Van Der Paw (VDP) Hall configuration using a 0.5-1T magnetic field and a current of 10-200 μA through indium ohmic contacts, the Hall coefficient was calculated. Results suggest semiconducting behavior of the films which is consistent with the EXAFS results.

Development and biological applications of optical tweezers and Raman spectroscopy

NASA Astrophysics Data System (ADS)

Xie, Chang'an

Optical tweezers is a three-dimensional manipulation tool that employs a gradient force that originates from the single highly focused laser beam. Raman spectroscopy is a molecular analytical tool that can give a highly unique "fingerprint" for each substance by measuring the unique vibrations of its molecules. The combination of these two optical techniques offers a new tool for the manipulation and identification of single biological cells and microscopic particles. In this thesis, we designed and implemented a Laser-Tweezers-Raman-Spectroscopy (LTRS) system, also called the Raman-tweezers, for the simultaneous capture and analysis of both biological particles and non-biological particles. We show that microparticles can be conveniently captured at the focus of a laser beam and the Raman spectra of trapped particles can be acquired with high quality. The LTRS system overcomes the intrinsic Brownian motion and cell motility of microparticles in solution and provides a promising tool for in situ identifying suspicious agents. In order to increase the signal to noise ratio, several schemes were employed in LTRS system to reduce the blank noise and the fluorescence signal coming from analytes and the surrounding background. These techniques include near-infrared excitation, optical levitation, confocal microscopy, and frequency-shifted Raman difference. The LTRS system has been applied for the study in cell biology at the single cell level. With the built Raman-tweezers system, we studied the dynamic physiological processes of single living cells, including cell cycle, the transcription and translation of recombinant protein in transgenic yeast cells and the T cell activation. We also studied cell damage and associated biochemical processes in optical traps, UV radiations, and evaluated heating by near-infrared Raman spectroscopy. These studies show that the Raman-tweezers system is feasible to provide rapid and reliable diagnosis of cellular disorders and can be

Damage-free vibrational spectroscopy of biological materials in the electron microscope

PubMed Central

Rez, Peter; Aoki, Toshihiro; March, Katia; Gur, Dvir; Krivanek, Ondrej L.; Dellby, Niklas; Lovejoy, Tracy C.; Wolf, Sharon G.; Cohen, Hagai

2016-01-01

Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an ‘aloof' electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies <1 eV can be ‘safely' investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C–H, N–H and C=O vibrational signatures with no observable radiation damage. The technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ∼10 nm, simultaneously combined with imaging in the electron microscope. PMID:26961578

Damage-free vibrational spectroscopy of biological materials in the electron microscope.

PubMed

Rez, Peter; Aoki, Toshihiro; March, Katia; Gur, Dvir; Krivanek, Ondrej L; Dellby, Niklas; Lovejoy, Tracy C; Wolf, Sharon G; Cohen, Hagai

2016-03-10

Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an 'aloof' electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies <1 eV can be 'safely' investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C-H, N-H and C=O vibrational signatures with no observable radiation damage. The technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ∼10 nm, simultaneously combined with imaging in the electron microscope.

Investigation of Damage with Cluster Ion Beam Irradiation Using HR-RBS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seki, Toshio; Aoki, Takaaki; Matsuo, Jiro

2008-11-03

Cluster ion beam can process targets with shallow damage because of the very low irradiation energy per atom. However, it is needed to investigate the damage with cluster ion beam irradiation, because recent applications demand process targets with ultra low damage. The shallow damage can be investigated from depth profiles of specific species before and after ion irradiation. They can be measured with secondary ion mass spectrometry (SIMS) and Rutherford backscattering spectroscopy (RBS). High resolution Rutherford backscattering spectroscopy (HR-RBS) is a non destructive measurement method and depth profiles can be measured with nano-resolution. The cluster ion beam mixing of thinmore » Ni layer in carbon targets can be investigated with HR-RBS. The mixing depth with cluster ion irradiation at 10 keV was about 10 nm. The mixing depth with cluster ion irradiation at 1 keV and 5 keV were less than 1 nm and 5 nm, respectively. The number of displaced Ni atoms with cluster ion irradiation was very larger than that with monomer ion irradiation of same energy. This result shows that violent mixing occurs with single cluster impact.« less

A source of antihydrogen for in-flight hyperfine spectroscopy

PubMed Central

Kuroda, N.; Ulmer, S.; Murtagh, D. J.; Van Gorp, S.; Nagata, Y.; Diermaier, M.; Federmann, S.; Leali, M.; Malbrunot, C.; Mascagna, V.; Massiczek, O.; Michishio, K.; Mizutani, T.; Mohri, A.; Nagahama, H.; Ohtsuka, M.; Radics, B.; Sakurai, S.; Sauerzopf, C.; Suzuki, K.; Tajima, M.; Torii, H. A.; Venturelli, L.; Wu¨nschek, B.; Zmeskal, J.; Zurlo, N.; Higaki, H.; Kanai, Y.; Lodi Rizzini, E.; Nagashima, Y.; Matsuda, Y.; Widmann, E.; Yamazaki, Y.

2014-01-01

Antihydrogen, a positron bound to an antiproton, is the simplest antiatom. Its counterpart—hydrogen—is one of the most precisely investigated and best understood systems in physics research. High-resolution comparisons of both systems provide sensitive tests of CPT symmetry, which is the most fundamental symmetry in the Standard Model of elementary particle physics. Any measured difference would point to CPT violation and thus to new physics. Here we report the development of an antihydrogen source using a cusp trap for in-flight spectroscopy. A total of 80 antihydrogen atoms are unambiguously detected 2.7 m downstream of the production region, where perturbing residual magnetic fields are small. This is a major step towards precision spectroscopy of the ground-state hyperfine splitting of antihydrogen using Rabi-like beam spectroscopy. PMID:24448273

Injected ion energy dependence of SiC film deposited by low-energy SiC3H9+ ion beam produced from hexamethyldisilane

NASA Astrophysics Data System (ADS)

Yoshimura, Satoru; Sugimoto, Satoshi; Takeuchi, Takae; Murai, Kensuke; Kiuchi, Masato

2018-04-01

We mass-selected SiC3H9+ ions from various fragments produced through the decomposition of hexamethyldisilane, and finally produced low-energy SiC3H9+ ion beams. The ion beams were injected into Si(1 0 0) substrates and the dependence of deposited films on injected ion energy was then investigated. Injected ion energies were 20, 100, or 200 eV. Films obtained were investigated with X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. X-ray diffraction and X-ray photoelectron spectroscopy of the substrates obtained following the injection of 20 eV ions demonstrated the occurrence of silicon carbide film (3C-SiC) deposition. On the other hand, Raman spectroscopy showed that the films deposited by the injection of 100 or 200 eV ions included 3C-SiC plus diamond-like carbon. Ion beam deposition using hexamethyldisilane-derived 20 eV SiC3H9+ ions is an efficient technique for 3C-SiC film formation on Si substrates.

Superconductivity in ion-beam-mixed layered Au-Si thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jisrawi, N.M.; McLean, W.L.; Stoffel, N.G.

The superconducting properties of thin films made by mixing alternating layers of Au and Si using ion-beam bombardment correlate with the formation of metastable metallic phases in what is otherwise a simple eutectic system. Transmission-electron-microscopy measurements reveal the superconducting phases to be amorphous. Compound formation and the nature of Au-Si bonding in these metastable phases are demonstrated from x-ray photoelectron spectroscopy and from a previous study of x-ray-absorption spectroscopy. After mixing with a beam of Xe ions, multilayered films with an average nominal composition Au{sub {ital x}}Si{sub 1{minus}{ital x}}, where {ital x}=0.2, 0.4, 0.5, 0.72, and 0.8, exhibited superconducting transitionmore » temperatures in the range 0.2--1.2 K. A double transition feature in the magnetic field dependence of the resistivity is attributed to the formation of more than one metastable metallic phase in the same sample as the ion dose increases.« less

Transient Infrared Emission Spectroscopy

NASA Astrophysics Data System (ADS)

Jones, Roger W.; McClelland, John F.

1989-12-01

Transient Infrared Emission Spectroscopy (TIRES) is a new technique that reduces the occurrence of self-absorption in optically thick solid samples so that analytically useful emission spectra may be observed. Conventional emission spectroscopy, in which the sample is held at an elevated, uniform temperature, is practical only for optically thin samples. In thick samples the emission from deep layers of the material is partially absorbed by overlying layers.1 This self-absorption results in emission spectra from most optically thick samples that closely resemble black-body spectra. The characteristic discrete emission bands are severely truncated and altered in shape. TIRES bypasses this difficulty by using a laser to heat only an optically thin surface layer. The increased temperature of the layer is transient since the layer will rapidly cool and thicken by thermal diffusion; hence the emission collection must be correlated with the laser heating. TIRES may be done with both pulsed and cw lasers.2,3 When a pulsed laser is used, the spectrometer sampling must be synchronized with the laser pulsing so that only emission during and immediately after each laser pulse is observed.3 If a cw laser is used, the sample must move rapidly through the beam. The hot, transient layer is then in the beam track on the sample at and immediately behind the beam position, so the spectrometer field of view must be limited to this region near the beam position.2 How much self-absorption the observed emission suffers depends on how thick the heated layer has grown by thermal diffusion when the spectrometer samples the emission. Use of a pulsed laser synchronized with the spectrometer sampling readily permits reduction of the time available for heat diffusion to about 100 acs .3 When a cw laser is used, the heat-diffusion time is controlled by how small the spectrometer field of view is and by how rapidly the sample moves past within this field. Both a very small field of view and a

SU-E-T-610: Phosphor-Based Fiber Optic Probes for Proton Beam Characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Darafsheh, A; Soldner, A; Liu, H

2015-06-15

Purpose: To investigate feasibility of using fiber optics probes with rare-earth-based phosphor tips for proton beam radiation dosimetry. We designed and fabricated a fiber probe with submillimeter resolution (<0.5 mm3) based on TbF3 phosphors and evaluated its performance for measurement of proton beam including profiles and range. Methods: The fiber optic probe with TbF3 phosphor tip, embedded in tissue-mimicking phantoms was irradiated with double scattering proton beam with energy of 180 MeV. Luminescence spectroscopy was performed by a CCD-coupled spectrograph to analyze the emission spectra of the fiber tip. In order to measure the spatial beam profile and percentage depthmore » dose, we used singular value decomposition method to spectrally separate the phosphors ionoluminescence signal from the background Cerenkov radiation signal. Results: The spectra of the TbF3 fiber probe showed characteristic ionoluminescence emission peaks at 489, 542, 586, and 620 nm. By using singular value decomposition we found the contribution of the ionoluminescence signal to measure the percentage depth dose in phantoms and compared that with measurements performed with ion chamber. We observed quenching effect at the spread out Bragg peak region, manifested as under-responding of the signal, due to the high LET of the beam. However, the beam profiles were not dramatically affected by the quenching effect. Conclusion: We have evaluated the performance of a fiber optic probe with submillimeter resolution for proton beam dosimetry. We demonstrated feasibility of spectral separation of the Cerenkov radiation from the collected signal. Such fiber probes can be used for measurements of proton beams profile and range. The experimental apparatus and spectroscopy method developed in this work provide a robust platform for characterization of proton-irradiated nanophosphor particles for ultralow fluence photodynamic therapy or molecular imaging applications.« less

Compositional analysis of ultrananocrystalline diamond (UNCD) films using ion beam scattering

NASA Astrophysics Data System (ADS)

AlFaify, S.; Garratt, E.; Nandasiri, M. I.; Kayani, A.; Sumant, A. V.; Mancini, D. C.

2009-11-01

Determination of the elemental composition is important to correlate the electrical and the optical properties of ultrananocrystalline diamond (UNCD) films, doped with and without nitrogen. To obtain the complete picture of impurities in the UNCD thin films, Rutherford backscattering spectroscopy (RBS), Non-Rutherford backscattering spectroscopy (NRBS), Elastic recoil detection analysis (ERDA) and nuclear reaction analysis (NRA) were performed on UNCD films on Si substrate and on free standing films. Helium beam was used for RBS and ERDA and protons were used for NRBS measurements. Exploiting the nuclear reaction of deuterons with C, O and N, 1.1 MeV D+ beam was used to quantitatively measure the concentration of these elements. Our results show that UNCD films contain less than 3% of Hydrogen while Nitrogen content incorporated in the film was estimated to be lower than 1%. The intermixing region between the substrate and the film was found to be negligible.

Study by AES, EELS Spectroscopy of electron Irradiation on InP and InPO4/InP in comparison with Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Lounis, Z.; Bouslama, M.; Hamaida, K.; Jardin, C.; Abdellaoui, A.; Ouerdane, A.; Ghaffour, M.; Berrouachedi, N.

2012-02-01

We give the great interest to characterise the InP and InPO4/InP submitted to electron beam irradiation owing to the Auger Electron Spectroscopy (AES) associated to both methods Electron Energy Loss Spectroscopy (EELS). The incident electron produces breaking of (In-P) chemical bonds. The electron beam even acts to stimulate oxidation of InP surface involving on the top layers. Other, the oxide InPO4 developed on InP does appear very sensitive to the irradiation due to electron beam shown by the monitoring of EELS spectra recorded versus the irradiated times of the surface. There appears a new oxide thought to be In2O3. We give the simulation methods Casino (Carlo simulation of electron trajectory in solids) for determination with accuracy the loss energy of backscattered electrons and compared with reports results have been obtained with EELS Spectroscopy. These techniques of spectroscopy alone do not be able to verify the affected depth during interaction process. So, using this simulation method, we determine the interaction of electrons in the matter.

Experimental Study on Full-Scale Beams Made by Reinforced Alkali Activated Concrete Undergoing Flexure.

PubMed

Monfardini, Linda; Minelli, Fausto

2016-08-30

Alkali Activated Concrete (AAC) is an alternative kind of concrete that uses fly ash as a total replacement of Portland cement. Fly ash combined with alkaline solution and cured at high temperature reacts to form a binder. Four point bending tests on two full scale beams made with AAC are described in this paper. Companion small material specimens were also casted with the aim of properly characterizing this new tailored material. The beam's length was 5000 mm and the cross section was 200 mm × 300 mm. The AAC consisted of fly ash, water, sand 0-4 mm and coarse aggregate 6-10 mm; and the alkaline solution consisted of sodium hydroxide mixed with sodium silicate. No cement was utilized. The maximum aggregate size was 10 mm; fly ash was type F, containing a maximum calcium content of 2%. After a rest period of two days, the beam was cured at 60 °C for 24 h. Data collected and critically discussed included beam deflection, crack patterns, compressive and flexural strength and elastic modulus. Results show how AAC behavior is comparable with Ordinary Portland Cement (OPC) based materials. Nonlinear numerical analyses are finally reported, promoting a better understanding of the structural response.

Adsorption of n-butane on graphene/Ru(0001)—A molecular beam scattering study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sivapragasam, Nilushni; Nayakasinghe, Mindika T.; Burghaus, Uwe, E-mail: uwe.burghaus@ndsu.edu

2016-07-15

Adsorption kinetics/dynamics of n-butane on graphene, physical vapor deposited on Ru(0001) (hereafter G/Ru), and bare Ru(0001) (hereafter Ru) are discussed. The chemical activity of the supported-graphene as well as the support was probed by thermal desorption spectroscopy (adsorption kinetics). In addition and to the best of our knowledge, for the first time, molecular beam scattering data of larger molecules were collected for graphene (probing the adsorption dynamics). Furthermore, samples were inspected by x-ray photoelectron spectroscopy and Auger electron spectroscopy. At the measuring conditions used here, n-butane adsorption kinetics/dynamics are molecular and nonactivated. Binding energies of butane on Ru and G/Rumore » are indistinguishable within experimental uncertainty. Thus, G/Ru is “kinetically transparent.” Initial adsorption probabilities, S{sub 0}, of n-butane decrease with increasing impact energy (0.76–1.72 eV) and are adsorption temperature independent for both Ru and G/Ru, again consistent with molecular adsorption. Also, S{sub 0} of Ru and G/Ru are indistinguishable within experimental uncertainty. Thus, G/Ru is “dynamically transparent.” Coverage dependent adsorption probabilities indicate precursor effects for graphene/Ru.« less

Simultaneous multi-beam planar array IR (pair) spectroscopy

DOEpatents

Elmore, Douglas L.; Rabolt, John F.; Tsao, Mei-Wei

2005-09-13

An apparatus and method capable of providing spatially multiplexed IR spectral information simultaneously in real-time for multiple samples or multiple spatial areas of one sample using IR absorption phenomena requires no moving parts or Fourier Transform during operation, and self-compensates for background spectra and degradation of component performance over time. IR spectral information and chemical analysis of the samples is determined by using one or more IR sources, sampling accessories for positioning the samples, optically dispersive elements, a focal plane array (FPA) arranged to detect the dispersed light beams, and a processor and display to control the FPA, and display an IR spectrograph. Fiber-optic coupling can be used to allow remote sensing. Portability, reliability, and ruggedness is enhanced due to the no-moving part construction. Applications include determining time-resolved orientation and characteristics of materials, including polymer monolayers. Orthogonal polarizers may be used to determine certain material characteristics.

Ion Beam And Plasma Jet Generated By A 3 kJ Plasma Focus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, L. K.; Ngoi, S. K.; Yap, S. L.

The plasma focus device is well known as a copious source of X-ray, neutrons, ion and electron beams. In this work, the characteristics of energetic ion beam emission in a 3 kJ Mather-type plasma focus is studied. The plasma focus system is operated at low pressure with argon as the working gas. The objective of the project is to obtain the argon ion beam and the plasma jet. The ion beam and plasma jet are used for material processing. In order to investigate the effect of the ion beam and plasma jet, crystalline silicon substrates are placed above the anode.more » Samples obtained after irradiation with the plasma focus discharge are analyzed by using the Scanning electron microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX).« less

Ultrashort megaelectronvolt positron beam generation based on laser-accelerated electrons

NASA Astrophysics Data System (ADS)

Xu, Tongjun; Shen, Baifei; Xu, Jiancai; Li, Shun; Yu, Yong; Li, Jinfeng; Lu, Xiaoming; Wang, Cheng; Wang, Xinliang; Liang, Xiaoyan; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

2016-03-01

Experimental generation of ultrashort MeV positron beams with high intensity and high density using a compact laser-driven setup is reported. A high-density gas jet is employed experimentally to generate MeV electrons with high charge; thus, a charge-neutralized MeV positron beam with high density is obtained during laser-accelerated electrons irradiating high-Z solid targets. It is a novel electron-positron source for the study of laboratory astrophysics. Meanwhile, the MeV positron beam is pulsed with an ultrashort duration of tens of femtoseconds and has a high peak intensity of 7.8 × 1021 s-1, thus allows specific studies of fast kinetics in millimeter-thick materials with a high time resolution and exhibits potential for applications in positron annihilation spectroscopy.

Precision spectroscopy of the 2S-4P transition in atomic hydrogen

NASA Astrophysics Data System (ADS)

Maisenbacher, Lothar; Beyer, Axel; Matveev, Arthur; Grinin, Alexey; Pohl, Randolf; Khabarova, Ksenia; Kolachevsky, Nikolai; Hänsch, Theodor W.; Udem, Thomas

2017-04-01

Precision measurements of atomic hydrogen have long been successfully used to extract fundamental constants and to test bound-state QED. However, both these applications are limited by measurements of hydrogen lines other than the very precisely known 1S-2S transition. Moreover, the proton r.m.s.charge radius rp extracted from electronic hydrogen measurements currently disagrees by 4 σ with the much more precise value extracted from muonic hydrogen spectroscopy. We have measured the 2S-4P transition in atomic hydrogen using a cryogenic beam of hydrogen atoms optically excited to the initial 2S state. The first order Doppler shift of the one-photon 2S-4P transition is suppressed by actively stabilized counter-propagating laser beams and time-of-flight resolved detection. Quantum interference between excitation paths can lead to significant line distortions in our system. We use an experimentally verified, simple line shape model to take these distortions into account. With this, we can extract a new value for rp and the Rydberg constant R∞ with comparable accuracy as the combined previous H world data.

Ion beam radiation effects on natural halite crystals

NASA Astrophysics Data System (ADS)

Arun, T.; Ram, S. S.; Karthikeyan, B.; Ranjith, P.; Ray, D. K.; Rout, B.; Krishna, J. B. M.; Sengupta, Pranesh; Parlapalli, Venkata Satyam

2017-10-01

Halites are one of the interesting material due to its color variations. Natural halites whose color ranges from transparent to dark blue were studied by UV-VIS and Raman spectroscopy. The halite crystals were irradiated with 3 MeV proton micro-beam (∼20 μm beam width with ∼80 PA beam current) for 10 and 90 min to study the radiation damage. After 10 mins of irradiation, small spot developed on the surface of transparent halite crystal whereas after 90 mins of irradiation the spot spread inside the bulk leading to a brown coloration (20 μm initial size to ∼2.0 mm final size). The irradiated portion and the un-irradiated portion of the halites was characterized by Raman spectroscopic technique. The variation in the population density was observed from the UV-Vis spectra. The change in the Raman band intensities was observed for transparent, blue colored and proton beam irradiation halites. Such variation of spectroscopic characteristics due to proton irradiation suggests that the halite can be used for the radiation monitoring.

Graphene engineering by neon ion beams

DOE PAGES

Iberi, Vighter; Ievlev, Anton V.; Vlassiouk, Ivan; ...

2016-02-18

Achieving the ultimate limits of materials and device performance necessitates the engineering of matter with atomic, molecular, and mesoscale fidelity. While common for organic and macromolecular chemistry, these capabilities are virtually absent for 2D materials. In contrast to the undesired effect of ion implantation from focused ion beam (FIB) lithography with gallium ions, and proximity effects in standard e-beam lithography techniques, the shorter mean free path and interaction volumes of helium and neon ions offer a new route for clean, resist free nanofabrication. Furthermore, with the advent of scanning helium ion microscopy, maskless He + and Ne + beam lithographymore » of graphene based nanoelectronics is coming to the forefront. Here, we will discuss the use of energetic Ne ions in engineering graphene devices and explore the mechanical, electromechanical and chemical properties of the ion-milled devices using scanning probe microscopy (SPM). By using SPM-based techniques such as band excitation (BE) force modulation microscopy, Kelvin probe force microscopy (KPFM) and Raman spectroscopy, we demonstrate that the mechanical, electrical and optical properties of the exact same devices can be quantitatively extracted. Additionally, the effect of defects inherent in ion beam direct-write lithography, on the overall performance of the fabricated devices is elucidated.« less

Multiple ion beam irradiation for the study of radiation damage in materials

NASA Astrophysics Data System (ADS)

Taller, Stephen; Woodley, David; Getto, Elizabeth; Monterrosa, Anthony M.; Jiao, Zhijie; Toader, Ovidiu; Naab, Fabian; Kubley, Thomas; Dwaraknath, Shyam; Was, Gary S.

2017-12-01

The effects of transmutation produced helium and hydrogen must be included in ion irradiation experiments to emulate the microstructure of reactor irradiated materials. Descriptions of the criteria and systems necessary for multiple ion beam irradiation are presented and validated experimentally. A calculation methodology was developed to quantify the spatial distribution, implantation depth and amount of energy-degraded and implanted light ions when using a thin foil rotating energy degrader during multi-ion beam irradiation. A dual ion implantation using 1.34 MeV Fe+ ions and energy-degraded D+ ions was conducted on single crystal silicon to benchmark the dosimetry used for multi-ion beam irradiations. Secondary Ion Mass Spectroscopy (SIMS) analysis showed good agreement with calculations of the peak implantation depth and the total amount of iron and deuterium implanted. The results establish the capability to quantify the ion fluence from both heavy ion beams and energy-degraded light ion beams for the purpose of using multi-ion beam irradiations to emulate reactor irradiated microstructures.

Active Signal Propagation and Imaging Using Vortex Beams

DTIC Science & Technology

2014-08-01

Though this method of OV beam generation allows dynamic control it also results in poor power conversion efficiency (~< 15%) and relatively low power...rectangular quart cell (1cm x 10 cm x 10cm). Various TM conditions are simulated inside the cell by diluting deionized water with polystyrene spheres...c). Both beams were then focused into a 1cm x 1cm x 10cm glass cell comprising a solution of latex spheres and ionized water . Different particle

Pulsed Electron Beam Spectroscopy for Temperature Measurements in Hypersonic Flows

DTIC Science & Technology

2010-01-01

atmospheric pr essures wit hin the fligh t envelope of scramjet-powered flight vehicles. Because of the pressure disparity between measured flow and me...represents what might be o btained from the pulse d e-beam s ystem if it were used in the high-te mperature (but high-pr essure ) st agnation cha...di fferential pressure pump has been developed for pressure separations up to approximately 1 torr. F or higher pr essures , a f ast act ion r otary

X-ray-induced photo-chemistry and X-ray absorption spectroscopy of biological samples

PubMed Central

George, Graham N.; Pickering, Ingrid J.; Pushie, M. Jake; Nienaber, Kurt; Hackett, Mark J.; Ascone, Isabella; Hedman, Britt; Hodgson, Keith O.; Aitken, Jade B.; Levina, Aviva; Glover, Christopher; Lay, Peter A.

2012-01-01

As synchrotron light sources and optics deliver greater photon flux on samples, X-ray-induced photo-chemistry is increasingly encountered in X-ray absorption spectroscopy (XAS) experiments. The resulting problems are particularly pronounced for biological XAS experiments. This is because biological samples are very often quite dilute and therefore require signal averaging to achieve adequate signal-to-noise ratios, with correspondingly greater exposures to the X-ray beam. This paper reviews the origins of photo-reduction and photo-oxidation, the impact that they can have on active site structure, and the methods that can be used to provide relief from X-ray-induced photo-chemical artifacts. PMID:23093745

Damage-free vibrational spectroscopy of biological materials in the electron microscope

DOE PAGES

Rez, Peter; Aoki, Toshihiro; March, Katia; ...

2016-03-10

Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an ‘aloof’ electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies o1 eV can be ‘safely’ investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C–H, N–H and C=O vibrational signatures with nomore » observable radiation damage. Furthermore, the technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ~10nm, simultaneously combined with imaging in the electron microscope.« less

Damage-free vibrational spectroscopy of biological materials in the electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rez, Peter; Aoki, Toshihiro; March, Katia

Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an ‘aloof’ electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies o1 eV can be ‘safely’ investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C–H, N–H and C=O vibrational signatures with nomore » observable radiation damage. Furthermore, the technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ~10nm, simultaneously combined with imaging in the electron microscope.« less

Active control of the forced and transient response of a finite beam. M.S. Thesis

NASA Technical Reports Server (NTRS)

Post, John T.

1990-01-01

Structural vibrations from a point force are modelled on a finite beam. This research explores the theoretical limit on controlling beam vibrations utilizing another point source as an active controller. Three different types of excitation are considered, harmonic, random, and transient. For harmonic excitation, control over the entire beam length is possible only when the excitation frequency is near a resonant frequency of the beam. Control over a subregion may be obtained even between resonant frequencies at the cost of increasing the vibration outside of the control region. For random excitation, integrating the expected value of the displacement squared over the required interval, is shown to yield the identical cost function as obtained by integrating the cost function for harmonic excitation over all excitation frequencies. As a result, it is always possible to reduce the cost function for random excitation whether controlling the entire beam or just a subregion, without ever increasing the vibration outside the region in which control is desired. The last type of excitation considered is a single, transient pulse. The form of the controller is specified as either one or two delayed pulses, thus constraining the controller to be casual. The best possible control is examined while varying the region of control and the controller location. It is found that control is always possible using either one or two control pulses.

How gamma-rays and electron-beam irradiation would affect the antimicrobial activity of differently processed wild mushroom extracts?

PubMed

Alves, M J; Fernandes, Â; Barreira, J C M; Lourenço, I; Fernandes, D; Moura, A; Ribeiro, A R; Salgado, J; Antonio, A; Ferreira, I C F R

2015-03-01

The effects of irradiation (gamma-rays and electron-beams), up to 10 kGy, in the antimicrobial activity of mushroom species (Boletus edulis, Hydnum repandum, Macrolepiota procera and Russula delica) differently processed (fresh, dried, freeze) were evaluated. Clinical isolates with different resistance profiles from hospitalized patients in Local Health Unit of Mirandela, Northeast of Portugal, were used as target micro-organisms. The mushrooms antimicrobial activity did not suffer significant changes that might compromise applying irradiation as a possible mushroom conservation technology. Two kGy dose (independently of using gamma-rays or electron-beams) seemed to be the most suitable choice to irradiate mushrooms. This study provides important results in antimicrobial activity of extracts prepared from irradiated mushroom species. © 2014 The Society for Applied Microbiology.

Determination of the active volumes of solid-state photon-beam dosimetry detectors using the PTB proton microbeam.

PubMed

Poppinga, Daniela; Delfs, Bjoern; Meyners, Jutta; Langner, Frank; Giesen, Ulrich; Harder, Dietrich; Poppe, Bjoern; Looe, Hui K

2018-05-04

This study aims at the experimental determination of the diameters and thicknesses of the active volumes of solid-state photon-beam detectors for clinical dosimetry. The 10 MeV proton microbeam of the PTB (Physikalisch-Technische Bundesanstalt, Braunschweig) was used to examine two synthetic diamond detectors, type microDiamond (PTW Freiburg, Germany), and the silicon detectors Diode E (PTW Freiburg, Germany) and Razor Diode (Iba Dosimetry, Germany). The knowledge of the dimensions of their active volumes is essential for their Monte Carlo simulation and their applications in small-field photon-beam dosimetry. The diameter of the active detector volume was determined from the detector current profile recorded by radially scanning the proton microbeam across the detector. The thickness of the active detector volume was determined from the detector's electrical current, the number of protons incident per time interval and their mean stopping power in the active volume. The mean energy of the protons entering this volume was assessed by comparing the measured and the simulated influence of the thickness of a stack of aluminum preabsorber foils on the detector signal. For all detector types investigated, the diameters measured for the active volume closely agreed with the manufacturers' data. For the silicon Diode E detector, the thickness determined for the active volume agreed with the manufacturer's data, while for the microDiamond detectors and the Razor Diode, the thicknesses measured slightly exceeded those stated by the manufacturers. The PTB microbeam facility was used to analyze the diameters and thicknesses of the active volumes of photon dosimetry detectors for the first time. A new method of determining the thickness values with an uncertainty of ±10% was applied. The results appear useful for further consolidating detailed geometrical knowledge of the solid-state detectors investigated, which are used in clinical small-field photon-beam dosimetry. �

Measurement of key resonances for the Al 24 ( p , γ ) Si 25 reaction rate using in-beam γ -ray spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Longfellow, B.; Gade, A.; Brown, B. A.

Energy levels and branching ratios for the rp-process nucleus 25Si were determined from the reactions 9Be ( 26Si, 25Si) X and 9Be ( 25Al, 25Si) X using in-beam γ-ray spectroscopy with both high-efficiency and high-resolution detector arrays. Proton-unbound states at 3695(14) and 3802(11) keV were identified and assigned tentative spins and parities based on comparison to theory and the mirror nucleus. The 24Al (p, γ) 25Si reaction rate was calculated using the experimental states and states from charge-dependent USDA and USDB shell-model calculations with downward shifts of the 1s 1/2 proton orbital to account for the observed Thomas-Ehrman shift, leadingmore » to a factor of 10–100 increase in rate for the temperature region of 0.22 GK as compared to a previous calculation. These shifts may be applicable to neighboring nuclei, impacting the proton capture rates in this region of the chart.« less

Measurement of key resonances for the Al 24 ( p , γ ) Si 25 reaction rate using in-beam γ -ray spectroscopy

DOE PAGES

Longfellow, B.; Gade, A.; Brown, B. A.; ...

2018-05-04

Energy levels and branching ratios for the rp-process nucleus 25Si were determined from the reactions 9Be ( 26Si, 25Si) X and 9Be ( 25Al, 25Si) X using in-beam γ-ray spectroscopy with both high-efficiency and high-resolution detector arrays. Proton-unbound states at 3695(14) and 3802(11) keV were identified and assigned tentative spins and parities based on comparison to theory and the mirror nucleus. The 24Al (p, γ) 25Si reaction rate was calculated using the experimental states and states from charge-dependent USDA and USDB shell-model calculations with downward shifts of the 1s 1/2 proton orbital to account for the observed Thomas-Ehrman shift, leadingmore » to a factor of 10–100 increase in rate for the temperature region of 0.22 GK as compared to a previous calculation. These shifts may be applicable to neighboring nuclei, impacting the proton capture rates in this region of the chart.« less

A differential optical absorption spectroscopy method for retrieval from ground-based Fourier transform spectrometers measurements of the direct solar beam

NASA Astrophysics Data System (ADS)

Huo, Yanfeng; Duan, Minzheng; Tian, Wenshou; Min, Qilong

2015-08-01

A differential optical absorption spectroscopy (DOAS)-like algorithm is developed to retrieve the column-averaged dryair mole fraction of carbon dioxide from ground-based hyper-spectral measurements of the direct solar beam. Different to the spectral fitting method, which minimizes the difference between the observed and simulated spectra, the ratios of multiple channel-pairs—one weak and one strong absorption channel—are used to retrieve from measurements of the shortwave infrared (SWIR) band. Based on sensitivity tests, a super channel-pair is carefully selected to reduce the effects of solar lines, water vapor, air temperature, pressure, instrument noise, and frequency shift on retrieval errors. The new algorithm reduces computational cost and the retrievals are less sensitive to temperature and H2O uncertainty than the spectral fitting method. Multi-day Total Carbon Column Observing Network (TCCON) measurements under clear-sky conditions at two sites (Tsukuba and Bremen) are used to derive xxxx for the algorithm evaluation and validation. The DOAS-like results agree very well with those of the TCCON algorithm after correction of an airmass-dependent bias.

Gas-phase broadband spectroscopy using active sources: progress, status, and applications

PubMed Central

Cossel, Kevin C.; Waxman, Eleanor M.; Finneran, Ian A.; Blake, Geoffrey A.; Ye, Jun; Newbury, Nathan R.

2017-01-01

Broadband spectroscopy is an invaluable tool for measuring multiple gas-phase species simultaneously. In this work we review basic techniques, implementations, and current applications for broadband spectroscopy. We discuss components of broad-band spectroscopy including light sources, absorption cells, and detection methods and then discuss specific combinations of these components in commonly-used techniques. We finish this review by discussing potential future advances in techniques and applications of broad-band spectroscopy. PMID:28630530

Beta-decay spectroscopy relevant to the r-process nucleosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishimura, Shunji; Collaboration: RIBF Decay Collaboration

2012-11-12

A scientific program of beta-decay spectroscopy relevant to r-process nucleosynthesis has been started using high intensity U-beam at the RIBF. The first results of {beta}-decay half-lives of very neutron-rich Kr to Tc nuclides, all of which lie close to the r-process path, suggest a systematic enhancement of the the {beta}-decay rates of the Zr and Nb isotopes around A110 with respect to the predictions of the deformed quasiparticle-random-phase-approximation model (FRDM + QRPA). An impact of the results on the astrophysical r-process is discussed together with the future perspective of the {beta}-decay spectroscopy with the EURICA.

Neutral particle beam intensity controller

DOEpatents

Dagenhart, William K.

1986-01-01

A neutral beam intensity controller is provided for a neutral beam generator in which a neutral beam is established by accelerating ions from an ion source into a gas neutralizer. An amplitude modulated, rotating magnetic field is applied to the accelerated ion beam in the gas neutralizer to defocus the resultant neutral beam in a controlled manner to achieve intensity control of the neutral beam along the beam axis at constant beam energy. The rotating magnetic field alters the orbits of ions in the gas neutralizer before they are neutralized, thereby controlling the fraction of neutral particles transmitted out of the neutralizer along the central beam axis to a fusion device or the like. The altered path or defocused neutral particles are sprayed onto an actively cooled beam dump disposed perpendicular to the neutral beam axis and having a central open for passage of the focused beam at the central axis of the beamline. Virtually zero therough 100% intensity control is achieved by varying the magnetic field strength without altering the ion source beam intensity or its species yield.

Positron annihilation induced Auger electron spectroscopy

NASA Technical Reports Server (NTRS)

Weiss, Alex; Koymen, A. R.; Mehl, David; Jensen, K. O.; Lei, Chun; Lee, K. H.

1990-01-01

Recently, Weiss et al. have demonstrated that it is possible to excite Auger transitions by annihilating core electrons using a low energy (less than 30eV) beam of positrons. This mechanism makes possible a new electron spectroscopy, Positron annihilation induced Auger Electron Spectroscopy (PAES). The probability of exciting an Auger transition is proportional to the overlap of the positron wavefunction with atomic core levels. Since the Auger electron energy provides a signature of the atomic species making the transition, PAES makes it possible to determine the overlap of the positron wavefunction with a particular element. PAES may therefore provide a means of detecting positron-atom complexes. Measurements of PAES intensities from clean and adsorbate covered Cu surfaces are presented which indicate that approx. 5 percent of positrons injected into CU at 25eV produce core annihilations that result in Auger transitions.

Cryogenically cooled octupole ion trap for spectroscopy of biomolecular ions.

PubMed

Boyarkin, Oleg V; Kopysov, Vladimir

2014-03-01

We present here the design of a linear octupole ion trap, suitable for collisional cryogenic cooling and spectroscopy of large ions. The performance of this trap has been assessed using ultraviolet (UV) photofragmentation spectroscopy of protonated dipeptides. At the trap temperature of 6.1 K, the vibrational temperature of the ions reaches 9.1 K, although their estimated translational temperature is ~150 K. This observation suggests that, despite the significant translational heating by radio-frequency electrical field, vibrational cooling of heavy ions in the octupole is at least as efficient as in the 22-pole ion traps previously used in our laboratory. In contrast to the 22-pole traps, excellent radial confinement of ions in the octupole makes it convenient for laser spectroscopy and boosts the dissociation yield of the stored ions to 30%. Overlap of the entire ion cloud by the laser beam in the octupole also allows for efficient UV depletion spectroscopy of ion-He clusters. The measured electronic spectra of the dipeptides and the clusters differ drastically, complicating a use of UV tagging spectroscopy for structural determination of large species.

[System of ns time-resolved spectroscopy diagnosis and radioprotection].

PubMed

Yao, Wei-Bo; Guo, Jian-Ming; Zhang, Yong-min; Tang, Jun-Ping; Cheng, Liang; Xu, Qi-fuo

2014-06-01

Cathode plasma of high current electron beam diode is an important research on high power microwave and strong pulsed radio accelerator. It is a reliable method to study cathode plasma by diagnosing the cathode plasma parameters with non-contact spectroscopy measurement system. The present paper introduced the work principle, system composition and performance of the nanosecond (ns) time-resolved spectroscopy diagnosis system. Furthermore, it introduced the implementing method and the temporal relation of lower jitter synchronous trigger system. Simultaneously, the authors designed electromagnetic and radio shield room to protect the diagnosis system due to the high electromagnetic and high X-ray and γ-ray radiation, which seriously interferes with the system. Time-resolved spectroscopy experiment on brass (H62) cathode shows that, the element and matter composition of cathode plasma is clearly increase with the increase in the diode pulsed voltage and current magnitude. The spectroscopy diagnosis system could be of up to 10 ns time resolve capability. It's least is 2 ns. Synchronous trigger system's jitter is less than 4 ns. The spectroscopy diagnosis system will open a new way to study the cathode emission mechanism in depth.

Design of titania nanotube structures by focused laser beam direct writing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Enachi, Mihai; Stevens-Kalceff, Marion A.; Sarua, Andrei

In this work, we report on electrochemical fabrication of titania films consisting of nanotubes (NTs) and their treatment by focused laser beam. The results of sample characterization by optical and scanning electron microscopy, cathodoluminescence imaging, and Raman scattering scanning spectroscopy are compared to those inherent to specimens subjected to thermal treatment in a furnace. The obtained data demonstrate possibilities for controlling crystallographic structure of TiO{sub 2} NTs by focused laser beam direct writing. These findings open new prospects for the design and fabrication of spatial architectures based on titania nanotubes.

Ion traps for precision experiments at rare-isotope-beam facilities

NASA Astrophysics Data System (ADS)

Kwiatkowski, Anna

2016-09-01

Ion traps first entered experimental nuclear physics when the ISOLTRAP team demonstrated Penning trap mass spectrometry of radionuclides. From then on, the demand for ion traps has grown at radioactive-ion-beam (RIB) facilities since beams can be tailored for the desired experiment. Ion traps have been deployed for beam preparation, from bunching (thereby allowing time coincidences) to beam purification. Isomerically pure beams needed for nuclear-structure investigations can be prepared for trap-assisted or in-trap decay spectroscopy. The latter permits studies of highly charged ions for stellar evolution, which would be impossible with traditional experimental nuclear-physics methods. Moreover, the textbook-like conditions and advanced ion manipulation - even of a single ion - permit high-precision experiments. Consequently, the most accurate and precise mass measurements are now performed in Penning traps. After a brief introduction to ion trapping, I will focus on examples which showcase the versatility and utility of the technique at RIB facilities. I will demonstrate how this atomic-physics technique has been integrated into nuclear science, accelerator physics, and chemistry. DOE.

Ablation centration after active eye tracker-assisted LASIK and comparison of flying-spot and broad-beam laser.

PubMed

Lin, Jane-Ming; Chen, Wen-Lu; Chiang, Chun-Chi; Tsai, Yi-Yu

2008-04-01

To evaluate ablation centration of flying-spot LASIK, investigate the effect of patient- and surgeon-related factors on centration, and compare flying-spot and broad-beam laser results. This retrospective study comprised 173 eyes of 94 patients who underwent LASIK with the Alcon LADARVision4000 with an active eye-tracking system. The effective tracking rate of the system is 100 Hz. The amount of decentration was analyzed by corneal topography. Patient- (low, high, and extreme myopia; effect of learning) and surgeon-related (learning curve) factors influencing centration were identified. Centration was compared to the SCHWIND Multiscan broad-beam laser with a 50-Hz tracker from a previous study. Mean decentration was 0.36+/-0.18 mm (range: 0 to 0.9 mm). Centration did not differ in low, high, and extreme myopia or in patients' first and second eyes. There were no significant differences in centration between the first 50 LASIK procedures and the last 50 procedures. Comparing flying-spot and broad-beam laser results, there were no differences in centration in low myopia. However, the LADARVision4000 yielded better centration results in high and extreme myopia. The Alcon LADARVision4000 active eye tracking system provides good centration for all levels of myopic correction and better centration than the Schwind broad-beam Multiscan in eyes with high and extreme myopia.

X-ray Echo Spectroscopy

NASA Astrophysics Data System (ADS)

Shvyd'ko, Yuri

2016-02-01

X-ray echo spectroscopy, a counterpart of neutron spin echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a pointlike x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-0.02 meV ultrahigh-resolution IXS applications (resolving power >108 ) with broadband ≃5 - 13 meV dispersing systems are introduced featuring more than 103 signal enhancement. The technique is general, applicable in different photon frequency domains.

A study on the anisole-water complex by molecular beam-electronic spectroscopy and molecular mechanics calculations.

PubMed

Becucci, M; Pietraperzia, G; Pasquini, M; Piani, G; Zoppi, A; Chelli, R; Castellucci, E; Demtroeder, W

2004-03-22

An experimental and theoretical study is made on the anisole-water complex. It is the first van der Waals complex studied by high resolution electronic spectroscopy in which the water is seen acting as an acid. Vibronically and rotationally resolved electronic spectroscopy experiments and molecular mechanics calculations are used to elucidate the structure of the complex in the ground and first electronic excited state. Some internal dynamics in the system is revealed by high resolution spectroscopy. (c) 2004 American Institute of Physics

A beam condenser for infrared spectrophotometers.

PubMed

Brandt, R C

1969-02-01

The design and performance of a beam condenser for ir spectrophotometers such as the Beckman model IR-11 is described. The instrument has an image size of 4 mm x 8 mm and permits the use of samples mounted in the tail of a cryostat whose outside dimension is as large as 7 cm square. Applications to negative light flux spectroscopy are described, in particular, the direct measurement of the longitudinal optical frequency of lattice vibration for AgBr and AgCl.

Power beaming research at NASA

NASA Technical Reports Server (NTRS)

Rather, John D. G.

1992-01-01

NASA's current research activities to evaluate laser power beaming systems are summarized with regard to their applications of greatest interest. Key technical certainties and uncertainties pertaining to laser power beaming systems appropriate for space applications are quantified. A path of development is presented that includes maturation of key technology components for reliable laser and millimeter wave power beaming systems during the 1990s.

Evaluation of beam halo from beam-gas scattering at the KEK Accelerator Test Facility

NASA Astrophysics Data System (ADS)

Yang, R.; Naito, T.; Bai, S.; Aryshev, A.; Kubo, K.; Okugi, T.; Terunuma, N.; Zhou, D.; Faus-Golfe, A.; Kubytskyi, V.; Liu, S.; Wallon, S.; Bambade, P.

2018-05-01

In circular colliders, as well as in damping rings and synchrotron radiation light sources, beam halo is one of the critical issues limiting the performance as well as potentially causing component damage and activation. It is imperative to clearly understand the mechanisms that lead to halo formation and to test the available theoretical models. Elastic beam-gas scattering can drive particles to large oscillation amplitudes and be a potential source of beam halo. In this paper, numerical estimation and Monte Carlo simulations of this process at the ATF of KEK are presented. Experimental measurements of beam halo in the ATF2 beam line using a diamond sensor detector are also described, which clearly demonstrate the influence of the beam-gas scattering process on the transverse halo distribution.

Optical spectroscopy using gas-phase femtosecond laser filamentation.

PubMed

Odhner, Johanan; Levis, Robert

2014-01-01

Femtosecond laser filamentation occurs as a dynamic balance between the self-focusing and plasma defocusing of a laser pulse to produce ultrashort radiation as brief as a few optical cycles. This unique source has many properties that make it attractive as a nonlinear optical tool for spectroscopy, such as propagation at high intensities over extended distances, self-shortening, white-light generation, and the formation of an underdense plasma. The plasma channel that constitutes a single filament and whose position in space can be controlled by its input parameters can span meters-long distances, whereas multifilamentation of a laser beam can be sustained up to hundreds of meters in the atmosphere. In this review, we briefly summarize the current understanding and use of laser filaments for spectroscopic investigations of molecules. A theoretical framework of filamentation is presented, along with recent experimental evidence supporting the established understanding of filamentation. Investigations carried out on vibrational and rotational spectroscopy, filament-induced breakdown, fluorescence spectroscopy, and backward lasing are discussed.

First neutral beam injection experiments on KSTAR tokamak.

PubMed

Jeong, S H; Chang, D H; Kim, T S; In, S R; Lee, K W; Jin, J T; Chang, D S; Oh, B H; Bae, Y S; Kim, J S; Park, H T; Watanabe, K; Inoue, T; Kashiwagi, M; Dairaku, M; Tobari, H; Hanada, M

2012-02-01

The first neutral beam (NB) injection system of the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak was partially completed in 2010 with only 1∕3 of its full design capability, and NB heating experiments were carried out during the 2010 KSTAR operation campaign. The ion source is composed of a JAEA bucket plasma generator and a KAERI large multi-aperture accelerator assembly, which is designed to deliver a 1.5 MW, NB power of deuterium at 95 keV. Before the beam injection experiments, discharge, and beam extraction characteristics of the ion source were investigated. The ion source has good beam optics in a broad range of beam perveance. The optimum perveance is 1.1-1.3 μP, and the minimum beam divergence angle measured by the Doppler shift spectroscopy is 0.8°. The ion species ratio is D(+):D(2)(+):D(3)(+) = 75:20:5 at beam current density of 85 mA/cm(2). The arc efficiency is more than 1.0 A∕kW. In the 2010 KSTAR campaign, a deuterium NB power of 0.7-1.5 MW was successfully injected into the KSTAR plasma with a beam energy of 70-90 keV. L-H transitions were observed within a wide range of beam powers relative to a threshold value. The edge pedestal formation in the T(i) and T(e) profiles was verified through CES and electron cyclotron emission diagnostics. In every deuterium NB injection, a burst of D-D neutrons was recorded, and increases in the ion temperature and plasma stored energy were found.

Electron beam diagnostic for profiling high power beams

DOEpatents

Elmer, John W [Danville, CA; Palmer, Todd A [Livermore, CA; Teruya, Alan T [Livermore, CA

2008-03-25

A system for characterizing high power electron beams at power levels of 10 kW and above is described. This system is comprised of a slit disk assembly having a multitude of radial slits, a conducting disk with the same number of radial slits located below the slit disk assembly, a Faraday cup assembly located below the conducting disk, and a start-stop target located proximate the slit disk assembly. In order to keep the system from over-heating during use, a heat sink is placed in close proximity to the components discussed above, and an active cooling system, using water, for example, can be integrated into the heat sink. During use, the high power beam is initially directed onto a start-stop target and after reaching its full power is translated around the slit disk assembly, wherein the beam enters the radial slits and the conducting disk radial slits and is detected at the Faraday cup assembly. A trigger probe assembly can also be integrated into the system in order to aid in the determination of the proper orientation of the beam during reconstruction. After passing over each of the slits, the beam is then rapidly translated back to the start-stop target to minimize the amount of time that the high power beam comes in contact with the slit disk assembly. The data obtained by the system is then transferred into a computer system, where a computer tomography algorithm is used to reconstruct the power density distribution of the beam.

Production of pulsed atomic oxygen beams via laser vaporization methods

NASA Technical Reports Server (NTRS)

Brinza, David E.; Coulter, Daniel R.; Liang, Ranty H.; Gupta, Amitava

1986-01-01

The generation of energetic pulsed atomic oxygen beams by laser-driven evaporation of cryogenically frozen ozone/oxygen films and thin indium-tin oxide (ITO) films is reported. Mass spectroscopy is used in the mass and energy characterization of beams from the ozone/oxygen films, and a peak flux of 3 x 10 to the 20th/sq m per sec at 10 eV is found. Analysis of the time-of-flight data suggests that several processes contribute to the formation of the oxygen beam. Results show the absence of metastable states such as the 2p(3)3s(1)(5S) level of atomic oxygen blown-off from the ITO films. The present process has application to the study of the oxygen degradation problem of LEO materials.

a Study of the Role of Large-Amplitude Motions in Unimolecular Energy Transfer Using Molecular Beam Optothermal Spectroscopy.

NASA Astrophysics Data System (ADS)

Miller, Carl Cameron

1995-01-01

The role of molecular structure in energy transfer reactions in the ground and excited electronic states was explored using optothermal spectroscopy. In the ground state, the relationship between intramolecular van der Waals interactions and vibrational mode coupling was explored in a homologous series of disubstituted ethanes, including Gg^' -2-fluoroethanol, g-1,2-difluoroethane, g-1-chloro-2-fluoroethane, t-1-chloro-2-fluoroethane, and 1,1,2-trifluoroethane. This series of substituted ethanes varies in degree of van der Waals interactions that hinder internal rotation about the C-C bond. High resolution infrared molecular beam spectroscopy was used to determine the extent of vibrational mode coupling. Perturbations in the rotational structure of these molecules provided a measure of vibrational mode coupling. We have observed that the degree of intramolecular interaction, which is dependent on the van der Waals separation of the substituents and the shape of the potential well, correlates with the extent of vibrational mode coupling. The extent of vibrational mode coupling in this series of molecules did not correlate with the density of states available for coupling. Therefore, density of states alone is insufficient to explain the observed trend. In the excited electronic state, optothermal detection has been used to observe non-radiative relaxation channels in aniline, p-bromoaniline and trans-stilbene. p-Bromoaniline has no detectable fluorescence due to a heavy atom effect which increases the rate of intersystem crossing to the triplet state. An optothermal spectrum of p-bromoaniline was observed with the origin at 32625 cm^ {-1}. For trans-stilbene the differences between the laser excitation spectrum and the optothermal spectrum of the S_1 state clearly show the onset of isomerization at ~1250 cm^{-1} above the origin. Absolute quantum yields of fluorescence, Frank-Condon factors, non -radiative rates, and radiative rates have been obtained for a series

Femtosecond Beam Sources and Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uesaka, Mitsuru

2004-12-07

Short particle beam science has been promoted by electron linac and radiation chemistry up to picoseconds. Recently, table-top TW laser enables several kinds of short particle beams and pump-and-probe analyses. 4th generation SR sources aim to generation and application of about 100 fs X-ray. Thus, femtosecond beam science has become one of the important field in advanced accelerator concepts. By using electron linac with photoinjector, about 200 fs single bunch and 3 fs multi-bunches are available. Tens femtoseconds monoenergetic electron bunch is expected by laser plasma cathode. Concerning the electron bunch diagnosis, we have seen remarkable progress in streak camera,more » coherent radiation spectroscopy, fluctuation method and E/O crystal method. Picosecond time-resolved pump-and-probe analysis by synchronizing electron linac and laser is now possible, but the timing jitter and drift due to several fluctuations in electronic devices and environment are still in picoseconds. On the other hand, the synchronization between laser and secondary beam is done passively by an optical beam-splitter in the system based on one TW laser. Therefore, the timing jitter and drift do not intrinsically exist there. The author believes that the femtosecond time-resolved pump-and-probe analysis must be initiated by the laser plasma beam sources. As to the applications, picosecond time-resolved system by electron photoinjector/linac and femtosecond laser are operating in more than 5 facilities for radiation chemistry in the world. Ti:Sapphire-laser-based repetitive pump-and-probe analysis started by time-resolved X-ray diffraction to visualize the atomic motion. Nd:Glass-laser-based single-shot analysis was performed to visualize the laser ablation via the single-shot ion imaging. The author expects that protein dynamics and ultrafast nuclear physics would be the next interesting targets. Monograph titled 'Femtosecond Beam Science' is published by Imperial College Press

Auger spectroscopy analysis of lubrication with zinc dialkyldithiophosphate of several metal combinations in sliding contact

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1979-01-01

Sliding friction experiments were conducted with aluminum and other riders rubbing on disks of various elemental metals in the presence of a thin film of zinc dialkyldithiophosphate (ZDP). Auger emission spectroscopy was used to in situ monitor the changes in surface chemistry with rubbing under various loads. The metal disks examined included iron, titanium, rhodium, tungsten, molybdenum, and copper. For equivalent films of ZDP the film is a more effective lubricant for some metals than it is for others. The important active element in the compound varies with the metal lubricated and is a function of metal chemistry. The zinc in the ZDP is susceptible to electron beam induced desorption.

Annular Focused Electron/Ion Beams for Combining High Spatial Resolution with High Probe Current.

PubMed

Khursheed, Anjam; Ang, Wei Kean

2016-10-01

This paper presents a proposal for reducing the final probe size of focused electron/ion beam columns that are operated in a high primary beam current mode where relatively large final apertures are used, typically required in applications such as electron beam lithography, focused ion beams, and electron beam spectroscopy. An annular aperture together with a lens corrector unit is used to replace the conventional final hole-aperture, creating an annular ring-shaped primary beam. The corrector unit is designed to eliminate the first- and second-order geometric aberrations of the objective lens, and for the same probe current, the final geometric aberration limited spot size is predicted to be around a factor of 50 times smaller than that of the corresponding conventional hole-aperture beam. Direct ray tracing simulation is used to illustrate how a three-stage core lens corrector can be used to eliminate the first- and second-order geometric aberrations of an electric Einzel objective lens.

Design of charge exchange recombination spectroscopy for the joint Texas experimental tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chi, Y.; Zhuang, G., E-mail: ge-zhuang@hust.edu.cn; Cheng, Z. F.

The old diagnostic neutral beam injector first operated at the University of Texas at Austin is ready for rejoining the joint Texas experimental tokamak (J-TEXT). A new set of high voltage power supplies has been equipped and there is no limitation for beam modulation or beam pulse duration henceforth. Based on the spectra of fully striped impurity ions induced by the diagnostic beam the design work for toroidal charge exchange recombination spectroscopy (CXRS) system is presented. The 529 nm carbon VI (n = 8 − 7 transition) line seems to be the best choice for ion temperature and plasma rotationmore » measurements and the considered hardware is listed. The design work of the toroidal CXRS system is guided by essential simulation of expected spectral results under the J-TEXT tokamak operation conditions.« less

A Study of the Effect of Preschool Children's Participation in Sensorimotor Activities on Their Understanding of the Mechanical Equilibrium of a Balance Beam

ERIC Educational Resources Information Center

Hadzigeorgiou, Yannis; Anastasiou, Leonidas; Konsolas, Manos; Prevezanou, Barbara

2009-01-01

The purpose of this study was to investigate whether participation in sensorimotor activities by preschool children involving their own bodily balance while walking on a beam over the floor has an effect on their understanding of the mechanical equilibrium of a balance beam. The balance beam consisted of a horizontal stick balancing around its…

Overview of the negative ion based neutral beam injectors for ITER.

PubMed

Schunke, B; Boilson, D; Chareyre, J; Choi, C-H; Decamps, H; El-Ouazzani, A; Geli, F; Graceffa, J; Hemsworth, R; Kushwah, M; Roux, K; Shah, D; Singh, M; Svensson, L; Urbani, M

2016-02-01

The ITER baseline foresees 2 Heating Neutral Beams (HNB's) based on 1 MeV 40 A D(-) negative ion accelerators, each capable of delivering 16.7 MW of deuterium atoms to the DT plasma, with an optional 3rd HNB injector foreseen as a possible upgrade. In addition, a dedicated diagnostic neutral beam will be injecting ≈22 A of H(0) at 100 keV as the probe beam for charge exchange recombination spectroscopy. The integration of the injectors into the ITER plant is nearly finished necessitating only refinements. A large number of components have passed the final design stage, manufacturing has started, and the essential test beds-for the prototype route chosen-will soon be ready to start.

Recent progress of laser spectroscopy experiments on antiprotonic helium

NASA Astrophysics Data System (ADS)

Hori, Masaki

2018-03-01

The Atomic Spectroscopy and Collisions Using Slow Antiprotons (ASACUSA) collaboration is currently carrying out laser spectroscopy experiments on antiprotonic helium ? atoms at CERN's Antiproton Decelerator facility. Two-photon spectroscopic techniques have been employed to reduce the Doppler width of the measured ? resonance lines, and determine the atomic transition frequencies to a fractional precision of 2.3-5 parts in 109. More recently, single-photon spectroscopy of buffer-gas cooled ? has reached a similar precision. By comparing the results with three-body quantum electrodynamics calculations, the antiproton-to-electron mass ratio was determined as ?, which agrees with the known proton-to-electron mass ratio with a precision of 8×10-10. The high-quality antiproton beam provided by the future Extra Low Energy Antiproton Ring (ELENA) facility should enable further improvements in the experimental precision. This article is part of the Theo Murphy meeting issue `Antiproton physics in the ELENA era'.

Measurements and FLUKA Simulations of Bismuth, Aluminium and Indium Activation at the upgraded CERN Shielding Benchmark Facility (CSBF)

NASA Astrophysics Data System (ADS)

Iliopoulou, E.; Bamidis, P.; Brugger, M.; Froeschl, R.; Infantino, A.; Kajimoto, T.; Nakao, N.; Roesler, S.; Sanami, T.; Siountas, A.; Yashima, H.

2018-06-01

The CERN High energy AcceleRator Mixed field (CHARM) facility is situated in the CERN Proton Synchrotron (PS) East Experimental Area. The facility receives a pulsed proton beam from the CERN PS with a beam momentum of 24 GeV/c with 5·1011 protons per pulse with a pulse length of 350 ms and with a maximum average beam intensity of 6.7·1010 protons per second. The extracted proton beam impacts on a cylindrical copper target. The shielding of the CHARM facility includes the CERN Shielding Benchmark Facility (CSBF) situated laterally above the target that allows deep shielding penetration benchmark studies of various shielding materials. This facility has been significantly upgraded during the extended technical stop at the beginning of 2016. It consists now of 40 cm of cast iron shielding, a 200 cm long removable sample holder concrete block with 3 inserts for activation samples, a material test location that is used for the measurement of the attenuation length for different shielding materials as well as for sample activation at different thicknesses of the shielding materials. Activation samples of bismuth, aluminium and indium were placed in the CSBF in September 2016 to characterize the upgraded version of the CSBF. Monte Carlo simulations with the FLUKA code have been performed to estimate the specific production yields of bismuth isotopes (206 Bi, 205 Bi, 204 Bi, 203 Bi, 202 Bi, 201 Bi) from 209 Bi, 24 Na from 27 Al and 115 m I from 115 I for these samples. The production yields estimated by FLUKA Monte Carlo simulations are compared to the production yields obtained from γ-spectroscopy measurements of the samples taking the beam intensity profile into account. The agreement between FLUKA predictions and γ-spectroscopy measurements for the production yields is at a level of a factor of 2.

Active Vibration damping of Smart composite beams based on system identification technique

NASA Astrophysics Data System (ADS)

Bendine, Kouider; Satla, Zouaoui; Boukhoulda, Farouk Benallel; Nouari, Mohammed

2018-03-01

In the present paper, the active vibration control of a composite beam using piezoelectric actuator is investigated. The space state equation is determined using system identification technique based on the structure input output response provided by ANSYS APDL finite element package. The Linear Quadratic (LQG) control law is designed and integrated into ANSYS APDL to perform closed loop simulations. Numerical examples for different types of excitation loads are presented to test the efficiency and the accuracy of the proposed model.

Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion

PubMed Central

Ferrer, R.; Barzakh, A.; Bastin, B.; Beerwerth, R.; Block, M.; Creemers, P.; Grawe, H.; de Groote, R.; Delahaye, P.; Fléchard, X.; Franchoo, S.; Fritzsche, S.; Gaffney, L. P.; Ghys, L.; Gins, W.; Granados, C.; Heinke, R.; Hijazi, L.; Huyse, M.; Kron, T.; Kudryavtsev, Yu.; Laatiaoui, M.; Lecesne, N.; Loiselet, M.; Lutton, F.; Moore, I. D.; Martínez, Y.; Mogilevskiy, E.; Naubereit, P.; Piot, J.; Raeder, S.; Rothe, S.; Savajols, H.; Sels, S.; Sonnenschein, V.; Thomas, J-C; Traykov, E.; Van Beveren, C.; Van den Bergh, P.; Van Duppen, P.; Wendt, K.; Zadvornaya, A.

2017-01-01

Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we demonstrate the on-line application of atomic laser ionization spectroscopy in a supersonic gas jet, a technique suited for high-precision studies of the ground- and isomeric-state properties of nuclei located at the extremes of stability. The technique is characterized in a measurement on actinium isotopes around the N=126 neutron shell closure. A significant improvement in the spectral resolution by more than one order of magnitude is achieved in these experiments without loss in efficiency. PMID:28224987

(Proceedings) 18th Advanced ICFA Beam Dynamics Workshop on Quantum Aspects of Beam Physics (QABP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Pisin

2002-10-25

The 18th Advanced ICFA Beam Dynamics Workshop on ''Quantum Aspects of Beam Physics'' was held from October 15 to 20, 2000, in Capri, Italy. This was the second workshop under the same title. The first one was held in Monterey, California, in January, 1998. Following the footstep of the first meeting, the second one in Capri was again a tremendous success, both scientifically and socially. About 70 colleagues from astrophysics, atomic physics, beam physics, condensed matter physics, particle physics, and general relativity gathered to update and further explore the topics covered in the Monterey workshop. Namely, the following topics weremore » actively discussed: (1) Quantum Fluctuations in Beam Dynamics; (2) Photon-Electron Interaction in Beam handling; (3) Physics of Condensed Beams; (4) Beam Phenomena under Strong Fields; (5) Quantum Methodologies in Beam Physics. In addition, there was a newly introduced subject on Astro-Beam Physics and Laboratory Astrophysics.« less

The characteristics of a new negative metal ion beam source and its applications

NASA Astrophysics Data System (ADS)

Paik, Namwoong

2001-10-01

Numerous efforts at energetic thin film deposition processes using ion beams have been made to meet the demands of today's thin film industry. As one of these efforts, a new Magnetron Sputter Negative Ion Source (MSNIS) was developed. In this study, the development and the characterization of the MSNIS were investigated. Amorphous carbon films were used as a sample coating medium to evaluate the ion beam energy effect. A review of energetic Physical Vapor Deposition (PVD) techniques is presented in Chapter 1. The energetic PVD methods can be classified into two major categories: the indirect ion beam method Ion Beam Assisted Deposition (IBAD), and the direct ion beam method-Direct Ion Beam Deposition (DIBD). In this chapter, currently available DIBD processes such as Cathodic Arc, Laser Ablation, Ionized Physical Vapor Deposition (I-PVD) and Magnetron Sputter Negative Ion Source (MSNIS) are individually reviewed. The design and construction of the MSNIS is presented in chapter 2. The MSNIS is a hybrid of the conventional magnetron sputter configuration and the cesium surface ionizer. The negative sputtered ions are produced directly from the sputter target by surface ionization. In chapter 3, the ion beam and plasma characteristics of an 8″ diameter MSNIS are investigated using a retarding field analyzer and a cylindrical Langmuir Probe. The measured electron temperature is approximately 2-5 eV, while the plasma density and plasma potential were of the order of 10 11-1012 cm3 and 5-20 V, respectively, depending on the pressure and power. In chapter 4, in order to evaluate the effect of the ion beam on the resultant films, amorphous carbon films were deposited under various conditions. The structure of carbon films was investigated using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The result suggests the fraction of spa bonding is more than 70% in some samples prepared by MSNIS while magnetron sputtered samples showed less than 30%. (Abstract

Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks

NASA Astrophysics Data System (ADS)

Pace, D. C.; Austin, M. E.; Bardoczi, L.; Collins, C. S.; Crowley, B.; Davis, E.; Du, X.; Ferron, J.; Grierson, B. A.; Heidbrink, W. W.; Holcomb, C. T.; McKee, G. R.; Pawley, C.; Petty, C. C.; Podestà, M.; Rauch, J.; Scoville, J. T.; Spong, D. A.; Thome, K. E.; Van Zeeland, M. A.; Varela, J.; Victor, B.

2018-05-01

An engineering upgrade to the neutral beam system at the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] enables time-dependent programming of the beam voltage and current. Initial application of this capability involves pre-programmed beam voltage and current injected into plasmas that are known to be susceptible to instabilities that are driven by energetic ( E ≥ 40 keV) beam ions. These instabilities, here all Alfvén eigenmodes (AEs), increase the transport of the beam ions beyond a classical expectation based on particle drifts and collisions. Injecting neutral beam power, P beam ≥ 2 MW, at reduced voltage with increased current reduces the drive for Alfvénic instabilities and results in improved ion confinement. In lower-confinement plasmas, this technique is applied to eliminate the presence of AEs across the mid-radius of the plasmas. Simulations of those plasmas indicate that the mode drive is decreased and the radial extent of the remaining modes is reduced compared to a higher beam voltage case. In higher-confinement plasmas, this technique reduces AE activity in the far edge and results in an interesting scenario of beam current drive improving as the beam voltage reduces from 80 kV to 65 kV.

Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Austin, Max E.; Bardoczi, Laszlo; Collins, Cami S.

Here, an engineering upgrade to the neutral beam system at the DIII-D tokamak enables time-dependent programming of the beam voltage and current. Initial application of this capability involves pre-programmed beam voltage and current injected into plasmas that are known to be susceptible to instabilities that are driven by energetic (E ≥ 40 keV) beam ions. These instabilities, here all Alfvén eigenmodes (AEs), increase the transport of the beam ions beyond a classical expectation based on particle drifts and collisions. Injecting neutral beam power, P beam ≥ 2MW, at reduced voltage with increased current reduces the drive for Alfvénic instabilities andmore » results in improved ion confinement. In lower-confinement plasmas, this technique is applied to eliminate the presence of AEs across the mid-radius of the plasmas. Simulations of those plasmas indicate that the mode drive is decreased and the radial extent of the remaining modes is reduced compared to a higher beam voltage case. In higher-confinement plasmas, this technique reduces AE activity in the far edge and results in an interesting scenario of beam current drive improving as the beam voltage reduces from 80 kV to 65 kV.« less

Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks

DOE PAGES

Austin, Max E.; Bardoczi, Laszlo; Collins, Cami S.; ...

2018-04-20

Here, an engineering upgrade to the neutral beam system at the DIII-D tokamak enables time-dependent programming of the beam voltage and current. Initial application of this capability involves pre-programmed beam voltage and current injected into plasmas that are known to be susceptible to instabilities that are driven by energetic (E ≥ 40 keV) beam ions. These instabilities, here all Alfvén eigenmodes (AEs), increase the transport of the beam ions beyond a classical expectation based on particle drifts and collisions. Injecting neutral beam power, P beam ≥ 2MW, at reduced voltage with increased current reduces the drive for Alfvénic instabilities andmore » results in improved ion confinement. In lower-confinement plasmas, this technique is applied to eliminate the presence of AEs across the mid-radius of the plasmas. Simulations of those plasmas indicate that the mode drive is decreased and the radial extent of the remaining modes is reduced compared to a higher beam voltage case. In higher-confinement plasmas, this technique reduces AE activity in the far edge and results in an interesting scenario of beam current drive improving as the beam voltage reduces from 80 kV to 65 kV.« less

Recent work of decay spectroscopy at RIBF

NASA Astrophysics Data System (ADS)

Söderström, Pär-Anders

2014-09-01

β- and isomer-decay spectroscopy are sensitive probes of nuclear structure, and are often the only techniques capable of providing data for exotic nuclei that are producted with very low rates. Decay properties of exotic nuclei are also essential to model astrophysical events responible for the evolution of the universe such as the rp- and r-process. The EURICA project (EUROBALL RIKEN Cluster Array) has been launched in 2012 with the goal of performing spectroscopy of very exotic nuclei. Since 2012, four experimental campaigns have been successfully completed using fragmentation of 124Xe beam and in-flight-fission of 238U beam, approaching for example the key nuclei 78Ni, 110Zr, 100Sn, 128Pd, and 138Sn. This contribution highlights the experiments performed, results obtained, and discusses the future perspective of the EURICA project. In collaboration with Shunji Nishimura, Hidetada Baba, RIKEN Nishina Center; Frank Browne, Brighton University; Pieter Doornenbal, RIKEN Nishina Center; Guillaume Gey, Universite Joseph Fourier Grenoble; Tadaaki Isobe and Giuseppe Lorusso, RIKEN Nishina Center; Daniel Lubos, Technische Universitat Munchen; Kevin Mochner, University of Cologne; Zena Patel and Simon Rice, University of Surrey; Hiroyoshi Sakurai, RIKEN Nishina Center; Laura Sinclair, University of York; Toshiyuki Sumikama, Tohoku University; Jan Taprogge, Universidad Autonoma de Madrid; Zsolt Vajta, MTA Atomki; Hiroshi Watanabe, Beihang University; Jin Wu, Peking University; and Zhengyu Xu, University of Tokyo.

Discharge cell for optogalvanic spectroscopy having orthogonal relationship between the probe laser and discharge axis

NASA Technical Reports Server (NTRS)

Webster, C. R. (Inventor)

1986-01-01

A method and apparatus for an optogalvanic spectroscopy system are disclosed. Orthogonal geometry exists between the axis of a laser probe beam and the axis of a discharge created by a pair of spaced apart and longituduinally aligned high voltage electrodes. The electrodes are movable to permit adjustment of the location of a point in the discharge which is to irradiated by a laser beam crossing the discharge region. The cell dimensions are selected so that the cross section of the discharge region is substantly comparable in size to the cross section of the laser beam passing orthogonally through the discharge region.

Positron annihilation lifetime and Doppler broadening spectroscopy at the ELBE facility

NASA Astrophysics Data System (ADS)

Wagner, Andreas; Butterling, Maik; Liedke, Maciej O.; Potzger, Kay; Krause-Rehberg, Reinhard

2018-05-01

The Helmholtz-Zentrum Dresden-Rossendorf operates a superconducting linear accelerator for electrons with energies up to 35 MeV and average beam currents up to 1.6 mA with bunch charges up to 120 pC. The electron beam is employed to produce several secondary beams including X-rays from bremsstrahlung production, coherent IR light in a Free Electron Laser, superradiant THz radiation, neutrons, and positrons. The secondary positron beam after moderation feeds the Monoenergetic Positron Source (MePS) where positron annihilation lifetime (PALS) and positron annihilation Doppler-broadening experiments in materials science are performed. The adjustable repetition rate of the continuous-wave electron beams allows matching of the pulse separation to the positron lifetime in the sample under study. The energy of the positron beam can be set between 0.5 keV and 20 keV to perform depth resolved defect spectroscopy and porosity studies especially for thin films. Bulk materials, fluids, gases, and even radioactive samples can be studied at the unique Gamma-induced Positron Source (GiPS) where an intense bremsstrahlung source generates positrons directly inside the material under study. A 22Na-based monoenergetic positron beam serves for offline experiments and additional depth-resolved Doppler-broadening studies complementing both accelerator-based sources.

Spatially Resolved Imaging and Spectroscopy of Candidate Dual Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

McGurk, R. C.; Max, C. E.; Medling, A. M.; Shields, G. A.; Comerford, J. M.

2015-09-01

When galaxies merge, both central supermassive black holes are immersed in a dense and chaotic environment. If there is sufficient gas in the nuclear regions, one expects to see close pairs of active galactic nuclei (AGNs), or dual AGNs, in a fraction of galaxy mergers. However, finding them remains a challenge. The presence of double-peaked [O iii] emission lines has been proposed as a technique to select dual AGNs efficiently. We studied a sample of double-peaked narrow [O iii] emitting AGNs from Sloan Digital Sky Survey (SDSS) DR7. By obtaining new and archival high spatial resolution images taken with the Keck II Laser Guide Star Adaptive Optics system and the near-infrared camera NIRC2, we show that 30% of 140 double-peaked [O iii] emission line SDSS AGNs have two spatial components within a 3″ radius. However, spatially resolved spectroscopy or X-ray observations are needed to confirm these galaxy pairs as systems containing two AGNs. We followed up three spatially double candidate dual AGNs with integral field spectroscopy from Keck OSIRIS and 10 candidates with long-slit spectroscopy from the Shane Kast Double Spectrograph at Lick Observatory. We find that the double-peaked emission lines in our sample of 12 candidates are caused by: one dual AGN (SDSS J114642.47+511029.6), one confirmed outflow and four likely outflows, two pairs of star-forming galaxies, one candidate indeterminate due to sky line interference, and three AGNs with spatially coincident double [O iii] peaks, likely due to unresolved complex narrow line kinematics, outflows, binary AGN, or small-scale jets.

The Heidelberg compact electron beam ion traps

NASA Astrophysics Data System (ADS)

Micke, P.; Kühn, S.; Buchauer, L.; Harries, J. R.; Bücking, T. M.; Blaum, K.; Cieluch, A.; Egl, A.; Hollain, D.; Kraemer, S.; Pfeifer, T.; Schmidt, P. O.; Schüssler, R. X.; Schweiger, Ch.; Stöhlker, T.; Sturm, S.; Wolf, R. N.; Bernitt, S.; Crespo López-Urrutia, J. R.

2018-06-01

Electron beam ion traps (EBITs) are ideal tools for both production and study of highly charged ions (HCIs). In order to reduce their construction, maintenance, and operation costs, we have developed a novel, compact, room-temperature design, the Heidelberg Compact EBIT (HC-EBIT). Four already commissioned devices operate at the strongest fields (up to 0.86 T) reported for such EBITs using permanent magnets, run electron beam currents up to 80 mA, and energies up to 10 keV. They demonstrate HCI production, trapping, and extraction of pulsed Ar16+ bunches and continuous 100 pA ion beams of highly charged Xe up to charge state 29+, already with a 4 mA, 2 keV electron beam. Moreover, HC-EBITs offer large solid-angle ports and thus high photon count rates, e.g., in x-ray spectroscopy of dielectronic recombination in HCIs up to Fe24+, achieving an electron-energy resolving power of E/ΔE > 1500 at 5 keV. Besides traditional on-axis electron guns, we have also implemented a novel off-axis gun for laser, synchrotron, and free-electron laser applications, offering clear optical access along the trap axis. We report on its first operation at a synchrotron radiation facility demonstrating the resonant photoexcitation of highly charged oxygen.

Intracavity Faraday modulation spectroscopy (INFAMOS): A tool for radical detection

NASA Astrophysics Data System (ADS)

Gianella, Michele; Pinto, Tomas H. P.; Wu, Xia; Ritchie, Grant A. D.

2017-08-01

We present the intra-cavity Faraday modulation spectroscopy technique, whereby optical feedback cavity-enhanced spectroscopy is coupled with Faraday modulation spectroscopy to greatly enhance the interaction path length of a laser beam with a paramagnetic sample in a magnetic field. We describe a first prototype based upon a cw quantum cascade laser targeting a selection of fundamental rovibrational R-branch transitions of nitric oxide (1890 cm-1), consisting of a linear cavity (finesse F =6300 ) and a water-cooled solenoid. We demonstrate a minimum detectable Verdet constant of Vmin=4.7 ×10-14 rad cm-1 G-1 H z-1/2 (at SNR = 1), corresponding to a single-pass rotation angle of 1.6 ×10-10 rad Hz-1/2 and a limit of detection of 0.21 ppbv Hz-1/2 NO.

Intracavity Faraday modulation spectroscopy (INFAMOS): A tool for radical detection.

PubMed

Gianella, Michele; Pinto, Tomas H P; Wu, Xia; Ritchie, Grant A D

2017-08-07

We present the intra-cavity Faraday modulation spectroscopy technique, whereby optical feedback cavity-enhanced spectroscopy is coupled with Faraday modulation spectroscopy to greatly enhance the interaction path length of a laser beam with a paramagnetic sample in a magnetic field. We describe a first prototype based upon a cw quantum cascade laser targeting a selection of fundamental rovibrational R-branch transitions of nitric oxide (1890 cm -1 ), consisting of a linear cavity (finesse F=6300) and a water-cooled solenoid. We demonstrate a minimum detectable Verdet constant of V min =4.7×10 -14  rad cm -1  G -1  Hz -1/2 (at SNR = 1), corresponding to a single-pass rotation angle of 1.6×10 -10  rad Hz -1/2 and a limit of detection of 0.21 ppbv Hz -1/2 NO.

Doubly resonant three-wave-mixing spectroscopy of a chiral coupled-chromophore system in solution: coherent two-dimensional optical activity spectroscopy.

PubMed

Cheon, Sangheon; Lee, Hochan; Choi, Jun-Ho; Cho, Minhaeng

2007-02-07

Theoretical descriptions of doubly resonant two-dimensional (2D) sum-frequency-generation (SFG) and difference-frequency-generation (DFG) spectroscopies of coupled-chromophore systems are presented. Despite that each electronic or vibrational chromophore is achiral, the interaction-induced chirality of a coupled multichromophore system in solution can be measured by using the doubly resonant 2D three-wave-mixing (3WM) spectroscopic method. An electronically coupled dimer, where each monomer is modeled as a simple two-level system, can have nonvanishing SFG (or DFG) properties, e.g., susceptibility in frequency domain or nonlinear response function in time domain, if the induced dipole vector of the dimer is not orthogonal to the vector product of the two monomer electronic transition dipole vectors. In order to demonstrate that these 2D 3WM spectroscopic methods can be used to determine the solution structure of a polypeptide, the authors carried out quantum chemistry calculations for an alanine dipeptide and obtained first- and second-order dipole derivatives associated with the amide I vibrational transitions of the dipeptide. It is shown that the numerically simulated 2D IR-IR SFG spectrum is highly sensitive to the dipeptide secondary structure and provides rich information on the one- and two-exciton states. It is believed that the theoretically proposed doubly resonant 2D 3WM spectroscopy, which can be considered to be an optical activity spectroscopy, will be of use in studying both structural and dynamical aspects of coupled multichromophore systems, such as proteins, nucleic acids, nanoparticle aggregates etc.

Advanced techniques for characterization of ion beam modified materials

DOE PAGES

Zhang, Yanwen; Debelle, Aurélien; Boulle, Alexandre; ...

2014-10-30

Understanding the mechanisms of damage formation in materials irradiated with energetic ions is essential for the field of ion-beam materials modification and engineering. Utilizing incident ions, electrons, photons, and positrons, various analysis techniques, including Rutherford backscattering spectrometry (RBS), electron RBS, Raman spectroscopy, high-resolution X-ray diffraction, small-angle X-ray scattering, and positron annihilation spectroscopy, are routinely used or gaining increasing attention in characterizing ion beam modified materials. The distinctive information, recent developments, and some perspectives in these techniques are reviewed in this paper. Applications of these techniques are discussed to demonstrate their unique ability for studying ion-solid interactions and the corresponding radiationmore » effects in modified depths ranging from a few nm to a few tens of μm, and to provide information on electronic and atomic structure of the materials, defect configuration and concentration, as well as phase stability, amorphization and recrystallization processes. Finally, such knowledge contributes to our fundamental understanding over a wide range of extreme conditions essential for enhancing material performance and also for design and synthesis of new materials to address a broad variety of future energy applications.« less

Range degradation and distal edge behavior of proton radiotherapy beams using 11C activation and Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Elmekawy, Ahmed Farouk

The distal edge of therapeutic proton radiation beams was investigated by different methods. Proton beams produced at the Hampton University Proton Therapy Institute (HUPTI) were used to irradiate a Polymethylmethacrylate (PMMA) phantom for three different ranges (13.5, 17.0 and 21.0 cm) to investigate the distal slope dependence of the Bragg peak. The activation of 11 C was studied by scanning the phantom less than 10 minutes post-irradiation with a Philips Big Bore Gemini(c) PET/CT. The DICOM images were imported into the Varian Eclipse(c) Treatment Planning System (TPS) for analysis and then analyzed by ImageJ(c) . The distal slope ranged from ?0.1671 +/- 0.0036 to -0.1986 +/- 0.0052 (pixel intensity/slice number) for ranges 13.5 to 21.0 cm respectively. A realistic description of the setup was modeled using the GATE 7.0 Monte Carlo simulation tool and compared to the experiment data. The results show the distal slope ranged from -0.1158+/-0.0133 to -0.0787+/-0.002 (Gy/mm). Additionally, low activity, 11C were simulated to study the 11C reconstructed half-life dependence versus the initial activity for six ranges chosen around the previous activation study. The results of the expected/nominal half-life vs. activity ranged from -5 x 10-4 +/- 2.8104 x 10-4 to 1.6 x 10-3 +/- 9.44 x 10-4 (%diff./Bq). The comparison between two experiments with proton beams on a PMMA phantom and multi-layer ion chamber, and two GATE simulations of a proton beam incident on a water phantom and 11C PET study show that: (i) the distal fall-off variation of the steepness of the slopes are found to be similar thus validating the sensitivity of the PET technique to the range degradation and (ii) the average of the super-ratios difference between all studies observed is primarily due to the difference in the dose deposited in the media.

Atomic and Molecular Spectroscopic Studies of the DIII-D Neutral Beam Ion Source and Neutralizer

NASA Astrophysics Data System (ADS)

Crowley, B.; Rauch, J.; Scoville, J. T.; Sharma, S. K.; Choksi, B.

2015-11-01

The neutral beam system is interesting in that it comprises two distinct low temperature plasmas. Firstly, the ion source is typically a filament or RF driven plasma from which ions are extracted by a high voltage accelerator grid system. Secondly the neutralizer is essentially a low temperature plasma system with the beam serving as the primary ionization source and the neutralizer walls serving as conducting boundaries. Atomic spectroscopy of Doppler shifted D-alpha light emanating from the fast atoms is studied to determine the composition of the source and the divergence of the beam. Molecular spectroscopy involves measuring fine structure in electron-vibrational rotational bands. The technique has applications in low temperature plasmas and here it is used to determine gas temperature in the neutralizer. We describe the experimental set-up and the physics model used to relate the spectroscopic data to the plasma parameters and we present results of recent experiments exploring how to increase neutralization efficiency. Supported by the US DOE under DE-FC02-04ER54698.

Active Control of the Forced and Transient Response of a Finite Beam. M.S. Thesis

NASA Technical Reports Server (NTRS)

Post, John Theodore

1989-01-01

When studying structural vibrations resulting from a concentrated source, many structures may be modelled as a finite beam excited by a point source. The theoretical limit on cancelling the resulting beam vibrations by utilizing another point source as an active controller is explored. Three different types of excitation are considered, harmonic, random, and transient. In each case, a cost function is defined and minimized for numerous parameter variations. For the case of harmonic excitation, the cost function is obtained by integrating the mean squared displacement over a region of the beam in which control is desired. A controller is then found to minimize this cost function in the control interval. The control interval and controller location are continuously varied for several frequencies of excitation. The results show that control over the entire beam length is possible only when the excitation frequency is near a resonant frequency of the beam, but control over a subregion may be obtained even between resonant frequencies at the cost of increasing the vibration outside of the control region. For random excitation, the cost function is realized by integrating the expected value of the displacement squared over the interval of the beam in which control is desired. This is shown to yield the identical cost function as obtained by integrating the cost function for harmonic excitation over all excitation frequencies. As a result, it is always possible to reduce the cost function for random excitation whether controlling the entire beam or just a subregion, without ever increasing the vibration outside the region in which control is desired. The last type of excitation considered is a single, transient pulse. A cost function representative of the beam vibration is obtained by integrating the transient displacement squared over a region of the beam and over all time. The form of the controller is chosen a priori as either one or two delayed pulses. Delays

Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope.

PubMed

Bäcke, Olof; Lindqvist, Camilla; de Zerio Mendaza, Amaia Diaz; Gustafsson, Stefan; Wang, Ergang; Andersson, Mats R; Müller, Christian; Kristiansen, Per Magnus; Olsson, Eva

2017-05-01

We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices. To investigate how electron irradiation affects the thermal stability of polymer:fullerene films, a model bulk-heterojunction film based on a thiophene-quinoxaline copolymer and a fullerene derivative was heat-treated in-situ in a transmission electron microscope. In areas of the film that exposed to the electron beam the nanostructure of the film remained stable, while the nanostructure in areas not exposed to the electron beam underwent large phase separation and nucleation of fullerene crystals. UV-vis spectroscopy shows that the polymer:fullerene films are stable for electron doses up to 2000kGy. Copyright © 2016 Elsevier B.V. All rights reserved.

Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope.

PubMed

Bäcke, Olof; Lindqvist, Camilla; de Zerio Mendaza, Amaia Diaz; Gustafsson, Stefan; Wang, Ergang; Andersson, Mats R; Müller, Christian; Kristiansen, Per Magnus; Olsson, Eva

2017-02-01

We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices. To investigate how electron irradiation affects the thermal stability of polymer:fullerene films, a model bulk-heterojunction film based on a thiophene-quinoxaline copolymer and a fullerene derivative was heat-treated in-situ in a transmission electron microscope. In areas of the film that exposed to the electron beam the nanostructure of the film remained stable, while the nanostructure in areas not exposed to the electron beam underwent large phase separation and nucleation of fullerene crystals. UV-vis spectroscopy shows that the polymer:fullerene films are stable for electron doses up to 2000kGy. Copyright © 2017 Elsevier B.V. All rights reserved.

In situ ion-beam-induced luminescence analysis for evaluating a micrometer-scale radio-photoluminescence glass dosimeter

NASA Astrophysics Data System (ADS)

Kawabata, Shunsuke; Kada, Wataru; Parajuli, Raj Kumar; Matsubara, Yoshinori; Sakai, Makoto; Miura, Kenta; Satoh, Takahiro; Koka, Masashi; Yamada, Naoto; Kamiya, Tomihiro; Hanaizumi, Osamu

2016-06-01

Micrometer-scale responses of radio-photoluminescence (RPL) glass dosimeters to focused ionized particle radiation were evaluated by combining ion-beam-induced luminescence (IBIL) and proton beam writing (PBW) using a 3 MeV focused proton microbeam. RPL phosphate glass dosimeters doped with ionic Ag or Cu activators at concentrations of 0.2 and 0.1% were fabricated, and their scintillation intensities were evaluated by IBIL spectroscopy under a PBW micropatterning condition. Compared with the Ag-doped dosimeter, the Cu-doped dosimeter was more tolerant of the radiation, while the peak intensity of its luminescence was lower, under the precise dose control of the proton microprobe. Proton-irradiated areas were successfully recorded using these dosimeters and their RPL centers were visualized under 375 nm ultraviolet light. The reproduction of the irradiated region by post-RPL imaging suggests that precise estimation of irradiation dose using microdosimeters can be accomplished by optimizing RPL glass dosimeters for various proton microprobe applications in organic material analysis and in micrometer-scale material modifications.

A Coupled Layerwise Analysis of the Thermopiezoelectric Response of Smart Composite Beams Beams

NASA Technical Reports Server (NTRS)

Lee, H.-J.; Saravanos, D. A.

1995-01-01

Thermal effects are incorporated into previously developed discrete layer mechanics for piezoelectric composite beam structures. The updated mechanics explicitly account for the complete coupled thermoelectromechanical response of smart composite beams. This unified representation leads to an inherent capability to model both the sensory and actuator responses of piezoelectric composite beams in a thermal environment. Finite element equations are developed and numerical results are presented to demonstrate the capability of the current formulation to represent the behavior of both sensory and active smart structures under thermal loadings.

Cryogenically cooled octupole ion trap for spectroscopy of biomolecular ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyarkin, Oleg V., E-mail: oleg.boiarkin@epfl.ch; Kopysov, Vladimir

2014-03-15

We present here the design of a linear octupole ion trap, suitable for collisional cryogenic cooling and spectroscopy of large ions. The performance of this trap has been assessed using ultraviolet (UV) photofragmentation spectroscopy of protonated dipeptides. At the trap temperature of 6.1 K, the vibrational temperature of the ions reaches 9.1 K, although their estimated translational temperature is ∼150 K. This observation suggests that, despite the significant translational heating by radio-frequency electrical field, vibrational cooling of heavy ions in the octupole is at least as efficient as in the 22-pole ion traps previously used in our laboratory. In contrastmore » to the 22-pole traps, excellent radial confinement of ions in the octupole makes it convenient for laser spectroscopy and boosts the dissociation yield of the stored ions to 30%. Overlap of the entire ion cloud by the laser beam in the octupole also allows for efficient UV depletion spectroscopy of ion–He clusters. The measured electronic spectra of the dipeptides and the clusters differ drastically, complicating a use of UV tagging spectroscopy for structural determination of large species.« less

Ultrashort megaelectronvolt positron beam generation based on laser-accelerated electrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Tongjun; Shen, Baifei, E-mail: bfshen@mail.shcnc.ac.cn; Xu, Jiancai, E-mail: jcxu@siom.ac.cn

Experimental generation of ultrashort MeV positron beams with high intensity and high density using a compact laser-driven setup is reported. A high-density gas jet is employed experimentally to generate MeV electrons with high charge; thus, a charge-neutralized MeV positron beam with high density is obtained during laser-accelerated electrons irradiating high-Z solid targets. It is a novel electron–positron source for the study of laboratory astrophysics. Meanwhile, the MeV positron beam is pulsed with an ultrashort duration of tens of femtoseconds and has a high peak intensity of 7.8 × 10{sup 21} s{sup −1}, thus allows specific studies of fast kinetics in millimeter-thick materials withmore » a high time resolution and exhibits potential for applications in positron annihilation spectroscopy.« less

Particle beam experiments for the analysis of reactive sputtering processes in metals and polymer surfaces

NASA Astrophysics Data System (ADS)

Corbella, Carles; Grosse-Kreul, Simon; Kreiter, Oliver; de los Arcos, Teresa; Benedikt, Jan; von Keudell, Achim

2013-10-01

A beam experiment is presented to study heterogeneous reactions relevant to plasma-surface interactions in reactive sputtering applications. Atom and ion sources are focused onto the sample to expose it to quantified beams of oxygen, nitrogen, hydrogen, noble gas ions, and metal vapor. The heterogeneous surface processes are monitored in situ by means of a quartz crystal microbalance and Fourier transform infrared spectroscopy. Two examples illustrate the capabilities of the particle beam setup: oxidation and nitriding of aluminum as a model of target poisoning during reactive magnetron sputtering, and plasma pre-treatment of polymers (PET, PP).

Oxidation of silicon with a 5 eV O(-) beam

NASA Technical Reports Server (NTRS)

Hecht, M. H.; Orient, O. J.; Chutjian, A.; Vasquez, R. P.

1989-01-01

A silicon wafer has been oxidized at room temperature in vacuum using a pure, ground-state beam of O(-) ions. The beam was of sufficiently low energy that no displacement damage or implantation was energetically possible. The resulting SiO2 films were analyzed with X-ray photoelectron spectroscopy. A logarithmic dependence of oxide thickness on dose was observed, with an extrapolated oxidation efficiency of unity for the clean silicon surface. A distinct initial oxidation phase was observed, with an anomalously high level of silicon suboxides. In addition, the valence-band offset between the silicon and the oxide was unusually small, suggesting a large interfacial dipole.

In situ electron-beam polymerization stabilized quantum dot micelles.

PubMed

Travert-Branger, Nathalie; Dubois, Fabien; Renault, Jean-Philippe; Pin, Serge; Mahler, Benoit; Gravel, Edmond; Dubertret, Benoit; Doris, Eric

2011-04-19

A polymerizable amphiphile polymer containing PEG was synthesized and used to encapsulate quantum dots in micelles. The quantum dot micelles were then polymerized using a "clean" electron beam process that did not require any post-irradiation purification. Fluorescence spectroscopy revealed that the polymerized micelles provided an organic coating that preserved the quantum dot fluorescence better than nonpolymerized micelles, even under harsh conditions. © 2011 American Chemical Society

Integrated control system for electron beam processes

NASA Astrophysics Data System (ADS)

Koleva, L.; Koleva, E.; Batchkova, I.; Mladenov, G.

2018-03-01

The ISO/IEC 62264 standard is widely used for integration of the business systems of a manufacturer with the corresponding manufacturing control systems based on hierarchical equipment models, functional data and manufacturing operations activity models. In order to achieve the integration of control systems, formal object communication models must be developed, together with manufacturing operations activity models, which coordinate the integration between different levels of control. In this article, the development of integrated control system for electron beam welding process is presented as part of a fully integrated control system of an electron beam plant, including also other additional processes: surface modification, electron beam evaporation, selective melting and electron beam diagnostics.

Development of Two-Photon Pump Polarization Spectroscopy Probe Technique Tpp-Psp for Measurements of Atomic Hydrogen .

NASA Astrophysics Data System (ADS)

Satija, Aman; Lucht, Robert P.

2015-06-01

Atomic hydrogen (H) is a key radical in combustion and plasmas. Accurate knowledge of its concentration can be used to better understand transient phenomenon such as ignition and extinction in combustion environments. Laser induced polarization spectroscopy is a spatially resolved absorption technique which we have adapted for quantitative measurements of H atom. This adaptation is called two-photon pump, polarization spectroscopy probe technique (TPP-PSP) and it has been implemented using two different laser excitation schemes. The first scheme involves the two-photon excitation of 1S-2S transitions using a linearly polarized 243-nm beam. An anisotropy is created amongst Zeeman states in 2S-3P levels using a circularly polarized 656-nm pump beam. This anisotropy rotates the polarization of a weak, linearly polarized probe beam at 656 nm. As a result, the weak probe beam "leaks" past an analyzer in the detection channel and is measured using a PMT. This signal can be related to H atom density in the probe volume. The laser beams were created by optical parametric generation followed by multiple pulse dye amplification stages. This resulted in narrow linewidth beams which could be scanned in frequency domain and varied in energy. This allowed us to systematically investigate saturation and Stark effect in 2S-3P transitions with the goal of developing a quantitative H atom measurement technique. The second scheme involves the two-photon excitation of 1S-2S transitions using a linearly polarized 243-nm beam. An anisotropy is created amongst Zeeman states in 2S-4P transitions using a circularly polarized 486-nm pump beam. This anisotropy rotates the polarization of a weak, linearly polarized probe beam at 486 nm. As a result the weak probe beam "leaks" past an analyzer in the detection channel and is measured using a PMT. This signal can be related to H atom density in the probe volume. A dye laser was pumped by third harmonic of a Nd:YAG laser to create a laser beam

Overview of the negative ion based neutral beam injectors for ITER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schunke, B., E-mail: email@none.edu; Boilson, D.; Chareyre, J.

2016-02-15

The ITER baseline foresees 2 Heating Neutral Beams (HNB’s) based on 1 MeV 40 A D{sup −} negative ion accelerators, each capable of delivering 16.7 MW of deuterium atoms to the DT plasma, with an optional 3rd HNB injector foreseen as a possible upgrade. In addition, a dedicated diagnostic neutral beam will be injecting ≈22 A of H{sup 0} at 100 keV as the probe beam for charge exchange recombination spectroscopy. The integration of the injectors into the ITER plant is nearly finished necessitating only refinements. A large number of components have passed the final design stage, manufacturing has started,more » and the essential test beds—for the prototype route chosen—will soon be ready to start.« less

Characterization of Noble Gas Ion Beam Fabricated Single Molecule Nanopore Detectors

NASA Astrophysics Data System (ADS)

Rollings, Ryan; Ledden, Bradley; Shultz, John; Fologea, Daniel; Li, Jiali; Chervinsky, John; Golovchenko, Jene

2006-03-01

Nanopores fabricated with low energy noble gas ion beams in a silicon nitride membrane can be employed as the fundamental element of single biomolecule detection and characterization devices [1,2]. With the help of X-ray Photoelectron Spectroscopy (XPS) and Rutherford Backscattering (RBS), we demonstrate that the electrical noise properties, and hence ultimate sensitivity of nanopore single molecule detectors depends on ion beam species and nanopore annealing conditions. .1. Li, J., D. Stein, C. McMullan, D. Branton, M.J. Aziz, and J.A. Golovchenko, Ion-beam sculpting at nanometre length scales. Nature, 2001. 412(12 July): p. 166-169. 2. Li, J., M. Gershow, D. Stein, E. Brandin, and J.A. Golovchenko, DNA Molecules and Configurations in a Solid-state Nanopore Microscope. Nature Materials, 2003. 2: p. 611-615.

Full-beam performances of a PET detector with synchrotron therapeutic proton beams.

PubMed

Piliero, M A; Pennazio, F; Bisogni, M G; Camarlinghi, N; Cerello, P G; Del Guerra, A; Ferrero, V; Fiorina, E; Giraudo, G; Morrocchi, M; Peroni, C; Pirrone, G; Sportelli, G; Wheadon, R

2016-12-07

Treatment quality assessment is a crucial feature for both present and next-generation ion therapy facilities. Several approaches are being explored, based on prompt radiation emission or on PET signals by [Formula: see text]-decaying isotopes generated by beam interactions with the body. In-beam PET monitoring at synchrotron-based ion therapy facilities has already been performed, either based on inter-spill data only, to avoid the influence of the prompt radiation, or including both in-spill and inter-spill data. However, the PET images either suffer of poor statistics (inter-spill) or are more influenced by the background induced by prompt radiation (in-spill). Both those problems are expected to worsen for accelerators with improved duty cycle where the inter-spill interval is reduced to shorten the treatment time. With the aim of assessing the detector performance and developing techniques for background reduction, a test of an in-beam PET detector prototype was performed at the CNAO synchrotron-based ion therapy facility in full-beam acquisition modality. Data taken with proton beams impinging on PMMA phantoms showed the system acquisition capability and the resulting activity distribution, separately reconstructed for the in-spill and the inter-spill data. The coincidence time resolution for in-spill and inter-spill data shows a good agreement, with a slight deterioration during the spill. The data selection technique allows the identification and rejection of most of the background originated during the beam delivery. The activity range difference between two different proton beam energies (68 and 72 MeV) was measured and found to be in sub-millimeter agreement with the expected result. However, a slightly longer (2 mm) absolute profile length is obtained for in-spill data when compared to inter-spill data.

Future prospects of nuclear reactions induced by gamma-ray beams at ELI-NP

NASA Astrophysics Data System (ADS)

Filipescu, D.; Balabanski, D. L.; Camera, F.; Gheorghe, I.; Ghita, D.; Glodariu, T.; Kaur, J.; Ur, C. A.; Utsunomiya, H.; Varlamov, V. V.

2017-01-01

The future prospects of photonuclear reactions studies at the new Extreme Light Infrastructure—Nuclear Physics (ELI-NP) facility are discussed in view of the pursuit of investigating the electromagnetic response of nuclei using γ-ray beams of unprecedented energy resolution and intensity characteristics. We present here the features of the γ-ray beam source, the emerging ELI-NP experimental program involving photonuclear reactions cross section measurements and spectroscopy and angular measurements of γ-rays and neutrons along with the detection arrays currently under implementation.

Diamond sensors and polycapillary lenses for X-ray absorption spectroscopy.

PubMed

Ravel, B; Attenkofer, K; Bohon, J; Muller, E; Smedley, J

2013-10-01

Diamond sensors are evaluated as incident beam monitors for X-ray absorption spectroscopy experiments. These single crystal devices pose a challenge for an energy-scanning experiment using hard X-rays due to the effect of diffraction from the crystalline sensor at energies which meet the Bragg condition. This problem is eliminated by combination with polycapillary lenses. The convergence angle of the beam exiting the lens is large compared to rocking curve widths of the diamond. A ray exiting one capillary from the lens meets the Bragg condition for any reflection at a different energy from the rays exiting adjacent capillaries. This serves to broaden each diffraction peak over a wide energy range, allowing linear measurement of incident intensity over the range of the energy scan. Extended X-ray absorption fine structure data are measured with a combination of a polycapillary lens and a diamond incident beam monitor. These data are of comparable quality to data measured without a lens and with an ionization chamber monitoring the incident beam intensity.

Propagation-invariant beams with quantum pendulum spectra: from Bessel beams to Gaussian beam-beams.

PubMed

Dennis, Mark R; Ring, James D

2013-09-01

We describe a new class of propagation-invariant light beams with Fourier transform given by an eigenfunction of the quantum mechanical pendulum. These beams, whose spectra (restricted to a circle) are doubly periodic Mathieu functions in azimuth, depend on a field strength parameter. When the parameter is zero, pendulum beams are Bessel beams, and as the parameter approaches infinity, they resemble transversely propagating one-dimensional Gaussian wave packets (Gaussian beam-beams). Pendulum beams are the eigenfunctions of an operator that interpolates between the squared angular momentum operator and the linear momentum operator. The analysis reveals connections with Mathieu beams, and insight into the paraxial approximation.

Optical trapping, pulling, and Raman spectroscopy of airborne absorbing particles based on negative photophoretic force

NASA Astrophysics Data System (ADS)

Chen, Gui-hua; He, Lin; Wu, Mu-ying; Yang, Guang; Li, Y. Q.

2017-08-01

Optical pulling is the attraction of objects back to the light source by the use of optically induced "negative forces". The light-induced photophoretic force is generated by the momentum transfer between the heating particles and surrounding gas molecules and can be several orders of magnitude larger than the radiation force and gravitation force. Here, we demonstrate that micron-sized absorbing particles can be optically pulled and manipulated towards the light source over a long distance in air with a collimated Gaussian laser beam based on a negative photophoretic force. A variety of airborne absorbing particles can be pulled by this optical pipeline to the region where they are optically trapped with another focused laser beam and their chemical compositions are characterized with Raman spectroscopy. We found that micron-sized particles are pulled over a meter-scale distance in air with a pulling speed of 1-10 cm/s in the optical pulling pipeline and its speed can be controlled by changing the laser intensity. When an aerosol particle is optically trapped with a focused Gaussian beam, we measured its rotation motion around the laser propagation direction and measured its Raman spectroscopy for chemical identification by molecular fingerprints. The centripetal acceleration of the trapped particle as high as 20 times the gravitational acceleration was observed. Optical pulling over large distances with lasers in combination with Raman spectroscopy opens up potential applications for the collection and identification of atmospheric particles.

Methanogenic activity tests by Infrared Tunable Diode Laser Absorption Spectroscopy.

PubMed

Martinez-Cruz, Karla; Sepulveda-Jauregui, Armando; Escobar-Orozco, Nayeli; Thalasso, Frederic

2012-10-01

Methanogenic activity (MA) tests are commonly carried out to estimate the capability of anaerobic biomass to treat effluents, to evaluate anaerobic activity in bioreactors or natural ecosystems, or to quantify inhibitory effects on methanogenic activity. These activity tests are usually based on the measurement of the volume of biogas produced by volumetric, pressure increase or gas chromatography (GC) methods. In this study, we present an alternative method for non-invasive measurement of methane produced during activity tests in closed vials, based on Infrared Tunable Diode Laser Absorption Spectroscopy (MA-TDLAS). This new method was tested during model acetoclastic and hydrogenotrophic methanogenic activity tests and was compared to a more traditional method based on gas chromatography. From the results obtained, the CH(4) detection limit of the method was estimated to 60 ppm and the minimum measurable methane production rate was estimated to 1.09(.)10(-3) mg l(-1) h(-1), which is below CH(4) production rate usually reported in both anaerobic reactors and natural ecosystems. Additionally to sensitivity, the method has several potential interests compared to more traditional methods among which short measurements time allowing the measurement of a large number of MA test vials, non-invasive measurements avoiding leakage or external interferences and similar cost to GC based methods. It is concluded that MA-TDLAS is a promising method that could be of interest not only in the field of anaerobic digestion but also, in the field of environmental ecology where CH(4) production rates are usually very low. Copyright © 2012 Elsevier B.V. All rights reserved.

Non-mechanical optical path switching and its application to dual beam spectroscopy including gas filter correlation radiometry

NASA Technical Reports Server (NTRS)

Sachse, Glen W. (Inventor); Wang, Liang-Guo (Inventor)

1992-01-01

A non-mechanical optical switch is developed for alternately switching a monochromatic or quasi-monochromatic light beam along two optical paths. A polarizer polarizes light into a single, e.g., vertical component which is then rapidly modulated into vertical and horizontal components by a polarization modulator. A polarization beam splitter then reflects one of these components along one path and transmits the other along the second path. In the specific application of gas filter correlation radiometry, one path is directed through a vacuum cell and one path is directed through a gas correlation cell containing a desired gas. Reflecting mirrors cause these two paths to intersect at a second polarization beam splitter which reflects one component and transmits the other to recombine them into a polarization modulated beam which can be detected by an appropriate single sensor.

Chitin and Cellulose Processing in Low-Temperature Electron Beam Plasma.

PubMed

Vasilieva, Tatiana; Chuhchin, Dmitry; Lopatin, Sergey; Varlamov, Valery; Sigarev, Andrey; Vasiliev, Michael

2017-11-06

Polysaccharide processing by means of low-temperature Electron Beam Plasma (EBP) is a promising alternative to the time-consuming and environmentally hazardous chemical hydrolysis in oligosaccharide production. The present paper considers mechanisms of the EBP-stimulated destruction of crab shell chitin, cellulose sulfate, and microcrystalline cellulose, as well as characterization of the produced oligosaccharides. The polysaccharide powders were treated in oxygen EBP for 1-20 min at 40 °C in a mixing reactor placed in the zone of the EBP generation. The chemical structure and molecular mass of the oligosaccharides were analyzed by size exclusion and the reversed phase chromatography, FTIR-spectroscopy, XRD-, and NMR-techniques. The EBP action on original polysaccharides reduces their crystallinity index and polymerization degree. Water-soluble products with lower molecular weight chitooligosaccharides (weight-average molecular mass, M w = 1000-2000 Da and polydispersity index 2.2) and cellulose oligosaccharides with polymerization degrees 3-10 were obtained. The ¹H-NMR analysis revealed 25-40% deacetylation of the EBP-treated chitin and FTIR-spectroscopy detected an increase of carbonyl- and carboxyl-groups in the oligosaccharides produced. Possible reactions of β-1,4-glycosidic bonds' destruction due to active oxygen species and high-energy electrons are given.

Flash spectroscopy of purple membrane.

PubMed Central

Xie, A H; Nagle, J F; Lozier, R H

1987-01-01

Flash spectroscopy data were obtained for purple membrane fragments at pH 5, 7, and 9 for seven temperatures from 5 degrees to 35 degrees C, at the magic angle for actinic versus measuring beam polarizations, at fifteen wavelengths from 380 to 700 nm, and for about five decades of time from 1 microsecond to completion of the photocycle. Signal-to-noise ratios are as high as 500. Systematic errors involving beam geometries, light scattering, absorption flattening, photoselection, temperature fluctuations, partial dark adaptation of the sample, unwanted actinic effects, and cooperativity were eliminated, compensated for, or are shown to be irrelevant for the conclusions. Using nonlinear least squares techniques, all data at one temperature and one pH were fitted to sums of exponential decays, which is the form required if the system obeys conventional first-order kinetics. The rate constants obtained have well behaved Arrhenius plots. Analysis of the residual errors of the fitting shows that seven exponentials are required to fit the data to the accuracy of the noise level. PMID:3580488

Flash spectroscopy of purple membrane.

PubMed

Xie, A H; Nagle, J F; Lozier, R H

1987-04-01

Flash spectroscopy data were obtained for purple membrane fragments at pH 5, 7, and 9 for seven temperatures from 5 degrees to 35 degrees C, at the magic angle for actinic versus measuring beam polarizations, at fifteen wavelengths from 380 to 700 nm, and for about five decades of time from 1 microsecond to completion of the photocycle. Signal-to-noise ratios are as high as 500. Systematic errors involving beam geometries, light scattering, absorption flattening, photoselection, temperature fluctuations, partial dark adaptation of the sample, unwanted actinic effects, and cooperativity were eliminated, compensated for, or are shown to be irrelevant for the conclusions. Using nonlinear least squares techniques, all data at one temperature and one pH were fitted to sums of exponential decays, which is the form required if the system obeys conventional first-order kinetics. The rate constants obtained have well behaved Arrhenius plots. Analysis of the residual errors of the fitting shows that seven exponentials are required to fit the data to the accuracy of the noise level.

Deposition of reactively ion beam sputtered silicon nitride coatings

NASA Technical Reports Server (NTRS)

Grill, A.

1982-01-01

An ion beam source was used to deposit silicon nitride films by reactively sputtering a silicon target with beams of Ar + N2 mixtures. The nitrogen fraction in the sputtering gas was 0.05 to 0.80 at a total pressure of 6 to 2 millionth torr. The ion beam current was 50 mA at 500 V. The composition of the deposited films was investigated by auger electron spectroscopy and the rate of deposition was determined by interferometry. A relatively low rate of deposition of about 2 nm. one-tenth min. was found. AES spectra of films obtained with nitrogen fractions higher than 0.50 were consistent with a silicon to nitrogen ratio corresponding to Si3N4. However the AES spectra also indicated that the sputtered silicon nitride films were contaminated with oxygen and carbon and contained significant amounts of iron, nickel, and chromium, most probably sputtered from the holder of the substrate and target.

Bigelow BEAM Contract

NASA Image and Video Library

2013-01-16

NASA Deputy Administrator Lori Garver talks during a media briefing where she and President and founder of Bigelow Aerospace Robert T. Bigelow, discussed their $17.8 million contract to provide a Bigelow Expandable Activity Module (BEAM) to the International Space Station to test expandable space habitat technology, Wednesday, Jan. 16, 2013 at Bigelow Aerospace in Las Vegas. BEAM is scheduled to arrive at the space station in 2015 for a two-year technology demonstration. Photo Credit: (NASA/Bill Ingalls)

Bigelow BEAM Contract

NASA Image and Video Library

2013-01-16

President and founder of Bigelow Aerospace Robert T. Bigelow, talks during a media briefing where he and NASA Deputy Administrator Lori Garver discussed their $17.8 million contract to provide a Bigelow Expandable Activity Module (BEAM) to the International Space Station to test expandable space habitat technology, Wednesday, Jan. 16, 2013 at Bigelow Aerospace in Las Vegas. BEAM is scheduled to arrive at the space station in 2015 for a two-year technology demonstration. Photo Credit: (NASA/Bill Ingalls)

X-ray absorption fine structure (XAFS) spectroscopy using synchrotron radiation

NASA Astrophysics Data System (ADS)

Shrivastava, B. D.

2012-05-01

The X-ray absorption fine structure (XAFS) spectra are best recorded when a highly intense beam of X-rays from a synchrotron is used along with a good resolution double crystal or curved crystal spectrometer and detectors like ionization chambers, scintillation counters, solid state detectors etc. Several synchrotrons around the world have X-ray beamlines dedicated specifically to XAFS spectroscopy. Fortunately, the Indian synchrotron (Indus-2) at Raja Ramanna Centre for Advanced Technology (RRCAT) at Indore has started operation. A dispersive type EXAFS beamline called BL-8 has been commissioned at this synchrotron and another beamline having double crystal monochromator (DCM) is going to be commissioned shortly. In Indian context, in order that more research workers use these beamlines, the study of XAFS spectroscopy using synchrotron radiation becomes important. In the present work some of the works done by our group on XAFS spectroscopy using synchrotron radiation have been described.

Optimization of ion-atomic beam source for deposition of GaN ultrathin films.

PubMed

Mach, Jindřich; Šamořil, Tomáš; Kolíbal, Miroslav; Zlámal, Jakub; Voborny, Stanislav; Bartošík, Miroslav; Šikola, Tomáš

2014-08-01

We describe the optimization and application of an ion-atomic beam source for ion-beam-assisted deposition of ultrathin films in ultrahigh vacuum. The device combines an effusion cell and electron-impact ion beam source to produce ultra-low energy (20-200 eV) ion beams and thermal atomic beams simultaneously. The source was equipped with a focusing system of electrostatic electrodes increasing the maximum nitrogen ion current density in the beam of a diameter of ≈15 mm by one order of magnitude (j ≈ 1000 nA/cm(2)). Hence, a successful growth of GaN ultrathin films on Si(111) 7 × 7 substrate surfaces at reasonable times and temperatures significantly lower (RT, 300 °C) than in conventional metalorganic chemical vapor deposition technologies (≈1000 °C) was achieved. The chemical composition of these films was characterized in situ by X-ray Photoelectron Spectroscopy and morphology ex situ using Scanning Electron Microscopy. It has been shown that the morphology of GaN layers strongly depends on the relative Ga-N bond concentration in the layers.

Position-sensitive scanning fluorescence correlation spectroscopy.

PubMed

Skinner, Joseph P; Chen, Yan; Müller, Joachim D

2005-08-01

Fluorescence correlation spectroscopy (FCS) uses a stationary laser beam to illuminate a small sample volume and analyze the temporal behavior of the fluorescence fluctuations within the stationary observation volume. In contrast, scanning FCS (SFCS) collects the fluorescence signal from a moving observation volume by scanning the laser beam. The fluctuations now contain both temporal and spatial information about the sample. To access the spatial information we synchronize scanning and data acquisition. Synchronization allows us to evaluate correlations for every position along the scanned trajectory. We use a circular scan trajectory in this study. Because the scan radius is constant, the phase angle is sufficient to characterize the position of the beam. We introduce position-sensitive SFCS (PSFCS), where correlations are calculated as a function of lag time and phase. We present the theory of PSFCS and derive expressions for diffusion, diffusion in the presence of flow, and for immobilization. To test PSFCS we compare experimental data with theory. We determine the direction and speed of a flowing dye solution and the position of an immobilized particle. To demonstrate the feasibility of the technique for applications in living cells we present data of enhanced green fluorescent protein measured in the nucleus of COS cells.

Hollow Core Fiber Optics for Mid-Wave and Long-Wave Infrared Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kriesel, J.M.; Gat, N.; Bernacki, Bruce E.

The development and testing of hollow core glass waveguides (i.e., fiber optics) for use in Long-Wave Infrared (LWIR) spectroscopy systems is described. LWIR fiber optics are a key enabling technology needed to improve the utility and effectiveness of trace chemical detection systems based in the 8 to 12 micron region. This paper focuses on recent developments in hollow waveguide technology geared specifically for LWIR spectroscopy, including a reduction in both the length dependent loss and the bending loss while maintaining relatively high beam quality. Results will be presented from tests conducted with a Quantum Cascade Laser.

Decomposition and biodegradability enhancement of textile wastewater using a combination of electron beam irradiation and activated sludge process.

PubMed

Mohd Nasir, Norlirubayah; Teo Ming, Ting; Ahmadun, Fakhru'l-Razi; Sobri, Shafreeza

2010-01-01

The research conducted a study on decomposition and biodegradability enhancement of textile wastewater using a combination of electron beam irradiation and activated sludge process. The purposes of this research are to remove pollutant through decomposition and to enhance the biodegradability of textile wastewater. The wastewater is treated using electron beam irradiation as a pre-treatment before undergo an activated sludge process. As a result, for non-irradiated wastewater, the COD removal was achieved to be between 70% and 79% after activated sludge process. The improvement of COD removal efficiency increased to 94% after irradiation of treated effluent at the dose of 50 kGy. Meanwhile, the BOD(5) removal efficiencies of non-irradiated and irradiated textile wastewater were reported to be between 80 and 87%, and 82 and 99.2%, respectively. The maximum BOD(5) removal efficiency was achieved at day 1 (HRT 5 days) of the process of an irradiated textile wastewater which is 99.2%. The biodegradability ratio of non-irradiated wastewater was reported to be between 0.34 and 0.61, while the value of biodegradability ratio of an irradiated wastewater increased to be between 0.87 and 0.96. The biodegradability enhancement of textile wastewater is increased with increasing the doses. Therefore, an electron beam radiation holds a greatest application of removing pollutants and also on enhancing the biodegradability of textile wastewater.

Neutron Time-of-Flight Spectroscopy

PubMed Central

Copley, John R. D.; Udovic, Terrence J.

1993-01-01

The time-of-flight technique is employed in two of the instruments at the NIST Cold Neutron Research Facility (CNRF). A pulsed monochromatic beam strikes the sample, and the energies of scattered neutrons are determined from their times-of-flight to an array of detectors. The time-of-flight method may be used in a variety of types of experiments such as studies of vibrational and magnetic excitations, tunneling spectroscopy, and quasielastic scattering studies of diffusional behavior; several examples of experiments are discussed. We also present brief descriptions of the CNRF time-of-flight instruments, including their modi operandi and some of their more pertinent parameters and performance characteristics. PMID:28053459

Workshop on Physics with Neutral Kaon Beam at JLab (KL2016) Mini-Proceedings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strakovsky, Igor I.; Amaryan, Moskov; Chudakov, Eugene A.

2016-05-01

The KL2016 Workshop is following the Letter of Intent LoI12-15-001 "Physics Opportunities with Secondary KL beam at JLab" submitted to PAC43 with the main focus on the physics of excited hyperons produced by the Kaon beam on unpolarized and polarized targets with GlueX setup in Hall D. Such studies will broaden a physics program of hadron spectroscopy extending it to the strange sector. The Workshop was organized to get a feedback from the community to strengthen physics motivation of the LoI and prepare a full proposal.

Emission Spectroscopy of the 4X Source Discharge With and Without N 2 Gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Horace Vernon

2016-01-14

This tech note summarizes the December, 1988 emission spectroscopy measurements made on the 4X source discharge with and without N₂ gas added to the H + Cs discharge. This study is motivated by the desire to understand why small amounts of N₂ gas added to the source discharge results in a reduction in the H⁻ beam noise. The beneficial effect of N₂ gas on H⁻ beam noise was first discovered by Bill Ingalls and Stu Orbesen on the ATS SAS source. For the 4X source the observed effect is that when N2 gas is added to the discharge the H⁻more » beam noise is reduced about a factor of 2.« less

A new single crystal diamond dosimeter for small beam: comparison with different commercial active detectors.

PubMed

Marsolat, F; Tromson, D; Tranchant, N; Pomorski, M; Le Roy, M; Donois, M; Moignau, F; Ostrowsky, A; De Carlan, L; Bassinet, C; Huet, C; Derreumaux, S; Chea, M; Cristina, K; Boisserie, G; Bergonzo, P

2013-11-07

Recent developments of new therapy techniques using small photon beams, such as stereotactic radiotherapy, require suitable detectors to determine the delivered dose with a high accuracy. The dosimeter has to be as close as possible to tissue equivalence and to exhibit a small detection volume compared to the size of the irradiation field, because of the lack of lateral electronic equilibrium in small beam. Characteristics of single crystal diamond (tissue equivalent material Z = 6, high density) make it an ideal candidate to fulfil most of small beam dosimetry requirements. A commercially available Element Six electronic grade synthetic diamond was used to develop a single crystal diamond dosimeter (SCDDo) with a small detection volume (0.165 mm(3)). Long term stability was studied by irradiating the SCDDo in a (60)Co beam over 14 h. A good stability (deviation less than ± 0.1%) was observed. Repeatability, dose linearity, dose rate dependence and energy dependence were studied in a 10 × 10 cm(2) beam produced by a Varian Clinac 2100 C linear accelerator. SCDDo lateral dose profile, depth dose curve and output factor (OF) measurements were performed for small photon beams with a micro multileaf collimator m3 (BrainLab) attached to the linac. This study is focused on the comparison of SCDDo measurements to those obtained with different commercially available active detectors: an unshielded silicon diode (PTW 60017), a shielded silicon diode (Sun Nuclear EDGE), a PinPoint ionization chamber (PTW 31014) and two natural diamond detectors (PTW 60003). SCDDo presents an excellent spatial resolution for dose profile measurements, due to its small detection volume. Low energy dependence (variation of 1.2% between 6 and 18 MV photon beam) and low dose rate dependence of the SCDDo (variation of 1% between 0.53 and 2.64 Gy min(-1)) are obtained, explaining the good agreement between the SCDDo and the efficient unshielded diode (PTW 60017) in depth dose curve

Experimental Study on Full-Scale Beams Made by Reinforced Alkali Activated Concrete Undergoing Flexure

PubMed Central

Monfardini, Linda; Minelli, Fausto

2016-01-01

Alkali Activated Concrete (AAC) is an alternative kind of concrete that uses fly ash as a total replacement of Portland cement. Fly ash combined with alkaline solution and cured at high temperature reacts to form a binder. Four point bending tests on two full scale beams made with AAC are described in this paper. Companion small material specimens were also casted with the aim of properly characterizing this new tailored material. The beam’s length was 5000 mm and the cross section was 200 mm × 300 mm. The AAC consisted of fly ash, water, sand 0–4 mm and coarse aggregate 6–10 mm; and the alkaline solution consisted of sodium hydroxide mixed with sodium silicate. No cement was utilized. The maximum aggregate size was 10 mm; fly ash was type F, containing a maximum calcium content of 2%. After a rest period of two days, the beam was cured at 60 °C for 24 h. Data collected and critically discussed included beam deflection, crack patterns, compressive and flexural strength and elastic modulus. Results show how AAC behavior is comparable with Ordinary Portland Cement (OPC) based materials. Nonlinear numerical analyses are finally reported, promoting a better understanding of the structural response. PMID:28773861

Design and performance of an instrument for electron impact tandem mass spectrometry and action spectroscopy of mass/charge selected macromolecular ions stored in RF ion trap*

NASA Astrophysics Data System (ADS)

Ranković, Milos Lj.; Giuliani, Alexandre; Milosavljević, Aleksandar R.

2016-06-01

A new apparatus was designed, coupling an electron gun with a linear quadrupole ion trap mass spectrometer, to perform m/ z (mass over charge) selected ion activation by electron impact for tandem mass spectrometry and action spectroscopy. We present in detail electron tracing simulations of a 300 eV electron beam inside the ion trap, design of the mechanical parts, electron optics and electronic circuits used in the experiment. We also report examples of electron impact activation tandem mass spectra for Ubiquitin protein, Substance P and Melittin peptides, at incident electron energies in the range from 280 eV to 300 eV.

Effects of prenatal irradiation with accelerated heavy-ion beams on postnatal development in rats: III. Testicular development and breeding activity

NASA Astrophysics Data System (ADS)

Wang, B.; Murakami, M.; Eguchi-Kasai, K.; Nojima, K.; Shang, Y.; Tanaka, K.; Watanabe, K.; Fujita, K.; Moreno, S. G.; Coffigny, H.; Hayata, I.

With a significant increase in human activities dealing with space missions, potential teratogenic effects on the mammalian reproductive system from prenatal exposure to space radiation have become a hot topic that needs to be addressed. However, even for the ground experiments, such effects from exposure to high LET ionizing radiation are not as well studied as those for low LET ionizing radiations such as X-rays. Using the Heavy-Ion Medical Accelerator in Chiba (HIMAC) and Wistar rats, effects on gonads in prenatal male fetuses, on postnatal testicular development and on breeding activity of male offspring were studied following exposure of the pregnant animals to either accelerated carbon-ion beams with a LET value of about 13 keV/μm or neon-ion beams with a LET value of about 30 keV/μm at a dose range from 0.1 to 2.0 Gy on gestation day 15. The effects of X-rays at 200 kVp estimated for the same biological end points were studied for comparison. A significantly dose-dependent increase of apoptosis in gonocytes appeared 6 h after irradiations with a dose of 0.5 Gy or more. Measured delayed testis descent and malformed testicular seminiferous tubules were observed to be significantly different from the control animals at a dose of 0.5 Gy. These effects are observed to be dose- and LET-dependent. Markedly reduced testicular weight and testicular weight to body weight ratio were scored at postnatal day 30 even in the offspring that were prenatally irradiated with neon-ions at a dose of 0.1 Gy. A dose of 0.5 Gy from neon-ion beams induced a marked decrease in breeding activity in the prenatally irradiated male rats, while for the carbon-ion beams or X-rays, the significantly reduced breeding activity was observed only when the prenatal dose was at 1.0 Gy or more. These findings indicated that prenatal irradiations with heavy-ion beams on gestation day 15 generally induced markedly detrimental effects on prenatal gonads, postnatal testicular development and male

Active retroreflector with in situ beam analysis to measure the rotational orientation in conjunction with a laser tracker

NASA Astrophysics Data System (ADS)

Hofherr, O.; Wachten, C.; Müller, C.; Reinecke, H.

2013-04-01

High precision optical non-contact position measurement is a key technology in modern engineering. Laser trackers (LT) can determine accurately x-y-z coordinates of passive retroreflectors. Next-generation systems answer the additional need to measure an object`s rotational orientation (pitch, yaw, roll). These devices are based either on photogrammetry or on enhanced retroreflectors. However, photogrammetry relies on costly camera systems and time-consuming image processing. Enhanced retroreflectors analyze the LT`s beam but are restricted in roll angle measurements. In the past we have presented a new method [1][2] to measure all six degrees of freedom in conjunction with a LT. Now we dramatically optimized the method and designed a new prototype, e.g. taking into consideration optical alignment, reduced power loss, highly optimized measuring signals and higher resolution. A method is described that allows compensating the influence of the LT's beam offset during tracking the active retroreflector. We prove the functionality of the active retroreflector with the LT and, furthermore, demonstrate the capability of the system to characterize the tracking behavior of a LT. The measurement range for the incident laser beam is +/-12° with a resolution of 0.6".

Effects of Cycling Conditions of Active Material From Discharged Ni Positive Plates Studied by Inelastic Neutron Scattering Spectroscopy

NASA Technical Reports Server (NTRS)

Eckert, Juergen; Varma, Ravi; Diebolt, Lisa; Reid, Margaret

1998-01-01

The objectives of this presentation are: identify atomic-level signatures of electrochemical activity of the active material on the Ni positive plates of Ni-H2 batteries, relate finding to cycling conditions and histories, and develop INS spectroscopy as a non-destructive testing technique for the evaluation of Ni-positive plates of Ni-H2 batteries.

Slow positron beam study of hydrogen ion implanted ZnO thin films

NASA Astrophysics Data System (ADS)

Hu, Yi; Xue, Xudong; Wu, Yichu

2014-08-01

The effects of hydrogen related defect on the microstructure and optical property of ZnO thin films were investigated by slow positron beam, in combination with x-ray diffraction, infrared and photoluminescence spectroscopy. The defects were introduced by 90 keV proton irradiation with doses of 1×1015 and 1×1016 ions cm-2. Zn vacancy and OH bonding (VZn+OH) defect complex were identified in hydrogen implanted ZnO film by positron annihilation and infrared spectroscopy. The formation of these complexes led to lattice disorder in hydrogen implanted ZnO film and suppressed the luminescence process.

An online, energy-resolving beam profile detector for laser-driven proton beams.

PubMed

Metzkes, J; Zeil, K; Kraft, S D; Karsch, L; Sobiella, M; Rehwald, M; Obst, L; Schlenvoigt, H-P; Schramm, U

2016-08-01

In this paper, a scintillator-based online beam profile detector for the characterization of laser-driven proton beams is presented. Using a pixelated matrix with varying absorber thicknesses, the proton beam is spatially resolved in two dimensions and simultaneously energy-resolved. A thin plastic scintillator placed behind the absorber and read out by a CCD camera is used as the active detector material. The spatial detector resolution reaches down to ∼4 mm and the detector can resolve proton beam profiles for up to 9 proton threshold energies. With these detector design parameters, the spatial characteristics of the proton distribution and its cut-off energy can be analyzed online and on-shot under vacuum conditions. The paper discusses the detector design, its characterization and calibration at a conventional proton source, as well as the first detector application at a laser-driven proton source.

Molecular beam optical Stark spectroscopy of calcium monocyanide

NASA Astrophysics Data System (ADS)

Steimle, Timothy C.; Fletcher, David A.; Jung, Kook Y.; Scurlock, Christopher T.

1992-09-01

The 617.7 and 614.7 nm bands of calcium monocyanide, CaNC/CaCN, have been recorded at high resolution by laser-induced fluorescence using a supersonic molecular beam. The two bands consist of twelve branches that are assigned to a case a (0,0,0)A 2Πr-(0,0,0)X 2Σ+ transition. A reduction of the data to an effective Hamiltonian model produced the spectroscopic parameters (cm-1): T00= 16229.5417(26), B″=0.13499(14), γ″=6.1837(33)×10-4, A'=77.6451(40), B'=0.15027(23), AD'=2.69(11) × 10-3, D'= -3.50(25) × 10-5, p'=0.0754(18), q'=-0.04808(87), qD''= 2.64(65) × 10-5. It is proposed that the anomalous values of the excited state parameters arise because of Renner-Teller interactions. The magnitude of the permanent electric dipoles, |μ|, were also determined and are 5.949(1) D[A 2Π1/2(0,0,0),J= 0.5] and 6.895(9) D[X 2Σ+(0,0,0),J= 1.5]. The large value of |μ| is consistent with an isocyanide structure, CaNC. A comparison with theoretical predictions is presented.

Finite element modeling of light propagation in fruit under illumination of continuous-wave beam

USDA-ARS?s Scientific Manuscript database

Spatially-resolved spectroscopy provides a means for measuring the optical properties of biological tissues, based on analytical solutions to diffusion approximation for semi-infinite media under the normal illumination of infinitely small size light beam. The method is, however, prone to error in m...

Impulsive Raman spectroscopy via precision measurement of frequency shift with low energy excitation.

PubMed

Raanan, Dekel; Ren, Liqing; Oron, Dan; Silberberg, Yaron

2018-02-01

Stimulated Raman scattering (SRS) has recently become useful for chemically selective bioimaging. It is usually measured via modulation transfer from the pump beam to the Stokes beam. Impulsive stimulated Raman spectroscopy, on the other hand, relies on the spectral shift of ultrashort pulses as they propagate in a Raman active sample. This method was considered impractical with low energy pulses since the observed shifts are very small compared to the excitation pulse bandwidth, spanning many terahertz. Here we present a new apparatus, using tools borrowed from the field of precision measurement, for the detection of low-frequency Raman lines via stimulated-Raman-scattering-induced spectral shifts. This method does not require any spectral filtration and is therefore an excellent candidate to resolve low-lying Raman lines (<200  cm -1 ), which are commonly masked by the strong Rayleigh scattering peak. Having the advantage of the high repetition rate of the ultrafast oscillator, we reduce the noise level by implementing a lock-in detection scheme with a wavelength shift sensitivity well below 100 fm. This is demonstrated by the measurement of low-frequency Raman lines of various liquid samples.

Micro/nanofabrication of poly({sub L}-lactic acid) using focused ion beam direct etching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oyama, Tomoko Gowa; Nagasawa, Naotsugu; Taguchi, Mitsumasa

2013-10-14

Micro/nanofabrication of biocompatible and biodegradable poly({sub L}-lactic acid) (PLLA) using focused Ga ion beam direct etching was evaluated for future bio-device applications. The fabrication performance was determined with different ion fluences and fluxes (beam currents), and it was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat. Focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds. Controlled micro/nanostructures of PLLA were fabricated with C=C bond-rich surfaces expected to have good cell attachmentmore » properties.« less

8 MeV electron beam induced modifications in the thermal, structural and electrical properties of nanophase CeO2 for potential electronics applications

NASA Astrophysics Data System (ADS)

Babitha, K. K.; Sreedevi, A.; Priyanka, K. P.; Ganesh, S.; Varghese, Thomas

2018-06-01

The effect of 8 MeV electron beam irradiation on the thermal, structural and electrical properties of CeO2 nanoparticles synthesized by chemical precipitation route was investigated. The dose dependent effect of electron irradiation was studied using various characterization techniques such as, thermogravimetric and differential thermal analyses, X-ray diffraction, Fourier transformed infrared spectroscopy and impedance spectroscopy. Systematic investigation based on the results of structural studies confirm that electron beam irradiation induces defects and particle size variation on CeO2 nanoparticles, which in turn results improvements in AC conductivity, dielectric constant and loss tangent. Structural modifications and high value of dielectric constant for CeO2 nanoparticles due to electron beam irradiation make it as a promising material for the fabrication of gate dielectric in metal oxide semiconductor devices.

Selective suppression of CARS signal with three-beam competing stimulated Raman scattering processes.

PubMed

Choi, Dae Sik; Rao, B Jayachander; Kim, Doyeon; Shim, Sang-Hee; Rhee, Hanju; Cho, Minhaeng

2018-06-14

Coherent Raman scattering spectroscopy and microscopy are useful methods for studying the chemical and biological structures of molecules with Raman-active modes. In particular, coherent anti-Stokes Raman scattering (CARS) microscopy, which is a label-free method capable of imaging structures by displaying the vibrational contrast of the molecules, has been widely used. However, the lack of a technique for switching-off the CARS signal has prevented the development of the super-resolution Raman imaging method. Here, we demonstrate that a selective suppression of the CARS signal is possible by using a three-beam double stimulated Raman scattering (SRS) scheme; the three beams are the pump, Stokes, and depletion lights in order of frequency. Both pump-Stokes and pump-depletion beam pairs can generate SRS processes by tuning their beat frequencies to match two different vibrational modes, then two CARS signals induced by pump-Stokes-pump and pump-depletion-pump interactions can be generated, where the two CARS signals are coupled with each other because they both involve interactions with the common pump beam. Herein, we show that as the intensity of the depletion beam is increased, one can selectively suppress the pump-Stokes-pump CARS signal because the pump-depletion SRS depletes the pump photons. A detailed theoretical description of the coupled differential equations for the three incident fields and the generated CARS signal fields is presented. Taking benzene as a molecular system, we obtained a maximum CARS suppression efficiency of about 97% with our experimental scheme, where the ring breathing mode of the benzene is associated with pump-Stokes-pump CARS, while the C-H stretching mode is associated with the competing pump-depletion SRS process. We anticipate that this selective switching-off scheme will be of use in developing super-resolution label-free CARS microscopy.

Intersubject variability of near-infrared spectroscopy signals during sensorimotor cortex activation.

PubMed

Sato, Hiroki; Fuchino, Yutaka; Kiguchi, Masashi; Katura, Takusige; Maki, Atsushi; Yoro, Takeshi; Koizumi, Hideaki

2005-01-01

We investigate the intersubject signal variability of near-infrared spectroscopy (NIRS), which is commonly used for noninvasive measurement of the product of the optical path length and the concentration change in oxygenated hemoglobin (DeltaC'oxy) and deoxygenated hemoglobin (DeltaC'deoxy) and their sum (DeltaC'total) related to human cortical activation. We do this by measuring sensorimotor cortex activation in 31 healthy adults using 24-measurement-position near-infrared (NIR) topography. A finger-tapping task is used to activate the sensorimotor cortex, and significant changes in the hemisphere contralateral to the tapping hand are assessed as being due to the activation. Of the possible patterns of signal changes, 90% include a positive DeltaC'oxy, 76% included a negative DeltaC'deoxy, and 73% included a positive DeltaC'total. The DeltaC'deoxy and DeltaC'total are less consistent because of a large intersubject variability in DeltaC'deoxy; in some cases there is a positive DeltaC'deoxy. In the cases with no positive DeltaC'oxy in the contralateral hemisphere, there are cases of other possible changes for either or both hemispheres and no cases of no change in any hemoglobin species in either hemisphere. These results suggest that NIR topography is useful for observing brain activity in most cases, although intersubject signal variability still needs to be resolved.

Optical trapping and Raman spectroscopy of single nanostructures using standing-wave Raman tweezers

NASA Astrophysics Data System (ADS)

Wu, Mu-ying; He, Lin; Chen, Gui-hua; Yang, Guang; Li, Yong-qing

2017-08-01

Optical tweezers integrated with Raman spectroscopy allows analyzing a single trapped micro-particle, but is generally less effective for individual nano-sized objects in the 10-100 nm range. The main challenge is the weak gradient force on nanoparticles that is insufficient to overcome the destabilizing effect of scattering force and Brownian motion. Here, we present standing-wave Raman tweezers for stable trapping and sensitive characterization of single isolated nanostructures with a low laser power by combining a standing-wave optical trap (SWOT) with confocal Raman spectroscopy. This scheme has stronger intensity gradients and balanced scattering forces, and thus is more stable and sensitive in measuring nanoparticles in liquid with 4-8 fold increase in the Raman signals. It can be used to analyze many nanoparticles that cannot be measured with single-beam Raman tweezers, including individual single-walled carbon nanotubes (SWCNT), graphene flakes, biological particles, polystyrene beads (100 nm), SERS-active metal nanoparticles, and high-refractive semiconductor nanoparticles with a low laser power of a few milliwatts. This would enable sorting and characterization of specific SWCNTs and other nanoparticles based on their increased Raman fingerprints.

X-ray astronomical spectroscopy

NASA Technical Reports Server (NTRS)

Holt, S. S.

1980-01-01

The current status of the X-ray spectroscopy of celestial X-ray sources, ranging from nearby stars to distant quasars, is reviewed. Particular emphasis is placed on the role of such spectroscopy as a useful and unique tool in the elucidation of the physical parameters of the sources. The spectroscopic analysis of degenerate and nondegenerate stellar systems, galactic clusters and active galactic nuclei, and supernova remnants is discussed.

A unified formulation of dichroic signals using the Borrmann effect and twisted photon beams.

PubMed

Collins, Stephen P; Lovesey, Stephen W

2018-05-21

Dichroic X-ray signals derived from the Borrmann effect and a twisted photon beam with topological charge l = 1 are formulated with an effective wavevector. The unification applies for non-magnetic and magnetic materials. Electronic degrees of freedom associated with an ion are encapsulated in multipoles previously used to interpret conventional dichroism and Bragg diffraction enhanced by an atomic resonance. A dichroic signal exploiting the Borrmann effect with a linearly polarized beam presents charge-like multipoles that include a hexadecapole. A difference between dichroic signals obtained with a twisted beam carrying spin polarization (circular polarization) and opposite winding numbers presents charge-like atomic multipoles, whereas a twisted beam carrying linear polarization alone presents magnetic (time-odd) multipoles. Charge-like multipoles include a quadrupole, and magnetic multipoles include a dipole and an octupole. We discuss the practicalities and relative merits of spectroscopy exploiting the two remarkably closely-related processes. Signals using beams with topological charges l ≥ 2 present additional atomic multipoles.

Ion Temperature Measurements in an electron beam ion trap (EBIT)

NASA Astrophysics Data System (ADS)

Beiersdorfer, P.; Decaux, V.; Widmann, K.

1997-11-01

An electron beam ion trap consists of a Penning-type cylindrical trap traversed by a high-energy (<= 200 keV), high-density (Ne <= 10^13 cm-3) electron beam. Ions are trapped by the space charge potential of the electron beam, a static potential on the end electrodes, and a 3-T axial magnetic field [1]. The ions are heated by the electron beam and leave the trap once their kinetic energy suffices to overcome the potential barriers. Using high-resolution x-ray spectroscopy, we have made systematic measurements of the temperature of Ti^20+ and Cs^45+ ions in the trap [2]. The dependence of the ion temperature on operating parameters, such as trapping potential, beam current, and neutral gas pressure, will be presented. Temperatures as low as 15.4 ± 4.4 eV and as high as 2 keV were observed. *Work performed under the auspices of the U.S.D.o.E. by Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48. [1] M. Levine et al., Phys. Scripta T22, 157 (1989). [2]P. Beiersdorfer et al., PRL 77, 5356 (1996); P. Beiersdorfer, in AIP Conf. Proc. No. 389, p. 121 (1997).

Activation of QA devices and phantom materials under clinical scanning proton beams-a gamma spectrometry study.

PubMed

Hanušová, Tereza; Johnová, Kamila; Navrátil, Matěj; Valenta, Jiří; Müller, Lutz

2018-06-07

Activation of detectors and phantoms used for commissioning and quality assurance of clinical proton beams may lead to radiation protection issues. Good understanding of the activation nuclide vectors involved is necessary to assess radiation risk for the personnel working with these devices on a daily basis or to fulfill legal requirements regarding transport of radioactive material and its release to the public. 11 devices and material samples were irradiated with a 220 MeV proton pencil beam (PBS, Proton Therapy Center, Prague). This study focuses on devices manufactured by IBA Dosimetry GmbH: MatriXX PT, PPC05, Stingray, Zebra, Lynx, a Blue Phantom rail and samples of RW3, PMMA, titanium, copper and carbon fibre plastic. Monitor units (MU) were monitored during delivery. Gamma spectrometry was then performed for each item using a HPGe detector, with a focus on longer lived gamma emitting radionuclides. Activities were quantified for all found isotopes and compared to relevant legal limits for exemption and clearance of radioactive objects. Activation was found to be significant after long irradiation sessions, as done during commissioning of a proton therapy room. Some of the investigated devices may also cumulate activity in time, depending on the scenario of periodic irradiation in routine clinical practice. However, the levels of activity and resulting beta/gamma doses are more comparable to internationally recommended concentration limits for exemption than to dose limits for radiation workers. Results of this study will help to determine nuclide inventories required by some legal authorities for radiation protection purposes.

Some performance tests of a microarea AES. [Auger Electron Spectroscopy

NASA Technical Reports Server (NTRS)

Todd, G.; Poppa, H.

1978-01-01

An Auger electron spectroscopy (AES) system which has a submicron analysis capability is described. The system provides secondary electron imaging, as well as micro- and macro-area AES. The resolution of the secondary electron image of an oxidized Al contact pad on a charge-coupled device chip indicates a primary beam size of about 1000 A. For Auger mapping, a useful resolution of about 4000 A is reported

Autobalanced Ramsey Spectroscopy

NASA Astrophysics Data System (ADS)

Sanner, Christian; Huntemann, Nils; Lange, Richard; Tamm, Christian; Peik, Ekkehard

2018-01-01

We devise a perturbation-immune version of Ramsey's method of separated oscillatory fields. Spectroscopy of an atomic clock transition without compromising the clock's accuracy is accomplished by actively balancing the spectroscopic responses from phase-congruent Ramsey probe cycles of unequal durations. Our simple and universal approach eliminates a wide variety of interrogation-induced line shifts often encountered in high precision spectroscopy, among them, in particular, light shifts, phase chirps, and transient Zeeman shifts. We experimentally demonstrate autobalanced Ramsey spectroscopy on the light shift prone Yb+ 171 electric octupole optical clock transition and show that interrogation defects are not turned into clock errors. This opens up frequency accuracy perspectives below the 10-18 level for the Yb+ system and for other types of optical clocks.

Apparatus and process for active pulse intensity control of laser beam

DOEpatents

Wilcox, Russell B.

1992-01-01

An optically controlled laser pulse energy control apparatus and process is disclosed wherein variations in the energy of a portion of the laser beam are used to vary the resistance of a photodetector such as a photoresistor through which a control voltage is fed to a light intensity controlling device through which a second portion of the laser beam passes. Light attenuation means are provided to vary the intensity of the laser light used to control the resistance of the photodetector. An optical delay path is provided through which the second portion of the beam travels before reaching the light intensity controlling device. The control voltage is supplied by a variable power supply. The apparatus may be tuned to properly attenuate the laser beam passing through the intensity controlling device by adjusting the power supply, the optical delay path, or the light attenuating means.

Use of particle beams for lunar prospecting

NASA Technical Reports Server (NTRS)

Toepfer, A. J.; Eppler, D.; Friedlander, A.; Weitz, R.

1993-01-01

A key issue in choosing the appropriate site for a manned lunar base is the availability of resources, particularly oxygen and hydrogen for the production of water, and ores for the production of fuels and building materials. NASA has proposed two Lunar Scout missions that would orbit the Moon and use, among other instruments, a hard X-ray spectrometer, a neutron spectrometer, and a Ge gamma ray spectrometer to map the lunar surface. This passive instrumentation will have low resolution (tens of kilometers) due to the low signal levels produced by natural radioactivity and the interaction of cosmic rays and the solar wind with the lunar surface. This paper presents the results of a concept definition effort for a neutral particle beam lunar mapper probe. The idea of using particle beam probes to survey asteroids was first proposed by Sagdeev et al., and an ion beam device was fielded on the 1988 Soviet probe to the Mars moon Phobos. During the past five years, significant advances in the technology of neutral particle beams (NPB) have led to a suborbital flight of a neutral hydrogen beam device in the SDIO-sponsored BEAR experiment. An orbital experiment, the Neutral Particle Beam Far Field Optics Experiment (NPB-FOX) is presently in the preliminary design phase. The development of NPB accelerators that are space-operable leads one to consider the utility of these devices for probing the surface of the Moon using gamma ray, X-ray, and optical/UV spectroscopy to locate various elements and compounds. We consider the utility of the NPB-FOX satellite containing a 5-MeV particle beam accelerator as a probe in lunar orbit. Irradiation of the lunar surface by the particle beam will induce secondary and back scattered radiation from the lunar surface to be detected by a sensor that may be co-orbital with or on the particle beam satellite platform, or may be in a separate orbit. The secondary radiation is characteristic of the make-up of the lunar surface. The size of the

Photodissociation dynamics and spectroscopy of free radical combustion intermediates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osborn, David Lewis

1996-12-01

The photodissociation spectroscopy and dynamics of free radicals is studied by the technique of fast beam photofragment translational spectroscopy. Photodetachment of internally cold, mass-selected negative ions produces a clean source of radicals, which are subsequently dissociated and detected. The photofragment yield as a function of photon energy is obtained, mapping out the dissociative and predissociative electronic states of the radical. In addition, the photodissociation dynamics, product branching ratios, and bond energies are probed at fixed photon energies by measuring the translational energy, P(E T), and angular distribution of the recoiling fragments using a time- and position-sensitive detector. Ab initio calculationsmore » are combined with dynamical and statistical models to interpret the observed data. The photodissociation of three prototypical hydrocarbon combustion intermediates forms the core of this work.« less

An online, energy-resolving beam profile detector for laser-driven proton beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Metzkes, J.; Rehwald, M.; Obst, L.

In this paper, a scintillator-based online beam profile detector for the characterization of laser-driven proton beams is presented. Using a pixelated matrix with varying absorber thicknesses, the proton beam is spatially resolved in two dimensions and simultaneously energy-resolved. A thin plastic scintillator placed behind the absorber and read out by a CCD camera is used as the active detector material. The spatial detector resolution reaches down to ∼4 mm and the detector can resolve proton beam profiles for up to 9 proton threshold energies. With these detector design parameters, the spatial characteristics of the proton distribution and its cut-off energymore » can be analyzed online and on-shot under vacuum conditions. The paper discusses the detector design, its characterization and calibration at a conventional proton source, as well as the first detector application at a laser-driven proton source.« less

Terahertz plasmonic laser radiating in an ultra-narrow beam

DOE PAGES

Wu, Chongzhao; Khanal, Sudeep; Reno, John L.; ...

2016-07-07

Plasmonic lasers (spasers) generate coherent surface plasmon polaritons (SPPs) and could be realized at subwavelength dimensions in metallic cavities for applications in nanoscale optics. Plasmonic cavities are also utilized for terahertz quantum-cascade lasers (QCLs), which are the brightest available solid-state sources of terahertz radiation. A long standing challenge for spasers that are utilized as nanoscale sources of radiation, is their poor coupling to the far-field radiation. Unlike conventional lasers that could produce directional beams, spasers have highly divergent radiation patterns due to their subwavelength apertures. Here, we theoretically and experimentally demonstrate a new technique for implementing distributed feedback (DFB) thatmore » is distinct from any other previously utilized DFB schemes for semiconductor lasers. The so-termed antenna-feedback scheme leads to single-mode operation in plasmonic lasers, couples the resonant SPP mode to a highly directional far-field radiation pattern, and integrates hybrid SPPs in surrounding medium into the operation of the DFB lasers. Experimentally, the antenna-feedback method, which does not require the phase matching to a well-defined effective index, is implemented for terahertz QCLs, and single-mode terahertz QCLs with a beam divergence as small as 4°×4° are demonstrated, which is the narrowest beam reported for any terahertz QCL to date. Moreover, in contrast to a negligible radiative field in conventional photonic band-edge lasers, in which the periodicity follows the integer multiple of half-wavelengths inside the active medium, antenna-feedback breaks this integer limit for the first time and enhances the radiative field of the lasing mode. Terahertz lasers with narrow-beam emission will find applications for integrated as well as standoff terahertz spectroscopy and sensing. Furthermore, the antenna-feedback scheme is generally applicable to any plasmonic laser with a Fabry–Perot cavity

A Study of The Effect of Preschool Children's Participation in Sensorimotor Activities on Their Understanding of the Mechanical Equilibrium of a Balance Beam

NASA Astrophysics Data System (ADS)

Hadzigeorgiou, Yannis; Anastasiou, Leonidas; Konsolas, Manos; Prevezanou, Barbara

2009-01-01

The purpose of this study was to investigate whether participation in sensorimotor activities by preschool children involving their own bodily balance while walking on a beam over the floor has an effect on their understanding of the mechanical equilibrium of a balance beam. The balance beam consisted of a horizontal stick balancing around its center of mass (middle point), while carrying equal-weight objects on either side of it. The study utilized a two-group design, and was conducted in three phases (pre-test, treatment and post-test). The results of the study provide evidence that there was such an effect, since the children (who participated in the sensorimotor activities) could select out of a number of objects those two with the same weight regardless of their shape, size or colour, in order to balance the stick. This effect also can be seen when a comparison is made with a second group of children, which had previously participated in a hands-on activity regarding the equilibrium of a similar balance beam, and which (children), therefore, had a definite advantage over the other children who had participated in the sensorimotor activity. A Chi Square Test showed no significant differences between the two groups on both an immediate and a delayed post-test, while the McNemar Test for the Significance of Change showed a statistically significant difference (that is, a negative change in performance between the first and the second post-test) only within the hands-on group. This difference represents evidence that the children from the sensorimotor group remembered better the rule they were applying (i.e., selecting equal-weight objects) in order to balance the beam.

Beam characterization at BATMAN for variation of the Cs evaporation asymmetry and comparing two driver geometries

NASA Astrophysics Data System (ADS)

Aza, E.; Schiesko, L.; Wimmer, C.; Wünderlich, D.; Fantz, U.

2017-08-01

The properties of the negative hydrogen ion beam produced by the scaled prototype ITER NBI source at the BATMAN testbed were investigated by means of two beam diagnostics: Beam Emission Spectroscopy (BES) and a calorimeter. Two modifications to the prototype were applied. The first was the installation of a second Cs oven at the bottom part of the backplate in addition to the standard one at the upper part of the backplate varying the Cs evaporation asymmetry inside the source. The second consisted in the replacement of the cylindrical driver with a larger racetrack-shaped RF driver and placing a single Cs oven in a central position at the backplate of the driver. The resulting beam characteristics are discussed and compared with those obtained with the previous source design. The position of the Cs oven and the different driver size and geometry appear not to influence the beam profile and the beam deflection for a well-conditioned source.

Low-loss electron energy loss spectroscopy: An atomic-resolution complement to optical spectroscopies and application to graphene

DOE PAGES

Kapetanakis, Myron; Zhou, Wu; Oxley, Mark P.; ...

2015-09-25

Photon-based spectroscopies have played a central role in exploring the electronic properties of crystalline solids and thin films. They are a powerful tool for probing the electronic properties of nanostructures, but they are limited by lack of spatial resolution. On the other hand, electron-based spectroscopies, e.g., electron energy loss spectroscopy (EELS), are now capable of subangstrom spatial resolution. Core-loss EELS, a spatially resolved analog of x-ray absorption, has been used extensively in the study of inhomogeneous complex systems. In this paper, we demonstrate that low-loss EELS in an aberration-corrected scanning transmission electron microscope, which probes low-energy excitations, combined with amore » theoretical framework for simulating and analyzing the spectra, is a powerful tool to probe low-energy electron excitations with atomic-scale resolution. The theoretical component of the method combines density functional theory–based calculations of the excitations with dynamical scattering theory for the electron beam. We apply the method to monolayer graphene in order to demonstrate that atomic-scale contrast is inherent in low-loss EELS even in a perfectly periodic structure. The method is a complement to optical spectroscopy as it probes transitions entailing momentum transfer. The theoretical analysis identifies the spatial and orbital origins of excitations, holding the promise of ultimately becoming a powerful probe of the structure and electronic properties of individual point and extended defects in both crystals and inhomogeneous complex nanostructures. The method can be extended to probe magnetic and vibrational properties with atomic resolution.« less

Neutron molecular spectroscopy using a white beam time-of-flight spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, S.; Jorgensen, J.D.; Berney, C.V.

1978-01-01

An inverted-geometry white beam TOF neutron spectrometer using an extended graphite crystal analyzer was constructed at the CP-5 reactor at Argonne. A performance test of the spectrometer for incoherent inelastic scattering studies was made with five selected molecular solids. The results demonstrate the utility of such a spectrometer for investigation of lattice vibrational spectra of hydrogenous compounds in the energy range 0--400 cm/sup -1/. We describe design considerations and energy resolution of the spectrometer, and discuss observed low-frequency spectra of acetic acid (CH/sub 3/COOH, CD/sub 3/COOH, and CH/sub 3/COOD), cyclohexane, and cyclopentane.

In-beam γ -ray spectroscopy of the neutron-rich platinum isotope 200Pt toward the N =126 shell gap

NASA Astrophysics Data System (ADS)

John, P. R.; Valiente-Dobón, J. J.; Mengoni, D.; Modamio, V.; Lunardi, S.; Bazzacco, D.; Gadea, A.; Wheldon, C.; Rodríguez, T. R.; Alexander, T.; de Angelis, G.; Ashwood, N.; Barr, M.; Benzoni, G.; Birkenbach, B.; Bizzeti, P. G.; Bizzeti-Sona, A. M.; Bottoni, S.; Bowry, M.; Bracco, A.; Browne, F.; Bunce, M.; Camera, F.; Corradi, L.; Crespi, F. C. L.; Melon, B.; Farnea, E.; Fioretto, E.; Gottardo, A.; Grente, L.; Hess, H.; Kokalova, Tz.; Korten, W.; Kuşoǧlu, A.; Lenzi, S.; Leoni, S.; Ljungvall, J.; Menegazzo, R.; Michelagnoli, C.; Mijatović, T.; Montagnoli, G.; Montanari, D.; Napoli, D. R.; Podolyák, Zs.; Pollarolo, G.; Recchia, F.; Reiter, P.; Roberts, O. J.; Şahin, E.; Salsac, M.-D.; Scarlassara, F.; Sferrazza, M.; Söderström, P.-A.; Stefanini, A. M.; Szilner, S.; Ur, C. A.; Vogt, A.; Walshe, J.

2017-06-01

The neutron-rich nucleus 200Pt is investigated via in-beam γ -ray spectroscopy to study the shape evolution in the neutron-rich platinum isotopes towards the N =126 shell closure. The two-neutron transfer reaction 198Pt(82Se, 80Se)200Pt is used to populate excited states of 200Pt. The Advanced Gamma Ray Tracking Array (AGATA) demonstrator coupled with the PRISMA spectrometer detects γ rays coincident with the 80Se recoils, the binary partner of 200Pt. The binary partner method is applied to extract the γ -ray transitions and build the level scheme of 200Pt. The level at 1884 keV reported by Yates et al. [S. W. Yates, E. M. Baum, E. A. Henry, L. G. Mann, N. Roy, A. Aprahamian, R. A. Meyer, and R. Estep, Phys. Rev. C 37, 1889 (1988)] was confirmed to be at 1882.1 keV and assigned as the (61+) state. An additional γ ray was found and it presumably deexcites the (81+) state. The results are compared with state-of-the-art beyond mean-field calculations, performed for the even-even 190 -204Pt isotopes, revealing that 200Pt marks the transition from the γ -unstable behavior of lighter Pt nuclei towards a more spherical one when approaching the N =126 shell closure.

Demonstration of temperature imaging by H₂O absorption spectroscopy using compressed sensing tomography.

PubMed

An, Xinliang; Brittelle, Mack S; Lauzier, Pascal T; Gord, James R; Roy, Sukesh; Chen, Guang-Hong; Sanders, Scott T

2015-11-01

This paper introduces temperature imaging by total-variation-based compressed sensing (CS) tomography of H2O vapor absorption spectroscopy. A controlled laboratory setup is used to generate a constant two-dimensional temperature distribution in air (a roughly Gaussian temperature profile with a central temperature of 677 K). A wavelength-tunable laser beam is directed through the known distribution; the beam is translated and rotated using motorized stages to acquire complete absorption spectra in the 1330-1365 nm range at each of 64 beam locations and 60 view angles. Temperature reconstructions are compared to independent thermocouple measurements. Although the distribution studied is approximately axisymmetric, axisymmetry is not assumed and simulations show similar performance for arbitrary temperature distributions. We study the measurement error as a function of number of beams and view angles used in reconstruction to gauge the potential for application of CS in practical test articles where optical access is limited.

Fabrication of plasmonic nanopore by using electron beam irradiation for optical bio-sensor

NASA Astrophysics Data System (ADS)

Choi, Seong Soo; Park, Myoung Jin; Han, Chul Hee; Oh, Seh Joong; Park, Nam Kyou; Park, Doo Jae; Choi, Soo Bong; Kim, Yong-Sang

2017-05-01

The Au nano-hole surrounded by the periodic nano-patterns would provide the enhanced optical intensity. Hence, the nano-hole surrounded with periodic groove patterns can be utilized as single molecule nanobio optical sensor device. In this report, the nano-hole on the electron beam induced membrane surrounded by periodic groove patterns were fabricated by focused ion beam technique (FIB), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Initially, the Au films with three different thickness of 40 nm, 60 nm, and 200 nm were deposited on the SiN film by using an electron beam sputter-deposition technique, followed by removal of the supporting SiN film. The nanopore was formed on the electron beam induced membrane under the FESEM electron beam irradiation. Nanopore formation inside the Au aperture was controlled down to a few nanometer, by electron beam irradiations. The optical intensities from the biomolecules on the surfaces including Au coated pyramid with periodic groove patterns were investigated via surface enhanced Raman spectroscopy (SERS). The fabricated nanopore surrounded by periodic patterns can be utilized as a next generation single molecule bio optical sensor.

Development of activity pencil beam algorithm using measured distribution data of positron emitter nuclei generated by proton irradiation of targets containing (12)C, (16)O, and (40)Ca nuclei in preparation of clinical application.

PubMed

Miyatake, Aya; Nishio, Teiji; Ogino, Takashi

2011-10-01

The purpose of this study is to develop a new calculation algorithm that is satisfactory in terms of the requirements for both accuracy and calculation time for a simulation of imaging of the proton-irradiated volume in a patient body in clinical proton therapy. The activity pencil beam algorithm (APB algorithm), which is a new technique to apply the pencil beam algorithm generally used for proton dose calculations in proton therapy to the calculation of activity distributions, was developed as a calculation algorithm of the activity distributions formed by positron emitter nuclei generated from target nuclear fragment reactions. In the APB algorithm, activity distributions are calculated using an activity pencil beam kernel. In addition, the activity pencil beam kernel is constructed using measured activity distributions in the depth direction and calculations in the lateral direction. (12)C, (16)O, and (40)Ca nuclei were determined as the major target nuclei that constitute a human body that are of relevance for calculation of activity distributions. In this study, "virtual positron emitter nuclei" was defined as the integral yield of various positron emitter nuclei generated from each target nucleus by target nuclear fragment reactions with irradiated proton beam. Compounds, namely, polyethylene, water (including some gelatin) and calcium oxide, which contain plenty of the target nuclei, were irradiated using a proton beam. In addition, depth activity distributions of virtual positron emitter nuclei generated in each compound from target nuclear fragment reactions were measured using a beam ON-LINE PET system mounted a rotating gantry port (BOLPs-RGp). The measured activity distributions depend on depth or, in other words, energy. The irradiated proton beam energies were 138, 179, and 223 MeV, and measurement time was about 5 h until the measured activity reached the background level. Furthermore, the activity pencil beam data were made using the activity pencil

Time-Resolved Spectroscopy of Active Binary Stars

NASA Technical Reports Server (NTRS)

Brown, Alexander

2000-01-01

This NASA grant covered EUVE observing and data analysis programs during EUVE Cycle 5 GO observing. The research involved a single Guest Observer project 97-EUVE-061 "Time-Resolved Spectroscopy of Active Binary Stars". The grant provided funding that covered 1.25 months of the PI's salary. The activities undertaken included observation planning and data analysis (both temporal and spectral). This project was awarded 910 ksec of observing time to study seven active binary stars, all but one of which were actually observed. Lambda-And was observed on 1997 Jul 30 - Aug 3 and Aug 7-14 for a total of 297 ksec; these observations showed two large complex flares that were analyzed by Osten & Brown (1999). AR Psc, observed for 350 ksec on 1997 Aug 27 - Sep 13, showed only relatively small flares that were also discussed by Osten & Brown (1999). EUVE observations of El Eri were obtained on 1994 August 24-28, simultaneous with ASCA X-ray spectra. Four flares were detected by EUVE with one of these also observed simultaneously, by ASCA. The other three EUVE observations were of the stars BY Dra (1997 Sep 22-28), V478 Lyr (1998 May 18-27), and sigma Gem (1998 Dec 10-22). The first two stars showed a few small flares. The sigma Gem data shows a beautiful complete flare with a factor of ten peak brightness compared to quiescence. The flare rise and almost all the decay phase are observed. Unfortunately no observations in other spectral regions were obtained for these stars. Analysis of the lambda-And and AR Psc observations is complete and the results were published in Osten & Brown (1999). Analysis of the BY Dra, V478 Lyr and sigma Gem EUVE data is complete and will be published in Osten (2000, in prep.). The El Eri EUV analysis is also completed and the simultaneous EUV/X-ray study will be published in Osten et al. (2000, in prep.). Both these latter papers will be submitted in summer 2000. All these results will form part of Rachel Osten's PhD thesis.

Phenomenology of beam driven modes in the field reversed configuration

NASA Astrophysics Data System (ADS)

Magee, Richard; Bolte, Nathan; Clary, Ryan; Necas, Ales; Korepanov, Sergey; Smirnov, Artem; Thompson, Matthew; Tajima, Toshiki; THE TAE Team

2016-10-01

The C-2U experiment offers a unique plasma environment combining a high beta field reversed configuration (FRC) embedded in a low beta magnetic mirror with high power neutral beam injection. The beams are injected tangentially into a modest magnetic field so that the orbits of the resulting fast ions encircle the entire plasma. These large orbit particles sustain and stabilize the plasma and suppress turbulence. Measurements of magnetic fluctuations at the edge of the plasma reveal the presence of three coherent beam driven modes: a low frequency, chirping mode, a mode near the ion cyclotron frequency, and a high frequency compressional Alfven mode. Remarkably, none of these modes are observed to have a deleterious effect on global plasma confinement. In fact, the cyclotron mode has the beneficial effect of dramatically enhancing the DD fusion reaction rate by drawing a trail from the plasma ion energy distribution on a sub-collisional timescale. In this presentation, we experimentally characterize the beam driven modes in the C-2U FRC with data from multiple diagnostics including magnetics, spectroscopy, neutral particle analyzers and fusion product diagnostics. Results are compared to a particle-in-cell simulation in a simplified geometry.

Selective propagation and beam splitting of surface plasmons on metallic nanodisk chains.

PubMed

Hu, Yuhui; Zhao, Di; Wang, Zhenghan; Chen, Fei; Xiong, Xiang; Peng, Ruwen; Wang, Mu

2017-05-01

Manipulating the propagation of surface plasmons (SPs) on a nanoscale is a fundamental issue of nanophotonics. By using focused electron beam, SPs can be excited with high spatial accuracy. Here we report on the propagation of SPs on a chain of gold nanodisks with cathodoluminescence (CL) spectroscopy. Experimental evidence for the propagation of SPs excited by the focused electron beam is demonstrated. The wavelength of the transmitted SPs depends on the geometrical parameters of the nanodisk chain. Furthermore, we design and fabricate a beam splitter, which selectively transmits SPs of certain wavelengths to a specific direction. By scanning the sample surface point by point and collecting the CL spectra, we obtain the spectral mapping and identify that the chain of the smaller nanodisks can efficiently transport SPs at shorter wavelengths. This Letter provides a unique approach to manipulate in-plane propagation of SPs.

The effect of high energy ion beam analysis on D trapping in W

NASA Astrophysics Data System (ADS)

Finlay, T. J.; Davis, J. W.; Schwarz-Selinger, T.; Haasz, A. A.

2017-12-01

High energy ion beam analyses (IBA) are invaluable for measuring concentration depth profiles of light elements in solid materials, and important in the study of fusion fuel retention in tokamaks. Polycrystalline W specimens were implanted at 300 and 500 K, 5-10 × 1023 D m-2 fluence, with deuterium-only and simultaneous D-3%He ion beams. Selected specimens were analysed by elastic recoil detection analysis (ERDA) and/or nuclear reaction analysis (NRA). All specimens were measured by thermal desorption spectroscopy (TDS). The D TDS spectra show an extra peak at 900-1000 K following ERDA and/or NRA measurements. The peak height appears to correlate with the amount of D initially trapped beyond the calculated IBA probe beam peak damage depth. Similar to pre-implantation damage scenarios, the IBA probe beam creates empty high energy traps which later retrap D atoms during TDS heating, which is supported by modelling experimental results using the Tritium Migration Analysis Program.

Perspectives of the Pixel Detector Timepix for Needs of Ion Beam Therapy

NASA Astrophysics Data System (ADS)

Martišíková, M.; Hartmann, B.; Jäkel, O.; Granja, C.; Jakubek, J.

2012-08-01

Radiation therapy with ion beams is a highly precise kind of cancer treatment. In ion beam therapy the finite range of the ion beams in tissue and the increase of ionization density at the end of their path, the Bragg-peak, are exploited. Ions heavier than protons offer in addition increased biological effectiveness and decreased scattering. In this contribution we discuss the potential of a quantum counting and position sensitive semiconductor detector Timepix for its applications in ion beam therapy measurements. It provides high sensitivity and high spatial resolution (pixel pitch 55 μm). The detector, developed by the Medipix Collaboration, consists of a silicon sensor bump bonded to a pixelated readout chip (256 × 256 pixels with 55 μm pitch). An integrated USB-based readout interface together with the Pixelman software enable registering single particles online with 2D-track visualization. The experiments were performed at the Heidelberg Ion Beam Therapy Center (HIT), which is a modern ion beam therapy facility. Patient treatments are performed with proton and carbon ions, which are accelerated by a synchrotron. For dose delivery to the patient an active technique is used: narrow pencil-like beams are scanned over the target volume. The possibility to use the detector for two different applications was investigated: ion spectroscopy and beam delivery monitoring by measurement of secondary charged particles around the patient. During carbon ion therapy, a variety of ion species is created by nuclear fragmentation processes of the primary beam. Since they differ in their biological effectiveness, it is of large interest to measure the ion spectra created under different conditions and to visualize their spatial distribution. The possibility of measurements of ion energy loss in silicon makes Timepix a promising detector for ion-spectroscopic studies in patient-like phantoms. Unpredictable changes in the patient can alter the range of the ion beam in the body

Active metamaterial: Gain and stability, and microfluidic chip for THz cell spectroscopy

NASA Astrophysics Data System (ADS)

Tang, Qi

Metamaterials are artificially designed composite materials which can exhibit unique and unusual properties such as the negative refractive index, negative phase velocity, etc. The concept of metamaterials becomes prevalent in the electromagnetic society since the first experimental implementation in the early 2000s. Many fascinated potential applications, e.g. super lens, invisibility cloaking, and novel antennas that are electrically small, have been proposed based on metamaterials. However, most of the applications still remain in theory and are not suitable for practical applications mainly due to the intrinsic loss and narrow bandwidth (large dispersion) determined by the fundamental physics of metamaterials. In this dissertation, we incorporate active gain devices into conventional passive metamaterials to overcome loss and even provide gain. Two types of active gain negative refractive index metamaterials are proposed, designed and experimentally demonstrated, including an active composite left-/right-handed transmission line and an active volumetric metamaterial. In addition, we investigate the non-Foster circuits for broadband matching of electrically small antennas. A rigorous way of analyzing the stability of non-Foster circuits by normalized determinant function is proposed. We study the practical factors that may affect the stability of non-Foster circuits, including the device parasitics, DC biasing, layouts and load impedance. A stable floating negative capacitor is designed, fabricated and tested. Moreover, it is important to resolve the sign of refractive index for active gain media which can be quite challenging. We investigate the analytical solution of a gain slab system, and apply the Nyquist criterion to analyze the stability of a causal gain medium. We then emphasize that the result of frequency domain simulation has to be treated with care. Lastly, this dissertation discusses another interesting topic about THz spectroscopy of live cells

Focusing adaptive-optics for neutron spectroscopy at extreme conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simeoni, G. G., E-mail: ggsimeoni@outlook.com; Physics Department E13, Technical University of Munich, D-85748 Garching; Valicu, R. G.

2015-12-14

Neutron Spectroscopy employing extreme-conditions sample environments is nowadays a crucial tool for the understanding of fundamental scientific questions as well as for the investigation of materials and chemical-physical properties. For all these kinds of studies, an increased neutron flux over a small sample area is needed. The prototype of a focusing neutron guide component, developed and produced completely at the neutron source FRM II in Garching (Germany), has been installed at the time-of-flight (TOF) disc-chopper neutron spectrometer TOFTOF and came into routine-operation. The design is based on the compressed Archimedes' mirror concept for finite-size divergent sources. It represents a uniquemore » device combining the supermirror technology with Adaptive Optics, suitable for broad-bandwidth thermal-cold TOF neutron spectroscopy (here optimized for 1.4–10 Å). It is able to squeeze the beam cross section down to a square centimeter, with a more than doubled signal-to-background ratio, increased efficiency at high scattering angles, and improved symmetry of the elastic resolution function. We present a comparison between the simulated and measured beam cross sections, as well as the performance of the instrument within real experiments. This work intends to show the unprecedented opportunities achievable at already existing instruments, along with useful guidelines for the design and construction of next-generation neutron spectrometers.« less

High quality atomically thin PtSe2 films grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Yan, Mingzhe; Wang, Eryin; Zhou, Xue; Zhang, Guangqi; Zhang, Hongyun; Zhang, Kenan; Yao, Wei; Lu, Nianpeng; Yang, Shuzhen; Wu, Shilong; Yoshikawa, Tomoki; Miyamoto, Koji; Okuda, Taichi; Wu, Yang; Yu, Pu; Duan, Wenhui; Zhou, Shuyun

2017-12-01

Atomically thin PtSe2 films have attracted extensive research interests for potential applications in high-speed electronics, spintronics and photodetectors. Obtaining high quality thin films with large size and controlled thickness is critical. Here we report the first successful epitaxial growth of high quality PtSe2 films by molecular beam epitaxy. Atomically thin films from 1 ML to 22 ML have been grown and characterized by low-energy electron diffraction, Raman spectroscopy and x-ray photoemission spectroscopy. Moreover, a systematic thickness dependent study of the electronic structure is revealed by angle-resolved photoemission spectroscopy (ARPES), and helical spin texture is revealed by spin-ARPES. Our work provides new opportunities for growing large size single crystalline films to investigate the physical properties and potential applications of PtSe2.

Application of FTIR spectroscopy to the characterization of archeological wood.

PubMed

Traoré, Mohamed; Kaal, Joeri; Martínez Cortizas, Antonio

2016-01-15

Two archeological wood samples were studied by attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectroscopy. They originate from a shipwreck in Ribadeo Bay in the northwest of Spain and from a beam wood of an old nave of the Cathedral of Segovia in the central Spain. Principal component analysis was applied to the transposed data matrix (samples as columns and spectral bands as rows) of 43 recorded spectra (18 in the shipwreck and 25 in the beam wood). The results showed differences between the two samples, with a larger proportion of carbohydrates and smaller proportion of lignin in the beam than in the shipwreck wood. Within the beam wood, lignin content was significantly lower in the recent than the old tree rings (P=0.005). These variations can be attributed to species differences between the two woods (oak and pine respectively), with a mixture of guaiacyl and syringyl in hardwood lignin, whereas softwood lignin consists almost exclusively of guaiacyl moieties. The influence of environmental conditions on the FTIR fingerprint was probably reflected by enhanced oxidation of lignin in aerated conditions (beam wood) and hydrolysis of carbohydrates in submerged-anoxic conditions (shipwreck wood). Molecular characterization by analytical pyrolysis of selected samples from each wood type confirmed the interpretation of the mechanisms behind the variability in wood composition obtained by the FTIR-ATR. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of FTIR spectroscopy to the characterization of archeological wood

NASA Astrophysics Data System (ADS)

Traoré, Mohamed; Kaal, Joeri; Martínez Cortizas, Antonio

2016-01-01

Two archeological wood samples were studied by attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectroscopy. They originate from a shipwreck in Ribadeo Bay in the northwest of Spain and from a beam wood of an old nave of the Cathedral of Segovia in the central Spain. Principal component analysis was applied to the transposed data matrix (samples as columns and spectral bands as rows) of 43 recorded spectra (18 in the shipwreck and 25 in the beam wood). The results showed differences between the two samples, with a larger proportion of carbohydrates and smaller proportion of lignin in the beam than in the shipwreck wood. Within the beam wood, lignin content was significantly lower in the recent than the old tree rings (P = 0.005). These variations can be attributed to species differences between the two woods (oak and pine respectively), with a mixture of guaiacyl and syringyl in hardwood lignin, whereas softwood lignin consists almost exclusively of guaiacyl moieties. The influence of environmental conditions on the FTIR fingerprint was probably reflected by enhanced oxidation of lignin in aerated conditions (beam wood) and hydrolysis of carbohydrates in submerged-anoxic conditions (shipwreck wood). Molecular characterization by analytical pyrolysis of selected samples from each wood type confirmed the interpretation of the mechanisms behind the variability in wood composition obtained by the FTIR-ATR.

Cone penetrometer fiber optic raman spectroscopy probe assembly

DOEpatents

Kyle, Kevin R.; Brown, Steven B.

2000-01-01

A chemically and mechanically robust optical Raman spectroscopy probe assembly that can be incorporated in a cone penetrometer (CPT) for subsurface deployment. This assembly consists of an optical Raman probe and a penetrometer compatible optical probe housing. The probe is intended for in-situ chemical analysis of chemical constituents in the surrounding environment. The probe is optically linked via fiber optics to the light source and the detection system at the surface. A built-in broadband light source provides a strobe method for direct measurement of sample optical density. A mechanically stable sapphire window is sealed directly into the side-wall of the housing using a metallic, chemically resistant, hermetic seal design. This window permits transmission of the interrogation light beam and the resultant signal. The spectroscopy probe assembly is capable of accepting Raman, Laser induced Fluorescence, reflectance, and other optical probes with collimated output for CPT deployment.

Active control of flexural vibrations in beams

NASA Technical Reports Server (NTRS)

Gerhold, Carl H.

1987-01-01

The feasibility of using piezoelectric actuators to control the flexural oscillations of large structures in space is investigated. Flexural oscillations are excited by impulsive loads. The vibratory response can degrade the pointing accuracy of cameras and antennae, and can cause high stresses at structural node points. Piezoelectric actuators have the advantage of exerting localized bending moments. In this way, vibration is controlled without exciting rigid body modes. The actuators are used in collocated sensor/driver pairs to form a feedback control system. The sensor produces a voltage that is proportional to the dynamic stress at the sensor location, and the driver produces a force that is proportional to the voltage applied to it. The analog control system amplifies and phase shifts the sensor signal to produce the voltage signal that is applied to the driver. The feedback control is demonstrated to increase the first mode damping in a cantilever beam by up to 100 percent, depending on the amplifier gain. The damping efficiency of the control system when the piezoelectrics are not optimally positioned at points of high stress in the beam is evaluated.

Implementation of depolarization due to beam-beam effects in the beam-beam interaction simulation tool GUINEA-PIG++

NASA Astrophysics Data System (ADS)

Rimbault, C.; Le Meur, G.; Blampuy, F.; Bambade, P.; Schulte, D.

2009-12-01

Depolarization is a new feature in the beam-beam simulation tool GUINEA-PIG++ (GP++). The results of this simulation are studied and compared with another beam-beam simulation tool, CAIN, considering different beam parameters for the International Linear Collider (ILC) with a centre-of-mass energy of 500 GeV.

High-Resolution Spectroscopy of He{_2}^+ Using Rydberg-Series Extrapolation and Zeeman-Decelerated Supersonic Beams of Metastable He_2

NASA Astrophysics Data System (ADS)

Jansen, Paul; Semeria, Luca; Merkt, Frederic

2016-06-01

Having only three electrons, He{_2}^+ represents a system for which highly accurate ab initio calculations are possible. The latest calculations of rovibrational energies in He{_2}^+ do not include relativistic or QED corrections but claim an accuracy of 120 MHz We have performed high-resolution Rydberg spectroscopy of metastable He_2 molecules and employed multichannel-quantum-defect-theory extrapolation techniques to determine the rotational energy-level structure in the He{_2}^+ ion. To this end, we have produced samples of metastable helium molecules in supersonic beams with velocities tunable down to 100 m/s by combining a cryogenic supersonic-beam source with a multistage Zeeman decelerator. The metastable He_2 molecules are excited to np Rydberg states using the frequency-doubled output of a pulse-amplified ring dye laser. Although the bandwidth of the laser system is too large to observe the reduction of the Doppler width resulting from deceleration, the deceleration greatly simplifies the spectral assignments because of its spin-rotational state selectivity. Our approach enabled us to determine the rotational structure of He_2 with an unprecedented accuracy of 18 MHz, to quantify the size of the relativistic and QED corrections by comparison with the results of Tung et al. and to precisely measure the rotational structure of the metastable state for comparison with the results of Focsa et al. Here, we present an extension of these measurements in which we have measured higher rotational intervals of He{_2}^+. In addition, we have replaced the pulsed UV laser by a cw UV laser and improved the resolution of the spectra by a factor of more than five. W.-C. Tung, M. Pavanello and L. Adamowicz, J. Chem. Phys. 136, 104309 (2012). P. Jansen, L. Semeria, L. Esteban Hofer, S. Scheidegger, J.A. Agner, H. Schmutz, and F. Merkt, Phys. Rev. Lett. 115, 133202 (2015). D. Sprecher, J. Liu, T. Krähenmann, M. Schäfer, and F. Merkt, J. Chem. Phys. 140, 064304 (2014). M

X-ray spectroscopy of E2 and M3 transitions in Ni-like W

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clementson, J.; Beiersdorfer, P.; Gu, M. F.

2010-01-15

The electric quadrupole (E2) and magnetic octupole (M3) ground-state transitions in Ni-like W{sup 46+} have been measured using high-resolution crystal spectroscopy at the LLNL electron-beam ion trap facility. The lines fall in the soft x-ray region near 7.93 A and were originally observed as an unresolved feature in tokamak plasmas. Using flat ammonium dihydrogen phosphate and quartz crystals, the wavelengths, intensities, and polarizations of the two lines have been measured for various electron-beam energies and compared to intensity and polarization calculations performed using the Flexible Atomic Code (FAC).

X-ray Spectroscopy of E2 and M3 Transitions in Ni-like W

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clementson, J; Beiersdorfer, P; Gu, M F

2009-11-09

The electric quadrupole (E2) and magnetic octupole (M3) ground state transitions in Ni-like W{sup 46+} have been measured using high-resolution crystal spectroscopy at the Livermore electron beam ion trap facility. The lines fall in the soft x-ray region near 7.93 {angstrom} and were originally observed as an unresolved feature in tokamak plasmas. Using flat ADP and quartz crystals the wavelengths, intensities, and polarizations of the two lines have been measured for various electron beam energies and compared to intensity and polarization calculations performed using the Flexible Atomic Code (FAC).

Cortical activation patterns to spatially presented pure tone stimuli with different intensities measured by functional near-infrared spectroscopy.

PubMed

Bauernfeind, Günther; Wriessnegger, Selina C; Haumann, Sabine; Lenarz, Thomas

2018-03-08

Functional near-infrared spectroscopy (fNIRS) is an emerging technique for the assessment of functional activity of the cerebral cortex. Recently fNIRS was also envisaged as a novel neuroimaging approach for measuring the auditory cortex activity in the field of in auditory diagnostics. This study aimed to investigate differences in brain activity related to spatially presented sounds with different intensities in 10 subjects by means of functional near-infrared spectroscopy (fNIRS). We found pronounced cortical activation patterns in the temporal and frontal regions of both hemispheres. In contrast to these activation patterns, we found deactivation patterns in central and parietal regions of both hemispheres. Furthermore our results showed an influence of spatial presentation and intensity of the presented sounds on brain activity in related regions of interest. These findings are in line with previous fMRI studies which also reported systematic changes of activation in temporal and frontal areas with increasing sound intensity. Although clear evidence for contralaterality effects and hemispheric asymmetries were absent in the group data, these effects were partially visible on the single subject level. Concluding, fNIRS is sensitive enough to capture differences in brain responses during the spatial presentation of sounds with different intensities in several cortical regions. Our results may serve as a valuable contribution for further basic research and the future use of fNIRS in the area of central auditory diagnostics. © 2018 Wiley Periodicals, Inc.

Chirped-Pulse Millimeter-Wave Spectroscopy of Rydberg-Rydberg Transitions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prozument, Kirill; Colombo, Anthony P.; Zhou Yan

2011-09-30

Transitions between Rydberg states of Ca atoms, in a pulsed, supersonic atomic beam, are directly detected by chirped-pulse millimeter-wave spectroscopy. Broadband, high-resolution spectra with accurate relative intensities are recorded instantly. Free induction decay (FID) of atoms, polarized by the chirped pulse, at their Rydberg-Rydberg transition frequencies, is heterodyne detected, averaged in the time domain, and Fourier transformed into the frequency domain. Millimeter-wave transient nutations are observed, and the possibility of FID evolving to superradiance is discussed.

Parasitic production of slow RI-beam from a projectile fragment separator by ion guide Laser Ion Source (PALIS)

NASA Astrophysics Data System (ADS)

Sonoda, Tetsu

2009-10-01

The projectile fragment separator BigRIPS of RIBF at RIKEN provides a wide variety of short-lived radioactive isotope (RI) ions without restrictions on their lifetime or chemical properties. A universal slow RI-beam facility (SLOWRI) to decelerate the beams from BigRIPS using an RF-carpet ion guide has been proposed as a principal facility of RIBF. However, beam time at such a modern accelerator facility is always limited and operational costs are high. We therefore propose an additional scheme as a complementary option to SLOWRI to drastically enhance the usability of such an expensive facility. In BigRIPS, a single primary beam produces thousands of isotopes but only one isotope is used for an experiment while the other >99.99% of isotopes are simply dumped in the slits or elsewhere in the fragment separator. We plan to locate a compact gas cell with 1 bar Ar at the slits. The thermalized ions in the cell will be quickly neutralized and transported to the exit by gas flow and resonantly re-ionized by lasers. Such low energy RI-beams will always be provided without any restriction to the main experiment. It will allow us to run parasitic experiments for precision atomic or decay spectroscopy, mass measurements. Furthermore, the resonance ionization in the cell itself can be used for high-sensitive laser spectroscopy, which will expand our knowledge of the ground state property of unstable nuclei.

Helium cluster isolation spectroscopy

NASA Astrophysics Data System (ADS)

Higgins, John Paul

Clusters of helium, each containing ~103- 104 atoms, are produced in a molecular beam and are doped with alkali metal atoms (Li, Na, and K) and large organic molecules. Electronic spectroscopy in the visible and UV regions of the spectrum is carried out on the dopant species. Since large helium clusters are liquid and attain an equilibrium internal temperature of 0.4 K, they interact weakly with atoms or molecules absorbed on their surface or resident inside the cluster. The spectra that are obtained are characterized by small frequency shifts from the positions of the gas phase transitions, narrow lines, and cold vibrational temperatures. Alkali atoms aggregate on the helium cluster surface to form dimers and trimers. The spectra of singlet alkali dimers exhibit the presence of elementary excitations in the superfluid helium cluster matrix. It is found that preparation of the alkali molecules on the surface of helium clusters leads to the preferential formation of high-spin, van der Waals bound, triplet dimers and quartet trimers. Four bound-bound and two bound-free transitions are observed in the triplet manifold of the alkali dimers. The quartet trimers serve as an ideal system for the study of a simple unimolecular reaction in the cold helium cluster environment. Analysis of the lowest quartet state provides valuable insight into three-body forces in a van der Waals trimer. The wide range of atomic and molecular systems studied in this thesis constitutes a preliminary step in the development of helium cluster isolation spectroscopy, a hybrid technique combining the advantages of high resolution spectroscopy with the synthetic, low temperature environment of matrices.

Decreased leftward bias of prefrontal activity in autism spectrum disorder revealed by functional near-infrared spectroscopy.

PubMed

Tamura, Ryu; Kitamura, Hideaki; Endo, Taro; Abe, Ryo; Someya, Toshiyuki

2012-01-01

Hemodynamic responses in rostral prefrontal cortex (RoPFC) were measured by functional near-infrared spectroscopy. Although performance level was equal, autistic patients showed a decrease in leftward bias of the balance between right and left RoPFC activity when compared with typically developing children when anatomical imitation was contrasted with mirror-image imitation. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

High-accuracy deep-UV Ramsey-comb spectroscopy in krypton

NASA Astrophysics Data System (ADS)

Galtier, Sandrine; Altmann, Robert K.; Dreissen, Laura S.; Eikema, Kjeld S. E.

2017-01-01

In this paper, we present a detailed account of the first precision Ramsey-comb spectroscopy in the deep UV. We excite krypton in an atomic beam using pairs of frequency-comb laser pulses that have been amplified to the millijoule level and upconverted through frequency doubling in BBO crystals. The resulting phase-coherent deep-UV pulses at 212.55 nm are used in the Ramsey-comb method to excite the two-photon 4p^6 → 4p^5 5p [1/2 ]_0 transition. For the {}^{84}Kr isotope, we find a transition frequency of 2829833101679(103) kHz. The fractional accuracy of 3.7 × 10^{-11} is 34 times better than previous measurements, and also the isotope shifts are measured with improved accuracy. This demonstration shows the potential of Ramsey-comb excitation for precision spectroscopy at short wavelengths.

Module for multiphoton high-resolution hyperspectral imaging and spectroscopy

NASA Astrophysics Data System (ADS)

Zeytunyan, Aram; Baldacchini, Tommaso; Zadoyan, Ruben

2018-02-01

We developed a module for dual-output, dual-wavelength lasers that facilitates multiphoton imaging and spectroscopy experiments and enables hyperspectral imaging with spectral resolution up to 5 cm-1. High spectral resolution is achieved by employing spectral focusing. Specifically, two sets of grating pairs are used to control the chirps in each laser beam. In contrast with the approach that uses fixed-length glass rods, grating pairs allow matching the spectral resolution and the linewidths of the Raman lines of interest. To demonstrate the performance of the module, we report the results of spectral focusing CARS and SRS microscopy experiments for various test samples and Raman shifts. The developed module can be used for a variety of multimodal imaging and spectroscopy applications, such as single- and multi-color two-photon fluorescence, second harmonic generation, third harmonic generation, pump-probe, transient absorption, and others.

Stability of a Light Sail Riding on a Laser Beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manchester, Zachary; Loeb, Abraham, E-mail: zmanchester@seas.harvard.edu

2017-03-10

The stability of a light sail riding on a laser beam is analyzed both analytically and numerically. Conical sails on Gaussian beams, which have been studied in the past, are shown to be unstable without active control or additional mechanical modifications. A new architecture for a passively stable sail-and-beam configuration is proposed. The novel spherical shell design for the sail is capable of “beam riding” without the need for active feedback control. Full three-dimensional ray-tracing simulations are performed to verify our analytical results.

Setup for in situ deep level transient spectroscopy of semiconductors during swift heavy ion irradiation.

PubMed

Kumar, Sandeep; Kumar, Sugam; Katharria, Y S; Safvan, C P; Kanjilal, D

2008-05-01

A computerized system for in situ deep level characterization during irradiation in semiconductors has been set up and tested in the beam line for materials science studies of the 15 MV Pelletron accelerator at the Inter-University Accelerator Centre, New Delhi. This is a new facility for in situ irradiation-induced deep level studies, available in the beam line of an accelerator laboratory. It is based on the well-known deep level transient spectroscopy (DLTS) technique. High versatility for data manipulation is achieved through multifunction data acquisition card and LABVIEW. In situ DLTS studies of deep levels produced by impact of 100 MeV Si ions on Aun-Si(100) Schottky barrier diode are presented to illustrate performance of the automated DLTS facility in the beam line.

Persistence of the Z =28 Shell Gap Around 78Ni: First Spectroscopy of 79Cu

NASA Astrophysics Data System (ADS)

Olivier, L.; Franchoo, S.; Niikura, M.; Vajta, Z.; Sohler, D.; Doornenbal, P.; Obertelli, A.; Tsunoda, Y.; Otsuka, T.; Authelet, G.; Baba, H.; Calvet, D.; Château, F.; Corsi, A.; Delbart, A.; Gheller, J.-M.; Gillibert, A.; Isobe, T.; Lapoux, V.; Matsushita, M.; Momiyama, S.; Motobayashi, T.; Otsu, H.; Péron, C.; Peyaud, A.; Pollacco, E. C.; Roussé, J.-Y.; Sakurai, H.; Santamaria, C.; Sasano, M.; Shiga, Y.; Takeuchi, S.; Taniuchi, R.; Uesaka, T.; Wang, H.; Yoneda, K.; Browne, F.; Chung, L. X.; Dombradi, Z.; Flavigny, F.; Giacoppo, F.; Gottardo, A.; Hadyńska-Klek, K.; Korkulu, Z.; Koyama, S.; Kubota, Y.; Lee, J.; Lettmann, M.; Louchart, C.; Lozeva, R.; Matsui, K.; Miyazaki, T.; Nishimura, S.; Ogata, K.; Ota, S.; Patel, Z.; Sahin, E.; Shand, C.; Söderström, P.-A.; Stefan, I.; Steppenbeck, D.; Sumikama, T.; Suzuki, D.; Werner, V.; Wu, J.; Xu, Z.

2017-11-01

In-beam γ -ray spectroscopy of 79Cu is performed at the Radioactive Isotope Beam Factory of RIKEN. The nucleus of interest is produced through proton knockout from a 80Zn beam at 270 MeV /nucleon . The level scheme up to 4.6 MeV is established for the first time and the results are compared to Monte Carlo shell-model calculations. We do not observe significant knockout feeding to the excited states below 2.2 MeV, which indicates that the Z =28 gap at N =50 remains large. The results show that the 79Cu nucleus can be described in terms of a valence proton outside a 78Ni core, implying the magic character of the latter.

Electron Beam Irradiated Intercalated CNT Yarns For Aerospace Applications

NASA Technical Reports Server (NTRS)

Waters, Deborah L.; Gaier, James R.; Williams, Tiffany S.; Lopez Calero, Johnny E.; Ramirez, Christopher; Meador, Michael A.

2015-01-01

Multi-walled CNT yarns have been experimentally and commercially created to yield lightweight, high conductivity fibers with good tensile properties for application as electrical wiring and multifunctional tendons. Multifunctional tendons are needed as the cable structures in tensegrity robots for use in planetary exploration. These lightweight robust tendons can provide mechanical strength for movement of the robot in addition to power distribution and data transmission. In aerospace vehicles, such as Orion, electrical wiring and harnessing mass can approach half of the avionics mass. Use of CNT yarns as electrical power and data cables could reduce mass of the wiring by thirty to seventy percent. These fibers have been intercalated with mixed halogens to increase their specific electrical conductivity to that near copper. This conductivity, combined with the superior strength and fatigue resistance makes it an attractive alternative to copper for wiring and multifunctional tendon applications. Electron beam irradiation has been shown to increase mechanical strength in pristine CNT fibers through increased cross-linking. Both pristine and intercalated CNT yarns have been irradiated using a 5-megavolt electron beam for various durations and the conductivities and tensile properties will be discussed. Structural information obtained using a field emission scanning electron microscope, energy dispersive X-ray spectroscopy (EDS), and Raman spectroscopy will correlate microstructural details with bulk properties.

SU-E-T-666: Radionuclides and Activity of the Patient Apertures Used in a Proton Beam of Wobbling System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, B.Y.; Chen, H.H.; Tsai, H.Y.

2015-06-15

Purpose: To identify the radionuclides and quantify the activity of the patient apertures used in a 190-MeV proton beam of wobbling system. Methods: A proton beam of wobbling system in the first proton center in Taiwan, Chang Gung Memorial Hospital at Linkou, was used to bombard the patient apertures. The patient aperture was composed of 60.5 % copper, 39.4 % Zinc, 0.05 % iron, 0.05 % lead. A protable high-purity germanium (HPGe) coaxial detector was used to measure the spectra of the induced nuclides of patient apertures. The analysis of the spectra and the identification of the radionuclides were preliminarilymore » operated by the Nuclide Navigator III Master Library. On the basis of the results by Nuclide Navigator III Master Library, we manually selected the reliable nuclides by the gamma-ray energies, branching ratio, and half life. In the spectra, we can quantify the activity of radionuclides by the Monte Carlo efficiency transfer method. Results: In this study, the radioisotopes activated in patient apertures by the 190-MeV proton beam were divided into two categories. The first category is long half-life radionuclides, such as Co-56 (half life, 77.3 days). Other radionuclides of Cu-60, Cu-61, Cu-62, Cu-66, and Zn-62 have shorter half life. The radionuclide of Cu-60 had the highest activity. From calculation with the efficiency transfer method, the deviations between the computed results and the measured efficiencies were mostly within 10%. Conclusion: To identify the radionuclides and quantify the activity helps us to estimate proper time intervals for cooling the patient apertures. This study was supported by the grants from the Chang Gung Memorial Hospital (CMRPD1C0682)« less

Comparative study of cross-field and field-aligned electron beams in active experiments. [in upper atmosphere

NASA Technical Reports Server (NTRS)

Winglee, R. M.; Pritchett, P. L.

1988-01-01

Beam-plasma interactions associated with the cross-field and field-aligned injection of electron beams from spacecraft were investigated using a two-dimensional (three velocity component) electrostatic particle simulations. It is shown that the beam properties and plasma response can be characterized well by the ratio between the stagnation time and the plasma response time, which depends on the ratio of the ambient plasma density to the beam density, the beam width, the beam energy, and the spacecraft length. It was found that the beams injected across the field lines tend to lose their coherence after about one or two gyrations due to space-charge oscillations induced by the beam, irrespective of the spacecraft charging. These oscillations scatter the beam electrons into a hollow cylinder of a radius equal to a beam electron gyroradius and thickness of the order of two beam Debye lengths. Parallel injected beams are subjected to similar oscillations, which cause the beam to expand to fill a solid cylinder of a comparable thickness.

Initial Results of Optical Vortex Laser Absorption Spectroscopy in the HYPER-I Device

NASA Astrophysics Data System (ADS)

Yoshimura, Shinji; Asai, Shoma; Aramaki, Mitsutoshi; Terasaka, Kenichiro; Ozawa, Naoya; Tanaka, Masayoshi; Morisaki, Tomohiro

2015-11-01

Optical vortex beams have a potential to make a new Doppler measurement, because not only parallel but perpendicular movement of atoms against the beam axis causes the Doppler shift of their resonant absorption frequency. As the first step of a proof-of-principle experiment, we have performed the optical vortex laser absorption spectroscopy for metastable argon neutrals in an ECR plasma produced in the HYPER-I device at the National Institute for Fusion Science, Japan. An external cavity diode laser (TOPTICA, DL100) of which center wavelength was 696.735 nm in vacuum was used for the light source. The Hermite-Gaussian (HG) beam was converted into the Laguerre-Gaussian (LG) beam (optical vortex) by a computer-generated hologram displayed on the spatial light modulator (Hamamatsu, LCOS-SLM X10468-07). In order to make fast neutral flow across the LG beam, a high speed solenoid valve system was installed on the HYPER-I device. Initial results including the comparison of absorption spectra for HG and LG beams will be presented. This study was supported by NINS young scientists collaboration program for cross-disciplinary study, NIFS collaboration research program (NIFS13KOAP026), and JSPS KAKENHI grant number 15K05365.

Color change of tourmaline by heat treatment and electron beam irradiation: UV-Visible, EPR, and Mid-IR spectroscopic analyses

NASA Astrophysics Data System (ADS)

Maneewong, Apichate; Seong, Baek Seok; Shin, Eun Joo; Kim, Jeong Seog; Kajornrith, Varavuth

2016-01-01

The color of pink tourmaline gemstone changed to colorless when heating at temperature of 600 °C in air. This colorless tourmaline recovered its pink color when irradiated with an electron beam (e-beam) of 800 kGy. The origin of the color change was investigated in three types of tourmaline gemstones, two pink are from Afghanistan and one green are from Nigeria, by using Ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), Electron paramagnetic resonance (EPR), and Energy Dispersive X-ray Fluorescence (EDXRF). The UV-Vis absorption spectrum of the pink tourmaline with higher Mn concentration (T2, 0.24 wt%) showed characteristic absorption peaks originating from the Mn3+ color center: two absorption bands centered at wavelength of 396 and 520 nm, respectively. Both absorption bands disappeared when heated in air at 600 °C and then reappeared when irradiated with an e-beam at 800 kGy. EPR T2 spectra showed that the color change was related to the valence change of Mn3+ to Mn2+ and vice versa. The pink tourmaline of lower MnO content (T1, 0.08 wt%) also became colorless when heated, but the color was not recovered when the gemstone underwent e-beam irradiation. Instead, a yellow color was obtained. UV-Vis and FTIR spectra indicated that this yellow color originated from a decomposition of the hydroxyl group (-OH) into O- and Ho by the e-beam irradiation. Green tourmaline did not show any color change with either heat treatment or e-beam irradiation.

Finite element modeling of light propagation in turbid media under illumination of a continuous-wave beam

USDA-ARS?s Scientific Manuscript database

Spatially-resolved spectroscopy provides a means for measuring the optical properties of biological tissues, based on analytical solutions to diffusion approximation for semi-infinite media under the normal illumination of infinitely small size light beam. The method is, however, prone to error in m...

Automatic laser beam alignment using blob detection for an environment monitoring spectroscopy

NASA Astrophysics Data System (ADS)

Khidir, Jarjees; Chen, Youhua; Anderson, Gary

2013-05-01

This paper describes a fully automated system to align an infra-red laser beam with a small retro-reflector over a wide range of distances. The component development and test were especially used for an open-path spectrometer gas detection system. Using blob detection under OpenCV library, an automatic alignment algorithm was designed to achieve fast and accurate target detection in a complex background environment. Test results are presented to show that the proposed algorithm has been successfully applied to various target distances and environment conditions.

Isotope shifts from collinear laser spectroscopy of doubly charged yttrium isotopes

NASA Astrophysics Data System (ADS)

Vormawah, L. J.; Vilén, M.; Beerwerth, R.; Campbell, P.; Cheal, B.; Dicker, A.; Eronen, T.; Fritzsche, S.; Geldhof, S.; Jokinen, A.; Kelly, S.; Moore, I. D.; Reponen, M.; Rinta-Antila, S.; Stock, S. O.; Voss, A.

2018-04-01

Collinear laser spectroscopy has been performed on doubly charged ions of radioactive yttrium in order to study the isotope shifts of the 294.6-nm 5 s 1/2 2S →5 p 1/2 2P line. The potential of such an alkali-metal-like transition to improve the reliability of atomic-field-shift and mass-shift factor calculations, and hence the extraction of nuclear mean-square radii, is discussed. Production of yttrium ion beams for such studies is available at the IGISOL IV Accelerator Laboratory, Jyväskylä, Finland. This newly recommissioned facility is described here in relation to the on-line study of accelerator-produced short-lived isotopes using collinear laser spectroscopy and application of the technique to doubly charged ions.

Orientational analysis of dodecanethiol and p-nitrothiophenol SAMs on metals with polarisation-dependent SFG spectroscopy.

PubMed

Cecchet, Francesca; Lis, Dan; Guthmuller, Julien; Champagne, Benoît; Caudano, Yves; Silien, Christophe; Mani, Alaa Addin; Thiry, Paul A; Peremans, André

2010-02-22

Polarisation-dependent sum frequency generation (SFG) spectroscopy is used to investigate the orientation of molecules on metallic surfaces. In particular, self-assembled monolayers (SAMs) of dodecanethiol (DDT) and of p-nitrothiophenol (p-NTP), grown on Pt and on Au, have been chosen as models to highlight the ability of combining ppp and ssp polarisations sets (representing the polarisation of the involved beams in the conventional order of SFG, Vis and IR beam) to infer orientational information at metallic interfaces. Indeed, using only the ppp set of data, as it is usually done for metallic surfaces, is not sufficient to determine the full molecular orientation. We show here that simply combining ppp and ssp polarisations enables both the tilt and rotation angles of methyl groups in DDT SAMs to be determined. Moreover, for p-NTP, while the SFG active vibrations detected with the ppp polarisation alone provide no orientational information, however, the combination with ssp spectra enables to retrieve the tilt angle of the p-NTP 1,4 axis. Though orientational information obtained by polarisation-dependent measurements has been extensively used at insulating interfaces, we report here their first application to metallic surfaces.

Particle-Induced Gamma-ray Emission Spectroscopy Over a Broad Range of Elements

NASA Astrophysics Data System (ADS)

Olds, Hannah; Wilkinson, John; Tighe, Meghanne; McLallen, Walter; McGuire, Patrick

2017-09-01

Ion beam analysis is a common application of nuclear physics that allows elemental and isotopic information about materials to be determined from accelerated light ion beams One of the best know ion beam analysis techniques is Particle-Induced Gamma-ray Emission (PIGE) spectroscopy, which can be used ex vacuo to identify the elements of interest in almost any solid target. The energies of the gamma-rays emitted by excited nuclei will be unique to each element and depend on its nuclear structure. For the most sensitivity, the accelerated ions should exceed the Coulomb barrier of the target, but many isotopes are known to be accessible to PIGE even below the Coulomb barrier. To explore the sensitivity of PIGE across the periodic table, PIGE measurements were made on elements with Z = 5, 9, 11-15, 17, 19-35, 37, 42, 44-48, 53, 56, 60, 62, 73, and 74 using 3.4 MeV protons. These measurements will be compared with literature values and be used as a basis for comparison with higher-energy proton beams available at the University of Notre Dame's St. Andre accelerator when it comes online this Fall. The beam normalization technique of using atmospheric argon and its 1459 keV gamma-ray to better estimate the integrated beam on target will also be discussed. Funded by the NSF REU program and the University of Notre Dame.

Optical signatures of molecular particles via mass-selected cluster spectroscopy

NASA Technical Reports Server (NTRS)

Duncan, Michael A.

1990-01-01

A new molecular beam apparatus was developed to study optical absorption in cold (less than 100 K) atomic clusters and complexes produced by their condensation with simple molecular gases. In this instrument, ionized clusters produced in a laser vaporization nozzle source are mass selected and studied with photodissociation spectroscopy at visible and ultraviolet wavelengths. This new approach can be applied to synthesize and characterize numerous particulates and weakly bound complexes expected in planetary atmospheres and in comets.

Pump-probe surface photovoltage spectroscopy measurements on semiconductor epitaxial layers.

PubMed

Jana, Dipankar; Porwal, S; Sharma, T K; Kumar, Shailendra; Oak, S M

2014-04-01

Pump-probe Surface Photovoltage Spectroscopy (SPS) measurements are performed on semiconductor epitaxial layers. Here, an additional sub-bandgap cw pump laser beam is used in a conventional chopped light geometry SPS setup under the pump-probe configuration. The main role of pump laser beam is to saturate the sub-bandgap localized states whose contribution otherwise swamp the information related to the bandgap of material. It also affects the magnitude of Dember voltage in case of semi-insulating (SI) semiconductor substrates. Pump-probe SPS technique enables an accurate determination of the bandgap of semiconductor epitaxial layers even under the strong influence of localized sub-bandgap states. The pump beam is found to be very effective in suppressing the effect of surface/interface and bulk trap states. The overall magnitude of SPV signal is decided by the dependence of charge separation mechanisms on the intensity of the pump beam. On the contrary, an above bandgap cw pump laser can be used to distinguish the signatures of sub-bandgap states by suppressing the band edge related feature. Usefulness of the pump-probe SPS technique is established by unambiguously determining the bandgap of p-GaAs epitaxial layers grown on SI-GaAs substrates, SI-InP wafers, and p-GaN epilayers grown on Sapphire substrates.

FAR-INFRARED SPECTROSCOPY OF CATIONIC POLYCYCLIC AROMATIC HYDROCARBONS: ZERO KINETIC ENERGY PHOTOELECTRON SPECTROSCOPY OF PENTACENE VAPORIZED FROM LASER DESORPTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Jie; Han Fangyuan; Pei Linsen

2010-05-20

The distinctive set of infrared (IR) emission bands at 3.3, 6.2, 7.7, 8.6, and 11.3 {mu}m are ubiquitously seen in a wide variety of astrophysical environments. They are generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. However, not a single PAH species has yet been identified in space, as the mid-IR vibrational bands are mostly representative of functional groups and thus do not allow one to fingerprint individual PAH molecules. In contrast, the far-IR (FIR) bands are sensitive to the skeletal characteristics of a molecule, hence they are important for chemical identification of unknown species. With an aim to offermore » laboratory astrophysical data for the Herschel Space Observatory, Stratospheric Observatory for Infrared Astronomy, and similar future space missions, in this work we report neutral and cation FIR spectroscopy of pentacene (C{sub 22}H{sub 14}), a five-ring PAH molecule. We report three IR active modes of cationic pentacene at 53.3, 84.8, and 266 {mu}m that may be detectable by space missions such as the SAFARI instrument on board SPICA. In the experiment, pentacene is vaporized from a laser desorption source and cooled by a supersonic argon beam. We have obtained results from two-color resonantly enhanced multiphoton ionization and two-color zero kinetic energy photoelectron (ZEKE) spectroscopy. Several skeletal vibrational modes of the first electronically excited state of the neutral species and those of the cation are assigned, with the aid of ab initio and density functional calculations. Although ZEKE is governed by the Franck-Condon principle different from direct IR absorption or emission, vibronic coupling in the long ribbon-like molecule results in the observation of a few IR active modes. Within the experimental resolution of {approx}7 cm{sup -1}, the frequency values from our calculation agree with the experiment for the cation, but differ for the electronically excited intermediate state. Consequently

Understanding individual defects in CdTe thin-film solar cells via STEM: From atomic structure to electrical activity

DOE PAGES

Li, Chen; Poplawsky, Jonathan; Yan, Yanfa; ...

2017-07-01

Here in this paper we review a systematic study of the structure-property correlations of a series of defects in CdTe solar cells. A variety of experimental methods, including aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy, energy dispersive X-ray spectroscopy, and electron-beam-induced current have been combined with density-functional theory. The research traces the connections between the structures and electrical activities of individual defects including intra-grain partial dislocations, grain boundaries and the CdTe/CdS interface. The interpretations of the physical origin underlying the structure-property correlation provide insights that should further the development of future CdTe solar cells.

Understanding individual defects in CdTe thin-film solar cells via STEM: From atomic structure to electrical activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Chen; Poplawsky, Jonathan; Yan, Yanfa

Here in this paper we review a systematic study of the structure-property correlations of a series of defects in CdTe solar cells. A variety of experimental methods, including aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy, energy dispersive X-ray spectroscopy, and electron-beam-induced current have been combined with density-functional theory. The research traces the connections between the structures and electrical activities of individual defects including intra-grain partial dislocations, grain boundaries and the CdTe/CdS interface. The interpretations of the physical origin underlying the structure-property correlation provide insights that should further the development of future CdTe solar cells.

Identification of active fluorescence stained bacteria by Raman spectroscopy

NASA Astrophysics Data System (ADS)

Krause, Mario; Beyer, Beatrice; Pietsch, Christian; Radt, Benno; Harz, Michaela; Rösch, Petra; Popp, Jürgen

2008-04-01

Microorganisms can be found everywhere e.g. in food both as useful ingredients or harmful contaminations causing food spoilage. Therefore, a fast and easy to handle analysis method is needed to detect bacteria in different kinds of samples like meat, juice or air to decide if the sample is contaminated by harmful microorganisms. Conventional identification methods in microbiology require always cultivation and therefore are time consuming. In this contribution we present an analysis approach to identify fluorescence stained bacteria on strain level by means of Raman spectroscopy. The stained bacteria are highlighted and can be localized easier against a complex sample environment e.g. in food. The use of Raman spectroscopy in combination with chemometrical methods allows the identification of single bacteria within minutes.

Active Control of Sound Radiation due to Subsonic Wave Scattering from Discontinuities on Thin Elastic Beams.

NASA Astrophysics Data System (ADS)

Guigou, Catherine Renee J.

1992-01-01

Much progress has been made in recent years in active control of sound radiation from vibrating structures. Reduction of the far-field acoustic radiation can be obtained by directly modifying the response of the structure by applying structural inputs rather than by adding acoustic sources. Discontinuities, which are present in many structures are often important in terms of sound radiation due to wave scattering behavior at their location. In this thesis, an edge or boundary type discontinuity (clamped edge) and a point discontinuity (blocking mass) are analytically studied in terms of sound radiation. When subsonic vibrational waves impinge on these discontinuities, large scattered sound levels are radiated. Active control is then achieved by applying either control forces, which approximate shakers, or pairs of control moments, which approximate piezoelectric actuators, near the discontinuity. Active control of sound radiation from a simply-supported beam is also examined. For a single frequency, the flexural response of the beam subject to an incident wave or an input force (disturbance) and to control forces or control moments is expressed in terms of waves of both propagating and near-field types. The far-field radiated pressure is then evaluated in terms of the structural response, using Rayleigh's formula or a stationary phase approach, depending upon the application. The control force and control moment magnitudes are determined by optimizing a quadratic cost function, which is directly related to the control performance. On determining the optimal control complex amplitudes, these can be resubstituted in the constitutive equations for the system under study and the minimized radiated fields can be evaluated. High attenuation in radiated sound power and radiated acoustic pressure is found to be possible when one or two active control actuators are located near the discontinuity, as is shown to be mostly associated with local changes in beam response near

Surface-enhanced Raman scattering active gold nanoparticle/nanohole arrays fabricated through electron beam lithography

NASA Astrophysics Data System (ADS)

Wu, Tsunghsueh; Lin, Yang-Wei

2018-03-01

Effective surface-enhanced Raman scattering (SERS)-active substrates from gold nanoparticle and gold nanohole arrays were successfully fabricated through electron beam lithography with precise computer-aided control of the unit size and intergap distance. Their SERS performance was evaluated using 4-mercaptobenzoic acid (4-MBA). These gold arrays yielded strong SERS signals under 785 nm laser excitation. The enhancement factors for 4-MBA molecules on the prepared gold nanoparticle and nanohole arrays maxed at 1.08 × 107 and 8.61 × 106, respectively. The observed increase in SERS enhancement was attributed to the localized surface plasmon resonance (LSPR) wavelength shifting toward the near-infrared regime when the gold nanohole diameter increased, in agreement with the theoretical prediction in this study. The contribution of LSPR to the Raman enhancement from nanohole arrays deposited on fluorine-doped tin oxide glass was elucidated by comparing SERS and transmission spectra. This simple fabrication procedure, which entails employing electron beam lithography and the controllability of the intergap distance, suggests highly promising uses of nanohole arrays as functional components in sensing and photonic devices.

Evidence of locally enhanced target heating due to instabilities of counter-streaming fast electron beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koester, Petra; Cecchetti, Carlo A.; Booth, Nicola

2015-02-15

The high-current fast electron beams generated in high-intensity laser-solid interactions require the onset of a balancing return current in order to propagate in the target material. Such a system of counter-streaming electron currents is unstable to a variety of instabilities such as the current-filamentation instability and the two-stream instability. An experimental study aimed at investigating the role of instabilities in a system of symmetrical counter-propagating fast electron beams is presented here for the first time. The fast electron beams are generated by double-sided laser-irradiation of a layered target foil at laser intensities above 10{sup 19 }W/cm{sup 2}. High-resolution X-ray spectroscopy ofmore » the emission from the central Ti layer shows that locally enhanced energy deposition is indeed achieved in the case of counter-propagating fast electron beams.« less

Activation of accelerator construction materials by heavy ions

NASA Astrophysics Data System (ADS)

Katrík, P.; Mustafin, E.; Hoffmann, D. H. H.; Pavlovič, M.; Strašík, I.

2015-12-01

Activation data for an aluminum target irradiated by 200 MeV/u 238U ion beam are presented in the paper. The target was irradiated in the stacked-foil geometry and analyzed using gamma-ray spectroscopy. The purpose of the experiment was to study the role of primary particles, projectile fragments, and target fragments in the activation process using the depth profiling of residual activity. The study brought information on which particles contribute dominantly to the target activation. The experimental data were compared with the Monte Carlo simulations by the FLUKA 2011.2c.0 code. This study is a part of a research program devoted to activation of accelerator construction materials by high-energy (⩾200 MeV/u) heavy ions at GSI Darmstadt. The experimental data are needed to validate the computer codes used for simulation of interaction of swift heavy ions with matter.

Active Vibration Control of Elastic Beam by Means of Shape Memory Alloy Layers

NASA Technical Reports Server (NTRS)

Chen, Q.; Levy, C.

1996-01-01

The mathematical model of a flexible beam covered with shape memory alloy (SMA) layers is presented. The SMA layers are used as actuators, which are capable of changing their elastic modulus and recovery stress, thus changing the natural frequency of, and adjusting the excitation to, the vibrating beam. The frequency factor variation as a function of SMA Young's modulus, SMA layer thickness and beam thickness is discussed. Also control of the beam employing an optimal linear control law is evaluated. The control results indicate how the system reacts to various levels of excitation input through the non-homogeneous recovery shear term of the governing differential equation.

Coronagraphic Notch Filter for Raman Spectroscopy

NASA Technical Reports Server (NTRS)

Cohen, David; Stirbl, Robert

2004-01-01

A modified coronagraph has been proposed as a prototype of improved notch filters in Raman spectrometers. Coronagraphic notch filters could offer alternatives to both (1) the large and expensive double or triple monochromators in older Raman spectrometers and (2) holographic notch filters, which are less expensive but are subject to environmental degradation as well as to limitations of geometry and spectral range. Measurement of a Raman spectrum is an exercise in measuring and resolving faint spectral lines close to a bright peak: In Raman spectroscopy, a monochromatic beam of light (the pump beam) excites a sample of material that one seeks to analyze. The pump beam generates a small flux of scattered light at wavelengths slightly greater than that of the pump beam. The shift in wavelength of the scattered light from the pump wavelength is known in the art as the Stokes shift. Typically, the flux of scattered light is of the order of 10 7 that of the pump beam and the Stokes shift lies in the wave-number range of 100 to 3,000 cm 1. A notch filter can be used to suppress the pump-beam spectral peak while passing the nearby faint Raman spectral lines. The basic principles of design and operation of a coronagraph offer an opportunity for engineering the spectral transmittance of the optics in a Raman spectrometer. A classical coronagraph may be understood as two imaging systems placed end to end, such that the first system forms an intermediate real image of a nominally infinitely distant object and the second system forms a final real image of the intermediate real image. If the light incident on the first telescope is collimated, then the intermediate image is a point-spread function (PSF). If an appropriately tailored occulting spot (e.g., a Gaussian-apodized spot with maximum absorption on axis) is placed on the intermediate image plane, then the instrument inhibits transmission of light from an on-axis source. However, the PSFs of off-axis light sources are

Control of the kerf size and microstructure in Inconel 738 superalloy by femtosecond laser beam cutting

NASA Astrophysics Data System (ADS)

Wei, J.; Ye, Y.; Sun, Z.; Liu, L.; Zou, G.

2016-05-01

Femtosecond laser beam cutting is becoming widely used to meet demands for increasing accuracy in micro-machining. In this paper, the effects of processing parameters in femtosecond laser beam cutting on the kerf size and microstructure in Inconel 738 have been investigated. The defocus, pulse width and scanning speed were selected to study the controllability of the cutting process. Adjusting and matching the processing parameters was a basic enhancement method to acquire well defined kerf size and the high-quality ablation of microstructures, which has contributed to the intensity clamping effect. The morphology and chemical compositions of these microstructures on the cut surface have been characterized by a scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Additionally, the material removal mechanism and oxidation mechanism on the Inconel 738 cut surface have also been discussed on the basis of the femtosecond laser induced normal vaporization or phase explosion, and trapping effect of the dangling bonds.