A fast new cadioptric design for fiber-fed spectrographs

NASA Astrophysics Data System (ADS)

Saunders, Will

2012-09-01

The next generation of massively multiplexed multi-object spectrographs (DESpec, SUMIRE, BigBOSS, 4MOST, HECTOR) demand fast, efficient and affordable spectrographs, with higher resolutions (R = 3000-5000) than current designs. Beam-size is a (relatively) free parameter in the design, but the properties of VPH gratings are such that, for fixed resolution and wavelength coverage, the effect on beam-size on overall VPH efficiency is very small. For alltransmissive cameras, this suggests modest beam-sizes (say 80-150mm) to minimize costs; while for cadioptric (Schmidt-type) cameras, much larger beam-sizes (say 250mm+) are preferred to improve image quality and to minimize obstruction losses. Schmidt designs have benefits in terms of image quality, camera speed and scattered light performance, and recent advances such as MRF technology mean that the required aspherics are no longer a prohibitive cost or risk. The main objections to traditional Schmidt designs are the inaccessibility of the detector package, and the loss in throughput caused by it being in the beam. With expected count rates and current read-noise technology, the gain in camera speed allowed by Schmidt optics largely compensates for the additional obstruction losses. However, future advances in readout technology may erase most of this compensation. A new Schmidt/Maksutov-derived design is presented, which differs from previous designs in having the detector package outside the camera, and adjacent to the spectrograph pupil. The telescope pupil already contains a hole at its center, because of the obstruction from the telescope top-end. With a 250mm beam, it is possible to largely hide a 6cm × 6cm detector package and its dewar within this hole. This means that the design achieves a very high efficiency, competitive with transmissive designs. The optics are excellent, as least as good as classic Schmidt designs, allowing F/1.25 or even faster cameras. The principal hardware has been costed at $300K per arm, making the design affordable.

Discovery and Classification of Optical Transient in M81 : P60- M81-081203

NASA Astrophysics Data System (ADS)

Kasliwal, M. M.; Cenko, S. B.; Quimby, R.; Rau, A.; Ofek, E. O.; Kulkarni, S. R.

2008-12-01

On UT 2008 Dec 3.303, P60-FasTING (Palomar 60-inch Fast Transients In Nearby Galaxies) discovered an optical transient in M81 at RA(J2000) = 09:55:16.920, DEC(J2000)=+69:02:17.68, offset from the nucleus by 87.2"W, 97.4"S. P60-M81-081203 had a brightness of g = 20.5 +/- 0.1 at discovery. It was not detected by P60 to g > 22.3 on Nov 30.410. There is no counterpart in SDSS or SIMBAD. Follow-up spectroscopy with the Double Beam Spectrograph on the Palomar Hale telescope showed a featureless spectrum on Dec 4 UT and Dec 5 UT.

Discovery and Classification of Nova in M31 : P60-M31-081230

NASA Astrophysics Data System (ADS)

Kasliwal, M. M.; Rau, A.; Salvato, M.; Cenko, S. B.; Ofek, E. O.; Quimby, R.; Kulkarni, S. R.

2009-01-01

On UT 2008 Dec 30.207, P60-FasTING (Palomar 60-inch Fast Transients In Nearby Galaxies) discovered an optical transient in M31 at RA(J2000) = 00:43:05.027, DEC(J2000)=+41:17:52.25, offset from the nucleus by 233.4"E,103.8"N. P60-M31-081230 had a brightness of g = 20.5 +/- 0.2 at discovery. It was not detected by P60 to g > 22.0 on Dec 29.140. There is no counterpart in SIMBAD. Follow-up spectroscopy with the Double Beam Spectrograph on the Palomar Hale telescope on Dec 31.104 revealed prominent Balmer emission and strong P Cygni profiles of several Fe II lines.

Investigation of focal ratio degradation in optical fibres for astronomical instrumentation

NASA Astrophysics Data System (ADS)

Crause, Lisa; Bershady, Matthew; Buckley, David

2008-07-01

A differential method was used to investigate the focal ratio degradation (FRD) exhibited by, and throughput of, a selection of current-generation optical fibres. These fibres were tested to establish which would be best suited to feed the High Resolution Spectrograph being built for the Southern African Large Telescope (SALT), as well as for future instruments on WIYN and SALT. The double re-imaging system of Bershady et al. (2004) was substantially modified to improve image quality and measurement efficiency, and to permit a direct FRD-measurement in the far-field. The re-imaging method compares the beam profile produced by light which passes through a fibre to that which does not. Broad and intermediate band-pass filters were used between 400-800 nm to test for wavelength dependence in the observed FRD over a wide range in beam-speeds. Our results continue to be at odds with a mico-bend model for FRD. We conclude that the new Polymicro FBP fibre is the most suitable product for broadband applications.

CARMENES in SPIE 2014. Building a fibre link for CARMENES

NASA Astrophysics Data System (ADS)

Stürmer, J.; Stahl, O.; Schwab, C.; Seifert, W.; Quirrenbach, A.; Amado, P. J.; Ribas, I.; Reiners, A.; Caballero, J. A.

2014-07-01

Optical fibres have successfully been used to couple high-resolution spectrographs to telescopes for many years. As they allow the instrument to be placed in a stable and isolated location, they decouple the spectrograph from environmental influences. Fibres also provide a substantial increase in stability of the input illumination of the spectrograph, which makes them a key optical element of the two high-resolution spectrographs of CARMENES. The optical properties of appropriate fibres are investigated, especially their scrambling and focal ratio degradation (FRD) behaviour. In the laboratory the output illumination of various fibres is characterized and different methods to increase the scrambling of the fibre link are tested and compared. In particular, a combination of fibres with different core shapes shows a very good scrambling performance. The near-field (NF) shows an extremely low sensitivity to the exact coupling conditions of the fibre. However, small changes in the far-field (FF) can still be seen. Related optical simulations of the stability performance of the two spectrographs are presented. The simulations focus on the influence of the non-perfect illumination stabilization in the far-field of the fibre on the radial velocity stability of the spectrographs. We use ZEMAX models of the spectrographs to simulate how the barycentres of the spots move depending on the FF illumination pattern and therefore how the radial velocity is affected by a variation of the spectrograph illumination. This method allows to establish a quantitative link between the results of the measurements of the optical properties of fibres on the one hand and the radial velocity precision on the other. The results provide a strong indication that 1ms?1 precision can be reached using a circular-octagonal fibre link even without the use of an optical double scrambler, which has successfully been used in other high-resolution spectrographs. Given the typical throughput of an optical double scrambler of about 75% to 85 %, our solution allows for a substantially higher throughput of the system.

Hollow-cathode lamps as optical frequency standards: the influence of optical imaging on the line-strength ratios

NASA Astrophysics Data System (ADS)

Huke, Philipp; Tal-Or, Lev; Sarmiento, Luis Fernando; Reiners, Ansgar

2016-07-01

Hollow cathode discharge lamps (HCLs) have been successfully used in recent years as calibration sources of optical astronomical spectrographs. The numerous narrow metal lines have stable wavelengths, which makes them well suited for m/s calibration accuracy of high-resolution spectrographs, while the buffer-gas lines are less stable and less useful. Accordingly, an important property is the metal-to-gas line-strength ratio (Rmetal/gas). Processes inside the lamp cause the light to be emitted from different regions between the cathode and the anode leaing to the emission of different beams with different values of Rmetal/gas. We used commercially- available HCLs to measure and characterize these beams with respect to their spatial distribution, their angle of propagation relative to the optical axis, and their values of Rmetal/gas. We conclude that a good imaging of an HCL into a fiber-fed spectrograph would consist of an aperture close to its front window in order to filter out the parts of the beam with low Rmetal/gas, and of a lens to collimate the important central beam. We show that Rmetal/gas can be further improved with only minor adjustments of the imaging parameters, and that the imaging scheme that yields the highest Rmetal/gas does not necessarily provide the highest flux.

VizieR Online Data Catalog: The ELM survey. VI. 11 new ELM WD binaries (Gianninas+, 2015)

NASA Astrophysics Data System (ADS)

Gianninas, A.; Kilic, M.; Brown, W. R.; Canton, P.; Kenyon, S. J.

2016-02-01

We used the 6.5m MMT telescope equipped with the Blue Channel spectrograph, the 200 inch Hale telescope equipped with the Double spectrograph, the Kitt Peak National Observatory 4m telescope equipped with the R-C spectrograph, and more recently with Kitt Peak Ohio State Multi-Object Spectrograph (KOSMOS), to obtain spectroscopy of our 11 targets in several observing runs. We have also been obtaining radial-velocity measurements for candidates from other sources including the Large Sky Area Multi-Object Spectroscopy Telescope (LAMOST). Those 11 new Extremely low-mass white dwarf (ELM WD) binaries bring the total of ELM WDs identified by the ELM Survey up to 73. (4 data files).

Effects of fiber manipulation methods on optical fiber properties

NASA Astrophysics Data System (ADS)

Reynolds, Robert O.; Bechter, Andrew; Crass, Jonathan

2016-07-01

Optical fibers are routinely used to couple high-resolution spectrographs to modern telescopes, enabling important advantages in areas such as the search for extrasolar planets using spectroscopic radial velocity measurements of candidate stars. Optical fibers partially scramble the input illumination, and this feature enables a fiber feed to provide more uniform illumination to the spectrograph optics, thereby reducing systematic errors in radial velocity measurements. However fibers suffer from focal ratio degradation (FRD), a spreading of the beam at the output of the fiber with respect to that at the fiber input, which results in losses in throughput and resolution. Modal noise, a measurement uncertainty caused by inherent fiber properties and evident as a varying spatial intensity at the fiber exit plane, reduces the signal to noise ratio in the data. Devices such as double scramblers are often used to improve scrambling, and better fiber end preparation can mitigate FRD. Many instruments agitate the fiber during an observation to reduce modal noise, and stretching the fiber during use has been shown to offer a greater reduction in that noise. But effects of agitation and stretching on fiber parameters such as total transmission and focal ratio degradation have not been adequately studied. In this paper we present measurements of transmission loss and focal ratio degradation for both agitated and stretched fibers.

Spectrographic Polarimeter and Method of Recording State of Polarity

NASA Technical Reports Server (NTRS)

Sparks, William B. (Inventor)

2015-01-01

A single-shot real-time spectropolarimeter for use in astronomy and other sciences that captures and encodes some or all of the Stokes polarization parameters simultaneously using only static, robust optical components with no moving parts is described. The polarization information is encoded onto the spectrograph at each wavelength along the spatial dimension of the 2D output data array. The varying embodiments of the concept include both a two-Stokes implementation (in which any two of the three Stokes polarization parameters are measured) and a full Stokes implementation (in which all three of the Stokes polarization parameters are measured), each of which is provided in either single beam or dual beam forms.

The extreme ultraviolet spectrograph: A radial groove grating, sounding rocket-borne, astronomical instrument

NASA Technical Reports Server (NTRS)

Wilkinson, Erik; Green, James C.; Cash, Webster

1993-01-01

The design, calibration, and sounding rocket flight performance of a novel spectrograph suitable for moderate-resolution EUV spectroscopy are presented. The sounding rocket-borne instrument uses a radial groove grating to maintain a high system efficiency while controlling the aberrations induced when doing spectroscopy in a converging beam. The instrument has a resolution of approximately 2 A across the 200-330 A bandpass with an average effective area of 2 sq cm. The instrument, called the Extreme Ultraviolet Spectrograph, acquired the first EUV spectra in this wavelength region of the hot white dwarf G191-B2B and the late-type star Capella.

AN EFFICIENT, COMPACT, AND VERSATILE FIBER DOUBLE SCRAMBLER FOR HIGH PRECISION RADIAL VELOCITY INSTRUMENTS

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

Halverson, Samuel; Roy, Arpita; Mahadevan, Suvrath

2015-06-10

We present the design and test results of a compact optical fiber double-scrambler for high-resolution Doppler radial velocity instruments. This device consists of a single optic: a high-index n ∼ 2 ball lens that exchanges the near and far fields between two fibers. When used in conjunction with octagonal fibers, this device yields very high scrambling gains (SGs) and greatly desensitizes the fiber output from any input illumination variations, thereby stabilizing the instrument profile of the spectrograph and improving the Doppler measurement precision. The system is also highly insensitive to input pupil variations, isolating the spectrograph from telescope illumination variationsmore » and seeing changes. By selecting the appropriate glass and lens diameter the highest efficiency is achieved when the fibers are practically in contact with the lens surface, greatly simplifying the alignment process when compared to classical double-scrambler systems. This prototype double-scrambler has demonstrated significant performance gains over previous systems, achieving SGs in excess of 10,000 with a throughput of ∼87% using uncoated Polymicro octagonal fibers. Adding a circular fiber to the fiber train further increases the SG to >20,000, limited by laboratory measurement error. While this fiber system is designed for the Habitable-zone Planet Finder spectrograph, it is more generally applicable to other instruments in the visible and near-infrared. Given the simplicity and low cost, this fiber scrambler could also easily be multiplexed for large multi-object instruments.« less

A flux calibration device for the SuperNova Integral Field Spectrograph (SNIFS)

NASA Astrophysics Data System (ADS)

Lombardo, Simona; Aldering, Greg; Hoffmann, Akos; Kowalski, Marek; Kuesters, Daniel; Reif, Klaus; Rigault, Michael

2014-07-01

Observational cosmology employing optical surveys often require precise flux calibration. In this context we present SNIFS Calibration Apparatus (SCALA), a flux calibration system developed for the SuperNova Integral Field Spectrograph (SNIFS), operating at the University of Hawaii 2.2 m telescope. SCALA consists of a hexagonal array of 18 small parabolic mirrors distributed over the face of, and feeding parallel light to, the telescope entrance pupil. The mirrors are illuminated by integrating spheres and a wavelength-tunable (from UV to IR) light source, generating light beams with opening angles of 1°. These nearly parallel beams are flat and flux-calibrated at a subpercent level, enabling us to calibrate our "telescope + SNIFS system" at the required precision.

The optical design of the G-CLEF Spectrograph: the first light instrument for the GMT

NASA Astrophysics Data System (ADS)

Ben-Ami, Sagi; Epps, Harland; Evans, Ian; Mueller, Mark; Podgorski, William; Szentgyorgyi, Andrew

2016-08-01

The GMT-Consortium Large Earth Finder (G-CLEF), the first major light instrument for the GMT, is a fiber-fed, high-resolution echelle spectrograph. In the following paper, we present the optical design of G-CLEF. We emphasize the unique solutions derived for the spectrograph fiber-feed: the Mangin mirror that corrects the cylindrical field curvature, the implementation of VPH grisms as cross dispersers, and our novel solution for a multi-colored exposure meter. We describe the spectrograph blue and red cameras comprised of 7 and 8 elements respectively, with one aspheric surface in each camera, and present the expected echellogram imaged on the instrument focal planes. Finally, we present ghost analysis and mitigation strategy that takes into account both single reflection and double reflection back scattering from various elements in the optical train.

Compact high-resolution spectrographs for large and extremely large telescopes: using the diffraction limit

NASA Astrophysics Data System (ADS)

Robertson, J. Gordon; Bland-Hawthorn, Joss

2012-09-01

As telescopes get larger, the size of a seeing-limited spectrograph for a given resolving power becomes larger also, and for ELTs the size will be so great that high resolution instruments of simple design will be infeasible. Solutions include adaptive optics (but not providing full correction for short wavelengths) or image slicers (which give feasible but still large instruments). Here we develop the solution proposed by Bland-Hawthorn and Horton: the use of diffraction-limited spectrographs which are compact even for high resolving power. Their use is made possible by the photonic lantern, which splits a multi-mode optical fiber into a number of single-mode fibers. We describe preliminary designs for such spectrographs, at a resolving power of R ~ 50,000. While they are small and use relatively simple optics, the challenges are to accommodate the longest possible fiber slit (hence maximum number of single-mode fibers in one spectrograph) and to accept the beam from each fiber at a focal ratio considerably faster than for most spectrograph collimators, while maintaining diffraction-limited imaging quality. It is possible to obtain excellent performance despite these challenges. We also briefly consider the number of such spectrographs required, which can be reduced by full or partial adaptive optics correction, and/or moving towards longer wavelengths.

Conditional-sampling spectrograph detection system for fluorescence measurements of individual airborne biological particles

NASA Astrophysics Data System (ADS)

Nachman, Paul; Pinnick, R. G.; Hill, Steven C.; Chen, Gang; Chang, Richard K.; Mayo, Michael W.; Fernandez, Gilbert L.

1996-03-01

We report the design and operation of a prototype conditional-sampling spectrograph detection system that can record the fluorescence spectra of individual, micrometer-sized aerosols as they traverse an intense 488-nm intracavity laser beam. The instrument's image-intensified CCD detector is gated by elastic scattering or by undispersed fluorescence from particles that enter the spectrograph's field of view. It records spectra only from particles with preselected scattering-fluorescence levels (a fiber-optic-photomultiplier subsystem provides the gating signal). This conditional-sampling procedure reduces data-handling rates and increases the signal-to-noise ratio by restricting the system's exposures to brief periods when aerosols traverse the beam. We demonstrate these advantages by reliably capturing spectra from individual fluorescent microspheres dispersed in an airstream. The conditional-sampling procedure also permits some discrimination among different types of particles, so that spectra may be recorded from the few interesting particles present in a cloud of background aerosol. We demonstrate such discrimination by measuring spectra from selected fluorescent microspheres in a mixture of two types of microspheres, and from bacterial spores in a mixture of spores and nonfluorescent kaolin particles.

Design, development, and performance of the fibres of MOONS

NASA Astrophysics Data System (ADS)

Guinouard, Isabelle; Avila, Gerardo; Lee, David; Amans, Jean-Philippe; Rees, Phil; Taylor, William; Oliva, Ernesto

2016-07-01

The Multi-Object Optical and Near-infrared Spectrograph (MOONS) will exploit the full 500 square arcmin field of view offered by the Nasmyth focus of the Very Large Telescope and will be equipped with two identical triple arm cryogenic spectrographs covering the wavelength range 0.64μm-1.8μm, with a multiplex capability of over 1000 fibres. Each spectrograph will produce spectra for 500 targets simultaneously, each with its own dedicated sky fibre for optimal sky subtraction. The system will have both a medium resolution (R 4000-6000) mode and a high resolution (R 20000) mode. The fibres are used to pick off each sub field of 1" and are used to transport the light from the instrument focal plane to the two spectrographs. Each fibre has a microlens to focus the beam into the fibre at a relative fast focal ratio of F/3.65 to reduce the Focal Ratio Degradation (FRD).

NOAO's next-generation optical spectrograph

NASA Astrophysics Data System (ADS)

Barden, Samuel C.; Harmer, Charles F.; Blakley, Rick D.; Parks, Rachel J.

2000-08-01

The National Optical Astronomy Observatory is developing a new, wide-field, imaging spectrograph for use on its existing 4-meter telescopes. This Next Generation Optical Spectrograph (NGOS) will utilize volume-phase holographic grating technology and will have a mosaiced detector array to image the spectra over a field of view that will be something like 10.5 by 42 arc-minutes on the sky. The overall efficiency of the spectrograph should be quite high allowing it to outperform the current RC spectrograph by factors of 10 to 20 and the Hydra multi-fiber instrument by a facto of fiber to ten per object. The operational range of the instrument will allow observations within the optical and near-IR regions. Spectral resolutions will go from R equals 1000 to at least R equals 5000 with 1.4 arc-second slits. The large size of this instrument, with a beam diameter of 200 mm and an overall length of nearly 3 meters, presents a significant challenge in mounting it at the Cassegrain location of the telescope. Design trades and options that allow it to fit are discussed.

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

Thomson scattering diagnostic on the Compact Toroidal Hybrid Experiment

NASA Astrophysics Data System (ADS)

Traverso, Peter; Maurer, D. A.; Ennis, D. A.; Hartwell, G. J.

2016-10-01

A Thomson scattering system is being commissioned for the non-axisymmetric plasmas of the Compact Toroidal Hybrid (CTH), a five-field period current-carrying torsatron. The system takes a single point measurement at the magnetic axis to both calibrate the two- color soft x-ray Te system and serve as an additional diagnostic for the V3FIT 3D equilibrium reconstruction code. A single point measurement will reduce the uncertainty in the reconstructed peak pressure by an order of magnitude for both current-carrying plasmas and future gyrotron-heated stellarator plasmas. The beam, generated by a frequency doubled Continuum 2 J, Nd:YaG laser, is passed vertically through an entrance Brewster window and a two-aperture optical baffle system to minimize stray light. The beam line propagates 8 m to the CTH device mid-plane with the beam diameter < 3 mm inside the plasma volume. Thomson scattered light is collected by two adjacent f/2 plano-convex condenser lenses and focused onto a custom fiber bundle. The fiber is then re-bundled and routed to a Holospec f/1.8 spectrograph to collect the red-shifted scattered light from 535-565 nm. The system has been designed to measure plasmas with core Te of 100 to 200 eV and densities of 5 ×1018 to 5 ×1019 m-3. Work supported by USDOE Grant DE-FG02-00ER54610.

Reliability Modeling of Double Beam Bridge Crane

NASA Astrophysics Data System (ADS)

Han, Zhu; Tong, Yifei; Luan, Jiahui; Xiangdong, Li

2018-05-01

This paper briefly described the structure of double beam bridge crane and the basic parameters of double beam bridge crane are defined. According to the structure and system division of double beam bridge crane, the reliability architecture of double beam bridge crane system is proposed, and the reliability mathematical model is constructed.

The new classic data acquisition system for NPOI

NASA Astrophysics Data System (ADS)

Sun, B.; Jorgensen, A. M.; Landavazo, M.; Hutter, D. J.; van Belle, G. T.; Mozurkewich, David; Armstrong, J. T.; Schmitt, H. R.; Baines, E. K.; Restaino, S. R.

2014-07-01

The New Classic data acquisition system is an important portion of a new project of stellar surface imaging with the NPOI, funded by the National Science Foundation, and enables the data acquisition necessary for the project. The NPOI can simultaneously deliver beams from 6 telescopes to the beam combining facility, and in the Classic beam combiner these are combined 4 at a time on 3 separate spectrographs with all 15 possible baselines observed. The Classic data acquisition system is limited to 16 of 32 wavelength channels on two spectrographs and limited to 30 s integrations followed by a pause to ush data. Classic also has some limitations in its fringe-tracking capability. These factors, and the fact that Classic incorporates 1990s technology which cannot be easily replaced are motivation for upgrading the data acquisition system. The New Classic data acquisition system is based around modern electronics, including a high-end Stratix FPGA, a 200 MB/s Direct Memory Access card, and a fast modern Linux computer. These allow for continuous recording of all 96 channels across three spectrographs, increasing the total amount of data recorded by a an estimated order of magnitude. The additional computing power on the data acquisition system also allows for the implementation of more sophisticated fringe-tracking algorithms which are needed for the Stellar Surface Imaging project. In this paper we describe the New Classic system design and implementation, describe the background and motivation for the system as well as show some initial results from using it.

Toroidal varied-line space (TVLS) gratings

NASA Astrophysics Data System (ADS)

Thomas, Roger J.

2003-02-01

It is a particular challenge to develop a stigmatic spectrograph for EUV wavelengths since the very low normal-incidence reflectance of standard materials most often requires that the design be restricted to a single optical element which must simultaneously provide both re-imaging and spectral dispersion. This problem has been solved in the past by the use of toroidal gratings with uniform line-space rulings (TULS). A number of solar EUV spectrographs have been based on such designs, including SOHO/CDS, Solar-B/EIS, and the sounding rockets SERTS and EUNIS. More recently, Kita, Harada, and collaborators have developed the theory of spherical gratings with varied line-space rulings (SVLS) operated at unity magnification, which have been flown on several astronomical satellite missions. These ideas are now combined into a spectrograph concept that considers varied-line space grooves ruled onto toroidal gratings. Such TVLS designs are found to provide excellent imaging even at very large spectrograph magnifications and beam-speeds, permitting extremely high-quality performance in remarkably compact instrument packages. Optical characteristics of two solar spectrographs based on this concept are described: SUMI, proposed as a sounding rocket experiment, and NEXUS, proposed for the Solar Dynamics Observatory mission.

Performance, results, and prospects of the visible spectrograph VEGA on CHARA

NASA Astrophysics Data System (ADS)

Mourard, Denis; Challouf, Mounir; Ligi, Roxanne; Bério, Philippe; Clausse, Jean-Michel; Gerakis, Jérôme; Bourges, Laurent; Nardetto, Nicolas; Perraut, Karine; Tallon-Bosc, Isabelle; McAlister, H.; ten Brummelaar, T.; Ridgway, S.; Sturmann, J.; Sturmann, L.; Turner, N.; Farrington, C.; Goldfinger, P. J.

2012-07-01

In this paper, we review the current performance of the VEGA/CHARA visible spectrograph and make a review of the most recent astrophysical results. The science programs take benefit of the exceptional angular resolution, the unique spectral resolution and one of the main features of CHARA: Infrared and Visible parallel operation. We also discuss recent developments concerning the tools for the preparation of observations and important features of the data reduction software. A short discussion of the future developments will complete the presentation, directed towards new detectors and possible new beam combination scheme for improved sensitivity and imaging capabilities.

The SALT HRS Spectrograph

NASA Astrophysics Data System (ADS)

Tyas, Luke Martin Graham

2012-05-01

SALT HRS (Southern African Large Telescope High Resolution Échelle Spectrograph) is a high-resolution, high-efficiency spectrograph for the 11m SALT telescope in Sutherland, South Africa. The initial optical design work was performed at the University of Canterbury, New Zealand. Revisions to the concept, the mechanical design, manufacture, assembly and testing have been handled by the Centre for Advanced Instrumentation, at Durham University in the United Kingdom. SALT HRS is a fibre-fed échelle grating spectrograph with four operational modes: low-, medium- and high-resolution and high-stability modes, having spectral resolutions of R≈16000, 37000, 67000 and 67000 respectively over a wavelength range of 370-890nm. The instrument is of a dual channel, 'white pupil' design, in which the primary mirror acts to collimate light onto a single R4 échelle grating, and also to focus dispersed light to an intermediate focus. A dichroic beam-splitter separates the dispersed light into two separate spectral channels. Spherical pupil mirrors transfer the separated beams via a fold mirror to two wavelength-specific volume-phase holographic gratings (VPHGs) used as cross-dispersers. Cross-dispersed spectra are then imaged by two fully dioptric camera systems onto optimized CCD detectors. This thesis presents the results of the laboratory testing and specification of several critical sub-systems of SALT HRS, as well as the development of key software tools for the design verification and operation at the telescope. In Chapter 1 we first review the technical development of high-resolution spectroscopy and its specific implementation in SALT HRS. In Chapter 2 we develop a comprehensive throughput model of the entire system based on a combination of as-built performance and specific throughput measurements in the laboratory. This is used to make some specific predictions for the on-sky performance of SALT HRS and the magnitude limits for science targets. We also present a graphical exposure time calculator based on these measurements which can be used by an astronomer to plan their observations with SALT HRS. Chapter 3 contains a detailed treatise on the optical fibre system of SALT HRS. Considerations for the use of optical fibres in astronomy are provided, as are details of an optional double scrambler, and the various instrument fibre modes. Extensive measurements of focal ratio degradation (FRD) are also presented, with testing of input beam speed; wavelength; fibre bending; variable pupil mirror illumination; and vacuum tank pressure dependency. The systems for fibre management are reviewed, as is the fibre bundle assembly process. Testing of two further sub-systems is described in Chapter 4. Firstly the long-term stability of the mirror mounting mechanisms is determined. The advantages of cross-dispersion of échelle spectra using volume-phase holographic gratings are then discussed, and the results of diffraction efficiency measurements are given for both red and blue channel gratings. Modern CCD technologies are examined in Chapter 5, and the blue detector is experimentally characterized using photon transfer and quantum efficiency curves. It is also used for an investigation into cosmic ray events in CCDs. Results from shielding the detector using lead are described, as is an attempt to distinguish the source of the events based on their morphology. Finally, Chapter 6 deals with the handling of data produced by SALT HRS. Methods of wavelength calibration of the spectra are discussed, including the use of Thorium-Argon lamps and an iodine absorption cell. The implementation of a Python based quick-look data reduction pipeline is reviewed, with a description of the processes performed. A summary of the thesis is given in Chapter 7.

SPRAT: Spectrograph for the Rapid Acquisition of Transients

NASA Astrophysics Data System (ADS)

Piascik, A. S.; Steele, Iain A.; Bates, Stuart D.; Mottram, Christopher J.; Smith, R. J.; Barnsley, R. M.; Bolton, B.

2014-07-01

We describe the development of a low cost, low resolution (R ~ 350), high throughput, long slit spectrograph covering visible (4000-8000) wavelengths. The spectrograph has been developed for fully robotic operation with the Liverpool Telescope (La Palma). The primary aim is to provide rapid spectral classification of faint (V ˜ 20) transient objects detected by projects such as Gaia, iPTF (intermediate Palomar Transient Factory), LOFAR, and a variety of high energy satellites. The design employs a volume phase holographic (VPH) transmission grating as the dispersive element combined with a prism pair (grism) in a linear optical path. One of two peak spectral sensitivities are selectable by rotating the grism. The VPH and prism combination and entrance slit are deployable, and when removed from the beam allow the collimator/camera pair to re-image the target field onto the detector. This mode of operation provides automatic acquisition of the target onto the slit prior to spectrographic observation through World Coordinate System fitting. The selection and characterisation of optical components to maximise photon throughput is described together with performance predictions.

Multi-object medium resolution optical spectroscopy at the E-ELT

NASA Astrophysics Data System (ADS)

Spanò, Paolo; Bonifacio, Piercarlo

2008-07-01

We present the design of a compact medium resolution spectrograph (R~15,000-20,000), intended to operate on a 42m telescope in seeing-limited mode. Our design takes full advantage of some new technology optical components, like volume phase holographic (VPH) gratings. At variance with the choice of complex large echelle spectrographs, which have been the standard on 8m class telescopes, we selected an efficient VPH spectrograph with a limited beam diameter, in order to keep overall dimensions and costs low, using proven available technologies. To obtain such a resolution, we need to moderately slice the telescope image plane onto the spectrograph entrance slit (5-6 slices). Then, standard telescope AO-mode (GLAO, Ground Layer Adaptive Optics) can be used over a large field of view (~10 arcmin), without loosing efficiency. Multiplex capabilities can greatly increase the observing efficiency. A robotic pick-up mirror system can be implemented, within conventional environmental conditions (temperature, pressure, gravity, size), demanding only standard mechanical and optical tolerances. A modular approach allows us scaling multiplex capabilities on overall costs and available space.

[Design of Dual-Beam Spectrometer in Spectrophotometer for Colorimetry].

PubMed

Liu, Yi-xuan; Yan, Chang-xiang

2015-07-01

Spectrophotometers for colorimetry are usually composed of two independent and identical spectrometers. In order to reduce the volume of spectrophotometer for colorimetry, a design method of double-beam spectrometer is put forward. A traditional spectrometer is modified so that a new spectrometer can realize the function of double spectrometers, which is especially suitable for portable instruments. One slit is replaced by the double-slit, than two beams of spectrum can be detected. The working principle and design requirement of double-beam spectrometer are described. A spectrometer of portable spectrophotometer is designed by this method. A toroidal imaging mirror is used for the Czerny-Turner double-beam spectrometer in this paper, which can better correct astigmatism, and prevent the dual-beam spectral crosstalk. The results demonstrate that the double-beam spectrometer designed by this method meets the design specifications, with the spectral resolution less than 10 nm, the spectral length of 9.12 mm, and the volume of 57 mm x 54 mm x 23 mm, and without the dual-beam spectral overlap in the detector either. Comparing with a traditional spectrophotometer, the modified spectrophotometer uses a set of double-beam spectrometer instead of two sets of spectrometers, which can greatly reduce the volume. This design method can be specially applied in portable spectrophotometers, also can be widely applied in other double-beam spectrophotometers, which offers a new idea for the design of dual-beam spectrophotometers.

Population inversions in ablation plasmas generated by intense electron beams. Final report, 1 November 1985-31 October 1988

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

Gilgenbach, R.M.; Kammash, T.; Brake, M.L.

1988-11-01

Experiments during the past three years have concerned the generation and spectroscopic study of electron beam-driven carbon plasmas in order to explore the production of optical and ultraviolet radiation from nonequilibrium populations. The output of MELBA (Michigan Electron Long Beam Accelerator), has been connected to an electron-beam diode consisting of an aluminum (or brass) cathode stalk and a carbon anode. Magnetic-field coils were designed, procured, and utilized to focus the electron beam. A side viewing port permitted spectroscopic diagnostics to view across the surface of the anode. Spectroscopic diagnosis was performed using a 1-m spectrograph capable of operation from themore » vacuum-ultraviolet through the visible. This spectrograph is coupled to a 1024-channel optical multichannel analyzer. Spectra taken during the initial 400-ns period of the e-beam pulse showed a low effective-charge plasma with primarily molecular components (C/sub 2/, CH) as well as atomic hydrogen and singly ionized carbon (CII). When the generator pulse was crowbarred after the first 400 ns, the spectra revealed a continuation of the low-charge-state plasma. At times greater than 400 ns in non-crowbarred shots, the spectra revealed a highly ionized plasma with a very large intensity line at 2530 Angstroms due to CIV (5g-4f), and lower-intensity lines due to CIII and CII. This CIV line emission increased with time, peaking sharply between 750 and 900 ns, and decayed rapidly in less than 100 ns. Emission from these high ionization states may be due to electron beam-plasma instabilities, as this emission was accompanied by high levels of radio frequency and microwave emission.« less

APOGEE fiber development and FRD testing

NASA Astrophysics Data System (ADS)

Brunner, Sophia; Burton, Adam; Crane, Jeff; Zhao, Bo; Hearty, Fred R.; Wilson, John C.; Carey, Larry; Leger, French; Skrutskie, Mike; Schiavon, Ricardo; Majewski, Steven R.

2010-07-01

Development of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) near-infrared spectrograph has motivated thorough investigation into the properties and performance of optical fibers. The fiber selected for APOGEE is a step index, multi-mode fiber, developed by PolyMicro, with a 120μm low OH, fused silica core, 25μm cladding, and 10μm buffer. The instrument design includes a 40 meter fiber run, connecting the spectrograph to the 2.5m Sloan Digital Sky Survey (SDSS) telescope, and an additional 2.5 meter fiber segment located within the instrument dewar, a vacuum-sealed, cryogenic environment. This light path is convoluted and includes many transitions and connections where the beam is susceptible irrevocable loss. To optimize the spectrograph performance it is necessary to minimize the losses incurred in the fiber system, especially those resulting in focal ratio degradation (FRD). The focus of this research has been to identify potential sources of loss and where applicable, select material components to minimize this effect. There is little previous documented work concerning the performance of optical fibers within this wavelength band (1.5-1.7μm). Consequently, the following includes comprehensive explanations of the APOGEE fiber system components, our experimental design and optical test bed set-up, beam alignment procedures, fiber terminating and polishing techniques, and results from our examination of FRD as correlated with source wavelength, fiber length and termination, and environmental conditions.

Spectroscopic Classifications of PSN J20372558+6607115 with Lick 3-m Reflector

NASA Astrophysics Data System (ADS)

Foley, R. J.; Zheng, W.; Filippenko, A. V.; van Dyk, S. D.

2015-03-01

We report the classifications of PSN J20372558+6607115 (discovered by K. Shima and announced on the CBAT TOCP) from a spectrum obtained with the Kast dual-beam spectrograph on the Lick 3-m Shane telescope on 2015 March 26 UT.

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

Bailey, J.E.; Adams, R.; Carlson, A.L.

Stark-shift measurements using emission spectroscopy are a powerful tool for advancing understanding in many plasma physics experiments. The authors use simultaneous 2-D-spatial and time-resolved spectra to study the electric field evolution in the 20 TW Particle Beam Fusion Accelerator II ion diode acceleration gap. Fiber optic arrays transport light from the gap to remote streaked spectrographs operated in a multiplexed mode that enables recording time-resolved spectra from eight spatial locations on a single instrument. Design optimization and characterization measurements of the multiplexed spectrograph properties include the astigmatism, resolution, dispersion variation, and sensitivity. A semi-automated line-fitting procedure determines the Stark shiftmore » and the related uncertainties. Fields up to 10 MV/cm are measured with an accuracy {+-}2--4%. Detailed tests of the fitting procedure confirm that the wavelength shift uncertainties are accurate to better than {+-}20%. Development of an active spectroscopy probe technique that uses laser-induced fluorescence from an injected atomic beam to obtain 3-D space- and time-resolved measurements of the electric and magnetic fields is in progress.« less

S4EI (Spectral Sampling with Slicer for Stellar and Extragalactical Instrumentation), a new-generation of 3D spectro-imager dedicated to night astronomy

NASA Astrophysics Data System (ADS)

Sayède, Frédéric; Puech, Mathieu; Mein, Pierre; Bonifacio, Piercarlo; Malherbe, Jean-Marie; Galicher, Raphaël.; Amans, Jean-Philippe; Fasola, Gilles

2014-07-01

Multichannel Subtractive Double Pass (MSDP) spectrographs have been widely used in solar spectroscopy because of their ability to provide an excellent compromise between field of view and spatial and spectral resolutions. Compared with other types of spectrographs, MSDP can deliver simultaneous monochromatic images at higher spatial and spectral resolutions without any time-scanning requirement (as with Fabry-Perot spectrographs), and with limited loss of flux. These performances are obtained thanks to a double pass through the dispersive element. Recent advances with VPH (Volume phase holographic) Grisms as well as with image slicers now make MSDP potentially sensitive to much smaller fluxes. We present S4EI (Spectral Sampling with Slicer for Stellar and Extragalactical Instrumentation), which is a new concept for extending MSDP to night-time astronomy. It is based on new generation reflecting plane image slicers working with large apertures specific to night-time telescopes. The resulting design could be potentially very attractive and innovative for different domains of astronomy, e.g., the simultaneous spatial mapping of accurately flux-calibrated emission lines between OH sky lines in extragalactic astronomy or the simultaneous imaging of stars, exoplanets and interstellar medium. We present different possible MSDP/S4EI configurations for these science cases and expected performances on telescopes such as the VLT.

VizieR Online Data Catalog: Lick AGN monitoring 2011: light curves (Barth+, 2015)

NASA Astrophysics Data System (ADS)

Barth, A. J.; Bennert, V. N.; Canalizo, G.; Filippenko, A. V.; Gates, E. L.; Greene, J. E.; Li, W.; Malkan, M. A.; Pancoast, A.; Sand, D. J.; Stern, D.; Treu, T.; Woo, J.-H.; Assef, R. J.; Bae, H.-J.; Brewer, B. J.; Cenko, S. B.; Clubb, K. I.; Cooper, M. C.; Diamond-Stanic, A. M.; Hiner, K. D.; Honig, S. F.; Hsiao, E.; Kandrashoff, M. T.; Lazarova, M. S.; Nierenberg, A. M.; Rex, J.; Silverman, J. M.; Tollerud, E. J.; Walsh, J. L.

2015-05-01

This project was allocated 69 nights at the Lick 3m Shane telescope, distributed between 2011 March 27 and June 13. Observations were conducted using the Kast double spectrograph (3440-5515Å on the blue side and 5410-8200Å on the red side). In order to extend our light curves for two AGNs, we also requested additional observations from other observers using the Kast spectrograph: Mrk 50 from 2011 January through March, and Zw 229-015 in June and July. For Zw 229-015, three additional observations were taken 20-23 days after the end of our main campaign. See section 3. (2 data files).

Design and early performance of IGRINS (Immersion Grating Infrared Spectrometer)

NASA Astrophysics Data System (ADS)

Park, Chan; Jaffe, Daniel T.; Yuk, In-Soo; Chun, Moo-Young; Pak, Soojong; Kim, Kang-Min; Pavel, Michael; Lee, Hanshin; Oh, Heeyoung; Jeong, Ueejeong; Sim, Chae Kyung; Lee, Hye-In; Nguyen Le, Huynh Anh; Strubhar, Joseph; Gully-Santiago, Michael; Oh, Jae Sok; Cha, Sang-Mok; Moon, Bongkon; Park, Kwijong; Brooks, Cynthia; Ko, Kyeongyeon; Han, Jeong-Yeol; Nah, Jakyoung; Hill, Peter C.; Lee, Sungho; Barnes, Stuart; Yu, Young Sam; Kaplan, Kyle; Mace, Gregory; Kim, Hwihyun; Lee, Jae-Joon; Hwang, Narae; Park, Byeong-Gon

2014-07-01

The Immersion Grating Infrared Spectrometer (IGRINS) is a compact high-resolution near-infrared cross-dispersed spectrograph whose primary disperser is a silicon immersion grating. IGRINS covers the entire portion of the wavelength range between 1.45 and 2.45μm that is accessible from the ground and does so in a single exposure with a resolving power of 40,000. Individual volume phase holographic (VPH) gratings serve as cross-dispersing elements for separate spectrograph arms covering the H and K bands. On the 2.7m Harlan J. Smith telescope at the McDonald Observatory, the slit size is 1ʺ x 15ʺ and the plate scale is 0.27ʺ pixel. The spectrograph employs two 2048 x 2048 pixel Teledyne Scientific and Imaging HAWAII-2RG detectors with SIDECAR ASIC cryogenic controllers. The instrument includes four subsystems; a calibration unit, an input relay optics module, a slit-viewing camera, and nearly identical H and K spectrograph modules. The use of a silicon immersion grating and a compact white pupil design allows the spectrograph collimated beam size to be only 25mm, which permits a moderately sized (0.96m x 0.6m x 0.38m) rectangular cryostat to contain the entire spectrograph. The fabrication and assembly of the optical and mechanical components were completed in 2013. We describe the major design characteristics of the instrument including the system requirements and the technical strategy to meet them. We also present early performance test results obtained from the commissioning runs at the McDonald Observatory.

Vacuum Spectrograph for E-Beam Ablation Studies.

DTIC Science & Technology

1987-07-31

Washington, D. C. 20332 I. ISAIAS OP ISUNCISNGMPONSORING IN. OFFICE svm*OL 9. PROCUREMENT INSTRVMG14T IDENTIFICATION NdUMBERi ORGA1CNIZATION Ia ~b *Air...Unannounced [J Justification ’pig ~Distribution/______ AvAilability Codes Avnil andr/or Di pC a Figure 1. Photograph of the VM-510 and pumping station

Multistable wireless micro-actuator based on antagonistic pre-shaped double beams

NASA Astrophysics Data System (ADS)

Liu, X.; Lamarque, F.; Doré, E.; Pouille, P.

2015-07-01

This paper presents a monolithic multistable micro-actuator based on antagonistic pre-shaped double beams. The designed micro-actuator is formed by two rows of bistable micro-actuators providing four stable positions. The bistable mechanism for each row is a pair of antagonistic pre-shaped beams. This bistable mechanism has an easier pre-load operation compared to the pre-compressed bistable beams method. Furthermore, it solves the asymmetrical force output problem of parallel pre-shaped bistable double beams. At the same time, the geometrical limit is lower than parallel pre-shaped bistable double beams, which ensures a smaller stroke of the micro-actuator with the same dimensions. The designed micro-actuator is fabricated using laser cutting machine on medium density fiberboard (MDF). The bistability and merits of antagonistic pre-shaped double beams are experimentally validated. Finally, a contactless actuation test is performed using 660 nm wavelength laser heating shape memory alloy (SMA) active elements.

Curved diamond-crystal spectrographs for x-ray free-electron laser noninvasive diagnostics.

PubMed

Terentyev, Sergey; Blank, Vladimir; Kolodziej, Tomasz; Shvyd'ko, Yuri

2016-12-01

We report on the manufacturing and X-ray tests of bent diamond-crystal X-ray spectrographs, designed for noninvasive diagnostics of the X-ray free-electron laser (XFEL) spectra in the spectral range from 5 to 15 keV. The key component is a curved, 20-μm thin, single crystalline diamond triangular plate in the (110) orientation. The radius of curvature can be varied between R = 0.6 m and R = 0.1 m in a controlled fashion, ensuring imaging in a spectral window of up to 60 eV for ≃8 keV X-rays. All of the components of the bending mechanism (about 10 parts) are manufactured from diamond, thus ensuring safe operations in intense XFEL beams. The spectrograph is transparent to 88% for 5-keV photons and to 98% for 15-keV photons. Therefore, it can be used for noninvasive diagnostics of the X-ray spectra during XFEL operations.

Curved diamond-crystal spectrographs for x-ray free-electron laser noninvasive diagnostics

DOE PAGES

Terentyev, Sergey; Blank, Vladimir; Kolodziej, Tomasz; ...

2016-12-29

Here, we report on the manufacturing and X-ray tests of bent diamond-crystal X-ray spectrographs, designed for noninvasive diagnostics of the X-ray free-electron laser (XFEL) spectra in the spectral range from 5 to 15 keV. The key component is a curved, 20-µm thin, single crystalline diamond triangular plate in the (110) orientation. The radius of curvature can be varied between R = 0.6 m and R = 0.1 m in a controlled fashion, ensuring imaging in a spectral window of up to 60 eV for ' 8 keV X-rays. All of the components of the bending mechanism (about 10 parts) aremore » manufactured from diamond, thus ensuring safe operations in intense XFEL beams. The spectrograph is transparent to 88% for 5-keV photons, and to 98% for 15-keV photons. Therefore, it can be used for noninvasive diagnostics of the X-ray spectra during XFEL operations.« less

Curved diamond-crystal spectrographs for x-ray free-electron laser noninvasive diagnostics

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

Terentyev, Sergey; Blank, Vladimir; Kolodziej, Tomasz

Here, we report on the manufacturing and X-ray tests of bent diamond-crystal X-ray spectrographs, designed for noninvasive diagnostics of the X-ray free-electron laser (XFEL) spectra in the spectral range from 5 to 15 keV. The key component is a curved, 20-µm thin, single crystalline diamond triangular plate in the (110) orientation. The radius of curvature can be varied between R = 0.6 m and R = 0.1 m in a controlled fashion, ensuring imaging in a spectral window of up to 60 eV for ' 8 keV X-rays. All of the components of the bending mechanism (about 10 parts) aremore » manufactured from diamond, thus ensuring safe operations in intense XFEL beams. The spectrograph is transparent to 88% for 5-keV photons, and to 98% for 15-keV photons. Therefore, it can be used for noninvasive diagnostics of the X-ray spectra during XFEL operations.« less

MEGARA: large pupil element tests and performance

NASA Astrophysics Data System (ADS)

Martínez-Delgado, I.; Sánchez-Blanco, E.; Pérez-Calpena, A.; García-Vargas, M. L.; Maldonado, X. M.; Gil de Paz, A.; Carrasco, E.; Gallego, J.; Iglesias-Páramo, J.; Sánchez-Moreno, F. M.

2016-07-01

MEGARA is a third generation spectrograph for the Spanish 10.4m telescope (GTC) providing two observing modes: a large central Integral Field Unit (IFU), called the Large Compact Bundle (LCB), covering a FOV of 12.5 × 11.3 arcsec2, and a Multi-Object Spectrograph (MOS) with a FOV of 3.5 × 3.5 arcmin2. MEGARA will observe the whole visible range from 3650A to 10000A allowing different spectral resolutions (low, medium and high) with R = 6000, 11000 and 18000 respectively. The dispersive elements are placed at the spectrograph pupil position in the path of the collimated beam and they are composed of a set of volume phase hologram gratings (VPHs) sandwiched between two flat windows and coupled in addition to two prisms in the case of the medium- and high-resolution units. We will describe the tests and setups developed to check the requirements of all units, as well as the obtained performance at laboratory

Method for determination of small amounts of rare earths and thorium in phosphate rocks

USGS Publications Warehouse

Waring, C.L.; Mela, H.

1953-01-01

In laboratory investigations, interest developed in the possible rare-earth content of phosphate samples from Florida and the northwestern United States. Because of the difficulty of making chemical determinations of traces of individual rare earths, a combined chemical-spectrographic method was investigated. After removal of iron by the extraction of the chloride with ether, the rare earths and thorium are concentrated by double oxalate precipitation, using calcium as a carrier. The rare earths are freed from calcium by an ammonium hydroxide precipitation with a fixed amount of aluminum as a carrier. The aluminum also serves as an internal standard in the final spectrographic analysis. The method will determine from 0.02 to 2 mg. of each rare earth with an error no greater than 10%. The investigation has resulted in a fairly rapid and precise procedure, involving no special spectrographic setup. The method could be applied to other types of geologic materials with the same expected accuracy.

VizieR Online Data Catalog: Palomar Transient Factory SNe IIn photometry (Ofek+, 2014)

NASA Astrophysics Data System (ADS)

Ofek, E. O.; Arcavi, I.; Tal, D.; Sullivan, M.; Gal-Yam, A.; Kulkarni, S. R.; Nugent, P. E.; Ben-Ami, S.; Bersier, D.; Cao, Y.; Cenko, S. B.; De Cia, A.; Filippenko, A. V.; Fransson, C.; Kasliwal, M. M.; Laher, R.; Surace, J.; Quimby, R.; Yaron, O.

2017-07-01

The Palomar Transient Factory (PTF; Law et al. 2009PASP..121.1395L; Rau et al. 2009PASP..121.1334R) and its extension the intermediate PTF (iPTF) found over 2200 spectroscopically confirmed SNe. We selected 19 SNe IIn for which PTF/iPTF has good coverage of the light-curve rise and peak; they are listed in Table 1. Optical spectra were obtained with a variety of telescopes and instruments, including the Double Spectrograph (Oke & Gunn 1982PASP...94..586O) at the Palomar 5 m Hale telescope, the Kast spectrograph (Miller & Stone 1993, Lick Observatory Technical Report 66 (Santa Cruz, CA: Lick Observatory)) at the Lick 3 m Shane telescope, the Low Resolution Imaging Spectrometer (Oke et al. 1995PASP..107..375O) on the Keck-1 10 m telescope, and the Deep Extragalactic Imaging Multi-Object Spectrograph (Faber et al. 2003SPIE.4841.1657F) on the Keck-2 10 m telescope. (2 data files).

Over-under double-pass interferometer

NASA Technical Reports Server (NTRS)

Schindler, Rudolf A. (Inventor)

1980-01-01

An over-under double-pass interferometer in which the beamsplitter area and thickness can be reduced to conform only with optical flatness considerations is achieved by offsetting the optical center line of one cat's-eye retroreflector relative to the optical center line of the other in order that one split beam be folded into a plane distinct from the other folded split beam. The beamsplitter is made transparent in one area for a first folded beam to be passed to a mirror for doubling back and is made totally reflective in another area for the second folded beam to be reflected to a mirror for doubling back. The two beams thus doubled back are combined in the central, beam-splitting area of the beamsplitter and passed to a detector. This makes the beamsplitter insensitive to minimum-thickness requirements and selection of material.

DARKNESS: A Microwave Kinetic Inductance Detector Integral Field Spectrograph for High-contrast Astronomy

NASA Astrophysics Data System (ADS)

Meeker, Seth R.; Mazin, Benjamin A.; Walter, Alex B.; Strader, Paschal; Fruitwala, Neelay; Bockstiegel, Clint; Szypryt, Paul; Ulbricht, Gerhard; Coiffard, Grégoire; Bumble, Bruce; Cancelo, Gustavo; Zmuda, Ted; Treptow, Ken; Wilcer, Neal; Collura, Giulia; Dodkins, Rupert; Lipartito, Isabel; Zobrist, Nicholas; Bottom, Michael; Shelton, J. Chris; Mawet, Dimitri; van Eyken, Julian C.; Vasisht, Gautam; Serabyn, Eugene

2018-06-01

We present DARKNESS (the DARK-speckle Near-infrared Energy-resolving Superconducting Spectrophotometer), the first of several planned integral field spectrographs to use optical/near-infrared Microwave Kinetic Inductance Detectors (MKIDs) for high-contrast imaging. The photon counting and simultaneous low-resolution spectroscopy provided by MKIDs will enable real-time speckle control techniques and post-processing speckle suppression at frame rates capable of resolving the atmospheric speckles that currently limit high-contrast imaging from the ground. DARKNESS is now operational behind the PALM-3000 extreme adaptive optics system and the Stellar Double Coronagraph at Palomar Observatory. Here, we describe the motivation, design, and characterization of the instrument, early on-sky results, and future prospects.

Last technology and results from the IOTA interferometer

NASA Astrophysics Data System (ADS)

Pedretti, Ettore; Traub, Wesley A.; Monnier, John D.; Schuller, Peter A.; Ragland, Sam; Berger, Jean–Philippe; Millan-Gabet, Rafael; Wallace, Gary; Burke, Michael; Lacasse, Marc G.; Thureau, Nathalie D.; Carleton, Nathaniel

2008-07-01

The infrared optical telescope array (IOTA), one of the most productive interferometers in term of science and new technologies was decommissioned in summer 2006. We discuss the testing of a low-resolution spectrograph coupled with the IOTA-3T integrated-optics beam combiner and some of the scientific results obtained from this instrument.

GMTIFS: the adaptive optics beam steering mirror for the GMT integral-field spectrograph

NASA Astrophysics Data System (ADS)

Davies, J.; Bloxham, G.; Boz, R.; Bundy, D.; Espeland, B.; Fordham, B.; Hart, J.; Herrald, N.; Nielsen, J.; Sharp, R.; Vaccarella, A.; Vest, C.; Young, P. J.

2016-07-01

To achieve the high adaptive optics sky coverage necessary to allow the GMT Integral-Field Spectrograph (GMTIFS) to access key scientific targets, the on-instrument adaptive-optics wavefront-sensing (OIWFS) system must patrol the full 180 arcsecond diameter guide field passed to the instrument. The OIWFS uses a diffraction limited guide star as the fundamental pointing reference for the instrument. During an observation the offset between the science target and the guide star will change due to sources such as flexure, differential refraction and non-sidereal tracking rates. GMTIFS uses a beam steering mirror to set the initial offset between science target and guide star and also to correct for changes in offset. In order to reduce image motion from beam steering errors to those comparable to the AO system in the most stringent case, the beam steering mirror is set a requirement of less than 1 milliarcsecond RMS. This corresponds to a dynamic range for both actuators and sensors of better than 1/180,000. The GMTIFS beam steering mirror uses piezo-walk actuators and a combination of eddy current sensors and interferometric sensors to achieve this dynamic range and control. While the sensors are rated for cryogenic operation, the actuators are not. We report on the results of prototype testing of single actuators, with the sensors, on the bench and in a cryogenic environment. Specific failures of the system are explained and suspected reasons for them. A modified test jig is used to investigate the option of heating the actuator and we report the improved results. In addition to individual component testing, we built and tested a complete beam steering mirror assembly. Testing was conducted with a point source microscope, however controlling environmental conditions to less than 1 micron was challenging. The assembly testing investigated acquisition accuracy and if there was any un-sensed hysteresis in the system. Finally we present the revised beam steering mirror design based on the outcomes and lessons learnt from this prototyping.

Solar Imaging UV/EUV Spectrometers Using TVLS Gratings

NASA Technical Reports Server (NTRS)

Thomas, Roger J.

2003-01-01

It is a particular challenge to develop a stigmatic spectrograph for UV, EUV wavelengths since the very low normal-incidence reflectance of standard materials most often requires that the design be restricted to a single optical element which must simultaneously provide both reimaging and spectral dispersion. This problem has been solved in the past by the use of toroidal gratings with uniform line-spaced rulings (TULS). A number of solar extreme ultraviolet (EUV) spectrometers have been based on such designs, including SOHO/CDS, Solar-B/EIS, and the sounding rockets Solar Extreme ultraviolet Research Telescope and Spectrograph (SERTS) and Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS). More recently, Kita, Harada, and collaborators have developed the theory of spherical gratings with varied line-space rulings (SVLS) operated at unity magnification, which have been flown on several astronomical satellite missions. We now combine these ideas into a spectrometer concept that puts varied-line space rulings onto toroidal gratings. Such TVLS designs are found to provide excellent imaging even at very large spectrograph magnifications and beam-speeds, permitting extremely high-quality performance in remarkably compact instrument packages. Optical characteristics of three new solar spectrometers based on this concept are described: SUMI and RAISE, two sounding rocket payloads, and NEXUS, currently being proposed as a Small-Explorer (SMEX) mission.

[Design and analysis of a novel light visible spectrum imaging spectrograph optical system].

PubMed

Shen, Man-de; Li, Fei; Zhou, Li-bing; Li, Cheng; Ren, Huan-huan; Jiang, Qing-xiu

2015-02-01

A novel visible spectrum imaging spectrograph optical system was proposed based on the negative dispersion, the arbitrary phase modulation characteristics of diffractive optical element and the aberration correction characteristics of freeform optical element. The double agglutination lens was substituted by a hybrid refractive/diffractive lens based on the negative dispersion of diffractive optical element. Two freeform optical elements were used in order to correct some aberration based on the aberration correction characteristics of freeform optical element. An example and frondose design process were presented. When the design parameters were uniform, compared with the traditional system, the novel visible spectrum imaging spectrograph optical system's weight was reduced by 22.9%, the total length was reduced by 26.6%, the maximal diameter was reduced by 30.6%, and the modulation transfer function (MTF) in 1.0 field-of-view was improved by 0.35 with field-of-view improved maximally. The maximal distortion was reduced by 1.6%, the maximal longitudinal aberration was reduced by 56.4%, and the lateral color aberration was reduced by 59. 3%. From these data, we know that the performance of the novel system was advanced quickly and it could be used to put forward a new idea for modern visible spectrum imaging spectrograph optical system design.

Optical fiber systems for the BigBOSS instrument

NASA Astrophysics Data System (ADS)

Edelstein, Jerry; Poppett, Claire; Sirk, Martin; Besuner, Robert; Lafever, Robin; Allington-Smith, Jeremy R.; Murray, Graham J.

2012-09-01

We describe the fiber optics systems for use in BigBOSS, a proposed massively parallel multi-object spectrograph for the Kitt Peak Mayall 4-m telescope that will measure baryon acoustic oscillations to explore dark energy. BigBOSS will include 5,000 optical fibers each precisely actuator-positioned to collect an astronomical target’s flux at the telescope prime-focus. The fibers are to be routed 40m through the telescope facility to feed ten visible-band imaging spectrographs. We report on our fiber component development and performance measurement program. Results include the numerical modeling of focal ratio degradation (FRD), observations of actual fibers’ collimated and converging beam FRD, and observations of FRD from different types of fiber terminations, mechanical connectors, and fusion-splice connections.

WISDOM: the WIYN spectrograph for Doppler monitoring: a NASA-NSF concept for an extreme precision radial velocity instrument in support of TESS

NASA Astrophysics Data System (ADS)

Fżrész, Gábor; Simcoe, Robert; Barnes, Stuart I.; Buchhave, Lars A.; Egan, Mark; Foster, Rick; Hellickson, Tim; Malonis, Andrew; Phillips, David; Shectman, Stephen; Walsworth, Ronald; Winn, Josh; Woods, Deborah

2016-08-01

The Kepler mission highlighted that precision radial velocity (PRV) follow-up is a real bottleneck in supporting transiting exoplanet surveys. The limited availability of PRV instruments, and the desire to break the "1 m/s" precision barrier, prompted the formation of a NASA-NSF collaboration `NN-EXPLORE' to call for proposals designing a new Extreme Precision Doppler Spectrograph (EPDS). By securing a significant fraction of telescope time on the 3.5m WIYN at Kitt Peak, and aiming for unprecedented long-term precision, the EPDS instrument will provide a unique tool for U.S. astronomers in characterizing exoplanet candidates identified by TESS. One of the two funded instrument concept studies is led by the Massachusetts Institute of Technology, in consortium with Lincoln Laboratories, Harvard-Smithsonian Center for Astrophysics and the Carnegie Observatories. This paper describes the instrument concept WISDOM (WIYN Spectrograph for DOppler Monitoring) prepared by this team. WISDOM is a fiber fed, environmentally controlled, high resolution (R=110k), asymmetric white-pupil echelle spectrograph, covering a wide 380-1300nm wavelength region. Its R4 and R6 echelle gratings provide the main dispersion, symmetrically mounted on either side of a vertically aligned, vacuum-enclosed carbon fiber optical bench. Each grating feeds two cameras and thus the resulting wavelength range per camera is narrow enough that the VPHG cross-dispersers and employed anti-reflection coatings are highly efficient. The instrument operates near room temperature, and so thermal background for the near-infrared arm is mitigated by thermal blocking filters and a short (1.7μm) cutoff HgCdTe detector. To achieve high resolution while maintaining small overall instrument size (100/125mm beam diameter), imposed by the limited available space within the observatory building, we chose to slice the telescope pupil 6 ways before coupling light into fibers. An atmospheric dispersion corrector and fast tip-tilt system assures maximal light gathering within the 1.2″ entrance aperture. The six octagonal fibers corresponding to each slice of the pupil employ ball-lens double scramblers to stabilize the near- and far-fields. Three apiece are coupled into each of two rectangular fibers, to mitigate modal nose and present a rectilinear illumination pattern at the spectrograph's slit plane. Wavelength solutions are derived from ThAr lamps and an extremely wide coverage dual-channel laser frequency comb. Data is reduced on the fly for evaluation by a custom pipeline, while daily archives and extended scope data reduction products are stored on NExScI servers, also managing archives and access privileges for GTO and GO programs. Note: individual papers, submitted along this main paper, describe the details of subsystems such as the optical design (Barnes et al., 9908-247), the fiber link design (Fűrész et al., 9908-281), and the pupil slicer (Egan et al., 9912-183).

Over-under double-pass interferometer

NASA Technical Reports Server (NTRS)

Schindler, R. A. (Inventor)

1977-01-01

An over-under double pass interferometer in which the beamsplitter area and thickness can be reduced to conform only with optical flatness considerations was achieved by offsetting the optical center line of one cat's-eye retroreflector relative to the optical center line of the other in order that one split beam be folded into a plane distinct from the other folded split beam. The beamsplitter is made transparent in one area for a first folded beam to be passed to a mirror for doubling back and is made totally reflective in another area for the second folded beam to be reflected to a mirror for doubling back. The two beams thus doubled back are combined in the central, beamsplitting area of the beamsplitting and passed to a detector. This makes the beamsplitter insensitive to minimum thickness requirements and selection of material.

Optical design of MEMS-based infrared multi-object spectrograph concept for the Gemini South Telescope

NASA Astrophysics Data System (ADS)

Chen, Shaojie; Sivanandam, Suresh; Moon, Dae-Sik

2016-08-01

We discuss the optical design of an infrared multi-object spectrograph (MOS) concept that is designed to take advantage of the multi-conjugate adaptive optics (MCAO) corrected field at the Gemini South telescope. This design employs a unique, cryogenic MEMS-based focal plane mask to select target objects for spectroscopy by utilizing the Micro-Shutter Array (MSA) technology originally developed for the Near Infrared Spectrometer (NIRSpec) of the James Webb Space Telescope (JWST). The optical design is based on all spherical refractive optics, which serves both imaging and spectroscopic modes across the wavelength range of 0.9-2.5 μm. The optical system consists of a reimaging system, MSA, collimator, volume phase holographic (VPH) grisms, and spectrograph camera optics. The VPH grisms, which are VPH gratings sandwiched between two prisms, provide high dispersing efficiencies, and a set of several VPH grisms provide the broad spectral coverage at high throughputs. The imaging mode is implemented by removing the MSA and the dispersing unit out of the beam. We optimize both the imaging and spectrographic modes simultaneously, while paying special attention to the performance of the pupil imaging at the cold stop. Our current design provides a 1' ♢ 1' and a 0.5' ♢ 1' field of views for imaging and spectroscopic modes, respectively, on a 2048 × 2048 pixel HAWAII-2RG detector array. The spectrograph's slit width and spectral resolving power are 0.18'' and 3,000, respectively, and spectra of up to 100 objects can be obtained simultaneously. We present the overall results of simulated performance using optical model we designed.

New modified multi-level residue harmonic balance method for solving nonlinearly vibrating double-beam problem

NASA Astrophysics Data System (ADS)

Rahman, Md. Saifur; Lee, Yiu-Yin

2017-10-01

In this study, a new modified multi-level residue harmonic balance method is presented and adopted to investigate the forced nonlinear vibrations of axially loaded double beams. Although numerous nonlinear beam or linear double-beam problems have been tackled and solved, there have been few studies of this nonlinear double-beam problem. The geometric nonlinear formulations for a double-beam model are developed. The main advantage of the proposed method is that a set of decoupled nonlinear algebraic equations is generated at each solution level. This heavily reduces the computational effort compared with solving the coupled nonlinear algebraic equations generated in the classical harmonic balance method. The proposed method can generate the higher-level nonlinear solutions that are neglected by the previous modified harmonic balance method. The results from the proposed method agree reasonably well with those from the classical harmonic balance method. The effects of damping, axial force, and excitation magnitude on the nonlinear vibrational behaviour are examined.

Fireball multi object spectrograph: as-built optic performances

NASA Astrophysics Data System (ADS)

Grange, R.; Milliard, B.; Lemaitre, G.; Quiret, S.; Pascal, S.; Origné, A.; Hamden, E.; Schiminovich, D.

2016-07-01

Fireball (Faint Intergalactic Redshifted Emission Balloon) is a NASA/CNES balloon-borne experiment to study the faint diffuse circumgalactic medium from the line emissions in the ultraviolet (200 nm) above 37 km flight altitude. Fireball relies on a Multi Object Spectrograph (MOS) that takes full advantage of the new high QE, low noise 13 μm pixels UV EMCCD. The MOS is fed by a 1 meter diameter parabola with an extended field (1000 arcmin2) using a highly aspherized two mirror corrector. All the optical train is working at F/2.5 to maintain a high signal to noise ratio. The spectrograph (R 2200 and 1.5 arcsec FWHM) is based on two identical Schmidt systems acting as collimator and camera sharing a 2400 g/mm aspherized reflective Schmidt grating. This grating is manufactured from active optics methods by double replication technique of a metal deformable matrix whose active clear aperture is built-in to a rigid elliptical contour. The payload and gondola are presently under integration at LAM. We will present the alignment procedure and the as-built optic performances of the Fireball instrument.

VizieR Online Data Catalog: R-band light curves of type II supernovae (Rubin+, 2016)

NASA Astrophysics Data System (ADS)

Rubin, A.; Gal-Yam, A.; De Cia, A.; Horesh, A.; Khazov, D.; Ofek, E. O.; Kulkarni, S. R.; Arcavi, I.; Manulis, I.; Yaron, O.; Vreeswijk, P.; Kasliwal, M. M.; Ben-Ami, S.; Perley, D. A.; Cao, Y.; Cenko, S. B.; Rebbapragada, U. D.; Wozniak, P. R.; Filippenko, A. V.; Clubb, K. I.; Nugent, P. E.; Pan, Y.-C.; Badenes, C.; Howell, D. A.; Valenti, S.; Sand, D.; Sollerman, J.; Johansson, J.; Leonard, D. C.; Horst, J. C.; Armen, S. F.; Fedrow, J. M.; Quimby, R. M.; Mazzali, P.; Pian, E.; Sternberg, A.; Matheson, T.; Sullivan, M.; Maguire, K.; Lazarevic, S.

2016-05-01

Our sample consists of 57 SNe from the PTF (Law et al. 2009PASP..121.1395L; Rau et al. 2009PASP..121.1334R) and the intermediate Palomar Transient Factory (iPTF; Kulkarni 2013ATel.4807....1K) surveys. Data were routinely collected by the Palomar 48-inch survey telescope in the Mould R-band. Follow-up observations were conducted mainly with the robotic 60-inch telescope using an SDSS r-band filter, with additional telescopes providing supplementary photometry and spectroscopy (see Gal-Yam et al. 2011, J/ApJ/736/159). The full list of SNe, their coordinates, and classification spectra are presented in Table 1. Most of the spectra were obtained with the Double Spectrograph on the 5m Hale telescope at Palomar Observatory, the Kast spectrograph on the Shane 3m telescope at Lick Observatory, the Low Resolution Imaging Spectrometer (LRIS) on the Keck I 10m telescope, and the DEep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II 10m telescope. (2 data files).

ANALYSIS OF ENERGY LOSSES OF A 30-kev ELECTRON BEAM IN THE FLUORIDE, CHLORIDE, AND BROMIDE OF LITHIUM (in French)

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

Pradal, F.; Gout, C.

1963-02-01

The energy loss of a 30-kev electron beam in films of LiF, LiCl, and LiBr were analyzed with a magnetic spectrograph. For LiF, the results are compared to the absorption curve in the ultraviolet. The rays observed seem due to the excitation of valence band electrons of the 2s band of F/sup -/ and the 1s band of Li/sup +/. In some cases, energy losses less than 10 ev were observed, which seems connected to the presence of color centers. (tr-auth)

Experiment to Detect Accelerating Modes in a Photonic Bandgap Fiber

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

England, R.J.; /SLAC; Colby, E.R.

An experimental effort is currently underway at the E-163 test beamline at Stanford Linear Accelerator Center to use a hollow-core photonic bandgap (PBG) fiber as a high-gradient laser-based accelerating structure for electron bunches. For the initial stage of this experiment, a 50pC, 60 MeV electron beam will be coupled into the fiber core and the excited modes will be detected using a spectrograph to resolve their frequency signatures in the wakefield radiation generated by the beam. They will describe the experimental plan and recent simulation studies of candidate fibers.

Laser continuum source atomic absorption spectroscopy: Measuring the ground state with nanosecond resolution in laser-induced plasmas

NASA Astrophysics Data System (ADS)

Merten, Jonathan; Johnson, Bruce

2018-01-01

A new dual-beam atomic absorption technique is applied to laser-induced plasmas. The technique uses an optical parametric oscillator pseudocontinuum, producing emission that is both wider than the absorption line profile, but narrow enough to allow the use of an echelle spectrograph without order sorting. The dual-beam-in space implementation makes the technique immune to nonspecific attenuation of the probe beam and the structure of the pseudocontinuum. The potential for plasma diagnostics is demonstrated with spatially and temporally resolved measurements of magnesium metastable and lithium ground state optical depths in a laser-induced plasma under reduced pressure conditions. The lithium measurements further demonstrate the technique's potential for isotope ratio measurements.

Beam current enhancement of microwave plasma ion source utilizing double-port rectangular cavity resonator

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

Lee, Yuna; Park, Yeong-Shin; Jo, Jong-Gab

2012-02-15

Microwave plasma ion source with rectangular cavity resonator has been examined to improve ion beam current by changing wave launcher type from single-port to double-port. The cavity resonators with double-port and single-port wave launchers are designed to get resonance effect at TE-103 mode and TE-102 mode, respectively. In order to confirm that the cavities are acting as resonator, the microwave power for breakdown is measured and compared with the E-field strength estimated from the HFSS (High Frequency Structure Simulator) simulation. Langmuir probe measurements show that double-port cavity enhances central density of plasma ion source by modifying non-uniform plasma density profilemore » of the single-port cavity. Correspondingly, beam current from the plasma ion source utilizing the double-port resonator is measured to be higher than that utilizing single-port resonator. Moreover, the enhancement in plasma density and ion beam current utilizing the double-port resonator is more pronounced as higher microwave power applied to the plasma ion source. Therefore, the rectangular cavity resonator utilizing the double-port is expected to enhance the performance of plasma ion source in terms of ion beam extraction.« less

Beam current enhancement of microwave plasma ion source utilizing double-port rectangular cavity resonator.

PubMed

Lee, Yuna; Park, Yeong-Shin; Jo, Jong-Gab; Yang, J J; Hwang, Y S

2012-02-01

Microwave plasma ion source with rectangular cavity resonator has been examined to improve ion beam current by changing wave launcher type from single-port to double-port. The cavity resonators with double-port and single-port wave launchers are designed to get resonance effect at TE-103 mode and TE-102 mode, respectively. In order to confirm that the cavities are acting as resonator, the microwave power for breakdown is measured and compared with the E-field strength estimated from the HFSS (High Frequency Structure Simulator) simulation. Langmuir probe measurements show that double-port cavity enhances central density of plasma ion source by modifying non-uniform plasma density profile of the single-port cavity. Correspondingly, beam current from the plasma ion source utilizing the double-port resonator is measured to be higher than that utilizing single-port resonator. Moreover, the enhancement in plasma density and ion beam current utilizing the double-port resonator is more pronounced as higher microwave power applied to the plasma ion source. Therefore, the rectangular cavity resonator utilizing the double-port is expected to enhance the performance of plasma ion source in terms of ion beam extraction.

Propagation of Bessel-Gaussian beams through a double-apertured fractional Fourier transform optical system.

PubMed

Tang, Bin; Jiang, Chun; Zhu, Haibin

2012-08-01

Based on the scalar diffraction theory and the fact that a hard-edged aperture function can be expanded into a finite sum of complex Gaussian functions, an approximate analytical solution for Bessel-Gaussian (BG) beams propagating through a double-apertured fractional Fourier transform (FrFT) system is derived in the cylindrical coordinate. By using the approximate analytical formulas, the propagation properties of BG beams passing through a double-apertured FrFT optical system have been studied in detail by some typical numerical examples. The results indicate that the double-apertured FrFT optical system provides a convenient way for controlling the properties of the BG beams by properly choosing the optical parameters.

Designing the optimal semi-warm NIR spectrograph for SALT via detailed thermal analysis

NASA Astrophysics Data System (ADS)

Wolf, Marsha J.; Sheinis, Andrew I.; Mulligan, Mark P.; Wong, Jeffrey P.; Rogers, Allen

2008-07-01

The near infrared (NIR) upgrade to the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT), RSS/NIR, extends the spectral coverage of all modes of the optical spectrograph. The RSS/NIR is a low to medium resolution spectrograph with broadband, spectropolarimetric, and Fabry-Perot imaging capabilities. The optical and NIR arms can be used simultaneously to extend spectral coverage from 3200 Å to approximately 1.6 μm. Both arms utilize high efficiency volume phase holographic gratings via articulating gratings and cameras. The NIR camera incorporates a HAWAII-2RG detector with an Epps optical design consisting of 6 spherical elements and providing subpixel rms image sizes of 7.5 +/- 1.0 μm over all wavelengths and field angles. The NIR spectrograph is semi-warm, sharing a common slit plane and partial collimator with the optical arm. A pre-dewar, cooled to below ambient temperature, houses the final NIR collimator optic, the grating/Fabry-Perot etalon, the polarizing beam splitter, and the first three camera optics. The last three camera elements, blocking filters, and detector are housed in a cryogenically cooled dewar. The semi-warm design concept has long been proposed as an economical way to extend optical instruments into the NIR, however, success has been very limited. A major portion of our design effort entails a detailed thermal analysis using non-sequential ray tracing to interactively guide the mechanical design and determine a truly realizable long wavelength cutoff over which astronomical observations will be sky-limited. In this paper we describe our thermal analysis, design concepts for the staged cooling scheme, and results to be incorporated into the overall mechanical design and baffling.

Dual surface interferometer

DOEpatents

Pardue, R.M.; Williams, R.R.

1980-09-12

A double-pass interferometer is provided which allows direct measurement of relative displacement between opposed surfaces. A conventional plane mirror interferometer may be modified by replacing the beam-measuring path cube-corner reflector with an additional quarterwave plate. The beam path is altered to extend to an opposed plane mirrored surface and the reflected beam is placed in interference with a retained reference beam split from dual-beam source and retroreflected by a reference cube-corner reflector mounted stationary with the interferometer housing. This permits direct measurement of opposed mirror surfaces by laser interferometry while doubling the resolution as with a conventional double-pass plane mirror laser interferometer system.

Dual surface interferometer

DOEpatents

Pardue, Robert M.; Williams, Richard R.

1982-01-01

A double-pass interferometer is provided which allows direct measurement of relative displacement between opposed surfaces. A conventional plane mirror interferometer may be modified by replacing the beam-measuring path cube-corner reflector with an additional quarter-wave plate. The beam path is altered to extend to an opposed plane mirrored surface and the reflected beam is placed in interference with a retained reference beam split from dual-beam source and retroreflected by a reference cube-corner reflector mounted stationary with the interferometer housing. This permits direct measurement of opposed mirror surfaces by laser interferometry while doubling the resolution as with a conventional double-pass plane mirror laser interferometer system.

Development of the beam extraction synchronization system at the Fermilab Booster

DOE PAGES

Seiya, K.; Chaurize, S.; Drennan, C. C.; ...

2015-07-28

The new beam extraction synchronization control system called “Magnetic Cogging” was developed at the Fermilab Booster and it replaces a system called “RF Cogging” as part of the Proton Improvement Plan (PIP). [1] The flux throughput goal for the PIP is 2.2×10 17 protons per hour, which is double the present flux. Thus, the flux increase will be accomplished by doubling the number of beam cycles which, in turn, will double the beam loss in the Booster accelerator if nothing else is done.

Fiber Scrambling for High Precision Spectrographs

NASA Astrophysics Data System (ADS)

Kaplan, Zachary; Spronck, J. F. P.; Fischer, D.

2011-05-01

The detection of Earth-like exoplanets with the radial velocity method requires extreme Doppler precision and long-term stability in order to measure tiny reflex velocities in the host star. Recent planet searches have led to the detection of so called "super-Earths” (up to a few Earth masses) that induce radial velocity changes of about 1 m/s. However, the detection of true Earth analogs requires a precision of 10 cm/s. One of the largest factors limiting Doppler precision is variation in the Point Spread Function (PSF) from observation to observation due to changes in the illumination of the slit and spectrograph optics. Thus, this stability has become a focus of current instrumentation work. Fiber optics have been used since the 1980's to couple telescopes to high-precision spectrographs, initially for simpler mechanical design and control. However, fiber optics are also naturally efficient scramblers. Scrambling refers to a fiber's ability to produce an output beam independent of input. Our research is focused on characterizing the scrambling properties of several types of fibers, including circular, square and octagonal fibers. By measuring the intensity distribution after the fiber as a function of input beam position, we can simulate guiding errors that occur at an observatory. Through this, we can determine which fibers produce the most uniform outputs for the severest guiding errors, improving the PSF and allowing sub-m/s precision. However, extensive testing of fibers of supposedly identical core diameter, length and shape from the same manufacturer has revealed the "personality” of individual fibers. Personality describes differing intensity patterns for supposedly duplicate fibers illuminated identically. Here, we present our results on scrambling characterization as a function of fiber type, while studying individual fiber personality.

Generation of vector beams using a double-wedge depolarizer: Non-quantum entanglement

NASA Astrophysics Data System (ADS)

Samlan, C. T.; Viswanathan, Nirmal K.

2016-07-01

Propagation of horizontally polarized Gaussian beam through a double-wedge depolarizer generates vector beams with spatially varying state of polarization. Jones calculus is used to show that such beams are maximally nonseparable on the basis of even (Gaussian)-odd (Hermite-Gaussian) mode parity and horizontal-vertical polarization state. The maximum nonseparability in the two degrees of freedom of the vector beam at the double wedge depolarizer output is verified experimentally using a modified Sagnac interferometer and linear analyser projected interferograms to measure the concurrence 0.94±0.002 and violation of Clauser-Horne-Shimony-Holt form of Bell-like inequality 2.704±0.024. The investigation is carried out in the context of the use of vector beams for metrological applications.

Compact electrostatic beam optics for multi-element focused ion beams: simulation and experiments.

PubMed

Mathew, Jose V; Bhattacharjee, Sudeep

2011-01-01

Electrostatic beam optics for a multi-element focused ion beam (MEFIB) system comprising of a microwave multicusp plasma (ion) source is designed with the help of two widely known and commercially available beam simulation codes: AXCEL-INP and SIMION. The input parameters to the simulations are obtained from experiments carried out in the system. A single and a double Einzel lens system (ELS) with and without beam limiting apertures (S) have been investigated. For a 1 mm beam at the plasma electrode aperture, the rms emittance of the focused ion beam is found to reduce from ∼0.9 mm mrad for single ELS to ∼0.5 mm mrad for a double ELS, when S of 0.5 mm aperture size is employed. The emittance can be further improved to ∼0.1 mm mrad by maintaining S at ground potential, leading to reduction in beam spot size (∼10 μm). The double ELS design is optimized for different electrode geometrical parameters with tolerances of ±1 mm in electrode thickness, electrode aperture, inter electrode distance, and ±1° in electrode angle, providing a robust design. Experimental results obtained with the double ELS for the focused beam current and spot size, agree reasonably well with the simulations.

Development of the fibres of MOONS

NASA Astrophysics Data System (ADS)

Guinouard, Isabelle; Lee, David; Schnetler, Hermine; Taylor, William; Amans, Jean-Philippe; Montgomery, David; Oliva, Ernesto

2014-07-01

MOONS will exploit the full 500 square arcmin field of view offered by the Nasmyth focus of the Very Large Telescope and will be equipped with two identical triple arm cryogenic spectrographs covering the wavelength range 0.8 - 1.8 μm, with a multiplex capability of approximately 1000 fibres. Each triple arm spectrograph will produce spectra for half of the targets simultaneously. The system will have both a medium resolution (R~4000-6000) mode and a high resolution (R~20000) mode. The fibres are used to pick off each sub field of 1.05 arcseconds and are used to transport the light from the instrument focal plane to the two spectrographs. Each fibre has a microlens to focus the beam into the fibre at a relative fast focal ratio of F/3.65 to reduce the Focal Ratio Degradation (FRD). This paper presents the overall design of the fibre system and describes the specific developments required to optimise its performance. The design of the fibre input optics, the choice of the fibre connector, and the layout of the slit end are described. The results of preliminary tests to measure the effect of twisting on the FRD performance of prototype fibres are also discussed.

MSE spectrograph optical design: a novel pupil slicing technique

NASA Astrophysics Data System (ADS)

Spanò, P.

2014-07-01

The Maunakea Spectroscopic Explorer shall be mainly devoted to perform deep, wide-field, spectroscopic surveys at spectral resolutions from ~2000 to ~20000, at visible and near-infrared wavelengths. Simultaneous spectral coverage at low resolution is required, while at high resolution only selected windows can be covered. Moreover, very high multiplexing (3200 objects) must be obtained at low resolution. At higher resolutions a decreased number of objects (~800) can be observed. To meet such high demanding requirements, a fiber-fed multi-object spectrograph concept has been designed by pupil-slicing the collimated beam, followed by multiple dispersive and camera optics. Different resolution modes are obtained by introducing anamorphic lenslets in front of the fiber arrays. The spectrograph is able to switch between three resolution modes (2000, 6500, 20000) by removing the anamorphic lenses and exchanging gratings. Camera lenses are fixed in place to increase stability. To enhance throughput, VPH first-order gratings has been preferred over echelle gratings. Moreover, throughput is kept high over all wavelength ranges by splitting light into more arms by dichroic beamsplitters and optimizing efficiency for each channel by proper selection of glass materials, coatings, and grating parameters.

Nuclear Physics Laboratory technical progress report, November 1, 1972-- November 1, 1973

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

None

1973-11-01

The experimental program was divided into the areas of nuclear physics (charged-particle experiments, gamma-ray experiments andd beta decay, neutron time-of-flight experiments, x-ray fluorescence analysis, other activities), intermediate enengy physics, and apparatus and facility development. The energy- loss spectrograph, rotating-beam neutron time-of-flight spectrometer, and cyclotron and the rearch done using these facilities are described. The theoretical program has concentrated on the effects of two-step processes in nuclear reactions. The trace element analysis program continued, and a neutron beam for cancer therapy is being developed. Lists of publications and personnel are also included. (RWR)

TH-C-BRD-04: Beam Modeling and Validation with Triple and Double Gaussian Dose Kernel for Spot Scanning Proton Beams

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

Hirayama, S; Takayanagi, T; Fujii, Y

2014-06-15

Purpose: To present the validity of our beam modeling with double and triple Gaussian dose kernels for spot scanning proton beams in Nagoya Proton Therapy Center. This study investigates the conformance between the measurements and calculation results in absolute dose with two types of beam kernel. Methods: A dose kernel is one of the important input data required for the treatment planning software. The dose kernel is the 3D dose distribution of an infinitesimal pencil beam of protons in water and consists of integral depth doses and lateral distributions. We have adopted double and triple Gaussian model as lateral distributionmore » in order to take account of the large angle scattering due to nuclear reaction by fitting simulated inwater lateral dose profile for needle proton beam at various depths. The fitted parameters were interpolated as a function of depth in water and were stored as a separate look-up table for the each beam energy. The process of beam modeling is based on the method of MDACC [X.R.Zhu 2013]. Results: From the comparison results between the absolute doses calculated by double Gaussian model and those measured at the center of SOBP, the difference is increased up to 3.5% in the high-energy region because the large angle scattering due to nuclear reaction is not sufficiently considered at intermediate depths in the double Gaussian model. In case of employing triple Gaussian dose kernels, the measured absolute dose at the center of SOBP agrees with calculation within ±1% regardless of the SOBP width and maximum range. Conclusion: We have demonstrated the beam modeling results of dose distribution employing double and triple Gaussian dose kernel. Treatment planning system with the triple Gaussian dose kernel has been successfully verified and applied to the patient treatment with a spot scanning technique in Nagoya Proton Therapy Center.« less

The Magellan Telescopes

NASA Astrophysics Data System (ADS)

Shectman, Stephen A.; Johns, Matthew

2003-02-01

Commissioning of the two 6.5-meter Magellan telescopes is nearing completion at the Las Campanas Observatory in Chile. The Magellan 1 primary mirror was successfully aluminized at Las Campanas in August 2000. Science operations at Magellan 1 began in February 2001. The second Nasmyth focus on Magellan 1 went into operation in September 2001. Science operations on Magellan 2 are scheduled to begin shortly. The ability to deliver high-quality images is maintained at all times by the simultaneous operation of the primary mirror support system, the primary mirror thermal control system, and a real-time active optics system, based on a Shack-Hartmann image analyzer. Residual aberrations in the delivered image (including focus) are typically 0.10-0.15" fwhm, and real images as good as 0.25" fwhm have been obtained at optical wavelengths. The mount points reliably to 2" rms over the entire sky, using a pointing model which is stable from year to year. The tracking error under typical wind conditions is better than 0.03" rms, although some degradation is observed under high wind conditions when the dome is pointed in an unfavorable direction. Instruments used at Magellan 1 during the first year of operation include two spectrographs previously used at other telescopes (B&C, LDSS-2), a mid-infrared imager (MIRAC) and an optical imager (MAGIC, the first Magellan-specific facility instrument). Two facility spectrographs are scheduled to be installed shortly: IMACS, a wide-field spectrograph, and MIKE, a double echelle spectrograph.

Solar XUV grazing incidence spectrograph on Skylab.

PubMed

Garrett, D L; Tousey, R

1977-04-01

The objective of Skylab corollary experiment S020 was to obtain through the availability of long exposure times more complete information than was then available on the extreme ultraviolet (XUV) and soft x-ray spectrum of the sun in the 10-200-A range. The instrument was a small grazing incidence spectrograph with photographic recording. Use was made of a novel split-ruled grating that combined 1200- and 2400-1/mm rulings to double the spectral coverage of the instrument and to aid in the measurement of wavelengths and order sorting. As it happened, there were many difficulties resulting from the major problems encountered by the Apollo and Skylab missions. Useful spectra were obtained, but the sensitivity of the instrument was greatly reduced, probably because of contamination resulting from leakage of the fluid used in the spacecraft cooling system.

Double deflection system for an electron beam device

DOEpatents

Parker, Norman W.; Golladay, Steven D.; Crewe, Albert V.

1978-01-01

A double deflection scanning system for electron beam instruments is provided embodying a means of correcting isotropic coma, and anisotropic coma aberrations induced by the magnetic lens of such an instrument. The scanning system deflects the beam prior to entry into the magnetic lens from the normal on-axis intersection of the beam with the lens according to predetermined formulas and thereby reduces the aberrations.

Limiting effects in double EEX beamline

NASA Astrophysics Data System (ADS)

Ha, G.; Power, J. G.; Conde, M.; Doran, D. S.; Gai, W.

2017-07-01

The double emittance exchange (EEX) beamline is suggested to overcome the large horizontal emittance and transverse jitter issues associated with the single EEX beamline while preserving its powerful phase-space manipulation capability. However, the double EEX beamline also has potential limitations due to coherent synchrotron radiation (CSR) and transverse jitter. The former limitation arises because double EEX uses twice as many bending magnets as single EEX which means stronger CSR effects degrading the beam quality. The latter limitation arises because a longitudinal jitter in front of the first EEX beamline is converted into a transverse jitter in the middle section (between the EEX beamlines) which can cause beam loss or beam degradation. In this paper, we numerically explore the effects of these two limitations on the emittance and beam transport.

A microlens-array based pupil slicer and double scrambler for MAROON-X

NASA Astrophysics Data System (ADS)

Seifahrt, Andreas; Stürmer, Julian; Bean, Jacob L.

2016-07-01

We report on the design and construction of a microlens-array (MLA)-based pupil slicer and double scrambler for MAROON-X, a new fiber-fed, red-optical, high-precision radial-velocity spectrograph for one of the twin 6.5m Magellan Telescopes in Chile. We have constructed a 3X slicer based on a single cylindrical MLA and show that geometric efficiencies of >=85% can be achieved, limited by the fill factor and optical surface quality of the MLA. We present here the final design of the 3x pupil slicer and double scrambler for MAROON-X, based on a dual MLA design with (a)spherical lenslets. We also discuss the techniques used to create a pseudo-slit of rectangular core fibers with low FRD levels.

Creating unconventional geometric beams with large depth of field using double freeform-surface optics.

PubMed

Feng, Zexin; Froese, Brittany D; Huang, Chih-Yu; Ma, Donglin; Liang, Rongguang

2015-07-10

We consider here creation of an unconventional flattop beam with a large depth of field by employing double freeform optical surfaces. The output beam is designed with continuous variations from the flattop to almost zero near the edges to resist the influence of diffraction on its propagation. We solve this challenging problem by naturally incorporating an optimal transport map computation scheme for unconventional boundary conditions with a simultaneous point-by-point double surface construction procedure. We demonstrate experimentally the generation of a long-range propagated triangular beam through a plano-freeform lens pair fabricated by a diamond-tuning machine.

CALUTRON

DOEpatents

Brobeck, W.M.; Lofgren, E.J.; Thornton, R.L.

1959-06-01

A calutron improved in liner and capacity is offered. The liner is a hollow insulated structure at high negative potential with respect to the vessel. The liner has delimiting vanes to prevent ions from one beam scattering into the receiver from another beam. The double beam-double receiver feature is thus made possible, increasing the capacity of the calutron. (T.R.H.)

Interferometric Methods of Measuring Refractive Indices and Double-Refraction of Fibres.

ERIC Educational Resources Information Center

Hamza, A. A.; El-Kader, H. I. Abd

1986-01-01

Presents two methods used to measure the refractive indices and double-refraction of fibers. Experiments are described, with one involving the use of Pluta microscope in the double-beam interference technique, the other employing the multiple-beam technique. Immersion liquids are discussed that can be used in the experiments. (TW)

NIRPS: an adaptive-optics assisted radial velocity spectrograph to chase exoplanets around M-stars

NASA Astrophysics Data System (ADS)

Wildi, F.; Blind, N.; Reshetov, V.; Hernandez, O.; Genolet, L.; Conod, U.; Sordet, M.; Segovilla, A.; Rasilla, J. L.; Brousseau, D.; Thibault, S.; Delabre, B.; Bandy, T.; Sarajlic, M.; Cabral, A.; Bovay, S.; Vallée, Ph.; Bouchy, F.; Doyon, R.; Artigau, E.; Pepe, F.; Hagelberg, J.; Melo, C.; Delfosse, X.; Figueira, P.; Santos, N. C.; González Hernández, J. I.; de Medeiros, J. R.; Rebolo, R.; Broeg, Ch.; Benz, W.; Boisse, I.; Malo, L.; Käufl, U.; Saddlemyer, L.

2017-09-01

Since 1st light in 2002, HARPS has been setting the standard in the exo-planet detection by radial velocity (RV) measurements[1]. Based on this experience, our consortium is developing a high accuracy near-infrared RV spectrograph covering YJH bands to detect and characterize low-mass planets in the habitable zone of M dwarfs. It will allow RV measurements at the 1-m/s level and will look for habitable planets around M- type stars by following up the candidates found by the upcoming space missions TESS, CHEOPS and later PLATO. NIRPS and HARPS, working simultaneously on the ESO 3.6m are bound to become a single powerful high-resolution, high-fidelity spectrograph covering from 0.4 to 1.8 micron. NIRPS will complement HARPS in validating earth-like planets found around G and K-type stars whose signal is at the same order of magnitude than the stellar noise. Because at equal resolving power the overall dimensions of a spectrograph vary linearly with the input beam étendue, spectrograph designed for seeing-limited observations are large and expensive. NIRPS will use a high order adaptive optics system to couple the starlight into a fiber corresponding to 0.4" on the sky as efficiently or better than HARPS or ESPRESSO couple the light 0.9" fiber. This allows the spectrograph to be very compact, more thermally stable and less costly. Using a custom tan(θ)=4 dispersion grating in combination with a start-of-the-art Hawaii4RG detector makes NIRPS very efficient with complete coverage of the YJH bands at 110'000 resolution. NIRPS works in a regime that is in-between the usual multi-mode (MM) where 1000's of modes propagates in the fiber and the single mode well suited for perfect optical systems. This regime called few-modes regime is prone to modal noise- Results from a significant R and D effort made to characterize and circumvent the modal noise show that this contribution to the performance budget shall not preclude the RV performance to be achieved.

VizieR Online Data Catalog: The AllWISE motion survey (AllWISE2) (Kirkpatrick+, 2016)

NASA Astrophysics Data System (ADS)

Kirkpatrick, J. D.; Kellogg, K.; Schneider, A. C.; Fajardo-Acosta, S.; Cushing, M. C.; Greco, J.; Mace, G. N.; Gelino, C. R.; Wright, E. L.; Eisenhardt, P. R. M.; Stern, D.; Faherty, J. K.; Sheppard, S. S.; Lansbury, G. B.; Logsdon, S. E.; Martin, E. C.; McLean, I. S.; Schurr, S. D.; Cutri, R. M.; Conrow, T.

2016-07-01

Observations for the spectroscopic follow-up of interesting AllWISE sources are listed in Table 4. Optical follow-up was conducted with the Palomar/Double Spectrograph on the Hale 5m telescope on Palomar Mountain, California, as our primary optical spectrograph in the northern hemisphere. It was used during the UT nights of 2014 January 26, February 23/24, April 22, June 25/26, July 21, September 27, October 24, and November 15 as well as 2015 June 08, September 07, and December 10. The Boller & Chivens Spectrograph (BCSpec) on the 2.5m Irenee duPont telescope at Las Campanas Observatory, Chile, served as our primary optical spectrograph in the southern hemisphere and was used on the UT nights of 2014 April 30, May 01-04, and November 16-20. Spectra of 10 objects were obtained on the UT nights of 2014 July 03-04 and 2015 December 07-10 at the European Southern Observatory (ESO) 3.58m New Technology Telescope (NTT) at La Silla, Chile. Spectra of seven objects were obtained on the UT nights of 2014 June 26, 2015 August 13, and 2015 December 05 with the Low Resolution Imaging Spectrometer (LRIS) at the 10m W. M. Keck Observatory on Mauna Kea, Hawaii. SpeX on the NASA 3m Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, served as our primary near-infrared spectrograph in the northern hemisphere. The UT dates of observation were 2014 November 11 and 2015 January 27, May 08-09, June 27, July 03-05, and July 20. The Folded-port Infrared Echellette (FIRE) at the 6.5m Walter Baade Telescope at Las Campanas Observatory, Chile, served as our primary near-infrared spectrograph in the southern hemisphere. The UT dates of observation were 2014 August 07-09, 2015 February 08, and 2015 May 31. Several sources were also observed with the Near-Infrared Spectrometer (NIRSPEC) at the 10m W. M. Keck Observatory on Mauna Kea, Hawaii. The observation dates were UT 2014 April 12 and December 03, and 2015 July 03 and July 11. (9 data files).

Optical trapping forces of a focused azimuthally polarized Bessel-Gaussian beam on a double-layered sphere

NASA Astrophysics Data System (ADS)

Wu, F. P.; Zhang, B.; Liu, Z. L.; Tang, Y.; Zhang, N.

2017-12-01

We calculate the trapping forces exerted by a highly focused Bessel-Gaussian beam on a double-layered sphere by means of vector diffraction integral, T-matrix method and Maxwell stress tensor integral. The Bessel-Gaussian beam is azimuthally polarized. Numerical results predicate that the double-layered sphere with air core can be stably trapped in three-dimensions. The trapping forces and efficiencies are dependent on the refraction index and size of the inner core. The trapping efficiency can be optimized by choosing the refraction indices of the inner core and outer layer. Our computational method can be easily modified for other laser beams and particles with arbitrary geometries and multilayers.

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 present a theoretical expression and numerical simulation results for the full-width-at-half-maximum of SRS imaging point spread function, assuming that the pump and Stokes beam profiles are Gaussian and the second Stokes beam has a doughnut-shaped spatial profile. It is clear that the spatial resolution with the present 3-beam cascading SRS method can be enhanced well beyond the diffraction limit. We anticipate that the present work will provide a theoretical framework for a super-resolution stimulated Raman scattering microscopy that is currently under investigation.

VizieR Online Data Catalog: Space telescope RM project. V. NGC5548 sp. monitoring (Pei+, 2017)

NASA Astrophysics Data System (ADS)

Pei, L.; Fausnaugh, M. M.; Barth, A. J.; Peterson, B. M.; Bentz, M. C.; De Rosa, G.; Denney, K. D.; Goad, M. R.; Kochanek, C. S.; Korista, K. T.; Kriss, G. A.; Pogge, R. W.; Bennert, V. N.; Brotherton, M.; Clubb, K. I.; Dalla Bonta, E.; Filippenko, A. V.; Greene, J. E.; Grier, C. J.; Vestergaard, M.; Zheng, W.; Adams, S. M.; Beatty, T. G.; Bigley, A.; Brown, J. E.; Brown, J. S.; Canalizo, G.; Comerford, J. M.; Coker, C. T.; Corsini, E. M.; Croft, S.; Croxall, K. V.; Deason, A. J.; Eracleous, M.; Fox, O. D.; Gates, E. L.; Henderson, C. B.; Holmbeck, E.; Holoien, T. W.-S.; Jensen, J. J.; Johnson, C. A.; Kelly, P. L.; Kim, S.; King, A.; Lau, M. W.; Li, M.; Lochhaas, C.; Ma, Z.; Manne-Nicholas, E. R.; Mauerhan, J. C.; Malkan, M. A.; McGurk, R.; Morelli, L.; Mosquera, A.; Mudd, D.; Sanchez, F. M.; Nguyen, M. L.; Ochner, P.; Ou-Yang, B.; Pancoast, A.; Penny, M. T.; Pizzella, A.; Poleski, R.; Runnoe, J.; Scott, B.; Schimoia, J. S.; Shappee, B. J.; Shivvers, I.; Simonian, G. V.; Siviero, A.; Somers, G.; Stevens, D. J.; Strauss, M. A.; Tayar, J.; Tejos, N.; Treu, T.; van Saders, J.; Vican, L.; Villanueva, S.; Yuk, H.; Zakamska, N. L.; Zhu, W.; Anderson, M. D.; Arevalo, P.; Bazhaw, C.; Bisogni, S.; Borman, G. A.; Bottorff, M. C.; Brandt, W. N.; Breeveld, A. A.; Cackett, E. M.; Carini, M. T.; Crenshaw, D. M.; de Lorenzo-Caceres, A.; Dietrich, M.; Edelson, R.; Efimova, N. V.; Ely, J.; Evans, P. A.; Ferland, G. J.; Flatland, K.; Gehrels, N.; Geier, S.; Gelbord, J. M.; Grupe, D.; Gupta, A.; Hall, P. B.; Hicks, S.; Horenstein, D.; Horne, K.; Hutchison, T.; Im, M.; Joner, M. D.; Jones, J.; Kaastra, J.; Kaspi, S.; Kelly, B. C.; Kennea, J. A.; Kim, M.; Kim, S. C.; Klimanov, S. A.; Lee, J. C.; Leonard, D. C.; Lira, P.; Macinnis, F.; Mathur, S.; McHardy, I. M.; Montouri, C.; Musso, R.; Nazarov, S. V.; Netzer, H.; Norris, R. P.; Nousek, J. A.; Okhmat, D. N.; Papadakis, I.; Parks, J. R.; Pott, J.-U.; Rafter, S. E.; Rix, H.-W.; Saylor, D. A.; Schnulle, K.; Sergeev, S. G.; Siegel, M.; Skielboe, A.; Spencer, M.; Starkey, D.; Sung, H.-I.; Teems, K. G.; Turner, C. S.; Uttley, P.; Villforth, C.; Weiss, Y.; Woo, J.-H.; Yan, H.; Young, S.; Zu, Y.

2017-10-01

Spectroscopic data were obtained from five telescopes: the McGraw-Hill 1.3m telescope at the MDM Observatory (4225-5775Å; median S/N=118), the Shane 3m telescope at the Lick Observatory (Kast Double Spectrograph: 3250-7920Å; median S/N=194), the 1.22m Galileo telescope at the Asiago Astrophysical Observatory (3250-7920Å; median S/N=160), the 3.5m telescope at Apache Point Observatory (APO; Dual Imaging Spectrograph: 4180-5400Å, median S/N =160), and the 2.3m telescope at the Wyoming Infrared Observatory (WIRO; 5599-4399Å; median S/N=217). The optical spectroscopic monitoring targeting NGC 5548 began on 2014 January 4 and continued through 2014 July 6 with approximately daily cadence. MDM contributed the largest number of spectra with 143 epochs. (1 data file).

A flat array large telescope concept for use on the moon, earth, and in space

NASA Technical Reports Server (NTRS)

Woodgate, Bruce E.

1991-01-01

An astronomical optical telescope concept is described which can provide very large collecting areas, of order 1000 sq m. This is an order of magnitude larger than the new generation of telescopes now being designed and built. Multiple gimballed flat mirrors direct the beams from a celestial source into a single telescope of the same aperture as each flat mirror. Multiple images of the same source are formed at the telescope focal plane. A beam combiner collects these images and superimposes them into a single image, onto a detector or spectrograph aperture. This telescope could be used on the earth, the moon, or in space.

Focal-surface detector for heavy ions

DOEpatents

Erskine, John R.; Braid, Thomas H.; Stoltzfus, Joseph C.

1979-01-01

A detector of the properties of individual charged particles in a beam includes a gridded ionization chamber, a cathode, a plurality of resistive-wire proportional counters, a plurality of anode sections, and means for controlling the composition and pressure of gas in the chamber. Signals generated in response to the passage of charged particles can be processed to identify the energy of the particles, their loss of energy per unit distance in an absorber, and their angle of incidence. In conjunction with a magnetic spectrograph, the signals can be used to identify particles and their state of charge. The detector is especially useful for analyzing beams of heavy ions, defined as ions of atomic mass greater than 10 atomic mass units.

High performance Si immersion gratings patterned with electron beam lithography

NASA Astrophysics Data System (ADS)

Gully-Santiago, Michael A.; Jaffe, Daniel T.; Brooks, Cynthia B.; Wilson, Daniel W.; Muller, Richard E.

2014-07-01

Infrared spectrographs employing silicon immersion gratings can be significantly more compact than spectro- graphs using front-surface gratings. The Si gratings can also offer continuous wavelength coverage at high spectral resolution. The grooves in Si gratings are made with semiconductor lithography techniques, to date almost entirely using contact mask photolithography. Planned near-infrared astronomical spectrographs require either finer groove pitches or higher positional accuracy than standard UV contact mask photolithography can reach. A collaboration between the University of Texas at Austin Silicon Diffractive Optics Group and the Jet Propulsion Laboratory Microdevices Laboratory has experimented with direct writing silicon immersion grating grooves with electron beam lithography. The patterning process involves depositing positive e-beam resist on 1 to 30 mm thick, 100 mm diameter monolithic crystalline silicon substrates. We then use the facility JEOL 9300FS e-beam writer at JPL to produce the linear pattern that defines the gratings. There are three key challenges to produce high-performance e-beam written silicon immersion gratings. (1) E- beam field and subfield stitching boundaries cause periodic cross-hatch structures along the grating grooves. The structures manifest themselves as spectral and spatial dimension ghosts in the diffraction limited point spread function (PSF) of the diffraction grating. In this paper, we show that the effects of e-beam field boundaries must be mitigated. We have significantly reduced ghost power with only minor increases in write time by using four or more field sizes of less than 500 μm. (2) The finite e-beam stage drift and run-out error cause large-scale structure in the wavefront error. We deal with this problem by applying a mark detection loop to check for and correct out minuscule stage drifts. We measure the level and direction of stage drift and show that mark detection reduces peak-to-valley wavefront error by a factor of 5. (3) The serial write process for typical gratings yields write times of about 24 hours- this makes prototyping costly. We discuss work with negative e-beam resist to reduce the fill factor of exposure, and therefore limit the exposure time. We also discuss the tradeoffs of long write-time serial write processes like e-beam with UV photomask lithography. We show the results of experiments on small pattern size prototypes on silicon wafers. Current prototypes now exceed 30 dB of suppression on spectral and spatial dimension ghosts compared to monochromatic spectral purity measurements of the backside of Si echelle gratings in reflection at 632 nm. We perform interferometry at 632 nm in reflection with a 25 mm circular beam on a grating with a blaze angle of 71.6°. The measured wavefront error is 0.09 waves peak to valley.

Investigating the Lyman photon escape in local starburst galaxies with the Cosmic Origins Spectrograph ★

NASA Astrophysics Data System (ADS)

Hernandez, Svea; Leitherer, Claus; Boquien, Médéric; Buat, Véronique; Burgarella, Denis; Calzetti, Daniela; Noll, Stefan

2018-04-01

We present a study of 7 star-forming galaxies from the Cosmic Evolution Survey (COSMOS) observed with the Cosmic Origins Spectrograph (COS) on board the Hubble Space Telescope (HST). The galaxies are located at relatively low redshifts, z ˜0.3, with morphologies ranging from extended and disturbed to compact and smooth. To complement the HST observations we also analyze observations taken with the VIMOS spectrograph on the Very Large Telescope (VLT). In our galaxy sample we identify three objects with double peak Lyman-α profiles similar to those seen in Green Pea compact galaxies and measure peak separations of 655, 374, and 275 km s-1. We measure Lyman-α escape fractions with values ranging between 5-13%. Given the low flux levels in the individual COS exposures we apply a weighted stacking approach to obtain a single spectrum. From this COS combined spectrum we infer upper limits for the absolute and relative Lyman continuum escape fractions of f_abs(LyC) = 0.4^{+10.1}_{-0.4}% and f_res(LyC) = 1.7^{+15.2}_{-1.7}%, respectively. Finally, we find that most of these galaxies have moderate UV and optical SFRs (SFRs ≲ 10 M⊙ yr-1).

Investigating the Lyman photon escape in local starburst galaxies with the Cosmic Origins Spectrograph

NASA Astrophysics Data System (ADS)

Hernandez, Svea; Leitherer, Claus; Boquien, Médéric; Buat, Véronique; Burgarella, Denis; Calzetti, Daniela; Noll, Stefan

2018-07-01

We present a study of seven star-forming galaxies from the Cosmic Evolution Survey observed with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST). The galaxies are located at relatively low redshifts, z ˜ 0.3, with morphologies ranging from extended and disturbed to compact and smooth. To complement the HST observations, we also analyse observations taken with the Visible Multi-object Spectrograph (VIMOS) on the Very Large Telescope (VLT). In our galaxy sample, we identify three objects with double peak Lyman-α profiles similar to those seen in Green Pea compact galaxies and measure peak separations of 655, 374, and 275 km s-1. We measure Lyman-α escape fractions with values ranging between 5 per cent and 13 per cent. Given the low flux levels in the individual COS exposures, we apply a weighted stacking approach to obtain a single spectrum. From this COS combined spectrum, we infer upper limits for the absolute and relative Lyman continuum escape fractions of f_abs(LyC) = 0.4^{+10.1}_{-0.4} per cent and f_res(LyC) = 1.7^{+15.2}_{-1.7}per cent, respectively. Finally, we find that most of these galaxies have moderate ultraviolet and optical star formation rates (SFRs) (SFRs ≲10 M⊙ yr-1).

VizieR Online Data Catalog: RV of candidate hybrid variable stars (Lampens+, 2018)

NASA Astrophysics Data System (ADS)

Lampens, P.; Fremat, Y.; Vermeylen, L.; Sodor, A.; Skarka, M.; De Cat, P.; Bognar, Zs.; de Nutte, R.; Dumortier, L.; Escorza, A.; Oomen, G. M.; van de Steene, G.; Kamath, D.; Laverick, M.; Samadi, A.; Triana, S.; Lehmann, H.

2017-09-01

We present the individual radial velocity measurements of 50 candidate delta Scuti - gamma Doradus hybrid stars and one delta Scuti star from the Kepler mission collected with the Hermes and Ace spectrographs over a time span of months to years. The radial velocities were measured using spectrum synthesis and a two-dimensional cross-correlation technique in the case of double- and triple-lined systems. (5 data files).

CARMENES science preparation: characterisation of M dwarfs with low-resolution spectroscopy and search for low-mass wide companions to young stars

NASA Astrophysics Data System (ADS)

Alonso-Floriano, F. J.

2015-11-01

This thesis is focused on the study of low-mass objects that can be targets of exoplanet searches with near-infrared spectrographs in general and CARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs; see Quirrenbach et al. 2014) in particular. The CARMENES consortium comprises 11 institutions from Germany and Spain that are building a high-resolution spectrograph (R=82,000) with two channels, visible (0.55 - 1.05 um) and infrared (0.95 - 1.7 um), for the 3.5 m Calar Alto telescope. It will observe a sample of 300 M dwarfs in 600 nights of guaranteed time during at least three years, starting in January 2016. The final sample will be chosen from the 2200 M dwarfs included in the CARMENCITA input catalogue. For these stars, we have obtained and collected a large amount of data: spectral types, radial and rotational velocities, photometry in several bands, etc. Part of the e effort of the science preparation necessary for the final selection of targets for CARMENES and other near-infrared spectrographs has been collected in two publications, which are presented in this PhD thesis. In the first publication (Alonso-Floriano et al., 2015A&A...577A.128A), we obtained low-resolution spectra for 753 stars using the CAFOS spectrograph at the 2.2 m Calar Alto telescope. The main goal was to derive accurate spectral types, which are fundamental parameters for the sample selection. We used a grid of 49 standard stars, from spectral types K3V to M8V, together with a double least-square minimisation technique and 31 spectral indices previously defined by other authors. In addition, we quantified the surface gravity, metallicity and chromospheric activity of the sample, in order to detect low-gravity stars (giants and very young), metal-poor and very metal-poor stars (subdwarfs), and very active stars. In the second publication (Alonso-Floriano et al., 2015A&A...583A..85A), we searched for common proper motion companions, especially of low mass, to members of the near young beta Pictoris moving group. First, we compiled a list of 185 members and candidate members to beta Pictoris from 35 representatives studies on this moving group. Next, we used the Aladin and STILTS virtual observatory tools, as well as the PPMXL proper motion and Washington double stars catalogues. The objects that showed similar proper motions to those stars of the sample were targets of an astro-photometric follow-up. The 36 common proper motion companion eventually obtained were subjects of a study of binding energies to determine their physical ligation.

Stress-induced waveguides in Nd:YAG by simultaneous double-beam irradiation with femtosecond pulses

NASA Astrophysics Data System (ADS)

Castillo, Gabriel R.; Romero, Carolina; Lifante, Ginés; Jaque, Daniel; Chen, Feng; Varela, Óscar; García-García, Enrique; Méndez, Cruz; Camacho-López, Santiago; Vázquez de Aldana, Javier R.

2016-01-01

We report on the fabrication of stress-induced waveguides in Nd:YAG (neodymium doped yttrium aluminum garnet, Nd:Y3Al5O12) by simultaneous double-beam irradiation with femtosecond laser pulses. An interferometer was used to generate two femtosecond laser beams that, focused with certain lateral separation inside the crystal, produced two parallel damage tracks with a single scan. The propagation of the mechanical waves simultaneously created in both focal spots produced a highly symmetrical stress field that is clearly revealed in micro-luminescence maps. The optical properties of the double-beam waveguides are studied and compared to those of single-beam irradiation, showing relevant differences. The creation of more symmetric stress patterns and a slight reduction of propagation losses are explained in terms of the fact that simultaneous inscription allows for a drastic reduction in the magnitude of "incubation" effects related to the existence of pre-damaged states.

Ultra-Compact, Superconducting Spectrometer-on-a-Chip at Submillimeter Wavelengths

NASA Technical Reports Server (NTRS)

Chattopadhyay, Goutam; Zmuidzinas, Jonas; Bradford, Charles M.; Leduc, Henry G.; Day, Peter K.; Swenson, Loren; Hailey-Dunsheath, Steven; O'Brient, Roger C.; Padin, Stephen; Shirokoff, Erik D.;

The First Light of the Subaru Laser Guide Star Adaptive Optics System

NASA Astrophysics Data System (ADS)

Takami, H.; Hayano, Y.; Oya, S.; Hattori, M.; Watanabe, M.; Guyon, O.; Eldred, M.; Colley, S.; Saito, Y.; Itoh, M.; Dinkins, M.

Subaru Telescope has been operating 36 element curvature sensor AO system for the Cassegrain focus since 2000. We have developed a new AO system for the Nasmyth focus. The AO system has 188 element curvature wavefront sensor and bimorph deformable mirror. It is the largest format system for this type of sensor . The deformable mirror has also 188 element with 90 mm effective aperture and 130 mm blank size. The real time controller is 4 CPU real time Linux OS computer and the update speed is now 1.5 kHz. The AO system also has laser guide star system. The laser is sum frequency solid state laser generating 589 nm light. We have achieved 4.7 W output power with excellent beam quality of M^2=1.1 and good stability. The laser is installed in a clean room on the Nasmyth platform. The laser beam is transferred by photonic crystal optical fiber with 35 m to the 50 cm laser launching telescope mounted behind the Subaru 2ry mirror. The field of view of the low order wavefront sensor for tilt guide star in LGS mode is 2.7 arcmin in diameter. The AO system had the first light with natural guide star in October 2006. The Strehl ratio was > 0.5 at K band under the 0.8 arcsec visible seeing. We also has projected laser beam on the sky during the same engineering run. Three instruments will be used with the AO system. Infrared camera and spectrograph (IRCS), High dynamic range IR camera (HiCIAO) for exosolar planet detection, and visible 3D spectrograph.

The nature of pulsar radio emission

NASA Astrophysics Data System (ADS)

Dyks, J.; Rudak, B.; Demorest, P.

2010-01-01

High-quality averaged radio profiles of some pulsars exhibit double, highly symmetric features both in emission and in absorption. It is shown that both types of feature are produced by a split fan beam of extraordinary-mode curvature radiation that is emitted/absorbed by radially extended streams of magnetospheric plasma. With no emissivity in the plane of the stream, such a beam produces bifurcated emission components (BFCs) when our line of sight passes through the plane. An example of a double component created in this way is present in the averaged profile of the 5-ms pulsar J1012+5307. We show that the component can indeed be very well fitted by the textbook formula for the non-coherent beam of curvature radiation in the polarization state that is orthogonal to the plane of electron trajectory. The observed width of the BFC decreases with increasing frequency at a rate that confirms the curvature origin. Likewise, the double absorption features (double notches) are produced by the same beam of the extraordinary-mode curvature radiation, when it is eclipsed by thin plasma streams. The intrinsic property of curvature radiation to create bifurcated fan beams explains the double features in terms of a very natural geometry and implies the curvature origin of pulsar radio emission. Similarly, the `double conal' profiles of class D result from a cut through a wider stream with finite extent in magnetic azimuth. Therefore, their width reacts very slowly to changes of viewing geometry resulting from geodetic precession. The stream-cut interpretation implies a highly non-orthodox origin of both the famous S-swing of polarization angle and the low-frequency pulse broadening in D profiles. The azimuthal structure of polarization modes in the curvature radiation beam provides an explanation for the polarized `multiple imaging' and the edge depolarization of pulsar profiles.

11. Corner of Derrick Showing Bolted Joints and DoublePipe/Wood Beam ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

11. Corner of Derrick Showing Bolted Joints and Double-Pipe/Wood Beam Support For Bull Wheel, Looking Southeast - David Renfrew Oil Rig, East side of Connoquenessing Creek, 0.4 mile North of confluence with Thorn Creek, Renfrew, Butler County, PA

Double Layers in Astrophysics

NASA Technical Reports Server (NTRS)

Williams, Alton C. (Editor); Moorehead, Tauna W. (Editor)

1987-01-01

Topics addressed include: laboratory double layers; ion-acoustic double layers; pumping potential wells; ion phase-space vortices; weak double layers; electric fields and double layers in plasmas; auroral double layers; double layer formation in a plasma; beamed emission from gamma-ray burst source; double layers and extragalactic jets; and electric potential between plasma sheet clouds.

The re-flight of the Colorado high-resolution Echelle stellar spectrograph (CHESS): improvements, calibrations, and post-flight results

NASA Astrophysics Data System (ADS)

Hoadley, Keri; France, Kevin; Kruczek, Nicholas; Fleming, Brian; Nell, Nicholas; Kane, Robert; Swanson, Jack; Green, James; Erickson, Nicholas; Wilson, Jacob

2016-07-01

In this proceeding, we describe the scientific motivation and technical development of the Colorado High- resolution Echelle Stellar Spectrograph (CHESS), focusing on the hardware advancements and testing supporting the second flight of the payload (CHESS-2). CHESS is a far ultraviolet (FUV) rocket-borne instrument designed to study the atomic-to-molecular transitions within translucent cloud regions in the interstellar medium (ISM). CHESS is an objective f/12.4 echelle spectrograph with resolving power > 100,000 over the band pass 1000 - 1600 Å. The spectrograph was designed to employ an R2 echelle grating with "low" line density. We compare the FUV performance of experimental echelle etching processes (lithographically by LightSmyth, Inc. and etching via electron-beam technology by JPL Microdevices Laboratory) with traditional, mechanically-ruled gratings (Bach Research, Inc. and Richardson Gratings). The cross-dispersing grating, developed and ruled by Horiba Jobin-Yvon, is a holographically-ruled, "low" line density, powered optic with a toroidal surface curvature. Both gratings were coated with aluminum and lithium fluoride (Al+LiF) at Goddard Space Flight Center (GSFC). Results from final efficiency and reflectivity measurements for the optical components of CHESS-2 are presented. CHESS-2 utilizes a 40mm-diameter cross-strip anode readout microchannel plate (MCP) detector fabricated by Sensor Sciences, Inc., to achieve high spatial resolution with high count rate capabilities (global rates 1 MHz). We present pre-flight laboratory spectra and calibration results. CHESS-2 launched on 21 February 2016 aboard NASA/CU sounding rocket mission 36.297 UG. We observed the intervening ISM material along the sightline to epsilon Per and present initial characterization of the column densities, temperature, and kinematics of atomic and molecular species in the observation.

Simultaneous observation of rotational coherent Stokes Raman scattering and coherent anti-Stokes Raman scattering in air and nitrogen

NASA Technical Reports Server (NTRS)

Snow, J. B.; Chang, R. K.; Zheng, J. B.; Leipertz, A.

1983-01-01

Rotational coherent Stokes Raman scattering (CSRS) and coherent anti-Stokes Raman scattering (CARS) in air and in nitrogen were observed simultaneously by using broadband generation and detection. In the broadband technique used, the entire CARS and CSRS spectrum was generated in a single laser pulse; the CSRS and CARS signals were dispersed by a spectrograph and detected simultaneously by an optical multichannel analyzer. A three-dimensional phase-matching geometry was used to achieve spatial resolution of the CSRS and CARS beams from the input beams. Under resonant conditions, similar experiments may provide a means of investigating the possible interaction between the CSRS and CARS processes in driving the rotational levels.

New high-precision orbital and physical parameters of the double-lined low-mass spectroscopic binary BY Draconis

NASA Astrophysics Data System (ADS)

Hełminiak, K. G.; Konacki, M.; Muterspaugh, M. W.; Browne, S. E.; Howard, A. W.; Kulkarni, S. R.

2012-01-01

We present the most precise to date orbital and physical parameters of the well-known short period (P= 5.975 d), eccentric (e= 0.3) double-lined spectroscopic binary BY Draconis (BY Dra), a prototype of a class of late-type, active, spotted flare stars. We calculate the full spectroscopic/astrometric orbital solution by combining our precise radial velocities (RVs) and the archival astrometric measurements from the Palomar Testbed Interferometer (PTI). The RVs were derived based on the high-resolution echelle spectra taken between 2004 and 2008 with the Keck I/high-resolution echelle spectrograph, Shane/CAT/HamSpec and TNG/SARG telescopes/spectrographs using our novel iodine-cell technique for double-lined binary stars. The RVs and available PTI astrometric data spanning over eight years allow us to reach 0.2-0.5 per cent level of precision in Msin 3i and the parallax but the geometry of the orbit (i≃ 154°) hampers the absolute mass precision to 3.3 per cent, which is still an order of magnitude better than for previous studies. We compare our results with a set of Yonsei-Yale theoretical stellar isochrones and conclude that BY Dra is probably a main-sequence system more metal rich than the Sun. Using the orbital inclination and the available rotational velocities of the components, we also conclude that the rotational axes of the components are likely misaligned with the orbital angular momentum. Given BY Dra's main-sequence status, late spectral type and the relatively short orbital period, its high orbital eccentricity and probable spin-orbit misalignment are not in agreement with the tidal theory. This disagreement may possibly be explained by smaller rotational velocities of the components and the presence of a substellar mass companion to BY Dra AB.

VizieR Online Data Catalog: PTF 12dam & iPTF 13dcc follow-up (Vreeswijk+, 2017)

NASA Astrophysics Data System (ADS)

Vreeswijk, P. M.; Leloudas, G.; Gal-Yam, A.; De Cia, A.; Perley, D. A.; Quimby, R. M.; Waldman, R.; Sullivan, M.; Yan, L.; Ofek, E. O.; Fremling, C.; Taddia, F.; Sollerman, J.; Valenti, S.; Arcavi, I.; Howell, D. A.; Filippenko, A. V.; Cenko, S. B.; Yaron, O.; Kasliwal, M. M.; Cao, Y.; Ben-Ami, S.; Horesh, A.; Rubin, A.; Lunnan, R.; Nugent, P. E.; Laher, R.; Rebbapragada, U. D.; Wozniak, P.; Kulkarni, S. R.

2017-08-01

Spectroscopic follow-up observations of PTF 12dam were performed with the Kast Spectrograph at the Lick 3m Shane telescope, and the Low Resolution Imaging Spectrograph (LRIS) at the Keck-I 10m telescope (on Mauna Kea, Hawaii) on 2012 May 20, 21, and 22. The full spectroscopic sequence of PTF 12dam will be presented by R. M. Quimby et al. (2016, in preparation). PTF 12dam was imaged with the Palomar Oschin 48 inch (P48) (i)PTF survey telescope in the Mould R filter, the Palomar 60 inch (P60) and CCD camera in Johnson B and Sloan Digital Sky Survey (SDSS) gri, the Las Cumbres Observatory Global Telescope Network (LCOGT) in SDSS r, and LRIS mounted on the 10m Keck-I telescope in Rs. iPTF 13dcc has not had any exposure in the literature yet. It was flagged as a transient source on 2013 August 29. Spectroscopic follow-up observations spanning 2013 Nov 26 to 2014 Jan 16 were performed with the Double Spectrograph (DBSP) at the Palomar 200 inch (P200), LRIS at Keck-I, and the Inamori-Magellan Areal Camera & Spectrograph (IMACS) at the Magellan Baade telescope, showing iPTF 13dcc to be an SLSN at z=0.4305. iPTF 13dcc was imaged with the P48 Oschin (i)PTF survey telescope in the Mould R filter, the P60 in SDSS gri, the 4.3m Discovery Channel Telescope (DCT, at Lowell Observatory, Arizona) with the Large Monolithic Imager (LMI) in SDSS ri, and finally with the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Wide-Field Camera using filter F625W (under program GO-13858; P.I. A. De Cia). (3 data files).

SU-F-T-338: Flattening Filter Free Photon Beams Can Achieve the Same Plan Quality as Conventional Flattened Beams for Prostate Radiotherapy

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

Kolar, M; Szwedowski, R; Greskovich, J

Purpose: Some modern linear accelerators are equipped with one low energy flat beam and two flattening filter free (FFF) beams at high and low energies. The purpose of this study is to investigate whether the high energy FFF beam can produce the same plan quality as the conventional low energy flat beam, using a volumetric modulated arc (VMAT) technique for prostate patients. Methods: Ten prostate cancer patients were selected with a prescription of 78Gy. For each patient, three plans were created: (a) double arc flat 6MV plan used clinically; (b) double arc 10MV FFF plan; (c) single arc 10MV FFFmore » plan. Each plan was prescribed so that at least 95% of the PTV received the prescription dose. The following dosimetric endpoints were evaluated: volume receiving 78Gy (V78) of the CTV and PTV, PTV conformality index (CI, ratio of prescription isodose volume to the PTV volume), bladder volume receiving 70Gy (V70) and 60Gy (V60), rectum volume receiving 70Gy (V70) and 50Gy (V50), dose to 10cc of the rectum, and volume of both femoral heads receiving 50Gy (V50). Total monitor units for each plan were recorded. Results: No significant difference was found for all dosimetric endpoints between all plans (p>0.05). Compared to the 6MV plans, monitor units were higher with the double arc 10MV FFF plans and lower with the single arc 10MV FFF plans, 29% and 4% respectively. Conclusion: Both single arc and double arc 10MV FFF VMAT can achieve equivalent plan quality as 6MV flat beam double arc treatment plans. With the gantry speed restriction, a high dose rate of 2400MU/min may allow the optimizer to use more MUs than actually needed. Single arc 10MV FFF VMAT plans are a reasonable alternative to double arc 6MV flat beam VMAT plans.« less

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.

Autogenerator of beams of charged particles

DOEpatents

Adler, Richard J.; Mazarakis, Michael G.; Miller, Robert B.; Shope, Steven L.; Smith, David L.

1986-01-01

An autogenerating apparatus provides secondary intense relativistic current beam pulses in response to an injected beam pulse. One or more electromagnetic energy storage devices are provided in conjunction with gaps along a beam propagation path for the injected beam pulse. For injected beam pulses which are no longer than double the transit time of electromagnetic waves within the storage devices (which may be resonant cavities), distinct secondary beam pulses are generated by each of the energy storage devices. The beam propagation path, together with the one or more gaps provided therein, operates as a pulse forming transmission line cavity, in which the separate cavities associated with the gaps provide delays for electromagnetic waves generated at the gaps. After doubly traversing the cavity, the electromagnetic waves cause the gap to generate the secondary beam pulses, which are thus delayed by a time interval equal to the double transit time for the induced wave within the cavity.

Autogenerator of beams of charged particles

DOEpatents

Adler, R.J.; Mazarakis, M.G.; Miller, R.M.; Shope, S.L.; Smith, D.L.

1983-10-31

An autogenerating apparatus provides secondary intense relativistic current beam pulses in response to an injected beam pulse. One or more electromagnetic energy storage devices are provided in conjunction with gaps along a beam propagation path for the injected beam pulse. For injected beam pulses which are no longer than double the transit time of electromagnetic waves within the storage devices (which may be resonant cavities), distinct secondary beam pulses are generated by each of the energy storage devices. The beam propagation path, together with the one or more gaps provided therein, operates as a pulse forming transmission line cavity, in which the separate cavities associated with the gaps provide delays for electromagnetic waves generated at the gaps. After doubly traversing the cavity, the electromagnetic waves cause the gap to generate the secondary beam pulses, which are thus delayed by a time interval equal to the double transit time for the induced wave within the cavity.

The Magneto-optical Filter, Working Principles and Recent Progress

NASA Technical Reports Server (NTRS)

Cacciani, A.; Rhodes, E. J., Jr.

1984-01-01

The Magneto-Optical Filter is described which allows simultaneous magnetic and velocity measurements (in both imaging and non-imaging modes) without the need for a spectrograph. In this way the stability and alignment problems of the spectrograph are completely overcome. Its major advantages are: wavelength absolute reference and stability, high signal to noise ratio and independence of the transmission profile from the incidence angle of the solar beam. It is an imaging instrument allowing high wave number analysis in the solar oscillation spectrum and a continuous monitoring of the image position through the chromospheric facular structures. The apparatus in use at Mt. Wilson is assembled in a modular form. The most important part of it is a glass cell containing the sodium vapor. The filter is easy to use but the cell is not easy to construct in an optimal way. The technology is in progress both to use Na and K together and to prevent the windows from becoming coated during a long-term operation.

Calibrating the SNfactory Integral Field Spectrograph (SNIFS) with SCALA

NASA Astrophysics Data System (ADS)

Küsters, Daniel; Lombardo, Simona; Kowalski, Marek; Aldering, Greg; Nordin, Jakob; Rigault, Mickael

2016-08-01

The SNIFS CALibration Apparatus (SCALA), a device to calibrate the Supernova Integral Field Spectrograph on the University Hawaii 2.2m telescope, was developed and installed in Spring 2014. SCALA produces an artificial planet with a diameter of 1° and a constant surface brightness. The wavelength of the beam can be tuned between 3200 Å and 10000 Å and has a bandwidth of 35 Å. The amount of light injected into the telescope is monitored with NIST calibrated photodiodes. SCALA was upgraded in 2015 with a mask installed at the entrance pupil of the UH88 telescope, ensuring that the illumination of the telescope by stars is similar to that of SCALA. With this setup, a first calibration run was performed in conjunction with the spectrophotometric observations of standard stars. We present first estimates for the expected systematic uncertainties of the in-situ calibration and discuss the results of tests that examine the influence of stray light produced in the optics.

SpUpNIC (Spectrograph Upgrade: Newly Improved Cassegrain) on the South African Astronomical Observatory's 74-inch telescope

NASA Astrophysics Data System (ADS)

Crause, Lisa A.; Carter, Dave; Daniels, Alroy; Evans, Geoff; Fourie, Piet; Gilbank, David; Hendricks, Malcolm; Koorts, Willie; Lategan, Deon; Loubser, Egan; Mouries, Sharon; O'Connor, James E.; O'Donoghue, Darragh E.; Potter, Stephen; Sass, Craig; Sickafoose, Amanda A.; Stoffels, John; Swanevelder, Pieter; Titus, Keegan; van Gend, Carel; Visser, Martin; Worters, Hannah L.

2016-08-01

SpUpNIC (Spectrograph Upgrade: Newly Improved Cassegrain) is the extensively upgraded Cassegrain Spectrograph on the South African Astronomical Observatory's 74-inch (1.9-m) telescope. The inverse-Cassegrain collimator mirrors and woefully inefficient Maksutov-Cassegrain camera optics have been replaced, along with the CCD and SDSU controller. All moving mechanisms are now governed by a programmable logic controller, allowing remote configuration of the instrument via an intuitive new graphical user interface. The new collimator produces a larger beam to match the optically faster Folded-Schmidt camera design and nine surface-relief diffraction gratings offer various wavelength ranges and resolutions across the optical domain. The new camera optics (a fused silica Schmidt plate, a slotted fold flat and a spherically figured primary mirror, both Zerodur, and a fused silica field-flattener lens forming the cryostat window) reduce the camera's central obscuration to increase the instrument throughput. The physically larger and more sensitive CCD extends the available wavelength range; weak arc lines are now detectable down to 325 nm and the red end extends beyond one micron. A rear-of-slit viewing camera has streamlined the observing process by enabling accurate target placement on the slit and facilitating telescope focus optimisation. An interactive quick-look data reduction tool further enhances the user-friendliness of SpUpNI

Simulation and Optimization of an Astrophotonic Reformatter

NASA Astrophysics Data System (ADS)

Anagnos, Th; Harris, R. J.; Corrigan, M. K.; Reeves, A. P.; Townson, M. J.; MacLachlan, D. G.; Thomson, R. R.; Morris, T. J.; Schwab, C.; Quirrenbach, A.

2018-05-01

Image slicing is a powerful technique in astronomy. It allows the instrument designer to reduce the slit width of the spectrograph, increasing spectral resolving power whilst retaining throughput. Conventionally this is done using bulk optics, such as mirrors and prisms, however more recently astrophotonic components known as PLs and photonic reformatters have also been used. These devices reformat the MM input light from a telescope into SM outputs, which can then be re-arranged to suit the spectrograph. The PD is one such device, designed to reduce the dependence of spectrograph size on telescope aperture and eliminate modal noise. We simulate the PD, by optimising the throughput and geometrical design using Soapy and BeamProp. The simulated device shows a transmission between 8 and 20 %, depending upon the type of AO correction applied, matching the experimental results well. We also investigate our idealised model of the PD and show that the barycentre of the slit varies only slightly with time, meaning that the modal noise contribution is very low when compared to conventional fibre systems. We further optimise our model device for both higher throughput and reduced modal noise. This device improves throughput by 6.4 % and reduces the movement of the slit output by 50%, further improving stability. This shows the importance of properly simulating such devices, including atmospheric effects. Our work complements recent work in the field and is essential for optimising future photonic reformatters.

A method for generating double-ring-shaped vector beams

NASA Astrophysics Data System (ADS)

Huan, Chen; Xiao-Hui, Ling; Zhi-Hong, Chen; Qian-Guang, Li; Hao, Lv; Hua-Qing, Yu; Xu-Nong, Yi

2016-07-01

We propose a method for generating double-ring-shaped vector beams. A step phase introduced by a spatial light modulator (SLM) first makes the incident laser beam have a nodal cycle. This phase is dynamic in nature because it depends on the optical length. Then a Pancharatnam-Berry phase (PBP) optical element is used to manipulate the local polarization of the optical field by modulating the geometric phase. The experimental results show that this scheme can effectively create double-ring-shaped vector beams. It provides much greater flexibility to manipulate the phase and polarization by simultaneously modulating the dynamic and the geometric phases. Project supported by the National Natural Science Foundation of China (Grant No. 11547017), the Hubei Engineering University Research Foundation, China (Grant No. z2014001), and the Natural Science Foundation of Hubei Province, China (Grant No. 2014CFB578).

Overtaking collision effects in a cw double-pass proton linac

DOE PAGES

Tao, Yue; Qiang, Ji; Hwang, Kilean

2017-12-22

The recirculating superconducting proton linac has the advantage of reducing the number of cavities in the accelerator and the corresponding construction and operational costs. Beam dynamics simulations were done recently in a double-pass recirculating proton linac using a single proton beam bunch. For continuous wave (cw) operation, the high-energy proton bunch during the second pass through the linac will overtake and collide with the low-energy bunch during the first pass at a number of locations of the linac. These collisions might cause proton bunch emittance growth and beam quality degradation. Here, we study the collisional effects due to Coulomb space-chargemore » forces between the high-energy bunch and the low-energy bunch. Our results suggest that these effects on the proton beam quality would be small and might not cause significant emittance growth or beam blowup through the linac. A 10 mA, 500 MeV cw double-pass proton linac is feasible without using extra hardware for phase synchronization.« less

Overtaking collision effects in a cw double-pass proton linac

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

Tao, Yue; Qiang, Ji; Hwang, Kilean

The recirculating superconducting proton linac has the advantage of reducing the number of cavities in the accelerator and the corresponding construction and operational costs. Beam dynamics simulations were done recently in a double-pass recirculating proton linac using a single proton beam bunch. For continuous wave (cw) operation, the high-energy proton bunch during the second pass through the linac will overtake and collide with the low-energy bunch during the first pass at a number of locations of the linac. These collisions might cause proton bunch emittance growth and beam quality degradation. Here, we study the collisional effects due to Coulomb space-chargemore » forces between the high-energy bunch and the low-energy bunch. Our results suggest that these effects on the proton beam quality would be small and might not cause significant emittance growth or beam blowup through the linac. A 10 mA, 500 MeV cw double-pass proton linac is feasible without using extra hardware for phase synchronization.« less

Optimization of the Nonradiative Lifetime of Molecular-Beam-Epitaxy (MBE)-Grown Undoped GaAs/AlGaAs Double Heterostructures (DH)

DTIC Science & Technology

2013-09-01

Optimization of the Nonradiative Lifetime of Molecular- Beam-Epitaxy (MBE)-Grown Undoped GaAs/AlGaAs Double Heterostructures (DH) by P...it to the originator. Army Research Laboratory Adelphi, MD 20783-1197 ARL-TR-6660 September 2013 Optimization of the Nonradiative ...REPORT TYPE Final 3. DATES COVERED (From - To) FY2013 4. TITLE AND SUBTITLE Optimization of the Nonradiative Lifetime of Molecular-Beam-Epitaxy

Measurement of transverse emittance and coherence of double-gate field emitter array cathodes

PubMed Central

Tsujino, Soichiro; Das Kanungo, Prat; Monshipouri, Mahta; Lee, Chiwon; Miller, R.J. Dwayne

2016-01-01

Achieving small transverse beam emittance is important for high brightness cathodes for free electron lasers and electron diffraction and imaging experiments. Double-gate field emitter arrays with on-chip focussing electrode, operating with electrical switching or near infrared laser excitation, have been studied as cathodes that are competitive with photocathodes excited by ultraviolet lasers, but the experimental demonstration of the low emittance has been elusive. Here we demonstrate this for a field emitter array with an optimized double-gate structure by directly measuring the beam characteristics. Further we show the successful application of the double-gate field emitter array to observe the low-energy electron beam diffraction from suspended graphene in minimal setup. The observed low emittance and long coherence length are in good agreement with theory. These results demonstrate that our all-metal double-gate field emitters are highly promising for applications that demand extremely low-electron bunch-phase space volume and large transverse coherence. PMID:28008918

Measurement of transverse emittance and coherence of double-gate field emitter array cathodes

NASA Astrophysics Data System (ADS)

Tsujino, Soichiro; Das Kanungo, Prat; Monshipouri, Mahta; Lee, Chiwon; Miller, R. J. Dwayne

2016-12-01

Achieving small transverse beam emittance is important for high brightness cathodes for free electron lasers and electron diffraction and imaging experiments. Double-gate field emitter arrays with on-chip focussing electrode, operating with electrical switching or near infrared laser excitation, have been studied as cathodes that are competitive with photocathodes excited by ultraviolet lasers, but the experimental demonstration of the low emittance has been elusive. Here we demonstrate this for a field emitter array with an optimized double-gate structure by directly measuring the beam characteristics. Further we show the successful application of the double-gate field emitter array to observe the low-energy electron beam diffraction from suspended graphene in minimal setup. The observed low emittance and long coherence length are in good agreement with theory. These results demonstrate that our all-metal double-gate field emitters are highly promising for applications that demand extremely low-electron bunch-phase space volume and large transverse coherence.

Design of FHiRE: the Fiber High Resolution Echelle Spectrograph

NASA Astrophysics Data System (ADS)

Pierce, Michael J.; McLane, Jacob N.; Pilachowski, C. A.; Kobulnicky, Henry; Jang-Condell, Hannah

2018-01-01

The enormous success of the Kepler mission in the discovery of transiting exoplanets implies that the majority of stars have planetary systems. NASA's upcomming Transiting Exoplanet Survey Satellite (TESS) is designed to survey the brightest stars over the entire sky, systems that are accessible to spectroscopic follow-up with mid-sized telescopes. We have undertaken the development of a precision radial velocity spectrograph with the goal of providing ground-based suppoert for TESS. The instrument, known as FHiRE (Fiber High Resolution Echelle spectrograph), is being developed in collaboration with Indiana University and will deployed at the 2.3-meter telescope of the Wyoming InfraRed Observatory (WIRO). FHiRE features a traditional white pupil echelle design with R ~ 60,000 that is fed via two optical fibers from the telescope. Both the science fiber and a simultaneously sampled Thorium-Argon comparison fiber will make use of double mode scramblers. FHiRE itself will be housed within a vacuum enclosure in order to minimize any temperatue variations of the instrument and maximize its radial velocity precision. Together, these two features should enable FHiRE to reach a long-term velocity precision of < 1 m/s. We present the design of FHiRE and its expected performance. In a companion poster (Jang-Condell et al.) we will present the exoplanet science goals of the project.

3C 159 - a double emission-line radio galaxy

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

Tytler, D.; Browne, I.

1985-09-01

An optical identification for 3C 159 is reported with a 19-mag emission-line radio galaxy at z = 0.482. Photometric measurements show it to be unusually bright and blue. The emission lines are of exceptionally high luminosity, and are split into two components separated by 598 + or - 13 km/s and 3 kpc along the spectrograph slit. A VLA may show that one of the radio lobes has two hot spots with tails of emission leading to both. 21 references.

Simulation of plasma double-layer structures

NASA Technical Reports Server (NTRS)

Borovsky, J. E.; Joyce, G.

1982-01-01

Electrostatic plasma double layers are numerically simulated by means of a magnetized 2 1/2 dimensional particle in cell method. The investigation of planar double layers indicates that these one dimensional potential structures are susceptible to periodic disruption by instabilities in the low potential plasmas. Only a slight increase in the double layer thickness with an increase in its obliqueness to the magnetic field is observed. Weak magnetization results in the double layer electric field alignment of accelerated particles and strong magnetization results in their magnetic field alignment. The numerical simulations of spatially periodic two dimensional double layers also exhibit cyclical instability. A morphological invariance in two dimensional double layers with respect to the degree of magnetization implies that the potential structures scale with Debye lengths rather than with gyroradii. Electron beam excited electrostatic electron cyclotron waves and (ion beam driven) solitary waves are present in the plasmas adjacent to the double layers.

Construction of a Virginia short-span bridge with the Strongwell 36-inch double-web I-beam.

DOT National Transportation Integrated Search

2005-01-01

The Route 601 Bridge in Sugar Grove, VA, spans 39 ft over Dickey Creek. The bridge is the first to use the Strongwell 36-in-deep fiber-reinforced polymer (FRP) double-web beam (DWB) in a vehicular bridge superstructure. Construction of the new bridge...

Propagation of flat-topped multi-Gaussian beams through a double-lens system with apertures.

PubMed

Gao, Yanqi; Zhu, Baoqiang; Liu, Daizhong; Lin, Zunqi

2009-07-20

A general model for different apertures and flat-topped laser beams based on the multi-Gaussian function is developed. The general analytical expression for the propagation of a flat-topped beam through a general double-lens system with apertures is derived using the above model. Then, the propagation characteristics of the flat-topped beam through a spatial filter are investigated by using a simplified analytical expression. Based on the Fluence beam contrast and the Fill factor, the influences of a pinhole size on the propagation of the flat-topped multi-Gaussian beam (FMGB) through the spatial filter are illustrated. An analytical expression for the propagation of the FMGB through the spatial filter with a misaligned pinhole is presented, and the influences of the pinhole offset are evaluated.

Physics constraints on double-pulse LIA engineering

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

Ekdahl, Carl August Jr.

2015-05-20

The options for advanced-radiography double-pulse linear induction accelerators (LIA) under consideration naturally fall into three categories that differ by the number of cells required. Since the two major physics issues, beam breakup (BBU) and corkscrew, are also dependent on the number of cells, it may be useful for the decision process to review the engineering consequences of beam physics constraints for each class. The LIAs can be categorized three different ways, and this report compares the different categories based upon the physics of their beams.

Double passing the Kitt Peak 1-m Fourier transform spectrometer

NASA Technical Reports Server (NTRS)

Jennings, D. E.; Hubbard, R.; Brault, J. W.

1985-01-01

Attention is given to a simple technique for performing the conversion of the Kitt Peak 1-m Fourier transform spectrometer's dual input/output optical configuration to a double pass configuration that improves spectral resolution by a factor of 2. The modification is made by placing a flat mirror in the output beam from each cat's eye, retroreflecting the beams back through the cat's eyes to the first beam splitter. A single detector is placed at the second input port, which then becomes the instrument's output.

Fiber link design for the NASA-NSF extreme precision Doppler spectrograph concept "WISDOM"

NASA Astrophysics Data System (ADS)

Fżrész, Gábor; Pawluczyk, Rafal; Fournier, Paul; Simcoe, Robert; Woods, Deborah F.

2016-08-01

We describe the design of the fiber-optic coupling and light transfer system of the WISDOM (WIYN Spectrograph for DOppler Monitoring) instrument. As a next-generation Precision Radial Velocity (PRV) spectrometer, WISDOM incorporates lessons learned from HARPS about thermal, pressure, and gravity control, but also takes new measures to stabilize the spectrograph illumination, a subject that has been overlooked until recently. While fiber optic links provide more even illumination than a conventional slit, careful engineering of the interface is required to realize their full potential. Conventional round fiber core geometries have been used successfully in conjunction with optical double scramblers, but such systems still retain a memory of the input illumination that is visible in systems seeking sub-m/s PRV precision. Noncircular fibers, along with advanced optical scramblers, and careful optimization of the spectrograph optical system itself are therefore necessary to study Earth-sized planets. For WISDOM, we have developed such a state-of-the-art fiber link concept. Its design is driven primarily by PRV requirements, but it also manages to preserve high overall throughput. Light from the telescope is coupled into a set of six, 32 μm diameter octagonal core fibers, as high resolution is achieved via pupil slicing. The low-OH, step index, fused silica, FBPI-type fibers are custom designed for their numerical aperture that matches the convergence of the feeding beam and thus minimizes focal ratio degradation at the output. Given the demanding environment at the telescope the fiber end tips are mounted in a custom fused silica holder, providing a perfect thermal match. We used a novel process, chemically assisted photo etching, to manufacture this glass fiber holder. A single ball-lens scrambler is inserted into the 25m long fibers. Employing an anti-reflection (AR) coated, high index, cubic-zirconia ball lens the alignment of the scrambler components are straightforward, as the fiber end tips (also AR coated) by design touch the ball lens and thus eliminate spacing tolerances. A clever and simple opto-mechanical design and assembly process assures micron-level self-alignment, yielding a 87% throughput and a scrambling gain of >20,000. To mitigate modal noise the individual fibers then subsequently combined into a pair of rectangular fibers, providing a much larger modal area thanks to the 34x106 micron diameter. To minimize slit height, and thus better utilize detector area, the octagonal cores are brought very close together in this transition. The two outer fibers are side polished at one side, into a D-shaped cladding, while the central fiber has a dual side polish. These tapered, side-flattening operations are executed with precise alignment to the octagonal core. Thus the cores of the 3 fibers are brought together and aligned within few microns of each other before spliced onto the rectangular fiber. Overall throughput kept high and FRD at bay by careful management of fiber mounting, vacuum feed-through, application of efficient AR coatings, and implementation of thermal breaks that allow for independent expansion of the fibers and the protective tubing.

Development of the beam extraction synchronization system at the Fermilab Booster

NASA Astrophysics Data System (ADS)

Seiya, K.; Chaurize, S.; Drennan, C. C.; Pellico, W.; Sullivan, T.; Triplett, A. K.; Waller, A. M.

2015-11-01

The new beam extraction synchronization control system called "Magnetic Cogging" was developed at the Fermilab Booster and it replaces a system called "RF Cogging" as part of the Proton Improvement Plan (PIP).[1] The flux throughput goal for the PIP is 2.2×1017 protons per hour, which is double the present flux. The flux increase will be accomplished by doubling the number of beam cycles which, in turn, will double the beam loss in the Booster accelerator if nothing else is done. The Booster accelerates beam from 400 MeV to 8 GeV and extracts it to the Main Injector (MI) or Recycler Ring (RR). Cogging controls the beam extraction gap position which is created early in the Booster cycle and synchronizes the gap to the rising edge of the Booster extraction kicker and the MI/RR injection kicker. The RF Cogging system controls the gap position by changing only the radial position of the beam thus limiting the beam aperture and creating beam loss due to beam scraping. The Magnetic Cogging system controls the gap position with the magnetic field of the dipole correctors while the radial position feedback keeps the beam on a central orbit. Also with Magnetic Cogging the gap creation can occur earlier in the Booster cycle when the removed particles are at a lower energy. Thus Magnetic Cogging reduces the deposited energy of the lost particles (beam energy loss) and results in less beam loss activation. Energy loss was reduced by 40% by moving the gap creation energy from 700 MeV to 400 MeV when the Booster Cogging system was switched from RF Cogging to Magnetic Cogging in March 2015.

The National Superconducting Cyclotron Laboratory

NASA Astrophysics Data System (ADS)

Gelbke, C. Korad; Morrissey, D. J.; York, R. C.

1996-10-01

The National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University has constructed and operates two superconducting cyclotrons for research in nuclear science, accelerator and instrumental physics. The K500, the world's first superconducting cyclotron, was commissioned in 1982 and the K1200, the world's most powerful cyclotron, was commissioned in 1988. Heavy-ion beams across the entire periodic table produced in a pair of ECR ion sources and accelerated to energies on the order of 100 MeV/A are delivered to a modern and versatile complement of experimental apparatus, including the new S800 high-resolution superconducting magnetic spectrograph now undergoing initial testing. The diverse variety of beams are used for studies of the quantum-statistical properties of hot nuclei, the liquid-gas phase transition in nuclear matter, and for nuclear structure research, particularly with radioactive ion beams from the A1200 fragment separator. The NSCL provides radioactive nuclear beams out to the limits of stability on both the neutron-rich and the proton-rich sides of the valley of stability. The laboratory is also used for multi-disciplinary research in astrophysics, condensed matter physics, geophysics, medicine, and biology. The NSCL has recently proposed a major upgrade of its facility based on coupled operation of the two cyclotrons. The upgrade will provide large increases in beam intensities for radioactive beam production and increased energies of the heaviest beams.

Wave-vector and polarization dependence of conical refraction.

PubMed

Turpin, A; Loiko, Yu V; Kalkandjiev, T K; Tomizawa, H; Mompart, J

2013-02-25

We experimentally address the wave-vector and polarization dependence of the internal conical refraction phenomenon by demonstrating that an input light beam of elliptical transverse profile refracts into two beams after passing along one of the optic axes of a biaxial crystal, i.e. it exhibits double refraction instead of refracting conically. Such double refraction is investigated by the independent rotation of a linear polarizer and a cylindrical lens. Expressions to describe the position and the intensity pattern of the refracted beams are presented and applied to predict the intensity pattern for an axicon beam propagating along the optic axis of a biaxial crystal.

Simulations of the Mg II K and Ca II 8542 Lines From an Alfvén Wave-Heated Flare Chromosphere

NASA Technical Reports Server (NTRS)

Kerr, Graham S.; Fletcher, Lyndsay; Russell, Alexander J. B.; Allred, Joel C.

2016-01-01

We use radiation hydrodynamic simulations to examine two models of solar flare chromospheric heating: Alfven wave dissipation and electron beam collisional losses. Both mechanisms are capable of strong chromospheric heating, and we show that the distinctive atmospheric evolution in the mid-to-upper chromosphere results in Mg II k-line emission that should be observably different between wave-heated and beam-heated simulations. We also present Ca II 8542 A profiles that are formed slightly deeper in the chromosphere. The Mg II k-line profiles from our wave-heated simulation are quite different from those from a beam-heated model and are more consistent with Interface Region Imaging Spectrograph observations. The predicted differences between the Ca II 8542 A in the two models are small. We conclude that careful observational and theoretical study of lines formed in the mid-to-upper chromosphere holds genuine promise for distinguishing between competing models for chromospheric heating inflares.

Thomson scattering diagnostic on the Compact Toroidal Hybrid Experiment

NASA Astrophysics Data System (ADS)

Traverso, P. J.; Ennis, D. A.; Hartwell, G. J.; Kring, J. D.; Maurer, D. A.

2017-10-01

A Thomson scattering system is being commissioned for the non-axisymmetric plasmas of the Compact Toroidal Hybrid (CTH), a five-field period current-carrying torsatron. The system takes a single point measurement at the magnetic axis to both calibrate the two-color soft x-ray Te system and serve as an additional diagnostic for the V3FIT 3D equilibrium reconstruction code. A single point measurement will reduce the uncertainty in the reconstructed peak pressure by an order of magnitude for both current-carrying plasmas and future gyrotron-heated stellarator plasmas. The beam, generated by a frequency doubled Continuum 2 J, Nd:YAG laser, is passed vertically through an entrance Brewster window and a two-aperture optical baffle system to minimize stray light. Thomson scattered light is collected by two adjacent f/2 plano-convex condenser lenses and routed via a fiber bundle through a Holospec f/1.8 spectrograph. The red-shifted scattered light from 533-563 nm will be collected by an array of Hamamatsu H11706-40 PMTs. The system has been designed to measure plasmas with core Te of 100 to 200 eV and densities of 5 ×1018 to 5 ×1019 m-3. Stray light and calibration data for a single wavelength channel will be presented. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.

CARMENES instrument overview

NASA Astrophysics Data System (ADS)

Quirrenbach, A.; Amado, P. J.; Caballero, J. A.; Mundt, R.; Reiners, A.; Ribas, I.; Seifert, W.; Abril, M.; Aceituno, J.; Alonso-Floriano, F. J.; Ammler-von Eiff, M.; Antona Jiménez, R.; Anwand-Heerwart, H.; Azzaro, M.; Bauer, F.; Barrado, D.; Becerril, S.; Béjar, V. J. S.; Benítez, D.; Berdiñas, Z. M.; Cárdenas, M. C.; Casal, E.; Claret, A.; Colomé, J.; Cortés-Contreras, M.; Czesla, S.; Doellinger, M.; Dreizler, S.; Feiz, C.; Fernández, M.; Galadí, D.; Gálvez-Ortiz, M. C.; García-Piquer, A.; García-Vargas, M. L.; Garrido, R.; Gesa, L.; Gómez Galera, V.; González Álvarez, E.; González Hernández, J. I.; Grözinger, U.; Guàrdia, J.; Guenther, E. W.; de Guindos, E.; Gutiérrez-Soto, J.; Hagen, H.-J.; Hatzes, A. P.; Hauschildt, P. H.; Helmling, J.; Henning, T.; Hermann, D.; Hernández Castaño, L.; Herrero, E.; Hidalgo, D.; Holgado, G.; Huber, A.; Huber, K. F.; Jeffers, S.; Joergens, V.; de Juan, E.; Kehr, M.; Klein, R.; Kürster, M.; Lamert, A.; Lalitha, S.; Laun, W.; Lemke, U.; Lenzen, R.; López del Fresno, Mauro; López Martí, B.; López-Santiago, J.; Mall, U.; Mandel, H.; Martín, E. L.; Martín-Ruiz, S.; Martínez-Rodríguez, H.; Marvin, C. J.; Mathar, R. J.; Mirabet, E.; Montes, D.; Morales Muñoz, R.; Moya, A.; Naranjo, V.; Ofir, A.; Oreiro, R.; Pallé, E.; Panduro, J.; Passegger, V.-M.; Pérez-Calpena, A.; Pérez Medialdea, D.; Perger, M.; Pluto, M.; Ramón, A.; Rebolo, R.; Redondo, P.; Reffert, S.; Reinhardt, S.; Rhode, P.; Rix, H.-W.; Rodler, F.; Rodríguez, E.; Rodríguez-López, C.; Rodríguez-Pérez, E.; Rohloff, R.-R.; Rosich, A.; Sánchez-Blanco, E.; Sánchez Carrasco, M. A.; Sanz-Forcada, J.; Sarmiento, L. F.; Schäfer, S.; Schiller, J.; Schmidt, C.; Schmitt, J. H. M. M.; Solano, E.; Stahl, O.; Storz, C.; Stürmer, J.; Suárez, J. C.; Ulbrich, R. G.; Veredas, G.; Wagner, K.; Winkler, J.; Zapatero Osorio, M. R.; Zechmeister, M.; Abellán de Paco, F. J.; Anglada-Escudé, G.; del Burgo, C.; Klutsch, A.; Lizon, J. L.; López-Morales, M.; Morales, J. C.; Perryman, M. A. C.; Tulloch, S. M.; Xu, W.

2014-07-01

This paper gives an overview of the CARMENES instrument and of the survey that will be carried out with it during the first years of operation. CARMENES (Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Echelle Spectrographs) is a next-generation radial-velocity instrument under construction for the 3.5m telescope at the Calar Alto Observatory by a consortium of eleven Spanish and German institutions. The scientific goal of the project is conducting a 600-night exoplanet survey targeting ~ 300 M dwarfs with the completed instrument. The CARMENES instrument consists of two separate echelle spectrographs covering the wavelength range from 0.55 to 1.7 μm at a spectral resolution of R = 82,000, fed by fibers from the Cassegrain focus of the telescope. The spectrographs are housed in vacuum tanks providing the temperature-stabilized environments necessary to enable a 1 m/s radial velocity precision employing a simultaneous calibration with an emission-line lamp or with a Fabry-Perot etalon. For mid-M to late-M spectral types, the wavelength range around 1.0 μm (Y band) is the most important wavelength region for radial velocity work. Therefore, the efficiency of CARMENES has been optimized in this range. The CARMENES instrument consists of two spectrographs, one equipped with a 4k x 4k pixel CCD for the range 0.55 - 1.05 μm, and one with two 2k x 2k pixel HgCdTe detectors for the range from 0.95 - 1.7μm. Each spectrograph will be coupled to the 3.5m telescope with two optical fibers, one for the target, and one for calibration light. The front end contains a dichroic beam splitter and an atmospheric dispersion corrector, to feed the light into the fibers leading to the spectrographs. Guiding is performed with a separate camera; on-axis as well as off-axis guiding modes are implemented. Fibers with octagonal cross-section are employed to ensure good stability of the output in the presence of residual guiding errors. The fibers are continually actuated to reduce modal noise. The spectrographs are mounted on benches inside vacuum tanks located in the coudé laboratory of the 3.5m dome. Each vacuum tank is equipped with a temperature stabilization system capable of keeping the temperature constant to within +/-0.01°C over 24 hours. The visible-light spectrograph will be operated near room temperature, while the near-IR spectrograph will be cooled to ~ 140 K. The CARMENES instrument passed its final design review in February 2013. The MAIV phase is currently ongoing. First tests at the telescope are scheduled for early 2015. Completion of the full instrument is planned for the fall of 2015. At least 600 useable nights have been allocated at the Calar Alto 3.5m Telescope for the CARMENES survey in the time frame until 2018. A data base of M stars (dubbed CARMENCITA) has been compiled from which the CARMENES sample can be selected. CARMENCITA contains information on all relevant properties of the potential targets. Dedicated imaging, photometric, and spectroscopic observations are underway to provide crucial data on these stars that are not available in the literature.

SU-F-T-158: Experimental Characterization of Field Size Dependence of Dose and Lateral Beam Profiles of Scanning Proton and Carbon Ion Beams for Empirical Model in Air

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

Li, Y; Hsi, W; Zhao, J

2016-06-15

Purpose: The Gaussian model for the lateral profiles in air is crucial for an accurate treatment planning system. The field size dependence of dose and the lateral beam profiles of scanning proton and carbon ion beams are due mainly to particles undergoing multiple Coulomb scattering in the beam line components and secondary particles produced by nuclear interactions in the target, both of which depend upon the energy and species of the beam. In this work, lateral profile shape parameters were fitted to measurements of field size dependence dose at the center of field size in air. Methods: Previous studies havemore » employed empirical fits to measured profile data to significantly reduce the QA time required for measurements. From this approach to derive the weight and sigma of lateral profiles in air, empirical model formulations were simulated for three selected energies for both proton and carbon beams. Results: The 20%–80% lateral penumbras predicted by the double model for proton and single model for carbon with the error functions agreed with the measurements within 1 mm. The standard deviation between measured and fitted field size dependence of dose for empirical model in air has a maximum accuracy of 0.74% for proton with double Gaussian, and of 0.57% for carbon with single Gaussian. Conclusion: We have demonstrated that the double Gaussian model of lateral beam profiles is significantly better than the single Gaussian model for proton while a single Gaussian model is sufficient for carbon. The empirical equation may be used to double check the separately obtained model that is currently used by the planning system. The empirical model in air for dose of spot scanning proton and carbon ion beams cannot be directly used for irregular shaped patient fields, but can be to provide reference values for clinical use and quality assurance.« less

Reducing the beam impedance of the kicker at the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

NASA Astrophysics Data System (ADS)

Shobuda, Yoshihiro; Chin, Yong Ho; Hayashi, Naoki; Irie, Yoshiro; Takayanagi, Tomohiro; Togashi, Tomohito; Toyama, Takeshi; Yamamoto, Kazami; Yamamoto, Masanobu

2018-06-01

The present four-terminal kicker at the rapid cycling synchrotron (RCS) at the Japan Proton Accelerator Research Complex has the power-saving benefit that it allows beam extraction by doubling the excitation currents with two shorted ends. In this configuration, two terminals of the kicker are connected to the pulse-forming line while the other two are terminated in a short circuit. On the other hand, beam instabilities are excited in the RCS by the kicker beam impedances, which result from the short-circuit termination of the kicker. In this paper, we describe a scheme to reduce the beam impedance of the kicker using diodes (nonlinear devices), while retaining the benefit of the doubled kicker excitation currents. We employ a simulation technique to determine the beam impedance of the kicker, even when such nonlinear devices and long cables are included. The characteristic of beam impedance measured using the accelerated beams is well explained by that obtained from the simulation.

KiwiSpec - an advanced spectrograph for high resolution spectroscopy: optical design and variations

NASA Astrophysics Data System (ADS)

Barnes, Stuart I.; Gibson, Steve; Nield, Kathryn; Cochrane, Dave

2012-09-01

The KiwiSpec R4-100 is an advanced high resolution spectrograph developed by KiwiStar Optics, Industrial Research Ltd, New Zealand. The instrument is based around an R4 echelle grating and a 100mm collimated beam diameter. The optical design employs a highly asymmetric white pupil design, whereby the transfer collimator has a focal length only 1/3 that of the primary collimator. This allows the cross-dispersers (VPH gratings) and camera optics to be small and low cost while also ensuring a very compact instrument. The KiwiSpec instrument will be bre-fed and is designed to be contained in both thermal and/or vacuum enclosures. The instrument concept is highly exible in order to ensure that the same basic design can be used for a wide variety of science cases. Options include the possibility of splitting the wavelength coverage into 2 to 4 separate channels allowing each channel to be highly optimized for maximum eciency. CCDs ranging from smaller than 2K2K to larger than 4K4K can be accommodated. This allows good (3-4 pixel) sampling of resolving powers ranging from below 50,000 to greater than 100,000. Among the specic design options presented here will be a two-channel concept optimized for precision radial velocities, and a four-channel concept developed for the Gemini High- Resolution Optical Spectrograph (GHOST). The design and performance of a single-channel prototype will be presented elsewhere in these proceedings.

VizieR Online Data Catalog: Spectroscopy of EG And over roughly 14 years (Kenyon+, 2016)

NASA Astrophysics Data System (ADS)

Kenyon, S. J.; Garcia, M. R.

2016-08-01

From 1994 September to 2016 January, P. Berlind, M. Calkins, and other observers acquired 480 low-resolution optical spectra of EG And with FAST, a high throughput, slit spectrograph mounted at the Fred L. Whipple Observatory 1.5m telescope on Mount Hopkins, Arizona They used a 300g/mm grating blazed at 4750Å, a 3'' slit, and a thinned 512*2688 CCD. These spectra cover 3800-7500Å at a resolution of 6Å. The full wavelength solution is derived from calibration lamps acquired immediately after each exposure. The wavelength solution for each frame has a probable error of <~+/-0.5Å. Most of the resulting spectra have moderate signal-to-noise ratio, S/N >~15-30 per pixel. Prior to the start of the FAST observations, we obtained occasional optical spectrophotometric observations of EG And throughout 1982-1989 with the cooled dual-beam intensified Reticon scanner (IRS) mounted on the white spectrograph at the KPNO No. 1 and No. 2 90cm telescopes. Various remote observers acquired high-resolution spectroscopic observations of EG And with the echelle spectrographs and Reticon detectors on the 1.5m telescopes of the Fred L. Whipple Observatory on Mount Hopkins, Arizona and the Oak Ridge Observatory in Harvard, Massachusetts. These spectra cover a 44Å bandpass centered near 5190Å or 5200Å and have a resolution of roughly 12km/s. (1 data file).

Green frequency-doubled laser-beam propagation in high-temperature hohlraum plasmas.

PubMed

Niemann, C; Berger, R L; Divol, L; Froula, D H; Jones, O; Kirkwood, R K; Meezan, N; Moody, J D; Ross, J; Sorce, C; Suter, L J; Glenzer, S H

2008-02-01

We demonstrate propagation and small backscatter losses of a frequency-doubled (2omega) laser beam interacting with inertial confinement fusion hohlraum plasmas. The electron temperature of 3.3 keV, approximately a factor of 2 higher than achieved in previous experiments with open geometry targets, approaches plasma conditions of high-fusion yield hohlraums. In this new temperature regime, we measure 2omega laser-beam transmission approaching 80% with simultaneous backscattering losses of less than 10%. These findings suggest that good laser coupling into fusion hohlraums using 2omega light is possible.

The Performance and Scientific Rationale for an Infrared Imaging Fourier Transform Spectrograph on a Large Space Telescope

DTIC Science & Technology

1998-06-22

micromirrors . Thus, an IFTS will produce a rich scientific legacy with tremendous potential for serendipity. Table 1 details the capabilities of an IFTS...maintain modulation efficiency. Curves are plotted for resolutions , 105, and 1064R 5 k/dk 5 10 assuming an 8 m diameter primary aperture and a beam splitter...passbands centered at 1.1, 1.3, 1.7, 2.3, and 3.6 mm. Colors are plotted from ; a triangle is plotted at every interval of unit redshift. These curves

Operation of GRETINA at NSCL

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

Sherrill, Bradley; Gade, Alexandra

This proposal funded the continued operation of the Gamma-ray Energy tracking Array GRETINA as a user device at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. This was a continuation and covered the operation from January 1, 2017 to December 31, 2017. Twenty-three experiments were completed with GRETINA at NSCL. GRETINA was installed at the reaction target position of the high-resolution, large-acceptance S800 spectrograph and the program started on October 15, 2017. The campaign capitalized on the opportunities provided by NSCL’s energetic rare isotope beams produced by projectile fragmentation.

OH radicals generated by DC corona discharge for improving the pulsed discharge desulfuration efficiency.

PubMed

Li, Jie; Li, Guo-feng; Wu, Yan; Wang, Ning-hui; Huang, Qiu-nan

2004-01-01

Positive DC corona discharge is formed with needle-plate electrode configuration, in which the water vapor is ejected though the needle points. The purpose is to increase the numbers of the water-based radicals, ionize the water molecule and improve the desulfuration efficiency of pulsed corona reactor. The water ions were determined by four stages molecular beam mass spectrometer and diagnose the water-based radicals by emission spectrograph. A conclusion on formation of ions and radicals with DC corona discharges can be drawn.

Advanced Instrumentation for Aero Engine Components: Conference Proceedings of the Propulsion and Energetics Panel Symposium (67th) Held in Philadelphia, Pennsylvania on 19-23 May 1986.

DTIC Science & Technology

1986-11-01

optical wave-mixing am., interact via the third order non linear susceptibility of the medium to produce a coherent laser-like signal beam at the higher...is the third order non- linear susceptibility of the medium and determines the shape of the CARS spectrum. It is the sum of a resonant contribution and...simultaneously using an appropriate spectrograph/optical multichannel detector; intensified linear diode array detectors are now used in most systems. The two

Precision improving of double beam shadow moiré interferometer by phase shifting interferometry for the stress of flexible substrate

NASA Astrophysics Data System (ADS)

Huang, Kuo-Ting; Chen, Hsi-Chao; Lin, Ssu-Fan; Lin, Ke-Ming; Syue, Hong-Ye

2012-09-01

While tin-doped indium oxide (ITO) has been extensively applied in flexible electronics, the problem of the residual stress has many obstacles to overcome. This study investigated the residual stress of flexible electronics by the double beam shadow moiré interferometer, and focused on the precision improvement with phase shifting interferometry (PSI). According to the out-of-plane displacement equation, the theoretical error depends on the grating pitch and the angle between incident light and CCD. The angle error could be reduced to 0.03% by the angle shift of 10° as a result of the double beam interferometer was a symmetrical system. But the experimental error of the double beam moiré interferometer still reached to 2.2% by the noise of the vibration and interferograms. In order to improve the measurement precision, PSI was introduced to the double shadow moiré interferometer. Wavefront phase was reconstructed by the five interferograms with the Hariharan algorithm. The measurement results of standard cylinder indicating the error could be reduced from 2.2% to less than 1% with PSI. The deformation of flexible electronic could be reconstructed fast and calculated the residual stress with the Stoney correction formula. This shadow moiré interferometer with PSI could improve the precision of residual stress for flexible electronics.

Suppressing longitudinal double-layer oscillations by using elliptically polarized laser pulses in the hole-boring radiation pressure acceleration regime

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

Wu Dong; Yan, X. Q.; Key Laboratory of High Energy Density Physics Simulation, Ministry of Education, Peking University, Beijing 100871

It is shown that well collimated mono-energetic ion beams with a large particle number can be generated in the hole-boring radiation pressure acceleration regime by using an elliptically polarized laser pulse with appropriate theoretically determined laser polarization ratio. Due to the J Multiplication-Sign B effect, the double-layer charge separation region is imbued with hot electrons that prevent ion pileup, thus suppressing the double-layer oscillations. The proposed mechanism is well confirmed by Particle-in-Cell simulations, and after suppressing the longitudinal double-layer oscillations, the ion beams driven by the elliptically polarized lasers own much better energy spectrum than those by circularly polarized lasers.

Fabrication and characterization of tunnel barriers in a multi-walled carbon nanotube formed by argon atom beam irradiation

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

Tomizawa, H.; Department of Applied Physics, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585; Yamaguchi, T., E-mail: tyamag@riken.jp

We have evaluated tunnel barriers formed in multi-walled carbon nanotubes (MWNTs) by an Ar atom beam irradiation method and applied the technique to fabricate coupled double quantum dots. The two-terminal resistance of the individual MWNTs was increased owing to local damage caused by the Ar beam irradiation. The temperature dependence of the current through a single barrier suggested two different contributions to its Arrhenius plot, i.e., formed by direct tunneling through the barrier and by thermal activation over the barrier. The height of the formed barriers was estimated. The fabrication technique was used to produce coupled double quantum dots withmore » serially formed triple barriers on a MWNT. The current measured at 1.5 K as a function of two side-gate voltages resulted in a honeycomb-like charge stability diagram, which confirmed the formation of the double dots. The characteristic parameters of the double quantum dots were calculated, and the feasibility of the technique is discussed.« less

New technique of skin embedded wire double-sided laser beam welding

NASA Astrophysics Data System (ADS)

Han, Bing; Tao, Wang; Chen, Yanbin

2017-06-01

In the aircraft industry, double-sided laser beam welding is an approved method for producing skin-stringer T-joints on aircraft fuselage panels. As for the welding of new generation aluminum-lithium alloys, however, this technique is limited because of high hot cracking susceptibility and strengthening elements' uneven distributions within weld. In the present study, a new technique of skin embedded wire double-sided laser beam welding (LBW) has been developed to fabricate T-joints consisting of 2.0 mm thick 2060-T8/2099-T83 aluminum-lithium alloys using eutectic alloy AA4047 filler wire. Necessary dimension parameters of the novel groove were reasonably designed for achieving crack-free welds. Comparisons were made between the new technique welded T-joint and conventional T-joint mainly on microstructure, hot crack, elements distribution features and mechanical properties within weld. Excellent crack-free microstructure, uniform distribution of silicon and superior tensile properties within weld were found in the new skin embedded wire double-sided LBW T-joints.

A review of the development of portable laser induced breakdown spectroscopy and its applications

NASA Astrophysics Data System (ADS)

Rakovský, J.; Čermák, P.; Musset, O.; Veis, P.

2014-11-01

In this review, we present person-transportable laser induced breakdown spectroscopy (LIBS) devices that have previously been developed and reported in the literature as well as their applications. They are compared with X-ray fluorescent (XRF) devices, which represent their strongest competition. Although LIBS devices have advantages over XRF devices, such as sensitivity to the light elements, high spatial resolution and the possibility to distinguish between different layers of the sample, there are also disadvantages and both are discussed here. Furthermore, the essential portable LIBS instrumentation (laser, spectrograph and detector) is presented, and published results related to new laser sources (diode-pumped solid-state, microchip and fiber lasers) used in LIBS are overviewed. Compared to conventional compact flashlamp pumped solid-state lasers, the new laser sources provide higher repetition rates, higher efficiency (less power consumption) and higher beam quality, resulting in higher fluences, even for lower energies, and could potentially increase the figure of merit of portable LIBS instruments. Compact spectrometers used in portable LIBS devices and their parts (spectrograph, detector) are also discussed.

The Cryogenic Near Infrared Spectropolarimeter for the Daniel K. Inouye Solar Telescope

NASA Astrophysics Data System (ADS)

Fehlmann, Andre; Giebink, Cindy; Kuhn, Jeffrey Richard; Mickey, D. L.; Scholl, Isabelle

2017-08-01

The Cryogenic Near Infrared Spectropolarimeter is one of the first light instruments for the Daniel K. Inouye Solar Telescope. This dual-beam instrument, which is currently characterized at the University of Hawaii’s Institute for Astronomy, is designed to sensitively measure the solar spectrum at wavelengths from 1 to 5 μm. The high dynamic range of the spectrograph and its context imager will provide sensitive data of the solar disk in the CO bands; unique observations of the low corona and unprecedented measurements of the coronal magnetic field. Observations near the limb and in the corona will greatly benefit from DKIST’s limb occulting system. The initial suite of filters includes selecting filters for the spectrograph at He I / Fe XIII 1080 nm, Si X 1430 nm, Si IX 3934 nm and CO 4651 nm as well as narrow band filters for the context imager at Fe XIII 1074.7 nm, He I 1083.0, Si X 1430.0 nm and J band 1250 nm. In this paper we will present an update on the ongoing instrument characterization and CryoNIRSP’s capabilities.

Design study of the PEPSI polarimeter for the LBT

NASA Astrophysics Data System (ADS)

Hofmann, A.; Strassmeier, K. G.; Woche, M.

2002-07-01

We present the conceptual design of the two polarimetric channels of the PEPSI spectropolarimeter for the Large Binocular Telescope (LBT). The two direct Gregorian f/15 focii of the LBT will take up two identical but independent full-Stokes IQUV polarimeters that themselves fiberfeed a high-resolution Echelle spectrograph (see the accompanying paper by Zerbi et al.). The polarizing units will be based on super-achromatic Fresnel-rhomb retarders and Foster prisms. A total of four fibers are foreseen to simultaneously direct two ordinary and two extraordinary light beams to the Echelle spectrograph. Both polarimetric units are layed out in a modular design, each one optimized to the polarization state in which it is used. A number of observing modes can be chosen that are optimized to the type of polarization that is expected from the target, e.g. circularly and linearly polarized light simultaneously, or linearly polarized light in both polarimeters, or integral light from one and polarized light from the other telescope, a.s.o.. Calibration would be provided for each polarimeter separately.

Teaching Quantum Uncertainty

ERIC Educational Resources Information Center

Hobson, Art

2011-01-01

An earlier paper introduces quantum physics by means of four experiments: Youngs double-slit interference experiment using (1) a light beam, (2) a low-intensity light beam with time-lapse photography, (3) an electron beam, and (4) a low-intensity electron beam with time-lapse photography. It's ironic that, although these experiments demonstrate…

Integration, commissioning, and performance of the UK FMOS spectrograph

NASA Astrophysics Data System (ADS)

Dalton, Gavin B.; Lewis, Ian J.; Tosh, Ian A. J.; Blackburn, Colin; Bonfield, David G.; Brooks, Charles B.; Holmes, Alan R.; Lee, Hanshin; Froud, Tim R.; Akiyama, Masayuki; Tamura, Naoyuki; Takato, Naruhisa

2008-07-01

The UK FMOS spectrograph forms part of Subaru's FMOS multi-object infrared spectroscopy facility. The spectrograph was shipped to Hilo in component form in August of 2007. We describe the integration sequence for the spectrograph, the results of cooldown tests using a new chiller unit fitted to the spectrograph at the telescope, and alignment tests of the spectrograph, gratings and OH-suppression masks. We present the first-light observations for the spectrograph from May 2008.

SU-F-T-522: Dosimetric Study of Junction Dose in Double Isocenter Flatten and Flatten Filter Free IMRT and VMAT Plan Delivery

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

Samuvel, K; Yadav, G; Bhushan, M

2016-06-15

Purpose: To quantify the dosimetric accuracy of junction dose in double isocenter flattened and flatten filter free(FFF) intensity modulated radiation therapy(IMRT) and volumetric modulated arc therapy(VMAT) plan delivery using pelvis phantom. Methods: Five large field pelvis patients were selected for this study. Double isocenter IMRT and VMAT treatment plans were generated in Eclipse Treatment planning System (V.11.0) using 6MV FB and FFF beams. For all the plans same distance 17.0cm was kept between one isocenter to another isocenter. IMRT Plans were made with 7 coplanar fields and VMAT plans were made with full double arcs. Dose calculation was performed usingmore » AAA algorithms with dose grid size of 0.25 cm. Verification plans were calculated on Scanditronix Wellhofer pelvis slab phantom. Measurement point was selected and calculated, where two isocenter plan fields are overlapping, this measurement point was kept at distance 8.5cm from both isocenter. The plans were delivered using Varian TrueBeamTM machine on pelvis slab phantom. Point dose measurements was carried out using CC13 ion chamber volume of 0.13cm3. Results: The measured junction point dose are compared with TPS calculated dose. The mean difference observed was 4.5%, 6.0%, 4.0% and 7.0% for IMRT-FB,IMRT-FFF, VMAT-FB and VMAT-FFF respectively. The measured dose results shows closer agreement with calculated dose in Flatten beam planning in both IMRT and VMAT, whereas in FFF beam plan dose difference are more compared with flatten beam plan. Conclusion: Dosimetry accuracy of Large Field junction dose difference was found less in Flatten beam compared with FFF beam plan delivery. Even though more dosimetric studies are required to analyse junction dose for FFF beam planning using multiple point dose measurements and fluence map verification in field junction area.« less

Wave-optics simulation of the double-pass beam propagation in modulating retro-reflector FSO systems using a corner cube reflector.

PubMed

Yang, Guowei; You, Shengzui; Bi, Meihua; Fan, Bing; Lu, Yang; Zhou, Xuefang; Li, Jing; Geng, Hujun; Wang, Tianshu

2017-09-10

Free-space optical (FSO) communication utilizing a modulating retro-reflector (MRR) is an innovative way to convey information between the traditional optical transceiver and the semi-passive MRR unit that reflects optical signals. The reflected signals experience turbulence-induced fading in the double-pass channel, which is very different from that in the traditional single-pass FSO channel. In this paper, we consider the corner cube reflector (CCR) as the retro-reflective device in the MRR. A general geometrical model of the CCR is established based on the ray tracing method to describe the ray trajectory inside the CCR. This ray tracing model could treat the general case that the optical beam is obliquely incident on the hypotenuse surface of the CCR with the dihedral angle error and surface nonflatness. Then, we integrate this general CCR model into the wave-optics (WO) simulation to construct the double-pass beam propagation simulation. This double-pass simulation contains the forward propagation from the transceiver to the MRR through the atmosphere, the retro-reflection of the CCR, and the backward propagation from the MRR to the transceiver, which can be realized by a single-pass WO simulation, the ray tracing CCR model, and another single-pass WO simulation, respectively. To verify the proposed CCR model and double-pass WO simulation, the effective reflection area, the incremental phase, and the reflected beam spot on the transceiver plane of the CCR are analyzed, and the numerical results are in agreement with the previously published results. Finally, we use the double-pass WO simulation to investigate the double-pass channel in the MRR FSO systems. The histograms of the turbulence-induced fading in the forward and backward channels are obtained from the simulation data and are fitted by gamma-gamma (ΓΓ) distributions. As the two opposite channels are highly correlated, we model the double-pass channel fading by the product of two correlated ΓΓ random variables (RVs).

A double expansion method for the frequency response of finite-length beams with periodic parameters

NASA Astrophysics Data System (ADS)

Ying, Z. G.; Ni, Y. Q.

2017-03-01

A double expansion method for the frequency response of finite-length beams with periodic distribution parameters is proposed. The vibration response of the beam with spatial periodic parameters under harmonic excitations is studied. The frequency response of the periodic beam is the function of parametric period and then can be expressed by the series with the product of periodic and non-periodic functions. The procedure of the double expansion method includes the following two main steps: first, the frequency response function and periodic parameters are expanded by using identical periodic functions based on the extension of the Floquet-Bloch theorem, and the period-parametric differential equation for the frequency response is converted into a series of linear differential equations with constant coefficients; second, the solutions to the linear differential equations are expanded by using modal functions which satisfy the boundary conditions, and the linear differential equations are converted into algebraic equations according to the Galerkin method. The expansion coefficients are obtained by solving the algebraic equations and then the frequency response function is finally determined. The proposed double expansion method can uncouple the effects of the periodic expansion and modal expansion so that the expansion terms are determined respectively. The modal number considered in the second expansion can be reduced remarkably in comparison with the direct expansion method. The proposed double expansion method can be extended and applied to the other structures with periodic distribution parameters for dynamics analysis. Numerical results on the frequency response of the finite-length periodic beam with various parametric wave numbers and wave amplitude ratios are given to illustrate the effective application of the proposed method and the new frequency response characteristics, including the parameter-excited modal resonance, doubling-peak frequency response and remarkable reduction of the maximum frequency response for certain parametric wave number and wave amplitude. The results have the potential application to structural vibration control.

Gradient forces on double-negative particles in optical tweezers using Bessel beams in the ray optics regime.

PubMed

Ambrosio, Leonardo A; Hernández-Figueroa, Hugo E

2010-11-08

Gradient forces on double negative (DNG) spherical dielectric particles are theoretically evaluated for v-th Bessel beams supposing geometrical optics approximations based on momentum transfer. For the first time in the literature, comparisons between these forces for double positive (DPS) and DNG particles are reported. We conclude that, contrary to the conventional case of positive refractive index, the gradient forces acting on a DNG particle may not reverse sign when the relative refractive index n goes from |n|>1 to |n|<1, thus revealing new and interesting trapping properties.

Exploring forward physics with the PHENIX MPC-EX upgrade

NASA Astrophysics Data System (ADS)

Novitzky, Norbert; Phenix Collaboration

2014-09-01

The MPC-EX detector is a Si-W preshower extension to the existing Muon Piston Calorimeter (MPC) at PHENIX. Located at forward rapidity, 3 . 1 < | η | < 3 . 8 , the MPC-EX consists of eight layers of alternating W absorber and Si minipad sensors. Covering a large range at forward rapidity makes the MPC-EX and MPC ideal to access low-x partons in the A nucleus of p + A collisions. The neutral pion and direct photon are excellent probes to separate between the initial and final state effects of the pA collisions. Isolating the direct photon signal requires the MPC-EX to be able to distinguish single showers from double showers. The single versus double shower separation was tested with an electron beam at the SLAC test beam facility. Results from the test beam data will be presented in this talk. The MPC-EX detector is a Si-W preshower extension to the existing Muon Piston Calorimeter (MPC) at PHENIX. Located at forward rapidity, 3 . 1 < | η | < 3 . 8 , the MPC-EX consists of eight layers of alternating W absorber and Si minipad sensors. Covering a large range at forward rapidity makes the MPC-EX and MPC ideal to access low-x partons in the A nucleus of p + A collisions. The neutral pion and direct photon are excellent probes to separate between the initial and final state effects of the pA collisions. Isolating the direct photon signal requires the MPC-EX to be able to distinguish single showers from double showers. The single versus double shower separation was tested with an electron beam at the SLAC test beam facility. Results from the test beam data will be presented in this talk. Norbert Novitzky for PHENIX collaboration.

Automatic alignment of double optical paths in excimer laser amplifier

NASA Astrophysics Data System (ADS)

Wang, Dahui; Zhao, Xueqing; Hua, Hengqi; Zhang, Yongsheng; Hu, Yun; Yi, Aiping; Zhao, Jun

2013-05-01

A kind of beam automatic alignment method used for double paths amplification in the electron pumped excimer laser system is demonstrated. In this way, the beams from the amplifiers can be transferred along the designated direction and accordingly irradiate on the target with high stabilization and accuracy. However, owing to nonexistence of natural alignment references in excimer laser amplifiers, two cross-hairs structure is used to align the beams. Here, one crosshair put into the input beam is regarded as the near-field reference while the other put into output beam is regarded as the far-field reference. The two cross-hairs are transmitted onto Charge Coupled Devices (CCD) by image-relaying structures separately. The errors between intersection points of two cross-talk images and centroid coordinates of actual beam are recorded automatically and sent to closed loop feedback control mechanism. Negative feedback keeps running until preset accuracy is reached. On the basis of above-mentioned design, the alignment optical path is built and the software is compiled, whereafter the experiment of double paths automatic alignment in electron pumped excimer laser amplifier is carried through. Meanwhile, the related influencing factors and the alignment precision are analyzed. Experimental results indicate that the alignment system can achieve the aiming direction of automatic aligning beams in short time. The analysis shows that the accuracy of alignment system is 0.63μrad and the beam maximum restoration error is 13.75μm. Furthermore, the bigger distance between the two cross-hairs, the higher precision of the system is. Therefore, the automatic alignment system has been used in angular multiplexing excimer Main Oscillation Power Amplification (MOPA) system and can satisfy the requirement of beam alignment precision on the whole.

KiwiSpec - an advanced spectrograph for high resolution spectroscopy: prototype design and performance

NASA Astrophysics Data System (ADS)

Gibson, Steve; Barnes, Stuart I.; Hearnshaw, John; Nield, Kathryn; Cochrane, Dave; Grobler, Deon

2012-09-01

A new advanced high resolution spectrograph has been developed by Kiwistar Optics of Industrial Research Ltd., New Zealand. The instrument, KiwiSpec R4-100, is bench-mounted, bre-fed, compact (0.75m by 1.5m footprint), and is well-suited for small to medium-sized telescopes. The instrument makes use of several advanced concepts in high resolution spectrograph design. The basic design follows the classical white pupil concept in an asymmetric implementation and employs an R4 echelle grating illuminated by a 100mm diameter collimated beam for primary dispersion. A volume phase holographic grating (VPH) based grism is used for cross-dispersion. The design also allows for up to four camera and detector channels to allow for extended wavelength coverage at high eciency. A single channel prototype of the instrument has been built and successfully tested with a 1m telescope. Targets included various spectrophotometric standard stars and several radial velocity standard stars to measure the instrument's light throughput and radial velocity capabilities. The prototype uses a 725 lines/mm VPH grism, an off-the-shelf camera objective, and a 2k×2k CCD. As such, it covers the wavelength range from 420nm to 660nm and has a resolving power of R ≍ 40,000. Spectrophotometric and precision radial velocity results from the on-sky testing period will be reported, as well as results of laboratory-based measurements. The optical design of KiwiSpec, and the various multi-channel design options, will be presented elsewhere in these proceedings.

DMD-based programmable wide field spectrograph for Earth observation

NASA Astrophysics Data System (ADS)

Zamkotsian, Frédéric; Lanzoni, Patrick; Liotard, Arnaud; Viard, Thierry; Costes, Vincent; Hébert, Philippe-Jean

2015-03-01

In Earth Observation, Universe Observation and Planet Exploration, scientific return could be optimized in future missions using MOEMS devices. In Earth Observation, we propose an innovative reconfigurable instrument, a programmable wide-field spectrograph where both the FOV and the spectrum could be tailored thanks to a 2D micromirror array (MMA). For a linear 1D field of view (FOV), the principle is to use a MMA to select the wavelengths by acting on intensity. This component is placed in the focal plane of a first grating. On the MMA surface, the spatial dimension is along one side of the device and for each spatial point, its spectrum is displayed along the perpendicular direction: each spatial and spectral feature of the 1D FOV is then fully adjustable dynamically and/or programmable. A second stage with an identical grating recomposes the beam after wavelengths selection, leading to an output tailored 1D image. A mock-up has been designed, fabricated and tested. The micromirror array is the largest DMD in 2048 x 1080 mirrors format, with a pitch of 13.68μm. A synthetic linear FOV is generated and typical images have been recorded o at the output focal plane of the instrument. By tailoring the DMD, we could modify successfully each pixel of the input image: for example, it is possible to remove bright objects or, for each spatial pixel, modify the spectral signature. The very promising results obtained on the mock-up of the programmable wide-field spectrograph reveal the efficiency of this new instrument concept for Earth Observation.

Status of the New Surface Muon Beamline at J-PARC MUSE

NASA Astrophysics Data System (ADS)

Strasser, P.; Koda, A.; Kojima, K. M.; Ito, T. U.; Fujimori, H.; Irie, Y.; Aoki, M.; Nakatsugawa, Y.; Higemoto, W.; Hiraishi, M.; Li, H.; Okabe, H.; Takeshita, S.; Shimomura, K.; Kawamura, N.; Kadono, R.; Miyake, Y.

A new surface muon beamline (S-line) dedicated to condensed matter physics experiments is being constructed at the Muon Science Facility (MUSE) located in the Materials and Life Science Facility (MLF) building at J-PARC. This beamline designed to provide high-intensity surface muons with a momentum of 28 MeV/c will comprise four beam legs and four experimental areas that will share the double-pulsed muon beam. The key feature is a new kicker system comprising two electric kickers to deliver the muon beam to the four experimental areas ensuring an optimum and seamless sharing of the double-pulsed muon beam. At present, only one experimental area (S1) has been completed and is now open to the user program since February 2017. An overview of the different aspects of this new surface muon beamline and the present status of the beam commissioning are presented.

Double-Referential Holography and Spatial Quadrature Amplitude Modulation

NASA Astrophysics Data System (ADS)

Zukeran, Keisuke; Okamoto, Atsushi; Takabayashi, Masanori; Shibukawa, Atsushi; Sato, Kunihiro; Tomita, Akihisa

2013-09-01

We proposed a double-referential holography (DRH) that allows phase-detection without external additional beams. In the DRH, phantom beams, prepared in the same optical path as signal beams and preliminary multiplexed in a recording medium along with the signal, are used to produce interference fringes on an imager for converting a phase into an intensity distribution. The DRH enables stable and high-accuracy phase detection independent of the fluctuations and vibrations of the optical system owing to medium shift and temperature variation. Besides, the collinear arrangement of the signal and phantom beams leads to the compactness of the optical data storage system. We conducted an experiment using binary phase modulation signals for verifying the DRH operation. In addition, 38-level spatial quadrature amplitude modulation signals were successfully reproduced with the DRH by numerical simulation. Furthermore, we verified that the distributed phase-shifting method moderates the dynamic range consumption for the exposure of phantom beams.

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.

Vacuum deposition of iridium on large astronomical mirrors for use in the far UV

NASA Technical Reports Server (NTRS)

Herzig, H.; Spencer, R. S.

1982-01-01

An iridium coating has been deposited by electron-beam evaporation on a 0.91-m mirror which serves as the telescope primary of a sounding rocket instrument for far-UV spectrometry. The evaporation was carried out by applying 8 kV at 400 mA to the electron gun. Zone refined Ir of 99.99% purity was used, and the electron beam was electromagnetically swept over the surface of the evaporant. Under these conditions, deposition rates of 0.55 A/sec were achieved. The reflectance distribution achieved at a wavelength of 584 A was extremely uniform; the mean reflectance was 21.2% with a standard deviation of only 0.3%. This represents a substantial improvement over Al + MgF2 and Al + LiF coatings for applications involving multiple reflections and weak signals, as might be expected in a high-resolution spectrograph studying distant celestial objects.

Asymmetry of bifurcated features in radio pulsar profiles

NASA Astrophysics Data System (ADS)

Dyks, J.; Rudak, B.

2012-03-01

High-quality integrated radio profiles of some pulsars contain bifurcated, highly symmetric emission components (BECs). They are observed when our line of sight traverses through a split-fan shaped emission beam. It is shown that for oblique cuts through such a beam, the features appear asymmetric at nearly all frequencies, except for a single 'frequency of symmetry'νsym, at which both peaks in the BEC have the same height. Around νsym, the ratio of flux in the two peaks of a BEC evolves in a way resembling the multifrequency behaviour of J1012+5307. Because of the inherent asymmetry resulting from the oblique traverse of the sightline, each minimum in double notches can be modelled independently. Such a composed model reproduces the double notches of B1929+10 if the fitted function is the microscopic beam of curvature radiation in the orthogonal polarization mode. These results confirm our view that some of the double components in radio pulsar profiles directly reveal the microscopic nature of the emitted radiation beam as the microbeam of the curvature radiation polarized orthogonally to the trajectory of electrons.

Double-layered microstrip metamaterial beam scanning leaky wave antenna with consistent gain and low cross-polarization

NASA Astrophysics Data System (ADS)

An, Yong-li; Tan, Yi-li; Zhang, Hong-bo; Wu, Guo-cheng

2017-12-01

In this paper, a novel double-layered microstrip metamaterial beam scanning leaky wave antenna (LWA) is proposed and investigated to achieve consistent gain and low cross-polarization. Thanks to the continuous phase constant changing from negative to positive values over the passband of the double-layered microstrip metamaterial, the proposed LWA, which consists of 20 identical microstrip metamaterial unit cells, can obtain a continuous beam scanning property from backward to forward directions. The proposed LWA is fabricated and measured. The measured results show that the fabricated antenna obtains a continuous beam scanning angle of 140° over the operating frequency band of 3.80-5.25 GHz (32%), the measured 3 dB gain bandwidth is 30.17% with maximum gain of 11.7 dB. Besides, the measured cross-polarization of the fabricated antenna keeps at a level of at least 30 dB below the co-polarization across the entire radiation region. Moreover, the measured and simulated results are in good agreement with each other, indicating the significance and effectiveness of this method.

Progress on Background-Limited Membrane-Isolated TES Bolometers for Far-IR/Submillimeter Spectroscopy

NASA Technical Reports Server (NTRS)

Kenyon, M.; Day, P. K.; Bradford, C. M.; Bock, J. J.; Leduc, H. G.

2006-01-01

To determine the lowest attainable phonon noise equivalent power (NEP) for membrane-isolation bolometers, we fabricated and measured the thermal conductance of suspended Si3N4 beams with different geometries via a noise thermometry technique. We measured beam cross-sectional areas ranging from 0.35 x 0.5 (micro)m(sup 2) to 135 x 1.0 (micro)m(sup 2) and beam lengths ranging from (micro)m to 8300 (micro)m. The measurements directly imply that membrane-isolation bolometers are capable of reaching a phonon noise equivalent power (NEP) of 4 x 10(sup -20)W/Hz(sup 1)/O . This NEP adequate for the Background-Limited Infrared-Submillimeter Spectrograph (BLISS) proposed for the Japanese SPICA observatory, and adequate for NASA's SAFIR observatory, a 10-meter, 4 K telescope to be deployed at L2. Further, we measured the heat capacity of a suspended Si3N4 membrane and show how this result implies that one can make membrane-isolation bolometers with a response time which is fast enough for BLISS.

Local Deplanation Of Double Reinforced Beam Cross Section Under Bending

NASA Astrophysics Data System (ADS)

Baltov, Anguel; Yanakieva, Ana

2015-12-01

Bending of beams, double reinforced by means of thin composite layers, is considered in the study. Approximate numerical solution is proposed, considering transitional boundary areas, where smooth quadratic transition of the elasticity modulus and deformations take place. Deplanation of the cross section is also accounted for in the areas. Their thickness is found equalizing the total stiffness of the cross section and the layer stiffness. Deplanation of the cross section of the transitional area is determined via the longitudinal deformation in the reinforcing layer, accounting for the equilibrium between the internal and the external moment, generated by the longitudinal stresses in the cross section. A numerical example is given as an illustration demonstrating model's plausibility. The model allows the design and the calculation of recycled concrete beams double reinforced by means of thin layers. The approach is in agreement with modern design of nearly zero energy buildings (NZEB).

Fracture Mechanics Analysis of Stitched Stiffener-Skin Debonding

NASA Technical Reports Server (NTRS)

Glaessgen, E. H.; Raju, I. S.; Poe, C. C., Jr.

1998-01-01

An analysis based on plate finite elements and the virtual crack closure technique has been implemented to study the effect of stitching on mode I and mode II strain energy release rates for debond configurations. The stitches were modeled as discrete nonlinear fastener elements with a compliance determined by experiment. The axial and shear behavior of the stitches was considered, however, the two compliances and failure loads were assumed to be independent. Both a double cantilever beam (mode I) and a mixed mode skin-stiffener debond configuration were studied. In the double cantilever beam configurations, G(sub I) began to decrease once the debond had grown beyond the first row of stitches and was reduced to zero for long debonds. In the mixed-mode skin-stiffener configurations, G(sub I) showed a similar behavior as in the double cantilever beam configurations, however, G(sub u), continued to increase with increasing debond length.

Spectrum of sodiumlike selenium - Se XXIV

NASA Technical Reports Server (NTRS)

Brown, C. M.; Seely, J. F.; Feldman, U.; Richardson, M. C.; Behring, W. E.; Cohen, L.

1986-01-01

High-resolution spectra of Se XXIV have been obtained with a 3-m grazing-incidence spectrograph. Thin plastic foils coated with selenium were irradiated with four or eight beams of the OMEGA laser in a line-focus configuration. Spectrograms were obtained by viewing the plasma axially. Prominent in the spectra were the 3s-3p and 3p-3d transitions in the 150-240-A region and the transitions nl-(n + 1)l-prime with n = 3, 4 in the 24-80-A region. The energy levels and ionization limit derived from the measured wavelengths are also presented.

VizieR Online Data Catalog: Equivalent widths and atomic data for GCs (Lamb+, 2015)

NASA Astrophysics Data System (ADS)

Lamb, M. P.; Venn, K. A.; Shetrone, M. D.; Sakari, C. M.; Pritzl, B. J.

2017-11-01

Optical spectra were gathered with the High Resolution Spectrograph (HRS; Tull 1998, Proc. SPIE, 3355, 387) on the HET. The HRS was configured at resolution R=30000 with 2x2 pixel binning using the 2 arcsec fibre. The HRS splits the incoming beam on to two CCD chips, from which the spectral regions 6000-7000 Å (red chip) and 4800-5900 Å (blue chip) were extracted for this work. Two standard stars were also observed, RGB stars with previously published spectral analyses in each of the GCs M3 and M13. (2 data files).

Enhanced long-distance transport of periodic electron beams in an advanced double layer cone-channel target

NASA Astrophysics Data System (ADS)

Ji, Yanling; Duan, Tao; Zhou, Weimin; Li, Boyuan; Wu, Fengjuan; Zhang, Zhimeng; Ye, Bin; Wang, Rong; Wu, Chunrong; Tang, Yongjian

2018-02-01

An enhanced long-distance transport of periodic electron beams in an advanced double layer cone-channel target is investigated using two-dimensional particle-in-cell simulations. The target consists of a cone attached to a double-layer hollow channel with a near-critical-density inner layer. The periodic electron beams are generated by the combination of ponderomotive force and longitudinal laser electric field. Then a stable electron propagation is achieved in the double-layer channel over a much longer distance without evident divergency, compared with a normal cone-channel target. Detailed simulations show that the much better long-distance collimation and guidance of energetic electrons is attributed to the much stronger electromagnetic fields at the inner wall surfaces. Furthermore, a continuous electron acceleration is obtained by the more intense laser electric fields and extended electron acceleration length in the channel. Our investigation shows that by employing this advanced target, both the forward-going electron energy flux in the channel and the energy coupling efficiency from laser to electrons are about threefold increased in comparison with the normal case.

Volume phase holographic gratings for the Subaru Prime Focus Spectrograph: performance measurements of the prototype grating set

NASA Astrophysics Data System (ADS)

Barkhouser, Robert H.; Arns, James; Gunn, James E.

2014-08-01

The Prime Focus Spectrograph (PFS) is a major instrument under development for the 8.2 m Subaru telescope on Mauna Kea. Four identical, fixed spectrograph modules are located in a room above one Nasmyth focus. A 55 m fiber optic cable feeds light into the spectrographs from a robotic fiber positioner mounted at the telescope prime focus, behind the wide field corrector developed for Hyper Suprime-Cam. The positioner contains 2400 fibers and covers a 1.3 degree hexagonal field of view. Each spectrograph module will be capable of simultaneously acquiring 600 spectra. The spectrograph optical design consists of a Schmidt collimator, two dichroic beamsplitters to separate the light into three channels, and for each channel a volume phase holographic (VPH) grating and a dual- corrector, modified Schmidt reimaging camera. This design provides a 275 mm collimated beam diameter, wide simultaneous wavelength coverage from 380 nm to 1.26 µm, and good imaging performance at the fast f/1.1 focal ratio required from the cameras to avoid oversampling the fibers. The three channels are designated as the blue, red, and near-infrared (NIR), and cover the bandpasses 380-650 nm (blue), 630-970 nm (red), and 0.94-1.26 µm (NIR). A mosaic of two Hamamatsu 2k×4k, 15 µm pixel CCDs records the spectra in the blue and red channels, while the NIR channel employs a 4k×4k, substrate-removed HAWAII-4RG array from Teledyne, with 15 µm pixels and a 1.7 µm wavelength cutoff. VPH gratings have become the dispersing element of choice for moderate-resolution astronomical spectro- graphs due their potential for very high diffraction efficiency, low scattered light, and the more compact instru- ment designs offered by transmissive dispersers. High quality VPH gratings are now routinely being produced in the sizes required for instruments on large telescopes. These factors made VPH gratings an obvious choice for PFS. In order to reduce risk to the project, as well as fully exploit the performance potential of this technology, a set of three prototype VPH gratings (one each of the blue, red, and NIR designs) was ordered and has been recently delivered. The goal for these prototype units, but not a requirement, was to meet the specifications for the final gratings in order to serve as spares and also as early demonstration and integration articles. In this paper we present the design and specifications for the PFS gratings, the plan and setups used for testing both the prototype and final gratings, and results from recent optical testing of the prototype grating set.

The optical design of GMOX: a next-generation instrument concept for Gemini

NASA Astrophysics Data System (ADS)

Barkhouser, Robert; Robberto, Massimo; Smee, Stephen A.; Ninkov, Zoran; Gennaro, Mario; Heckman, Timothy

2016-08-01

We present the optical design of GMOX, the Gemini Multi-Object eXtra-wide-band spectrograph. GMOX was selected as part of the Gemini Instrument Feasibility Study to develop capabilities and requirements for the next facility instrument (Gen4#3) for the observatory. We envision GMOX covering the entire optical/near-IR wavelength range accessible from the ground, from 3500 Å in the U band up to 2.4 μm in the K band, with nominal resolving power R≃5,000. To maximize efficiency, the bandpass is split into three spectrograph arms - blue, red, and near-infrared - with the near-infrared arm further split into three channels covering the Y+J, H, and K bands. At the heart of each arm is a Digital Micromirror Device (DMD) serving as a programmable slit array. This technology will enable GMOX to simultaneously acquire hundreds of spectra of faint sources in crowded fields with unparalleled spatial resolution, optimally adapting to both seeing-limited and diffraction limited conditions provided by ALTAIR and GeMS at Gemini North and South, respectively. Fed by GeMS at f/33, GMOX can synthesize slits as small as 40 mas (corresponding to a single HST/WFC3 CCD pixel) over its entire 85"x45" field of view. With either ALTAIR or the native telescope focal ratio of f/16, both the slit and field sizes double. In this paper we discuss the conceptual optical design of GMOX including, for each arm: the pre-slit optics, DMD slit array, off-axis Schmidt collimator, VPH grating, and refractive spectrograph and slit-viewing cameras.

Optomechanical design concept for GMACS: a wide-field multi-object moderate resolution optical spectrograph for the Giant Magellan Telescope (GMT)

NASA Astrophysics Data System (ADS)

Smee, Stephen A.; Prochaska, Travis; Shectman, Stephen A.; Hammond, Randolph P.; Barkhouser, Robert H.; DePoy, D. L.; Marshall, J. L.

2012-09-01

We describe the conceptual optomechanical design for GMACS, a wide-field, multi-object, moderate-resolution optical spectrograph for the Giant Magellan Telescope (GMT). GMACS is a candidate first-light instrument for the GMT and will be one of several instruments housed in the Gregorian Instrument Rotator (GIR) located at the Gregorian focus. The instrument samples a 9 arcminute x 18 arcminute field of view providing two resolution modes (i.e, low resolution, R ~ 2000, and moderate resolution, R ~ 4000) over a 3700 Å to 10200 Å wavelength range. To minimize the size of the optics, four fold mirrors at the GMT focal plane redirect the full field into four individual "arms", that each comprises a double spectrograph with a red and blue channel. Hence, each arm samples a 4.5 arcminute x 9 arcminute field of view. The optical layout naturally leads to three separate optomechanical assemblies: a focal plane assembly, and two identical optics modules. The focal plane assembly contains the last element of the telescope's wide-field corrector, slit-mask, tent-mirror assembly, and slit-mask magazine. Each of the two optics modules supports two of the four instrument arms and houses the aft-optics (i.e. collimators, dichroics, gratings, and cameras). A grating exchange mechanism, and articulated gratings and cameras facilitate multiple resolution modes. In this paper we describe the details of the GMACS optomechanical design, including the requirements and considerations leading to the design, mechanism details, optics mounts, and predicted flexure performance.

High-power Bessel beams with orbital angular momentum in the terahertz range

NASA Astrophysics Data System (ADS)

Choporova, Yu. Yu.; Knyazev, B. A.; Kulipanov, G. N.; Pavelyev, V. S.; Scheglov, M. A.; Vinokurov, N. A.; Volodkin, B. O.; Zhabin, V. N.

2017-08-01

In this paper, we have performed experimental, analytical, and numerical studies of beams with topological charges of ±1 and ±2 formed by silicon binary phase axicons (BPAs) with spiral zone structures. The axicons were illuminated with the Novosibirsk free electron laser radiation (a continuous stream of 100-ps pulses at f =5.6 MHz). The cw power of the beams produced reached 30 W and can by doubled via antireflection coating of the axicons. The intensity distribution in the beam cross sections was in good agreement with the Bessel functions and was kept constant within a distance of about L /r ≈190 and 100, where the first ring radii of the beams r were 0.9 and 1.5 mm for the Bessel beams of the first and second orders, respectively. Although the characteristics of the beams (Bessel cross section, "diffraction-free" propagation, self-recovery after passing obstacles, and randomly inhomogeneous media) corresponded to the properties of ideal Bessel beams, their spatial Fourier spectrum (the image in the focal plane of the lens) was, instead of an ideal ring, intertwined segments of arcs with phases shifted by π , the number of which was equal to the double value of the topological charge. This feature can be used, for example, in a demultiplexing unit of a free vortex-wave communication system or for identification of beam topological charge. We also revisited Young's double-slit diffraction and rotation of beams obstructed by a half-plane, previously applied to Laguerre-Gaussian beam characterization, in the case of the Bessel beams. The Young diffraction pattern demonstrated in this case a complicated intensity-phase distribution. It was shown that the Bessel beams formed by BPAs have two important advantages, which can be used in applications, in comparison with other methods of generation, e.g., a combination of an axicon lens with a spiral phase plate. Although the phase jumps of the axicons are designed for a determined wavelength (141 μ m in our case), the BPAs can form the beams at incident radiation with any wavelength, albeit with a reduced diffraction efficiency, and their cross section is the same for any wavelength.

Diffraction imaging for in situ characterization of double-crystal X-ray monochromators

DOE PAGES

Stoupin, Stanislav; Liu, Zunping; Heald, Steve M.; ...

2015-10-30

In this paper, imaging of the Bragg-reflected X-ray beam is proposed and validated as an in situ method for characterization of the performance of double-crystal monochromators under the heat load of intense synchrotron radiation. A sequence of images is collected at different angular positions on the reflectivity curve of the second crystal and analyzed. The method provides rapid evaluation of the wavefront of the exit beam, which relates to local misorientation of the crystal planes along the beam footprint on the thermally distorted first crystal. The measured misorientation can be directly compared with the results of finite element analysis. Finally,more » the imaging method offers an additional insight into the local intrinsic crystal quality over the footprint of the incident X-ray beam.« less

PEPSI spectro-polarimeter for the LBT

NASA Astrophysics Data System (ADS)

Strassmeier, Klaus G.; Hofmann, Axel; Woche, Manfred F.; Rice, John B.; Keller, Christoph U.; Piskunov, N. E.; Pallavicini, Roberto

2003-02-01

PEPSI (Postham Echelle Polarimetric and Spectroscopic Instrument) is to use the unique feature of the LBT and its powerful double mirror configuration to provide high and extremely high spectral resolution full-Stokes four-vector spectra in the wavelength range 450-1100nm. For the given aperture of 8.4m in single mirror mode and 11.8m in double mirror mode, and at a spectral resolution of 40,000-300,000 as designed for the fiber-fed Echelle spectrograph, a polarimetric accuracy between 10-4 and 10-2 can be reached for targets with visual magnitudes of up to 17th magnitude. A polarimetric accuracy better than 10-4 can only be reached for either targets brighter than approximately 10th magnitude together wiht a substantial trade-off wiht the spectral resolution or with spectrum deconvolution techniques. At 10-2, however, we will be able to observe the brightest AGNs down to 17th magnitude.

A specialized bioengineering ion beam line

NASA Astrophysics Data System (ADS)

Yu, L. D.; Sangyuenyongpipat, S.; Sriprom, C.; Thongleurm, C.; Suwanksum, R.; Tondee, N.; Prakrajang, K.; Vilaithong, T.; Brown, I. G.; Wiedemann, H.

2007-04-01

A specialized bioengineering ion beam line has recently been completed at Chiang Mai University to meet rapidly growing needs of research and application development in low-energy ion beam biotechnology. This beam line possesses special features: vertical main beam line, low-energy (30 keV) ion beams, double swerve of the beam, a fast pumped target chamber, and an in-situ atomic force microscope (AFM) system chamber. The whole beam line is situated in a bioclean environment, occupying two stories. The quality of the ion beam has been studied. It has proved that this beam line has significantly contributed to our research work on low-energy ion beam biotechnology.

Solar Imaging UV/EUV Spectrometers Using TVLS Gratings

NASA Astrophysics Data System (ADS)

Thomas, R. J.

2003-05-01

It is a particular challenge to develop a stigmatic spectrograph for UV/EUV wavelengths since the very low normal-incidence reflectance of standard materials most often requires that the design be restricted to a single optical element which must simultaneously provide both re-imaging and spectral dispersion. This problem has been solved in the past by the use of toroidal gratings with uniform line-spaced rulings (TULS). A number of solar EUV spectrometers have been based on such designs, including SOHO/CDS, Solar-B/EIS, and the sounding rockets SERTS and EUNIS. More recently, Kita, Harada, and collaborators have developed the theory of spherical gratings with varied line-space rulings (SVLS) operated at unity magnification, which have been flown on several astronomical satellite missions. We now combine these ideas into a spectrometer concept that puts varied-line space rulings onto toroidal gratings. Such TVLS designs are found to provide excellent imaging even at very large spectrograph magnifications and beam-speeds, permitting extremely high-quality performance in remarkably compact instrument packages. Optical characteristics of three new solar spectrometers based on this concept are described: SUMI and RAISE, two sounding rocket payloads, and NEXUS, currently being proposed as a Small-Explorer (SMEX) mission.

Toroidal Varied-Line Space (TVLS) Gratings

NASA Technical Reports Server (NTRS)

Thomas, Roger J.; Oegerle, William (Technical Monitor)

2002-01-01

It is a particular challenge to develop a stigmatic spectrograph for XUV wavelengths since the very low normal-incidence reflectance of standard materials most often requires that the design be restricted to a single optical element which must simultaneously provide both re-imaging and spectral dispersion. This problem has been solved in the past by the use of toroidal gratings with uniform line-spaced rulings (TULS). A number of solar EUV (Extreme Ultraviolet) spectrometers have been based on such designs, including SOHO/CDS, Solar-B/EIS, and the sounding rockets SERTS and EUNIS. More recently, Kita, Harada, and collaborators have developed the theory of spherical gratings with varied line-space rulings (SVLS) operated at unity magnification, which have been flown on several astronomical satellite missions. We now combine these ideas into a spectrometer concept that puts varied-line space rulings onto toroidal gratings. Such TVLS designs are found to provide excellent imaging even at very large spectrograph magnifications and beam-speeds, permitting extremely high-quality performance in remarkably compact instrument packages. Optical characteristics of two solar spectrometers based on this concept are described: SUMI, proposed as a sounding rocket experiment, and NEXUS, proposed for the Solar Dynamics Observatory mission.

VizieR Online Data Catalog: 89 Her interferometric study (Hillen+, 2013)

NASA Astrophysics Data System (ADS)

Hillen, M.; Verhoelst, T.; van Winckel, H.; Chesneau, O.; Hummel, C. A.; Monnier, J. D.; Farrington, C.; Tycner, C.; Mourard, D.; Ten Brummelaar, T.; Banerjee, D. P. K.; Zavala, R. T.

2013-08-01

89 Herculis was observed with the AMBER instrument on the VLTI using the Auxiliary Telescopes (ATs) in 2007, 2008, and 2012, all in the low-spectral-resolution (R=30) mode covering the H and K bands with detector integration times (DITs) of 25 and 50ms and without the use of the fringe tracker FINITO. Both the CLASSIC and CLIMB beam combiners on the Georgia State University CHARA Array interferometer were used to conduct observations in the H and K bands.In May 2012 observations were performed with the sensitive two-beam CLASSIC beam combiner in both H and K band. Three-beam CLIMB observations, in H and K band, were also obtained during three nights in July 2012. We retrieved and calibrated observations from the PTI archive. 89 Her was observed during 30 nights between 1999 and 2003, equally spread over the H and K bands. Eight and 15 observations of 89 Her were obtained at the IOTA interferometer on 2003 June 15 and 16, respectively. Observations of 89 Her were carried out in October 2011 with the NPOI. Two observations were performed in June and August 2011 with the Visible spEctroGraph And Polarimeter (VEGA instrument) integrated within the CHARA Array. (2 data files).

Improved double-pass michelson interferometer

NASA Technical Reports Server (NTRS)

Schindler, R. A.

1978-01-01

Interferometer design separates beams by offsetting centerlines of cat's-eye retroreflectors vertically rather than horizontally. Since beam splitter is insensitive to minimum-thickness condition in this geometry, relatively-low-cost, optically flat plate can be used.

Operation of the CAPRICE electron cyclotron resonance ion source applying frequency tuning and double frequency heating.

PubMed

Maimone, F; Tinschert, K; Celona, L; Lang, R; Mäder, J; Rossbach, J; Spädtke, P

2012-02-01

The properties of the electromagnetic waves heating the electrons of the ECR ion sources (ECRIS) plasma affect the features of the extracted ion beams such as the emittance, the shape, and the current, in particular for higher charge states. The electron heating methods such as the frequency tuning effect and the double frequency heating are widely used for enhancing the performances of ECRIS or even for the routine operation during the beam production. In order to better investigate these effects the CAPRICE ECRIS has been operated using these techniques. The ion beam properties for highly charged ions have been measured with beam diagnostic tools. The reason of the observed variations of this performance can be related to the different electromagnetic field patterns, which are changing inside the plasma chamber when the frequency is varying.

Plasma response to the injection of an electron beam

NASA Technical Reports Server (NTRS)

Singh, N.; Schunk, R. W.

1984-01-01

The results of Vlasov-Poisson-solver numerical simulations of the detailed temporal response of a Maxwellian plasma to the sudden injection of an electron beam are presented in graphs and maps and discussed. Phenomena characterized include ion bursts, electron shocks and holes, plasma heating and expulsion, density gradients; cavitons, deep-density-front and solitary-pulse propagation down the density gradient, and Bunemann-mode excitation leading to formation of a virtual cathode and double layers which are at first monotonic or have low-potential-side dips or high-potential-side bumps and become strong as the electron-current density decreases. The strength of the double layer is found to be roughly proportional to the beam energy.

Numerically simulated two-dimensional auroral double layers

NASA Technical Reports Server (NTRS)

Borovsky, J. E.; Joyce, G.

1983-01-01

A magnetized 2 1/2-dimensional particle-in-cell system which is periodic in one direction and bounded by reservoirs of Maxwellian plasma in the other is used to numerically simulate electrostatic plasma double layers. For the cases of both oblique and two-dimensional double layers, the present results indicate periodic instability, Debye length rather than gyroradii scaling, and low frequency electrostatic turbulence together with electron beam-excited electrostatatic electron-cyclotron waves. Estimates are given for the thickness of auroral doule layers, as well as the separations within multiple auroral arcs. Attention is given to the temporal modulation of accelerated beams, and the possibilities for ion precipitation and ion conic production by the double layer are hypothesized. Simulations which include the atmospheric backscattering of electrons imply the action of an ionospheric sheath which accelerates ionospheric ions upward.

Design and prototyping of HL-LHC double quarter wave crab cavities for SPS test

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

Verdu-Andres, S.; Skaritka, J.; Wu, Q.

2015-05-03

The LHC high luminosity project envisages the use of the crabbing technique for increasing and levelling the LHC luminosity. Double Quarter Wave (DQW) resonators are compact cavities especially designed to meet the technical and performance requirements for LHC beam crabbing. Two DQW crab cavities are under fabrication and will be tested with beam in the Super Proton Synchrotron (SPS) at CERN by 2017. This paper describes the design and prototyping of the DQW crab cavities for the SPS test.

Design and Fabrication of 1D and 2D Micro Scanners Actuated by Double Layered Lead Zirconate Titanate (PZT) Bimorph Beams

NASA Astrophysics Data System (ADS)

Tsaur, Jiunnjye; Zhang, Lulu; Maeda, Ryutaro; Matsumoto, Sohei; Khumpuang, Sommawan

2002-06-01

Micro scanners including 1D scanner beams and 2D scanning micromirrors are designed and fabricated. In order to yield large bending force, the sol-gel derived double layered lead zirconate titanate (PZT) structures are developed to be the actuator components. In our developed fabrication process, the use of thermal treatment and the addition of one platinium/titanium film played an important role to yield the well-crystallized perovskite phase and decrease the residual strss of total cantilever structures successfully. In the case of 1D scanner beams with the size of 750× 230 μm2, the optical scanning angle was 41.2 deg with respect to actuation with AC 5 V at 2706 Hz. Under the applied bias of 10 V, the bimorph beam bended upward and the deflection angle of 34.3 deg was measured. A 2D scanning micromirror supported by four suspended double layered PZT actuators was designed to rotate around two orthogonal axes by the operation at different resonant frequencies. While resonating with AC 7.5 V at 3750 Hz and 5350 Hz, the maximum scanning area of 24\\circ× 26\\circ was obtained.

Antiproton beam polarizer using a dense polarized target

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

Wojtsekhowski, Bogdan

2011-05-01

We describe considerations regarding the spin filtering method for the antiproton beam. The proposed investigation of the double polarization cross section for antiproton to nucleon interaction is outlined. It will use a single path of the antiproton beam through a dense polarized target, e.g. 3He or CH2, followed by a polarimeter.

Enhanced optical limiting effects in a double-decker bis(phthalocyaninato) rare earth complex using radially polarized beams

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

Wu, Jia-Lu; Gu, Bing, E-mail: gubing@seu.edu.cn; Liu, Dahui

2014-10-27

Optical limiting (OL) effects can be enhanced by exploiting various limiting mechanisms and by designing nonlinear optical materials. In this work, we present the large enhancement of OL effects by manipulating the polarization distribution of the light field. Theoretically, we develop the Z-scan and nonlinear transmission theories on a two-photon absorber under the excitation of cylindrical vector beams. It is shown that both the sensitivity of Z-scan technique and the OL effect using radially polarized beams have the large enhancement compared with that using linearly polarized beams (LPBs). Experimentally, we investigate the nonlinear absorption properties of a double-decker Pr[Pc(OC{sub 8}H{submore » 17}){sub 8}]{sub 2} rare earth complex by performing Z-scan measurements with femtosecond-pulsed radially polarized beams at 800 nm wavelength. The observed two-photon absorption process, which originates from strong intramolecular π–π interaction, is exploited for OL application. The results demonstrate the large enhancement of OL effects using radially polarized beams instead of LPBs.« less

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.

First storage of ion beams in the Double Electrostatic Ion-Ring Experiment: DESIREE.

PubMed

Schmidt, H T; Thomas, R D; Gatchell, M; Rosén, S; Reinhed, P; Löfgren, P; Brännholm, L; Blom, M; Björkhage, M; Bäckström, E; Alexander, J D; Leontein, S; Hanstorp, D; Zettergren, H; Liljeby, L; Källberg, A; Simonsson, A; Hellberg, F; Mannervik, S; Larsson, M; Geppert, W D; Rensfelt, K G; Danared, H; Paál, A; Masuda, M; Halldén, P; Andler, G; Stockett, M H; Chen, T; Källersjö, G; Weimer, J; Hansen, K; Hartman, H; Cederquist, H

2013-05-01

We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (C(n)(-), n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C2 (-) molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s ± 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10(-14) mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.

Grism and immersion grating for space telescope

NASA Astrophysics Data System (ADS)

Ebizuka, Noboru; Oka, Kiko; Yamada, Akiko; Ishikawa, Mami; Kashiwagi, Masako; Kodate, Kashiko; Hirahara, Yasuhiro; Sato, Shuji; Kawabata, Koji S.; Wakaki, Moriaki; Morita, Shin-ya; Simizu, Tomoyuki; Yin, Shaohui; Omori, Hitoshi; Iye, Masanori

2017-11-01

The grism is a versatile dispersion element for an astronomical instrument ranging from ultraviolet to infrared. Major benefit of using a grism in a space application, instead of a reflection grating, is the size reduction of optical system because collimator and following optical elements could locate near by the grism. The surface relief (SR) grism is consisted a transmission grating and a prism, vertex angle of which is adjusted to redirect the diffracted beam straight along the direct vision direction at a specific order and wavelength. The volume phase holographic (VPH) grism consists a thick VPH grating sandwiched between two prisms, as specific order and wavelength is aligned the direct vision direction. The VPH grating inheres ideal diffraction efficiency on a higher dispersion application. On the other hand, the SR grating could achieve high diffraction efficiency on a lower dispersion application. Five grisms among eleven for the Faint Object Camera And Spectrograph (FOCAS) of the 8.2m Subaru Telescope with the resolving power from 250 to 3,000 are SR grisms fabricated by a replication method. Six additional grisms of FOCAS with the resolving power from 3,000 to 7,000 are VPH grisms. We propose "Quasi-Bragg grism" for a high dispersion spectroscopy with wide wavelength range. The germanium immersion grating for instance could reduce 1/64 as the total volume of a spectrograph with a conventional reflection grating since refractive index of germanium is over 4.0 from 1.6 to 20 μm. The prototype immersion gratings for the mid-InfraRed High dispersion Spectrograph (IRHS) are successfully fabricated by a nano-precision machine and grinding cup of cast iron with electrolytic dressing method.

A 2.5 kW advanced technology ion thruster

NASA Technical Reports Server (NTRS)

Poeschel, R. L.

1974-01-01

A program has been conducted in order to improve the performance characteristics of 30 cm thrusters. This program was divided into three distinct, but related tasks: (1) the discharge chamber and component design modifications proposed for inclusion in the engineering model thruster were evaluated and engineering specifications were verified; (2) thrust losses which result from the contributions of double charged ions and nonaxial ion trajectories to the ion beam current were measured and (3) the specification and verification of power processor and control requirements of the engineering model thruster design were demonstrated. Proven design modifications which provide improved efficiencies are incorporated into the engineering model thruster during a structural re-design without introducing additional delay in schedule or new risks. In addition, a considerable amount of data is generated on the relation of double ion production and beam divergence to thruster parameters. Overall thruster efficiency is increased from 68% to 71% at full power, including corrections for double ion and beam divergence thrust losses.

1.6  MW peak power, 90  ps all-solid-state laser from an aberration self-compensated double-passing end-pumped Nd:YVO₄ rod amplifier.

PubMed

Wang, Chunhua; Liu, Chong; Shen, Lifeng; Zhao, Zhiliang; Liu, Bin; Jiang, Hongbo

2016-03-20

In this paper a delicately designed double-passing end-pumped Nd:YVO₄ rod amplifier is reported that produces 10.2 W average laser output when seeded by a 6 mW Nd:YVO₄ microchip laser at a repetition rate of 70 kHz with pulse duration of 90 ps. A pulse peak power of ∼1.6  MW and pulse energy of ∼143  μJ is achieved. The beam quality is well preserved by a double-passing configuration for spherical-aberration compensation. The laser-beam size in the amplifier is optimized to prevent the unwanted damage from the high pulse peak-power density. This study provides a simple and robust picosecond all-solid-state master oscillator power amplifier system with both high peak power and high beam quality, which shows great potential in the micromachining.

Development of low-noise CCD drive electronics for the world space observatory ultraviolet spectrograph subsystem

NASA Astrophysics Data System (ADS)

Salter, Mike; Clapp, Matthew; King, James; Morse, Tom; Mihalcea, Ionut; Waltham, Nick; Hayes-Thakore, Chris

2016-07-01

World Space Observatory Ultraviolet (WSO-UV) is a major Russian-led international collaboration to develop a large space-borne 1.7 m Ritchey-Chrétien telescope and instrumentation to study the universe at ultraviolet wavelengths between 115 nm and 320 nm, exceeding the current capabilities of ground-based instruments. The WSO Ultraviolet Spectrograph subsystem (WUVS) is led by the Institute of Astronomy of the Russian Academy of Sciences and consists of two high resolution spectrographs covering the Far-UV range of 115-176 nm and the Near-UV range of 174-310 nm, and a long-slit spectrograph covering the wavelength range of 115-305 nm. The custom-designed CCD sensors and cryostat assemblies are being provided by e2v technologies (UK). STFC RAL Space is providing the Camera Electronics Boxes (CEBs) which house the CCD drive electronics for each of the three WUVS channels. This paper presents the results of the detailed characterisation of the WUVS CCD drive electronics. The electronics include a novel high-performance video channel design that utilises Digital Correlated Double Sampling (DCDS) to enable low-noise readout of the CCD at a range of pixel frequencies, including a baseline requirement of less than 3 electrons rms readout noise for the combined CCD and electronics system at a readout rate of 50 kpixels/s. These results illustrate the performance of this new video architecture as part of a wider electronics sub-system that is designed for use in the space environment. In addition to the DCDS video channels, the CEB provides all the bias voltages and clocking waveforms required to operate the CCD and the system is fully programmable via a primary and redundant SpaceWire interface. The development of the CEB electronics design has undergone critical design review and the results presented were obtained using the engineering-grade electronics box. A variety of parameters and tests are included ranging from general system metrics, such as the power and mass, to more detailed analysis of the video performance including noise, linearity, crosstalk, gain stability and transient response.

Guiding and focusing of fast electron beams produced by ultra-intense laser pulse using a double cone funnel target

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

Zhang, Wen-shuai; Cai, Hong-bo, E-mail: Cai-hongbo@iapcm.ac.cn; HEDPS, Center for Applied Physics and Technology, Peking University, Beijing 100871

A novel double cone funnel target design aiming at efficiently guiding and focusing fast electron beams produced in high intensity (>10{sup 19 }W/cm{sup 2}) laser-solid interactions is investigated via two-dimensional particle-in-cell simulations. The forward-going fast electron beams are shown to be directed and focused to a smaller size in comparison with the incident laser spot size. This plasma funnel attached on the cone target guides and focuses electrons in a manner akin to the control of liquid by a plastic funnel. Such device has the potential to add substantial design flexibility and prevent inefficiencies for important applications such as fast ignition.more » Two reasons account for the collimation of fast electron beams. First, the sheath electric fields and quasistatic magnetic fields inside the vacuum gap of the double cone provide confinement of the fast electrons in the laser-plasma interaction region. Second, the interface magnetic fields inside the beam collimator further guide and focus the fast electrons during the transport. The application of this technique to cone-guided fast ignition is considered, and it is shown that it can enhance the laser energy deposition in the compressed fuel plasma by a factor of 2 in comparison with the single cone target case.« less

Helium-induced one-neutron transfer to levels in 162Dy

NASA Astrophysics Data System (ADS)

Andersen, E.; Helstrup, H.; Løvhøiden, G.; Thorsteinsen, T. F.; Guttormsen, M.; Messelt, S.; Tveter, T. S.; Hofstee, M. A.; Schippers, J. M.; van der Werf, S. Y.

1992-12-01

Levels in 162Dy have been studied in the 161Dy(α, 3He) and 163Dy( 3He, α) reactions with 50 MeV α- and 3He-beams from the KVI cyclotron in Groningen. The reaction products were analyzed in the QMG/2 magnetic spectrograph and registered in a two-dimensional detector system. The observed levels and cross sections are well described by the Nilsson model with the exception of the three levels at 1578, 1759 and 1990 keV. The present data combined with previous results strongly indicate that these levels are the spin-4, -6, and -8 members of the S-band.

Performance of multilayer coated diffraction gratings in the EUV

NASA Technical Reports Server (NTRS)

Keski-Kuha, Ritva A. M.; Thomas, Roger J.; Gum, Jeffrey S.; Condor, Charles E.

1990-01-01

The effect of multilayer coating application on the performance of a diffraction grating in the EUV spectral region was evaluated by examining the performance of a 3600-line/mm and a 1200-line/mm replica blazed gratings, designed for operation in the 300-A spectral region in first order. A ten-layer IrSi multilayer optimized for 304 A was deposited using electron-beam evaporation. The grating efficiency was measured on the SURF II calibration beamline in a chamber designed for calibrating the solar EUV rocket telescope and spectrograph multilayer coatings. A significant (by a factor of about 7) enhancement in grating efficiency in the 300-A region was demonstrated.

Transitions of the type 2s-2p in oxygenlike Y, Zr, and Nb

NASA Technical Reports Server (NTRS)

Behring, W. E.; Brown, C. M.; Feldman, U.; Seely, J. F.; Reader, J.

1986-01-01

Transitions of the type 2s-2p in the oxygenlike ions Y XXXII, Zr XXXIII, and Nb XXXIV were identified in spectra recorded at the University of Rochester's Omega laser facility. Solid targets were spherically irradiated by 24 beams of frequency-tripled (351-nm) Nd-glass laser radiation. The spectra were photographed with a 3-m grazing-incidence spectrograph. The identified transitions of the oxygenlike ions are in the range 30 to 73 A. The wavelengths for the magnetic-dipole transitions within the 2s2p4 ground configurations of these ions are predicted from the experimental energy levels.

PLASMA EMISSION BY COUNTER-STREAMING ELECTRON BEAMS

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

Ziebell, L. F.; Petruzzellis, L. T.; Gaelzer, R.

2016-02-10

The radiation emission mechanism responsible for both type-II and type-III solar radio bursts is commonly accepted as plasma emission. Recently Ganse et al. suggested that type-II radio bursts may be enhanced when the electron foreshock geometry of a coronal mass ejection contains a double hump structure. They reasoned that the counter-streaming electron beams that exist between the double shocks may enhance the nonlinear coalescence interaction, thereby giving rise to more efficient generation of radiation. Ganse et al. employed a particle-in-cell simulation to study such a scenario. The present paper revisits the same problem with EM weak turbulence theory, and showmore » that the fundamental (F) emission is not greatly affected by the presence of counter-streaming beams, but the harmonic (H) emission becomes somewhat more effective when the two beams are present. The present finding is thus complementary to the work by Ganse et al.« less

Stability Formulation for Integrated Opto-mechanic Phase Shifters.

PubMed

Ozer, Yigit; Kocaman, Serdar

2018-01-31

Stability of opto-mechanical phase shifters consisting of waveguides and non-signal carrying control beams is investigated thoroughly and a formula determining the physical limitations has been proposed. Suggested formulation is not only beneficial to determine physical strength of the system but also advantageous to guess the response of the output to the fabrication errors. In the iterative analysis of cantilever and double-clamped beam geometrical configurations, the stability condition is revealed under the strong inter-dependence of the system parameters such as input power, device length and waveguide separation. Numerical calculations involving effective index modifications and opto-mechanic movements show that well-known cantilever beams are unstable and inadequate to generate φ = 180° phase difference, while double-clamped beam structures can be utilized to build functional devices. Ideal operation conditions are also presented in terms of both the device durability and the controllability of phase evolution.

Soft X-ray holographic grating beam splitter including a double frequency grating for interferometer pre-alignment.

PubMed

Liu, Ying; Tan, Xin; Liu, Zhengkun; Xu, Xiangdong; Hong, Yilin; Fu, Shaojun

2008-09-15

Grating beam splitters have been fabricated for soft X-ray Mach- Zehnder interferometer using holographic interference lithography. The grating beam splitter consists of two gratings, one works at X-ray laser wavelength of 13.9 nm with the spatial frequency of 1000 lines/mm as the operation grating, the other works at visible wavelength of 632.8 nm for pre-aligning the X-ray interferometer with the spatial frequency of 22 lines/mm as the pre-alignment grating. The two gratings lie vertically on the same substrate. The main feature of the beam splitter is the use of low-spatial- frequency beat grating of a holographic double frequency grating as the pre-alignment grating of the X-ray interferometer. The grating line parallelism between the two gratings can be judged by observing the diffraction patterns of the pre-alignment grating directly.

Measurement of the Double Polarization Observable E in π0 and η Photoproduction off Protons with the Cbelsa/taps Experiment

NASA Astrophysics Data System (ADS)

Gottschall, M.; Müller, J.

2014-01-01

Double polarization experiments using a longitudinally or transversely polarized frozen-spin-butanol target and a linearly or circularly polarized photon beam were performed with the CBELSA/TAPS experiment at the electron accelerator ELSA. With its nearly 4π angular coverage, this setup is very well suited to study neutral meson photoproduction off the nucleon up to beam energies of 3.2 GeV. Results obtained for the double polarization observable E in neutral pion and eta photoproduction show the large sensitivity of the data on the contributing resonances. If the data are compared to the predictions of state of the art partial wave analyses, large discrepancies are observed.

Gain measurements and spatial coherence in neon-like x-ray lasers

NASA Astrophysics Data System (ADS)

Krishnan, J.; Cairns, C.; Dwivedi, L.; Holden, M.; Key, M. H.; Lewis, C. L. S.; MacPhee, A.; Neely, D.; Norreys, P. A.; Pert, G. J.; Ramsden, S. A.; Smith, C. G.; Tallents, G. J.; Zhang, J.

1995-05-01

Many of the applications with x-ray lasers require high quality output radiation with properties such as short wavelength and a high degree of coherence (longitudinal and spatial). Ne-like Yttrium (Z=39) is potentially a bright and monochromatic XUV lasing medium. The output at 15.5 nm is monochromatic due to the overlap of the J=2-1 and J=0-1 lines. A gain coefficient of 3±1 was obtained at 15.5 nm by irradiating 100 μm wide yttrium stripes at 6×1013 W/cm2 with 1.06 μm, 650 ps pulses from the Rutherford Appleton Laboratory VULCAN laser. We have investigated improving x-ray laser spatial coherence utilizing a series of amplifiers instead of the standard double target configuration. An ``injector-amplifier'' scheme was successfully demonstrated with the Ne-like Ge x-ray laser. A spatially small and coherent part of the 23 nm beam from the standard double target geometry has been relayed using a W/Si multilayer mirror onto a single or double target configuration situated at a distance of ˜1.5 m from the mirror and pumped by two 150 mm diameter beams of VULCAN laser. A beam ``foot-print monitor'' was employed with a flat mirror to relay 23 nm output onto a film pack to record the spatial variation of the x-ray laser beam. Analyzing the fringes obtained through a cross-wire placed in front of the beam shows that an increase in spatial coherence was achieved by adding amplifiers to the x-ray laser beam line.

Optics of a Double Focussing Magnetic Sector by Fringe Effect; OPTIQUE D'UN SECTEUR MAGNETIQUE A DOUBLE FOCALISATION PAR EFFET DE FRANCES

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

Krafft, J.

1960-01-01

A general study is made of the optical elements of a double-fccusing magnetic sector by the fringe effect, with a view to its application to the monochromation of the proton, deuteron, or triton beam of the 1.4 Mev accelerator. (auth)

Low-metallicity (sub-SMC) massive stars

NASA Astrophysics Data System (ADS)

Garcia, Miriam; Herrero, Artemio; Najarro, Francisco; Camacho, Inés; Lennon, Daniel J.; Urbaneja, Miguel A.; Castro, Norberto

2017-11-01

The double distance and metallicity frontier marked by the SMC has been finally broken with the aid of powerful multi-object spectrographs installed at 8-10m class telescopes. VLT, GTC and Keck have enabled studies of massive stars in dwarf irregular galaxies of the Local Group with poorer metal-content than the SMC. The community is working to test the predictions of evolutionary models in the low-metallicity regime, set the new standard for the metal-poor high-redshift Universe, and test the extrapolation of the physics of massive stars to environments of decreasing metallicity. In this paper, we review current knowledge on this topic.

Double Cantilever Beam Fracture Toughness Testing of Several Composite Materials

NASA Technical Reports Server (NTRS)

Kessler, Jeff A.; Adams, Donald F.

1992-01-01

Double-cantilever beam fracture toughness tests were performed by the Composite Materials Research Group on several different unidirectional composite materials provided by NASA Langley Research Center. The composite materials consisted of Hercules IM-7 carbon fiber and various matrix resin formulations. Multiple formulations of four different families of matrix resins were tested: LaRC - ITPI, LaRC - IA, RPT46T, and RP67/RP55. Report presents the materials tested and pertinent details supplied by NASA. For each material, three replicate specimens were tested. Multiple crack extensions were performed on each replicate.

LOITA: Lunar Optical/Infrared Telescope Array

NASA Technical Reports Server (NTRS)

1993-01-01

LOITA (Lunar Optical/Infrared Telescope Array) is a lunar-based interferometer composed of 18 alt-azimuth telescopes arranged in a circular geometry. This geometry results in excellent uv coverage and allows baselines up to 5 km long. The angular resolution will be 25 micro-arcsec at 500 nm and the main spectral range of the array will be 200 to 1100 nm. For infrared planet detection, the spectral range may be extended to nearly 10 mu m. The telescope mirrors have a Cassegrain configuration using a 1.75 m diameter primary mirror and a 0.24 m diameter secondary mirror. A three-stage (coarse, intermediate, and fine) optical delay system, controlled by laser metrology, is used to equalize path lengths from different telescopes to within a few wavelengths. All instruments and the fine delay system are located within the instrument room. Upon exiting the fine delay system, all beams enter the beam combiner and are then directed to the various scientific instruments and detectors. The array instrumentation will consist of CCD detectors optimized for both the visible and infrared as well as specially designed cameras and spectrographs. For direct planet detection, a beam combiner employing achromatic nulling interferometry will be used to reduce star light (by several orders of magnitude) while passing the planet light. A single telescope will be capable of autonomous operation. This telescope will be equipped with four instruments: wide field and planetary camera, faint object camera, high resolution spectrograph, and faint object spectrograph. These instruments will be housed beneath the telescope. The array pointing and control system is designed to meet the fine pointing requirement of one micro-arcsec stability and to allow precise tracking of celestial objects for up to 12 days. During the lunar night, the optics and the detectors will be passively cooled to 70-80 K temperature. To maintain a continuous communication with the earth a relay satellite placed at the L4 libration point will be used in conjunction with the Advanced Tracking and Data Relay Satellite System (ATDRSS). Electrical power of about 10 kW will be supplied by a nuclear reactor based on the SP-100 technology. LOITA will be constructed in three phases of six telescopes each. The total mass of the first operational phase is estimated at 58,820 kg. The cost of the fully operational first phase of the observatory is estimated at $8.9 billion. LOITA's primary objectives will be to detect and characterize planets around nearby stars (up to ten parsec away), study physics of collapsed stellar objects, solar/stellar surface features and the processes in nuclear regions of galaxies and quasars. An interferometric array such as LOITA will be capable of achieving resolutions three orders of magnitude greater than Hubble's design goal. LOITA will also be able to maintain higher signal to noise ratios than are currently attainable due to long observation times available on the moon.

The deterministic optical alignment of the HERMES spectrograph

NASA Astrophysics Data System (ADS)

Gers, Luke; Staszak, Nicholas

2014-07-01

The High Efficiency and Resolution Multi Element Spectrograph (HERMES) is a four channel, VPH-grating spectrograph fed by two 400 fiber slit assemblies whose construction and commissioning has now been completed at the Anglo Australian Telescope (AAT). The size, weight, complexity, and scheduling constraints of the system necessitated that a fully integrated, deterministic, opto-mechanical alignment system be designed into the spectrograph before it was manufactured. This paper presents the principles about which the system was assembled and aligned, including the equipment and the metrology methods employed to complete the spectrograph integration.

A Study on Double Event Detection for PHENIX at RHIC

NASA Astrophysics Data System (ADS)

Vazquez-Carson, Sebastian; Phenix Collaboration

2016-09-01

Many measurements made in Heavy Ion experiments such as PHENIX at RHIC focus on geometrical properties because phenomena such as collective flow give insight into quark-gluon plasma and the strong nuclear force. As part of this investigation, PHENIX has taken data in 2016 for deuteron on gold collisions at several energies. An acceptable luminosity is achieved by injecting up to 120 separate bunches each with billions of ions into the storage ring, from which two, separate beams are made to collide. This method has a drawback as there is a chance for multiple pairs of nuclei to collide in a single bunch crossing. Data taken in a double event cannot be separated into two independent events and has no clear interpretation. This effect's magnitude is estimated and incorporated in published results as a systematic uncertainty and studies on this topic have already been conducted within PHENIX. I develop several additional algorithms to flag multiple interaction events by examining the time dependence of data from the two Beam-Beam Counters - detectors surrounding the beam pipe on opposite ends of the interaction region. The algorithms are tested with data, in which events with double interactions are artificially produced using low luminosity data. I am working at the University of Colorado at Boulder on behalf of the PHENIX collaboration.

Beam-tracing model for predicting sound fields in rooms with multilayer bounding surfaces

NASA Astrophysics Data System (ADS)

Wareing, Andrew; Hodgson, Murray

2005-10-01

This paper presents the development of a wave-based room-prediction model for predicting steady-state sound fields in empty rooms with specularly reflecting, multilayer surfaces. A triangular beam-tracing model with phase, and a transfer-matrix approach to model the surfaces, were involved. Room surfaces were modeled as multilayers of fluid, solid, or porous materials. Biot theory was used in the transfer-matrix formulation of the porous layer. The new model consisted of the transfer-matrix model integrated into the beam-tracing algorithm. The transfer-matrix model was validated by comparing predictions with those by theory, and with experiment. The test surfaces were a glass plate, double drywall panels, double steel panels, a carpeted floor, and a suspended-acoustical ceiling. The beam-tracing model was validated in the cases of three idealized room configurations-a small office, a corridor, and a small industrial workroom-with simple boundary conditions. The number of beams, the reflection order, and the frequency resolution required to obtain accurate results were investigated. Beam-tracing predictions were compared with those by a method-of-images model with phase. The model will be used to study sound fields in rooms with local- or extended-reaction multilayer surfaces.

Large-angle production of charged pions with incident pion beams on nuclear targets

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

Apollonio, M.; Chimenti, P.; Giannini, G.

2009-12-15

Measurements of the double-differential {pi}{sup {+-}} production cross section in the range of momentum 100{<=}p{<=}800 MeV/c and angle 0.35{<=}{theta}{<=}2.15 rad using {pi}{sup {+-}} beams incident on beryllium, aluminum, carbon, copper, tin, tantalum, and lead targets are presented. The data were taken with the large-acceptance hadron production (HARP) detector in the T9 beam line of the CERN Proton Synchrotron. The secondary pions were produced by beams in a momentum range from 3 to 12.9GeV/c hitting a solid target with a thickness of 5% of a nuclear interaction length. The tracking and identification of the produced particles was performed using a small-radiusmore » cylindrical time projection chamber placed inside a solenoidal magnet. Incident particles were identified by an elaborate system of beam detectors. Results are obtained for the double-differential cross sections d{sup 2}{sigma}/dp d{theta} at six incident-beam momenta. Data at 3,5,8, and 12GeV/c are available for all targets, while additional data at 8.9 and 12.9GeV/c were taken in positive particle beams on Be and Al targets, respectively. The measurements are compared with several generators of GEANT4 and the MARS Monte Carlo simulation.« less

THE RADIAL VELOCITY TATOOINE SEARCH FOR CIRCUMBINARY PLANETS: PLANET DETECTION LIMITS FOR A SAMPLE OF DOUBLE-LINED BINARY STARS-INITIAL RESULTS FROM KECK I/HIRES, SHANE/CAT/HAMSPEC, AND TNG/SARG OBSERVATIONS

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

Konacki, Maciej; Helminiak, Krzysztof G.; Muterspaugh, Matthew W.

2009-10-10

We present preliminary results of the first and on-going radial velocity survey for circumbinary planets. With a novel radial velocity technique employing an iodine absorption cell, we achieve an unprecedented radial velocity (RV) precision of up to 2 m s{sup -1} for double-lined binary stars. The high-resolution spectra collected with the Keck I/Hires, TNG/Sarg, and Shane/CAT/Hamspec telescopes/spectrographs over the years 2003-2008 allow us to derive RVs and compute planet detection limits for 10 double-lined binary stars. For this initial sample of targets, we can rule out planets on dynamically stable orbits with masses as small as approx0.3 to 3 Mmore » {sub Jup} for the orbital periods of up to approx5.3 years. Even though the presented sample of stars is too small to make any strong conclusions, it is clear that the search for circumbinary planets is now technique-wise possible and eventually will provide new constraints for the planet formation theories.« less

Bifurcations and Chaos of AN Immersed Cantilever Beam in a Fluid and Carrying AN Intermediate Mass

NASA Astrophysics Data System (ADS)

AL-QAISIA, A. A.; HAMDAN, M. N.

2002-06-01

The concern of this work is the local stability and period-doubling bifurcations of the response to a transverse harmonic excitation of a slender cantilever beam partially immersed in a fluid and carrying an intermediate lumped mass. The unimodal form of the non-linear dynamic model describing the beam-mass in-plane large-amplitude flexural vibration, which accounts for axial inertia, non-linear curvature and inextensibility condition, developed in Al-Qaisia et al. (2000Shock and Vibration7 , 179-194), is analyzed and studied for the resonance responses of the first three modes of vibration, using two-term harmonic balance method. Then a consistent second order stability analysis of the associated linearized variational equation is carried out using approximate methods to predict the zones of symmetry breaking leading to period-doubling bifurcation and chaos on the resonance response curves. The results of the present work are verified for selected physical system parameters by numerical simulations using methods of the qualitative theory, and good agreement was obtained between the analytical and numerical results. Also, analytical prediction of the period-doubling bifurcation and chaos boundaries obtained using a period-doubling bifurcation criterion proposed in Al-Qaisia and Hamdan (2001 Journal of Sound and Vibration244, 453-479) are compared with those of computer simulations. In addition, results of the effect of fluid density, fluid depth, mass ratio, mass position and damping on the period-doubling bifurcation diagrams are studies and presented.

The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. I. Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29

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

Kowalski, Adam F.; Allred, Joel C.; Daw, Adrian

2017-02-10

The 2014 March 29 X1 solar flare (SOL20140329T17:48) produced bright continuum emission in the far- and near-ultraviolet (NUV) and highly asymmetric chromospheric emission lines, providing long-sought constraints on the heating mechanisms of the lower atmosphere in solar flares. We analyze the continuum and emission line data from the Interface Region Imaging Spectrograph (IRIS) of the brightest flaring magnetic footpoints in this flare. We compare the NUV spectra of the brightest pixels to new radiative-hydrodynamic predictions calculated with the RADYN code using constraints on a nonthermal electron beam inferred from the collisional thick-target modeling of hard X-ray data from Reuven Ramatymore » High Energy Solar Spectroscopic Imager . We show that the atmospheric response to a high beam flux density satisfactorily achieves the observed continuum brightness in the NUV. The NUV continuum emission in this flare is consistent with hydrogen (Balmer) recombination radiation that originates from low optical depth in a dense chromospheric condensation and from the stationary beam-heated layers just below the condensation. A model producing two flaring regions (a condensation and stationary layers) in the lower atmosphere is also consistent with the asymmetric Fe ii chromospheric emission line profiles observed in the impulsive phase.« less

The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. I. Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29

NASA Technical Reports Server (NTRS)

Kowalski, Adam F.; Allred, Joel C.; Daw, Adrian N.; Cauzzi, Gianna; Carlsson, Mats

2017-01-01

The 2014 March 29 X1 solar flare (SOL20140329T17:48) produced bright continuum emission in the far- and near-ultraviolet (NUV) and highly asymmetric chromospheric emission lines, providing long-sought constraints on the heating mechanisms of the lower atmosphere in solar flares. We analyze the continuum and emission line data from the Interface Region Imaging Spectrograph (IRIS) of the brightest flaring magnetic footpoints in this flare. We compare the NUV spectra of the brightest pixels to new radiative-hydrodynamic predictions calculated with the RADYN code using constraints on a nonthermal electron beam inferred from the collisional thick-target modeling of hard X-ray data from Reuven Ramaty High Energy Solar Spectroscopic Imager. We show that the atmospheric response to a high beam flux density satisfactorily achieves the observed continuum brightness in the NUV. The NUV continuum emission in this flare is consistent with hydrogen (Balmer) recombination radiation that originates from low optical depth in a dense chromospheric condensation and from the stationary beam-heated layers just below the condensation. A model producing two flaring regions (a condensation and stationary layers) in the lower atmosphere is also consistent with the asymmetric Fe II chromospheric emission line profiles observed in the impulsive phase.

On the influence of monochromator thermal deformations on X-ray focusing

DOE PAGES

Antimonov, M. A.; Khounsary, A. M.; Sandy, A. R.; ...

2016-03-02

A cooled double crystal monochromator system is used on many high heat load X-ray synchrotron radiation beamlines in order to select, by diffraction, a narrow spectrum of the beam. Thermal deformation of the first crystal monochromator – and the potential loss of beam brightness – is often a concern. However, if downstream beam focusing is planned, the lensing effect of the monochromator must be considered even if thermal deformations are small. In this paper we report on recent experiments at an Advanced Photon Source (APS) beamline that focuses the X-ray beam using compound refractive lenses downstream of an X-ray monochromatormore » system. Increasing the X-ray beam power by increasing the storage ring current from 100 mA to 130 mA resulted in an effective doubling of the focal distance. We show quantitatively that this is due to a lensing effect of the distorted monochromator that results in the creation of a virtual source downstream of the actual source. Lastly, an analysis of the defocusing and options to mitigate this effect are explored.« less

Spatial Studies of Ion Beams in an Expanding Plasma

NASA Astrophysics Data System (ADS)

Aguirre, Evan; Good, Timothy; Scime, Earl; Thompson, Derek

2017-10-01

We report spatially resolved perpendicular and parallel ion velocity distribution function (IVDF) measurements in an expanding argon helicon plasma. The parallel IVDFs, obtained through laser induced fluorescence (LIF), show an ion beam with v 8 km/s flowing downstream that is confined to the center of the discharge. The ion beam is confined to within a few centimeters radially and is measurable for tens of centimeters axially before the LIF signal fades, likely a result of metastable quenching of the beam ions. The axial ion beam velocity slows in agreement with collisional processes. The perpendicular IVDFs show an ion population with a radially outward flow that increases with radial location. The DC electric field, electron temperature, and the plasma density in the double layer plume are all consistent with magnetic field aligned structures. The upstream and downstream electric field measurements show clear evidence of an ion hole that maps along the magnetic field at the edge of the plasma. Current theories and simulations of double layers, which are one-dimensional, completely miss these critically important two-dimensional features.

Large magnetic to electric field contrast in azimuthally polarized vortex beams generated by a metasurface (Presentation Recording)

NASA Astrophysics Data System (ADS)

Veysi, Mehdi; Guclu, Caner; Capolino, Filippo

2015-09-01

We investigate azimuthally E-polarized vortex beams with enhanced longitudinal magnetic field. Ideally, such beams possess strong longitudinal magnetic field on the beam axis where there is no electric field. First we formulate the electric field vector and the longitudinal magnetic field of an azimuthally E-polarized beam as an interference of right- and left-hand circularly polarized Laguerre Gaussian (LG) beams carrying the orbital angular momentum (OAM) states of -1 and +1, respectively. Then we propose a metasurface design that is capable of converting a linearly polarized Gaussian beam into an azimuthally E-polarized vortex beam with longitudinal magnetic field. The metasurface is composed of a rectangular array of double-layer double split-ring slot elements, though other geometries could be adopted as well. The element is specifically designed to have nearly a 180° transmission phase difference between the two polarization components along two orthogonal axes, similar to the optical axes of a half-wave plate. By locally rotating the optical axes of each metasurface element, the transmission phase profile of the circularly polarized waves over the metasurface can be tailored. Upon focusing of the generated vortex beam through a lens with a numerical aperture of 0.7, a 41-fold enhancement of the magnetic to electric field ratio is achieved on the beam axis with respect to that of a plane wave. Generation of beams with large magnetic field to electric field contrast can find applications in future spectroscopy systems based on magnetic dipole transitions, which are usually much weaker than electric dipole transitions.

Operational head-on beam-beam compensation with electron lenses in the Relativistic Heavy Ion Collider

DOE PAGES

Fischer, W.; Gu, X.; Altinbas, Z.; ...

2015-12-23

Head-on beam-beam compensation has been implemented in the Relativistic Heavy Ion Collider (RHIC) in order to increase the luminosity delivered to the experiments. We discuss the principle of combining a lattice for resonance driving term compensation and an electron lens for tune spread compensation. We describe the electron lens technology and its operational use. As of this date the implemented compensation scheme approximately doubled the peak and average luminosities.

Transport of ion beam in an annular magnetically expanding helicon double layer thruster

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

Zhang, Yunchao, E-mail: yunchao.zhang@anu.edu.au; Charles, Christine; Boswell, Rod

2014-06-15

An ion beam generated by an annular double layer has been measured in a helicon thruster, which sustains a magnetised low-pressure (5.0 × 10{sup −4} Torr) argon plasma at a constant radio-frequency (13.56 MHz) power of 300 W. After the ion beam exits the annular structure, it merges into a solid centrally peaked structure in the diffusion chamber. As the annular ion beam moves towards the inner region in the diffusion chamber, a reversed-cone plasma wake (with a half opening angle of about 30°) is formed. This process is verified by measuring both the radial and axial distributions of the beam potential and beammore » current. The beam potential changes from a two-peak radial profile (maximum value ∼ 30 V, minimum value ∼ 22.5 V) to a flat (∼28 V) along the axial direction; similarly, the beam current changes from a two-peak to one-peak radial profile and the maximum value decreases by half. The inward cross-magnetic-field motion of the beam ions is caused by a divergent electric field in the source. Cross-field diffusion of electrons is also observed in the inner plume and is determined as being of non-ambipolar origin.« less

Slit Function Measurement of An Imaging Spectrograph Using Fourier Transform Techniques

NASA Technical Reports Server (NTRS)

Park, Hongwoo; Swimyard, Bruce; Jakobsen, Peter; Moseley, Harvey; Greenhouse, Matthew

2004-01-01

Knowledge of a spectrograph slit function is necessary to interpret the unresolved lines in an observed spectrum. A theoretical slit function can be calculated from the sizes of the entrance slit, the detector aperture when it functions as an exit slit, the dispersion characteristic of the disperser, and the point spread function of the spectrograph. A measured slit function is preferred to the theoretical one for the correct interpretation of the spectral data. In a scanning spectrometer with a single exit slit, the slit function is easily measured. In a fixed grating/or disperser spectrograph, illuminating the entrance slit with a near monochromatic light from a pre-monochrmator or a tunable laser and varying the wavelength of the incident light can measure the slit function. Even though the latter technique had been used successfully for the slit function measurements, it had been very laborious and it would be prohibitive to an imaging spectrograph or a multi-object spectrograph that has a large field of view. We explore an alternative technique that is manageable for the measurements. In the proposed technique, the imaging spectrograph is used as a detector of a Fourier transform spectrometer. This method can be applied not only to an IR spectrograph but also has a potential to a visible/UV spectrograph including a wedge filter spectrograph. This technique will require a blackbody source of known temperature and a bolometer to characterize the interferometer part of the Fourier Transform spectrometer. This pa?er will describe the alternative slit function measurement technique using a Fourier transform spectrometer.

Mauna Kea Spectrographic Explorer (MSE): a conceptual design for multi-object high resolution spectrograph

NASA Astrophysics Data System (ADS)

Zhang, Kai; Zhu, Yongtian; Hu, Zhongwen

2016-08-01

The Maunakea Spectroscopic Explorer (MSE) project will transform the CFHT 3.6m optical telescope into a 10m class dedicated multi-object spectroscopic facility, with an ability to simultaneously measure thousands of objects with a spectral resolution range spanning 2,000 to 40,000. MSE will develop two spectrographic facilities to meet the science requirements. These are respectively, the Low/Medium Resolution spectrographs (LMRS) and High Resolution spectrographs (HRS). Multi-object high resolution spectrographs with total of 1,156 fibers is a big challenge, one that has never been attempted for a 10m class telescope. To date, most spectral survey facilities work in single order low/medium resolution mode, and only a few Wide Field Spectrographs (WFS) provide a cross-dispersion high resolution mode with a limited number of orders. Nanjing Institute of Astronomical Optics and Technology (NIAOT) propose a conceptual design with the use of novel image slicer arrays and single order immersed Volume Phase Holographic (VPH) grating for the MSE multi-object high resolution spectrographs. The conceptual scheme contains six identical fiber-link spectrographs, each of which simultaneously covers three restricted bands (λ/30, λ/30, λ/15) in the optical regime, with spectral resolution of 40,000 in Blue/Visible bands (400nm / 490nm) and 20,000 in Red band (650nm). The details of the design is presented in this paper.

Design of a double-anode magnetron-injection gun for the W-band gyrotron

NASA Astrophysics Data System (ADS)

Jang, Kwang Ho; Choi, Jin Joo; So, Joon Ho

2015-07-01

A double-anode magnetron-injection gun (MIG) was designed. The MIG is for a W-band 10-kW gyrotron. Analytic equations based on adiabatic theory and angular momentum conservation were used to examine the initial design parameters such as the cathode angle, and the radius of the beam emitting surface. The MIG's performances were predicted by using an electron trajectory code, the EGUN code. The beam spread of the axial velocity, Δvz/vz, obtained from the EGUN code was observed to be 1.34% at α = 1.3. The cathode edge emission and the thermal effect were modeled. The cathode edge emission was found to have a major effect on the velocity spread. The electron beam's quality was significantly improved by affixing non-emissive cylinders to the cathode.

Demonstration of Current Profile Shaping using Double Dog-Leg Emittance Exchange Beam Line at Argonne Wakefield Accelerator

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

Ha, Gwanghui; Cho, Moo-Hyun; Conde, Manoel

Emittance exchange (EEX) based longitudinal current profile shaping is the one of the promising current profile shaping technique. This method can generate high quality arbitrary current profiles under the ideal conditions. The double dog-leg EEX beam line was recently installed at the Argonne Wakefield Accelerator (AWA) to explore the shaping capability and confirm the quality of this method. To demonstrate the arbitrary current profile generation, several different transverse masks are applied to generate different final current profiles. The phase space slopes and the charge of incoming beam are varied to observe and suppress the aberrations on the ideal profile. Wemore » present current profile shaping results, aberrations on the shaped profile, and its suppression.« less

Study on depth profile of heavy ion irradiation effects in poly(tetrafluoroethylene-co-ethylene)

NASA Astrophysics Data System (ADS)

Gowa, Tomoko; Shiotsu, Tomoyuki; Urakawa, Tatsuya; Oka, Toshitaka; Murakami, Takeshi; Oshima, Akihiro; Hama, Yoshimasa; Washio, Masakazu

2011-02-01

High linear energy transfer (LET) heavy ion beams were used to irradiate poly(tetrafluoroethylene-co-ethylene) (ETFE) under vacuum and in air. The irradiation effects in ETFE as a function of the depth were precisely evaluated by analyzing each of the films of the irradiated samples, which were made of stacked ETFE films. It was indicated that conjugated double bonds were generated by heavy ion beam irradiation, and their amounts showed the Bragg-curve-like distributions. Also, it was suggested that higher LET beams would induce radical formation in high density and longer conjugated C=C double bonds could be generated by the second-order reactions. Moreover, for samples irradiated in air, C=O was produced correlating to the yield of oxygen molecules diffusing from the sample surface.

Ultra-compact laser beam steering device using holographically formed two dimensional photonic crystal.

PubMed

Dou, Xinyuan; Chen, Xiaonan; Chen, Maggie Yihong; Wang, Alan Xiaolong; Jiang, Wei; Chen, Ray T

2010-03-01

In this paper, we report the theoretical study of polymer-based photonic crystals for laser beam steering which is based on the superprism effect as well as the experiment fabrication of the two dimensional photonic crystals for the laser beam steering. Superprism effect, the principle for beam steering, was separately studied in details through EFC (Equifrequency Contour) analysis. Polymer based photonic crystals were fabricated through double exposure holographic interference method using SU8-2007. The experiment results showed a beam steering angle of 10 degree for 30 nm wavelength variation.

Double-clad photonic crystal fiber coupler for compact nonlinear optical microscopy imaging.

PubMed

Fu, Ling; Gu, Min

2006-05-15

A 1 x 2 double-clad photonic crystal fiber coupler is fabricated by the fused tapered method, showing a low excess loss of 1.1 dB and a splitting ratio of 97/3 over the entire visible and near-infrared wavelength range. In addition to the property of splitting the laser power, the double-clad feature of the coupler facilitates the separation of a near-infrared single-mode beam from a visible multimode beam, which is ideal for nonlinear optical microscopy imaging. In conjunction with a gradient-index lens, this coupler is used to construct a miniaturized microscope based on two-photon fluorescence and second-harmonic generation. Three-dimensional nonlinear optical images demonstrate potential applications of the coupler to compact all-fiber and nonlinear optical microscopy and endoscopy.

Behavior of Double-Web Angles Beam to column connections

NASA Astrophysics Data System (ADS)

Fakih, K. Al; Chin, S. C.; Doh, S. I.

2018-04-01

This paper contains the study performed on the behavior of double-web angles by using finite element analysis computer package known as “Abaqus”. The aim of this present study was simulating the behavior of double-web angles (DWA) steel connections. The purpose of this article is to provide the basis for the fastest and most economical design and analysis and to ensure the required steel connection strength. This study, started used review method of behavior of steel beam-to-column bolted connections. Two models of different cross-section were examined under the effect of concentrated load and different boundary conditions. In all the studied case, material nonlinearity was accounted. A sample study on DWA connections was carried out using both material and geometric nonlinearities. This object will be of great value to anyone who wants to better understand the behavior of the steel beam to column connection. The results of the study have a field of reference for future research for members of the development of the steel connection approach with simulation model design.

An experimental investigation of alternative propellants for the helicon double layer thruster

NASA Astrophysics Data System (ADS)

Charles, C.; Boswell, R. W.; Laine, R.; MacLellan, P.

2008-09-01

Ion energy distribution functions are measured using a retarding field energy analyser located 7.5 cm downstream of a helicon double layer plasma source, respectively, operating with four molecular gases: nitrogen (N2), methane (CH4), ammonia (NH3) and nitrous oxide (N2O). For radiofrequency powers of a few hundred watts, and a magnetic field diverging from about 0.013 T (130 G) in the source to about 0.001 T (10 G) in the exhaust, an ion beam is detected for each propellant over a very similar operating pressure range (~0.023 Pa (0.17 mTorr) to ~0.267 Pa (2 mTorr)), as a result of spontaneous electric double layer formation near the exit of the plasma source. The characteristics of the ion beam versus operating pressure closely follow those previously obtained in argon, xenon and hydrogen. The ion beam exhaust velocity in space is found to be in the 17-19 km s-1 range in N2, 21-27 km s-1 range in CH4 and NH3 and 14-16 km s-1 range in N2O.

Parallel electric fields in extragalactic jets - Double layers and anomalous resistivity in symbiotic relationships

NASA Technical Reports Server (NTRS)

Borovsky, J. E.

1986-01-01

After examining the properties of Coulomb-collision resistivity, anomalous (collective) resistivity, and double layers, a hybrid anomalous-resistivity/double-layer model is introduced. In this model, beam-driven waves on both sides of a double layer provide electrostatic plasma-wave turbulence that greatly reduces the mobility of charged particles. These regions then act to hold open a density cavity within which the double layer resides. In the double layer, electrical energy is dissipated with 100 percent efficiency into high-energy particles, creating conditions optimal for the collective emission of polarized radio waves.

Developments of a multi-wavelength spectro-polarimeter on the Domeless Solar Telescope at Hida Observatory

NASA Astrophysics Data System (ADS)

Anan, Tetsu; Huang, Yu-Wei; Nakatani, Yoshikazu; Ichimoto, Kiyoshi; UeNo, Satoru; Kimura, Goichi; Ninomiya, Shota; Okada, Sanetaka; Kaneda, Naoki

2018-05-01

To obtain full Stokes spectra in multi-wavelength windows simultaneously, we developed a new spectro-polarimeter on the Domeless Solar Telescope at Hida Observatory. The new polarimeter consists of a 60 cm aperture vacuum telescope on an altazimuth mounting, an image rotator, a high-dispersion spectrograph, and a polarization modulator and an analyzer composed of a continuously rotating waveplate with a retardation that is nearly constant at around 127° in 500-1100 nm. There are also a polarizing beam splitter located close behind the focus of the telescope, fast and large format CMOS cameras, and an infrared camera. A slit spectrograph allows us to obtain spectra in as many wavelength windows as the number of cameras. We characterized the instrumental polarization of the entire system and established a polarization calibration procedure. The cross-talks among the Stokes Q, U, and V have been evaluated to be about 0.06%-1.2%, depending on the degree of the intrinsic polarizations. In a typical observing setup, a sensitivity of 0.03% can be achieved in 20-60 seconds for 500-1100 nm. The new polarimeter is expected to provide a powerful tool for diagnosing the 3D magnetic field and other vector physical quantities in the solar atmosphere.

PSF modeling by spikes simulations and wings measurements for the MOONS multi fiber spectrograph

NASA Astrophysics Data System (ADS)

Li Causi, G.; Lee, D.; Vitali, F.; Royer, F.; Oliva, E.

2016-08-01

The optical design of MOONS, the next generation thousand-fiber NIR spectrograph for the VLT, involves both on-axis reflective collimators and on-axis very fast reflective cameras, which yields both beam obstruction, due to fiber slit and detector support, and image spread, due to propagation within detector substrate. The need to model and control i) the effect of the diffraction spikes produced by these obstructions, ii) the detector-induced shape variation of the Point Spread Function (PSF), and iii) the intensity profile of the PSF wings, leads us to perform both simulations and lab measurements, in order to optimize the spider design and built a reliable PSF model, useful for simulate realistic raw images for testing the data reduction. Starting from the unobstructed PSF variation, as computed with the ZEMAX software, we numerically computed the diffraction spikes for different spider shapes, to which we added the PSF wing profile, as measured on a sample of the MOONS VPH diffraction grating. Finally, we implemented the PSF defocusing due to the thick detector (for the visible channel), we convolved the PSF with the fiber core image, and we added the optical ghosts, so finally obtaining a detailed and realistic PSF model, that we use for spectral extraction testing, cross talk estimation, and sensitivity predictions.

First results of tests on the WEAVE fibres

NASA Astrophysics Data System (ADS)

Sayède, Frédéric; Younes, Youssef; Fasola, Gilles; Dorent, Stéphane; Abrams, Don Carlos; Aguerri, J. Alphonso L.; Bonifacio, Piercarlo; Carrasco, Esperanza; Dalton, Gavin; Dee, Kevin; Laporte, Philippe; Lewis, Ian; Lhome, Emilie; Middleton, Kevin; Pragt, Johan H.; Rey, Juerg; Stuik, Remko; Trager, Scott C.; Vallenari, Antonella

2016-07-01

WEAVE is a new wide-field spectroscopy facility proposed for the prime focus of the 4.2m William Herschel Telescope. The facility comprises a new 2-degree field of view prime focus corrector with a 1000-multiplex fibre positioner, a small number of individually deployable integral field units, and a large single integral field unit. The IFUs (Integral Field Units) and the MOS (Multi Object Spectrograph) fibres can be used to feed a dual-beam spectrograph that will provide full coverage of the majority of the visible spectrum in a single exposure at a spectral resolution of 5000 or modest wavelength coverage in both arms at a resolution 20000. The instrument is expected to be on-sky by the first quarter of 2018 to provide spectroscopic sampling of the fainter end of the Gaia astrometric catalogue, chemical labeling of stars to V 17, and dedicated follow up of substantial numbers of sources from the medium deep LOFAR surveys. After a brief description of the Fibre System, we describe the fibre test bench, its calibration, and some test results. We have to verify 1920 fibres from the MOS bundles and 740 fibres from the mini-IFU bundles with the test bench. In particular, we present the Focal Ratio Degradation of a cable.

Failure Behavior and Strength of Composite I-Section Beam with Double Cutouts and Stiffener Reinforcement

NASA Astrophysics Data System (ADS)

Zhang, Jian; Liu, Wei; Gao, Weicheng

2018-02-01

This work is carried out to study the influence of double cutouts and stiffener reinforcements on the performance of I-section Carbon Fibre/Epoxy composites beam, including buckling, post-buckling behavior and the ultimate failure. The cantilever I-section beam with two diamond-shaped cutouts in the web and three longitudinal L-shaped stiffeners bonded to one side is subjected to a shear load at free end. Both numerical modelling and Experiment of I-section CFRP beam are performed. In numerical analysis, Tsai-Wu failure criterion is utilized to detect the first-ply-failure load in nonlinear analysis by predicting the load-deflection response. Good agreements are obtained from comparison between the numerical simulations and test results. For the double-hole beam web, the two cutouts show close surface deformation amplitude, which indicates that the stiffeners make the force transformation more effective. Comparing to the numerical result of corresponding beam with single cutout and stiffener reinforcement, the longitudinal stiffeners can not only play a significant role in improving the structural stability (increase about 30%), but also take effects to improve the deformation compatibility of structure. Local buckling happened within the sub-webs partioned by the stiffener and the buckling load is different but close. With post-buckling regime, the two areas show similar deformation characteristic, while the sub-web close to fixed end bears more shear load than the sub-web close to loading end with the increase of normal deformation of structure. The catastrophic failure load is approximate 75.6% higher comparing to buckling load. Results illustrate that the tensile fracture of the fiber is the immediate cause of the ultimate failure of the structure.

Observation of a stationary, current-free double layer in a plasma

NASA Technical Reports Server (NTRS)

Hairapetian, G.; Stenzel, R. L.

1990-01-01

A stationary, current-free, potential double layer is formed in a two-electron-population plasma due to self-consistent separation of the two electron species. The position and amplitude of the double layer are controlled by the relative densities of the two electron populations. The steady-state double layer traps the colder electrons on the high potential side, and generates a neutralized, monoenergetic ion beam on the low potential side. The field-aligned double layer is annihilated when an electron current is drawn through the plasma.

Sodium Laser Guide Star Technique, Spectroscopy and Imaging with Adaptive Optics

NASA Astrophysics Data System (ADS)

Ge, Jian

A sodium laser guide star (LGS) adaptive optics (AO) system developed at Stewart Observatory is to be used at the 6.5m MMT. Annual measurements at Kitt Peak show that the mean mesospheric sodium column density varies from ~2×109cm-2 (summer) to ~5×109cm-2 (winter). The sodium column density also varies by a factor of two during a one hour period. The first simultaneous measurements of sodium LGS brightness, sodium column density and laser power were obtained. The absolute sodium return for a continuous wave circularly polarized beam is 1.2([/pm]0.3)× 106 photons s-1m-2W-1 for the sodium column density of 3.7×109cm-2. Theoretical studies demonstrate that the 6.5m MMT LGS AO can provide Strehl ratios better than 0.15 and about 50% flux concentration within 0.2'' aperture for 1-5.5μm under median seeing. This correction will be available for the full sky. Better Strehl and higher flux concentration can be achieved with natural guide stars, but limited sky coverage. The AO corrected field-of-view is about 60''. The Arizona IR Imager and Echelle Spectrograph (ARIES) was designed to match the 6.5m MMT AO. Detection limits of more than 2 magnitude fainter can be reached with the AO over without the AO. A pre-ARIES wide field near-IR camera was designed, built and tested. The camera provides 1'' images in the near-IR over an 8.5 × 8.5arcmin2 field. The 10-σ detection limit with one minute exposures is 17.9 mag. in the K band. A prototype very high resolution cross-dispersed optical echelle spectrograph was designed and built to match the Starfire Optical Range 1.5m AO images. Interstellar KI 7698A absorption lines have been detected in the spectra of αCyg and ζPer. The spectral resolution is 250.000. About 300A wavelengths were covered in a single exposure. Total detection efficiency of 1% has been achieved. For the first time, a near-single-mode fiber with 10μm core size was applied to transmit the Mt. Wilson 100inch AO corrected beams to a spectrograph. The coupling efficiency of the fiber reached up to 70%. Spectra of αOri were recorded. The spectral resolution is 200,000. The total wavelength coverage is about 650A per exposure.

Physics Notes.

ERIC Educational Resources Information Center

School Science Review, 1982

1982-01-01

Discusses determination of elliptical path of a satellite caught into orbit by the sun or earth; using microcomputer as signal generator (includes program listing); collision process; simple hysteresis loop using double beam CRO; method of demonstrating parallelogram of forces; measuring radius of electron beam curvature; and half-life of thorium…

A chevron beam-splitter interferometer

NASA Technical Reports Server (NTRS)

Breckinridge, J. B.

1979-01-01

Fully tilt compensated double-pass chevron beam splitter, that removes channelling effects and permits optical phase tuning, is wavelength independent and allows small errors in alignment that are not tolerated in Michelson, Machzender, or Sagnac interferometers. Device is very useful in experiments where background vibration affects conventional interferometers.

Analytical solutions to the free vibration of a double-walled carbon nanotube carrying a bacterium at its tip

NASA Astrophysics Data System (ADS)

Storch, Joel A.; Elishakoff, Isaac

2013-11-01

We calculate the natural frequencies and mode shapes of a cantilevered double-walled carbon nanotube carrying a rigid body—representative of a bacterium or virus—at the tip of the outer nanotube. By idealizing the nanotubes as Bernoulli-Euler beams, we are able to obtain exact expressions for both the mode shapes and characteristic frequency equation. Separate analyses are performed for the special case of a concentrated tip mass and the more complicated situation where the tip body also exhibits inertia and mass center offset from the beam tip.

High-precision double-frequency interferometric measurement of the cornea shape

NASA Astrophysics Data System (ADS)

Molebny, Vasyl V.; Pallikaris, Ioannis G.; Naoumidis, Leonidas P.; Smirnov, Eugene M.; Ilchenko, Leonid M.; Goncharov, Vadym O.

1996-11-01

To measure the shape of the cornea and its declinations from the necessary values before and after PRK operation, s well as the shape of other spherical objects like artificial pupil, a technique was used of double-frequency dual-beam interferometry. The technique is based on determination of the optical path difference between two neighboring laser beams, reflected from the cornea or other surface under investigation. Knowing the distance between the beams on the investigated shape. The shape itself is reconstructed by along-line integration. To adjust the wavefront orientation of the laser beam to the spherical shape of the cornea or artificial pupil in the course of scanning, additional lens is involved. Signal-to-noise ratio is ameliorated excluding losses in the acousto-optic deflectors. Polarization selection is realized for choosing the signal needed for measurement. 2D image presentation is accompanied by convenient PC accessories, permitting precise cross-section measurements along selected directions. Sensitivity of the order of 10-2 micrometers is achieved.

Measuring the effective pixel positions for the HARPS3 CCD

NASA Astrophysics Data System (ADS)

Hall, Richard D.; Thompson, Samantha; Queloz, Didier

2016-07-01

We present preliminary results from an experiment designed to measure the effective pixel positions of a CCD to sub-pixel precision. This technique will be used to characterise the 4k x 4k CCD destined for the HARPS-3 spectrograph. The principle of coherent beam interference is used to create intensity fringes along one axis of the CCD. By sweeping the physical parameters of the experiment, the geometry of the fringes can be altered which is used to probe the pixel structure. We also present the limitations of the current experimental set-up and suggest what will be implemented in the future to vastly improve the precision of the measurements.

Single-particle states in ^112Cd probed with the ^111Cd(d,p) reaction

NASA Astrophysics Data System (ADS)

Garrett, P. E.; Jamieson, D.; Demand, G. A.; Finlay, P.; Green, K. L.; Leach, K. G.; Phillips, A. A.; Sumithrarachchi, C. S.; Svensson, C. E.; Triambak, S.; Wong, J.; Ball, G. C.; Hertenberger, R.; Wirth, H.-F.; Kr"Ucken, R.; Faestermann, T.

2009-10-01

As part of a program of detailed spectroscopy of the Cd isotopes, the single-particle neutron states in ^112Cd have been probed with the ^111Cd(d,p) reaction. Beams of polarized 22 MeV deuterons, obtained from the LMU/TUM Tandem Accelerator, bombarded a target of ^111Cd. The protons from the reaction, corresponding to excitation energies up to 3 MeV in ^112Cd, were momentum analyzed with the Q3D spectrograph. Cross sections and analyzing powers were fit to results of DWBA calculations, and spectroscopic factors were determined. The results from the experiment, and implications for the structure of ^112Cd, will be presented.

High Precision Material Study at Near Millimeter Wavelengths.

DTIC Science & Technology

1983-08-30

propagating through these tubes , the beams are allowed to expand for a short distance in free space before they are combined by a mylar -film beam- splitter...Laser Precision Rkp-5200). 22 6 The attenuation of the low-loss EH mode in circular plexiglass tubes of I.D. 0.95 cm, and of various lengths. he...pyroelectric detectors (Laser Precision Rkp-545): L L, and L TPx lens; BS1, wire-mesh beam splitter; BS, mylar -film beam splitter; DPC, double-prism coupler

Packaging consideration of two-dimensional polymer-based photonic crystals for laser beam steering

NASA Astrophysics Data System (ADS)

Dou, Xinyuan; Chen, Xiaonan; Chen, Maggie Yihong; Wang, Alan Xiaolong; Jiang, Wei; Chen, Ray T.

2009-02-01

In this paper, we report the theoretical study of polymer-based photonic crystals for laser beam steering which is based on the superprism effect as well as the experiment fabrication of the two dimensional photonic crystals for the laser beam steering. Superprism effect, the principle for beam steering, was separately studied in details through EFC (Equifrequency Contour) analysis. Polymer based photonic crystals were fabricated through double exposure holographic interference method using SU8-2007. The experiment results were also reported.

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.

Preliminary studies of radiation coupling between remote soft X-ray laser amplifiers

NASA Astrophysics Data System (ADS)

Cairns, G.; Lewis, C. L. S.; Macphee, A. G.; Neely, D.; Holden, M.; Krishnan, J.; Tallents, G. J.; Key, M. H.; Norreys, P. N.; Smith, C. G.; Zhang, J.; Holden, P. B.; Pert, G. J.; Plowes, J.; Ramsden, S. A.

1994-01-01

Coupling of a soft X-ray laser beam with a relaying concave mirror in a sequentially pumped amplifier geometry using the Ne-like Ge system has been studied experimentally. Preliminary observations indicate an increase in the spatial coherence of the amplified relayed beam. In addition, near-field imaging of one of the amplifier plasmas shows a double-lobed intensity pattern of the emergent beam indicating refractive guiding of the amplified beam with components both normal and tangential to the target surface.

New symmetric reflector ultrasonic transducers (SRUT).

PubMed

Toda, Minoru

2009-10-01

This paper proposes a new structure composed of reflector plates mounted in front and in back of the transducer at an angle of 45 degrees, so that acoustic waves from front and back of the transducer are combined to form a single main beam. This principle is applicable to both transmitters and receivers. Because the propagation path lengths of the 2 beams are identical, they constructively add at all frequencies. Theoretical investigations revealed that far field directivity becomes sharper and acoustic pressure output is doubled. Experiments using an air ultrasonic transducer constructed of 50-kHz polyvinylidene fluoride corrugated film has shown doubled acoustic pressure in the far field, and the predicted sharper directivity has been observed. The reflector structure has been also applied to a 2.6-MHz lead zirconate titanate transducer in water with matching layers at both surfaces which has shown almost doubled bandwidth compared with an air backing structure, and doubled output power in continuous drive. Also pulse echo experiments have shown the effectiveness of this scheme.

Polarization modeling and predictions for DKIST part 3: focal ratio and thermal dependencies of spectral polarization fringes and optic retardance

NASA Astrophysics Data System (ADS)

Harrington, David M.; Sueoka, Stacey R.

2018-01-01

Data products from high spectral resolution astronomical polarimeters are often limited by fringes. Fringes can skew derived magnetic field properties from spectropolarimetric data. Fringe removal algorithms can also corrupt the data if the fringes and object signals are too similar. For some narrow-band imaging polarimeters, fringes change the calibration retarder properties and dominate the calibration errors. Systems-level engineering tools for polarimetric instrumentation require accurate predictions of fringe amplitudes, periods for transmission, diattenuation, and retardance. The relevant instabilities caused by environmental, thermal, and optical properties can be modeled and mitigation tools developed. We create spectral polarization fringe amplitude and temporal instability predictions by applying the Berreman calculus and simple interferometric calculations to optics in beams of varying F/ number. We then apply the formalism to superachromatic six-crystal retarders in converging beams under beam thermal loading in outdoor environmental conditions for two of the world's largest observatories: the 10-m Keck telescope and the Daniel K. Inouye Solar Telescope (DKIST). DKIST will produce a 300-W optical beam, which has imposed stringent requirements on the large diameter six-crystal retarders, dichroic beamsplitters, and internal optics. DKIST retarders are used in a converging beam with F/ ratios between 8 and 62. The fringe spectral periods, amplitudes, and thermal models of retarder behavior assisted DKIST optical designs and calibration plans with future application to many astronomical spectropolarimeters. The Low Resolution Imaging Spectrograph with polarimetry instrument at Keck also uses six-crystal retarders in a converging F / 13 beam in a Cassegrain focus exposed to summit environmental conditions providing observational verification of our predictions.

LRS2: A New Integral Field Spectrograph for the HET

NASA Astrophysics Data System (ADS)

Tuttle, Sarah E.; Hill, Gary J.; Chonis, Taylor S.; Tonnesen, Stephanie

2016-01-01

Here we present LRS2 (Low Resolution Spectrograph) and highlight early science opportunities with the newly upgraded Hobby Eberly telescope (HET). LRS2 is a four-channel optical wavelength (370nm - 1micron) spectrograph based on two VIRUS unit spectrographs. This fiber-fed integral field spectrograph covers a 12" x 6" field of view, switched between the two units (one blue, and one red) at R~2000. We highlight design elements, including the fundamental modification to grisms (from VPH gratings in VIRUS) to access the higher resolution. We discuss early science opportunities, including investigating nearby "blue-bulge" spiral galaxies and their anomalous star formation distribution.

VizieR Online Data Catalog: FGK dwarfs atmospheric parameters (Ryabchikova+, 2016)

NASA Astrophysics Data System (ADS)

Ryabchikova, T.; Piskunov, N.; Pakhomov, Y.; Tsymbal, V.; Titarenko, A.; Sitnova, T.; Alexeeva, S.; Fossati, L.; Mashonkina, L.

2016-08-01

For the spectroscopic analysis, we choose the 13 MS stars including the Sun (Table 1) in the 4900-6600K temperature range and with metallicity between [Fe/H]=-1.5 and +0.3dex. All the stars, except HD 149026, have, at least, one interferometric determination of radius and effective temperature. Spectra of the programme stars were obtained with different spectrographs. Most data were extracted from the following archives: the UVES/VLT and HARPS/3.6m spectrographs at ESO,2 the ELODIE/1.93-m spectrograph3 at the Observatoire de Haute Provence, and the ESPaDONs spectrograph at the Canada-France-Hawaii Telescope (CFHT). Spectra of beta Vir and HD 103095 were obtained with the FOCES spectrograph at 2.2-m telescope of the Calar Alto Observatory. One of the spectra of 61 Vir was obtained with the Hamilton Echelle Spectrograph attached to the Shane 3-m telescope of the Lick Observatory. Spectra of few stars, including that of the Sun reflected from Ganymede, were obtained with the HiReS/Keck spectrograph. (3 data files).

The infrared imaging spectrograph (IRIS) for TMT: reflective ruled diffraction grating performance testing and discussion

NASA Astrophysics Data System (ADS)

Meyer, Elliot; Chen, Shaojie; Wright, Shelley A.; Moore, Anna M.; Larkin, James E.; Simard, Luc; Marie, Jerome; Mieda, Etsuko; Gordon, Jacob

2014-07-01

We present the efficiency of near-infrared reflective ruled diffraction gratings designed for the InfraRed Imaging Spectrograph (IRIS). IRIS is a first light, integral field spectrograph and imager for the Thirty Meter Telescope (TMT) and narrow field infrared adaptive optics system (NFIRAOS). IRIS will operate across the near-infrared encompassing the ZYJHK bands (~0.84 - 2.4μm) with multiple spectral resolutions. We present our experimental setup and analysis of the efficiency of selected reflective diffraction gratings. These measurements are used as a comparison sample against selected candidate Volume Phase Holographic (VPH) gratings (see Chen et al., this conference). We investigate the efficiencies of five ruled gratings designed for IRIS from two separate vendors. Three of the gratings accept a bandpass of 1.19-1.37μm (J band) with ideal spectral resolutions of R=4000 and R=8000, groove densities of 249 and 516 lines/mm, and blaze angles of 9.86° and 20.54° respectively. The other two gratings accept a bandpass of 1.51-1.82μm (H Band) with an ideal spectral resolution of R=4000, groove density of 141 lines/mm, and blaze angle of 9.86°. The fraction of flux in each diffraction mode was compared to both a pure reflection mirror as well as the sum of the flux measured in all observable modes. We measure the efficiencies off blaze angle for all gratings and the efficiencies between the polarization transverse magnetic (TM) and transverse electric (TE) states. The peak reflective efficiencies are 98.90 +/- 3.36% (TM) and 84.99 +/- 2.74% (TM) for the H-band R=4000 and J-band R=4000 respectively. The peak reflective efficiency for the J-band R=8000 grating is 78.78 +/- 2.54% (TE). We find that these ruled gratings do not exhibit a wide dependency on incident angle within +/-3°. Our best-manufactured gratings were found to exhibit a dependency on the polarization state of the incident beam with a ~10-20% deviation, consistent with the theoretical efficiency predictions. This work will significantly contribute to the selection of the final grating type and vendor for the IRIS optical system, and are also pertinent to current and future near-infrared astronomical spectrographs.

Exact vibration analysis of a double-nanobeam-systems embedded in an elastic medium by a Hamiltonian-based method

NASA Astrophysics Data System (ADS)

Zhou, Zhenhuan; Li, Yuejie; Fan, Junhai; Rong, Dalun; Sui, Guohao; Xu, Chenghui

2018-05-01

A new Hamiltonian-based approach is presented for finding exact solutions for transverse vibrations of double-nanobeam-systems embedded in an elastic medium. The continuum model is established within the frameworks of the symplectic methodology and the nonlocal Euler-Bernoulli and Timoshenko beam beams. The symplectic eigenfunctions are obtained after expressing the governing equations in a Hamiltonian form. Exact frequency equations, vibration modes and displacement amplitudes are obtained by using symplectic eigenfunctions and end conditions. Comparisons with previously published work are presented to illustrate the accuracy and reliability of the proposed method. The comprehensive results for arbitrary boundary conditions could serve as benchmark results for verifying numerically obtained solutions. In addition, a study on the difference between the nonlocal beam and the nonlocal plate is also included.

Study on DNA Damage Induced by Neon Beam Irradiation in Saccharomyces Cerevisiae

NASA Astrophysics Data System (ADS)

Lu, Dong; Li, Wenjian; Wu, Xin; Wang, Jufang; Ma, Shuang; Liu, Qingfang; He, Jinyu; Jing, Xigang; Ding, Nan; Dai, Zhongying; Zhou, Jianping

2010-12-01

Yeast strain Saccharomyces cerevisiae was irradiated with different doses of 85 MeV/u 20Ne10+ to investigate DNA damage induced by heavy ion beam in eukaryotic microorganism. The survival rate, DNA double strand breaks (DSBs) and DNA polymorphic were tested after irradiation. The results showed that there were substantial differences in DNA between the control and irradiated samples. At the dose of 40 Gy, the yeast cell survival rate approached 50%, DNA double-strand breaks were barely detectable, and significant DNA polymorphism was observed. The alcohol dehydrogenase II gene was amplified and sequenced. It was observed that base changes in the mutant were mainly transversions of T→G and T→C. It can be concluded that heavy ion beam irradiation can lead to change in single gene and may be an effective way to induce mutation.

Distribución Espacial de Ancho Equivalente del Triplete del CaII a partir de Imágenes GMOS

NASA Astrophysics Data System (ADS)

Díaz, R. J.; Mast, D.

Using Gemini+GMOS imagery obtained through the filters i, z and CaT, we developed a technique for estimating the value of the Ca II triplet (CaT) equivalent width (EW). The map generated through arithmetic operations with the near infrared images was calibrated with long slit spectra obtained with REOSC spectrograph at CASLEO. We apply this technique to the study of M 83 central region and present the preliminary results on the spatial distribution of the EW(CaT) within an area of 40 per 40 square arcsec around the double nucleus of M 83, with a spatial resolution of 0.8 arcsec. FULL TEXT IN SPANISH.

Neutron production from beam-modifying devices in a modern double scattering proton therapy beam delivery system.

PubMed

Pérez-Andújar, Angélica; Newhauser, Wayne D; Deluca, Paul M

2009-02-21

In this work the neutron production in a passive beam delivery system was investigated. Secondary particles including neutrons are created as the proton beam interacts with beam shaping devices in the treatment head. Stray neutron exposure to the whole body may increase the risk that the patient develops a radiogenic cancer years or decades after radiotherapy. We simulated a passive proton beam delivery system with double scattering technology to determine the neutron production and energy distribution at 200 MeV proton energy. Specifically, we studied the neutron absorbed dose per therapeutic absorbed dose, the neutron absorbed dose per source particle and the neutron energy spectrum at various locations around the nozzle. We also investigated the neutron production along the nozzle's central axis. The absorbed doses and neutron spectra were simulated with the MCNPX Monte Carlo code. The simulations revealed that the range modulation wheel (RMW) is the most intense neutron source of any of the beam spreading devices within the nozzle. This finding suggests that it may be helpful to refine the design of the RMW assembly, e.g., by adding local shielding, to suppress neutron-induced damage to components in the nozzle and to reduce the shielding thickness of the treatment vault. The simulations also revealed that the neutron dose to the patient is predominated by neutrons produced in the field defining collimator assembly, located just upstream of the patient.

M&A For Lithography Of Sparse Arrays Of Sub-Micrometer Features

DOEpatents

Brueck, Steven R.J.; Chen, Xiaolan; Zaidi, Saleem; Devine, Daniel J.

1998-06-02

Methods and apparatuses are disclosed for the exposure of sparse hole and/or mesa arrays with line:space ratios of 1:3 or greater and sub-micrometer hole and/or mesa diameters in a layer of photosensitive material atop a layered material. Methods disclosed include: double exposure interferometric lithography pairs in which only those areas near the overlapping maxima of each single-period exposure pair receive a clearing exposure dose; double interferometric lithography exposure pairs with additional processing steps to transfer the array from a first single-period interferometric lithography exposure pair into an intermediate mask layer and a second single-period interferometric lithography exposure to further select a subset of the first array of holes; a double exposure of a single period interferometric lithography exposure pair to define a dense array of sub-micrometer holes and an optical lithography exposure in which only those holes near maxima of both exposures receive a clearing exposure dose; combination of a single-period interferometric exposure pair, processing to transfer resulting dense array of sub-micrometer holes into an intermediate etch mask, and an optical lithography exposure to select a subset of initial array to form a sparse array; combination of an optical exposure, transfer of exposure pattern into an intermediate mask layer, and a single-period interferometric lithography exposure pair; three-beam interferometric exposure pairs to form sparse arrays of sub-micrometer holes; five- and four-beam interferometric exposures to form a sparse array of sub-micrometer holes in a single exposure. Apparatuses disclosed include arrangements for the three-beam, five-beam and four-beam interferometric exposures.

HUBBLE DISCOVERS POWERFUL LASER BEAMED FROM CHAOTIC STAR

NASA Technical Reports Server (NTRS)

2002-01-01

This is an artist's concept of a gas cloud (left) that acts as a natural ultraviolet laser, near the huge, unstable star Eta Carinae (right) -- one of most massive and energetic stars in our Milky Way Galaxy. The super-laser was identified by a team led by Kris Davidson of the University of Minnesota, and including nine other collaborators in the U.S. and Sweden during spectroscpic observations made with the Goddard High Resolution spectrograph aboard NASA's Hubble Space Telescope. Since it's unlikely that a single beam from the cloud would happen to be precisely aimed in earth's driection, the astronomers conclude that numerous beams must be radiating from the cloud in all directions - beams from a dance hall mirror-ball. The interstellar laser may result from Eta Carinae's violently chaotic eruptions, illustrated here as a reddish (due to light scattering by dust) outflow from the bright star. A laser, (an acronym for Light Amplification by Stimulated Emission of Radiation) creates an intense coherent beam of light when atoms or molecules in a gas, liquid or solid medium, force an incoming mix of wavelengths (or colors) of light to work in phase, or, at the same wavelength. Though a natural infrared laser was identified in space in 1995, lasers are very rare in space and nothing like the UV laser has ever been seen before. Eta Carinae is several million times brighter than the Sun, and one hundred times as massive. The superstar, located 8,000 light-years away in the souther constellation Carina, underwent a colossal outburst 150 years ago. Illustration courtesy James Gitlin/STScI

Enhanced dynamical stability with harmonic slip stacking

DOE PAGES

Eldred, Jeffrey; Zwaska, Robert

2016-10-26

We develop a configuration of radio-frequency (rf) cavities to dramatically improve the performance of slip-stacking. Slip-stacking is an accumulation technique used at Fermilab to nearly double proton intensity by maintaining two beams of different momenta in the same storage ring. The two particle beams are longitudinally focused in the Recycler by two 53 MHz 100 kV rf cavities with a small frequency difference between them. We propose an additional 106 MHz 20 kV rf cavity with a frequency at the double the average of the upper and lower main rf frequencies. We show the harmonic rf cavity cancels out themore » resonances generated between the two main rf cavities and we derive the relationship between the harmonic rf voltage and the main rf voltage. We find the area factors that can be used to calculate the available phase space area for any set of beam parameters without individual simulation. We establish Booster beam quality requirements to achieve 99\\% slip-stacking efficiency. We measure the longitudinal distribution of the Booster beam and use it to generate a realistic beam model for slip-stacking simulation. In conclusion, we demonstrate that the harmonic rf cavity can not only reduce particle loss during slip-stacking, but also reduce the final longitudinal emittance.« less

Enhanced dynamical stability with harmonic slip stacking

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

Eldred, Jeffrey; Zwaska, Robert

We develop a configuration of radio-frequency (rf) cavities to dramatically improve the performance of slip-stacking. Slip-stacking is an accumulation technique used at Fermilab to nearly double proton intensity by maintaining two beams of different momenta in the same storage ring. The two particle beams are longitudinally focused in the Recycler by two 53 MHz 100 kV rf cavities with a small frequency difference between them. We propose an additional 106 MHz 20 kV rf cavity with a frequency at the double the average of the upper and lower main rf frequencies. We show the harmonic rf cavity cancels out themore » resonances generated between the two main rf cavities and we derive the relationship between the harmonic rf voltage and the main rf voltage. We find the area factors that can be used to calculate the available phase space area for any set of beam parameters without individual simulation. We establish Booster beam quality requirements to achieve 99\\% slip-stacking efficiency. We measure the longitudinal distribution of the Booster beam and use it to generate a realistic beam model for slip-stacking simulation. In conclusion, we demonstrate that the harmonic rf cavity can not only reduce particle loss during slip-stacking, but also reduce the final longitudinal emittance.« less

Optical Design And Performance Of A Dual-Grating, Direct-Reading Spectrograph For Spectrochemical Analyses

NASA Astrophysics Data System (ADS)

Steinhaus, David W.; Kline, John V.; Bieniewski, Thomas M.; Dow, Grove S.; Apel, Charles T.

1980-11-01

An all-mirror optical system is used to direct the light from a variety of spectroscopic sources to two 2-m spectrographs that are placed on either side of a sturdy vertical mounting plate. The gratings were chosen so that the first spectrograph covers the ultraviolet spectral region, and the second spectrograph covers the ultraviolet, visible, and near-infrared regions. With the over 2.5 m of focal curves, each ultraviolet line is available at more than one place. Thus, problems with close lines can be overcome. The signals from a possible maximum of 256 photoelectric detectors go to a small computer for reading and calculation of the element abundances. To our knowledge, no other direct-reading spectrograph has more than about 100 fixed detectors. With an inductively-coupled-plasma source, our calibration curves, and detection limits, are similar to those of other workers using a direct-reading spectrograph.

Primary Objective Grating Astronomical Telescope

NASA Technical Reports Server (NTRS)

Ditto, Thomas D.

2007-01-01

It has been 370 years since a seventeenth century French mathematician, Mersenne, presciently sketched out an astronomical telescope based on dual parabolic reflectors. Since that time the concept of the primary objective has been virtually unchanged. Now a new class of astronomical telescope with a primary objective grating (POG) has been studied as an alternative. The POG competes with mirrors, in part, because diffraction gratings provide the very chromatic dispersion that mirrors defeat. The resulting telescope deals effectively with long-standing restrictions on multiple object spectroscopy (MOS). Other potential benefits include unprecedented apertures and collection areas. The new design also favors space deployment as a gossamer membrane. The inventor, Tom Ditto, first discovered that higher-order diffraction images contain hidden depth cues, for which he was granted a seminal range finding patent in 1987. Subsequently, he invented and patented 3D localizers, profilometers and microscopes using POGs. The POG telescope was placed in the public domain to expedite research. The function of a telescopes primary objective is to collect flux and to deliver images. Both functions dictate that size matters, and bigger is better. For that reason, there has been a steady push over the past century to ramp up the size of the primary mirror. However, for every doubling of mirror diameter, the elapsed time between initial effort and first light has also doubled. Meanwhile, costs escalated beyond the mirror alone, because larger instruments required larger enclosures and better pointing mechanisms. One key catalog of observation, spectrographic data, is far more difficult to amass than two-dimensional imagery. While the number of observable objects has increased with mirror size, the capacity to take spectra has not increased proportionately. In the best of circumstances, spectrograms are available for one per cent of the all objects surveyed. Spectroscopy was a historical afterthought introduced in the nineteenth century shortly after the invention of the diffraction grating and over a century after Newtons 1670 telescope. Spectroscopy is generally accomplished using a diffraction grating as the disperser in the secondary. The light being delivered to the spectrograph is first captured by a primary mirror which provides no chromatic magnification by itself. Sizeable spectrographs could not be deployed while diffraction gratings were rare commodities scribed using mechanical ruling engines that produced one grating line at a time. Today diffraction gratings are commonplace. Their recent availability is a product of both the invention of holography and the mass replication of surface microstructures. Holography permits all lines in a grating to be made simultaneously in a single photographic exposure. Holograms can then be reproduced by embossing processes. The improvement in replication is analogous to how Gutenberg changed the availability of books. The masters may be expensive, but the copies are not. Computer science is another technology that emerged in the second half of the twentieth century without which our proposed spectrographic instrument could not function due to the complexity of image processing required in data reduction. The employment of very large diffraction gratings as primary objectives for astronomical telescopes requires a novel

Bi-tangential hybrid IMRT for sparing the shoulder in whole breast irradiation.

PubMed

Farace, P; Deidda, M A; Iamundo de Cumis, I; Iamundo de Curtis, I; Deiana, E; Farigu, R; Lay, G; Porru, S

2013-11-01

A bi-tangential technique is proposed to reduce undesired doses to the shoulder produced by standard tangential irradiation. A total of 6 patients affected by shoulder pain and reduced functional capacity after whole-breast irradiation were retrospectively analysed. The standard tangential plan used for treatment was compared with (1) a single bi-tangential plan where, to spare the shoulder, the lateral open tangent was split into two half-beams at isocentre, with the superior portion rotated by 10-20° medially with respect to the standard lateral beam; (2) a double bi-tangential plan, where both the tangential open beams were split. The planning target volume (PTV) coverage and the dose to the portion of muscles and axilla included in the standard tangential beams were compared. PTV95 % of standard plan (91.9 ± 3.8) was not significantly different from single bi-tangential plan (91.8 ± 3.4); a small but significant (p < 0.01) decrease was observed with the double bi-tangential plan (90.1 ± 3.7). A marked dose reduction to the muscle was produced by the single bi-tangential plan around 30-40 Gy. The application of the double bi-tangential technique further reduced the volume receiving around 20 Gy, but did not markedly affect the higher doses. The dose to the axilla was reduced both in the single and the double bi-tangential plans. The single bi-tangential technique would have been able to reduce the dose to shoulder and axilla, without compromising target coverage. This simple technique is valuable for irradiation after axillary lymph node dissection or in patients without dissection due to negative or low-volume sentinel lymph node disease.

The double layers in the plasma sheet boundary layer during magnetic reconnection

NASA Astrophysics Data System (ADS)

Guo, J.; Yu, B.

2014-11-01

We studied the evolutions of double layers which appear after the magnetic reconnection through two-dimensional electromagnetic particle-in-cell simulation. The simulation results show that the double layers are formed in the plasma sheet boundary layer after magnetic reconnection. At first, the double layers which have unipolar structures are formed. And then the double layers turn into bipolar structures, which will couple with another new weak bipolar structure. Thus a new double layer or tripolar structure comes into being. The double layers found in our work are about several ten Debye lengths, which accords with the observation results. It is suggested that the electron beam formed during the magnetic reconnection is responsible for the production of the double layers.

Mapper: high throughput maskless lithography

NASA Astrophysics Data System (ADS)

Kuiper, V.; Kampherbeek, B. J.; Wieland, M. J.; de Boer, G.; ten Berge, G. F.; Boers, J.; Jager, R.; van de Peut, T.; Peijster, J. J. M.; Slot, E.; Steenbrink, S. W. H. K.; Teepen, T. F.; van Veen, A. H. V.

2009-01-01

Maskless electron beam lithography, or electron beam direct write, has been around for a long time in the semiconductor industry and was pioneered from the mid-1960s onwards. This technique has been used for mask writing applications as well as device engineering and in some cases chip manufacturing. However because of its relatively low throughput compared to optical lithography, electron beam lithography has never been the mainstream lithography technology. To extend optical lithography double patterning, as a bridging technology, and EUV lithography are currently explored. Irrespective of the technical viability of both approaches, one thing seems clear. They will be expensive [1]. MAPPER Lithography is developing a maskless lithography technology based on massively-parallel electron-beam writing with high speed optical data transport for switching the electron beams. In this way optical columns can be made with a throughput of 10-20 wafers per hour. By clustering several of these columns together high throughputs can be realized in a small footprint. This enables a highly cost-competitive alternative to double patterning and EUV alternatives. In 2007 MAPPER obtained its Proof of Lithography milestone by exposing in its Demonstrator 45 nm half pitch structures with 110 electron beams in parallel, where all the beams where individually switched on and off [2]. In 2008 MAPPER has taken a next step in its development by building several tools. A new platform has been designed and built which contains a 300 mm wafer stage, a wafer handler and an electron beam column with 110 parallel electron beams. This manuscript describes the first patterning results with this 300 mm platform.

Monte Carlo-based parametrization of the lateral dose spread for clinical treatment planning of scanned proton and carbon ion beams.

PubMed

Parodi, Katia; Mairani, Andrea; Sommerer, Florian

2013-07-01

Ion beam therapy using state-of-the-art pencil-beam scanning offers unprecedented tumour-dose conformality with superior sparing of healthy tissue and critical organs compared to conventional radiation modalities for external treatment of deep-seated tumours. For inverse plan optimization, the commonly employed analytical treatment-planning systems (TPSs) have to meet reasonable compromises in the accuracy of the pencil-beam modelling to ensure good performances in clinically tolerable execution times. In particular, the complex lateral spreading of ion beams in air and in the traversed tissue is typically approximated with ideal Gaussian-shaped distributions, enabling straightforward superimposition of several scattering contributions. This work presents the double Gaussian parametrization of scanned proton and carbon ion beams in water that has been introduced in an upgraded version of the worldwide first commercial ion TPS for clinical use at the Heidelberg Ion Beam Therapy Center (HIT). First, the Monte Carlo results obtained from a detailed implementation of the HIT beamline have been validated against available experimental data. Then, for generating the TPS lateral parametrization, radial beam broadening has been calculated in a water target placed at a representative position after scattering in the beamline elements and air for 20 initial beam energies for each ion species. The simulated profiles were finally fitted with an idealized double Gaussian distribution that did not perfectly describe the nature of the data, thus requiring a careful choice of the fitting conditions. The obtained parametrization is in clinical use not only at the HIT center, but also at the Centro Nazionale di Adroterapia Oncologica.

Monte Carlo-based parametrization of the lateral dose spread for clinical treatment planning of scanned proton and carbon ion beams

PubMed Central

Parodi, Katia; Mairani, Andrea; Sommerer, Florian

2013-01-01

Ion beam therapy using state-of-the-art pencil-beam scanning offers unprecedented tumour-dose conformality with superior sparing of healthy tissue and critical organs compared to conventional radiation modalities for external treatment of deep-seated tumours. For inverse plan optimization, the commonly employed analytical treatment-planning systems (TPSs) have to meet reasonable compromises in the accuracy of the pencil-beam modelling to ensure good performances in clinically tolerable execution times. In particular, the complex lateral spreading of ion beams in air and in the traversed tissue is typically approximated with ideal Gaussian-shaped distributions, enabling straightforward superimposition of several scattering contributions. This work presents the double Gaussian parametrization of scanned proton and carbon ion beams in water that has been introduced in an upgraded version of the worldwide first commercial ion TPS for clinical use at the Heidelberg Ion Beam Therapy Center (HIT). First, the Monte Carlo results obtained from a detailed implementation of the HIT beamline have been validated against available experimental data. Then, for generating the TPS lateral parametrization, radial beam broadening has been calculated in a water target placed at a representative position after scattering in the beamline elements and air for 20 initial beam energies for each ion species. The simulated profiles were finally fitted with an idealized double Gaussian distribution that did not perfectly describe the nature of the data, thus requiring a careful choice of the fitting conditions. The obtained parametrization is in clinical use not only at the HIT center, but also at the Centro Nazionale di Adroterapia Oncologica. PMID:23824133

A double-arm Møller Polarimeter for Jefferson Lab's Hall B

NASA Astrophysics Data System (ADS)

Grún, E.; Krúger, H.; Dermott, S.; Fechtig, H.; Graps, A. L.; Zook, H. A.; Gustafson, B. A.; Hamilton, D. P.; Hanner, M. S.; Heck, A.; Horányi, M.; Kissel, J.; Lindbad, B. A.; Linkert, D.; Linkert, G.; Mann, I.; Mcdonnell, J. A. M.; Morfill, G. E.; Polanskey, C.; Schwehm, G.; Srama, R.

1998-10-01

We have constructed and commissioned a double-arm Møller polarimeter for the Hall B beamline at the Thomas Jefferson National Accelerator Facility. The polarimeter measures the longitudinal polarization of the 0.8-4.0 GeV electron beam as it enters the experimental hall. The primary components of the apparatus are a target chamber, a pair of quadrupole magnets, and a pair of lead/scintillating-fiber detectors. The target chamber contains two 20 μm-thick permendur foils tilted at ± 20^o with respect to the beam axis. A target polarization of approximately 8% is produced along the beam direction by a 90 G (nominal) magnetic field generated by a pair of Helmholtz coils. The scattered Møller-electron pairs are directed toward the detectors by the quadrupoles. The quadrupoles are are individually tuned--depending on the beam energy--to center the peak of the Møller asymmetry (θ_c.m.=90^o) onto the fixed detectors. The real-to-accidental coincident-detection rate is better than 200:1. The beam polarization can be measured to a 3% relative statistical precision in less than 30 minutes with a relative systematic uncertainty of less than 5%.

Development of Fast, Background-Limited Transition-Edge Sensors for the Background-Limited Infrared/Sub-Millimetre Spectrograph (BLISS) for SPICA

NASA Technical Reports Server (NTRS)

Beyer, Andrew D.; Runyan, M. C.; Kenyon, M.; Echternach, P. M.; Chui, T.; Bumble, B.; Bradford, C. M.; Holmes, W. A.; Bock, J. J.

2012-01-01

We report experimental progress toward demonstrating background-limited arrays of membrane-isolated transition-edge sensors (TESs) for the Background Limited Infrared/Sub-mm Spectrograph (BLISS). BLISS is a space-borne instrument with grating spectrometers for wavelengths lambda = 35-435 microns and with R = lambda/(delta)lambda approx. 500. The goals for BLISS TESs are: noise equivalent power (NEP) = 5x10(exp -20) W/Hz(1/2) and response time t<30ms. We expect background-limited performance from bilayers TESs with T(sub c)=65mK and G=15fW/K. However, such TESs cannot be operated at 50mK unless stray power on the devices, or dark power PD, is less than 200aW. We describe criteria for measuring P? that requires accurate knowledge of TC. Ultimately, we fabricated superconducting thermistors from Ir (T(sub c) > or = 135mK) and Mo/Cu proximitized bilayers, where T(sub c) is the thermistor transition temperature. We measured the Ir TES arrays in our 50mK adiabatic demagnetization refrigerator test system, which can measure up to eight 1x32 arrays simultaneously using a time-division multiplexer, as well as our single-pixel test system which can measure down to 15mK. In our previous Ir array measurements our best reported performance was NEP=2.5x10(exp -19) W/Hz(1/2) and tapprox.5ms for straight-beam TESs. In fact, we expected NEPapprox.1.5x10(exp -19)W/Hz(1/2) for meander beam TESs, but did not achieve this previously due to 1/f noise. Here, we detail improvements toward measuring the expected NEP and demonstrate NEP=(1.3+0.2)x10(exp -19)W/Hz(1/2) in our single-pixel test system and NEP=(1.6+0.3)x10(exp -19)W/Hz(1/2) in our array test system.

The New Instrument Suite of the TSU/Fairborn 2m Automatic Spectroscopic Telescope

NASA Astrophysics Data System (ADS)

Muterspaugh, Matthew W.; Maxwell, T.; Williamson, M. W.; Fekel, F. C.; Ge, J.; Kelly, J.; Ghasempour, A.; Powell, S.; Zhao, B.; Varosi, F.; Schofield, S.; Liu, J.; Warner, C.; Jakeman, H.; Avner, L.; Swihart, S.; Harrison, C.; Fishler, D.

2014-01-01

Tied with the Liverpool Telescope as the world's largest fully robotic optical research telescope, Tennessee State University's (TSU) 2m Automatic Spectroscopic Telescope (AST) has recently been upgraded to improve performance and increase versatility by supporting multiple instruments. Its second-generation instrument head enables us to rapidly switch between any of up to twelve fibers optics, each of which can supply light to a different instrument. In 2013 construction was completed on a new temperature-controlled guest instrument building, and two new high resolution spectrographs were commissioned. The current set of instrumentation includes (1) the telescope's original R=30,000 echelle spectrograph (0.38--0.83 microns simultaneous), (2) a single order R=7,000 spectrograph centered at Ca H&K features, (3) a single-mode-fiber fed miniature echelle spectrograph (R=100,000; 0.48--0.62 microns simultaneous), (4) the University of Florida's EXPERT-3 spectrograph (R=100,000; 0.38--0.9 microns simultaneous; vacuum and temperature controlled) and (5) the University of Florida's FIRST spectrograph (R=70,000$; 0.8--1.35 or 1.4--1.8 microns simultaneous; vacuum and temperature controlled). Future instruments include the Externally Dispersed Interferometry (EDI) Testbed, a combination low resolution dispersed spectrograph and Fourier Transform Spectrograph. We welcome inquiries from the community in regards to observing access and/or proposals for future guest instruments.

Evaluation of the influence of double and triple Gaussian proton kernel models on accuracy of dose calculations for spot scanning technique.

PubMed

Hirayama, Shusuke; Takayanagi, Taisuke; Fujii, Yusuke; Fujimoto, Rintaro; Fujitaka, Shinichiro; Umezawa, Masumi; Nagamine, Yoshihiko; Hosaka, Masahiro; Yasui, Keisuke; Omachi, Chihiro; Toshito, Toshiyuki

2016-03-01

The main purpose in this study was to present the results of beam modeling and how the authors systematically investigated the influence of double and triple Gaussian proton kernel models on the accuracy of dose calculations for spot scanning technique. The accuracy of calculations was important for treatment planning software (TPS) because the energy, spot position, and absolute dose had to be determined by TPS for the spot scanning technique. The dose distribution was calculated by convolving in-air fluence with the dose kernel. The dose kernel was the in-water 3D dose distribution of an infinitesimal pencil beam and consisted of an integral depth dose (IDD) and a lateral distribution. Accurate modeling of the low-dose region was important for spot scanning technique because the dose distribution was formed by cumulating hundreds or thousands of delivered beams. The authors employed a double Gaussian function as the in-air fluence model of an individual beam. Double and triple Gaussian kernel models were also prepared for comparison. The parameters of the kernel lateral model were derived by fitting a simulated in-water lateral dose profile induced by an infinitesimal proton beam, whose emittance was zero, at various depths using Monte Carlo (MC) simulation. The fitted parameters were interpolated as a function of depth in water and stored as a separate look-up table. These stored parameters for each energy and depth in water were acquired from the look-up table when incorporating them into the TPS. The modeling process for the in-air fluence and IDD was based on the method proposed in the literature. These were derived using MC simulation and measured data. The authors compared the measured and calculated absolute doses at the center of the spread-out Bragg peak (SOBP) under various volumetric irradiation conditions to systematically investigate the influence of the two types of kernel models on the dose calculations. The authors investigated the difference between double and triple Gaussian kernel models. The authors found that the difference between the two studied kernel models appeared at mid-depths and the accuracy of predicting the double Gaussian model deteriorated at the low-dose bump that appeared at mid-depths. When the authors employed the double Gaussian kernel model, the accuracy of calculations for the absolute dose at the center of the SOBP varied with irradiation conditions and the maximum difference was 3.4%. In contrast, the results obtained from calculations with the triple Gaussian kernel model indicated good agreement with the measurements within ±1.1%, regardless of the irradiation conditions. The difference between the results obtained with the two types of studied kernel models was distinct in the high energy region. The accuracy of calculations with the double Gaussian kernel model varied with the field size and SOBP width because the accuracy of prediction with the double Gaussian model was insufficient at the low-dose bump. The evaluation was only qualitative under limited volumetric irradiation conditions. Further accumulation of measured data would be needed to quantitatively comprehend what influence the double and triple Gaussian kernel models had on the accuracy of dose calculations.

New infrared spectrograph for the investigation of the mesopause region

NASA Astrophysics Data System (ADS)

Koltovskoi, I. I.; Ammosov, P. P.; Gavrilyeva, G. A.; Ammosova, A. M.; Sivseva, V. I.

2017-11-01

A new infrared spectrograph with high temporal resolution for observation of OH band (3-1) emission dynamics is described. For the automated work of the spectrograph, special software was created. Remote control over the device is also configured.

Detecting the Length of Double-stranded DNA with Solid State Nanopores

NASA Astrophysics Data System (ADS)

Li, Jiali; Gershow, Marc; Stein, Derek; Qun, Cai; Brandin, Eric; Wang, Hui; Huang, Albert; Branton, Dan; Golovchenko, Jene

2003-03-01

We report on the use of nanometer scale diameter, solid-state nanopores as single molecule detectors of double stranded DNA molecules. These solid-state nanopores are fabricated in thin membranes of silicon nitride, by ion beam sculpting 1. They produce discrete electronic signals: current blockages, when an electrically biased nanopore is exposed to DNA molecules in aqueous salt solutions. We demonstrate examples of such electronic signals for 3k base pairs (bp) and 10k bp double stranded DNA molecules, which suggest that these molecules are individually translocating through the nanopore during the detection process. The translocating time for the 10k bp double stranded DNA is about 3 times longer than the 3k bp, demonstrating that a solid-state nanopore device can be used to detect the lengths of double stranded DNA molecules. Similarities and differences with signals obtained from single stranded DNA in a biological nanopores are discussed 2. 1. Li, J., Stein, D., McMullan, C., Branton, D. Aziz, M. J. and Golovchenko, J. Ion Beam Sculpting at nanometer length scales. Nature 412, 166-169 (2001). 2. Meller, A., L. Nivon, E. Brandin, Golovchenko, J. & Branton, D. Proc. Natl. Acad. Sci. USA 97, 1079-1084 (2000).

Tensile, Compression, Open-Hole Compression and Double Cantilever Beam Fracture Toughness Testing of Multiple NASA Langley Research Center Composite Materials

NASA Technical Reports Server (NTRS)

Adams, Donald F.

1999-01-01

The attached data summarizes the work performed by the Composite Materials Research Group at the University of Wyoming funded by the NASA LaRC Research Grant NAG-1-1294. The work consisted primarily of tension, compression, open-hole compression and double cantilever beam fracture toughness testing performed an a variety of NASA LaRC composite materials. Tests were performed at various environmental conditions and pre-conditioning requirements. The primary purpose of this work was to support the LaRC material development efforts. The data summaries are arranged in chronological order from oldest to newest.

Effective light coupling in reflective fiber optic distance sensors using a double-clad fiber

NASA Astrophysics Data System (ADS)

Werzinger, Stefan; Härteis, Lisa; Köhler, Aaron; Engelbrecht, Rainer; Schmauss, Bernhard

2017-04-01

Many fiber optic distance sensors use a reflective configuration, where a light beam is launched from an optical fiber, reflected from a target and coupled back into the fiber. While singlemode fibers (SMF) provide low-loss, high-performance components and a well-defined output beam, the coupling of the reflected light into the SMF is very sensitive to mechanical misalignments and scattering at the reflecting target. In this paper we use a double-clad fiber (DCF) and a DCF coupler to obtain an enhanced multimodal coupling of reflected light into the fiber. Increased power levels and robustness are achieved compared to a pure SMF configuration.

A complete sample of double-lobed radio quasars for VLBI tests of source models - Definition and statistics

NASA Technical Reports Server (NTRS)

Hough, D. H.; Readhead, A. C. S.

1989-01-01

A complete, flux-density-limited sample of double-lobed radio quasars is defined, with nuclei bright enough to be mapped with the Mark III VLBI system. It is shown that the statistics of linear size, nuclear strength, and curvature are consistent with the assumption of random source orientations and simple relativistic beaming in the nuclei. However, these statistics are also consistent with the effects of interaction between the beams and the surrounding medium. The distribution of jet velocities in the nuclei, as measured with VLBI, will provide a powerful test of physical theories of extragalactic radio sources.

A high-finesse Fabry-Perot cavity with a frequency-doubled green laser for precision Compton polarimetry at Jefferson Lab

DOE PAGES

Rakhman, A.; Hafez, Mohamed A.; Nanda, Sirish K.; ...

2016-03-31

Here, a high-finesse Fabry-Perot cavity with a frequency-doubled continuous wave green laser (532 nm) has been built and installed in Hall A of Jefferson Lab for high precision Compton polarimetry. The infrared (1064 nm) beam from a ytterbium-doped fiber amplifier seeded by a Nd:YAG nonplanar ring oscillator laser is frequency doubled in a single-pass periodically poled MgO:LiNbO 3 crystal. The maximum achieved green power at 5 W infrared pump power is 1.74 W with a total conversion efficiency of 34.8%. The green beam is injected into the optical resonant cavity and enhanced up to 3.7 kW with a corresponding enhancementmore » of 3800. The polarization transfer function has been measured in order to determine the intra-cavity circular laser polarization within a measurement uncertainty of 0.7%. The PREx experiment at Jefferson Lab used this system for the first time and achieved 1.0% precision in polarization measurements of an electron beam with energy and current of 1.0 GeV and 50 μA.« less

Two-photon polymerization of a three dimensional structure using beams with orbital angular momentum

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

Zhang, Shi-Jie; Li, Yan, E-mail: li@pku.edu.cn; Liu, Zhao-Pei

The focus of a beam with orbital angular momentum exhibits internal structure instead of an elliptical intensity distribution of a Gaussian beam, and the superposition of Gauss-Laguerre beams realized by two-dimensional phase modulation can generate a complex three-dimensional (3D) focus. By taking advantage of the flexibility of this 3D focus tailoring, we have fabricated a 3D microstructure with high resolution by two-photon polymerization with a single exposure. Furthermore, we have polymerized an array of double-helix structures that demonstrates optical chirality.

Generation and characterization of ultra-short electron beams for single spike infrared FEL radiation at SPARC_LAB

NASA Astrophysics Data System (ADS)

Villa, F.; Anania, M. P.; Artioli, M.; Bacci, A.; Bellaveglia, M.; Bisesto, F. G.; Biagioni, A.; Carpanese, M.; Cardelli, F.; Castorina, G.; Chiadroni, E.; Cianchi, A.; Ciocci, F.; Croia, M.; Curcio, A.; Dattoli, G.; Gallo, A.; Di Giovenale, D.; Di Palma, E.; Di Pirro, G.; Ferrario, M.; Filippi, F.; Giannessi, L.; Giribono, A.; Marocchino, A.; Massimo, F.; Mostacci, A.; Petralia, A.; Petrarca, M.; Petrillo, V.; Piersanti, L.; Pioli, S.; Pompili, R.; Romeo, S.; Rossi, A. R.; Scifo, J.; Shpakov, V.; Vaccarezza, C.

2017-09-01

The technique for producing and measuring few tens of femtosecond electron beams, and the consequent generation of few tens femtoseconds single spike FEL radiation pulses at SPARC_LAB is presented. The undulator has been used in the double role of radiation source and diagnostic tool for the characterization of the electron beam. The connection between the electron bunch length and the radiation bandwidth is analyzed.

Development of a golden beam data set for the commissioning of a proton double-scattering system in a pencil-beam dose calculation algorithm

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

Slopsema, R. L., E-mail: rslopsema@floridaproton.org; Flampouri, S.; Yeung, D.

2014-09-15

Purpose: The purpose of this investigation is to determine if a single set of beam data, described by a minimal set of equations and fitting variables, can be used to commission different installations of a proton double-scattering system in a commercial pencil-beam dose calculation algorithm. Methods: The beam model parameters required to commission the pencil-beam dose calculation algorithm (virtual and effective SAD, effective source size, and pristine-peak energy spread) are determined for a commercial double-scattering system. These parameters are measured in a first room and parameterized as function of proton energy and nozzle settings by fitting four analytical equations tomore » the measured data. The combination of these equations and fitting values constitutes the golden beam data (GBD). To determine the variation in dose delivery between installations, the same dosimetric properties are measured in two additional rooms at the same facility, as well as in a single room at another facility. The difference between the room-specific measurements and the GBD is evaluated against tolerances that guarantee the 3D dose distribution in each of the rooms matches the GBD-based dose distribution within clinically reasonable limits. The pencil-beam treatment-planning algorithm is commissioned with the GBD. The three-dimensional dose distribution in water is evaluated in the four treatment rooms and compared to the treatment-planning calculated dose distribution. Results: The virtual and effective SAD measurements fall between 226 and 257 cm. The effective source size varies between 2.4 and 6.2 cm for the large-field options, and 1.0 and 2.0 cm for the small-field options. The pristine-peak energy spread decreases from 1.05% at the lowest range to 0.6% at the highest. The virtual SAD as well as the effective source size can be accurately described by a linear relationship as function of the inverse of the residual energy. An additional linear correction term as function of RM-step thickness is required for accurate parameterization of the effective SAD. The GBD energy spread is given by a linear function of the exponential of the beam energy. Except for a few outliers, the measured parameters match the GBD within the specified tolerances in all of the four rooms investigated. For a SOBP field with a range of 15 g/cm{sup 2} and an air gap of 25 cm, the maximum difference in the 80%–20% lateral penumbra between the GBD-commissioned treatment-planning system and measurements in any of the four rooms is 0.5 mm. Conclusions: The beam model parameters of the double-scattering system can be parameterized with a limited set of equations and parameters. This GBD closely matches the measured dosimetric properties in four different rooms.« less

[Spectral analysis of fiber bragg grating modulated by double long period grating and its application in smart structure monitoring].

PubMed

Lu, Ji-Yun; Liang, Da-Kai; Zhang, Xiao-Li; Zhu, Zhu

2009-12-01

Spectrum of fiber bragg grating (FBG) sensor modulated by double long period grating (LPFG) is proposed in the paper. Double LPFG consists of two LPFGS whose center wavelengths are the same and reflection spectrum of FBG sensor is located in linear range of double LPFG transmission spectrum. Based on spectral analysis of FBG and double LPFG, reflection spectrum of FBG modulated by double LPFG is obtained and studied by use of band-hider filter characteristics for double LPFG. An FBG sensor is attached on the surface of thin steel beam, which is strained by bending, and the center wavelength of FBG sensor will shift. The spectral peak of FBG sensor modulated by double LPFG is changed correspondingly, and the spectral change will lead to variation in exit light intensity from double LPFG. Experiment demonstrates that the relation of filtering light intensity from double LPFG monitored by optical power meter to center wavelength change of FBG sensor is linear and the minimum strain of material (steel beam) detected by the modulation and demodulation system is 1.05 microepsilon. This solution is used in impact monitoring of optical fibre smart structure, and FBG sensor is applied for impulse response signal monitoring induced by low-velocity impact, when impact pendulum is loaded to carbon fiber-reinforced plastics (CFP). The acquired impact response signal and fast Fourier transform of the signal detected by FBG sensor agree with the measurement results of eddy current displacement meter attached to the FBG sensor. From the results, the present method using FBG sensor is found to be effective for monitoring the impact. The research provides a practical reference in dynamic monitoring of optical fiber smart structure field.

Cusped magnetic field mercury ion thruster. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Beattie, J. R.

1976-01-01

The importance of a uniform current density profile in the exhaust beam of an electrostatic ion thruster is discussed in terms of thrust level and accelerator system lifetime. A residence time approach is used to explain the nonuniform beam current density profile of the divergent magnetic field thruster. Mathematical expressions are derived which relate the thruster discharge power loss, propellant utilization, and double to single ion density ratio to the geometry and plasma properties of the discharge chamber. These relationships are applied to a cylindrical discharge chamber model of the thruster. Experimental results are presented for a wide range of the discharge chamber length. The thruster designed for this investigation was operated with a cusped magnetic field as well as a divergent field geometry, and the cusped field geometry is shown to be superior from the standpoint of beam profile uniformity, performance, and double ion population.

Measurements of thermal conductivity and the coefficient of thermal expansion for polysilicon thin films by using double-clamped beams

NASA Astrophysics Data System (ADS)

Liu, Haiyun; Wang, Lei

2018-01-01

In this paper, a test structure for simultaneously determining thermal conductivity and the coefficient of thermal expansion (CTE) of polysilicon thin film is proposed. The test structure consists of two double-clamped beams with different lengths. A theoretical model for extracting thermal conductivity and CTE based on electrothermal analysis and resonance frequency approach is developed. Both flat and buckled beams are considered in the theoretical model. The model is confirmed by finite element software ANSYS. The test structures are fabricated by surface micromachined fabrication process. Experiments are carried out in our atmosphere. Thermal conductivity and CTE of polysilicon thin film are obtained to be (29.96  ±  0.92) W · m · K-1 and (2.65  ±  0.03)  ×  10-6 K-1, respectively, with temperature ranging from 300-400 K.

Wavelength-doubling optical parametric oscillator

DOEpatents

Armstrong, Darrell J [Albuquerque, NM; Smith, Arlee V [Albuquerque, NM

2007-07-24

A wavelength-doubling optical parametric oscillator (OPO) comprising a type II nonlinear optical medium for generating a pair of degenerate waves at twice a pump wavelength and a plurality of mirrors for rotating the polarization of one wave by 90 degrees to produce a wavelength-doubled beam with an increased output energy by coupling both of the degenerate waves out of the OPO cavity through the same output coupler following polarization rotation of one of the degenerate waves.

The scaling of relativistic double-year widths - Poisson-Vlasov solutions and particle-in-cell simulations

NASA Technical Reports Server (NTRS)

Sulkanen, Martin E.; Borovsky, Joseph E.

1992-01-01

The study of relativistic plasma double layers is described through the solution of the one-dimensional, unmagnetized, steady-state Poisson-Vlasov equations and by means of one-dimensional, unmagnetized, particle-in-cell simulations. The thickness vs potential-drop scaling law is extended to relativistic potential drops and relativistic plasma temperatures. The transition in the scaling law for 'strong' double layers suggested by analytical two-beam models by Carlqvist (1982) is confirmed, and causality problems of standard double-layer simulation techniques applied to relativistic plasma systems are discussed.

Design and Construction of VUES: The Vilnius University Echelle Spectrograph

NASA Astrophysics Data System (ADS)

Jurgenson, Colby; Fischer, Debra; McCracken, Tyler; Sawyer, David; Giguere, Matt; Szymkowiak, Andrew; Santoro, Fernando; Muller, Gary

2016-03-01

In February 2014, the Yale Exoplanet Laboratory was commissioned to design, build, and deliver a high resolution (R=60,000) spectrograph for the 1.65m telescope at the Molėtai Astronomical Observatory. The observatory is operated by the Institute of Theoretical Physics and Astronomy at Vilnius University. The Vilnius University Echelle Spectrograph (VUES) is a white-pupil design that is fed via an octagonal fiber from the telescope and has an operational bandpass from 400nm to 880nm. VUES incorporates a novel modular optomechanical design that allows for quick assembly and alignment on commercial optical tables. This approach allowed the spectrograph to be assembled and commissioned at Yale using lab optical tables and then reassembled at the observatory on a different optical table with excellent repeatability. The assembly and alignment process for the spectrograph was reduced to a few days, allowing the spectrograph to be completely disassembled for shipment to Lithuania, and then installed at the observatory during a 10-day period in June of 2015.

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.

Experimental Estimation of CLASP Spatial Resolution: Results of the Instrument's Optical Alignment

NASA Technical Reports Server (NTRS)

Giono, Gabrial; Katsukawa, Yukio; Ishikawa, Ryoko; Narukage, Noriyuki; Bando, Takamasa; Kano, Ryohei; Suematsu, Yoshinori; Kobayashi, Ken; Winebarger, Amy; Auchere, Frederic

2015-01-01

The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) is a sounding-rocket experiment currently being built at the National Astronomical Observatory of Japan. This instrument aims to probe for the first time the magnetic field strength and orientation in the solar upper-chromosphere and lower-transition region. CLASP will measure the polarization of the Lyman-Alpha line (121.6nm) with an unprecedented accuracy, and derive the magnetic field information through the Hanle effect. Although polarization accuracy and spectral resolution are crucial for the Hanle effect detection, spatial resolution is also important to get reliable context image via the slit-jaw camera. As spatial resolution is directly related with the alignment of optics, it is also a good way of ensuring the alignment of the instrument to meet the scientific requirement. This poster will detail the experiments carried out to align CLASP's optics (telescope and spectrograph), as both part of the instrument were aligned separately. The telescope was aligned in double-pass mode, and a laser interferometer (He-Ne) was used to measure the telescope's wavefront error (WFE). The secondary mirror tilt and position were adjusted to remove comas and defocus aberrations from the WFE. Effect of gravity on the WFE measurement was estimated and the final WFE derived in zero-g condition for CLASP telescope will be presented. In addition, an estimation of the spot shape and size derived from the final WFE will also be shown. The spectrograph was aligned with a custom procedure: because Ly-??light is absorbed by air, the spectrograph's off-axis parabolic mirrors were aligned in Visible Light (VL) using a custom-made VL grating instead of the flight Ly-? grating. Results of the alignment in Visible Light will be shown and the spot shape recorded with CCDs at various position along the slit will be displayed. Results from both alignment experiment will be compared to the design requirement, and will be combined in order to estimate CLASP spatial resolution after its alignment in visible light.

Laser Intensity Scaling Through Stimulated Scattering in Optical Fibers

DTIC Science & Technology

2001-12-17

Stokes beams transmitted through a 300 m multimode fiber. ..................................127 Figure 58: Circles (squares) indicate the measured size...circles) and first order Stokes (squares) beams at the fiber facet. (b,c) Pump (left) and Stokes (right) intensity distributions for a 300 m and...75 m fiber respectively. .......................................................................................130 Figure 61: Double clad fiber

Particle Heating in Space and Laboratory Plasmas

NASA Astrophysics Data System (ADS)

Scime, E. E.; Keesee, A. M.; Aquirre, E.; Good, T.

2017-12-01

We report spatially resolved perpendicular and parallel ion velocity distribution function (IVDF) measurements in an expanding argon helicon plasma. The parallel IVDFs, obtained through laser induced fluorescence (LIF), show an ion beam with v ˜ 8 km/s flowing downstream that is confined to the center of the discharge. The ion beam is confined to within a few centimeters radially and is measurable for tens of centimeters axially before the LIF signal fades, likely a result of metastable quenching of the beam ions. The axial ion beam velocity slows in agreement with collisional processes. The perpendicular IVDFs show an ion population with a radially outward flow that increases with radial location. The DC electric field, electron temperature, and the plasma density in the double layer plume are all consistent with magnetic field aligned structures. The upstream and downstream electric field measurements show clear evidence of an ion hole that maps along the magnetic field at the edge of the plasma. Current theories and simulations of double layers, which are one-dimensional, completely miss these critically important two-dimensional features.

Error in the determination of the deformed shape of prismatic beams using the double integration of curvature

NASA Astrophysics Data System (ADS)

Sigurdardottir, Dorotea H.; Stearns, Jett; Glisic, Branko

2017-07-01

The deformed shape is a consequence of loading the structure and it is defined by the shape of the centroid line of the beam after deformation. The deformed shape is a universal parameter of beam-like structures. It is correlated with the curvature of the cross-section; therefore, any unusual behavior that affects the curvature is reflected through the deformed shape. Excessive deformations cause user discomfort, damage to adjacent structural members, and may ultimately lead to issues in structural safety. However, direct long-term monitoring of the deformed shape in real-life settings is challenging, and an alternative is indirect determination of the deformed shape based on curvature monitoring. The challenge of the latter is an accurate evaluation of error in the deformed shape determination, which is directly correlated with the number of sensors needed to achieve the desired accuracy. The aim of this paper is to study the deformed shape evaluated by numerical double integration of the monitored curvature distribution along the beam, and create a method to predict the associated errors and suggest the number of sensors needed to achieve the desired accuracy. The error due to the accuracy in the curvature measurement is evaluated within the scope of this work. Additionally, the error due to the numerical integration is evaluated. This error depends on the load case (i.e., the shape of the curvature diagram), the magnitude of curvature, and the density of the sensor network. The method is tested on a laboratory specimen and a real structure. In a laboratory setting, the double integration is in excellent agreement with the beam theory solution which was within the predicted error limits of the numerical integration. Consistent results are also achieved on a real structure—Streicker Bridge on Princeton University campus.

Early laser operations at the Large Binocular Telescope Observatory

NASA Astrophysics Data System (ADS)

Rahmer, Gustavo; Lefebvre, Michael; Christou, Julian; Raab, Walfried; Rabien, Sebastian; Ziegleder, Julian; Borelli, José L.; Gässler, Wolfgang

2014-08-01

ARGOS is the GLAO (Ground-Layer Adaptive Optics) Rayleigh-based LGS (Laser Guide Star) facility for the Large Binocular Telescope Observatory (LBTO). It is dedicated for observations with LUCI1 and LUCI2, LBTO's pair of NIR imagers and multi-object spectrographs. The system projects three laser beams from the back of each of the two secondary mirror units, which create two constellations circumscribed on circles of 2 arcmin radius with 120 degree spacing. Each of the six Nd:YAG lasers provides a beam of green (532nm) pulses at a rate of 10kHz with a power of 14W to 18W. We achieved first on-sky propagation on the night of November 5, 2013, and commissioning of the full system will take place during 2014. We present the initial results of laser operations at the observatory, including safety procedures and the required coordination with external agencies (FAA, Space Command, and Military Airspace Manager). We also describe our operational procedures and report on our experiences with aircraft spotters. Future plans for safer and more efficient aircraft monitoring and detection are discussed.

End effects in optical fibres

NASA Astrophysics Data System (ADS)

Allington-Smith, Jeremy; Dunlop, Colin; Lemke, Ulrike; Murray, Graham

2013-12-01

The performance of highly multiplexed spectrographs is limited by focal ratio degradation (FRD) in the optical fibres. It has already been shown that this is caused mainly by processes concentrated around the mounting points at the ends of the fibres. We use the thickness of rings produced in the far-field when a fibre is illuminated by a collimated beam, to estimate the size of the region where the FRD is generated. This requires the development of a new model, using features of existing ray-tracing and wave-based models, which fits existing data very well. The results suggest that the amount of FRD is primarily determined by the length of fibre bonded into the supporting ferrule. We point out the implications for the production of future fibre systems.

MIT modular x-ray source systems for the study of plasma diagnostics

NASA Astrophysics Data System (ADS)

Coleman, J. W.; Wenzel, K. W.; Petrasso, R. D.; Lo, D. H.; Li, C. K.; Lierzer, J. R.; Wei, T.

1992-10-01

Two new x-ray source systems are now on line at our facility. Each provides an e-beam to 25 kV. Targets are interchangeable between machines, and four x-ray detectors may be used simultaneously with a target. The gridded e-gun of the RACEHORSE system gives a 0.5-1.0-cm pulsable spot on target. The nongridded e-gun of the SCORPION system provides a 0.3-mm or smaller dc microspot on target. RACEHORSE is being used to study and characterize type-II diamond photoconductors for use in diagnosing plasmas, while SCORPION is being used to develop a slitless spectrograph using photographic film. Source design details and some RACEHORSE results are presented.

Neutron production from beam-modifying devices in a modern double scattering proton therapy beam delivery system

PubMed Central

Pérez-Andújar, Angélica; Newhauser, Wayne D; DeLuca, Paul M

2014-01-01

In this work the neutron production in a passive beam delivery system was investigated. Secondary particles including neutrons are created as the proton beam interacts with beam shaping devices in the treatment head. Stray neutron exposure to the whole body may increase the risk that the patient develops a radiogenic cancer years or decades after radiotherapy. We simulated a passive proton beam delivery system with double scattering technology to determine the neutron production and energy distribution at 200 MeV proton energy. Specifically, we studied the neutron absorbed dose per therapeutic absorbed dose, the neutron absorbed dose per source particle and the neutron energy spectrum at various locations around the nozzle. We also investigated the neutron production along the nozzle's central axis. The absorbed doses and neutron spectra were simulated with the MCNPX Monte Carlo code. The simulations revealed that the range modulation wheel (RMW) is the most intense neutron source of any of the beam spreading devices within the nozzle. This finding suggests that it may be helpful to refine the design of the RMW assembly, e.g., by adding local shielding, to suppress neutron-induced damage to components in the nozzle and to reduce the shielding thickness of the treatment vault. The simulations also revealed that the neutron dose to the patient is predominated by neutrons produced in the field defining collimator assembly, located just upstream of the patient. PMID:19147903

Two-beam pumped cascaded four-wave-mixing process for producing multiple-beam quantum correlation

NASA Astrophysics Data System (ADS)

Liu, Shengshuai; Wang, Hailong; Jing, Jietai

2018-04-01

We propose a two-beam pumped cascaded four-wave-mixing (CFWM) scheme with a double-Λ energy-level configuration in 85Rb vapor cell and experimentally observe the emission of up to 10 quantum correlated beams from such CFWM scheme. During this process, the seed beam is amplified; four new signal beams and five idler beams are generated. The 10 beams show strong quantum correlation which is characterized by the intensity-difference squeezing of about -6.7 ±0.3 dB. Then, by altering the angle between the two pump beams, we observe the notable transition of the number of the output beams from 10 to eight, and even to six. We find that both the number of the output quantum correlated beams and their degree of quantum correlation from such two-beam pumped CFWM scheme increase with the decrease of the angle between the two pump beams. Such system may find potential applications in quantum information and quantum metrology.

Constraining Calcium Production in Novae

NASA Astrophysics Data System (ADS)

Tiwari, Pranjal; C. Fry, C. Wrede Team; A. Chen, J. Liang Collaboration; S. Bishop, T. Faestermann, D. Seiler Collaboration; R. Hertenberger, H. Wirth Collaboration

2017-09-01

Calcium is an element that can be produced by thermonuclear reactions in the hottest classical novae. There are discrepancies between the abundance of Calcium observed in novae and expectations based on astrophysical models. Unbound states 1 MeV above the proton threshold affect the production of Calcium in nova models because they act as resonances in the 38 K(p , γ) 39 Ca reaction present. This work describes an experiment to measure the energies of the excited states of 39 Ca . We will bombard a thin target of 40 Ca with a beam of 22 MeV deuterons, resulting in tritons and 39Ca. We will use a Q3D magnetic spectrograph from the MLL in Garching, Germany to momenta analyze the tritons to observe the excitation energies of the resulting 39 Ca states. Simulations have been run to determine the optimal spectrograph settings. We decided to use a chemically stable target composed of CaF2 , doing so resulted in an extra contaminant, Fluorine, which is dealt with by measuring the background from a LiF target. These simulations have led to settings and targets that will result in the observation of the 39 Ca states of interest with minimal interference from contaminants. Preliminary results from this experiment will be presented. National Sciences and Engineering Research Council of Canada and U.S. National Science Foundation.

The Keck Cosmic Web Imager (KCWI): A Powerful New Integral Field Spectrograph for the Keck Observatory

NASA Astrophysics Data System (ADS)

Morrissey, Patrick; KCWI Team

2013-01-01

The Keck Cosmic Web Imager (KCWI) is a new facility instrument being developed for the W. M. Keck Observatory and funded for construction by the Telescope System Instrumentation Program (TSIP) of the National Science Foundation (NSF). KCWI is a bench-mounted spectrograph for the Keck II right Nasmyth focal station, providing integral field spectroscopy over a seeing-limited field up to 20"x33" in extent. Selectable Volume Phase Holographic (VPH) gratings provide high efficiency and spectral resolution in the range of 1000 to 20000. The dual-beam design of KCWI passed a Preliminary Design Review in summer 2011. The detailed design of the KCWI blue channel (350 to 700 nm) is now nearly complete, with the red channel (530 to 1050 nm) planned for a phased implementation contingent upon additional funding. KCWI builds on the experience of the Caltech team in implementing the Cosmic Web Imager (CWI), in operation since 2009 at Palomar Observatory. KCWI adds considerable flexibility to the CWI design, and will take full advantage of the excellent seeing and dark sky above Mauna Kea with a selectable nod-and-shuffle observing mode. The KCWI team is lead by Caltech (project management, design and implementation) in partnership with the University of California at Santa Cruz (camera optical and mechanical design) and the W. M. Keck Observatory (program oversight and observatory interfaces).

Nonlinear frequency doubling characteristics of asymmetric vortices of tunable, broad orbital angular momentum spectrum

NASA Astrophysics Data System (ADS)

Alam, Sabir Ul; Rao, A. Srinivasa; Ghosh, Anirban; Vaity, Pravin; Samanta, G. K.

2018-04-01

We report on a simple experimental scheme to generate and control the orbital angular momentum (OAM) spectrum of the asymmetric vortex beams in a nonlinear frequency conversion process. Using a spiral phase plate (SPP) and adjusting the transverse shift of the SPP with respect to the incident Gaussian beam axis, we have transformed the symmetric (intensity distribution) optical vortex of order l into an asymmetric vortex beam of measured broad spectrum of OAM modes of orders l, l - 1, l - 2, …, 0 (Gaussian mode). While the position of the SPP determines the distribution of the OAM modes, we have also observed that the modal distribution of the vortex beam changes with the shift of the SPP of all orders and finally results in a Gaussian beam (l = 0). Using single-pass frequency doubling of the asymmetric vortices, we have transferred the pump OAM spectra, l, l - 1, l - 2, …, 0, into the broad spectra of higher order OAM modes, 2l, 2l - 1, 2l - 2, …, 0 at green wavelength, owing to OAM conservation in nonlinear processes. We also observed an increase in single-pass conversion efficiency with the increase in asymmetry of the pump vortices producing a higher power vortex beam of mixed OAM modes at a new wavelength than that of the pure OAM mode.

Trapping two types of particles using a double-ring-shaped radially polarized beam

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

Zhang Yaoju; Ding Biaofeng; Suyama, Taikei

An optical-trap method based on the illumination of a double-ring-shaped radially polarized beam (R-TEM{sub 11}*) is proposed. The numerical results based on the vector diffraction theory show that a highly focused R-TEM{sub 11}* beam not only can produce a bright spot but also can form an optical cage in the focal region by changing the truncation parameter {beta}, defined as the ratio of the radius of the aperture to the waist of the beam. The radiation forces acting on Rayleigh particles are calculated by using the Rayleigh scattering theory. The bright spot generated by the R-TEM{sub 11}* beam with amore » {beta} value close to 2 can three-dimensionally trap a particle with a refractive index larger than that of the ambient. An optical cage or three-dimensional dark spot generated by the R-TEM{sub 11}* beam with a {beta} value close to 1.3 can three-dimensionally trap a particle with refractive index smaller than that of the ambient. Because the adjustment of the truncation parameter can be actualized by simply changing the radius of a circular aperture inserted in the front of the lens, only one optical-trap system in the present method can be used to three-dimensionally trap two types of particles with different refractive indices.« less

Intra-Beam Scattering, Impedance, and Instabilities in Ultimate Storage Rings

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

Bane, Karl; /SLAC

We have investigated collective effects in an ultimate storage ring, i.e. one with diffraction limited emittances in both planes, using PEP-X as an example. In an ultimate ring intra-beam scattering (IBS) sets the limit of current that can be stored. In PEP-X, a 4.5 GeV ring running round beams at 200 mA in 3300 bunches, IBS doubles the emittances to 11.5 pm at the design current. The Touschek lifetime is 11 hours. Impedance driven collective effects tend not to be important since the beam current is relatively low. We have investigated collective effects in PEP-X, an ultimate storage ring, i.e.more » one with diffraction limited emittances (at one angstrom wavelength) in both planes. In an ultimate ring intra-beam scattering (IBS) sets the limit of current that can be stored. In PEP-X, IBS doubles the emittances to 11.5 pm at the design current of 200 mA, assuming round beams. The Touschek lifetime is quite large in PEP-X, 11.6 hours, and - near the operating point - increases with decreasing emittance. It is, however, a very sensitive function of momentum acceptance. In an ultimate ring like PEP-X impedance driven collective effects tend not to be important since the beam current is relatively low. Before ultimate PEP-X can be realized, the question of how to run a machine with round beams needs serious study. For example, in this report we assumed that the vertical emittance is coupling dominated. It may turn out that using vertical dispersion is a preferable way to generate round beams. The choice will affect IBS and the Touschek effect.« less

Goodman High Throughput Spectrograph | SOAR

Science.gov Websites

SPARTAN Near-IR Camera Ohio State Infrared Imager/Spectrograph (OSIRIS) - NO LONGER AVAILABLE SOAR 320-850 nm wavelength range. The paper describing the instrument is Clemens et al. (2004) Applying for IRAF. Publishing results based on Goodman data?: ADS link to 2004 SPIE Goodman Spectrograph paper

The coude spectrograph and echelle scanner of the 2.7 m telescope at McDonald Observatory.

NASA Technical Reports Server (NTRS)

Tull, R. G.

1972-01-01

Discussion of certain design aspects of the coude spectrograph, and description of the coude scanner that uses some of the spectrograph optics. The configuration of the large echelle grating used is reviewed along with the systems of computer scanner control and data handling.

The Coude spectrograph and echelle scanner of the 2.7 m telescope at McDonald observatory

NASA Technical Reports Server (NTRS)

Tull, R. G.

1972-01-01

The design of the Coude spectrograph of the 2.7 m McDonald telescope is discussed. A description is given of the Coude scanner which uses the spectrograph optics, the configuration of the large echelle and the computer scanner control and data systems.

Second generation spectrograph for the Hubble Space Telescope

NASA Astrophysics Data System (ADS)

Woodgate, B. E.; Boggess, A.; Gull, T. R.; Heap, S. R.; Krueger, V. L.; Maran, S. P.; Melcher, R. W.; Rebar, F. J.; Vitagliano, H. D.; Green, R. F.; Wolff, S. C.; Hutchings, J. B.; Jenkins, E. B.; Linsky, J. L.; Moos, H. W.; Roesler, F.; Shine, R. A.; Timothy, J. G.; Weistrop, D. E.; Bottema, M.; Meyer, W.

1986-01-01

The preliminary design for the Space Telescope Imaging Spectrograph (STIS), which has been selected by NASA for definition study for future flight as a second-generation instrument on the Hubble Space Telescope (HST), is presented. STIS is a two-dimensional spectrograph that will operate from 1050 A to 11,000 A at the limiting HST resolution of 0.05 arcsec FWHM, with spectral resolutions of 100, 1200, 20,000, and 100,000 and a maximum field-of-view of 50 x 50 arcsec. Its basic operating modes include echelle model, long slit mode, slitless spectrograph mode, coronographic spectroscopy, photon time-tagging, and direct imaging. Research objectives are active galactic nuclei, the intergalactic medium, global properties of galaxies, the origin of stellar systems, stelalr spectral variability, and spectrographic mapping of solar system processes.

Constraints on filament models deduced from dynamical analysis

NASA Technical Reports Server (NTRS)

Simon, G.; Schmieder, B.; Demoulin, P.; Malherbe, J. M.; Poland, A. I.

1986-01-01

The conclusions deduced from simultaneous observations with the Ultra-Violet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission satellite, and the Multichannel Subtractive Double Pass (MSPD) spectrographs at Meudon and Pic du Midi observatories are presented. The observations were obtained in 1980 and 1984. All instruments have almost the same field of view and provide intensity and velocity maps at two temperatures. The resolution is approx. 0.5 to 1.5" for H alpha line and 3" for C IV. The high resolution and simultaneity of the two types of observations allows a more accurate description of the flows in prominences as functions of temperature and position. The results put some contraints on the models and show that dynamical aspects must be taken into account.

Identification of Interesting Objects in Large Spectral Surveys Using Highly Parallelized Machine Learning

NASA Astrophysics Data System (ADS)

Škoda, Petr; Palička, Andrej; Koza, Jakub; Shakurova, Ksenia

2017-06-01

The current archives of LAMOST multi-object spectrograph contain millions of fully reduced spectra, from which the automatic pipelines have produced catalogues of many parameters of individual objects, including their approximate spectral classification. This is, however, mostly based on the global shape of the whole spectrum and on integral properties of spectra in given bandpasses, namely presence and equivalent width of prominent spectral lines, while for identification of some interesting object types (e.g. Be stars or quasars) the detailed shape of only a few lines is crucial. Here the machine learning is bringing a new methodology capable of improving the reliability of classification of such objects even in boundary cases. We present results of Spark-based semi-supervised machine learning of LAMOST spectra attempting to automatically identify the single and double-peak emission of Hα line typical for Be and B[e] stars. The labelled sample was obtained from archive of 2m Perek telescope at Ondřejov observatory. A simple physical model of spectrograph resolution was used in domain adaptation to LAMOST training domain. The resulting list of candidates contains dozens of Be stars (some are likely yet unknown), but also a bunch of interesting objects resembling spectra of quasars and even blazars, as well as many instrumental artefacts. The verification of a nature of interesting candidates benefited considerably from cross-matching and visualisation in the Virtual Observatory environment.

SU-F-T-166: On the Nature of the Background Visible Light Observed in Fiber Optic Dosimetry of Proton Beams

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

Darafsheh, A; Kassaee, A; Finlay, J

Purpose: The nature of the background visible light observed during fiber optic dosimetry of proton beams, whether it is due to Cherenkov radiation or not, has been debated in the literature recently. In this work, experimentally and by means of Monte Carlo simulations, we shed light on this problem and investigated the nature of the background visible light observed in fiber optics irradiated with proton beams. Methods: A bare silica fiber optics was embedded in tissue-mimicking phantoms and irradiated with clinical proton beams with energies of 100–225 MeV at Roberts Proton Therapy Center. Luminescence spectroscopy was performed by a CCD-coupledmore » spectrograph to analyze in detail the emission spectrum of the fiber tip across the visible range of 400–700 nm. Monte Carlo simulation was performed by using FLUKA Monte Carlo code to simulate Cherenkov light and ionizing radiation dose deposition in the fiber. Results: The experimental spectra of the irradiated silica fiber shows two distinct peaks at 450 and 650 nm, whose spectral shape is different from that of Cherenkov radiation. We believe that the nature of these peaks are connected to the point defects of silica including oxygen-deficiency center (ODC) and non-bridging oxygen hole center (NBOHC). Monte Carlo simulations confirmed the experimental observations that Cherenkov radiation cannot be solely responsible for such a signal. Conclusion: We showed that Cherenkov radiation is not the dominant visible signal observed in bare fiber optics irradiated with proton beams. We observed two distinct peaks at 450 and 650 nm whose nature is connected with the point defects of silica fiber including oxygen-deficiency center and non-bridging oxygen hole center.« less

PRAXIS: a low background NIR spectrograph for fibre Bragg grating OH suppression

NASA Astrophysics Data System (ADS)

Horton, Anthony; Ellis, Simon; Lawrence, Jon; Bland-Hawthorn, Joss

2012-09-01

Fibre Bragg grating (FBG) OH suppression is capable of greatly reducing the bright sky background seen by near infrared spectrographs. By filtering out the airglow emission lines at high resolution before the light enters the spectrograph this technique prevents scattering from the emission lines into interline regions, thereby reducing the background at all wavelengths. In order to take full advantage of this sky background reduction the spectrograph must have very low instrumental backgrounds so that it remains sky noise limited. Both simulations and real world experience with the prototype GNOSIS system show that existing spectrographs, designed for higher sky background levels, will be unable to fully exploit the sky background reduction. We therefore propose PRAXIS, a spectrograph optimised specifically for this purpose. The PRAXIS concept is a fibre fed, fully cryogenic, fixed format spectrograph for the J and H-bands. Dark current will be minimised by using the best of the latest generation of NIR detectors while thermal backgrounds will be reduced by the use of a cryogenic fibre slit. Optimised spectral formats and the use of high throughput volume phase holographic gratings will further enhance sensitivity. Our proposal is for a modular system, incorporating exchangeable fore-optics units, integral field units and OH suppression units, to allow PRAXIS to operate as a visitor instrument on any large telescope and enable new developments in FBG OH suppression to be incorporated as they become available. As a high performance fibre fed spectrograph PRAXIS could also serve as a testbed for other astrophotonic technologies.

Nonlinear Elastic J-Integral Measurements in Mode I Using a Tapered Double Cantilever Beam Geometry

NASA Technical Reports Server (NTRS)

Macon, David J.

2006-01-01

An expression for the J-integral of a nonlinear elastic material is derived for an advancing crack in a tapered double cantilever beam fracture specimen. The elastic and plastic fracture energies related to the test geometry and how these energies correlates to the crack position are discussed. The dimensionless shape factors eta(sub el and eta(sub p) are shown to be equivalent and the deformation J-integral is analyzed in terms of the eta(sub el) function. The fracture results from a structural epoxy are interpreted using the discussed approach. The magnitude of the plastic dissipation is found to strongly depend upon the initial crack shape.

High intensity, plasma-induced electron emission from large area carbon nanotube array cathodes

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

Liao Qingliang; Yang Ya; Qi Junjie

2010-02-15

The plasma-induced electron emission properties of large area carbon nanotube (CNT) array cathodes under different pulse electric fields were investigated. The formation and expansion of cathode plasmas were proved; in addition, the cathodes have higher emission current in the double-pulse mode than that in the single-pulse mode due to the expansion of plasma. Under the double-pulse electric field of 8.16 V/mum, the plasma's expansion velocity is about 12.33 cm/mus and the highest emission current density reached 107.72 A/cm{sup 2}. The Cerenkov radiation was used to diagnose the distribution of electron beams, and the electron beams' generating process was plasma-induced emission.

Neutron spectroscopy for pulsed beams with frame overlap using a double time-of-flight technique

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

Harrig, K. P.; Goldblum, B. L.; Brown, J. A.

A new double time-of- ight (dTOF) neutron spectroscopy technique has been developed for pulsed broad spectrum sources with a duty cycle that results in frame overlap, where fast neutrons from a given pulse overtake slower neutrons from previous pulses. Using a tunable beam at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory, neutrons were produced via thick-target breakup of 16 MeV deuterons on a beryllium target in the cyclotron vault. The breakup spectral shape was deduced from a dTOF measurement using an array of EJ-309 organic liquid scintillators. Simulation of the neutron detection efficiency of the scintillator array was performedmore » using both GEANT4 and MCNP6. The efficiency- corrected spectral shape was normalized using a foil activation technique to obtain the energy-dependent flux of the neutron beam at zero degrees with respect to the incoming deuteron beam. The dTOF neutron spectrum was compared to spectra obtained using HEPROW and GRAVEL pulse height spectrum unfolding techniques. While the unfolding and dTOF results exhibit some discrepancies in shape, the integrated flux values agree within two standard deviations. As a result, this method obviates neutron time-of-flight spectroscopy challenges posed by pulsed beams« less

Neutron Spectroscopy for pulsed beams with frame overlap using a double time-of-flight technique

NASA Astrophysics Data System (ADS)

Harrig, K. P.; Goldblum, B. L.; Brown, J. A.; Bleuel, D. L.; Bernstein, L. A.; Bevins, J.; Harasty, M.; Laplace, T. A.; Matthews, E. F.

2018-01-01

A new double time-of-flight (dTOF) neutron spectroscopy technique has been developed for pulsed broad spectrum sources with a duty cycle that results in frame overlap, where fast neutrons from a given pulse overtake slower neutrons from previous pulses. Using a tunable beam at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory, neutrons were produced via thick-target breakup of 16 MeV deuterons on a beryllium target in the cyclotron vault. The breakup spectral shape was deduced from a dTOF measurement using an array of EJ-309 organic liquid scintillators. Simulation of the neutron detection efficiency of the scintillator array was performed using both GEANT4 and MCNP6. The efficiency-corrected spectral shape was normalized using a foil activation technique to obtain the energy-dependent flux of the neutron beam at zero degrees with respect to the incoming deuteron beam. The dTOF neutron spectrum was compared to spectra obtained using HEPROW and GRAVEL pulse height spectrum unfolding techniques. While the unfolding and dTOF results exhibit some discrepancies in shape, the integrated flux values agree within two standard deviations. This method obviates neutron time-of-flight spectroscopy challenges posed by pulsed beams with frame overlap and opens new opportunities for pulsed white neutron source facilities.

Neutron spectroscopy for pulsed beams with frame overlap using a double time-of-flight technique

DOE PAGES

Harrig, K. P.; Goldblum, B. L.; Brown, J. A.; ...

2017-10-16

A new double time-of- ight (dTOF) neutron spectroscopy technique has been developed for pulsed broad spectrum sources with a duty cycle that results in frame overlap, where fast neutrons from a given pulse overtake slower neutrons from previous pulses. Using a tunable beam at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory, neutrons were produced via thick-target breakup of 16 MeV deuterons on a beryllium target in the cyclotron vault. The breakup spectral shape was deduced from a dTOF measurement using an array of EJ-309 organic liquid scintillators. Simulation of the neutron detection efficiency of the scintillator array was performedmore » using both GEANT4 and MCNP6. The efficiency- corrected spectral shape was normalized using a foil activation technique to obtain the energy-dependent flux of the neutron beam at zero degrees with respect to the incoming deuteron beam. The dTOF neutron spectrum was compared to spectra obtained using HEPROW and GRAVEL pulse height spectrum unfolding techniques. While the unfolding and dTOF results exhibit some discrepancies in shape, the integrated flux values agree within two standard deviations. As a result, this method obviates neutron time-of-flight spectroscopy challenges posed by pulsed beams« less

Development and testing of a double length pets for the CLIC experimental area

NASA Astrophysics Data System (ADS)

Sánchez, L.; Carrillo, D.; Gavela, D.; Lara, A.; Rodríguez, E.; Gutiérrez, J. L.; Calero, J.; Toral, F.; Samoshkin, A.; Gudkov, D.; Riddone, G.

2014-05-01

CLIC (compact linear collider) is a future e+e- collider based on normal-conducting technology, currently under study at CERN. Its design is based on a novel two-beam acceleration scheme. The main beam gets RF power extracted from a drive beam through power extraction and transfer structures (PETS). The technical feasibility of CLIC is currently being proved by its Third Test Facility (CTF3) which includes the CLIC experimental area (CLEX). Two Double Length CLIC PETS will be installed in CLEX to validate their performance with beam. This paper is focused on the engineering design, fabrication and validation of this PETS first prototype. The design consists of eight identical bars, separated by radial slots in which damping material is located to absorb transverse wakefields, and two compact couplers placed at both ends of the bars to extract the generated power. The PETS bars are housed inside a vacuum tank designed to make the PETS as compact as possible. Several joint techniques such as vacuum brazing, electron beam and arc welding were used to complete the assembly. Finally, several tests such as dimensional control and leak testing were carried out to validate design and fabrication methods. In addition, RF measurements at low power were made to study frequency tuning.

Beam test of CSES silicon strip detector module

NASA Astrophysics Data System (ADS)

Zhang, Da-Li; Lu, Hong; Wang, Huan-Yu; Li, Xin-Qiao; Xu, Yan-Bing; An, Zheng-Hua; Yu, Xiao-xia; Wang, Hui; Shi, Feng; Wang, Ping; Zhao, Xiao-Yun

2017-05-01

The silicon-strip tracker of the China Seismo-Electromagnetic Satellite (CSES) consists of two double-sided silicon strip detectors (DSSDs) which provide incident particle tracking information. A low-noise analog ASIC VA140 was used in this study for DSSD signal readout. A beam test on the DSSD module was performed at the Beijing Test Beam Facility of the Beijing Electron Positron Collider (BEPC) using a 400-800 MeV/c proton beam. The pedestal analysis results, RMSE noise, gain correction, and intensity distribution of incident particles of the DSSD module are presented. Supported by the XXX Civil Space Programme

The problem of scattering in fibre-fed VPH spectrographs and possible solutions

NASA Astrophysics Data System (ADS)

Ellis, S. C.; Saunders, Will; Betters, Chris; Croom, Scott

2014-07-01

All spectrographs unavoidably scatter light. Scattering in the spectral direction is problematic for sky subtraction, since atmospheric spectral lines are blurred. Scattering in the spatial direction is problematic for fibre fed spectrographs, since it limits how closely fibres can be packed together. We investigate the nature of this scattering and show that the scattering wings have both a Lorentzian component, and a shallower (1/r) component. We investigate the causes of this from a theoretical perspective, and argue that for the spectral PSF the Lorentzian wings are in part due to the profile of the illumination of the pupil of the spectrograph onto the diffraction grating, whereas the shallower component is from bulk scattering. We then investigate ways to mitigate the diffractive scattering by apodising the pupil. In the ideal case of a Gaussian apodised pupil, the scattering can be significantly improved. Finally we look at realistic models of the spectrograph pupils of fibre fed spectrographs with a centrally obstructed telescope, and show that it is possible to apodise the pupil through non-telecentric injection into the fibre.

Deck of West 232nd Street overpass, showing wide W beam ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Deck of West 232nd Street overpass, showing wide W beam collision barrier, double-faced wooden guardrail, pedestrian fencing in front of parapet, pedestrian ramp, crosswalk, traffic light, and oversized signage, looking southeast. - Henry Hudson Parkway, Extending 11.2 miles from West 72nd Street to Bronx-Westchester border, New York County, NY

A spectrographic study of the aurora and the relation to solar wind pressure pulses.

NASA Astrophysics Data System (ADS)

Stockton-Chalk, A. B.; Lanchester, B. S.; Ivchenko, N.; Lummerzheim, D.; Throp, K.

SIF (Spectrographic Imaging Facility) is a Southampton University / University College London collaboration. The platform consists of a High Throughput Imaging Echelle Spectrograph, HiTIES, two photometers and a narrow angle auroral imager. The spectrograph has a mosaic filter; each of the three spectral panels are centred over/near important spectral features: Hbeta (486.1nm), N2+(470.9nm), N2+(465.2nm), thus allowing studies of proton and electron aurorae. The platform has been successfully deployed in Svalbard since November 1999. The purpose of the experiment was to take spectrographic measurements to study the relationship between proton and electron precipitation and to understand the nature of the precipitating spectrum of protons, both in energy and angular distributions. We present a study of the aurora observed in relation to solar wind pressure pulses.

High efficiency spectrographs for the EUV and soft X-rays

NASA Technical Reports Server (NTRS)

Cash, W.

1983-01-01

The use of grazing incidence optics and reflection grating designs is shown to be a method that improves the performance of spectrographs at wavelengths shorter than 1200 A. Emphasis is laid on spectroscopic designs for X ray and EUV astronomy, with sample designs for an objective reflection grating spectrograph (ORGS) and an echelle spectrograph for wavelengths longer than 100 A. Conical diffraction allows operations at grazing incidence in the echelle spectrograph. In ORGS, the extreme distance of X ray objects aids in collimating the source radiation, which encounters conical diffraction within the instrument, proceeds parallel to the optical axis, and arrives at the detector. A series of gratings is used to achieve the effect. A grazing echelle is employed for EUV observations, and offers a resolution of 20,000 over a 300 A bandpass.

Visible camera cryostat design and performance for the SuMIRe Prime Focus Spectrograph (PFS)

NASA Astrophysics Data System (ADS)

Smee, Stephen A.; Gunn, James E.; Golebiowski, Mirek; Hope, Stephen C.; Madec, Fabrice; Gabriel, Jean-Francois; Loomis, Craig; Le fur, Arnaud; Dohlen, Kjetil; Le Mignant, David; Barkhouser, Robert; Carr, Michael; Hart, Murdock; Tamura, Naoyuki; Shimono, Atsushi; Takato, Naruhisa

2016-08-01

We describe the design and performance of the SuMIRe Prime Focus Spectrograph (PFS) visible camera cryostats. SuMIRe PFS is a massively multi-plexed ground-based spectrograph consisting of four identical spectrograph modules, each receiving roughly 600 fibers from a 2394 fiber robotic positioner at the prime focus. Each spectrograph module has three channels covering wavelength ranges 380 nm - 640 nm, 640 nm - 955 nm, and 955 nm - 1.26 um, with the dispersed light being imaged in each channel by a f/1.07 vacuum Schmidt camera. The cameras are very large, having a clear aperture of 300 mm at the entrance window, and a mass of 280 kg. In this paper we describe the design of the visible camera cryostats and discuss various aspects of cryostat performance.

Conical refraction and formation of multiring focal image with Laguerre-Gauss light beams.

PubMed

Peet, Viktor

2011-08-01

For a light beam focused through a biaxial crystal along one of its optical axes, the effect of internal conical refraction in the crystal leads to the formation in the focal image plane of two bright rings separated by a dark ring. It is shown that, with circularly polarized Laguerre-Gauss LG(0)(ℓ) beams entering the crystal, this classical double-ring pattern is transformed into a multiring one consisting of ℓ+2 bright rings. © 2011 Optical Society of America

Recent improvements of the JET lithium beam diagnostica)

NASA Astrophysics Data System (ADS)

Brix, M.; Dodt, D.; Dunai, D.; Lupelli, I.; Marsen, S.; Melson, T. F.; Meszaros, B.; Morgan, P.; Petravich, G.; Refy, D. I.; Silva, C.; Stamp, M.; Szabolics, T.; Zastrow, K.-D.; Zoletnik, S.; JET-EFDA Contributors

2012-10-01

A 60 kV neutral lithium diagnostic beam probes the edge plasma of JET for the measurement of electron density profiles. This paper describes recent enhancements of the diagnostic setup, new procedures for calibration and protection measures for the lithium ion gun during massive gas puffs for disruption mitigation. New light splitting optics allow in parallel beam emission measurements with a new double entrance slit CCD spectrometer (spectrally resolved) and a new interference filter avalanche photodiode camera (fast density and fluctuation studies).

Dynamical stability of slip-stacking particles

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

Eldred, Jeffrey; Zwaska, Robert

2014-09-01

We study the stability of particles in slip-stacking configuration, used to nearly double proton beam intensity at Fermilab. We introduce universal area factors to calculate the available phase space area for any set of beam parameters without individual simulation. We find perturbative solutions for stable particle trajectories. We establish Booster beam quality requirements to achieve 97% slip-stacking efficiency. We show that slip-stacking dynamics directly correspond to the driven pendulum and to the system of two standing-wave traps moving with respect to each other.

Surface-Finish Measurement with Interference Microscopes,

DTIC Science & Technology

1977-02-01

Microscope 17 Multiple-Beam Interference Microscope .. 25 Fringes of Equal Chromatic Order 27 Nomarski Polarization-Contrast Technique 33...characteristics of each instrument: the double and multiple-beam interferometer, the FECO fringe interferometer, and the Nomarski polarization contrast...328X Beam Reichert 8X 0.15 2.22 87 33X Nomarski 16X 0.25 1.33 52 55X 203X Technique 32X 0.40 0.83 33 87X 395X 45 X 0.65 0.51 20 142X 567 X 80X

Challenges and Plans for the Proton Injectors

NASA Astrophysics Data System (ADS)

Garoby, R.

The flexibility of the LHC injectors combined with multiple longitudinal beam gymnastics have significantly contributed to the excellent performance of the LHC during its first run, delivering beam with twice the ultimate brightness with 50 ns bunch spacing. To meet the requirements of the High Luminosity LHC, 25 ns bunch spacing is required, the intensity per bunch at injection has to double and brightness shall almost triple. Extensive hardware modifications or additions are therefore necessary in all accelerators of the injector complex, as well as new beam gymnastics.

NRES: The Network of Robotic Echelle Spectrographs

NASA Astrophysics Data System (ADS)

Siverd, Robert; Brown, Tim; Henderson, Todd; Hygelund, John; Barnes, Stuart; de Vera, Jon; Eastman, Jason; Kirby, Annie; Smith, Cary; Taylor, Brook; Tufts, Joseph; van Eyken, Julian

2018-01-01

Las Cumbres Observatory (LCO) is building the Network of Robotic Echelle Spectrographs (NRES), which will consist of four (up to six in the future) identical, optical (390 - 860 nm) high-precision spectrographs, each fiber-fed simultaneously by up to two 1-meter telescopes and a Thorium-Argon calibration source. We plan to install one at up to 6 observatory sites in the Northern and Southern hemispheres, creating a single, globally-distributed, autonomous spectrograph facility using up to ten 1-m telescopes. Simulations suggest we will achieve long-term radial velocity precision of 3 m/s in less than an hour for stars brighter than V = 11 or 12 once the system reaches full capability. Acting in concert, these four spectrographs will provide a new, unique facility for stellar characterization and precise radial velocities.Following a few months of on-sky evaluation at our BPL test facility, the first spectrograph unit was shipped to CTIO in late 2016 and installed in March 2017. After several more months of additional testing and commissioning, regular science operations began with this node in September 2017. The second NRES spectrograph was installed at McDonald Observatory in September 2017 and released to the network after its own brief commissioning period, extending spectroscopic capability to the Northern hemisphere. The third NRES spectrograph was installed at SAAO in November 2017 and released to our science community just before year's end. The fourth NRES unit shipped in October and is currently en route to Wise Observatory in Israel with an expected release to the science community in early 2018.We will briefly overview the LCO telescope network, the NRES spectrograph design, the advantages it provides, and development challenges we encountered along the way. We will further discuss real-world performance from our first three units, initial science results, and the ongoing software development effort needed to automate such a facility for a wide array of science cases.

Impedance of an intense plasma-cathode electron source for tokamak startup

NASA Astrophysics Data System (ADS)

Hinson, E. T.; Barr, J. L.; Bongard, M. W.; Burke, M. G.; Fonck, R. J.; Perry, J. M.

2016-05-01

An impedance model is formulated and tested for the ˜1 kV , 1 kA/cm2 , arc-plasma cathode electron source used for local helicity injection tokamak startup. A double layer sheath is established between the high-density arc plasma ( narc≈1021 m-3 ) within the electron source, and the less dense external tokamak edge plasma ( nedge≈1018 m-3 ) into which current is injected at the applied injector voltage, Vinj . Experiments on the Pegasus spherical tokamak show that the injected current, Iinj , increases with Vinj according to the standard double layer scaling Iinj˜Vinj3 /2 at low current and transitions to Iinj˜Vinj1 /2 at high currents. In this high current regime, sheath expansion and/or space charge neutralization impose limits on the beam density nb˜Iinj/Vinj1 /2 . For low tokamak edge density nedge and high Iinj , the inferred beam density nb is consistent with the requirement nb≤nedge imposed by space-charge neutralization of the beam in the tokamak edge plasma. At sufficient edge density, nb˜narc is observed, consistent with a limit to nb imposed by expansion of the double layer sheath. These results suggest that narc is a viable control actuator for the source impedance.

Doubling The Intensity Of An ERL Based Light Source

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

Andrew Hutton

2005-05-01

A light source based on an Energy Recovered Linac (ERL) [1] consists of a superconducting linac and a transfer line that includes wigglers and undulators to produce the synchrotron light. The transfer line brings the electron bunches back to the beginning of the linac so that their energy can be recovered when they traverse the linac a second time, {lambda}/2 out of RF phase. There is another interesting condition when the length of the transfer line is (n {+-} 1/4) {lambda}. In this case, the electrons drift through on the zero RF crossing, and make a further pass around themore » transfer line, effectively doubling the circulating current in the wigglers and undulators. On the third pass through the linac, they will be decelerated and their energy recovered. The longitudinal focusing at the zero crossing is a problem, but it can be canceled if the drifting beam sees a positive energy gradient for the first half of the linac and a negative gradient for the second half (or vice versa). This paper presents a proposal to use a double chicane at the center of the linac to provide this focusing inversion for the drifting beam while leaving the accelerating and decelerating beams on crest. [1] G. R. Neil, et al, Phys. Rev. Let. 84, 662 2000« less

NRES: The Network of Robotic Echelle Spectrographs

NASA Astrophysics Data System (ADS)

Siverd, Robert; Brown, Timothy M.; Henderson, Todd; Hygelund, John; Barnes, Stuart; Bowman, Mark; De Vera, Jon; Eastman, Jason D.; Kirby, Annie; Norbury, Martin; Smith, Cary; Taylor, Brook; Tufts, Joseph; Van Eyken, Julian C.

2017-06-01

Las Cumbres Observatory (LCO) is building the Network of Robotic Echelle Spectrographs (NRES), which will consist of four to six identical, optical (390 - 860 nm) high-precision spectrographs, each fiber-fed simultaneously by up to two 1-meter telescopes and a Thorium-Argon calibration source. We plan to install one at up to 6 observatory sites in the Northern and Southern hemispheres, creating a single, globally-distributed, autonomous spectrograph facility using up to ten 1-m telescopes. Simulations suggest we will achieve long-term radial velocity precision of 3 m/s in less than an hour for stars brighter than V = 11 or 12. Following a few months of on-sky evaluation at our BPL test facility, the first spectrograph unit was shipped to CTIO in late 2016 and installed in March 2017. Barring serious complications, we expect regular scheduled science observing to begin in mid-2017. Three additional units are in building or testing phases and slated for deployment in late 2017. Acting in concert, these four spectrographs will provide a new, unique facility for stellar characterization and precise radial velocities. We will briefly overview the LCO telescope network, the NRES spectrograph design, the advantages it provides, and development challenges we encountered along the way. We will further discuss real-world performance from our first unit, initial science results, and the ongoing software development effort needed to automate such a facility for a wide array of science cases.

Hypersonic Induced Interactions of Plasma and Non-Plasma Jets

DTIC Science & Technology

2006-06-12

kHz, and an output transformer cascade which transforms the voltage to up to 76 kVpp. The burst pulses of the pulse control board are controlled by a...flow condition have imposed the use of a double- pulse laser system with a pulse separation time in the microsecond range. The PIV image acquisition...system utilises a double-cavity Nd:YAG Litron Laser with a pulse energy of 2 x 200 mJ. The beams are frequency doubled to a wavelength of 532 nm and

On the equivalence between Young's double-slit and crystal double-refraction interference experiments.

PubMed

Ossikovski, Razvigor; Arteaga, Oriol; Vizet, Jérémy; Garcia-Caurel, Enric

2017-08-01

We show, both analytically and experimentally, that under common experimental conditions the interference pattern produced in a classic Young's double-slit experiment is indistinguishable from that generated by means of a doubly refracting uniaxial crystal whose optic axis makes a skew angle with the light propagation direction. The equivalence between diffraction and crystal optics interference experiments, taken for granted by Arago and Fresnel in their pioneering research on the interference of polarized light beams, is thus rigorously proven.

Effect of Acoustic Spectrographic Instruction on Production of English /i/ and /I/ by Spanish Pre-Service English Teachers

ERIC Educational Resources Information Center

Quintana-Lara, Marcela

2014-01-01

This study investigates the effects of Acoustic Spectrographic Instruction on the production of the English phonological contrast /i/ and / I /. Acoustic Spectrographic Instruction is based on the assumption that physical representations of speech sounds and spectrography allow learners to objectively see and modify those non-accurate features in…

Double-ring structure formation of intense ion beams with finite radius in a pre-formed plasma

NASA Astrophysics Data System (ADS)

Hu, Zhang-Hu; Wang, Xiao-Juan; Zhao, Yong-Tao; Wang, You-Nian

2017-12-01

The dynamic structure evolution of intense ion beams with a large edge density gradient is investigated in detail with an analytical model and two-dimensional particle-in-cell (PIC) simulations, with special attention paid to the influence of beam radius. At the initial stage of beam-plasma interactions, the ring structure is formed due to the transverse focusing magnetic field induced by the unneutralized beam current in the beam edge region. As the beam-plasma system evolves self-consistently, a second ring structure appears in the case of ion beams with a radius much larger than the plasma skin depth, due to the polarity change in the transverse magnetic field in the central regions compared with the outer, focusing field. Influences of the current-filamentation and two-stream instability on the ring structure can be clearly observed in PIC simulations by constructing two different simulation planes.

Optical design of the NASA-NSF extreme precision Doppler spectrograph concept "WISDOM"

NASA Astrophysics Data System (ADS)

Barnes, Stuart I.; Fżrész, Gábor; Simcoe, Robert A.; Shectman, Stephen A.; Woods, Deborah F.

2016-08-01

The WISDOM instrument concept was developed at MIT as part of a NASA-NSF funded study to equip the 3.5m WIYN telescope with an extremely precise radial velocity spectrometer. The spectrograph employs an asymmetric white pupil optical design, where the instrument is split into two nearly identical "Short" (380 to 750 nm) and "Long"" (750 to 1300 nm) wavelength channels. The echelle grating and beam sizes are R3.75/125mm and R6/80mm in the short and long channels respectively. Together with the pupil slicer, and octagonal to rectangular fibre coupling, this permits resolving powers over R = 120k with a 1.2" diameter fibre on the sky. A factor of two reduction in the focal length between the main collimator OAP and the transfer collimator ensures a very compact instrument, with a small white pupil footprint, thereby enabling small cross-dispersing and camera elements. A dichroic is used near the white pupil to split each of the long and short channels into two, so that the final spectrograph has 4 channels; namely "Blue," "Green," "Red" and "NIR." Each of these channels has an anamorphic VPH grism for cross-dispersion, and a fully dioptric all-spherical camera objective. The spectral footprints cover 4k×4k and 6k×6k CCDs with 15 µm pixels in the short "Blue" and "Green" wavelength channels, respectively. A 4k×4k CCD with 15 μm pixels is used in the long "Red" channel, with a HgCdTe 1.7 μm cutoff 4k×4k detector with 10um pixels is to be used in the long "NIR" channel. The white pupil relay includes a Mangin mirror very close to the intermediate focus to correct the white pupil relay Petzval curvature before it is swept into a cylinder by the cross-dispersers. This design decision allows each of the dioptric cameras to be fully optimised and tested independently of the rest of the spectrograph. The baseline design for the cameras also ensures that the highest possible (diffraction limited) image quality is achieved across all wavelengths, while also ensuring insensitivity of spot centroid locations to variations in the pupil illumination. This insensitivity is proven to remain even in the presence of reasonable manufacturing and alignment tolerances. Fully ray-traced simulations of the spectral formats are used to demonstrate the optical performance, as well as to provide pre-first-light data that can be used to optimise the data reduction pipeline.

Sky Subtraction with Fiber-Fed Spectrograph

NASA Astrophysics Data System (ADS)

Rodrigues, Myriam

2017-09-01

"Historically, fiber-fed spectrographs had been deemed inadequate for the observation of faint targets, mainly because of the difficulty to achieve high accuracy on the sky subtraction. The impossibility to sample the sky in the immediate vicinity of the target in fiber instruments has led to a commonly held view that a multi-object fibre spectrograph cannot achieve an accurate sky subtraction under 1% contrary to their slit counterpart. The next generation of multi-objects spectrograph at the VLT (MOONS) and the planed MOS for the E-ELT (MOSAIC) are fiber-fed instruments, and are aimed to observed targets fainter than the sky continuum level. In this talk, I will present the state-of-art on sky subtraction strategies and data reduction algorithm specifically developed for fiber-fed spectrographs. I will also present the main results of an observational campaign to better characterise the sky spatial and temporal variations ( in particular the continuum and faint sky lines)."

The FIREBall fiber-fed UV spectrograph

NASA Astrophysics Data System (ADS)

Tuttle, Sarah E.; Schiminovich, David; Milliard, Bruno; Grange, Robert; Martin, D. Christopher; Rahman, Shahinur; Deharveng, Jean-Michel; McLean, Ryan; Tajiri, Gordon; Matuszewski, M.

2008-07-01

FIREBall (Faint Intergalactic Redshifted Emission Balloon) had a successful first engineering flight in July of 2007 from Palestine, Texas. Here we detail the design and construction of the spectrograph. FIREBall consists of a 1m telescope coupled to a fiber-fed ultraviolet spectrograph flown on a short duration balloon. The spectrograph is designed to map hydrogen and metal line emission from the intergalactic medium at several redshifts below z=1, exploiting a small window in atmospheric oxygen absorption at balloon altitudes. The instrument is a wide-field IFU fed by almost 400 fibers. The Offner mount spectrograph is designed to be sensitive in the 195-215nm window accessible at our altitudes of 35-40km. We are able to observe Lyα, as well as OVI and CIV doublets, from 0.3 < z < 0.9. Observations of UV bright B stars and background measurements allow characterization of throughput for the entire system and will inform future flights.

MAPPER: high-throughput maskless lithography

NASA Astrophysics Data System (ADS)

Wieland, M. J.; de Boer, G.; ten Berge, G. F.; Jager, R.; van de Peut, T.; Peijster, J. J. M.; Slot, E.; Steenbrink, S. W. H. K.; Teepen, T. F.; van Veen, A. H. V.; Kampherbeek, B. J.

2009-03-01

Maskless electron beam lithography, or electron beam direct write, has been around for a long time in the semiconductor industry and was pioneered from the mid-1960s onwards. This technique has been used for mask writing applications as well as device engineering and in some cases chip manufacturing. However because of its relatively low throughput compared to optical lithography, electron beam lithography has never been the mainstream lithography technology. To extend optical lithography double patterning, as a bridging technology, and EUV lithography are currently explored. Irrespective of the technical viability of both approaches, one thing seems clear. They will be expensive [1]. MAPPER Lithography is developing a maskless lithography technology based on massively-parallel electron-beam writing with high speed optical data transport for switching the electron beams. In this way optical columns can be made with a throughput of 10-20 wafers per hour. By clustering several of these columns together high throughputs can be realized in a small footprint. This enables a highly cost-competitive alternative to double patterning and EUV alternatives. In 2007 MAPPER obtained its Proof of Lithography milestone by exposing in its Demonstrator 45 nm half pitch structures with 110 electron beams in parallel, where all the beams where individually switched on and off [2]. In 2008 MAPPER has taken a next step in its development by building several tools. The objective of building these tools is to involve semiconductor companies to be able to verify tool performance in their own environment. To enable this, the tools will have a 300 mm wafer stage in addition to a 110-beam optics column. First exposures at 45 nm half pitch resolution have been performed and analyzed. On the same wafer it is observed that all beams print and based on analysis of 11 beams the CD for the different patterns is within 2.2 nm from target and the CD uniformity for the different patterns is better than 2.8 nm.

SU-E-T-523: On the Radiobiological Impact of Lateral Scatter in Proton Beams

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

Heuvel, F Van den; Deruysscher, D

2014-06-01

Introduction: In proton therapy, justified concern has been voiced with respect to an increased efficiency in cell kill at the distal end of the Bragg peak. This coupled with range uncertainty is a counter indication to use the Bragg peak to define the border of a treated volume with a critical organ. An alternative is to use the lateral edge of the proton beam, obtaining more robust plans. We investigate the spectral and biological effects of the lateral scatter . Methods: A general purpose Monte Carlo simulation engine (MCNPX 2.7c) installed on a Scientific Linux cluster, calculated the dose depositionmore » spectrum of protons, knock on electrons and generated neutrons for a proton beam with maximal kinetic energy of 200MeV. Around the beam at different positions in the beam direction the spectrum is calculated in concentric rings of thickness 1cm. The deposited dose is converted to a double strand break map using an analytical expression.based on micro dosimetric calculations using a phenomenological Monte Carlo code (MCDS). A strict version of RBE is defined as the ratio of generation of double strand breaks in the different modalities. To generate the reference a Varian linac was modelled in MCNPX and the generated electron dose deposition spectrum was used . Results: On a pristine point source 200MeV beam the RBE before the Bragg peak was of the order of 1.1, increasing to 1.7 right behind the Bragg peak. When using a physically more realistic beam of 10cm diameter the effect was smaller. Both the lateral dose and RBE increased with increasing beam depth, generating a dose deposition with mixed biological effect. Conclusions: The dose deposition in proton beams need to be carefully examined because the biological effect will be different depending on the treatment geometry. Deeply penetrating proton beams generate more biologically effective lateral scatter.« less

Electron density profile measurements at a self-focusing ion beam with high current density and low energy extracted through concave electrodes.

PubMed

Fujiwara, Y; Hirano, Y; Kiyama, S; Nakamiya, A; Koguchi, H; Sakakita, H

2014-02-01

The self-focusing phenomenon has been observed in a high current density and low energy ion beam. In order to study the mechanism of this phenomenon, a special designed double probe to measure the electron density and temperature is installed into the chamber where the high current density ion beam is injected. Electron density profile is successfully measured without the influence of the ion beam components. Estimated electron temperature and density are ∼0.9 eV and ∼8 × 10(8) cm(-3) at the center of ion beam cross section, respectively. It was found that a large amount of electrons are spontaneously accumulated in the ion beam line in the case of self-forcing state.

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

Igarashi, Noriyuki, E-mail: noriyuki.igarashi@kek.jp; Nitani, Hiroaki; Takeichi, Yasuo

BL-15A is a new x-ray undulator beamline at the Photon Factory. It will be dedicated to two independent research activities, simultaneous XAFS/XRF/XRD experiments, and SAXS/WAXS/GI-SAXS studies. In order to supply a choice of micro-focus, low-divergence and collimated beams, a double surface bimorph mirror was recently developed. To achieve further mirror surface optimization, the pencil beam scanning method was applied for “in-situ” beam inspection and the Inverse Matrix method was used for determination of optimal voltages on the piezoelectric actuators. The corrected beam profiles at every focal spot gave good agreement with the theoretical values and the resultant beam performance ismore » promising for both techniques. Quick and stable switching between highly focused and intense collimated beams was established using this new mirror with the simple motorized stages.« less

Development of a double beam process for joining aluminum and steel

NASA Astrophysics Data System (ADS)

Frank, Sascha

2014-02-01

Multi-material structures pose an attractive option for overcoming some of the central challenges in lightweight design. An exceptionally high potential for creating cost-effective lightweight solutions is attributed to the combination of steel and aluminum. However, these materials are also particularly difficult to join due to their tendency to form intermetallic compounds (IMCs). The growth of these compounds is facilitated by high temperatures and long process times. Due to their high brittleness, IMCs can severely weaken a joint. Thus, it is only possible to create durable steel-aluminum joints when the formation of IMCs can be limited to a non-critical level. To meet this goal, a new joining method has been designed. The method is based on the combination of a continuous wave (pw) and a pulsed laser (pw) source. Laser beams from both sources are superimposed in a common process zone. This makes it possible to apply the advantages of laser brazing to mixed-metal joints without requiring the use of chemical fluxes. The double beam technology was first tested in bead-on-plate experiments using different filler wire materials. Based on the results of these tests, a process for joining steel and aluminum in a double-flanged configuration is now being developed. The double flanged seams are joined using zinc- or aluminum-based filler wires. Microsections of selected seams show that it is possible to achieve good base material wetting while limiting the growth of IMCs to acceptable measures. In addition, the results of tensile tests show that high joint strengths can be achieved.

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

Fischer, W.; Gu, X.; Altinbas, Z.

Head-on beam-beam compensation has been implemented in the Relativistic Heavy Ion Collider (RHIC) in order to increase the luminosity delivered to the experiments. We discuss the principle of combining a lattice for resonance driving term compensation and an electron lens for tune spread compensation. We describe the electron lens technology and its operational use. As of this date the implemented compensation scheme approximately doubled the peak and average luminosities.

Investigation of radiofrequency plasma sources for space travel

NASA Astrophysics Data System (ADS)

Charles, C.; Boswell, R. W.; Takahashi, K.

2012-12-01

Optimization of radiofrequency (RF) plasma sources for the development of space thrusters differs from other applications such as plasma processing of materials since power efficiency, propellant usage, particle acceleration or heating become driving parameters. The development of two RF (13.56 MHz) plasma sources, the high-pressure (˜1 Torr) capacitively coupled ‘pocket rocket’ plasma micro-thruster and the low-pressure (˜1 mTorr) inductively coupled helicon double layer thruster (HDLT), is discussed within the context of mature and emerging electric propulsion devices. The density gradient in low-pressure expanding RF plasmas creates an electric field that accelerates positive ions out of the plasma. Generally, the total potential drop is similar to that of a wall sheath allowing the plasma electrons to neutralize the ion beam. A high-pressure expansion with no applied magnetic field can result in large dissociation rates and/or a collimated beam of ions of small area and a flowing heated neutral beam (‘pocket rocket’). A low-pressure expansion dominated by a magnetic field can result in the formation of electric double layers which produce a very directed neutralized beam of ions of large area (HDLT).

Existence domain of electrostatic solitary waves in the lunar wake

NASA Astrophysics Data System (ADS)

Rubia, R.; Singh, S. V.; Lakhina, G. S.

2018-03-01

Electrostatic solitary waves (ESWs) and double layers are explored in a four-component plasma consisting of hot protons, hot heavier ions (He++), electron beam, and suprathermal electrons having κ-distribution using the Sagdeev pseudopotential method. Three modes exist: slow and fast ion-acoustic modes and electron-acoustic mode. The occurrence of ESWs and their existence domain as a function of various plasma parameters, such as the number densities of ions and electron beam, the spectral index, κ, the electron beam velocity, the temperatures of ions, and electron beam, are analyzed. It is observed that both the slow and fast ion-acoustic modes support both positive and negative potential solitons as well as their coexistence. Further, they support a "forbidden gap," the region in which the soliton ceases to propagate. In addition, slow ion-acoustic solitons support the existence of both positive and negative potential double layers. The electron-acoustic mode is only found to support negative potential solitons for parameters relevant to the lunar wake plasma. Fast Fourier transform of a soliton electric field produces a broadband frequency spectrum. It is suggested that all three soliton types taken together can provide a good explanation for the observed electrostatic waves in the lunar wake.

Fracture toughness in Mode I (GIC) for ductile adhesives

NASA Astrophysics Data System (ADS)

Gálvez, P.; Carbas, RJC; Campilho, RDSG; Abenojar, J.; Martínez, MA; Silva LFM, da

2017-05-01

Works carried out in this publication belong to a project that seeks the replacement of welded joints by adhesive joints at stress concentration nodes in bus structures. Fracture toughness in Mode I (GIC) has been measured for two different ductile adhesives, SikaTack Drive and SikaForce 7720. SikaTack Drive is a single-component polyurethane adhesive with high viscoelasticity (more than 100%), whose main use is the car-glass joining and SikaForce 7720 is double-component structural polyurethane adhesive. Experimental works have been carried out from the test called Double Cantilever Beam (DCB), using two steel beams as adherents and an adhesive thickness according to the problem posed in the Project, of 2 and 3 mm for SikaForce 7720 and SikaTack Drive, respectively. Three different methods have been used for measuring the fracture toughness in mode I (GIC) from the values obtained in the experimental DCB procedure for each adhesive: Corrected Beam Theory (CBT), Compliance Calibration Method (CCM) and Compliance Based Beam Method (CBBM). Four DCB specimens have been tested for each adhesive. Dispersion of each GIC calculation method for each adhesive has been studied. Likewise variations between the three different methods have been also studied for each adhesive.

Comparison of large-angle production of charged pions with incident protons on cylindrical long and short targets

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

Apollonio, M.; Chimenti, P.; Giannini, G.

2009-12-15

The HARP Collaboration has presented measurements of the double-differential {pi}{sup {+-}} production cross section in the range of momentum 100 MeV/c{<=}p{<=}800 MeV/c and angle 0.35 rad{<=}{theta}{<=}2.15 rad with proton beams hitting thin nuclear targets. In many applications the extrapolation to long targets is necessary. In this article the analysis of data taken with long (one interaction length) solid cylindrical targets made of carbon, tantalum, and lead is presented. The data were taken with the large-acceptance HARP detector in the T9 beam line of the CERN proton synchrotron. The secondary pions were produced by beams of protons with momenta of 5,more » 8, and 12GeV/c. The tracking and identification of the produced particles were performed using a small-radius cylindrical time projection chamber placed inside a solenoidal magnet. Incident protons were identified by an elaborate system of beam detectors. Results are obtained for the double-differential yields per target nucleon d{sup 2}{sigma}/dpd{theta}. The measurements are compared with predictions of the MARS and GEANT4 Monte Carlo simulations.« less

Numerical Simulation of a Double-anode Magnetron Injection Gun for 110 GHz, 1 MW Gyrotron

NASA Astrophysics Data System (ADS)

Singh, Udaybir; Kumar, Nitin; Purohit, L. P.; Sinha, Ashok K.

2010-07-01

A 40 A double-anode magnetron injection gun for a 1 MW, 110 GHz gyrotron has been designed. The preliminary design has been obtained by using some trade-off equations. The electron beam analysis has been performed by using the commercially available code EGUN and the in-house developed code MIGANS. The operating mode of the gyrotron is TE22,6 and it is operated in the fundamental harmonic. The electron beam with a low transverse velocity spread ( δ {β_{ bot max }} = 2.26% ) and the transverse-to-axial velocity ratio of the electron beam (α) = 1.37 is obtained. The simulated results of the MIG obtained with the EGUN code have been validated with another trajectory code TRAK. The results on the design output parameters obtained by both the codes are in good agreement. The sensitivity analysis has been carried out by changing the different gun parameters to decide the fabrication tolerance.

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

Rakhman, A.; Hafez, Mohamed A.; Nanda, Sirish K.

Here, a high-finesse Fabry-Perot cavity with a frequency-doubled continuous wave green laser (532 nm) has been built and installed in Hall A of Jefferson Lab for high precision Compton polarimetry. The infrared (1064 nm) beam from a ytterbium-doped fiber amplifier seeded by a Nd:YAG nonplanar ring oscillator laser is frequency doubled in a single-pass periodically poled MgO:LiNbO 3 crystal. The maximum achieved green power at 5 W infrared pump power is 1.74 W with a total conversion efficiency of 34.8%. The green beam is injected into the optical resonant cavity and enhanced up to 3.7 kW with a corresponding enhancementmore » of 3800. The polarization transfer function has been measured in order to determine the intra-cavity circular laser polarization within a measurement uncertainty of 0.7%. The PREx experiment at Jefferson Lab used this system for the first time and achieved 1.0% precision in polarization measurements of an electron beam with energy and current of 1.0 GeV and 50 μA.« less

Automated Sample Exchange Robots for the Structural Biology Beam Lines at the Photon Factory

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

Hiraki, Masahiko; Watanabe, Shokei; Yamada, Yusuke

2007-01-19

We are now developing automated sample exchange robots for high-throughput protein crystallographic experiments for onsite use at synchrotron beam lines. It is part of the fully automated robotics systems being developed at the Photon Factory, for the purposes of protein crystallization, monitoring crystal growth, harvesting and freezing crystals, mounting the crystals inside a hutch and for data collection. We have already installed the sample exchange robots based on the SSRL automated mounting system at our insertion device beam lines BL-5A and AR-NW12A at the Photon Factory. In order to reduce the time required for sample exchange further, a prototype ofmore » a double-tonged system was developed. As a result of preliminary experiments with double-tonged robots, the sample exchange time was successfully reduced from 70 seconds to 10 seconds with the exception of the time required for pre-cooling and warming up the tongs.« less

Double diffraction in an atomic gravimeter

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

Malossi, N.; Bodart, Q.; Merlet, S.

2010-01-15

We demonstrate the realization of a scheme for cold-atom gravimetry based on the recently demonstrated use of double-diffraction beam splitters [T. Leveque, A. Gauguet, F. Michaud, F. Pereira Dos Santos, and A. Landragin, Phys. Rev. Lett. 103, 080405 (2009)], where the use of two retro-reflected Raman beams allows symmetric diffraction in +-(Planck constant/2pi)k{sub eff} momenta. Although in principle restricted to the case of zero Doppler shift, for which the two pairs of Raman beams are simultaneously resonant, such diffraction pulses can remain efficient on atoms with nonzero velocity, such as in a gravimeter, when the frequency of one of themore » two Raman laser sources is modulated. Such pulses are used to realize an interferometer insensitive to laser phase noise and some of the dominant systematics. This approach reduces the technical requirements and would allow the realization of a simple atomic gravimeter. A sensitivity of 1.2x10{sup -7}g per shot is demonstrated.« less

Measurements of forward proton production with incident protons and charged pions on nuclear targets at the CERN Proton Synchrotron

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

Apollonio, M.; Chimenti, P.; Giannini, G.

2010-10-15

Measurements of the double-differential proton production cross-section d{sup 2{sigma}}/dpd{Omega} in the range of momentum 0.5 GeV/c{<=}p<8.0 GeV/c and angle 0.05 rad{<=}{theta}<0.25 rad in collisions of charged pions and protons on beryllium, carbon, aluminium, copper, tin, tantalum, and lead are presented. The data were taken with the large acceptance HARP detector in the T9 beam line of the CERN Proton Synchrotron. Incident particles were identified by an elaborate system of beam detectors and impinged on a target of 5% of a nuclear interaction length. The tracking and identification of the produced particles was performed using the forward spectrometer of the HARPmore » experiment. Results are obtained for the double-differential cross-sections mainly at four incident beam momenta (3,5,8, and 12 GeV/c). Measurements are compared with predictions of the geant4 and mars Monte Carlo generators.« less

DNA Double-strand Breaks Induced byFractionated Neutron Beam Irradiation for Boron Neutron Capture Therapy.

PubMed

Kinashi, Yuko; Yokomizo, Natsuya; Takahashi, Sentaro

2017-04-01

To use the 53BP1 foci assay to detect DNA double-strand breaks induced by fractionated neutron beam irradiation of normal cells. The Kyoto University Research Reactor heavy-water facility and gamma-ray irradiation system were used as experimental radiation sources. After fixation of Chinese Hamster Ovary cells with 3.6% formalin, immunofluorescence staining was performed. Number and size of foci were analyzed using ImageJ software. Fractionated neutron irradiation induced 25% fewer 53BP1 foci than single irradiation at the same dose. By contrast, gamma irradiation induced 30% fewer 53BP1 foci than single irradiation at the same dose. Fractionated neutron irradiation induced larger foci than gamma irradiation, raising the possibility that persistent unrepaired DNA damage was amplified due to the high linear energy transfer component in the neutron beam. Unrepaired cluster DNA damage was more prevalent after fractionated neutron irradiation than after gamma irradiation. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

The stress intensity factor for the double cantilever beam

NASA Technical Reports Server (NTRS)

Fichter, W. B.

1983-01-01

Fourier transforms and the Wiener-Hopf technique are used in conjunction with plane elastostatics to examine the singular crack tip stress field in the double cantilever beam (DCB) specimen. In place of the Dirac delta function, a family of functions which duplicates the important features of the concentrated forces without introducing unmanageable mathematical complexities is used as a loading function. With terms of order h-squared/a-squared retained in the series expansion, the dimensionless stress intensity factor is found to be K (h to the 1/2)/P = 12 to the 1/2 (a/h + 0.6728 + 0.0377 h-squared/a-squared), in which P is the magnitude of the concentrated forces per unit thickness, a is the distance from the crack tip to the points of load application, and h is the height of each cantilever beam. The result is similar to that obtained by Gross and Srawley by fitting a line to discrete results from their boundary collocation analysis.

A Student Assembled Spectrograph with a CCD Detector to Assist with Students' Understanding of Spectrometry

ERIC Educational Resources Information Center

Grove, T. T.; Masters, M. F.

2007-01-01

To help students develop an understanding of the proper use and function of spectrographs and monochromators we describe a student-assembled spectrograph using a "webcam" detector. The apparatus also works well as a low-cost demonstration, helping students make connections between an atomic spectrum observed by eye and a plot of the relative…

Effect of Training Japanese L1 Speakers in the Production of American English /r/ Using Spectrographic Visual Feedback

ERIC Educational Resources Information Center

Patten, Iomi; Edmonds, Lisa A.

2015-01-01

The present study examines the effects of training native Japanese speakers in the production of American /r/ using spectrographic visual feedback. Within a modified single-subject design, two native Japanese participants produced single words containing /r/ in a variety of positions while viewing live spectrographic feedback with the aim of…

X-ray spectrographic determination of cesium and rubidium

USGS Publications Warehouse

Axelrod, J.M.; Adler, I.

1957-01-01

An x-ray spectrographic method for the determination of rubidium and cesium was developed, using the internal-standard method and a four-channel flat-crystal spectrograph. The sensitivity is within 0.1% for cesia and 0.02% for rubidia; the precision is within 10% of the amount present. Results agree well with those obtained by flame photometry and by radio-activation.

Scientific Design of a High Contrast Integral Field Spectrograph for the Subaru Telescope

NASA Technical Reports Server (NTRS)

McElwain, Michael W.

2012-01-01

Ground based telescopes equipped with adaptive optics systems and specialized science cameras are now capable of directly detecting extrasolar planets. We present the scientific design for a high contrast integral field spectrograph for the Subaru Telescope. This lenslet based integral field spectrograph will be implemented into the new extreme adaptive optics system at Subaru, called SCExAO.

Thirty-Meter Telescope: A Technical Study of the InfraRed Multiobject Spectrograph

NASA Astrophysics Data System (ADS)

U, Vivian; Dekany, R.; Mobasher, B.

2013-01-01

The InfraRed Multiobject Spectrograph (IRMS) is an adaptive optics (AO)-fed, reconfigurable near-infrared multi-object spectrograph and imager on the Thirty Meter Telescope (TMT). Its design is based on the MOSFIRE spectrograph currently operating on the Keck Observatory. As one of the first three first-light instruments on the TMT, IRMS is in a mini-conceptual design phase. Here we motivate the science goals of the instrument and present the anticipated sensitivity estimates based on the combination of MOSFIRE with the AO system NFIRAOS on TMT. An assessment of the IRMS on-instrument wavefront sensor performance and vignetting issue will also be discussed.

VizieR Online Data Catalog: The ELM survey. VII. 15 new ELM white dwarf cand. (Brown+, 2016)

NASA Astrophysics Data System (ADS)

Brown, W. R.; Gianninas, A.; Kilic, M.; Kenyon, S. J.; Allende Prieto, C.

2016-05-01

We present observations of 15 new extremely low-mass white dwarf (ELM WD) candidates. Ten objects are selected by color for our targeted spectroscopic ELM Survey program as described in Brown et al. (2012ApJ...744..142B). Five objects come from follow-up spectroscopy of the completed Hypervelocity Star survey. We acquire spectra for the 15 ELM WD candidates using the Blue Channel spectrograph on the 6.5m MMT telescope. We configured the Blue Channel spectrograph to obtain 3650-4500Å spectral coverage with 1.0Å spectral resolution. We acquire additional spectra for 5 objects using the KOSMOS spectrograph on the Kitt Peak National Observatory 4m Mayall telescope on program numbers 2014B-0119 and 2015A-0082. We configured the KOSMOS spectrograph to obtain 3500-6200Å spectral coverage with 2.0Å spectral resolution. We also acquire spectra for objects with g<17mag using the FAST spectrograph on the Fred Lawrence Whipple Observatory 1.5m Tillinghast telescope. We configured the FAST spectrograph to obtain 3500-5500Å spectral coverage with 1.7Å spectral resolution. (3 data files).

Production and characterization of femtosecond laser-written double line waveguides in heavy metal oxide glasses

NASA Astrophysics Data System (ADS)

da Silva, Diego Silvério; Wetter, Niklaus Ursus; de Rossi, Wagner; Kassab, Luciana Reyes Pires; Samad, Ricardo Elgul

2018-01-01

We report the fabrication and characterization of double line waveguides directly written in tellurite and germanate glasses using a femtosecond laser delivering 30 μJ, 80 fs pulses at 4 kHz repetition rate. The double line waveguides produced presented internal losses inferior to 2.0 dB/cm. The output mode profile and the M2 measurements indicate multimodal guiding behavior. A better beam quality for the GeO2 - PbO waveguide was observed when compared with TeO2 - ZnO glass. Raman spectroscopy of the waveguides showed structural modification of the glassy network and indicates that a negative refractive index modification occurs at the focus of the laser beam, therefore allowing for light guiding in between two closely spaced laser written lines. The refractive index change at 632 nm is around 10-4, and the structural changes in the laser focal region of the writing, evaluated by Raman spectroscopy, corroborated our findings that these materials are potential candidates for optical waveguides and passive components. To the best of our knowledge, the two double line configuration demonstrated in the present work was not reported before for germanate or tellurite glasses.

Multiparameter double hole contrast detail phantom: Ability to detect image displacement due to off position anode stem

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

Pauzi, Nur Farahana; Majid, Zafri Azran Abdul; Sapuan, Abdul Halim

Contrast Detail phantom is a quality control tool to analyze the performance of imaging devices. Currently, its function is solely to evaluate the contrast detail characteristic of imaging system. It consists of drilled hole which gives effect to the penetration of x-ray beam divergence to pass through the base of each hole. This effect will lead to false appearance of image from its original location but it does not being visualized in the radiograph. In this study, a new design of Contrast Detail phantom’s hole which consists of double hole construction has been developed. It can detect the image displacementmore » which is due to off position of anode stem from its original location. The double hole differs from previous milled hole, whereby it consists of combination of different hole diameters. Small hole diameter (3 mm) is positioned on top of larger hole diameter (10 mm). The thickness of double hole acrylic blocks is 13 mm. Result revealed that Multiparameter Double Hole Contrast Detail phantom can visualize the shifted flaw image quality produced by x-ray machine due to improper position of the anode stem which is attached to rotor and stator. The effective focal spot of x-ray beam also has been shifted from the center of collimator as a result of off-position anode stem. As a conclusion, the new design of double hole Contrast Detail phantom able to measure those parameters in a well manner.« less

Searching for Dual AGNs in Galaxy Mergers: Understanding Double-Peaked [O III] and Ultra Hard X-rays as Selection Method

NASA Astrophysics Data System (ADS)

McGurk, Rosalie C.; Max, Claire E.; Medling, Anne; Shields, Gregory A.

2015-01-01

When galaxies merge, gas accretes onto both central supermassive black holes. Thus, 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] or of ultra hard X-rays have been proposed as techniques to select dual AGNs efficiently. We studied a sample of double-peaked narrow [O III] emitting AGNs from SDSS DR7. By obtaining new and archival high spatial resolution images taken with the Keck 2 Laser Guide Star Adaptive Optics system and the near-infrared (IR) camera NIRC2, we showed that 30% of 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 these spatially-double candidate dual AGNs with integral field spectroscopy from Keck OSIRIS and Gemini GMOS and with long-slit spectroscopy from Keck NIRSPEC and Shane Kast Double Spectrograph. We find double-peaked emitters are caused sometimes by dual AGN and sometimes by outflows or narrow line kinematics. We also performed Chandra X-ray ACIS-S observations on 12 double-peaked candidate dual AGNs. Using our observations and 8 archival observations, we compare the distribution of X-ray photons to our spatially double near-IR images, measure X-ray luminosities and hardness ratios, and estimate column densities. By assessing what fraction of double-peaked emission line SDSS AGNs are true dual AGNs, we can better determine whether double-peaked [O III] is an efficient dual AGN indicator and constrain the statistics of dual AGNs. A second technique to find dual AGN is the detection of ultra hard X-rays by the Swift Burst Alert Telescope. We use CARMA observations to measure and map the CO(1-0) present in nearby ultra-hard X-ray Active Galactic Nuclei (AGNs) merging with either a quiescent companion galaxy or a companion galaxy hosting a second AGN, in order to understand the role molecular gas plays in feeding this unusual population of ultra-hard X-ray AGNs and to understand ultra-hard X-rays as a dual AGN selection method.

Structure of the Kπ = 4+ bands in 186,188Os

NASA Astrophysics Data System (ADS)

Phillips, A. A.; Garrett, P. E.; Bettermann, L.; Braun, N.; Burke, D. G.; Demand, G. A.; Faestermann, T.; Finlay, P.; Green, K. L.; Hertenberger, R.; Krü; cken, R.; Leach, K. G.; Schumaker, M. A.; Svensson, C. E.; Wirth, H.-F.; Wong, J.

2009-01-01

The structures of 3+ states in Os have been debated over several decades. Based on measured B(E2) values they were interpreted in 186-192Os as Kπ = 4+ two-phonon vibrations, whereas inelastic scattering, and (t,α) work imply a hexadecapole phonon description. To clarify the nature of these Kπ = 4+ bands in 186,188Os, we performed a (3He,d) reaction on 185,187Re targets using 30 MeV 3He beams and a Q3D spectrograph. Absolute cross sections were obtained for excited states up to 3 MeV at 9 angles from 5° to 50°. Results indicate a significant 5/2+[402]π+3/2+[402]π component in agreement with quasiparticle phonon model predictions for a single hexadecapole phonon structure.

Study of 162Er via the (p , t) and (p ,p') reactions

NASA Astrophysics Data System (ADS)

Kisliuk, D.; Garrett, P. E.; Finlay, A.; Bianco, L.; Bildstein, V.; Burbadge, C.; Chagnon-Lessard, S.; Diaz Varela, A.; Dunlop, M. R.; Dunlop, R.; Finlay, P.; Jamieson, D.; Jigmeddorj, B.; Maclean, A. D.; Michetti-Wilson, J.; Leach, K. G.; Radich, A. J.; Rand, E.; Svensson, C. E.; Wong, J.; Ball, G. C.; Triambak, S.; Faestermann, T.; Hertenberger, R.; Wirth, H.-F.

2015-10-01

The nature of excited states in well-deformed nuclei pose a challenge in nuclear structure. In light of this, the study of 162Er via the 164Er (p , t) and 162Er (p ,p') reactions has been initiated to shed light on the structure of these excited states. The experiments were performed at the Maier-Leibnitz Laboratory using a 22 MeV proton beam on highly-enriched targets of 162,164Er and the reaction was analyzed with the Q3D spectrograph. Strong population in the (p , t) reaction of the 02+ state, far greater than other 0+ states, has been observed. Transition matrix elements for population of low-lying states in the (p ,p') reaction have also been extracted. Initial results from these experiments will be presented.

Structure of the Kπ=4+ bands in Os186,188

NASA Astrophysics Data System (ADS)

Phillips, A. A.; Garrett, P. E.; Lo Iudice, N.; Sushkov, A. V.; Bettermann, L.; Braun, N.; Burke, D. G.; Demand, G. A.; Faestermann, T.; Finlay, P.; Green, K. L.; Hertenberger, R.; Leach, K. G.; Krücken, R.; Schumaker, M. A.; Svensson, C. E.; Wirth, H.-F.; Wong, J.

2010-09-01

The (He3,d) single-proton stripping reaction has been performed on targets of Re185,187 to investigate the structures of the 43+ states in Os186,188. The experiment employed 30 MeV He3 beams, and the reaction products were analyzed with a Q3D spectrograph. Absolute cross sections were determined at nine angles between 5° and 50° for states up to approximately 3 MeV in excitation energy. Large (5)/(2)+[402]π+(3)/(2)+[402]π two-quasiparticle components are deduced for the 43+ levels of both isotopes. Their magnitudes are in agreement with calculations performed using the quasiparticle phonon model, which predicts a coexistence of a large hexadecapole with a smaller, but sizable, γ-γ component in the 43+.

K-line spectra from tungsten heated by an intense pulsed electron beam.

PubMed

Pereira, N R; Weber, B V; Apruzese, J P; Mosher, D; Schumer, J W; Seely, J F; Szabo, C I; Boyer, C N; Stephanakis, S J; Hudson, L T

2010-10-01

The plasma-filled rod-pinch diode (PFRP) is an intense source of x-rays ideal for radiography of dense objects. In the PRFP megavoltage electrons from a pulsed discharge concentrate at the pointed end of a 1 mm diameter tapered tungsten rod. Ionization of this plasma might increase the energy of tungsten's Kα(1) fluorescence line, at 59.3182 keV, enough for the difference to be observed by a high-resolution Cauchois transmission crystal spectrograph. When the PFRP's intense hard bremsstrahlung is suppressed by the proper shielding, such an instrument gives excellent fluorescence spectra, albeit with as yet insufficient resolution to see any effect of tungsten's ionization. Higher resolution is possible with various straightforward upgrades that are feasible thanks to the radiation's high intensity.

MIT modular x-ray source systems for the study of plasma diagnostics

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

Coleman, J.W.; Wenzel, K.W.; Petrasso, R.D.

1992-10-01

Two new x-ray source systems are now on line at our facility. Each provides an {ital e}-beam to 25 kV. Targets are interchangeable between machines, and four x-ray detectors may be used simultaneously with a target. The gridded {ital e}-gun of the RACEHORSE system gives a 0.5--1.0-cm pulsable spot on target. The nongridded {ital e}-gun of the SCORPION system provides a 0.3-mm or smaller dc microspot on target. RACEHORSE is being used to study and characterize type-II diamond photoconductors for use in diagnosing plasmas, while SCORPION is being used to develop a slitless spectrograph using photographic film. Source design detailsmore » and some RACEHORSE results are presented.« less

Compact intra-cavity frequency doubled line beam green laser by a laser diode array pumped

NASA Astrophysics Data System (ADS)

Yan, Boxia; Qi, Yan; Wang, Yanwei

2016-10-01

Compact, high power, and low-cost green laser light sources are needed in projection-related applications such as digital cinema, rear-projection television, simulators, and command and control stations. We report a LD array directly pumped intracavity SHG Nd:YVO4/PPMgLN laser without lens or waveguide in this letter. A compact 3.12 W green laser was demonstrated by intra-cavity frequency doubled using a PPMgLN bulk crystal by a 19-emitter LD array pumped(single bar), the conversion efficiency from input LD array was 9.2%. A line-beam output suitable for laser projectors was generated, which has the potential to be scalable to small volumes and low costs for laser projection displays.

Double differential neutron spectra generated by the interaction of a 12 MeV/nucleon 36S beam on a thick natCu target

NASA Astrophysics Data System (ADS)

Trinh, N. D.; Fadil, M.; Lewitowicz, M.; Ledoux, X.; Laurent, B.; Thomas, J.-C.; Clerc, T.; Desmezières, V.; Dupuis, M.; Madeline, A.; Dessay, E.; Grinyer, G. F.; Grinyer, J.; Menard, N.; Porée, F.; Achouri, L.; Delaunay, F.; Parlog, M.

2018-07-01

Double differential neutron spectra (energy, angle) originating from a thick natCu target bombarded by a 12 MeV/nucleon 36S16+ beam were measured by the activation method and the Time-of-flight technique at the Grand Accélérateur National d'Ions Lourds (GANIL). A neutron spectrum unfolding algorithm combining the SAND-II iterative method and Monte-Carlo techniques was developed for the analysis of the activation results that cover a wide range of neutron energies. It was implemented into a graphical user interface program, called GanUnfold. The experimental neutron spectra are compared to Monte-Carlo simulations performed using the PHITS and FLUKA codes.

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

Palma, Giuseppina; Cozzarini, Luca; Capria, Ennio

A home-made system for incident photon-to-electron conversion efficiency (IPCE) characterization, based on a double-beam UV-Vis spectrophotometer, has been set up. In addition to its low cost (compared to the commercially available apparatuses), the double-beam configuration gives the advantage to measure, autonomously and with no need for supplementary equipment, the lamp power in real time, compensating possible variations of the spectral emission intensity and quality, thus reducing measurement times. To manage the optical and electronic components of the system, a custom software has been developed. Validations carried out on a common silicon-based photodiode and on a dye-sensitized solar cell confirm themore » possibility to adopt this system for determining the IPCE of solar cells, including dye-sensitized ones.« less

Single Mode, Extreme Precision Doppler Spectrographs

NASA Astrophysics Data System (ADS)

Schwab, Christian; Leon-Saval, Sergio G.; Betters, Christopher H.; Bland-Hawthorn, Joss; Mahadevan, Suvrath

2014-04-01

The `holy grail' of exoplanet research today is the detection of an earth-like planet: a rocky planet in the habitable zone around a main-sequence star. Extremely precise Doppler spectroscopy is an indispensable tool to find and characterize earth-like planets; however, to find these planets around solar-type stars, we need nearly one order of magnitude better radial velocity (RV) precision than the best current spectrographs provide. Recent developments in astrophotonics (Bland-Hawthorn & Horton 2006, Bland-Hawthorn et al. 2010) and adaptive optics (AO) enable single mode fiber (SMF) fed, high resolution spectrographs, which can realize the next step in precision. SMF feeds have intrinsic advantages over multimode fiber or slit coupled spectrographs: The intensity distribution at the fiber exit is extremely stable, and as a result the line spread function of a well-designed spectrograph is fully decoupled from input coupling conditions, like guiding or seeing variations (Ihle et al. 2010). Modal noise, a limiting factor in current multimode fiber fed instruments (Baudrand & Walker 2001), can be eliminated by proper design, and the diffraction limited input to the spectrograph allows for very compact instrument designs, which provide excellent optomechanical stability. A SMF is the ideal interface for new, very precise wavelength calibrators, like laser frequency combs (Steinmetz et al. 2008, Osterman et al. 2012), or SMF based Fabry-Perot Etalons (Halverson et al. 2013). At near infrared wavelengths, these technologies are ready to be implemented in on-sky instruments, or already in use. We discuss a novel concept for such a spectrograph.

High peak current operation of x-ray free-electron laser multiple beam lines by suppressing coherent synchrotron radiation effects

NASA Astrophysics Data System (ADS)

Hara, Toru; Kondo, Chikara; Inagaki, Takahiro; Togawa, Kazuaki; Fukami, Kenji; Nakazawa, Shingo; Hasegawa, Taichi; Morimoto, Osamu; Yoshioka, Masamichi; Maesaka, Hirokazu; Otake, Yuji; Tanaka, Hitoshi

2018-04-01

The parallel operation of multiple beam lines is an important means to expand the opportunity of user experiments at x-ray free-electron laser (XFEL) facilities. At SPring-8 Angstrom free-electron laser (SACLA), the multi-beam-line operation had been tested using two beam lines, but transverse coherent synchrotron radiation (CSR) effects at a dogleg beam transport severely limited the laser performance. To suppress the CSR effects, a new beam optics based on two double bend achromat (DBA) structures was introduced for the dogleg. After the replacement of the beam optics, high peak current bunches of more than 10 kA are now stably transported through the dogleg and the laser pulse output is increased by a factor of 2-3. In the multi-beam-line operation of SACLA, the electron beam parameters, such as the beam energy and peak current, can be adjusted independently for each beam line. Thus the laser output can be optimized and wide spectral tunability is ensured for all beam lines.

Beam dynamics simulation of a double pass proton linear accelerator

DOE PAGES

Hwang, Kilean; Qiang, Ji

2017-04-03

A recirculating superconducting linear accelerator with the advantage of both straight and circular accelerator has been demonstrated with relativistic electron beams. The acceleration concept of a recirculating proton beam was recently proposed and is currently under study. In order to further support the concept, the beam dynamics study on a recirculating proton linear accelerator has to be carried out. In this paper, we study the feasibility of a two-pass recirculating proton linear accelerator through the direct numerical beam dynamics design optimization and the start-to-end simulation. This study shows that the two-pass simultaneous focusing without particle losses is attainable including fullymore » 3D space-charge effects through the entire accelerator system.« less

Spectra of Th/Ar and U/Ne hollow cathode lamps for spectrograph calibration

NASA Astrophysics Data System (ADS)

Nave, Gillian; Shlosberg, Ariel; Kerber, Florian; Den Hartog, Elizabeth; Neureiter, Bianca

2018-01-01

Low-current Th/Ar hollow cathode lamps have long been used for calibration of astronomical spectrographs on ground-based telescopes. Thorium is an attractive element for calibration as it has a single isotope, has narrow spectral lines, and has a dense spectrum covering the whole of the visible region. However, the high density of the spectrum that makes it attractive for calibrating high-resolution spectrographs is a detriment for lower resolution spectrographs and this is not obvious by examination of existing linelists. In addition, recent changes in regulations regarding the handling of thorium have led to a degradation in the quality of Th/Ar calibration lamps, with contamination by molecular ThO lines that are strong enough to obscure the calibration lines of interest.We are pursuing two approaches to these problems. First, we have expanded and improved the NIST Standard Reference Database 161, "Spectrum of Th-Ar Hollow Cathode Lamps" to cover the region 272 nm to 5500 nm. Spectra of hollow cathode lamps at up to 3 different currents can now be displayed simultaneously. Interactive zooming and the ability to convolve any of the spectra with a Gaussian or uploaded instrument profile enable the user to see immediately what the spectrum would look like at the particular resolution of their spectrograph. Second, we have measured the spectrum of a recent, contaminated Th/Ar hollow cathode lamp using a high-resolution Echelle spectrograph (Madison Wisconsin) at a resolving power (R~ 250,000). This significantly exceeds the resolving power of most astronomical spectrographs and resolves many of the molecular lines of ThO. With these spectra we are measuring and calibrating the positions of these molecular lines in order to make them suitable for spectrograph calibration.In the near infrared region, U/Ne hollow cathode lamps give a higher density of calibration lines than Th/Ar lamps and will be implemented on the upgraded CRIRES+ spectrograph on ESO’s Very Large Telescope in Chile. A new atlas of the U/Ne spectrum as measured by CRIRES will be presented.

Optimum performance of electron beam pumped GaAs and GaN

NASA Astrophysics Data System (ADS)

Afify, M. S.; Moslem, W. M.; Hassouba, M. A.; Abu-El Hassan, A.

2018-05-01

This paper introduces a physical solution in order to overcome the damage to semiconductors, due to increasing temperature during the pumping process. For this purpose, we use quantum hydrodynamic fluid equations, including different quantum effects. This study concludes that nonlinear acoustic waves, in the form of soliton and shock-like (double layer) pulses, can propagate depending on the electron beam temperature and the streaming speed. Therefore, one can precisely tune the beam parameters in order to avoid such unfavorable noises that may lead to defects in semiconductors.

Shunting arc plasma source for pure carbon ion beam.

PubMed

Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

2012-02-01

A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA∕mm(2) at the peak of the pulse.

Electron Beam Lithography Double Step Exposure Technique for Fabrication of Mushroom-Like Profile in Bilayer Resist System

NASA Astrophysics Data System (ADS)

Kornelia, Indykiewicz; Bogdan, Paszkiewicz; Tomasz, Szymański; Regina, Paszkiewicz

2015-01-01

The Hi/Lo bilayer resist system exposure in e-beam lithography (EBL) process, intended for mushroom-like profile fabrication, was studied. Different exposure parameters and theirs influence on the resist layers were simulated in CASINO software and the obtained results were compared with the experimental data. The AFM technique was used for the estimation of the e-beam penetration depth in the resist stack. Performed numerical and experimental results allow us to establish the useful ranges of the exposure parameters.

A multi-damages identification method for cantilever beam based on mode shape curvatures and Kriging surrogate model

NASA Astrophysics Data System (ADS)

Xie, Fengle; Jiang, Zhansi; Jiang, Hui

2018-05-01

This paper presents a multi-damages identification method for Cantilever Beam. First, the damage location is identified by using the mode shape curvatures. Second, samples of varying damage severities at the damage location and their corresponding natural frequencies are used to construct the initial Kriging surrogate model. Then a particle swarm optimization (PSO) algorithm is employed to identify the damage severities based on Kriging surrogate model. The simulation study of a double-damaged cantilever beam demonstrated that the proposed method is effective.

Coherence measurement with digital micromirror device.

PubMed

Partanen, Henri; Turunen, Jari; Tervo, Jani

2014-02-15

We measure the complex-valued spatial coherence function of a multimode broad-area laser diode using Young's classical double slit experiment realized with a digital micromirror device. We use this data to construct the coherent modes of the beam and to simulate its propagation before and after the measurement plane. When comparing the results to directly measured intensity profiles, we find excellent correspondence to the extent that even small details of the beam can be predicted. We also consider the number of measurement points required to model the beam with sufficient accuracy.

Shunting arc plasma source for pure carbon ion beam

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

Koguchi, H.; Sakakita, H.; Kiyama, S.

2012-02-15

A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA/mm{sup 2} at the peak of the pulse.

Homogeneous spectral broadening of pulsed terahertz quantum cascade lasers by radio frequency modulation.

PubMed

Wan, W J; Li, H; Cao, J C

2018-01-22

The authors present an experimental investigation of radio frequency modulation on pulsed terahertz quantum cascade lasers (QCLs) emitting around 4.3 THz. The QCL chip used in this work is based on a resonant phonon design which is able to generate a 1.2 W peak power at 10 K from a 400-µm-wide and 4-mm-long laser with a single plasmon waveguide. To enhance the radio frequency modulation efficiency and significantly broaden the terahertz spectra, the QCLs are also processed into a double-metal waveguide geometry with a Silicon lens out-coupler to improve the far-field beam quality. The measured beam patterns of the double-metal QCL show a record low divergence of 2.6° in vertical direction and 2.4° in horizontal direction. Finally we perform the inter-mode beat note and terahertz spectra measurements for both single plasmon and double-metal QCLs working in pulsed mode. Since the double-metal waveguide is more suitable for microwave signal transmission, the radio frequency modulation shows stronger effects on the spectral broadening for the double-metal QCL. Although we are not able to achieve comb operation in this work for the pulsed lasers due to the large phase noise, the homogeneous spectral broadening resulted from the radio frequency modulation can be potentially used for spectroscopic applications.

Observation of the effects of stronger magnetic fields on warm, higher energy electrons and ion beams transiting a double layer in a helicon plasma

NASA Astrophysics Data System (ADS)

Scharer, John; Sung, Yung-Ta; Li, Yan

2017-10-01

Fast, two-temperature electrons (>80 eV, Te =13 eV tail, 4 eV bulk) with substantial tail density fractions are created at low (< = 1.7 mtorr) Ar pressure @ 340 G in the antenna region with nozzle mirror ratio of 1.4 on MadHeX @ 900W. These distributions including a fast tail are observed upstream of a double layer. The fast, untrapped tail electrons measured downstream of the double layer have a higher temperature of 13 eV than the trapped, upstream electrons of 4 eV temperature. Upstream plasma potential fluctuations of + - 30 percent are observed. An RF-compensated Langmuir probe is used to measure the electron temperatures and densities and OES, mm wave IF and an RPA for the IEDF are also utilized. As the magnetic field is increased to 1020 G, an increase in the electron temperature and density upstream of the double layer is observed with Te= 15-25 eV with a primarily single temperature mode. Accelerated ion beam energies in the range of 65-120 eV are observed as the magnetic field is increased from 340 to 850 G. The role of the nozzle, plasma double layer and helicon wave coupling on the EEDF and ion acceleration will be discussed. Research supported in part by the University of Wisconsin.

Fusion splicing: a novel approach to fiber connections for the Dark Energy Spectroscopic Instrument

NASA Astrophysics Data System (ADS)

Fagrelius, Parker; Poppett, Claire; Edelstein, Jerry

2016-08-01

The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the universe using the Baryon Acoustic Oscillation (BAO) technique and the growth of structure using redshift-space distortions (RSD). The spectra of 40 million galaxies over 14,000 square degrees will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers will run 50 meters from the focal plane to the coudé room where they feed ten broadband spectrographs. The focal plane assembly will be integrated separately from the spectrograph slits and long fiber cables in order to ease integration flow, and the two subsystems will be connected before final integration on the telescope. In order to retain maximum throughput and minimize the focal ratio degradation (FRD) when connecting the fiber system, we are employing fusion splicing as opposed to mechanical connectorization. For the best splice performance, the optical fibers are stripped of their polyimide coating, precision cleaved, and then fused with a heating filament. We report results from the splicing process, measuring a collimated FRD increase of less than 0.5 degrees for a f/3.9 input beam compared to >1 degree increase for mechanical connectors. We also show that the near field performance is minimally degraded after splicing. These results represent the first of their kind for a fiber-fed astronomical instrument.

Fiber Scrambling for Extreme Doppler Precision

NASA Astrophysics Data System (ADS)

Spronck, Julien; Kaplan, Z.; Fischer, D.

2011-09-01

The detection of Earth-like exoplanets with the radial velocity method requires extreme Doppler precision and long-term stability in order to measure tiny reflex velocities in the host star. Recent planet searches have led to the detection of so called “super-Earths” (up to a few Earth masses) that induce radial velocity changes of about 1 m/s. However, the detection of true Earth analogs requires a precision of 10 cm/s. One of the factors limiting Doppler precision is variation in the Point Spread Function (PSF) from observation to observation due to changes in the illumination of the slit and spectrograph optics. Thus, this stability has become a focus of current instrumentation work. Fiber optics have been used since the 1980’s to couple telescopes to high-precision spectrographs, initially for simpler mechanical design and control. However, fiber optics are also naturally efficient scramblers. Scrambling refers to a fiber’s ability to produce an output beam independent of input. Our research is focused on understanding the scrambling properties of fibers with different geometries (circular, square, octagonal), different lengths and fiber sizes. Another important parameter when it comes to fibers is the so-called focal ratio degradation (FRD), which accounts for a different (faster) focal ratio after the fiber than the one sent into the fiber. In this paper, we will present new insight on fiber scrambling, FRD and what we call fiber personality, which describes differing behaviors for supposedly identical fiber.

Elliptical varied line-space (EVLS) gratings

NASA Astrophysics Data System (ADS)

Thomas, Roger J.

2004-10-01

Imaging spectroscopy at wavelengths below 2000 Å offers an especially powerful method for studying many extended high-temperature astronomical objects, like the Sun and its outer layers. But the technology to make such measurements is also especially challenging, because of the poor reflectance of all standard materials at these wavelengths, and because the observation must be made from above the absorbing effects of the Earth's atmosphere. To solve these problems, single-reflection stigmatic spectrographs for XUV wavelengths have bee flown on several space missions based on designs with toroidal uniform line-space (TULS) or spherical varied line-space (SVLS) gratings that operate at near normal-incidence. More recently, three solar EUV/UV instruments have been selected that use toroidal varied line-space (TVLS) gratings; these are SUMI and RAISE, both sounding rocket payloads, and NEXUS, a SMEX satellite-mission. The next logical extension to such designs is the use of elliptical surfaces for varied line-space (EVLS) rulings. In fact, EVLS designs are found to provide superior imaging even at very large spectrograph magnifications and beam-speeds, permitting extremely high-quality performance in remarkably compact instrument packages. In some cases, such designs may be optimized even further by using a hyperbolic surface for the feeding telescope. The optical characteristics of two solar EUV spectrometers based on these concepts are described: EUS and EUI, both being developed as possible instruments for ESA's Solar Orbiter mission by consortia led by RAL and by MSSL, respectively.

A new Cassegrain calibration lamp unit for the Blanco Telescope

NASA Astrophysics Data System (ADS)

Points, S. D.; James, D. J.; Tighe, R.; Montané, A.; David, N.; Martínez, M.

2016-08-01

The f/8 RC-Cassegrain Focus of the Blanco Telescope at Cerro Tololo Inter-American Observatory, hosts two new instruments: COSMOS, a multi-object spectrograph in the visible wavelength range (350 - 1030nm), and ARCoIRIS, a NIR cross-dispersed spectrograph featuring 6 spectral orders spanning 0.8 - 2.45μm. Here we describe a calibration lamp unit designed to deliver the required illumination at the telescope focal plane for both instruments. These requirements are: (1) an f/8 beam of light covering a spot of 92mm diameter (or 10 arcmin) for a wavelength range of 0.35μm through 2.5μm and (2) no saturation of flat-field calibrations for the minimal exposure times permitted by each instrument, and (3) few saturated spectral lines when using the wavelength calibration lamps for the instruments. To meet these requirements this unit contains an adjustable quartz halogen lamp for flat-field calibrations, and one hollow cathode lamp and four penray lamps for wavelength calibrations. The wavelength calibration lamps are selected to provide optimal spectral coverage for the instrument mounted and can be used individually or in sets. The device designed is based on an 8-inch diameter integrating sphere, the output of which is optimized to match the f/8 calibration input delivery system which is a refractive system based on fused-silica lenses. We describe the optical design, the opto-mechanical design, the electronic control and give results of the performance of the system.

Inkjet Assisted Creation of Self-Healing Layers Between Composite Plies

DTIC Science & Technology

2013-07-29

technology into a prepreg manufacturing process. The approach consisted of depositing novel thermoplastic low-viscosity microdroplets with chemically and...mechanically comparable properties to epoxy matrix in aerospace grade composites onto fiber-reinforced epoxy prepregs before curing using an ink-jet... prepreg Cycom977-2. Double cantilever beam (DCB) and short beam shear (SBS) tests were used to evaluate the self-healing efficiency. It was shown

The double polarization program of CBELSA/TAPS

NASA Astrophysics Data System (ADS)

Thiel, Annika

2014-06-01

The excitation spectrum of the proton consists of resonances with substancial width which are often strongly overlapping and are therefore difficult to disentangle. To determine the exact contributions and identify these resonances, a partial wave analysis solution has to be found. For a complete experiment, which leads to an unambiguous solution, several single and double polarization observables are needed. With the Crystal Barrel/TAPS experiment at ELSA, the measurement of double polarization observables in different reactions is possible by using a circularly or linearly polarized photon beam on a transversely or longitudinally polarized butanol target.

SU-F-T-138: Commissioning and Evaluating Dose Computation Models for a Dedicated Proton Line Scanning Beam Nozzle in Eclipse Treatment Planning System

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

Tsai, P; Chang Gung University, Taoyuan, Taiwan; Huang, H

Purpose: In this study, we present an effective method to derive low dose envelope of the proton in-air spot fluence at beam positions other than the isocenter to reduce amount of measurements required for planning commission. Also, we demonstrate commissioning and validation results of this method to the Eclipse treatment planning system (version 13.0.29) for a Sumitomo dedicated proton line scanning beam nozzle. Methods: The in-air spot profiles at five beam-axis positions (±200, ±100 and 0 mm) were obtained in trigger mode using a MP3 Water tank (PTW-Freiburg) and a pinpoint ionization chamber (model 31014, PTW-Freiburg). Low dose envelope (belowmore » 1% of the center dose) of the spot profile at isocenter was obtained by repeated point measurements to minimize dosimetry uncertainty. The double Gaussian (DG) model was used to fit and obtain optimal σ1, σ2 and their corresponding weightings through our in-house MATLAB (Mathworks) program. σ1, σ2 were assumed to expand linearly along the beam axis from a virtual source position calculated by back projecting fitted sigmas from the single Gaussian (SG) model. Absolute doses in water were validated using an Advanced Markus chamber at the depth of 2cm with Pristine Peak (BP) R90d ranging from 5–32 cm for 10×10 cm2 scanned fields. The field size factors were verified with square fields from 2 to 20 cm at 2cm and before BP depth. Results: The absolute dose outputs were found to be within ±3%. For field size factor, the agreement between calculated and measurement were within ±2% at 2cm and ±3% before BP, except for the field size below 2×2 cm2. Conclusion: The double Gaussian model was found to be sufficient for characterizing the Sumitomo dedicated proton line scanning nozzle. With our effective double Gaussian fitting method, we are able to save significant proton beam time with acceptable output accuracy.« less

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

Pirlepesov, F.; Shin, J.; Moskvin, V. P.

Purpose: Dose weighted Linear Energy Transfer (LETd) analysis of critical structures may be useful in understanding the side effects of the proton therapy. The objective is to analyze the differences between LETd and dose distributions in brain tumor patients receiving double scattering proton therapy, to quantify LETd variation in critical organs, and to identify beam arrangements contributing to high LETd in critical organs. Methods: Monte Carlo simulations of 9 pediatric brain tumor patients were performed. The treatment plans were reconstructed with the TOPAS Monte Carlo code to calculate LETd and dose. The beam data were reconstructed proximal to the aperturemore » of the double scattering nozzle. The dose and LETd to target and critical organs including brain stem, optic chiasm, lens, optic nerve, pituitary gland, and hypothalamus were computed for each beam. Results: Greater variability in LETd compared to dose was observed in the brainstem for patients with a variety of tumor types including 5 patients with tumors located in the posterior fossa. Approximately 20%–44% brainstem volume received LETd of 5kev/µm or greater from beams within gantry angles 180°±30° for 5 patients treated with a 3 beam arrangement. Critical organs received higher LETd when located in the vicinity of the beam distal edge. Conclusion: This study presents a novel strategy in the evaluation of the proton treatment impact on critical organs. While the dose to critical organs is confined below the required limits, the LETd may have significant variation. Critical organs in the vicinity of beam distal edge receive higher LETd and depended on beam arrangement, e.g. in posterior fossa tumor treatment, brainstem receive higher LETd from posterior-anterior beams. This study shows importance of the LETd analysis of the radiation impact on the critical organs in proton therapy and may be used to explain clinical imaging observations after therapy.« less

Laser marking on soda-lime glass by laser-induced backside wet etching with two-beam interference

NASA Astrophysics Data System (ADS)

Nakazumi, Tomoka; Sato, Tadatake; Narazaki, Aiko; Niino, Hiroyuki

2016-09-01

For crack-free marking of glass materials, a beam-scanning laser-induced backside wet etching (LIBWE) process by a beam spot with a fine periodic structure was examined. The fine periodic structure was produced within a beam spot by means of a Mach-Zehnder interferometer incorporated to the optical setup for the beam-scanning LIBWE. A fine structure with a period of 9 µm was observed within the microstructures with a diameter of ca. 40 µm fabricated by a laser shot under double-beam irradiation, and they could be homogeneously fabricated within an area of 800  ×  800 µm. The area filled with the microstructures, including fine periodic structures, could be observed in high contrast under a diffuse, on-axis illumination that was used in commercial QR code readers.

Electromagnetic sinc Schell-model beams and their statistical properties.

PubMed

Mei, Zhangrong; Mao, Yonghua

2014-09-22

A class of electromagnetic sources with sinc Schell-model correlations is introduced. The conditions on source parameters guaranteeing that the source generates a physical beam are derived. The evolution behaviors of statistical properties for the electromagnetic stochastic beams generated by this new source on propagating in free space and in atmosphere turbulence are investigated with the help of the weighted superposition method and by numerical simulations. It is demonstrated that the intensity distributions of such beams exhibit unique features on propagating in free space and produce a double-layer flat-top profile of being shape-invariant in the far field. This feature makes this new beam particularly suitable for some special laser processing applications. The influences of the atmosphere turbulence with a non-Kolmogorov power spectrum on statistical properties of the new beams are analyzed in detail.

GRACES, the Gemini remote access CFHT ESPaDOnS spectrograph: initial design and testing

NASA Astrophysics Data System (ADS)

Tollestrup, Eric V.; Pazder, John; Barrick, Gregory; Martioli, Eder; Schiavon, Ricardo; Anthony, André; Halman, Mark; Veillet, Christian

2012-09-01

The Gemini Remote Access CFHT ESPaDOnS Spectrograph (GRACES) is an innovative instrumentation experiment that will demonstrate if ESPaDOnS, a bench-mounted high-resolution optical spectrograph at CFHT, can be fed by a 270-m long fiber from the Gemini-North telescope with low enough losses to remain competitive with conventional spectrographs on other 8 to 10-m telescopes. Detailed simulations have shown that GRACES should be more sensitive than the HIRES spectrograph at Keck Observatory at wavelengths longer than about 600-700 nm. This result is possible by using FPB-type of optical fibers made by Polymicro Technologies and by keeping the critical focal ratio degradation (FRD) losses to less than 10%. Laboratory tests on these FPB optical fibers are underway and show that for 36-m lengths that the FRD losses are as low as 0.8% with a repeatability of 1%. Tests are currently underway on 280-m lengths.

HESP: Instrument control, calibration and pipeline development

NASA Astrophysics Data System (ADS)

Anantha, Ch.; Roy, Jayashree; Mahesh, P. K.; Parihar, P. S.; Sangal, A. K.; Sriram, S.; Anand, M. N.; Anupama, G. C.; Giridhar, S.; Prabhu, T. P.; Sivarani, T.; Sundararajan, M. S.

Hanle Echelle SPectrograph (HESP) is a fibre-fed, high resolution (R = 30,000 and 60,000) spectrograph being developed for the 2m HCT telescope at IAO, Hanle. The major components of the instrument are a) Cassegrain unit b) Spectrometer instrument. An instrument control system interacting with a guiding unit at Cassegrain interface as well as handling spectrograph functions is being developed. An on-axis auto-guiding using the spill-over angular ring around the input pinhole is also being developed. The stellar light from the Cassegrain unit is taken to the spectrograph using an optical fiber which is being characterized for spectral transmission, focal ratio degradation and scrambling properties. The design of the thermal enclosure and thermal control for the spectrograph housing is presented. A data pipeline for the entire Echelle spectral reduction is being developed. We also plan to implement an instrument physical model based calibration into the main data pipeline and in the maintenance and quality control operations.

Reconstructive correction of aberrations in nuclear particle spectrographs

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

Berz, M.; Joh, K.; Nolen, J.A.

A method is presented that allows the reconstruction of trajectories in particle spectrographs and the reconstructive correction of residual aberrations that otherwise limit the resolution. Using a computed or fitted high order transfer map that describes the uncorrected aberrations of the spectrograph, it is possible to calculate a map via an analytic recursion relation that allows the computation of the corrected data of interest such as reaction energy and scattering angle as well as the reconstructed trajectories in terms of position measurements in two planes near the focal plane. The technique is only limited by the accuracy of the positionmore » measurements, the incoherent spot sizes, and the accuracy of the transfer map. In practice the method can be expressed as an inversion of a nonlinear map and implemented in the differential algebraic framework. The method is applied to correct residual aberrations in the S800 spectrograph which is under construction at the National Superconducting Cyclotron Laboratory at Michigan State University and to two other high resolution spectrographs.« less

A generic double-curvature piezoelectric shell energy harvester: Linear/nonlinear theory and applications

NASA Astrophysics Data System (ADS)

Zhang, X. F.; Hu, S. D.; Tzou, H. S.

2014-12-01

Converting vibration energy to useful electric energy has attracted much attention in recent years. Based on the electromechanical coupling of piezoelectricity, distributed piezoelectric zero-curvature type (e.g., beams and plates) energy harvesters have been proposed and evaluated. The objective of this study is to develop a generic linear and nonlinear piezoelectric shell energy harvesting theory based on a double-curvature shell. The generic piezoelectric shell energy harvester consists of an elastic double-curvature shell and piezoelectric patches laminated on its surface(s). With a current model in the closed-circuit condition, output voltages and energies across a resistive load are evaluated when the shell is subjected to harmonic excitations. Steady-state voltage and power outputs across the resistive load are calculated at resonance for each shell mode. The piezoelectric shell energy harvesting mechanism can be simplified to shell (e.g., cylindrical, conical, spherical, paraboloidal, etc.) and non-shell (beam, plate, ring, arch, etc.) distributed harvesters using two Lamé parameters and two curvature radii of the selected harvester geometry. To demonstrate the utility and simplification procedures, the generic linear/nonlinear shell energy harvester mechanism is simplified to three specific structures, i.e., a cantilever beam case, a circular ring case and a conical shell case. Results show the versatility of the generic linear/nonlinear shell energy harvesting mechanism and the validity of the simplification procedures.

Experimental equipment for an advanced ISOL facility[Isotope Separation On-Line Facility

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

Baktash, C.; Lee, I.Y.; Rehm, K.E.

This report summarizes the proceedings and recommendations of the Workshop on the Experimental Equipment for an Advanced ISOL Facility which was held at Lawrence Berkeley National Laboratory on July 22--25, 1998. The purpose of this workshop was to discuss the performance requirements, manpower and cost estimates, as well as a schedule of the experimental equipment needed to fully exploit the new physics which can be studied at an advanced ISOL facility. An overview of the new physics opportunities that would be provided by such a facility has been presented in the White Paper that was issued following the Columbus Meeting.more » The reactions and experimental techniques discussed in the Columbus White Paper served as a guideline for the formulation of the detector needs at the Berkeley Workshop. As outlined a new ISOL facility with intense, high-quality beams of radioactive nuclei would provide exciting new research opportunities in the areas of: the nature of nucleonic matter; the origin of the elements; and tests of the Standard Model. After an introductory section, the following equipment is discussed: gamma-ray detectors; recoil separators; magnetic spectrographs; particle detectors; targets; and apparatus using non-accelerated beams.« less

High numerical aperture multimode fibers for prime focus use

NASA Astrophysics Data System (ADS)

Zhang, Kaiyuan; Zheng, Jessica R.; Saunders, Will

2016-07-01

Modern telescopes typically have prime focus speeds too fast for direct use with standard numerical aperture (NA=0.22+/-0.02) silica-cored fibers. Specifically, the current design for the proposed Maunakea Spectroscopic Explorer (MSE) telescope is f/2, requiring fibers with NA>0.25. Micro foreoptics can be used to slow the beam, as used on the prime focus spectrograph (PFS) on Subaru, but this adds cost and complexity, and increases losses. An attractive alternative is offered by high NA pure silica-cored fibers, which can be used directly at f/2, and which are now available from multiple vendors. We present throughput and focal ratio degradation measurements on two samples of these high NA fibers. It is found that the measured attenuation losses are comparable with the best available standard NA fibers. The fibers were also tested for focal ratio degradation, and the fiber from CeramOptec was found to have acceptable FRD, representng additional collimator losses 1%. The near field performance of the high NA fiber is also investigated and these high NA fibers exhibit very good scrambling performance; we saw no evidence for significant output near-field variations for varying input beam angles or position in a 50m fiber.

New separators at the ATLAS facility

NASA Astrophysics Data System (ADS)

Back, Birger; Agfa Collaboration; Airis Team

2015-10-01

Two new separators are being built for the ATLAS facility. The Argonne Gas-Filled Analyzer (AGFA) is a novel design consisting of a single quadrupole and a multipole magnet that has both dipole and quadrupole field components. The design allows for placing Gammasphere at the target position while providing a solid angle of ~ 22 msr for capturing recoil products emitted at zero degrees. This arrangement enables studies of prompt gamma ray emission from weakly populated trans-fermium nuclei and those near the doubly-magic N = Z = 50 shell closure measured in coincidence with the recoils registered by AGFA. The Argonne In-flight Radioactive Ion Separator (AIRIS) is a magnetic chicane that will be installed immediately downstream of the last ATLAS cryostat and serve to separate radioactive ion beams generated in flight at an upstream high intensity production target. These beams will be further purified by a downstream RF sweeper and transported into a number of target stations including HELIOS, the Enge spectrograph, the FMA and Gammasphere. This talk will present the status of these two projects. This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.

Ultra-High Sensitivity Techniques for the Determination of 3 He /4 He Abundances in Helium by Accelerator Mass Spectrometry

NASA Astrophysics Data System (ADS)

Mumm, H. P.; Huber, M.; Bauder, W.; Abrams, N.; Deibel, C.; Huffer, C.; Huffman, P.; Schelhammer, K.; Janssens, R.; Jiang, C.; Scott, R.; Pardo, R.; Rehm, K.; Vondrasek, R.; Swank, C.; O'Shaughnessy, C.; Paul, M.; Yang, L.

2017-01-01

We report the development of an Accelerator Mass Spectrometry technique to measure the 3He/4He isotopic ratio using a radio frequency (RF) discharge source and the ATLAS facility at Argonne National Laboratory. Control over 3He/4He ratio in helium several orders of magnitude lower than natural abundance is critical for neutron lifetime and source experiments using liquid helium. Due to low ultimate beam currents, the ATLAS accelerator and beam line were tuned using a succession of species of the same M/q. A unique RF source was developed for the experiment due to large natural 3He backgrounds. Analog H_3 + and DH + molecular ions are eliminated by dissociation via a gold stripper foil near the detector. The stripped ions were dispersed in a magnetic spectrograph and 3He2 + ions counted in the focal plane detector. This technique is sensitive to 3 He /4 He ratios in the regime of 10-12 with backgrounds that appear to be below 10-14. The techniques used to reduce the backgrounds and remaining outstanding problems will be presented along with results from measurements on high purity 4He samples.

Development of Fast, Background-Limited Transition-Edge Sensors for the Background-Limited Infrared/Sub-mm Spectrograph (BLISS) for SPICA

NASA Technical Reports Server (NTRS)

Beyer, Andrew D.; Runyan, M. C.; Kenyon, M.; Echternach, P. M .; Chui, T.; Bumble, B.; Bradford, C. M.; Holmes, W. A.; Bock, J. J.

2012-01-01

We report experimental progress toward demonstrating background-limited arrays of membrane-isolated transition-edge sensors (TESs) for the Background Limited Infrared/Sub-mm Spectrograph (BLISS). BLISS is a space-borne instrument with grating spectrometers for wavelengths lambda=35-435 micron and with R=lambda/delta lambda approximately equals 500. The goals for BLISS TESs are: noise equivalent power (NEP) = 5x10 (sup -20) W/Hz(exp 1/2) and response time tau <30ms. We expect background-limited performance from bilayers TESs with T(sub c) = 65mK and G=15fW/K. However, such TESs cannot be operated at 50mK unless stray power on the devices, or dark power P(sub D), is less than 200aW. We describe criteria for measuring P(sub D) that requires accurate knowledge of TC. Ultimately, we fabricated superconducting thermistors from Ir (T(sub c) >= 135mK) and Mo/Cu proximitized bilayers, where T(sub c) is the thermistor transition temperature. We measured the Ir TES arrays in our 50mK adiabatic demagnetization refrigerator test system, which can measure up to eight 1x32 arrays simultaneously using a time-division multiplexer, as well as our single-pixel test system which can measure down to 15mK. In our previous Ir array measurements our best reported performance was NEP=2.5x10(exp -19) W/Hz(sub 1/2) and Tau approximately equals 5ms for straight-beam TESs. In fact, we expected NEP approximately equals 1.5x10(exp -19)?W/Hz(sup 1/2) for meander beam TESs, but did not achieve this previously due to 1/f noise. Here, we detail improvements toward measuring the expected NEP and demonstrate NEP=(1.3+0.2)x10 (sup -19)W/Hz(exp 1/2) in our single-pixel test system and NEP=(1.6+/-0.3)x10(sup -19)W/Hz(sup 1/2) in our array test system.

Non-Maxwellian Analysis of the Transition-region Line Profiles Observed by the Interface Region Imaging Spectrograph

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

Dudík, Jaroslav; Dzifčáková, Elena; Polito, Vanessa

2017-06-10

We investigate the nature of the spectral line profiles for transition-region (TR) ions observed with the Interface Region Imaging Spectrograph (IRIS) . In this context, we analyzed an active-region observation performed by IRIS in its 1400 Å spectral window. The TR lines are found to exhibit significant wings in their spectral profiles, which can be well fitted with a non-Maxwellian κ distribution. The fit with a κ distribution can perform better than a double-Gaussian fit, especially for the strongest line, Si iv 1402.8 Å. Typical values of κ found are about 2, occurring in a majority of spatial pixels wheremore » the TR lines are symmetric, i.e., the fit can be performed. Furthermore, all five spectral lines studied (from Si iv, O iv, and S iv) appear to have the same full-width at half-maximum irrespective of whether the line is an allowed or an intercombination transition. A similar value of κ is obtained for the electron distribution by the fitting of the line intensities relative to Si iv 1402.8 Å, if photospheric abundances are assumed. The κ distributions, however, do not remove the presence of non-thermal broadening. Instead, they actually increase the non-thermal width. This is because, for κ distributions, TR ions are formed at lower temperatures. The large observed non-thermal width lowers the opacity of the Si iv line sufficiently enough for this line to become optically thin.« less

The Temperature and Distribution of Organic Molecules in the Inner Regions of T Tauri Disks

NASA Technical Reports Server (NTRS)

Mandell, Avi

2012-01-01

"High-resolution NIR spectroscopic observations of warm molecular gas emission from young circumstellar disks allow us to constrain the temperature and composition of material in the inner planet-forming region. By combining advanced data reduction algorithms with accurate modeling of the terrestrial atmospheric spectrum and a novel double-differencing data analysis technique, we have achieved very high-contrast measurements (S/N approx. 500-1000) of molecular emission at 3 microns. In disks around low-mass stars, we have achieved the first detections of emission from HCN and C2H2 at near-infrared wavelengths from several bright T Tauri stars using the CRIRES spectrograph on the Very Large Telescope and NIRSPEC spectrograph on the Keck Telescope. We spectrally resolve the line shape, showing that the emission has both a Keplerian and non-Keplerian component as observed previously for CO emission. We used a simplified single-temperature local thermal equilibrium (LTE) slab model with a Gaussian line profile to make line identifications and determine a best-fit temperature and initial abundance ratios, and we then compared these values with constraints derived from a detailed disk radiative transfer model assuming LTE excitation but utilizing a realistic temperature and density structure. Abundance ratios from both sets of models are consistent with each other and consistent with expected values from theoretical chemical models, and analysis of the line shapes suggests that the molecular emission originates from within a narrow region in the inner disk (R < 1 AU)."

Variations in the Processing of DNA Double-Strand Breaks Along 60-MeV Therapeutic Proton Beams

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

Chaudhary, Pankaj; Marshall, Thomas I.; Currell, Frederick J.

Purpose: To investigate the variations in induction and repair of DNA damage along the proton path, after a previous report on the increasing biological effectiveness along clinically modulated 60-MeV proton beams. Methods and Materials: Human skin fibroblast (AG01522) cells were irradiated along a monoenergetic and a modulated spread-out Bragg peak (SOBP) proton beam used for treating ocular melanoma at the Douglas Cyclotron, Clatterbridge Centre for Oncology, Wirral, Liverpool, United Kingdom. The DNA damage response was studied using the 53BP1 foci formation assay. The linear energy transfer (LET) dependence was studied by irradiating the cells at depths corresponding to entrance, proximal, middle, andmore » distal positions of SOBP and the entrance and peak position for the pristine beam. Results: A significant amount of persistent foci was observed at the distal end of the SOBP, suggesting complex residual DNA double-strand break damage induction corresponding to the highest LET values achievable by modulated proton beams. Unlike the directly irradiated, medium-sharing bystander cells did not show any significant increase in residual foci. Conclusions: The DNA damage response along the proton beam path was similar to the response of X rays, confirming the low-LET quality of the proton exposure. However, at the distal end of SOBP our data indicate an increased complexity of DNA lesions and slower repair kinetics. A lack of significant induction of 53BP1 foci in the bystander cells suggests a minor role of cell signaling for DNA damage under these conditions.« less

Construction of the Helsinki University of Technology (HUT) pulsed positron beam

NASA Astrophysics Data System (ADS)

Fallström, K.; Laine, T.

1999-08-01

We are constructing a pulsed positron beam facility for lifetime measurements in thin surface layers. Our beam system comprises a 22Na positron source and a tungsten foil moderator followed by a prebuncher and a chopper. A double-drift buncher will compress the beam into 120-ps pulses at the target. The end energy of the positron beam can be adjusted between 3 keV and 30 keV by changing the potential of the source end of the beam. The bunching electronics and most of the beam guiding magnets are also floating at the high voltage. The sample is at ground potential to facilitate variable temperature measurements. With a test source of 6 mCi 22Na we get a prebunched beam intensity of 4×10 3 positrons per second in 1.5-ns wide pulses (the bunching frequency is 33.33 MHz). We are currently testing the chopper and the following buncher stages and building the final accelerator/decelerator system.

A home-made system for IPCE measurement of standard and dye-sensitized solar cells.

PubMed

Palma, Giuseppina; Cozzarini, Luca; Capria, Ennio; Fraleoni-Morgera, Alessandro

2015-01-01

A home-made system for incident photon-to-electron conversion efficiency (IPCE) characterization, based on a double-beam UV-Vis spectrophotometer, has been set up. In addition to its low cost (compared to the commercially available apparatuses), the double-beam configuration gives the advantage to measure, autonomously and with no need for supplementary equipment, the lamp power in real time, compensating possible variations of the spectral emission intensity and quality, thus reducing measurement times. To manage the optical and electronic components of the system, a custom software has been developed. Validations carried out on a common silicon-based photodiode and on a dye-sensitized solar cell confirm the possibility to adopt this system for determining the IPCE of solar cells, including dye-sensitized ones.

An analytical study of double bend achromat lattice.

PubMed

Fakhri, Ali Akbar; Kant, Pradeep; Singh, Gurnam; Ghodke, A D

2015-03-01

In a double bend achromat, Chasman-Green (CG) lattice represents the basic structure for low emittance synchrotron radiation sources. In the basic structure of CG lattice single focussing quadrupole (QF) magnet is used to form an achromat. In this paper, this CG lattice is discussed and an analytical relation is presented, showing the limitation of basic CG lattice to provide the theoretical minimum beam emittance in achromatic condition. To satisfy theoretical minimum beam emittance parameters, achromat having two, three, and four quadrupole structures is presented. In this structure, different arrangements of QF and defocusing quadruple (QD) are used. An analytical approach assuming quadrupoles as thin lenses has been followed for studying these structures. A study of Indus-2 lattice in which QF-QD-QF configuration in the achromat part has been adopted is also presented.

Beam-Plasma Interaction Experiments on the Princeton Advanced Test Stand

NASA Astrophysics Data System (ADS)

Stepanov, A.; Gilson, E. P.; Grisham, L.; Kaganovich, I. D.; Davidson, R. C.

2011-10-01

The Princeton Advanced Test Stand (PATS) is a compact experimental facility for studying the fundamental physics of intense beam-plasma interactions relevant to the Neutralized Drift Compression Experiment - II (NDCX-II). The PATS facility consists of a 100 keV ion beam source mounted on a six-foot-long vacuum chamber with numerous ports for diagnostic access. A 100 keV Ar+ beam is launched into a volumetric plasma, which is produced by a ferroelectric plasma source (FEPS). Beam diagnostics upstream and downstream of the FEPS allow for detailed studies of the effects that the plasma has on the beam. This setup is designed for studying the dependence of charge and current neutralization and beam emittance growth on the beam and plasma parameters. This work reports initial measurements of beam quality produced by the extraction electrodes that were recently installed on the PATS device. The transverse beam phase space is measured with double-slit emittance scanners, and the experimental results are compared to WARP simulations of the extraction system. This research is supported by the U.S. Department of Energy.

Plasma-based beam combiner for very high fluence and energy

DOE PAGES

Kirkwood, R. K.; Turnbull, D. P.; Chapman, T.; ...

2017-10-02

Extreme optical fluences, much beyond the damage threshold of conventional optics, are of interest for a range of high-energy-density physics applications. Nonlinear interactions of multiple beams in plasmas have the potential to produce optics that operate at much higher intensity and fluence than is possible in solids. In inertial confinement fusion experiments indirectly driven with lasers, many beams overlap in the plasma inside a hohlraum, and cross-beam energy transfer by Brillouin scattering has been employed to redistribute energy between laser beams within the target. Here in this paper, we show that in a hot, under-dense plasma the energy of manymore » input beams can be combined into a single well-collimated beam. The emerging beam has an energy of 4 kJ (over 1 ns) that is more than triple that of any incident beam, and a fluence that is more than double. Because the optic produced is plasma, and is diffractive, it is inherently capable of generating higher fluences in a single beam than solid-state refractive or reflective optics.« less

Recent results on reactions with radioactive beams at RIBRAS (Radioactive Ion Beams in Brazil)

NASA Astrophysics Data System (ADS)

Lépine-Szily, A.; Lichtenthäler, R.; Guimarães, V.; Arazi, A.; Barioni, A.; Benjamim, E. A.; de Faria, P. N.; Descouvemont, P.; Gasques, L. R.; E; Leistenschneider; Mendes, D. R., Jr.; Morais, M. C.; Morcelle, V.; Moro, A. M.; Pampa Condori, R.; Pires, K. C. C.; Rodriguez-Gallardo, M.; Scarduelli, V.; Shorto, J. M. B.; Zamora, J. C.

2015-04-01

We present a quick description of RIBRAS (Radioactive Ion beams in Brazil), which is a superconducting double solenoid system, installed at the Pelletron Laboratory of the University of São Paulo and extends the capabilities of the original Pelletron Tandem Accelerator of 8MV terminal voltage (8UD) by producing secondary beams of unstable nuclei. The experimental program of the RIBRAS covers the study of elastic and inelastic scattering with the objective to study the interaction potential and the reaction mechanisms between weakly bound (RIB) and halo (6He and 8B) projectiles on light, medium and heavy mass targets. With highly purified beams, the study of resonant elastic scattering and resonant transfer reactions, using inverse kinematics and thick targets, have also been included in our recent experimental program.

4MOST fiber feed preliminary design: prototype testing and performance

NASA Astrophysics Data System (ADS)

Haynes, Dionne M.; Kelz, Andreas; Barden, Samuel C.; Bauer, Svend-Marian; Ehrlich, Katjana; Haynes, Roger; Jahn, Thomas; Saviauk, Allar; de Jong, Roelof S.

2016-08-01

The 4MOST instrument is a multi-object-spectrograph for the ESO-VISTA telescope. The 4MOST fiber feed subsystem is composed of a fiber positioner (AESOP) holding 2436 science fibers based on the Echidna tilting spine concept, and the fiber cable, which feeds two low-resolution spectrographs (1624 fibers) and one high-resolution spectrograph (812 fibers). In order to optimize the fiber feed subsystem design and provide essential information required for the spectrograph design, prototyping and testing has been undertaken. In this paper we give an overview of the current fiber feed subsystem design and present the preliminary FRD, scrambling, throughput and system performance impact results for: maximum and minimum spine tilt, fiber connectors, cable de-rotator simulator for fiber cable lifetime tests.

A CAUTIONARY TALE: MARVELS BROWN DWARF CANDIDATE REVEALS ITSELF TO BE A VERY LONG PERIOD, HIGHLY ECCENTRIC SPECTROSCOPIC STELLAR BINARY

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

Mack, Claude E. III; Stassun, Keivan G.; De Lee, Nathan

2013-05-15

We report the discovery of a highly eccentric, double-lined spectroscopic binary star system (TYC 3010-1494-1), comprising two solar-type stars that we had initially identified as a single star with a brown dwarf companion. At the moderate resolving power of the MARVELS spectrograph and the spectrographs used for subsequent radial-velocity (RV) measurements (R {approx}< 30, 000), this particular stellar binary mimics a single-lined binary with an RV signal that would be induced by a brown dwarf companion (Msin i {approx} 50 M{sub Jup}) to a solar-type primary. At least three properties of this system allow it to masquerade as a singlemore » star with a very-low-mass companion: its large eccentricity (e {approx} 0.8), its relatively long period (P {approx} 238 days), and the approximately perpendicular orientation of the semi-major axis with respect to the line of sight ({omega} {approx} 189 Degree-Sign ). As a result of these properties, for {approx}95% of the orbit the two sets of stellar spectral lines are completely blended, and the RV measurements based on centroiding on the apparently single-lined spectrum is very well fit by an orbit solution indicative of a brown dwarf companion on a more circular orbit (e {approx} 0.3). Only during the {approx}5% of the orbit near periastron passage does the true, double-lined nature and large RV amplitude of {approx}15 km s{sup -1} reveal itself. The discovery of this binary system is an important lesson for RV surveys searching for substellar companions; at a given resolution and observing cadence, a survey will be susceptible to these kinds of astrophysical false positives for a range of orbital parameters. Finally, for surveys like MARVELS that lack the resolution for a useful line bisector analysis, it is imperative to monitor the peak of the cross-correlation function for suspicious changes in width or shape, so that such false positives can be flagged during the candidate vetting process.« less

Impact of the phase-mismatch in the SHG crystal and consequential self-action of the fundamental wave by cascaded second-order effects on the THG efficiency of a Q-switched 1342 nm Nd:YVO₄ laser.

PubMed

Koch, Peter; Bartschke, Juergen; L'huillier, Johannes A

2015-05-18

We report on the influence of self-focusing and self-defocusing in the phase-mismatched frequency doubling crystal on the third harmonic generation (THG) efficiency in a two crystal frequency tripling scheme. By detuning the temperature of the doubling crystal, the impact of a phase-mismatch in second harmonic generation (SHG) on the subsequent sum frequency mixing process was investigated. It was found that adjusting the temperature not only affected the power ratio of the second harmonic to the fundamental but also the beam diameter of the fundamental beam in the THG crystal, which was caused by self-focusing and self-defocusing of the fundamental beam, respectively. This self-action was induced by a cascaded χ(2) : χ(2) process in the phase-mismatched SHG crystal. Self-defocusing was observable for positive detuning and self-focusing for negative detuning of the phase-matching temperature. Hence, the THG efficiency was not symmetric with respect to the point of optimum phase-matching. Optimum THG was obtained for positive detuning and the resulting self-defocusing in combination with the focusing lens in front of the THG stage was also beneficial for the beam quality of the third harmonic.

A New Light Curve and Analysis of the Long Period Eclipsing Binary BF Draconis

NASA Astrophysics Data System (ADS)

Wolf, G. W.; Craig, L. E.; Caffey, J. F.

1999-01-01

The star BF Draconis was found to be an eclipsing binary by Strohmeier, Knigge and Ott (1962) and originally thought to be an Algol-type system with a period of 5.6 days. A spectrographic study by Imbert (1985) showed that the period was actually double this value and that the system consisted of two well-separated, almost-equal F-type stars in elliptical orbit. Diethelm, Wolf and Agerer (1993) later published a preliminary light curve of this system showing minima of unequal depth and width with a displaced secondary, confirming the elliptical orbit but disagreeing with Imbert on the specific orbital parameters. As a part of our long-term program of obtaining improved light curves of double-lined spectroscopic and eclipsing binaries, we have observed BF Draconis for the past four years using the 0.4 meter telescope at the Baker Observatory of Southwest Missouri State University. Complete light curves in the Cousins BVRI passbands have been obtained with our Photometrics CCD system, and a new model and orbital parameters for the binary have been determined using the Wilson-Devinney program. This research has been supported by NSF Grants AST-9315061 and AST-9605822 and NASA Grant NGT5-40060.

Compliant Robot Wrist

NASA Technical Reports Server (NTRS)

Voellmer, George

1992-01-01

Compliant element for robot wrist accepts small displacements in one direction only (to first approximation). Three such elements combined to obtain translational compliance along three orthogonal directions, without rotational compliance along any of them. Element is double-blade flexure joint in which two sheets of spring steel attached between opposing blocks, forming rectangle. Blocks moved parallel to each other in one direction only. Sheets act as double cantilever beams deforming in S-shape, keeping blocks parallel.

Measurement of the equilibrium charge state distributions of Ni, Co, and Cu beams in Mo at 2 MeV/u: Review and evaluation of the relevant semi-empirical models

NASA Astrophysics Data System (ADS)

Gastis, P.; Perdikakis, G.; Robertson, D.; Almus, R.; Anderson, T.; Bauder, W.; Collon, P.; Lu, W.; Ostdiek, K.; Skulski, M.

2016-04-01

Equilibrium charge state distributions of stable 60Ni, 59Co, and 63Cu beams passing through a 1 μm thick Mo foil were measured at beam energies of 1.84 MeV/u, 2.09 MeV/u, and 2.11 MeV/u respectively. A 1-D position sensitive Parallel Grid Avalanche Counter detector (PGAC) was used at the exit of a spectrograph magnet, enabling us to measure the intensity of several charge states simultaneously. The number of charge states measured for each beam constituted more than 99% of the total equilibrium charge state distribution for that element. Currently, little experimental data exists for equilibrium charge state distributions for heavy ions with 19 ≲Zp,Zt ≲ 54 (Zp and Zt, are the projectile's and target's atomic numbers respectively). Hence the success of the semi-empirical models in predicting typical characteristics of equilibrium CSDs (mean charge states and distribution widths), has not been thoroughly tested at the energy region of interest. A number of semi-empirical models from the literature were evaluated in this study, regarding their ability to reproduce the characteristics of the measured charge state distributions. The evaluated models were selected from the literature based on whether they are suitable for the given range of atomic numbers and on their frequent use by the nuclear physics community. Finally, an attempt was made to combine model predictions for the mean charge state, the distribution width and the distribution shape, to come up with a more reliable model. We discuss this new ;combinatorial; prescription and compare its results with our experimental data and with calculations using the other semi-empirical models studied in this work.

THE MULTI-OBJECT, FIBER-FED SPECTROGRAPHS FOR THE SLOAN DIGITAL SKY SURVEY AND THE BARYON OSCILLATION SPECTROSCOPIC SURVEY

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

Smee, Stephen A.; Gunn, James E.; Uomoto, Alan

2013-07-12

We present the design and performance of the multi-object fiber spectrographs for the Sloan Digital Sky Survey (SDSS) and their upgrade for the Baryon Oscillation Spectroscopic Survey (BOSS). Originally commissioned in Fall 1999 on the 2.5-m aperture Sloan Telescope at Apache Point Observatory, the spectrographs produced more than 1.5 million spectra for the SDSS and SDSS-II surveys, enabling a wide variety of Galactic and extra-galactic science including the first observation of baryon acoustic oscillations in 2005. The spectrographs were upgraded in 2009 and are currently in use for BOSS, the flagship survey of the third-generation SDSS-III project. BOSS will measuremore » redshifts of 1.35 million massive galaxies to redshift 0.7 and Lyman-alpha absorption of 160,000 high redshift quasars over 10,000 square degrees of sky, making percent level measurements of the absolute cosmic distance scale of the Universe and placing tight constraints on the equation of state of dark energy. The twin multi-object fiber spectrographs utilize a simple optical layout with reflective collimators, gratings, all-refractive cameras, and state-of-the-art CCD detectors to produce hundreds of spectra simultaneously in two channels over a bandpass covering the near ultraviolet to the near infrared, with a resolving power R = \\lambda/FWHM ~ 2000. Building on proven heritage, the spectrographs were upgraded for BOSS with volume-phase holographic gratings and modern CCD detectors, improving the peak throughput by nearly a factor of two, extending the bandpass to cover 360 < \\lambda < 1000 nm, and increasing the number of fibers from 640 to 1000 per exposure. In this paper we describe the original SDSS spectrograph design and the upgrades implemented for BOSS, and document the predicted and measured performances.« less

Mini-Spec: A Compact, Fiber-Coupled, VPH Grating Spectrograph for Small Observatories

NASA Astrophysics Data System (ADS)

Nations, H. L.; Haynes, P.; Brewer, P.

2003-05-01

We report on the development and testing of what we believe to be the first VPH grating based spectrograph developed primarily for use at telescopes of modest aperture. To date, the most common instrument suite for such observatories is typically that of a CCD camera with attached filter wheel. While there is no doubt that a wide range of interesting and good science has been done with such instrumentation, the addition of a robust and easy to operate spectrograph would greatly increase the utility of such installations. While some commercial spectrographs exist for use on small telescopes, the authors have found them to be, with few exceptions, either inefficient, difficult for inexperienced students or amateurs to use, or not remotely operable. Correcting these deficiencies is thus the primary motivation for Mini-Spec. The design of Mini-Spec has been influenced by previous work the authors have done on a full-sized fiber-coupled spectrograph (Nations and Pierce, 2002). Mini-Spec uses some of those original design features, only reduced drastically in size. This size reduction (the spectrograph fits within a 7 inch cube), along with a much more careful choice of some critical components, has resulted in a dramatic reduction in cost. The spectrograph uses a highly efficient 1200 l/mm, 40 mm diameter vph grating on loan from Richard Rallison. Focus, central wavelength selection, and comparison lamps are all controlled via an RS-232 link and a custom Visual Basic GUI. Sample spectra of stellar and non-stellar targets will be presented along with a discussion of research projects admirably suited for this instrument. Funding for equipment has been provided by a NASA EPSCoR grant to PI Ron Canterna. HLN has been partially funded by a Wyoming Space Grant Faculty Fellowship.

rf traveling-wave electron gun for photoinjectors

NASA Astrophysics Data System (ADS)

Schaer, Mattia; Citterio, Alessandro; Craievich, Paolo; Reiche, Sven; Stingelin, Lukas; Zennaro, Riccardo

2016-07-01

The design of a photoinjector, in particular that of the electron source, is of central importance for free electron laser (FEL) machines where a high beam brightness is required. In comparison to standard designs, an rf traveling-wave photocathode gun can provide a more rigid beam with a higher brightness and a shorter pulse. This is illustrated by applying a specific optimization procedure to the SwissFEL photoinjector, for which a brightness improvement up to a factor 3 could be achieved together with a double gun output energy compared to the reference setup foreseeing a state-of-the-art S-band rf standing-wave gun. The higher brightness is mainly given by a (at least) double peak current at the exit of the gun which brings benefits for both the beam dynamics in the linac and the efficiency of the FEL process. The gun design foresees an innovative coaxial rf coupling at both ends of the structure which allows a solenoid with integrated bucking coil to be placed around the cathode in order to provide the necessary focusing right after emission.

Accurate characterization of wafer bond toughness with the double cantilever specimen

NASA Astrophysics Data System (ADS)

Turner, Kevin T.; Spearing, S. Mark

2008-01-01

The displacement loaded double cantilever test, also referred to as the "Maszara test" and the "crack opening method" by the wafer bonding community, is a common technique used to evaluate the interface toughness or surface energy of direct wafer bonds. While the specimen is widely used, there has been a persistent question as to the accuracy of the method since the actual specimen geometry differs from the ideal beam geometry assumed in the expression used for data reduction. The effect of conducting the test on whole wafer pairs, in which the arms of cantilevers are wide plates rather than slender beams, is examined in this work using finite element analysis. A model is developed to predict the equilibrium shape of the crack front and to develop a corrected expression for calculating interface toughness from crack length measurements obtained in tests conducted on whole wafer pairs. The finite element model, which is validated through comparison to experiments, demonstrates that using the traditional beam theory-based expressions for data reduction can lead to errors of up to 25%.

Single and double spin asymmetries for pion electro-production from the deuteron in the resonance region

NASA Astrophysics Data System (ADS)

Careccia, Sharon L.

The single and double spin asymmetries At and Aet have been measured in pi- electro-production off the deuteron using a longitudinally polarized electron beam and a polarized ND3 target. The electron beam was polarized using a strained GaAs cathode and the target was polarized using Dynamic Nuclear Polarization. The data were collected at beam energies of 1.6, 1.7, 2.5 and 4.2 GeV in Hall B at Jefferson Lab in the spring of 2001. The final state particles were detected in the CEBAF Large Acceptance Spectrometer (CLAS). The d(e,e'pi-p)p exclusive channel was identified using the missing mass technique and the asymmetries were extracted as a function of the momentum transfer Q2, invariant mass W, and center of mass pion angles cos(theta*) and φ*. The results are generally in agreement with the phenomenological model MAID at low energies, but there are discrepancies in the 2nd and 3rd resonance regions, as well as at forward angles.

A Post-AGB Star in the Small Magellanic Cloud Observed with the Spitzer Infrared Spectrograph

DTIC Science & Technology

2006-10-23

spectral features, MSX SMC 029, in the Small Magellanic Cloud (SMC) usimg the low-resolution modules of the Infrared Spectrograph on the Spitzer Space ...029, in the Small Magellanic Cloud (SMC) using the low-resolution modules of the Infrared Spectrograph on the Spitzer Space Telescope. A cool dust... outer atmosphere expands and pulsates, pushing gas away from the star where it can cool and condense into dust grains. The resulting circumstellar dust

Crystal face temperature determination means

DOEpatents

Nason, D.O.; Burger, A.

1994-11-22

An optically transparent furnace having a detection apparatus with a pedestal enclosed in an evacuated ampule for growing a crystal thereon is disclosed. Temperature differential is provided by a source heater, a base heater and a cold finger such that material migrates from a polycrystalline source material to grow the crystal. A quartz halogen lamp projects a collimated beam onto the crystal and a reflected beam is analyzed by a double monochromator and photomultiplier detection spectrometer and the detected peak position in the reflected energy spectrum of the reflected beam is interpreted to determine surface temperature of the crystal. 3 figs.

Double lens device for tunable harmonic generation of laser beams in KBBF/RBBF crystals or other non-linear optic materials

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

Kaminski, Adam

A method and apparatus to generate harmonically related laser wavelengths includes a pair of lenses at opposing faces of a non-linear optical material. The lenses are configured to promote incoming and outgoing beams to be normal to each outer lens surface over a range of acceptance angles of the incoming laser beam. This reduces reflection loss for higher efficiency operation. Additionally, the lenses allow a wider range of wavelengths for lasers for more universal application. Examples of the lenses include plano-cylindrical and plano-spherical form factors.

Non-deterministic quantum CNOT gate with double encoding

NASA Astrophysics Data System (ADS)

Gueddana, Amor; Attia, Moez; Chatta, Rihab

2013-09-01

We define an Asymmetric Partially Polarizing Beam Splitter (APPBS) to be a linear optical component having different reflectivity (transmittance) coefficients, on the upper and the lower arms, for horizontally and vertically Polarized incident photons. Our CNOT model is composed by two APPBSs, one Half Wave Plate (HWP), two Polarizing Beam Splitters (PBSs), a Beam Splitter (BS) and a -phase rotator for specific wavelength. Control qubit operates with dual rail encoding while target qubit is based on polarization encoding. To perform CNOT operation in 4/27 of the cases, input and target incoming photons are injected with different wavelengths.

Thai National Telescope beam simulator testbed development status

NASA Astrophysics Data System (ADS)

Buisset, Christophe; Prasit, Apirat; Lépine, Thierry; Poshyachinda, Saran; Leckngam, A.

2016-07-01

The Thai National Telescope (TNT) is a Ritchey-Chretien Telescope with a clear aperture ΦM1 = 2.3 m, a focal ratio f/10 and a central obstruction Obsc = 0.3. The TNT is the main instrument of the Thai National Observatory (TNO) which is located near the summit of the Doi Inthanon, situated in the Chiang Mai Province of Thailand at altitude 2,457 meters. The median seeing on this site is approximately 0.9" and is remarkably stable on most nights, rarely exceeding 2". We decided to develop an optical setup to simulate in laboratory conditions the geometry of the TNT output beam. This, in order to carefully prepare and to improve the efficiency of the test to be performed in real conditions at the TNT focal plane level. We specified the setup to be representative of the TNT optical design, beam aperture, central obscuration, geometry of the spider, wavefront quality and PSF size under various seeing conditions. This setup comprises 2 identical Cassegrain telescopes mounted on dedicated supports with 5 degree-of-Freedom. The first application of this setup will be the preparation of the TNT optical alignment. The second application of this setup will be the development and the test of the future instruments for the TNT such as a focal reducer or a spectrograph. In this paper, we discuss the setup specifications we describe the setup optical and mechanical design and we present the performance.

Manufacturing, integration, and test results of the MATISSE cold optics bench

NASA Astrophysics Data System (ADS)

Bettonvil, Felix C. M.; Kroes, G.; Agoćs, T.; van Duin, A.; Elswijk, E.; de Haan, M.; ter Horst, R.; Kragt, J.; Kuindersma, J.; Navarro, R.; Roelfsema, R.; Schuil, M.; Tromp, T.; Venema, L.; van Kessel, F.; Jaskó, A.

2014-07-01

MATISSE is the second-generation mid-infrared interferometric spectrograph and imager for ESO's Very Large Telescope Interferometer (VLTI). NOVA-ASTRON is responsible for the Cold Optics Bench (COB), representing the last part of the optics train where the four beams are re-arranged, spectrally dispersed and combined. The COB consist of two sister units, one for the LM-band, one for the N-band, which were successively completed at NOVA-ASTRON in autumn 2013 and spring 2014. The LM-band COB is under cryogenic test in its cryostat at MPIA/Heidelberg; the N-band COB finished cryogenic tests and has been installed at OCA/Nice for integration together with the Warm Optics. This paper focuses on the manufacturing, integration and test results of the COBs, and gives an overview of the current status.

A large area diamond-based beam tagging hodoscope for ion therapy monitoring

NASA Astrophysics Data System (ADS)

Gallin-Martel, M.-L.; Abbassi, L.; Bes, A.; Bosson, G.; Collot, J.; Crozes, T.; Curtoni, S.; Dauvergne, D.; De Nolf, W.; Fontana, M.; Gallin-Martel, L.; Hostachy, J.-Y.; Krimmer, J.; Lacoste, A.; Marcatili, S.; Morse, J.; Motte, J.-F.; Muraz, J.-F.; Rarbi, F. E.; Rossetto, O.; Salomé, M.; Testa, É.; Vuiart, R.; Yamouni, M.

2018-01-01

The MoniDiam project is part of the French national collaboration CLaRyS (Contrôle en Ligne de l'hAdronthérapie par RaYonnements Secondaires) for on-line monitoring of hadron therapy. It relies on the imaging of nuclear reaction products that is related to the ion range. The goal here is to provide large area beam detectors with a high detection efficiency for carbon or proton beams giving time and position measurement at 100 MHz count rates (beam tagging hodoscope). High radiation hardness and intrinsic electronic properties make diamonds reliable and very fast detectors with a good signal to noise ratio. Commercial Chemical Vapor Deposited (CVD) poly-crystalline, heteroepitaxial and monocrystalline diamonds were studied. Their applicability as a particle detector was investigated using α and β radioactive sources, 95 MeV/u carbon ion beams at GANIL and 8.5 keV X-ray photon bunches from ESRF. This facility offers the unique capability of providing a focused ( 1 μm) beam in bunches of 100 ps duration, with an almost uniform energy deposition in the irradiated detector volume, therefore mimicking the interaction of single ions. A signal rise time resolution ranging from 20 to 90 ps rms and an energy resolution of 7 to 9% were measured using diamonds with aluminum disk shaped surface metallization. This enabled us to conclude that polycrystalline CVD diamond detectors are good candidates for our beam tagging hodoscope development. Recently, double-side stripped metallized diamonds were tested using the XBIC (X Rays Beam Induced Current) set-up of the ID21 beamline at ESRF which permits us to evaluate the capability of diamond to be used as position sensitive detector. The final detector will consist in a mosaic arrangement of double-side stripped diamond sensors read out by a dedicated fast-integrated electronics of several hundreds of channels.

Effect of ion beam on the characteristics of ion acoustic Gardner solitons and double layers in a multicomponent superthermal plasma

NASA Astrophysics Data System (ADS)

Kaur, Nimardeep; Singh, Kuldeep; Saini, N. S.

2017-09-01

The nonlinear propagation of ion acoustic solitary waves (IASWs) is investigated in an unmagnetized plasma composed of a positive warm ion fluid, two temperature electrons obeying kappa type distribution and penetrated by a positive ion beam. The reductive perturbation method is used to derive the nonlinear equations, namely, Korteweg-de Vries (KdV), modified KdV (mKdV), and Gardner equations. The characteristic features of both compressive and rarefactive nonlinear excitations from the solution of these equations are studied and compared in the context with the observation of the He+ beam in the polar cap region near solar maximum by the Dynamics Explorer 1 satellite. It is observed that the superthermality and density of cold electrons, number density, and temperature of the positive ion beam crucially modify the basic properties of compressive and rarefactive IASWs in the KdV and mKdV regimes. It is further analyzed that the amplitude and width of Gardner solitons are appreciably affected by different plasma parameters. The characteristics of double layers are also studied in detail below the critical density of cold electrons. The theoretical results may be useful for the observation of nonlinear excitations in laboratory and ion beam driven plasmas in the polar cap region near solar maximum and polar ionosphere as well in Saturn's magnetosphere, solar wind, pulsar magnetosphere, etc., where the population of two temperature superthermal electrons is present.

Single and double capture in F9+ + Ar collisions: Comparison of total capture with capture occurring from the Ar K shell

NASA Astrophysics Data System (ADS)

La Mantia, David; Kumara, Nuwan; Kayani, Asghar; Simon, Anna; Tanis, John

2016-05-01

Total cross sections for single and double capture, as well as the corresponding cross sections for capture resulting in the emission of an Ar K x ray, were measured. This work was performed at Western Michigan University with the use of the tandem Van de Graaff accelerator. A 45 MeV beam of fully-stripped fluorine ions was collided with argon gas molecules in a differentially pumped cell. Surface barrier detectors were used to observe the charge changed projectiles and a Si(Li) x-ray detector, placed at 90o to the incident beam, were used to measure coincidences with Ar K x rays. The total capture cross sections are compared to previously measured cross sections in the existing literature. The coincidence cross sections, considerably smaller than the total cross sections, are found to be nearly equal for single and double capture in contrast to the total cross sections, which vary by about an order of magnitude. Possible reasons for this behavior are discussed. Supported in part by the NSF.

Experimental Study of an Advanced Concept of Moderate-resolution Holographic Spectrographs

NASA Astrophysics Data System (ADS)

Muslimov, Eduard; Valyavin, Gennady; Fabrika, Sergei; Musaev, Faig; Galazutdinov, Gazinur; Pavlycheva, Nadezhda; Emelianov, Eduard

2018-07-01

We present the results of an experimental study of an advanced moderate-resolution spectrograph based on a cascade of narrow-band holographic gratings. The main goal of the project is to achieve a moderately high spectral resolution with R up to 5000 simultaneously in the 4300–6800 Å visible spectral range on a single standard CCD, together with an increased throughput. The experimental study consisted of (1) resolution and image quality tests performed using the solar spectrum, and (2) a total throughput test performed for a number of wavelengths using a calibrated lab monochromator. The measured spectral resolving power reaches values over R > 4000 while the experimental throughput is as high as 55%, which agrees well with the modeling results. Comparing the obtained characteristics of the spectrograph under consideration with the best existing spectrographs, we conclude that the used concept can be considered as a very competitive and cheap alternative to the existing spectrographs of the given class. We propose several astrophysical applications for the instrument and discuss the prospect of creating its full-scale version.

Conceptual design for an AIUC multi-purpose spectrograph camera using DMD technology

NASA Astrophysics Data System (ADS)

Rukdee, S.; Bauer, F.; Drass, H.; Vanzi, L.; Jordan, A.; Barrientos, F.

2017-02-01

Current and upcoming massive astronomical surveys are expected to discover a torrent of objects, which need groundbased follow-up observations to characterize their nature. For transient objects in particular, rapid early and efficient spectroscopic identification is needed. In particular, a small-field Integral Field Unit (IFU) would mitigate traditional slit losses and acquisition time. To this end, we present the design of a Digital Micromirror Device (DMD) multi-purpose spectrograph camera capable of running in several modes: traditional longslit, small-field patrol IFU, multi-object and full-field IFU mode via Hadamard spectra reconstruction. AIUC Optical multi-purpose CAMera (AIUCOCAM) is a low-resolution spectrograph camera of R 1,600 covering the spectral range of 0.45-0.85 μm. We employ a VPH grating as a disperser, which is removable to allow an imaging mode. This spectrograph is envisioned for use on a 1-2 m class telescope in Chile to take advantage of good site conditions. We present design decisions and challenges for a costeffective robotized spectrograph. The resulting instrument is remarkably versatile, capable of addressing a wide range of scientific topics.

Generation of tunable chain of three-dimensional optical bottle beams via focused multi-ring hollow Gaussian beam.

PubMed

Philip, Geo M; Viswanathan, Nirmal K

2010-11-01

We report here the generation of a chain of three-dimensional (3-D) optical bottle beams by focusing a π-phase shifted multi-ring hollow Gaussian beam (HGB) using a lens with spherical aberration. The rings of the HGB of suitable radial (k(r)) and axial (k(z)) wave vectors are generated using a double-negative axicon chemically etched in the optical fiber tips. Moving the lens position with respect to the fiber tip results in variation of the semi-angle of the cones of wave vectors of the HGBs and their diameter, using which we demonstrate tunability in the size and the periodicity of the 3-D optical bottle beams over a wide range, from micrometers to millimeters. The propagation characteristics of the beams resulting from focusing of single- and multi-ring HGBs and resulting in a quasi-non-diffracting beam and a chain of 3-D optical bottle beams, respectively, are simulated using only the input beam parameters and are found to agree well with experimental results.

Double dipole antenna SIS receivers at 100 and 400 GHz

NASA Technical Reports Server (NTRS)

Skalare, A.; Vandestadt, H.; Degraauw, T.; Panhuyzen, R. A.; Dierichs, M. M. T. M.

1992-01-01

Antenna patterns were measured between 95 and 120 GHz for a double dipole antenna / ellipsoidal lens combination. The structure produces a non-astigmatic beam with low side lobe levels over that whole band. A heterodyne SIS receiver based on this concept gave a best noise temperature of 145 K DSB at 98 GHz. Measurements were also made with a 400 GHz heterodyne SIS receiver, using a double dipole antenna in conjunction with a hyperhemispherical lens. The best noise temperature was 220 K DSB at 402 GHz. On-chip stubs were used to tune out the SIS junction capacitance.

Curved VPH gratings for novel spectrographs

NASA Astrophysics Data System (ADS)

Clemens, J. Christopher; O'Donoghue, Darragh; Dunlap, Bart H.

2014-07-01

The introduction of volume phase holographic (VPH) gratings into astronomy over a decade ago opened new possibilities for instrument designers. In this paper we describe an extension of VPH grating technology that will have applications in astronomy and beyond: curved VPH gratings. These devices can disperse light while simultaneously correcting aberrations. We have designed and manufactured two different kinds of convex VPH grating prototypes for use in off-axis reflecting spectrographs. One type functions in transmission and the other in reflection, enabling Offnerstyle spectrographs with the high-efficiency and low-cost advantages of VPH gratings. We will discuss the design process and the tools required for modelling these gratings along with the recording layout and process steps required to fabricate them. We will present performance data for the first convex VPH grating produced for an astronomical spectrograph.

Web-based multi-channel analyzer

DOEpatents

Gritzo, Russ E.

2003-12-23

The present invention provides an improved multi-channel analyzer designed to conveniently gather, process, and distribute spectrographic pulse data. The multi-channel analyzer may operate on a computer system having memory, a processor, and the capability to connect to a network and to receive digitized spectrographic pulses. The multi-channel analyzer may have a software module integrated with a general-purpose operating system that may receive digitized spectrographic pulses for at least 10,000 pulses per second. The multi-channel analyzer may further have a user-level software module that may receive user-specified controls dictating the operation of the multi-channel analyzer, making the multi-channel analyzer customizable by the end-user. The user-level software may further categorize and conveniently distribute spectrographic pulse data employing non-proprietary, standard communication protocols and formats.

Development of the MAMA Detectors for the Hubble Space Telescope Imaging Spectrograph

NASA Technical Reports Server (NTRS)

Timothy, J. Gethyn

1997-01-01

The development of the Multi-Anode Microchannel Array (MAMA) detector systems started in the early 1970's in order to produce multi-element detector arrays for use in spectrographs for solar studies from the Skylab-B mission. Development of the MAMA detectors for spectrographs on the Hubble Space Telescope (HST) began in the late 1970's, and reached its culmination with the successful installation of the Space Telescope Imaging Spectrograph (STIS) on the second HST servicing mission (STS-82 launched 11 February 1997). Under NASA Contract NAS5-29389 from December 1986 through June 1994 we supported the development of the MAMA detectors for STIS, including complementary sounding rocket and ground-based research programs. This final report describes the results of the MAMA detector development program for STIS.

Generation of high-power, tunable terahertz radiation from laser interaction with a relativistic electron beam

DOE PAGES

Zhang, Zhen; Yan, Lixin; Du, Yingchao; ...

2017-05-01

We propose a method based on the slice energy spread modulation to generate strong subpicosecond density bunching in high-intensity relativistic electron beams. A laser pulse with periodic intensity envelope is used to modulate the slice energy spread of the electron beam, which can then be converted into density modulation after a dispersive section. It is found that the double-horn slice energy distribution of the electron beam induced by the laser modulation is very effective to increase the density bunching. Since the modulation is performed on a relativistic electron beam, the process does not suffer from strong space charge force ormore » coupling between phase spaces, so that it is straightforward to preserve the beam quality for terahertz (THz) radiation and other applications. We show in both theory and simulations that the tunable radiation from the beam can cover the frequency range of 1 - 10 THz with high power and narrow-band spectra.« less

Dynamic analysis of beam-cable coupled systems using Chebyshev spectral element method

NASA Astrophysics Data System (ADS)

Huang, Yi-Xin; Tian, Hao; Zhao, Yang

2017-10-01

The dynamic characteristics of a beam-cable coupled system are investigated using an improved Chebyshev spectral element method in order to observe the effects of adding cables on the beam. The system is modeled as a double Timoshenko beam system interconnected by discrete springs. Utilizing Chebyshev series expansion and meshing the system according to the locations of its connections, numerical results of the natural frequencies and mode shapes are obtained using only a few elements, and the results are validated by comparing them with the results of a finite-element method. Then the effects of the cable parameters and layout of connections on the natural frequencies and mode shapes of a fixed-pinned beam are studied. The results show that the modes of a beam-cable coupled system can be classified into two types, beam mode and cable mode, according to the dominant deformation. To avoid undesirable vibrations of the cable, its parameters should be controlled in a reasonable range, or the layout of the connections should be optimized.

MO-G-BRF-07: Optical Characterization of Novel Terbium-Doped Nanophosphors Excited by Clinical Electron and Photon Beams for Potential Use in Molecular Imaging Or Photodynamic Therapy

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

Darafsheh, A; Paik, T; Tenuto, M

Purpose: Optical properties of terbium (Tb3+)-doped gadolinium trifluoride (GdF3) nanoplates irradiated by electron and photon beams were investigated for their potential as optical probes. The contribution of induced Cerenkov radiation in exciting the nanophosphors was investigated as well. Methods: The emission spectra of Terbium-doped GdF3 dispersed in hexane, embedded in tissue mimicking phantoms were collected by an optical fiber connected to a CCD-coupled spectrograph, while the samples were irradiated by a medical linear accelerator with electron beams of energies 6, 9, 12, 16, and 20 MeV or X-ray beams of energies of 6, and 15 MV. The contribution of inducedmore » Cerenkov radiation in exciting the nanophosphores was investigated in a dedicated experimental apparatus through optical isolation of the samples and also by using 125 kVp X-ray beams whose energy is below the threshold for generating Cerenkov radiation in that medium. Results: Terbium-doped GdF3 nanoplates show characteristic cathodoluminescence emission peaks at 488, 543, 586, and 619 nm, which are responsible for the characteristic f-f transition of terbium ion. In a series of experiments, the contribution of Cerenkov radiation in the luminescence of such nanophosphors was ruled out. Conclusion: We have characterized the optical properties of Terbium-doped GdF3 nanoplates. Such nanocrystals with emission tunability and high surface area that facilitates attachment with targeting reagents are promising in situ light source candidates for molecular imaging or exciting a photosensitizer for ultralow fluence photodynamic therapy. This work is supported by the Department of Radiation Oncology at the University of Pennsylvania, the American Cancer Society through IRG-78-002-28, and the University of Pennsylvania's Nano/Bio Interface Center through NSEC DMR08-32802.« less

bHROS: A New High-Resolution Spectrograph Available on Gemini South

NASA Astrophysics Data System (ADS)

Margheim, S. J.; Gemini bHROS Team

2005-12-01

The Gemini bench-mounted High-Resolution Spectrograph (bHROS) is available for science programs beginning in 2006A. bHROS is the highest resolution (R=150,000) optical echelle spectrograph optimized for use on an 8-meter telescope. bHROS is fiber-fed via GMOS-S from the Gemini South focal plane and is available in both a dual-fiber Object/Sky mode and a single (larger) Object-only mode. Instrument characteristics and sample data taken during commissioning will be presented.

A FEROS Survey of Hot Subdwarf Stars

NASA Astrophysics Data System (ADS)

Vennes, Stéphane; Németh, Péter; Kawka, Adela

2018-02-01

We have completed a survey of twenty-two ultraviolet-selected hot subdwarfs using the Fiber-fed Extended Range Optical Spectrograph (FEROS) and the 2.2-m telescope at La Silla. The sample includes apparently single objects as well as hot subdwarfs paired with a bright, unresolved companion. The sample was extracted from our GALEX catalogue of hot subdwarf stars. We identified three new short-period systems (P = 3.5 hours to 5 days) and determined the orbital parameters of a long-period (P = 62d.66) sdO plus G III system. This particular system should evolve into a close double degenerate system following a second common envelope phase.We also conducted a chemical abundance study of the subdwarfs: Some objects show nitrogen and argon abundance excess with respect to oxygen. We present key results of this programme.

VizieR Online Data Catalog: Abundance analysis of 9 very metal-poor stars (O'Malley+, 2017)

NASA Astrophysics Data System (ADS)

O'Malley, E. M.; McWilliam, A.; Chaboyer, B.; Thompson, I.

2017-10-01

We were awarded time on HST to obtain fine guidance sensor (FGS) parallaxes of nine very metal-poor stars with the goal of extending the range of metallicities below at least [Fe/H]=-2.3dex for stars with well-determined parallaxes. High-resolution spectroscopy of the nine target stars were obtained between 2008 and 2012 using the Magellan Inamori Kyocera Echelle (MIKE) double spectrograph on the 6.5m Magellan II Clay Telescope at Las Campanas Observatory, Chile (R=48000 for the red side and R=55000 for the blue side), and the High-Resolution Echelle Spectrometer (HiRES) on the twin telescopes at the W. M. Keck Observatory (R~70500). A log of the spectroscopic observations along with the HST F606W magnitudes and parallaxes appears in Table 1. (5 data files).

Analysis of dynamic properties for a composite laminated beam at intermediate strain rate

NASA Astrophysics Data System (ADS)

Lin, J. C.; Pendleton, R. L.; Dolan, D. F.

The dynamic mechanical behavior of a graphite epoxy composite laminate in flexural vibration has been investigated. The effects of fiber orientation and vibration frequency for both unidirectional tape and Kevlar fabric were studied both analytically and experimentally. Measurement of storage and loss moduli were presented for laminated double cantilever beams of fiber reinforced composite with frequency range from 8 to 1230 Hz (up to 5th mode).

Improved Electro-Optical Switches

NASA Technical Reports Server (NTRS)

Nelson, Bruce N.; Cooper, Ronald F.

1994-01-01

Improved single-pole, double-throw electro-optical switches operate in switching times less than microsecond developed for applications as optical communication systems and networks of optical sensors. Contain no moving parts. In comparison with some prior electro-optical switches, these are simpler and operate with smaller optical losses. Beam of light switched from one output path to other by applying, to electro-optical crystal, voltage causing polarization of beam of light to change from vertical to horizontal.

Linear time-to-space mapping system using double electrooptic beam deflectors.

PubMed

Hisatake, Shintaro; Tada, Keiji; Nagatsuma, Tadao

2008-12-22

We propose and demonstrate a linear time-to-space mapping system, which is based on two times electrooptic sinusoidal beam deflection. The direction of each deflection is set to be mutually orthogonal with the relative deflection phase of pi/2 rad so that the circular optical beam trajectory can be achieved. The beam spot at the observation plane moves with an uniform velocity and as a result linear time-to-space mapping (an uniform temporal resolution through the mapping) can be realized. The proof-of-concept experiment are carried out and the temporal resolution of 5 ps has been demonstrated using traveling-wave type quasi-velosity-matched electrooptic beam deflectors. The developed system is expected to be applied to characterization of ultrafast optical signal or optical arbitrary waveform shaping for modulated microwave/millimeter-wave generation.

Coherent control of the Goos-Hänchen shift via Fano interference

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

Liu, Shaopeng; Yang, Wen-Xing, E-mail: wenxingyang@seu.edu.cn; Zhu, Zhonghu

2016-04-14

A scheme of enhanced Goos-Hänchen (GH) shifts in reflected and transmitted light beams is exploited in a cavity, where an asymmetric double AlGaAs/GaAs quantum well structure with resonant tunneling to a common continuum is employed as the intracavity medium. With the help of Fano-type interference induced by resonant tunneling, the generated GH shifts that contain a negative lateral shift in reflected light beam and a positive lateral shift in transmitted light beam are found to be significantly enhanced. More interestingly, these GH shifts in reflected and transmitted light beams are modulated by means of a control beam and external biasmore » voltage, in which maximum negative shift of 1.86 mm and positive shift of 0.37 mm are achievable.« less

Overview of laser systems for the Orion facility at the AWE.

PubMed

Hopps, Nicholas; Danson, Colin; Duffield, Stuart; Egan, David; Elsmere, Stephen; Girling, Mark; Harvey, Ewan; Hillier, David; Norman, Michael; Parker, Stefan; Treadwell, Paul; Winter, David; Bett, Thomas

2013-05-20

The commissioning of the Orion laser facility at the Atomic Weapons Establishment (AWE) in the UK has recently been completed. The facility is a twelve beam Nd:glass-based system for studying high energy density physics. It consists of ten frequency-tripled beam-lines operating with nanosecond pulses, synchronized with two beam-lines with subpicosecond pulses, each capable of delivering 500 J to target. One of the short pulse beams has the option of frequency doubling, at reduced aperture, to yield up to 100 J at 527 nm in a subpicosecond pulse with high temporal contrast. An extensive array of target diagnostics is provided. This article describes the laser design and commissioning and presents key performance data of the facility's laser systems.

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

Wei, Zi-an; Ma, J. X., E-mail: jxma@ustc.edu.cn

Ion sheaths formed in the up- and downstream sides of a negatively biased metal plate/mesh in an ion-beam-background-plasma system were experimentally investigated in a double plasma device. Measured potential profiles near the plate exhibit asymmetric structure, showing thicker sheath in the downstream side. The presence of the ion beam causes the shrink of the sheaths on both sides. The sheath thickness decreases with the increase of beam energy and density. Furthermore, the sheaths near the mesh are substantially thinner than that near the plate because of the partial transmission of the mesh to the ions. In addition, the increase ofmore » neutral gas pressure leads to the reduction of the beam energy and density, resulting in the increase of the sheath thickness.« less

Evaluating the beam quality of double-cladding fiber lasers in applications.

PubMed

Yan, Ping; Wang, Xuejiao; Gong, Mali; Xiao, Qirong

2016-08-10

We put forward a new β_FL factor, which is used exclusively in fiber lasers and is suitable to assess beam quality and choose the LP₀₁ mode as the new suitable ideal beam. We present a new simple measurement method and verify the reasonability of the β_FL factor in experiment in a 20/400 μm fiber laser. Furthermore, we use the β_FL factor to evaluate the beam quality of a 3-kW-level fiber laser. It can be concluded that β_FL is a key factor not only for assessing the performance of the high-power fiber laser that is our main focus, but also for the simple measurement.

Designing and commissioning of a prototype double Laue monochromator at CHESS

NASA Astrophysics Data System (ADS)

Ko, J. Y. Peter; Oswald, Benjamin B.; Savino, James J.; Pauling, Alan K.; Lyndaker, Aaron; Revesz, Peter; Miller, Matthew P.; Brock, Joel D.

2014-03-01

High-energy X-rays are efficiently focused sagittally by a set of asymmetric Laue (transmission) crystals. We designed, built and commissioned a prototype double Laue monochromator ((111) reflection in Si(100)) optimized for high-energy X-rays (30-60 keV). Here, we report our design of novel prototype sagittal bender and highlight results from recent characterization experiments. The design of the bender combines the tuneable bending control afforded by previous leaf-spring designs with the stability and small size of a four-bar bender. The prototype monochromator focuses a 25 mm-wide white beam incident on the first monochromator crystal to a monochromatized 0.6 mm beam waist in the experimental station. Compared to the flux in the same focal spot with the Bragg crystal (without focusing), the prototype Laue monochromator delivered 85 times more at 30 keV.

Influence of frequency tuning and double-frequency heating on ions extracted from an electron cyclotron resonance ion source

NASA Astrophysics Data System (ADS)

Maimone, F.; Celona, L.; Lang, R.; Mäder, J.; Roßbach, J.; Spädtke, P.; Tinschert, K.

2011-12-01

The electromagnetic field within the plasma chamber of an electron cyclotron resonance ion source (ECRIS) and the properties of the plasma waves affect the plasma properties and ion beam production. We have experimentally investigated the "frequency tuning effect" and "double frequency heating" on the CAPRICE ECRIS device. A traveling wave tube amplifier, two microwave sweep generators, and a dedicated experimental set-up were used to carry out experiments in the 12.5-16.5 GHz frequency range. During the frequency sweeps the evolution of the intensity and shape of the extracted argon beam were measured together with the microwave reflection coefficient. A range of different ion source parameter settings was used. Here we describe these experiments and the resultant improved understanding of these operational modes of the ECR ion source.

Influence of frequency tuning and double-frequency heating on ions extracted from an electron cyclotron resonance ion source.

PubMed

Maimone, F; Celona, L; Lang, R; Mäder, J; Rossbach, J; Spädtke, P; Tinschert, K

2011-12-01

The electromagnetic field within the plasma chamber of an electron cyclotron resonance ion source (ECRIS) and the properties of the plasma waves affect the plasma properties and ion beam production. We have experimentally investigated the "frequency tuning effect" and "double frequency heating" on the CAPRICE ECRIS device. A traveling wave tube amplifier, two microwave sweep generators, and a dedicated experimental set-up were used to carry out experiments in the 12.5-16.5 GHz frequency range. During the frequency sweeps the evolution of the intensity and shape of the extracted argon beam were measured together with the microwave reflection coefficient. A range of different ion source parameter settings was used. Here we describe these experiments and the resultant improved understanding of these operational modes of the ECR ion source.

Double spin asymmetries of inclusive hadron electroproductions from a transversely polarized ³He target

DOE PAGES

Zhao, Yuxiang X.

2015-07-14

We report the measurement of beam-target double-spin asymmetries A LT in the inclusive production of identified hadrons, e +³He ↑ → h + X, using a longitudinally polarized 5.9 GeV electron beam and a transversely polarized ³He target. Hadrons (π ±, K ± and proton) were detected at 16° with an average momentum h>=2.35 GeV/c and a transverse momentum (p T) coverage from 0.60 to 0.68 GeV/c. Asymmetries from the ³He target were observed to be non-zero for π ± production when the target was polarized transversely in the horizontal plane. The π⁺ and π⁻ asymmetries have opposite signs, analogousmore » to the behavior of A LT in semi-inclusive deep-inelastic scattering.« less

High power single-frequency and frequency-doubled laser with active compensation for the thermal lens effect of terbium gallium garnet crystal.

PubMed

Yin, Qiwei; Lu, Huadong; Su, Jing; Peng, Kunchi

2016-05-01

The thermal lens effect of terbium gallium garnet (TGG) crystal in a high power single-frequency laser severely limits the output power and the beam quality of the laser. By inserting a potassium dideuterium phosphate (DKDP) slice with negative thermo-optical coefficient into the laser resonator, the harmful influence of the thermal lens effect of the TGG crystal can be effectively mitigated. Using this method, the stable range of the laser is broadened, the bistability phenomenon of the laser during the process of changing the pump power is completely eliminated, the highest output power of an all-solid-state continuous-wave intracavity-frequency-doubling single-frequency laser at 532 nm is enhanced to 30.2 W, and the beam quality of the laser is significantly improved.

A comparison of constant-load and constant-deflection stress-corrosion tests on precracked DCB specimens. [Double Cantilever Beam

NASA Technical Reports Server (NTRS)

Dorward, R. C.; Hasse, K. R.

1978-01-01

A comparison is made between measurements of stress-corrosion crack propagation made by a constant-load procedure and by a constant-deflection procedure. Precracked double cantilever beam specimens from 7075 aluminum alloy plate were used. The specimens were oriented in such a way that cracking would begin in the short-transverse plane and would propagate in the rolling direction. The specimens were subjected to a buffered salt-chromate solution and a 3.6% synthetic sea salt solution. The measurements were made optically with a binocular microscope. Stress intensities and crack lengths were calculated and crack velocities were obtained. Velocity was plotted against the average calculated stress intensity. Good agreement between the two methods was found for the salt-chromate solution, although some descrepancies were noted for the artificial sea salt solution.

Impedance of an intense plasma-cathode electron source for tokamak startup

DOE PAGES

Hinson, Edward Thomas; Barr, Jayson L.; Bongard, Michael W.; ...

2016-05-31

In this study, an impedance model is formulated and tested for the ~1kV, ~1kA/cm 2, arc-plasma cathode electron source used for local helicity injection tokamak startup. A double layer sheath is established between the high-density arc plasma (n arc ≈ 10 21 m -3) within the electron source, and the less dense external tokamak edge plasma (n edge ≈ 10 18 m -3) into which current is injected at the applied injector voltage, V inj. Experiments on the Pegasus spherical tokamak show the injected current, I inj, increases with V inj according to the standard double layer scaling I injmore » ~ V inj 3/2 at low current and transitions to I inj ~ V inj 1/2 at high currents. In this high current regime, sheath expansion and/or space charge neutralization impose limits on the beam density n b ~ I inj/V inj 1/2. For low tokamak edge density n edge and high I inj, the inferred beam density n b is consistent with the requirement n b ≤ n edge imposed by space-charge neutralization of the beam in the tokamak edge plasma. At sufficient edge density, n b ~ n arc is observed, consistent with a limit to n b imposed by expansion of the double layer sheath. These results suggest that n arc is a viable control actuator for the source impedance.« less

Design and implementation of a robust and cost-effective double-scattering system at a horizontal proton beamline

NASA Astrophysics Data System (ADS)

Helmbrecht, S.; Baumann, M.; Enghardt, W.; Fiedler, F.; Krause, M.; Lühr, A.

2016-11-01

Purpose: particle therapy has the potential to improve radiooncology. With more and more facilities coming into operation, also the interest for research at proton beams increases. Though many centers provide beam at an experimental room, some of them do not feature a device for radiation field shaping, a so called nozzle. Therefore, a robust and cost-effective double-scattering system for horizontal proton beamlines has been designed and implemented. Materials and methods: the nozzle is based on the double scattering technique. Two lead scatterers, an aluminum ridge-filter and two brass collimators were optimized in a simulation study to form a laterally homogeneous 10 cm × 10 cm field with a spread-out Bragg-peak (SOBP). The parts were mainly manufactured using 3D printing techniques and the system was set up at OncoRay's experimental beamline. Measurement of the radiation field were carried out using a water phantom. Results: high levels of dose homogeneity were found in lateral (dose variation ΔD/D < ±2%) as well as in beam direction (ΔD/D < ± 3% in the SOBP). The system has already been used for radiobiology and physical experiments. Conclusion: the presented setup allows for creating clinically realistic extended radiation fields at fixed horizontal proton beamlines and is ready to use for internal and external users. The excellent performance combined with the simplistic design let it appear as a valuable option for proton therapy centers intending to foster their experimental portfolio.

Remote double resonance coupling of radar energy to ionospheric irregularities

NASA Technical Reports Server (NTRS)

Kennel, C. F.

1971-01-01

Experimental results indicate that low frequency modulation of a high power radar beam, tuned to one of the critical frequencies of the ionosphere, may produce field-aligned density irregularities when the modulation frequency matches an ionospheric eigenfrequency. By choosing the radar carrier frequency and polarization, a number of interaction layers were selected. The variety of possible excitations shows that the double resonance technique may be adaptable to a number of different objectives.

Sensitivity Testing of the NSTAR Ion Thruster

NASA Technical Reports Server (NTRS)

Sengupta, Anita; Anderson, John; Brophy, John

2007-01-01

During the Extended Life Test of the DS1 flight spare ion thruster, the engine was subjected to sensitvity testing in order to characterize the macroscopic dependence of discharge chamber sensitivity to a +\\-3% vatiation in main flow, cathode flow and beam current, and to +\\5% variation in beam and accelerator voltage, was determined for the minimum- (THO), half- (TH8) and full power (TH15) throttle levels. For each power level investigared, 16 high/low operating conditions were chosen to vary the flows, beam current, and grid voltages in in a matrix that mapped out the entire parameter space. The matrix of data generated was used to determine the partial derivative or senitivity of the dependent parameters--discharge voltage, discharge current, discharge loss, double-to-single-ion current ratio, and neutralizer-keeper voltage--to the variation in the independent parameters--main flow, cathode flow, beam current, and beam voltage. The sensititivities of each dependent parameter with respect to each independent parameter were determined using a least-square fit routine. Variation in these sensitivities with thruster runtime was recorded over the duration of the ELT, to detemine if discharge performance changed with thruster wear. Several key findings have been ascertained from the sensitivity testing. Discharge operation is most sensitve to changes in cathode flow and to a lesser degree main flow. The data also confirms that for the NSTAR configuration plasma production is limited by primary electron input due to the fixed neutral population. Key sensitivities along with their change with thruster wear (operating time) will be presented. In addition double ion content measurements with an ExB probe will also be presented to illustrate beam ion production and content sensitivity to the discharge chamber operating parameteres.

Instantaneous electron beam emittance measurement system based on the optical transition radiation principle

NASA Astrophysics Data System (ADS)

Jiang, Xiao-Guo; Wang, Yuan; Zhang, Kai-Zhi; Yang, Guo-Jun; Shi, Jin-Shui; Deng, Jian-Jun; Li, Jin

2014-01-01

One kind of instantaneous electron beam emittance measurement system based on the optical transition radiation principle and double imaging optical method has been set up. It is mainly adopted in the test for the intense electron-beam produced by a linear induction accelerator. The system features two characteristics. The first one concerns the system synchronization signal triggered by the following edge of the main output waveform from a Blumlein switch. The synchronous precision of about 1 ns between the electron beam and the image capture time can be reached in this way so that the electron beam emittance at the desired time point can be obtained. The other advantage of the system is the ability to obtain the beam spot and beam divergence in one measurement so that the calculated result is the true beam emittance at that time, which can explain the electron beam condition. It provides to be a powerful beam diagnostic method for a 2.5 kA, 18.5 MeV, 90 ns (FWHM) electron beam pulse produced by Dragon I. The ability of the instantaneous measurement is about 3 ns and it can measure the beam emittance at any time point during one beam pulse. A series of beam emittances have been obtained for Dragon I. The typical beam spot is 9.0 mm (FWHM) in diameter and the corresponding beam divergence is about 10.5 mrad.

An Ultraviolet Spectrograph Concept for Exploring Ocean Worlds

NASA Astrophysics Data System (ADS)

Schindhelm, E. R.; Hendrix, A. R.; Fleming, B. T.

2018-05-01

UV spectroscopy can probe dust/ice composition of the surface or plumes via uniquely identifying features. We present a technology concept for a future planetary science UV multi-object imaging spectrograph.

Small Astronomy Payloads for Spacelab. [conferences

NASA Technical Reports Server (NTRS)

Bohlin, R. C. (Editor)

1975-01-01

The workshop to define feasible concepts in the UV-optical 1R area for Astronomy Spacelab Payloads is reported. Payloads proposed include: high resolution spectrograph, Schmidt camera spectrograph, UV telescope, and small infrared cryogenic telescope.

PRISM Spectrograph Optical Design

NASA Technical Reports Server (NTRS)

Chipman, Russell A.

1995-01-01

The objective of this contract is to explore optical design concepts for the PRISM spectrograph and produce a preliminary optical design. An exciting optical configuration has been developed which will allow both wavelength bands to be imaged onto the same detector array. At present the optical design is only partially complete because PRISM will require a fairly elaborate optical system to meet its specification for throughput (area*solid angle). The most complex part of the design, the spectrograph camera, is complete, providing proof of principle that a feasible design is attainable. This camera requires 3 aspheric mirrors to fit inside the 20x60 cm cross-section package. A complete design with reduced throughput (1/9th) has been prepared. The design documents the optical configuration concept. A suitable dispersing prism material, CdTe, has been identified for the prism spectrograph, after a comparison of many materials.

Optical design of a versatile FIRST high-resolution near-IR spectrograph

NASA Astrophysics Data System (ADS)

Zhao, Bo; Ge, Jian

2012-09-01

We report the update optical design of a versatile FIRST high resolution near IR spectrograph, which is called Florida IR Silicon immersion grating spectromeTer (FIRST). This spectrograph uses cross-dispersed echelle design with white pupils and also takes advantage of the image slicing to increase the spectra resolution, while maintaining the instrument throughput. It is an extremely high dispersion R1.4 (blazed angle of 54.74°) silicon immersion grating with a 49 mm diameter pupil is used as the main disperser at 1.4μm -1.8μm to produce R=72,000 while an R4 echelle with the same pupil diameter produces R=60,000 at 0.8μm -1.35μm. Two cryogenic Volume Phase Holographic (VPH) gratings are used as cross-dispersers to allow simultaneous wavelength coverage of 0.8μm -1.8μm. The butterfly mirrors and dichroic beamsplitters make a compact folding system to record these two wavelength bands with a 2kx2k H2RG array in a single exposure. By inserting a mirror before the grating disperser (the SIG and the echelle), this spectrograph becomes a very efficient integral field 3-D imaging spectrograph with R=2,000-4,000 at 0.8μm-1.8μm by coupling a 10x10 telescope fiber bundle with the spectrograph. Details about the optical design and performance are reported.

Time-of-flight mass spectrographs—From ions to neutral atoms

NASA Astrophysics Data System (ADS)

Möbius, E.; Galvin, A. B.; Kistler, L. M.; Kucharek, H.; Popecki, M. A.

2016-12-01

After their introduction to space physics in the mid 1980s time-of-flight (TOF) spectrographs have become a main staple in spaceborne mass spectrometry. They have largely replaced magnetic spectrometers, except when extremely high mass resolution is required to identify complex molecules, for example, in the vicinity of comets or in planetary atmospheres. In combination with electrostatic analyzers and often solid state detectors, TOF spectrographs have become key instruments to diagnose space plasma velocity distributions, mass, and ionic charge composition. With a variety of implementation schemes that also include isochronous electric field configurations, TOF spectrographs can respond to diverse science requirements. This includes a wide range in mass resolution to allow the separation of medium heavy isotopes or to simply provide distributions of the major species, such as H, He, and O, to obtain information on source tracers or mass fluxes. With a top-hat analyzer at the front end, or in combination with deflectors for three-axis stabilized spacecraft, the distribution function of ions can be obtained with good time resolution. Most recently, the reach of TOF ion mass spectrographs has been extended to include energetic neutral atoms. After selecting the arrival direction with mechanical collimation, followed by conversion to ions, adapted TOF sensors form a new branch of the spectrograph family tree. We review the requirements, challenges, and implementation schemes for ion and neutral atom spectrographs, including potential directions for the future, while largely avoiding overlap with complementary contributions in this special issue.

A Cross-Dispersed Medium-Resolution Spectrograph for Appalachian State Univeristy's 32-inch Telescope

NASA Astrophysics Data System (ADS)

Kluttz, K. A.; Gray, R. O.

2003-12-01

We have designed and constructed an economical medium-resolution spectrograph to be used on the 32-inch telescope of Appalachian State University's Dark Sky Observatory (DSO). The primary function of this instrument will be to study shell and emission-line stars. However, we will also use this instrument for chemical abundance studies and radial velocities. The basic design is that of an Ebert spectrograph with a single 6-inch mirror acting as both the collimator and camera. The primary dispersion is accomplished by a reflection grating, and order separation is accomplished by a grism. The spectrograph has been designed so that three wavelength regions are simultaneously imaged on the CCD camera. When the Hα line is centered in the third order, Hβ and lines of Fe II multiplet 42 -- often enhanced in shell and emission-line stars -- appear in the fourth order and the fifth order contains both the Ca II K & H lines. To facilitate abundance measurements, a telluric-free region near 6400Å is available in the third order by tilting the main diffraction grating. Preliminary tests have shown that the resolution of the new spectrograph is 0.42Å in the third order (R ≈ 15,000). This relatively high resolution will allow studies to be conducted at DSO which have not previously been possible with the instrumentation currently in use. Several optical components for this spectrograph were purchased with grants from the Fund for Astrophysical Research and the University Research Council.

Suppression of fiber modal noise induced radial velocity errors for bright emission-line calibration sources

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

Mahadevan, Suvrath; Halverson, Samuel; Ramsey, Lawrence

2014-05-01

Modal noise in optical fibers imposes limits on the signal-to-noise ratio (S/N) and velocity precision achievable with the next generation of astronomical spectrographs. This is an increasingly pressing problem for precision radial velocity spectrographs in the near-infrared (NIR) and optical that require both high stability of the observed line profiles and high S/N. Many of these spectrographs plan to use highly coherent emission-line calibration sources like laser frequency combs and Fabry-Perot etalons to achieve precision sufficient to detect terrestrial-mass planets. These high-precision calibration sources often use single-mode fibers or highly coherent sources. Coupling light from single-mode fibers to multi-mode fibersmore » leads to only a very low number of modes being excited, thereby exacerbating the modal noise measured by the spectrograph. We present a commercial off-the-shelf solution that significantly mitigates modal noise at all optical and NIR wavelengths, and which can be applied to spectrograph calibration systems. Our solution uses an integrating sphere in conjunction with a diffuser that is moved rapidly using electrostrictive polymers, and is generally superior to most tested forms of mechanical fiber agitation. We demonstrate a high level of modal noise reduction with a narrow bandwidth 1550 nm laser. Our relatively inexpensive solution immediately enables spectrographs to take advantage of the innate precision of bright state-of-the art calibration sources by removing a major source of systematic noise.« less

Characterizing the Performance of the Princeton Advanced Test Stand Ion Source

NASA Astrophysics Data System (ADS)

Stepanov, A.; Gilson, E. P.; Grisham, L.; Kaganovich, I.; Davidson, R. C.

2012-10-01

The Princeton Advanced Test Stand (PATS) is a compact experimental facility for studying the physics of intense beam-plasma interactions relevant to the Neutralized Drift Compression Experiment - II (NDCX-II). The PATS facility consists of a multicusp RF ion source mounted on a 2 m-long vacuum chamber with numerous ports for diagnostic access. Ar+ beams are extracted from the source plasma with three-electrode (accel-decel) extraction optics. The RF power and extraction voltage (30 - 100 kV) are pulsed to produce 100 μsec duration beams at 0.5 Hz with excellent shot-to-shot repeatability. Diagnostics include Faraday cups, a double-slit emittance scanner, and scintillator imaging. This work reports measurements of beam parameters for a range of beam energies (30 - 50 keV) and currents to characterize the behavior of the ion source and extraction optics. Emittance scanner data is used to calculate the beam trace-space distribution and corresponding transverse emittance. If the plasma density is changing during a beam pulse, time-resolved emittance scanner data has been taken to study the corresponding evolution of the beam trace-space distribution.

Fluorescence/depolarization lidar for mid-range stand-off detection of biological agents

NASA Astrophysics Data System (ADS)

Mierczyk, Z.; Kopczyński, K.; Zygmunt, M.; Wojtanowski, J.; Młynczak, J.; Gawlikowski, A.; Młodzianko, A.; Piotrowski, W.; Gietka, A.; Knysak, P.; Drozd, T.; Muzal, M.; Kaszczuk, M.; Ostrowski, R.; Jakubaszek, M.

2011-06-01

LIDAR system for real-time standoff detection of bio-agents is presented and preliminary experimental results are discussed. The detection approach is based on two independent physical phenomena: (1) laser induced fluorescence (LIF), (2) depolarization resulting from elastic scattering on non-spherical particles. The device includes three laser sources, two receiving telescopes, depolarization component and spectral signature analyzing spectrograph. It was designed to provide the stand-off detection capability at ranges from 200 m up to several kilometers. The system as a whole forms a mobile platform for vehicle or building installation. Additionally, it's combined with a scanning mechanics and advanced software, which enable to conduct the semi-automatic monitoring of a specified space sector. For fluorescence excitation, 3-rd (355 nm) and 4-th (266 nm) harmonics of Nd:YAG pulsed lasers are used. They emit short (~6 ns) pulses with the repetition rate of 20 Hz. Collecting optics for fluorescence echo detection and spectral content analysis includes 25 mm diameter f/4 Newton telescope, Czerny Turner spectrograph and 32-channel PMT. Depending on the grating applied, the spectral resolution from 20 nm up to 3 nm per channel can be achieved. The system is also equipped with an eye-safe (1.5 μm) Nd:YAG OPO laser for elastic backscattering/depolarization detection. The optical echo signal is collected by Cassegrain telescope with aperture diameter of 12.5 mm. Depolarization detection component based on polarizing beam-splitter serves as the stand-off particle-shape analyzer, which is very valuable in case of non-spherical bio-aerosols sensing.

HYDROGEN BALMER CONTINUUM IN SOLAR FLARES DETECTED BY THE INTERFACE REGION IMAGING SPECTROGRAPH (IRIS)

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

Heinzel, P.; Kleint, L., E-mail: pheinzel@asu.cas.cz

We present a novel observation of the white light flare (WLF) continuum, which was significantly enhanced during the X1 flare on 2014 March 29 (SOL2014-03-29T17:48). Data from the Interface Region Imaging Spectrograph (IRIS) in its near-UV channel show that at the peak of the continuum enhancement, the contrast at the quasi-continuum window above 2813 Å reached 100%-200% and can be even larger closer to Mg II lines. This is fully consistent with the hydrogen recombination Balmer-continuum emission, which follows an impulsive thermal and non-thermal ionization caused by the precipitation of electron beams through the chromosphere. However, a less probable photosphericmore » continuum enhancement cannot be excluded. The light curves of the Balmer continuum have an impulsive character with a gradual fading, similar to those detected recently in the optical region on the Solar Optical Telescope on board Hinode. This observation represents a first Balmer-continuum detection from space far beyond the Balmer limit (3646 Å), eliminating seeing effects known to complicate the WLF detection. Moreover, we use a spectral window so far unexplored for flare studies, which provides the potential to study the Balmer continuum, as well as many metallic lines appearing in emission during flares. Combined with future ground-based observations of the continuum near the Balmer limit, we will be able to disentangle various scenarios of the WLF origin. IRIS observations also provide a critical quantitative measure of the energy radiated in the Balmer continuum, which constrains various models of the energy transport and deposit during flares.« less

GMTIFS: challenging optical design problems and their solutions for the GMT integral-field spectrograph

NASA Astrophysics Data System (ADS)

Hart, John; Bloxham, Gabe; Boz, Robert; Espeland, Brady; Sharp, Robert

2016-08-01

GMTIFS is a first generation instrument for the Giant Magellan Telescope (GMT). It is a combined Imager and Integral Field Spectrograph (IFS) designed to work with the Adaptive Optics (AO) Systems of the GMT. Working at the diffraction limit of the GMT and satisfying the challenging AO interface requirements and constraints results in unique optical challenges. We describe two of these challenges and how we have addressed them. The GMT has a direct feed architecture that maximizes transmission and reduces emissivity. This means that the cryostat window is tilted to reflect visual wavelengths to the external Visual Wave Front Subsystem (VWS). For a plane-parallel window, this tilt causes astigmatism in the transmitted beam that must be corrected. A corrective system using two plates, tilted and slightly wedged in opposite directions, is used. Geometry and performance of the system is described. Another challenging problem is the optical design of the anamorphic field projector. The Integral Field Unit of GMTIFS requires that a small field delivered to it be projected onto an Image Slicer at much larger scale, with the magnification in the spectral direction being twice that in the spatial direction so that the spaxels are square when referred to the sky. Output images must be coincident in the spectral and spatial projections in both the field and pupil domains. Additionally, field and pupil image locations must be independently controllable so that they can be made coincident for interchangeable units that provide a range of output field scales. A two-mirror system that satisfies these requirements is described.

On-board data processing for the near infrared spectrograph and photometer instrument (NISP) of the EUCLID mission

NASA Astrophysics Data System (ADS)

Bonoli, Carlotta; Balestra, Andrea; Bortoletto, Favio; D'Alessandro, Maurizio; Farinelli, Ruben; Medinaceli, Eduardo; Stephen, John; Borsato, Enrico; Dusini, Stefano; Laudisio, Fulvio; Sirignano, Chiara; Ventura, Sandro; Auricchio, Natalia; Corcione, Leonardo; Franceschi, Enrico; Ligori, Sebastiano; Morgante, Gianluca; Patrizii, Laura; Sirri, Gabriele; Trifoglio, Massimo; Valenziano, Luca

2016-07-01

The Near Infrared Spectrograph and Photometer (NISP) is one of the two instruments on board the EUCLID mission now under implementation phase; VIS, the Visible Imager is the second instrument working on the same shared optical beam. The NISP focal plane is based on a detector mosaic deploying 16x, 2048x2048 pixels^2 HAWAII-II HgCdTe detectors, now in advanced delivery phase from Teledyne Imaging Scientific (TIS), and will provide NIR imaging in three bands (Y, J, H) plus slit-less spectroscopy in the range 0.9÷2.0 micron. All the NISP observational modes will be supported by different parametrization of the classic multi-accumulation IR detector readout mode covering the specific needs for spectroscopic, photometric and calibration exposures. Due to the large number of deployed detectors and to the limited satellite telemetry available to ground, a consistent part of the data processing, conventionally performed off-line, will be accomplished on board, in parallel with the flow of data acquisitions. This has led to the development of a specific on-board, HW/SW, data processing pipeline, and to the design of computationally performing control electronics, suited to cope with the time constraints of the NISP acquisition sequences during the sky survey. In this paper we present the architecture of the NISP on-board processing system, directly interfaced to the SIDECAR ASICs system managing the detector focal plane, and the implementation of the on-board pipe-line allowing all the basic operations of input frame averaging, final frame interpolation and data-volume compression before ground down-link.

Marching of the microlithography horses: electron, ion, and photon: past, present, and future

NASA Astrophysics Data System (ADS)

Lin, Burn J.

2007-03-01

Microlithography patterning employs one of three media; electron, ion, and photon. They are in a way like horses, racing towards the mainstream. Some horses such as electrons run fast but repel each other. Ion beams behave like electron beams but are less developed. The photon beam is the undisputed workhorse, taking microlithography from the 5-μm minimum feature size to 32-nm half pitch. This paper examines the history of microlithography in pattern generation, proximity printing, and projection printing, then identifies the strong and weak points of each technology. In addition to ion-beam and e-beam lithography, the coverage of optical lithography spans the wavelength from 436 to 13.5 nm. Our learning from history helps us prevent mistakes in the future. In almost all cases, making or using the mask presents one of the limiting problems, no matter the type of beams or the replication method. Only the maskless method relieves us from mask-related problems. A way to overcome the low throughput handicap of maskless systems is to use multiple e-beam direct writing, whose imaging lens can be economically and compactly fabricated using MEMS techniques. In a way, the history of microlithography parallels that of aviation. Proximity printing is like the Wright-Brothers' plane; 1X projection printing, single-engine propeller plane with unitized body; reduction step-and-repeat projection printing, multi-engine commercial airliner; scanners, jet airliners. Optical lithography has improved in many ways than just increasing NA and reducing wavelength just as the commercial airliners improving in many other areas than just the speed. The SST increased the speed of airliners by more than a factor of two just as optical resolution doubled with double exposures. EUV lithography with the wavelength reduced by an order of magnitude is similar to the space shuttle increasing its speed to more than 10 times that of the SST. Multiple-beam direct write systems are like helicopters. They do not need airports(masks) but we need a lot of beams to carry the same payload.

SU-F-BRD-08: A Novel Technique to Derive a Clinically-Acceptable Beam Model for Proton Pencil-Beam Scanning in a Commercial Treatment Planning System

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

Scholey, J. E.; Lin, L.; Ainsley, C. G.

2015-06-15

Purpose: To evaluate the accuracy and limitations of a commercially-available treatment planning system’s (TPS’s) dose calculation algorithm for proton pencil-beam scanning (PBS) and present a novel technique to efficiently derive a clinically-acceptable beam model. Methods: In-air fluence profiles of PBS spots were modeled in the TPS alternately as single-(SG) and double-Gaussian (DG) functions, based on fits to commissioning data. Uniform-fluence, single-energy-layer square fields of various sizes and energies were calculated with both beam models and delivered to water. Dose was measured at several depths. Motivated by observed discrepancies in measured-versus-calculated dose comparisons, a third model was constructed based on double-Gaussianmore » parameters contrived through a novel technique developed to minimize these differences (DGC). Eleven cuboid-dose-distribution-shaped fields with varying range/modulation and field size were subsequently generated in the TPS, using each of the three beam models described, and delivered to water. Dose was measured at the middle of each spread-out Bragg peak. Results: For energies <160 MeV, the DG model fit square-field measurements to <2% at all depths, while the SG model could disagree by >6%. For energies >160 MeV, both SG and DG models fit square-field measurements to <1% at <4 cm depth, but could exceed 6% deeper. By comparison, disagreement with the DGC model was always <3%. For the cuboid plans, calculation-versus-measured percent dose differences exceeded 7% for the SG model, being larger for smaller fields. The DG model showed <3% disagreement for all field sizes in shorter-range beams, although >5% differences for smaller fields persisted in longer-range beams. In contrast, the DGC model predicted measurements to <2% for all beams. Conclusion: Neither the TPS’s SG nor DG models, employed as intended, are ideally suited for routine clinical use. However, via a novel technique to be presented, its DG model can be tuned judiciously to yield acceptable results.« less

Enhanced Exoplanet Biosignature from an Interferometer Addition to Low Resolution Spectrographs

NASA Astrophysics Data System (ADS)

Erskine, D. J.; Muirhead, P. S.; Vanderburg, A. M.; Szentgyorgyi, A.

2017-12-01

The absorption spectral signature of many atmospheric molecules consists of a group of 40 or so lines that are approximately periodic due to the physics of molecular vibration. This is fortuitous for detecting atmospheric features in an exoEarth, since it has a similar periodic nature as an interferometer's transmission, which is sinusoidal. The period (in wavenumbers) of the interferometer is selectable, being inversely proportional to the delay (in cm). We show that the addition of a small interferometer of 0.6 cm delay to an existing dispersive spectrograph can greatly enhance the detection of molecular features, by several orders of magnitude for initially low resolution spectrographs. We simulate the Gemini Planet Imager measuring a telluric spectrum having native resolution of 40 and 70 in the 1.65 micron and 2 micron bands. These low resolutions are insufficient to resolve the fine features of the molecular feature group. However, the addition of a 0.6 cm delay outside the spectrograph and in series with it increases the local amplitude of the signal to a level similar to a R=4400 (at 1.65 micron) or R=3900 (at 2 micron) classical spectrograph. Prepared by LLNL under Contract DE-AC52-07NA27344.

Hectospec, the MMT's 300 Optical Fiber-Fed Spectrograph

NASA Astrophysics Data System (ADS)

Fabricant, Daniel; Fata, Robert; Roll, John; Hertz, Edward; Caldwell, Nelson; Gauron, Thomas; Geary, John; McLeod, Brian; Szentgyorgyi, Andrew; Zajac, Joseph; Kurtz, Michael; Barberis, Jack; Bergner, Henry; Brown, Warren; Conroy, Maureen; Eng, Roger; Geller, Margaret; Goddard, Richard; Honsa, Michael; Mueller, Mark; Mink, Douglas; Ordway, Mark; Tokarz, Susan; Woods, Deborah; Wyatt, William; Epps, Harland; Dell'Antonio, Ian

2005-12-01

The Hectospec is a 300 optical fiber fed spectrograph commissioned at the MMT in the spring of 2004. In the configuration pioneered by the Autofib instrument at the Anglo-Australian Telescope, Hectospec's fiber probes are arranged in a radial ``fisherman on the pond'' geometry and held in position with small magnets. A pair of high-speed, six-axis robots move the 300 fiber buttons between observing configurations within ~300 s, and to an accuracy of ~25 μm. The optical fibers run for 26 m between the MMT's focal surface and the bench spectrograph, operating at R~1000-2000. Hectochelle, another high-dispersion bench spectrograph offering R~35,000, is also available. The system throughput, including all losses in the telescope optics, fibers, and spectrograph, peaks at ~10% at the grating blaze in 1" FWHM seeing. Correcting for aperture losses at the 1.5" diameter fiber entrance aperture, the system throughput peaks at ~17%, close to our prediction of 20%. Hectospec has proven to be a workhorse instrument at the MMT. Together, Hectospec and Hectochelle have been scheduled for 1/3 of the available nights since its commissioning. Hectospec has returned approximately 60,000 reduced spectra for 16 scientific programs during its first year of operation.

VizieR Online Data Catalog: weak G-band stars abundances (Palacios+, 2016)

NASA Astrophysics Data System (ADS)

Palacios, A.; Jasniewicz, G.; Masseron, T.; Thevenin, F.; Itam-Pasquet, J.; Parthasarathy, M.

2016-05-01

Seventeen southern wGb stars were observed at La Silla, ESO Chile, with the high-efficiency Fiber-fed Extended Range Optical Spectrograph FEROS spectrograph mounted on the 2.2m telescope. FEROS is a bench-mounted, thermally controlled, prism-cross-dispersed echelle spectrograph, providing, in a single spectrogram spread over 39 orders, almost complete spectral coverage from ~350 to ~920nm at a resolution of 48000. The FEROS observations were carried out during an observing run between May 10 and 13, 2012. All these spectra were flat-fielded and calibrated by means of ThArNe exposures using standard processing tools available at ESO. In addition, two northern wGb stars, HD 18474 and HD 166208, were observed in service mode at the Observatoire du Pic du Midi, France, with the NARVAL spectrograph mounted on the Bernard Lyot 2.0m telescope. The NARVAL instrument consists of a bench-mounted cross-dispersed echelle spectrograph, fibre-fed from a Cassegrain-mounted polarimeter unit. It was used in its non-polarimetric mode; it provided almost complete spectral coverage from ~375 to ~1050nm at a resolution of 75000 in a single spectrogram spread over 40 orders. (6 data files).

Influence of beam efficiency through the patient-specific collimator on secondary neutron dose equivalent in double scattering and uniform scanning modes of proton therapy.

PubMed

Hecksel, D; Anferov, V; Fitzek, M; Shahnazi, K

2010-06-01

Conventional proton therapy facilities use double scattering nozzles, which are optimized for delivery of a few fixed field sizes. Similarly, uniform scanning nozzles are commissioned for a limited number of field sizes. However, cases invariably occur where the treatment field is significantly different from these fixed field sizes. The purpose of this work was to determine the impact of the radiation field conformity to the patient-specific collimator on the secondary neutron dose equivalent. Using a WENDI-II neutron detector, the authors experimentally investigated how the neutron dose equivalent at a particular point of interest varied with different collimator sizes, while the beam spreading was kept constant. The measurements were performed for different modes of dose delivery in proton therapy, all of which are available at the Midwest Proton Radiotherapy Institute (MPRI): Double scattering, uniform scanning delivering rectangular fields, and uniform scanning delivering circular fields. The authors also studied how the neutron dose equivalent changes when one changes the amplitudes of the scanned field for a fixed collimator size. The secondary neutron dose equivalent was found to decrease linearly with the collimator area for all methods of dose delivery. The relative values of the neutron dose equivalent for a collimator with a 5 cm diameter opening using 88 MeV protons were 1.0 for the double scattering field, 0.76 for rectangular uniform field, and 0.6 for the circular uniform field. Furthermore, when a single circle wobbling was optimized for delivery of a uniform field 5 cm in diameter, the secondary neutron dose equivalent was reduced by a factor of 6 compared to the double scattering nozzle. Additionally, when the collimator size was kept constant, the neutron dose equivalent at the given point of interest increased linearly with the area of the scanned proton beam. The results of these experiments suggest that the patient-specific collimator is a significant contributor to the secondary neutron dose equivalent to a distant organ at risk. Improving conformity of the radiation field to the patient-specific collimator can significantly reduce secondary neutron dose equivalent to the patient. Therefore, it is important to increase the number of available generic field sizes in double scattering systems as well as in uniform scanning nozzles.

System selects framing rate for spectrograph camera

NASA Technical Reports Server (NTRS)

1965-01-01

Circuit using zero-order light is reflected to a photomultiplier in the incoming radiation of a spectrograph monitor to provide an error signal which controls the advancing and driving rate of the film through the camera.

Study of the stability of beam characteristics of the neon-like Zn X-ray laser using a half cavity

NASA Astrophysics Data System (ADS)

Präg, A. R.; Mocek, T.; Kozlová, M.; Rus, B.; Jamelot, G.; Ros, D.

2003-01-01

At the Prague Asterix Laser System Center (PALS) the Asterix iodine laser delivering up to 700 J/0.5 ns is used as a pump source for X-ray laser experiments and applications. The prepulse technique was applied which is known to improve the neon-like X-ray laser output at the J = 0 {-} 1 transition dramatically. Since Zn slab targets were used the operating wavelength was 21.2 nm. A prepulse having up to 20 J precedes the main pulse by 10 ns. The main beam and the prepulse beam are focussed by two different optical systems separately and their foci are superimposed at the target surface. By implementing a half-cavity set-up for double-pass amplification using a Mo/Si multilayer mirror which can be used for more than 100 shots the X-ray laser output was more than 10 times stronger than at the single pass in a 30 mm long plasma. Double-pass amplification was observed to be most efficient when the pump pulse duration was at least 150 ps longer than the round trip time (≈ 260 ps) in the half-cavity. Under this fundamental condition the X-ray laser reached saturation in the double-pass regime containing approx. 4 mJ energy which has been proved to be enough for future applications. In this contribution, the X-ray laser features like divergence in two dimensions, the beam quality (symmetry), the pointing angle and the integrated intensity giving an estimation of the output energy are investigated over 110 shots. To characterize the stability of the X-ray laser the shot distribution, the mean value and the standard deviation for these parameters are evaluated. For 18 shots in a series what was achievable during one day the corresponding values are given, and a statistical analysis carrying out a chi-squared test characterize the Zn X-ray laser as a robust tool suitable for applications. In the future it is planned to allocate X-ray laser beam time to external research groups.

Single and double superimposing interferometer systems

DOEpatents

Erskine, David J.

2000-01-01

Interferometers which can imprint a coherent delay on a broadband uncollimated beam are described. The delay value can be independent of incident ray angle, allowing interferometry using uncollimated beams from common extended sources such as lamps and fiber bundles, and facilitating Fourier Transform spectroscopy of wide angle sources. Pairs of such interferometers matched in delay and dispersion can measure velocity and communicate using ordinary lamps, wide diameter optical fibers and arbitrary non-imaging paths, and not requiring a laser.