27 results on '"Eric H. Silver"'
Search Results
2. Exposure and analysis of microparticles embedded in silica aerogel keystones using <scp>NF</scp> 3 ‐mediated electron beam–induced etching and energy‐dispersive X‐ray spectroscopy
- Author
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Andrew J. Westphal, Edward P. Vicenzi, Eric H. Silver, Ting Lin, Jeffrey W. Beeman, Milos Toth, and Aiden A. Martin
- Subjects
Geophysics ,Materials science ,Space and Planetary Science ,Etching (microfabrication) ,0103 physical sciences ,Analytical chemistry ,Energy-dispersive X-ray spectroscopy ,Cathode ray ,Aerogel ,010502 geochemistry & geophysics ,010303 astronomy & astrophysics ,01 natural sciences ,0105 earth and related environmental sciences - Published
- 2016
3. Emission-Line Intensity Ratios in F[CLC]e[/CLC] [CSC]xvii[/CSC] Observed with a Microcalorimeter on an Electron Beam Ion Trap
- Author
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D.A. Landis, Norman W. Madden, Herbert W. Schnopper, George A. Doschek, Nancy Brickhouse, James V. Porto, A. K. Bhatia, John D. Gillaspy, Jeffrey W. Beeman, Eugene E. Haller, J. M. Laming, Simon R. Bandler, Endre Takacs, Marco Barbera, Eric H. Silver, S. S. Murray, I Kink, Laming, J, Kink, I, Takacs, E, Porto, J, Gillaspy, J, Silver, E, Schnopper, H, Bandler, S, Brickhouse, N, Murray, S, Barbera, M, Bhatia, A, Doschek, G, Madden, N, Landis, D, Beeman, J, and Haller, E
- Subjects
Physics ,Methods: laboratory ,Sun: corona ,Detector ,Techniques: spectroscopic ,Astronomy and Astrophysics ,laboratory ,Stars: individual (Capella) ,X-rays: general [Atomic data ,Methods] ,Plasma ,X-rays: general ,Intensity ratio ,Polarization (waves) ,Ion ,Settore FIS/05 - Astronomia E Astrofisica ,Space and Planetary Science ,Radiative transfer ,Emission spectrum ,Atomic physics ,Atomic data ,Electron beam ion trap - Abstract
We report new observations of emission line intensity ratios of Fe XVII under controlled experimental conditions, using the National Institute of Standards and Technology electron beam ion trap (EBIT) with a microcalorimeter detector. We compare our observations with collisional-radiative models using atomic data computed in distorted wave and R-matrix approximations, which follow the transfer of the polarization of level populations through radiative cascades. Our results for the intensity ratio of the 2p6 1S0-2p53d 1P1 15.014 A line to the 2p6 1S0-2p53d 3D1 15.265 A line are 2.94 ± 0.18 and 2.50 ± 0.13 at beam energies of 900 and 1250 eV, respectively. These results are not consistent with collisional-radiative models and support conclusions from earlier EBIT work at the Lawrence Livermore National Laboratory that the degree of resonance scattering in the solar 15.014 A line has been overestimated in previous analyses. Further observations assess the intensity ratio of the three lines between the 2p6-2p53s configurations to the three lines between the 2p6-2p53d configurations. Both R-matrix and distorted wave approximations agree with each other and our experimental results much better than most solar and stellar observations, suggesting that other processes not present in our experiment must play a role in forming the Fe XVII spectrum in solar and astrophysical plasmas.
- Published
- 2000
4. The Extreme Physics Explorer and large area micro-channel plate optics
- Author
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Suzanne Romaine, Brian D. Ramsey, Daniel J. Patnaude, Martin Elvis, Jon H. Chappell, Ian N. Evans, Richard Willingale, Laura Brenneman, George W. Fraser, Eric H. Silver, T. J. Turner, Michael R. Garcia, and Ricardo J. Bruni
- Subjects
Physics ,X-ray astronomy ,Calorimeter (particle physics) ,business.industry ,Antenna aperture ,FOS: Physical sciences ,X-ray optics ,Neutron star ,Optics ,Microchannel plate detector ,Astrophysics - Instrumentation and Methods for Astrophysics ,business ,Spectroscopy ,Instrumentation and Methods for Astrophysics (astro-ph.IM) - Abstract
The Extreme Physics Explorer (EPE) is a concept timing/spectroscopy mission that would use micro-channel plate optics (MCPO) to provide 4 square meters effective area focused to ~1 arc-min onto an X-ray calorimeter. We describe science drivers for such a mission, possible designs for the large area MCPO needed for EPE, and the challenges of the large area MCPO design., Comment: 12 pages, 9 figures, to appear in proceedings of SPIE V8147, "Optics for EUV, X-ray, and Gamma-Ray Astronomy V"
- Published
- 2011
5. Energy resolving X-ray detectors using niobium absorbers and multiple quasiparticle tunneling between two aluminum traps
- Author
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F.S. Goulding, Charles E. Cunningham, Simon E. Labov, Eric H. Silver, R.W. Bland, R.C. Dynes, Norman W. Madden, George W. Morris, M. Le Gros, D.A. Landis, A. T. Barfknecht, Kenneth E. Laws, and C. A. Mears
- Subjects
Fabrication ,Materials science ,Condensed matter physics ,business.industry ,Niobium ,X-ray detector ,chemistry.chemical_element ,Condensed Matter Physics ,Particle detector ,Electronic, Optical and Magnetic Materials ,Tunnel effect ,chemistry ,Optoelectronics ,Superconducting tunnel junction ,Electrical and Electronic Engineering ,business ,Type-II superconductor ,Quantum tunnelling - Abstract
Superconducting tunnel junction devices are being developed for use as high-resolution, high-efficiency X-ray spectrometers. A device with niobium X-ray absorbing layers coupled to two aluminum layers on either side of the tunneling barrier which serve as quasi-particle traps has been tested. These devices were fabricated photolithographically using a modified niobium/aluminum/niobium trilayer fabrication process. The first devices have a very thin barrier with specific normal state resistance of 1.5*10/sup -6/ Omega -cm/sup 2/, and also exhibit very low leakage current ( >
- Published
- 1993
6. Calorimetric ionization detector
- Author
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Eric H. Silver, Paul N. Luke, Simon E. Labov, J. W. Beeman, and F.S. Goulding
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Physics ,Nuclear and High Energy Physics ,Physics::Instrumentation and Detectors ,business.industry ,Ionization ,Ionization detector ,Detector ,Process (computing) ,Optoelectronics ,business ,Instrumentation ,Temperature measurement - Abstract
A new mode of operation for ionization detectors is described. The amount of ionization produced in a detector is determined by measuring the amount of heat generated during the carrier collection process. Very high detection sensitivities, including single carrier detection, may be achieved at cryogenic temperatures. Results from an experimental device operated at T = 0.3 K are presented.
- Published
- 1990
7. Thin-shell plastic lenses for space and laboratory applications
- Author
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Dervis Vernani, Salvatore Varisco, Russell H. Ingram, Maria Antonella Artale, Roberto Candia, Carsten P. Jensen, Vincenzo Cotroneo, Suzanne Romaine, Marco Barbera, Kristin K. Madsen, Eric H. Silver, Herbert W. Schnopper, Alfonso Collura, Finn Erland Christensen, SCHNOPPER HERBERT, W., Ingram, R., Silver, E., Barbera, M., Candia, R., CHRISTENSEN FINN, E., JENSEN CARSTEN, P., ROMAINE SUZANNE, E., Vernani, D., Cotroneo, V., Varisco, S., ARTALE MARIA, A., MADSEN KRISTIN, K., Collura, A., MacDonald, Carolyn A., Macrander, Albert T., Ishikawa, Tetsuya, Morawe, Christian, and Wood, James L.
- Subjects
Materials science ,Scanning electron microscope ,business.industry ,Shell (structure) ,X-ray optics ,X-ray telescope ,law.invention ,Telescope ,chemistry.chemical_compound ,Optics ,Optical coating ,chemistry ,law ,Polyethylene terephthalate ,X-ray optics, X-ray telescopes, X-ray lenses, X-ray imaging, X-ray collimation, medical diagnostics, microanalysis ,Thin film ,business - Abstract
We have identified an inexpensive, readily available, mechanically stable, extremely smooth, elastic, and mechanically uniform plastic suitable for thin film X-ray optics. Polyethylene terephthalate (PET) is easily deformed without losing its elastic properties or surface smoothness. Most important, PET can be coated with mono- or multilayers that reflect X-rays at grazing incidence. We have used these properties to produce X-ray optics made either as a concentric nest of cylinders or as a spiral. We have produced accurately formed shells in precisely machined vacuum mandresl or used a pin and wheel structure to form a continuously wound spiral. The wide range of medical, industrial and scientific applications for our technology includes: a monochromatic X-ray collimater for medical diagnostics, a relay optic to transport an X-ray beam from the target in a scanning electron microscop0e to a lithium-drifted silicon and microcalorimeter detectors and a satellite mounted telescope to collect celestial X-rays. A wide variety of mono- and multilayer coatings allow X-rays up to ~100 keV to be reflected. Our paper presents data from a variety of diagnostic measurements on the properties of the PET foil and imaging results form single- and multi-shell lenses.
- Published
- 2004
8. Visible, EUV, and X-ray Spectroscopy at the NIST EBIT Facility
- Author
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Endre Takacs, H. W. Schnopper, E.-O. Le Bigot, Eric H. Silver, K. Fahey, L P. Ratliff, Alexander Dalgarno, J. M. Laming, J. D. Gillaspy, Károly Tökési, V. Kharchenko, K. Makonyi, L. Lugosi, Joseph N. Tan, H. Tawara, B. Blagojevic, Physics Laboratory (NIST), National Institute of Standards and Technology [Gaithersburg] (NIST), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, Department of Experimental Physics (UCD SCHOOL OF PHYSICS), University College Dublin [Dublin] (UCD), E. O. Hurlburt Center for Space Research, Naval Research Laboratory (NRL), Laboratoire Kastler Brossel (LKB (Jussieu)), Université Pierre et Marie Curie - Paris 6 (UPMC)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute for Nuclear Research [Budapest] (ATOMKI), Hungarian Academy of Sciences (MTA), James S. Cohen, David P. Kilcrease, Stephane Mazevet, Harvard University-Smithsonian Institution, Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
spectroscopy ,Atomic Physics (physics.atom-ph) ,Extreme ultraviolet lithography ,extreme ultra-violet ,FOS: Physical sciences ,x-rays ,microcalorimeter ,Astrophysics ,01 natural sciences ,010305 fluids & plasmas ,Ion ,Physics - Atomic Physics ,Nuclear physics ,[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO] ,Ultraviolet visible spectroscopy ,[PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph] ,[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph] ,0103 physical sciences ,Microelectronics ,[PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det] ,010306 general physics ,Physics ,X-ray spectroscopy ,Quantum Physics ,[PHYS.PHYS.PHYS-ATOM-PH]Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph] ,[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] ,business.industry ,Astrophysics (astro-ph) ,charge exchange ,Physics - Plasma Physics ,Plasma Physics (physics.plasm-ph) ,highly-charged ions ,NIST ,Atomic physics ,Quantum Physics (quant-ph) ,business ,Charge exchange - Abstract
After a brief introduction to the NIST EBIT facility, we present the results of three different types of experiments that have been carried out there recently: EUV and visible spectroscopy in support of the microelectronics industry, laboratory astrophysics using an x-ray microcalorimeter, and charge exchange studies using extracted beams of highly charged ions., 10 pages
- Published
- 2004
9. A low power 12-bit ADC for nuclear instrumentation
- Author
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Eric H. Silver, Norman W. Madden, D.A. Landis, Mark LeGros, and R. Adachi
- Subjects
Reduction (complexity) ,Effective number of bits ,Differential nonlinearity ,CMOS ,Computer science ,12-bit ,Nuclear electronics ,Hardware_INTEGRATEDCIRCUITS ,Electronic engineering ,Successive approximation ADC ,Hardware_ARITHMETICANDLOGICSTRUCTURES ,Power (physics) - Abstract
A low-power, successive-approximation, analog-to-digital converter (ADC) for low-rate, low-cost, battery-powered applications is described. The ADC is based on a commercial 50-mW successive-approximation CMOS device (CS5102). An on-chip self-calibration circuit reduces the inherent differential nonlinearity to 7%. A further reduction of the differential nonlinearity to 0.5% is attained with a four-bit Gatti function. The Gatti function is distributed to minimize battery power consumption. All analog functions reside with the ADC, while the noisy digital functions reside in the personal-computer-based histogramming memory. Fiber-optic cables carry all digital information between the ADC and this memory. >
- Published
- 2003
10. Analysis of broadband x-ray spectra of highly charged krypton from a microcalorimeter detector of an electron-beam ion trap
- Author
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Eric H. Silver, Norman W. Madden, James V. Porto, I Kink, John D. Gillaspy, Jeffrey W. Beeman, Endre Takacs, Nancy Brickhouse, M. Barbera, J. M. Laming, D.A. Landis, E. E. Haller, Simon R. Bandler, Herbert W. Schnopper, S. S. Murray, Kink, I., Laming, J., Takács, E., Porto, J., Gillaspy, J., Silver, E., Schnopper, H., Bandler, S., Barbera, M., Brickhouse, N., Murray, S., Madden, N., Landis, D., Beeman, J., and Haller, E.
- Subjects
Physics ,Detector ,Krypton ,chemistry.chemical_element ,Fizikai tudományok ,Plasma ,Condensed Matter Physic ,Spectral line ,Ion ,Physics and Astronomy (all) ,Settore FIS/05 - Astronomia E Astrofisica ,Természettudományok ,chemistry ,Physics::Atomic Physics ,Ion trap ,Atomic physics ,Electronic band structure ,Mathematical Physics ,Electron beam ion trap ,Statistical and Nonlinear Physic - Abstract
Spectra of highly charged Kr ions, produced in an electron-beam ion trap (EBIT), have been recorded in a broad x-ray energy band (0.3 keV to 4 keV) with a microcalorimeter detector. Most of the spectral lines have been identified as transitions of B- to Al-like Kr. The transition energies have been determined with 0.2% uncertainty. A semi-empirical EBIT plasma model has been created to calculate a synthetic spectrum of highly charged Kr and to determine a charge state distribution of Kr ions inside the EBIT.
- Published
- 2001
11. X–Ray Imaging Spectroscopy Using an NTD Ge-Based Microcalorimeter: An Interdisciplinary Spin-Off from Astrophysics Research
- Author
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E. E. Haller, Eric H. Silver, Edward P. Vicenzi, Jeffrey W. Beeman, C Gilpin, and Ting Lin
- Subjects
Physics ,Imaging spectroscopy ,Nuclear magnetic resonance ,X-ray ,Astrophysics ,Spin (physics) ,Instrumentation - Abstract
Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.
- Published
- 2010
12. Calibration of the Stellar X-Ray Polarimeter
- Author
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Ronald F. Elsner, John A. Tomsick, Eric C. Ford, Paolo Soffitta, Robert Novick, Philip E. Kaaret, Klaus P. Ziock, Eric H. Silver, Martin C. Weisskopf, Enrico Costa, J. Dwyer, and Andrea Santangelo
- Subjects
Physics ,X-ray astronomy ,business.industry ,Thomson scattering ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics::Instrumentation and Methods for Astrophysics ,Polarimetry ,Bragg's law ,Polarimeter ,Polarization (waves) ,law.invention ,Telescope ,Crystal ,Optics ,law ,Astrophysics::Solar and Stellar Astrophysics ,business - Abstract
The Stellar X-Ray Polarimeter (SXRP) will be more than an order of magnitude more sensitive than any previous x-ray polarimeter in the 2-15 keV energy band. The SXRP is a focal plane detector for a Danish-Russian SODART telescope, which will be launched on the Russian Spectrum-X-Gamma (SXG) mission. The SXRP exploits the polarization dependence of Bragg reflection from a graphite crystal, and of Thomson scattering from a target of metallic lithium. The SXRP flight model (FM) was calibrated at a facility at Lawrence Livermore National Laboratory (LLNL) equipped with polarized and unpolarized x-ray sources producing x-rays in the band pass for the graphite and the lithium scatterers. By adjusting the orientation of the SXRP with respect to the incident x-ray beam, it was possible to simulate the converging beam from a SODART telescope and to measure the SXRP response to telescope pointing errors. In this paper we describe the SXRP-FM calibration and present results for the graphite polarimeter.
- Published
- 1997
13. Stellar x-ray polarimeter: polarizer development and calibration at the LEA/LLNL
- Author
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Michael P. Raffanti, Klaus P. Ziock, and Eric H. Silver
- Subjects
Physics ,Scattering ,business.industry ,Optical engineering ,Polarimetry ,X-ray ,Polarimeter ,Polarizer ,Polarization (waves) ,law.invention ,Crystal ,Optics ,law ,business - Abstract
A large area thin graphite crystal and a lithium scattering block are used as the polarization sensitive elements of the Stellar X-Ray Polarimeter. We discuss the construction, selection and characterization of these two polarizing elements. In addition, we describe the plans for calibration of the completed instrument and the facility where it will be conducted.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
- Published
- 1994
14. Fe XVII X-RAY LINE RATIOS FOR ACCURATE ASTROPHYSICAL PLASMA DIAGNOSTICS
- Author
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T. Lin, Joshua M. Pomeroy, Guo-Xin Chen, Eric H. Silver, Nancy Brickhouse, J. M. Laming, J. D. Gillaspy, Joseph N. Tan, and L. Tedesco
- Subjects
Physics ,Atomic Physics (physics.atom-ph) ,Scattering ,FOS: Physical sciences ,Astronomy and Astrophysics ,Electron ,Physics - Plasma Physics ,Spectral line ,Physics - Atomic Physics ,Computational physics ,Ion ,Plasma Physics (physics.plasm-ph) ,Space and Planetary Science ,Astrophysical plasma ,Plasma diagnostics ,Emission spectrum ,Astrophysics - Instrumentation and Methods for Astrophysics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Electron beam ion trap - Abstract
New laboratory measurements using an Electron Beam Ion Trap (EBIT) and an x-ray microcalorimeter are presented for the n=3 to n=2 Fe XVII emission lines in the 15 {\AA} to 17 {\AA} range, along with new theoretical predictions for a variety of electron energy distributions. This work improves upon our earlier work on these lines by providing measurements at more electron impact energies (seven values from 846 to 1185 eV), performing an in situ determination of the x-ray window transmission, taking steps to minimize the ion impurity concentrations, correcting the electron energies for space charge shifts, and estimating the residual electron energy uncertainties. The results for the 3C/3D and 3s/3C line ratios are generally in agreement with the closest theory to within 10%, and in agreement with previous measurements from an independent group to within 20%. Better consistency between the two experimental groups is obtained at the lowest electron energies by using theory to interpolate, taking into account the significantly different electron energy distributions. Evidence for resonance collision effects in the spectra is discussed. Renormalized values for the absolute cross sections of the 3C and 3D lines are obtained by combining previously published results, and shown to be in agreement with the predictions of converged R-matrix theory. This work establishes consistency between results from independent laboratories and improves the reliability of these lines for astrophysical diagnostics. Factors that should be taken into account for accurate diagnostics are discussed, including electron energy distribution, polarization, absorption/scattering, and line blends., Comment: 29 pages, including 7 figures
- Published
- 2011
15. X-ray microcalorimeters with germanium-resistance thermometers
- Author
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Don A. Landis, Eric H. Silver, Simon E. Labov, Eugene E. Haller, Yolanda C. Wai, Timothy E. Pfafman, Jeffrey W. Beeman, Norman W. Madden, and Fred S. Goulding
- Subjects
Materials science ,Physics::Instrumentation and Detectors ,business.industry ,Astrophysics::High Energy Astrophysical Phenomena ,Thermistor ,Analytical chemistry ,chemistry.chemical_element ,Germanium ,Semiconductor device ,Heat capacity ,Particle detector ,law.invention ,Calorimeter ,chemistry ,law ,Optoelectronics ,Resistance thermometer ,Resistor ,business - Abstract
We report on the current status of our work on x-ray microcalorimeters for use as high resolution x-ray spectrometers. To maximize the x-ray collecting area and the signal to noise ratio, the total heat capacity of the device must be minimized. This is best achieved if the calorimeter is divided into two components, a thermal sensor and an x-ray absorber. The thermal sensor is a neutron transmutation doped (NTD) germanium resistor made as small as possible to minimize the heat capacity of the calorimeter. The thermistor can be attached to a thin x-ray absorber with large area and low heat capacity fabricated from superconducting materials such as niobium. We discuss results from our most recent studies of such superconducting absorbers and present the x-ray spectra obtained with these composite microcalorimeters at a temperature of 0. 1 K. An energy resolution of 19 eV FWHM has been measured.
- Published
- 1990
16. Application of kinetic inductance thermometers to x-ray calorimetry
- Author
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Eric H. Silver, Yolanda C. Wai, and Simon E. Labov
- Subjects
Physics ,Noise temperature ,FET amplifier ,business.industry ,Amplifier ,Electrical engineering ,Optoelectronics ,Johnson–Nyquist noise ,Y-factor ,business ,Noise (electronics) ,Low-noise amplifier ,Kinetic inductance - Abstract
A kinetic inductance thermometer is applied to x-ray calorimetry, and its operation over a wide range of fre-quencies and geometries is discussed. Three amplifier configurations are described, one using a superconducting quantum int.erference device (SQUID) amplifier, another incorporating an FET amplifier in an amplitude modulated system, and the third, using a tunnel diode frequency modulated oscillator circuit. The predicted performance of each configuration is presented. 1. INTRODUCTIONWe are interested in fabricating bmad band x-ray detectors operating between 0.1 and 10 keY with thehighest achievable energy resolution. In principle, x-ray microcalorimeters operating at cryogenic temperaturesshould be able to cover this energy band with a 1 eV resolution.1'2 To date, 12 eV has been achieved using resis-tive sensors thermally connected to an x-ray absorbing material.3 In these devices, the resistive Johnson noise ofthe sensor is always present and is a limitation to the overall performance. To further improve the resolution of thedevice, the Johnson noise must be reduced. If the Johnson and amplifier noise can be reduced, the temperaturefluctuation noise will dominate the noise spectrum over a much larger range in frequencies. Experiments arecurrently being carried out with calorimeters using dielectric sensors.4 In principle, dielectric calorimeters are freeof Johnson noise, and produce signal strengths far above the remaining amplifier noise. Another way to circumventJohnson noise is through the use of superconducting materials. Below the critical temperature, only the residualresistance from superconducting surfaces need to be considered, and they prove to be negligible.5 As suggested byMcDonald,6 the temperature dependence of the kinetic inductance in a superconducting thin film can be utilized as
- Published
- 1990
17. Test results of a prototype dielectric microcalorimeter
- Author
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Jeffrey W. Beeman, Fred S. Goulding, Timothy E. Pfafman, Norman W. Madden, Eric H. Silver, Don A. Landis, W. L. Hansen, and Simon E. Labov
- Subjects
Materials science ,Spectrometer ,chemistry ,Analytical chemistry ,Measuring instrument ,Niobium ,chemistry.chemical_element ,Dielectric ,Alpha particle ,Capacitance ,Ferroelectricity ,Particle detector - Abstract
The initial development work on a dielectric microcalorimeter is presented. It focuses on the dielectric properties of the ferroelectric material KTa(1-x)Nb(x)O3 (KTN). Measurements of the temperature dependent dielectric constant are given together with the first alpha particle detection results from a prototype composite microcalorimeter operating at 1.3 K. A nonthermal mechanism for detecting 6 MeV alpha particles in a monolithic KTN sample is also reported.
- Published
- 1990
18. X-ray transitions in highly charged neonlike ions
- Author
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Manfred Bitter, K. W. Hill, A. Wouters, Daniel D. Dietrich, Gerassimenko M, von Goeler S, J Felt, Szymon Suckewer, P. Beiersdorfer, James H. Scofield, J. Timberlake, Einar Hinnov, J. E. Stevens, S. Bernabei, R. S. Walling, Mau Hsiung Chen, R. Bell, Peter L. Hagelstein, R. Hulse, and Eric H. Silver
- Subjects
Physics ,Dipole ,Cover (topology) ,Atomic electron transition ,Atomic number ,Type (model theory) ,Atomic physics ,Energy (signal processing) ,Spectral line ,Charged particle - Abstract
Wavelength measurements of n=3 to n=2 transitions in neonlike ${\mathrm{Xe}}^{44+}$, ${\mathrm{La}}^{47+}$, ${\mathrm{Nd}}^{50+}$, and ${\mathrm{Eu}}^{53+}$ have been made using a high-resolution Bragg-crystal spectrometer on the Princeton Large Torus tokamak. The measurements cover the wavelength regions 2.00--3.00 A\r{} and include the electric dipole and the electric and magnetic quadrupole transitions. The measured wavelengths are compared to energy levels obtained from a multiconfigurational Dirac-Fock calculation. Systematic differences between the experimental and theoretical values are found, which vary smoothly with atomic number. The magnitude of the differences depends on the particular type of transition and ranges from -2.8 eV to +2.2 eV. Inclusion of electron correlation corrections due to ground-state correlations and (super-) Coster-Kronig-type fluctuations in the theoretical energies is shown to reduce the differences for some but not all types of transitions.
- Published
- 1988
19. Observations of giant recombination edges on PLT tokamak induced by particle transport
- Author
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S. von Goeler, R. D. Cowan, N. R. Sauthoff, Manfred Bitter, D. Eames, W. Stodiek, K. Brau, Eric H. Silver, and K. W. Hill
- Subjects
Physics ,Tokamak ,Argon ,Bremsstrahlung ,chemistry.chemical_element ,Plasma ,Electromagnetic radiation ,Particle transport ,law.invention ,Nuclear physics ,chemistry ,Impurity ,law ,Atomic physics ,Recombination - Published
- 1980
20. Low energy x-ray emission from magnetic fusion plasmas
- Author
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S. von Goeler, Eric H. Silver, Manfred Bitter, K. W. Hill, N. R. Sauthoff, and D. Eames
- Subjects
Physics ,Radiative cooling ,Impurity ,Electron temperature ,Plasma diagnostics ,Electron ,Atomic physics ,Electromagnetic radiation ,Spectral line ,Ion - Abstract
Complex, transient, spatially inhomogeneous tokamak plasmas require careful diagnosis. As the reactor regime is approched, soft x rays become more important as a versatile diagnostic tool and an energy‐loss mechanism. Continuum emission provides a measure of electron temperatures and light impurity content. Impurity lines serve as a probe for ion and electron temperature, impurity behavior, and radiative cooling. The entire spectrum yields vital information on instabilities and disruptions. The importance of impurities is illustrated by the extensive efforts toward understanding impurity production, effects, and control. Minute heavy impurity concentrations can prevent reactor ignition. Si(Li)‐detector arrays give a broad overview of continuum and line x‐ray emission (.3−50 keV) with moderate energy (200 eV) and time (50 ms) resolution. Bragg crystal and grating spectrometers provide detailed informaion on impurity lines with moderate to excellent (E/ΔE=100−23,000) resolving power and 1−50 ms time resolution. Imaging detector arrays measure rapid (∼10 μs) fluctuations due to MHD instabilities and probe impurity behavior and radiative cooling. Future tokamaks require more diagnostic channels to avoid spatial scanning; higher throughput for fast, single‐shot diagnosis; increased spectral information per sample period via fast scanning or use of multi‐element detectors with dispersive elements; and radiation shielding and hardening of detectors.
- Published
- 1981
21. Laboratory astrophysics survey of key x-ray diagnostic lines using a microcalorimeter on an electron beam ion trap
- Author
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I Kink, Herbert W. Schnopper, Simon R. Bandler, Endre Takacs, S. S. Murray, Nancy Brickhouse, James V. Porto, John D. Gillaspy, D.A. Landis, Marco Barbera, Eric H. Silver, Jeffrey W. Beeman, J. M. Laming, Norman W. Madden, Eugene E. Haller, Silver, E, Schnopper, H, Bandler, S, Brickhouse, N, Murray, S, Barbera, M, Takacs, E, Gillaspy, J, Porto, J, Kink, I, Laming, J, Madden, N, Landis, D, Beeman, J, and Haller, E
- Subjects
Physics::Instrumentation and Detectors ,Astrophysics::High Energy Astrophysical Phenomena ,chemistry.chemical_element ,Fizikai tudományok ,Astrophysics ,Spectral line ,Neon ,Természettudományok ,Atomic processe ,Ionization ,Physics::Atomic Physics ,Atomic data ,Nuclear and High Energy Physic ,Physics ,Argon ,Krypton ,Astronomy and Astrophysics ,Line: Identification ,Plasma ,X-rays: General ,chemistry ,Space and Planetary Science ,Astrophysical plasma ,Methods: Laboratory plasma ,Atomic physics ,Electron beam ion trap - Abstract
Cosmic plasma conditions created in an electron beam ion trap (EBIT) make it possible to simulate the dependencies of key diagnostic X-ray lines on density, temperature, and excitation conditions that exist in astrophysical sources. We used a microcalorimeter for such laboratory astrophysics studies because it has a resolving power ≈1000, quantum efficiency approaching 100%, and a bandwidth that spans the X-ray energies from 0.2 keV to 10 keV. Our microcalorimeter, coupled with an X-ray optic to increase the effective solid angle, provides a significant new capability for laboratory astrophysics measurements. Broadband spectra obtained from the National Institute of Standards and Technology EBIT with an energy resolution approaching that of a Bragg crystal spectrometer are presented for nitrogen, oxygen, neon, argon, and krypton in various stages of ionization. We have compared the measured line intensities to theoretical predictions for an EBIT plasma.
22. The graphite crystal X-ray spectrometer on OSO-8
- Author
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Eric H. Silver, G. G. Cohen, Richard S. Wolff, Martin C. Weisskopf, Robert Novick, K. S. Long, and H. L. Kestenbaum
- Subjects
Physics ,X-ray astronomy ,X-ray spectroscopy ,Spectrometer ,business.industry ,Astrophysics::High Energy Astrophysical Phenomena ,Bragg's law ,Astronomy and Astrophysics ,Astronomical spectroscopy ,Optics ,Space and Planetary Science ,Graphite ,Electronic band structure ,business ,Equivalent width - Abstract
The large-area graphite crystal X-ray spectrometer aboard the OSO-8 satellite is described. The instrument can be used to measure continuum profiles over the energy band from 2 to 8 keV with a resolution of several tens of electron volts and to detect narrow line emission from strong X-ray sources with a limiting sensitivity (3 sigmas) of the order of 10-eV, equivalent width for a three-day observing period.
- Published
- 1976
23. The first search for X-ray polarization in the Centaurus X-3 and Hercules X-1 pulsars
- Author
-
Robert Novick, K. S. Long, Eric H. Silver, Richard S. Wolff, Martin C. Weisskopf, and H. L. Kestenbaum
- Subjects
Physics ,Neutron star ,Pulsar ,Space and Planetary Science ,Linear polarization ,Binary star ,Astronomy ,Astronomy and Astrophysics ,Astrophysics ,Light curve ,Polarization (waves) ,Electromagnetic radiation ,Stellar evolution - Abstract
The first search for X-ray polarization in the Cen X-3 and Her X-1 pulsars was performed by the OSO 8 polarimeters in 1975 July and 1975 August, respectively. Three-sigma upper limits to the polarization in Cen X-3 of 13.5% and 19% at 2.6 keV and 5.2 keV, respectively, were obtained when the data were averaged over the pulse and binary periods. The upper limit for Her X-1 at 2.6 keV is 60%. A search for pulse-phase dependent X-ray polarization from both objects was also performed. At the 91% confidence level, emission from Cen X-3 exhibits evidence for X-ray polarization at 2.6 keV that varies with pulse phase. Upper limits to polarization are presented for the leading and trailing edges and peak of the Her X-1 pulse at 2.6 keV.
- Published
- 1979
24. Search for X-ray polarization in Cygnus X-1
- Author
-
Eric H. Silver, H. L. Kestenbaum, Martin C. Weisskopf, Robert Novick, Richard S. Wolff, and K. S. Long
- Subjects
Physics ,Space and Planetary Science ,Binary star ,X-ray ,Astronomy and Astrophysics ,Astrophysics ,Polarization (waves) ,Confidence interval ,Positive evidence - Abstract
Cygnus X-1 was observed at 2.6 and 5.2 keV during a three-day period in November 1975 by the X-ray polarimeters on the OSO-8 satellite. At the 99% confidence level, the results are consistent with the source being unpolarized. Positive evidence for polarization at 2.6 keV was obtained at the 96% confidence level.
- Published
- 1977
25. Measurement of X-ray iron line emission from Cygnus X-3 with the OSO 8 crystal spectrometer
- Author
-
K. S. Long, H. L. Kestenbaum, W. H. M. Ku, Eric H. Silver, and Robert Novick
- Subjects
Physics ,Spectrometer ,Space and Planetary Science ,Ionization ,X-ray ,Astronomy and Astrophysics ,Emission spectrum ,Atomic physics ,Equivalent width ,Spectral line ,Line (formation) ,Ion - Abstract
X-ray Fe line emission from Cyg X-3 was detected at an energy of 6.52 +- 0.08 keV with the graphite crystal spectrometer on OSO 8. The measured line energy indicates emission from moderately ionized Fe with a line strength of 0.0097 +- 0.0043 photons (cm/sup 2/ s)/sup -1/, corresponding to an equivalent width of 220 +- 100 eV. 2 figures, 2 tables.
- Published
- 1978
26. Further comments on the effects of vacuum birefringence on the polarization of X-rays emitted from magnetic neutron stars
- Author
-
Robert Novick, Gary Chanan, and Eric H. Silver
- Subjects
Physics ,Birefringence ,Linear polarization ,Astrophysics::High Energy Astrophysical Phenomena ,Astronomy and Astrophysics ,Astrophysics ,Polarization (waves) ,Electromagnetic radiation ,Magnetic field ,symbols.namesake ,Neutron star ,Space and Planetary Science ,symbols ,Stokes parameters ,Cyclotron radiation ,Atomic physics - Abstract
The birefringence of the vacuum in the presence of strong (of the order of 1 teragauss) magnetic fields will in general affect the polarization of X-rays propagating through these fields. Two of the four Stokes parameters will vary so rapidly with wavelength as to be 'washed out' and unobservable, but the remaining two parameters will be unaffected. These results show that one conclusion of an earlier work is incorrect: Polarized X-ray emission from the surface of a magnetic neutron star will not in general be completely depolarized by the effects of vacuum birefringence. In particular, this birefringence has no effect on the linear polarization of cyclotron emission from the poles of magnetic neutron stars, and a similar result holds for synchrotron emission. More general cases of the propagation of polarized X-rays in magnetic fields are also discussed.
- Published
- 1979
27. Search for X-ray line emission from A0620-00
- Author
-
Richard S. Wolff, Martin C. Weisskopf, H. L. Kestenbaum, Robert Novick, K. S. Long, Eric H. Silver, and G. G. Cohen
- Subjects
Physics ,Space and Planetary Science ,Continuum (design consultancy) ,X-ray ,Astronomy and Astrophysics ,Astrophysics ,Emission spectrum ,Plasma ,Atomic physics ,Electromagnetic radiation ,Spectral line ,Ion ,Line (formation) - Abstract
Measurements of the X-ray spectrum (1.85-7 keV) of A0620-00 obtained on 1975 October 17 and 1976 January 1-9 with the graphite crystal spectrometer on OSO-8 show a smooth continuum with an absence of emission lines. Upper limits are given for line emission from Si and S ions and are used to establish that the source is not optically thin. The results support a dense plasma model.
- Published
- 1976
Catalog
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