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Using a scanning modulation collimator, the optical identification of X-ray sources by means of precise positioning was carried out. Two galactic identifications (4U2129+47 and 2A0311-227) and two extragalactic identifications (NGC 526a and Parkes H2155-304) are described.
The main source of attenuation which will be studied is the optical fiber's sensitivity to bending at radii that are much larger than the radius of the fiber. This type of environmental attenuation causes losses that are a function of the severity of the bend. The average attenuation caused by bending varies exponentially with the bend radius. There are many different fibers, sources, and testing equipment available. This thesis describes tests that were performed to evaluate the variables that effect bending related attenuation and will discuss the consistency of the results. Descriptions and comparisons will be made between single mode and multimode fibers as well as instrumentation comparisons between detection equipment. Detailed analysis of the effects of the whispering gallery mode will be performed along with theorized methods for characterization of these modes.
Methods, systems and apparatus for generating atomic traps, and for storing, controlling and transferring information between first and second spatially separated phase-coherent objects, or using a single phase-coherent object. For plural objects, both phase-coherent objects have a macroscopic occupation of a particular quantum state by identical bosons or identical BCS-paired fermions. The information may be optical information, and the phase-coherent object(s) may be Bose-Einstein condensates, superfluids, or superconductors. The information is stored in the first phase-coherent object at a first storage time and recovered from the second phase-coherent object, or the same first phase-coherent object, at a second revival time. In one example, an integrated silicon wafer-based optical buffer includes an electrolytic atom source to provide the phase-coherent object(s), a nanoscale atomic trap for the phase-coherent object(s), and semiconductor-based optical sources to cool the phase-coherent object(s) and provide coupling fields for storage and transfer of optical information.
We describe an upgraded fiber-optic sensor system and its performance in measuring the dynamic strains in a mercury target of the Spallation Neutron Source (SNS). Strains result from dynamic pressure waves in the stainless-steel mercury target induced by short (~700 ns), intense (up to 23.3 kJ), high-energy (~1 GeV) proton pulses. In the upgraded sensor system, the output of each sensor head is interrogated with a compact, all-fiber based Faraday Michelson interferometer, which generates interference signals with a steady phase shift. Strain waveforms are recovered from the phase-shifted interference signals using a high-speed digital signal processing procedure developed in our previous work. We demonstrate successful measurements of dynamic strain pulses, e.g., 400με over 190μs , on a recently installed SNS target using the upgraded sensor system. The measured strain waveforms are analyzed for more than 20 sensor locations and/or orientations, and provide information regarding the temporal structure of strain profiles and dependence of the strain magnitude on the proton powers of 200 – 1400 kW. The new interrogator also measures the radiation-induced-attenuation (RIA) in the optical fiber, enabling experimental investigations of RIA profiles induced by a 700-ns radiation pulse. The radiation effects on the strain measurement performance are discussed over a radiation dose range of up to 4×10 8 Gy and an RIA compensation method is proposed. The measurements allow insight into the response of this unique piece of equipment and can be used for validation of simulations.
High time-resolution photometry of the proposed optical counterpart (Star 30) of the X-ray source 2S1254-690 is reported here. An event of high statistical significance was observed from the star that has all the temporal characteristics of an X-ray burst (see, for example, ref. 3). 2S1254-690 has not previously been identified as an X-ray burst source, but its optical counterpart shows properties in common with this class of objects. We also derive the X-ray spectrum of 2S1254-690 using data obtained with the HEAO 1 satellite. The spectrum can be fit in the energy range 0.18-30 keV by a power law of photon index -2.5, modified by interstellar absorption.
The newly constructed time-resolved atomic, molecular and optical science instrument (TMO) is configured to take full advantage of both linear accelerators at SLAC National Accelerator Laboratory, the copper accelerator operating at a repetition rate of 120 Hz providing high per-pulse energy as well as the superconducting accelerator operating at a repetition rate of about 1 MHz providing high average intensity. Both accelerators power a soft X-ray free-electron laser with the new variable-gap undulator section. With this flexible light source, TMO supports many experimental techniques not previously available at LCLS and will have two X-ray beam focus spots in line. Thereby, TMO supports atomic, molecular and optical, strong-field and nonlinear science and will also host a designated new dynamic reaction microscope with a sub-micrometer X-ray focus spot. The flexible instrument design is optimized for studying ultrafast electronic and molecular phenomena and can take full advantage of the sub-femtosecond soft X-ray pulse generation program.
A fiber optic microphone is provided for measuring fluctuating pressures. An optical fiber probe having at least one transmitting fiber for transmitting light to a pressure-sensing membrane and at least one receiving fiber for receiving light reflected from a stretched membrane is provided. The pressure-sensing membrane may be stretched for high frequency response. Further, a reflecting surface of the pressure-sensing membrane may have dimensions which substantially correspond to dimensions of a cross section of the optical fiber probe. Further, the fiber optic microphone can be made of materials for use in high temperature environments, for example greater than 1000 F. A fiber optic probe is also provided with a back plate for damping membrane motion. The back plate further provides a means for on-line calibration of the microphone.
Results of a photographic and spectrophotometric search to a limiting B magnitude of approximately 18.5 for the optical counterparts of nine galactic X-ray sources with good positions are reported. The sources included in this survey are 3U 1709-23, 1728-16, 1728-24, 1758-20, 1758-25, 1811-17, 1813-14, 1837+04, 1908+00. Optical candidates for six of these sources are discussed, including blue objects which may be the optical counterparts of 1709-23 and 1728-16, a distant B star near 1908+00, and a very unusual strong-emission-line object which is probably associated with 1728-24 (GX 2+5). Coordinates, magnitudes, colors, spectral data, and finding charts are presented.
The results of a program of optical identification of the X-ray point sources in the direction of the Large Magellanic Cloud (LMC) are presented. Observational results are combined with accurate positions of about 3-arcsec obtained with the Einstein Observatory Imaging Proportional Counter (IPC). The sources include 13 foreground stars, three background active galaxies, and six LMC members which are known or suspected to be binaries. The 24 other sources in the Einstein LMC survey have only 30-arcsec positions and on average are less luminous and in more crowded regions of the LMC. On the basis of the new identifications, comparisons are made between the overall stellar X-ray population in the LMC and in the Galaxy. Although the mean X-ray luminosity of the LMC sources is significantly higher than that of the Galaxy, the total number of stellar X-ray systems per unit mass is similar in the LMC and the Galaxy.
There are a number of sources of scattering in binary optics: etch depth errors, line edge errors, quantization errors, roughness, and the binary approximation to the ideal surface. These sources of scattering can be systematic (deterministic) or random. In this paper, scattering formulas for both systematic and random errors are derived using Fourier optics. These formulas can be used to explain the results of scattering measurements and computer simulations.
Deterministic sources of high-fidelity entangled qubit pairs encoded in the dual-rail photonic basis, i.e., presence of a single photon in one of two orthogonal modes, are a key enabling technology of many applications of quantum information processing, including high-rate, high-fidelity quantum communications over long distances. The most popular and mature sources of such photonic entanglement, e.g., those that leverage spontaneous parametric down-conversion (SPDC) or spontaneous four-wave mixing, generate an entangled (so-called continuous-variable) quantum state that contains contributions from high-order photon terms that lie outside the span of the dual-rail basis, which is detrimental to most applications. One often uses low pump power to mitigate the effects of those high-order terms. However, that reduces the pair generation rate, and the source becomes inherently probabilistic. We investigate a cascaded source that performs a linear-optical entanglement swap between two SPDC sources, to generate a heralded photonic entangled state that has a higher fidelity (to the ideal Bell state) compared to a free-running SPDC source. Furthermore, with the Bell swap providing a heralding trigger, we show how to build a multiplexed source, which despite reasonable switching losses and detector loss and noise, yields a fidelity versus success probability trade-off of a high-efficiency source of high-fidelity dual-rail photonic entanglement. We find, however, that there is a threshold of 1.5 dB of loss per switch, beyond which multiplexing hurts the fidelity versus success probability trade-off.
The blazar J1924–2914 is a primary Event Horizon Telescope (EHT) calibrator for the Galactic center’s black hole Sagittarius A*. Here we present the first total and linearly polarized intensity images of this source obtained with the unprecedented 20 μas resolution of the EHT. J1924–2914 is a very compact flat-spectrum radio source with strong optical variability and polarization. In April 2017 the source was observed quasi-simultaneously with the EHT (April 5–11), the Global Millimeter VLBI Array (April 3), and the Very Long Baseline Array (April 28), giving a novel view of the source at four observing frequencies, 230, 86, 8.7, and 2.3 GHz. These observations probe jet properties from the subparsec to 100 pc scales. We combine the multifrequency images of J1924–2914 to study the source morphology. We find that the jet exhibits a characteristic bending, with a gradual clockwise rotation of the jet projected position angle of about 90° between 2.3 and 230 GHz. Linearly polarized intensity images of J1924–2914 with the extremely fine resolution of the EHT provide evidence for ordered toroidal magnetic fields in the blazar compact core.
X-ray sources are reported for HZ Herculis, supergiant primary X-ray binary systems, and Cyg X-3. Also reported is an analysis of earlier optical and X-ray observations, along with optical coverage of the 1974 lunar occulation of the Crab Nebula.
The results are reported of submillisecond white-light optical photometry of the X-ray source GX 339-4 obtained over the years 1985-1988 at the Las Campanas Observatory and Cerro Tololo Inter-American Observatory. A coherent, df/f less than 0.025, 5.25 mHz feature with pulsed amplitude up to 50 percent is found which persisted for about 20-30 cycles. The feature only appeared in data taken in July 5, 1986 UT. The 885 Hz feature proposed by Imamura et al. (1990) was not detected at 90-percent-confidence upper limits of 2 percent pulsed emission. The 885 Hz feature was reported by Imamura et al. to have a pulsed amplitude of 2.3-2.4 percent. The proposed 0.2 mag, 0.618 day orbital variation proposed by Honey et al. (1988) could not be verified due to the length of the data strings.
A pulse-counting mass spectrometer is described which is comprised of a new ion source of cylindrical geometry, with exceptional optical properties (the Baur source), a dual focal plane externally adjustable collector slits, and a 17-stage Allen-type electron multiplier, all housed in a metal 21 cm radius, 90 deg magnetic sector flight tube. Mass discrimination of the instrument is less than 1 per mil per mass unit; the optical transmission is more than 90%; the source sensitivity (Faraday collection) is 4 ma/torr at 250 micron emission; and the abundance sensitivity is 30,000.
The data from a recently completed survey of the galactic plane with the SAS-3 modulation collimators provide precise (20 to 60 arcsec) celestial positions of galactic X-ray sources. Preliminary positions of 60-arcsec precision are reported for five sources. One of these led to the identification of the star, Gamma Cas, as an X-ray source, and the others lend substantial confidence to previously proposed optical identifications: 3U 0352+30 = X Per, 3U 1145-61 = HEN 715, GX301-2 = WRA977, and GX304-1 = MMV star. These identifications seem to establish the existence of a previously suggested class of Be-star X-ray emitters.
The potential usefulness of the constrained sheath optics concept as a means of controlling the divergence of low energy, high current density ion beams is examined numerically and experimentally. Numerical results demonstrate that some control of the divergence of typical ion beamlets can be achieved at perveance levels of interest by contouring the surface of the constrained sheath properly. Experimental results demonstrate that a sheath can be constrained by a wire mesh attached to the screen plate of the ion optics system. The numerically predicted beamlet divergence characteristics are shown to depart from those measured experimentally, and additional numerical analysis is used to demonstrate that this departure is probably due to distortions of the sheath caused by the fact that it attempts to conform to the individual wires that make up the sheath constraining mesh. The concept is considered potentially useful in controlling the divergence of ion beamlets in applications where low divergence, low energy, high current density beamlets are being sought, but more work is required to demonstrate this for net beam ion energies as low as 5 eV.
Precision synchronization is vital for robust long-distance quantum networking over fiber and free-space channels for which high-fidelity entanglement swapping between separate sources via an optical Bell state measurement requires temporal overlap of photonic qubits arriving from either source. This challenge is particularly distinct in satellite-based entanglement distribution in which relative motion, channel effects, and propagation delay must be addressed. This work presents a precision synchronization method for free space entanglement distribution, and reports on risk reduction testing in a quantum networking testbed at MIT Lincoln Laboratory. Primary consideration is for a dual-uplink architecture in which photons from entanglement sources at two ground locations interact in an optical Bell-state measurement implemented on a satellite in a low-earth orbit. The control approach uses independent entanglement sources at each ground location supplemented with a synchronization signal for feedback control from a timing discriminant measured at the spacecraft. The approach is being implemented in a laboratory testbed using 1-GHz repetition rate 1550-nm band entanglement sources generating ~10-MHz source entanglement rates with few-ps photon pulse lengths. The paper describes both fundamental architectural considerations and practical implementation details.