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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRSDate not supplied

Modeling and simulation of space-based entanglement distribution

In this talk we present a model for analyzing space-based entanglement distribution links. In particular, we analyze deterministic entanglement distribution links relevant to quantum communication applications where all communication nodes must be synchronized with deterministic photon arrival times. The focus is on systems operating within practical limitations set by current technology. The architectures studied in this work are based on all-photonic links with probabilistic (memory-less) entanglement swapping used to signal the success of the entanglement distribution without destroying the entangled state. An end-to-end link model is described which accounts for satellite orbital mechanics as well as the physical effects of entangled photon pair sources, space-to-ground atmospheric channels, two-photon interference, pointing and tracking, and photon counting detectors with and without photon number resolution (this is joint work with Robert Manning, Ian Nemitz, and Bryan Welch).

quantum communication↗
NASA NTRS2015

High-Fidelity Down-Conversion Source for Secure Communications Using On-Demand Single Photons

AdvR, Inc., has built an efficient, fully integrated, waveguide-based source of spectrally uncorrelated photon pairs that will accelerate research and development (R&D) in the emerging field of quantum information science. Key to the innovation is the use of submicron periodically poled waveguides to produce counter propagating photon pairs, which is enabled by AdvR's patented segmented microelectrode poling technique. This novel device will provide a high brightness source of down-conversion pairs with enhanced spectral properties and low attenuation, and it will operate in the visible to the mid-infrared spectral region. A waveguide-based source of spectrally and spatially pure heralded photons will contribute to a wide range of NASA's advanced technology development efforts, including on-demand single photon sources for high-rate spaced-based secure communications.

Roberts, Tony↗
NASA NTRS2019

PAH Products and Processing by Different Energy Sources

Isoviolanthrene (C34H18), a polycyclic aromatic hydrocarbon (PAH) molecule, was studied via matrix isolation in argon and water at 20 K. Infrared spectroscopy was performed in situ where samples were irradiated using ultraviolet light. Experimental spectra were compared to theoretical spectra for vibrational band assignment, determination of the corresponding A-values, and photoproduct identification. Isoviolanthrene was also deposited as a thin film and irradiated with different energy sources: ultraviolet photons (10.2 eV), soft electrons (1.5 keV), protons (1.5 MeV), and He+ particles (1.5 MeV), to understand the effects of different energy sources on a PAH. Anions and cations of soviolanthrene were produced as a result of UV photolysis in an argon matrix. Hydrogenand oxygen-rich aromatic photoproducts were produced by ultraviolet photons when isoviolanthrene was isolated in a water matrix. The irradiated PAH thin films results were dependent on the energy source. Irradiation with ultraviolet photons yielded a broad underlying feature centered at 9.6 μm, while bombardment with soft electrons gave a broad feature centered at 7.7 μm. In the case of proton bombardment, no broad feature was detected, in contrast with He+ bombardment that destroyed most of the isoviolanthrene and produced broad features in the C-Hoop and C–H stretching regions. A comparison of astronomical IR emission observations with our experimental results in the mid-infrared range has revealed a similarity between the observed plateaus and the broad features produced by our experiments.

astrochemistry – infrared: ISM – methods: laborato↗
NASA NTRS1986

One- and two-photon Compton scattering in strong magnetic fields

Calculations are made of the Compton scattering cross section in a very strong magnetic field, such as encountered in pulsars, for arbitrary photon and electron energies. The effect of the vacuum polarization in the weak-field limit is included as well as the plasma polarizability. Radiative transitions between any pair of Landau levels are included as well as two-photon scattering. The latter process, due to the presence of the cyclotron resonance, becomes comparable to nonresonant one-photon scattering when excited final states are allowed, and acts as a source of photons which is more important than bremsstrahlung at low plasma densities.

Bussard, R. W.↗
NASA NTRS1989

Scanning Photoelectron-Emission Inspection Equipment

Surfaces to be bonded tested for cleanliness. Equipment includes commercial photoelectron-emission sensor. Inspected surface irradiated with ultraviolet photons from source in sensor head while anode in sensor head collects photoelectrons ejected from surface by absorbed photons. If intensity and spectrum of ultraviolet light and distance between sensor and surface held constant, then photocurrent varies according to amount and type of contamination.

Gause, Raymond L.↗
NASA NTRS1983

Electron-photon coincidence technique for the absolute calibration of VUV detectors

A method is described whereby VUV photon detectors can be accurately calibrated. This method is illustrated by taking the 58.4-nm transition of He as an example. The technique consists of crossing a monoenergetic electron beam with a beam of He atoms. When inelastically scattered electrons which have excited the 2 1P state are detected in coincidence with the 58.4-nm photons emitted in the decay of the excited state, the interaction volume formed by the crossed beams constitutes a standard source of photons. By comparing the number of detected coincidences with the predicted number the calibration can be made. A total detector efficiency of 0.024 + or - 0.003 is obtained for a Galileo 4830 channeltron.

Mcadams, R.↗
NASA NTRS1994

An Optics Free Spectrometer for the Extreme Ultraviolet

The optics-free spectrometer is a photon spectrometer. It provides the photon spectrum of a broadband source by converting photons of energy E into electrons of energy E', according to the Einstein relation, E' = E - Ei. E, is the ionization threshold of the gas target of interest (any of the rare gases are suitable) and E is the incoming photon energy. As is evident from the above equation, only a single order spectrum is produced throughout the energy range between the first and second ionization potentials of the rare gas used. Photons with energy above the second ionization potential produce two groups of electrons, but they are readily distinguished from each other. This feature makes this device extremely useful for determining the true spectrum of a continuum source or a many line source. The principle of operation and the laboratory results obtained with a representative configuration of the optics-free spectrometer are presented.

Judge, D. L.↗
NASA NTRS1985

Some evidence for large gravitational redshift in Seyfert galaxy NGC 4151

The photon spectra of two Seyfert galaxies NGC 4151 and MCG 8-11-11 are good experimentally established in the X-ray and gamma range. The annihilation of the high temperature positrons with cold electrons is proposed as the possible mechanism of photon production in the Seyfert galaxy NGC 4151. The photon spectrum of NGC 4151 with its observed features from the soft X to the gamma ray range is described by annihilation of positrons and electrons at temperatures 3 x 10 to the 12th power K and 10 to the 8th power K respectively. The photon spectra from annihilation of unthermalized plasma with above parameters should be shifted to the lower energy by redshift z = 100. In that case the source of photons should be placed closely to the black hole horizon (r approximately equal to 1.0001 r sub g.

Tkaczyk, W.↗
NASA NTRS2001

A Possible X-Ray and Radio Counterpart of the High-Energy Gamma-Ray Source 3EG J2227+6122

The identity of the persistent EGRET sources in the Galactic plane is largely a mystery. For one of these, 3EG J2227+6122, our complete census of X-ray and radio sources in its error circle reveals a remarkable superposition of an incomplete radio shell with a flat radio spectrum, and a compact, power-law X-ray source with photon index Gamma = 1.5 and with no obvious optical counterpart. The radio shell is polarized at a level of approx. = 25%. The anomalous properties of the radio source prevent us from deriving a completely satisfactory theory as to its nature. Nevertheless, using data from ROSAT, ASCA, the VLA, and optical imaging and spectroscopy, we argue that the X-ray source may be a young pulsar with an associated wind-blown bubble or bow shock nebula, and an example of the class of radio-quiet pulsars which are hypothesized to comprise the majority of EGRET sources in the Galaxy. The distance to this source can be estimated from its X-ray absorption as 3 kpc. At this distance, the X-ray and gamma-ray luminosities would be approx. = 1.7 x 10(exp 33) and approx. = 3.7 x 10(exp 35) erg/s, respectively, which would require an energetic pulsar to power them. If, on the contrary, this X-ray source is not the counterpart of 3EG J2227+6122, then by process of elimination the X-ray luminosity of the latter must be less than 10(exp -4) of its gamma-ray luminosity, a condition not satisfied by any established class of gamma-ray source counterpart. This would require the existence of at least a quantitatively new type of EGRET source, as has been suggested in studies of other EGRET fields.

Halpern, Jules P.↗
NASA NTRS1987

Performance measurements of a diode laser optical communications link with Q = 4 PPM signaling

The theoretical and measured performance characteristics of a direct detection optical communication system are reported. The system consisted of a semiconductor diode laser, silicon avalanche photodiode detector, and used Q = 4 optical pulse position modulation signaling to transmit binary source data at a rate of 25 megabits/sec. Operation at a receiver bit error probability of 10 to the -6th was demonstrated at received signal energies corresponding to an average of 160 detected photons per PPM symbol, or 80 photons per source bit.

Sun, X.↗
NASA NTRS1987

A search for X-ray emission from a nearby pulsar - PSR 1929 + 10

Observations of the radio pulsar PSR 1929 + 10 with the Exosat observatory are reported. A 2 sigma upper limit of 0.0005 cts/s was obtained in the 0.04-2.4 keV range, which translates into a luminosity upper limit of 2 x 10 to the 29th erg/s for a power-law source with photon number index 1-3, and a luminosity upper limit of 10 to the 30th erg/s corresponding to a temperature of 190,000 K for a blackbody with radius 10 km. The implications of these upper limits for various models and their compatibility with the positive detection of this source by the Einstein Observatory are discussed.

Alpar, A.↗
NASA NTRS1979

Direct energy inputs to the middle atmosphere

As a working definition of the extent of the middle atmosphere (MA), the height range from 30 to 100 km was adopted. The neutral and ionic composition and the dynamics within this height range are, for the most part, poorly understood. From available information, the importance of various particle and photon energy sources, including their variability, for ionization of the neutral atmosphere in this height range is assessed. The following topics are discussed: (1) penetration of the MA by particle and electromagnetic energy; (2) ionization sources for the MA; (3) galactic cosmic rays; (4) solar H Ly alpha, other EUV, and X-rays; (5) magnetospheric electrons and bremsstrahlung X-rays; and (6) solar cosmic rays.

Rosenberg, T. J.↗
NASA NTRS1983

Influence of radiative recombination on the minority-carrier transport in direct band-gap semiconductors

When a semiconductor sample is irradiated by means of an external source, emitting photons or electrons, excess carriers are produced which distribute themselves throughout the sample. One of the parameters which determine the distribution of the carriers is the surface recombination velocity. The present investigation is concerned with the recombination lifetime tau. The predominant mechanism for recombination in wide band-gap semiconductors is described by the Shockley-Read-Hall (SRH) theory. The transport equations are derived for free carriers and the radiation field. The considered theory is applied to a semiinfinite, one-dimensional semiconductor slab irradiated by light of a given frequency. Some numerical considerations based on n-type GaAs are presented. Attention is given to a determination of the radiation transmitted through the surface of the sample.

Von Roos, O.↗
NASA NTRS1986

A densitometric analysis of IIaO film flown aboard the space shuttle transportation system STS-3, STS-8, and STS-7

Three canisters of IIaO film were prepared along with packets of color film from the National Geographic Society, which were then placed on the Space Shuttle #3. The ultimate goal was to obtain reasonably accurate data concerning the background fogging effects on IIaO film as it relates to the film's total environmental experience. This includes: the ground based packing, and loading of the film from Goddard Space Flight Center to Cape Kennedy; the effects of the solar wind, humidity, and cosmic rays; the Van Allen Belt radiation exposure; various thermal effect; reentry and off-loading of the film during take off, and 8 day, 3 hour 15 minutes orbits. The total densitometric change caused by all of the above factors were examined. The results of these studies have implications for the utilization of IIaO spectroscopic film on the future shuttle and space lab missions. These responses to standard photonic energy sources will have immediate application for the uneven responses of the film photographing a star field in a terrestrial or extraterrestrial environment with associated digital imaging equipment.

Hammond, E. C., Jr.↗
NASA NTRS1987

The calibration of photographic and spectroscopic films. A densitometric analysis of IIaO film flown aboard the space shuttle transportation system STS3, STS8, and STS7

The results of these studies have implications for the utilization of the IIaO spectroscopic film on the future shuttle and space lab missions. These responses to standard photonic energy sources will have immediate application for the uneven responses of the film photographing a star field in a terrestrial or extraterrestrial environment with associated digital imaging equipment.

Hammond, Ernest C., Jr.↗
NASA NTRS1987

In situ measurement of atomic hydrogen in the upper mesosphere

In situ measurements of H abundance between 73 and 93 km are reported for conditions of winter solstice, magnetic quiet, and a solar depression angle of 12 deg. The data were obtained by a rocket-borne instrument using the resonance fluorescence technique. A discharge source emitting photons at 1216 A was an integral part of the instrument. The instrument was radially deployed 80 cm by a boom from the front of the payload in order to avoid the shock created by the gas flow over the front of the payload. An attitude control system oriented the payload so that the gas flow was nearly perpendicular to the plane containing the incident and scattered photons, thus minimizing any correction for Doppler shift. The resonance radiation detector viewed a black backstop in order to minimize background radiation from the hydrogen geocorona; however, the background was not entirely eliminated. The signal-to-noise ratio was improved by summing the data in 1.8-s bins. The observed hydrogen concentration maximized at 85 km at 1.5 + or - 1.1 x 10 to the 8th atoms/cu cm.

Sharp, W. E.↗
NASA NTRS1992

Photon escape probabilities from resolved sources - Application to solar C III limb emission

Monodirectional effective escape probabilities, involving line-of-sight-integrated escape factors, are calculated for the highly anisotropic source represented by C III emission at the solar limb as a concrete example of the application of such probabilities. Predicted intensity variations of C III lines with limb distance are obtained using a spherical shell model, showing several interesting features which may be observable with appropriate instruments. Among these are expected enhancements of extreme ultraviolet lines at 884.5 and 1308.7 A, and local limb-brightening and limb-darkening effects in optically thick lines, which may provide sensitive constraints on the solar C III emission distribution. Comparisons are made with available observations.

Kastner, S. O.↗
NASA NTRS1994

Deformed ellipsoidal diffraction grating blank

The Deformed Ellipsoidal Grating Blank (DEGB) is the primary component in an ultraviolet spectrometer. Since one of the major concerns for these instruments is throughput, significant efforts are made to reduce the number of components and subsequently reflections. Each reflection results in losses through absorption and scattering. It is these two sources of photon loss that dictated the requirements for the DEGB. The first goal is to shape the DEGB in such a way that the energy at the entrance slit is focused as well as possible on the exit slit. The second goal is to produce a surface smooth enough to minimize the photon loss due to scattering. The program was accomplished in three phases. The first phase was the fabrication planning. The second phase was the actual fabrication and initial testing. The last phase was the final testing of the completed DEGB.

Decew, Alan E., Jr.↗