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NASA NTRS1985

Anomalous short-term increases in the galactic cosmic ray intensity: Are they related to the interplanetary magnetic cloud-like structures?

Thirty-one short-term increases (time duration 24 hours and amplitude up to 5%) in the galactic cosmic ray intensity, occurring inside Forbush decreases events, have been identified over the period 1966 - 1977. These increases are highly anisotropic and occur after the compression region following the shock; the interplanetary medium is characterized by intense ( 10 nT) and higly fluctuating magnetic field B, high velocity, low density and temperature (flare ejecta piston?). These B-fluctuations seem to be ordered variations which could be representative of magnetic clouds. Also the large cosmic ray increase occurring on 17-18 September 1979, belongs to this category of events.

Iucci, N.↗

NASA NTRS1985

Anomalous low level of cosmic ray intensity decreases observed during 1980

Past studies have revealed solar cycle changes in the sunspot activity, as well as in many other solar parameters, such as, solar flares and solar coronal holes. These solar features in turn produce the observed cyclic variations in the interplanetary plasma and fields. Both the cosmic ray intensity as well as the intensity of geomagnetic disturbances are affected by the interplanetary changes and produce 11/22 year periodicity. An anomalous situation has been noticed during the year 1980 (period of high sunspot activity), when both the geomagnetic disturbance index Ap, as well as the magnitude and number of Forbush decreases as small. Such an anomaly occurs, in spite of the fact that both the sunspot numbers and the energetic solar flares are almost maximum during the present solar cycle.

Jain, A. K.↗

NASA NTRS1985

Connection between variations of the atmosphere temperature profile and variations of the meson component intensity

The influence of temperature effects on intensity variations of the cosmic ray meson component were studied. The connection between the temperature variation delta T and the intensity variation delta I was established by using the temperature coefficient density technique. To realize how many devices are needed on the Earth for predicting the temperature variation of the atmosphere profile with a reasonable accuracy, IO isobaric levels and IO were calculated. The set of initial elements of the cosmic ray mesons are varied and it is shown that the matrix of the coefficients B sub ij is rather sensitive to their choice. It is found that if for the calculations of the atmospheric temperature variations the model is used, the number of meson components, essentially exceeding 3, should be considered.

Blokh, Y. L.↗

NASA NTRS1985

Underwater measurements of muon intensity

Experimental measurements of cosmic ray muon intensity deep underwater aimed at determining a muon absorption curve are of considerable interest, as they allow to reproduce independently the muon energy spectrum at sea level. The comparison of the muon absorption curve in sea water with that in rock makes it possible to determine muon energy losses caused by nuclear interactions. The data available on muon absorption in water and that in rock are not equivalent. Underground measurements are numerous and have been carried out down to the depth of approx. 15km w.e., whereas underwater muon intensity have been measured twice and only down to approx. 3km deep.

V.M. Fedorov↗

NASA NTRS1985

Measurement of muon intensity by Cerenkov method

Optical detection is an important technique in studies and observations of air showers, muons and relevant phenomena. The muon intensity is measured in a proper energy range and to study some problems about Cerenkov radiation of cosmic rays are studied, by a muon-telescope operated with Cerenkov detector. It is found that the measured muon intensity agrees with the integral energy spectrum of cosmic ray muons.

Liu, Z. H.↗

NASA NTRS1985

Analytical calculation of muon intensities under deep sea-water

The study of the energy loss of high energy muons through different materials, such as rock and sea-water can cast light on characteristics of lepton interactions. There are less ambiguities for the values of atomic number (Z) and mass number (A) in sea-water than in rock. Muon intensities should be measured as fundamental data and as background data for searching the fluxes of neutrino. The average range energy relation in sea-water is derived. The correction factors due to the range fluctuation is also computed. By applying these results, the intensities deep under sea are converted from a given muon energy spectra at sea-level. The spectra of conventional muons from eta, K decays have sec theta enhancement. The spectrum of prompt muons from charmed particles is almost isotropic. The effect of prompt muons is examined.

Inazawa, H.↗

NASA NTRS1985

Calculation of intensity of high energy muon groups observed deep underground

The intensity of narrow muon groups observed in Kolar Gold Field (KGF) at the depth of 3375 m.w.e. was calculated in terms of quark-gluon strings model for high energy hadron - air nuclei interactions by the method of direct modeling of nuclear cascade in the air and muon propagation in the ground for normal primary cosmic ray composition. The calculated intensity has been found to be approx. 10 to the 4 times less than one observed experimentally.

Vavilov, Y. N.↗

NASA NTRS1985

Radar and photometric measurements of an intense type A red aurora

On the evening of March 5, 1981, an intense, type A red aurora appeared over southern Alaska. Radar and photometric measurements were made of the aurora from the Chatanika radar site. The line of sight intensity of the 630.0-nm emissions exceeded 150 kR and was accompanied by enhanced emissions at 486.1 and 427.8 nm. The Chatanika radar measured electron densities of 10 to the 6th per cu cm and electron temperatures of 6000 K at an altitude of 400 km and an invariant latitude of 59 deg in association with the aurora. Comparison of optical and radar measurements indicated that the 630.0-nm emissions were produced to a large degree by thermal excitation of O(1D) in the region of high electron temperatures and densities. Model calculations indicate that the observed density and temperature enhancements and the related optical emissions were the results of a relatively short duration (5-10 min) pulse of precipitating, low-energy (about 30 eV) electrons. Whereas conventional stable auroral red arcs are associated with a gradual decrease in ring current energy density during the recovery phase of a magnetic storm, the type A red aurora may be produced by impulsive ring current energy loss during the main phase.

Robinson, R. M.↗

NASA NTRS1984

Influence of precracked specimen configuration and starting stress intensity on the stress corrosion cracking of 4340 steel

Since the pioneer work of Brown (1966), precracked specimens and related fracture mechanics analyses have been extensively used to study stress corrosion cracking. Certain questions arose in connection with initial attempts to prepare standardized recommended practices by ASTM Committee G-1 on Corrosion of Metals. These questions were related to adequacy of test control as it pertains to acceptable limits of variability, and to validity of expressions for stress intensity and crack-surface displacements for both specimen configurations. An interlaboratory test program, was, therefore, planned with the objective to examine the validity of KIscc testing for selected specimen configurations, materials,and environmental systems. The results reported in the present paper include details of a single laboratory test program. The program was conducted to determine if the threshold value of stress intensity for onset and arrest of stress corrosion cracking was independent for the two specimen configurations examined.

Lisagor, W. B.↗

NASA NTRS1985

Expected intensities of solar neon-like ions

A study of the expected intensities of the stronger solar neon-like ion emission lines, some not yet observed, is carried out to compare with the observational situation. The potential usefulness of the 2p5 3s(3P2) - 2p6 forbidden line as a density diagnostic is discussed, and new electric quadrupole lines in the soft X-ray range are noted. 'Observability diagrams' are presented as a convenient overview of the known and unobserved lines. The S VII resonance lines appear to have anomalous intensities.

Bhatia, A. K.↗

NASA NTRS1985

Theoretical calculation of ozone vibrational infrared intensities

An ab initio dipole moment function for ozone has been computed using the CASSCF (complete active space self-consistent field) method, and forms the basis for a calculation of ozone infrared band intensities. Vibrational wave functions were generated using the variational method with potential energy surfaces derived from experimental force constants. Computed values of the permanent dipole moment, dipole moment derivatives, and infrared band strengths are all found to be in remarkably good agreement with experiment. Intensities are predicted for hot bands for which experimental values are unavailable, and implications for atmospheric ozone spectroscopy are discussed. As the dipole moment matrix element signs are now established for nearly all of the observed bands, further refinement of the dipole moment function is possible.

Adler-Golden, S. M.↗

NASA NTRS1985

Fluctuations of precipitated electron intensity in flickering auroral arcs

Electron spectra associated with two aurorae observed by ground-based television are reported. One auroral arc was observed to flicker, large variations in the precipitated electron energy occurring on a time scale of 114 ms. The major variations occur at the higher energies of the 0.5-20 keV range covered by the detectors. Changes in the particle flux occur primarily in the pitch angle range 0 to 60 deg. Analysis of the video data shows a larger variation in intensity along the lower border of the arc in keeping with the results of the electron spectra. The second arc was not observed to flicker, and the associated electron spectra and video data show no large variations in precipitated electron energy or video intensity modulation. While pitch-angle distributions tend to be field-aligned in the first arc, the distributions in the second arc are nearly isotropic or peaked from 60 to 90 deg in the downward hemisphere.

Spiger, R. J.↗

NASA NTRS1985

The detailed intensity distribution of the AKR emission cone

The detailed intensity distribution of auroral kilometric radiation (AKR) at frequencies near the spectral peak of 200 kHz and below, over the entire northern hemisphere at large radial distances, is presented based on 3.5 years of IMP 6 data and four years of Hawkeye data. The time-averaged intensity of the AKR emission cone at frequencies from 178 to 100 kHz is found to be nearly uniform. Evidence contradicts a 'hollow cone' structure. The solid angles for the AKR emission cones studied are in good agreement with previously published results, and there is good agreement with previously determined AKR source location. The time-averaged picture of the AKR emission pattern at 178 kHz is representative of the instantaneous AKR emission. Present theories for the generation and propagation of AKR appear insufficient to explain the observed illumination pattern.

Green, J. L.↗

NASA NTRS1986

The effective intensity of Coriolis, cross-coupling stimulation is gravitoinertial force dependent - Implications for space motion sickness

The effect of gravity on the severity of the Coriolis-induced motion sickness was investigated in ten individuals subjected to high and low G-force phases of parabolic flight maneuvers using constant level Coriolis, cross-coupled angular acceleration stimulation. Using seven levels of severity in the diagnosis of motion sickness, it was found that the subjects were less susceptible at 0 G than at +2 Gz, and that the perceived intensity and provocativeness of Coriolis stimulation decreased in 0 G and increased in +2 Gz relative to the +1 Gz baseline values. The changes in the apparent intensity of Coriolis stimulation occur virtually immediately when the background gravitatioinertial force level is varied. These findings explain why the Skylab astronauts were refractory to motion sickness during Coriolis stimulation in-flight.

Lackner, J. R.↗

NASA NTRS1986

Strong scintillations during atmospheric occultations Theoretical intensity spectra

Each of the two Voyager spacecraft launched in 1977 has completed a reconnaissance of the Jovian and Saturnian systems. In connection with occultation experiments, strong scintillations were observed. Further theoretical work is required before these scintillations can be interpreted. The present study is, therefore, concerned with the derivation of a theory for strong scattering during atmospheric occultation experiments, taking into account as fundamental quantity of interest the spatial spectrum (or spectral density) of intensity fluctuations. Attention is given to a theory for intensity spectra, and numerical calculations. The new formula derived for Phi-i accounts for strong scattering of electromagnetic waves during atmospheric occultations.

Hinson, D. P.↗

NASA NTRS1986

Absolute line intensities in CO2 bands near 4.8 microns

Absolute intensities for 726 unblended lines in 20 bands of C-12(O-16)2, C-13(O-16)2, O-16C-12O-18, and O-16C-12O-17 in the 4.8-micron spectral region have been determined using a natural sample of ultrahigh-purity CO2. Spectral data were recorded at low pressure (less than 10 torr) and room temperature with the Fourier transform spectrometer in the McMath solar telescope complex on Kitt Peak. Derived vibrational band intensities and coefficients of the F factor for each band were compared to values of the 1982 Air Force Geophysics Laboratory line parameters compilation. The present work fills out the CO2 lines in the 5-micron band systems. Lines in the strongest of these measured bands are being used to infer atmospheric pressure from high-resolution stratospheric spectra recorded during the Spacelab 3 Atmospheric Trace Molecule Spectroscopy experiment.

Rinsland, C. P.↗

NASA NTRS1986

Absolute intensities and self-, N2-, and air-broadened Lorentz halfwidths for selected lines in the nu3 band of (C-12)H3D from measurements with a tunable diode laser spectrometer

Absolute intensities and self-, air- and N2-broadened half-widths have been determined for the first time for individual lines in the nu3(A1) band of (C-12)H3D near 7.6 microns from measurements of individual vibration-rotation lines using a tunable diode laser spectrometer. The intensity measurements are believed to be accurate to within three percent. Within experimental uncertainties, equal broadening efficiencies are found for both air and nitrogen. Self-broadened half-widths determined for three transitions yield an average half-width value of 0.803 + or -0.0010/cm/atm at 296 K.

Malathy Devi, V.↗

NASA NTRS1986

Concentration independent absolute intensity determinations A new method

Attention is given to the means for obtaining, independently of any data on molecular concentration, the absolute intensity determinations on the basis of relative line intensity measurements conducted across the vibration-rotation band of a diatomic molecule. This approach is important for the vibrational fundamental bands of diatomic molecules, which cannot be studied by the lifetime method; its application will be especially significant in the case of diatomic radical species whose concentrations can only be indirectly inferred.

Chackerian, C., Jr.↗