Engineering topics

Guzik, T. G.

Publications and source records attributed to Guzik, T. G..

At least 37 records · Page 2

NASA NTRS2001

First Flight of the Advanced Thin Ionization Calorimeter (ATIC) Balloon Experiment

The ATILT instrument is designed to measure the composition and energy spectra of Z = 1 to 28 cosmic rays over the energy range -10 GeV - 100 TeV. ATIC was launched as a long duration test balloon flight on 12/28/00 local time from McMurdo, Antarctica. The operations preceding and during launch went very smoothly. During the first -20 hr while the instrument remained within line of sight (LOS), a full system check out was conducted, the experiment was operated in several test configurations, and all major tuning was completed. Preliminary analysis of the science data indicates that the overall detector system is functioning as expected. With our fully functioning analysis software we were able to monitor the data in nearly real time. Each event was reconstructed event-by-event to confirm the detector performance. The shower profiles indicate that the shower maximum location is deeper in the calorimeter for higher energy events, as expected. The energy spectra of protons, Helium nuclei, and "all particles" appear to follow power laws. Both the Si matrix and top scintillator layer of the charge module show clear charge separation for p and He. As the statistics increase, heavy nuclei charge separation will be evaluated. We will present preliminary results of the LOS data, as well as other data that will be available from the flight-data hard disk,

Case, G.↗

NASA NTRS1995

Cosmic ray heavy ion penetration deep into the magnetosphere: Results from S81-1 and CRRES

In spite of strong magnetic shielding by the geomagnetic field, small fractions (1-10 %) of the total high energy, heavy ion intensities of solar and galactic cosmic rays have been observed at energies below theoretical cutoffs for direct entry into the earth's magnetosphere from interplanetary space. We report on measurements of these heavy ions at 10 to 500 MeV/nucleon by cosmic ray composition experiments on the S81-1 satellite in polar orbit during 1982 and on the Combined Release and Radiation Effects Satellite (CRRES) satellite in geosynchronous transfer orbit during 1990-1991.

Cooper, J. F.↗

NASA NTRS1994

A model of solar energtic particles for use in calculating LET spectra developed from ONR-604 data

A model of Solar Energetic Particles (SEP) has been developed and is applied to solar flares during the 1990/1991 Combined Release and Radiation Effects Satellite (CRRES) mission using data measured by the University of Chicago instrument, ONR-604. The model includes the time-dependent behavior, heavy-ion content, energy spectrum and influence, and can accurately represent the observed SEP events in the energy range between 40 to 500 MeV/nucleon. Results are presented for the March and June, 1991 flare periods.

Chen, J.↗

NASA NTRS1994

A model of galactic cosmic rays for use in calculating linear energy transfer spectra

The Galactic Cosmic Rays (GCR) contain fully stripped nuclei, from Hydrogen to beyond the Iron group, accelerated to high energies and are a major component of the background radiation encountered by satellites and interplanetary spacecraft. This paper presents a GCR model which is based upon our current understanding of the astrophysics of GCR transport through interstellar and interplanetary space. The model can be used to predict the energy spectra for all stable and long-lived radioactive species from H to Ni over an energy range from 50 to 50,000 MeV/nucleon as a function of a single parameter, the solar modulation level phi. The details of this model are summarized, phi is derived for the period 1974 to present, and results from this model during the 1990/1991 Combined Release and Radiation Effects Satellite (CRRES) mission are presented.

Chen, J.↗

NASA NTRS1994

A program to measure new energetic particle nuclear interaction cross sections

The Transport Collaboration, consisting of researchers from institutions in France, Germany, Italy, and the USA, has established a program to make new measurements of nuclear interaction cross sections for heavy projectiles (Z greater than or equal to 2) in targets of liquid H2, He and heavier materials. Such cross sections directly affect calculations of galactic and solar cosmic ray transport through matter and are needed for accurate radiation hazard assessment. To date, the collaboration has obtained data using the Lawrence Berkeley Laboratory Bevalac HISS facility with 20 projectiles from He-4 to Ni-58 in the energy range 393-910 MeV/nucleon. Preliminary results from the analysis of these data are presented here and compared to other measurements and to cross section prediction formulae.

Guzik, T. G.↗

NASA NTRS1994

A model of solar energetic particles for use in calculating LET spectra developed from ONR-604 data

A model of solar energetic particles (SEP) has been developed and is applied to solar flares during the 1990/1991 CRRES mission using data measured by the University of Chicago instrument, ONR-604. The model includes the time-dependent behavior, heavy-ion content, energy spectrum and fluence, and can accurately represent the observed SEP events in the energy range between 40 to 500 MeV/nucleon. Results are presented for the March and June, 1991 flare periods.

unmanned↗

NASA NTRS1993

Balloon observations of Galactic cosmic ray helium before and during a Forbush decrease

The energy spectrum of Galactic cosmic ray helium was measured in two different balloon experiments launched four days apart from Canada: SMILI-I on Sept 1, 1989 and MASS on Sept 5, 1989. A slow Forbush decrease began on Sept 4, 1989 and had not reached its maximum at the time of the MASS flight. Comparison of the balloon measurements shows a fractional decrease of 0.37 to 0.15 in the Helium flux between 200 and 450 MeV/nucleon (1.2-2.0 GV). The rigidity dependence is analyzed in two models and found to be steeper than previous observations. Interplanetary particle data and ground-based Neutron Monitor results are consistent with the balloon observations. Probable sources for this Forbush decrease are discussed.

Clem, J. M.↗

NASA NTRS1993

The cosmic-ray He-3/He-4 ratio from 100 to 1600 MeV/amu

The Superconducting Magnet Instrument for Light Isotopes (SMILI) flew for 19 hours on September 1, 1989, with a residual overburden of 5 g/sq cm. It measured the charge, rigidity, and velocity of 30,000 cosmic-ray helium nuclei, with velocity determined by time-of-flight and Cerenkov techniques. Using these data, the flux and isotopic composition of helium as a function of energy were determined. The observed isotopic composition is consistent with that expected from interstellar propagation models inferred from the secondaries of CNO, in contrast to earlier observations which indicated an overabundance of He-3. We discuss constraints that this result places on cosmic-ray transport and solar modulation models.

Beatty, J. J.↗

NASA NTRS1990

POsitron Electron Magnet Spectrometer (POEMS) for the Eos Mission

The scientific objectives of the POsitron Electron Magnet Spectrometer (POEMS) experiment are briefly reviewed. These include determining the origin of primary positrons and studying particle confinement in the Galaxy, solar modulation, solar flares, the geospace environment, and atmospheric physics and chemistry. The design of the POEMS instrument is summarized.

Evenson, Paul↗

NASA NTRS1990

Current and future uses of accelerators in particle astrophysics

Beams of artificially accelerated heavy ions, protons, antiprotons, electrons, and positrons currently available at (and planned for) numerous facilities around the world are a valuable resource to the Cosmic Ray community. Such beams have been used to test detector concepts, calibrate balloon-borne and space flight experiments and to measure fundamental nuclear physics parameter necessary for the interpretation of Cosmic Ray data. As new experiments are flown the quality and extent of Cosmic Ray measurements will continue to improve. It will be necessary to increase activity at ground based accelerators in order to test/calibrate these new instruments and to maintain (or possibly improve) the ability to interpret these data. In this area, the newly formed Transport Collaboration, supported by NASA, will be providing new nuclear interaction cross section measurements for beams with Z less than or = 58 and supporting new instrument calibrations at the Lawrence Berkeley Laboratory Bevalac accelerator.

Guzik, T. G.↗

NASA NTRS1989

Low-altitude trapped protons at the geomagnetic equator

Geomagnetically trapped protons in the 0.6- to 9-MeV energy range were measured at latitudes near the geomagnetic equator by the Phoenix 1 experiment on board the S81-1 mission from May to November 1982. The protons show a distribution in latitude along the line of minimum magnetic field strength with a full width at half maximum of about 10 deg but with no appreciable longitudinal variation. Between 170 and 290 Km the peak proton flux shows a fifth-power altitude dependence, in contrast to previous measurements at higher altitudes, possibly demonstrating source attenuation. The efficiency of the telescope is calculated as a function of particle pitch angle and used to investigate the time dependence (1969-1982) of the intensity.

Guzik, T. G.↗

NASA NTRS1987

Cosmic-ray propagation in the Galaxy and in the heliosphere - The path-length distribution at low energy

The energy dependence of the path-length distribution of cosmic rays at low energies, below relativistic velocities, is studied, and its implications for models of cosmic-ray confinement and propagation in the Galaxy and Galactic halo, including the effects of a possible Galactic wind, are studied. It is found that the mean free path in Galactic propagation must be fully energy-dependent, with the mean of an exponential path-length distribution increasing with increasing energy below 1 GeV per nucleon and decreasing with increasing energy above 1 GeV per nucleon. This indicates that, at low energies, diffusion is not the controlling process. The path-length distribution is not purely exponential but is depleted in short path lengths at low energies. This depletion is energy-dependent, being largest at low energies and decreasing with increasing energy.

Garcia-Munoz, M.↗

NASA NTRS1985

Galactic propagation models consistent with the cosmic ray lifetime derived from Be-10 measurements

Using a propagation calculation with energy dependent parameters, including the depletion of short pathlengths, and incorporating experimental nuclear excitation functions, the variation of the Be-10/Be9 ratio with the matter densities in two nested confinement regions is investigated. It is shown that there is no unique correspondence between a Be-10/Be9 measurement at low energy and the density of matter in the galaxy. Be-10/Be9 measurements at both low and high energy are needed to fully specify the matter densities.

Guzik, T. G.↗

NASA NTRS1985

Implications of new measurements of O-16 + p + C-12,13, N-14,15 for the abundances of C, N isotopes at the cosmic ray source

The fragmentation of a 225 MeV/n O-16 beam was investigated at the Bevalac. Preliminary cross sections for mass = 13, 14, 15 fragments are used to constrain the nuclear excitation functions employed in galactic propagation calculations. Comparison to cosmic ray isotonic data at low energies shows that in the cosmic ray source C-13/C approximately 2% and N-14/0=3-6%. No source abundance of N-15 is required with the current experimental results.

Guzik, T. G.↗

NASA NTRS1984

The path-length distribution for galactic cosmic-ray propagation - An energy-dependent depletion of short path lengths

It is shown that at low energies, the depletion of short path lengths in the interstellar cosmic-ray path-length distribution is a function of energy, decreasing in magnitude with increasing energy. The analysis leading to this conclusion is based on the comparison of compiled data for the B/C and sub-Fe/Fe ratios at 0.08-50 GeV per nucleon, with the results of detailed galactic propagation and solar modulation calculations, which include experimental values for the important nuclear cross sections. This energy dependence of the depletion resolves some of the conflicts between previous reports on the question of short path lengths and may be explained by models including a matter distribution around discrete sources or, possibly, by models invoking waves generated by particle-magnetic field interactions in the Galaxy.

Garcia-Munoz, M.↗

NASA NTRS1984

The cosmic-ray pathlength distribution at low energy - A new probe of the source/acceleration regions

Compiled measurements of secondary to primary ratios covering the charge range Z = 3-26 and the energy range 0.05 - 50 GeV/nucleon are analyzed in energy dependent galactic propagation plus solar modulation calculations. The cosmic ray pathlength distribution is shown to consist of two energy dependent components interpreted as representing confinement in the galaxy and confinement in the 'source' regions.

Guzik, T. G.↗

NASA NTRS1983

Evidence for an energy dependence in the short pathlengths of the cosmic ray pathlength distribution

The energy dependence of the short pathlengths in the cosmic ray pathlength distribution is investigated in a galactic propagation plus solar modulation calculation. In order to reproduce, simultaneously, the compiled B/C and sub-Fe/Fe measurements, an energy dependent deficiency of short pathlengths is required which is largest at low energies and becomes negligible above a few GeV/nucleon. Such behavior could imply a significant contribution from matter in the vicinity of the cosmic ray source or the acceleration site.

Garcia-Munoz, M.↗

NASA NTRS1982

The energy dependence of cosmic ray propagation at low energy

The interstellar propagation of cosmic rays is investigated using current 'best estimates' for the partial and total cross sections and their energy dependence and the current model of solar modulation. The experimental boron to carbon ratio is reproduced if the mean of the path length distribution decreases with decreasing energy below approximately 1 GeV/nucleon. This energy dependence is compared to shock acceleration models and dynamical halo models using different galactic wind velocities.

Garcia-Munoz, M.↗