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Lheureux, J.

Publications and source records attributed to Lheureux, J..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

The development of a high energy cosmic ray detector for Spacelab-2

A large cosmic ray detector aimed at measurements of the energy spectra and of the elemental abundances of cosmic ray nuclei at very high energies, up to several TeV/nucleon was constructed. The instrument is an electronic counter telescope with a geometric factor of 5 sq ster. It accomplishes measurements of the particle energies through the use of gas Cerenkov counters and of transition radiation detectors. The solutions of a number of technological problems that are encountered when developing such instrumentation for Shuttle missions are discussed.

Lheureux, J.↗
NASA NTRS1985

Detectors for high energy cosmic rays on Spacelab

Two instruments designed to determine the spectra of the individual cosmic-ray components at very high energies are described. One of these (CRNE) uses a combination of gas Cerenkov counters and transition radiation detectors for the cosmic-ray nuclei lithium to nickel; the other (TRIC) is optimized for the light cosmic rays (electrons, protons, helium) and uses a transition-radiation/ionization-calorimeter combination. The CRNE instrument, constructed at the University of Chicago, was delivered to NASA for a first Shuttle flight on Spacelab-2 in summer 1985. Some of the technical and programmatic requirements encountered during the hardware construction and integration are discussed, and the expected scientific return and the prospects of using such instrumentation on the Space Station are considered.

Lheureux, J.↗
NASA NTRS1981

A new transition radiation detector for cosmic ray nuclei

Test measurements on materials for transition radiation detectors at a low Lorentz factor are reported. The materials will be based on board Spacelab-2 for determining the composition and energy spectra of nuclear cosmic rays in the 1 TeV/nucleon range. The transition radiation detectors consist of a sandwich of radiator-photon detector combinations. The radiators emit X-rays and are composed of polyolefin fibers used with Xe filled multiwired proportional chamber (MWPC) detectors capable of detecting particle Lorentz factors of several hundred. The sizing of the detectors is outlined, noting the requirement of a thickness which provides a maximum ratio of transition radiation to total signal in the chambers. The fiber radiator-MWPC responses were tested at Fermilab and in an electron cyclotron. An increase in transition radiation detection was found as a square power law of Z, and the use of six radiator-MWPC on board the Spacelab-2 is outlined.

Lheureux, J.↗
NASA NTRS1980

The high energy cosmic ray detector for Spacelab II

A large cosmic ray detector to be flown on Spacelab II is presently under construction at the University of Chicago. The instrument, with a geometric factor of 5 sq m-ster, is designed to measure the elemental composition and the energy spectra of individual cosmic ray nuclei (Li to Fe) from 50 GeV/nucleon to several TeV/nucleon. Plastic scintillators are used for charge determination, and gas Cerenkov and transition radiation detectors for energy measurements. The instrument and its functions are described, and several test results that are important for an optimum design are discussed.

Lamport, J. E.↗
NASA NTRS1978

Cosmic ray scintillations in the frequency range from 0.00001 to 0.01 Hz

Power spectra of the flux variations in cosmic rays of energy greater than a few GeV are presented. The data were obtained at balloon altitudes (40-45 km) from two scintillation-type detectors flown for six hours from Palestine, Texas, on November 4, 1972. The large area detectors had effective count rates up to 2000 cps setting the Poisson noise level in the power spectra of the relative fluctuations at 0.001/Hz. The analysis was made on the singles rate of each of the counters as well as on the coincidence rates between them. In all cases, the spectra between 0.0001 and 0.002 Hz are power laws in frequency of the form f to the exponent negative gamma, where gamma is between 1.5 and 2.0. No significant peaks in the range 0.0001 to 0.01 Hz are observed.

Gehrels, N.↗
NASA NTRS1976

Quiet-time increases of low-energy electrons - The Jovian origin

With a detector on board the OGO-5 satellite, the flux and energy spectrum of electrons in the 10-200-MeV range has been continuously measured from 1968 to 1971. Sudden increases in intensity by factors of up to 300% have been observed during solar quiet times. It is shown that these increases are nearly independent of energy up to about 25 MeV and disappear rapidly above that energy. The frequency of the increases peaks every 13 months at a time following the crossing by earth of the interplanetary magnetic-field line which passes the vicinity of the planet Jupiter. Most of the increases occur in a period of 3 to 5 months following this crossing and often appear to be 27 days apart. A Jovian origin for these electrons and their mode of transport to the inner solar system are discussed.

Lheureux, J.↗
NASA NTRS1975

On the quiet-time increases of low energy cosmic ray electrons

With a detector on board the OGO-5 satellite, the flux and energy spectrum of electrons in the 10-30 MeV range has been continuously monitored from 1968 to 1972. Sudden increases by factors of up to 300 percent have been observed during solar quiet periods. These 'Quiet-Time Increases' abruptly die out above 30 MeV and correlate well with identical increases reported at lower energies leading to a flat relative energy spectrum. A large fraction of these electrons is most likely of Jovian origin.

Lheureux, J.↗
NASA NTRS1975

Modulation of low energy electrons and protons near solar maximum

The intensities of cosmic-ray electrons in the energy range from 24 to 235 MeV and of protons in the ranges 40 to 150 MeV and greater than 700 MeV are compared with the neutron intensity data over the period 1968 to 1972. Correlation plots between these various components show a marked break following the June 9, 1969 Forbush decrease. The resulting hysteresis curve is best explained as a sudden change in the rigidity dependence of solar modulation. A variation in the size of the solar cavity is also possible but not likely.

Lheureux, J.↗
NASA NTRS1974

Cosmic gamma-ray burst detected with an instrument on board the OGO-5 satellite

Gamma-ray bursts of cosmic origin have recently been detected by instruments on the Vela satellites. We now confirm the detection of the June 30, 1971 event with an instrument on board the OGO-5 satellite. The intensity of this burst is calculated to be approximately 100-200 photons per sq cm/sec for photons of energy greater than 150 keV with an upper limit of 50 photons per sq cm/sec for the intensity above 5 MeV. An upper limit of one-third of the intensity of the June 30, 1971 event is set for 10 other events studied.

Lheureux, J.↗
NASA NTRS1974

Chemical abundances of cosmic rays greater than 4.5 GV measured with a large area proportional counter-scintillation counter stack

A 6500 sq cm-ster cosmic-ray detector consisting of 12 gas counter trays sandwiched between two large-area circular scintillation counters was flown from Palestine, Texas in November 1972 to study the composition of primary particles greater than 1.5 GeV/nucleon in the charge range from 3 to 30. For each analyzed event, the particle trajectory was recorded, using four 20-wire proportional counter trays. Also recorded were the energy loss in each of the solid counters and the dE/dx losses in each of the 12 gas counters. The large dynamic range of the detector is established by operating six of the gas counters in the ionization mode. A description of the instrument and some preliminary results are given.

Lheureux, J.↗
NASA NTRS1974

The cosmic ray electron spectrum and its modulation from 1968 through 1972

Over the past five years we have measured the energy spectrum of primary cosmic ray electrons with both a balloon-borne and a satellite absorption spectrometer. All of the balloon flights used identical equipment that was launched each summer from Fort Churchill, Manitoba, Canada. The satellite, OGO-5, has been in an eccentric orbit since March 1968. Together these instruments provide the electron spectrum over a range of energy from 20 MeV to 20 GeV. This wide range and the substantial span of time covered by the measurements permit a detailed study of the solar modulation of electrons. These results are compared with the modulation of the nuclear components as observed by a neutron monitor and interpreted using the cosmic ray transport equation.

Fulks, G.↗
NASA NTRS1973

Chemical abundances of cosmic rays greater than 4.5 GV measured with a large area proportional counter-scintillation counter stack

A 6500 sq cm-ster cosmic ray detector consisting of twelve gas counter trays sandwiched between two large area circular scintillation counters was flown from Palestine, Texas in November of 1972 to study the composition of primary particles 1.5 GeV/nucleon in the charge range 3 to 30. For each analyzed event, a recording was made of (1) the particle trajectory using four 20 wire proportional counter trays, (2) the energy loss in each of the solid counters, and (3) the dE/dx losses in each of the twelve gas counters. The large dynamic range of the detector is established by operating six of the gas counters in the ionization mode. A description of the instrument and some preliminary results are given.

Lheureux, J.↗