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Stilwell, D. E.

Publications and source records attributed to Stilwell, D. E..

8 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

The transient gamma-ray spectrometer

The authors describe the Transient Gamma-Ray Spectrometer (TGRS) to be flown onboard the WIND spacecraft. This instrument is designed to detect cosmic gamma-ray bursts over the energy range of 20 keV to 10 MeV with an expected spectroscopic resolution of 2 keV at 1 MeV (E/Delta-E = 500). The active detection element is a 215-cu cm high-purity n-type Ge crystal cooled to cryogenic temperatures by a passive radiative cooler. The geometric field of view (FOV) defined by the cooler is 170 deg FWFM. Burst data are stored directly in an onboard 2.75-Mb burst memory with an absolute timing accuracy of +/-1.5 ms. This capacity is sufficient to store the entire spectral data set of all but the largest bursts. In addition to burst measurements, the instrument will also study solar flares, search for possible diffuse background lines, and monitor the 511-keV positron annihilation radiation from the galactic center. The experiment is scheduled to be launched on a Delta II launch vehicle from Cape Canaveral on December 31, 1992.

Owens, A.↗
NASA NTRS1979

The Voyager Cosmic Ray Experiment

The Voyager Cosmic Ray Experiment includes seven dE/dx-E telescopes to measure the energy and charge of particles with atomic numbers from 1 to 26 in the energy range 1-500 MeV/nucleon and to measure electron energy in the range from 3 to 110 MeV. Isotopic composition of hydrogen through sulfur in the range up to 75 Mev/nucleon can also be resolved. The electronic systems include a dual-gain, charge sensitive preamplifier, 4096-channel pulse height analyzers for three parameter analysis of selected events, and an event type readout polling scheme to maximize the use of available telemetry space and to enhance the occurrence of rare events in the data. Details of the detector, electronic and mechanical design are presented.

Stilwell, D. E.↗
NASA NTRS1975

The Helios A/B cosmic ray instrument /E 7/

This paper describes the design and performance of a cosmic ray particle experiment for the Helios A/B space missions. This experiment had to be very lightweight, low power and electronically sophisticated in order to meet the spacecraft and scientific requirements, and very similar to those on the Pioneer 10 and 11 missions to Jupiter. Both sets of missions use several solid-state detector telescopes to measure protons from 100 KeV to 800 MeV per nucleon. Additionally, the Helios experiment includes a proportional counter to monitor the solar X-ray activity. The experiment has functioned quite well for 5 months in space, and large quantities of data are now being received.

Trainor, J. H.↗
NASA NTRS1975

Jovian protons and electrons: Pioneer 11

A preliminary account of the Pioneer 11 passage through the Jovian magnetosphere as viewed by particle detector systems is presented. Emphasis is placed on the region well within the Jovian magnetosphere using data from the LET-II telescope, which measured the proton flux from 0.2 to 21.2 MeV in seven energy intervals and electrons from 0.1 to 2 MeV in four energy intervals. The relative trajectories of Pioneer 10 and 11 are discussed and indicate that Pioneer 11 was exposed to a much lower total radiation dose than Pioneer 10, largely as a result of the retrograde trajectory which approached and exited the inner region of the magnetosphere at high latitudes. Angular distributions, calculations from Pioneer 11 magnetic field data, and the low-energy nucleon component are included in the discussion.

Trainor, J. H.↗
NASA NTRS1975

The Pioneer 10/11 and Helios A/B cosmic ray instruments

This paper describes the design and performance of a set of cosmic-ray particle experiments for the Pioneer 10/11 and Helios A/B space missions. These experiments had to be very light-weight, low-power and electronically sophisticated in order to meet the spacecraft and scientific requirements. Both sets of missions use several solid-state detector telescopes to measure protons from 100 KeV to 800 MeV and heavier ions up to Neon at 200 MeV per nucleon. Good performance is required for 7-8 years, and the system must tolerate large vibration loads and ionizing radiation doses up to 500,000 rads.

Stilwell, D. E.↗
NASA NTRS1974

Energetic particle population in the Jovian magnetosphere - A preliminary note

Preliminary account of energetic particle measurements conducted by the Pioneer 10 spacecraft during approach to Jupiter in November and December 1973. Graphs illustrate electron and proton flux levels as a function of distance from the planet for different particle energy intervals. Times of predicted equatorial crossing are marked along with positions corresponding to the bowshock, magnetopause, and other features. The general patterns of particle distribution in the Jovian vicinity are discussed.

Trainor, J. H.↗