Prometheus update
- Rice Univ., Houston, TX (United States)
Prometheus I is a very low background 0.03 - 6.5 MeV gamma-ray balloon-borne imager. It eliminates the activation component of instrumental background through use of a gamma ray detector that is segmented in two dimensions, an active collimator fabricated from low-Z matter, an active collimator that vetoes prompt events due to fast neutrons, and a radiationless absorber of slow neutrons. The segmented detector rejects beta rays emitted by internal Nal activated nuclei because a beta causes only one segment to pulse, but a gamma ray interacting through Compton scattering causes several segments to simultaneously pulse. It serves as a position sensitive gamma-ray detector for the coded mask that fills the collimator's aperture. Because of its low background, the 3 [sigma] spectral-line sensitivity at 1 MeV of Prometheus II is expected to be 5 [times] 10[sup -5] photons cm[sup -2] sec[sup -1], given six hours observing time at midlatitude balloon altitudes. Prometheus will be used to produce a 0.5 - degree map of the entire sky in an energy band above that of the hard X-ray band, but below that of the COMPTEL:sky map. The map will be the principal objective of two Long Duration Balloon flights that are planned for 1994 and 1995. Prometheus has an in-flight selectable field of view (FOV) that ranges from 4 deg [times] 4 deg to 38 deg [times] 38 deg, and 30 arc-minute angular resolution. The localizability of bright sources is about 3 arc minutes. Since there is no unvetoed activation gamma radiation from the collimator, the energy spectrum of the aperture radiation may be unambiguously determined by measuring the dependence of counting rate upon size of the FOV. This has implications for an independent means of measuring the MeV bump' in the spectrum of the diffuse extragalactic background.
- OSTI ID:
- 6885210
- Report Number(s):
- CONF-930189-; CODEN: AASBAR
- Journal Information:
- American Astronomical Society, Bulletin; (United States), Vol. 24:4; Conference: 181. meeting of the American Astronomical Society (AAS), Phoenix, AZ (United States), 3-7 Jan 1993; ISSN 0002-7537
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BALLOONS
DIAGNOSTIC USES
SKY
ENERGY SPECTRA
MAPPING
CHARGED PARTICLES
FAST NEUTRONS
GAMMA RADIATION
HARD X RADIATION
PHOTONS
SLOW NEUTRONS
AIRSHIPS
BARYONS
BOSONS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FERMIONS
HADRONS
IONIZING RADIATIONS
MASSLESS PARTICLES
NEUTRONS
NUCLEONS
RADIATIONS
SPECTRA
USES
X RADIATION
440103* - Radiation Instrumentation- Nuclear Spectroscopic Instrumentation