author={Paul T. Feffer and Robert P. Lin and Said A. Slassi-Sennou and Steve McBride and J. H. Primbsch and Gretchen Zimmer and R. M. Pelling and Richard H. Pehl and Norman W. Madden and Don F. Malone and Christopher P. Cork and Paul N. Luke and Gilbert Vedrenne and Frederic Cotin},
  journal={Solar Physics},
The HIgh-REsolution Gamma-ray and hard X-ray Spectrometer (HIREGS) consists of an actively shielded array of twelve liquid-nitrogen-cooled germanium detectors designed to provide unprecedented spectral resolution and narrow-line sensitivity for solar gamma-ray line observations. Two long-duration, circumpolar balloon flights of HIREGS in Antarctica (10–24 January, 1992 and 31 December, 1992–10 January, 1993) provided 90.9 and 20.4 hours of solar observations, respectively. During the… 

Constraining the Hard X-ray Properties of the Quiet Sun with New RHESSI Observations

We present new RHESSI upper limits in the 3–200 keV energy range for solar hard X-ray emission in the absence of flares and active regions, i.e., the quiet Sun, using data obtained between 2005 July

Simulation of Quiet-Sun Hard X-Rays Related to Solar Wind Superhalo Electrons

In this paper, we propose that the accelerated electrons in the quiet Sun could collide with the solar atmosphere to emit Hard X-rays (HXRs) via non-thermal bremsstrahlung, while some of these

Development and Characterization of a Fast Neutron Imaging Telescope (FNIT) for 1--20 MeV Neutrons From the Sun and Nuclear Material

We discuss the development and complete characterization of a double scatter telescope for 1--20 MeV neutrons intended for applications in solar physics and nuclear security. In high-energy solar

Major Unsolved Problems in Space Plasma Physics

There are many space plasma physics problems that are both majorand unsolved, there are other problems for which the categorization of solved or unsolved depends on one's point of view, and there are



High spectral resolution measurements of a solar flare hard X-ray burst

Observations are reported of an intense solar flare hard X-ray burst on June 27, 1980, made with a balloon-borne array of liquid nitrogen-cooled Ge detector which provided unprecedented spectral

A long-duration balloon payload for hard X-ray and gamma-ray observations of the sun

We describe a balloon payload designed to study the processes of energy release, particle acceleration, and heating of the active corona, in hard X-ray microflares and normal flares. An array of

X-ray imaging of three flares during the impulsive phase

AbstractThe impulsive phases of three flares that occurred on April 10, May 21, and November 5, 1980 are discussed. Observations were obtained with the Hard X-ray Imaging Spectrometer (HXIS) and

Solar Hard X-Ray Bursts

The major results from SMM are presented as they relate to our understanding of the energy release and particle transportation processes that lead to the high-energy X-ray aspects of solar flares.

Upper limit on the steady emission of the 2.223 MeV neutron capture γ-ray line from the Sun

Data accumulated by the Solar Maximum Mission Gamma Ray Spectrometer (GRS) have been searched for evidence of the 2.223 MeV neutron capture line from the Sun, outside the times of γ-ray-emitting

Solar gamma rays

The theory of gamma-ray production in solar flares is treated in detail. Both lines and continuum are produced. The strongest line predicted at 2.225 MeV with a width of less than 100 eV and detected

Are solar gamma-ray-line flares different from other large flares?

We reevaluate evidence indicating that gamma-ray-line (GRL) flares are fundamentally different from other large flares without detectable GRL emission and find no compelling support for this

On the proton origin of a small optical gamma-ray solar flare

The starting conditions for a small optical gamma-ray flare are examined, proposing a new scenario for the onset and development of a solar flare in which the starting or preflare conditions are

Solar hard x-ray microflares

Using balloon-borne instrumentation of very high sensitivity, we have detected approx.25 hard x-ray bursts with peak fluxes of above 7 x 10/sup -3/ (cm/sup 2/ s keV)/sup -1/ at 20 keV, in 141 minutes

Gamma-Ray Measurements of Flare-to-Flare Variations in Ambient Solar Abundances

We have measured uxes of ten narrow-ray lines in 19 X-class solar ares observed by the Solar Maximum Mission spectrometer from 1980 to 1989. These lines originate from interaction of energetic