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In association with the X28 solar flare on November 4, 2003, the muon telescope installed in Mexico City observed an enhancement in its counting rate between 19:55 and 20:00 UT. Based on a numerical simulation, we found that the entry of a high-energy solar neutron, with energy range from 0.2 to 2 GeV, is capable of producing muon flux that reach the atmospheric depth of Mexico City. Furthermore, we also found that this muon flux is of the order of 3% with respect to the average muon flux recorded by the telescope. Therefore it is very likely that the excess signals observed in the muon telescope are due to muons generated by solar neutrons in the Earth's atmosphere. [ABSTRACT FROM AUTHOR]

GRIS (Gamma and Roentgen Irradiation of the Sun) is a scientific instrument for detection of hard X-rays and gamma-rays of solar flares with the energies from 50 keV to 200 MeV and for registration of solar neutrons with energies above 30 MeV. The experiment will be performed since 2019 onboard the International Space Station. The instrument includes two spectrometers: the low energy spectrometer based on a fast scintillator with high energy resolution 3.5–4.5% at 662 keV (LaBr 3 (Ce) or CeBr 3 ) and dimensions ø7.62 × 7.62 cm, and the high energy spectrometer based on CsI(Tl) scintillator ø12 × 15 cm (which is also intended for neutron registration). The apparatus will be mounted on the oriented platform outside the Zvezda service module in 2019. Simulated response of the detectors to background radiation and to solar flares of different magnitudes and compositions obtained with GEANT4 toolkit confirms the instrument’s possibility to measure different components of the solar flares spectra: narrow gamma lines, pion decay component, etc. with a sufficient confidence due to the usage of two types of detectors. [ABSTRACT FROM AUTHOR]

Abstract: The Sun was intensely active from late October to the beginning of November 2003. A series of 11 X class solar flares occurred in NOAA regions 484, 486 and 488. Unique among this series of flares were those occurring on November 2 and 4 in which solar neutrons were observed by the ground based neutron monitors located at Mt. Chacaltaya, Bolivia and Haleakala, Hawaii, respectively. In these flares, intense emission of hard X-rays and γ-rays have been observed by the satellites. It seems that production of solar neutrons coincided with the production of the hard electromagnetic radiations of these two flares. [Copyright &y& Elsevier]

Abstract: A concept for a highly integrated High Energy Telescope with neutron detection capabilities (HETn) is under development. In the current design for implementation on a spinning platform, the instrument consists of one solid-state detector telescope with coincidence electronics. The instrument further includes a CsI scintillator that is read out by photo-diodes. A 30g plastic scintillator will offer measurement capabilities for low-energy (∼2–100MeV) solar flare neutrons that are only accessible from an inner heliospheric mission. The scintillators are wrapped in active anti-coincidence shielding. With a total weight of <900g, the instrument will provide measurements of the time profile, kinetic energy and anisotropy of 4–400MeV/n protons and heavy ions, and 0.3–15MeV electrons. This paper will introduce the objectives, the measurement concept, and the critical issues to be addressed by laboratory tests and simulations. [Copyright &y& Elsevier]

Abstract: We describe a phoswich-based detector concept for studies of low energy (∼1–10MeV) solar neutrons in the innermost heliosphere (R <∼0.5AU). The detector has applications both as a very low mass (<∼1kg), low power (∼1–2W) stand-alone instrument, and as a component to enhance the capabilities of more sophisticated instruments, for example, the fast neutron imaging telescope instrument described by Moser et al. [Moser, M.R., Flückiger, E.O., Ryan, J.M., et al. A fast neutron imaging telescope for inner heliosphere missions. Adv. Space Res., in press, this issue, doi:10.1016/j.asr.2005.03.037]. In its most basic form, the detector consists of a small volume (∼1 cm3) of fast organic scintillator completely surrounded by a slow inorganic scintillator. The dimensions of the organic scintillator are chosen to minimize multiple n–p scatterings while retaining adequate sensitivity. The inorganic scintillator provides anti-coincidence protection against energetic charged particles. A single PM tube views light from both scintillators. Pulse shape analysis identifies as potential neutrons those events where only the organic scintillator contributes to the signal. The signal size corresponds to the energy of the recoil proton from an n–p elastic scatter, on average half the energy of the incident neutron. An instrument based on this concept would provide measurements of the neutron flux and, through statistical analysis of recoil proton energies, basic information about the neutron spectrum. [Copyright &y& Elsevier]

Abstract: We describe a Fast Neutron Imaging Telescope (FNIT) that is sensitive to neutrons in the energy range 3–100MeV, optimized to study solar neutrons in the innermost heliosphere. The detection principle is based on multiple elastic neutron–proton scatterings in stacked organic scintillator layers. Plastic scintillator provides the proton target and is an efficient detector of charged particles. At the upper and lower face of each scintillator plate orthogonally oriented wavelength shifting fibers (∅∼1mm) collect and guide the scintillation light to a multi-anode photomultiplier tube (MAPMT). The relative anode signals of the MAPMT register the interaction location while the total intensity of the signal is a measure of the recoil proton energy. Elastic scattering kinematics allows one to determine direction and energy spectrum of the primary neutron flux. A performance evaluation prototype has been built, and we show results from first laboratory measurements. We then present Monte Carlo simulation results to outline the performance of an optimized design. [Copyright &y& Elsevier]