Measurements of Cross Sections Relevant to γ-Ray Line Astronomy

Lesko, K. T.; Norman, E. B.; Larimer, R. M.; Crane, S. G.

doi:10.1007/978-94-009-4025-3_24

Cited by 1 publication

(1 citation statement)

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“…This line can also be produced from elements other than Mg (e.g., Al and Si), but the GRS sensor is surrounded by a Mg housing, and other estimates suggest that Mg will likely contribute at least 50% of the overall neutron reactions [ Reedy , ]. Cross sections for the proton‐induced Mg(p,xγ 1635 ) reactions have a mean value of ~150 mb for proton energies above the reaction threshold and less than 45 MeV [ Lesko et al , ]. Thus, the gamma‐ray production per incident source particle will be approximately a factor of 5 larger for the (n,n′γ 1369 ) neutrons than for the (p,xγ 1635 ) protons.…”

Section: Evidence For a Solar Origin Of Neutrons Detected At 15:45 Utcmentioning

confidence: 99%

Detection and characterization of 0.5–8 MeV neutrons near Mercury: Evidence for a solar origin

et al. 2014

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[1] Data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) Neutron Spectrometer (NS) have been used to identify energetic neutrons (0.5-8 MeV energy) associated with solar events that occurred on 4 June 2011. Multiple lines of evidence, including measurements from the NS and the MESSENGER Gamma-Ray Spectrometer, indicate that the detected neutrons have a solar origin. This evidence includes a lack of time-coincident, energetic (>45 MeV) charged particles that could otherwise create local neutrons from nearby spacecraft material and a lack of proton-induced gamma rays that should be seen if energetic protons were present. NS data cannot rule out the presence of lower-energy ions (<30 MeV) that can produce local neutrons. However, the ion spectral shape required to produce the measured neutron count rate locally is softer than any known ion spectral shape. The neutron energy spectrum shows a relative enhancement in the energy range 0.8-3 MeV compared with cosmic-ray-generated neutrons from the spacecraft or Mercury. The spectral shape of the measured neutron fluence spectrum is consistent with a previously modeled fluence spectrum of neutrons that originate at the Sun and are propagated through the MESSENGER spacecraft to the NS. These measurements provide strong evidence for a solar origin of the detected neutrons and suggest that a large number of low-energy threshold ion evaporation reactions were taking place on the Sun during the neutron event.

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Section: Evidence For a Solar Origin Of Neutrons Detected At 15:45 Utcmentioning

confidence: 99%