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arXiv 1007.2349astro-ph.SR
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太阳中子产生的物理学:对2007年12月31日耀斑中子的可疑探测

Physics of Solar Neutron Production: Questionable Detection of Neutrons from the 2007 December 31 Flare

Gerald H. Share, Ronald J. Murphy, Allan J. Tylka, Benz Kozlovsky, James M. Ryan, Chul Gwon

摘要:

在内日光层的航天器观测首次提供了测量1-10 MeV太阳中子的机会。我们讨论了太阳耀斑中低能中子产生的物理过程,并指出即使在相互作用粒子能量为2 MeV/核子时,也会产生能量大于10 MeV的中子。另一方面,在典型的耀斑谱中,1-10 MeV中子中的很大一部分是由>10 MeV/核子离子的相互作用产生的。我们计算逃逸中子谱的单能和幂律粒子谱在太阳的位置和观测角度的信使在其报告的检测到低能中子与2007年12月31日太阳耀斑。我们详细关注这个可疑的观测太阳中子:1。在太阳上,这个中等的M2级耀斑的加速质子的推断数量是迄今为止观测到的任何耀斑的10倍,2。“太阳”中子计数率的起始和持续时间与太阳高能粒子(SEP)的相似;作者的论点,即SEP主要由电子控制,因此不能在航天器中局部产生中子计数。相反,我们认为,太阳高能质子和α粒子,通过当地的中子生产和偶然的巧合,是大多数的“太阳中子”计数的来源。

英文摘要:

Spacecraft observations in the inner heliosphere offer the first opportunity to measure 1-10 MeV solar neutrons. We discuss the physics of low-energy neutron production in solar flares and show that, even at interacting-particle energies of 2 MeV/nucleon, neutrons with energies >10 MeV are produced. On the other hand, a significant fraction of 1-10 MeV neutrons result from interactions of >10 MeV/nucleon ions in typical flare spectra. We calculate the escaping neutron spectra for mono-energetic and power-law particle spectra at the Sun for the location and observation angle of MESSENGER at the time of its reported detection of low-energy neutrons associated with the 2007 December 31 solar flare. We detail concerns about this questionable observation of solar neutrons: 1. the inferred number of accelerated protons at the Sun for this modest M2-class flare was 10X larger than any flare observed to date, 2. the onset and duration of the 'solar' neutron count rate was similar to that of the solar energetic particles (SEPs), and 3. the authors' argument that the SEPs were dominated by electrons and so could not have produced the neutron counts locally in the spacecraft. In contrast we argue that solar energetic protons and alpha particles, through local neutron production and accidental coincidences, were the source of most of the reported 'solar-neutron' counts.

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