Solar energetic particle event with 3He/4He>1

• Published in: Nature (London) 1974-12, Vol.252 (5483), p.460-462
• Main Authors: BALASUBRAHMANYAN, V. K., SERLEMITSOS, A. T.
• Format: Article
• Language: English
• Subjects: Humanities and Social Sciences; letter; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/252460b0

OBSERVATIONS of γ rays and the short lived isotope 3 H provide evidence for the occurrence of nuclear reactions by high energy particles accelerated in solar flares 1,2 . Stable isotopes such as 2 H and 3 He should also be produced in these reactions. Solar 3 He particles were first detected by Hsieh and Simpson 3 . In the energy range 10 to 100 MeV per nucleon they obtained 3 He/ 4 He = (2.1±0.4) × 10 −2 by summing over seven solar particle events. Garrard et al. 4 and Anglin et al. 5 have reported that 3 He/ 4 He was highly variable from event to event. (Table 1). In the ‘ 3 He-rich events’, 2 H and 3 H were not detected and the resulting upper limits were much less than expected from the theory of nuclear reactions 6 . These events were small, and the number of 3 He particles observed was low (∼ 70). This anomalous production of 3 He should provide new insight into the acceleration and confinement process of energetic particles in solar flares.