Geomagnetically trapped light isotopes observed with the detector NINA

Abstract

[1] The detector New Instrument for Nuclear Analysis (NINA) aboard the satellite Resurs-01-N4 detected hydrogen and helium isotopes geomagnetically trapped, while crossing the South Atlantic Anomaly. Deuterium and tritium at L shell < 1.2 were unambiguously recognized. The 3 He and 4 He power law spectra, reconstructed at L shell = 1.2 and B < 0.22 G, have indices equal to 2.30 ± 0.08 in the energy range 12-50 MeV nucleon À1 and 3.4 ± 0.2 in 10-30 MeV nucleon À1 , respectively. The measured 3 He/ 4 He ratio and the reconstructed deuterium profile as a function of L shell bring one to the conclusion that the main source of radiation belt light isotopes at Resurs altitudes ($800 km) and for energy greater than 10 MeV nucleon À1 is the interaction of trapped protons with residual atmospheric helium.

Pitch angle distribution of trapped energetic protons and helium isotope nuclei measured along the Resurs-01 No. 4 LEO satellite

“…The 3 He spectrum is fitted by a power law with an index equal to 2.6±0.3 in the energy range 12-40 MeV/n, while 4 He has a spectral index of 3.0±0.5 in the range 10-25 MeV/n. These indexes are coincided with the values previously received for a more broad (B, L) bin (Bakaldin et al, 2002a). The calculated spectra of trapped 3 He (solid curves) and 4 He (dotted curves) isotopes at L-shell 1.2 are also presented in Fig.…”

“…Due to the isotope identification ability of the NINA instrument, we could measure the isotope composition of the helium radiation belt component (Bakaldin et al, 2002a). It is believed that this component results from the nuclear interaction of primary radiation and the upper atmosphere near the inner edge of the inner radiation belt (L<1.3) (Pugacheva et al, 1998;Selesnick and Mewaldt, 1996;Galper et al, 2003).…”

“…Data also include particles collected during solar energetic particle events, because even in conditions of intense solar activity, the fluxes measured by NINA in the inner radiation belt remained practically constant. The background evaluation and systematic errors estimation for events detected by the NINA instrument were presented in Bakaldin et al (2002a) and Bidoli et al (2001), respectively. The intensity contribution of background events and systematic errors does not exceed several percents.…”

The measurements of light high-energy ions in NINA-2 experiment

“…8a the NINA-2 instrument could detect particles of trapped origin, as reported by Bakaldin et al (2002a) in the South Atlantic Anomaly (SAA). But for long-range events in the SAA (Fig.…”

“…The experimental measurements for contained particles of solar, galactic and trapped origin were presented in Bakaldin et al (2002b), Bidoli et al (2001) and Bakaldin et al (2002a), respectively. In this section we present the adapted dE/dx-E methods to recognize long-range particle species and to determine their energy spectrum.…”