Helium in near Earth orbit

Abstract

The helium spectrum from 0.1 to 100 GeV/nucleon was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at altitudes near 380 km. Above the geomagnetic cutoff the spectrum is parameterized by a power law. Below the geomagnetic cutoff a second helium spectrum was observed. In the second helium spectra over the energy range 0.1 to 1.2 GeV/nucleon the flux was measured to be (6.3±0.9) x10-3(m2 sec sr)-1 and more than ninety percent of the helium was determined to be 3He (at the 90% CL). Tracing helium from the second spectrum shows that about half of the 3He travel for an extended period of time in the geomagnetic field and that they originate from restricted geographic regions similar to protons and positrons

Atmospheric neutrino flux supported by recent muon experiments

“…On the other hand it slightly exceeds the AMS helium flux [32] (with average discrepancy of about 15%). Our choice of the BESS 98 data was in particular conditioned by the fact that the power-law extrapolation of the high-energy tail of the AMS helium rigidity spectrum (∝ R −(2.74±0.02) ) [32] distinctly worse joins the world-averaged fit (∝ E −(2.64±0.02) ) [21] and even the JACEE 1-12 fit (∝ E −(2.68 +0.04 −0.06 ) ) [20]. 6 We assume that the spectra of the remaining three nuclear groups are similar to the helium spectrum,…”

“…Figure 1 shows a comparison between the BESS+JACEE fit, the data from [19,20], the fit from [21] (shaded areas) and several other experiments [22][23][24][25][26][27][28][29][30][31][32], performed in different periods of solar activity. The filled/shaded areas in fig.…”

“…The filled/shaded areas in fig. 1 represent the power-type parametrizations derived in [20,22,24,28,31,32] from the original data. The legend indicates the publication dates and (when relevant) the years of measurements.…”

The Alpha Magnetic Spectrometer (AMS) on the International Space Station: Part I – results from the test flight on the space shuttle

“…In this report we present the data collected during the ight to study the cosmic ray proton spectrum from kinetic energies of 0.1-200 GeV [37,38], the helium spectrum over the kinetic energy range 0.1-100 GeV=nucleon [39] and the spectra of electrons and positrons over the respective kinetic energy ranges of 0.2-30 GeV and 0.2-3 GeV [40], the latter range being limited by the proton background. Antiproton and deuteron spectra were measured from 0.2 to 4 GeV and from 0.09 to 0:85 GeV=nucleon.…”

Outstanding Problems in Particle Astrophysics

“…2. Data from the magnetic spectrometers BESS98 (Sanuki, et al, 2000) and AMS (Alcarez et al, 2000a) are indistinguishable on the plot for protons, although they differ somewhat for helium ( Alcarez et al, 2000b). Data from the CAPRICE spectrometer (Boezio et al, 1999) are 15-20% lower than BESS98 above 10 GeV/nucleon.…”