Comparison between PAMELA proton spectra and neutron monitor count rates

25 Apr 2018, 09:30
30m
Madison Hilton

Madison Hilton

1177 15th Street NW, Washington DC

Speaker

Ilya Usoskin (University of Oulu)

Description

Recently published spectra of comic ray protons measured by PAMELA instrument for the period 2006-2014 make it possible to perform a direct comparison with the neutron monitor (NM) count rates. Here we used the measured proton spectra as an input and computed, using two recent NM yield function models (Mishev et al., 2013 and Mangeard et al., 2016), the expected NM count rate. These computed count rates were systematically compared with the actual NM records. Since spectra of helium and heavier species are not presently available, we standardly considered them as a 0.3 nucleonic fraction of protons in the local interstellar spectrum (LIS). The comparison shows a good agreement between modelled and recorded NM count rates but also reveals a problem to be resolved, as the model predicts too strong dependence of the NM count rate on the level of solar modulation. This may indicate slightly underestimated contribution of high-energy cosmic rays in the NM yield function.

Authors

Ilya Usoskin (University of Oulu) Dr Gennady Kovaltsov (Ioffe Phys-Tech Institute) Sergey Koldobsky (MEPhI)

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