Validation of the neutron monitor yield function using data from AMS-02 experiment, 2011–2017. (arXiv:1904.01929v1 [physics.space-ph])
<a href="http://arxiv.org/find/physics/1/au:+Koldobskiy_S/0/1/0/all/0/1">Sergey A. Koldobskiy</a>, <a href="http://arxiv.org/find/physics/1/au:+Bindi_V/0/1/0/all/0/1">Veronica Bindi</a>, <a href="http://arxiv.org/find/physics/1/au:+Corti_C/0/1/0/all/0/1">Claudio Corti</a>, <a href="http://arxiv.org/find/physics/1/au:+Kovaltsov_G/0/1/0/all/0/1">Gennady A. Kovaltsov</a>, <a href="http://arxiv.org/find/physics/1/au:+Usoskin_I/0/1/0/all/0/1">Ilya G. Usoskin</a>
The newly published spectra of protons and helium over time directly measured
in space by the AMS-02 experiment for the period 2011–2017 provide a unique
opportunity to calibrate ground-based neutron monitors (NMs). Here, calibration
of several stable sealevel NMs (Inuvik, Apatity, Oulu, Newark, Moscow,
Hermanus, Athens) was performed using these spectra. Four modern NM yield
functions were verified: Mi13 (Mishev et al., 2013), Ma16 (Mangeard et al.,
2016), CM12 (Caballero-Lopez & Moraal, 2012) and CD00 (Clem & Dorman, 2000), on
the basis of the cosmic-ray spectra measured by AMS-02. The Mi13 yield function
was found to realistically represent the NM response to galactic cosmic rays.
CM12 yield function leads to a small skew in the solar cycle dependence of the
scaling factor. In contrast, Ma16 and CD00 yield functions tend to overestimate
the NM sensitivity to low-rigidity (<10 GV) cosmic rays. This effect may be
important for an analysis of ground level enhancements, leading to a potential
underestimate of fluxes of solar energetic particles as based on NM data. The
Mi13 yield function is recommended for quantitative analyses of NM data,
especially for ground-level enhancements. The validity the force-field
approximation was studied, and it was found that it fits well the directly
measured proton spectra, within a few % for periods of low to moderate activity
and up to ~10% for active periods. The results of this work strengthen and
validate the method of the cosmic-ray variability analysis based on the NM data
and yield-function formalism, and improves its accuracy.
The newly published spectra of protons and helium over time directly measured
in space by the AMS-02 experiment for the period 2011–2017 provide a unique
opportunity to calibrate ground-based neutron monitors (NMs). Here, calibration
of several stable sealevel NMs (Inuvik, Apatity, Oulu, Newark, Moscow,
Hermanus, Athens) was performed using these spectra. Four modern NM yield
functions were verified: Mi13 (Mishev et al., 2013), Ma16 (Mangeard et al.,
2016), CM12 (Caballero-Lopez & Moraal, 2012) and CD00 (Clem & Dorman, 2000), on
the basis of the cosmic-ray spectra measured by AMS-02. The Mi13 yield function
was found to realistically represent the NM response to galactic cosmic rays.
CM12 yield function leads to a small skew in the solar cycle dependence of the
scaling factor. In contrast, Ma16 and CD00 yield functions tend to overestimate
the NM sensitivity to low-rigidity (<10 GV) cosmic rays. This effect may be
important for an analysis of ground level enhancements, leading to a potential
underestimate of fluxes of solar energetic particles as based on NM data. The
Mi13 yield function is recommended for quantitative analyses of NM data,
especially for ground-level enhancements. The validity the force-field
approximation was studied, and it was found that it fits well the directly
measured proton spectra, within a few % for periods of low to moderate activity
and up to ~10% for active periods. The results of this work strengthen and
validate the method of the cosmic-ray variability analysis based on the NM data
and yield-function formalism, and improves its accuracy.
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