Validation of the Neutron Monitor Yield Function Using Data From AMS‐02 Experiment, 2011–2017

Abstract

The newly published spectra of protons and helium over time directly measured in space by the Alpha Magnetic Spectrometer (AMS-02) experiment for the period 2011-2017 provide a unique opportunity to calibrate ground-based neutron monitors (NMs). Here, calibration of several stable sea level NMs (Inuvik, Apatity, Oulu, Newark, Moscow, Hermanus, and Athens) was performed using these spectra. Four modern NM yield functions were verified: Mi13 (Mishev et al.

Updated Neutron‐Monitor Yield Function: Bridging Between In Situ and Ground‐Based Cosmic Ray Measurements

“…The spectra were measured for 79 Bartels rotations (BR) 27 days each, 2,426–2,506. Heavier ( ) species of GCR were included using the rigidity‐dependent scaling of helium, as proposed by Koldobskiy et al (). Thus, using these input parameters and the NM YF computed here, we calculated the theoretically expected count rates of all NM64‐type NMs in operation during the time period considered, that is, for 79 BRs.…”

“…Then the expected count rates were confronted with the actually measured count rates (corrected for the pressure and efficiency) of these NMs, for the same periods. Because of the nonideality of a NM, namely, electronic setups, very local environment (materials, electronics, and existing construction), efficiency of counter tubes, and so forth, the expected count rates are not always equal to the real ones but are typically proportional to that (see, e.g., Koldobskiy et al, ; Usoskin et al, ), via the so‐called scaling factor, which is defined as …”

“…The line depicts the best fit linear regression, which is consistent with no dependence. electronic setups, very local environment (materials, electronics, and existing construction), efficiency of counter tubes, and so forth, the expected count rates are not always equal to the real ones but are typically proportional to that (see, e.g., Koldobskiy et al, 2019;Usoskin et al, 2017), via the so-called scaling factor, which is defined as…”

“…Although (semi)empirical parameterization of latitude survey observations was used earlier to determine the YF (e.g., Caballero‐Lopez & Moraal, ; Lockwood et al, ; Nagashima et al, ), modern state‐of‐the‐art models for the YF (Clem & Dorman, ; Mangeard et al, ; Mishev et al, ) are based on Monte Carlo tools but still exhibit a degree of discrepancy between each other, especially in the low‐energy range (Koldobskiy et al, ). Comparison between direct CR spectral measurements and NM responses (Gil et al, ; Koldobskiy et al, , ) has shown that YF by Mishev et al () is most consistent with the observational data. However, this YF, as well as some other YFs, was determined for sea level, while many NMs are located at middle and high altitudes.…”

New Method of Assessment of the Integral Fluence of Solar Energetic (> 1 GV Rigidity) Particles from Neutron Monitor Data

“…We used the force-field parameterization (Caballero- Lopez and Moraal, 2004;Usoskin et al, 2005) of the GCR spectra near Earth based on an updated local interstellar spectrum for protons (Vos and Potgieter, 2015) as constrained by recent measurements of Voyager (Stone et al, 2013) and PAMELA (Adriani et al, 2013) in-situ data. The methodology is described elsewhere (Koldobskiy, Kovaltsov, and Usoskin, 2018a;Koldobskiy et al, 2019). The values of the modulation potential φ in the force-field parameterization were calculated for each GLE pre-increase interval from polar NM data, using the methodology described in Usoskin et al (2017).…”