1. Modeling of secondary cosmic ray spectra for Solar Cycles 23
Blahoslav Pastirčák 1, Pavol Bobík 1, Karel Kudela 1, Marián Putiš 1,
Mario Bertaina 2, Kenji Shinozaki 3, Jacek Szabelski 4.
1Institute of Experimental Physics SAS, Kosice, Slovakia, 2Department of General Physics, University of Torino, Torino, Italy, 3RIKEN, Wako, Japan, 4Soltan Institute for Nuclear Studies, Lodz, Poland
Abstract: The SecondaryCR model evaluate secondary particles spectra of e−, e+, μ+, μ−, gammas, protons, neutrons, Cherenkov light etc. in the Earth atmosphere at different positions, altitudes and times during 23rd solar cycle. For evaluation of spectra at 1AU on magnetopause we use results of HelMod model [1]. Transparency of magnetosphere was obtained by GeoMag model [2] and finally secondary production in Earth magnetoshpere was simulated by Corsika package [3]. The review of SecondaryCR model results is presented.
Heliosphere and Magnetosphere model
To evaluate CR spectra above atmosphere in different periods, we use HelMod protons differential spectra at 1AU multiplied by transmission function of the magnetopshere. The transmission function [provides probability for particle from interplanetary space at 1AU to reach selected point inside magnetosphere as a function of energy and time. The trasmision functions are evaluated for energies from AMS-01 energy bins to allow multiplications with differential intensities provided by HelMod model.. H
Figure 1: Sky map of effective cutoff rigidity. Dotted circles show a 10 degrees zenith angles.
Figure 2: PCR differential intensity. Protons at 1 Aufrom HelMod model– red solid line, at the top of atmosphere – triangles, helium at the top of atmosphere – black line with squares.
Figure 3: Comparison between muons spectra for different low energy CORSIKA models and BESS LynnLake measurements. BESS muon spectra is most similar to URQMD results.
Figure 4. μ− differential spectra at Mt. Norikura. Red line with
diamonds represent a result from SCR model, black line with
circles represent BESS measurements.
Figure 5. μ− differential spectra at Mt. Norikura. Red line with
diamonds represent a result from SCR model, black line with
circles represent BESS measurements.
CORSIKA
To simulate secondary cosmic ray production in the atmosphere we use Corsika package version 7.37 with QGSJETII model for hadronic interactions at high energies and urqmd model for lower energies. Geomagnetic field at positions of
NM stations was evaluated in IGRF model [7].
To verify precision of used approach we compare muon spectrum produced by SCR model with muon spectrum measured by BESS detector [8]. BESS spectrum was measured at the top of Mt. Norikura (altitude 2770 m) in september For the same time and position we evaluate spectrum in SecondaryCR model. Obtained spectra are very simmilar however production of secondary particle by helium component of primary cosmic ray was not considered. Following results from [9] we expect a few percent additional muons from helium primaries. The production of secondary particles by other primary particles we assume be negligible.
Comparison of BESS spectrum with result of SCR model is presented at the figure 3. The both spectra has very simmilar shape and comparable intensities. Helium component will be added in future article.
Simulation for NM stations positions provide neutrons spectra for years 2001 and 2005 presented at figure 4 (left here). Neutrons intensity created by GCR at Athens station increase 7% in period from 2001 till For station Lomnicky stit intensity increase 13%, for Newark station 11% and for Oulu 11%.
References
[1] P. Bobik et al. The Astrophysical Journal (2012)
[2] P. Bobik Journal of Geophysical Research 111 (2006)
[3] D. Heck et al. CORSIKA: a Monte Carlo code to simulate extensive air showers. Forschungszentrum Karlsruhe GmbH, Karlsruhe (Germany), D Hannover, 1998.
[4]
[5] P. Bobik, K. Kudela, I. Usoskin, Proceedings of the 27th International Cosmic Ray Conference, Hamburg, 4056 (2001)
[6] R. A. Burger, M.S. Potgieter, B. Heber, J. Geophys. Res.,105, (2000)
[7] IGRF,
[8] T. Sanuki et al. Physics Letters B (2002)
[9] P. Bobik et al., Advances in Space Research (2012)
Conclusions
We combine model of secondary cosmic rays production in the Earth’s atmosphere from existing models evaluating particles transport in heliosphere and magnetosphere and Corsika model for interaction of primary cosmic rays with the atmosphere. The comparison of muon spectrum evaluated by SCR model with BESS measurement in year 1999 is presented. Neutrons spectra for solar minimum and maximum condition for four neutron monitors of NMDB network were evaluated. SCR model results in the form of catalog will be published at secondaryCR.org.