Ionizing particle fluxes in the near-ground atmosphere BAZILEVSKAYA G.A., KRAINEV M.B., KVASHNIN A.N., MAKHMUTOV V.S., STOZHKOV Y.I., SVIRZHEVSKAYA A.K., SVIRZHEVSKY N.S. Lebedev Physical Institute, RAS, Leninsky prospect, 53, 119991, Moscow, Russia

Motivation and goal Ionization in the near-ground atmosphere is of interest for the cosmic ray physics and mechanisms of weather formation. There is a discrepancy between the results of charged particle fluxes observation and simulation near the ground. We try to understand the source of this discrepancy.

Long-term cosmic ray observations in the Earth’s atmosphere by Lebedev Physical Institute (Russia) Measurements with omnidirectional Geiger tubes and with Geiger tube telescopes beginning from 1957 Light balloon launchings several times a week at polar (Murmansk, Arctica, and Mirny, Antarctica) and mid-latitudes (Moscow region). Latitudinal surveys during sea expeditions. Here we use data of 1987 sea survey. Occasional measurements with a “B1” device with high statistics at polar (Arkhangelsk region) and mid-latitudes (Saratov region).

Radio-sound detectors

Stratos\Ser5708_1.xls

Main latitude surveys 19621965 19681969 19701971 19751976 19791980 19861987 Stratos\ISSI2007\MORSK871h.xls After Golenkov, A. E., Svirzhevskaya, A. K., Svirzhevsky, N. S., and Stozhkov, Yu. I.: 1990, Proc. 21st Int. Cosmic Ray Conf., Adelaide 7, 1417.

Stratos\photon\ФЭУ из Дис.xls

L. Desorgher et al., Int.J.Mod Phys. A, 20(29),6802-6804, 2005

Makhmutov , 2009

Discrepancy between the observed and simulated particle fluxes in the near-ground level (Bazilevskaya et al., 31 ICRC, Lodz, 2009) 13-14 km Cosmic ray fluxes and CRII normalized at averages for the whole period of observations 2.3 km Cosmic ray induced ionization: Usoskin et al. Acta Geophysica, 57(1), 88-101, DOI: 10.2478/s11600-008-0019-9, 2009.

Assumption: Ionizing radiation in the near-ground level (below 3 km – 700 g/cm2) Cosmic rays from the atmosphere Natural radioactivity

Approach A telescope is not sensitive to radioactivity. Sea water is much less radioactive than ground or rock. In Mirny, Antarctica, radioactivity is lower because the ground is mostly covered by glacier.

Data used Data of single Geiger counters Data of telescopes: Moscow and Murmansk regions 07.1957-2010. Mirny observatory, Antarctica, 03.1963-2009. Sea survey 1987. Arkhangelsk and Saratov regions, Set of 240 Geiger counters and a NaI scintillator (1970s, Charakhchyan et al., 1975, in Russian). Data of telescopes: Moscow and Murmansk regions, Mirny observatory, 1964-2009.

Stratos\Near_ground\sea_surv_1987.xls It is rightful to average the data of observations at various latitudes (various geomagnetic cutoffs) over sea at atmospheric pressures >400 g/cm2 (altitude < 7 km).

Stratos\Near_ground\compar_to_GEANT.xls

Stratos\STR\STR_season.xls

Ratio of count rates of an omnidirectional counter and a telescope Ratio for cosmic rays

There is a transition effect while cosmic ray particles pass through a boundary between air and soil (rock) because differences in the critical energy for electrons in these media. There is virtually no transition effect for cosmic rays passing from air to water.

Ionizing radiation in the near-ground level (below 3 km – 700 g/cm2) Cosmic rays from the atmosphere Natural radioactivity effect from the air-ground transition

Difference between observational data omnidirectional component) and GEANT 4 results (Desorgher et al., 2005): Contribution from the transition effect; Contribution from the natural radioactivity.

Difference between the observed X-ray fluxes at Arkhangelsk region and Mirny (Antarctida): 3. Contribution from the transition effect; 4. Contribution from the natural radioactivity.

Conclusion Difference between GEANT 4 results of Desorgher et al., 2005, and results of Makhmutov, 2009 is ~ 25% - need tuning. Divergence of results of GEANT 4 (Desorgher et al, 2005) from observations of omnidirectional fluxes of charged particles over ground begins at ~800 g/cm2 (altitude of ~2.1 km) and reaches ~30% at ~980 g/cm2 (altitude ~450 m). This is due to transition effect of cosmic rays between air and ground. Below ~ 500 m (pressure > ~970 g/cm2) the divergence is growing due to contribution of natural radioactivity which depends on location and changes with time. at

Conclusion (continuation) The observational results of omnidirectional charged particle fluxes over sea surface are virtually free from the transition effect. They are in reasonable agreement with the results of GEANT 4 simulation (Desorgher et al., 2005)

Conclusion (continuation) The results of X-ray observations over the ground surface demonstrate contributions from the CR transition effect (air-ground) and from natural radioactivity. The CR transition effect should be included into GEANT 4 simulations.

Thank you for your attention!

Измерения сцинтил. счетчиком у берегов Австралии на самолете. 916 811 715 630 г/см2 Измерения сцинтил. счетчиком у берегов Австралии на самолете. 5.06.59 – после 5 дней ветра с моря, остальные дни – ветер с континента. J.A. Walburton et al., Nature, 207(4993), 181, 1965

Stations of the cosmic ray measurements in the atmosphere Site of balloon launching Geographical coordinates Cutoff rigidity, GV McIlwain’s L-parameter Period of observations Olenya, Apatity (Murmansk region) 68º57'N 33º03'E 0.6 5.5 1957 – present time Dolgoprudny, Moscow region 5556'N 3731'E 2.35 2.6 Alma-Ata, Kazakhstan 4315'N 7655'E 6.7 1.8 1962- 1991 Mirny, Antarctica 6634'S 92º55'E 0.03 ~20 1963 –

The results of observations with a set of 240 Geiger tubes on the large-volume balloons (in Russian: А.Н. Чарахчьян, Г.А. Базилевская, А.Ф. Красоткин, Т.Н. Чарахчьян. Геомагнетизм и аэрономия, 15 (2), 197-202, 1975)