The CARPET cosmic ray detector was installed on April 2006 at CASLEO (Complejo Astronmico El Leoncito) at the Argentinean Andes (31.8S, 69.3W, 2550 m, Rc=9.65 GV). This instrument was developed within an international cooperation between the Lebedev Physical Institute RAS (LPI; Russia), the Centro de Radio Astronomia e Astrofsica Mackenzie (CRAAM; Brazil) and the Complejo Astronmico el Leoncito (CASLEO; Argentina). In this paper we present results of analysis of cosmic ray variations recorded by the CARPET during increased solar flare activity in 2011-2012. Available solar and interplanetary medium observational data obtained onboard GOES, FERMI, ISS, as well as cosmic ray measurements by ground-based neutron monitor network were also used in the present analysis.Fil: Makhmutov, V.. Lebedev Physical Institute; Rusia. Universidade Presbiteriana Mackenzie; BrasilFil: Raulin, J. P.. Universidade Presbiteriana Mackenzie; BrasilFil: De Mendonca, R. R. S.. National Institute for Space Research; BrasilFil: Bazilevskaya, G. A.. Lebedev Physical Institute; RusiaFil: Correia, E.. Universidade Presbiteriana Mackenzie; Brasil. National Institute for Space Research; BrasilFil: Kaufmann, Pierre. Universidade Presbiteriana Mackenzie; BrasilFil: Marun, Adolfo Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Complejo Astronómico "El Leoncito". Universidad Nacional de Córdoba. Complejo Astronómico "El Leoncito". Universidad Nacional de la Plata. Complejo Astronómico "El Leoncito". Universidad Nacional de San Juan. Complejo Astronómico "El Leoncito"; ArgentinaFil: Fernandez, German Enzo Leonel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Complejo Astronómico "El Leoncito". Universidad Nacional de Córdoba. Complejo Astronómico "El Leoncito". Universidad Nacional de la Plata. Complejo Astronómico "El Leoncito". Universidad Nacional de San Juan. Complejo Astronómico "El Leoncito"; ArgentinaFil: Echer, E.. National Institute for Space Research; Brasi

Bazilevskaya, G. A.

Correia, E.

De Mendonca, R. R. S.

Echer, E.

Fernandez, German Enzo Leonel

Kaufmann, Pierre

Makhmutov, V.

Marun, Adolfo Hector

Raulin, J. P.

Journal of Physics Conference Series

English

LAReferencia - Red Federada de Repositorios Institucionales de Publicaciones Científicas Latinoamericanas

Journal of Physics: Conference SeriesAnalysis of cosmic ray variations observed by theCARPET in association with solar flares in 2011-2012To cite this article: V Makhmutov et al 2013 J. Phys.: Conf. Ser. 409 012185 View the article online for updates and enhancements.Related contentTransport of solar protons through theatmosphere during GLEE A Maurchev, Yu V Balabin, E VVashenyuk et al.-Determination of Acceleration Time ofProtons Responsible for the GLE OnsetV Kurt, B Yushkov, A Belov et al.-Computations of cosmic ray propagation inthe Earth's atmosphere, towards a GLEanalysisA Mishev and I Usoskin-Recent citationsProton activity of the Sun in current solarcycle 24Chuan Li et al-Mid- and low-latitude response of theionosphere to solar proton events onJanuary 2012E Correia et al-This content was downloaded from IP address 143.0.168.2 on 06/06/2018 at 13:07Analysis of cosmic ray variations observed by theCARPET in association with solar flares in 2011-2012V Makhmutov1,2, J-P Raulin2, R R S De Mendonca3, G ABazilevskaya1, E Correia2,3, P Kaufmann2, A Marun4, G Fernandez4and E Echer31 Lebedev Physical Institute RAS, Moscow, Russia2 Universidade Presbiteriana Mackenzie, EE, CRAAM, Sao Paulo, Brazil3 National Institute for Space Research, INPE, Brazil4 Complejo Astronmico el Leoncito, CASLEO, ArgentinaE-mail: makhmutv@sci.lebedev.ruAbstract. The CARPET cosmic ray detector was installed on April 2006 at CASLEO(Complejo Astronmico El Leoncito) at the Argentinean Andes (31.8S, 69.3W, 2550 m, Rc=9.65GV). This instrument was developed within an international cooperation between the LebedevPhysical Institute RAS (LPI; Russia), the Centro de Radio Astronomia e Astrofsica Mackenzie(CRAAM; Brazil) and the Complejo Astronmico el Leoncito (CASLEO; Argentina). Inthis paper we present results of analysis of cosmic ray variations recorded by the CARPETduring increased solar flare activity in 2011-2012. Available solar and interplanetary mediumobservational data obtained onboard GOES, FERMI, ISS, as well as cosmic ray measurementsby ground-based neutron monitor network were also used in the present analysis.1. IntroductionThe CARPET cosmic ray detector was installed on April 2006 at Complejo AstronomicoEl Leoncito (CASLEO) in the Argentinean Andes at an altitude of 2550 m (31.8S, 69.3W).The CARPET instrument (based on 240 Geiger tubes) was developed within an internationalcooperation between the CRAAM, the CASLEO and the LPI RAS [1]. Description of theCARPET cosmic ray detector is reported in [1,2]. Its main features are:(1) the CARPET records include 3 channels data with 0.5 s time resolution. The UP andLOW channels data are records of the total fluxes of >200 keV electrons and positrons, >5MeV protons, >1.5 MeV muons and >20 keV γ-rays (the latter with an efficiency <1 %). Thetelescope channel (TEL) counts number of particles crossing through both UP and LOW layersof counters: >5 MeV electrons, >30 MeV protons and >15.5 MeV muons.(2) in contrast to the Neutron Monitor (NM) mesurements our detector is sensitive to thelow energy secondary component of cosmic rays produced by primary galactic or solar cosmicray flux in the Earth’s atmosphere.To calculate vertical geomagnetic cutoff rigidity (Rc) at the CARPET location we used amethod proposed by Nymmik et al. [3]. We obtained Rc=9.65 GV for quiet geomagneticconditions and Rc=9.0 GV during geomagnetic disturbances (for Kp=4).During over six years of observations a large number of cosmic ray variations related to rainprecipitations and surface atmospheric electric field changes were recorded [1,2]. In previous23rd European Cosmic Ray Symposium (and 32nd Russian Cosmic Ray Conference) IOP PublishingJournal of Physics: Conference Series 409 (2013) 012185 doi:10.1088/1742-6596/409/1/012185Published under licence by IOP Publishing Ltd 1studies atmospheric effects in the CARPET detector records were analyzed. As a result thebarometric and temperature correction coefficients were estimated [2].Solar flare activity has increased in 2010-2012 which corresponds to the rising phase of the24th solar activity cycle. Several significant solar flares were detected during this period, whichproduced 11 Solar Energetic Particle events detected onboard GOES satellites [4]. Only oneGLE was observed in the current solar cycle (17 May 2012).In this paper we discuss the results of the analysis of cosmic ray variations observed by theCARPET detector on March 2011 and on January 2012. We concentrate on the possible solarflare effects observed by the CARPET on 7 March, 2011 and on 23 January, 2012.2. Experimental data and discussion2.1. Solar flare on 7 March 2011The solar proton event on 7 March 2011 was associated with a M3.7 flare from active regionNOAA 11164 located at N23W50 [4]. Figure 1 shows several dynamic features of this event.Panel A and B compare cosmic ray records in TEL channel of the CARPET and >50 MeVproton flux variations observed onboard GOES-13. High-energy solar neutron bursts were alsorecorded by NEM-FIB detector onboard International Space Station (ISS), and their arrival timedistribution is shown in panel C [6]. Panel D shows 12-25 keV X-ray solar bursts recorded byFERMI-GBM monitor and 100-300 keV X-ray solar burst observed by RHESSI [4,7]. Trianglesshow Start-Maximum-End time of the bursts originated from NOAA 11164. Heights of trianglescorrespond to the logarithm of total counts detected during these bursts. And finally, the solar0.5-4 Å X-ray flux recorded on board GOES-13 is presented on panel E [4].From the analysis of available experimental data which are presented in Figure 1 we pointout that:(1) the solar flare 0.5-4Å X-ray emission on 7 March 2011 started at 19:40 UT and reached itspeak flux around 20:12 UT (panel E). During this time few hard X-ray bursts were also detectedby the Fermi-GBM and RHESSI instruments (panel D). Finally, long-lasting >100 MeV γ-rayemission was observed for more than 12 hours [8]. Appearance of energetic solar neutrons wasdetected around maximum of X-ray emission (panel C). This is a direct indication of the presenceof high-energy solar protons at the flare site. Some of these protons can interact within solaratmosphere producing neutrons, while other protons can be ejected into interplanetary spaceand detected by available cosmic ray instruments in space and at ground level.(2) the CARPET’s count incerase in TEL channel was observed during ∼20:10-21:40 UT ata statistically significant level of 3-10 r.m.s. Also, we point out that simultaneously statisticallysignificant increase of counts was detected in UP and LOW channels of the CARPET.(3) the GOES-13 records only show an increase of proton flux in low energy channels (<100MeV), which starts on ∼21:30 UT. Evidently, there is a delay in arrival time of these low energyprotons in comparison to high-energy protons detected by the CARPET after ∼20:10 UT.Bearing in mind that geomagnetic cutoff rigidity at the CARPET location is Rc=9.6 GV itmeans that the observed CARPET count rate increases may be produced by cascade of secondaryparticles originated from high-energy solar protons (E≥9 GeV) in the Earth‘s atmosphere. Weunderstand that this hypothesis needs a careful and accurate verification, i.e. estimation ofpossible proton fluxes, energy spectra and expected response of the CARPET and NMs.4) we note, by using the NM Data Base facilities (NMDB, [9]), that the network records on 7March 2011 do not show any clear increase associated with the present flare. No ground basedNM increase (GLE) was reported yet in association to this solar flare [5].2.2. Solar flare on 23 January 2012This event was associated with a M8.7 solar flare which started at ∼03:30 UT on 23 January2012 in active region NOAA 11402 (N28W20).23rd European Cosmic Ray Symposium (and 32nd Russian Cosmic Ray Conference) IOP PublishingJournal of Physics: Conference Series 409 (2013) 012185 doi:10.1088/1742-6596/409/1/0121852Figure 1. Solar flare event on March 7, 2011.Panel A: 5 min TEL channel records of theCARPET. Vertical red bar at left shows 3r.m.s of the data during preflare period (19-20 UT). B: time profile of > 50 MeV protonflux (p/cm2·s·sr) as recorded onboard GOES-13 [4]. C: solar neutron observations by NEM-FIB detector onboard ISS [6]; D: FERMI-GBM (12-25 keV) and RHESSI (100-300 keV)solar burst observations [7]. E: solar X-rayflux (W/m2) recorded on board GOES-13 [4].Figure 2. Solar flare event on January 23,2012. Panel A: 5 min TEL channel recordsof the CARPET. Vertical red bar at leftshows 3 r.m.s of the data during preflareperiod 0-3 UT. Panel B and C: time profilesof proton flux (p/cm2·s·sr·MeV) in energychannels 110-900 MeV and 350-420 MeV,recorded onboard GOES-15 [4]. Panel Dpresents X-ray solar flux (W/m2) variationsdetected onboard GOES-15 [4].Figure 2 presents several experimental time profiles for the 23 January 2012 event. Panel Ashows 5 min cosmic ray records in TEL channel of the CARPET. We note a very significantincrease (∼3-7 r.m.s) of TEL counts between 03:40 and 08:00 UT. Panel B and C show 110-900MeV and 350-420 MeV proton flux variations observed by GOES-15. Also, the Fermi-LATinstrument, detected increased γ-ray emission (E>100 MeV) from the Sun between 00:00 UTand 18:37 UT [10].This event was recorded in 8 particle channels (energy range E=15-900 MeV) by GOES-15sensors. Then we can estimate a solar proton energy spectrum between 5 and 8 UT witha power law form as J(E)= 3·107·E−3.9(p/(cm2·s·sr·MeV)) (1) in the 100-900 MeV energyrange. To evaluate the expected flux of secondaries at the CARPET device location, we havesimulated solar proton transport through the Earth’s atmosphere. The simalations were based23rd European Cosmic Ray Symposium (and 32nd Russian Cosmic Ray Conference) IOP PublishingJournal of Physics: Conference Series 409 (2013) 012185 doi:10.1088/1742-6596/409/1/0121853on PLANETOCOSMICS/Geant4 code [11-13]. In the present simulations we used the spectralform (1), extended up to 15 GeV, as the first iteration step. Finally, we deduced a protonspectrum at the top of the Earth‘s atmosphere as J(E)=1.5·104·E−2.7±0.5(p/(cm2·s·sr·MeV))in the energy range 9-15 GeV, which fits well the increase detected by the CARPET. Thisspectrum is unusually hard for this energy range and may be indicative of special conditions inthe acceleration region.3. SummaryAs a peliminary result of the analysis of the CARPET cosmic ray detector records on March,2011 and January, 2012, we conclude: (1) statistically significant increases were detected during∼20:10-21:30 UT on 7 March 2011 and during ∼03:30-08:00 UT on 23 January 2012. (2) theseincreases are indications of the long-lasting presence of high-energy solar protons (E≥9 GeV)with unusually hard spectrum entering into the Earth‘s atmosphere. Independent results ofthe analysis of VLF propagation characterstics data and riometer records during these eventssupport this conclusion (see paper [14] for details).The observed CARPET excesses are therefore indicative of high-energy processes occurringon the Sun in magnetized environment, initiated by energetic protons, and producing subsequentproducts as high-energy electrons, positrons, pions and photons. Therefore, comparison withthe Submillimeter Solar Telescope (SST) records at 212 and 405 GHz during solar flares, will becrucial to better understand these processes. Unfortunately, during the 07 March 2011 and 23January 2012 solar events, no SST data are available because of calibration tasks and nighttimehours, respectively.Finally, we note that a more careful analysis of the NMDB records is needed in order to geta final conclusion on the presence or not of solar flare effects in the form of GLEs during theseevents.AcknowledgmentsAuthors wish to thank partial support from Brazilian agencies FAPESP (contracts 2011/09700-0, 2011/24117-9), Program N-22 of the Presidium RAS, CNPq (contract 305655/2010-8),CNPq/PROANTAR (contract 0520186/06-0 and 556872/2009-6). We thank to Profs. R.A.Nymmik and B.Yu. Yushkov for their help.References[1] De Mendonca R, Raulin J-P, Makhmutov V, Stozhkov Y et al 2009 Bull.RAS 73(3) 404[2] De Mendonca R, Raulin J-P, Bertoni F, Echer E, Makhmutov V et al 2011 JASTP 73 1410[3] Nymmik R A, Panasyuk M I, Petrukhin V V, Yushkov B Yu 2009 Cosmic Res. 47 191[4] http://www.swpc.noaa.gov/[5] http://cr0.izmiran.ru/GLE-AlertAndProfilesPrognosing/[6] Koga K, Goka T, Matsumoto H, Obara T et al 2011 Proc. 32nd ICRC 10 166[7] http://hesperia.gsfc.nasa.gov/fermi-solar/[8] Allafort A, Gigliletto N, Omodei N, Takahashi H, Tanaka Y 2011 Proc. 32nd ICRC 10 113[9] http://www.nmdb.eu/[10] Tanaka Y T, Omodei N, Giglietto N et al 2012 http://www.astronomerstelegram.org/?read=3886[11] Agostinelli S, Allison J, Amako K et al 2003 Nuclear Instr. and Meth. A506 250[12] Desorgher L 2005 PLANETOCOSMICS. Software User Manual[13] Makhmutov V, Desorgher L, Bazilevskaya G et al 2007 AdSR 39 1460[14] Correia E, Makhmutov V and Raulin J-P 2012 J. Phys.: Conf. Series this volume23rd European Cosmic Ray Symposium (and 32nd Russian Cosmic Ray Conference) IOP PublishingJournal of Physics: Conference Series 409 (2013) 012185 doi:10.1088/1742-6596/409/1/0121854

Analysis of cosmic ray variations observed by the CARPET in association with solar flares in 2011-2012

V Makhmutov

J-P Raulin

R R S De Mendonca

G A Bazilevskaya

E Correia

P Kaufmann

A Marun

G Fernandez

E Echer

Crossref

CONICET Digital

Journal of Physics: Conference SeriesAnalysis of cosmic ray variations observed by theCARPET in association with solar flares in 2011-2012To cite this article: V Makhmutov et al 2013 J. Phys.: Conf. Ser. 409 012185 View the article online for updates and enhancements.Related contentTransport of solar protons through theatmosphere during GLEE A Maurchev, Yu V Balabin, E VVashenyuk et al.-Determination of Acceleration Time ofProtons Responsible for the GLE OnsetV Kurt, B Yushkov, A Belov et al.-Computations of cosmic ray propagation inthe Earth's atmosphere, towards a GLEanalysisA Mishev and I Usoskin-Recent citationsProton activity of the Sun in current solarcycle 24Chuan Li et al-Mid- and low-latitude response of theionosphere to solar proton events onJanuary 2012E Correia et al-This content was downloaded from IP address 143.0.168.2 on 06/06/2018 at 13:07Analysis of cosmic ray variations observed by theCARPET in association with solar ares in 2011-2012V Makhmutov1;2, J-P Raulin2, R R S De Mendonca3, G ABazilevskaya1, E Correia2;3, P Kaufmann2, A Marun4, G Fernandez4and E Echer31 Lebedev Physical Institute RAS, Moscow, Russia2 Universidade Presbiteriana Mackenzie, EE, CRAAM, Sao Paulo, Brazil3 National Institute for Space Research, INPE, Brazil4 Complejo Astronmico el Leoncito, CASLEO, ArgentinaE-mail: makhmutv@sci.lebedev.ruAbstract. The CARPET cosmic ray detector was installed on April 2006 at CASLEO(Complejo Astronmico El Leoncito) at the Argentinean Andes (31.8S, 69.3W, 2550 m, Rc=9.65GV). This instrument was developed within an international cooperation between the LebedevPhysical Institute RAS (LPI; Russia), the Centro de Radio Astronomia e Astrofsica Mackenzie(CRAAM; Brazil) and the Complejo Astronmico el Leoncito (CASLEO; Argentina). Inthis paper we present results of analysis of cosmic ray variations recorded by the CARPETduring increased solar are activity in 2011-2012. Available solar and interplanetary mediumobservational data obtained onboard GOES, FERMI, ISS, as well as cosmic ray measurementsby ground-based neutron monitor network were also used in the present analysis.1. IntroductionThe CARPET cosmic ray detector was installed on April 2006 at Complejo AstronomicoEl Leoncito (CASLEO) in the Argentinean Andes at an altitude of 2550 m (31.8S, 69.3W).The CARPET instrument (based on 240 Geiger tubes) was developed within an internationalcooperation between the CRAAM, the CASLEO and the LPI RAS [1]. Description of theCARPET cosmic ray detector is reported in [1,2]. Its main features are:(1) the CARPET records include 3 channels data with 0.5 s time resolution. The UP andLOW channels data are records of the total uxes of >200 keV electrons and positrons, >5MeV protons, >1.5 MeV muons and >20 keV -rays (the latter with an eciency <1 %). Thetelescope channel (TEL) counts number of particles crossing through both UP and LOW layersof counters: >5 MeV electrons, >30 MeV protons and >15.5 MeV muons.(2) in contrast to the Neutron Monitor (NM) mesurements our detector is sensitive to thelow energy secondary component of cosmic rays produced by primary galactic or solar cosmicray ux in the Earth's atmosphere.To calculate vertical geomagnetic cuto rigidity (Rc) at the CARPET location we used amethod proposed by Nymmik et al. [3]. We obtained Rc=9.65 GV for quiet geomagneticconditions and Rc=9.0 GV during geomagnetic disturbances (for Kp=4).During over six years of observations a large number of cosmic ray variations related to rainprecipitations and surface atmospheric electric eld changes were recorded [1,2]. In previous23rd European Cosmic Ray Symposium (and 32nd Russian Cosmic Ray Conference) IOP PublishingJournal of Physics: Conference Series 409 (2013) 012185 doi:10.1088/1742-6596/409/1/012185Published under licence by IOP Publishing Ltd 1studies atmospheric eects in the CARPET detector records were analyzed. As a result thebarometric and temperature correction coecients were estimated [2].Solar are activity has increased in 2010-2012 which corresponds to the rising phase of the24th solar activity cycle. Several signicant solar ares were detected during this period, whichproduced 11 Solar Energetic Particle events detected onboard GOES satellites [4]. Only oneGLE was observed in the current solar cycle (17 May 2012).In this paper we discuss the results of the analysis of cosmic ray variations observed by theCARPET detector on March 2011 and on January 2012. We concentrate on the possible solarare eects observed by the CARPET on 7 March, 2011 and on 23 January, 2012.2. Experimental data and discussion2.1. Solar are on 7 March 2011The solar proton event on 7 March 2011 was associated with a M3.7 are from active regionNOAA 11164 located at N23W50 [4]. Figure 1 shows several dynamic features of this event.Panel A and B compare cosmic ray records in TEL channel of the CARPET and >50 MeVproton ux variations observed onboard GOES-13. High-energy solar neutron bursts were alsorecorded by NEM-FIB detector onboard International Space Station (ISS), and their arrival timedistribution is shown in panel C [6]. Panel D shows 12-25 keV X-ray solar bursts recorded byFERMI-GBM monitor and 100-300 keV X-ray solar burst observed by RHESSI [4,7]. Trianglesshow Start-Maximum-End time of the bursts originated from NOAA 11164. Heights of trianglescorrespond to the logarithm of total counts detected during these bursts. And nally, the solar0.5-4 A X-ray ux recorded on board GOES-13 is presented on panel E [4].From the analysis of available experimental data which are presented in Figure 1 we pointout that:(1) the solar are 0.5-4A X-ray emission on 7 March 2011 started at 19:40 UT and reached itspeak ux around 20:12 UT (panel E). During this time few hard X-ray bursts were also detectedby the Fermi-GBM and RHESSI instruments (panel D). Finally, long-lasting >100 MeV -rayemission was observed for more than 12 hours [8]. Appearance of energetic solar neutrons wasdetected around maximum of X-ray emission (panel C). This is a direct indication of the presenceof high-energy solar protons at the are site. Some of these protons can interact within solaratmosphere producing neutrons, while other protons can be ejected into interplanetary spaceand detected by available cosmic ray instruments in space and at ground level.(2) the CARPET's count incerase in TEL channel was observed during 20:10-21:40 UT ata statistically signicant level of 3-10 r.m.s. Also, we point out that simultaneously statisticallysignicant increase of counts was detected in UP and LOW channels of the CARPET.(3) the GOES-13 records only show an increase of proton ux in low energy channels (<100MeV), which starts on 21:30 UT. Evidently, there is a delay in arrival time of these low energyprotons in comparison to high-energy protons detected by the CARPET after 20:10 UT.Bearing in mind that geomagnetic cuto rigidity at the CARPET location is Rc=9.6 GV itmeans that the observed CARPET count rate increases may be produced by cascade of secondaryparticles originated from high-energy solar protons (E9 GeV) in the Earth`s atmosphere. Weunderstand that this hypothesis needs a careful and accurate verication, i.e. estimation ofpossible proton uxes, energy spectra and expected response of the CARPET and NMs.4) we note, by using the NM Data Base facilities (NMDB, [9]), that the network records on 7March 2011 do not show any clear increase associated with the present are. No ground basedNM increase (GLE) was reported yet in association to this solar are [5].2.2. Solar are on 23 January 2012This event was associated with a M8.7 solar are which started at 03:30 UT on 23 January2012 in active region NOAA 11402 (N28W20).23rd European Cosmic Ray Symposium (and 32nd Russian Cosmic Ray Conference) IOP PublishingJournal of Physics: Conference Series 409 (2013) 012185 doi:10.1088/1742-6596/409/1/0121852Figure 1. Solar are event on March 7, 2011.Panel A: 5 min TEL channel records of theCARPET. Vertical red bar at left shows 3r.m.s of the data during preare period (19-20 UT). B: time prole of > 50 MeV protonux (p/cm2ssr) as recorded onboard GOES-13 [4]. C: solar neutron observations by NEM-FIB detector onboard ISS [6]; D: FERMI-GBM (12-25 keV) and RHESSI (100-300 keV)solar burst observations [7]. E: solar X-rayux (W/m2) recorded on board GOES-13 [4].Figure 2. Solar are event on January 23,2012. Panel A: 5 min TEL channel recordsof the CARPET. Vertical red bar at leftshows 3 r.m.s of the data during preareperiod 0-3 UT. Panel B and C: time prolesof proton ux (p/cm2ssrMeV) in energychannels 110-900 MeV and 350-420 MeV,recorded onboard GOES-15 [4]. Panel Dpresents X-ray solar ux (W/m2) variationsdetected onboard GOES-15 [4].Figure 2 presents several experimental time proles for the 23 January 2012 event. Panel Ashows 5 min cosmic ray records in TEL channel of the CARPET. We note a very signicantincrease (3-7 r.m.s) of TEL counts between 03:40 and 08:00 UT. Panel B and C show 110-900MeV and 350-420 MeV proton ux variations observed by GOES-15. Also, the Fermi-LATinstrument, detected increased -ray emission (E>100 MeV) from the Sun between 00:00 UTand 18:37 UT [10].This event was recorded in 8 particle channels (energy range E=15-900 MeV) by GOES-15sensors. Then we can estimate a solar proton energy spectrum between 5 and 8 UT witha power law form as J(E)= 3107E 3:9(p=(cm2ssrMeV)) (1) in the 100-900 MeV energyrange. To evaluate the expected ux of secondaries at the CARPET device location, we havesimulated solar proton transport through the Earth's atmosphere. The simalations were based23rd European Cosmic Ray Symposium (and 32nd Russian Cosmic Ray Conference) IOP PublishingJournal of Physics: Conference Series 409 (2013) 012185 doi:10.1088/1742-6596/409/1/0121853on PLANETOCOSMICS/Geant4 code [11-13]. In the present simulations we used the spectralform (1), extended up to 15 GeV, as the rst iteration step. Finally, we deduced a protonspectrum at the top of the Earth`s atmosphere as J(E)=1.5104E 2:70:5(p=(cm2ssrMeV))in the energy range 9-15 GeV, which ts well the increase detected by the CARPET. Thisspectrum is unusually hard for this energy range and may be indicative of special conditions inthe acceleration region.3. SummaryAs a peliminary result of the analysis of the CARPET cosmic ray detector records on March,2011 and January, 2012, we conclude: (1) statistically signicant increases were detected during20:10-21:30 UT on 7 March 2011 and during 03:30-08:00 UT on 23 January 2012. (2) theseincreases are indications of the long-lasting presence of high-energy solar protons (E9 GeV)with unusually hard spectrum entering into the Earth`s atmosphere. Independent results ofthe analysis of VLF propagation characterstics data and riometer records during these eventssupport this conclusion (see paper [14] for details).The observed CARPET excesses are therefore indicative of high-energy processes occurringon the Sun in magnetized environment, initiated by energetic protons, and producing subsequentproducts as high-energy electrons, positrons, pions and photons. Therefore, comparison withthe Submillimeter Solar Telescope (SST) records at 212 and 405 GHz during solar ares, will becrucial to better understand these processes. Unfortunately, during the 07 March 2011 and 23January 2012 solar events, no SST data are available because of calibration tasks and nighttimehours, respectively.Finally, we note that a more careful analysis of the NMDB records is needed in order to geta nal conclusion on the presence or not of solar are eects in the form of GLEs during theseevents.AcknowledgmentsAuthors wish to thank partial support from Brazilian agencies FAPESP (contracts 2011/09700-0, 2011/24117-9), Program N-22 of the Presidium RAS, CNPq (contract 305655/2010-8),CNPq/PROANTAR (contract 0520186/06-0 and 556872/2009-6). We thank to Profs. R.A.Nymmik and B.Yu. Yushkov for their help.References[1] De Mendonca R, Raulin J-P, Makhmutov V, Stozhkov Y et al 2009 Bull.RAS 73(3) 404[2] De Mendonca R, Raulin J-P, Bertoni F, Echer E, Makhmutov V et al 2011 JASTP 73 1410[3] Nymmik R A, Panasyuk M I, Petrukhin V V, Yushkov B Yu 2009 Cosmic Res. 47 191[4] http://www.swpc.noaa.gov/[5] http://cr0.izmiran.ru/GLE-AlertAndProlesPrognosing/[6] Koga K, Goka T, Matsumoto H, Obara T et al 2011 Proc. 32nd ICRC 10 166[7] http://hesperia.gsfc.nasa.gov/fermi-solar/[8] Allafort A, Gigliletto N, Omodei N, Takahashi H, Tanaka Y 2011 Proc. 32nd ICRC 10 113[9] http://www.nmdb.eu/[10] Tanaka Y T, Omodei N, Giglietto N et al 2012 http://www.astronomerstelegram.org/?read=3886[11] Agostinelli S, Allison J, Amako K et al 2003 Nuclear Instr. and Meth. A506 250[12] Desorgher L 2005 PLANETOCOSMICS. Software User Manual[13] Makhmutov V, Desorgher L, Bazilevskaya G et al 2007 AdSR 39 1460[14] Correia E, Makhmutov V and Raulin J-P 2012 J. Phys.: Conf. Series this volume23rd European Cosmic Ray Symposium (and 32nd Russian Cosmic Ray Conference) IOP PublishingJournal of Physics: Conference Series 409 (2013) 012185 doi:10.1088/1742-6596/409/1/0121854

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Analysis of cosmic ray variations observed by the CARPET in association with solar flares in 2011-2012

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