Time Dependence of the Proton Flux Measured by Pamela During the 2006 July-2009 December Solar Minimum

Adriani, O.; Barbarino, G. C.; Bazilevskaya, G. A.; Bellotti, R.; Boezio, M.; Bogomolov, É. A.; Bongi, M.; Bonvicini, V.; Борисов, С. В.; Bottai, S.; Bruno, A.; Cafagna, F.; Campana, D.; Carbone, R.; Carlson, P.; Casolino, M.; Castellini, G.; Pascale, M. P. De; Santis, C. De; Simone, N. De; Felice, V. Di; Formato, V.; Galper, A. M.; Grishantseva, L.; Karelin, A. V.; Koldashov, S. V.; Koldobskiy, S.; Krutkov, S. Y.; Kvashnin, A. N.; Leonov, A.; Malakhov, V.; Marcelli, L.; Mayorov, A. G.; Menn, W.; Mikhailov, V. V.; Mocchiutti, E.; Monaco, A.; Mori, N.; Nikonov, N.; Osteria, G.; Palma, F.; Papini, P.; Pearce, Mark; Picozza, P.; Pizzolotto, C.; Ricci, M.; Ricciarini, S.; Rossetto, L.; Sarkar, R.; Simon, M.; Sparvoli, R.; Спиллантини, П.; Stozhkov, Y. I.; Vacchi, A.; Vannuccini, E.; Vasilyev, G.; Voronov, S. A.; Yurkin, Y. T.; Wu, J.; Zampa, G.; Zampa, N.; Zverev, V. G.; Potgieter, M. S.; Vos, E. E.

doi:10.1088/0004-637x/765/2/91

Cited by 272 publications

(252 citation statements)

References 18 publications

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“…This is shown in Fig. 5b for the PAMELA observations (Adriani et al 2013;. Instead of grouping with the previously observed A < 0 spectra (in red) the December 2009 spectrum was even higher than the A > 0 spectra (in blue) which, according to drift modulation models, should always be higher than A < 0 cycles at energies below 500 MeV.…”

Section: Cosmic Ray Observationsmentioning

confidence: 56%

A Remarkable Recent Transition in the Solar Dynamo

et al. 2016

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We summarize the major aspects of the remarkable, fairly long lasting period (∼ 2005 to ∼ 2010) of low solar activity, that we will call the Transition. It is the transitional stage between the Grand Maximum of the 20th century and a forthcoming (most probably Regular) episode of solar activity. The various kinds of activity in the functioning of the equatorial components of the solar dynamo before and during the Transition are summarized. While the behavior of unipolar magnetic regions and their rest-latitudes already gave very early indications -mid 20th century -of the forthcoming Transition, more such indications became available around 1995 and the main part of it occurred between 2005 and 2010. Some of the inferences are discussed. We submit the hypothesis that the solar tachocline undergoes pulsations and we present some helioseismic evidences. In that scenario we find that its equatorial part has moved downward over a fairly small semi-amplitude (∼ 0.03 solar radii) during the time of the Transition. There are several indications, apart from this 'pulsation', that the tachocline may even be pulsating with still smaller amplitudes in more modes. We speculate about the physical mechanism(s).

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Section: Cosmic Ray Observationsmentioning

confidence: 56%

A Remarkable Recent Transition in the Solar Dynamo

et al. 2016

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“…Lines shown in purple, black, and red colors represent P 21∕22 , P 22∕23 , and P 23∕24 , respectively. IMP-8 and STEREO spacecraft measurements of GCR are shown as diamonds and squares, respectively, and red circles denote the measurements from PAMELA instrument in the higher energy range for the year 2009 [Adriani et al, 2013, Table 1]. For each energy point, the flux is calculated with a stochastic process simulation.…”

Section: Simulation Resultsmentioning

confidence: 99%

“…The observation data are calculated from the measurements of proton flux by STEREO (squares) and IMP-8 (diamonds) after SEP contribution is removed. And red circles denote the measurements from PAMELA instrument for the year 2009 [Adriani et al, 2013, Table 1]. …”

Section: Gcr Datamentioning

confidence: 99%

Modulation of galactic cosmic rays during the unusual solar minimum between cycles 23 and 24

et al. 2014

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During the recent solar minimum between cycles 23 and 24 (solar minimum P23/24), the intensity of galactic cosmic rays (GCR) measured at the Earth was the highest ever recorded since space age. It is the purpose of this paper to resolve the most plausible mechanism for this unusually high intensity. A GCR transport model in three‐dimensional heliosphere based on a simulation of Markov stochastic process is used to find the relation of cosmic ray modulation to various transport parameters, including solar wind (SW) speed, distance of heliospheric boundary, magnitude of interplanetary magnetic field (IMF) at the Earth, tilt angle of heliospheric current sheet, and values of parallel and perpendicular diffusion coefficients. We calculate GCR proton energy spectra at the Earth for the last three solar minima P21/22, P22/23, and P23/24, with the transport parameters obtained from observations. Besides weak IMF magnitude and slow SW speed, we find that a possible low magnetic turbulence, which increases the parallel diffusion and reduces the perpendicular diffusion in the polar direction, might be an additional possible mechanism for the high GCR intensity in the solar minimum P23/24.

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“…Figure 1 gives the proton very LIS used in this study. Voyager 1 observations (diamonds) below ∼600 MeV were used to set the absolute value of the spectrum beyond the HP (Stone et al 2013;Webber & McDonald 2013), while PAMELA and AMS-02 measurements (Adriani et al 2013;Aguilar et al 2015) were used to normalize the very LIS above 30 GeV, where solar modulation is considered negligible (shaded band). GALPROP solutions (see, e.g., Moskalenko et al 2002) were used as a guide between 600 MeV and 30 GeV.…”

Section: A New Local Interstellar Proton Spectrummentioning

confidence: 99%

“…With the availability of accurate proton energy spectra measured by PAMELA during the recent unusual minimum of 2009 (Adriani et al 2013), this solar minimum period can be studied in detail with regard to how the proton energy spectrum developed. Potgieter et al (2014) conducted a similar study, aiming to uncover the extent to which various modulation processes contributed to the high intensities observed by PAMELA, as well as to prove the interplay that exists among these processes.…”

Section: Introductionmentioning

confidence: 99%

New Modeling of Galactic Proton Modulation During the Minimum of Solar Cycle 23/24

Vos

Potgieter

2015

ApJ

158

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During the recent prolonged solar minimum of cycle 23/24, the PAMELA detector measured 27-day averaged Galactic proton energy spectra over the energy range that is important for solar modulation. By comparing these spectra to computed spectra from a three-dimensional model that contains all of the important heliospheric modulation processes, the recent minimum can be studied in detail from a modulation perspective. This was done by setting up a realistic heliosphere in the model, and reproducing a representative selection of seven intermittent PAMELA spectra, separated by approximately six months, from 2006 July to 2009 December. Additionally, a new very local interstellar proton spectrum was constructed using measurements below 600 MeV from Voyager 1, taken beyond the heliopause, combined with PAMELA and AMS-02 measurements above 30 GeV at the Earth. As a result of the extreme minimum modulation conditions that governed the recent solar minimum, the highest ever Galactic cosmic ray spectrum at Earth was observed by PAMELA at the end of 2009. It was found that, apart from the self-consistent changes in the heliospheric current sheet and the heliospheric magnetic field over time, additional increases in the mean free paths during this period were required below~4 GV in order to reproduce the intensities observed by PAMELA.

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Time Dependence of the Proton Flux Measured by Pamela During the 2006 July-2009 December Solar Minimum

Cited by 272 publications

References 18 publications

A Remarkable Recent Transition in the Solar Dynamo

A Remarkable Recent Transition in the Solar Dynamo

Modulation of galactic cosmic rays during the unusual solar minimum between cycles 23 and 24

New Modeling of Galactic Proton Modulation During the Minimum of Solar Cycle 23/24

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