ICRC2015

Session

Parallel SH 09 Modulation II

5 Aug 2015, 14:00

World Forum

1152. An ab initio approach to solar-cycle dependent cosmic-ray modulation

Renier Burger (North-West University)

05/08/2015, 14:00

SH-TH

Oral contribution

Very often cosmic-ray modulation studies entail adjusting ad hoc parameters in order to fit observed cosmic-ray intensities. Since typically not all of the parameters in such models are related to observable physical quantities like magnetic field variances and correlation scales, they cannot predict changes in cosmic-ray intensity caused by changes in turbulence quantities. In this ab initio...

263. LATITUDE SURVEY INVESTIGATION OF GALACTIC COSMIC RAY SOLAR MODULATION DURING 1994–2007

David Ruffolo (Mahidol University)

05/08/2015, 14:15

SH-EX

Oral contribution

The Galactic cosmic ray spectrum exhibits subtle variations over the 22 yr solar magnetic cycle in addition to the more dramatic variations over the 11 yr sunspot cycle. Neutron monitors are large ground-based detectors that provide accurate measurements of variations in the cosmic ray flux at the top of the atmosphere above the detector. At any given location the magnetic field of the...

724. Heliospheric modulation and periodicities of galactic cosmic rays during 21-24 solar cycles

Prof. Karel Kudela (Institute of Experimental Physics, Slovak Academy of Sciences), Dr PARTHA CHOWDHURY (Kyung Hee University), Prof. Y.-J Moon (Kyung Hee University)

05/08/2015, 14:30

SH-TH

Oral contribution

Galactic cosmic rays (GCRs) encounter an outward-moving solar wind with cyclic magnetic-field fluctuation and turbulence. This causes convection and diffusion in the heliosphere. The GCR counts from the ground-based neutron monitor stations show intensity changes that are anti-correlated with the sunspot numbers with a lag of a few months. In this paper, we make a detailed correlative study...

198. On the causes and mechanisms of the long-term variations in the GCR characteristics

Mikhail Krainev (Lebedev Physical Institute, Moscow, Russia)

05/08/2015, 14:45

SH-TH

Oral contribution

There is a long-lasting controversy on the main causes of the long-term (11-year and 22-year) variations in the intensity and anisotropy of the galactic cosmic rays (GCR) observed for more than 50 years in the inner heliosphere. Some people believe that the 11-year variation is due entirely to the toroidal branch of solar activity (the area and number of sunspots, the strength of the...

275. Cosmic ray modulation as a possible diagnostic for the low-wavenumber behaviour of turbulence in the heliospheric magnetic field

Nicholas Eugene Engelbrecht (SANSA)

05/08/2015, 15:00

SH-TH

Oral contribution

Galactic cosmic-ray (CR) intensities calculated using numerical modulation models that proceed from first principles, where the diffusion tensor is calculated using as inputs observationally motivated forms for the heliospheric turbulence power spectrum as function of turbulence quantities yielded by turbulence transport models, are incredibly sensitive to assumptions made as to the...

54. Modelling the effects of scattering parameters on particle drifts in the solar modulation of galactic cosmic rays.

Dr Donald Ngobeni (Vaal University of Technology)

05/08/2015, 15:15

SH-TH

Oral contribution

It is well known that particle drift motions are suppressed by diffusive scattering as established by direct numerical simulations. The effect of constant scattering on the drift velocities of charged particles has always been included in numerical modulation models provided that the weak scattering drift velocity is scaled down in magnitude, although in an empirical manner as comparisons...

471. Cosmic Rays Propagation with HelMod: Difference between forward-in-time and backward-in-time approaches

Stefano Della Torre (Universita & INFN, Milano-Bicocca (IT))

05/08/2015, 15:30

SH-TH

Oral contribution

The cosmic rays modulation inside the heliosphere, is well described by a transport equation introduced by Parker in 1965. To solve this equation several approaches were followed in the past. Recently the Monte Carlo approach become widely used in force of his advantages with respect to other numerical methods. In the Monte Carlo approach the transport equation is associated to a fully...

865. The AD 775 cosmic ray event shown in Beryllium-10 data from Antarctic Dome Fuji ice core

Fusa Miyake (Nagoya University)

05/08/2015, 15:45

SH-EX

Oral contribution

${}^{14}$C content in tree rings and ${}^{10}$Be concentration records in ice core provide information about past cosmic ray intensities. Some studies reported a large annual increase in the ${}^{14}$C content from AD 774 to 775. Also quasi-decadal ${}^{10}$Be data in the Dome Fuji ice core show a sharp peak in a corresponding period of the AD 775 event. However, annual ${}^{10}$Be variations in the...