Experiment RIM-PAMELA: the registration of cosmic rays from solar flares


Figure 1. The active region of the sun number 1429 (left) and the number 1430 (right) 

On the spacecraft (SC) "Resource-DK1", developed and manufactured in accordance with the Federal Space Program of Russia on behalf of the Federal Space Agency, the continued implementation of the joint Russian-Italian experiment "RIM-PAMELA."

The experiment was conducted in order to explore outer space, designed to search for and study of antimatter (antiprotons, positrons), nuclear and electronic components in the primary cosmic radiation. Carrying out the experiment, according to the scientists, will solve a number of fundamental problems in cosmology (the origin of the universe).

A minimum of solar activity between 23 and 24 solar cycles proved to be abnormally long. This is confirmed by measurements of the solar gamma radiation, solar and galactic cosmic rays, as well as a small number of active regions on the Sun. According to some scholars, there comes a new era of long-term solar activity minimum. However, since 2010 the number of active regions, including sunspots, increased and, consequently, increased the number of solar flares with emission in the interplanetary space of accelerated charged particles. Measurement of the absolute value of the flux, composition, and time profiles, of course, it is important to study the physical processes occurring on the Sun during the transition to the 24th cycle of its activity and the near-Earth space.

In the experiment, "RIM-PAMELA", which takes place from June 2006 to the present time on the satellite "Resource-DK1", a magnetic spectrometer, "Pamela", which allows for precise measurements of charged particle fluxes of galactic and solar cosmic rays in a wide energy range (from 100 MeV to hundreds GeV) with high energy resolution. Energy range of particle detection can be extended to lower energies up to 20 MeV using the information from the scintillation spectrometer "Arina" installed on the same spacecraft. Compared with the space monitors GOES-13, GOES-15 and other spacecraft, the characteristics of the spectrometer "Pamela" is also given the opportunity to explore nuclear and isotopic composition of solar particles in high-energy part of the spectrum, providing thus a unique insight into the mechanisms of generation and particle acceleration in powerful solar flares.

March 5 at the sun solar flare occurred class X1.1, which was followed by a series of powerful events. The source of many of them was the active region number 1429 shown in Figure 1.


7 March she made a powerful burst of class H5.4, and March 9 and 10 outbreaks of M6.3 and M8.4 class. On March 7, there was another powerful X1.3 class flare from active region number 1430. A total of from 2 to 8 March in the Sun were 38 solar events and three large coronal mass ejection. March 13 active region number 1429 re-emitted a flash of smaller class M7.9. A day later, this area has moved to the invisible side of the solar disk. A few days ago, it reappeared on the visible side, however, is almost "solution". New strong solar events are expected from it.

Figure 2 shows the intensity of protons from 1 to 15 March 2012 when an event at high latitudes where the geomagnetic cutoff rigidity allows to register the accelerated particles in flares.


Fig.2. The intensity of protons from time to time according to the spectrometer "Pamela" and "Arina". 

 As can be seen from the figure, the 7th and the morning of March 13th the evening of March are considerable, 2-3 orders of magnitude, increase the intensity of protons compared to the period before the solar flares. The plateau of the 7th and 8th of March due to the registration of particles accelerated in two consecutive X-class flares that occurred with a small time interval from each other, and a series of flashes of class M. The spectrum of solar protons measured to the flares and the plateau at the maximum flash X5.4, shown in Figure 3.

Figure 3. The spectrum of galactic protons in a quiet period and the spectrum of protons accelerated at the Sun according spectrometers "Pamela" and "Arina".

 At rest, the measured intensity of the proton is determined only by the galactic component of cosmic rays in the energy range of the spectrometer "Pamela" and stationary solar component in the range of the spectrometer "Arina". The results are shown in black. Flare spectrum as shown in the figure in red, has a single-stage view, the maximum energy of the accelerated protons ~ 500 MeV.

Spectrometer "Pamela" registered an increase on the order of intensity of helium nuclei accelerated during solar flares H5.4 (area number 1429), and X1.3 (region number 1430). Increasing the flow of high-energy electrons were detected.

At present, a detailed analysis of the experimental data in order to obtain detailed composition and energy spectra of solar particles that will give important new information about the physical processes in the Sun, the mechanisms of generation of high-energy solar cosmic rays and their propagation in interplanetary space.

Flight satellite "Resource-DK1" and measurements on a magnetic spectrometer "Pamela" and spectrometer "Arina" progress.

Press Service of the Russian Federal Space Agency

(Materials provided by the supervisor of the experiment A.M.Galperom)

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