ASTRA - Latest Articles

A Shannon entropy approach to the temporal evolution of SEP energy spectrum

Tue, 28 Feb 2012 00:00:00 +0100

A Shannon entropy approach to the temporal evolution of SEP energy spectrum

Astrophysics and Space Sciences Transactions, 8, 19-24, 2012

Author(s): M. Laurenza, G. Consolini, M. Storini, and A. Damiani

The kinetic energy spectra of solar energetic particle (SEP) events contain information on the particle acceleration mechanisms. A novel approach is proposed to investigate the time evolution of the spectral shape for the 20 February 2002 SEP event. Proton differential fluxes recorded by the ERNE instrument aboard SOHO, in the energy range 1.67–112 MeV, are analyzed. The solar source is associated with this SEP event by studying solar and interplanetary conditions during the considered time period. The energy spectrum evolution is studied by evaluating the time history of Shannon's differential entropy derived from the SEP fluxes. Our findings suggest that particle acceleration in the considered event is produced by a perpendicular shock in the solar corona. Moreover, dropouts in the particle flux are clearly identified up to energies of at least ~10 MeV.

The effect of cosmic rays on biological systems – an investigation during GLE events

Tue, 10 Jan 2012 00:00:00 +0100

The effect of cosmic rays on biological systems – an investigation during GLE events

Astrophysics and Space Sciences Transactions, 8, 7-17, 2012

Author(s): N. K. Belisheva, H. Lammer, H. K. Biernat, and E. V. Vashenuyk

In this study, first direct and circumstantial evidences of the effects of cosmic rays (CR) on biological systems are presented. A direct evidence of biological effects of CR is demonstrated in experiments with three cellular lines growing in culture during three events of Ground Level Enhancement (GLEs) in the neutron count rate detected by ground-based neutron monitor in October 1989. Various phenomena associated with DNA lesion on the cellular level demonstrate coherent dynamics of radiation effects in all cellular lines coincident with the time of arrival of high-energy solar particles to the near-Earth space and with the main peak in GLE. These results were obtained in the course of six separate experiments, with partial overlapping of the time of previous and subsequent experiments, which started and finished in the quiet period of solar activity (SA). A significant difference between the values of multinuclear cells in all cellular lines in the quiet period and during GLE events indicates that the cause of radiation effects in the cell cultures is an exposure of cells to the secondary solar CR near the Earth's surface. The circumstantial evidence was obtained by statistical analysis of cases of congenital malformations (CM) at two sites in the Murmansk region. The number of cases of all classes of CM reveals a significant correlation with the number of GLE events. The number of cases of CM with pronounced chromosomal abnormalities clearly correlates with the GLE events that occurred a year before the birth of a child. We have found a significant correlation between modulations of the water properties and daily background variations of CR intensity. We believe that the effects of CR on biological systems can be also mediated by fluctuations in water properties, considered as one of possible mechanisms controlling the effects of CRs on biological systems.

Observation of solar energetic particle (SEP) events associated with narrow CMEs

Tue, 10 Jan 2012 00:00:00 +0100

Observation of solar energetic particle (SEP) events associated with narrow CMEs

Astrophysics and Space Sciences Transactions, 8, 1-5, 2012

Author(s): A. Al-Sawad, H. Allawi, W. Al-Ramdhan, and E. Valtonen

We report here on two proton energetic particle events observed by the Energetic and Relativistic Nuclei and Electron (ERNE) instrument on the Solar and Heliospherical Observatory (SOHO). Both events were impulsive (SEP) events with intensities of >10⁻³ cm⁻² sr⁻¹ s⁻¹ MeV⁻¹ at an energy range of tens of MeVs and were associated with CMEs of angular widths <60° and linear speed of >800 kms⁻¹. In one of the events there was no associated solar flare, which indicates that the first injected protons were completely due to the associated CME and in the second event the associated solar flare was an impulsive M1.1 class flare and the calculated first injection time for protons of energies ~36 MeV and propagating along 1.2 AU path length, was close to the liftoff time of the CME. These observations are inconsistent with the view presented in some studies that narrow fast CME are not associated with SEP events.

Helium counters for low neutron flux measurements

Wed, 30 Nov 2011 00:00:00 +0100

Helium counters for low neutron flux measurements

Astrophysics and Space Sciences Transactions, 7, 511-514, 2011

Author(s): Z. Dębicki, K. Jędrzejczak, J. Karczmarczyk, M. Kasztelan, R. Lewandowski, J. Orzechowski, B. Szabelska, J. Szabelski, P. Tokarski, and T. Wibig

We present a comparison of some characteristics of helium counters for measurements of low intensity neutron flux.

We focus on neutron flux density measurements in low background laboratories. Because of an extremely low counting rate (few events per hour or less), we have concentrated on counter parameters which are sometimes meaningless under regular conditions, i.e. background from internal alpha radioactivity, percentage of events in full energy peak, and the width of this peak. The background depends on residual radioactivity of the counter tube material and can not be eliminated. The full energy peak characteristics can be specified by counter gas composition. We will present a comparison of four types of helium gas counters.

EAS hadronic component as registered by a neutron monitor

Wed, 23 Nov 2011 00:00:00 +0100

EAS hadronic component as registered by a neutron monitor

Astrophysics and Space Sciences Transactions, 7, 507-510, 2011

Author(s): Yu. V. Balabin, B. B. Gvozdevsky, E. V. Vashenyuk, and D. D. Dzhappuev

For the purposes of a study of hadron component of an extended air shower (EAS), two detectors of cosmic rays (CR) were joined at the Baksan Neutrino Observatory. They are an EAS array detector (the "Carpet") and a neutron monitor (NM). Due to the versatility of a new recording system a master-pulse, which comes from the "Carpet" and marks to occurring of EAS, is joined to NM data. After processing of the huge data set it is found that the time of EAS influence on NM is less than 1 ms. The distribution of time intervals between pulses in the first millisecond after EAS onset is essentially different from the background and shows presence of two processes with characteristic times 45 and 230 μs.

Observations with the High Altitude GAmma-Ray (HAGAR) telescope array in the Indian Himalayas

Fri, 18 Nov 2011 00:00:00 +0100

Observations with the High Altitude GAmma-Ray (HAGAR) telescope array in the Indian Himalayas

Astrophysics and Space Sciences Transactions, 7, 501-505, 2011

Author(s): R. J. Britto, B. S. Acharya, G. C. Anupama, N. Bhatt, P. Bhattacharjee, S. Bhattacharya, V. R. Chitnis, R. Cowsik, N. Dorji, S. K. Duhan, K. S. Gothe, P. U. Kamath, R. Koul, J. Manoharan, P. K. Mahesh, A. Mitra, B. K. Nagesh, N. K. Parmar, T. P. Prabhu, R. C. Rannot, S. K. Rao, L. Saha, F. Saleem, A. K. Saxena, S. K. Sharma, A. Shukla, B. B. Singh, R. Srinivasan, G. Srinivasulu, P. V. Sudersanan, A. K. Tickoo, D. Tsewang, S. S. Upadhya, P. R. Vishwanath, and K. K. Yadav

The High Altitude GAmma-Ray (HAGAR) array is a wavefront sampling array of 7 telescopes, set-up at Hanle, at 4270 m amsl, in the Ladakh region of the Himalayas (Northern India). It constitutes the first phase of the HImalayan Gamma-Ray Observatory (HIGRO) project. HAGAR is the first array of atmospheric Cherenkov telescopes established at a so high altitude, and was designed to reach a relatively low threshold (currently around 200 GeV) with quite a low mirror area (31 m²). Regular source observations are running since September 2008. Estimation of the sensitivity of the experiment is undergoing using several hours of data from the direction of Crab nebula, the standard candle source of TeV gamma-ray astronomy, and from dark regions. Data were acquired using the On-source/Off-source tracking mode, and by comparing these sky regions the strength of the gamma-ray signal could be estimated. Gamma-ray events arrive close to telescope axis direction while the cosmic-ray background events arrive from the whole field of view. We discuss our analysis procedures for the estimate of arrival direction, estimate of gamma ray flux from Crab nebula, and the sensitivity of the HAGAR system, in this paper.

Improvement of charge resolution for trans-iron nuclei (Z ≥ 30) in CR-39 plastic nuclear track detectors using trajectory tracing technique

Tue, 15 Nov 2011 00:00:00 +0100

Improvement of charge resolution for trans-iron nuclei (Z ≥ 30) in CR-39 plastic nuclear track detectors using trajectory tracing technique

Astrophysics and Space Sciences Transactions, 7, 495-500, 2011

Author(s): S. Ota, N. Yasuda, L. Sihver, S. Kodaira, S. Naka, Y. Ideguchi, and N. Hasebe

Charge identification of trans-iron nuclei (nuclear charge: Z ≥30) using CR-39 plastic nuclear track detector (PNTD) is essential as a part of an effort to our future measurements of the projectile charge changing cross sections for galactic cosmic ray nuclei, but extremely hard. Therefore, an improvement method of the charge resolution (δZ) for 350 MeV/n Ge in CR-39 PNTD using the trajectory tracing technique with averaging the signals of nuclear tracks for each ion was studied. Eight sheets of CR-39 PNTDs were aligned and exposed to Ge beam behind a graphite target to produce projectile fragments. Average of the nuclear track data was taken over 16 detector surfaces for each ion, then the δZ of Ge was successfully improved from 0.31 charge unit on single surface to 0.15 charge unit in rms, which is good enough for making the precise cross section measurements and no other experiments using CR-39 PNTDs or the other passive detectors have achieved such a good δZ for the trans-iron nuclei with Z/β < 50 (β: relativistic velocity). This method will be very important for our future cross section measurements toward the study of galactic cosmic ray origin.

An explanation of the Pioneer anomaly involving accelerated atomic clocks

Wed, 09 Nov 2011 00:00:00 +0100

An explanation of the Pioneer anomaly involving accelerated atomic clocks

Astrophysics and Space Sciences Transactions, 7, 487-494, 2011

Author(s): K. Wilhelm and B. N. Dwivedi

The Pioneer anomaly stands for unexplained frequency shifts of the Doppler radio-tracking signals received at the ground stations from the Pioneer 10 and 11 spacecraft in disagreement with expectations based on model calculations. We consider here observations of Pioneer 10 at heliocentric distances between 40 ua and 70.5 ua over a time interval of 11.55 years from 1987 to 1998. The anomaly has been interpreted in the literature either as a Doppler shift caused by an apparent spacecraft deceleration not accounted for by known effects, or as an unexpected clock acceleration of the frequency standards at the ground stations. The reasons for the anomalous behaviour are not understood in both cases. Based on a gravitational impact model – requiring a secular mass increase of all massive bodies – a solution is proposed that implies a clock acceleration with a value close to that of the Hubble constant.

On the energy spectrum of cosmic ray muons in 100 TeV region

Fri, 28 Oct 2011 00:00:00 +0200

On the energy spectrum of cosmic ray muons in 100 TeV region

Astrophysics and Space Sciences Transactions, 7, 483-486, 2011

Author(s): Yu. F. Novoseltsev, A. G. Bogdanov, R. P. Kokoulin, R. V. Novoseltseva, V. B. Petkov, and A. A. Petrukhin

The energy spectrum of cosmic ray muons in the energy range from several TeV to ~1 PeV obtained by means of the analysis of multiple interactions of muons (pair meter technique) in the Baksan underground scintillation telescope is presented. Some evidence for the additional muon flux (to the conventional one from pion and kaon decays) has been obtained at energies ~100 TeV.

Detecting ultra-high energy cosmic rays from space with unprecedented acceptance: objectives and design of the JEM-EUSO mission

Wed, 26 Oct 2011 00:00:00 +0200

Detecting ultra-high energy cosmic rays from space with unprecedented acceptance: objectives and design of the JEM-EUSO mission

Astrophysics and Space Sciences Transactions, 7, 477-482, 2011

Author(s): M. Casolino, J. H. Adams, M. E. Bertaina, M. J. Christl, T. Ebisuzaki, P. Gorodetzky, Y. Hachisu, F. Kajino, Y. Kawasaki, G. Medina-Tanco, H. Miyamoto, H. Ohomori, E. Parizot, I. Park, P. Picozza, N. Sakaki, A. Santangelo, K. Shinozaki, Y. Takizawa, K. Tsuno, and JEM-EUSO collaboration

The Extreme Universe Space Observatory on the Japanese Experiment Module (JEM-EUSO) of the International Space Station (ISS) is the first mission that will study from space Ultra High-Energy Cosmic Rays (UHECR). JEM-EUSO will observe Extensive Air Showers (EAS) produced by UHECRs traversing the Earth's atmosphere from above. For each event, the detector will make accurate measurements of the energy, arrival direction and nature of the primary particle using a target volume far greater than what is achievable from ground. The corresponding increase in statistics will help to clarify the origin and sources of UHECRs as well as the environment traversed during production and propagation. Possibly this will bring new light onto particle physics mechanisms operating at energies well beyond those achievable by man-made accelerators. The spectrum of scientific goals of the JEM-EUSO mission includes as exploratory objectives the detection of high-energy gamma rays and neutrinos, the study of cosmic magnetic fields, and tests of relativity and quantum gravity effects at extreme energies. In parallel JEM-EUSO will systematically perform observation of the surface of the Earth in the infra-red and ultra-violet ranges, studying also atmospheric phenomena (Transient Luminous Effects). The apparatus is a 2 t detector using Fresnel-based optics to focus the UV-light from EAS on a focal surface composed of about 6 000~multianode photomultipliers for a total of ~3 · 10⁵ channels. A multi-layer parallel architecture has been devised to handle the data flow and select valid triggers, reducing it to a rate compatible with downlink constraints. Each processing level filters the event with increasingly complex algorithms using ASICs, FPGAs and DSPs in this order to reject spurious triggers and reduce the data rate.

High-energy photons connected to atmospheric precipitations

Wed, 26 Oct 2011 00:00:00 +0200

High-energy photons connected to atmospheric precipitations

Astrophysics and Space Sciences Transactions, 7, 471-475, 2011

Author(s): A. V. Germanenko, Yu. V. Balabin, E. V. Vashenyuk, B. B. Gvozdevsky, and L. I. Schur

Increases in intensity of X-radiation in the ground layer of the atmosphere observed during various atmospheric phenomena in two points: Apatity (Kola Peninsula) and Barentsburg (Spitsbergen) have been studied. A clear relationship between the increases and such atmospheric phenomena as rain and snowfall has been found. It is shown that these increases are not connected with any radionuclides. This research suggests that the principal cause of high-energy photons increase during precipitations are bremsstrahlung X-rays created by energetic electrons accelerated by electric fields in the clouds. A possible mechanism of generation of X-ray photons is discussed.

Measurements of He isotopic ratio in cosmic rays in the 100 MeV – 1 GeV range with the PAMELA experiment

Wed, 26 Oct 2011 00:00:00 +0200

Measurements of He isotopic ratio in cosmic rays in the 100 MeV – 1 GeV range with the PAMELA experiment

Astrophysics and Space Sciences Transactions, 7, 465-469, 2011

Author(s): M. Casolino, C. De Santis, N. De Simone, V. Formato, N. Nikonov, P. Picozza, and the PAMELA collaboration

The PAMELA satellite-borne experiment was launched on 15 June 2006 from the Baikonur cosmodrome and it has been collecting data since then. The apparatus comprises a time-of-flight system, a silicon-microstrip magnetic spectrometer, a silicon-tungsten electromagnetic calorimeter, an anticoincidence system, a shower tail counter scintillator and a neutron detector. The combination of these devices allows precision studies of the charged cosmic radiation to be conducted over a wide energy range (100 MeV – 1 TeV) with high statistics, with particular focus on the antiparticle component. In this work we present ³He/⁴He isotopic ratio in the energy range from 100 MeV nucleon⁻¹ to ~1 GeV nucleon⁻¹. The measured abundances are compared with different interstellar/heliospheric propagation calculations which are tuned on previous proton and helium measurements.

Features of relativistic solar proton spectra derived from ground level enhancement events (GLE) modeling

Wed, 26 Oct 2011 00:00:00 +0200

Features of relativistic solar proton spectra derived from ground level enhancement events (GLE) modeling

Astrophysics and Space Sciences Transactions, 7, 459-463, 2011

Author(s): E. V. Vashenyuk, Yu. V. Balabin, and B. B. Gvozdevsky

With the developed by the authors of a ground level enhancements events (GLE) modeling technique, the modeling study of 35 large GLEs for the period 1956–2006 has been carried out. The basic characteristics of relativistic solar protons (RSP) are obtained: a rigidity (energetic) spectrum, anisotropy axis direction, and pitch angle distributions for each event. It is shown that in nearly all events there existed two components (population) of relativistic solar particles: prompt and delayed. The prompt component (PC) prevails in the beginning of the event. It is characterized by an impulsive profile, strong anisotropy and exponential energetic spectrum. The delayed component (DC) dominates during maximum and decline phases of the events. It has a gradual intensity profile, moderate anisotropy and a power law energetic spectrum. The analysis of the large number GLE shows the value of a characteristic energy in the exponential spectrum of PC has rather stable meaning ~0.5 GeV and well agrees with the spectrum of protons accelerated in an electric field arising during the magnetic reconnection in the solar corona. The value of a spectral exponent of the power law spectrum of DC is distributed from 4 up to 6 with most at 5. This is close to the simulated spectrum arising in the process of stochastic acceleration in turbulent solar plasma.

A method for real-time GLE modeling

Wed, 26 Oct 2011 00:00:00 +0200

A method for real-time GLE modeling

Astrophysics and Space Sciences Transactions, 7, 453-458, 2011

Author(s): E. V. Vashenyuk

By now real time systems of data collection of neutron monitor network have been created. The main goal of such systems is early detection of dangerous events of space weather, such as GLE, caused by arrival to the Earth of relativistic solar protons. Characteristics of these particles are determined from the data of the worldwide neutron monitor network by methods of GLE modeling. Traditional GLE modeling requires data of no less than 30–35 stations and takes a long time of computations. We developed a truncated technique of solar proton spectrum determination by data of limited number (20–25) of neutron monitor stations and with a simplified procedure of computations adapted for operative diagnostics of relativistic solar protons just arriving to the Earth. Possibilities of this truncated GLE modeling for the early forecast of radiation-dangerous fluxes of solar particles with moderate energies are also shown.

General overview of recent results from the Pierre Auger Observatory

Wed, 19 Oct 2011 00:00:00 +0200

General overview of recent results from the Pierre Auger Observatory

Astrophysics and Space Sciences Transactions, 7, 445-451, 2011

Author(s): R. Caruso on behalf of the Pierre Auger Collaboration

Since June 2008 the Pierre Auger Observatory, designed for the research of ultra high energy cosmic rays, is taking data in its final configuration. In this paper I will present a short overview of its recent scientific results. More specifically, I will discuss the all particle energy spectrum and the evidence for the GZK features, the measurement of the elongation rate and the resulting inferences on mass composition, the evidence for anisotropy in the subset of the highest energy events.

Solar activity and the associated ground level enhancements of solar cosmic rays during solar cycle 23

Fri, 07 Oct 2011 00:00:00 +0200

Solar activity and the associated ground level enhancements of solar cosmic rays during solar cycle 23

Astrophysics and Space Sciences Transactions, 7, 439-443, 2011

Author(s): M. Andriopoulou, H. Mavromichalaki, P. Preka-Papadema, C. Plainaki, A. Belov, and E. Eroshenko

The solar cycle 23 seems to be of great interest for the researchers due to many peculiarities. A study of the parameters of the sixteen ground level enhancements recorded during the approximately 12-year period of it (1996–2008) together with the associated solar activity, including the main properties of the solar flares, the coronal mass ejections and the radio bursts has been realized, in an effort to understand the connection of these events. All studied cases seem to be connected with very intense flares of long duration, having a mean importance value of X5.9 and a mean duration of 164.5 min, with either halo or partial halo coronal mass ejections with a mean linear velocity of 1876 km/sec, as well as with intense radio bursts. It is also noticed that the ground level enhancements of the 23rd solar cycle occurred after the onset time of the associated solar X-ray flares with a mean time delay of about 38 min, very useful result for their monitoring and prediction.

Large area scintillation muon hodoscope for monitoring of atmospheric and heliospheric processes

Thu, 22 Sep 2011 00:00:00 +0200

Large area scintillation muon hodoscope for monitoring of atmospheric and heliospheric processes

Astrophysics and Space Sciences Transactions, 7, 435-438, 2011

Author(s): N. V. Ampilogov, I. I. Astapov, N. S. Barbashina, V. V. Borog, D. V. Chernov, A. N. Dmitrieva, K. G. Kompaniets, A. A. Petrukhin, V. V. Shutenko, A. I. Teregulov, and I. I. Yashin

A new muon hodoscope for investigations of the processes in heliosphere and terrestrial atmosphere by means of cosmic ray muons is described. The setup design is based on multi-layer assemblies of narrow long scintillation strips with WLS fiber readout. Features of the hodoscope design are described and results of tests of a full-scale prototype of the basic unit of the hodoscope detection system – the module – are discussed.

Latitudinal and radial gradients of galactic cosmic ray protons in the inner heliosphere – PAMELA and Ulysses observations

Thu, 22 Sep 2011 00:00:00 +0200

Latitudinal and radial gradients of galactic cosmic ray protons in the inner heliosphere – PAMELA and Ulysses observations

Astrophysics and Space Sciences Transactions, 7, 425-434, 2011

Author(s): N. De Simone, V. Di Felice, J. Gieseler, M. Boezio, M. Casolino, P. Picozza, PAMELA Collaboration†, and B. Heber

Ulysses, launched on 6 October 1990, was placed in an elliptical, high inclined (80.2°) orbit around the Sun, and was switched off in June 2009. It has been the only spacecraft exploring high-latitude regions of the inner heliosphere. The Kiel Electron Telescope (KET) aboard Ulysses measures electrons from 3 MeV to a few GeV and protons and helium in the energy range from 6 MeV/nucleon to above 2 GeV/nucleon. The PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) space borne experiment was launched on 15 June 2006 and is continuously collecting data since then. The apparatus measures electrons, positrons, protons, anti-protons and heavier nuclei from about 100 MeV to several hundreds of GeV. Thus the combination of Ulysses and PAMELA measurements is ideally suited to determine the spatial gradients during the extended minimum of solar cycle 23. For protons in the rigidity interval 1.6–1.8 GV we find a radial gradient of 2.7%/AU and a latitudinal gradient of −0.024%/degree. Although the latitudinal gradient is as expected negative, its value is much smaller than predicted by current particle propagation models. This result is of relevance for the study of propagation parameters in the inner heliosphere.

Lower limits on the lifetime of massive neutrino radiative decay from the 2006 total solar eclipse

Thu, 22 Sep 2011 00:00:00 +0200

Lower limits on the lifetime of massive neutrino radiative decay from the 2006 total solar eclipse

Astrophysics and Space Sciences Transactions, 7, 419-423, 2011

Author(s): V. Popa

We report on the search for signatures of possible neutrino radiative decays, in occasion of the 2006 total solar eclipse (TSE). The lower lifetime limits obtained in the hypothesis of normal mass hierarchy (m₃ >> m ₂ > m₁) are about 3 orders of magnitude better than the previous results. The inverted mass hierarchy scenario (m₂ > m₁ >> m₃) is also investigated. The reached sensitivity suggests that the limits presented here are the best obtainable using this technique.

Corrigendum to "Linsley's EAS time structure method for the primary cosmic ray spectrum at LAAS" published in Astrophys. Space Sci. Trans., 7, 335–344, 2011

Wed, 21 Sep 2011 00:00:00 +0200

Corrigendum to "Linsley's EAS time structure method for the primary cosmic ray spectrum at LAAS" published in Astrophys. Space Sci. Trans., 7, 335–344, 2011

Astrophysics and Space Sciences Transactions, 7, 417-417, 2011

Author(s): A. Iyono, H. Matsumoto, K. Okei, S. Tsuji, S. Ohara, N. Ochi, T. Konishi, N. Takahashi, I. Yamamoto, T. Nakatsuka, T. Nakamura, N. Ohmori, and K. Saito

No abstract available.