Journal: The Astrophysical Journal

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Journal: New Astronomy
Title: Diurnal Anisotrophy of Cosmic Rays during intensive Solar Activity for the period 2001-2014
General Information: Accepted 18 December 2015, Available online 29 December 2015
Author(s): A. Tezari, H. Mavromichalaki
Abstract: The diurnal variation of cosmic ray intensity, based on the records of two neutron monitor stations at Athens (Greece) and Oulu (Finland) for the time period 2001 to 2014, is studied. This period covers the maximum and the descending phase of the solar cycle 23, the minimum of the solar cycles 23/24 and the ascending phase of the solar cycle 24.These two stations differ in their geographic latitude and magnetic threshold rigidity. The amplitude and phase of the diurnal anisotropy vectors have been calculated on annual and monthly basis.

From our analysis it is resulted that there is a different behaviour in the characteristics of the diurnal anisotropy during the different phases of the solar cycle, depended on the solar magnetic field polarity, but also during extreme events of solar activity, such as Ground Level Enhancements and cosmic ray events, such as Forbush decreases and magnetospheric events. These results may be useful to Space Weather forecasting and especially to Biomagnetic studies.



Journal: Advances in Space Research
Title: Forbush Decreases Observed by Daejeon Neutron Monitor
General Information: Accepted 20 November 2015, Available online 28 November 2015
Author(s): Jeongsoo Kang, Suyeon Oh, Yu Yi, Yongkyun Kim
Abstract: The neutron monitor (NM) is a ground-based detector designed to estimate the cosmic ray intensity by measuring secondary particles. In October 2011, an NM64-type NM with a vertical cutoff rigidity of 11.2 GV was installed at Daejeon in Korea. It has produced reliable cosmic ray data after detector stabilization. In order to examine the reliability of cosmic ray data collected by the Daejeon NM, we select Forbush decreases (FDs) that occurred during the three years of 2012–2014. We also analyze the FDs at the Oulu NM in Finland in order to identify and compare them. We identify 37 FDs at both Daejeon and Oulu NMs. Student t-test analysis reveals that FDs at Daejeon have smaller intensity variation of main phase and shorter duration of main phase than those at the Oulu NM. Of the 37 FDs, 17 are simultaneous and 20 are non-simultaneous. The intensity variation of simultaneous FDs is larger than that of non-simultaneous FDs at both NMs with high confidence levels in the Student t-test. Most of the non-simultaneous FDs that have an onset time in the dayside hold typical properties of non-simultaneous FDs. Our study results demonstrate that the Daejeon NM can provide cosmic ray data of reliability comparable to that of the Oulu NM. As one of only a few NMs worldwide with a high vertical cutoff rigidity exceeding 10.0 GV, the Daejeon NM will continue to provide important information on higher-energy cosmic ray spectra.


Journal: Applied Mathematics and Computation
Title: Calculating the Ambient Dose Equivalent of Fast Neutrons using Elemental Composition of Human Body
General Information: Accepted 11 November 2015, Available online 5 December 2015, Volume 274, Pages 604-610
Author(s): A. Saeed, Sherif S. Nafee, Salem A. Shaheen, Gehan A. Raouf, Y. Al-Hadeethi, Salahuddin M. Kamal, M.A.N. Razvi
Abstract: The sphere of International Commission on Radiation Units and Measurements (ICRU) consists of 4-elemental compositions of 76.2% oxygen (O), 11.1% carbon (C), 10.1% hydrogen (H), and 2.6% nitrogen (N) whereas there are 26 elemental compositions in the human body. In this work, human body elemental composition has been used to calculate the ambient dose equivalent rate of fast neutrons. 241Am–Be of 185 GBq (5 Ci) was utilized as neutron source. In addition, the conversion coefficients in International Commission on Radiological Protection publication 116 (ICRP 116) was used to verify from the results of using elemental compositions in the human body. The calculated results have been compared to those measured by a neutron monitor. The mean values of discrepancies from the measured values were within ∼8%. Moreover, systematic comparisons have been carried out with values published in literature. This work concluded that the elemental compositions in the human body could be used to design a phantom that has the same elemental composition of human body.


Journal: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment
Title: Characterization of high-energy quasi-monoenergetic neutron energy spectra and ambient dose equivalents of 80–389 MeV 7Li(p,n) reactions using a time-of-flight method

General Information: Accepted 3 September 2015, Available online 26 September 2015, Volume 804, Pages 50-58

Author(s): Yosuke Iwamoto, Masayuki Hagiwara, Daiki Satoh, Shouhei Araki, Hiroshi Yashima, Tatsuhiko Sato, Akihiko Masuda, Tetsuro Matsumoto, Noriaki Nakao, Tatsushi Shima, Tadahiro Kin, Yukinobu Watanabe, Hiroshi Iwase, Takashi Nakamura
Abstract: We completed a series of measurements on mono-energetic neutron energy spectra of the 7Li(p,n) reaction with 80–389-MeV protons in the 100-m time-of-flight (TOF) tunnel at the Research Center for Nuclear Physics cyclotron facility. For that purpose, we measured neutron energy spectra of the 80-, 100- and 296-MeV proton incident reactions, which had not been investigated in our previous studies. The neutron peak intensity was 0.9–1.1×1010 neutrons/sr/µC in the incident proton energy region of 80–389 MeV, and it was almost independent of the incident proton energy. The contribution of peak intensity of the spectrum to the total intensity integrated with energies above 3 MeV varied between 0.38 and 0.48 in the incident proton energy range of 80–389 MeV. To consider the correction required to derive a response in the peak region from the measured total responses of neutron monitors in the 100-m TOF tunnel, we proposed the subtraction method using energy spectra between 0° and 25°. The normalizing factor kagainst 25° neutron fluence to equalize it to 0° neutron fluence in the continuum region ranges from 0.74 to 1.02 depending on the incident proton energy and angle measured. Even without the TOF method, the subtraction method with the k factor almost decreases the response in the continuum region of a neutron spectrum against the total response of neutron monitors.

Journal: Astroparticle Physics

Title: Estimates of the Neutron Emission during Large Solar Flares in the Rising and Maximum Period of Solar Cycle 24
General Information: Accepted 14 December 2015, Available online 19 December 2015, Volume 76, Pages 19-28
Author(s): D. Lopez, Y. Matsubara, Y. Muraki, T. Sako, J.F. Valdés-Galicia
Abstract: We searched for solar neutrons using the data collected by six detectors from the International Network of Solar Neutron Telescopes and one Neutron Monitor between January 2010 and December 2014. We considered the peak time of the X-ray intensity of thirty five ≥ X1.0 class flares detected by GOES satellite as the most probable production time of solar neutrons. We prepared a light-curve of the solar neutron telescopes and the neutron monitor for each flare, spanning ± 3 h from the peak time of GOES. Based on these light curves, we performed a statistical analysis for each flare. Setting a significance level at greater than 3σ, we report that no statistically significant signals due to solar neutrons were found. Therefore, upper limits are determined by the background level and solar angle of these thirty five solar flares. Our calculation assumed a power-law neutron energy spectrum and an impulsive emission profile at the Sun. The estimated upper limits of the neutron emission are consistent within the order of magnitude of the successful detections of solar neutrons made in solar cycle 23.


Journal: New Astronomy
Title: Detection of Solar Neutron Events and Their Theoretical Approach
General Information: Accepted 29 December 2014, Available online 6 January 2015, Volume 39, Pages 25-35
Author(s): Xiao Xia Yu, Hong Lu, Guan Ting Chen, Xin Qiao Li, Jian Kui Shi, Cheng Ming Tan
Abstract: Solar neutron events provide important opportunities to explore particle acceleration mechanisms using data from ground-based detectors and spacecrafts. Energetic neutrons carry crucial physics information of the acceleration site, such as energy spectrum, atmospheric elements of solar flare, scale height, convergence of the magnetic field and magnetohydrodynamic turbulence. Here 12 representative solar neutron events observed on the Earth, together with X and γ-ray observations from spacecrafts are presented. Theoretical approaches on solar neutrons that are carried out mainly through the Monte Carlo simulation are compared with the observation data, and the constraints of different theoretical models on the observations are to be summarized.


Journal: Astroparticle Physics
Title: Long and Short-Term Atmospheric Radiation Analyses Based on Coupled Measurements at High Altitude Remote Stations and Extensive Air Shower Modeling
General Information: Accepted 16 September 2015, Available online 30 September 2015, Volume 74, Pages 27-36
Author(s): G. Hubert, C. A. Federico, M. T. Pazianotto, O. L. Gonzales
Abstract: In this paper are described the ACROPOL and OPD high-altitude stations devoted to characterize the atmospheric radiation fields. The ACROPOL platform, located at the summit of the Pic du Midi in the French Pyrenees at 2885 m above sea level, exploits since May 2011 some scientific equipment, including a BSS neutron spectrometer, detectors based on semiconductor and scintillators. In the framework of a IEAv and ONERA collaboration, a second neutron spectrometer was simultaneously exploited since February 2015 at the summit of the Pico dos Dias in Brazil at 1864 m above the sea level.
The both high station platforms allow for investigating the long period dynamics to analyze the spectral variation of cosmic-ray- induced neutron and effects of local and seasonal changes, but also the short term dynamics during solar flare events.
This paper presents long and short-term analyses, including measurement and modeling investigations considering the both high altitude stations data. The modeling approach, based on ATMORAD computational platform, was used to link the both station measurements.


Journal: Advances in Space Research
Title: Gnevyshev-Ohl Rule for Strong Solar Proton Events
General Information: Available online 22 October 2015
Author(s): M. Ogurtsov, M. Lindholm
Abstract: Data on strong solar proton events, including: (a) instrumental record of ground level enhancements (1954–1996), (b) proxy record derived from nitrate series (1700–1944) and (c) proxy record derived from 10Be series (1755–1927) were analyzed. It was shown that strong solar proton events are more frequent during even-numbered solar cycles than during odd-numbered ones with a probability of more than 0.93. The results provide new evidence for the fundamental character of the Gnevyshev–Ohl rule. Possible causes of the revealed even-odd effect are discussed.


Journal: Advances in Space Research
Title: Solar Modulation of Low Energy Galactic Cosmic Rays in the Near-Earth Space Environment
General Information: Available online 17 November 2015
Author(s): J.F. Valdés-Galicia, L.X. González
Abstract: This is an overview of the solar modulation of galactic cosmic rays as seen from the Earth and spacecrafts closeby, where we have put the contributions of Latin-American researchers in the global context in the last five to ten years. It is a broad topic with numerous intriguing aspects so that a research framework has to be chosen to concentrate on, therefore we have put our emphasis on measurements of the cosmic ray flux, without attempting to review all details or every contribution made in this field of research. In consequence, after establishing the basic characteristics of the cosmic radiation such as composition and energy spectrum, we focus on a few selected subjects, almost all within the framework of solar modulation of galactic cosmic rays such as Forbush decreases, periodic variations, space and atmospheric weather cosmic ray relationships, to which we add a general description of ground level enhancement observations. Controversial aspects are discussed where the appropriate results are presented, some of the challenges and prospects of key issues are also pointed out. At the end of the paper, a brief summary of the last decade Latin-American contributions to the subjects treated is given.


Journal: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Title: The EEE Project: An Extended Network of Muon Telescopes for the Study of Cosmic Rays
General Information: Available online 26 October 2015
Author(s): M. P. Panetta, On behalf of the EEE Collaboration
Abstract: The EEE (Extreme Energy Event) Project׳s goal is the study of high energy Extensive Air Showers (EAS) over a very large area, using an array of muon telescopes, based on position-sensitive Multigap Resistive Plate Chambers (MRPCs). Young students are directly involved in assembling and monitoring the telescopes, with the aim to introduce them to advanced physics research. At present the array is composed of more than 40 stations, distributed on a total area of view the mathml source. Most of them are independently taking data since several years. A new combined run (RUN-1) has started in February 2015, with 35 telescopes taking data simultaneously for a collected statistics larger than4×109 reconstructed events. An overview of the experiment and some results from studies on correlated muons from the same EAS, and on solar events as Forbush decreases, will be shown.


Journal: Atmospheric Research
Title: The Time Structure of Neutron Emission during Atmospheric Discharge
General Information: Published 1 October – 1 November 2015, Volumes 164-165, Pages 339-346
Author(s): A.V. Gurevich, V.P. Antonova, A.P. Chubenko, A.N. Karashtin, O.N. Kryakunova, V.Yu. Lutsenko, G.G. Mitko, V.V. Piskald, M.O. Ptitsyn, V.A. Ryabov, A.L. Shepetov, Yu.V. Shlyugaev, W.M. Thu, L.I. Vildanova, K.P. Zybin
Abstract: The time structure of neutron count rate enhancement during thunderstorm is studied. The enhancements take place during the time of atmospheric discharge. Significant part of neutrons is emitted in short bursts (200–400 μs). Sometimes the emission is well correlated over the space scale 1 km. Short burst width enables us to suppose that neutrons are generated mainly in a dense medium (probably soil).


Journal: Advances in Space Research
Title: Understanding Space Weather to Shield Society: A Global Road Map for 2015-2025 Commissioned by COSPAR and ILWS
General Information: Published 15 June 2015, Volume 55, Issue 12, Pages 2745-2807
Author(s): Carolus J. Schrijver, Kirsti Kauristie, Alan D. Aylward, Clezio M. Denardini, Sarah E. Gibson, Alexi Glover, Nat Gopalswamy, Manuel Grande, Mike Hapgood, Daniel Heynderickx, Norbert Jakowski, Vladimir V. Kalegaev, Giovanni Lapenta, Jon A. Linker, Siqing Liu, Cristina H. Mandrini, Ian R. Mann, Tsutomu Nagatsuma, Dibyendu Nandy, Takahiro Obara, T. Paul O’Brien, Terrance Onsager, Hermann J. Opgenoorth, Michael Terkildsen, Cesar E. Valladares, Nicole Vilmer
Abstract: There is a growing appreciation that the environmental conditions that we call space weather impact the technological infrastructure that powers the coupled economies around the world. With that comes the need to better shield society against space weather by improving forecasts, environmental specifications, and infrastructure design. We recognize that much progress has been made and continues to be made with a powerful suite of research observatories on the ground and in space, forming the basis of a Sun–Earth system observatory. But the domain of space weather is vast – extending from deep within the Sun to far outside the planetary orbits – and the physics complex – including couplings between various types of physical processes that link scales and domains from the microscopic to large parts of the solar system. Consequently, advanced understanding of space weather requires a coordinated international approach to effectively provide awareness of the processes within the Sun–Earth system through observation-driven models. This roadmap prioritizes the scientific focus areas and research infrastructure that are needed to significantly advance our understanding of space weather of all intensities and of its implications for society. Advancement of the existing system observatory through the addition of small to moderate state-of-the-art capabilities designed to fill observational gaps will enable significant advances. Such a strategy requires urgent action: key instrumentation needs to be sustained, and action needs to be taken before core capabilities are lost in the aging ensemble. We recommend advances through priority focus (1) on observation-based modeling throughout the Sun–Earth system, (2) on forecasts more than 12 h ahead of the magnetic structure of incoming coronal mass ejections, (3) on understanding the geospace response to variable solar-wind stresses that lead to intense geomagnetically-induced currents and ionospheric and radiation storms, and (4) on developing a comprehensive specification of space climate, including the characterization of extreme space storms to guide resilient and robust engineering of technological infrastructures. The roadmap clusters its implementation recommendations by formulating three action pathways, and outlines needed instrumentation and research programs and infrastructure for each of these. An executive summary provides an overview of all recommendations.


Journal: Journal of Atmospheric and Solar-Terrestrial Physics
Title: An Analysis of Large Forbush Decrease Events using Phase Diagrams of View Channels of the Nagoya Multidirectional Muon Telescope
General Information: Available online 1 January 2015, Volume 123, Pages 124-136
Author(s): G. Kalugin, K. Kabin
Abstract: Large Forbush decrease (FD) events are analysed using data recorded by the ground-based Nagoya multi-directional muon telescope in Japan. As a part of the analysis we introduce a phase diagram for the channels of telescope, which provides more robust information about characteristics of events. Specifically, the slope of the regression line in the phase diagram represents the FD amplitude which can be computed for different channels. This allows us to analyze the dependence of the FD amplitude on the rigidity of CR particles. Two models for this dependence are considered, a power law and exponential and the former is found to be more suitable for the considered events. In terms of the power-law index and the FD amplitude the events are split into two groups. It is shown that the larger events are characterized by smaller power-law index than the smaller ones.


Journal: Journal of Atmospheric and Solar-Terrestrial Physics
Title: Time Evolution of Ionization Effect due to Cosmic Rays in Terrestrial Atmosphere during GLE 70
General Information: Available online 5 May 2015, Volume 129, Pages 78-86
Author(s): A. L. Mishev, P. I. Y. Velinov
Abstract: In the last years the possible effect of solar variability on atmospheric physics and chemistry is highly debated. In most of the proposed models the role of ion production in the atmosphere due to cosmic rays is significant. At present, effects on minor constituents and aerosols are observed over polar regions during major solar events. According to recent findings for such a study it is necessary an essential increase of ion production, specifically during the winter season. Therefore, the ground level enhancement on 13th of December 2006 is appropriate for such a study. Here, we compute the ion production on 13th of December 2006 on the basis of a full target model based on Monte Carlo simulations. The ion production is computed on a step ranging from 10 to 30 min throughout the event. The spectral and angular characteristics of the solar protons are explicitly considered as well as their time evolution. The ionization effect is computed at several altitudes above the sea level, namely 25 km, 18 km, 15 km, 12 km and 8 km in a sub-polar a and polar region, where the effect is maximal. Several applications of the obtained results are discussed.


Journal: Quaternary Geochronology
Title: CRONUS-Earth Cosmogenic 36Cl Calibration
General Information: Available online 22 October 2015, Volume 31, Pages 199-219
Author(s): Shasta M. Marrero, Fred M. Phillips, Marc W. Caffee, John C. Gosse
Abstract: Chlorine-36 production rates obtained from different geological calibration studies (e.g. Evans et al., 1997; Phillips et al., 2001; Schimmelpfennig et al., 2011; Stone et al., 1996; Swanson and Caffee, 2001) vary significantly, principally because of the many reactions contributing to the production of this nuclide. The CRONUS-Earth Project has provided high-quality geological calibration sites, including Lake Bonneville, Peru, and Scotland, for a large-scale calibration of 36Cl production rates. Three sites were used to calibrate the K and Ca spallation pathways for 36Cl production yielding production rates of 56.0 ± 4.1 at 36Cl (g Ca)−1 yr−1 and 155 ± 11 at 36Cl (g K)−1 yr−1 respectively, using Lifton-Sato-Dunai scaling (LSDn). The low-energy production parameter, Pf(0), was calibrated separately using CRONUS-Earth data from the Bonneville and Baboon Lakes sites where Cl concentrations were higher, and yielded a value of 759 ± 180 neutrons (g air)−1 yr−1. There is significant uncertainty associated with this pathway due to the sensitivity of this reaction to environmental conditions. The uncertainties associated with the calibrated production parameters were estimated based on the variance of calculated ages from independent ages for an independent secondary dataset.


Journal: Advances in Space Research
Title: The Storm of March 1989 Revisited: A Fresh Look at the Event
General Information: Published 1 January 2015, Volume 55, Issue 1, Pages 211-219
Author(s): A. V. Schirochkov, L. N. Makarova, V. D. Nikolaeva, A. L. Kotikov
Abstract: Some new features of the well known geomagnetic storm of March 1989 are presented in this paper. They include more detailed description of the geophysical situation in the Eastern hemisphere (Siberian sector) as well as more careful consideration of the dynamics of the energetic particle precipitation during the event. More attention is given to the peculiarities of the geomagnetic activity at that time. Change of the magnetospheric configuration during active phase of the storm is especially noteworthy. Intriguing feature of this storm is the impulsive powerful solar proton event (SPE) with simultaneous impulsive intense precipitation of the protons with “soft” energetic spectra (1–40 MeV) appearing in a time interval between 02 and 12 UT of March 13 at the background of a previously existing moderate energetic proton flux. Intensity of this impulsive SPE was very high (up to 5300 pfu for protons with E > 10 MeV). Most probably this SPE was caused by the impulsive solar X-ray flare (N28, W02) classified as X-1.4. It is worth to note that this peak of the proton fluxes was recorded at the same time (07:45 UT) when the Quebec energetic system was collapsed. Simultaneous sharp decrease of the geomagnetic indices AU, AL and PC (Polar Cap index) with a fast recovery time was recorded. Precipitation of more soft particles (E = 30–30,000 eV) was studied by the data of the DMSP 8 and 9 satellites. Equatorward protrusion of the soft particles precipitation boundary reached such lower geomagnetic latitudes as 45 degrees. A specific feature of this storm was absence of the satellite measurements of the solar wind and Interplanetary Magnetic Field (IMF) during several days including active phase of the event. Under these circumstances more important became the data obtained by ground-based geophysical observations especially at the high-latitudes. A special attention was given to the elements of the storm whose peaks were close to time of technological catastrophe (07–45 UT of March 13 1989).


Journal: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment
Title: The Sensitivity of LaBr3:Ce Scintillation Detectors to Low Energy Neutrons: Measurement and Monte Carlo Simulation
General Information: Published 21 February 2015, Volume 774, Pages 17-24
Author(s): J.L. Tain, J. Agramunt, A. Algora, A. Aprahamian, D. Cano-Ott, L.M. Fraile, C. Guerrero, M.D. Jordan, H. Mach, T. Martinez, E. Mendoza, M. Mosconi, R. Nolte
Abstract: The neutron sensitivity of a cylindrical ⊘1.5 in.×1.5 in. LaBr3:Ce scintillation detector was measured using quasi-monoenergetic neutron beams in the energy range from 40 keV to 2.5 MeV. In this energy range the detector is sensitive to γ-rays generated in neutron inelastic and capture processes. The experimental energy response was compared with Monte Carlo simulations performed with the Geant4 simulation toolkit using the so-called High Precision Neutron Models. These models rely on relevant information stored in evaluated nuclear data libraries. The performance of the Geant4 Neutron Data Library as well as several standard nuclear data libraries was investigated. In the latter case this was made possible by the use of a conversion tool that allowed the direct use of the data from other libraries in Geant4. Overall it was found that there was good agreement with experiment for some of the neutron data bases like ENDF/B-VII.0 or JENDL-3.3 but not with the others such as ENDF/B-VI.8 or JEFF-3.1.


Journal: Earth, Planets, and Space
Title: Search for Solar Neutrons at Mount Chacaltaya Associated with M- and X- Class Flares During the Rising Period of Solar Cycle 24
General Information: Published December 2015
Author(s): Diego Lopez, Yutaka Matsubara
Abstract: To better understand the acceleration mechanism of high-energy particles that are driven by solar flares, we examined solar neutron signals. We have performed a statistical analysis by reviewing the data collected by a neutron monitor during the period of January 2010 to August 2013. This detector operates at Mount Chacaltaya in Bolivia at 5,200 m above sea level. Our aim is to search for solar neutron events in association with large solar flares observed by the GOES satellite. We report that our analysis did not yield any positive excess due to solar neutrons that are statistically significant. Hence, we calculated the upper limit of the number of solar neutrons for the X2.8-class solar flare which occurred on 13 May 2013. We performed a similar calculation with a solar neutron event that occurred on 7 September 2005. Our upper limit is seven times less than the one produced by the real signal.


Journal: Advances in Space Research
Title: North-South Component of Galactic Cosmic-Ray Anisotrophy at 1 AU
General Information: Accepted 30 September 2015, Available online 9 October 2015, Volume 56, Issue 11, Pages 2649-2653
Author(s): H. S. Ahluwalia
Abstract: The galactic cosmic ray (GCR) solar diurnal anisotropy (SDA) may be represented by a vector (
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