Journal: Journal of Atmospheric and Solar-Terrestrial Physics
Title: The Inter-Annual Distribution of Cloudless Days and Nights in Abastumani: Coupling with Cosmic Factors and Climate Change
General Information: Accepted 2 October 2015, Available online 9 October 2015
Author(s): G. G. Didebuildze, M. Todua
Abstract: We examined inter-annual variations and long-term trends of cloudless days (CD) and cloudless nights (CN) in 1957–1993 from Abastumani (41.75N, 42.82E), at different geomagnetic conditions and corresponding galactic cosmic rays (GCRs) flux changes. It showed possible influence of cosmic factors on cloud covering processes and, thus, climate change. It was demonstrated that (1) the inter-annual distribution of monthly mean values of planetary geomagnetic index Ap (for low and moderate disturbances) at CDs can be described by harmonic function with semiannual (with sharp maxima in March and September) and annual (with maximum in August) periodicities; (2) the inter-annual distribution of Ap index for CN has an additional maximum in June, where the largest decrease of GCR flux is observed. This phenomenon is expressed even stronger during Sudden Storm Commencement (SSC) events and strong geomagnetic disturbances (Ap≥50), when their relative numbers are the greatest and are accompanied by bigger reduction of GCRs flux; (3) the long-term trends of mean annual and mean seasonal values of Ap index and GCRs flux at CD and CN are estimated. It was detected that, for the latitudes of this region, long-term decreases (negative trends) of seasonal GCR flux are different at CD and CN, which could affect the radiative balance at the Earth's surface and, as a result, contribute to the climate change.
Journal: The Astrophysical Journal
Title: Sensitivity of Cosmic-Ray Proton Spectra to the Low-Wavenumber Behavior of the 2D Turbulence Power Spectrum
General Information: Published 1 December 2015, Volume 814, Number 2
Author(s): N. E. Engelbrecht, R. A. Burger
Abstract: In this study, a novel ab initio cosmic ray (CR) modulation code that solves a set of stochastic transport equations equivalent to the Parker transport equation, and that uses output from a turbulence transport code as input for the diffusion tensor, is introduced. This code is benchmarked with a previous approach to ab initio modulation. The sensitivity of computed galactic CR proton spectra at Earth to assumptions made as to the low-wavenumber behavior of the two-dimensional (2D) turbulence power spectrum is investigated using perpendicular mean free path expressions derived from two different scattering theories. Constraints on the low-wavenumber behavior of the 2D power spectrum are inferred from the qualitative comparison of computed CR spectra with spacecraft observations at Earth. Another key difference from previous studies is that observed and inferred CR intensity spectra at 73 AU are used as boundary spectra instead of the usual local interstellar spectrum. Furthermore, the results presented here provide a tentative explanation as to the reason behind the unusually high galactic proton intensity spectra observed in 2009 during the recent unusual solar minimum.
Journal: Quaternary Geochronology
Title: Physics-Based Modeling of Cosmogenic Nuclides Part 1 – Radiation Transport Methods and New Insights
General Information: Available online 30 September 2014, Volume 26, Pages 29-43
Author(s): David C. Argento, John O. Stone, Robert C. Reedy, Keran O’Brien
Abstract: We present a comprehensive, nuclear-physics-based cosmogenic nuclide production rate model combining radiation transport modeling with excitation functions for commonly measured nuclides. This model allows investigation of factors influencing nuclide production, such as the energy spectrum and angular distribution of the incident radiation that cannot be easily isolated in calibration measurements on natural samples. We present neutron and proton fluxes over a range of atmospheric depths and cut-off rigidities. Calculated production rates for 3He, 10Be, 14C, 21Ne, 26Al, and 36Cl based on these fluxes are presented. The model predicts that production rates for these nuclides diverge from one another with altitude, hence that production ratios depend on altitude. Compared to existing scaling schemes, the model predicts a larger difference between sea-level production rates at low and high latitude.
Journal: Journal of Atmospheric and Solar-Terrestrial Physics
Title: Influence of Cosmic-Ray Variability on the Monsoon Rainfall and Temperature
General Information: Accepted 19 November 2014, Available online 22 November 2014, Volume 122, Pages 86-96
Author(s): Badruddin, O. P. M. Aslam
Abstract: We study the role of galactic cosmic ray (GCR) variability in influencing the rainfall variability in Indian Summer Monsoon Rainfall (ISMR) season. We find that on an average during ‘drought’ (low ISMR) periods in India, GCR flux is decreasing, and during ‘flood’ (high ISMR) periods, GCR flux is increasing. The results of our analysis suggest for a possibility that the decreasing GCR flux during the summer monsoon season in India may suppress the rainfall. On the other hand, increasing GCR flux may enhance the rainfall. We suspect that in addition to real environmental conditions, significant levitation/dispersion of low clouds and hence reduced possibility of collision/coalescence to form raindrops suppresses the rainfall during decreasing GCR flux in monsoon season. On the other hand, enhanced collision/coalescence efficiency during increasing GCR flux due to electrical effects may contribute to enhancing the rainfall. Based on the observations, we put forward the idea that, under suitable environmental conditions, changing GCR flux may influence precipitation by suppressing/enhancing it, depending upon the decreasing/increasing nature of GCR flux variability during monsoon season in India, at least. We further note that the rainfall variability is inversely related to the temperature variation during ISMR season. We suggest an explanation, although speculative, how a decreasing/increasing GCR flux can influence the rainfall and the temperature. We speculate that the proposed hypothesis, based on the Indian climate data can be extended to whole tropical and sub-tropical belt, and that it may contribute to global temperature in a significant way. If correct, our hypothesis has important implication for the sun - climate link.
68) (3) THIS IS A GOOD SOURCE
Darzi, M.A., et al. "Cosmic ray modulation studies with Lead-Free Gulmarg Neutron Monitor." Astroparticle Physics 54 (2014): 81+. Academic OneFile. Web. 6 Jan. 2016.
Abstract: A lead-free neutron monitor operating at High Altitude Research Laboratory (HARL), Gulmarg optimized for detecting 2.45MeV neutron bursts produced during the atmospheric lightning discharges is also concurrently used for studying background neutron component present in the atmosphere. These background neutrons are produced due to the interaction of primary cosmic rays with the atmospheric constituents. In order to study and extract the information about the yield of the neutron production during transient atmospheric lightning discharges, the system is continuously operated to monitor and record the cosmic ray produced background secondary neutrons in the atmosphere. The data analysis of the background neutrons recorded by Lead-Free Gulmarg Neutron Monitor (LFGNM) has convincingly established that the modulation effects due to solar activity phenomena compare very well with those monitored by the worldwide IGY or NM64 type neutron monitors which have optimum energy response relatively towards the higher energy regime of the cosmic rays. The data has revealed various types of modulation phenomena like diurnal variation, Forbush decrease etc. during its entire operational period. However, a new kind of a periodic/seasonal variation pattern is also revealed in the data from September 2007 to September 2012, which is seen to be significantly consistent with the data recorded by Emilio Segre observatory, Israel (ESOI) Neutron Monitor. Interestingly, both these neutron monitors have comparable latitude and altitude. However, the same type of consistency is not observed in the data recorded by the other conventional neutron monitors operating across the globe.
69) (4) THIS IS A GOOD SOURCE
Sapundjiev, Danislav, et al. "Data reduction and correction algorithm for digital real-time processing of cosmic ray measurements: NM64 monitoring at Dourbes." Advances in Space Research 53.1 (2014): 71+. Academic OneFile. Web. 6 Jan. 2016.
Abstract: We present a data correction algorithm for real-time data processing for the NM64 galactic cosmic ray neutron monitor at the Royal Meteorological Institute (RMI) in Dourbes, Belgium. The correction is based on three main tests: a continuity test, tube ratios test and a derivative test. The continuity test works as a high pass filter with a threshold based on the entire recorded dataset. Additionally, it monitors whether the logging takes place at regular intervals (continuously). The ratios test identifies noisy sections and the final derivative test criterion will identify single or double spikes by testing them against the median increase of the intensities. Using these criteria, all data from the cosmic ray station at Dourbes is corrected in real time. Test results have been compared with data from verified neutron monitor stations with a similar geomagnetic cutoff rigidity.
Journal: Astroparticle Physics
Title: A Model of the Cosmic Ray Induced Atmospheric Neutron Environment
General Information: Accepted 6 October 2014, Available online 14 October 2014, Volume 62, Pages 230-240
Author(s): Merlin Kolea, Mark Pearce, Maria Muñoz Salinas
Abstract: In order to optimise the design of space instruments making use of detection materials with low atomic numbers, an understanding of the atmospheric neutron environment and its dependencies on time and position is needed. To produce a simple equation based model, Monte Carlo simulations were performed to obtain the atmospheric neutron fluxes produced by charged galactic cosmic ray interactions with the atmosphere. Based on the simulation results the omnidirectional neutron environment was parametrized including dependencies on altitude, magnetic latitude and solar activity. The upward- and downward-moving component of the atmospheric neutron flux are considered separately. The energy spectra calculated using these equations were found to be in good agreement with data from a purpose built balloon-borne neutron detector, high altitude aircraft data and previously published simulation based spectra.
Journal: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment
Title: PoGOLino: A Scintillaor-Based Balloon-Borne Neutron Detector
General Information: Accepted 7 October 2014, Available online 15 October 2014, Volume 770, Pages 68-75
Author(s): Merlin Kole, Maxime Chauvin, Yasushi Fukazawa, Kentaro Fukuda, Sumito Ishizu, Miranda Jackson, Tune Kamae, Noriaki Kawaguchi, Takafumi Kawano, Mózsi Kiss, Elena Moretti, Mark Pearce, Stefan Rydström, Hiromitsu Takahashi, Takayuki Yanagida
Abstract: PoGOLino is a balloon-borne scintillator-based experiment developed to study the largely unexplored high altitude neutron environment at high geomagnetic latitudes. The instrument comprises two detectors that make use of LiCAF, a novel neutron sensitive scintillator, sandwiched by BGO crystals for background reduction. The experiment was launched on March 20th 2013 from the Esrange Space Centre, Northern Sweden (geomagnetic latitude of 65°), for a three hour flight during which the instrument took data up to an altitude of 30.9 km. The detector design and ground calibration results are presented together with the measurement results from the balloon flight.
Journal: Advances in Space Research
Title: Neutron Monitors and Muon Detectors for Solar Modulation Studies: Interstellar Flux, Yield Function, and Assessment of Critical Parameters in Count Rate Calculations
General Information: Accepted 16 June 2014, Available online 24 June 2014, Volume 55, Issue 1, Pages 363-389
Author(s): D. Maurin, A. Cheminet, L. Derome, A. Ghelfi, G. Hubert
Abstract: Particles count rates at given Earth location and altitude result from the convolution of (i) the interstellar (IS) cosmic-ray fluxes outside the solar cavity, (ii) the time-dependent modulation of IS into Top-of-Atmosphere (TOA) fluxes, (iii) the rigidity cut-off (or geomagnetic transmission function) and grammage at the counter location, (iv) the atmosphere response to incoming TOA cosmic rays (shower development), and (v) the counter response to the various particles/energies in the shower. Count rates from neutron monitors or muon counters are therefore a proxy to solar activity. In this paper, we review all ingredients, discuss how their uncertainties impact count rate calculations, and how they translate into variation/uncertainties on the level of solar modulation ϕ (in the simple Force-Field approximation). The main uncertainty for neutron monitors is related to the yield function. However, many other effects have a significant impact, at the 5–10% level on ϕ values. We find no clear ranking of the dominant effects, as some depend on the station position and/or the weather and/or the season. An abacus to translate any variation of count rates (for neutron and μ detectors) to a variation of the solar modulation ϕ is provided.
Journal: Solar Cosmic Rays
Title: Spectrum of Solar Cosmic Rays Near the Earth
General Information: Published 22 August 2014, Volume 405 of the series Astrophysics and Space Science Library, Pages 299-332
Author(s): Leonty Mirochnichenko
Abstract: As it was postulated in Chap. 1, an energy distribution (or a shape of the energy spectrum) of solar cosmic rays (SCR) is of great significance for the formulation of self-consistent model of particle acceleration at the Sun. In turn, the main problems of fundamental interest in the theory of particle acceleration at the Sun lie now at two boundary domains of SCR spectra, namely, in low-energy (non-relativistic) and high-energy (relativistic) ranges. The most important of them are: initial acceleration from the thermal background (see, e.g., Vlahos et al. 1989; Simnett 1995; Miroshnichenko 1995; Miller et al. 1997) and final stage of acceleration to extremely high energies (see, e.g., Miroshnichenko 1994, 1996; Karpov et al. 1995a, b, 1998).
Journal: Solar Cosmic Rays
Title: Interactions of Accelerated Particles with the Solar Atmosphere
General Information: Published 22 August 2014, Volume 405 of the series Astrophysics and Space Science Library, Pages 165-210
Author(s): Leonty Miroshnichenko
Abstract: As one can see from above considerations, in no other situation except for that during solar flares the acceleration of charged particles can be explored in such details, because (a) events can be studied in their temporal history and (b) the Sun is near enough to investigate the phenomenon in a very wide energy range from X-rays to gamma rays – two main kinds of flare neutral radiation, where the accelerated particles leave their “fingerprints” more clearly.
Logachev, Yu.I., L.L. Lazutin, and K. Kudela. "Cosmic ray investigation in the stratosphere and space: results from instruments on Russian satellites and balloons." Advances in Astronomy (2013).Academic OneFile. Web. 7 Jan. 2016.
Abstract: Selected activities aimed to investigate cosmic ray fluxes and to contribute to the understanding of the mechanisms behind, over a long-time period using space research tools in the former USSR/Russia and Slovakia, are reviewed, and some of the results obtained are presented. As the selection is connected with the institutes where the authors are working, it represents only a partial review of this wide topic.
Journal; American Institute of Physics: Conference Proceedings
Title: The Variable Nature of the Cosmic Ray Intensity over the past 10,000 Years
General Information: Published online 07 February 2013
Author(s): Ken McCracken
Abstract: As first recognized by Lal and Peters, the cosmogenic radionuclides, 10Be and 14C, provide a record of the time dependent changes in the intensity of the galactic cosmic radiation at Earth in the past. We now have three independent cosmogenic records, each spanning the past 10,000 years, that allow us to compare the cosmic radiation intensity and solar activity during the modern "space era" with those since the end of the last glacial epoch. They show that the Sun has experienced twenty-six extended periods of low activity, called "Grand Minima", each similar to the Maunder Minimum (1650-1715). During such times, the near earth cosmic radiation intensity in the vicinity of 3GeV was a factor of 2-3 greater than during the "space era". The paleo-cosmic ray (PCR) data exhibit a number of persistent periodicities that modulate the amplitude of the 11-year cycle of cosmic ray intensity. The most prominent are the Gleissberg (∼87 y); the de Vries (∼208 y); the Eddy (∼978 y) and the Hallstatt (∼2320 y) periodicities. The Hallstatt periodicity is responsible for the sequence of "Grand Minima" that occurred between the 11th and 19th centuries, and a similar one thousand yearlong sequence that occurred ∼6000 yrs. ago. These periods of low solar activity were accompanied by "little ice ages". The speaker will outline the manner in which the present day high quality PCR record is providing the means to study the properties of the solar dynamo, and "space weather" in the past, and permit projections to be made into the future.
Journal: Journal of the Korean Physical Society
Title: Analysis of the Ambient Dose Variation due to Cosmic Rays in Daejeon by using a Neutron Monitor
General Information: Published December 2013, Volume 63, Issue 11, Pages 2262-2268
Author(s): Yun Ho Kim, Jeongsoo Kang, Doh-Yun Jang, Jae Bum Son, Yong-Kyun Kim, Sung Joong Kim
Abstract: The Basic Atomic Energy Research Institute of Hanyang University in Korea has constructed a cosmic-ray detection system that is presently being operated. In this study, the impact of cosmic-rays on 18-tube NM64-type neutron monitor installed in Daejeon was confirmed for the first time. In order to evaluate the reliability of the neutron monitor, we predicted the count rates from the neutron flux by using the Excel-based Program for calculating Atmospheric Cosmic-ray Spectrum (EXPACS); these predictions were then compared with experimental results. The predictions agree well with the results, with differences no greater than 3.95%. Also, changes in the neutron ambient dose equivalent rate from cosmic rays due to different environmental conditions were analyzed using EXPACS; the results obtained were compared with those of previous studies and were thus, confirmed to be reliable, suggesting that the detection system is suitable for making the relevant measurements. That detection system was then used to evaluate the neutron ambient dose equivalent rate for various environmental conditions in Daejeon. Finally, a conversion coefficient, defined as the ratio of counts from the neutron monitor to the neutron ambient dose equivalent, was obtained and included considerations of the impacts of geological factors and of meteorological factors of relative humidity and atmospheric depth. The derived formula fit the source data with an adjusted coefficient of determination (R 2) of 0.9894 and a root-mean-square error of 1.7056 × 10−10, equivalent to about 1%. This confirmed satisfactory accuracy and reliability of the formula, thereby showing this methodology to be legitimate for use in evaluating the neutron ambient dose equivalent by using the Daejeon neutron monitor.
Hyperlink: Full Text not Available
Journal: Journal of the Korean Physical Society
Title: Comparing Hadronic Models of GEANT4 for the Neutron Monitor Response Function
General Information: Published September 2013, Volume 63, Issue 6, Pages 1228-1233
Author(s): Jeongsoo Kang, Yunho Kim, Jae Bum Son, Doh Yun Jang, Yong-Kyun Kim, Sung Joong Kim
Abstract: The NM64 neutron monitor is the most popular instrument that measures the number of highenergy particles impacting the Earth from space. A simulation of the NM64 neutron monitor response function with the GEANT4 toolkit is conducted, and the result is processed to compare low- and high-energy hadronic models provided by this Monte Carlo code. Results shows that the thermal interaction for hydrogen in polyethlene for neutron energies less than 4 eV has a great influence. G4NeutronHP and G4LEND models are compared for low-energy neutrons in this study. At energies from 20 MeV to 10 GeV, the Bertini Cascade and the Binary Cascade models are used and evaluated as applicable physics lists. At energies above 10 GeV, the FTFP and the QGSP physics models are applied to calculate the response function, and the results are a few percents higher than the FLUKA results found in the literature.
Hyperlink: Full Text not Available
Journal: Solar Physics
Title: Artificial Neural Network Approach of Cosmic Ray Primary Data Processing
General Information: Published January 2013, Volume 282, Issue 1, Pages 303-318
Author(s): P. Paschalis, C. Sarlanis, H. Mavromichalaki
Abstract: One of the most critical points in the detection of cosmic rays by neutron monitors is the correction of the raw data. The data that a detector measures may be distorted by a variety of reasons and the subtraction of these distortions is a prerequisite for processing them further. The final aim of these corrections is to keep only the fluctuations related to the real cosmic-ray intensity. To achieve this, we analyze data from identical neutron monitor detectors which provide a configuration with the ability to exclude the distortions by comparing the counting rate of each detector. Based on this method, a number of effective algorithms have been developed: Median Editor, Median Editor Plus, and Super Editor are some of the algorithms that are being used in the neutron monitor data processing with satisfactory results. In this work, a new approach for the correction of the neutron monitor primary data with a completely different method, based on the use of artificial neural networks, is proposed. A comparison of this method with the algorithms mentioned previously is also presented.