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1
Ardashev, Khamit. "Asymmetry and Cross Section Measurements of Neutral Pion Photo-Production in the Range 240-405 MeV." Ohio University / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1020689523.
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張增 and Tsang Cheung. "Primary cosmic ray composition at 10 [to the power] 15--10 [to the power] 17eV studied from extensive air shower simulations." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1985. http://hub.hku.hk/bib/B31230593.
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Cheung, Tsang. "Primary cosmic ray composition at 10 [to the power] 15--10 [to the power] 17eV studied from extensive air shower simulations /." [Hong Kong : University of Hong Kong], 1985. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12266176.
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Gabici, Stefano. "Gamma ray astronomy and the origin of galactic cosmic rays." Habilitation à diriger des recherches, Université Paris-Diderot - Paris VII, 2011. http://tel.archives-ouvertes.fr/tel-00719791.
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Diffusive shock acceleration operating at expanding supernova remnant shells is by far the most popular model for the origin of galactic cosmic rays. Despite the general consensus received by the model, an unambiguous and conclusive proof of the supernova remnant hypothesis is still missing. In this context, the recent developments in gamma ray astronomy provide us with precious insights into the problem of the origin of galactic cosmic rays, since production of gamma rays is expected both during the acceleration of cosmic rays at supernova remnant shocks and during their subsequent propagation in the interstellar medium. In particular, the recent detection of a number of supernova remnants at TeV energies nicely fits with the model, but it still does not constitute a conclusive proof of it, mainly due to the difficulty of disentangling the hadronic and leptonic contributions to the observed gamma ray emission. The main goal of my research is to search for an unambiguous and conclusive observational test for proving (or disproving) the idea that supernova remnants are the sources of galactic cosmic rays with energies up to (at least) the cosmic ray knee. Our present comprehension of the mechanisms of particle acceleration at shocks and of the propagation of cosmic rays in turbulent magnetic fields encourages beliefs that such a conclusive test might come from future observations of supernova remnants and of the Galaxy in the almost unexplored domain of multi-TeV gamma rays.
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Lee, Anthony A. "Application of Monte Carlo methods to some problems in high energy astrophysics /." Title page, contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09phl4768.pdf.
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Guberman, Daniel Alberto. "MAGIC observations with bright Moon and their application to measuring the VHE gamma-ray spectral cut-off of the PeVatron candidate Cassiopeia A." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/664122.
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Los rayos cósmicos son núcleos atómicos que constantemente bombardean la Tierra. Está largamente aceptado que estos núcleos con energías de hasta ~3 PeV son de origen Galáctico. Pero aún no se sabe dónde en la Galaxia ni cómo son acelerados. Durante muchos años la hipótesis más popular ha sido que son acelerados en remanentes de supernova. En esta tesis presento los detalles de una serie de observaciones de la joven remanente de supernova Cassiopeia A, uno de los candidatos más prometedores a ser un Pevatrón, un sistema capaz de acelerar rayos cósmicos hasta energías de PeV. Las observaciones fueron realizadas con los telescopios MAGIC, que observan rayos gamma de muy alta energía (VHE, E > 50 GeV), entre Diciembre de 2014 y Octubre de 2016, adquiriendo 191 horas de datos buena calidad. Acumular una gran cantidad de horas de observación era indispensable para obtener una medida precisa del espectro y fue posible gracias a la posibilidad de extender el tiempo activo de MAGIC operando los telescopios bajo una luminosidad lunar intensa. Trabajé en la optimización de las observaciones con Luna en MAGIC, tanto en el momento de operar los telescopios como en la etapa del análisis de los datos. Abordo los detalles de este desarrollo y evaluó su rendimiento. Con más del 70 % de las horas obtenidas con la Luna presente en el cielo, he podido obtener el espectro más preciso hasta ahora de Cassiopeia A en VHE. Por primera vez se encuentra evidencia de un corte a E = 3,5 (+1,6\—1,0) stat (+0,8\−0,9) sys TeV en el espectro. El
modelado de dicho espectro sugiere que la mayoría de los rayos gamma emitidos
pueden ser atribuidos a una población de protones de muy alta energía con un
índice espectral de ~2.2 y un corte a ~10 TeV. Esto implica que, asumiendo que no hay una difusión significativa d elos rayos cósmicos en el entorno de la supernova, Cassiopeia A no puede ser un PeVatrón en este momento.Cosmic rays are atomic nuclei that are constantly bombarding the Earth. It is widely accepted that these nuclei with energies up to ~3 PeV are of Galactic origin. But the question about where in the Galaxy and how they are accelerated still remains unanswered. For several years the most popular hypothesis has been that they are accelerated in supernova remnants. In this thesis I present the details of a deep observation campaign on the young supernova remnant Cassiopeia A, one of the most promising candidates to be a PeVatron, a system capable of accelerating cosmic rays up to PeV energies. The observations were performed with the MAGIC telescopes, that observe very high energy (VHE, E > 50 GeV) gamma rays, between December 2014 and October 2016, acquiring 191 hours of good-quality data. Accumulating a large amount of observation hours was indispensable to obtain a precise measurement of the spectrum and it was possible thanks to the possibility of extending the MAGIC duty cycle by operating the telescopes under bright moonlight. I worked in the optimization of moonlight observations with MAGIC, both during the operation of the telescopes and at the data analysis stage. I discuss the details of these developments and the resulting performance. With more than 70% of the data obtained under moonlight, I was able to obtain the most precise spectrum of Cassiopeia A to date at VHE. The obtained spectrum shows for the rst time 4:9 evidence of a cut-o at E = 3,5 (+1,6\—1,0) stat (+0,8\−0,9) sys TeV. The modelling of the spectrum suggests that the bulk of the gamma-rays emitted can be attributed to a population of high-energy protons with spectral index ~2.2 and energy cuto at ~10 TeV. This implies that, assuming there is no signicant cosmic-ray diusion, Cassiopeia A cannot be a PeVatron at its present age.
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Pinzke, Anders. "Gamma-Ray Emission from Galaxy Clusters : DARK MATTER AND COSMIC-RAYS." Doctoral thesis, Stockholms universitet, Fysikum, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-42453.
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The quest for the first detection of a galaxy cluster in the high energy gamma-ray regime is ongoing, and even though clusters are observed in several other wave-bands, there is still no firm detection in gamma-rays. To complement the observational efforts we estimate the gamma-ray contributions from both annihilating dark matter and cosmic-ray (CR) proton as well as CR electron induced emission. Using high-resolution simulations of galaxy clusters, we find a universal concave shaped CR proton spectrum independent of the simulated galaxy cluster. Specifically, the gamma-ray spectra from decaying neutral pions, which are produced by CR protons, dominate the cluster emission. Furthermore, based on our derived flux and luminosity functions, we identify the galaxy clusters with the brightest galaxy clusters in gamma-rays. While this emission is challenging to detect using the Fermi satellite, major observations with Cherenkov telescopes in the near future may put important constraints on the CR physics in clusters. To extend these predictions, we use a dark matter model that fits the recent electron and positron data from Fermi, PAMELA, and H.E.S.S. with remarkable precision, and make predictions about the expected gamma-ray flux from nearby clusters. In order to remain consistent with the EGRET upper limit on the gamma-ray emission from Virgo, we constrain the minimum mass of substructures for cold dark matter halos. In addition, we find comparable levels of gamma-ray emission from CR interactions and dark matter annihilations without Sommerfeld enhancement.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Accepted.
8
Wilkinson, Christopher Richard. "The application of high precision timing in the high resolution fly's eye cosmic ray detector." Title page, contents and abstract only, 1998. http://hdl.handle.net/2440/37715.
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This thesis represents work performed by the author on the development of the High Resolution Fly's Eye (HiRes) detector for the study of extremely high energy (>10 [superscript 18] eV) cosmic rays. Chapter 1 begins with an review of this field. This chapter details the development of the field, the physics questions we seek to answer, and our current understanding based on experimental and theoretical results. It provides the basis for understanding why detectors such as HiRes are being constructed. This review leads into chapter 2, which discuses the development of cosmic ray induced extensive air showers (EAS) and the techniques used to study them. Particular emphasis is placed upon the air fluorescence technique utilised by HiRes. The two site HiRes prototype detector is then discussed in detail in chapter 3. This covers the different components that form the detector, together with details of the calibration performed to extract useful information from the data. Chapter 4 discusses the installation and subsequent testing of GPS based clock systems for the two sites that make up the HiRes prototype detector. The entire timing system was checked, and some previously hidden bugs fixed. This chapter concludes with work performed on the time to digital converter calibration for the second HiRes site. The high relative timing accuracy provided by the GPS clocks allowed the use of timing information in programs to reconstruct the arrival directions of cosmic rays. Chapter 5 covers the development of a program to use geometrical and timing information to reconstruct EAS viewed by both HiRes sites. This chapter concludes with an evaluation of the likely reconstruction accuracy of the new HiRes (stage1) detector. A well reconstructed EAS trajectory is the first step in the determination of more interesting parameters such as primary particle energy. Chapter 6 covers the collation and analysis of EAS viewed by the both sites of the prototype detector. This includes an evaluation of effects such as the atmosphere, and an estimation of the performance of the new (stage 1) HiRes detector based on results with the prototype detector. Finally the conclusions from this thesis are summarised and sugestions made for further follow up work.Thesis (Ph.D.)--Department of Physics and Mathematical Physics, 1998.
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Chadwick, Mary Paula. "Very high energy cosmic gamma rays from radio and X-ray pulsars." Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6720/.
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This thesis is concerned with the detection of very high energy cosmic gamma-rays from isolated pulsars and X-ray binary sources using the atmospheric Cerenkov technique. A general introduction to gamma ray detection techniques is followed by adscription of the properties of atmospheric Cerenkov radiation and a discussion of the principles of the atmospheric Cerenkov technique. The Mark I and Mark II gamma-ray telescopes operated in Dugway, Utah by the University of Durham between 1981 and 1984 are briefly described. There follows a discussion of the results from observations at many different wavelengths of Cygnus X-3. This object was observed by the Durham group between 1981 and 1983 in Dugway Utah and also in Durham during autumn 1985. The detection in the Dugway data of the 4.8 hr X-ray period and the possible detection of a19.2 day intensity variation are considered. The discovery of a 12.59 ms pulsar in data taken on Cygnus X-3 in 1983 is described. Evidence is presented which suggests this periodicity is also present at a weaker level in earlier data and also in the data taken in Durham in 1985.Results from observations of PSR1937+21 , PSR1953+29and six radio pulsars , are presented. The design and construction of the Mark III telescope, now operating in Narrabri , N.S.W. , is described in detail. Preliminary results from observations with the Mark III telescope of three objects, LMC X-4, the Vela pulsar and CentaurusX-3, are presented, with particular reference to periodicities inherent in the sources. An observation of the supernova in the Large Magellanic Cloud is discussed. A brief discussion of the mechanisms by which V.H.E. gamma-rays may be produced in isolated pulsars and X-ray binary pulsars is given, followed by a description of the future prospects for the Mark III and Mark IV telescopes.
10
Richardson, K. M. "Gamma rays, cosmic rays and local molecular clouds." Thesis, Durham University, 1988. http://etheses.dur.ac.uk/942/.
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Siemens, Xavier. "Gravitational waves and cosmic strings /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2002.
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Thesis (Ph.D.)--Tufts University, 2002.Adviser: Alexander Vilenkin. Submitted to the Dept. of Physics. Includes bibliographical references (leaves 95-98). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Poluianov, S. V. (Stepan V. ). "Proxies for long-term cosmic ray variability." Doctoral thesis, Oulun yliopisto, 2019. http://urn.fi/urn:isbn:9789526213743.
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Abstract The thesis is focused on the reconstruction of long-term cosmic ray variability using proxy data. The 11-year solar cycle in production/deposition rates of cosmogenic nuclides ¹⁰Be and ¹⁴C has been modelled for the conditions of grand minima and maxima of solar activity (namely, Maunder Minimum and Grand Modern Maximum). The result shows that contrary to the observed strongly suppressed amplitude of the solar cycle in sunspots during Maunder Minimum relatively to Grand Modern Maximum, the cosmic ray proxies have the comparable amplitudes during the two periods. This phenomenon is caused by the nonlinear relation between solar activity and production of cosmogenic nuclides. In addition to well-established proxies of cosmic rays, nitrate in polar ice has been recently proposed as a new proxy for the long-term variability of galactic cosmic rays. The thesis contains two tests of its applicability for this purpose with TALDICE and EPICA-Dome C ice core data from Central Antarctica. The results support the proposal for the multimillennial time scales. Lunar samples acquired during the Apollo missions are important data for estimating the averaged energy spectra of galactic cosmic rays and solar energetic particles at the Earth’s orbit. The development in modelling of the interaction between energetic particles and matter makes it necessary to revise the earlier results. Because of that, new production rates of ¹⁰Be and ¹⁴C in lunar samples by galactic cosmic rays and solar energetic particles have been computed. New accurate cosmic ray reconstructions from natural archives containing cosmogenic nuclides use sophisticated climatic models requiring yield functions of the nuclides with high altitude resolution. These functions have been computed for ⁷Be, ¹⁰Be, ¹⁴C, ²²Na, and ³⁶Cl in the Earth’s atmosphere. Overall, the major purpose of the studies presented in the thesis is to increase the quality of reconstructions of the long-term cosmic ray variability for better understanding of the solar and heliospheric physicsOriginal papers The original publications are not included in the electronic version of the dissertation. Poluianov, S. V., Usoskin, I. G., & Kovaltsov, G. A. (2014). Cosmogenic Isotope Variability During the Maunder Minimum: Normal 11-year Cycles Are Expected. Solar Physics, 289(12), 4701–4709. https://doi.org/10.1007/s11207-014-0587-6 Poluianov, S., Traversi, R., & Usoskin, I. (2014). Cosmogenic production and climate contributions to nitrate record in the TALDICE Antarctic ice core. Journal of Atmospheric and Solar-Terrestrial Physics, 121, 50–58. https://doi.org/10.1016/j.jastp.2014.09.011 Poluianov, S., Artamonov, A., Kovaltsov, G., & Usoskin, I. (2015). Energetic particles in lunar rocks: Production of cosmogenic isotopes. Proceedings of Science, 30-July-2015, art. no. 051 . Traversi, R., Becagli, S., Poluianov, S., Severi, M., Solanki, S. K., Usoskin, I. G., & Udisti, R. (2016). The Laschamp geomagnetic excursion featured in nitrate record from EPICA-Dome C ice core. Scientific Reports, 6(1). https://doi.org/10.1038/srep20235 Poluianov, S. V., Kovaltsov, G. A., Mishev, A. L., & Usoskin, I. G. (2016). Production of cosmogenic isotopes 7Be, 10Be, 14C, 22Na, and 36Cl in the atmosphere: Altitudinal profiles of yield functions. Journal of Geophysical Research: Atmospheres, 121(13), 8125–8136. https://doi.org/10.1002/2016jd025034
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吳文謙 and Man-him Ng. "Searching for gamma-ray signals form pulsars and periodic signals fromthe galactic gamma-ray sources." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31213509.
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Ng, Man-him. "Searching for gamma-ray signals form pulsars and periodic signals from the galactic gamma-ray sources /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19667942.
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Ueno, Masaru. "Supernova remnants selected with X-rays : contribution to the galactic cosmic-ray acceleration." 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/145075.
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Kyoto University (京都大学)0048
新制・課程博士
博士(理学)
甲第11307号
理博第2865号
新制||理||1428(附属図書館)
22950
UT51-2005-D58
京都大学大学院理学研究科物理学･宇宙物理学専攻
(主査)教授 小山 勝二, 教授 今井 憲一, 教授 中村 卓史
学位規則第4条第1項該当
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Lacki, Brian Cameron. "Cosmic Rays in Star-Forming Galaxies." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313437011.
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Ngobeni, Mabedle Donald. "Aspects of the modulation of cosmic rays in the outer heliosphere / by Mabedle Donald Ngobeni." Thesis, North-West University, 2006. http://hdl.handle.net/10394/97.
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A time-dependent two-dimensional (2D) modulation model including drifts, the solar wind
tennination shock (TS) with diffusive shock acceleration and a heliosheath based on the
Parker (1965) transport equation is used to study the modulation of galactic cosmic rays
(GCRs) and the anomalous component of cosmic rays (ACRs) in the heliosphere. In
particular, the latitude dependence of the TS compression ratio and injection efficiency of the
ACRs (source strength) based on the hydrodynamic modeling results of Scherer et al. (2006)
is used for the first time in a modulation model. The subsequent effects on differential
intensities for both GCRs and ACRs are illustrated, comparing them to the values without a
latitude dependence for these parameters. It is found that the latitude dependence of these
parameters is important and that it enables an improved description of the modulation of
ACRs beyond the TS. With this modeling approach (without fitting observations) to the
latitude dependence of the two parameters, it is possible to obtain a TS spectrum for ACRs at
a polar angle of B = 55" that qualitatively approximates the main features of the Voyager 1
observations. This positive result has to be investigated further. Additionally, it is shown that
the enhancement of the cosmic ray intensity just below the cut-off energy found for the ACR
at the TS in an A < 0 magnetic polarity cycle in the equatorial plane with the latitude
independent scenario, disappears in this region when the latitude dependence of the
compression ratio and injection efficiency is assumed. Subsequent effects of these scenarios
are illustrated on the global anisotropy vector of both GCRs and ACRs as the main theme of
this work. For this purpose the radial and latitudinal gradients for GCRs and ACRs were
accurately computed. The radial and latitudinal anisotropy components were then computed
as a function of energy, radial distance and polar angle. It is also the first time that the
anisotropy vector is comprehensively calculated in such a global approach to cosmic ray
modeling in the heliosphere, in particular for ACRs. It is shown that the anisotropy vector
inside (up-stream) and outside (down-stream) the TS behaves in a complicated way, so care
must be taken in interpreting it. It is found that the latitude dependence of the two mentioned
parameters can alter the direction (sign) of the anisotropy vector. Its behaviour beyond the TS
is markedly different from inside the TS, mainly because of the slower solar wind velocity,
with less dependence on the magnetic polarity cycles.Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2007.
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Desilets, Darin Maurice. "Cosmogenic nuclides as a surface exposure dating tool: improved altitude/latitude scaling factors for production rates." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1125%5F1%5Fm.pdf&type=application/pdf.
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Chrisman, Bobby Brady. "Quantifying Mesoscale Soil Moisture with the Cosmic-Ray Rover." Thesis, The University of Arizona, 2013. http://hdl.handle.net/10150/293622.
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Existing techniques measure soil moisture either at a point or over a large area many kilometers across. To bridge these two scales, we used the mobile cosmic-ray probe, or cosmic-ray rover, an instrument similar to the recently developed COSMOS probe, but bigger and mobile. This study explores the challenges and opportunities for making maps of soil moisture over large areas using the cosmic-ray rover. In 2012, soil moisture was mapped 22 times in a 25 km x 40 km survey area of the Tucson Basin at 1 km² resolution, i.e., at a scale comparable to that of a pixel for the Soil Moisture and Ocean Salinity (SMOS) satellite mission. The soil moisture distribution is influenced mainly by climatic variations, notably by the North American monsoon, which resulted in a systematic change in the regional variance as a function of the mean soil moisture.
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Montzka, Carsten, Heye Bogena, Marek Zreda, Alessandra Monerris, Ross Morrison, Sekhar Muddu, and Harry Vereecken. "Validation of Spaceborne and Modelled Surface Soil Moisture Products with Cosmic-Ray Neutron Probes." MDPI AG, 2017. http://hdl.handle.net/10150/623251.
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]The scale difference between point in situ soil moisture measurements and low resolution satellite products limits the quality of any validation efforts in heterogeneous regions. Cosmic Ray Neutron Probes (CRNP) could be an option to fill the scale gap between both systems, as they provide area-average soil moisture within a 150-250 m radius footprint. In this study, we evaluate differences and similarities between CRNP observations, and surface soil moisture products from the Advanced Microwave Scanning Radiometer 2 (AMSR2), the METOP-A/B Advanced Scatterometer (ASCAT), the Soil Moisture Active and Passive (SMAP), the Soil Moisture and Ocean Salinity (SMOS), as well as simulations from the Global Land Data Assimilation System Version 2 (GLDAS2). Six CRNPs located on five continents have been selected as test sites: the Rur catchment in Germany, the COSMOS sites in Arizona and California (USA), and Kenya, one CosmOz site in New SouthWales (Australia), and a site in Karnataka (India). Standard validation scores as well as the Triple Collocation (TC) method identified SMAP to provide a high accuracy soil moisture product with low noise or uncertainties as compared to CRNPs. The potential of CRNPs for satellite soil moisture validation has been proven; however, biomass correction methods should be implemented to improve its application in regions with large vegetation dynamics.
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Federici, Simone. "Gamma-ray studies of the young shell-type SNR RX J1713.7-3946." Phd thesis, Universität Potsdam, 2014. http://opus.kobv.de/ubp/volltexte/2014/7173/.
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One of the most significant current discussions in Astrophysics relates to the origin of high-energy cosmic rays. According to our current knowledge, the abundance distribution of the elements in cosmic rays at their point of origin indicates, within plausible error limits, that they were initially formed by nuclear processes in the interiors of stars. It is also believed that their energy distribution up to 1018 eV has Galactic origins. But even though the knowledge about potential sources of cosmic rays is quite poor above „ 1015 eV, that is the “knee” of the cosmic-ray spectrum, up to the knee there seems to be a wide consensus that supernova remnants are the most likely candidates. Evidence of this comes from observations of non-thermal X-ray radiation, requiring synchrotron electrons with energies up to 1014 eV, exactly in the remnant of supernovae. To date, however, there is not conclusive evidence that they produce nuclei, the dominant component of cosmic rays, in addition to electrons.
In light of this dearth of evidence, γ-ray observations from supernova remnants can offer the most promising direct way to confirm whether or not these astrophysical objects are indeed the main source of cosmic-ray nuclei below the knee. Recent observations with space- and ground-based observatories have established shell-type supernova remnants as GeV-to- TeV γ-ray sources. The interpretation of these observations is however complicated by the different radiation processes, leptonic and hadronic, that can produce similar fluxes in this energy band rendering ambiguous the nature of the emission itself.
The aim of this work is to develop a deeper understanding of these radiation processes from a particular shell-type supernova remnant, namely RX J1713.7–3946, using observations of the LAT instrument onboard the Fermi Gamma-Ray Space Telescope. Furthermore, to obtain accurate spectra and morphology maps of the emission associated with this supernova remnant, an improved model of the diffuse Galactic γ-ray emission background is developed. The analyses of RX J1713.7–3946 carried out with this improved background show that the hard Fermi-LAT spectrum cannot be ascribed to the hadronic emission, leading thus to the conclusion that the leptonic scenario is instead the most natural picture for the high-energy γ-ray emission of RX J1713.7–3946. The leptonic scenario however does not rule out the possibility that cosmic-ray nuclei are accelerated in this supernova remnant, but it suggests that the ambient density may not be high enough to produce a significant hadronic γ-ray emission.
Further investigations involving other supernova remnants using the improved back- ground developed in this work could allow compelling population studies, and hence prove or disprove the origin of Galactic cosmic-ray nuclei in these astrophysical objects. A break- through regarding the identification of the radiation mechanisms could be lastly achieved with a new generation of instruments such as CTA.Eine der gegenwärtigen bedeutendsten geführten Diskussionen in der Astrophysik bezieht sich auf den Ursprung der hochenergetischen Kosmischen Strahlung. Nach unserem heutigen Verständnis weist die am Ort des Ursprungs elementare Zusam- mensetzung der Kosmischen Strahlung darauf hin, dass diese zu Beginn mittels nuklearer Prozesse im Inneren von Sternen gebildet wurde. Weiterhin wird ange- nommen, dass die Kosmische Strahlung bis 1018 eV galaktischen Ursprungs ist. Auch wenn das Verständnis über die potentiellen Quellen der Kosmischen Strahlung ober- halb von 1015 eV, dem sogenannten „Knie“ des Spektrums der Kosmischen Strah- lung, lückenhaft ist, so liegt doch der Konsens vor, dass Supernovaüberreste (SNR) die wahrscheinlichsten Quellen für Energien bis 1015 eV sind. Unterstützt wird die- ser Sachverhalt durch Beobachtungen von nichtthermischer Röntgenstrahlung von SNR, deren Emission Elektronen mit Energien bis zu 1014 eV erfordern. Jedoch gibt es bis heute keinen überzeugenden Beweis, dass SNR zusätzlich zu den Elektronen auch Atomkerne, die den dominierenden Anteil in der Kosmischen Strahlung bilden, beschleunigen. Trotz fehlender überzeugender Beweise ermöglichen nun Beobachtungen von SNR im γ-Strahlungsbereich einen vielversprechenden Weg zur Aufklärung der Fra- ge, ob diese astrophysikalischen Objekte in der Tat die Hauptquelle der Kosmischen Strahlung unterhalb des Knies sind. Kürzlich durchgeführte Beobachtungen im Welt- raum und auf der Erdoberfläche haben zu der Erkenntnis geführt, dass schalenartige SNR γ-Strahlung im GeV- und TeV-Bereich emittieren. Die Interpretation dieser Beobachtungen ist jedoch schwierig, da sowohl Atomkerne als auch Elektronen im betrachteten Energiebereich zu ähnlichen γ-Emissionen führen. Dadurch wird die eindeutige Identifizierung der Emission als das Resultat hadronischer oder leptoni- scher Emissionsprozesse erschwert. Das Ziel dieser Arbeit ist es, am Beispiel des schalenartigen SNR RX J1713.7- 3946 ein tieferes Verständnis über die Strahlungsprozesse zu erhalten, indem vom γ-Weltraumteleskop Fermi durchgeführte Beobachtungen analysiert werden. Um ge- naue Spektren und die Ausdehnung der Region der Emission zu erhalten, wird ein verbessertes Modell für die diffuse galaktische γ-Hintergrundstrahlung entwickelt. Die mit diesem verbesserten Hintergrund durchgeführte Analyse von RX J1713.7- 3946 zeigt, dass das vom Fermi-Satelliten beobachtete Spektrum nicht dem hadro- nischen Szenario zugeschrieben werden kann, sodass das leptonische Szenario für die γ-Emissionen von diesem SNR verantwortlich ist. Das leptonische Szenario schließt jedoch nicht die Möglichkeit aus, dass auch Atomkerne in diesem SNR beschleu- nigt werden. Aber es deutet darauf hin, dass die umgebende Teilchendichte nicht ausreichend hoch genug ist, um zu einer signifikanten hadronischen γ-Emission zu führen. Weitere Untersuchungen, die andere SNR in Kombination mit dem hier ent- wickelten verbesserten Modell der Hintergrundstrahlung beinhalten, können Popu- lationsstudien erlauben. Dies könnte klären, ob die SNR tatsächlich die Quellen der galaktischen Kosmischen Strahlung sind. Ein Durchbruch bezüglich der Identi- fikation des Strahlungsmechanismus könnte auch durch eine neue Generation von Beobachtungsinstrumenten, wie das Cherenkov Telescope Array, erreicht werden.
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Jubelgas, Martin. "Cosmological Hydrodynamics: Thermal Conduction and Cosmic Rays." Diss., [S.l.] : [s.n.], 2007. http://edoc.ub.uni-muenchen.de/archive/00006928.
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Bisschoff, Driaan. "Galactic propagation of cosmic rays / Driaan Bisschoff." Thesis, North-West University, 2011. http://hdl.handle.net/10394/9164.
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The widely used steady-state, rotational symmetric models (2D models) of cosmic ray (CR)
propagation, assume smeared-out sources, which do not necessarily result in the same local CR
ux as the real local point sources. This suggests that the 2D models may not be adequate to
describe the CR primary component originating from point-like CR sources. By means of 3D
time-dependent calculations, it has been shown that the secondary CR component is not a ected
by local point-like sources. When working with 2D models, concentrating on secondary, tertiary
and higher CR nuclei may thus yield a better description of galactic CR propagation, as the
ux
of these nuclei does not depend on the local source history. Taking advantage of this fact and
looking at CR primaries and secondaries separately, evidence of nearby CR point sources might
be found with a 2D code. Conducting a parameter study, this should be seen in the di erent best
t values for CR primaries and secondaries. The 2D version of the GALPROP code was adapted
to a compute-cluster environment using the MPI framework and used to perform parameter
studies comparing CR spectra with mainly primary and secondary CR data separately. The
force eld approximation was implemented to account for heliospheric modulation. At Earth
the approximation is valid, as only nuclei are studied and time-dependence is not considered,
thus the disadvantages of the force eld are largely avoided. Using the GALPROP code to model
CR propagation through the Galaxy, three of the parameters in the 2D plain di usion model
were varied in the parameter study: the source spectral index ( ), the spectral index of the
di usion coe cient ( ) and the magnitude of the di usion coe cient at particle rigidity 4GV
(K0). The LIS produced by the models were compared to experimental CR data by means of a
2 test. For each set of data from di erent experiments, the LIS was inferred using the force eld
approximation and the individual CR species were divided up into three groups according to the
fraction of secondary and primary nuclei in each. The parameter values for the best t models
were found to di er between these Primary, Mixed and Secondary CR component groups. The
secondary CRs were found to be more easily t to data than the Primary component or the
Mixed component group, implying that the 2D GALPROP model as used is indeed better suited
for CR secondaries than for primaries. The results, together with the manner in which the 2D
model handles CR sources, imply that there maybe local point sources of CRs that, so far, are
not being taken into account.
iThesis (MSc (Space Physics))--North-West University, Potchefstroom Campus, 2012.
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Healy, Matthew David. "Composition of the highest energy cosmic rays." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1414128651&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Krüger, Tjaart Petrus Jakobus. "The effect of a Fisk-Parker hybrid magnetic field on cosmic rays in the heliosphere / Tjaart P.J. Krüger." Thesis, North-West University, 2005. http://hdl.handle.net/10394/1205.
Full textAbstract:
The existence of a Fisk-type heliospheric magnetic field (HMF) is one of the most debated
questions in cosmic-ray modulation. Recently, Burger and Hitge [2004] developed a divergence-free
Fisk-Parker hybrid magnetic field model to demonstrate the behaviour of cosmic rays in
the heliosphere due to such a field. This approach has been refined and the properties of the
consequent field are investigated. It is found that randomly directed magnetic field diffusion
in and above the photosphere significantly influences the solar magnetic field both at the solar
poles and near the polar coronal hole boundary. The solar cycle dependence of this field is
investigated, a study which is of particular importance for studies of the long-term behaviour
of cosmic rays, such as those undertaken at the SANAE base in Antarctica. The amplitudes of
the 26-day recurrent cosmic-ray variations are modelled as function of both latitudinal gradient
and heliolatitude and are found to agree qualitatively and in some cases quantitatively with
the observational results reported by Zhang 119971 and Paizis et al. 119991. Although magnetic
field data do not clearly indicate the existence of the Fisk field [see, e.g., Fursyth et al., 20021,
this study supports the existence of a Fisk-type HMF.Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2006.
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Kirn, Malina Aurelia. "Search for Point-Like Sources of Cosmic Rays with Energies Above 10 (18.5) eV in the Hires-I Monocular Dataset." Thesis, Montana State University, 2005. http://etd.lib.montana.edu/etd/2005/kirn/KirnM0505.pdf.
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Seglar-Arroyo, Monica. "Studying the origin of cosmic-rays : Multi-messenger studies with very-high-energy gamma-ray instruments." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS260.
Full textAbstract:
Les phénomènes explosifs qui se produisent dans l'Univers à haute énergie sont capables d'accélérer les particules jusqu'aux énergies les plus élevées. Ces processus produisent des particules secondaires de nature différente, c'est-à-dire des photons et des neutrinos. Dans des cas particuliers, ces événements induisent des perturbations sur l'espace-temps, c'est-à-dire des ondes gravitationnelles détectables par des interféromètres sur Terre. La combinaison des informations complémentaires fournies par ces messagers cosmiques peuvent permettre de répondre à des questions ouvertes en astrophysique. Parmi les événements les plus violents qui produisent de tels signaux figurent la fusion des deux objets les plus denses, comme les étoiles à neutrons et les trous noirs ou l'activité accréatrice dans les galaxies sur un trou noir supermassif. Dans ce travail, nous nous concentrons sur les photons à très haute énergie que produisent ces événements extrêmes, et sur la connexion avec les autres contreparties, afin de fournir une image globale multi-messagers qui permet l'étude des mécanismes physiques en place. Les défis inhérents à l'astronomie multi-messager dans le domaine temporel, ce qui implique un effort mondial coordonné et simultané entre les installations et les disciplines astronomiques, sont discutés et abordés. Une nouvelle stratégie d'observation optimisée du suivi de l'eau souterraine pour les petits et moyens instruments de FoV comme le H.E.S.S. et le futur CTA, capable d'apporter une réponse rapide aux alertes, qui prend en compte les risques caractéristiques de l'événement GW et maximise les chances de détecter la contrepartie électromagnétique, sera présentée. Cette stratégie s'est avérée fructueuse lors d'observations de suivi avec les télescopes H.E.S.S., et en particulier dans le cas de la première detection de la fusion d'une binaire d'étoiles à neutrons, GW170817. Dans le cadre du réseau AMON, une analyse multi-messagers qui combine des événements d'ondes gravitationnelles avec des données HAWC a été développée dans le but d'identifier les coïncidences astrophysiques à partir d'événements indépendants. De plus, la découverte par H.E.S.S. en très hautes énergies du noyau galactique actif OT 081, lors d'un état de flux élevé en juillet 2016, sera présentéeThe explosive phenomena occurring in the high-energy Universe are able to accelerate particles up to the highest energies. These processes produce secondary particles of different nature, i.e. photons and neutrinos. In special cases, these events induce perturbations on the space-time, i.e. gravitational waves detectable by interferometers on Earth. The combination and the complementary information provided by these cosmic messengers may allow to answer open questions in astrophysics, as the origin of cosmic rays. Amongst the most violent events producing such signals are the merge of the two densest objects, as neutron stars and black holes or the accretion activity in galaxies onto a supermassive black hole. In this work, we focus on the very-high energy photons that these extreme events produce, and the connection with the other counterparts, in order to provide a broad multi-messenger picture which enables the study of the physical mechanisms in place. The challenges inherent to time-domain multi-messenger astronomy are discussed and tackled, which involves simultaneous coordinated worldwide effort across facilities and astronomical disciplines. A novel, optimized GW follow-up observation strategy for small/mid- FoV instruments as H.E.S.S. and the future CTA, able to perform a rapid response to alerts, which considers the characteristics of the GW event and maximizes the chances to detect the electromagnetic counterpart will be presented. This strategy was proven successful in follow-up observations with the H.E.S.S. telescopes and in particular in the case of the first ever detected binary neutron star merger, GW170817. In the context of the AMON network, a multi-messenger analysis that combines gravitational wave events with HAWC data, with the aim to identify astrophysical coincidences out of independent events, has been developed. In addition, the discovery by H.E.S.S. in very-high energies of the active galactic nucleus OT 081, during a flaring episode in July 2016, will be presented
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Rengifo, Gonzáles Javier. "Disentangling atmospheric cascades started by gamma rays from cosmic rays with CORSIKA." Master's thesis, Pontificia Universidad Católica del Perú, 2017. http://tesis.pucp.edu.pe/repositorio/handle/123456789/8716.
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En este trabajo buscamos un método para diferenciar entre lluvias de partículas producidas por rayos cósmicos y por rayos gamma a energías de TeV, utilizando simulaciones CORSIKA. Este método intenta resolver el problema que existe en la búsqueda de señales de rayos gamma medidos por diversos experimentos frente a un fondo de flujo dominante de hadrones. Los resultados de este trabajo pueden aplicarse al estudio de Explosiones de Rayos Gamma (GRBs). Los GRBs emiten fotones muy energéticos, que al interactuar con la atmósfera terrestre, producen una gran cascada electromagnética de partículas secundarias, las cuales son detectables.
El procedimiento sería simular eventos producidos por fotones, la señal, y protones, el fondo, que son las partículas más abundantes de los rayos cósmicos. Extraemos varios parámetros de los perfiles longitudinales de las lluvias de partículas, caracterizando las lluvias simuladas. Algunos de los parámetros de ajuste más importantes son el m_aximo de lluvia (Xmax), el ancho de la lluvia FWHM, el parámetro de asimetría, el número máximo de partículas Nmax y el comienzo de lluvia XStart. Existen diferentes experimentos utilizando tanques Cherenkov de agua y detectores de fluorescencia que pueden medir estos parámetros de las lluvias.
Hemos probado dos métodos. El primero se basa en cortes simples, mientras que el segundo se basa en un análisis multivariado utilizando el paquete TMVA, que mejora los cortes individuales. El primer método se aplicó a las energías simuladas separadas de 102, 103, 104 y 105 GeV para encontrar cortes adecuados.
Encontramos que Xmax, FWHM, Xstart y Nmax dependen de la energía.
Posteriormente aplicamos estos cortes dependientes de la energía y otros cortes
fijos a una muestra realista, que consiste en 104 eventos de señales (fotones) y 106 eventos de fondo (protones) que cubren un rango de energía de 102 a 105 GeV con diferentes espectros. Además, se introdujo un error en la energía simulada para simular la eficiencia de reconstrucción de energía de un detector. El resultado obtenido deja 54% eventos de señal y 12% eventos de fondo. Aplicando el análisis multivariado TMVA, encontramos que el método Boosted Decision Trees (BDT) era el mejor para distinguir la señal del fondo. El resultado para una eficiencia de señal similar fue 0:7% de eventos de fondo.
Por último, utilizando cortes más estrictos en la BDT para mejorar la significancia, el resultado fue 1 evento de fotón por cada 1000 eventos de protón. Dada la proporción de flujo inicial, significa una capacidad de rechazo de fondo de 103.
Por lo tanto, la viabilidad de la separación gamma/hadrón requiere una mejora adicional.In this work we search for a method to differentiate between particle showers produced by cosmic rays and by gamma rays at TeV energies, using CORSIKA simulations. This method tries to solve the dominant hadron flux background problem when looking for gamma-ray signals measured by different experiments. The results of this work can be applied to the study of Gamma-Ray Bursts (GRBs). GRBs emit very energetic photons, which after interacting in the Earth's atmosphere, produce a large detectable electromagnetic cascade of secondary particles. The procedure will be to simulate events produced by photons, the signal, and protons, the most abundant cosmic-ray background. We extract several parameters from fitting particle air-shower longitudinal profiles, characterizing the simulated showers. Some of the most important _t parameters are the shower maximum (Xmax), the width of the shower FWHM, the asymmetry parameter, the maximum number of particles Nmax and the shower start Xstart. There are different experiments using water Cherenkov tanks and fluorescence detectors which can measure these shower parameters. We tested two methods. The first relies on simple cuts, while the second is based on a multivariate analysis using the TMVA package, which improves individual cuts. The first method was applied to single simulated energies of 102, 103, 104 and 105 GeV to find adequate cuts. We found that Xmax, FWHM, Xstart and Nmax depend on the energy. Later we applied these energy-dependent cuts and other fixed cuts to a realistic sample, which consists of 104 signal events (photons) and 106 background events (protons) covering an energy range from 102 to 105 GeV with different spectra. Moreover, we introduced an energy smearing to simulate a detector energy reconstruction efficiency. The obtained result leaves 54% signal events and 12% background events. Applying the multivariate analysis TMVA, we found that the Boosted Decision Trees (BDT) method was the best for distinguishing signal from background. The result for a similar signal efficiency was 0:7% of background events. Finally using tighter cuts on the BDT to improve the significance results in 1 photon event for every 1000 protons. Given the initial ux proportion, it means a 103 background rejection capability. Thus the feasibility of gamma/hadron separation requires further improvement.
Trabajo de investigación
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Banday, Anthony John. "Fluctuations in the cosmic microwave background." Thesis, Durham University, 1991. http://etheses.dur.ac.uk/6284/.
Full textAbstract:
The search for fluctuations in the Cosmic Microwave Background (CMB) is one of the most important topics in modern cosmology, since their detection would reveal a great many details about the early universe and, in particular, the nature of the primordial density perturbations giving rise to the galaxies and clusters of galaxies seen in the universe today. However, the search for such anisotropies is not trivial- none have been detected as yet - largely as a consequence of the fact that all radiative astrophysical sources can give rise to anisotropic foregrounds which confuse the search for genuine cosmological signals. In this thesis, a detailed study is made of the contribution of such foregrounds to searches for CMB fluctuations. After Chapter 1 summarises the theoretical and observational status of the subject, Chapters 2, 3 and 4 consider the foreground resulting from the Galaxy. It is found that frequencies in excess of 20 GHz are required to reduce the Galactic Synchrotron Radiation to a level where genuine anisotropies might be detected (the synchrotron emission is almost certainly responsible for a previously claimed detection), and that dust emission, especially if very cold dust exists which is unseen and possibly untraced by the dust responsible for the emission seen in the IRAS 100µm passband, can seriously constrain high frequency searches. In Chapter 4 a model is derived for the overall Galactic foreground including a separation of the thermal and non-thermal radio emission in the Galactic plane. Comparison with observations at 10 and 15 GHz suggests that the model is ~ 10%- 20% accurate on average at these frequencies, and maps of the predicted emission at the COBE frequencies 31.5, 53, and 90 GHz are provided. .4. search is made for a frequency window and sky region which minimises the Galactic contribution to the fluctuation measurements: highly sensitive, high resolution searches should be designed with these values in mind. Chapter 5 investigates the anisotropies resulting from discrete extragalactic sources, in particular, the far-infrared emission from dust in spiral galaxies and the integrated radio emission due to radio galaxies, QSOs etc. A frequency window of ~ 30 - 100 GHz is found to minimise both Galactic and extragalactic foreground anisotropies. Chapter 6 considers several cosmological models which could generate the recently observed large-scale structure in the galaxy- distribution: these are constrained by CMB anisotropy limits. It is concluded that genuine cosmological variations in the CMB temperature are now close to detection if the observed galaxy- structures are real. Chapter 7 indicates some future projects which should help in the detection and interpretation of CMB fluctuations.
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Weinreuter, Matthias Albert Maria [Verfasser], and W. de [Akademischer Betreuer] Boer. "On the Correlation between Cosmic Ray Arrival Directions and the Sources of Galactic Cosmic Rays / Matthias Albert Maria Weinreuter ; Betreuer: W. de Boer." Karlsruhe : KIT-Bibliothek, 2017. http://d-nb.info/1139360345/34.
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Hakmana, Witharana Sampath S. "Development of Cosmic Ray Simulation Program -- Earth Cosmic Ray Shower (ECRS)." Digital Archive @ GSU, 2007. http://digitalarchive.gsu.edu/phy_astr_diss/12.
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ECRS is a program for the detailed simulation of extensive air shower initiated by high energy cosmic ray particles. In this dissertation work, a Geant4 based ECRS simulation was designed and developed to study secondary cosmic ray particle showers in the full range of Earth's atmosphere. A proper atmospheric air density and geomagnetic field are implemented in order to correctly simulate the charged particles interactions in the Earth's atmosphere. The initial simulation was done for the Atlanta (33.460 N , 84.250 W) region. Four different types of primary proton energies (109, 1010, 1011 and 1012 eV) were considered to determine the secondary particle distribution at the Earth's surface. The geomagnetic field and atmospheric air density have considerable effects on the muon particle distribution at the Earth's surface. The muon charge ratio at the Earth's surface was studied with ECRS simulation for two different geomagnetic locations: Atlanta, Georgia, USA and Lynn Lake, Manitoba, Canada. The simulation results are shown in excellent agreement with the data from NMSU-WIZARD/CAPRICE and BESS experiments at Lynn Lake. At low momentum, ground level muon charge ratios show latitude dependent geomagnetic effects for both Atlanta and Lynn Lake from the simulation. The simulated charge ratio is 1.20 ± 0.05 (without geomagnetic field), 1.12 ± 0.05 (with geomagnetic field) for Atlanta and 1.22 ± 0.04 (with geomagnetic field) for Lynn Lake. These types of studies are very important for analyzing secondary cosmic ray muon flux distribution at the Earth's surface and can be used to study the atmospheric neutrino oscillations.
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Hakmana, Witharana Sampath. "Development of cosmic ray simulation program Earth cosmic ray shower (ECRS) /." unrestricted, 2007. http://etd.gsu.edu/theses/available/etd-04232007-151331/.
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Thesis (Ph. D.)--Georgia State University, 2007.Title from file title page. Xiaochun He, committee chair; Brian Thoms, Unil Perera, William Nelson, Richard Miller, committee members. Electronic text (173 p. : ill. (some col.)) : digital, PDF file. Description based on contents viewed Mar. 28, 2008. Includes bibliographical references (p. 165-173).
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Allison, Patrick S. "Design, calibration, and early results of a surface array for detection of ultrahigh energy cosmic rays." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1179849363.
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Wong, Chi-ming. "The equilibrium spectrum of cosmic ray positrons /." [Hong Kong : University of Hong Kong], 1985. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1226135X.
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Norwell, George A. "X-ray scattering by cosmic dust grains." Thesis, Keele University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293990.
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Weyer, Ralf. "Acceleration and spatial diffusion of galactic cosmic rays." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=976039400.
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Büsching, Ingo. "On the time dependent propagation of cosmic rays." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971996164.
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Blanco-Pillado, José Juan. "Topological defects and ultra-high energy cosmic rays /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2001.
Find full textAbstract:
Thesis (Ph.D.)--Tufts University, 2001.Adviser: Alexander Vilenkin. Submitted to the Dept. of Physics. Includes bibliographical references (leaves 108-114). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Taylor, Andrew Martin. "The propagation of ultra high energy cosmic rays." Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:63572ebe-fb32-41b6-8b91-a7294db135a6.
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This thesis presents theoretical work on the propagation of ultra high energy cosmic rays, from their source to Earth. The different energy loss processes, resulting from cosmic ray interactions with the radiation fields, are addressed. The subsequent uncertainties in the energy loss rates and the effect produced on the arriving cosmic ray spectrum are highlighted. The question of the composition of ultra high energy cosmic rays remains unresolved, with the range of possibilities leading to quite different results in both the secondary fluxes of particles produced through cosmic ray energy loss interactions en route, and the arriving cosmic ray spectra at Earth. A large range of nuclear species are considered in this work, spanning the range of physically motivated nuclear types ejected from the cosmic ray source. The treatment of cosmic ray propagation is usually handled through Monte Carlo simulations due to the stochastic nature of some of the particle physics processes relevant. In this work, an analytic treatment for cosmic ray nuclei propagation is developed. The development of this method providing a deeper understanding of the main components relevant to cosmic ray nuclei propagation, and through its application, a clear insight into the contributing particle physics aspects of the Monte Carlo simulation. A flux of secondary neutrinos, produced as a consequence of cosmic ray energy loss through pion production during propagation, is also expected to be observed at Earth. This spectrum, however, is dependent on several loosely constrained factors such as the radiation field in the infrared region and cosmic ray composition. The range of possible neutrino fluxes obtainable with such uncertainties are discussed in this work. High energy cosmic ray interactions with the radiation fields present within the source may also occur, leading to cosmic ray energy loss before the cosmic ray has even managed to escape. The secondary spectra produced are investigated through the consideration of three candidate sources. A relationship between the degree of photo-disintegration in the source region and the neutrino flux produced through p γ interactions is found.
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Giesen, Gaelle. "Dark Matter Indirect Detection with charged cosmic rays." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112160/document.
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Les preuves pour l'existence de la matière noire (MN), sous forme d'une particule inconnue qui rempli les halos galactiques, sont issues d'observations astrophysiques et cosmologiques: son effet gravitationnel est visible dans les rotations des galaxies, des amas de galaxies et dans la formation des grandes structures de l'univers. Une manifestation non-gravitationnelle de sa présence n'a pas encore été découverte. L'une des techniques les plus prometteuse est la détection indirecte de la MN, consistant à identifier des excès dans les flux de rayons cosmiques pouvant provenir de l'annihilation ou la désintégration de la MN dans le halo de la Voie Lactée. Les efforts expérimentaux actuels se focalisent principalement sur une gamme d'énergie de l'ordre du GeV au TeV, où un signal de WIMP (Weakly Interacting Massive Particles) est attendu. L'analyse des mesures récentes et inédites des rayons cosmiques chargés (antiprotons, électrons et positrons) et leurs émissions secondaires et les améliorations des modèles astrophysiques sont présentées.Les données de PAMELA sur les antiprotons contraignent l'annihilation et la désintégration de la MN de manière similaire (et même légèrement meilleurs) que les contraintes les plus fortes venant des rayons gamma, même dans le cas où les énergies cinétiques inférieures à 10 GeV sont écartées. En choisissant des paramètres astrophysiques différents (modèles de propagation et profils de MN), les contraintes peuvent changer d'un à deux ordres de grandeur. Pour exploiter la totalité de la capacité des antiprotons à contraindre la MN, des effets précédemment négligés sont incorporés et se révèlent être importants dans l'analyse des données inédites de AMS-02 : ajouter les pertes d'énergie, la diffusion dans l'espace des moments et la modulation solaire peut modifier les contraintes, même à de hautes masses. Une mauvaise interprétation des données peut survenir si ces effets ne sont pas pris en compte. Avec les flux de protons et d'hélium exposé par AMS-02, le fond astrophysique et ces incertitudes du ratio antiprotons sur protons sont réévalués et comparés aux données inédites de AMS-02. Aucune indication pour un excès n'est trouvé. Une préférence pour un halo confinant plus large et une dépendance en énergie du coefficient de diffusion plus plate apparaissent. De nouvelles contraintes sur l'annihilation et la désintégration de la MN sont ainsi dérivés.Les émissions secondaires des électrons et des positrons peuvent aussi contraindre l'annihilation et la désintégration de la MN dans le halo galactique : le signal radio dû à la radiation synchrotron des électrons et positrons dans le champs magnétique galactique, les rayons gamma des processus de bremsstrahlung avec le gas galactique et de Compton Inverse avec le champs radiatif interstellaire sont considérés. Différentes configurations de champs magnétique galactique et de modèles de propagation et des cartes de gas et de champs radiatif interstellaire améliorés sont utilisées pour obtenir des outils permettant le calculs des émissions synchrotrons et bremsstrahlung venant de MN de type WIMP. Tous les résultats numériques sont incorporés dans la dernière version du Poor Particle Physicist Coookbook for DM Indirect Detection (PPPC4DMID).Une interprétation d'un possible excès dans les données de rayons gamma de Fermi-LAT au centre galactique comme étant dû à l'annihilation de MN en canaux hadronique et leptonique est analysée. Dans une approche de messagers multiples, le calcul des émissions secondaires est amélioré et se révèle être important pour la détermination du spectre pour le canal leptonique. Ensuite, les limites provenant des antiprotons sur l'annihilation en canal hadronique contraignent sévèrement l'interprétation de cet excès comme étant dû à la MN, dans le cas de paramètres de propagation et de modulation solaire standards. Avec un choix plus conservatif de ces paramètres elles s'assouplissent considérablementOverwhelming evidence for the existence of Dark Matter (DM), in the form of an unknownparticle filling the galactic halos, originates from many observations in astrophysics and cosmology: its gravitational effects are apparent on galactic rotations, in galaxy clusters and in shaping the large scale structure of the Universe. On the other hand, a non-gravitational manifestation of its presence is yet to be unveiled. One of the most promising techniques is the one of indirect detection, aimed at identifying excesses in cosmic ray fluxes which could possibly be produced by DM annihilations or decays in the Milky Way halo. The current experimental efforts mainly focus in the GeV to TeV energy range, which is also where signals from WIMPs (Weakly Interacting Massive Particles) are expected. Focussing on charged cosmic rays, in particular antiprotons, electrons and positrons, as well as their secondary emissions, an analysis of current and forseen cosmic ray measurements and improvements on astrophysical models are presented. Antiproton data from PAMELA imposes contraints on annihilating and decaying DM which are similar to (or even slightly stronger than) the most stringent bounds from gamma ray experiments, even when kinetic energies below 10 GeV are discarded. However, choosing different sets of astrophysical parameters, in the form of propagation models and halo profiles, allows the contraints to span over one or two orders of magnitude. In order to exploit fully the power of antiprotons to constrain or discover DM, effects which were previously perceived as subleading turn out to be relevant especially for the analysis of the newly released AMS-02 data. In fact, including energy losses, diffusive reaccelleration and solar modulation can somewhat modify the current bounds, even at large DM masses. A wrong interpretation of the data may arise if they are not taken into account. Finally, using the updated proton and helium fluxes just released by the AMS-02 experiment, the astrophysical antiproton to proton ratio and its uncertainties are reevaluated and compared to the preliminarly reported AMS-02 measurements. No unambiguous evidence for a significant excess with respect to expectations is found. Yet, some preference for thicker halos and a flatter energy dependence of the diffusion coefficient starts to emerge. New stringed constraints on DM annihilation and decay are derived. Secondary emissions from electrons and positrons can also be used to constrain DM annihilation or decay in the galactic halo. The radio signal due to synchrotron radiation of electrons and positrons on the galactic magnetic field, gamma rays from bremsstrahlung processes on the galactic gas densities and from Inverse Compton scattering processes on the interstellar radiation field are considered. With several magnetic field configurations, propagation scenarios and improved gas density maps and interstellar radiation field, state-of-art tools allowing the computaion of synchrotron and bremssttrahlung radiation for any WIMP DM model are provided. All numerical results for DM are incorporated in the release of the Poor Particle Physicist Coookbook for DM Indirect Detection (PPPC4DMID). Finally, the possible GeV gamma-ray excess identified in the Fermi-LAT data from the Galactic Center in terms of DM annihilation, either in hadronic or leptonic channels is studied. In order to test this tantalizing interprestation, a multi-messenger approach is used: first, the computation of secondary emisison from DM with respect to previous works confirms it to be relevant for determining the DM spectrum in leptonic channels. Second, limits from antiprotons severely constrain the DM interpretation of the excess in the hadronic channel, for standard assumptions on the Galactic propagation parameters and solar modulation. However, they considerably relax if more conservative choices are adopted
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James, Kory T. "High energry gamma-ray source search with SPASE-2." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 65 p, 2007. http://proquest.umi.com/pqdweb?did=1397914891&sid=16&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Giller, Graham L. "The construction and analysis of a whole-sky map using underground muons." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386589.
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Herbst, Klaudia [Verfasser]. "Interaction of Cosmic Rays with the Earth's Magnetosphere and Atmosphere - Modeling the Cosmic Ray Induced Ionization and the Production of Cosmogenic Radionuclides / Klaudia Herbst." Kiel : Universitätsbibliothek Kiel, 2013. http://d-nb.info/1029981833/34.
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Simpson, K. M. "Studies of cosmic ray composition using a hybrid fluorescence detector /." Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phs61261.pdf.
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Kwok, Talent. "A study of background radiation and cosmic muon detection at the Aberdeen Tunnel laboratory in Hong Kong." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38819971.
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KO, CHUNG-MING. "COSMIC-RAY MODIFIED STELLAR WINDS (ACCELERATION, MODULATION, DIFFUSION, TRANSONIC SOLUTION)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183980.
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A two fluid hydrodynamical model describing the modification of a stellar wind flow due to its interaction with galactic cosmic-rays is investigated. The two fluids consist of the thermal stellar wind gas and the galactic cosmic-rays. A polytropic one fluid model is used to describe the stellar wind gas, and the cosmic-rays modify the wind via their pressure gradient. The cosmic-rays are considered to be a hot low density gas of negligible mass flux, but with a significant pressure and energy flux compared to the thermal gas. The equations used are essentially those employed in two fluid hydrodynamical models of cosmic-ray shock acceleration by the first order Fermi mechanism, but suitably modified to apply in a spherical geometry and including the effects of gravity on the flow. The stellar wind consists of a transonic flow with a termination shock, and subsonic flow outside the shock. The model shows the deceleration of the wind upstream of the shock by the positive galactic cosmic-ray pressure gradient. The dissertation first discusses the fluid polytropic stellar winds and how to insert shocks in the flow. The hydrodynamical equations governing cosmic-ray modified winds are then introduced followed by a discussion of the physics of the interaction between the thermal stellar wind and the cosmic-rays. A description of the singularities of the equations is also presented. The system of equations is first solved by a finite difference method in the test particle approximation in which the cosmic-rays do not modify the flow, with appropriate boundary conditions applied at infinity, at the wind termination shock, and at the star. A perturbation scheme to determine the modification of the wind by the cosmic-rays is then developed. This scheme applies when the modification of the wind by the cosmic-rays is sufficiently small. Finally a numerical iteration is employed to exactly solve the equations. This latter method has the advantage that it can be applied when there is a considerable modification of the wind by the cosmic-rays.
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Kwok, Talent, and 郭天能. "A study of background radiation and cosmic muon detection at the Aberdeen Tunnel laboratory in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38819971.
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Hembrow, K. P. "Observations of the muon component of PeV EAS." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277628.
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Tummey, Steven Peter. "A search for diffuse and point source emission of UHE gamma rays using muon content selected EAS." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336196.
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Mullen, Steven. "Analysis of hypervelocity impacts on the thermal blankets of the ultra heavy cosmic ray experiment from the long duration exposure facility." Thesis, University of Kent, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267412.
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