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The IceCube is the world largest neutrino observatory located at the geographic South Pole. It consists of two components, the 1 km2 surface array IceTop, and 1 km3 InIce array. The main focus of the IceCube is neutrino astronomy and studying the physics of the neutrinos. IceCube also measures the direction, energy and mass composition of cosmic ray particles in the energy range between several hundred TeV (~1014 eV) and a few EeV (~1018 eV), the most enigmatic Galactic-to-extragalactic transition region. One unique advantage of the cosmic ray study with IceCube data comes from the fact that IceCube measures both the surface particles (with IceTop) and high energy muons (with the InIce array) in extensive air showers produced by cosmic rays. Previous cosmic ray studies are mainly done with the data from IceTop only, which are limited by the quality of cosmic ray reconstruction, and the number of high energy events. This work aims to improve the cosmic ray reconstructions in two ways. The first is to investigate and solve the angular resolution problem that occurred in the reconstruction of cosmic rays at high energies. The second is to develop a new cosmic ray reconstruction that uses data from both the IceTop and InIce arrays simultaneously. The first work significantly improves the direction reconstruction of cosmic rays. The second achieves, for the first time, a three-dimensional reconstruction of cosmic ray events in IceCube. It not only increases the number of events for physics study at high energies but also provides new parameters that may improve the accuracy of the measurement of cosmic ray primary energy and composition. The new reconstruction was also applied to data for a test analysis that uses machine learning techniques, which provides insights into future science analyses.
Since the discovery of cosmic rays over a century ago, evidence of their origins has remained elusive. Deflected by galactic magnetic fields, the only direct evidence of their origin and propagation remain encoded in their energy distribution and chemical composition. Current models of galactic cosmic rays predict variations of the energy distribution of individual elements in an energy region around 3 x 1015 eV known as the knee. This work presents a method to measure the energy distribution of individual elemental groups in the knee region and its application to a year of data from the IceCube detector. The method uses cosmic rays detected by both IceTop, the surface-array component, and the deep-ice component of IceCube during the 2009-2010 operation of the IC-59 detector. IceTop is used to measure the energy and the relative likelihood of the mass composition using the signal from the cosmic-ray induced extensive air shower reaching the surface. IceCube, 1.5 km below the surface, measures the energy of the high-energy bundle of muons created in the very first interactions after the cosmic ray enters the atmosphere. These event distributions are fit by a constrained model derived from detailed simulations of cosmic rays representing five chemical elements. The results of this analysis are evaluated in terms of the theoretical uncertainties in cosmic-ray interactions and seasonal variations in the atmosphere. The improvements in high-energy cosmic ray hadronic-interaction models informed by this analysis, combined with increased data from subsequent operation of the IceCube detector, could provide crucial limits on the origin of cosmic rays and their propagation through the galaxy. In the course of developing this method, a number of analysis and statistical techniques were developed to deal with the difficulties inherent in this type of measurement. These include a composition-sensitive air shower reconstruction technique, a method to model simulated event distributions with limited statistics, and a method to optimize and estimate the error on a regularized fit.
Anisotropy in the cosmic-ray arrival direction distribution has been well documented over a large energy range, but its origin remains largely a mystery. In the TeV to PeV energy range, the galactic magnetic field thoroughly scatters cosmic rays, but anisotropy at the part-per-mille level and smaller persists, potentially carrying information about nearby cosmic-ray accelerators and the galactic magnetic field. The IceCube Neutrino Observatory was the first detector to observe anisotropy at these energies in the Southern sky. This work uses 318 billion cosmic-ray induced muon events, collected between May 2009 and May 2015 from both the in-ice component of IceCube as well as the surface component, IceTop. The observed global anisotropy features large regions of relative excess and deficit, with amplitudes on the order of $10^{-3}$. While a decomposition of the arrival direction distribution into spherical harmonics shows that most of the power is contained in the low-multipole ($\ell \leq 4$) moments, higher-multipole components are found to be statistically significant down to an angular scale of less than $10^{\circ}$, approaching the angular resolution of the detector. Above 100\,TeV, a change in the topology of the arrival direction distribution is observed, and the anisotropy is characterized by a wide relative deficit whose amplitude increases with primary energy up to at least 5\,PeV, the highest energies currently accessible to IceCube with sufficient event statistics. No time dependence of the large- and small-scale structures is observed in the six-year period covered by this analysis within statistical and systematic uncertainties. Analysis of the energy spectrum and composition in the PeV energy range as a function of sky position is performed with IceTop data over a five-year period using a likelihood-based reconstruction. Both the energy spectrum and the composition distribution are found to be consistent with a single source population over declination bands. This work represents an early attempt at understanding the anisotropy through the study of the spectrum and composition. The high-statistics data set reveals more details on the properties of the anisotropy, potentially able to shed light on the various physical processes responsible for the complex angular structure and energy evolution.
The handbook centers on detection techniques in the field of particle physics, medical imaging and related subjects. It is structured into three parts. The first one is dealing with basic ideas of particle detectors, followed by applications of these devices in high energy physics and other fields. In the last part the large field of medical imaging using similar detection techniques is described. The different chapters of the book are written by world experts in their field. Clear instructions on the detection techniques and principles in terms of relevant operation parameters for scientists and graduate students are given.Detailed tables and diagrams will make this a very useful handbook for the application of these techniques in many different fields like physics, medicine, biology and other areas of natural science.
Since the discovery of cosmic rays over one hundred years ago, many experiments have studied their properties. However, a definitive answer to the questions of where cosmic rays originate and how they are produced is still not known. Over the last several decades, a much more detailed understanding of high energy cosmic rays has begun to materialize. In particular, the cosmic-ray energy spectrum, with its transitions at 3 PeV (the "knee") and 3 EeV (the "ankle"), has been extensively investigated. Based on magnetic confinement arguments, it's generally believed that the energy range between the knee and ankle is where the transition from Galactic to extragalactic sources of cosmic rays. The ability to distinguish between high energy cosmic rays of different composition and study the relative mass abundances of cosmic rays in this transition region can provide invaluable insight in answering the open questions surrounding the origins of cosmic rays. This work focuses on measuring the composition-resolved cosmic-ray energy spectrum at and above the all-particle knee using one year of data collected by the IceCube Observatory. Sepcifically, we focus on making a two mass group spectrum measurement from 10^6.4 GeV to 10^7.8 GeV. The first mass group, referred to as the "light" mass group, is modeled using proton and helium cosmic rays, while the second, "heavy" mass group, is modeled using oxygen and iron cosmic rays. We observe a clear softening of the light spectrum near 3 PeV, while the energy spectrum for the heavy mass group follows a power-law like structure with a spectral index of ~2.7 throughout the entire energy range considered. The observed transition from a primarily light to a heavy-dominant spectrum takes place near 10^7.1 GeV. This feature is characteristic of a potential rigidity-dependent cutoff, or Peters cycle. The change in relative mass abundance could also indicate a possible transition in the source population of cosmic rays. In addition, a study to determine whether or not the light, heavy, or all-particle cosmic-ray energy spectra vary as a function of arrival direction is also presented. This marks the first time an analysis of this kind has been conducted using the IceCube Observatory. No statistically significant spectrum deviations were observed. The results from this analysis can be used to set a limit on the range of possible spectral deviations.
Offers an accessible text and reference (a cosmic-ray manual) for graduate students entering the field and high-energy astrophysicists will find this an accessible cosmic-ray manual Easy to read for the general astronomer, the first part describes the standard model of cosmic rays based on our understanding of modern particle physics. Presents the acceleration scenario in some detail in supernovae explosions as well as in the passage of cosmic rays through the Galaxy. Compares experimental data in the atmosphere as well as underground are compared with theoretical models
The origin of cosmic rays has been an open problem for over a century. By measuring and modeling the energy spectrum and mass composition we can provide information towards solving this problem. The energy spectrum in particular has several features that hold key information to the propagation and sources of cosmic rays. The energy spectrum, which spans over several decades, can be described as a power-law with the slope defined by a value called the spectral index which ranges from values of 2.5 -- 3.3. Deviations of the spectral index mark key features of the energy spectrum such as the knee ($\approx$ $10^{15}$ eV), the second knee ($\approx$ $10^{17}$), the ankle ($\approx$ $10^{18.5}$) and a sharp drop off that occurs at the highest energies ($\approx$ $10^{19.5}$). We develop a hybrid model of a neural network to reconstruct the maximum atmospheric depth (Xmax) and a decision tree to reconstruct the energy for an extensive air shower that is detected by the IceCube Neutrino Observatory. The resolution of our models are about 41.6 $\rm{g/cm^2}$ for Xmax and 5.64\% for log10(E/GeV). Each of these is comparable with direct optical measurements of the shower. With these reconstructions we can construct kernels, using Monte Carlo simulations, that are capable of reproducing the probability density function of real data through a weighted sum of the kernels for a showers predicted Xmax binned by the showers predicted energy. We use weights (species fractions) predicted by models, such as H3A and H4A, and use the resulting fits to determine how well those models represent the propagation and production of cosmic rays. The H3A and H4A in particular use a physical phenomenon called a Peters cycle where rigidity is expected to be the governing variable for confinement and acceleration of cosmic rays.
Ground detector arrays have been used to measure high energy cosmic rays for decades to overcome their very low rate. IceCube is a special case with its 3D deployment and unique location--the South Pole. Although all 86 strings and 81 stations of IceCube were completed in 2011, IceCube began to take data in 2006, after the completion of the first 9 strings. In this thesis, experimental data taken in 2009 with 59 strings are used for composition analysis albeit some techniques are illustrated with the 40-string data. Simulation is essential in the composition work. Simulated data must be compared against the experimental data to find the right mix of cosmic ray components. However, because of limited computing resources and complexities of cosmic rays, the simulation in IceCube is well behind the experiment. The lower and upper bounds of primary energy in simulation for events that go through IceTop and the deep arrays of IceCube are 10 14 e V and 1017 e V. However, since IceCube has a threshold energy about several hundred TeV, and an upper limit of 10 18 e V, the full energy range cannot be explored in this thesis. The approach taken to the composition problem in this thesis is a 2D Bayesian unfolding. It takes account of the measured IceTop and InIce energy spectrum and outputs the expected primary energy spectrum of different mass components. Studies of the uncertainties in the results are not complete because of limited simulation and understanding of the new detector and South Pole environment.