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A computerised 8-channel data acquisition unit constructed by the Durham University Microprocessor Unit is described and the calibration of this unit is given in chapter 2. A test for the data acquisition unit using a Geiger-Mul1er cosmic ray telescope is described in Chapter 3. In Chapter 4 the main experiment is described. Two plastic scintillation counters each of 0.4 area and 5cm thick in coincidence were used in this experiment to measure the density spectrum of electrons at sea level in the range 20 - 600 electrons per m(^2). The microcomputer data acquisition system is employed to record the scintillator pulse heights. The measured integral density spectrum has been used to calculate the integral size spectrum at sea level. A brief description of the theory of electron-photon cascades and the formation of extensive are showers is give in Chapter 5.A FORTRAN program which uses Monte Carlo method to simulate extensive air showers generated by high energy protons with a given energy is described in Chapter 6. Using the relation between primary energy and average number of electrons arriving at sea level found by Monte Carlo calculation in Chapter 6 an estimate has been made of the integral primary energy spectrum in the range lO(^14)-lQ(^16)eV, and the result is given in Chapter 7.

This thesis reports measurements made on the longitudinal cascade of high energy cosmic ray showers using observations of atmospheric Cerenkov light. The lateral distribution of the Cerenkov light shower has been shown to be one of the measurable ground parameters which is sensitive to cascade development. The interpretation of such measurements together with other depth sensitive parameters in recorded showers has allowed inferences to be made about the mass distribution of the primary particles and about the nature of the high energy interactions which govern the generation of the cascade through the atmosphere. Measurements of atmospheric Cerenkov light from showers between 10(^15) – 10(^18) eV were made at Dugway Proving Grounds, Utah, U.S.A. between October 1977 and March 1980, using an array of fast photo multipliers to record both the lateral distribution of light density and the time structure of the light pulses. This thesis concerns the detailed analysis and interpretation of the lateral distribution data. These results were subsequently combined with those from pulse timing measurements to present composite results on the gross feature of shower development, the depth of cascade maximum. Analysis techniques have been developed to determine both the average characteristics of the lateral distribution and the fluctuations in the data which could be attributed to intrinsic fluctuations in cascade development. The results of these analyses were then related, through the results of computer simulations of shower development, to the depth of cascade maximum. A change in the elongation rate and the magnitude of fluctuations between 10(^16) and 10(^17) eV has been observed and this is interpreted as a change in primary mass composition from predominantly heavy particles ~ 10(^16) eV to include a greater proportion of light nuclei ~ 2 x 10(^17) eV. The combined measurement of the mean and fluctuations in the depth of maximum has allowed certain interaction models to be rejected. These were those involving scaling in the central region or using an interaction cross section which remains constant with energy. Results from other observations of cosmic ray showers show further indication of the change in primary mass composition between ~ 10(^16) eV and ~ 2 x 10(^17) eV. At higher energies these other results indicate a mass composition changing little with energy.

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Leung Po Kin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 86-91). / Text in English; abstracts in English and Chinese. / Leung Po Kin. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- The expanding universe --- p.1 / Chapter 1.2 --- Brief Thermal History of The Universe --- p.5 / Chapter 1.3 --- Cosmic Microwave background --- p.7 / Chapter 1.3.1 --- CMB Anisotropy --- p.8 / Chapter 1.4 --- Structure Formation --- p.9 / Chapter 1.5 --- Current Observation --- p.9 / Chapter 2 --- Recombination --- p.11 / Chapter 2.1 --- Ionization Fraction --- p.12 / Chapter 2.1.1 --- Saha Equations --- p.12 / Chapter 2.1.2 --- Rate Equation --- p.13 / Chapter 2.2 --- Matter Temperature --- p.16 / Chapter 3 --- Review of Structure Formation Theory --- p.20 / Chapter 3.1 --- Basic Ideas --- p.21 / Chapter 3.1.1 --- Power Spectrum --- p.22 / Chapter 3.2 --- Equations that govern Structure Formation --- p.24 / Chapter 3.2.1 --- Newtonian theory --- p.24 / Chapter 3.2.2 --- Boltzmann equation --- p.25 / Chapter 4 --- Review of CMB Anisotropies Theory --- p.28 / Chapter 4.1 --- CMB Physics --- p.29 / Chapter 4.1.1 --- Tight Coupling Limit --- p.29 / Chapter 4.1.2 --- Diffusion Damping and Free Streaming --- p.30 / Chapter 4.2 --- Numerical Method --- p.31 / Chapter 4.2.1 --- Solving Systems of Boltzmann Equations --- p.31 / Chapter 4.2.2 --- Line of Sight Integration --- p.32 / Chapter 5 --- Effect of recombination --- p.35 / Chapter 5.1 --- Effect of Recombination --- p.35 / Chapter 5.1.1 --- Cosmic Reheating and Softening --- p.35 / Chapter 5.1.2 --- Release of Heat --- p.36 / Chapter 5.2 --- Effect on expansion of the universe --- p.36 / Chapter 5.3 --- Effect on ionization fraction --- p.38 / Chapter 5.4 --- Recombination softening --- p.38 / Chapter 5.4.1 --- Results --- p.40 / Chapter 5.4.2 --- Discussion and Summary --- p.44 / Chapter 6 --- Change of Fundamental Constants --- p.53 / Chapter 6.1 --- Change of fundamental constants --- p.54 / Chapter 6.1.1 --- Some conceptual problems --- p.55 / Chapter 6.1.2 --- Effect on CMB --- p.56 / Chapter 6.2 --- Friedmann equations --- p.57 / Chapter 6.3 --- Baryon temperature --- p.64 / Chapter 6.4 --- Ionization fraction --- p.66 / Chapter 6.4.1 --- Better treatment --- p.67 / Chapter 6.4.2 --- Numerical calculation --- p.70 / Chapter 6.5 --- Effect on different physics of formation of CMB --- p.77 / Chapter 6.5.1 --- Properties of photon-baryon fluid --- p.78 / Chapter 6.5.2 --- Diffusion damping --- p.80 / Chapter 6.6 --- Conclusion --- p.84 / Bibliography --- p.86 / Chapter A --- Boltzmann equations --- p.92 / Chapter B --- Comparison of the energy terms --- p.95 / Chapter C --- Discussion of the analytic method for CMB temperature spec- trum --- p.99

Tam, Yiu Ho = 宇宙射線渺子及其引致中子的研究 / 譚耀豪. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 148-153). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Tam, Yiu Ho = Yu zhou she xian miao zi ji qi yin zhi zhong zi de yan jiu / Tan Yaohao.

Ngan, Sze Yuen = 渺子及其於香港仔隧道實驗室內的綜合研究 / 顏思遠. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 84-85). / Abstracts in English and Chinese. / Ngan, Sze Yuen = Miao zi ji qi yu Xianggangzi sui dao shi yan shi nei de zong he yan jiu / Yan Siyuan. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Cosmic Rays --- p.1 / Chapter 1.2 --- Muons --- p.3 / Chapter 1.3 --- Neutrino Oscillation --- p.5 / Chapter 1.4 --- The Daya Bay Reactor Neutrino Experiment --- p.8 / Chapter 1.4.1 --- Overview --- p.8 / Chapter 1.4.2 --- Detection Mechanism --- p.9 / Chapter 1.5 --- The Aberdeen Tunnel Experiment --- p.11 / Chapter 1.5.1 --- Overview --- p.11 / Chapter 1.5.2 --- Muon Tracker --- p.13 / Chapter 1.5.3 --- Neutron Detector --- p.16 / Chapter 2 --- Underground Muons --- p.18 / Chapter 2.1 --- Muon Simulation in the Daya Bay Experiment --- p.18 / Chapter 2.1.1 --- Gaisser's Formula --- p.20 / Chapter 2.1.2 --- Digitization of the Geographical Profile --- p.23 / Chapter 2.1.3 --- Underground Muon Flux --- p.24 / Chapter 2.2 --- Muon Simulation in the Aberdeen Tunnel Experiment --- p.25 / Chapter 3 --- Muon Behaviors in the Aberdeen Tunnel Laboratory --- p.28 / Chapter 3.1 --- Preparation --- p.29 / Chapter 3.1.1 --- Definition of the Coordinate System --- p.29 / Chapter 3.1.2 --- Generation of Muon Events --- p.30 / Chapter 3.1.3 --- Muon Trajectory --- p.35 / Chapter 3.1.4 --- Muon Energy Dissipation --- p.36 / Chapter 3.2 --- Muon Detection by the ND --- p.38 / Chapter 3.2.1 --- Energy Deposition in Gd-LS --- p.38 / Chapter 3.2.2 --- Experimental Measurements and Comparison --- p.40 / Chapter 3.2.3 --- Energy Deposition in MO --- p.42 / Chapter 3.2.4 --- ND Muon Rate --- p.43 / Chapter 3.2.5 --- Stopping Muons and Muon Decay --- p.44 / Chapter 3.3 --- Muon Detection by the Muon Tracker --- p.46 / Chapter 3.3.1 --- Selection of Top-Bottom Muons --- p.47 / Chapter 3.3.2 --- Selection of Muons which cut the Gd-LS Volume Diagonally --- p.49 / Chapter 4 --- Optimization of the Photomultiplier Tubes --- p.52 / Chapter 4.1 --- Photomultiplier Tube --- p.52 / Chapter 4.2 --- The Earth Field Effect --- p.55 / Chapter 4.2.1 --- FINEMET Magnetic Shield on PMT --- p.56 / Chapter 4.2.2 --- Magnetic Fields Measurement near the PMT Mount --- p.63 / Chapter 4.3 --- p-sec Region Ringing in PMT Signal --- p.65 / Chapter 4.3.1 --- The PMT Body and Simulated PMT Signal --- p.67 / Chapter 4.3.2 --- The Dummy Base --- p.69 / Chapter 4.3.3 --- High Voltage and the PMT Base Design --- p.71 / Chapter 5 --- Summary --- p.81 / Chapter 5.1 --- Underground Muon simulation --- p.81 / Chapter 5.2 --- Optimization of the PMTs in the Daya Bay Experiment --- p.82 / Bibliography --- p.84

Wong, Koon Kei Jackie = 香港仔地底實驗室中的宇宙渺子研究 / 黃冠棋. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 74-76). / Abstracts in English and Chinese. / Wong, Koon Kei Jackie = Xianggangzi di di shi yan shi zhong de yu zhou miao zi yan jiu / Huang Guanqi. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.1.1 --- Neutrino Oscillation --- p.1 / Chapter 1.1.2 --- The Daya Bay Reactor Neutrino Experiment --- p.5 / Chapter 1.2 --- Cosmic muons --- p.8 / Chapter 1.2.1 --- Propagation of cosmic muons --- p.10 / Chapter 1.3 --- Aberdeen Tunnel Experiment --- p.11 / Chapter 1.3.1 --- Detection principles of Muon Tracker --- p.13 / Chapter 1.3.2 --- Detection principles of Neutron Detector --- p.16 / Chapter 1.3.3 --- The data acquisition (DAQ) and online monitoring system --- p.17 / Chapter 2 --- Study of Angular distribution of the Expected Muon Flux --- p.20 / Chapter 2.1 --- Determination of muon angular distribution detected by the muon tracker --- p.21 / Chapter 2.2 --- Spherical Harmonics Expansion of muon angular distribution --- p.29 / Chapter 3 --- Hardware Development of the Muon Tracker --- p.35 / Chapter 3.1 --- Front-end electronics board --- p.35 / Chapter 3.1.1 --- The circuit of front-end daughter board --- p.37 / Chapter 3.1.2 --- Test of the front-end daughter board --- p.39 / Chapter 3.2 --- Muon tracker PMT gain calibration --- p.45 / Chapter 4 --- Photomultiplier tubes (PMT) characterization --- p.48 / Chapter 4.1 --- Magnetic field test --- p.49 / Chapter 4.2 --- Nonlinearity test --- p.54 / Chapter 4.2.1 --- Two-LED system --- p.54 / Chapter 4.2.2 --- LED and reference PMT system --- p.56 / Chapter 4.3 --- Optimization of waveform --- p.59 / Chapter 4.4 --- Comparison with Hamamatsu's recommended PMT bases --- p.65 / Chapter 5 --- Summary --- p.71 / Chapter 5.1 --- Calculations about muon angular distribution --- p.71 / Chapter 5.2 --- Front-end electronics tests and PMT measurements --- p.71 / Chapter 5.3 --- Outlook for the Aberdeen Tunnel Experiment --- p.72 / Bibliography --- p.74

Luk, Wing Hong Antony = 地底實驗室的渺子致中子本底研究 / 陸永康. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 74-77). / Abstracts in English and Chinese. / Luk, Wing Hong Antony = Di di shi yan shi de miao zi zhi zhong zi ben di yan jiu / Lu Yongkang. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Muons at Earth´ةs Surface --- p.1 / Chapter 1.2 --- Underground Muons --- p.2 / Chapter 1.2.1 --- Muon Intensity --- p.2 / Chapter 1.2.2 --- Muon Energy --- p.6 / Chapter 1.3 --- Muon-induced Neutrons --- p.7 / Chapter 1.3.1 --- Production of Neutrons from Muons --- p.7 / Chapter 1.3.2 --- The Influence of Muon-induced Neutrons on Underground Experiments --- p.9 / Chapter 1.4 --- Aberdeen Tunnel Laboratory --- p.11 / Chapter 1.4.1 --- Geological Properties --- p.12 / Chapter 1.4.2 --- Detectors Description --- p.14 / Chapter 1.4.3 --- Detection Principles --- p.18 / Chapter 2 --- Simulation of Cosmic Muons for Aberdeen Tunnel Laboratory --- p.22 / Chapter 2.1 --- Muon Spectrum at Sea level --- p.22 / Chapter 2.2 --- Simulation of Muon Propagation through Rock --- p.23 / Chapter 2.3 --- Estimation of Expected Event Rate for the Muon Tracker --- p.28 / Chapter 3 --- Neutron Detector Simulation --- p.30 / Chapter 3.1 --- Simulation Parameters --- p.32 / Chapter 3.2 --- Energy Response --- p.35 / Chapter 3.3 --- Energy Resolution --- p.35 / Chapter 3.4 --- Neutron Drift Distance and Capture Efficiency --- p.40 / Chapter 3.5 --- Neutron Detection Efficiency --- p.42 / Chapter 3.6 --- Photons Arrival Time --- p.45 / Chapter 3.6.1 --- Cobalt-60 Source --- p.45 / Chapter 3.6.2 --- LED --- p.47 / Chapter 4 --- Simulation of Muon-induced Neutron Background --- p.49 / Chapter 4.1 --- Review on Muon-induced Neutron Simulations --- p.50 / Chapter 4.1.1 --- Methodology --- p.50 / Chapter 4.1.2 --- Results in the Literature --- p.52 / Chapter 4.1.3 --- Simulation of Muon-induced Neutrons in GdLS --- p.56 / Chapter 4.2 --- Full Monte Carlo Simulation of Expected Neutron Rate --- p.64 / Chapter 4.2.1 --- Simulation Details --- p.65 / Chapter 4.2.2 --- Results --- p.65 / Chapter 4.3 --- Estimation of the Expected Neutron Rate using Parameterization from Monte Carlo Simulations --- p.68 / Chapter 4.3.1 --- Simulation Details --- p.68 / Chapter 4.3.2 --- Results --- p.69 / Chapter 4.4 --- Summary --- p.71 / Chapter 5 --- Future Work --- p.72 / Chapter 5.1 --- Neutrons from Rock Radioactivity --- p.72 / Chapter 5.2 --- Muon-induced Neutrons from Rock --- p.73 / Chapter 5.3 --- Variation of Muon flux --- p.73 / Bibliography --- p.74