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The CAST experiment at CERN

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dc.contributor.author Κώστογλου, Σοφία el
dc.contributor.author Kostoglou, Sofia en
dc.date.accessioned 2016-07-08T11:39:45Z
dc.date.available 2016-07-08T11:39:45Z
dc.date.issued 2016-07-08
dc.identifier.uri https://dspace.lib.ntua.gr/xmlui/handle/123456789/43044
dc.identifier.uri http://dx.doi.org/10.26240/heal.ntua.8038
dc.rights Default License
dc.subject Axions en
dc.subject Dark matter en
dc.subject Data acquisition en
dc.subject Silicon drift detector en
dc.subject Microwave cavities en
dc.subject Αξιόνια el
dc.subject Σκοτεινή ύλη el
dc.subject Συστήματα λήψης δεδομένων el
dc.subject Ανιχνευτής ολίσθησης πυριτίου el
dc.subject Μικροκυματικές κοιλότητες el
dc.title The CAST experiment at CERN en
heal.type bachelorThesis
heal.secondaryTitle Το πείραμα CAST στο CERN el
heal.generalDescription The present diploma thesis was carried out at CERN. en
heal.classification Αστροσωματιδιακή φυσική el
heal.language en
heal.access free
heal.recordProvider ntua el
heal.publicationDate 2016-06-24
heal.abstract The introduction of the theta angle as a solution to the U(1)A problem in the Lagrangian of QCD indicates a violation of Charge-Parity in strong interactions, which is not observed leading to the strong CP problem. From experimental results, the neutron electric dipole moment and thus the theta angle is orders of magnitude more strict that expected. A solution to this invokes a new global symmetry, the Peccei-Quinn symmetry. The spontaneous breaking of this symmetry at a specific energy scale predicts the existence of a light, neutral and weakly interacting Nambu-Goldstone boson, the axion. The characteristic of the axion, its mass and its coupling constant, are inversely proportional to the breaking fa of the energy scale. Axions are expected to be copiously produced in stellar cores, escape and carry away amounts of energy from the star. Therefore they constitute an energy dissipation mechanism which affects their evolution and sets bounds in the axion mass and coupling. Axions might be created in reactions taking place inside the sun. The average energy of the expected axion solar flux is calculated equal to 4.2 keV. Depending on their density and mass, they may constitute a candidate for the cold dark matter in the universe. CERN Axion Solar telescope (CAST) is an astroparticle experiment at CERN running since 2003 and its main purpose is the search for axions. The detection technique is based on the Primakoff effect. Inside a strong electric and magnetic field the coupling of two photons could lead to an axion production and vice versa the axion couples with a virtual photon producing a real detectable photon. The main component of CAST is a 10-meter LHC prototype magnet, with a twin aperture that reaches a magnetic field of 8.8 T. The magnet is placed on a moving platform and can be moved up to±8◦ vertically and±40◦ horizontally. The magnet can track the sun 90 minutes during sunrise and sunset. The remaining hours are dedicated to background measurements. In the first phase the experiment operated with vacuum inside the magnet bores, thus exploring the axion mass range up to 0.02 eV. In order to extend CAST sensitivity to higher axion masses, the magnet bores were filled with a buffer gas, at first with 4He and then with 3He. For the first time, the limit entered the QCD axion model band and the KSVZ line was crossed. In the third phase of the experiment 4He was used in order to revisit the results of phase two, with improved sensitivity and longer exposure time. During the fourth phase, CAST took data with vacuum in the magnet pipes using for the first time sub-keV detectors. CAST has made a first dedicated sub-keV search for solar chameleons based on the Primakoff effect.CAST has completed the search for solar axions. Searches are now focused on relic axions using the haloscope technique. Up to now haloscope searches have used solenoid magnets to provide the magnetic field with cylindrical cavities. In the case of CAST, rectangular cavities will be inserted inside the dipole magnet. The conversion probability is significantly enhanced if it occurs in a cavity resonant to the energy of the ALP. To cover a wide range of axion masses a tuning mechanism will be used for different frequencies. In the first chapter a brief introduction on axions and their properties is presented. A description of the various subsystems and the results of the experiment are included in chapter 2. Chapter 3 refers to the data acquisition system and the control systems in CAST. This chapter includes detailed description of the Slow Control, the Solar Tracking Software and the Horizontal laser check program. The properties of the Silicon Drift Detector, which was installed in the experiment in 2013 and it is currently used in the CAST laboratory, are presented in chapter 4. The final chapter contains a description of the microwave cavities that will be installed in the magnet in the upcoming months. en
heal.advisorName Γαζής, Ευάγγελος el
heal.advisorName Davenport, Martyn en
heal.committeeMemberName Γλύτσης, Ηλίας el
heal.committeeMemberName Ξανθάκης, Ιωάννης el
heal.committeeMemberName Γαζής, Ευάγγελος el
heal.academicPublisher Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Ηλεκτρολόγων Μηχανικών και Μηχανικών Υπολογιστών el
heal.academicPublisherID ntua
heal.numberOfPages 115 σ.
heal.fullTextAvailability true


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