The CAST experiment at CERN

Κώστογλου, Σοφία; Kostoglou, Sofia

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