The baryogenesis is one of the greatest unanswered questions in contemporary physics. According to Sakarov’s conditions for baryogenesis, a process must have occurred early in universe’s life, that violated the fundamental CP-symmetry and led to the dominance of matter over antimatter in our universe. However all descriptions provided by the Standard Model in terms of CP-violating processes are insufficient by several order of magnitude to explain the observed abundance of matter. There must be some larger CP violation source, the observation of which could lead to the explanation of the matter-antimatter asymmetry and to new physics beyond the SM. A strong source of CP violation could manifest in the existence of an Electric Dipole Moment (EDM) of elementary particles. For neutral particles EDMs investigations started about 60 years ago, the approach was based on the use of magnetic traps, so far all results of EDM measurements are compatible with a vanishing EDM value. EDM searches on charged particles like protons and deuterons cannot be based on the same approach as for neutral particles, since the application of electric fields would result in an acceleration of the particle; therefore the use of storage rings in experiments aiming to directly measure a non-vanishing EDM on charged particles has been suggested by scientific collaborations all around the world. The ideal scenario would be an EDM-search dedicated electric storage ring to be developed on purpose to perform an EDM measurement on proton. As a first step towards a dedicated storage ring, feasibility studies on deuteron beams are performed by the JEDI (Jülich Electric Dipole Investigations) collaboration at the magnetic storage ring COSY (Cooler Synchrotron) at Forschungszentrum Jülich in Germany. The idea is based on the manipulation of the spin of the particles in the ring by use of a particular kind of radio frequency Wien Filter which acts on particles EDM leaving their orbit unperturbed, in such 6 a way to obtain a beam vertical polarization build-up which is proportional to the EDM value. The polarization-induced asymmetry in beam particles elastically scattered off a target, proportional to beam polarization, is then measured via a polarimeter and it is possible to obtain a value for the EDM. The cycles of tests that led to the development of the prototype of such a high precision polarimetry detector, made of a number of LYSO scintillator crystal modules and with a readout system based only on Silicon Photomultipliers (SiPMs), is the topic of the present thesis. In chapter I the theoretical background is presented. Chapter II is dedicated to a detailed description of the main principles in the use of storage rings for EDM searches in charged particles. Chapter III is a description of the COSY facility at FZ-Jülich and in chapter IV all the results from the tests performed in the development of the LYSO polarimeter are presented in detail.
The baryogenesis is one of the greatest unanswered questions in contemporary physics. According to Sakarov’s conditions for baryogenesis, a process must have occurred early in universe’s life, that violated the fundamental CP-symmetry and led to the dominance of matter over antimatter in our universe. However all descriptions provided by the Standard Model in terms of CP-violating processes are insufficient by several order of magnitude to explain the observed abundance of matter. There must be some larger CP violation source, the observation of which could lead to the explanation of the matter-antimatter asymmetry and to new physics beyond the SM. A strong source of CP violation could manifest in the existence of an Electric Dipole Moment (EDM) of elementary particles. For neutral particles EDMs investigations started about 60 years ago, the approach was based on the use of magnetic traps, so far all results of EDM measurements are compatible with a vanishing EDM value. EDM searches on charged particles like protons and deuterons cannot be based on the same approach as for neutral particles, since the application of electric fields would result in an acceleration of the particle; therefore the use of storage rings in experiments aiming to directly measure a non-vanishing EDM on charged particles has been suggested by scientific collaborations all around the world. The ideal scenario would be an EDM-search dedicated electric storage ring to be developed on purpose to perform an EDM measurement on proton. As a first step towards a dedicated storage ring, feasibility studies on deuteron beams are performed by the JEDI (Jülich Electric Dipole Investigations) collaboration at the magnetic storage ring COSY (Cooler Synchrotron) at Forschungszentrum Jülich in Germany. The idea is based on the manipulation of the spin of the particles in the ring by use of a particular kind of radio frequency Wien Filter which acts on particles EDM leaving their orbit unperturbed, in such 6 a way to obtain a beam vertical polarization build-up which is proportional to the EDM value. The polarization-induced asymmetry in beam particles elastically scattered off a target, proportional to beam polarization, is then measured via a polarimeter and it is possible to obtain a value for the EDM. The cycles of tests that led to the development of the prototype of such a high precision polarimetry detector, made of a number of LYSO scintillator crystal modules and with a readout system based only on Silicon Photomultipliers (SiPMs), is the topic of the present thesis. In chapter I the theoretical background is presented. Chapter II is dedicated to a detailed description of the main principles in the use of storage rings for EDM searches in charged particles. Chapter III is a description of the COSY facility at FZ-Jülich and in chapter IV all the results from the tests performed in the development of the LYSO polarimeter are presented in detail.
Development of a High Precision LYSO Polarimeter forEDM Search at COSY Storage Ring
BASILE, Simone
2019
Abstract
The baryogenesis is one of the greatest unanswered questions in contemporary physics. According to Sakarov’s conditions for baryogenesis, a process must have occurred early in universe’s life, that violated the fundamental CP-symmetry and led to the dominance of matter over antimatter in our universe. However all descriptions provided by the Standard Model in terms of CP-violating processes are insufficient by several order of magnitude to explain the observed abundance of matter. There must be some larger CP violation source, the observation of which could lead to the explanation of the matter-antimatter asymmetry and to new physics beyond the SM. A strong source of CP violation could manifest in the existence of an Electric Dipole Moment (EDM) of elementary particles. For neutral particles EDMs investigations started about 60 years ago, the approach was based on the use of magnetic traps, so far all results of EDM measurements are compatible with a vanishing EDM value. EDM searches on charged particles like protons and deuterons cannot be based on the same approach as for neutral particles, since the application of electric fields would result in an acceleration of the particle; therefore the use of storage rings in experiments aiming to directly measure a non-vanishing EDM on charged particles has been suggested by scientific collaborations all around the world. The ideal scenario would be an EDM-search dedicated electric storage ring to be developed on purpose to perform an EDM measurement on proton. As a first step towards a dedicated storage ring, feasibility studies on deuteron beams are performed by the JEDI (Jülich Electric Dipole Investigations) collaboration at the magnetic storage ring COSY (Cooler Synchrotron) at Forschungszentrum Jülich in Germany. The idea is based on the manipulation of the spin of the particles in the ring by use of a particular kind of radio frequency Wien Filter which acts on particles EDM leaving their orbit unperturbed, in such 6 a way to obtain a beam vertical polarization build-up which is proportional to the EDM value. The polarization-induced asymmetry in beam particles elastically scattered off a target, proportional to beam polarization, is then measured via a polarimeter and it is possible to obtain a value for the EDM. The cycles of tests that led to the development of the prototype of such a high precision polarimetry detector, made of a number of LYSO scintillator crystal modules and with a readout system based only on Silicon Photomultipliers (SiPMs), is the topic of the present thesis. In chapter I the theoretical background is presented. Chapter II is dedicated to a detailed description of the main principles in the use of storage rings for EDM searches in charged particles. Chapter III is a description of the COSY facility at FZ-Jülich and in chapter IV all the results from the tests performed in the development of the LYSO polarimeter are presented in detail.| File | Dimensione | Formato | |
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