Hadron structure is not fully understood yet. While the spin-averaged Parton Dis- tribution Functions (PDFs) and the helicity-dependent PDFs are well determined, little is known about the transverzity and some other transverse-momentum de- pendent PDFs (TMDs). The COMPASS experiment at CERN is preparing for studying the TMDs using a Drell-Yan process on transversely polarized target hit by pion beam in 2014-2015. An outline of the parton model of hadrons and of the TMDs is given. The COMPASS spectrometer is described, with emphasis on the modifications for the Drell-Yan program, and its capabilities to measure the TMDs is briefly discussed. A special attention is paid to the polarized target. The dilution refrigerator, the DNP system for polarizing the nuclei and the NMR for polarization measurement are described. The new monitoring system of the refrigerator is described, including the author's contribution to it. Issues of the new NMR coils design are discussed. 1

Title: Low temperature polarized target for spin structure studies of nucleons at COMPASS Author: Bc. Michael Pešek Department: Department of low temperature physics Supervisor of the master thesis: prof. Ing. Miroslav Finger, DrSc. Abstract: In presented thesis we describe concept of Deep Inelastic Scattering of leptons on nucleons in context of nucleon spin structure studies. Both polarized and unpolarized cases are discussed and concept of Transverse Momentum Dependent Parton Distribution Functions (TMD PDF) is introduced. The possibility of TMDs measurement using Semi-inclusive DIS (SIDIS) is described along with related results from COMPASS experiment. The future Drell-Yan programme at COMPASS is briefly mentioned and its importance is presented on the universality test i.e. change of sign of T-odd TMDs when measured in Drell-Yan and SIDIS. The importance of Polarized Target (PT) for spin structure studies is highlighted and principles of Dynamic Nuclear Polarization (DNP) are given using both Solid effect and spin temperature concept. COMPASS experiment is described in many details with accent given to PT. Finally the thermal equilibrium (TE) calibration procedure is described and carried out for 2010 and 2011 physics runs at COMPASS. The average polarization measurement results from 2010 and 2011 are...

L’étude de la structure du nucléon est un sujet actif de la recherche et un des objectifs majeurs du Thomas Jefferson National Accelerator Facility (Jefferson Lab). Dans cette optique et afin d’obtenir des résultats statistiquement significatifs, il est essentiel d’avoir une cible polarisée ayant à la fois une haute polarisation et une densité de matériel polarisé élevée. Cette thèse présente les principes et utilisations d’une cible de deutérure d’hydrogène (ou cible de HD) qui remplit les deux conditions précédemment énoncées. Bien qu’il ait été prouvé que la cible de HD pouvait être utilisée avec succès sous un faisceau de photons de haute intensité, il restait à montrer si elle pouvait résister un faisceau d’électrons de courant relativement élevé (nA). Dans ce but, la cible de HD a été testée pour la première fois dans son mode de “spin gelé” sous un faisceau d’électrons pendant l’expérience g14 dans le Hall B de Jefferson Lab en 2012. Deux méthodes de polarimétrie sont également décrites dans cette thèse : une par Resonance Magnétique Nucléaire appliquée à la cible de HD pendant les tests sous un faisceau d’électrons, et une autre utilisant la réaction de diffusion élastique d’un faisceau d’électrons sur une cible en utilisant des données élastiques sur l’hélium-3 prises en 2003 pendant l’expérience E97-110 dans le Hall A de Jefferson Lab. / The study of the nucleon structure has been a major research focus in fundamental physics in the past decades and still is the main research line of the Thomas Jefferson National Accelerator Facility (Jefferson Lab). For this purpose and to obtain statistically meaningful results, a highly efficient polarized target is essential. This means high polarization and high relative density of polarized material. This dissertation presents the principles and usage procedures of a Hydrogen Deuteride (HD) target that presents both such characteristics. Although the HD target has been shown to work successfully under a high intensity photon beam, it remained to be seen if the target could stand an electron beam of reasonably high current (nA). In this perspective, the HD target was tested for the first time in its “frozen spin” mode under an electron beam during the g14 experiment in the Jefferson Lab’s Hall B in 2012. Two methods of polarimetry are also discussed in this dissertation : one with Nuclear Magnetic Resonance of this HD target during the electron beam tests, and another with the elastic scattering of electrons off a polarized target by using data taken on helium-3 during the E97-110 experiment that occurred in Jefferson Lab’s Hall A in 2003.

The study of the nucleon structure has been a major research focus in fundamental physics in the past decades and still is the main research line of the Thomas Jefferson National Accelerator Facility (Jefferson Lab). For this purpose and to obtain statistically meaningful results, a highly efficient polarized target is essential. This means high polarization and high relative density of polarized material. This dissertation presents the principles and usage procedures of a Hydrogen Deuteride (HD) target that presents both such characteristics. Although the HD target has been shown to work successfully under a high intensity photon beam, it remained to be seen if the target could stand an electron beam of reasonably high current (nA). In this perspective, the HD target was tested for the first time in its "frozen spin" mode under an electron beam during the g14 experiment in the Jefferson Lab's Hall B in 2012. Two methods of polarimetry are also discussed in this dissertation : one with Nuclear Magnetic Resonance of this HD target during the electron beam tests, and another with the elastic scattering of electrons off a polarized target by using data taken on helium-3 during the E97-110 experiment that occurred in Jefferson Lab's Hall A in 2003.