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Studies on a Polarized Proton Target for Reactions with Radioactive Ion Beams University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 8-2009 Studies on a Polarized Proton Target for Reactions with Radioactive Ion Beams Juan Pablo Urrego-Blanco University of Tennessee - Knoxville Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Physics Commons Recommended Citation Urrego-Blanco, Juan Pablo, "Studies on a Polarized Proton Target for Reactions with Radioactive Ion Beams. " PhD diss., University of Tennessee, 2009. https://trace.tennessee.edu/utk_graddiss/70 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Juan Pablo Urrego-Blanco entitled "Studies on a Polarized Proton Target for Reactions with Radioactive Ion Beams." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Physics. Carroll R. Bingham, Major Professor We have read this dissertation and recommend its acceptance: Alfredo Galindo-Uribarri, Yuri Efremenko, Witold Nazarewicz, Lawrence W. Townsend Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) To the Graduate Council: I am submitting herewith a dissertation written by Juan Pablo Urrego-Blanco entitled “Studies on a Polarized Proton Target for Reactions with Radioactive Ion Beams.” I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, with a major in Physics. Carrol R. Bingham Major Professor We have read this dissertation and recommend its acceptance: Alfredo Galindo-Uribarri Yuri Efremenko Witold Nazarewicz Lawrence W. Townsend Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official student records) Studies on a Polarized Proton Target for Reactions with Radioactive Ion Beams A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Juan Pablo Urrego Blanco August 2009 A mis Padres, a Rolando y Diana, y a Pilar, por supuesto. ii Acknowledgements It is often said that it takes a village to raise a PhD. In my case, that is certainly true. The number of people involved in one way or another with this project is so large that I could not mention everybody here. It is an honor and a pleasure to express my deepest gratitude to all them. However, for the sake of brevity, I will mention here only the people who were involved in a very direct way. I am indebted to Dr. Alfredo Galindo-Uribarri for his close guidance and help throughout these years of graduate school. His passion for Physics and his commitment to the education and well being of his students are an inspiration. His teachings extend far beyond Nuclear Physics and will always accompany me. I am grateful to Professor Carrol Bingham for his continuous support and encouragement. I also acknowledge his help in the analysis of the cross section excitation functions measured at the Holifield Radioactive Ion Beam Facility (HRIBF) in Oak Ridge. I also want to thank the members of my PhD committee for their concern about the development of the project and the valuable comments to this dissertation. The success of this project largely rests upon the contributions and expertise from the Low Temperature Group from the Paul Scherrer Institute (PSI) led by Dr. Ben van den Brandt. Ben and his colleagues Patrick Hautle, and Ton Konter spent many hours training me in the subtleties of low temperature physics and dynamic nuclear polarization. The time spent at PSI with the Group at PSI will remain as one of the richest educational, professional, and personal experiences of my life. I am very thankful to Mr. Paul Schurter, Willi Arrigoni, and Michael Schmutz for their numerous technical contributions to this project, the good times spent in the workshop, and their patience for coping with my poor German. My respect and admiration goes to these gentlemen who demonstrate with their fine work that Swiss precision is no cliché. The in-beam tests of the polarized target were performed with the Phillips Cyclotron at PSI thanks to the willingness and diligent work of Dr. Pierre Schmelzbach and Peter Meyer. Many thanks for that. My sincere thanks to Dr. Elizabeth Padilla-Rodal, who played a critical role during the in-beam tests at PSI and HRIBF. She was always there when she was needed, either to discuss Physics, to help in all sort of technical matters, or simply to cheer me in the difficult moments. iii I am also indebted to Drs. Kamil Sedlak and Toni Shiroka, from the μSR group at PSI, for providing me with the basic GEANT4 routines to simulate the trajectories of charged particles in the magnetic field of the polarized target. The preparation and characterization of thin target foils was possible thanks to the help of Drs Jens Gobrecht, Harald Sehr, and Stela Canulescu from PSI, and Dr. Stefan Blunier from the Institute of Mechanical Systems in ETH-Zurich. Many thanks to Drs. Kurt Klausen, Peter Allenspach, and Michelle Kenzelmann from PSI and to Dr. James Beene, from HRIBF. The support they gave to this project through the leadership of their respective institutions was fundamental for the completion of this work. I am also very grateful to the operations and technical staff from PSI and HRIBF for their collaboration during beam time. It is a pleasure to acknowledge the support of the US Department of Energy through contracts at the University of Tennessee and ORNL, and PSI for the financial support of the research reported in this thesis. Of course, the completion of this project was only possible with a little help from my friends. And I was fortunate enough to get help from both sides of the Ocean. Very special thanks to Perla, Oscar, and Martin for the good times and the many memories we have in Knoxville. Thanks also to Eun Ju for her moral support during the final part of the dissertation. To Ruggero, Loic, Marian, and Nikolai, I can only say Yach’mat! Thanks to you, Switzerland felt like home. I also wish to thank to the friends and family who were cheering for me back at home. Pilar, thanks for helping me with the analysis of the thick target spectra. But of course, your help was much more significant than that. You were my greatest motivation for finishing this work. It was you who always showed me the North, even in the darkest moments. Thanks for being by my side albeit the distance and the long wait. The rest of my life is now yours. I also want to thank my siblings, Rolando and Diana, for thrusting me along the way. Thanks for the advices, the enthusiasm, and the examples you set. I am very proud of being your brother and I am certain that soon you will accomplish far greater things than I have. Finally, I thank the root of everything I have accomplished. Obtaining this degree is, above all, a triumph I owe to my parents. In adverse circumstances you made us believe in the power of education and science, in the value of hard work and honesty, and that if we try hard enough it is possible to reach our dreams. This one is to you, mom and dad. iv Abstract Over the last few years, much progress has been made towards the understanding of basic properties of nuclei with extreme neutron to proton ratios. However, the study of phenomena involving spin polarized nuclei near the drip lines remains practically unexplored. The importance of such studies lies in the fact that the most complete knowledge of the scattering matrix is obtained in reactions with polarized particles. The purpose of this dissertation was to explore the feasibility of using polarized probes in reactions with exotic nuclei. We identified areas where reactions between Radioactive Ion Beams (RIBs) and light polarized targets open a new window of opportunity to study the behavior of those nuclei. These include nuclear structure studies using elastic scattering, the investigation of isolated resonances in nuclei of interest for astrophysics, the study of weakly bound nuclei, one nucleon transfer reactions, and reaction mechanisms. Motivated by these potential applications, we developed a polarized proton target with unique capabilities to operate in reactions with heavy ions at low and intermediate energies. Protons in a plastic foil are polarized using the dynamic nuclear polarization method, which requires low temperature operation (~200 mK) and intense magnetic fields (2.5 T). The foils can be prepared using the spin coating technique, resulting in thicknesses between 100 μg/cm2 and 20 mg/cm2. We have demonstrated operation of the target in frozen spin mode (low magnetic field, e.g., 0.8 T), required for experiments at low energies. For experiments with fast beams the target can be operated in dynamic mode reaching polarizations of up to 30% (B=2.5 T, continuous microwave irradiation). The operational limits of the target have been explored at the Paul Scherrer Institute and at the Holifield Radioactive Ion Beam Facility using the thick target technique with 12C beams at 38 MeV and intensities up to 107 pps, corresponding to the most intense RIBs available.
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