Showing papers by "W. Meyer published in 2011"
01 Mar 2011-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the authors studied the dynamic nuclear 13C polarization in solid pyruvic acid doped with the trityl radical AH 111 501 at different temperatures and magnetic fields and found that the highest polarization was 74.7% at a temperature of 900 mK in a magnetic field of 5 T.
Abstract: Dynamic nuclear polarization (DNP) has proved to be one of the most effective methods to increase the nuclear spin polarization in inorganic as well as organic materials since several decades. In combination with methods to rapidly dissolve the polarized solid sample it is possible to obtain a solution of molecules containing hyperpolarized nuclei. This has enabled new applications in Nuclear Magnetic Resonance (NMR) spectroscopy as well as medical applications in Magnetic Resonance Imaging (MRI). We studied the dynamic nuclear 13C polarization in solid [1-13C] pyruvic acid doped with the trityl radical AH 111 501 at different temperatures and magnetic fields. The measurements were performed in a 4He evaporation refrigerator operated inside a superconducting solenoid system. Working points at temperatures between 900 and 1350 mK have been adjusted and the polarization measurements have been performed at magnetic fields of 2.5, 3.5 and 5 T, respectively. This set of measurements allows to draw a clear picture of the temperature and magnetic field dependency of the 13C polarization within the given range. The highest polarization measured was 74.7% at a temperature of 900 mK in a magnetic field of 5 T.
38 citations
TL;DR: In this paper, the helicity dependence of the total cross-section for the gamma n-to-p pi(-)pi(0) reaction at incident photon energies from 450 to 800MeV was measured with the largeacceptance detector DAPHNE at the tagged photon beam facility of the MAMI accelerator.
Abstract: The helicity dependence of the total cross-section for the gamma n -> p pi(-)pi(0) reaction has been measured for the first time at incident photon energies from 450 to 800MeV. The measurement was performed with the large-acceptance detector DAPHNE at the tagged photon beam facility of the MAMI accelerator in Mainz. Both the measured unpolarized and the helicity-dependent observables are not well described by the existing theoretical models.
5 citations