[en] We have experimentally studied the first and the second moments of D, ⁶Li and ⁷Li (I>((1)/(2))) NMR lines in a granulated LiD-target material as a function of nuclear polarizations and the data has been compared with a theory elaborated by Abragam, Roinel and Bouffard for monocrystalline samples. The experiments were carried out in the large COMPASS twin-target at CERN. The static local magnetic field of the polarized nuclei was measured by frequency shift between the NMR-signals in the two oppositely polarized cells and lead to the first moment, whereas the investigation of the second moment was done through Gaussian approximation. The average field magnitude in granulated material was estimated 20% larger than the value given by the calculations for monocrystalline samples of cylindrical shape. The second moment shows a qualitative agreement with the theory but it is slightly larger at the negative than at the positive polarization. In a polarized mode, the moments depend on the saturated microwave field

[en] Due to the vanishing quadrupole interaction only a single narrow 2.8 kHz full-width half-maximum nuclear magnetic resonance (NMR) line is observed in the ⁶LiD target material for deuterium and ⁶Li with spin 1. The second and fourth moments are obtained from a Memory function fit to the measured NMR signal. The values are compared to the calculations from dipole interaction between nuclei. The NMR line shape during polarization up to +55% and -52% is discussed

[en] The spin structure of the nucleons has been investigated by studying spin dependent process of deep inelastic scattering of a polarized muon beam and a polarized nucleon target in the COMPASS experiment since 2001. In order to achieve high luminosities it is necessary to use a large solid polarized target. The target consists of two independent and oppositely longitudinal polarized cells. The cells are filled with irradiated ⁶LiD granulated material. One of the characteristics of the polarized target is the spin reversal by magnetic field rotation in order to cancel the systematic error. The polarized target apparatus consists of a large refrigerator providing a low temperature of below 100 mK and a high cooling power with 200-300 mK, a superconducting magnet producing 2.5 T with good field homogeneity, two high power of a few watts microwave systems producing 70 GHz for Dynamic Nuclear Polarization (DNP) and 10 NMR signals detection system for the polarization measurement. (author)

[en] The ⁶LiD was weighed after unloading of the target. With the help of the measured cold volumes of the target cells the packing factor of the target material in each cell could be determined. From the known isotopic content in the target material a table of elements was produced for each cell

[en] The dilution refrigerator used to cool the large COMPASS polarized target is monitored through a PC running LabVIEW^TM 6.1 under Windows 2000^TM. About 60 parameters of the target (temperatures, pressures, flow rates) are continuously plotted and checked. They are periodically recorded in an Oracle^TM database and in a data file. An alarm for every parameter can be individually activated and optionally connected to a GSM (Global System for Mobile Communication) delivery message system. A web server receives and publishes the online status of the target with online tables and graphics on a dedicated COMPASS polarized target information web site. A Siemens programmable logic controller (PLC) powered by an uninterruptable source keeps the cryogenic system safe and stable during the long beam periods by controlling valves and interlocks. This safety feature protects the dilution refrigerator against potential damages in case of power failure

[en] We suggest using the Lagrange polynomial interpolation to calculate the longitudinal polarization of the large COMPASS target with a length of 2x55 cm. The algorithm does not change the polarizations measured by the NMR sensors. In addition, it allows taking into account the influence of the microwave field on the nuclear polarization at the resonator boundaries. As a result, measurements of polarization at several points of a long target and knowledge of the cavity design allow one to obtain a more explicit analytical expression for the target polarization. The work is performed in the COMPASS collaboration at CERN. (paper)

[en] The dynamic nuclear polarization (DNP) of ⁶LiD requires 1 mW/g or more microwave power in the beginning of the process. With the material of 350 g, this gives more than 350 mW in total for the COMPASS polarized target. A temperature around 300 mK or below is needed for an efficient polarization. These low temperatures can only be achieved with a dilution refrigerator designed to operate with a ³He flow of 100 mmol/s. In order to keep the polarization in the frozen mode, temperatures of about 65 mK are used with typical magnetic relaxation times of more than 1400 h at 0.42 T and of more than 15 000 h at 2.5 T. Low lattice temperature is important in achieving high nuclear polarization. The base temperature is limited by the heat brought to the mixing chamber by the inlet ³He and by radiation and conduction of heat

[en] A polarized deuterium target was developed for the use of the first measurement of the so-called complete spin dependent cross-sections of the D→(d→,p)T nuclear reaction at 20 MeV. In order to minimize the energy losses of incident and emitted particles in the target materials, the target thickness should be as thin as possible. A deuterated polyethylene foil of 30-50 μm thickness was used as polarized target. The deuterons contained in the foil are polarized by the dynamic nuclear polarization method in the magnetic field of 2.5 T. The polarized deuterium target system has been installed in the 1st experimental hall of the Tandem Accelerator Center at the University of Tsukuba. From the target asymmetry measurement of D→(d,d)D elastic scattering by a 20 MeV deuteron beam about 10% deuteron target polarization was confirmed

[en] A polarized deuterium target system was developed in order to measure the so-called complete spin dependent cross sections of the D-vector(d-vector, p)T nuclear fusion reaction at 20 MeV. By considering the nuclear fusion experiment in the low energy region, the deuterated polyethylene foils of 30-50 μm thickness were employed as a target material. The polarized deuterium target system consists of mainly a ³He-⁴He dilution cryostat, a 2.5 T superconducting magnet, a 70 GHz μ-wave system to enhance the polarization of deuteron using the dynamical nuclear polarization method and a NMR monitor system of the target polarization. The polarized target system was installed in the 1st experimental hall of University of Tsukuba Tandem Accelerator Center (UTTAC), About 10% polarization for deuteron in polyethylene was confirmed by the NMR measurement and the target asymmetry measurement of the D-vector(d, d)D elastic scattering by 20 MeV deuteron beam. (author)

[en] Continuous wave nuclear magnetic resonance (NMR) is used to determine the target polarization in the COMPASS experiment. The system is made of the so-called Liverpool Q-meters, Yale-cards, and VME modules for data taking and system controlling. In 2001 the NMR coils were embedded in the target material, while in 2002 and 2003 the coils were mounted on the outer surface of the target cells to increase the packing factor of the material. Though the error of the measurement became larger with the outer coils than with the inner coils, we have performed stable measurements throughout the COMPASS run time for 3 years. The maximum polarization was +57% and -53% as the average in the target cells