Bonn 2010 – wissenschaftliches Programm
HK 33.9: Vortrag
Dienstag, 16. März 2010, 19:00–19:15, HG ÜR 8
High precision beam momentum determination in a synchrotron using a spin resonance method — •Paul Goslawski — Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany
Measurements on the mass of the η-meson performed at different experimental facilities over the last decade have resulted in very precise data which differ by up to 0.5 MeV/c2, i.e., more than eight standard deviations. In order to clarify this situation a new high precision measurement of the dp→3He η reaction was proposed at the COoler SYnchrotron - COSY - of the Forschungszentrum Jülich with the aim to achieve a mass resolution of Δ m < 50 keV/c2.
In order to measure the η meson mass with high accuracy through the dp→ 3He η reaction, the momentum of the circulating deuteron beam in COSY has to be determined with unprecedented precision. This has been achieved by studying the spin dynamics of the polarised deuteron beam. By depolarising the beam through the use of an artificially induced spin resonance, it was possible to determine the beam momentum p with a precision of Δ p/p < 10−4 for p≈ 3 GeV/c. The method for determination of the η mass as well as final results for the high precision beam momentum evaluation will be shown in this presentation.
In collaboration with the COSY accelerator team. Supported by the COSY-FFE program.