SPIN Physics at GSI

Polarized antiprotons produced by spin filtering with an internal polarized gas target provide access to a wealth of single-- and double--spin observables, thereby opening a window to physics uniquely accessible with the HESR at FAIR. This includes a first measurement of the transversity distribution of the valence quarks in the proton, a test of the predicted opposite sign of the Sivers--function, related to the quark distribution inside a transversely polarized nucleon, in Drell--Yan (DY) as compared to semi--inclusive DIS, and a first measurement of the moduli and the relative phase of the time--like electric and magnetic form factors G_{E,M} of the proton. In polarized and unpolarized proton--antiproton elastic scattering open questions like the contribution from the odd charge--symmetry Landshoff--mechanism at large |t| and spin--effects in the extraction of the forward scattering amplitude at low |t| can be addressed.Comment: 10 pages, 3 figures. Contribution to the Proceedings of the 16th International Spin Physics Symposium, Spin 2004, October 10-16, 2004, Trieste, Italy. This replacement takes into account a request of the conference organizers that for invited talks only a single author is allowed. Also upon request of the conference organizers, a footnote (c) was added, which explains that some of the material presented was developed only after the oral presentation at the conferenc

Measurement of the Spin--Dependence of the pbar p Interaction at the AD-Ring

An internal polarized hydrogen storage cell gas target is proposed for the AD--ring to determine for the first time the two total spin--dependent cross sections $\sigma_1$ and $\sigma_2$ at antiproton beam energies in the range from 50 to 200 MeV. The data will allow the definition of the optimum working parameters of a dedicated Antiproton Polarizer Ring (APR), which has recently been proposed by the PAX collaboration for the new Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt, Germany. The availability of an intense beam of polarized antiprotons will provide access to a wealth of single-- and double--spin observables, thereby opening a new window to QCD transverse spin physics. The physics program proposed by the PAX collaboration includes a first measurement of the transversity distribution of the valence quarks in the proton, a test of the predicted opposite sign of the Sivers--function, related to the quark distribution inside a transversely polarized nucleon, in Drell--Yan (DY) as compared to semi--inclusive Deep Inelastic Scattering, and a first measurement of the moduli and the relative phase of the time--like electric and magnetic form factors $G_{E,M}$ of the proton

PERSPECTIVES FOR POLARIZED ANTIPROTONS

Polarized antiprotons would open a new window in hadron physics providing access to a wealth of single and double spin observables in proton-antiproton interactions. The PAX Collaboration aims to perform the first ever measurement of the spin-dependence of the proton-antiproton cross section at the AD ring at CERN. The spin-dependence of the cross section could in principle be exploited by the spin-filtering technique for the production of a polarized antiproton beam. As a preparatory phase to the experimentation at AD, the PAX Collaboration has initiated a series of dedicated studies with protons at the COSY-ring in Juelich (Germany), aimed at the commissioning of the experimental apparatus and confirmation of the predictions for spin-filtering with protons

Pricing Policy for Digital Research Data Archives

Not every digital research data archive is fully funded. Charging fees for data services may help archives to survive. Archives which follow this funding stream have to decide who has to pay, data producers or users, and how much. For the calculation of data service prices a multi-linear price function is suggested. Variables are the number of datasets and the data volume. Different user requirements and data complexity are mirrored as service levels in the price function. Its utilization is shown in a case study at the World Data Centre for Climate (WDCC)

Interplay between microstructural evolution and tribo-chemistry during dry sliding of metals

Understanding the microstructural and tribo-chemical processes during tribological loading is of utmost importance to further improve the tribological behavior of metals. In this study, the friction, wear and tribo-chemical behavior of Ni with different initial microstructures (nanocrystalline, bi-modal, coarse-grained) is investigated under dry sliding conditions. In particular, the interplay be-tween frictional response, microstructural evolution and tribo-oxidation is considered. Friction tests are carried out using ball-on-disk experiments with alumina balls as counter-bodies, varying the load between 1 and 5 N. The microstructural evolution as well as the chemical reactions beneath the samples’ surface is investigated by means of cross-sections. The samples with finer microstructures show a faster run-in and lower maximum values of the coefficient of friction (COF) which can be attributed to higher oxidation kinetics and a higher hardness. It is observed that with increasing sliding cycles, a stable oxide layer is formed. Furthermore, initially coarse-grained samples show grain refinement, whereas initially finer microstructures undergo grain coarsening converging towards the same superficial grain size after 2,000 sliding cycles. Consequently, the experimental evidence supports that, irrespective of the initial microstructure, after a certain deformation almost identical steady-state COF values for all samples are achieved