The Polarized Internal Gas Target of ANKE at COSY

Near-threshold φ meson production in proton–nucleus reactions and φ width in finite nuclei

“…with employing for this width the free one (dotted line in figure 3) and that depicted by solid curve in figure 1 (solid line in figure 3). We observe in this figure the visible experimentally separated differences between all calculations corresponding to different scenarios for the φ width in nuclei only for targets heavier than the Al target, where they are less than ∼ 10%, 8 which means that the future data from the ANKE-at-COSY experiment [15,16] performed using the heavy target nuclei (Cu, Ag, Au) should help, as one may hope, to distinguish between these scenarios.…”

“…the ratio of the nuclear total phi production cross section from pA reactions divided by A to the same quantity on 12 C. But instead of this ratio, first we consider the following analogous ratio R( A X)/R( 12 C) = ( σpA→φX /A)/( σp 12 C→φX /12), where σpA→φX is the nuclear cross section for φ production from proton-nucleus collisions in the whole ANKE acceptance window: 0.6 GeV/c p φ 1.8 GeV/c and 0 • θ φ 8 • . It is clear that our predictions for the latter ratio could be directly compared with the future data from the ANKE experiment [15,16] to extract the definite information on the φ width in the nuclear matter.…”

“…Looking at these figures, one can see that the secondary pion-induced reaction channel πN → φN plays a minor role for all considered target nuclei in the phi high-momentum interval 1.5 GeV/c p φ 1.8 GeV/c. This means that to put strong constraints on the in-medium φ width one needs to compare the results of more reliable model calculations, based only on the direct phi production mechanism, with the respective high-momentum data from the ANKE experiment [15,16].…”

“…Following the above method, in this paper we perform a detailed analysis of the φ production in pA interactions at 2.83 GeV beam energy. This energy was employed in the recent measurements of proton-induced φ production in nuclei at the ANKE-COSY facility [15,16]. We present the detailed predictions for the A and momentum dependences of the absolute and relative cross sections for the φ creation from these interactions obtained in the framework of a nuclear spectral function approach [4,[17][18][19][20][21] for an incoherent primary proton-nucleon and secondary pion-nucleon phi meson production processes in a different scenarios for the total φ in-medium width as well as with imposing the ANKE spectrometer kinematical cuts on the laboratory φ momenta and production angles.…”

Polarized Jets And Storage Cell Targets For Storage Rings

“…1. The ANKE target [29,30] at COSY: The state of the art ABS for polarized H and D atoms is operational and has produced up to 7-10 16 H/s into the compression tube. A Lamb shift polarimeter is used to optimize the system of rf transitions.…”