pp Elastic Scattering: New results from EDDA (COSY)

In the EDDA experiment excitation functions of proton-proton elastic scattering are studied with narrow steps in the projectile momentum range from 0.8 to 3.4 GeV/c and the angular range $35°⩽Θcm⩽90°$ with a detector providing $ΔΘcm≈1.4°$ resolution and 85% solid angle coverage. Measurements are performed continuously during projectile acceleration in the Cooler Synchrotron COSY. In phase 1 of the experiment spin-averaged differential cross sections dσ/dΩ have been measured with an internal $CH2$ fiber target; background corrections were derived from measurements with a carbon fiber target and from Monte Carlo simulations of inelastic pp contributions. The results provide excitation functions and angular distributions of high precision and internal consistency. In phase 2 of the experiment excitation functions of the analyzing power $AN$ have been measured using a polarized $(P⩾75%)$ atomic beam target, and those of the polarization correlation parameters $ANN,$ $ASS$ and $ASL$ will be measured lateron with the polarized COSY beam. The measured excitation functions are compared to recent phase shift analyses, and their impact on them is discussed. So far evidence for narrow structures was neither found in the spin averaged cross sections nor in the analyzing powers.