Darmstadt 2016 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 64: Hadron Structure and Spectroscopy XI

HK 64.5: Talk

Friday, March 18, 2016, 15:15–15:30, S1/01 A5

Measurement of the absolute differential cross section of proton-proton elastic scattering at small angles, using ANKE-COSY facility — •Zara Bagdasarian — Forschungszentrum Juelich

The most accepted approach to describe nucleon-nucleon (NN) interaction is the partial wave analysis (PWA). The goal of many experiments held at COSY-Jülich has been to provide PWA with valuable precision measurements at different energies aiming to cover the full angular range. This contribution reports on the differential cross section for proton-proton elastic scattering that has been measured at a beam energy of 1.0 GeV and in 200 MeV steps from 1.6 to 2.8 GeV at centre-of-mass angles between about 10 and 30 degrees.

The ANKE collaboration and the COSY machine crew have jointly developed a very accurate method for determining the absolute luminosity in an experiment at an internal target position. The technique relies on measuring the energy losses due to the electromagnetic interactions of the beam as it passes repeatedly through the thin target and measuring the shift of the revolution frequency by studying the Schottky spectrum. This powerful technique allows one to measure the absolute differential cross section for elastic pp scattering with the accuracy of typically 3%.

After extrapolating the differential cross sections to the forward direction, the results are broadly compatible with the predictions of forward dispersion relations. Finally, it is shown that the data have a significant impact on the partial wave analysis.