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Experiment Research

E05-110: Precision Measurement on Longitudinal and Transverse Response Functions of Quasi-Elastic Scattering in the Momentum Transfer Range 0.55GeV/c = |q| = 0.9GeV/c

A long-standing question in nuclear physics is whether the properties of protons and neutrons (and their building blocks: quarks) are modified when they are embedded in a nucleus. This possibility was brought to prominence in the mid-eighties by two results. The first was the discovery of the "nuclear EMC effect" - where the results obtained from experiments in which electrons were used to probe quarks in nuclei differed from those in which electrons were used to probe quarks in a free proton. For the second result, physicists discovered the violation of the "Coulomb sum rule," where the response to electrons scattering directly from the protons (not the quarks) in nuclei was found to be quenched, or less than, that of free protons.

This experiment aims to confirm or refute previous experimental results, and more importantly, to reach a range of momentum transfer (resolution) much extended and a precision much enhanced than previously achieved. The range of resolution covered by this experiment will allow an unambiguous interpretation of the data, and as a consequence, any modification of the properties of protons or neutrons in the nuclear medium will have consequences on our insights into the behavior of quarks and gluons inside a nucleus.

E05-110 Technical Paper (.pdf)