Precision measurement of longitudinal and transverse response functions of quasi-elastic electron scattering in the momentum transfer range 0.55 GeV/c≤|q ⃗|≤0.9GeV/c

Abstract

In order to test the Coulomb sum rule in nuclei, a precision measurement of inclusive electron scattering cross sections in the quasi-elastic region was performed at Jefferson Lab. Incident electrons of energies ranging from 0.4 GeV/c to 4 GeV/c scattered off 4 He, 12 C, 56 Fe and 208 Pb nuclei at four scattering angles ( 15 • , 60 • , 90 • , 120 • ) and scattered energies ranging from 0.1 GeV/c to 4 GeV/c. The Rosenbluth method with proper Coulomb corrections is used to extract the transverse and longitudinal response functions at three-momentum transfers 0.55 GeV/c ≤ |q| ≤ 1.0 GeV/c. The Coulomb Sum is determined in the same |q| range as mentioned above and will be compared to predictions. Analysis progress and preliminary results will be presented. PHYSICS MOTIVATIONThe test of Coulomb Sum Rule will shed light on the question of whether or not the properties of nucleons are modified in the nuclear medium. Coulomb Sum Rule states that the integration of the longitudinal response of a nucleus over the range of energy excitation dominated by quasi-elastic proton knock-out process should be equal to the total number of protons in the nucleus. As a result, quenching of the response at high momentum transfer may indicate the possibility of modification of nucleons' properties in the nuclear medium.ε(| q|, ω, θ ) = 1 + 2 q 2 Q 2 tan 2 θ 2 −1 R L = | q| Q 4 σ M