The correlated spectral function of the nucleus

Experiment E97-006 was performed at Thomas Jefferson National Accelerator Facility in Virginia to measure the strength of the spectral function S(E,k) via (e,e'p) for C, Al, Fr and Au at large E and k. The spectral function S(E,k) describes the probability to find a proton with removal energy E and initial momentum k in the nucleus. The goal of the experiment is to study nucleon-nucleon short range correlations that occur in nuclei due to the short range oand tensor nucleon-nucleon interaction.
Data were taken in parallel and perpendicular kinematics for the different targets. Electron and proton are detected in coincidence in two spectrometers which allows reconstruction of missing energy (Em) and missing momentum (pm). In the Plane Wave Impulse Approximation Em and pm are related to the absolute value of the initial energy E and the initial momentum k of the nucleon inside the nucleus. The deradiated spectral function for each nucleus can be extracted from the experimental data via an iterative process.
However, the region of high Em and high pm is contaminated by multi-step processes, rescattering of the knocked-out nuclon and [...]-excitation. The kinematics was chosen to minimize those effects but they are still significant and need to be corrected for. For that purpose, different kinematics and a variety of nuclei were used in the experiment to allow by their comparison to shed some light on those effects. Theoretical corrections as an additional handle on the multi-step processes are being computed.
The comparison with calculations reveals various discrepancies with the data. On one hand, for the parallel kinematics, which minimises the influence of FSI, one finds roughly agreement. On the other hand, the perpendicular kinematics confirm the importance of the FSI, the spectral function being bigger than the parallel experimental one. The use of the different targets emphasises this behavior; the FSI contributions, which increase with the target mass, tend to overwhelm the correlated region.