Orateur
Description
The goal of the ALERT experiment is to advance the understanding of the QCD structure of the nuclear matter. It proposes a precise measurement of the electro production of a real photon through the interaction with $^4\mbox{He}$ and $^2\mbox{D}$ targets. This process, referred to as Deeply Virtual Compton Scattering (DVCS), gives access to Generalized Parton Distributions (GPDs). The GPDs are used to perform a tomography of the quarks inside the nucleus, to understand the origin of its spin, and to access the shear forces inside it. To achieve this experiment, the Continuous Electron Beam Accelerator Facilities of Jefferson Lab, which can deliver spin polarized electron beam up to 11 GeV, are used. All the final states of the process are detected by pairing the CLAS12 spectrometer with the novel low-energy ALERT recoil tracker. ALERT consists of a hyperbolic drift chamber for track reconstruction and an array of scintillators for particle identification. It is specifically designed to detect low-energy recoil fragments ($^4\mbox{He}$, $^3\mbox{He}$, $^3\mbox{H}$, $^2\mbox{H}$, p).
After the success of the data taking, from April to September 2025, efforts are currently dedicated to the finalization of the reconstruction software and the calibration of the data. In this talk, I will briefly describe the main goal of the ALERT experiment, detail the latest update of the data reconstruction chain, and present a preliminary extraction of the Beam Spin Asymmetry of the coherent DVCS off $^4\mbox{He}$.
| Working Group | WG1. Nucleons and Hadrons |
|---|---|
| Type of oral contribution | Experiment |