Speakers
Description
Coherent deep virtual exclusive scattering (DVES) is an important tool for mapping the quark- and gluon-matter densities of nuclei. The separation of quark and gluon contributions can be achieved by combining the $e\,{}^{Z}\!\text{A} \to e\,{}^{Z}\!\text{A}\gamma$ (DVCS), $e\,{}^{Z}\!\text{A}\to e\,{}^{Z}\!\text{A} \phi$ and $e\,{}^{Z}\!\text{A}\to e\,{}^{Z}\!\text{A}J/\Psi$ reactions. This talk will describe the potential of the proposed ``COmpact detectoR for Eic'' (CORE) to achieve precision measurements of coherent DVCS on the $\alpha$-particle at the U.S. Electron Ion Collider (EIC).
Two key challenges for DVES on nuclei are (1) measuring the net invariant momentum transfer squared $t$ to the target ion with sufficient resolution to resolve the diffractive structure; and (2) selecting truly exclusive events without excitation in the final state. Due to the large intrinsic transverse momentum spread of nuclear beams in the EIC, the $t$-resolution in DVES is optimally determined by e.g. $(e,e' J/\Psi\to \mu^+ \mu^-)$ or $(e,e' \phi\to K^+ K^-)$ kinematics. In the DVCS reaction, we must rely upon the EM calorimeter resolution to resolve the $(e,e' \gamma)$ kinematics. With CORE, this is achieved with high resolution PbWO$_4$ calorimetry covering the entire backward (electron going) hemisphere of pseudo-rapidity $-3.5\le \eta \le 0$. Establishing exclusivity is particularly favorable for the $ e \alpha \to e \alpha \gamma$ reaction, as the helium nucleus has no bound excited states. The far-forward trackers ($\eta>4.5$) and zero-degree-calorimeter (ZDC) can tag (and veto) all nuclear break-up channels of the four-nucleon system.
This talk will present the projected $^4$He DVCS yield, and reconstruction resolution with CORE in a variety of EIC kinematics. Extensions to heavier nuclei, will also be discussed.
| Submitted on behalf of a Collaboration? | Yes |
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