Dave Meekins | Searcharxiv

arXiv2022

SIDIS Measurement with A=3 Nuclei

We introduce a new experimental effort at Jefferson Lab (JLab) to precisely measure the ratios of charged pion electroproduction in Semi-Inclusive Deep Inelastic Scattering (SIDIS) from $^2$D, $^3$He, and $^3$H targets \cite{c12-21-004}. This conditionally approved experiment (C12-21-004) aims to run in Hall-B using the standard CLAS12 configuration and a new target system developed for the approved quasi-elastic experiment (E12-20-005). In this data-driven study, we will measure the cross-sections as a function of ($x$, $Q^2$, $z$, $P_T$) to allow the extraction of the unpolarized parton distribution functions (PDFs), transverse momentum distributions (TMDs) and fragmentation functions (FFs) in A = 3 nuclei. By using super-ratios of pion yields of SIDIS off light nuclei over a wide $x_B$ range, we search for evidence of a flavor dependence in the EMC effect, giving us new insights into the effect of the nuclear environment on valance quarks. Double-ratios between A = 3 mirror nuclei can provide a direct measurement of the d/u ratios at large x due to their similar and well-understood nuclear corrections. With the utilization of mirror nuclei and the large kinematic range, and high precision of CLAS12, we will be able to maintain the sensitivity to the underlying physics but dramatically decrease the nuclear uncertainties due to attenuation and hadronization in heavy nuclei targets.

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arXiv2020

Precision measurements of A=3 nuclei in Hall B

We propose a high-statistics measurement of few body nuclear structure and short range correlations in quasi-elastic scattering at 6.6 GeV from $^2$H, $^3$He and $^3$H targets in Hall B with the CLAS12 detector. We will measure absolute cross sections for $(e,e'p)$ and $(e,e'pN)$ quasi-elastic reaction channels up to a missing momentum $p_{miss} \approx 1$ GeV/c over a wide range of $Q^2$ and $x_B$ and construct the isoscalar sum of $^3$H and $^3$He. We will compare $(e,e'p)$ cross sections to nuclear theory predictions using a wide variety of techniques and $NN$ interactions in order to constrain the $NN$ interaction at short distances. We will measure $(e,e'pN)$ quasi-elastic reaction cross sections and $(e,e'pN)/(e,e'p)$ ratios to understand short range correlated (SRC) $NN$ pairs in the simplest non-trivial system. $^3$H and $^3$He, being mirror nuclei, exploit the maximum available isospin asymmetry. They are light enough that their ground states are readily calculable, but they already exhibit complex nuclear behavior, including $NN$ SRCs. We will also measure $^2$H$(e,e'p)$ in order to help theorists constrain non-quasielastic reaction mechanisms in order to better calculate reactions on $A=3$ nuclei. Measuring all three few body nuclei together is critical, in order to understand and minimize different reaction effects, such as single charge exchange final state interactions, in order to test ground-state nuclear models. We will also measure the ratio of inclusive $(e,e')$ quasi-elastic cross sections (integrated over $x_B$) from $^3$He and $^3$H in order to extract the neutron magnetic form factor $G_M^n$ at small and moderate values of $Q^2$. We will measure this at both 6.6 GeV and 2.2 GeV.

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