Wesselmann, F. R. | Search NASA

DOE OSTI2021

Measurement of the EMC effect in light and heavy nuclei

In this work, inclusive electron scattering from nuclear targets has been measured to extract the nuclear dependence of the inelastic cross section in Hall C at the Thomas Jefferson National Accelerator facility. Results are presented for 2 H, 3 He, 4 He, 9 B, 12 C, 63 Cu and 197 Au at an incident electron beam energy of 5.77 GeV for a range of momentum transfer from Q 2 = 2 to 7 (GeV/c) 2 . These data improve the precision of the existing measurements of the EMC effect in the nuclear targets at large x, and allow for more detailed examinations of the A dependence of the EMC effect.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2021

Spectroscopy of A=9 hyperlithium with the $(e,e^{\prime}K^{+})$ reaction

Missing mass spectroscopy with the $(e,e^{\prime}K^{+})$ reaction was performed at JLab Hall C for the neutron rich $\Lambda$ hypernucleus $^{9}_{\Lambda}{\rm Li}$. The ground state energy was obtained to be $B_{\Lambda}^{\rm g.s.}=8.84\pm0.17^{\rm stat.}\pm0.15^{\rm sys.}~{\rm MeV}$ by using shell model calculations of a cross section ratio and an energy separation of the spin doublet states ($3/2^{+}_1$ and $5/2^{+}_1$). In addition, peaks that are considered to be states of [$^{8}{\rm Li}(3^{+})\otimes s_{\Lambda}=3/2^{+}_{2}, 1/2^{+}$] and [$^{8}{\rm Li}(1^{+})\otimes s_{\Lambda}=5/2^{+}_{2}, 7/2^{+}$] were observed at $E_{\Lambda}(\#2)=1.74\pm0.27^{\rm stat.}\pm0.11^{\rm sys.}~{\rm MeV}$ and $E_{\Lambda}(\#3)=3.30\pm0.24^{\rm stat.}\pm0.11^{\rm sys.}~{\rm MeV}$, respectively. The $E_{\Lambda}(\#3)$ is larger than shell model predictions by a few hundred keV, and the difference would indicate that a ${\rm ^{5}He}+t$ structure is more developed for the $3^{+}$ state than those for the $2^{+}$ and $1^{+}$ states in a core nucleus $^{8}{\rm Li}$ as a cluster model calculation suggests.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗