### Special Nuclear Physics Seminar

Tuesday, April 20, 2021
2:00pm – 3:00pm

Storrs Campus
WebEx

Abstract: As the size of an atomic nucleus gets bigger and bigger, the neutron-proton asymmetry becomes more and more prominent. This asymmetry characterizes the Symmetry Energy which affects the nuclear binding energy and other nuclear properties. While the central core of the nucleus is composed of symmetric nuclear matter, the extra neutrons in heavy nuclei are pushed out to the surface of the nucleus, forming a pure outer neutron skin layer. In contrast to the proton distribution inside a nucleus, which has been accurately measured with electron scattering, the previous measurements of neutron distributions have suffered a lack of systematic precision. PREX-2, which ran in Hall A of Jefferson lab from summer to fall of 2019, used the parity-violating signature of the weak interaction to measure the neutron distribution in $^{208}$Pb nuclei with unprecedented precision. Subtracting the previously measured proton distribution ($R_p$) from the neutron distribution ($R_n$), PREX-2 reports the neutron skin thickness in $^{208}$Pb nuclei. The measured neutron skin has a broad range of applications from calibration of the facility for radioactive isotope beams (FRIB) to neutron star structure. This talk will focus on PREX-2 measurement and highlight its broad implications.