System Size Dependence of Net-charge and Net-proton Fluctuations From Au+Au and Ru+Ru/Zr+Zr-mixed Collisions at $\sqrt{s_{NN}}= 200 GeV$ From STAR

Fluctuations of conserved charges have been extensively studied as sensitive probes to the evolution of heavy-ion collisions. In 2018, the STAR experiment collected large datasets of isobaric collisions of Ru+Ru and Zr+Zr at 200 GeV, which provide an opportunity to study the conserved charge fluctuations with good precision and to compare with similar measurements from the larger Au+Au collision system. The identity of isobar collisions is currently blinded but we can still perform measurements using average of Ru+Ru and Zr+Zr (iso-mixed data). In this talk, we present measurement of cumulants of the net-proton and net-charge multiplicity distribution up to fourth-order from the Ru+Ru and Zr+Zr iso-mixed data. The results are compared with similar results from Au+Au collisions.