Geometry of vanishing flow: a new probe to determine the in-medium nucleon nucleon cross-section

We study the transverse flow throughout the mass range from $^{20}Ne+^{20}Ne$ to $^{131}Xe+^{131}Xe$ as a function of the impact parameter. We find that at smaller impact parameters the flow is negative while going through the impact parameter, transverse flow vanishes at a particular colliding geometry named GVF. We find that the mass dependence of GVF is insensitive to the equation of state and momentum dependent interactions whereas it is quite sensitive to the cross section. So it can act as a useful tool to pin down the nucleon nucleon cross section.