ARPES study of doping dependence of the superconducting gap in Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_{2}$

High transition temperature superconductivity has been discovered recently in many doped iron pnictides which join the cuprates in the family of high-Tc superconductors. It is very important to understand the nature of the superconducting gap and its doping dependence, as in the case of the cuprates, in order to understand this new class of superconductors. A systematic angle-resolved photoemission spectroscopy (ARPES) study has been performed on the iron pnictide Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_{2}$ at different K concentrations, to determine its doping dependence of the superconducting gap. We will report our ARPES results and their implications.