x-index: a fantastic new indicator for quantifying a scientist's scientific impact.

h-index has become the most popular indicator for quantifying a scientist's scientific impact in various scientific fields. h-index is defined as the largest number of papers with citation number larger than or equal to h and it treats each citation equally. However, different citations usually come from different papers with different influence and quality, and a citation from a highly influential paper is a greater recognition of the target paper than a citation from an ordinary paper. Based on this assumption, we proposed a new indicator named x-index to quantify a scientist's scientific impact by considering only the citations coming from influential papers. x-index is defined as the largest number of papers with influential citation number larger than or equal to x, where each influential citation comes from a paper for which the average ACNPP (Average Citation Number Per Paper) of its authors larger than or equal to x . Through analysis on the APS dataset, we find that the proposed x-index has much better ability to discriminate between Physics Prize Winners and ordinary physicists.