Recently, Professor Li Jianxin from the Laser and Particle Beam Science and Technology Institute, XJTU School of Science, cooperated with Professor Christoph H. Keitel's group from the Max Planck Institute, Germany. Together, they found that a clash between the super-intense long laser pulses (with the wave length ranging from 6 to 10 or even longer) and relativistic electron beams would lead to two x-ray peaks on electronic backward radiation spectrums. The intensity and the corresponding polarization of the x-ray peaks are sensitive to the carrier phaseof the driving laser pulsein linear monotonic change, which provides evidence for localizing the carrier phase of long laser pulsesfor PW driving. The result has been published in the online journal Physical Review Letters.