摘要：The vacancy-type defects induced by co-implantation of He and H ions in China Low Activation Martensitic (CLAM) steel at room temperature were investigated with a variable-energy position beam Doppler broadening spectra (DBS). The co- implantation contained two patterns: one was implanted by He ions firstly, and then followed by H-ions implantation; the other was implanted by H ions in the first place, after that followed by He-ions implantation. The S parameters of implanted samples became larger than un-implanted one under different implantation fluences, and the S parameters of pre-implanted H were larger than pre-implanted He regardless of fluence. The difference of S parameters between pre-implanted H and He decreased with increasing fluence. He-H-vacancy complex is the reason that the S parameter of pre-implanted H is higher than pre-implanted He
摘要：Warped accretion disks have attracted intensive attention because of their critical role on shaping the spin of supermassive massive black holes (SMBHs) through the Bardeen-Petterson effect, a general relativistic effect that leads to final alignments or anti-alignments between black holes and warped accretion disks. We study such alignment processes by explicitly taking into account the finite sizes of accretion disks and the episodic lifetimes of AGNs that delineate the duration of gas fueling onto accretion disks. We employ an approximate global model to simulate the evolution of accretion disks, allowing to determine the gravitomagnetic torque that drives the alignments in a quite simple way. We then track down the evolutionary paths for mass and spin of black holes both in a single activity episode and over a series of episodes. Given with randomly and isotropically oriented gas fueling over episodes, we calculate the spin evolution with different episodic lifetimes and find that it is quite sensitive to the lifetimes. We therefore propose that spin distribution of SMBHs can place constraints on the episodic lifetimes of AGNs and vice versa. Applications of our results on the observed spin distributions of SMBHs and the observed episodic lifetimes of AGNs are discussed, although both the measurements at present are yet ambiguous to draw a firm conclusion. Our prescription can be easily incorporated into semi-analytic models for black hole growth and spin evolution.