Production of proton-rich nuclei around Z=84-90 in fusion-evaporation reactions

Within the framework of the dinuclear system model, production cross sections of proton-rich nuclei with charged numbers of Z=84-90 are investigated systematically. Possible combinations with the $^{28}$Si, $^{32}$S, $^{40}$Ar bombarding the target nuclides $^{165}$Ho, $^{169}$Tm, $^{170-174}$Yb, $^{175,176}$Lu, $^{174,176-180}$Hf and $^{181}$Ta are analyzed thoroughly. The optimal excitation energies and evaporation channels are proposed to produce the proton-rich nuclei. The systems are feasible to be constructed in experiments. It is found that the neutron shell closure of N=126 is of importance during the evaporation of neutrons. The experimental excitation functions in the $^{40}$Ar induced reactions can be nicely reproduced. The charged particle evaporation is comparable with neutrons in cooling the excited proton-rich nuclei, in particular for the channels with $\alpha$ and proton evaporation. The production cross section increases with the mass asymmetry of colliding systems because of the decrease of the inner fusion barrier. The channels with pure neutron evaporation depend on the isotopic targets. But it is different for the channels with charged particles and more sensitive to the odd-even effect.Comment: 15 pages, 10 figures. arXiv admin note: text overlap with arXiv:0803.1117, arXiv:0707.258

Three-Leaf Dart-Shaped Single-Crystal BN Formation Promoted by Surface Oxygen

Two-dimensional hexagonal boron nitride (h-BN) single crystals with various shapes have been synthesized by chemical vapor deposition over the past several years. Here we report the formation of three-leaf dart (3LD)-shaped single crystals of h-BN on Cu foil by atmospheric-pressure chemical vapor deposition. The leaves of the 3LD-shaped h-BN are as long as 18 {\mu}m and their edges are smooth armchair on one side and stepped armchair on the other. Careful analysis revealed that surface oxygen plays an important role in the formation of the 3LD shape. Oxygen suppressed h-BN nucleation by passivating Cu surface active sites and lowered the edge attachment energy, which caused the growth kinetics to change to a diffusion-controlled mode.Comment: 7 pages,6 figure

A dual cube hashing scheme for solving LPP integrity problem

In digital forensics, data stored in a hard disk usually contains valuable evidence. Preserving the integrity of the data in the hard disk is a critical issue. A single hash value for the whole hard disk is not appropriate as the investigation may take a long time and latent sector errors (LSEs) (bad sectors due to media imperfection, for example) which cause a sector suddenly unreadable will make the hash value inconsistent. On the other hand, using a hash per sector may need to store a lot of hash values. Previous research has been conducted to use fewer hash values, but can resist some of LSEs to decrease the number of unverifiable sectors even if there are LSEs. This integrity problem is more complicated in the presence of Legal Professional Privileged (LPP) data inside a seized hard disk in digital forensic as the hard disk has to be cloned once seized and the original hard disk will be sealed after cloning. Hash values need to be computed during this cloning process. However, the cloned copy will be returned to the suspect for the deletion of LPP data before the investigator can work on the sanitized copy. Thus, the integrity of unmodified sectors has to be verified using the hash values computed based on the original hard disk. This paper found that existing schemes are not good enough to solve the integrity problem in the presence of both LSEs and deletion of LPP data. We then propose the idea of a "Dual Cube" hashing scheme to solve the problem. The experiments show the proposed scheme performs better than the previous schemes and fits easily into the digital forensic procedure. © 2011 IEEE.published_or_final_versionThe 6th International Workshop on Systematic Approaches to Digital Forensic Engineering In conjunction with the IEEE Security and Privacy Symposium (IEEE/SADFE 2011), Oakland, CA., 26 May 2011. In IEEE/SADFE Proceedings, 2011, p. 1-