A white neutron beam line using back-streaming neutrons from the spallation target is under construction at China Spallation Neutron Source (CSNS). Different spectrometers, to be installed in the so-called Back-n beam line for nuclear data measurements, are also being developed in phases. The physical design of the beam line is carried out with the help of a complicated collimation system and a sophisticated neutron dump, taking the overview of the neutron beam characteristics into account. This includes energy spectrum, flux and time structure, the optimizations of neutron beam spots and in-hall background. The wide neutron energy range of 1 eV-100 MeV is excellent for supporting different applications, especially nuclear data measurements. At Endstation#2, which is about 80 m away from the target, the main properties of the beam line include neutron flux of 10 6 n/cm 2 /s, time resolution of a few per mille over nearly the entire energy range, and in-hall background of about 0.01 /cm 2 /s for both neutron and gamma. With its first commission in late 2017, Back-n will not only be the first high-performance white neutron source in China, but also one of the best white neutron sources in the world.

The phylogenetic and epidemiological relationships of 102 Burkholderia pseudomallei clinical isolates from different geographical and population sources in China were investigated by multilocus sequence typing (MLST). The MLST data were analysed using the e-BURST algorithm, and an unweighted pair-group method with arithmetic mean dendrogram was constructed based on the pair-wise differences in the allelic profiles of the strains. Forty-one sequence types (STs) were identified, of which eight were novel (ST1341, ST1345, ST1346, ST1347, ST1348, ST1349, ST1350, ST1351). No geographical-specific or host population-specific phylogenetic lineages were identified. ST46, ST50, ST55, ST58, ST70 and ST1095 predominated, but ~44% of isolates were assigned to 45 STs illustrating high genetic diversity in the strain collection. Additionally, the phylogenetic relationships of the dominant STs in China showed significant linkeage with B. pseudomallei isolates from Thailand. Analysis of the gmhD allele suggests high genetic variation in B. pseudomallei in China.