Intrinsic background radiation of LaBr3(Ce)detector via coincidence measurements and simulations

The LaBr3(Ce)detector has attracted much attention in recent years because of its superior characteristics compared with other scintillating materials in terms of resolution and efficiency.However,it has a relatively high intrinsic background radiation because of the naturally occurring radioisotopes in lanthanum,actinium,and their daughter nuclei.This limits its applications in low-counting rate experiments.In this study,we identified the radioactive isotopes in theφ3"x 3"Saint-Gobain B380 detector by a coincidence measurement using a Clover detector in a low-background shielding system.Moreover,we carried out a Geant4 simulation of the experimental spectra to evaluate the activities of the main internal radiation components.The total activity of the background radiation of B380 is determined to be 1.523(34)Bq/cm^3.The main sources include 138La at 1.428(34)Bq/cm^3,207Tl at 0.0135(13)Bq/cm^3,211Bi at 0.0136(15)Bq/cm^3,215Po at 0.0135(3)Bq/cm^3,219Rn at 0.0125(12)Bq/cm^3,223Fr at 0.0019(11)Bq/cm^3,223Ra at 0.0127(10)Bq/cm^3,227Th at 0.0158(22)Bq/cm^3,and 227Ac at 0.0135(13)Bq/cm^3.Of these,the activities of 207Tl,211Po,215Po,223Fr,and 227Ac are deduced for the first time from the secular equilibrium established in the decay chain of 227Ac.

Charge-changing cross section measurements of 300 MeV/nucleon^(28)Si on carbon and data analysis

Charge-changing cross section(σcc)measurements via the transmission method have recently seen significant progress with the aim of determining the charge radii of exotic nuclei.In this work,we report a newσcc measurement of 304(9)MeV/nucleon^(28)Si on carbon at the second Radioactive Ion Beam Line in Lanzhou(RIBLL2)and describe the data analysis procedure in detail.This procedure is essential for evaluating the systematic uncertainty in the transmission method.The determinedσcc of 1125(11)mb is found to be consistent with the existing data at similar energies.The present work will serve as a reference forσcc determinations at RIBLL2.

Towards the full realization of the RIBLL2 beam line at the HIRFL-CSR complex

More than 99%of the mass in the visible universe—the material that makes up ourselves,our planet,stars—is in the atomic nucleus.Although the matter has existed for billions of years,only over the past few decades have we had the tools and the knowledge necessary to get a basic understanding of the structure and dynamic of nuclei.Nuclear physicists around the world have made tremendous strides by initiating a broad range of key

Miniaturized Rotman lens with applications to wireless communication

Rotman lens is a type of beamforming network with many advantages,such as true-time delay characteristic,multibeam capability,and wide bandwidth.Rotman lens has been used in a wide range of applications in today’s wireless communication systems.However,the size of a conventional Rotman lens is considerably large.So,difficulties may arise with respect to its integration with base station antennas in wireless communication systems.In this study,three techniques for the miniaturization of a Rotman lens,i.e.,Chebyshev impedance transformers,power dividers,and truncated ports with energy distribution slots,are introduced to design the Rotman lens to reduce the size of the ports and hence the total area occupied by the Rotman lens.Simulation and measurement results indicate that good impedance matching between the lens body and its feed lines can be achieved.Using the proposed truncated ports with energy distribution slots,the size of the Rotman lens can be greatly reduced without performance degradation or production cost increment.Moreover,two possible applications of the proposed miniaturized Rotman lens to wireless communication systems are investigated.Rotman lens can not only provide multiple phase difference signals along the array ports to realize multibeams,but also generate high-performance formed beams such as flat-topped radiation pattern.