分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: Amino-type adsorbents (ATAs) were prepared by radiation-induced graft copolymerization of 4-hydroxybutyl acrylate glycidyl ether (HB) onto a polyethylene-coated polypropylene (PE/PP) duplex fiber of a non-woven fabric, and modified with different amines of ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and diethylamine (DEA). The adsorption behavior of uranyl ions onto the ATAs was studied in batch experiments. The effects of the contact time, initial concentration of the ions, temperature, and pH value. The salinity were investigated along with the adsorption kinetics and the adsorption isotherms. The kinetic experimental data followed the pseudo second-order kinetic model, and the adsorption isotherms correlated well with the Langmuir model. The ATAs showed good efficiency in adsorbing uranyl ions, with the best saturation adsorption capacity being 64.26 mg g-1 for ATA-DETA within 120 min. The temperature dependence of ATA-DETA was quite abnormal and the quickest behavior was obtained at 25 ℃. ATAs showed good adsorption capacity over a wide pH range of 4.08.5, and HCl could be used in the elution process. Salinity of the solution had great effect on the adsorption capacity, 3.5% salinity resulted in a 55% loss of capacity from ATA-DETA. The selectivity of ATA-DETA showed an order of: UO22+ Fe3+ > Zn2+ > VO3- > Co2+ > Ni2+.
分类: 物理学 >> 核物理学 提交时间: 2016-09-13
摘要: Aging experiments of a novel type of large area MCP-PMT made by JUNO collaboration were conducted.In these aging experiments, the multi-photoelectron spectrum and single photoelectron spectrum were measured daily,as well as the MCP resistance of the second PMT before and after the experiment. Two PMTs were aged successivelyfor cross check. The first PMT was aged for 52 days, while the other one was aged for 84 days. In order to study the mechanism of the aging process, the high voltage on the second PMT was increased to accelerate its aging process when the cumulative output of charge from its anode was about 4 C. From our study, it can be known that large area MCP-PMT aging had a strong relationship with the related MCPs. In accordance with the PMT aging curve,a PMT aging model was setup and a general aging formula was given.
分类: 物理学 >> 核物理学 提交时间: 2016-09-02
摘要: Reactor neutrino experiments build large-scale detector systems to trap ghost-like neutrinos. In liquid scintillator, a neutral bound state of a positron and an electron named positronium could be formed. The spin triplet state was called ortho-positronium (o-Ps). In this script, an experiment was designed to measure the lifetime of o-Ps, which turned out to be 3.1 ns. A PSD parameter based on photon emission time distribution (PETD) was constructed to discriminate e+/e−. Finally the application of e+/e− discrimination in JUNO experiment was shown. It helps suppression of 8He/9Li backgrounds and improves the sensitivity by 0.6 in χ2 analysis with assumption of σ=1 ns PMT Transit Time Spread, which will bring smearing effect to PETD.