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Measurements of proton beam flux and energy of APEP using foil activation technique
Li Wenlin,Dong Qifan,Jing Hantao,Ou Li,Tan Zhixin,Zhuang Sixuan,Wu Qingbiao 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.1
The activation method of metallic foils is an important technique to measure the flux and energy of proton beams. In this paper, the method was used to measure the CSNS APEP proton flux at seven nominal proton energies ranging from 10 MeV to 70 MeV for beam spot sizes of the 20 mm × 20 mm and 50 mm × 50 mm. The reactions of natTi(p, x)48V, natNi(p, x)57Ni, natCu(p, x)58Co, and 27Al(p, x)24Na were employed to measure the proton beam flux with a range of 107-109 p/cm2/s. Furthermore, we also proposed a method using the activity ratio with a stacked-foil target to determine the energy spread of a Gaussian-like distribution for different nominal proton energies. The optimal combinations of Al, Cu, Ti, Ni, Mo, Fe, Nb, and In foils were adopted for the proton energies. The measured energy spreads for degraded beams of 30 MeV–70 MeV were found to be smaller than 10.00%.
Toward Tetraradicaloid: The Effect of Fusion Mode on Radical Character and Chemical Reactivity
Hu, Pan,Lee, Sangsu,Herng, Tun Seng,Aratani, Naoki,Gonç,alves, Thé,o P.,Qi, Qingbiao,Shi, Xueliang,Yamada, Hiroko,Huang, Kuo-Wei,Ding, Jun,Kim, Dongho,Wu, Jishan American Chemical Society 2016 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.138 No.3
<P>Open-shell singlet diradicaloids display unique electronic, nonlinear optical, and magnetic activity and could become novel molecular materials for organic electronics, photonics, and spintronics. However, design and synthesis of diradicaloids with a significant polyradical character is a challenging task for chemists. In this Article, we report our efforts toward a tetraradicaloid system. A series of potential tetraradicaloids by fusion of two p-quinodimethane (p-QDM) units with naphthalene or benzene rings in different modes were synthesized. Their model compounds containing one p-QDM moiety were also prepared and compared. Their ground-state structures, physical properties, and chemical reactivity were systematically investigated by various experimental methods such as steady-state and transient absorption, two-photon absorption, X-ray crystallographic analysis, electron spin resonance, superconducting quantum interference device, and electrochemistry, assisted by density functional theory calculations. It was found that their diradical and tetraradical characters show a clear dependence on the fusion mode. Upon the introduction of more five-membered rings, the diradical characters greatly decrease. This difference can be explained by the pro-aromaticity/antiaromaticity of the molecules as well as the intramolecular charge transfer. Our comprehensive studies provide a guideline for the design and synthesis of stable open-shell singlet polycyclic hydrocarbons with significant polyradical characters.</P>