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莫晓虎 张建勇 张清江 Achasov Mikhail 蔡啸 傅成栋 Harris Fred 刘倩 Muchnoi Nikolay 秦庆 屈化民 王贻芳 徐金强 张天保 《中国物理 C》2011,35(7):642-655
Understanding the radiation background at the north crossing point (NCP) in the tunnel of BEPCII is crucial for the performance safety of the High Purity Germanium (HPGe) detector, and in turn of great significance for long-term stable running of the energy measurement system. Therefore, as the first step, a NaI(Tl) detector is constructed to continuously measure the radiation level of photons as background for future experiments. Furthermore, gamma and neutron dosimeters are utilized to explore the radiation distribution in the vicinity of the NCP where the HPGe detector will be located. Synthesizing all obtained information, the shielding for neutron irradiation is studied based on model-dependent theoretical analysis. 相似文献
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The China Spallation Neutron Source(CSNS) is going to be located in Dalang Town,Dongguan City in the Guangdong Province.In this paper we report the results of the parameters related with environment safety based on experiential calculations and Monte Carlo simulations.The main project of the accelerator is an under ground construction.On top there is a 0.5 m concrete and 5.0 m soil covering for shielding,which can reduce the dose out of the tunnel's top down to 0.2 μSv/h.For the residents on the boundary of the CSNS,the dose produced by skyshine,which is caused by the penetrated radiation leaking from the top of the accelerator,is no more than 0.68 μSv/a.When CSNS is operating normally,the maximal annual effective dose due to the emission of gas from the tunnel is 2.40×10-3 mSv/a to the public adult,and 2.29×10-3 mSv/a to a child,both values are two orders of magnitude less than the limiting value for control and management.CSNS may give rise to an activation of the soil and groundwater in the nearest tunnels,where the main productions are 3H,7Be,22Na,54Mn,etc.But the specific activity is less than the exempt specific activity in the national standard GB13376-92.So it is safe to say that the environmental impact caused by the activation of soil and groundwater is insignificant.To sum up,for CSNS,as a powerful neutron source device,driven by a highenergy high-current proton accelerator,a lot of potential factors affecting the environment exist.However,as long as effective shieldings for protection are adopted and strict rules are drafted,the environmental impact can be kept under control within the limits of the national standard. 相似文献
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估算问题在高考中经常出现,科学研究和实际生活中也需要对一些问题进行估算,从而大致把握一些事物的发展.因此估算题的考查,实际上是对考生综合能力的考查,有利于开发学生的智力和灵活运用知识的能力.因此,在实际教学中要特别注意培养学生的估算能力.本文将结合近几年的高考题目和同学们一起探讨如何估算的问题. 相似文献
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莫晓虎 E. V. Abakumova M. N. Achasov V. E. Blinov 初元萍 董海义 傅成栋 F. A. Harris V. V. Kaminskiy A. A. Krasnov 李小南 刘倩 N. Yu. Muchnoi I. B. Nikolaev E. E. Pyata 屈化民 秦庆 A.G. Shamov 沈成平 G. S. Varner 王贻芳 徐金强 张建勇 张清江 张银鸿 张天保 V. N. Zhilich 赵卓 A. A. Zhukov 《中国物理 C》2010,34(6):912-917
The beam energy measurement system at BEPCII is composed of there parts: laser source and optics system, laser-electron interaction system and High Purity Germanium (HPGe) detector system. The special components and construction of each part are introduced, especially about radiation background measurement in the storage ring, which is of great importance for the safe commissioning of HPGe detector. 相似文献
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BEPCⅡ is a double ring e+ecollider with high beam currents and luminosity,so the high beamrelated backgrounds may disturb the detector.In order to have a good quality of data taking,backgrounds should be kept at a level as low as possible.A series of collimators are designed and installed in both the e+ and erings.Two of the collimators are horizontally movable,each for one ring,about 8 m upstream from the interaction point.Experiments have been done to identify the e-ectiveness of the movable collimators with different apertures and beam currents.The results show that the movable collimators are very effective and can reduce as much as about 50% of beam-related backgrounds. 相似文献
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莫晓虎 张建勇 张天保 张清江 Achasov Mikhail 傅成栋 Muchnoi Nikolay 秦庆屈化民 王贻芳 吴靖民 徐金强 俞伯祥 《中国物理 C》2009,33(10):914-921
The technique details for measuring radiation dose are expounded. The results of gamma and neutron radiation levels are presented and the corresponding radiation shielding is discussed based on the simplified estimation. In addition, the photon radiation level move as background for future experiments is measured by a NaI(T1) detector. 相似文献