不可压缩超弹性止水材料的粘弹性计算方法研究

发展改进了研究不可压缩超弹性材料的Mooney-Rivlin公式,把材料参数假设成是随时间变化的粘弹性函数,并讨论了粘弹性函数的推导方法,通过工程实例进行了实验计算,并将计算结果与应力松弛试验进行了比较.结果表明,用改进Mooney-Rivlin公式可以简便有效地计算该类材料的粘弹性问题,为解决工程实际问题提供了新的途径.     

Study of radiation background at the north crossing point of the BEPCⅡ in collision mode

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.     

改进型Andersson–Braun中子雷姆仪对0.025eV–45.4MeV中子的能量响应

描述了一种适用于高能粒子加速器周围杂散辐射场测量的改进型Andersson-Braun中子雷姆仪的原理与结构. 利用国内外多种类型的中子源装置,进行了中子能量从0.025eV-45.4MeV的注量率能量响应实验,实验表明,这种改进型Andersson-Braun中子雷姆仪,对能量大于20MeV中子的响应,比普通Andersson-Braun中子雷姆仪有明显的改善.     

Analysis of radiation environmental safety for China＇s Spallation Neutron Source （CSNS）

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.     

Beam energy measurement system at BEPCⅡ

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.     

教学中要注意对学生估算能力的培养

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．     

改进型Andersson-Braun中子雷姆仪对0.025eV-45.4MeV中子的能量响应

描述了一种适用于高能粒子加速器周围杂散辐射场测量的改进型Ａｎｄｅｒｓｓｏｎ－Ｂｒａｕｎ中子雷姆仪的原理与结构。利用国内外多种类型的中子源装置，进行了中子能量从０．０２５ｅＶ－４５．４ＭｅＶ的注量率能量响应实验，实验表明，这种改进型Ａｎｄｅｒｓｓｏｎ－Ｂｒａｕｎ中子雷姆仪，对能量大于２０ＭｅＶ中子的响应，比普通Ａｎｄｅｒｓｓｏｎ－Ｂｒａｕｎ中子雷姆仪有明显的改善。     

北京正负电子对撞机(BEPC)同步辐射实验厅辐射剂量水平的测定

本文描述了北京正负电子对撞机(BEPC)同步辐射实验厅内辐射的来源和特点,辐射测量方法及其测量结果.通过对东、西两个实验厅的辐射剂量水平随时间和空间变化的分析,得出一个重要的结论:同步辐射实验厅内辐射剂量水平与实验厅相对正负电子束流注入点的位置、屏蔽墙厚度、束流注入的时间和效率有密切关系.     

Application of movable collimators to the BEPCⅡ

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.     

Measurement of radiation dose at the north interaction point of BEPCⅡ

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.