苏州阳澄湖地区淤泥质粘土工程地质特性探讨

苏州阳澄湖周围的沼积湖积平原存在一种性质较为特殊的淤泥质粘土,其亲水性粘土矿物含量和液塑限指标均较高,但在天然状态下虽具一定的胀缩性却未达到膨胀土的标准,可是经过扰动压实后,随着干密度的增大和含水量的减少却表现出较强的胀缩性,即转变为“人工膨胀土”[1]。本文通过苏州阳澄湖东北方向某一级公路附近3个取土场土样的试验分析,探讨了此地区这种淤泥质粘土的特殊性,为以后的工程施工提供了科学依据。     

A new method for high-energy pulsed Gamma measurement within intense background x-rays

The accelerator-generating 6.13~MeV pulsed Gamma by ¹⁹F(p, αγ )¹⁶⁰ reaction usually synchronizes with an intense bremsstrahlung x-ray which has a maximum energy of 1~MeV. This paper proposes a new method, named the scattering and absorbing method, to diagnose the 6.13~MeV Gamma. This method includes two parts: the detector and a scatterer placed in front of the detector. The detector converts the Gamma to electrons and then collects the electrons by a scintillator. In order to restrain the interference of the low-energy background, the scintillator collects the electrons at a small angle. The scintillator is wrapped with electro-absorbing material to absorb the low-energy electrons generated by background x-rays. The theoretical sensitivity ratio of 6.13~MeV Gamma to 1~MeV x-rays is greater than 150. The scatterer is a pretreatment tool to scatter some background x-rays away from the radial beam before they enter the detector. By varying the length, the scatterer can reduce the background x-rays to an acceptable level for the detector.     

Design and gamma sensitivity measurement of a novel dual-emitter vacuum Compton detector

A novel dual-emitter vacuum Compton detector (D-VCD) with higher gamma ray detecting efficiency is proposed. The emitters are made of Ta--Al clad metal. The gamma ray sensitivity is studied by Monte Carlo simulation using the MCNP code. A comparison between calculations and results measured by using the 1.25~MeV gamma ray of Co-60 is also performed. Experimental sensitivities for two sample D-VCDs with the same materials and structures are 1.92×10^ - 20 and 2.02×10^ - 20~C.cm²/MeV separately, which are consistent with the simulation result of 1.98×10^ - 20~C.cm²/MeV and are 4 times higher than that of VCD with a single Fe emitter. According to the simulation results, in a gamma energy range from 0.5 to 3~MeV, the maximum sensitivity variance for the D-VCD is less than 15%, and less than 5% in a range from 1 to 2~MeV in particular. The novel D-VCD is applicable to the detection of intense pulse gamma rays.     

掺杂有机染料的铅锡氟磷酸闪烁玻璃及其在伽马激发下的发光

制备了掺杂有机染料芪420的铅锡氟磷酸盐杂化闪烁玻璃(lead tin fluorophosphates,简记为PTFP),测量其玻璃转变温度为75℃,染料在玻璃中的荧光发射峰位为446nm.测量了几种掺杂浓度的闪烁玻璃在⁶⁰Co源1.25MeV伽马射线激发下的发光,并和同样厚度的有机闪烁体ST401的发光进行比较,约为ST401发光的1%—2%. 关键词： 铅锡氟磷酸 闪烁玻璃 芪420 伽马     

Experimental study on scintillation efficiency of ZnO:In to proton response

Film ZnO:In crystal is a good candidate for a scintillation recoil proton neutron detection system and the response of ZnO:In to protons is a crucial point. The energy response of ZnO:In to mono-energetic protons in the range of 10 keV-8 MeV was measured. The experiment was carried out in current mode, and Au foil scattering was employed, where the forward scattering protons were used for exciting the sample, and the backward scattering protons were used for monitoring the beam intensity. According to the result, the yield of light non-linearly depends on proton energy, and drops significantly when proton energy is low. The scintillation efficiency as a function of proton energy was obtained, which is very useful for researching the scintillation recoil proton neutron detection system.     

A new method for detecting pulse gamma ray with scattered electrons

This paper describes a newly designed gamma pulse detector of current mode that uses the scattered electron method. Tungsten is used as the scattering target, an organic thin film scintillator ST401 is used to collect the scattered electrons. The spatial distribution of the electronic energy-flux density is studied by using the MCNP code. The optimization of the target and the thickness of the scintillator are also discussed. The results indicate that the energy response is relatively flat in the range of 0.4 to 5 MeV.     

狭缝式裂变探测系统的中子灵敏度解析计算方法

 利用基于解析公式的理论方法来计算狭缝式裂变探测系统的中子灵敏度。采用积分和泰勒展开法推导了铀裂变材料在中子作用下产生的碎片数目及PIN探测器接收碎片的概率,并得到该系统的中子灵敏度理论计算公式。在D-T中子源上对该探测系统的中子灵敏度进行了实验标定,并将实验结果与解析公式计算得到的理论值进行比较。结果表明：理论计算值与实验结果保持一致,两者之间的偏差小于10%。