八单元一维位置灵敏雪崩室

In the experiment of nuclear reaction, it is important to measure the mass, charge, energy and emitted direction of particles. For multiparameter measurement, we must use a detector or a group of detectors which can give the time, energy, and position information. The Large Area position sensitive Ionization Chamber(LAIC) is one of the eight experiment terminals of HIRFL. It is built for researching nuclear reactions from low energy to intermediate energy. It is an excellent equipment for energy measurements and atomic number identification of emitted fragments in this energy region. It is also designed to give the time and position information of the emitted fragments by itself. Obviously, an IC can not supply a good timing signal. Moreover, the mechanical installation is different from the original design by some other reasons. In this case, it is not enough to obtain the correct direction information of the emitted fragments. To obtain good timing signals and the correct direction information, some modifications must be made. It is well known that a PPAC can give us excellent timing signals. It also can be easily built as a position sensitive detector. For this reason, a specially designed PPAC is installed in the entrance of the LAIC. For the different purposes, two types of PPACs were designed and tested. Both are OCTPSACs (OCTunit one dimension Position Sensitive Avalanche Counter). In this paper, both OCTPSACs will be introduced. Based on the requirements of the LAIC, the OCTPSACs consist of eight position sensitive PPACs. Each PPAC has an anode and a cathode. In both cases, the sizes are same. But different type of cathodes are used. In one type of OCTPSAC, its cathode is made of wire plane. It consists of gold-plated tungsten wires with the diameter of 20μm, spaced 0.5 mm apart from each other. The anode is a mylar foil which was evaporated by gold layer with the thickness of 50μg/cm~2 mounted on a printed plate in the shape of rectangle. the thickness of mylar foil is 1.5μm. The gap between anode and cathode is 3mm. The performance of the OCTPSAC has been tested by using a ~(252)Cf source in flowing isobutylene gas at the pressure of 3.4mb. The intrinsic time resolution of 289ps and position resolution of 2 mm have been obtained. In another type of OCTPSAC, the cathode is made of mylar foil, which is composed of gold strip by vacuume evaporation method with a special mask on the mylar foil. The thickness and the width of the gold strip is 50μg/cm~2 and 1.7mm. The strips are spaced 0.3 mm apart from each other. The anode is the same as the former type. We have obtained the time resolution of 296ps and position resolution of 2mm by using ~(241)Am-a source when the gas pressure is 6 mb and high voltage is 600V. The working gas is heptan

一台高分辨同位素鉴别望远镜

本文介绍了一套成功地用于深非弹激发函数测量实验的同位素鉴别探测系统，其中对反应产物质量数Ａ的鉴别采用的是飞行时间技术，对原子序数Ｚ的鉴别利用的是ΔＥ－Ｅ方法，飞行时间是通过两个ＰＰＡＣ来测量的，ΔＥ探测器为纵向电场气体电离室，Ｅ探测器为金硅面垒半导体探测器。测量结果得：ＰＰＡＣ的本征时间分辨δｔ约１４０ｐｓ，Ａ分辨Ａ／ΔＡ约５０和Ｚ分辨Ｚ／ΔＺ约３０。文中对作为定时探测器的ＰＰＡＣ作了较为详细的讨论

46．7MeV／u~（12）C轰击~（197）Au、~（115）In、~（58）

用气体电离室－半导体位置灵敏探测器望远镜测量了４６．７ＭｅＶ／ｕ（１２）Ｃ离子轰击（１９７）Ａｕ，（１１５）Ｉｎ，（５８）Ｎｉ靶时，在大角区发射的从Ｌｉ到Ｍｇ的复杂碎片能谱；由各碎片的能谱提取了蒸发源的温度和碎片发射的最可几动能Ｅｐ，并与＝Ｖｃｏｕｌ＋２Ｔ计算的平均动能进行了比较，发现实验上提取的最可几动能Ｅｐ总是低于计算的．用Ａ．Ｆｒｉｅｄｍａｎ简单的统计公式对复杂碎片的产额进行粗糙拟合，拟合结果令人满意

46.7MeV/u~(12)C引起的弹核碎裂反应

测量了46.7MeV/u~(12)C束流轰击不同靶核的核反应中前方向出射的类弹碎片,发现弹核碎裂产物的最可几能量可用Abrasion图象来解释。它们的平行动量分布宽度满足Goldhaber关系式,实验中提取的约化平行动量分布宽度σ_0=80±10MeV/c,接近于相对论情形下的值,并且σ_0对于不同的反应系统有相近的值

Electricity Generation in Microbial Fuel Cells Catalyzed by Mixed Culture and Pure Culture

利用淡水沉积物作为接种源构建了微生物燃料电池,考察苯酚对该微生物燃料电池性能的影响.结果表明,在淡水沉积物接种的微生物燃料电池中,电流的产生是由富集在电极表面的细菌引起的.苯酚降低了细菌消耗葡萄糖的速率,并在加入相同量葡萄糖的情况下,延长了产电时间.另一方面,实验还研究了一株从沉积物微生物燃料电池中分离出的单菌株的产电情况.该菌株在微生物燃料电池中需要借助自身代谢产生有电极反应活性的中间产物才能产电.GC-MS分析表明,中间产物中有吩嗪类物质,该类物质可在该细菌细胞与石墨电极之间充当电子传递介体,实现电子从细胞向电极的传递.Microbial fuel cells(MFCs) were constructed by inoculating fresh sedimentary microorganisms.Effect of phenol on performance of MFCs was investigated.The results showed that the generation of electrical current was induced by bacteria attached on the surface of the anode.Presence of phenol reduced the rate of glucose consumption and extended the duration of electricity generation with the same addition of glucose.In addition,the electricity generation by a single strain(belonging to pseudomonas species) separated from the sedimentary MFC was also investigated.The experimental results indicated that the presence of metabolic intermediates which exhibited electrochemical activity was necessary for the electricity production.Analysis of GC-MS showed that the metabolic intermediates included phenazine derivatives which can function as electron shuttles between the bacteria cells and the anode,realizing the electron transfer from the cells to the electrode.作者联系地址：扬州大学化学化工学院;Author's Address: Department of Chemistry and Chemical Engineering,Yangzhou University,Yangzhou 225002,Jiangsu,Chin

46.7MeV/u~(12)C引起的核反应中碎裂与转移的竞争

本文讨论了46.7MeV/u~(12)C引起的核反应中弹核碎裂与转移反应的共存及相互竞争,实验中提取的转移部分的约化平行动量分布宽度为44±10MeV/c,这比弹核碎裂部分的σ_0=80±10MeV/c要窄。弹核碎裂及转移反应发生的几率都与被转移结团的结构有关

~(19)F+~(51)V耗散反应中能量相干宽度的角度相关性

报道了102.25-109.25MeV~(19)F+~(51)V 耗散反应激发函数的振荡现象,用统计学方法分析了截面涨落的能量相干,振荡结构表现出很强的出射道相关性.能量相干宽度Γ随出射产物的原子序数和质量数而变化.讨论了双核系统的角速度阻尼与转动能耗散之间的关系.Excitation function fluctuations for projectile-like fragments from ~(19)F+~(51)V dissipative reaction within the energy region of 102.25—109.50MeV are reported.The statistical meth- od is applied to the analysis of energy coherence in the cross section fluctuations and the strong cross correlation between exit channels is obtained.The dependences on charge num- ber and on mass number are presented.The relation between angular velocity damping and the rotational energy dissipation is discussed.国家自然科学基金;; 中国科学院留学基金资助

~（19）F＋~（51）V耗散反应同位素类弹碎片的截面涨落

采用飞行时间（ＴＯＦ）加△Ｅ－Ｅ探测系统，在１０２．２５－１０９．５０ＭｅＶ（能量步长为２５０ｋｅＶ）的１９Ｔ＋５１Ｖ反应中，第一次给出了耗散碰撞同位素产物的激发函数，讨论了双核系统的能量相干宽度Γ与产物的质量数Ａ和Γ与产物的中子过剩自由度Ｎ／Ｚ的依赖关系。By using a detection system combining Time-of-Flight(TOF)method with(△E-E)technique,the excitation functions,the dependence of energy coherence widthΓon product mass A and the dependence of Γon the degree of freedom of neutron excess N/Z for some elements and their isotope products in the dissipative process of reaction 19F+51V at energies from 102.25MeV to 109.50 MeV(in 250 keV steps)were presented and discussed for the first time.国家自然科学基

46.7MeV/u~(12)C+~(58)Ni反应中的轻带电粒子关联测量

本文报道了在~(12)C(46.7 MeV/u)+~(58)Ni实验中利用9单元CsI(T1)阵列探测器测量轻带电粒子关联函数的实验结果,详细讨论了关联函数的定义及从实验上提取关联函数的方法。本文还讨论了非稳态粒子衰变在关联粒子测量中的表现,并给出了对于~(58)Ni靶得到的各种粒子组合的关联函数

~（19）F＋~（45）Sc深非弹反应产物的激发函数

测量了１０２ＭｅＶ到１０８ＭｅＶ（１９）Ｆ＋（４５）Ｓｃ反应在θ１＝２６°和θ１＝４２°的耗散部分产物的激发函数，能量步长３００ｋｅＶ，靶厚５３μｇ／ｃｍ２．用统计理论求得了各元素的能量相干宽度Γ，提取了反应的特征时间τ，探讨了耗散反应机制．Excitation functions have been measured for the dissipative reaction products at θl= 26° and θl= 42° in tEe 102 MeV to 108 MeV 19F8+ + 45Sc reactions by a step of 300 keV. The energy coherence widths and the dinuclear system lifetimes are extracted by analysing the cross section fluctuations. The dissipative reaction mechanisms are investigated.国家自然科学基