多击响应的三层阳极丝位置灵敏探测器及其信号重整

最新发展起来的三层延迟线阳极,即Hexanode与标准的螺旋状延迟线(HDL)阳极相比,对多击事件有较好的响应能力．它与一对微通道板组合在一起构成的位置灵敏探测器能够响应同时或短时间间隔内到达探测器的多个粒子,并给出粒子的全部动量信息．针对Hexanode在响应多个同时或短时间间隔内到达的粒子时出现的信号丢失问题,自行编写了一个信号重整程序．经过此程序的处理后,多击响应位置灵敏探测器的死时间只存在于两个粒子同时到达探测器的同一位置时(在一定时间及位置范围内)．在最近完成的使用Hexanode探测器的近阈值e+He→3e+He++中,获得了很好的结果．

并行设备总线电源控制系统设计

为实现CSRe试验环磁铁电源的控制同步,采用32位ARM内核芯片技术结合DSP控制板方式,稳定可靠地实现控制数据流的传输和同步事例的收发。同时通过CPLD逻辑时序编程来设计eVME背板总线系统。本系统用嵌入式网络和并行总线技术可靠稳定实现数据的快速获取与给定。

一些低能重离子物理实验时辐射场的中子、γ剂量分布

目的　测量低能重离子物理实验中靶和法拉第筒周围中子和γ辐射场的剂量分布。方法　利用1 2 C和2 0 Ne离子束轰击不同的金属薄靶 ,并测量中子和γ射线剂量。结果　辐射场中剂量当量率的主要贡献是中子 ,占 97%～99%,γ辐射仅占很少一部分。结论　进行此类实验时应同时考虑中子和γ射线的辐射防护 ,重点应放在中子防护上。

超重元素(新核素)合成研究进展情况分析和展望

本文在介绍和分析国际、国内在超重元素 (新核素 )合成实验研究与理论研究进展情况的基础上对我国今后如何从理论与实验的结合上开展超重元素 (核 )合成研究工作提出一些看法和建议 ,提供讨论

中能碳离子束对不同贯穿深度上黑色素瘤B16细胞的辐照存活效应

测量了 4 9.30MeV u及经脊形过滤器展宽的Bragg峰的 74 .55MeV u12 C离子束在不同贯穿深度上辐射后黑色素瘤B16细胞的存活率。结果显示 ,以存活为终点的B16细胞生物学效应与碳离子束能量沉积同步增大 ,即Bragg或展宽的Bragg峰区内细胞存活率远低于离子束入射或出射通道处的细胞存活率。通过实验测量与剂量平均LET结合的线性平方模型理论计算存活曲线的比较 ,发现在实验测量误差范围内两者符合较好。提示 :剂量平均LET结合线性平方模型可能是预测中能重离子束贯穿深度上B16细胞存活效应的一种有效的方法

高电荷态ECR离子源

综述了中国科学院近代物理研究所近几年来高电荷态ECR离子源的最新进展。

Half-Lives of Superheavy Nuclei in Z=113 Alpha Decay Chain

The generalized liquid drop model (GLDM), including the proximity effects and centrifugal potential, and the cluster model with Cosh potential are used to study the half-lives of some Z=113 isotopes and their alpha-decay products.The experimental half-lives of (284)113, (283)113, (282)113and their alpha-decay products are well reproduced by the two models when zero angular momenta transfer is assumed. For (278)113 and its alpha-decay products, both the GLDM andthe cluster model could provide satisfactory results if we assume the alpha particle carry five units of angular momenta, which indicates that possible non zero angular momenta transfer and need further experimental measurements with high precision. Finally, we show that half-lives of alpha-decay are quite sensitive to the angular momentum transfers, and a formula could be used to describe the correlation between alpha-decay half-life and angular momentum transfer successfully.

Restoration of the signals from multi-hit three-layer delay-line anode position-sensitive detector

Multi-hit 3-layer delay-line anode (Hexanode) has an increased ability to detect multi-hit events in a collision experiment. Coupled with a pair of micro-channel plates, it can provide position information of the particles even if the particles arrive at the same time or within small time dwell. But it suffers from some ambiguous outputs and signal losses due to timing order and triggering thresholds etc. We have developed a signal reconstruction program to correct those events. After the program correction, the dead time only exists when 2 paxticles arrive at the same time and the same position within a much smaller range. With the combination of Hexanode and the program, the experimental efficiencies will be greatly improved in near threshold double ionization on He collisions.

Radio-resistance induced by nitric oxide to heavy ion irradiation in A172 human glioma cells

To investigate effects of nitric oxide on cellular radio-sensitivity, three human glioma cell lines, i.e. A172, A172 transfected green fluorescence protein (EGFP) gene (EA172) and A172 transfected inducible nitric oxide synthesis (iNOS) gene (iA72), were irradiated by C-12(6+) ions to 0, 1 or My. Productions of nitric oxide and glutathione (GSH) in A172, EA172 and iA172 were determined by chemical methods, cell cycle was analyzed by flow cytometry at the 24th hour after irradiation, and survival fraction of the cells was measured by colorimetric MTT assay at the 5th day after irradiation. The results showed that the concentrations of nitric oxide and GSH in iA172 were significantly higher than in A172 and EA172; the G(2)/M stage arrest induced by the C-12(6+) ion irradiation was observed in A172 and EA172 but not in iA172 at the 24th hour after exposure; and the survival fraction of iA172 was higher than that of EA172 and iA172. Data suggest that the radio-sensitivity of the A172 was reduced after the iNOS gene transfection. The increase of GSH production and the change of cellular signals such as the cell cycle control induced by nitric oxide may be involved in this radio-resistance.

稠油降解菌的筛选及其生物表面活性剂的特性

添加稠油对土壤中土著微生物进行驯化,分离出33株能以稠油为惟一碳源生长的细菌,从中筛选出2株高效表面活性剂产生菌XJ1和SJ4,9株高效稠油降解菌.XJ1和SJ4可将发酵液的表面张力由72.4mN/m分别降到36.1mN/m和36.2mN/m;14d摇瓶油降解率分别为35.89%和31.59%,降解效率在各单菌中最高.同时研究了发酵液中XJ1和SJ4的生长量与其生物表面活性剂产生情况之间的关系,经红外光谱分析初步确定两种生物表面活性剂均为糖脂类化合物.

春小麦田喷灌的水量分布及小气候效应

春小麦喷灌的田间观测表明 ,在灌浆初期 ,春小麦冠层的截留水量可达 2 5 %～ 30 % ,冠层截留水量可使冠层下方的均匀系数比冠层上方提高 10 .1%～ 12 .7% .喷灌的水分飘移蒸发损失可达总水量的 2 0 %～ 2 5 % .春小麦喷灌可以降低空气和土壤温度 ,增加空气实际水汽压和相对湿度 ,这对抑制作物蒸腾将起一定作用 .