HIRFL浅层肿瘤治疗终端治癌碳离子束物理特性的测量

对HIRFL浅层肿瘤治疗终端提供的碳离子束的物理特性进行了首次测量．结果显示,能量为80．55MeV/u的~(12)C离子束,其束流强度在0．001—0．1nA范围时,直径50mm照射野的均匀性为73．48%,束流强度在一段时间内的稳定性为80．87%．测得了束流在治疗装置等中心处的深度剂量分布,其高剂量的Bragg峰位处在13．866mm的水等效深度,反推出碳离子束在等中心处对应的能量为71．71MeV/u,与计算值基本吻合．对自由空气电离室的读数进行了吸收剂量的标定．测量结果显示,HIRFL浅层肿瘤治疗装置性能与临床治疗的要求相比稍有差距,为了达到治疗终端进行临床试验的要求,须对治癌装置性能做进一步的优化．

Evaluation of the thermal/optical reflectance method for discrimination between char- and soot-EC

IEECAS SKLLQG

Impact of monsoonal climatic change on Holocene overbank flooding along Sushui River；middle reach of the Yellow River；China

IEECAS SKLLQG

Characteristics of indoor/outdoor PM2.5 and elemental components in generic urban；roadside and industrial plant areas of Guangzhou City；China

IEECAS SKLLQG

Carbonaceous aerosols in PM10 and pollution gases in winter in Beijing

IEECAS SKLLQG

大N近似下玻色-爱因斯坦凝聚体中单个涡旋态的解

给出了大N近似下轴对称、扁椭球状玻色 爱因斯坦凝聚体在轴对称各向异性谐振子势阱中单个涡旋态的一个近似解析波函数 ,并利用能量泛函变分的方法确定了待定参数C与凝聚体总粒子数N和凝聚体形状因子λ的关系 .C随N(或λ)的变化非常缓慢 ,在N和λ很大时 ,C趋于稳定值 0 32 1 6 4 6 .

The Holocene Asian monsoon: Links to solar changes and North Atlantic climate

IEECAS SKLLQG

~(130)Ce(EC+β~+)衰变研究及其放射化学分离

利用兰州SFC加速的16O束轰击同位素118Sn ,由熔合蒸发 4n反应产生目标核13 0 Ce。为了消除本底干扰并指定13 0 Ce核 ,采用溶剂萃取法对He - jet带传输系统从靶室传输出来的反应产物进行了离线分离与纯化。将目标核13 0 Ce从大量的靶材料、反应产物及母核中分离出来 ,快速制成薄源后在铅室中进行γ单谱测量及X -γ、γ -γ符合测量。从化学分离后的产物中观察到了半衰期为 2 2 .9min的 10 8条γ射线 ,其中 10 7条是新发现的 ,该活性被指定为13 0 Ce。在此基础上 ,进一步研究这些γ线的级联关系 ,建立了缺中子同位素13 0 Ce较完整的 (EC + β+ )衰变纲图。为118Sn(16O ,4n) 13 0 Ce反应体系建立的放化分离流程的分离时间仅 10min ,化学产额大于70 %。化学分离除去 98%以上的核反应生成的13 0 La ,对其它杂质的去污完全满足13 0 Ce(EC + β+ )衰变研究的要求。

Micro Insert: A Prototype Full-Ring PET Device for Improving the Image Resolution of a Small-Animal PET Scanner

A full-ring PET insert device should be able to enhance the image resolution of existing small-animal PET scanners. Methods: The device consists of 18 high-resolution PET detectors in a cylindric enclosure. Each detector contains a cerium-doped lutetium oxyorthosilicate array (12 x 12 crystals, 0.72 x 1.51 x 3.75 mm each) coupled to a position-sensitive photomultiplier tube via an optical fiber bundle made of 8 x 16 square multiclad fibers. Signals from the insert detectors are connected to the scanner through the electronics of the disabled first ring of detectors, which permits coincidence detection between the 2 systems. Energy resolution of a detector was measured using a Ge-68 point source, and a calibrated 68Ge point source stepped across the axial field of view (FOV) provided the sensitivity profile of the system. A Na-22 point source imaged at different offsets from the center characterized the in-plane resolution of the insert system. Imaging was then performed with a Derenzo phantom filled with 19.5 MBq of F-18-fluoride and imaged for 2 h; a 24.3-g mouse injected with 129.5 MBq of F-18-fluoride and imaged in 5 bed positions at 3.5 h after injection; and a 22.8-g mouse injected with 14.3 MBq of F-18-FDG and imaged for 2 h with electrocardiogram gating. Results: The energy resolution of a typical detector module at 511 keV is 19.0% +/- 3.1 %. The peak sensitivity of the system is approximately 2.67%. The image resolution of the system ranges from 1.0- to 1.8-mm full width at half maximum near the center of the FOV, depending on the type of coincidence events used for image reconstruction. Derenzo phantom and mouse bone images showed significant improvement in transaxial image resolution using the insert device. Mouse heart images demonstrated the gated imaging capability of the device. Conclusion: We have built a prototype full-ring insert device for a small-animal PET scanner to provide higher-resolution PET images within a reduced imaging FOV. Development of additional correction techniques are needed to achieve quantitative imaging with such an insert.

Promotion of cooperation in the form C0C1D classified by 'degree grads' in a scale-free network

In this paper, we revisit the issue of the public goods game (PGG) on a heterogeneous graph. By introducing a new effective topology parameter, 'degree grads' phi, we clearly classify the agents into three kinds, namely, C-0, C-1, and D. The mechanism for the heterogeneous topology promoting cooperation is discussed in detail from the perspective of C0C1D, which reflects the fact that the unreasoning imitation behaviour of C-1 agents, who are 'cheated' by the well-paid C-0 agents inhabiting special positions, stabilizes the formation of the cooperation community. The analytical and simulation results for certain parameters are found to coincide well with each other. The C0C1D case provides a picture of the actual behaviours in real society and thus is potentially of interest.