窄条选区外延技术研制AlGaInAs MQW DFB BH 激光器

Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-04-13T11:45:31Z

新核素~(263)Hs,~(260)Bh及其α衰变链上核素的半衰期

运用推广的液滴模型(GLDM)并结合量子力学中的WKB方法计算了新核素~(263)Hs和~(260)Bh及其α衰变链上各核素的势垒贯穿概率,对该链上各原子核的α衰变半衰期进行了研究。计算结果表明:利用推广的液滴模型结合WKB方法计算出的α衰变半衰期可以很好地符合在超重核区的实验值,验证了推广的液滴模型在超重核区的适用性,能够很好地描述超重核的α衰变。同时,计算表明新核素~(260)Bh和~(263)Hs的合成及其半衰期的测量是可靠的。

~(266)Bh的α衰变性质研究(英文)

报道了利用兰州重离子研究装置提供的26Mg重离子束流轰击243Am靶产生和鉴别已知超重核素266Bh的实验结果。利用转轮收集探测装置依靠母子核遗传关系通过观测Bh同位素与其子核Db和Lr之间的α-α关联事件来鉴别266Bh。实验中观测到266Bh的α能量为(9.03±0.08)MeV,与日本理化学研究所在合成113号元素中第一个衰变链中观测到266Bh的α能量为9.07 MeV相近。266Bh的半衰期为0.66+-00..5269s,从实验得到的Qα也符合Z=107的Qα随中子数变化的系统性。

新核素~(265)Bh及其α衰变链上核的基态性质

运用变形的相对论平均场理论系统地探讨了新核素265Bh及其α衰变链的基态性质.对关联的处理采用了BCS方法,不成对核子的处理运用了“阻塞”法后,所计算的结合能和四极形变符合了有限力程小液滴模型的结果,计算表明研究的α衰变链具有中等大小的长椭球形变;且计算的α衰变能Qα成功地与实验符合.在此基础上进一步研究了新核素265Bh的单粒子能级.

利用α关联衰变链鉴别新同位素_(107)~(265)Bh

主要介绍了合成和鉴别107号元素的新同位素265Bh的实验装置、实验方法以及实验结果.目标核265Bh是由能量为135MeV的26Mg离子轰击243Am靶,通过融合蒸发反应而产生.反应产物首先由He jet系统传输到装有数个探测器对的转轮收集测量系统,然后依靠母子核遗传关系通过观察新同位素和它们已知子核261Db和257Lr之间的α衰变的关联,来实现对新核素的鉴别.实验测得265Bh的α衰变能量为(9.24±0.05)MeV, 半衰期为0.94+0.70-0.31s.从该实验得出的265Bh的α衰变能量和半寿命能够与理论预言一致.

新同位素~(265)Bh(Z=107)的合成证据

利用兰州重离子加速器提供的26Mg离子束轰击243Am靶, 产生了新同位素265Bh. 实验中用氦喷技术对产物进行传输, 并用一套具有数对探测器组的转轮收集探测系统对产物进行收集和测量. 通过观测265Bh与它的衰变子核261Db及257Lr之间的α衰变的关联, 实现了对新核素的鉴别. 实验测得265Bh的α衰变能量为(9. 24±0. 05)MeV, 半衰期为 0. 94+0. 70 0. 31 s.

~(265)Bh(Z=107)同位素的首次观测

在兰州的重离子加速器上用 2 6Mg离子束轰击 2 43 Am靶 ,产生了新同位素 2 65Bh .通过观测新同位素 2 65Bh和它的已知子核 2 61Db和 2 57Lr之间的α衰变的关联 ,实现了对新核素的鉴别 .实验中使用了一套新建立的具有数个探测器对的转轮收集探测系统 .将该系统用于特殊的母 -子核搜索模式 ,从而大大减少了本底 .共测得了 8个 2 65Bh的α衰变关联事件 ;同时 4个已知核 2 64Bh的衰变关联事件也被鉴别出来 .实验测得 2 65Bh的α衰变能量为 (9.2 4± 0 .0 5 )MeV ,半衰期为 0 .94 + 0 .70-0 .3 1s .

关于合成~(265)Bh实验的可行性分析

分析了目前关于超重核研究的现状,结合现有的设备及条件,在合成259Db以后,下一次实验的目标核初步确定为107号元素的新同位素265Bh.描述了对MG转轮收集探测系统的实验检验结果.实验中成功地观察和测量了24Mg+232Th的产物252No的母子体的α衰变谱,为下一步合成265Bh完成了部分预实验工作.另外,也给出了下一个目标核的衰变特性的理论预言值,同时也选择了产生该目标核的弹靶组合及反应道,并对生成截面进行了粗略估计,给出了该核的可观测性产额及可行性分析.

Theoretical study on properties of new isotope (265)Bh

The properties of nuclei belonging to the newly observed a-decay chain starting from (265)Bh have been studied. The axially deformed relativistic mean-field calculation with the force NL-Z2 has been performed in the blocked BCS approximation. Some ground state properties such as binding energies, deformations, spins, and parities, as well as Q-values of the alpha-decay for this decay chain have been calculated and compared with known experimental data. Good agreement is found. The single-particle spectrum of the nucleus (265)Bh is studied and some new magic numbers are found, while the magnitudes of the shell gaps in superheavy nuclei are much smaller than those of nuclei before the actinium region, and the Fermi surfaces are close to the continuum. Thus the superheavy nuclei are usually not stable. The alpha-decay lifetimes in the (265)Bh decay chain are evaluated by different formulae, and compared with experimental data. The methods which give good agreement with the data are selected.

The aesthetics of he eyes and mouth position in a three-point face schema

Oculographical research of people watching a human face indicates than beholder's eyes stop most often and for the longest period of time on the eyes and the mouth of the face looked at and that they move among these three points most frequently. The position of the eyes and mouth in relation to one another can be described with a single number being a measure of an angle with the vertex in the middle of the mouth and with arms crossing the centers of the eye pupils. The angles were measured from photographs of people from all over the world, as well as of residents of Lublin. Subsequently, the subjects from Lublin were asked to make face schemas by positioning the eyes and the mouth in the way they considered most attractive. The eye-mouth-eye angle of these schemas was measured. Additionally, measurements of the same angle were taken from the faces depicted in icons. The schemas of the most attractive - according to the subjects - faces were characterized by angles approximating the mean angle from the photographs, and significantly greater than the mean angle from the icons.

Locating the transnational: representations and aesthetics of the city in contemporary European cinemas

This thesis focuses on two Western European cinematic cities, and two unique periods of their respective nations’ histories, in a bid to “locate” the transnational within a contemporary European milieu. I argue that my geo-cinematic case studies are emblematic of broader questions of the problematics of national identity in contemporary Europe in the face of cross-national flows yet, as a result of their representations as cities both “anchored” and “in flux”, they reject a European postnational identity. Through its engagement with cinematic Rome as the “Eternal City” of Europe and cinematic Dublin as the “newly Europeanised” city, my thesis traces how representations and aesthetics of the urban spaces of these two cities correspond with the tensions at the heart of the respective eras in question. Via the figures that inhabit it, navigate it and search for it, the city is utilised to highlight fixity and mobility, centrality and dislocation, in explicit and implicit ways, amid the rapidly changing landscape of its national terrain. It is through my analyses of the filmed places and sociopolitical, socioeconomic and sociocultural spaces of these capital cities under the rubric of the transnational that this research demonstrates the “pluralities” of the construct in its cinematic manifestations. It is also my aim to evaluate the concept of cinematic transnationalism when identifying and accounting for representations of a specific national, historical timeframe, when the momentousness of the changes that occur is not bound by the national, but rather is reflective of the influence of both domestic and external forces. To this end, my thesis draws attention to instances in which the nation is shown to persist and resist dilution, arguing that it is only against the backdrop and continuity of the nation (in its evershifting guises) that the transnational can be conceived in representative and aesthetic terms.