First observation of the decay B --> J/psistraight phiK

We present the first observation of the decay B-->J/psistraight phiK. Using 9.6x10(6) B&Bmacr; meson pairs collected with the CLEO detector, we have observed ten fully reconstructed B-->J/psistraight phiK candidates, whereas the estimated background is 0.5+/-0.2 event. We obtain a branching fraction of B(B-->J/psistraight phiK) = (8. 8(+3.5)(-3.0)[stat]+/-1.3[syst])x10(-5). This is the first observed B meson decay requiring the creation of an additional s&smacr; quark pair.     

Measurement of excitation functions in the reactions 197Au(11C, xn)208-xAt using a radioactive 11C beam

A light-element radioactive ion-beam capability has been developed at the LBNL 88-Inch Cyclotron. The system is based on the coupled-cyclotrons method and utilizes short-lived species, e.g., 11C, 14O, 13N produced by (p,n) and (p,alpha) reactions at the LBNL Biomedical Isotope Facility Cyclotron. In a first experiment, 197Au(11C,xn)208-xAt excitation functions have been measured for energies ranging from the Coulomb barrier up to 110 MeV using a beam of 11C with intensities up to (1-2)x10(8) ions/sec on target. The results of this experiment are compared to measurements of 197Au(12C, xn)209-xAt excitation functions.     

Coherent dynamics of the localized vibrational modes of hydrogen in CaF2

We report the observation of giant quantum coherence effects in the localized modes of ionized hydrogen in synthetic fluorite. Infrared free induction decay experiments on the substitutional H- center show dramatic modulations at negative delay times due to interference between multiple vibrational levels. Spectrally resolving the degenerate four wave mixing signal allows unambiguous assignments of the participating vibrational states. The dependence of the signal intensity upon the delay path between the exciting free electron laser pulses can be accounted for in terms of the resonant third order polarization with a common dephasing time for the excited states.     

Spatial mode control of a diode-pumped Nd:YAG laser by use of an intracavity holographic phase plate

We present a new method of realizing phase plates by phase-volume holography on a photopolymer film. We implement such a component in a diode-pumped Nd:YAG oscillator to control the output spatial beam profile. Flattop super-Gaussian and square-shaped beams are obtained.     

Co-Ni-Sr-O系低温热敏陶瓷材料研究

着重研究了工作温度范围为20~77K的低温热敏电阻器的生产工艺参数。利用先进的半导体陶瓷工艺,合成了新的低温NTC热敏陶瓷材料SrCoO3-δ,并用不同量的Ni取代Co对其掺杂改性,得到了不同阻值、不同B值的陶瓷材料,同时研究了烧结温度和恒温时间对Co-Ni-Sr-O系NTC热敏材料参数的影响。在材料粉体合成中,采用固相烧结、共沉淀法、溶胶凝胶法、Pechini法等不同方法制备,讨论了不同方法的基本原理与特点,并对一些具体制备方法进行了比较。     

越级搭配 加倍惊喜

前段时间，重庆的资深发烧友Zmalan出人意料的用1．4万元的“音乐之旅”推3900多元的AE200音箱，两者之间的身价相差不可谓不悬殊了，“严重”违反了一般发烧友心目中“音箱要比功放贵”的搭配准则。那么，搭配的效果又是怎样的呢？Zmalan在他的帖子里是这样描述的：“也许许多朋友觉得如果用ECI-3来搭配四千元的AE200有些夸张或者比例失衡……     

让电脑来写信封

您是否经常给朋友写信，写完信，选一个漂亮的信封，写上您特有的一手漂亮字，寄去你的祝福。如果把这一切重复几千遍变为您一天的工作，您还有此雅兴吗？笔者现在正从事杂志的发行工作，其中经常要处理读者订阅杂志的邮寄工作。手写信封较适合零星的工作，如果哪天，主编要求你一天给数据库中的２０００位读者各寄一份杂志，你是否会呆坐在那儿，不知如何应付？打开数据库？开始抄？不要吧，教你一招，用Ｗｏｒｄ轻松制作标签，一天搞定。只要您有一台电脑，又有现成的数据库，那就好办了，下面就可以开始教您做邮件标签：第一步：在Ｗｏｒ…     

N235—混合醇萃取分离稀土中的铁和铅

随着稀土在荧光和激光材料等领域的应用,对稀土纯度的要求越来越高,尤其是对非稀土杂质的含量要求越来越低。对稀土中非稀土杂质的分离去除,已有许多研究报导[1-3]。多是利用萃取剂对稀土和非稀土杂质的萃取能力不同而达到去除目的。分离因素较小,萃取级数都在20多级以上?..     

推动直流微电机的可编程驱动电路

图1所示电路是用LM723巧妙配置而成的、用来驱动微电机的可编程电源,它简单小巧,价格低廉。因为采用微处理器进行精确定位和控制,这些微电机可以用于光学安装、灵活的轴控制等应用场合,与步进电机相比具有速度高和伺服控制响应快的优点。这些微电机都需要一个稳定的可编程直流电压源。 LM723是一个可调线性调压器,但在用于驱动微电机时,将LM723配置成一个可编程电压源。