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<正>B-particle organization Many measurements of 8 decays involve admixtures of B hadrons.Previously we arbitrarily included such admixtures in the B~±section,but because of their importance we have created two new sections:B~±/B~0 Admixture"for T(4S)results and"B~±/B~0/B_(s~0)/b-baryon Admixture"for results at higher energies.Most inclusive decay branching fractions and x_b at high energy are found in the Admixture sections.B~0-B~0mixing data are found in the 6°section,while B_(s~0)-B_(S~0)mixing data and B-B mixing data for a B~0/B_(s~0)admixture are found in the B_(s~0)section.CP-violation data are found in the B~±,S~0,and B~±B~0 Admixture sections.b-baryons are found near the end of the Baryon section.Recently,we also created a new section:"V_(cb)and  相似文献   

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<正>Ω~-I(J~P)=0(3/2~+)Status:****The unambiguous discovery in both production and decay was by BARNES 64.The quantum numbers follow from the assignment of the particle to the baryon decuplet.DEUTSCHMANN 78 and BAUBILLIER 78 rule out J=1/2 and find consistency with J=3/2.AUBERT.BE 06 finds from the decay angular distributions ofΞ_c~0→Ω~-K~+andΩ_(c~0)→Ω~-K~+that J=3/2;this depends on the spins of theΞ_c~0 andΩ_c~0 being J=1/2,their supposed values.We have omitted some results that have been superseded by later experiments.See our earlier editions.  相似文献   

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近几年来,低b超导腔(例如spoke型,re-entrant 型,CH型)作为质子或者离子在中低能段的加速结构成为研究的热点.许多实验结果表明spoke腔在低能段是很好的选择,在中能段跟椭球腔相比也很具有竞争实力,为此,北京大学开展了β=0.45,频率为350MHz的spoke型质子超导加速腔研究. 本文详细阐述了这种腔的结构及电磁场的设计,从射频参数Q,r/Q,最大表面电磁场和加速效率的计算结果来看,它具有很好的加速性能.  相似文献   

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Using data on coherent production of π+π+π- systems in π+ collisions with nuclei we exclude the existence ofJ PC=1?+,I=1, exotic hybrid mesons with masses below 1.5 GeV and widths greater than 20 MeV, provided that their primary coupling is to πρ systems. Hybrid states with just such properties have recently been predicted from arguments based on QCD sum rules. Our experimental limit is based on Primakoff production of these states, and on an argument using vector dominance to relate their radiative widths to πρ channels. There has been increasing interest of late in the existence of hybrid states, which, in the case of mesons, contain a valence gluon in addition to aq \(\bar q\) pair in a color-octet state [1–5]. The pursuit of spectroscopic gluon degrees of freedom has been strongly motivated by the general QCD picture of hadrons, as well as by many specific calculations based on QCD sum rules, lattice simulations, and more phenomenological approaches such as QCD-bag models. Although much effort, both thoretical and experimental, has been devoted to the spectroscopy of glueballs, for which several candidates exist [6], it has also been realized that hybrid states may be as amenable to discovery, and perhaps less ambiguous to interpretation.  相似文献   

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Recently intensive studies have been done on superconducting cavities (e.g. spoke cavity, reentrant cavity, and ch cavity), which are used as accelerating structures in the low and medium energy part of high power high intensity proton or ion accelerators. many experiments have shown that spoke cavity is a good candidate for low energy part. it is also promising to be used for the medium β area. so a β=0.45 spoke cavity is being studied at Peking university. in this paper, the structural and electromagnetic design of a β=0.45, f=350mhz spoke cavity is reported in detail. the calculated rf parameters (e.g. Q, r/Q, peak surface fields and dissipated power) indict a potential of good acceleration.  相似文献   

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本文提供了一种测定金属硅中B,Fe,Al,Ca,Mn等14个杂质元素的ICP-AES方法,在样品处理过程中,加入适量体积的甘露醇能够抑制B的挥发。用本方法测定了一个国家地球化学标准样(GSR-4),结果令人满意。  相似文献   

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本文研究了贵金属标准溶液除氯离子的有关问题,解决了高纯硝酸银中贵金属等杂质元素的标样配制,以硝酸银直接压样于普通电极中直流电弧激发,可测定99.0~99.99%的高纯银,该方法简便、快速、准确。  相似文献   

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纯硒中杂质元素的ICP-AES测定   总被引:1,自引:0,他引:1  
电感耦合等离子体-原子发射光谱同时测定纯硒中的碲、铅、铋、锑、铜、铁、镍、铝、锡、砷和硼12种元素的含量,优化出各元素的分析波长和分析条件;用基体匹配补偿基体效应,方法简单,快速可靠,样品回收率为94%-107%.  相似文献   

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以电荷耦合器件为检测器的全谱直读等离子体光谱仪直接测定锡锭中As、Al、Bi、Cd、Cu、Fe、Pb、Se、Sb、Zn十种杂质元素的含量.该方法简便、快速且具有比化学法更低的检出限,加标回收试验结果表明,回收率为92%-105%,RSD均小于1.5%.  相似文献   

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Brudnyi  V. N. 《Russian Physics Journal》2017,59(12):2186-2190
Russian Physics Journal - On the basis of the charge neutrality concept, the analysis is fulfilled of the experimental data on the electron properties of the defective semiconductors after the...  相似文献   

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The lowest absorption band of the tetraphenyl compounds resembles that of the lowest absorption band of benzene with the following difference. In benzene the electronic origin is strictly forbidden, and all intensity is associated with a symmetric progression built on one mode of asymmetric vibration. In the tetraphenyl compounds the intensity associated with the asymmetric vibration is relatively unaffected; however, there is increasing intensity associated with the electronic origin and a symmetric progression built on it along the series
φ4Pb < φ4Sn < φ4Ge < φ4Si < φ4C ? φ4B? < φ4Sb+ < φ4As+ < φ4P+
. For the cations it is the electronic origin and the progression built on it that are the primary source of intensity. This effect is attributed to an inductive perturbation. A similar effect is observed in the fluorescence spectrum. In phosphorescence, the relative enhancement of the electronic origin and the progression built on it is far less marked. The phosphorescence emission of φ4Pb and φ4Sb+ are red shifted from the others by ~0.5 eV, an effect attributed to formation of a triplet excimer. Increasing spin-orbit coupling in the triplet due to a heavy atom effect can be seen in the decreasing phosphorescence lifetime (range 4 sec to 4 msec) and decreasing ratio of φfφp (fluorescence to phosphorescence quantum yields) in the order
φ4C > φ4B > φ4Si > φ4P+ > φ4Ge > φ4As+ > φ4Sn
In all cases nonexponential decay of phosphorescence is observed.  相似文献   

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ICP—AES法直接测定锡锭中的As,A1,Bi,Cd,Cu,Fe,Pb,Se,Sb,Zn   总被引:4,自引:0,他引:4  
以电荷耦合器件为检测器的全谱直读等离子体光谱仪直接测定锡锭中As、A1、Bi、Cd、Cu、Fed、Pb、Se、Sb、Zn十种杂质元素的含量。该方法简便、快速且具有比化学法更低的检出限,加标回收试验结果不明,回收率为92%-105%,RSD均小于1.5%。  相似文献   

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梁亚群 《光谱实验室》1998,15(5):101-104
本文介绍了电感耦合等离子体发射光谱法(ICP-AES)测定高纯铼酸铵中12个杂质元素的方法。采用挥发健康基体,探讨了高铼酸铵基体的干扰及其消除办法。ICP-AES测定结果的准确度和精密度均能满足分析要求。  相似文献   

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