Aqueous shift reagents for high-resolution cationic nuclear magnetic resonance. III. Dy(TTHA)3−, Tm(TTHA)3−, and Tm(PPP)27−

The isotropic hyperfine shifts induced in the ²³Na⁺ resonance by the shift reagents Dy(DPA)₃³⁻, Dy(NTA)₂³⁻, Dy(PPP)₂⁷⁻, Tm(PPP)₂⁷⁻, Dy(TTHA)³⁻, and Tm(TTHA)³⁻ are compared under similar conditions. The last three are introduced as shift reagents in this study. The Dy(PPP)₃⁷⁻ and Tm(PPP)₂⁷⁻ ions cause the largest shifts. However, these shifts are very pH dependent and are readily decreased by the presence of Ca²⁺ or Mg²⁺ ions. The Dy(TTHA)³⁻ and Tm(TTHA)³⁻ ions produce quite large shifts which are independent of pH (between 5.5 and 12) and less sensitive to Ca²⁺ and Mg²⁺. For a given chelate ligand, the analogous Dy(III) and Tm(III) complexes cause hyperfine shifts in opposite directions. However, while the Dy(PPP)₂⁷⁻ ion induces an upfield shift, the Dy(TTHA)³⁻ ion induces a downfield shift. Some data on shifts of the ²⁵Mg²⁺, ³⁹K⁺, and ⁸⁷Rb⁺ resonances are also presented. In addition the ¹⁴N peak of NH₄⁺ can be quite effectively shifted.     

Deeply bound pionic states with the (Σ −,Λ) reaction

We study the reaction ^– +A + (A ^–) with the ^– bound in the nucleus, as a means of producing deeply bound pionic states in nuclei, so far unobserved. The reaction is similar to the (n, p) reaction but, because of the ^–, mass difference, it allows the reaction to occur with smaller momentum transfer, thus increasing the transition probability and reducing the effects of distortion. The ratios of signal to background are one to two orders of magnitude better than in the (n, p) reaction.We would like to thank C. Dover and G. Tamas who helped us to get a perspective of the present and future possibilities of this and other reactions.One of us, J. Nieves wishes to acknowledge a fellowship from the Ministerio de Educatión y Ciencia. This work is partially supported by the CICYT. All the calculations have been done in the Centro Informático de la Universidad de Valencia.     

~(14)N~(16)O分子X~2Π_(3/2)R(1.5)v=0→1及~(15)N~(16)O分子X~2Π_(3/2)Q(1.5)v=0→1跃迁的FLMR光谱

本文采用法拉弟效应的激光磁共振光谱技术，研究了－氧化氮分子１４Ｎ１６ＯＸ２Π３／２Ｒ（１．５）ｖ＝０→１和同位素分子１５Ｎ１６ＯＸ２Π３／２Ｑ（１．５）ｖ＝０→１跃迁的ＦＬＭＲ光谱，实验给出了样品浓度和信号强度之间的关系及调制磁场强度与ＦＬＭＲ信号强度之间的关系。     

红外中性滤光法(1.8μ—2.5μ和0.7μ—22.5μ)

在红外跟踪,制导等光电子仪器的研制过程中,红外信号的强弱直接影响着跟踪距离和精度,为了取得可靠数据,必须作相应信号的模拟试验,这就需要采用不同透过率和不同光谱范围的中性滤光片。目前我国用量较大的是1.8μ至2.5μ光谱范围的中性滤光片。可见光到1.8μ的中性滤光片已有资料参考,但从可见光到2.5μ的还没见到报导。下面介绍我们镀制1.8μ至2.5μ和O.7μ至2.5μ中性滤光片的情况。     

Production ofρ +, −, 0 (770),η(550), ω(783) andf 2(1270) mesons in\bar v neon and ν neon charged current interactions

The production of the meson resonances ?(770) (all three charge states), η(550), ω(783) andf ₂(1270) in \(\bar v\) Ne and ν Ne charged current interactions is investigated in a bubble chamber experiment with BEBC at CERN. Except for thef ₂, the main features of resonance production are reasonably well described by the Lund model, although the average resonance multiplicities are overestimated by the model by (67±30)%. The average multiplicities of all resonances, including thef ₂, are well reproduced by a semiempirical model, whose parameters were determined from hadron interaction data.     

对10~(14)—10~(16)eV能区宇宙线多μ现象的分析

在不同成分初级宇宙线入射的情况下,用强子相互作用的Scaling模型加上大横动量喷注产生机制来模拟宇宙线多μ现象.结果表明,重核对于深层地下多μ事例中μ子多重数高的事例有明显的贡献.但在重核为主的假设下,产生的事例数仍小于实验值,预示多μ事例还有其他来源.多μ事例的横向分布与实验基本一致.     

Measurement of the average polarization of12B in the polarized-muon capture reaction12C(μ −,v μ)12B (g.s.)

The average polarization P_av of the recoil nucleus¹²B (ground state) produced by the polarized-muon capture reaction¹²C(^–,v )¹²B was measured by a new approach which involved the muon spin resonance, and the adoption of Grafoil as a carbon target where the polarization of¹² B can be preserved completely under 3 kG holding field. Our observed resultP _av=0.473±0.053 yields g_p/g_A=9.6 _–2.7 ^2.4 which seems to be consistent with the canonical PCAC prediction within the error.The authors would like to express their sincere thanks to the members of the Meson Science Laboratory and of the Van de Graaff Accerelator at Osaka University. They also acknowledge helpful discussions and suggestions given by Professors M. Morita, H. Ohtsubo and K. Kubodera. This work is supported by the Grant-in-Aid of the Ministry of Education, Science and Culture.     

The study of hypernuclei via the (K−, π0) reaction

A significant improvement in the resolution of hypernuclear levels could be attained by studying the (K^–, ⁰) reaction at rest. The new LAMPF neutral meson spectrometer can attain a ⁰ energy resolution of 200 keV. It is shown that, even today, an experiment is feasible and would shed significant light on our understanding of hypernuclei.     

Nondiagonal radiative (v i v jγ) interactions in an external field

Radiative v_j v_i and v_lv_j transitions of massive Dirac neutrinos are studied in the field of a linearly polarized wave and in a constant crossed field within the framework of an invariant procedure being developed for calculations in plane-wave-type fields. It is shown that with the upper bound used for the anomalous magnetic moment of the neutrinos, consideration of the external field may be decisive in the case of the v_j v_i (m_j>m_i) photodecay, with possible nontrivial consequences in the astrophysical aspect.Moscow State Open Pedagogical Institute. Translated from Izvestiya Vysshikh Zavedenii, Fizika, No. 7, pp. 11–17, July, 1994.     

关于介分子离子(αp,μ~-)和(αp,2μ~-)

应用ACQM理论和方法研究介分子离子(αp,μ~-)和(αp,2μ~-).发现(αp,μ~-)的基态(X~2Σ~+)为排斥态;(αp,2μ~-)为束缚态,平衡核间距R_e=0.0078bohr,能量极小值E=-551.78a.u.     

Measurement of the forward-backward asymmetry in the B→K*μ(+)μ(-) decay and first observation of the B(s)0→ϕμ(+)μ(-) decay

We reconstruct the rare decays B(+)→K(+)μ(+0μ(-0, B90)→K*(892)(0)μ(+)μ(-), and B(s)(0)→?(1020)μ(+)μ(-) in a data sample corresponding to 4.4 fb(-1) collected in pp collisions at √[s]=1.96 TeV by the CDF II detector at the Tevatron Collider. Using 121±16 B(+)→K(+)μ(+)μ(-) and 101±12 B(0)→K(*0)μ(+)μ(-) decays we report the branching ratios. In addition, we report the differential branching ratio and the muon forward-backward asymmetry in the B(+) and B(0) decay modes, and the K(*0) longitudinal polarization fraction in the B(0) decay mode with respect to the squared dimuon mass. These are consistent with the predictions, and most recent determinations from other experiments and of comparable accuracy. We also report the first observation of the B(s)(0)→?μ(+)μ(-) decay and measure its branching ratio BR(B(s)(0)→?μ(+)μ(-))=[1.44±0.33±0.46]×10(-6) using 27±6 signal events. This is currently the most rare B(s)(0) decay observed.     

~(40)Ca_(20)是否稳定?

本文计算表明通常认为高稳定的双满壳层核~(40)Ca_(20)其实并不稳定。~(40)Ca_(20)将可能通过双K层电子俘获的机制而转化为~(40)Ar_(18),其半衰期约为1.2×10~33年。     

C_(3v)和C_(4v)金属纳米多颗粒-薄膜系统的Fano共振光谱的群论

针对C_(3v)和C_(4v)对称构型金属纳米多颗粒-薄膜系统的Fano共振光谱低谷的产生机理,运用群论的方法给出了详细的推导。在前期研究成果的基础上,分析证实了当线偏振光电场沿多颗粒所在平面入射时,C_(nv)对称构型多颗粒-薄膜系统共有4个满足相同不可约表示的E模式:在多颗粒所在平面内只有3个局域表面等离激元电偶极矩共振对称模式,其中2个模式位于外围环形多颗粒中,中心颗粒单独具有1个模式,这与Dnh对称构型多颗粒系统的电偶极矩分布完全相同;另外1个模式虽满足对称性相同的要求,但其电偶极矩的方向垂直于多颗粒所在的平面。C_(nv)点群和D_(nh)点群虽然具有相同的光谱线型,但是薄膜基底的存在会使光谱谷(峰)产生一定的红移或蓝移,这就为设计金属纳米多颗粒-薄膜系统的光学性质及其广泛应用提供了一定的参考。     

O~(16)偶宇称态的结构(Ⅰ)

本文在L-S耦合近似下,并且限于讨论2ω激发的组态,用δ相互作用严格求解了0~+,2~+及4~+态。同时提出一种近似解的办法。即根据粒子的相干效应,可以近似地将双粒子双空穴的结构选为两个粒子相干和两个空穴相干的态。近似解的结果与严格解符合很好。在解释实验上,能量符合得不够好,但在解释O-0跃迁和E2跃迁上却相当成功。     

Supersymmetry restoration in the compactified O(16) ⊗ O (16)' heterotic string theory

We consider twisted compactifications of the O(16) ⊗ O(16)' heterotic string from ten to nine dimensions. We construct a model that interpolates between the O(16) ⊗ O(16)' model at large radii of the compact dimension, and the spontaneously broken E₈⊗E'₈ heterotic superstring at small radii. Further compactification leads to a four-dimensional model with an exponentially suppressed one-loop cosmological constant at small radii. The notion of duality between strings at small and large radii of the compact dimensions is clarified.     

Study of D±s→μ±vμ at Belle

We present a preliminary measurement of the B(Ds→μvμ) with the Belle experiment at the KEKB collider. We select Ds→μvμ decays with a method that provides a high-purity of the selected sample and an absolute measurement of the branching fraction. The results are based on a data sample of 550 fb-1 and are compared to similar measurements by other experiments as well as to the predictions of LQCD. We conclude with short prospects for improvements in the accuracy of the measurement.     

μ介子转化电子装置超导磁体低温系统(英文)

μ介子转化为电子的试验装置(MECO)将安装在美国布鲁克海文国家实验室的交变磁场梯度同步加速器中。一台4.5K千瓦制冷量的氦制冷设备将为MECO试验中的四个大型的超导螺线管磁体提供冷量,针对MECO中超导磁体的性能特点及要求,主要讨论了该低温系统中每个超导磁体的冷却方法以及相应氦制冷机的流程设计方案。