Pion program for the future rare-decay experiments

The future investigations of rare decays of elementary particles demand the creation of new-generation setups which can perform much greater statistics and precise experimental data. The proposed new setups at CERN, NA62 (NA48/3 (P326SPS)), and at IHEP, OKA, are planned to obtain experimental data at the level of 10⁻¹⁰–10⁻¹² branching ratio. The main goals of both experimental programs are connected with the study of ultrarare kaon decays, but beams of these experiments contain 95% (NA48) and 50% (OKA) of pions. It is natural to use the pion part of these beams for study of rare pion decays. The pion program may be performed simultaneously or consecutively with the main tasks. Such problems as search for tensor interaction, measurements of branching ratio and form factors of some pion decays, effects of polarization, and search for new particles are included in this program. The text was submitted by the authors in English.     

The horn, kink and step, dale: from few GeV to few TeV

Rich experimental data have been collected in heavy-ion collisions at high energies to study the properties of strongly interacting matter. As the theory of strong interactions, QCD, predicts asymptotic freedom, the created matter at sufficiently high temperature and density will be dominated by a state of quasi-free quarks and gluons referred to as the Quark-Qluon Plasma (QGP). Experimental signals for the onset of the QGP creation (the onset of the deconfinement) have been predicted within the statistical model for the early stage of nucleus-nucleus collisions. In this model the existence of two different phases is assumed: confined mater and the QGP, as well as a first order phase transition between them. Until recently, these predictions were confirmed only by the NA49 experiment at the CERN SPS. In this report recent results from STAR at RHIC/BNL and from ALICE at LHC/CERN, related to the onset of deconfinement, will be compared to published results from NA49.     

Hybrid optics for focusing ultrashort laser pulses

We present a specially designed hybrid optics comprising refraction and diffraction effects for tight spatial and temporal focusing of ultrashort laser pulses. Both aims can be put into practice by having a high numerical aperture (NA=0.45) and low internal dispersion at the same time. We are presenting what we believe is the first experimental realization of such a hybrid short plus focusing optics. The focusing properties are compared with a commonly used microscope objective (20 X, NA = 0.45) in theory and experimentally.     

Diffraction response of colloidal crystals: effect of numerical aperture

We present a quantitative experimental and theoretical study of the effect of numerical aperture (NA) on the Bragg diffraction from a dry polystyrene colloidal crystal. The diffraction peak parameters changed noticeably as the NA was increased from 0.017 to 0.5. The diffraction wavelength blueshifted 1.4% from 584 to 576 nm, and the normalized full width at half-maximum increased from 6.2% to 7.0%. These shifts occurred primarily for NA > 0.3 and agreed qualitatively with results predicted by a layered Korringa-Kohn-Rostoker method. Thus, by using focusing optics with NAs below 0.3, the diffraction response of low-photonic-strength mesostructures may be compared with normal-incidence experimental and theoretical data.     

绿光光存储实验研究

在光存储技术中,采用短激光波长激光器和大数值孔径物镜是提高光存储密度的两种有效途径.本文采用532 nm波长激光, 0.65数值孔径物镜,建立了绿光存储实验装置.并采用该实验装置在CD-RW相变光盘上进行了存储实验研究,实现了线宽约为500 nm的实验结果.     

Onset of deconfinement and critical point: NA49 and NA61/SHINE at the CERN SPS

This paper is dedicated to the memory of József Zimányi one of the founders of the experiment NA49 at the CERN SPS. Firstly, the paper summarizes the main results of NA49 concerning observation of the onset of deconfinement in central Pb+Pb collisions at the low SPS energies. Secondly, it sketches the physics program of NA61 at the CERN SPS, the successor of NA49, which in particular aims to discover the critical point of strongly interacting matter. Finaly, a brief review of the future experimental programs in the CERN SPS energy range is given.     

影响石英单模光纤数值孔径测量的因素及分析

本文采用远场光斑法和光强法测量了石英单模光纤的数值孔径.实验结果表明,由光纤耦合条件不同导致的光斑形状变化,对数值孔径的测量影响不大,单模光纤的纤芯直径小,导致出射光存在较强的衍射现象,对数值孔径的测量造成较大的影响,无论采用光斑法还是光强法,需以衍射第1次极大为计算标准,尽量选择光斑中心为亮斑时测量其数值孔径.此外,...     

The NA62 experiment at CERN

The goal of the NA62 experiment at CERN is to collect O(100) events of the ultrarare K\(^{+}\rightarrow \pi ^{+}\nu \bar {\nu }\) decay in two years. After a long R&D phase and a successful pilot run in 2014, the first data-taking phase took place in 2015. In this paper the importance of the experiment’s physics goal, as well as the experimental solutions adopted in order to attain it, will be reviewed.     

Spectrally encoded slit confocal microscopy

A simple and cost-effective method for real-time imaging in confocal microscopy is proposed. Spectrally encoded slit confocal microscopy (SESCoM) uses a spectral encoding technique together with a confocal slit aperture to achieve two-dimensional images. Simulation and experimental results of the SESCoM's axial and lateral performances are presented. The measured FWHM of the axial response is 1.15 mum when an objective with a NA of 0.95 is used. FWHMs of the lateral line spread functions are measured to be 236 and 244 nm along the x and y directions, respectively. Both the axial and the lateral experimental results agree well with the simulation results.     

Medium modifications of kaons in pion matter

Kaon in-medium masses and mean-field potentials are calculated in isotopically symmetric pion matter to one loop of chiral perturbation theory. The results are extended to BNL RHIC temperatures using experimental data on piK scattering phase shifts. The kaon in-medium broadening results in an acceleration of the phi-->K(-)K decay. The increased apparent dilepton branching of the phi mesons, observed recently by the NA50, NA49, and PHENIX Collaborations at RHIC, is interpreted in terms of rescattering of secondary kaons inside the pion matter.     

Refractive index dispersion properties of collagen for microscopic second-harmonic generation

We theoretically simulate second-harmonic generation (SHG) in collagen under linearly polarized focused laser beam. With this model, the effects of numerical aperture (NA) and refractive index dispersion on SHG emission have been investigated. Dispersion properties of collagen are significant under incident wavelength in the visible range. Our results show that the efficient SHG is obtained by controlling the NA, and the higher NA is a necessity when the dispersion effect is considered. Our theoretical simulation results provide useful clues for experimental study of microscopic SHG emission in collagen excited by focused beam.     

400GeV/c pp碰撞两粒子关联的角度依赖性

利用400GeV/c pp碰撞多重产生的实验数据计算了粒子-粒子关联(PPC)及其不对称性(PPCA)的角度依赖性.结果与L3的e⁺e^－数据有明显的差别,但与NA22强子碰撞的实验数据符合得很好;领头粒子对强子碰撞的PPCA分布有很大影响.通过计算两粒子方位角差的分布观察到了方位角关联.     

Methods to study event-by-event fluctuations in the NA61/SHINE experiment at the CERN SPS

Theoretical calculations locate the critical point (CP) of strongly interacting matter at energies accessible at the CERN SPS. Event-by-event transverse momentum and multiplicity fluctuations are considered as one of the most important tools to search for the CP. Pilot studies of the energy dependence and the system size dependence of both p _T and multiplicity fluctuations were performed by the NA49 experiment. The NA61/SHINE ion program is a continuation of these efforts. After briefly recalling the essential NA49 results on fluctuations we will discuss the technical methods (removing Non-Target interactions) which we plan to apply for future transverse momentum and multiplicity fluctuation analyses.     

Recent results on heavy-ion physics from the SPS

The CERN SPS heavy-ion physics program was recently given an important and fresh impetus with the running of the NA60 dimuon experiment, which probed indium-indium collisions at 158 GeV per incident nucleon (in 2003), as well as proton-nucleus collisions at 158 and 400 GeV (essentially in 2004). Several interesting physics results have been obtained and were recently presented by NA60. They address such varied physics topics as the search for in-medium modifications on the ρ short-lived vector meson (which could be related to the restoration of chiral symmetry, spontaneously broken in the hadronic world), the understanding of the “anomalous” J/ψ suppression (expected to be a signature of quark-gluon deconfinement), the search for thermal dimuons (presumably radiated from a thermal system, maybe composed of deconfined quarks and gluons — the “quark-gluon plasma”), the understanding of the enhancement of θ production in heavy-ion collisions, etc. These topics were previously studied by other SPS experiments, and very interesting observations were made, but serious doubts remained concerning the interpretation of those earlier results. It is remarkable that one single experiment, NA60, is able to provide high-quality information on each of these many topics, potentially triggering a very significant step forward in our understanding of “quark-matter physics”.In this paper, after a general introduction, I describe the NA60 apparatus, the data taking conditions, and the main steps in the data reconstruction procedure. I then give some information on the muon track matching and background subtraction procedures. In the remaining sections I review some of the results presently available from the on-going physics analyses, in what concerns the studies of low mass and intermediate mass dimuon production, and J/ψ suppression, in proton-nucleus and indium-indium collisions. These new (and still preliminary) results are placed in perspective, by recalling the findings of previous experiments.     

Proton and Λ hyperon production in nucleus-nucleus collisions

Experimental data obtained by the NA35 Collaboration for the difference of the p and \(\bar p\) spectra and the difference of the Λ and \(\bar \Lambda\) spectra (net proton and Λ-hyperon spectra), as well as the inclusive Λ and \(\bar \Lambda\) spectra measured by the NA49, NA57, and STAR Collaborations, are compared with the predictions of the quark-gluon string model. The contribution of string-junction diffusion is calculated, and interaction with nuclear clusters is taken into account along with the corrections for inelastic screening. The level of numerical agreement with experimental data is between 20 and 30%. The predictions for the LHC energy are given.     

Angular Dependence of Two Particle Correlation in 400GeV/c pp Collisions

The angular dependence of the particle-Particle comeladon (PPC) and its asytiumeby (PPCA) have been calculated by using the experimental data of multiplicity production for pp collisions at 400GeV/ c. The results are different stmngly from the overall behavior of e⁺e^－ data,but agree with the results obtained by NA22 collaboration quite well. The leading particles influence stingily the PPCA disribibudons for hadronic collisions data. The calculated results for the distributions of the azimuthal difference between two pardcles mean that the azimuthal correlation has been observed.     

高数值孔径双芯光纤的双折射研究

具体分析了具有高数值孔径的双芯光纤的双折射特性。首先利用超格子正交函数法和耦合模理论分析了双芯光纤的几何双折射,并将两种方法计算的几何双折射进行了比较分析。数值计算结果表明双芯光纤在两纤芯非常接近的情况下,几何双折射仍较小,只能到10-5量级。利用超格子正交函数法计算了双椭圆芯光纤的双折射,改变结构参量可使几何双折射达到10-4量级。高的数值孔径需要高的掺锗量,理论上分析了高数值孔径时双芯光纤功率集中区域的应力双折射,应力双折射接近10-4量级。设计制作出了具有良好保偏性能的双芯掺铒光纤,测试、分析了它的几何参量和折射率分布;双芯光纤双折射系数达到了8.4×10-5。双芯掺铒光纤可以作为保偏掺铒光纤,应用到制作具有稳定的单一偏振态输出的光纤激光器。     

Thin-thick coexistence behavior of 8CB liquid crystalline films on silicon

The wetting behavior of thin films of 4-n-octyl-4'-cyanobiphenyl (8CB) on Si is investigated via optical and x-ray reflectivity measurement. An experimental phase diagram is obtained showing a broad thick-thin coexistence region spanning the bulk isotropic-to-nematic (T(IN)) and the nematic-to-smectic-A (T(NA)) temperatures. For Si surfaces with coverages between 47 and 72 +/- 3 nm, reentrant wetting behavior is observed twice as we increase the temperature, with separate coexistence behaviors near T(IN) and T(NA). For coverages less than 47 nm, however, the two coexistence behaviors merge into a single coexistence region. The observed thin-thick coexistence near the second-order NA transition is not anticipated by any previous theory or experiment. Nevertheless, the behavior of the thin and thick phases within the coexistence regions is consistent with this being an equilibrium phenomenon.     

Mutation-induced spatial differences in neuraminidase structure and sensitivity to neuraminidase inhibitors

Neuraminidase(NA), a major surface glycoprotein of influenza virus with well-defined active sites, is an ideal platform for the development of antiviral drugs. However, a growing number of NA mutations have drug resistance to today's inhibitors. Numerous efforts are made to explore the resistance mechanisms through understanding the structural changes in mutated NA proteins and the associated different binding profiles of inhibitors, via x-ray, nuclear magnetic resonance,electron microscopy, and molecular dynamics methods. This review presents the architectural features of mutated NA proteins, as well as the respective inhibitor sensitivities arising from these spatial differences. Finally, we summarize the resistance mechanisms of today's neuraminidase inhibitors and the outlook for the development of novel inhibitors.