The light σ-meson

In the framework of the dispersion relation N/D-approach, we restore the low-energy (IJ ^PC = 00^{+ +})-wave amplitude sewing it with the previously obtained K-matrix solution for the region 450-1900 MeV. The restored N/D-amplitude has a pole on the second sheet of the complex-s plane near the threshold, that is the light -meson. Received: 21 February 2000 / Accepted: 20 June 2000     

Stackable luminescent device integrating blue light emitting diode with red organic light emitting diode

We present a novel stackable luminescent device integrating a blue light emitting diode(LED)with a red organic LED(OLED)in series.The anode of the OLED is connected with the cathode of the LED through a via in the insulation layer on the LED.The LED–OLED hybrid device is electroluminescent and two electroluminescence(EL)peaks(the blue peak around 454 nm and the red peak around 610 nm)are observed clearly.The effect of the indium tin oxide(ITO)layer on the device performance is analyzed.Compared with the individual LED and OLED,their combination shows great potential applications in the field of white lighting,plant lighting,and display.     

Can laser light cool semiconductors?

Laser cooling in semiconductors is theoretically investigated including arbitrary external efficiency and photon recycling. Experimental conditions needed to attain net cooling in GaAs are derived.     

Synchronization of long/short light pulse

Based on rough synchronization of long/short light pulse,fine synchronizationof long/short light pulse was achieved with a photoconductive switch.     

Simulations of light antinucleus–nucleus interactions

Creations of light anti-nuclei (anti-deuterium, anti-tritium, anti-³He and anti-⁴He) are observed by collaborations at the LHC and RHIC accelerators. Some cosmic ray experiments are aimed to find the anti-nuclei in cosmic rays. To support the experimental studies of anti-nuclei a Monte Carlo simulation of anti-nuclei interactions with matter is implemented in the Geant4 toolkit. The implementation combines practically all known theoretical approaches to the problem of antinucleon-nucleon interactions.     

Anisotropic light diffusion: an oxymoron?

Light propagation in anisotropic random media is studied in the steady-state and time domains. Solutions of the anisotropic diffusion equation are compared to results obtained by the Monte Carlo method. Contrary to what has been reported so far, we find that even in the "diffusive regime" the anisotropic diffusion equation does not describe correctly the light propagation in anisotropic random media.     

Ultrafast blue light emission from SiC nanowires

Cubic silicon carbide (SiC) nanowires are synthesized in a catalyst-assisted process. The nanowires with diameter of - 40 nm exhibit strong blue light emission at room temperature under ultraviolet (UV) femtosecond laser excitation. The photon energy of peak emission is higher than the energy bandgap of cubic SiC which shows involvement of quantum confinement effect. The ultrafast fluorescence is deconvoluted by Monte-Carlo method. The results show two ultrafast decay processes whose lifetimes are about 26 and 567 ps respectively. The mechanisms of such ultrafast processes are discussed.     

Green’s function calculations of light nuclei

The influence of short-range correlations in nuclei was investigated with realistic nuclear force. The nucleon-nucleon interaction was renormalized with V_lowk technique and applied to the Green’s function calculations. The Dyson equation was reformulated with algebraic diagrammatic constructions. We also analyzed the binding energy of ⁴He, calculated with chiral potential and CD-Bonn potential. The properties of Green’s function with realistic nuclear forces are also discussed.     

Shanghai symposium on intermediate‐energy light sources

The University of Wisconsin Synchrotron Radiation Center (SRC) held its annual users' meeting at Stoughton, WI, on October 23–24, 2009, with over 90 people from 30 institutions in attendance. Events included updates on the facility status, two poster sessions, the Aladdin Lamp Award session, several memorial sessions for Dr. Cliff Olson, and invited talks representing current research at SRC, along with related topics. The Aladdin Lamp Award was presented to the finishing graduate student with the best dissertation research, as judged by an extended abstract and an invited presentation. Additional prizes were given for the best poster in each of the poster sessions. Meetings between the SRC user community and National Science Foundation representatives were also held to discuss the future of the Aladdin electron storage ring at SRC.     

μ −SR-Spectroscopy on light neutral muonic atoms

In the past few years ^–SR-spectroscopy has been successfully applied to the simple muonic atoms, namely muonic helium: He ^–e^–. Here the theoretical and experimental progress in understanding this atomic system consisting of a nucleus, a muon and an electron is reviewed. The various effects contributing to the ground state hyperfine structure are explained. The experiments are described and are compared with the theoretical calculations.     

Fast light of CsI（Na） crystals

The responses of different common alkali halide crystals to alpha-rays and gamma-rays are tested in this research. It is found that only CsI(Na) crystals have significantly different waveforms between alpha and gamma scintillations, while others do not exhibit this phenomena. The rise time of the fast light is about 5 ns and the decay time is 17±12 ns. It is suggested that the fast light of CsI(Na) crystals arises from the recombination of free electrons with self-trapped holes of the host crystal CsI. Self-absorption limits the emission of fast light of CsI(Tl) and NaI(Tl) crystals.     

Strong guiding of light in hollow nanowire structures

We have theoretically investigated the guiding mode patterns of hollow nanowires.Two types of nanowires, round shape and hexagonal shape,are examined with different combination of outer and inner radii. Because of electric field discontinuity at hollow interfaces and evanescent modes overlap in low refractive index region,strong light guiding and confinement are achieved in both hollow wire structures.     

Nuclear structure effects in light π- mesoatoms

Performing the angle transformation from pion-nucleon to pion-nucleus CMS frame the first order pion-nucleus optical potential receives also a contribution due to nucleonic Fermi motion. The corresponding term is always repulsive and reflects the nuclear spin-orbital interaction playing an important role particularly for nuclei with half-filled valence shells. We demonstrate the effects due to this term yielding a contribution to the level shifts and widths of pionic atoms. Such ideas allow one to explain theA-dependence of 2p-level energy shifts for most of the s-d shell-mesoatoms.Dedicated by the co-authors to the memory of M. Gmitro.Two authors (A. C. and R. M.) are grateful to Prof. H. J. Leisi, Prof. M. P. Locher and Dr. P. F. A. Goudsmit for stimulating discussions and hospitality extended to them during their stay at Paul Scherrer Institute.     

Possible light neutral boson and particle mass quantization

Qualities of nucleons, such as the fundamental parameter mass, might be modified in extreme conditions relative to those of isolated nucleons. We show the ratio of the EMC-effect tagged nucleon mass to that of the free one(m*/m);these values are derived from the nuclear structure function ratio between heavy nuclei and deuterium measured in the electron Deep Inelastic Scattering(DIS) reaction in 0.3≤x≤0.7. The increase in m*/mwith A-1/3 is phenomenologically interpreted via the release of a color-singlet cluster formed by sea quarks and gluons in bound nucleons holding high momentum in the nucleus, from which the mass and fraction of non-nucleonic components in nuclei can be deduced. The mass of color-singlet clusters released per short range correlated(SRC) proton in the high momentum region(k > 2 fm-1) is extracted to be 16.890 ±0.016 MeV/c2, which evidences the possibility of a light neutral boson and quantized mass of matter.