Some aspects in accelerator structure studies at SLAC

Recent progress in the accelerator structure studies at SLAC is reported. This paper covers the room temperature accelerator structures for the ILC e⁺/e^－ sources; RF structures for some photon science projects including RF deflectors and the LCLS RF gun; the high gradient accelerator R &; D in a global CLIC collaboration for the future multi-TeV linear colliders.     

Complementary studies on N＊ from e＋e-, pp and pp collisions

Complementary to the conventional experimental studies on N＊ from πN and γ（＊）N reactions, the e＋e-, pp and pp collisions can give novel insights into these N＊ resonances. While the e＋e- collisions through production and decay of vector charmonium ψ provide a nice isospin filter for a simultaneously study of N＊, △＊, ∧＊, ∑＊ and 2＊, the pp collisions should be the best place for producing those △＊＋＋ with large coupling to p＋p though pp →nA＊＋＋ reaction, and the pp collisions should be the best place for looking for those N＊ with large coupling to σN.     

Branching Ratios of α Decay for Nuclei near Deformed Shell Closures

The generalized liquid drop model （GLDM） is extended to the region around deformed shell closure ^270Hs by taking into account the excitation energy EI＋ of the residual daughter nucleus and the centrifugal potential energy Vcen（r）. The branching ratios of a decays from the ground state of a parent nucleus to the ground state 0^＋ of its deformed daughter nucleus and to the first excited state 2^＋ are calculated in the framework of the GLDM. The results support the proposal that a measurement of a spectroscopy is a feasible method to extract information on nuclear deformation of superheavy nuclei around the deformed nucleus ^270Hs.     

Modulated Wave Packets in DNA and Impact of Viscosity

We study the nonlinear dynamics of a DNA molecular system at physiological temperature in a viscous media by using the Peyrard-Bishop model. The nonlinear dynamics of the above system is shown to be governed by the discrete complex Cinzburg-Landau equation. In the non-viscous limit, the equation reduces to the nonlinear Schroedinger equation. Modulational instability criteria are derived for both the cases. On the basis of these criteria, numerical simulations are made, which confirm the analytical predictions. The planar wave solution used as the initial condition makes localized oscillations of base pairs and causes energy localization. The results also show that the viscosity of the solvent in the surrounding damps out the amplitude of wave patterns.     

Spectroscopic investigations of Nd-, Er-, Er/Yb-, and Tm-ions doped SiO2-Al2O3-CaF2-GdF3 glasses

This paper reports on the absorption, visible and near-infrared luminescence properties of Nd³⁺, Er³⁺, Er³⁺/2Yb³⁺, and Tm³⁺ doped oxyfluoride aluminosilicate glasses. From the measured absorption spectra, Judd-Ofelt (J-O) intensity parameters (Ω₂, Ω₄ and Ω₆) have been calculated for all the studied ions. Decay lifetime curves were measured for the visible emissions of Er³⁺ (558 nm, green), and Tm³⁺ (650 and 795 nm), respectively. The near infrared emission spectrum of Nd³⁺ doped glass has shown full width at half maximum (FWHM) around 45 nm (for the ⁴F_3/2→⁴I_9/2 transition), 45 nm (for the ⁴F_3/2→⁴I_11/2 transition), and 60 nm (for the ⁴F_3/2→⁴I_13/2 transition), respectively, with 800 nm laser diode (LD) excitation. For Er³⁺, and Er³⁺/2Yb³⁺ co-doped glasses, the characteristic near infrared emission bands were spectrally centered at 1532 and 1544 nm, respectively, with 980 nm laser diode excitation, exhibiting full width at half maximum around 50 and 90 nm for the erbium ⁴I_13/2→⁴I_15/2 transition. The measured maximum decay times of ⁴I_13/2→⁴I_15/2 transition (at wavelength 1532 and 1544 nm) are about 5.280 and 5.719 ms for 1Er³⁺ and 1Er³⁺/2Yb³⁺ (mol%) co-doped glasses, respectively. The maximum stimulated emission cross sections for ⁴I_13/2→⁴I_15/2 transition of Er³⁺ and Er³⁺/Yb³⁺ are 10.81×10⁻²¹ and 5.723×10^-21 cm². These glasses with better thermal stability, bright visible emissions and broad near-infrared emissions should have potential applications in broadly tunable laser sources, interesting optical luminescent materials and broadband optical amplification at low-loss telecommunication windows.     

Nonlinear optical absorption properties of porphyrins confined in Nafion membrane

The nonlinear absorption (NLA) properties of five different types of porphyrins were studied using the Z-scan technique. The porphyrins under investigation were confined into Nafion column matrix membrane in order to protect them from possible degradation. The results of the experiments have indicated that all the porphyrins tested exhibited interesting NLA properties. The nonlinear absorption coefficients (β’s) were determined at different porphyrin concentrations by comparing the Z-scan data with the theoretical functions.     

利用磁聚焦法测量电子比荷的误差分析

在利用磁聚焦法测量电子比荷的实验中,测量误差与示波管的加速电压和聚焦电压存在较大的相关性．通过对测量误差与电聚焦程度、加速电压和聚焦电压之间关系的分析,指出了误差产生的原因,给出了加速电压和聚焦电压的最佳取值范围．     

King type modification of Meyer-König and Zeller operators based on the -integers

In the present paper, introducing a King type modification of the Meyer-König and Zeller (MKZ) operators, we prove that the error estimation of these operators is better than the classical MKZ operators. Furthermore, a King type modification of the q-MKZ is also introduced and the rate of convergence of this modification is examined.     

Non‐isolated quasi‐degrees

We show that non‐isolated from below 2‐c.e. Q ‐degrees are dense in the structure of c.e. Q ‐degrees. We construct a 2‐c.e. Q ‐degree, which can't be isolated from below not only by c.e. Q ‐degrees, but by any Q ‐degree. We also prove that below any c.e. Q ‐degree there is a 2‐c.e. Q ‐degree, which is non‐isolated from below and from above (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Strongly indexable graphs and applications

In 1990, Acharya and Hegde introduced the concept of strongly k-indexable graphs: A (p,q)-graph G=(V,E) is said to be strongly k-indexable if its vertices can be assigned distinct numbers 0,1,2,…,p−1 so that the values of the edges, obtained as the sums of the numbers assigned to their end vertices form an arithmetic progression k,k+1,k+2,…,k+(q−1). When k=1, a strongly k-indexable graph is simply called a strongly indexable graph. In this paper, we report some results on strongly k-indexable graphs and give an application of strongly k-indexable graphs to plane geometry, viz; construction of polygons of same internal angles and sides of distinct lengths.