Analysis of the effect of blocking mass at corner interface of two plates at arbitrary angles on transmission of plane bending waves

Vibration energy transmission at corner interface of two infinite plates rigidly jointed at arbitrary angles was studied by wave approach so as to investigate the effect of blocking mass used for reducing plane bending wave transmission.Two local coordinate sys- tems were introduced and six new non-dimensional coefficients implying corresponding ratio governing characteristic impedances of plates or blocking mass were introduced to simplify for- mulations of transmission and reflection coefficients.Five samples were tested in experiment. Discussions were carried out based on the comparison between prediction and experiment in terms of insertion loss.It is concluded that blocking mass at corner interface acts like a"low- pass filter",effective for vibration attenuation above certain frequency.The value of TL and IL in"attenuation band"depends mainly on mass per unit length and band width of"attenuation band"on mass moment of inertia per unit length of the blocking mass.     

Studies of dual-harmonic acceleration at CSNS-Ⅱ

The Rapid Cycling Synchrotron(RCS) of the China Spallation Neutron Source(CSNS) complex is designed to provide 1.56×1013 protons per pulse(ppp) during the initial stage,and it is upgradeable to 3.12×1013 ppp during the second stage and 6.24×1013 ppp during the ultimate stage.The high beam intensity in the RCS requires alleviation of space charge effects to reduce beam losses,which is key in such high beam power accelerators.With higher intensities in the upgrading phases,a dual-harmonic RF system is planned to produce flat-topped bunches that are useful to reduce the space charge effects.We have studied different schemes to apply the dual-harmonic acceleration in CSNS-,and have calculated the main parameters of the RF systems,which are presented in this paper.     

Simulation System of Internal-target Detector at HIRFL-CSRm

HIRFL-CSRm will accelerate the proton beam up to 2.8 GeV. The interesting physics, such as the hadron spectrum, di-baryon state and the rare decay mode of the neutral mesons can be investigated with such beams. The corresponding detector as introduced in Ref.[1] is an internal-target 4π detector which is composed of the forward detector (including position detector and hadron calorimeter) to detect particles emitted at forward angles, and the center detector (including tracker, plastic scintillator barrel and EM calorimeter) to measure momentum and energy loss of the charged particle, and the energy and emission angle of the high energy photon at central and backward angles. To design such a complex detector, the Monte-Carlo (MC) simulation is definitely necessary.     

RCE photodiodes at wavelength band of 1.06

Resonant cavity enhancement (RCE) typed optical detector and modulator which operating at wavelength band of 1.06 μm is reported. The peak quantum efficiency of detector is reasonably high as 50% without bias, and the photocurrent contrast ratio of modulator is 3.6 times at -3.5 V as compared to 0 V. The incident angle dependence of RCE device's photoelectric response is investigated carefully.     

Singularities at real points of ℋ space

In the presence of gravitational radiation, there are ordinarily no shear-free slices of null infinity. A four-complex-dimensional set of shear-free slices of complexified null infinity do exist. They comprise the manifold space. In general, there are no preferred real subspaces of space associated with slices of real null infinity. However, for radiation fields possessing a twist-free axial symmetry, a two-parameter family of shear-free slices of real null infinity exist and therefore pick out a preferred two-dimensional real subspace of space. In this paper, we study the geometry of these 2-spaces for the particular case of quadrupole radiation fields for which determination of the shear-free slices reduces to the standard problem of determining orbits of a particle moving in a potential. Our principal interest is the investigation of possible singularities caused by sufficiently intense radiation fields. We find that such singularities do occur for radiation fields having the characteristic powerc ⁵/G.     

Study of terahertz pulses at an edge

The propagation behaviour of terahertz(THz)pulses at an edge is characterized.The phenomenon that the amplitude oscillates periodically in the frequency spectrum is similar to Young's interference,if the absorption effect is neglected.The oscillation cycle is shorter for a thicker sample.THz pulses at an edge are analyzed by the broadband Huygens-Fresnel diffraction integral.The experimental results are in agreement with the simulation results approximately.The simulation errors are also analyzed.     

The Feasibility of Testing the Inverse Square Law of Gravitation at Newtonian Strength and at Mass Separations of 1 μm

We examine the feasibility of searching for violations of the inverse square law of gravitation with Newtonian strength and at particle separations of 1 m. We discuss systematic uncertainties, such as spurious forces due to the Casimir force, and various sources of random uncertainty, including those due to patch fields and detector noise. Our analysis suggests that a cryogenic, drag-free space environment is necessary to make the experiment feasible, as thermal and vibrational noise could potentially be reduced to the required level in such an environment.     

Thermodynamic Interpretation of Field Equations at Horizon of BTZ Black Hole

A spacetime horizon comprising with a black hole singularity acts like a boundary of a thermal system associated with the notions of temperature and entropy. In the case of static metric of Banados-Teitelboim-Zanelli （BTZ） black hole, the field equations near the horizon boundary can be expressed as a thermal identity dE = TdS＋ Pr dA, where E = M is the mass of BTZ black hole, dA is the change in the area of the black hole horizon when the horizon is displaced infinitesimally small, Pr is the radial pressure provided by the source of Einstein equations, S = 41πa is the entropy and T =κ/2π is the Hawking temperature associated with the horizon. This approach is studied further to generalize it for non-static BTZ black hole, showing that it is also possible to interpret the field equation near horizon as a thermodynamic identity dE = TdS ＋ PrdA ＋Ω＋dJ, where Ω＋ is the angular velocity and J is the angular momentum of BTZ black hole. These results indicate that the field equations for BTZ black hole possess intrinsic thermodynamic properties near the horizon.     

Determination of the number of ψ' events at BESⅢ

The number of ψ’ events accumulated by the BESⅢ experiment from March 3 through April 14, 2009, is determined by counting inclusive hadronic events. The result is 106.41×(1.00±0.81%)×106 . The error is systematic dominant; the statistical error is negligible.     

Equation of state of fluid helium at high temperatures and densities

Helium, hydrogen, and their isotopes are the simplest monoatomic and diatomic molecules. It is relatively easy to describe their properties using the basic principles of quantum mechanics. In condensed matter physics, hydrogen and helium serve as the models for the condensed matter properties at extreme conditions so that both experi- mental and theoretical physicists pay much attention to the study of their properties[1], especially the insulator-metal transition of hydrogen[2]. The aim to st…     

Determination of the angles of the unitarity triangle at BABAR⋆

We report recent measurements of the three angles of the unitarity triangle using the data collected with the BABAR detector at the PEP-II asymmetric energy e ⁺ e ^- collider. Original article based on material presented at HADRON 2007.     

Towards Control of Aggregational Behaviour of α-Lactalbumin at Acidic pH

α-Lactalbumin (α-La) undergoes considerable structural changes upon loss of bound Ca²⁺ at acidic pH, leaving α-La in a molten globule structure. Using fluorescence the present work provides more insight into the structural transition of α-La at acidic pH leading to protein aggregation, most likely caused by a combination of hydrophobic and electrostatic interactions. The rate of aggregation is determined by the protein concentration and temperature applied. Availability of Ca²⁺ stabilises the protein, and thus prevent aggregation at pH values as low as pH 2.9. In contrast, presence of Cu²⁺ induces a destabilisation of the protein, which can be explained by a binding to the Zn²⁺ binding site in α-La, possibly resulting in structural alterations of the protein. In general, presence of anions destabilise α-La at pH values below pI, with SO₄ ²⁻ exhibiting the strongest effect on the protein stability, thus correlating well with the Hofmeister series. At more acidic pH values far from pI, α-La becomes more stable towards ion induced aggregation, since higher ion activity is required to efficiently screen the charges on the protein surface. The results presented in this paper provide detailed knowledge on the external parameters leading to aggregation of α-La at acidic pH, thus permitting rational design of the aggregation process.     

Determination of the number of ψ' events at BES Ⅲ

The number of ψ' events accumulated by the BESⅢ experiment from March 3 through April 14, 2009, is determined by counting inclusive hadronic events. The result is 106.41×(1.00±0.81%)×106 . The error is systematic dominant; the statistical error is negligible.     

Current-Voltage Characteristics of Molecular Devices at Low Bias

We use density functional theory and the Green function formalism with charge energy effect included in the self-consistent calculation of the I-V characteristics of a single benzene ring with an appendage of cf3, and identify some interesting properties of the I-V characteristics at low bias. The molecule picks up a fractional charge at zero bias, then the additional fractional charge produces a barrier on the junction of the molecule and contacts to perturb current flow on the molecule. This phenomenon may be useful for the design of future molecular devices.     

Development of a μLCR facility at LAMPF

It has long been recognized thatLCR could profitably be done with the high intensity surface beam at LAMPF [1]. A spectrometer has been built that is matched to the LAMPF beam characteristics. The polarization information is obtained from a downstream array of counters while side counters, containing no polarization signal, monitor the ⁺ beam. Degraders select higher energy e⁺, thereby reducing rates and required counter segmentation while maintaining information content. We apply a ramped longitudinal field in addition to the static one to average over instabilities in the ⁺ beam. This field scan allows direct interpretation of data and does not require a prior estimate of the resonance structure of a sample. Flux coils monitor the applied ramp field and eddy-current induced fields. High average rate (2×10^{7 +}/s). good stability, and the versatile field scan permitted useful data to be collected from Cu, Al(Cu), Al, Si(Al), and polycrystalline Si targets.     

Elastic photoproduction of ϱ0 mesons at HERA

The cross section for the elastic photoproduction of ϱ⁰ mesons (γp → ϱ⁰p) has been measured with the H1 detector at HERA for two average photon-proton centre-of-mass energies of 55 and 187 GeV. The lower energy point was measured by observing directly the ϱ⁰ decay giving a cross section of 9.1 ± 0.9 (stat.) ± 2.5 (syst.) μb. The logarithmic slope parameter of the differential cross section, dσ/dt, is found to be 10.9 ± 2.4 (stat.) ± 1.1 (syst.) GeV⁻². The ϱ⁰ decay polar angular distribution is found to be consistent with s-channel helicity conservation. The higher energy cross section was determined from analysis of the lower part of the hadronic invariant mass spectrum of diffractive photoproduction and found to be 13.6 ± 0.8 (stat.) ± 2.4 (syst.) μb.     

Study of Neutral Track Measurement at BESⅡ

The measurement errors of the deposited energy and position of neutral tracks in Barrel Shower Counter (BSC) of BESⅡ are investigated. The errors of energy and position of real data are determined by radiative Bhabha events, while the errors of Monte Carlo Data are determined by e⁺e^－→γγ events. Then the corrections are tested by the selected ρπ sample, which shows better pull and Confidence Level distribution after the correction. The results are already applied to the kinematic fitting, which can improve the physics results at BESⅡ.     

Determination of event start time at BESⅢ

The principle of the method for the BESⅢ event start time determination and the code construction are described. The investigation of influence of the noise, the method of rejecting noise and the performance checking by the Monte Carlo physics data sample are also presented. The preliminary results got from the Monte Carlo simulation are presented, the reconstruction efficiency of J/ψ→ anything events at noise level 0~60% can achieve above 99%, and the error rate is below 1%.     

Single photo and electroproduction of pions at EBAC@JLAB

Within the Excited Baryon Analysis Center we have performed a dynamical coupled-channels analysis of the available p（e,e＇π）N data in the region of W ≤ 1.6 GeV and Q2 ≤1.45 （GeV/c）2. The channels included are γ＊N, π＊N, ηN, and ηN which has π△, pN, and σN components. With the hadronic parameters of the model determined in our previous investigations of πN→ πN reaction, we have found that the available data in the considered W ≤ 1.6 GeV region can be fitted well by only adjusting the bare γ＊N → N＊ helicity amplitudes for the lowest N＊ states in P33, P11, S11 and D13 partial waves. The meson cloud effect, as required by the unitarity conditions, on the γ＊N → N＊ form factors are examined.