Statistical Significance of Non-Reproducibility of Cross Sections in Dissipative Reactions

Two independent excitation function measurements have been performed in the reaction system of ^19F ^93Nb using two target foils of the same nominal thickness. We measured the dissipative reaction products at incident energies of 102 through 108 MeV with a step of 250ke V. The variance of energy autocorrelation functions of the reaction products was found to be three times of that originated from the randomized counting rates. By analysing the probability distributions of the deviations in the measured cross sections, we found that about 20% of all the deviations exceeds three standard deviations. This indicates that the non-reproduclbility of the cross sections in the two independent measurements is of a statistical significance but not originated from randomized fluctuation of counting rates.     

Properties of the β-delayed proton decay of 146Ho

The proton-rich isotope 146Ho was produced via the fusion-evaporation reaction ^92Mo （^58Ni, 3p1n）. The β-delayed proton decay of 146Ho was studied by proton-γ coincidence measurements using a He-jet tape transport system. The γ-transitions in ^145Tb following the proton emissions were observed, and the β-delayed proton branching ratios to the final states in the grand-daughter nucleus ^145Tb were determined. According to the relative branching ratios, the ground-state spin of 146Ho has been proposed and the possible configuration discussed.     

No Anomaly of the B（E2） Value Around the Backbend in ^130Ce

The lifetime measurements of the high-spin states in the yrast band of ^130Ce have been performed using the Doppler shift attenuation method in conjunction with the reaction ^116Sn(^16O,2n)^130Ce at a projectile energy of 73MeV.The reduced transition probabilities B(E2) deduced from these measurements show a great reduction in the vicinity of the backbending region.The previously reported anomalously high B(E2) value was not observed in the present experiment.This result is in agreement with theoretical prediction based on a realistic nucleon-nucleon interaction.     

In-beam γ-ray Spectroscopy of Level Structure in ^134Ba

Excited states of ^134Ba, populated via the heavy-ion induced ^128Te(^10B, 1p3n)134Ba reaction at 46 MeV beam energy, have been studied to medium and high spins by in-beam γ-ray spectroscopy techniques. The experiment was performed at the tandem accelerator laboratory in the University of Tsukuba, Japan. The target is an isotopically enriched ^128Te metallic foil of 2.3mg/cm^2 thickness with a 3mg/cm^2 gold backing. Nine anti-Compton HPGe detectors were employed for the measurements of γ-γ-t coincidences. The level scheme of ^134Ba, deduced from this study, was shown in Fig.1.     

Influence of purity of HfO_2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO_2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO_2 was the main impurity in the two kinds of HfO_2 either in the original HfO_2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO_2 single layer films was much larger than that of the other impurities such as Ti and Fe,which showed that it was just ZrO_2 that made the difference between the optical performance of the film products including the two kinds of HfO_2.With these two kinds of HfO_2 and the same kind of SiO_2,we deposited HfO_2/SiO_2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively, which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Observation of tropospheric NO_2 by airborne multi-axis differential optical absorption spectroscopy in the Pearl River Delta region,south China

An airborne multi-axis differential optical absorption spectroscopic （AMAX-DOAS） instrument was developed and applied to measure tropospheric NO2 in the Pearl River Delta region in the south of China. By combining the measurements in nadir and zenith directions and analyzing the UV and visible spectral region using the DOAS method, information about tropospheric NO2 vertical columns was obtained. Strong tropospheric NO2 signals were detected when flying over heavilly polluted regions and point sources like plants. The AMAX-DOAS results were compared with ground-based MAX-DOAS observations in the southwest of Zhuhai city using the same parameters for radiative transport calculations. The difference in vertical column data between the two instruments is about 8%. Our data were also compared with those from OMI and fair agreement was obtained with a correlation coefficient R of 0.61. The difference between the two instruments can be attributed to the different spatial resolution and the temporal mismatch during the measurements.     

An Experimental Analysis of Residual Stress Measurements in Porous Silicon Using Micro-Raman Spectroscopy

Micro-Raman spectroscopy of porous silicon films of micrometre thickness and on silicon bulk substrates is carried out.The practical information is given for applications of stress measurements in the films which were obtained with electrochemical etching technique.Higher residual stress (reached GPa) in the etched area falls continuously through the transitional area to the un-etched area of the sample.However,the stress gradient is smaller in the etched or un-etched area and increases in the transitional area between the two areas.Using atomic force microscopy to investigate the surface appearance of porous silicon films,the micro-cavity structure is expected to relate to the distribution of residual stress.     

Isospin Effect of Charged Particle Multiplicity in Intermediate Energy Heavy Ion Collisions

The dependences of He and intermediate mass fragments (IMF) production rates in the reactions 55 MeV/u ^40Ar ^58,64 Ni on the isospin, impact parameter and primary excitation energy of the reaction nuclear system were studied by using the 4π charged particle multi-detector array system (MUDAL). For the mentioned two reaction systems, the measured He particle contribution in the total charged particle multiplicity increases with increasing the total charged particle multiplicity but for the contribution of IMFs in the total charged particle multiplicity increases with increasing the total charged particle multiplicity at lower total charged particle multiplicities, and latter on it drops down with further increasing of the total charged particle multiplicities (see Fig.l). The experimental results of these two reaction systems with the same nuclear charge indicate that the contribution of He and IMFs in the total charged particle multiplicities are obviously isospin dependent.     

Unusual Band Splitting and Superconducting Gap Evolution with Sulfur Substitution in FeSe

High-resolution angle-resolved photoemission measurements were taken on FeSe_1-xS_x（x=0,0.04,and 0.08）superconductors.With an ultrahigh energy resolution of 0.4 meV,unusual two hole bands near the Brillouin-zone center,which was possibly a result of additional symmetry breaking,were identified in all the sulfur-substituted samples.In addition,in both of the hole bands highly anisotropic superconducting gaps with resolution limited nodes were evidenced.We find that the larger ...     

Influences of stress on the properties of GaN/InGaN multiple quantum well LEDs grown on Si(111) substrates

The influences of stress on the properties of In GaN/GaN multiple quantum wells(MQWs) grown on silicon substrate were investigated.The different stresses were induced by growing In GaN and Al GaN insertion layers(IL) respectively before the growth of MQWs in metal–organic chemical vapor deposition(MOCVD) system.High resolution x-ray diffraction(HRXRD) and photoluminescence(PL) measurements demonstrated that the In GaN IL introduced an additional tensile stress in n-GaN,which released the strain in MQWs.It is helpful to increase the indium incorporation in MQWs.In comparison with MQWs without the IL,the wavelength shows a red-shift.Al GaN IL introduced a compressive stress to compensate the tensile stress,which reduces the indium composition in MQWs.PL measurement shows a blue-shift of wavelength.The two kinds of ILs were adopted to In GaN/GaN MQWs LED structures.The same wavelength shifts were also observed in the electroluminescence(EL) measurements of the LEDs.Improved indium homogeneity with In GaN IL,and phase separation with Al GaN IL were observed in the light images of the LEDs.     

Mechanisms and Concentration Dependence of Upconversion Fluorescence in Er^3＋ and Tm^3＋ Codoped Tellurite Glasses

We investigate the upconversion luminescence of Er3^ and Tm^3 codoped tellurite glasses under both the 975 and 80Ohm excitations. By Tm^3 codoping, the Er^3 green emission corresponding to the (^4S3/2, 2H11/2) → 4I15/2 transitions was quenched, while the red emission corresponding to the ^4F9/2 → ^4I15/2 transition was selectively sensitized. The red emission has a maximum in the range where the ratio of Er^3 - to Tm^3 -content is about two and its fluorescence intensity becomes 1.5 and 5 times larger at the maximum than those in the absence of Tm^3 for 975 and 800 nm excitations, respectively. The results were explained considering the influence of energy transfers between these two active ions.     

Finite-Width Correction to Form Factors of γγ^＊→ π^0 Transition

Instead of the usual zero-width approximation for one resonance, we use the finite-width approximation for the two low resonances, i.e. the ρ- ω mesons, to investigate the light-cone local QCD sum rules for the form factor of the transition γγ^＊→ π^0 ,According to the method of the analytic continuation by duality, the weight function, the polynomial of a low order N, is added to the dispersion integral to annihilate the integrand in the region where both resonance saturation and the QCD asymptotic expression are least reliable. The resultant form factor in the cases for the zero- and finite-widths are almost the same, both agree well with the experimental measurements. A comparison with the result from the Laplacian transformed light-cone sum rules and a brief discussion are given.     

Role of decay in the search for double-charm baryons

Double-charm baryons,whose components are two heavy charm quarks and one light quark,are part of a large family of hadrons predicted by the quark model.Studies on them are helpful to understand the hadron structure and the nature of the strong interaction.After efforts expended over decades of searching,experimental measurements achieved a breakthrough with the first observation of the double-charm baryon of■^++cc(ccu)via■^++cc→Λ^+c K^-π^+π^+ by the LHCb collaboration in 2017[1].Since then,the LHCb collaboration has been leading the experimental studies for doubly charmed baryons[2-6]because they are produced in considerably large numbers in the Large Hadron Collider(LHC).     

Existence and Stability of Compact-Like Discrete Breather in Discrete One-Dimensional Monatomic Chains

Compact-like discrete breathers in discrete one-dimensional monatomic chains are investigated by discussing a generalized discrete one-dimensional monatomic model. It is proven that compact-like discrete breathers exist not only in soft Ф^4 potential but also in hard Ф^4 potential and K4 chains. The measurements of compact-like discrete breathers＇ core in soft and hard Ф^4 potential are determined by coupling parameter K4, while the measurements of compact-like discrete breathers＇ core in K4 chains are not related to coupling parameter K4. The stabilities of compact-like discrete breathers correlate closely to coupling parameter K4 and the boundary condition of lattice.     

Measurement of the pion form factor for Mππ^2 between 0.1 and 0.85 GeV2 with the KLOE detector

The KLOE experiment at the φ-factory DAФPNE has measured the pion form factor in the range between 0.1 〈 Mππ^2 〈 0.85 GeV^2 using events taken at √s = 1 GeV with a photon emitted at large polar angles in the initial state. This measurement extends the Mππ^2 region covered by KLOE ISR measurements of the pion form factor down to the two pion production threshold. The value obtained in this measurement of the dipion contribution to the muon anomalous magnetic moment of △αμ^ππ= （478.5±2-0stat±4.8syst±2.9theo）·10^-10 further confirms the discrepancy between the Standard Model evaluation for αμ and the experimental value measured by the （g-2） collaboration at BNL.     

Field Emission from an Array of Free—standing Metallic Nanowires

Arrays of single crystalline gold nanowires were synthesized electrochemically in porous polycarbonate membranes.The polycarbonate membrane was then removed to obtain free-standing nanowires for field emission measurements.The turn-on electric field strength for field emission is found to be lower than 2V/μm.The actual electric field that extracted electrons out of the gold nanowires is estimated to be about 10^3 times higher than the field directly expected in the model of a parallel plate condenser.The availability of the field emission is therefore attributed to the strong electric field at the tips resulting from small curvature radius of the gold nanowires.     

Theoretical analysis of the acoustical characteristics of suspended micro-perforated panel absorbers

Sound absorption characteristics of suspended micro-perforated panel absorbers were investigated theoretically. The method of half thickness model of such panel absorber with quadripole analysis was used for predicting its acoustic performance. The analysis results show that the predictions agree well with the measurements of absorption in the reverberation chamber. The factors affecting the absorption characteristics for such absorbers were discussed, and some rules as design guidelines were given.     

Experimental investigation of photolunlinescence spectra of Yb~(3+) sensitized Er~(3+)-doped glass samples in series

Fabrication technology of the Yb3+:Er3+ co-doped glass samples is introduced. Photolummescence (PL) characteristics of a single sample were experimentally investigated. The PL peak intensities of two samples in series were measured and discussed. The results show that the PL peak intensities of two samples in series depend on pump manners and arrangement of the samples. The better amplification ability can be obtained by two samples in series doped with low-concentration ytterbium instead of a single sample doped with high-concentration ytterbium.     

Measurement of Change of ^7Be Decay Rate in Be and Au

We have measured the possible change of the decay rate of ^7Be implanted into hosts of natural beryllium and natural gold. No difference between the ^7 Be decay rates in the two hosts is observed within the experimental precision of 0.12%. This result implies that change of the decay rate of ^7Be implanted in different materials cannot be simply expected from the electron affinity difference consideration lonely and the lattice structure of the host materials should be taken into account.     

Explicit Proof of Equivalence of Two—Point Functions in the Two Formalisms of Thermal Field Theory

We give an explicit proof of equivalence of the two-point function to one-loop order in the two formalisms of thermal λφ^3 theory based on the expressions in the real-time formalism and indicate that the key point of completing the proof is to separate carefully the imaginary part of the zero-temperature loop integral from relevant expressions and this fact will certainly be very useful for examination of the equivalent problem of two formalisms of thermal field theory in other theories,including the one of the propagators for scalar bound states in an NJL model.