Aligned Elongation of Ag Nanoparticles Embedded in Silica Irradiated with High Energy Ni Ions

Metallic nanoparticle （NP） shapes have a significant influence on the property of composite embedded with metallic NPs. Swift heavy ion irradiation is an effective way to modify shapes of metallic NPs embedded in an amorphous matrix. We investigate the shape deformation of Ag NPs with irradiation fluence, and 357 MeV Ni ions are used to irradiate the silica containing Ag NPs, which are prepared by ion implantation and vacuum annealing. The UV-vis results show that the surface plasmon resonance （SPR） peak from Ag NPs shifts from 400 to 377nm. The SPR peak has a significant shift at fluence lower than 1 × 10^14 ions/cm2 and shows less shift at fluence higher than 1 × 10^14 ions/cm2. The TEM results reveal that the shapes of Ag NPs also show significant deformation at fluence lower than 1 × 10^14 ions/cm2 and show less deformation at fluence higher than 1 × 10^14 ions/cm2. The blue shift of the SPR peak is considered to be the consequence of defect production and Ag NP shape deformation, Based on the thermal spike model calculation, the temperature of the silica surrounding Ag particles first increases rapidly, then the region of Ag NPs close to the interface of Ag/silica is gradually heated. Therefore, the driven force of Ag NPs deformation is considered as the volume expansion of the first heated silica layer surrounding Ag NPs.

Interactions of a Femtosecond Intense Laser with Rare Gas Clusters in a Dense Jet

A study on the interactions of high intensity (- 1016 W/cm2) femtosecond laser pulses with rare gas clusters in a dense jet is performed. Energy absorption by Ar and Xe clusters is measured and it can be as high as 90%. Very energetic ions produced in the laser interaction with a dense cluster jet are detected by time-of-flight spectrometry and the maximum ion energy of Xe is up to 1.3 MeV. The average ion energies are found to increase with increasing cluster size and get saturated gradually. The average ion energies also show a strong directionality and the average ion energy in the direction parallel to the laser polarization vector is 40% higher than that perpendicular to it. The findings are discussed in terms of a model of charge-dependent ion acceleration.

X-ray emission from 424-MeV/u C ions impacting on selected target

The K-shell x-rays of Ti, V, Fe, Co, Ni, Cu, and Zn induced by 424-MeV/u C^（6＋） ion impact are measured. It is found that the K x-ray shifts to the high energy side and the intensity ratio of Kβ/Kα is larger than the atomic data, owing to the L-shell multiple-ionization. The x-ray production cross sections are deduced from the experimental counts and compared with the binary encounter approximation（BEA）, plane wave approximation（PWBA） and energy-loss Coulomb-repulsion perturbed-stationary-state relativistic（ECPSSR） theoretical predictions. The BEA model with considering the multipleionization fluorescence yield is in better consistence with the experimental results. In addition, the cross section as a function of target atomic K-shell binding energy is presented.

Microstructure evolution of T91 steel after heavy ion irradiation at 550℃

Fe-Cr ferritic/martensitic(F/M)steels have been proposed as one of the candidate materials for the Generation IV nuclear technologies.In this study,a widely-used ferritic/martensitic steel,T91 steel,was irradiated by 196-MeV Kr^(+)ions at 550℃.To reveal the irradiation mechanism,the microstructure evolution of irradiated T91 steel was studied in details by transmission electron microscope(TEM).With increasing dose,the defects gradually changed from black dots to dislocation loops,and further to form dislocation walls near grain boundaries due to the production of a large number of dislocations.When many dislocation loops of primary a0/2<111>type with high migration interacted with other defects or carbon atoms,it led to the production of dislocation segments and other dislocation loops of a0<100>type.Lots of defects accumulated near grain boundaries in the irradiated area,especially in the high-dose area.The grain boundaries of martensite laths acted as important sinks of irradiation defects in T91.Elevated temperature facilitated the migration of defects,leading to the accumulation of defects near the grain boundaries of martensite laths.

Relativistic effects on the back-to-back correlation functions of boson-antiboson pairs in high energy heavy ion collisions

We calculate the back-to-back correlation （BBC） functions of relativistic boson-antiboson pairs in high energy heavy ion collisions using the Monte Carlo method. The relativistic effects on the BBC functions of ФФ and K＋K pairs are investigated. The investigations indicate that the relativistic effects on the BBC functions of K＋K- pairs with large momenta are significant, and the effect is sensitive to the particle freeze-out temperature.

Solution to the Sudakov suppressed Balitsky-Kovchegov equation and its application to HERA data

We analytically solve the Sudakov suppressed Balitsky-Kovchegov evolution equation with fixed and running coupling constants in the saturation region. The analytic solution of the S-matrix shows that the exp(-O(η^2))rapidity dependence of the solution with the fixed coupling constant is replaced by the exp(-O(η^3/2))dependence in the smallest dipole running coupling case, as opposed to obeying the law found in our previous publication, where all the solutions of the next-to-leading order evolution equations comply with exp(-O(η))rapidity dependence once the QCD coupling is switched from the fixed coupling to the smallest dipole running coupling prescription. This finding indicates that the corrections of the sub-leading double logarithms in the Sudakov suppressed evolution equation are significant, which compensate for a part of the evolution decrease of the dipole amplitude introduced by the running coupling effect. To test the analytic findings, we calculate the numerical solutions of the Sudakov suppressed evolution equation, and the numerical results confirm the analytic outcomes. Moreover, we use the numerical solutions of the evolution equationto fit the HERA data. This demonstrates that the Sudakov suppressed evolution equation can achieve a good quality fit to the data.

Enhancement of hydroxyapatite dissolution through structure modification by Krypton ion irradiation

Hydroxyapatite(HA)synthesized by a wet chemical route was subjected to heavy ion irradiation,using4 Me V Krypton ion(Kr17+)with ion fluence ranging from 1×1013 to 1×1015 ions/cm2.Glancing incidence X-ray diffraction(GIXRD)results confirmed the phase purity of irradiated HA with a moderate contraction in lattice parameters,and further indicated the irradiation-induced structural disorder,evidenced by broadening of the diffraction peaks.High-resolution transmission electron microscopy(HRTEM)observations indicated that the applied Kr irradiation induced significant damage in the hydroxyapatite lattice.Specifically,cavities were observed with their diameter and density varying with the irradiation fluences,while a radiation-induced crystalline-to-amorphous transition with increasing ion dose was identified.Raman and X-ray photoelectron spectroscopy(XPS)analysis further indicated the presence of irradiationinduced defects.Ion release from pristine and irradiated materials following immersion in Tris(p H 7.4,37?)buffer showed that dissolution in vitro was enhanced by irradiation,reaching a peak at 0.1 dpa.We examined the effects of irradiation on the early stages of the mouse osteoblast-like cells(MC3 T3-E)response.A cell counting kit-8 assay(CCK-8 test)was carried out to investigate the cytotoxicity of samples,and viable cells can be observed on the irradiated materials.

Single inclusive hadron production at the LHC with an improved impact parameter dependent saturation model

To obtain a reasonable description of the hadron production at the LHC energies,the impact parameter dependent saturation model is modified by inclusion of an anomalous dimensionγ,which controls the slope of the scattering amplitude in the transition from the dilute region to the saturation region.We calculate the transverse momentum distribution and nuclear modification factor of theπ^(0)and charged hadrons with the improved model,and the results are consistent with measurements performed at the LHC.Moreover,we use the original impact parameter dependent model to study the aforementioned measurements performed at the LHC by adjusting its parameters.We find that the improved model is more consistent with the experimental data than the original one,as the anomalous dimension plays a significant role in the suppression of the evolution of the scattering amplitude.

Running coupling effect in next-to-leading order Balitsky-Kovchegov evolution equations

Balitsky-Kovchegov equations in projectile and target rapidity representations are analytically solved for fixed and running coupling cases in the saturation domain. Interestingly, we find that the respective analytic S-matrices in the two rapidity representations have almost the same rapidity dependence in the exponent in the running coupling case, which provides a method to explain why the equally good fits to HERA data were obtained when using three different Balitsky-Kovchegov equations formulated in the two representations. To test the analytic outcomes, we solve the Balitsky-Kovchegov equations and numerically compute the ratios between these dipole amplitudes in the saturation region. The ratios are close to one, which confirms the analytic results. Moreover, the running coupling, collinearly-improved, and extended full collinearly-improved Balitsky-Kovchegov equations are used to fit the HERA data. We find that all of them provide high quality descriptions of the data, and the χ^(2)/d.o.f obtained from the fits are similar. Both the analytic and numerical calculations imply that the Balitsky-Kovchegov equation at the running coupling level is robust and has a sufficiently strong predictive power at HERA energies;however, higher order corrections could be significant for future experiments, such as those at the EIC or LHeC.