Nuclear modification factor in intermediate-energy heavy-ion collisions

The transverse momentum dependent nuclear modification factors (NMF), namely $R_{CP}$, is investigated for protons produced in Au + Au at 1$A$ GeV within the framework of the isospin-dependent quantum molecular dynamics (IQMD) model. It is found that the radial collective motion during the expansion stage affects the NMF at low transverse momentum a lot. By fitting the transverse mass spectra of protons with the distribution function from the Blast-Wave model, the magnitude of radial flow can be extracted. After removing the contribution from radial flow, the $R_{CP}$ can be regarded as a thermal one and is found to keep unitary at transverse momentum lower than 0.6 GeV/c and enhance at higher transverse momentum, which can be attributed to Cronin effect.Comment: 8 pages, 5 figures; aceepted by Physics Letters

Excitation Energy as a Basic Variable to Control Nuclear Disassembly

Thermodynamical features of Xe system is investigated as functions of temperature and freeze-out density in the frame of lattice gas model. The calculation shows different temperature dependence of physical observables at different freeze-out density. In this case, the critical temperature when the phase transition takes place depends on the freeze-out density. However, a unique critical excitation energy reveals regardless of freeze-out density when the excitation energy is used as a variable insteading of temperature. Moreover, the different behavior of other physical observables with temperature due to different $\rho_f$ vanishes when excitation energy replaces temperature. It indicates that the excitation energy can be seen as a more basic quantity to control nuclear disassembly.Comment: 3 pages, 2 figures, Revte

Surface Damage of Tangshan Earthquake and Characteristics of Response Spectrum of Ground Movement

The intensive ground movement of seismic region was an essential factor in causing ground damages. Damages in historical events signified that the extent of destruction not only conformed to the epicentral distance but also related to geomorphology, soil type and ground structure. Different combination of ground lithology may reflected directly the enhancement and attenuation of seismic wave during its propagation and it had also dominating influence on ground movement, different damages and seismic excitation of the same ground. Hence the amplitude and type of seismic response spectra were determined. In this paper, ground movement and damage feature on geomorphology units of various ground as well as the influence of seismic wave field on earthquake damages were analyzed by seismic ground response. Site zoning was carried out based on the types of response spectra