Quark‐gluon densities in the nuclear fragmentation region in heavy ion collisions at LHC
At the LHC, the leading partons in the nuclei are expected to interact with the maximal possible strength — black disk limit — up to transverse momenta of the order of few GeV. We demonstrate that in this limit the densities of the quark — gluon systems produced in the central AA collisions in the nucleus fragmentation regions should exceed 300GeV/fm3 which is at least as high as the densities discussed for the central region. Experimental signatures of such a regime are also discussed.
Ion-induced quark-gluon implosion.
We investigate nuclear fragmentation in the central proton-nucleus and nucleus-nucleus collisions at the energies of CERN LHC. Within the semiclassical approximation we argue that because of the fast increase with energy of the cross sections of soft and hard interactions each nucleon is stripped in the average process off "soft" partons and fragments into a collection of leading quarks and gluons with large p(t). Valence quarks and gluons are streaming in the opposite directions when viewed in the c.m. of the produced system. The resulting pattern of the fragmentation of the colliding nuclei leads to an implosion of the quark and gluon constituents of the nuclei. The nonequilibrium state produced at the initial stage in the nucleus fragmentation region is estimated to have densities >/=50 GeV/fm(3) at the LHC energies and probably >/=10 GeV/fm(3) at BNL RHIC.
Time behavior of gas pressure and PD activity in insulation cavities under AC voltage
In the framework of developing defect-based life models (i.e. the life model of partial discharge-induced damage growth from a micro-void in polymer matrix), ageing tests were performed on PE layered specimens with artificial cavities under constant gas pressure and constant gas volume conditions, respectively. Time behavior of the discharge repetition rate and amplitude were recorded and compared under these two conditions. Results show that pressure variation has little influence on PD activities at constant gas volume. Under constant gas pressure, the evolution of gas volume has similar characteristic to the product of discharge amplitude and repetition rate.