M.C. Güçlü

Impact parameter dependence of multiple lepton pair production from electromagnetic fields

In relativistic heavy-ion collisions, the strong Lorentz-contracted electromagnetic fields are capable of producing copious numbers of lepton pairs through the two-photon mechanism. Monte Carlo techniques have been developed that allow the exact calculation of production by this mechanism when a semi-classical approximation is made to the motion of the two ions. Here, we develop a hybrid Monte Carlo technique that enables us to calculate the impact parameter dependence of the two-photon mechanism for lepton-pair production, and by using this result, we obtain the probability distribution for multiple-pair production as a function of impact parameter. Computations are performed for S+Au and Pb+Pb systems at 200 A GeV and 160 A GeV, respectively. We also compare our results with the equivalent photon approximation and elucidate the differences.

Manufacturing of antibiofouling polymeric membranes with bismuth-BAL chelate (BisBAL)

AbstractRecent developments indicate an increase in demand of water supply and protection of natural water source quality with a requirement of advanced wastewater treatment systems. Formation of biofilms on the membrane surfaces and in the pores of membranes which are caused by extracellular polymeric substances and soluble microbial products has been identified as the main source of biofouling in membrane operation. The secretion of total polysaccharides and proteins by micro-organisms can be lowered when they are exposed to the bismuth-BAL chelate (BisBAL) at near minimum inhibition concentration. Our study aimed at controlling the population and co-products of micro-organisms that cause biofouling. After successful studies with the inhibition of Escherichia coli and Streptococcus pyogenes in activated sludge, BisBAL-containing membranes were fabricated. The effect of BisBAL on membrane performance was also observed. FTIR, SEM, contact angle, and surface roughness analyses were performed for the charac...

Semi-analytic calculations for the impact parameter dependence of electromagnetic multi-lepton pair production

Abstract We provide a new general semi-analytic derivation of the impact parameter dependence of lowest order electromagnetic lepton-pair production in relativistic heavy-ion collisions. By using this result we have also calculated the related analytic multiple-pair production in the two-photon external-field model. We have compared our results with the equivalent-photon approximation and other calculations.

Bound-free electron-positron pair production in relativistic heavy-ion collisions

The bound-free electron-positron pair production is considered for relativistic heavy ion collisions. In particular, cross sections are calculated for the pair production with the simultaneous capture of the electron into the 1s ground state of one of the ions and for energies that are relevant for the relativistic heavy ion collider and the large hadron colliders. In the framework of perturbation theory, we applied Monte Carlo integration techniques to compute the lowest-order Feynman diagrams amplitudes by using Darwin wave functions for the bound states of the electrons and Sommerfeld-Maue wave functions for the continuum states of the positrons. Calculations were performed especially for the collision of Au+Au at 100 GeV/nucleon and Pb+Pb at 3400 GeV/nucleon.The bound-free electron-positron pair production is considered for relativistic heavy ion collisions. In particular, cross sections are calculated for the pair production with the simultaneous capture of the electron into the 1s ground state of one of the ions and for energies that are relevant for the relativistic heavy ion collider and the large hadron colliders. In the framework of perturbation theory, we applied Monte Carlo integration techniques to compute the lowest-order Feynman diagrams amplitudes by using Darwin wave functions for the bound states of the electrons and Sommerfeld-Maue wave functions for the continuum states of the positrons. Calculations were performed especially for the collision of Au+ Au at 100 GeV/nucleon and Pb+ Pb at 3400 GeV/nucleon.

Atomic Collisions and free Lepton Pair Production

In this work, we have calculated the total cross sections of electron‐positron pair production for the collisions of fully stripped gold ions for various energies. We have also compared our calculation with other methods.

Long-term MBR performance of polymeric membrane modified with Bismuth-BAL chelate (BisBAL)

ABSTRACT An ultrafiltration membrane prepared by polyethersulfone (PES) was modified with Bismuth-BAL chelate (BisBAL) and was used in submerged membrane bioreactor system. Moreover, a control membrane reactor was also tasked to evaluate the effect of BisBAL on the membrane performance. The flux profile, transmembrane pressure, the effect of chemical treatment, cake layer formation, anti-fouling properties against extracellular polymeric substances (EPS) and soluble microbial products (SMP) were studied. The UF modified membrane demonstrated a sustained permeability, low cleaning frequency, and longer filtration time. In terms of anti-EPS and SMP accumulation, the modified membrane showed a lower membrane resistance. It can be illustrated from scanning electron microscopy and confocal laser scanning microscope images that the modified membrane had presented better properties than bare PES membrane, as it was looser and thinner. Thus, the UF membrane proved to be more efficient in terms of permeability and lifetime.

Simultaneous production of lepton pairs in ultraperipheral relativistic heavy ion collisions

We calculate the total cross sections and probabilities of electromagnetic productions of electron, muon and tauon pair productions simultaneously. At the Large Hadron Collider (LHC), the available electromagnetic energy is sufficient to produce all kind of leptons coherently. The masses of muon and tauon are large, so their Compton wavelengths are small enough to interact with the colliding nuclei. Therefore, the realistic nuclear form factors are included in the calculations of electromagnetic pair productions. The cross section calculations show that, at the LHC energies, the probabilities of simultaneous productions of all kind of leptons are increased significantly compare to the RHIC energies. Experimentally, observing this simultaneous production can give us important informations about the strong QED.

Multi-pair production cross sections at ultra-relativistic energies

Abstract We provide a new semi-analytic calculations for the electromagnetic multi-pair productions in ultra-relativistic heavy-ion collisions. We have compared our results with the equivalent-photon approximation and path integral method.