Multiplicity studies and effective energy in ALICE at the LHC

In this work we explore the possibility to perform “effective energy” studies in very high energy collisions at the CERN large hadron collider (LHC). In particular, we focus on the possibility to measure in pp collisions the average charged multiplicity as a function of the effective energy with the ALICE experiment, using its capability to measure the energy of the leading baryons with the zero degree calorimeters. Analyses of this kind have been done at lower centre-of-mass energies and have shown that, once the appropriate kinematic variables are chosen, particle production is characterized by universal properties: no matter the nature of the interacting particles, the final states have identical features. Assuming that this universality picture can be extended to ion–ion collisions, as suggested by recent results from RHIC experiments, a novel approach based on the scaling hypothesis for limiting fragmentation has been used to derive the expected charged event multiplicity in AA interactions at LHC. This leads to scenarios where the multiplicity is significantly lower compared to most of the predictions from the models currently used to describe high energy AA collisions. A mean charged multiplicity of about 1000–2000 per rapidity unit (at η∼0) is expected for the most central Pb–Pb collisions at . In memory of A. Smirnitskiy     

Performance studies of a full-length prototype for the CASTOR forward calorimeter at the CMS experiment

The Time-Of-Flight detector (TOF) of the ALICE experiment at the CERN LHC is based on Multi-gap Resistive Plate Chambers (MRPCs). The TOF detector consists of 152928 readout channels covering a total area of 141 m². In this paper the results of the calibration with cosmic-ray data collected during 2009 are presented.     

Synthesis and characterization of a paramagnetic receptor based on cyclobis(paraquat-p-phenylene) tetracation

Synthesis of a new class of π-electron-deficient tetracationic cyclophane ring, cyclobis(paraquat-p-phenylene), carrying one or two paramagnetic side-arms based on 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) moiety has been achieved in five steps starting from 2,5-dimethyl benzoic acid. The possibility of exploiting the proposed cyclophanes as hosts in rotaxane-like structures was tested preparing the monoradical receptor by the clipping procedure in the presence of 1,5-dimethoxynaphthalene (DMN). The addition of template allows the isolation of the monoradical complex with DMN.     

Redox mediation at 11-mercaptoundecanoic acid self-assembled monolayers on gold

Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and digital simulation techniques were used to investigate quantitatively the mechanism of electron transfer (ET) through densely packed and well-ordered self-assembled monolayers (SAMs) of 11-mercaptoundecanoic acid on gold, either pristine or modified by physically adsorbed glucose oxidase (GOx). In the presence of ferrocenylmethanol (FcMeOH) as a redox mediator, ET kinetics involving either solution-phase hydrophilic redox probes such as [Fe(CN)6]3-/4- or surface-immobilized GOx is greatly accelerated: [Fe(CN)6]3-/4- undergoes diffusion-controlled ET, while the enzymatic electrochemical conversion of glucose to gluconolactone is efficiently sustained by FcMeOH. Analysis of the results, also including the digital simulation of CV and EIS data, showed the prevalence of an ET mechanism according to the so-called membrane model that comprises the permeation of the redox mediator within the SAM and the intermolecular ET to the redox probe located outside the monolayer. The analysis of the catalytic current generated at the GOx/SAM electrode in the presence of glucose and FcMeOH allowed the high surface protein coverage suggested by X-ray photoelectron spectroscopy (XPS) measurements to be confirmed.     

Inclusive K(S);(0)K(S);(0) resonance production in ep collisions at HERA

Inclusive K_{S};{0}K_{S};{0} production in ep collisions at the DESY ep collider HERA was studied with the ZEUS detector using an integrated luminosity of 0.5 fb;{-1}. Enhancements in the mass spectrum were observed and are attributed to the production of f_{2}(1270)/a_{2};{0}(1320), f_{2};{'}(1525) and f_{0}(1710). Masses and widths were obtained using a fit which takes into account theoretical predictions based on SU(3) symmetry arguments, and are consistent with the Particle Data Group values. The f_{0}(1710) state, which has a mass consistent with a glueball candidate, was observed with a statistical significance of 5 standard deviations. However, if this state is the same as that seen in gammagamma-->K_{S};{0}K_{S};{0}, it is unlikely to be a pure glueball state.     

Space charge limited avalanche growth in multigap resistive plate chambers

The European Physical Journal C - The ALICE TOF array will be built using the Multigap Resistive Plate Chamber(MRPC) configured as a double stack. Each stack contains 5 gas gaps with width of...     

Electrode surface modification by a spirobifluorene derivative. An XPS and electrochemical investigation

Ordered thin layers of a spirobifluorene derivative containing an amino group were formed by grafting them onto a self-assembled monolayer (SAM) of 11-mercaptoundecanoic acid (11-MUA) on gold. Either physical (H-bonding) or chemical bonding (activated by EDCl) was investigated. X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy confirmed that both methods can be used to effectively graft 2-amino-9,9'-spirobifluorene molecules onto the SAM surface, giving high surface coverages, with a significantly higher packing in the case of chemisorbed films. EIS measurements also showed that the covalently bonded spirobifluorene SAMs act as an effective barrier to both ion penetration and heterogeneous electron transfer.