Z0 Boson Measurement with the ALICE Central Barrel in pp collisions at 14 TeV

The possibility to detect the Z0 in the ALICE central barrel is studied via the electronic decay channel Z0->e+e-. The signal and the background are simulated with the leading order event generator PYTHIA 6. The total cross-sections are taken from NLO calculations. Based on test beam data, the electron identification performance of the Transition Radiation Detector is extrapolated to high momenta. The expected yields for minimum-bias pp collisions at 14 TeV are presented. An isolation cut on the single electron, together with a minimum transverse momentum cut, allows to obtain a clear signal. The expected background is of the order of 1 % with the main contribution coming from misidentified pions from jets.Comment: 4 pages, 3 figures, QM2008 proceeding

A comprehensive study of rate capability in Multi-Wire Proportional Chambers

Systematic measurements on the rate capability of thin MWPCs operated in Xenon, Argon and Neon mixtures using CO2 as UV-quencher are presented. A good agreement between data and existing models has been found, allowing us to present the rate capability of MWPCs in a comprehensive way and ultimately connect it with the mobilities of the drifting ions.Comment: 29 pages, 18 figure

Charmonium suppression at RHIC and SPS: a hadronic baseline

A kinetic equation approach is applied to model anomalous J/psi suppression at RHIC and SPS by absorption in a hadron resonance gas which successfully describes statistical hadron production in both experiments. The puzzling rapidity dependence of the PHENIX data is reproduced as a geometric effect due to a longer absorption path for J/psi production at forward rapidity.Comment: 16 pages, 6 figures, final version accepted for publication in Phys. Lett.

Transition Radiation Spectra of Electrons from 1 to 10 GeV/c in Regular and Irregular Radiators

We present measurements of the spectral distribution of transition radiation generated by electrons of momentum 1 to 10 GeV/c in different radiator types. We investigate periodic foil radiators and irregular foam and fiber materials. The transition radiation photons are detected by prototypes of the drift chambers to be used in the Transition Radiation Detector (TRD) of the ALICE experiment at CERN, which are filled with a Xe, CO2 (15 %) mixture. The measurements are compared to simulations in order to enhance the quantitative understanding of transition radiation production, in particular the momentum dependence of the transition radiation yield.Comment: 18 pages, 15 figures, submitted to Nucl. Instr. Meth. Phys. Res.

Position Reconstruction in Drift Chambers operated with Xe, CO2 (15%)

We present measurements of position and angular resolution of drift chambers operated with a Xe,CO$_2$(15%) mixture. The results are compared to Monte Carlo simulations and important systematic effects, in particular the dispersive nature of the absorption of transition radiation and non-linearities, are discussed. The measurements were carried out with prototype drift chambers of the ALICE Transition Radiation Detector, but our findings can be generalized to other drift chambers with similar geometry, where the electron drift is perpendicular to the wire planes.Comment: 30 pages, 18 figure

Possible production of exotic baryonia in relativistic heavy-ion collisions

Properties of a hypothetical baryonium with the quark content (uds\ov{u}\ov{d}\ov{s}) are discussed. The MIT bag model predicts its mass to be unexpectedly low, approximately 1210 MeV. Possible hadronic decay modes of this state are analyzed. Ultrarelativistic heavy-ion collisions provide favorable conditions for the formation of such particles from the baryon-free quark-gluon plasma. We estimate multiplicities of such exotic baryonia on the basis of a simple thermal model.Comment: 8 pages, 1 figur

A large-NcN_c PNJL model with explicit ZNc_{N_c} symmetry

A PNJL model is built, in which the Polyakov-loop potential is explicitly Z$_{N_c}$-symmetric in order to mimic a Yang-Mills theory with gauge group SU($N_c$). The physically expected large-$N_c$ and large-$T$ behaviours of the thermodynamic observables computed from the Polyakov-loop potential are used to constrain its free parameters. The effective potential is eventually U(1)-symmetric when $N_c$ is infinite. Light quark flavours are added by using a Nambu-Jona-Lasinio (NJL) model coupled to the Polyakov loop (the PNJL model), and the different phases of the resulting PNJL model are discussed in 't Hooft's large-$N_c$ limit. Three phases are found, in agreement with previous large-$N_c$ studies. When the temperature $T$ is larger than some deconfinement temperature $T_d$, the system is in a deconfined, chirally symmetric, phase for any quark chemical potential $\mu$. When $T<T_d$ however, the system is in a confined phase in which chiral symmetry is either broken or not. The critical line $T_\chi(\mu)$, signalling the restoration of chiral symmetry, has the same qualitative features than what can be obtained within a standard $N_c=3$ PNJL model.Comment: To appear in Phys Rev

Heavy quark(onium) at LHC: the statistical hadronization case

We discuss the production of charmonium in nuclear collisions within the framework of the statistical hadronization model. We demonstrate that the model reproduces very well the availble data at RHIC. We provide predictions for the LHC energy where, dependently on the charm production cross section, a dramatically different behaviour of charmonium production as a function of centrality might be expected. We discuss also the case in elementary collisions, where clearly the statistical model does not reproduce the measurements.Comment: 8 pages, 5 figures; proceeding of SQM09, Buzios, Brazil, to be published in J. Phys.

The surgical approach of advanced esophageal cancers

Clinica l-a Chirurgi U.M.F, Iaşi, Al XI-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova și cea de-a XXXIII-a Reuniune a Chirurgilor din Moldova „Iacomi-Răzeșu” 27-30 septembrie 2011Lucrarea este un studiu retrospectiv a neoplasmelor esofagiene internate în Clinica I Chirurgie Iaşi între 2000 - 2009. După trecerea în revistă a datelor generale (sex, vârstă, posibilități de explorare, decizii terapeutice) a celor 71 de cazuri de neoplasme esofagiene internate în ultimii 10 ani, sunt prezentate sintetic cazurile care au beneficiat de abord chirurgical. Sunt expuse elementele care au concurat la luarea unei anumite decizii terapeutice şi analizate evoluția şi complicațiile postoperatorii. Nu au fost incluse în observații tumorile eso-cardiotuberozitare care constituie un subiect al patologiei joncțiunii esogastrice. Procent de rezecabilitate al leziunilor avansate este extrem de redus (24,13%). Dacă în cancerele avansate pentru exereză nu se porneşte pe ideea radicalității oncologice, având în vedere vârsta şi fragilitatea acestor bolnavi considerăm utilă fracționatea gestului chirurgical în două sau trei etape, atitudine care pe seria noastră a redus mortalitatea perioperatorie. În cazurile inoperabile, by-pass-ul este o soluție valoroasă de rezolvare a disfagiei, dar complexitatea intervenției trebuie să pună în balanță beneficiul net al pacientului; de aceea se indică pentru bolnavii bine compensați biologic şi funcțional, de vârste acceptabile.The therapeutical option was adapted to each case so for resectable tumors we apply a multimodal approach in 21 cases, a palliative approach in 12 cases and gastro or jejunostomy in 25 cases.The location of resectable tumors was cervical in 3 cases, mid third of esophagus in 11 cases, inferior third of esophagus in 4 cases and multiple tumor locations in 3 cases. The T.N.M. stages of operated tumors were especially stage III with 14 cases, Stage I one case, Stage II, 2 cases and Stage IV. 4 cases. A R0 resection was realized in 17 cases associated with a two field lymphadenectomy. We perform the operations in one step in 14 cases and in two steps in 7 cases. Considering esophagectomy with esophagoplasty the best palliation for esophageal cancers, we consider very important to adapt the surgical technique to the nutritional and biological status of the patient. So performing the operation in two steps we succeed to improve the survival rate as shown in our group of patients. The post operative mortality is of 4% In case of unresectable esophageal lesion the eso-gastric by-pass represents a good relief of dysphagia. We recommend this palliative attitude in case of patients with a good nutritional and biological status.The authors present a retrospective study of 58 epidermoid esophageal cancers treated in the l st Surgical Clinic U.M.F. Iasi, in the last decade 2000-2009.The eso-cardial tumors are excluded. The resectability of epidermoid esophageal cancers at the moment of the diagnosis was about 24, 13 %.The tumor location was: upper third of esophagus 10 cases, mid esophagus 33 cases, inferior third of esophagus 12 cases, multiple 3 cases.51 cases (87, 9%) were complicated at the moment of the diagnosis: malnutrition 39 cases, bleeding 2 cases, pneumonia 6 cases (aspiration), eso-tracheal fistula 4 cases

Charmonium from Statistical Hadronization of Heavy Quarks -- a Probe for Deconfinement in the Quark-Gluon Plasma

We review the statistical hadronization picture for charmonium production in ultra-relativistic nuclear collisions. Our starting point is a brief reminder of the status of the thermal model description of hadron production at high energy. Within this framework an excellent account is achieved of all data for hadrons built of (u,d,s) valence quarks using temperature, baryo-chemical potential and volume as thermal parameters. The large charm quark mass brings in a new (non-thermal) scale which is explicitely taken into account by fixing the total number of charm quarks produced in the collision. Emphasis is placed on the description of the physical basis for the resulting statistical hadronization model. We discuss the evidence for statistical hadronization of charmonia by analysis of recent data from the SPS and RHIC accelerators. Furthermore we discuss an extension of this model towards lower beam energies and develop arguments about the prospects to observe medium modifications of open and hidden charm hadrons. With the imminent start of the LHC accelerator at CERN, exciting prospects for charmonium production studies at the very high energy frontier come into reach. We present arguments that, at such energies, charmonium production becomes a fingerprint of deconfinement: even if no charmonia survive in the quark-gluon plasma, statistical hadronization at the QCD phase boundary of the many tens of charm quarks expected in a single central Pb-Pb collision could lead to an enhanced, rather than suppressed production probability when compared to results for nucleon-nucleon reactions scaled by the number of hard collisions in the Pb-Pb system.Comment: review article, 27 pages, Landoldt review volume "Relativistic Heavy Ion Physics", Reinhard Stock, edito