Electron identification performance with ALICE TRD prototypes

We present the electron/pion identification performance measured with prototypes for ALICE TRD. Measured spectra of energy deposit of pions and electrons as well as their average values are presented and compared to calculations. Various radiators are investigated over the momentum range of 1 to 6 GeV/c. The time signature of TR is exploited in a bidimensional likelihood mothod.Comment: Presented at the conference "TRDs for the 3rd millenium", Bari, Italy, Sept. 4-7 2003. To appear in Nucl.Instrum.Meth. A. (4 pages, 6 figures

Performance and First Physics Results of the ALICE Muon Spectrometer

A precise measurement of the heavy-flavor production cross-sections in pp collisions is an essential baseline for the heavy-ion program. In addition it is a crucial test of pQCD models in the new energy regime at LHC. ALICE measures the muons from the decay of charmonium resonances and from the semileptonic decay of heavy-flavored hadrons in its forward (-4.0 $<$ $\eta$ $<$ -2.5) Muon Spectrometer. We discuss the status of the detector and present results of data taken in pp collisions at $\sqrt{s}$=7 TeV.Comment: 8 pages and 6 figues. Proceedings for 6th International Conference on Physics and Astrophysics of Quark Gluon Plasma (ICPAQGP 2010), Goa, Indi

Upsilon Production In pp Collisions For Forward Rapidities At LHC

This is a continuation of recent studies of $\Upsilon(nS)$ production at the LHC in pp collisions. Our previous studies were for rapidity y=-1 to 1 for the CMS detector, while the present study is for y=2.5 to 4.0 at the LHC.Comment: 5 pages, 2 figure

The relation between velocity dispersion and mass in simulated clusters of galaxies: dependence on the tracer and the baryonic physics

[Abridged] We present an analysis of the relation between the masses of cluster- and group-sized halos, extracted from $\Lambda$CDM cosmological N-body and hydrodynamic simulations, and their velocity dispersions, at different redshifts from $z=2$ to $z=0$. The main aim of this analysis is to understand how the implementation of baryonic physics in simulations affects such relation, i.e. to what extent the use of the velocity dispersion as a proxy for cluster mass determination is hampered by the imperfect knowledge of the baryonic physics. In our analysis we use several sets of simulations with different physics implemented. Velocity dispersions are determined using three different tracers, DM particles, subhalos, and galaxies. We confirm that DM particles trace a relation that is fully consistent with the theoretical expectations based on the virial theorem and with previous results presented in the literature. On the other hand, subhalos and galaxies trace steeper relations, and with larger values of the normalization. Such relations imply that galaxies and subhalos have a $\sim10$ per cent velocity bias relative to the DM particles, which can be either positive or negative, depending on halo mass, redshift and physics implemented in the simulation. We explain these differences as due to dynamical processes, namely dynamical friction and tidal disruption, acting on substructures and galaxies, but not on DM particles. These processes appear to be more or less effective, depending on the halo masses and the importance of baryon cooling, and may create a non-trivial dependence of the velocity bias and the \soneD--\Mtwo relation on the tracer, the halo mass and its redshift. These results are relevant in view of the application of velocity dispersion as a proxy for cluster masses in ongoing and future large redshift surveys.Comment: 13 pages, 16 figures. Minor modifications to match the version in press on MNRA

Pointing to the minimum scatter: the generalized scaling relations for galaxy clusters

We introduce a generalized scaling law, M_tot = 10^K A^a B^b, to look for the minimum scatter in reconstructing the total mass of hydrodynamically simulated X-ray galaxy clusters, given gas mass M_gas, luminosity L and temperature T. We find a locus in the plane of the logarithmic slopes $a$ and $b$ of the scaling relations where the scatter in mass is minimized. This locus corresponds to b_M = -3/2 a_M +3/2 and b_L = -2 a_L +3/2 for A=M_gas and L, respectively, and B=T. Along these axes, all the known scaling relations can be identified (at different levels of scatter), plus a new one defined as M_tot ~ (LT)^(1/2). Simple formula to evaluate the expected evolution with redshift in the self-similar scenario are provided. In this scenario, no evolution of the scaling relations is predicted for the cases (b_M=0, a_M=1) and (b_L=7/2, a_L=-1), respectively. Once the single quantities are normalized to the average values of the sample under considerations, the normalizations K corresponding to the region with minimum scatter are very close to zero. The combination of these relations allows to reduce the number of free parameters of the fitting function that relates X-ray observables to the total mass and includes the self-similar redshift evolution.Comment: 6 pages, 3 figures. MNRAS in pres

Large-scale inhomogeneities of the intracluster medium: improving mass estimates using the observed azimuthal scatter

Using a set of hydrodynamical simulations of 62 galaxy clusters and groups we study the ICM of inhomogeneities, focusing on the ones on the large scale that, unlike clumps, are the most difficult to identify. To this purpose we introduce the concept of residual clumpiness, C_R, that quantifies the large-scale inhomogeneity of the ICM. After showing that this quantity can be robustly defined for relaxed systems, we characterize how it varies with radius, mass and dynamical state of the halo. Most importantly, we observe that it introduces an overestimate in the determination of the density profile from the X-ray emission, which translates into a systematic overestimate of 6 (12)% in the measurement of M_gas at R_200 for our relaxed (perturbed) cluster sample. At the same time, the increase of C_R with radius introduces also a ~2% systematic underestimate in the measurement of the hydrostatic-equilibrium mass (M_he), which adds to the previous one generating a systematic ~8.5% overestimate in f_gas in our relaxed sample. Since the residual clumpiness of the ICM is not directly observable, we study its correlation with the azimuthal scatter in the X-ray surface brightness of the halo and in the y-parameter profiles. We find that their correlation is highly significant (r_S = 0.6-0.7), allowing to define the azimuthal scatter measured in the X-ray surface brightness profile and in the y-parameter as robust proxies of C_R. After providing a function that connects the two quantities, we obtain that correcting the observed gas density profiles using the azimuthal scatter eliminates the bias in the measurement of M_gas for relaxed objects, which becomes (0+/-2)% up to 2R_200, and reduces it by a factor of 3 for perturbed ones. This method allows also to eliminate the systematics on the measurements of M_he and f_gas, although a significant halo to halo scatter remains. (abridged)Comment: 18 pages, 17 figures, 3 tables. Submitted to MNRAS, revised after referee's comment

Herzbergova dvofaktorska teorija delovne motivacije na primeru zaposlenih v turizmu

Prispevek obravnava delovno motivacijo kontaktnega osebja v turizmu v Sloveniji. Motivacijo opredeljujemo na podlagi Herzbergove dvofaktorske teorije, ki temelji na dveh vrstah faktorjev delovne motivacije, in sicer na motivatorjih, ki zaposlene motivirajo, in higienikih, ki zaposlenih ne motivirajo, a so brez njih nezadovoljni. Rezultati izvedene empirične raziskave kažejo, da imajo motivatorji (npr. priznanje, odgovornost) zelo močan vpliv na delovno motivacijo, medtem ko higieniki (npr. višina plače) nanjo nimajo statistično značilnega vpliva. Izhajajoč iz izsledkov raziskave lahko vodstva turističnih podjetij posvetijo večjo pozornost oz. povečajo pomen motivatorjev, v smislu povečanja odgovornosti kontaktnega osebja, uvedbe priznanj, omogočanja usposabljanj in podajanja ustreznih informacij, saj so le-ti dejavniki ključnega pomena za motiviranost zaposlenih.The article focuses on work motivation of Slovenian front-line employees working in tourism. The motivation is analyzed using a Herzbergs Two Factor Theory of work motivation, which is based on two factor groups of work motivation growth factors that motivate, and hygiene factors that do not motivate, yet their absence causes work dissatisfaction. The empirical research results indicated that growth factors (e.g. recognition and responsibility) have a major impact on work motivation, while hygiene factors (e.g. salary) did not show statistically signicant impact. The ndings of the research could be useful for management in tourism industry, who should give more attention to growth factors or strengthen their meaning by increasing front-line employees responsibilities, recognition, enabling additional trainings and giving adequate information as these factor have a pivotal meaning for employees work motivation

On the role of AGN feedback on the thermal and chemodynamical properties of the hot intra-cluster medium

We present an analysis of the properties of the ICM in an extended set of cosmological hydrodynamical simulations of galaxy clusters and groups performed with the TreePM+SPH GADGET-3 code. Besides a set of non-radiative simulations, we carried out two sets of simulations including radiative cooling, star formation, metal enrichment and feedback from supernovae, one of which also accounts for the effect of feedback from AGN resulting from gas accretion onto super-massive black holes. These simulations are analysed with the aim of studying the relative role played by SN and AGN feedback on the general properties of the diffuse hot baryons in galaxy clusters and groups: scaling relations, temperature, entropy and pressure radial profiles, and ICM chemical enrichment. We find that simulations including AGN feedback produce scaling relations that are in good agreement with X-ray observations at all mass scales. However, our simulations are not able to account for the observed diversity between CC and NCC clusters: unlike for observations, we find that temperature and entropy profiles of relaxed and unrelaxed clusters are quite similar and resemble more the observed behaviour of NCC clusters. As for the pattern of metal enrichment, we find that an enhanced level of iron abundance is produced by AGN feedback with respect to the case of purely SN feedback. As a result, while simulations including AGN produce values of iron abundance in groups in agreement with observations, they over-enrich the ICM in massive clusters. The efficiency of AGN feedback in displacing enriched gas from halos into the inter-galactic medium at high redshift also creates a widespread enrichment in the outskirts of clusters and produces profiles of iron abundance whose slope is in better agreement with observations.Comment: 23 pages, 14 figures, 1 table, accepted for publication in MNRA