Simple parallel stream to serial stream converter for Active Pixel Sensor readout

This paper describes a new electronics module for converting a parallel data flow to a serial stream in the USB 2.0 High Speed protocol. The system provides a connection between a PC USB port and a parallel interface of the DAQ board, which is used for investigation of performance of Active Pixel Sensors (APS) prototypes. The DAQ readout software supports Win XX OS and Linux OS. GUI examples have been prepared in the Lab Windows and Lab View environments. The module that was designed using virtual peripheral concept can be easily adapted for many similar tasks

Physics of Large-x Nuclear Suppression

We discuss a common feature of all known reactions on nuclear targets - a significant suppression at large x. Simple interpretation of this effect is based on energy conservation restrictions in initial state parton rescatterings. Using the light-cone dipole approach this mechanism is shown to control variety of processes on nuclear targets: high-pT particle production at different rapidities as well as direct and virtual (Drell-Yan) photon production. We demonstrate universality and wide applicability of this mechanism allowing to describe large-x effects also at SPS and FNAL energies too low for the onset of coherent effects or shadowing.Comment: 4 pages, 6 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennessee. Only minor changes in tex

Study of Nuclear Suppression at Large Forward Rapidities in d-Au Collisions at Relativistic and Ultrarelativistic Energies

We study a strong suppression of the relative production rate (d-Au)/(p-p) for inclusive high-pT hadrons of different species at large forward rapidities (large Feynman xF). The model predictions calculated in the light-cone dipole approach are in a good agreement with the recent measurements by the BRAHMS and STAR Collaborations at the BNL Relativistic Heavy Ion Collider. We predict a similar suppression at large pT and large xF also at lower energies, where no effect of coherence is possible. It allows to exclude the saturation models or the models based on Color Glass Condensate from interpretation of nuclear effects.Comment: Revised version (6 pages, 4 figures) to appear in Physical Review

Efficient Multi-site Data Movement Using Constraint Programming for Data Hungry Science

For the past decade, HENP experiments have been heading towards a distributed computing model in an effort to concurrently process tasks over enormous data sets that have been increasing in size as a function of time. In order to optimize all available resources (geographically spread) and minimize the processing time, it is necessary to face also the question of efficient data transfers and placements. A key question is whether the time penalty for moving the data to the computational resources is worth the presumed gain. Onward to the truly distributed task scheduling we present the technique using a Constraint Programming (CP) approach. The CP technique schedules data transfers from multiple resources considering all available paths of diverse characteristic (capacity, sharing and storage) having minimum user's waiting time as an objective. We introduce a model for planning data transfers to a single destination (data transfer) as well as its extension for an optimal data set spreading strategy (data placement). Several enhancements for a solver of the CP model will be shown, leading to a faster schedule computation time using symmetry breaking, branch cutting, well studied principles from job-shop scheduling field and several heuristics. Finally, we will present the design and implementation of a corner-stone application aimed at moving datasets according to the schedule. Results will include comparison of performance and trade-off between CP techniques and a Peer-2-Peer model from simulation framework as well as the real case scenario taken from a practical usage of a CP scheduler.Comment: To appear in proceedings of Computing in High Energy and Nuclear Physics 200

Universal Pion Freeze-out in Heavy-Ion Collisions

Based on an evaluation of data on pion interferometry and on particle yields at mid-rapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda_f reaches a value of about 1 fm, which is much smaller than the spatial extent of the system at freeze-out. This critical mean free path is independent of the centrality of the collision and beam energy from AGS to RHIC.Comment: 5 pages, 3 figures, revised version resubmitted to PR

New Results on Pb-Au Collisions at 40 AGeV from the CERES/NA45 Experiment

In 1999 the CERES/NA45 ran at the CERN SPS with a beam energy of 40 GeV/nucleon. The data set comprises about 8.7 millions Pb-Au events with a trigger selection corresponding to approximately the most central 30% of the geometrical cross section. Results on low-mass electron pair analysis are presented. The upgrade of the experimental setup with the radial drift TPC has allowed to enhance hadron physics capabilities of the experiment. New results on hadron spectra (including Lambda) and flow are presented.Comment: Talk at the International Nuclear Physics Conference INPC2001, Berkeley, CA, July 29th - August 3rd 200

Leptonic and charged kaon decay modes of the ϕ\phi meson measured in heavy-ion collisions at the CERN SPS

We report a measurement of $\phi$ meson production in central Pb+Au collisions at E$_{lab}$/A=158 GeV. For the first time in heavy-ion collisions, $\phi$ mesons were reconstructed in the same experiment both in the K$^+$K$^-$ and the dilepton decay channel. Near mid-rapidity, this yields rapidity densities, corrected for production at the same rapidity value, of 2.05 +- 0.14(stat) +- 0.25(syst) and 2.04 +- 0.49(stat)+-{0.32}(syst), respectively. The shape of the measured transverse momentum spectra is also in close agreement in both decay channels. The data rule out a possible enhancement of the $\phi$ yield in the leptonic over the hadronic channel by a factor larger than 1.6 at 95% CL.Comment: 11 pages, 4 figures,submitted to Phys. Rev. Let

Social Structure Predicts Genital Morphology in African Mole-Rats

BACKGROUND:African mole-rats (Bathyergidae, Rodentia) exhibit a wide range of social structures, from solitary to eusocial. We previously found a lack of sex differences in the external genitalia and morphology of the perineal muscles associated with the phallus in the eusocial naked mole-rat. This was quite surprising, as the external genitalia and perineal muscles are sexually dimorphic in all other mammals examined. We hypothesized that the lack of sex differences in naked mole-rats might be related to their unusual social structure. METHODOLOGY/PRINCIPAL FINDINGS:We compared the genitalia and perineal muscles in three African mole-rat species: the naked mole-rat, the solitary silvery mole-rat, and the Damaraland mole-rat, a species considered to be eusocial, but with less reproductive skew than naked mole-rats. Our findings support a relationship between social structure, mating system, and sexual differentiation. Naked mole-rats lack sex differences in genitalia and perineal morphology, silvery mole-rats exhibit sex differences, and Damaraland mole-rats are intermediate. CONCLUSIONS/SIGNIFICANCE:The lack of sex differences in naked mole-rats is not an attribute of all African mole-rats, but appears to have evolved in relation to their unusual social structure and reproductive biology

Event-by-event fluctuations of the mean transverse momentum in 40, 80, and 158 A GeV/c Pb-Au collisions

Measurements of event-by-event fluctuations of the mean transverse momentum in Pb-Au collisions at 40, 80, and 158 A GeV/c are presented. A significant excess of mean p_T fluctuations at mid-rapidity is observed over the expectation from statistically independent particle emission. The results are somewhat smaller than recent measurements at RHIC. A possible non-monotonic behaviour of the mean p_T fluctuations as function of collision energy, which may have indicated that the system has passed the critical point of the QCD phase diagram in the range of mu_B under investigation, has not been observed. The centrality dependence of mean p_T fluctuations in Pb-Au is consistent with an extrapolation from pp collisions assuming that the non-statistical fluctuations scale with multiplicity. The results are compared to calculations by the RQMD and UrQMD event generators.Comment: 28 pages, 10 figure

Disappearance of back-to-back high pTp_T hadron correlations in central Au+Au collisions at sNN\sqrt{s_{NN}} = 200 GeV

Azimuthal correlations for large transverse momentum charged hadrons have been measured over a wide pseudo-rapidity range and full azimuth in Au+Au and p+p collisions at $\sqrt{s_{NN}}$ = 200 GeV. The small-angle correlations observed in p+p collisions and at all centralities of Au+Au collisions are characteristic of hard-scattering processes already observed in elementary collisions. A strong back-to-back correlation exists for p+p and peripheral Au + Au. In contrast, the back-to-back correlations are reduced considerably in the most central Au+Au collisions, indicating substantial interaction as the hard-scattered partons or their fragmentation products traverse the medium.Comment: submitted to Phys. Rev. Let