This Letter presents the first measurement of event-by-event fluctuations of the elliptic flow parameter v{sub 2} in Au+Au collisions at {radical}(s{sub NN})=200 GeV as a function of collision ...centrality. The relative nonstatistical fluctuations of the v{sub 2} parameter are found to be approximately 40%. The results, including contributions from event-by-event elliptic flow fluctuations and from azimuthal correlations that are unrelated to the reaction plane (nonflow correlations), establish an upper limit on the magnitude of underlying elliptic flow fluctuations. This limit is consistent with predictions based on spatial fluctuations of the participating nucleons in the initial nuclear overlap region. These results provide important constraints on models of the initial state and hydrodynamic evolution of relativistic heavy ion collisions.
A measurement of two-particle correlations with a high transverse momentum trigger particle (p{sub T}{sup trig}>2.5 GeV/c) is presented for Au+Au collisions at sq root(s{sub NN})=200 GeV over the ...uniquely broad longitudinal acceptance of the PHOBOS detector (-4<{Delta}{eta}<2). A broadening of the away-side azimuthal correlation compared to elementary collisions is observed at all {Delta}{eta}. As in p+p collisions, the near side is characterized by a peak of correlated partners at small angle relative to the trigger particle. However, in central Au+Au collisions an additional correlation extended in {Delta}{eta} and known as the 'ridge' is found to reach at least |{Delta}{eta}|approx =4. The ridge yield is largely independent of {Delta}{eta} over the measured range, and it decreases towards more peripheral collisions. For the chosen p{sub T}{sup trig} cut, the ridge yield is consistent with zero for events with less than roughly 100 participating nucleons.
Highly integrated multichannel readout electronics is crucial in contemporary particle physics experiments. A novel silicon photomultiplier readout system based on the VMM3a ASIC was developed, for ...the first time exploiting this chip for calorimetric purposes. To extend the dynamic range the signal from each SiPM channel was processed by two electronics channels with different gain. A fully operational prototype system with 256 SiPM readout channels allowed the collection of data from a prototype of the ALICE Forward Hadron Calorimeter (FoCal-H). The design and the test beam results using high energy hadron beams are presented and discussed, confirming the applicability of VMM3a-based solutions for energy measurements in a high rate environment.
Glauber models are used to calculate geometric quantities in the initial state of heavy ion collisions, such as impact parameter, number of participating nucleons and initial eccentricity. ...Experimental heavy-ion collaboration, in particular at RHIC and LHC, use Glauber Model calculations for various geometric observables. In this document, we describe the assumptions inherent to the approach, and provide an updated implementation (v2) of the Monte Carlo based Glauber Model calculation, which originally was used by the PHOBOS collaboration. The main improvement w.r.t. the earlier version (arXiv:0805.4411) are the inclusion of Tritium, Helium-3, and Uranium, as well as the treatment of deformed nuclei and Glauber-Gribov fluctuations of the proton in p+A collisions. A users' guide (updated to reflect changes in v2) is provided for running various calculations.
This paper examines whether incumbent national governments of the member states of the European Union (EU) manipulated the fiscal policy instruments at their disposal in order to create national ...political business cycles (PBCs), opportunistic or partisan, in the 1970–1998 period. The empirical evidence does not support this hypothesis. Rather, it appears that governments have pursued stabilization policies. Such a finding is encouraging in the sense that it is expected to facilitate the intentions of the EMU states to coordinate their fiscal policies with the aim of establishing a federal-type fiscal policy in the future.
This paper reports the development and testing of n-type silicon pad array detectors targeted for the Forward Calorimeter (FoCal) detector, which is an upgrade of the ALICE detector at CERN, ...scheduled for data taking in Run~4~(2029-2034). The FoCal detector includes hadronic and electromagnetic calorimeters, with the latter made of tungsten absorber layers and granular silicon pad arrays read out using the High Granularity Calorimeter Readout Chip~(HGCROC). This paper covers the Technology Computer-Aided Design (TCAD) simulations, the fabrication process, current versus voltage (IV) and capacitance versus voltage (CV) measurements, test results with a blue LED and \(^{90}\)Sr beta source, and neutron radiation hardness tests. IV measurements for the detector showed that 90\% of the pads had leakage current below 10~nA at full depletion voltage. Simulations predicted a breakdown voltage of 1000~V and practical tests confirmed stable operation up to 500~V without breakdown. CV measurements in the data and the simulations gave a full depletion voltage of around 50~V at a capacitance of 35~pF. LED tests verified that all detector pads responded correctly. Additionally, the 1\(\times\)1 cm\(^2\) pads were also tested with the neutron radiations at a fluence of \(5\times10^{13}\) 1~MeV~n\(_{eq}\)/cm\(^2\).
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