1,564 research outputs found

    Comments on "Observation of Long-Range, Near-Side Angular Correlations in proton-proton Collisions at the LHC" by CMS Collaboration. arXiv:1009.4122[hep-ex]

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    We present comments on the paper "Observation of Long-Range, Near-Side Angular Correlations in proton-proton Collisions at the LHC"

    An Ad-Hoc Facility for Forward Angle Neutron Time-of-Flight Experiments: The 12-C(p,n)12-N Reaction

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    This work was supported by National Science Foundation Grant PHY 75-00289 and Indiana Universit

    Tracking the phase-transition energy in disassembly of hot nuclei

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    In efforts to determine phase transitions in the disintegration of highly excited heavy nuclei, a popular practice is to parametrise the yields of isotopes as a function of temperature in the form Y(z)=zāˆ’Ļ„f(zĻƒ(Tāˆ’T0))Y(z)=z^{-\tau}f(z^{\sigma}(T-T_0)), where Y(z)Y(z)'s are the measured yields and Ļ„,Ļƒ\tau, \sigma and T0T_0 are fitted to the yields. Here T0T_0 would be interpreted as the phase transition temperature. For finite systems such as those obtained in nuclear collisions, this parametrisation is only approximate and hence allows for extraction of T0T_0 in more than one way. In this work we look in detail at how values of T0T_0 differ, depending on methods of extraction. It should be mentioned that for finite systems, this approximate parametrisation works not only at the critical point, but also for first order phase transitions (at least in some models). Thus the approximate fit is no guarantee that one is seeing a critical phenomenon. A different but more conventional search for the nuclear phase transition would look for a maximum in the specific heat as a function of temperature T2T_2. In this case T2T_2 is interpreted as the phase transition temperature. Ideally T0T_0 and T2T_2 would coincide. We invesigate this possibility, both in theory and from the ISiS data, performing both canonical (TT) and microcanonical (e=Eāˆ—/Ae=E^*/A) calculations. Although more than one value of T0T_0 can be extracted from the approximate parmetrisation, the work here points to the best value from among the choices. Several interesting results, seen in theoretical calculations, are borne out in experiment.Comment: Revtex, 10 pages including 8 figures and 2 table

    Laying the groundwork at the AGS: Recent results from experiment E895

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    The E895 Collaboration at the Brookhaven AGS has performed a systematic investigation of Au+Au collisions at 2-8 AGeV, using a large-acceptance Time Projection Chamber. In addition to extensive measurements of particle flow, spectra, two-particle interferometry, and strangeness production, we have performed novel hybrid analyses, including azimuthally-sensitive pion HBT, extraction of the six-dimensional pion phasespace density, and a first measurement of the Lambda-proton correlation function.Comment: Presented at Quark Matter 2001, 8 pages, 5 figure

    Longitudinal Flow of Protons from 2-8 AGeV Central Au+Au Collisions

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    Rapidity distributions of protons from central 197^{197}Au + 197^{197}Au collisions measured by the E895 Collaboration in the energy range from 2 to 8 AGeV at the Brookhaven AGS are presented. Longitudinal flow parameters derived using a thermal model including collective longitudinal expansion are extracted from these distributions. The results show an approximately linear increase in the longitudinal flow velocity, L_{L}, as a function of the logarithm of beam energy.Comment: 5 Pages, including 3 figures, 1 tabl

    Charged Pion Production in 2 to 8 AGeV Central Au+Au Collisions

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    Momentum spectra of charged pions over nearly full rapidity coverage from target to beam rapidity have been measured in the 0-5% most central Au+Au collisions in the beam energy range from 2 to 8 AGeV by the E895 Experiment. Using a thermal parameterization to fit the transverse mass spectra, rapidity density distributions are extracted. The observed spectra are compared with predictions from the RQMD v2.3 cascade model and also to a thermal model including longitudinal flow. The total 4Ļ€\pi yields of the charged pions are used to infer an initial state entropy produced in the collisions.Comment: 13 pgs, 19 figs, accepted by Phys. Rev. C. Data tables available at http://nuclear.ucdavis.edu/~e895/published_spectra.htm
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