The PHENIX Experiment at RHIC

The physics emphases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed. The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program available at http://www.rhic.bnl.gov/phenix

Сравнительный анализ применения виртуальных и механических артикуляторов в функциональной диагностике

The paper presents the results of examination of patients with articulation disorders of the lower jaw caused by internal pathology of the TMJ. The purpose of the presented work: to study the effectiveness of the use of mechanical and virtual articulators in the functional diagnosis of patients with internal TMJ disorders. All patients underwent comprehensive clinical and instrumental examination including cone-beam computed tomography (CT) and axiographic examination (optical axiograph Dentograf Prosystom, Russia). CBCT was used to assess the state of the TMJ and determine the individual ratio of jaw and joint models. When axiography was recorded and analyzed articular trajectories of the lower jaw. In the first group of patients dynamic occlusion was evaluated using a mechanical articulator, in the second group a virtual articulator was used. It was revealed that the use of mechanical articulators in functional diagnostics to assess dynamic occlusion is limited and does not allow to obtain individualized patient data, their efficiency was 75%. The use of virtual articulators allows to evaluate the dynamic occlusion during opening and closing of the mouth, protrusion and laterotrusion, as well as the continuous movement of the lower jaw with the registration of all possible dental contacts. Due to the combination of CT data of the patient’s head and virtual models, the highest accuracy of placing models in the virtual articulator in accordance with the individual characteristics of patients was achieved.В работе представлены результаты обследования пациентов с нарушениями артикуляции нижней челюсти, вызванных внутренней патологией ВНЧС. Цель представленной работы - изучить эффективность применения механических и виртуальных артикуляторов в функциональной диагностике пациентов с внутренними нарушениями ВНЧС. Всем пациентам проводилось комплексное клиническое и инструментальное обследование, включавшее конусно-лучевую компьютерную томографию (КЛКТ) и аксиографическое исследование (оптический аксиограф Dentograf Prosystom, Россия). КЛКТ использовалось для оценки состояния ВНЧС и определения индивидуального соотношения моделей челюстей и суставов. При аксиографии регистрировали и анализировали суставные траектории движения нижней челюсти. В I группе пациентов динамическая окклюзия оценивалась с использованием механического артикулятора, во II группе применяли виртуальный артикулятор. Выявлено, что применение механических артикуляторов в функциональной диагностике для оценки динамической окклюзии ограничено и не позволяет получить индивидуализированные данные пациента, их эффективность составила 75%. Использование виртуальных артикуляторов позволяет оценить динамическую окклюзию при открывании-закрывании рта, протрузии и латеротрузии, а также непрерывном движении нижней челюсти с регистрацией всех возможных зубных контактов. Благодаря совмещению данных КТ головы пациента и виртуальных моделей была достигнута максимально высокая точность размещения моделей в виртуальном артикуляторе в соответствии с индивидуальными особенностями пациентов

Quarkonium production from d+Au to Au+Au collisions

M. Rosati on behalf of the PHENIX Collaboration EIThe PHENIX experiment measured J/$\psi$ production in pp, d+Au and Au+Au reactions at \sqrt{^sNN}$= 200 GeV over a wide range of rapidity and transverse momentum. The nuclear modification factor obtained by comparing the d+Au and pp cross sections as a function of rapidity, is consistent with shadowing of the gluon distribution functions. J/$\psi$ production in Au+Au collisions was compared to the production in pp collisions and it was found to be inconsistent with models that predict strong enhancement relative to binary collision scaling

Heavy flavor production in PHENIX

O. Drapier on behalf of the PHENIX Collaboration, EIThe PHENIX experiment at RHIC measured single electron spectra in p + p, d + Au and Au + Au collisions at $\sqrt{s_{NN}} = 200$ GeV, and in Au + Au collisions at $\sqrt{s_{NN}} = 62.4$ GeV. In these spectra, electrons from semi-leptonic decays of charmed particles are the dominant contribution after subtraction of all 'photonic' sources (photon conversions, Dalitz decays, decays of light vector mesons). The p + p open charm production cross-section is found to be in good agreement with pQCD NLO calculations. The shape of the distributions obtained for p + p interactions is compared with those observed for nucleus-nucleus collisions. From p + p to d + Au and Au + Au interactions, open charm production is found to scale with the number of binary collisions $N_{\rm coll}$ . Au + Au data at $\sqrt{s_{NN}} = 62.4$ GeV is compatible with the ISR p + p results scaled by $N_{\rm coll}$ . The elliptic flow parameter v2 of heavy flavor electrons has also been measured, and is found to be non-zero in the intermediate pT range

Differential probes of medium-induced energy loss

B. Cole on behalf of the PHENIX Collaboration -EIResults from the PHENIX experiment of measurements of high- $p_{\rm T}$ particle production presented at the Hard Probes 2004 Conference are summarized. This paper focuses on a sub-set of the measurements presented at the conference, namely the suppression of $\pi^0$ production at moderate to high $p_{\rm T}$ as a function of angle with respect to the collision reaction plane, $\Delta\phi$ , for different collision centralities. The data are presented in the form of nuclear modification factor as a function of angle with respect to the reaction plane, $R_{AA} (\Delta \phi)$ . The data are analyzed using empirical estimates of the medium-induced energy loss obtained from the $R_{AA} (\Delta \phi)$ values. A geometric analysis is performed with the goal of understanding the simultaneous dependence of RAA on $\Delta\phi$ and centrality. We find that the centrality and $\Delta\phi$ dependence of the $\pi^0$ suppression can be made approximately consistent using an admittedly over-simplistic description of the geometry of the jet propagation in the medium but only if the energy loss is effectively reduced for short parton path lengths in the medium. We find that with a more "canonical" treatment of the quenching geometry, the $\pi^0$ suppression varies more rapidly with $\Delta\phi$ than would be expected from the centrality dependence of the suppression