Initial state nuclear effects for jet production measured in sNN=200GeV\sqrt{s_\mathrm{NN}} = 200 \mathrm{GeV} d+Au collisions by STAR

Full jet reconstruction in heavy-ion collisions is a promising tool for quantitative study of properties of the dense medium produced at RHIC. Measurements of d+Au collisions are important to disentangle initial state nuclear effects from medium-induced $k_\mathrm{T}$ broadening and jet quenching. We report measurements of mid-rapidity ($|\eta_{jet}| < 0.4|$) di-jet correlations in d+Au using high-statistics run 8 RHIC data at $\sqrt{s_\mathrm{NN}} = 200 \mathrm{GeV}$.Comment: 2 pages, 2 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse

Jets in 200 GeV p+p and d+Au collisions from the STAR experiment at RHIC

Full jet reconstruction in heavy-ion collisions is a promising tool for the quantitative study of properties of the dense medium produced at RHIC. Measurements of d+Au collisions are important to disentangle initial state nuclear effects from medium-induced kT broadening and jet quenching. Study of jet production and properties in d+Au in combination with similar studies in p+p is an important baseline measurement needed to better understand heavy-ion results. We present mid-rapidity inclusive jet pT spectra and di-jet correlations (kT) in 200 GeV p+p and d+Au collisions from the 2007-2008 RHIC run. We discuss the methods used to correct the data for detector effects and for background in d+Au collisions.Comment: 4 pages, 5 figures. To appear in Hot Quarks 2010 conference proceeding

Setting up a STAR Tier 2 Site at Golias/Prague Farm

High Energy Nuclear Physics (HENP) collaborations' experience show that the computing resources available at a single site are often neither sufficient nor satisfy the need of remote collaborators. From latencies in the network connectivity to the lack of interactivity, work at distant computing centers is often inefficient. Having fully functional software stack on local resources is a strong enabler of science opportunities for any local group who can afford the time investment. Prague's heavy-ions group participating in STAR experiment at RHIC has been a strong advocate of local computing as the most efficient means of data processing and physics analyses. Tier 2 computing center was set up at a Regional Computing Center for Particle Physics called "Golias". We report on our experience in setting up a fully functional Tier 2 center and discuss the solutions chosen to address storage space and analysis issues and the impact on the farms overall functionality. This includes a locally built STAR analysis framework, integration with a local DPM system (a cost effective storage solution), the influence of the availability and quality of the network connection to Tier 0 via a dedicated CESNET/ESnet link and the development of light-weight yet fully automated data transfer tools allowing the movement of entire datasets from BNL (Tier 0) to Golias (Tier 2).Comment: To appear in proceedings of Computing in High Energy and Nuclear Physics 200

STAR inner tracking upgrade - A performance study

Anisotropic flow measurements have demonstrated development of partonic collectivity in $200\mathrm{GeV}$ Au+Au collisions at RHIC. To understand the partonic EOS, thermalization must be addressed. Collective motion of heavy-flavor (c,b) quarks can be used to indicate the degree of thermalization of the light-flavor quarks (u,d,s). Measurement of heavy-flavor quark collectivity requires direct reconstruction of heavy-flavor hadrons in the low \pt region. Measurement of open charm spectra to high \pt can be used to investigate heavy-quark energy loss and medium properties. The Heavy Flavor Tracker (HFT), a proposed upgrade to the STAR experiment at midrapidity, will measure $v_{2}$ of open-charm hadrons to very low \pt by reconstructing their displaced decay vertices. The innermost part of the HFT is the PIXEL detector (made of two low mass monolithic active pixel sensor layers), which delivers a high precision position measurement close to the collision vertex. The Intermediate Silicon Tracker (IST), a 1-layer strip detector, is essential to improve hit identification in the PIXEL detector when running at full RHIC-II luminosity. Using a full GEANT simulation, open charm measurement capabilities of STAR with the HFT will be shown. Its performance in a broad \pt range will be demonstrated on $v_{2}$ (\pt > 0.5\mathrm{GeV}/c) and $R_\mathrm{CP}$ (\pt < 10\mathrm{GeV}/c) measurements of \D meson. Results of reconstruction of \Lc baryon in heavy-ion collisions are presented.Comment: to appear in EPJ C (Hot Quarks 2008 conference volume

Jet Production in p+p and d+Au Collisions √sNN = 200 GeV in STAR

Title: Jet production in p+p and d+Au collisions at √ sNN = 200 GeV in STAR Author: Jan Kapitán Affiliation: Nuclear Physics Institute AS CR Supervisor: doc. Michal Šumbera, CSc., DSc., Nuclear Physics Institute AS CR Abstract: The aim of this work is to measure the effects of cold nuclear matter on jet production in √ sNN = 200 GeV d+Au collisions at Relativistic Heavy Ion Collider (RHIC). After a brief theoretical introduction and description of the experimental setup, jet analysis and the required corrections are described. The jets are reconstructed in p+p and d+Au collisions recorded by the STAR experiment using the anti − kT jet algorithm. Inclusive jet pT spectra in d+Au collisions and their centrality dependence are compared to the reference measurement in p+p collisions and to the binary collision scaling. Di-jet correlations are studied in p+p and most central d+Au collisions to measure the kT effect and its possible nuclear broadening. These results will also be used as a baseline measurement for ongoing studies of jet production in heavy-ion collisions at RHIC. Keywords: jets, d+Au collisions, cold nuclear matter effects, STAR, RHI

Studium proton-protonových srážek na RHIC

Ústav částicové a jaderné fyzikyInstitute of Particle and Nuclear PhysicsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Produkce jetů ve srážkách p+p a d+Au při √sNN = 200 GeV ve STARu

Název práce: Produkce jetů ve srážkách p+p a d+Au při √ sNN = 200 GeV ve STARu Autor: Jan Kapitán Školící pracoviště: Ústav jaderné fyziky AV ČR, v.v.i. Vedoucí disertační práce: doc. Michal Šumbera, CSc., DSc., Ústav jaderné fyziky AV ČR, v.v.i. Abstrakt: Cílem této práce je měření efektů studené jaderné hmoty na produkci jetů v √ sNN = 200 GeV srážkách d+Au na Relativistic Heavy Ion Collider (RHIC). Po stručném teoretickém úvodu a popisu experimentálního zařízení je popsána analýza jetů a potřebné opravy. Jety jsou rekon- struovány ve srážkách p+p a d+Au z experi-mentu STAR pomocí jetového algoritmu anti − kT. Inkluzivní pT spektra jetů ve srážkách d+Au a jejich centralitní závislost jsou porovnány s referenčním měřením ve srážkách p+p a se škálováním podle binárních srážek. Korelace di- jetů jsou studovány v p+p a nejcentrálnějších srážkách d+Au pro měření kT efektu a jeho možného jaderného rozšiřování. Tyto výsledky budou rovněž použity jako referenční měření pro probíhající studie produkce jetů ve srážkách těžkých iontů na RHICu. Klíčová slova: jety, srážky d+Au, efekty studené jaderné hmoty, STAR, RHICTitle: Jet production in p+p and d+Au collisions at √ sNN = 200 GeV in STAR Author: Jan Kapitán Affiliation: Nuclear Physics Institute AS CR Supervisor: doc. Michal Šumbera, CSc., DSc., Nuclear Physics Institute AS CR Abstract: The aim of this work is to measure the effects of cold nuclear matter on jet production in √ sNN = 200 GeV d+Au collisions at Relativistic Heavy Ion Collider (RHIC). After a brief theoretical introduction and description of the experimental setup, jet analysis and the required corrections are described. The jets are reconstructed in p+p and d+Au collisions recorded by the STAR experiment using the anti − kT jet algorithm. Inclusive jet pT spectra in d+Au collisions and their centrality dependence are compared to the reference measurement in p+p collisions and to the binary collision scaling. Di-jet correlations are studied in p+p and most central d+Au collisions to measure the kT effect and its possible nuclear broadening. These results will also be used as a baseline measurement for ongoing studies of jet production in heavy-ion collisions at RHIC. Keywords: jets, d+Au collisions, cold nuclear matter effects, STAR, RHICMatematicko-fyzikální fakultaFaculty of Mathematics and Physic