10281433
Evaluation of test structures for the novel n + -in-p pixel and strip sensors for very high radiation environments
Abstract Radiation-tolerant n + -in-p silicon sensors were developed for use in very high radiation environments. Novel n + -in-p silicon strip and pixel sensors and test structures were fabricated, tested and evaluated, in order to understand the designs implemented. The resistance between the n + implants (interstrip resistance), the electric potential of the p-stop, and the punch-through-protection (PTP) onset voltage were measured before and as a function of fluence after irradiation. The technology computer-aided design (TCAD) simulations were used to understand the radiation damage and fluence dependence of the structures. The decrease in the interstrip resistance is a consequence of increased leakage current. The decrease in the electric potential of the p-stop results from a build-up of positive charge in the silicon–silicon oxide interface. The decrease and subsequent increase in the PTP onset voltages results from the interface charge build-up and an increase in acceptor states.
125578451
Production of Charmonia in Cu+Cu and p+p Collisions at $\sqrt{s_{NN}}$=200GeV
174792146
Development of a time projection chamber using gas electron multipliers ( GEM – TPC )
We developed a prototype time projection chamber using gas electron multipliers (GEM–TPC) for high energy heavy ion collision experiments. To investigate its performance, we conducted a beam test with three kinds of gases (Ar(90%)–CH4(10%), Ar(70%)–C2H6(30%) and CF4). Detection efficiency of 99%, and spatial resolution of 79mm in the pad-row direction and 313mm in the drift direction were achieved. The test results show that the GEM–TPC meets the requirements for high energy heavy ion collision experiments. The configuration and performance of the GEM–TPC are described. r 2006 Elsevier B.V. All rights reserved. PACS: 29.40.Cs; 29.40.Gx; 25.75. q
119478986
A Hadron blind detector for the PHENIX experiment at RHIC
The PHENIX collaboration has designed a conceptually new Hadron Blind Detector (HBD) for electron identification in high density hadron environment. The HBD will identify low momentum electron-positron pairs to reduce the combinatorial background in the mass region below 1 GeV/c2. The HBD shall be installed in PHENIX during the 2007 physics run.The HBD is a windowless proximity focusing Cherenkov detector with a radiator length of 50 cm, CsI photocathode and three layers of Gas Electron Multipliers (GEM) for gas amplification. Pure CF4 serves both as a radiator and as a detector gas. The radiation budget of the device is less than 3% of a radiation length.
119267194
Early B-physics at ATLAS
The B-physics program at the ATLAS experiment, which covers the mid-rapidity region, complements that at the dedicated LHCb experiment, which covers the forward rapidity region. At the early stage of the LHC operation, the program concentrated on understanding of detector performance and measurements of quarkonia and D mesons. This article presents recent results of the B-physics program at ATLAS.
41470188
Prompt reconstruction of ATLAS data in 2010 and 2011
Excluding a short duration in 2008, the LHC started regular operation in November 2009 and has since then provided billions of collision events that were recorded by the ATLAS experiment and promptly reconstructed at an on-site computing farm. The prompt reconstruction chain takes place in two steps and is designed to provide high-quality data for physics publications with as little delay as possible. The first reconstruction step is used for data quality assessment and determining calibration constants and beam spot position, so that this information can be used in the second reconstruction step to optimize the reconstruction performance. After the technical stop of the LHC at the end of 2010, the prompt reconstruction chain had to deal with greatly increased luminosity and pileup conditions. To allow the computing resources to cope with this increased dataflow, without developing a backlog, recently significant improvements have been made in the ATLAS reconstruction software to reduce CPU time and file sizes for the produced datasets.
18734752
Grand-Canonical Simulation of Two-Dimensional Simplicial Gravity
The string susceptibility exponents of dynamically triangulated 2-dimensional surfaces with various topologies, such as a sphere, torus and double-torus, were calculated by the grand-canonical Monte Carlo method. These simulations were made for surfaces coupled to $d$-Ising spins ($d$=0,1,2,3,5). In each simulation the area of surface was constrained to within 1000 to 3000 of triangles, while maintaining the detailed-balance condition. The numerical results show excellent agreement with theoretical predictions as long as $d \leq 2$.