125122742
J/psi production in Cu+Cu and Au+Au collisions at RHIC-PHENIX
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.
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
15426340
Type IIB Random Superstrings
We consider random superstrings of type IIB in $d$-dimensional space. The discretized action is constructed from the supersymetric matrix model, which has been proposed as a constructive definition of superstring theory. Our action is invariant under the local N=2 super transformations, and doesn't have any redundant fermionic degrees of freedom.