Crystals for high-energy calorimetry in extreme environments

Crystals are used as a homogeneous calorimetric medium in many high-energy physics experiments. For some experiments, performance has to be ensured in very difficult operating conditions, like a high radiation environment, very large particle fluxes, high collision rates, placing constraints on response and readout time. An overview is presented of recent achievements in the field, with particular attention given to the performance of Lead Tungstate (PWO) crystals exposed to high particle fluxes.Comment: To be published in Proc. of the Meeting of the Division of Particles and Fields of the American Physical Society, DPF2004 (Riverside, USA, August 26th to 31st, 2004

Experimental probing of the anisotropy of the empty p states near the Fermi level in MgB2

We have studied the Boron K-edge in the superconductor MgB2 by electron energy loss spectroscopy (EELS) and experimentally resolved the empty p states at the Fermi level that have previously been observed within an energy window of 0.8eV by soft x-ray absorption spectroscopy. Using angular resolved EELS, we find that these states at the immediate edge onset have pxy character in agreement with predictions from first-principle electronic structure calculations.Comment: 15 pages, 5 figure

Technological innovations at the onset of the Mid-Pleistocene Climate Transition in high-latitude East Asia

The interplay between Pleistocene climatic variability and hominin adaptations to diverse terrestrial ecosystems is a key topic in human evolutionary studies. Early and Middle Pleistocene environmental change and its relation to hominin behavioural responses has been a subject of great interest in Africa and Europe, though little information is available for other key regions of the Old World, particularly from Eastern Asia. Here we examine key Early Pleistocene sites of the Nihewan Basin, in high-latitude northern China, dating between ∼1.4 to 1.0 million years ago (Ma). We compare stone tool assemblages from three Early Pleistocene sites in the Nihewan Basin, including detailed assessment of stone tool refitting sequences at the ∼1.1 Ma-old site of Cenjiawan. Increased toolmaking skills and technological innovations are evident in the Nihewan Basin at the onset of the Mid-Pleistocene Climate Transition (MPT). Examination of the lithic technology of the Nihewan sites, together with an assessment of other key Palaeolithic sites of China, indicates that toolkits show increasing diversity at the outset of the MPT and in its aftermath. The overall evidence indicates the adaptive flexibility of early hominins to ecosystem changes since the MPT, though regional abandonments are also apparent in high-latitudes, likely owing to cold and oscillating environmental conditions. The view presented here sharply contrasts with traditional arguments that stone tool technologies of China are homogeneous and continuous over the course of the Early Pleistocene.Introduction Results - Stone-tool-knapping skills recorded in the Cenjiawan assemblage - Technological comparisons of the Nihewan Basin assemblages Discussio

Quantum Algorithms for Finding Constant-sized Sub-hypergraphs

We develop a general framework to construct quantum algorithms that detect if a $3$-uniform hypergraph given as input contains a sub-hypergraph isomorphic to a prespecified constant-sized hypergraph. This framework is based on the concept of nested quantum walks recently proposed by Jeffery, Kothari and Magniez [SODA'13], and extends the methodology designed by Lee, Magniez and Santha [SODA'13] for similar problems over graphs. As applications, we obtain a quantum algorithm for finding a $4$-clique in a $3$-uniform hypergraph on $n$ vertices with query complexity $O(n^{1.883})$, and a quantum algorithm for determining if a ternary operator over a set of size $n$ is associative with query complexity $O(n^{2.113})$.Comment: 18 pages; v2: changed title, added more backgrounds to the introduction, added another applicatio

Relationship Between the Azimuthal Dependencies of Nuclear Modification Factor and Ridge Yield

The azimuthal angular dependence of the nuclear modification factor R_{AA}(p_T, phi,N_{part}) recently obtained by PHENIX is related at low p_T to the trigger phi dependence of the ridge yield as measured by STAR in a framework in which the azimuthal anisotropy is driven by semihard scattering near the surface. Careful consideration of the initial geometry leads to the determination of a surface segment in which the production of semihard partons are responsible for the phi dependence of the inclusive distribution on the one hand, and for the angular correlation in ridge phenomenology on the other. With v_2 also being well reproduced along with R_{AA} and ridge yield, all relevant phi dependencies in heavy-ion collisions can now be understood in a unified description that emphasizes the ridge production whether or not a trigger is used.Comment: This expanded version has additional discussions that render the paper more readable without change of substance. It is to be published in Phys. Rev.