Geoneutrinos in Borexino

This paper describes the Borexino detector and the high-radiopurity studies and tests that are integral part of the Borexino technology and development. The application of Borexino to the detection and studies of geoneutrinos is discussed.Comment: Conference: Neutrino Geophysics Honolulu, Hawaii December 14-16, 200

Observation of mixed anisotropy in the critical susceptibility of an ultrathin magnetic film

Measurements of the magnetic susceptibility of Fe/W(110) films with thickness in the range of 1.6 to 2.4 ML Fe, show that in addition to the large response along the easy axis associated with the Curie transition, there is a much smaller, paramagnetic hard axis response that is not consistent with the 2D anisotropic Heisenberg model used to describe homogeneous in-plane ferromagnets with uniaxial anisotropy. The shape, amplitude, and peak temperature of the hard axis susceptibility, as well as its dependence upon layer completion close to 2.0 ML, indicate that inhomogeneities in the films create a system of mixed anisotropy. A likely candidate for inhomogeneities that are magnetically relevant in the critical region are the closed lines of step edges associated with the incomplete layers. According to the Harris criterion, the existence of magnetically relevant inhomogeneities may alter the critical properties of the films from those of a 2D Ising model. Experiments in the recent literature are discussed in this context.Comment: 9 two-column pages, 6 figures. This replacement has a new title and abstract, and one additional figur

Verification-guided modelling of salience and cognitive load

Well-designed interfaces use procedural and sensory cues to increase the cognitive salience of appropriate actions. However, empirical studies suggest that cognitive load can influence the strength of those cues. We formalise the relationship between salience and cognitive load revealed by empirical data. We add these rules to our abstract cognitive architecture, based on higher-order logic and developed for the formal verification of usability properties. The interface of a fire engine dispatch task from the empirical studies is then formally modelled and verified. The outcomes of this verification and their comparison with the empirical data provide a way of assessing our salience and load rules. They also guide further iterative refinements of these rules. Furthermore, the juxtaposition of the outcomes of formal analysis and empirical studies suggests new experimental hypotheses, thus providing input to researchers in cognitive science

Overview of Solid Target Studies for a Neutrino Factory

The UK pro­gramme of high power tar­get de­vel­op­ments for a Neu­tri­no Fac­to­ry is cen­tred on the study of high-Z ma­te­ri­als (tung­sten, tan­ta­lum). A de­scrip­tion of life­time shock tests on can­di­date ma­te­ri­als is given as part of the re­search into a solid tar­get so­lu­tion. A fast high cur­rent pulse is ap­plied to a thin wire of the sam­ple ma­te­ri­al and the life­time mea­sured from the num­ber of puls­es be­fore fail­ure. These mea­sure­ments are made at tem­per­a­tures up to ~2000 K. The stress on the wire is cal­cu­lat­ed using the LS-DY­NA code and com­pared to the stress ex­pect­ed in the real Neu­tri­no Fac­to­ry tar­get. It has been found that tan­ta­lum is too weak to sus­tain pro­longed stress at these tem­per­a­tures but a tung­sten wire has reached over 26 mil­lion puls­es (equiv­a­lent to more than ten years of op­er­a­tion at the Neu­tri­no Fac­to­ry). An ac­count is given of the op­ti­mi­sa­tion of sec­ondary pion pro­duc­tion from the tar­get and the is­sues re­lat­ed to mount­ing the tar­get in the muon cap­ture solenoid and tar­get sta­tion are dis­cussed

Tungsten Behavior at High Temperature and High Stress

Re­cent­ly re­port­ed re­sults on the tung­sten life­time/fa­tigue tests under con­di­tions ex­pect­ed in the Neu­tri­no Fac­to­ry tar­get have strength­ened the case of solid tar­get op­tion for a Neu­tri­no Fac­to­ry. This paper gives de­scrip­tion of the de­tailed mea­sure­ments of the tung­sten prop­er­ties at high tem­per­a­ture and high stress. We have per­formed ex­ten­sive set of mea­sure­ments of the sur­face dis­place­ment and ve­loc­i­ty of the tung­sten wires that were stressed by pass­ing a fast, high cur­rent pulse through a thin sam­ple. Ra­di­al and lon­gi­tu­di­nal os­cil­la­tions of the wire were mea­sured by a Laser Doppler Vi­brom­e­ter. The wire was op­er­at­ed at tem­per­a­tures of 300-2500 K by ad­just­ing the pulse rep­e­ti­tion rate. In doing so we have tried to sim­u­late the con­di­tions (high stress and tem­per­a­ture) ex­pect­ed at the Neu­tri­no Fac­to­ry. Most im­por­tant re­sult of this study is an ex­per­i­men­tal con­fir­ma­tion that strength of tung­sten re­mains high at high tem­per­a­ture and high stress. The ex­per­i­men­tal re­sults have been found to agree very well with LS-DY­NA mod­elling re­sults

Consequences of energy conservation in relativistic heavy-ion collisions

Complete characterization of particle production and emission in relativistic heavy-ion collisions is in general not feasible experimentally. This work demonstrates, however, that the availability of essentially complete pseudorapidity distributions for charged particles allows for a reliable estimate of the average transverse momenta and energy of emitted particles by requiring energy conservation in the process. The results of such an analysis for Au+Au collisions at sqrt{s_{NN}}= 130 and 200 GeV are compared with measurements of mean-p_T and mean-E_T in regions where such measurements are available. The mean-p_T dependence on pseudorapidity for Au+Au collisions at 130 and 200 GeV is given for different collision centralities.Comment: 8 pages, 8 figures, Submitted to Phys. Rev.

Elliptic Flow, Initial Eccentricity and Elliptic Flow fluctuations in Heavy Ion Collisions at RHIC

We present measurements of elliptic flow and event-by-event fluctuations established by the PHOBOS experiment. Elliptic flow scaled by participant eccentricity is found to be similar for both systems when collisions with the same number of participants or the same particle area density are compared. The agreement of elliptic flow between Au+Au and Cu+Cu collisions provides evidence that the matter is created in the initial stage of relativistic heavy ion collisions with transverse granularity similar to that of the participant nucleons. The event-by-event fluctuation results reveal that the initial collision geometry is translated into the final state azimuthal particle distribution, leading to an event-by-event proportionality between the observed elliptic flow and initial eccentricity.Comment: To appear in the proceedings of the Lake Louise Winter Institute 2007. The proceedings of the institute will be published by World Scientifi

Energy and system dependence of high-pTp_T triggered two-particle near-side correlations

Previous studies have indicated that the near-side peak of high-$p_T$ triggered correlations can be decomposed into two parts, the \textit{Jet} and the \textit{Ridge}. We present data on the yield per trigger of the \textit{Jet} and the \textit{Ridge} from $d+Au$, $Cu+Cu$ and $Au+Au$ collisions at $\sqrt{s_{NN}}$ = 62.4 GeV and 200 GeV and compare data on the \textit{Jet} to PYTHIA 8.1 simulations for $p+p$. PYTHIA describes the \textit{Jet} component up to a scaling factor, meaning that PYTHIA can provide a better understanding of the \textit{Ridge} by giving insight into the effects of the kinematic cuts. We present collision energy and system dependence of the \textit{Ridge} yield, which should help distinguish models for the production mechanism of the \textit{Ridge}.Comment: 4 pages, 6 figures, proceedings for Hot Quarks in Estes Park, Colorad