CLIC Drive Beam and LHC Based Fel-Nucleus Collider

The feasibility of a CLIC-LHC based FEL-nucleus collider is investigated. It is shown that the proposed scheme satisfies all requirements of an ideal photon source for the Nuclear Resonance Fluorescence method. The physics potential of the proposed collider is illustrated for a beam of Pb nuclei.Comment: Presented at PAC05, 16-20 May 2005, Knoxville, TN, US

Helioseismic Holography of an Artificial Submerged Sound Speed Perturbation and Implications for the Detection of Pre-Emergence Signatures of Active Regions

We use a publicly available numerical wave-propagation simulation of Hartlep et al. 2011 to test the ability of helioseismic holography to detect signatures of a compact, fully submerged, 5% sound-speed perturbation placed at a depth of 50 Mm within a solar model. We find that helioseismic holography as employed in a nominal "lateral-vantage" or "deep-focus" geometry employing quadrants of an annular pupil is capable of detecting and characterizing the perturbation. A number of tests of the methodology, including the use of a plane-parallel approximation, the definition of travel-time shifts, the use of different phase-speed filters, and changes to the pupils, are also performed. It is found that travel-time shifts made using Gabor-wavelet fitting are essentially identical to those derived from the phase of the Fourier transform of the cross-covariance functions. The errors in travel-time shifts caused by the plane-parallel approximation can be minimized to less than a second for the depths and fields of view considered here. Based on the measured strength of the mean travel-time signal of the perturbation, no substantial improvement in sensitivity is produced by varying the analysis procedure from the nominal methodology in conformance with expectations. The measured travel-time shifts are essentially unchanged by varying the profile of the phase-speed filter or omitting the filter entirely. The method remains maximally sensitive when applied with pupils that are wide quadrants, as opposed to narrower quadrants or with pupils composed of smaller arcs. We discuss the significance of these results for the recent controversy regarding suspected pre-emergence signatures of active regions

Production of Strange Clusters and Strange Matter in Nucleus-Nucleus Collisions at the AGS

Production probabilities for strange clusters and strange matter in Au+Au collisions at AGS energy are obtained in the thermal fireball model. The only parameters of the model, the baryon chemical potential and temperature, were determined from a description of the rather complete set of hadron yields from Si+nucleus collisions at the AGS. For the production of light nuclear fragments and strange clusters the results are similar to recent coalescence model calculations. Strange matter production with baryon number larger than 10 is predicted to be much smaller than any current experimental sensitivities.Comment: 9 Pages (no figures

Fluctuations of the number of participants and binary collisions in AA interactions at fixed centrality in the Glauber approach

In the framework of the classical Glauber approach, the analytical expressions for the variance of the number of wounded nucleons and binary collisions in AA interactions at a given centrality are presented. Along with the optical approximation term, they contain additional contact terms arising only in the case of nucleus-nucleus collisions. The magnitude of the additional contributions, e.g., for PbPb collisions at SPS energies, is larger than the contribution of the optical approximation at some values of the impact parameter. The sum of the additional contributions is in good agreement with the results of independent Monte Carlo simulations of this process. Due to these additional terms, the variance of the total number of participants for peripheral PbPb collisions and the variance of the number of collisions at all values of the impact parameter exceed several multiples of the Poisson variances. The correlator between the numbers of participants in colliding nuclei at fixed centrality is also analytically calculated.Comment: updated version; as published by Phys. Rev.

Antiferromagnetic ordering in the Kondo lattice system Yb2_2Fe3_3Si5_5

Compounds belonging to the R$_2$Fe$_3$Si$_5$ series exhibit unusual superconducting and magnetic properties. Although a number of studies have been made on the first reentrant antiferromagnet superconductor Tm$_2$Fe$_3$Si$_5$, the physical properties of Yb$_2$Fe$_3$Si$_5$ are largely unexplored. In this work, we attempt to provide a comprehensive study of bulk properties such as, resistivity, susceptibility and heat-capacity of a well characterized polycrystalline Yb$_2$Fe$_3$Si$_5$. Our measurements indicate that Yb$^{3+}$ moments order antiferromagnetically below 1.7 K. Moreover, the system behaves as a Kondo lattice with large Sommerfeld coefficient ($\gamma$) of 0.5~J/Yb mol K$^{2}$ at 0.3 K, which is well below T$_N$. The absence of superconductivity in Yb$_2$Fe$_3$Si$_5$ down to 0.3 K at ambient pressure is attributed to the presence of the Kondo effect.Comment: 10 pages, 3 figures, tex document. A fuller version has appeared in PRB. Here we have omitted the figures showing the crystal structure and the fitting of the X-ray pattern. Also the table with the lattice parameters obtained from fitting has been remove

Enhanced quasiparticle heat conduction of the multigap superconductor Lu2Fe3Si5

The thermal transport measurements have been made on the Fe-based superconductor Lu2Fe3Si5 (Tc ~ 6 K) down to a very low temperature Tc/120. The field and temperature dependences of the thermal conductivity confirm the multigap superconductivity with fully opened gaps on the whole Fermi surfaces. In comparison to MgB2 as a typical example of the multigap superconductor in a p-electron system, Lu2Fe3Si5 reveals a remarkably enhanced quasiparticle heat conduction in the mixed state. The results can be interpreted as a consequence of the electronic correlations derived from Fe 3d-electrons.Comment: 5 pages, 4 figure