Measurement and simulation of the muon-induced neutron yield in lead

A measurement is presented of the neutron production rate in lead by high energy cosmic-ray muons at a depth of 2850m water equivalent (w.e.) and a mean muon energy of 260GeV. The measurement exploits the delayed coincidences between muons and the radiative capture of induced neutrons in a highly segmented tonne scale plastic scintillator detector. Detailed Monte Carlo simulations reproduce well the measured capture times and multiplicities and, within the dynamic range of the instrumentation, the spectrum of energy deposits. By comparing measurements with simulations of neutron capture rates a neutron yield in lead of (5.78_-_0_._2_8^+^0^.^2^1) x10^-^3neutrons/muon/(g/cm^2) has been obtained. Absolute agreement between simulation and data is of order 25%. Consequences for deep underground rare event searches are discussed.Peer Reviewe

Infinite-dimensional pp-adic groups, semigroups of double cosets, and inner functions on Bruhat--Tits builldings

We construct $p$-adic analogs of operator colligations and their characteristic functions. Consider a $p$-adic group $G=GL(\alpha+k\infty, Q_p)$, its subgroup $L=O(k\infty,Z_p)$, and the subgroup $K=O(\infty,Z_p)$ embedded to $L$ diagonally. We show that double cosets $\Gamma= K\setminus G/K$ admit a structure of a semigroup, $\Gamma$ acts naturally in $K$-fixed vectors of unitary representations of $G$. For each double coset we assign a 'characteristic function', which sends a certain Bruhat--Tits building to another building (buildings are finite-dimensional); image of the distinguished boundary is contained in the distinguished boundary. The latter building admits a structure of (Nazarov) semigroup, the product in $\Gamma$ corresponds to a point-wise product of characteristic functions.Comment: new version of the paper, 47pp, 3 figure

Challenges of beta-deformation

A brief review of problems, arising in the study of the beta-deformation, also known as "refinement", which appears as a central difficult element in a number of related modern subjects: beta \neq 1 is responsible for deviation from free fermions in 2d conformal theories, from symmetric omega-backgrounds with epsilon_2 = - epsilon_1 in instanton sums in 4d SYM theories, from eigenvalue matrix models to beta-ensembles, from HOMFLY to super-polynomials in Chern-Simons theory, from quantum groups to elliptic and hyperbolic algebras etc. The main attention is paid to the context of AGT relation and its possible generalizations.Comment: 20 page

Exclusive photoproduction of pi degrees up to large values of Mandelstam variables s, t, and u with CLAS

Exclusive photoproduction cross sections have been measured for the process $\gamma p \rightarrow p\pi^0(e^+e^-(\gamma))$ with the Dalitz decay final state using tagged photon energies in the range of $E_{\gamma} = 1.275-5.425$ GeV. The complete angular distribution of the final state $\pi^0$, for the entire photon energy range up to large values of $t$ and $u$, has been measured for the first time. The data obtained show that the cross section $d\sigma/dt$, at mid to large angles, decreases with energy as $s^{-6.89\pm 0.26}$. This is in agreement with the perturbative QCD quark counting rule prediction of $s^{-7}$. Paradoxically, the size of angular distribution of measured cross sections is greatly underestimated by the QCD based Generalized Parton Distribution mechanism at highest available invariant energy $s=11$ GeV$^2$. At the same time, the Regge exchange based models for $\pi^0$ photoproduction are more consistent with experimental data.Comment: 7 pages, 6 figure

Experimental and numerical analysis of short sisal fiber-cement composites produced with recycled matrix

"Published online: 02 Jan 2017"The proper use of renewable or recycled source materials can contribute significantly to reducing the environmental impact of construction industry. In this work, cement based composites reinforced with natural fibers were developed and their mechanical behavior was characterized. To ensure the composite sustainability and durability, the ordinary Portland cement matrix was modified by adding metakaolin and the natural aggregate was substituted by 10% and 20% of recycled concrete aggregate. Compression and splitting tensile tests indicated that mechanical strength did not seem to be affected by recycled content. Flat sheets were cast in a self-compacted cement matrix and bending tests were performed to determine the first crack, postpeak strength and cracking behavior of the composites. The use of short sisal fiber as reinforcement of recycled cement matrices results in a composite with multiple cracking and increment of strength after first crack. The modeling of composites using finite element method allowed to determine the tensile stress-strain behavior of material and to design possible applications of this new sustainable material.This research was supported by CAPES (PVE Program: Project 047/2012) and CNPqinfo:eu-repo/semantics/publishedVersio

Two-pion Bose-Einstein correlations in central Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV

The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV at the Large Hadron Collider is presented. We observe a growing trend with energy now not only for the longitudinal and the outward but also for the sideward pion source radius. The pion homogeneity volume and the decoupling time are significantly larger than those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/388

Pressure adaptation is linked to thermal adaptation in salt-saturated marine habitats

The present study provides a deeper view of protein functionality as a function of temperature, salt and pressure in deep-sea habitats. A set of eight different enzymes from five distinct deep-sea (3040–4908 m depth), moderately warm (14.0–16.5°C) biotopes, characterized by a wide range of salinities (39–348 practical salinity units), were investigated for this purpose. An enzyme from a ‘superficial’ marine hydrothermal habitat (65°C) was isolated and characterized for comparative purposes. We report here the first experimental evidence suggesting that in saltsaturated deep-sea habitats, the adaptation to high pressure is linked to high thermal resistance (P value = 0.0036). Salinity might therefore increase the temperature window for enzyme activity, and possibly microbial growth, in deep-sea habitats. As an example, Lake Medee, the largest hypersaline deepsea anoxic lake of the Eastern Mediterranean Sea, where the water temperature is never higher than 16°C, was shown to contain halopiezophilic-like enzymes that are most active at 70°C and with denaturing temperatures of 71.4°C. The determination of the crystal structures of five proteins revealed unknown molecular mechanisms involved in protein adaptation to poly-extremes as well as distinct active site architectures and substrate preferences relative to other structurally characterized enzymes.European Community project MAMBA (FP7-KBBE-2008-226977). This grant BIO2011-25012 from the Spanish Ministry of Economy and Competitiveness (formerly MICINN). European Commission for ‘MicroB3’ grant (FP7-OCEAN.2011-2 (contract Nr 287589)). Government of Canada through Genome Canada and the Ontario Genomics Institute (grant 2009-OGI-ABC-1405) and U.S. National Institutes of Health (grants GM074942 and GM094585). Midwest Center for Structural Genomics).http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1462-2920hb2016Biochemistr