Brewster window and windowless resonant spectrophones for intracavity operation

We report a new design for an acoustically resonant spectrophone well suited for intracavity operation with widely tunable lasers. Operation with Brewster angle windows or in a windowless mode is possible, and high quality factors (560 and 509, respectively) are achieved. Windowless operation permits continuous monitoring of ambient air. We discuss factors limiting the sensitivity, ∼10⁻⁷ cm⁻¹, and present a double chopping scheme capable of significantly reducing the acoustical background encountered in windowless operation. The sensitivity of the spectrophone's performance to misalignment is also examined.     

Simulation of muon-induced air showers affecting CMS tracking detectors

We study the propagation of energetic muons produced by ultrahigh energy cosmic rays which could penetrate the cavern of a giant experiment called Compact Muon Solenoid (CMS) at CERN. The present work is based on our previous simulation model proposed in [1]. We have improved this model by (1) eliminating the ambiguity via adding Landau-Pomeranchuk-Migdal effect to the Monte-Carlo code, (2) using different incidence angles of the simulated air showers, (3) defining the actual contents of the CMS cavern concrete. We estimate the energy spectrum of muons produced by air showers of primary protons and photons, which could be detected as a background in the CMS tracking detectors. Our results show that muons produced by air showers within the energy range 10¹⁷–10²⁰ eV injected to the CMS site could penetrate the cavern with cutoff energy 36.5 GeV. The article is published in the original.     

$e^{+}e^{-}\to t\bar{t}H$ including decays: on the size of background contributions

We present results for the lowest order cross sections, calculated with the complete set of standard model Feynman diagrams, of all possible detection channels of the associated production of the top quark pair and the light Higgs boson, which may be used for determination of the top–Higgs Yukawa coupling at the future e ⁺ e ⁻ linear collider. We show that, for typical particle identification cuts, the background contributions are large. In particular, the QCD background contributions are much bigger than could be expected when taking into account a possibly low virtuality of exchanged gluons. Moreover, we include the initial state radiation effects and discuss the dependence of the cross sections on the Higgs boson and top quark masses.     

Radon activity measurements around Bakreswar thermal springs

²²²Rn concentrations were measured in the bubble gases, spring waters, soil gases and in ambient air around the thermal springs at Bakreswar in West Bengal, India. This group of springs lies within a geothermal zone having exceptionally high heat flow about 230 mW/m², resembling young oceanic ridges. The spring gas has a high radon activity (～885 kBq/m³) and is rich in helium (～1.4 vol. %) with appreciably large flow rate. The measured radon exhalation rates in the soils of the spring area show extensive variations from 831 to 4550/mBqm² h while ²²²Rn concentrations in the different spring waters vary from 3.18 to 46.9 kBq/m³. Surface air at a radius of 40 m around the springs, within which is situated the Bakreswar temple complex and a group of dwellings, has radon concentration between 450 and 500 Bq/m³. In the present paper we assess the radon activity background in and around the spring area due to the different contributing sources and its possible effect on visiting pilgrims and the people who reside close to the springs.     

Peripherical processes in QED at high energies

In this review we consider the high energy processes in QED frames in peripherical kinematics. The key feature of this kinematics is that processes have a large cross section which do not decrease with the increasing of the initial center of mass energy. Two purposes to study peripheral processes are: the background processes with large total cross sections and the structure of jets in the fragmentation region.We describe the various QED peripherical processes in terms of Impact Factors and give the explicit expressions for the differential distributions and spin correlation effects, as well as estimates of the total cross section of peripheral processes in photon-photon, photon-lepton and lepton-lepton collisions.A special attention is paid to the small-angle Bhabha scattering process which is relevant for beam monitoring at LEP I, LEP II.Based on analytical properties of the amplitudes some relations (QED sum rules) between the high energy asymptotic of the cross sections of inelastic processes in e ⁺ e ^? collisions and higher order perturbative contributions to the electron Dirac and Pauli form-factors are derived.For practical using we present some loop momentum integrals.     

Monitoring of atmospheric 14CO2 in central European countries

Carbon-14 is a radionuclide with global occurrence and partly natural origin. The main anthropogenic sources of the ¹⁴C were the nuclear weapon tests, namely at the beginning of the 1960s, nowadays the nuclear energy facilities are the main sources. Maximum in the atmospheric ¹⁴C activity was observed in 1963. In the following years the considerable ¹⁴C activity decrease was due to intensive carbon deposition into oceanic water and sediments particularly. At present the ¹⁴C activity approximates the level before nuclear age, corresponding to ∼0 ‰ Δ ¹⁴C. Another actual type of anthropogenic influence is the Suess effect, i.e., the dilution of ¹⁴C by fossil carbon (fuel combustion). This effect causes a decrease of the ¹⁴C activity on a global, regional and local scale. Thus, monitoring of actual reference level of ¹⁴C activity gives a possibility to indicate local or global anthropogenic influences. This paper reporting data from the atmospheric ¹⁴CO₂ monitoring in the Czech Republic and Hungary compares the actual results with other European countries. The observed effects connected with local and regional CO₂ releases from fossil fuel combustion are discussed.     

Temperature Dependence study of19F implants in diamond by TDPAD

We present results of Time Dependent Perturbed Angular Distribution (TDPAD) studies of the temperature dependence of the electric field gradient (efg) parameters for the two residence sites of the¹⁹F ion implanted in diamond. The fractional site population results correlate well with cluster model molecular orbital calculations and support the site identifications based on these calculations. The importance of chemical effects in the probe host interaction is emphasized. In addition, the dependence of the efg on temperature is consistent with the charge-carrier governed dependence observed in many semiconductors. Honorary Research Associate of the University of the Witwatersrand.     

Dry soil diurnal quasi-periodic oscillations in soil 222Rn concentrations

²²²Rn concentrations have been monitored during the dry season in August 2009 and August 2010, in a reworked alluvial-pyroclastic soil of the Pietramelara Plain, in Southern Italy, with the aim of determining the role of atmospheric factors in producing the quasi-periodic oscillations in soil ²²²Rn concentrations reported in the literature. In this study we present the results of a detailed analysis and matching of soil ²²²Rn concentrations, meteorological and solar parameters where the observed oscillations feature a characteristic behavior with second order build-up and depletion limbs, separated by a daily maximum and minimum. All these features are clearly shown to be tied to sunrise and sunset timings and environmental radiative flux regimes. Furthermore, a significant, and previously unreported, second order correlation (r² = 0.73) between daily maximum hourly global radiation and the daily range of soil ²²²Rn concentrations has been detected, allowing estimates of the amplitude of these oscillations to be made from estimated or measured solar radiation data. The correlation has been found to be valid even in the presence of persistent patchy daytime cloudiness. In this case a daytime prolongation of the night-time build up stage and an attenuation or even suppression of daytime depletion is observed (a previously unreported effect). Neither soil cracking, nor precipitation, both suggested in some studies as causative factors for these oscillations, during the dry season appear to be necessary in explaining their occurrence. We also report the results of an artificial shading experiment, conducted in August 2009, that further support this conclusion. As soil ²²²Rn concentrations during the dry season show a characteristic daily cycle, radon monitoring in soils under these conditions necessarily has to be gauged to the timings of the daily maximum and minimum, as well as to the eventual occurrence of cloudiness and to its related effects, in order to avoid erroneous conclusions.     

Human and climate impact on 15N natural abundance of plants and soils in high-mountain ecosystems: a short review and two examples from the Eastern Pamirs and Mt. Kilimanjaro

Population pressure increasingly endangers high-mountain ecosystems such as the pastures in the Eastern Pamirs and the mountain forests on Mt. Kilimanjaro. At the same time, these ecosystems constitute the economic basis for millions of people living there. In our study, we, therefore, aimed at characterising the land-use effects on soil degradation and N-cycling by determining the natural abundance of ¹⁵N. A short review displays that δ¹⁵N of plant–soil systems may often serve as an integrated indicator of N-cycles with more positive δ¹⁵N values pointing towards N-losses. Results for the high-mountain pastures in the Eastern Pamirs show that intensively grazed pastures are significantly enriched in ¹⁵N compared to the less-exploited pastures by 3.5 ‰, on average. This can be attributed to soil organic matter degradation, volatile nitrogen losses, nitrogen leaching and a general opening of the N-cycle. Similarly, the intensively degraded savanna soils, the cultivated soils and the soils under disturbed forests on the foothill of Mt. Kilimanjaro reveal very positive δ¹⁵N values around 6.5 ‰. In contrast, the undisturbed forest soils in the montane zone are more depleted in ¹⁵N, indicating that here the N-cycle is relatively closed. However, significantly higher δ¹⁵N values characterise the upper montane forest zone at the transition to the subalpine zone. We suggest that this reflects N-losses by the recently monitored and climate change and antropogenically induced increasing fire frequency pushing the upper montane rainforest boundary rapidly downhill. Overall, we conclude that the analysis of the ¹⁵N natural abundance in high-mountain ecosystems is a purposeful tool for detecting land-use- or climate change-induced soil degradation and N-cycle opening.     

Search for a standard model Higgs boson in CMS via vector boson fusion in the H→WW→lνlν channel

We present the potential for discovering the standard model Higgs boson produced via the vector-boson fusion mechanism. We considered the decay of Higgs bosons to the W⁺W^- final state, with both W-bosons subsequently decaying leptonically. The main background is tt̄ produced in association with one or more jets. This study is based on a full simulation of the CMS detector. The result is that a signal of 5σ significance can be obtained with an integrated luminosity of 12–72 fb^-1 for Higgs boson masses in the range 130<m_H< 200 GeV. In addition, the major background can be measured directly to 7% from the data with an integrated luminosity of 30 fb^-1. We also suggest a method to determine the Higgs mass using template transverse mass distributions. PACS 14.80.Bn     

Activated Random Walkers: Facts, Conjectures and Challenges

We study a particle system with hopping (random walk) dynamics on the integer lattice ? ^d . The particles can exist in two states, active or inactive (sleeping); only the former can hop. The dynamics conserves the number of particles; there is no limit on the number of particles at a given site. Isolated active particles fall asleep at rate λ>0, and then remain asleep until joined by another particle at the same site. The state in which all particles are inactive is absorbing. Whether activity continues at long times depends on the relation between the particle density ζ and the sleeping rate λ. We discuss the general case, and then, for the one-dimensional totally asymmetric case, study the phase transition between an active phase (for sufficiently large particle densities and/or small λ) and an absorbing one. We also present arguments regarding the asymptotic mean hopping velocity in the active phase, the rate of fixation in the absorbing phase, and survival of the infinite system at criticality. Using mean-field theory and Monte Carlo simulation, we locate the phase boundary. The phase transition appears to be continuous in both the symmetric and asymmetric versions of the process, but the critical behavior is very different. The former case is characterized by simple integer or rational values for critical exponents (β=1, for example), and the phase diagram is in accord with the prediction of mean-field theory. We present evidence that the symmetric version belongs to the universality class of conserved stochastic sandpiles, also known as conserved directed percolation. Simulations also reveal an interesting transient phenomenon of damped oscillations in the activity density.     

Growth Rates and Explosions in Sandpiles

We study the abelian sandpile growth model, where n particles are added at the origin on a stable background configuration in ? ^d . Any site with at least 2d particles then topples by sending one particle to each neighbor. We find that with constant background height h≤2d?2, the diameter of the set of sites that topple has order n ^1/d . This was previously known only for h<d. Our proof uses a strong form of the least action principle for sandpiles, and a novel method of background modification. We can extend this diameter bound to certain backgrounds in which an arbitrarily high fraction of sites have height 2d?1. On the other hand, we show that if the background height 2d?2 is augmented by 1 at an arbitrarily small fraction of sites chosen independently at random, then adding finitely many particles creates an explosion (a sandpile that never stabilizes).     

89Y NMR probe of Zn induced local magnetism in YBa2(Cu1-yZny) 3O6+x

We present detailed data and analysis of the effects of Zn substitution on the planar Cu site in YBa₂Cu₃O_6+x (YBCO_6+x) as evidenced from our ⁸⁹Y NMR measurements on oriented powders. For x << 1x \ll 1 we find additional NMR lines which are associated with the Zn substitution. From our data on the intensities and temperature dependence of the shift, width, and spin-lattice relaxation rate of these resonances, we conclude that the spinless Zn 3d ¹⁰ state induces local moments on the near-neighbour (nn) Cu atoms. Additionally, we conjecture that the local moments actually extend to the farther Cu atoms with the magnetization alternating in sign at subsequent nn sites. We show that this analysis is compatible with ESR data taken on dilute Gd doped (on the Y site) and on neutron scattering data reported recently on Zn substituted YBCO_{6 + x}. For optimally doped compounds ⁸⁹Y nn resonances are not detected, but a large T-dependent contribution to the ⁸⁹Y NMR linewidth is evidenced and is also attributed to the occurence of a weak induced local moment near the Zn. These results are compatible with macroscopic magnetic measurements performed on YBCO_{6 + x} samples prepared specifically in order to minimize the content of impurity phases. We find significant differences between the present results on the underdoped YBCO_{6 + x} samples and ²⁷Al NMR data taken on Al³⁺ substituted on the Cu site in optimally doped La₂CuO₄. Further experimental work is needed to clarify the detailed evolution of the impurity induced magnetism with hole content in the cuprates.     

A renormalized perturbation theory for problems with non-trivial boundary conditions or backgrounds in two space–time dimensions

We discuss the effects of non-trivial boundary conditions or backgrounds, including non-perturbative ones, on the renormalization program for systems in two dimensions. We present an alternative renormalization procedure in which these non-perturbative conditions can be taken into account in a self-contained and, we believe, self-consistent manner. These conditions have profound effects on the properties of the system, in particular all of its n-point functions. To be concrete, we investigate these effects in the λ φ ⁴ model in two dimensions and show that the mass counterterms turn out to be proportional to the Green’s functions which have a non-trivial position dependence in these cases. We then compute the difference between the mass counterterms in the presence and absence of these conditions. We find that in the case of non-trivial boundary conditions this difference is minimum between the boundaries and infinite on them. The minimum approaches zero when the boundaries go to infinity. In the case of non-trivial backgrounds, we consider the kink background and show that the difference is again small and localized around the kink.     

Mineralogy of the clay fraction of soils from the moray cusco archaeological site: a study by energy dispersive X-ray fluorescence, X-ray diffractometry and M?ssbauer spectroscopy

The purpose of this work is to report the advances in the elemental and structural characterization of the clay fraction of soils from the terraces of the Moray Archaeological site, located 38 km north of the city of Cusco, Cusco Region. One sample was collected from each of the twelve terraces of this site and its clay fraction was separated by sedimentation. Previously the pH of the raw samples was measured resulting that all of the samples were from alkaline to strongly alkaline. Energy dispersive X-ray fluorescence (EDXRF) was used for the elemental characterization, and X-ray diffractometry (XRD) and transmission Mössbauer spectroscopy (TMS), using the ?? 14.4 keV nuclear resonance transition in ⁵⁷Fe, were used for the structural characterization of the clays and clay minerals present in each sample. The EDXRF analyses of all the samples show the presence of relatively high concentrations of sulfur in some of the samples and relatively high concentrations of calcium in all of the samples, which may be related to the high alkalinity of the samples. By XRD it is observed the presence of quartz, calcite, gypsum, cronstedtite, 2:1 phyllosilicates, and iron oxides. The mineralogical analysis of Fe by TMS shows that it is present in the form of hematite and occupying Fe^2?+? and Fe^3?+? sites in phyllosilicates, cronstedtite, and other minerals not yet identified.     

One-loop effective potential in gauged O(4) supergravity and the problem of the Λ term

We calculate the one-loop, off-shell, effective action in O(4) gauged supergravity assuming an (anti) de Sitter metric and constant scalar fields as a background. The problem of the large induced Λ term (present already for free matter fields) is stressed and the possibility of dynamical breakdown of local supersymmetry is pointed out. We illustrate our techniques and qualitative conclusions on a number of examples, including Ø⁴ theory and QED scalar potentials on a de Sitter background and an effective action in Einstein theory with a cosmological constant. Possible solutions of the Λ-term problem are also discussed.     

Energy-dispersive X-ray fluorescence study of elemental uptake in cauliflower

A ¹⁰⁹Cd radioisotope-induced energy-dispersive X-ray fluorescence (EDXRF) study has been performed on samples of cauliflower consisting of the flower, the leaves and the associated root soil. The cauliflowers were collected from farms near the main dumping site of municipal solid waste in the city of Kolkata, India and also from uncontaminated farms about 50 km away from the city. A unified calibration approach was undertaken for the elemental analysis of the samples of widely varying matrices. The present study suggests that the elemental concentrations in the root soils and leaves of the samples vary from farm to farm, whereby the concentrations of Cu, Zn and Pb in root soils of MSW-contaminated farms are higher by almost an order of magnitude compared to uncontaminated farms. But, the most notable feature of this study is the strikingly similar elemental concentrations in the edible flower part of all samples irrespective of the type of soil.     

A systematic study of the electron mobility in V-shaped quantum wires at low temperatures

We present a systematic study of the electron mobility in V-shaped AlGaAs/GaAs quantum wires taking into account the impurity (background, remote and interface) and the acoustic-phonon scattering. The electron scattering rates are calculated for wires with electron concentrations up to 10⁶ cm⁻¹ and temperatures up to 40 K by using Fermi’s golden rule. The effects of the interface roughness scattering and the alloy scattering are also discussed. The energy eigenstates and eigenvalues of the system under study are calculated using a finite difference method. We analyze the importance of each scattering mechanism on the mobility of several quantum wires of different qualities as a function of the electron concentration and the temperature.     

Radionuclide contamination of the LIRA faciliticies territory

Radiation situation at the LIRA site has been investigated. It served as a test site for 6 underground nuclear explosions. In comparison with background in the region the explosions caused a slight increase of the level of radionuclide contamination in the territory of the site. It was found that the release of ¹³⁷Xe and ⁹⁰Kr onto the surface is the main reason for formation of additional contamination with ¹³⁷Cs and ⁹⁰Sr. The peculiarities of the distribution and migration of the radionuclides in dependence on the relief and soil conditions are taken into consideration.     

Quasi-elastic pion scattering on 16O: A comparison between the Δ-hole approach and a standard first-order calculation

We present calculations of quasi-elastic pion scattering on ¹⁶O in both the Δ- hole model and a standard first-order theory. The basic approach is a modified “DWIA”, where the same in-medium πN t-operator is used for the transition and the optical potential generating the distorted pion wave functions. In order to allow a meaningful comparison with the recent SIN data, all technical complications such as background interactions, non-static vertex-corrections, 1/A effects, are taken into account, and the DWIA amplitude is evaluated without further numerical simplification like, e.g., factorization. In contrast to the closure approximation, the Δ-hole model predicts correctly the doubly differential cross sections for (π, π') on ¹⁶O over a wide range of angles and energy-losses.