Simulation of Time-Resolved Vibronic Spectra and the possibility of analyzing molecules with similar apectral properties

The possibility of using time-resolved vibronic spectroscopy for spectral analysis of mixtures of chemical compounds with similar optical properties, when traditional methods are inefficient, is demonstrated by using the method of computer simulation. The analysis is carried out by the example of molecules of a series of polyenes (butadiene, hexatraene, octatetraene, decapentaene, and decatetraene), their various cis- and trans-rotational isomers, and phenyl-substituted polyenes. Ranges of relative concentrations of molecules similar in their spectral properties, where reliable interpretation of time-resolved spectra of mixtures and both qualitative and quantitative analyses are possible, are determined. The use of computer simulation methods for oprimizing full-scale experiments in femtosecond spectroscopy is shown to hold much promise

Comment on ``Evidence for Narrow Baryon Resonances in Inelastic pp Scattering''

Compton scattering data are sensitive to the existence of low-mass resonances reported by Tatischeff et al. We show that such states, with their reported properties, are excluded by previous Compton scattering experiments.Comment: One page, submitted to PR

Cooper-pair coherence in a superfluid Fermi-gas of atoms

We study the coherence properties of a trapped two-component gas of fermionic atoms below the BCS critical temperature. We propose an optical method to investigate the Cooper-pair coherence across different regions of the superfluid. Near-resonant laser light is used to induce transitions between the two coupled hyperfine states. The beam is split so that it probes two spatially separate regions of the gas. Absorption of the light in this interferometric scheme depends on the Cooper-pair coherence between the two regions.Comment: 10 pages, 5 figures. Submitted to J. Phys. B as a proceedings of the Salerno 2001 BEC worksho

Singular perturbation theory for interacting fermions in two dimensions

We consider a system of interacting fermions in two dimensions beyond the second-order perturbation theory in the interaction. It is shown that the mass-shell singularities in the self-energy, arising already at the second order of the perturbation theory, manifest a non-perturbative effect: an interaction with the zero-sound mode. Resumming the perturbation theory for a weak, short-range interaction and accounting for a finite curvature of the fermion spectrum, we eliminate the singularities and obtain the results for the quasi-particle self-energy and the spectral function to all orders in the interaction with the zero-sound mode. A threshold for emission of zero-sound waves leads a non-monotonic variation of the self-energy with energy (or momentum) near the mass shell. Consequently, the spectral function has a kink-like feature. We also study in detail a non-analytic temperature dependence of the specific heat, $C(T)\propto T^2$. It turns out that although the interaction with the collective mode results in an enhancement of the fermion self-energy, this interaction does not affect the non-analytic term in $C(T)$ due to a subtle cancellation between the contributions from the real and imaginary parts of the self-energy. For a short-range and weak interaction, this implies that the second-order perturbation theory suffices to determine the non-analytic part of $C(T)$. We also obtain a general form of the non-analytic term in $C(T)$, valid for the case of a generic Fermi liquid, \emph{i.e.}, beyond the perturbation theory.Comment: 53 pages, 10 figure

Quantum gases in trimerized kagom\'e lattices

We study low temperature properties of atomic gases in trimerized optical kagom\'{e} lattices. The laser arrangements that can be used to create these lattices are briefly described. We also present explicit results for the coupling constants of the generalized Hubbard models that can be realized in such lattices. In the case of a single component Bose gas the existence of a Mott insulator phase with fractional numbers of particles per trimer is verified in a mean field approach. The main emphasis of the paper is on an atomic spinless interacting Fermi gas in the trimerized kagom\'{e} lattice with two fermions per site. This system is shown to be described by a quantum spin 1/2 model on the triangular lattice with couplings that depend on the bond directions. We investigate this model by means of exact diagonalization. Our key finding is that the system exhibits non-standard properties of a quantum spin-liquid crystal: it combines planar antiferromagnetic order in the ground state with an exceptionally large number of low energy excitations. The possibilities of experimental verification of our theoretical results are critically discussed.Comment: 19 pages/14 figures, version to appear in Phys. Rev. A., numerous minor corrections with respect to former lanl submissio

Біохімічні показники життєдіяльності насіння гіркокаштанів, найпоширеніших у західному регіоні України

The authors have identified the biochemical indicators of vitality of different kinds of seeds of horse chestnut in order to search for species and forms resistant against the chestnut leaf-mining moth (Cameraria ohridella Desch. & Dem (Lepidoptera, Gracillariidae)). These parameters were studied for four species of horse chestnut trees by comparing their content in relatively clean areas and in areas of intense anthropogenic and technogenic pollution of the Western region of Ukraine. The ersearch used approved methods of biochemical studies: ash analysis – seeds after combustion in a muffle furnace at a temperature of 450 °C; content "raw" fat – by Rushkovskiy; determination of macro- and microelements – by flame photometry; protein content was determined using Bradford reagent; reduced glutathione – Hryshko method using Ellman's reagent. The content of ash in relatively clean areas in the seeds of the test species of horse chestnut does not differ significantly, and in the contaminated areas anthropogenic decreases to 2 % for all species. According to the content of mineral elements in relatively clean areas of strong performance recorded in the seeds of the horse chestnut trees Pavia and eight stamina and less in ordinary horse and red chestnut. In contaminated areas potassium and calcium content decreased and sodium increased, especially in the horse chestnut. Within conditionally clean zones horse chestnut seed faba ordinary inherent maximum values ​​of all species studied the content of copper and zinc, and the minimum content of manganese. The lead content was almost the same in all species. Cadmium content in horse chestnut, eight stamina and meat-red was scanty. The brown Pavia except cadmium fixed maximum content of iron, nickel, chromium minimum level. The seeds of all the species studied by Buckeyes observed increased activity of lipid peroxidation and reduced glutathione content. The dynamics of biochemical parameters of studied seed by Buckeyes evidence of their individualization within a species. In this case, the horse chestnut trees and the stress in the ordinary soil and climatic conditions, with additional reduction in viability chestnut moth characterized Minira as the most negative change in metabolism compared to the three other species investigated, and consequently less biological resistance.Визначено біохімічні показники життєдіяльності насіння гіркокаштанів для пошуку стійких проти каштанової мінуючої молі (Cameraria ohridella Desch. & Dem (Lepidoptera, Gracillariidaе)) видів і форм. Для експериментів у насінний рік в умовно чистих зонах і в місцях інтенсивного антропогенно-техногенного забруднення відібрано насіння чотирьох видів гіркокаштанів. Заготівлю насіння здійснено способом збирання із поверхні землі у період найінтенсивнішого його опадання. Досліджено вміст у насінні гіркокаштанів низки фізіолого-біологічних, морфологічних та основних біохімічних показників (білка, розчинних вуглеводнів і "сирого жиру"), золи, макро- і мікроелементів в умовно чистих зонах і в місцях інтенсивного антропогенно-техногенного забруднення. Встановлено рівень активності перекисного окислення ліпідів (ПОЛ) та вміст відновленого глутатіону. Вивчені зміни фізіолого-біологічних та біохімічних показників свідчать, що порівняно із трьома іншими досліджуваними видами дерева гіркокаштана кінського звичайного у стресових ґрунтово-кліматичних умовах великого міста з додатковим зниженням життєздатності каштановою мінуючою міллю характеризуються найбільшими негативними змінами у метаболізмі. Це свідчить, що за зростання в аналогічних ґрунтово-кліматичних умовах та за подібного навантаження чинників антропогенно-техногенного впливу, дерева і насадження жовтоквіткового (Aesculus octаndra Marsh.) і червоноквіткових видів гіркокаштанів (Aesculus pavia L. і Aesculus carnea Hayne) на сьогодні є життєво стійкішими, ніж дерева і насадження найпоширенішого у регіоні гіркокаштана кінського звичайного (Aesculus hippocastanum L.)

Energy and time resolution for a LYSO matrix prototype of the Mu2e experiment

We have measured the performances of a LYSO crystal matrix prototype tested with electron and photon beams in the energy range 60$-$450 MeV. This study has been carried out to determine the achievable energy and time resolutions for the calorimeter of the Mu2e experiment.Comment: 2 pages, 3 figures, 13th Pisa Meeting on Advanced Detector

The Mu2e undoped CsI crystal calorimeter

The Mu2e experiment at Fermilab will search for Charged Lepton Flavor Violating conversion of a muon to an electron in an atomic field. The Mu2e detector is composed of a tracker, an electromagnetic calorimeter and an external system, surrounding the solenoid, to veto cosmic rays. The calorimeter plays an important role to provide: a) excellent particle identification capabilities; b) a fast trigger filter; c) an easier tracker track reconstruction. Two disks, located downstream of the tracker, contain 674 pure CsI crystals each. Each crystal is read out by two arrays of UV-extended SiPMs. The choice of the crystals and SiPMs has been finalized after a thorough test campaign. A first small scale prototype consisting of 51 crystals and 102 SiPM arrays has been exposed to an electron beam at the BTF (Beam Test Facility) in Frascati. Although the readout electronics were not the final, results show that the current design is able to meet the timing and energy resolution required by the Mu2e experiment.Comment: 6 pages, 8 figures, proceedings of the "Calorimetry for the high energy frontier (CHEF17)" conference, 2-6 October 2017, Lyon, Franc