Cosmogenic activation of Germanium and its reduction for low background experiments

Production of $^{60}$Co and $^{68}$Ge from stable isotopes of Germanium by nuclear active component of cosmic rays is a principal background source for a new generation of $^{76}$Ge double beta decay experiments like GERDA and Majorana. The biggest amount of cosmogenic activity is expected to be produced during transportation of either enriched material or already grown crystal. In this letter properties and feasibility of a movable iron shield are discussed. Activation reduction factor of about 10 is predicted by simulations with SHIELD code for a simple cylindrical configuration. It is sufficient for GERDA Phase II background requirements. Possibility of further increase of reduction factor and physical limitations are considered. Importance of activation reduction during Germanium purification and detector manufacturing is emphasized.Comment: 10 pages, 3 tables, 6 figure

Comparative study of perindopril and perindopril metabolite pharmacokinetics using the HPLC/MS method

Perindopril is a prodrug which is converted to an active metabolite perindoprilat in the human organism. The present study led to the development of a fast and easily reproducible procedure for simultaneous detection of perinoprilat and its metabolite in plasma using HPLC with mass-spectrometric detector (LC-MS). Detection of the target substance was performed using atmospheric pressure electrospray ionization (API-ES) techniques in negative polarity in two modes: SIM1, ion, m/z=368,10 for perindopril and SIM2, ion, m/z=339,30 for perindoprilat. Retention time of perindopril was about 2,4 min, for perindoprilat - about 1,4 min. Sample processing was performed using solid-phase extraction. The method’s limit of quantification was equal to 1 ng/ml for perindopril and 1 ng/ml for perindoprilat. The developed procedure was used to analyse pharmacokinetics and bioequivalence of medicines containing 8 mg of perindopril. Values of all calculated pharmacokinetic parameters had no statistically meaningful differences. Confidence intervals obtained fall within bioequivalence criterion (80-125% for AUC and 75-133% for Сmax и Cmax/AUC). The medicines under analysis were found to be bioequivalent

NMR Determination of 2D Electron Spin Polarization at ν=1/2\nu=1/2

Using a `standard' NMR spin-echo technique we determined the spin polarization of two-dimensional electrons, confined to GaAs quantum wells, from the hyperfine shift of Ga nuclei in the wells. Concentrating on the temperature and magnetic field dependencies of spin polarization at Landau level filling factor $\nu =1/2$, we find that the results are described well by a simple model of non-interacting composite fermions, although some inconsistencies remain when the two-dimensional electron system is tilted in the magnetic field.Comment: 4 pages (REVTEX) AND 4 figures (PS

CEM03 and LAQGSM03 - new modeling tools for nuclear applications

An improved version of the Cascade-Exciton Model (CEM) of nuclear reactions realized in the code CEM2k and the Los Alamos version of the Quark-Gluon String Model (LAQGSM) have been developed recently at LANL to describe reactions induced by particles and nuclei for a number of applications. Our CEM2k and LAQGSM merged with the GEM2 evaporation/fission code by Furihata have predictive powers comparable to other modern codes and describe many reactions better than other codes; therefore both our codes can be used as reliable event generators in transport codes for applications. During the last year, we have made a significant improvements to the intranuclear cascade parts of CEM2k and LAQGSM, and have extended LAQGSM to describe photonuclear reactions at energies to 10 GeV and higher. We have produced in this way improved versions of our codes, CEM03.01 and LAQGSM03.01. We present a brief description of our codes and show illustrative results obtained with CEM03.01 and LAQGSM03.01 for different reactions compared with predictions by other models, as well as examples of using our codes as modeling tools for nuclear applications.Comment: 12 pages, 10 figures, to be published in Journal of Physics: Conference Series: Proc. Europhysics Conf. on New Trends in Nuclear Physics Applications and Technologies (NPDC19), Pavia, Italy, September 5-9, 200

Test of exotic scalar and tensor interactions in K_e3 decay using stopped positive kaons

The form factors of the decay K+ --> pi0 e+ nu (K_e3) have been determined from the comparison of the experimental and Monte Carlo Dalitz distributions containing about 10^5 K_e3 events. The following values of the parameters were obtained: lambda_+ = 0.0278 +- 0.0017(stat) +- 0.0015(syst), f_S/f_+(0) = 0.0040 +- 0.0160(stat) +- 0.0067(syst) and f_T/f_+(0) = 0.019 +- 0.080(stat) +- 0.038(syst). Both scalar f_S and tensor f_T form factors are consistent with the Standard Model predictions of zero values.Comment: 10 pages, 5 figures, contributed to the proceedings of NANP Conference, Dubna, June 19-23, 200

Spectroscopic Evidence for the Localization of Skyrmions near Nu=1 as T->0

Optically pumped nuclear magnetic resonance measurements of Ga-71 spectra were carried out in an n-doped GaAs/Al0.1Ga0.9As multiple quantum well sample near the integer quantum Hall ground state Nu=1. As the temperature is lowered (down to T~0.3 K), a ``tilted plateau'' emerges in the Knight shift data, which is a novel experimental signature of quasiparticle localization. The dependence of the spectra on both T and Nu suggests that the localization is a collective process. The frozen limit spectra appear to rule out a 2D lattice of conventional skyrmions.Comment: 4 pages (REVTEX), 5 eps figures embedded in text, published versio

Распознавание породного и возрастного состава древостоев с использованием алгоритмов на основе самокорректирующихся кодов

The basic model of the recognition of forest inventory characteristics using spectral features is represented in the framework of the problem of hyperspectral airborne imagery processing. The algorithm of multiclass supervised classification based on the error-correcting output codes underlies this model. The support vector machine method is used as the necessary binary classifier. The method of the construction of training set by using mixed forest plots is represented. Results of the retrieval of species and age composition of forest stands from hyperspectral images are represented for the selected test area. The estimate of accuracy of the retrieval of the mixed forest composition is comparable with the accuracy of ground-based forest inventory dataПредставлена базовая модель распознавания таксационных характеристик древостоев по спектральным признакам в проблеме обработки гиперспектральных авиационных изображений. Основу модели составляет алгоритм многоклассовой обучаемой классификации с использованием самокорректирующихся кодов. В качестве необходимого метода бинарной классификации применен метод опорных векторов. Описана методика использования выделов со смешанным породным составом для построения обучающего ансамбля. Приведен пример восстановления породного и возрастного состава для выбранного тестового участка по данным гиперспектральных измерений. Оценка точности восстановления породного состава соответствует точности наземных данных лесотаксаци