Optical and Magnetooptical Spectroscopy of the Nanostructural Multilayered Films: Possible Applications

The aim of the paper is to show the potential of the spectroscopic ellipsometry and magnetooptical (MO) spectroscopy for probing of the multilayered films (MLF) with sublayer thickness of about a few nanometres. The main approach applied by us is based on the comparison of the experimental optical and MO properties with the simulated ones based on various models of the MLF. Specifically, as shown, such an approach can be useful for studying the nature of unusual MO properties and the interfaces in MLF comprising the noble and 3d-transition metals (3d-TM). The high sensitivity of the applied spectroscopic methods for the monitoring of the solid-state reactions in the 3d-TM/Si MLF induced by ion-beam treatment or by thermal annealing is also demonstrated. The optical properties of various silicides formed spontaneously or induced by various treatments at interfaces are evaluated experimentally and compared with the results of first-principle calculations.В данной работе показаны возможности спектральной эллипсометрии и магнитооптической (МО) спектроскопии для изучения структуры и особенностей физических свойств многослойных металлических пленок (МСП) с толщинами составляющих слоев порядка единиц нанометров. Основной подход исследования базируется на сравнении экспериментально измеренных оптических и МО свойств МСП с модельными, полученными для различных моделей структуры МСП. Было показано, что данный подход позволяет выяснить природу необычных МО свойств, а также структуру интерфейсной области в МСП, состоящих из слоев благородных и 3d-переходных металлов (ПМ). Также в работе продемонстрирована высокая чувствительность спектральной эллипсометрии для изучения твердотельных реакций в МСП 3d-ПМ/Si, вызванных ионной бомбардировкой или термическим отжигом. Оптические свойства различных силицидов 3d-ПМ, сформированных спонтанно либо в результате различных воздействий на МСП, были изучены экспериментально и сравнены с результатами теоретических первопринципных расчетов.В даній роботі показані можливості спектральної еліпсометрії та магнітооптичної (МО) спектроскопії для вивчення структури та особливостей фізичних властивостей багатошарових металевих плівок (БШП) з товщинами складаючих їх шарів порядку одиниць нанометрів. Основний підхід дослідження базується на порівнянні експериментально одержаних оптичних та МО властивостей БШП з модельними, що були одержані для різних моделей структури БШП. Було показано, що даний підхід дозволяє визначити природу незвичайних МО властивостей, а також природу інтерфейсної області БШП, що складаються з шарів благородних та 3d-перехідних металів (ПМ). В роботі також паказана висока чутливість спектральної еліпсометрії для вивчення твердотільних реакцій в БШП 3d-ПМ/Si, зумовлених іонним бомбардуванням або термічним відпалом. Оптичні властивості різних силіцидів 3d-ПМ, що було зформовані спонтанно або завдяки зовнішньому впливу, були вивчені експериментально та порівняні з результатами теоретичних першопринципних розрахунків

High statistic measurement of the K- -> pi0 e- nu decay form-factors

The decay K- -> pi0 e- nu is studied using in-flight decays detected with the ISTRA+ spectrometer. About 920K events are collected for the analysis. The lambda+ slope parameter of the decay form-factor f+(t) in the linear approximation (average slope) is measured: lambda+(lin)= 0.02774 +- 0.00047(stat) +- 0.00032(syst). The quadratic contribution to the form-factor was estimated to be lambda'+ = 0.00084 +- 0.00027(stat) +- 0.00031(syst). The linear slope, which has a meaning of df+(t)/dt|_{t=0} for this fit, is lambda+ = 0.02324 +- 0.00152(stat) +- 0.00032(syst). The limits on possible tensor and scalar couplings are derived: f_{T}/f_{+}(0)=-0.012 +- 0.021(stat) +- 0.011$(syst), f_{S}/f_{+}(0)=-0.0037^{+0.0066}_{-0.0056}(stat) +- 0.0041(syst).Comment: 11 pages, 8 figures. Accepted by Phys.Lett.

Extraction of Kaon Formfactors from K^- -> mu^- nu_mu gamma Decay at ISTRA+ Setup

The radiative decay K->mu nu gamma has been studied at ISTRA+ setup in a new kinematical region. About 22K events of K^- -> mu^- nu_mu gamma have been observed. The sign and value of Fv-Fa have been measured for the first time. The result is Fv-Fa=0.21(4)(4).Comment: 11 pages, 21 figures, submitted to Phys. Lett.

Search for light pseudoscalar sgoldstino in K- decays

A search for the light pseudoscalar sgoldstino production in the three body K- decay K-->pipi0P has been performed with the ISTRA+ detector exposed to the 25 GeV negative secondary beam of the U70 proton synchrotron. No signal is seen. An upper limit for the branching ratio Br(K->pipi0P), at 90% confidence level, is found to be around 9*10**-6 in the effective mass m(P) range from 0 till 200 MeV, excluding the region near m(pi0) where it degrades to 3.5*10**-5.Comment: 10 pages, LATEX, 8 EPS figures, revised version, to be published in Phys.Lett.

Search for Heavy Neutrino in K->mu nu_h(nu_h-> nu gamma) Decay at ISTRA+ Setup

Heavy neutrino nu_h with m_h < 300MeV/c^2 can be effectively searched for in kaon decays. We put upper limits on mixing matrix element |U_mu_h}|^2 for radiatively decaying nu_h from K->mu nu_h (nu_h -> nu gamma) decay chain in the following parameter region: 30MeV/c^2 < m_h < 80MeV/c^2; 10^{-11}sec < tau_h < 10^{-9}sec. For the whole region |U_{mu h}|^2 < 5 x 10^{-5} for Majorana type of nu_h and | U_{\mu h}|^2 < 8 x 10^{-5} for the Dirac case.Comment: Published in Phys. Lett.

Measurement of the Dalitz plot slope parameters for K- -> pi0 pi0 pi- decay using ISTRA+ detector

The Dalitz plot slope parameters g, h and k for the K- -> pi0 pi0 pi- decay have been measured using in-flight decays detected with the ISTRA+ setup operating in the 25 GeV negative secondary beam of the U-70 PS. About 252 K events with four-momenta measured for the pi- and four involved photons were used for the analysis. The values obtained g=0.627+/-0.004(stat)+/-0.010(syst), h=0.046+/-0.004(stat)+/-0.012(syst), k=0.001+/-0.001(stat)+/-0.002(syst) are consistent with the world averages dominated by K+ data, but have significantly smaller errors.Comment: LaTeX, 10 pages, 8 eps-figures, update of IHEP 2002-1

High statistic study of the K- -> pi0 mu- nu decay

The decay K- -> pi0 mu- nu has been studied using in-flight decays detected with the "ISTRA+" spectrometer. About 540K events were collected for the analysis. The lambda+ and lambda0 slope parameters of the decay form-factors f+(t), f0(t) have been measured : lambda+ = 0.0277+-0.0013 (stat)+-0.0009 (syst), lambda0 = 0.0183+-0.0011(stat)+-0.0006(syst), and d(lambda0)/d(lambda+)=-0.348. The limits on the possible tensor and scalar couplings have been derived: fT/f+(0)=-0.0007 +- 0.0071, fS/f+(0)=0.0017 +- 0.0014. No visible non-linearity in the form-factors have been observed.Comment: 11 pages, 8 EPS figures, accepted by Physics Letters

High statistics study of the K- -> pi0 e- nu decay

The decay K- -> pi0 e- nu has been studied using in-flight decays detected with the "ISTRA+" spectrometer working at the 25 GeV negative secondary beam of the U-70 PS. About 550K events were used for the analysis. The lambda+ parameter of the vector form-factor has been measured: lambda+ = 0.0286 +- 0.0008 (stat) +- 0.0006(syst). The limits on the possible tensor and scalar couplings have been obtained: f(T)/f+(0)=0.021 +0.064 -0.075 (stat) +- 0.026(syst) ; f(S)/f+(0)=0.002 +0.020 -0.022 (stat) +- 0.003(syst)Comment: LaTeX-2e, epsfig.sty, 10 pages, 7 figures in EPS forma

Measurement of the photon+b+b-jet production differential cross section in ppˉp\bar{p} collisions at \sqrt{s}=1.96~\TeV

We present measurements of the differential cross section dsigma/dpT_gamma for the inclusive production of a photon in association with a b-quark jet for photons with rapidities |y_gamma|< 1.0 and 30<pT_gamma <300 GeV, as well as for photons with 1.5<|y_gamma|< 2.5 and 30< pT_gamma <200 GeV, where pT_gamma is the photon transverse momentum. The b-quark jets are required to have pT>15 GeV and rapidity |y_jet| < 1.5. The results are based on data corresponding to an integrated luminosity of 8.7 fb^-1, recorded with the D0 detector at the Fermilab Tevatron $p\bar{p}$ Collider at sqrt(s)=1.96 TeV. The measured cross sections are compared with next-to-leading order perturbative QCD calculations using different sets of parton distribution functions as well as to predictions based on the kT-factorization QCD approach, and those from the Sherpa and Pythia Monte Carlo event generators.Comment: 10 pages, 9 figures, submitted to Phys. Lett.