Binding Energy of Charged Excitons in ZnSe-based Quantum Wells

Excitons and charged excitons (trions) are investigated in ZnSe-based quantum well structures with (Zn,Be,Mg)Se and (Zn,Mg)(S,Se) barriers by means of magneto-optical spectroscopy. Binding energies of negatively () and positively (X+) charged excitons are measured as functions of quantum well width, free carrier density and in external magnetic fields up to 47 T. The binding energy of shows a strong increase from 1.4 to 8.9 meV with decreasing quantum well width from 190 to 29 A. The binding energies of X+ are about 25% smaller than the binding energy in the same structures. The magnetic field behavior of and X+ binding energies differ qualitatively. With growing magnetic field strength, increases its binding energy by 35-150%, while for X+ it decreases by 25%. Zeeman spin splittings and oscillator strengths of excitons and trions are measured and discussed

Search for rare Phi decays in pi+ pi_ gamma final state

A search for phi radiative decays has been performed using a data sample of about 2.0 million phi decays collected by the CMD-2 detector at VEPP-2M collider in Novosibirsk. From the selected e+ e- -> pi+ pi- gamma events the following results were obtained: B(phi -> f0(980) gamma) < 1x10-4 for destructive and B(phi -> f0(980) gamma) < 7x10-4 for constructive interference with the Bremsstrahlung process respectively, B(phi -> gamma -> pi+ pi- gamma) 20 MeV, B(phi -> rho gamma) < 7x10-4. From the selected e+ e- -> mu+ mu- gamma events B(phi -> mu+ mu- gamma) = (2.3+-1.0)x10-5 has been obtained for E of gamma> 20 MeV. The upper limit on the P,CP-violating decay eta -> pi+ pi- has also been placed: B(eta -> pi+ pi-) < 9x10-4 . All upper limits are at 90 % C.L.Comment: 18 pages, 7 figure

Study of doubly strange systems using stored antiprotons

Bound nuclear systems with two units of strangeness are still poorly known despite their importance for many strong interaction phenomena. Stored antiprotons beams in the GeV range represent an unparalleled factory for various hyperon-antihyperon pairs. Their outstanding large production probability in antiproton collisions will open the floodgates for a series of new studies of systems which contain two or even more units of strangeness at the P‾ANDA experiment at FAIR. For the first time, high resolution γ-spectroscopy of doubly strange ΛΛ-hypernuclei will be performed, thus complementing measurements of ground state decays of ΛΛ-hypernuclei at J-PARC or possible decays of particle unstable hypernuclei in heavy ion reactions. High resolution spectroscopy of multistrange Ξ−-atoms will be feasible and even the production of Ω−-atoms will be within reach. The latter might open the door to the |S|=3 world in strangeness nuclear physics, by the study of the hadronic Ω−-nucleus interaction. For the first time it will be possible to study the behavior of Ξ‾+ in nuclear systems under well controlled conditions

Feasibility studies for the measurement of time-like proton electromagnetic form factors from p¯ p→ μ+μ- at P ¯ ANDA at FAIR

This paper reports on Monte Carlo simulation results for future measurements of the moduli of time-like proton electromagnetic form factors, | GE| and | GM| , using the p¯ p→ μ+μ- reaction at P ¯ ANDA (FAIR). The electromagnetic form factors are fundamental quantities parameterizing the electric and magnetic structure of hadrons. This work estimates the statistical and total accuracy with which the form factors can be measured at P ¯ ANDA , using an analysis of simulated data within the PandaRoot software framework. The most crucial background channel is p¯ p→ π+π-, due to the very similar behavior of muons and pions in the detector. The suppression factors are evaluated for this and all other relevant background channels at different values of antiproton beam momentum. The signal/background separation is based on a multivariate analysis, using the Boosted Decision Trees method. An expected background subtraction is included in this study, based on realistic angular distributions of the background contribution. Systematic uncertainties are considered and the relative total uncertainties of the form factor measurements are presented

Prognostic significance of delirium in the intensive care period of acute myocardial infarction

The aim: to identify the frequency and clinical features of delirium in acute myocardial infarction (AMI) in the conditions of the intensive care unit. Material and Methods. The study involved 104 patients (43,3% women and 56,7% men) with AMI during the stay at the intensive care unit. The average age was 68,0 [59,0-76,7] years. Delirium was diagnosed using the criteria questionnaire Moss-ICU. For neurodevelopmental testing we used screening tests and rating scales. Results. The incidence of delirium in patients in this category was 28,8%. Most frequently delirium develops in patients aged 60-89 years: in the age group 60-74 years 25,0%, in the group of 75-89 years 44,7%. Delirium developed in the 1-2 day stay in the intensive care unit and intensive care. The average duration of delirium was 7,7 days. Hypoproductive form of delirium was detected in 64,3% of all cases, hyperproductive form in 21,4% of patients, mixed form in 14,2% of patients. The occurrence of delirium is associated with an increase of the duration of stay at the intensive care unit at 6 times compared with patients without delirium. Conclusion. The presence of delirium greatly increases the probability of death in the reanimation period of acute myocardial infarction. Moss questionnaire and training of doctors to work with rating scales should be accepted in all ICU intensive care units for early diagnosis of delirium and immediate correction of disorders of consciousness in patients in critical condition

Synthesis and crystal structure of 7,7,10-trimethyl-7-silabenzo[a]anthrone

Skeletal isomerization of arylsilanes that occurs under conditions of catalytic dehydrocyclization and is accompanied by migration of the triorganosilyl group was additionally confirmed by dehydrocyclization of dimethyl(2,4-dimethylphenyl)(1-naphthyl)silane on chromium-containing oxide catalysts