Temperature changes in the excitonic absorption band in flat double nanoheterostructures GaAs/AlxGa₁₋xAs

Adduced in this paper are the method and results of theoretical studying the effects of spatial confinement and exciton-phonon interaction on the position and shape of the excitonic absorption band in flat double nanoheterostructures GaAs/AlxGa₁₋xAs. The heterojunction has been considered as unstrained, the nanosystem is modeled as a rectangular quantum well of a finite depth. Interaction of exciton with optical polarization phonons has been taken into account. Calculated has been the temperature dependence of the energy corresponding to transition into the background excitonic state, and determined have been temperature changes in the absorption coefficient related with this transition. It has been shown that observation of these temperature changes in the energy and absorption coefficient, caused by interaction with optical phonons, is possible in the case of exciton with heavy hole at temperatures above 100 K

Search for narrow resonances in e+ e- annihilation between 1.85 and 3.1 GeV with the KEDR Detector

We report results of a search for narrow resonances in e+ e- annihilation at center-of-mass energies between 1.85 and 3.1 GeV performed with the KEDR detector at the VEPP-4M e+ e- collider. The upper limit on the leptonic width of a narrow resonance Gamma(R -> ee) Br(R -> hadr) < 120 eV has been obtained (at 90 % C.L.)

Complete event-by-event α/γ(β) separation in a full-size TeO2 CUORE bolometer by simultaneous heat and light detection

The CUORE project began recently a search for neutrinoless double-beta decay ($0\nu\beta\beta$) of $^{130}$Te with a $\mathcal{O}$(1 ton) TeO$_2$ bolometer array. In this experiment, the background suppression relies essentially on passive shielding, material radiopurity and anti-coincidences. The lack of particle identification in CUORE makes $\alpha$ decays at the detector surface the dominant background, at the level of $\sim$0.01 counts/(keV kg y) in the region of interest ($Q$-value of $0\nu\beta\beta$ of the order of 2.5 MeV). In the present work we demonstrate, for the first time with a CUORE-size (5$\times$5$\times$5 cm) TeO$_2$ bolometer and using the same technology as CUORE for the readout of the bolometric signals, an efficient $\alpha$ particle discrimination (99.9\%) with a high acceptance of the $0\nu\beta\beta$ signal (about 96\%). This unprecedented result was possible thanks to the superior performance (10 eV RMS baseline noise) of a Neganov-Luke-assisted germanium bolometer used to detect a tiny (70 eV) light signal dominated by $\gamma$($\beta$)-induced Cherenkov radiation in the TeO$_2$ detector. The obtained results represent a major breakthrough towards the TeO$_2$-based version of CUPID, a ton-scale cryogenic $0\nu\beta\beta$ experiment proposed as a follow-up to CUORE with particle identification

Scintillating bolometers based on ZnMoO4 and Zn100MoO4 crystals to search for 0ν2β decay of 100Mo (LUMINEU project): first tests at the Modane Underground Laboratory

The technology of scintillating bolometers based on zinc molybdate (ZnMoO4) crystals is under development within the LUMINEU project to search for decay of 100Mo with the goal to set the basis for large scale experiments capable to explore the inverted hierarchy region of the neutrino mass pattern. Advanced ZnMoO4 crystal scintillators with mass of ∼0.3 kg were developed and Zn100MoO4 crystal from enriched 100Mo was produced for the first time by using the low-thermal-gradient Czochralski technique. One ZnMoO4 scintillator and two samples (59 g and 63 g) cut from the enriched boule were tested aboveground at milli-Kelvin temperature as scintillating bolometers showing a high detection performance. The first results of the low background measurements with three ZnMoO4 and two enriched detectors installed in the EDELWEISS set-up at the Modane Underground Laboratory (France) are presented

Electromagnetic moments of odd-A 193-203,211Po isotopes

Hyperfine splitting parameters have been measured for the neutron-deficient odd-mass polonium isotopes and isomers Po193-203g,m, Po209,211. The measurement was performed at the ISOLDE (CERN) online mass separator using the in-source resonance ionization spectroscopy technique. The magnetic dipole moments Î and spectroscopic electric quadrupole moments QS have been deduced. Their implication for the understanding of nuclear structure in the vicinity of the closed proton shell at Z=82 and the neutron mid-shell at N=104 is discussed. For the most neutron-deficient nuclei (A=193,195,197), a deviation of Î and QS from the nearly constant values for heavier polonium nuclei was observed. Particle-plus-rotor calculations with static oblate deformation describe the electromagnetic moments for these nuclei well, provided a gradual increase of a mean deformation when going to lighter masses is assumed for the polonium nuclei with

Electron Injection to Unoccupied Electronic States in Organic Semiconductor Thin Films Studied by Inverse Photoemission Spectroscopy (INTERFACE SCIENCE-Molecular Aggregates)

Inverse photoemission spectroscopy (IPES) in the vacuum ultraviolet region was applied to directly observe behaviors of electron injection into unoccupied electronic states in perylene-3,4,9,10- tetracarboxylic dianhydride (PTCDA) thin films due to alkali metal. By the analysis of the observed results the amount of injected electrons per PTCDA molecule was evaluated with relation to the dopant concentration. The derived relationship has been explained with the aid of DV-X calculations of energy levels concerned