Strontium optical lattice clocks for practical realization of the metre and secondary representation of the second

We present a system of two independent strontium optical lattice standards probed with a single shared ultra-narrow laser. The absolute frequency of the clocks can be verified by the use of Er:fiber optical frequency comb with the GPS-disciplined Rb frequency standard. We report hertz-level spectroscopy of the clock line and measurements of frequency stability of the two strontium optical lattice clocks.Comment: This is an author-created, un-copyedited version of an article accepted for publication in Meas. Sci. Technol. The publisher is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi:10.1088/0957-0233/26/7/07520

Positronium laser cooling via the 13S1^3S-23P2^3P transition with a broadband laser pulse

We report on laser cooling of a large fraction of positronium (Ps) in free-flight by strongly saturating the $1^3S$-$2^3P$ transition with a broadband, long-pulsed 243 nm alexandrite laser. The ground state Ps cloud is produced in a magnetic and electric field-free environment. We observe two different laser-induced effects. The first effect is an increase in the number of atoms in the ground state after the time Ps has spent in the long-lived $3^3P$ states. The second effect is the one-dimensional Doppler cooling of Ps, reducing the cloud's temperature from 380(20) K to 170(20) K. We demonstrate a 58(9) % increase in the coldest fraction of the Ps ensemble.Comment: 6 pages, 5 figure

Polarization and Optical Excitation Function of Resonance Radiation of Cadmium Atoms Excited by Electron Impact

First measurements of polarization of 228.8 nm radiation emitted by cadmium atoms excited to the first singlet state (5 $\text{}^{1}$P$\text{}_{1}$) following impact of electrons were carried out for the electron energy range 20-500 eV. New data were also obtained on the relative optical excitation function up to electron energy of 500 eV, which extend lower energy results published previously by other researchers

Optical-Excitation Function and Polarization of 4227-Å Resonance Line of Ca Excited by 8-500 eV Electron Impact

We report on measurements of the relative optical-excitation function for the 4$\text{}^{1}$P state of Ca and polarization degree of the 4227-Å resonance line. The measurements were carried out using crossed low-density beams of electrons and calcium atoms, for incident electron energies from 8 to 500 eV. For each electron energy we have used 28 results obtained at different polarizer positions from 0-180 ̊ to extract the required parameters. Excellent agreement between the present results and earlier predictions has been found

Electron-impact coherence parameters for 4(1)P(1) excitation of zinc

We present electron-impact coherence parameters (EICP) for electron-impact excitation of 41P1 state of zinc atoms for collision energies 40 eV and 60 eV. The experimental results are presented together with convergent close-coupling and relativistic distorted-wave approximation theoretical predictions. The results are compared and discussed with EICP data for collision energies 80 eV and 100 eV

Experimental investigation of electron impact excitation of zinc atoms to the 4

Polarization analysis version of the electron-photon coincidence technique was applied to completely determine quantum state of zinc atoms excited to the 41P1 state by electron impact. We report first experimental values of Stokes parameters and Electron Impact Coherence Parameters (EICPs) for incident electron energy 80 eV

"Mobile robots influence on people's collective behaviour" conclusions from an innovative project

W artykule przedstawiono założenia i wstępne wnioski z projektu realizowanego w PIAP, obejmującego badania nad wpływem robotów mobilnych na zbiorowe zachowanie ludzi, skupiającego się w szczególności na identyfikacji oraz interpretacji czynników mogących napędzać lub hamować powszechne zastosowanie robotów mobilnych w środowisku ludzkim. W referacie wskazano potrzebę zastosowania robotów mobilnych w systemach bezpieczeństwa publicznego, w celu zwiększenia możliwości systemów nadzoru ludzi, w szczególności podróżnych przebywających na lotnisku. Roboty mobilne działające na lotnisku, są zdolne zapewnić operatorowi kompleksowe wykrywanie zdarzeń, wraz z systemem sygnalizacji alarmowej. W ten sposób mogą znacznie przyczynić się do wspomagania oraz ulepszenia procesu percepcji oraz do proaktywnego identyfikowania zbliżających się zagrożeń, sygnałów ostrzegawczych, analizowania ich i wspierania procesu podejmowania decyzji przez służby odpowiedzialne za bezpieczeństwo. W pracy przedstawiono podsumowanie aktualnego etapu badania, polegającego na analizie i prezentacji możliwych wzorców zbiorowych zachowań ludzkich w kontakcie z robotem mobilnym, operującym na międzynarodowym lotnisku.This paper presents the objectives of the project, as currently executed in the Industrial Research Institute for Automation and Measurements PIAP, which is focused on examining the influence of the mobile robots on the collective behaviour of people. The main objective of the project is to identify and interpret the factors, which can drive or impede the common application of the mobile robots in a busy human environment. The paper also explains the necessity of application of the mobile robots in systems dedicated to the public safety and security, which would increase the level of necessary surveillance of the infrastructure and people, at the specific social area of the international airport. Mobile robots operating in the airport space can enable the security staff to detect the suspicious and dangerous events in a more efficient way. Complementing the existing surveillance systems with such devices would significantly enhance the processes of perception and decision making, in reference to preventing or reacting to the probable threats, such as terrorist or criminal attacks. This paper illustrates the current phase of the research, aimed at testing and describing the possible patterns in collective human behaviour connected with introduction of the mobile robot into the international airport area

Model of collision-induced constructive quantum interference

Yang and collaborators reported recently observation of unexpected resonaces in so-called hybrid excitation spectra of sodium vapour. Yang and Xie presented a theoretical model in which the resonances were interpreted as in terms of collision constructive quantum interference effects. This work reports results of testing of the applicability range of the model and demonstrates its serious limitations

Ultra-Narrow Laser for Optical Frequency Reference

We present ultra-narrow line width, tunable diode laser system which will be used as a local oscillator in an optical atomic clock and for precision spectroscopy of Sr near 689 nm. Design of the high finesse optical cavity used as short-term frequency reference is optimized with respect to insensitivity to vibrations. We achieved laser line width of about 8 Hz, measured by comparison of two identical systems. The relative phase lock of two lasers is better than 150 mHz. Laser tunability and usefulness for precison spectroscopy were demonstrated through line shape measurement of a 20 kHz wide resonance of the optical cavity