<title>Level-crossing spectroscopy of the 7, 9, and 10D states of Cs in an external electric field</title>

We discuss experimental and theoretical studies of coherent excitation of magnetic sublevels in n D states of cesium that cross in an external electric field. Crossings of mF magnetic sublevels of hyperfine F levels with ΔmF = ±2 lead to resonances in the linearly polarized laser induced fluorescence, while crossings with ΔmF = ±1 lead to resonances in the circularly polarized laser induced fluorescence. These resonances can be exploited to observe alignment to orientation conversion. From the level crossing signals it is possible to measure atomic properties, such as the tensor polarizability α2 and the hyperfine constant A . Alignment to orientation conversion involves the deformation of …

Nonlinear magneto-optical resonances atD1excitation ofRb85andRb87in an extremely thin cell

Nonlinear magneto-optical resonances have been measured in an extremely thin cell (ETC) for the ${D}_{1}$ transition of rubidium in an atomic vapor of natural isotopic composition. All hyperfine transitions of both isotopes have been studied for a wide range of laser power densities, laser detunings, and ETC wall separations. Dark resonances in the laser induced fluorescence (LIF) were observed as expected when the ground-state total angular momentum ${F}_{g}$ was greater than or equal to the excited-state total angular momentum ${F}_{e}$. Unlike the case of ordinary cells, the width and contrast of dark resonances formed in the ETC dramatically depended on the detuning of the laser from th…

Dynamic $^{14}\rm N$ nuclear spin polarization in nitrogen-vacancy centers in diamond

We studied the dynamic nuclear spin polarization of nitrogen in negatively charged nitrogen-vacancy (NV) centers in diamond both experimentally and theoretically over a wide range of magnetic fields from 0 to 1100 G covering both the excited-state level anti-crossing and the ground-state level anti-crossing magnetic field regions. Special attention was paid to the less studied ground-state level anti-crossing region. The nuclear spin polarization was inferred from measurements of the optically detected magnetic resonance signal. These measurements show that a very large (up to $96 \pm 2\%$) nuclear spin polarization of nitrogen can be achieved over a very broad range of magnetic field start…

Magnetic Field Gradiometer with Sub-Micron Spatial Resolution Based on Caesium Vapour in an Extremely Thin Cell

Abstract In this paper we present a device for measuring the magnetic field and its gradient with a spatial resolution of several hundred nanometres. This device is based on caesium metal vapour confined to an extremely thin cell (ETC). To measure magnetic signals, we use absorption and very low laser powers, which might be appealing for modern fabrication techniques. A portable, fully automated device was constructed.

Optical non-contact electric field mapping by LIF in Cs vapor

We present experimental and theoretical studies of the possibility of using cesium vapor as a tracer gas for optical non-contact electric field mapping. Optical images of electric field distributions have been obtained.

Level-crossing spectroscopy of the 7, 9, and10D5∕2states ofCs133and validation of relativistic many-body calculations of the polarizabilities and hyperfine constants

We present an experimental and theoretical investigation of the polarizabilities and hyperfine constants of D{sub J} states in {sup 133}Cs for J=3/2 and 5/2. Experimental values for the hyperfine constant A are obtained from level-crossing signals of the (7,9,10)D{sub 5} at {sub {approx}}{sub sol{approx}} at {sub 2} states of {sup 133}Cs and precise calculations of the tensor polarizabilities {alpha}{sub 2}. The results of relativistic many-body calculations for scalar and tensor polarizabilities of the (5-10)D{sub 3} at {sub {approx}}{sub sol{approx}} at {sub 2} and (5-10)D{sub 5} at {sub {approx}}{sub sol{approx}} at {sub 2} states are presented and compared with measured values from the …

F-resolved magneto-optical resonances in theD1excitation of cesium: Experiment and theory

Bright and dark nonlinear magneto-optical resonances associated with the ground state Hanle effect have been studied experimentally and theoretically for ${D}_{1}$ excitation of atomic cesium. This system offers the advantage that the separation between the different hyperfine levels exceeds the Doppler width, and hence transitions between individual levels can be studied separately. At the same time, the system retains the advantages offered by ordinary glass cells, including simplicity and subnatural width Hanle resonances. Experimental measurements for various laser power densities and transit relaxation times are compared with a model based on the optical Bloch equations, which averages…

Longitudinal spin-relaxation in nitrogen-vacancy centers in electron irradiated diamond

We present systematic measurements of longitudinal relaxation rates ($1/T_1$) of spin polarization in the ground state of the nitrogen-vacancy (NV$^-$) color center in synthetic diamond as a function of NV$^-$ concentration and magnetic field $B$. NV$^-$ centers were created by irradiating a Type 1b single-crystal diamond along the [100] axis with 200 keV electrons from a transmission electron microscope with varying doses to achieve spots of different NV$^-$ center concentrations. Values of ($1/T_1$) were measured for each spot as a function of $B$.

Accelerator testing of the general antiparticle spectrometer; a novel approach to indirect dark matter detection

We report on recent accelerator testing of a prototype general antiparticle spectrometer (GAPS). GAPS is a novel approach for indirect dark matter searches that exploits the antideuterons produced in neutralino-neutralino annihilations. GAPS captures these antideuterons into a target with the subsequent formation of exotic atoms. These exotic atoms decay with the emission of X-rays of precisely defined energy and a correlated pion signature from nuclear annihilation. This signature uniquely characterizes the antideuterons. Preliminary analysis of data from a prototype GAPS in an antiproton beam at the KEK accelerator in Japan has confirmed the multi-X-ray/pion star topology and indicated X-…

Alignment-to-orientation conversion in a magnetic field at nonlinear excitation of theD2line of rubidium: Experiment and theory

We studied alignment-to-orientation conversion caused by excited-state level crossings in a nonzero magnetic field of both atomic rubidium isotopes. Experimental measurements were performed on the transitions of the $D_2$ line of rubidium. These measured signals were described by a theoretical model that takes into account all neighboring hyperfine transitions, the mixing of magnetic sublevels in an external magnetic field, the coherence properties of the exciting laser radiation, and the Doppler effect. In the experiments laser induced fluorescence (LIF) components were observed at linearly polarized excitation and their difference was taken afterwards. By observing the two oppositely circ…

Electric-Field-Induced Symmetry Breaking of Angular Momentum Distribution in Atoms

We report the experimental observation of alignment to orientation conversion in the 7D_3/2 and 9D_3/2 states of Cs in the presence of an external dc electric field, and without the influence of magnetic fields or atomic collisions. Initial alignment of angular momentum states was created by two-step excitation with linearly polarized laser radiation. The appearance of transverse orientation of angular momentum was confirmed by the observation of circularly polarized light. We present experimentally measured signals and compare them with the results of a detailed theoretical model based on the optical Bloch equations.

68th annual scientific conference of the University of Latvia. Faculty of Theology. "Science and Religion Dialogue” interdisciplinary group meeting.

LU 68. zinātniskā konference. Teoloģijas fakultātes sekcija „Zinātnes un Reliģijas dialogs”. „Zinātnes un reliģijas dialoga” interdisciplinārās grupas sēde 2010. gada 12. februārī, Latvijas universitāte, Raiņa bulv. 19, Mazā zāle (video skatīties: http://www.lu.lv/par/mediji/video/konferences/2010/religijaunzinatne/12022010/) Vadītājs Dainis Zeps 1. Normunds Titāns, „Zemes dzīvības rašanās teorijas(ekstraterestriālā kontaminācija versus spontānai ģenerācijai no ‘organiskās zupas’) un to antropoloģiski teoloģiskās implikācijas” 2. Iļja Feščenko: „Ārpusvisuma saprāta hipotēze” (Extraterrestrial intelligence hypothesis), scireprints.lu.lv/93/ 3. Dainis Zeps, „Evolūcija un kreatīvā kārtība: Dāv…

Hyperfine level structure in nitrogen-vacancy centers near the ground-state level anticrossing

Energy levels of nitrogen-vacancy centers in diamond were investigated using optically detected magnetic-resonance spectroscopy near the electronic ground-state level anticrossing (GSLAC) at an axial magnetic field around 102.4~mT in diamond samples with a nitrogen concentration of 1~ppm and 200~ppm. By applying radiowaves in the frequency ranges from 0 to 40 MHz and from 5.6 to 5.9 GHz, we observed transitions that involve energy levels mixed by the hyperfine interaction. We developed a theoretical model that describes the level mixing, transition energies, and transition strengths between the ground-state sublevels, including the coupling to the nuclear spin of the NV center\textquotesing…

Dynamics of Singlet Oxygen Molecule Trapped in Silica Glass Studied by Luminescence Polarization Anisotropy and Density Functional Theory

The support from M-ERANET project “MyND” is acknowledged. A.A., M.M-S., and L.R. were supported by the Research Council of Lithuania (Grant M-ERA.NET-1/2015). The authors thank A. Pasquarello for providing the structures of the amorphous SiO 2 matrix for our computational work and K. Kajihara (Tokyo Metropolitan University) for valuable advice in PL kinetics measurements.

Dependence of the shapes of nonzero-field level-crossing signals in rubidium atoms on the laser frequency and power density

We studied magneto-optical resonances caused by excited-state level crossings in a nonzero magnetic field. Experimental measurements were performed on the transitions of the ${D}_{2}$ line of rubidium. These measured signals were described by a theoretical model that takes into account all neighboring hyperfine transitions, the mixing of magnetic sublevels in an external magnetic field, the coherence properties of the exciting laser radiation, and the Doppler effect. Good agreement between the experimental measurements and the theoretical model could be achieved over a wide range of laser power densities. We further showed that the contrasts of the level-crossing peaks can be sensitive to c…

Current status and future plans for the general antiparticle spectrometer (GAPS)

著者人数: 13名

Dynamic N14 nuclear spin polarization in nitrogen-vacancy centers in diamond

We studied the dynamic nuclear spin polarization of nitrogen in negatively charged nitrogen-vacancy (NV) centers in diamond both experimentally and theoretically over a wide range of magnetic fields from 0--1100 G covering both the excited-state level anticrossing and the ground-state level anticrossing magnetic field regions. Special attention was paid to the less studied ground-state level anticrossing region. The nuclear spin polarization was inferred from measurements of the optically detected magnetic resonance signal. These measurements show that a very large (up to $96\ifmmode\pm\else\textpm\fi{}2%$) nuclear spin polarization of nitrogen can be achieved over a very broad range of mag…

Krusta zinātne – kāpēc zinātniekiem ir jāsaprot krusta noslēpums, lai veidotu veiksmīgu dialogu ar kristiešiem

Nonlinear magneto-optical resonances atD1excitation ofR85bandR87bfor partially resolved hyperfineFlevels

Experimental signals of nonlinear magneto-optical resonances at ${D}_{1}$ excitation of natural rubidium in a vapor cell have been obtained and described with experimental accuracy by a detailed theoretical model based on the optical Bloch equations. The ${D}_{1}$ transition of rubidium is a challenging system to analyze theoretically because it contains transitions that are only partially resolved under Doppler broadening. The theoretical model took into account all nearby transitions, the coherence properties of the exciting laser radiation, and the mixing of magnetic sublevels in an external magnetic field and also included averaging over the Doppler profile. The experimental signals wer…

Searching for alignment-to-orientation conversion in the ground state of atomic Cs with circularly polarized laser probe

In this study we explored the possibilities for observing the angular momentum alignment-to-orientation conversion (AOC) in the ground state of various alkali metals: K, Rb, Cs. For theoretical analysis we used a model that is based on the Optical Bloch equations for the density matrix. Our model includes the interaction of all neighboring hyperfine levels with laser radiation, the mixing of magnetic sublevels in an external magnetic field, the coherence properties of the exciting laser radiation, and the Doppler effect. Additionally we simulated signals where the ground- or the excited-state coherent processes were numerically switched off in order to determine the origins of the features …

Conversion of bright magneto-optical resonances into dark resonances at fixed laser frequency forD2excitation of atomic rubidium

Nonlinear magneto-optical resonances on the hyperfine transitions belonging to the ${D}_{2}$ line of rubidium were changed from bright to dark resonances by changing the laser power density of the single exciting laser field or by changing the vapor temperature in the cell. In one set of experiments atoms were excited by linearly polarized light from an extended cavity diode laser with polarization vector perpendicular to the light's propagation direction and magnetic field, and laser-induced fluorescence was observed along the direction of the magnetic field, which was scanned. A low-contrast bright resonance was observed at low laser power densities when the laser was tuned to the ${F}_{g…

Level anti-crossing magnetometry with color centers in diamond

Recent developments in magnetic field sensing with negatively charged nitrogen-vacancy centers (NV) in diamond employ magnetic-field (MF) dependent features in the photoluminescence (PL) and eliminate the need for microwaves (MW). Here, we study two approaches towards improving the magnetometric sensitivity using the ground-state level anti-crossing (GSLAC) feature of the NV center at a background MF of 102.4\,mT. Following the first approach, we investigate the feature parameters for precise alignment in a dilute diamond sample; the second approach extends the sensing protocol into absorption via detection of the GSLAC in the diamond transmission of a 1042\,nm laser beam. This leads to an …

The General Antiparticle Spectrometer (GAPS) - Hunt for dark matter using low energy antideuterons

The GAPS experiment is foreseen to carry out a dark matter search using a novel detection approach to detect low-energy cosmic-ray antideuterons. The theoretically predicted antideuteron flux resulting from secondary interactions of primary cosmic rays with the interstellar medium is very low. So far not a single cosmic antideuteron has been detected by any experiment, but well-motivated theories beyond the standard model of particle physics, e.g., supersymmetry or universal extra dimensions, contain viable dark matter candidates, which could led to a significant enhancement of the antideuteron flux due to self-annihilation of the dark matter particles. This flux contribution is believed to…

Relaxation mechanisms affecting magneto-optical resonances in an extremely thin cell: Experiment and theory for the cesiumD1line

We have measured magneto-optical signals obtained by exciting the $D_1$ line of cesium atoms confined to an extremely thin cell (ETC), whose walls are separated by less than one micrometer, and developed an improved theoretical model to describe these signals with experimental precision. The theoretical model was based on the optical Bloch equations and included all neighboring hyperfine transitions, the mixing of the magnetic sublevels in an external magnetic field, and the Doppler effect, as in previous studies. However, in order to model the extreme conditions in the ETC more realistically, the model was extended to include a unified treatment of transit relaxation and wall collisions wi…

Estimating the magnetic moment of microscopic magnetic sources from their magnetic field distribution in a layer of nitrogen-vacancy (NV) centres in diamond

We have used a synthetic diamond with a layer of nitrogen-vacancy (NV) centres to image the magnetic field distributions of magnetic particles on the surface of the diamond. Magnetic field distributions of 4 µ m and 2 µ m ferromagnetic and 500 nm diameter superparamagnetic particles were obtained by measuring the position of the optically detected magnetic resonance peak in the fluorescence emitted by the NV centres for each pixel. We fitted the results to a model in order to determine the magnetic moment of the particles from the magnetic field image and compared the results to the measured magnetic moment of the particles. The best-fit magnetic moment differed from the value expected base…

Electric field induced hyperfine level-crossings in (nD)Cs at two-step laser excitation: experiment and theory

The pure electric field level-crossing of m_F Zeeman sublevels of hyperfine F levels at two-step laser excitation was described theoretically and studied experimentally for the nD_3/2 states in Cs with n = 7,9, and 10, by applying a diode laser in the first 6S_1/2 to 6P_3/2 step and a diode or dye laser for the second 6P_3/2 to nD_3/2 step. Level-crossing resonance signals were observed in the nD_3/2 to 6P_1/2 fluorescence. A theoretical model was developed to describe quantitatively the resonance signals by correlation analysis of the optical Bloch equations in the case when an atom simultaneously interacts with two laser fields in the presence of an external dc electric field. The simulat…

Colloidal nanoparticle sorting and ordering on anodic alumina patterned surfaces using templated capillary force assembly

Abstract A new, robust technique of size-selective nanoparticle ordering on porous anodized aluminum oxide (PAAO) templates is presented. Simultaneous particle sorting and array formation is achieved for the first time using a polydisperse suspension of irregularly shaped diamond nanocrystals. The array parameters can be tuned through a balance of evaporation driven particle flux, capillary, electrostatic, and adhesion forces, which are influenced by the asperities of the surface during the capillary and convective assembly dip-coating process. The resulting structures are dense (lower limit approximately 50 nm center separation), isolated (non-touching) nanoparticle arrays with a size dist…

Cascade coherence transfer and magneto-optical resonances at 455 nm excitation of Cesium

We present and experimental and theoretical study of nonlinear magneto-optical resonances observed in the fluorescence to the ground state from the 7P_{3/2} state of cesium, which was populated directly by laser radiation at 455 nm, and from the 6P_{1/2} and 6P_{3/2} states, which were populated via cascade transitions that started from the 7P_{3/2} state and passed through various intermediate states. The laser-induced fluorescence (LIF) was observed as the magnetic field was scanned through zero. Signals were recorded for the two orthogonal, linearly polarized components of the LIF. We compared the measured signals with the results of calculations from a model that was based on the optica…

Indirect Dark Matter Search with Antideuterons: Progress and Future Prospects for General Antiparticle Spectrometer (GAPS)

We report on recent accelerator testing of a prototype general antiparticle spectrometer (GAPS). GAPS is a novel approach for indirect dark matter searches that exploits the antideuterons produced in neutralino-neutralino annihilations. Many supersymmetry models, as well as other models based on extra dimensions, predict a primary antideuteron flux from dark matter annihilation that is much greater than the secondary and tertiary background sources at low energies. The GAPS method involves capturing antiparticles in a target material into excited energy states. The X-rays that are emitted as the antiparticle cascades to lower energy states before the exotic atom decays serve as a fingerprin…

Cross-relaxation studies with optically detected magnetic resonances in nitrogen-vacancy centers in diamond in an external magnetic field

In this paper cross-relaxation between nitrogen-vacancy (NV) centers and substitutional nitrogen in a diamond crystal was studied. It was demonstrated that optically detected magnetic resonance signals (ODMR) can be used to measure these signals successfully. The ODMR were detected at axial magnetic field values around 51.2~mT in a diamond sample with a relatively high (200~ppm) nitrogen concentration. We observed transitions that involve magnetic sublevels that are split by the hyperfine interaction. Microwaves in the frequency ranges from 1.3 GHz to 1.6 GHz ($m_S=0\longrightarrow m_S=-1$ NV transitions) and from 4.1 to 4.6 GHz ($m_S=0\longrightarrow m_S=+1$ NV transitions) were used. To u…

Science and Religion Dialogue: What is Life? Zinātnes un Reliģijas Dialogs: Kas ir dzīvība?

Juris Cālītis, Paskāla liesmas, Dekarta rēgs un cilvēka dzīvība Dzintars Edvīns Bušs, Dzīvības jēdziena aprises dvēseles, gara un apziņas izpratnes kontekstā Dainis Zeps, Dzīvība un Matemātika: vai ir kāds kopsakars? scireprints.lu.lv/227/ Pāvils Tjurins, Huligānisma psiholoģija (Dabas normativitāte un psihes nenormativitāte), scireprints.lu.lv/229/ Jānis Rudzītis, Dzīvība Vecajā Derībā Enoks Biķis, Cilvēka dzīvība bioloģiskā un medicīniskā aspektā Normunds Titāns, Bioloģisks universs? Inteliģenta ārpuszemes dzīvība? Astroteoloģija? scireprints.lu.lv/228/ Kaspars Mičulis, Dzīvība un saprāts pašorganizācijas un antropā principa kontekstā, scireprints.lu.lv/226/ Florian Gahbauer, Dzīva būtne:…

Antideuterons as an indirect dark matter signature: design and preparation for a balloon-born GAPS experiment

The General Antiparticle Spectrometer (GAPS) exploits low energy antideuterons produced in neutralino-neutralino annihilations as an indirect dark matter (DM) signature that is effectively free from background. When an antiparticle is captured by a target material, it forms an exotic atom in an excited state which quickly decays by emitting X-rays of precisely defined energy and a correlated pion signature from nuclear annihilation. We have successfully demonstrated the GAPS method in an accelerator environment and are currently planning a prototype flight from Japan for 2009. This will lead to a long duration balloon (LDB) mission that will complement existing and planned direct DM searche…

Composition of Primary Cosmic-Ray Nuclei at High Energies

The TRACER instrument (``Transition Radiation Array for Cosmic Energetic Radiation'') has been developed for direct measurements of the heavier primary cosmic-ray nuclei at high energies. The instrument had a successful long-duration balloon flight in Antarctica in 2003. The detector system and measurement process are described, details of the data analysis are discussed, and the individual energy spectra of the elements O, Ne, Mg, Si, S, Ar, Ca, and Fe (nuclear charge Z=8 to 26) are presented. The large geometric factor of TRACER and the use of a transition radiation detector make it possible to determine the spectra up to energies in excess of 10$^{14}$ eV per particle. A power-law fit to…