Frequency ratio of the Th nuclear isomeric transition and the Sr atomic clock.

Optical atomic clocks use electronic energy levels to precisely keep track of time. A clock based on nuclear energy levels promises a next-generation platform for precision metrology and fundamental physics studies. Thorium-229 nuclei exhibit a uniquely low-energy nuclear transition within reach of state-of-the-art vacuum ultraviolet (VUV) laser light sources and have, therefore, been proposed for construction of a nuclear clock.

Laser Excitation of the Th-229 Nucleus.

The 8.4 eV nuclear isomer state in Th-229 is resonantly excited in Th-doped CaF_{2} crystals using a tabletop tunable laser system. A resonance fluorescence signal is observed in two crystals with different Th-229 dopant concentrations, while it is absent in a control experiment using Th-232.

Growth and characterization of thorium-doped calcium fluoride single crystals.

We have grown [Formula: see text]Th:CaF[Formula: see text] and [Formula: see text]Th:CaF[Formula: see text] single crystals for investigations on the VUV laser-accessible first nuclear excited state of [Formula: see text]Th, with the aim of building a solid-state nuclear clock. To reach high doping concentrations despite the extreme scarcity (and radioactivity) of [Formula: see text]Th, we have scaled down the crystal volume by a factor 100 compared to established commercial or scientific growth processes. We use the vertical gradient freeze method on 3.

Continuous multi-step pumping of the optical clock transition in alkaline-earth atoms with minimal perturbation.

A suitable scheme to continuously create inversion on an optical clock transition with negligible perturbation is a key missing ingredient required to build an active optical atomic clock. Repumping of the atoms on the narrow transition typically needs several pump lasers in a multi step process involving several auxiliary levels. In general this creates large effective level shifts and a line broadening, strongly limiting clock accuracy.

Measurement of the ^{229}Th Isomer Energy with a Magnetic Microcalorimeter.

We present a measurement of the low-energy (0-60 keV) γ-ray spectrum produced in the α decay of ^{233}U using a dedicated cryogenic magnetic microcalorimeter. The energy resolution of ∼10  eV, together with exceptional gain linearity, allows us to determine the energy of the low-lying isomeric state in ^{229}Th using four complementary evaluation schemes. The most precise scheme determines the ^{229}Th isomer energy to be 8.

Characterisation and feasibility study for superradiant lasing in Ca atoms.

Superradiant active clocks operating on narrow linewidth clock transitions are predicted to achieve precision orders of magnitude higher than any currently existing optical atomic clocks. We introduce a theory of superradiant lasing and implement it for the example of Ca atoms. The presented model, however, is valid for any two- or three-level system in an optical lattice.

DFT calculation of thorium-doped magnesium fluoride for nuclear laser spectroscopy.

The thorium nucleus has an extremely low-energy isomeric state that could be manipulated with light in the vacuum ultraviolet (VUV) range. Recent measurements based on internal conversion electrons place the isomer energy at 8.28(17) eV (Seiferle B et al 2019), within the transmission window of large-band-gap materials, such as fluoride single crystals.

A Laser Excitation Scheme for ^{229m}Th.

Direct laser excitation of the lowest known nuclear excited state in ^{229}Th has been a long-standing objective. It is generally assumed that reaching this goal would require a considerably reduced uncertainty of the isomer's excitation energy compared to the presently adopted value of (7.8±0.

Cyanide free contraction of disclosed 1,4-dioxane ring as a route to cobalt bis(dicarbollide) derivatives with short spacer between the boron cage and terminal functional group.

The 1,4-dioxane derivative of cobalt bis(dicarbollide) reacts with dialkylsulfides and triphenylphosphine to give the corresponding sulfonium and phosphonium derivatives [8-L(CH2CH2O)2-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)] (L = SMe2, S(CH2CH2)2O, PPh3). The treatment of the triphenylphosphonium derivative with sodium hydroxide results in contraction of the side chain with formation of [8-HOCH2CH2O-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)](-). The same product was obtained by treatment of the dimethylsulfonium derivative with the poorly nucleophilic base t-BuOK, whereas the stronger nucleophiles induce the sulfur demethylation to give [8-MeS(CH2CH2O)2-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)](-).

229Thorium-doped calcium fluoride for nuclear laser spectroscopy.

The (229)thorium isotope presents an extremely low-energy isomer state of the nucleus which is expected around 7.8 eV, in the vacuum ultraviolet (VUV) regime. This unique system may bridge between atomic and nuclear physics, enabling coherent manipulation and precision spectroscopy of nuclear quantum states using laser light.

Prospects for measuring the Th isomer energy using a metallic magnetic microcalorimeter.

The Thorium-229 isotope features a nuclear isomer state with an extremely low energy. The currently most accepted energy value, 7.8±0.

Two-point phase correlations of a one-dimensional bosonic Josephson junction.

We realize a one-dimensional Josephson junction using quantum degenerate Bose gases in a tunable double well potential on an atom chip. Matter wave interferometry gives direct access to the relative phase field, which reflects the interplay of thermally driven fluctuations and phase locking due to tunneling. The thermal equilibrium state is characterized by probing the full statistical distribution function of the two-point phase correlation.

Influence of laser sources with different spectral properties on the performance of vapor cell atomic clocks based on lin||lin CPT.

We evaluate the influence of 2 types of laser sources with different spectral profiles on the performance of vapor cell atomic clocks based on lin||lin coherent population trapping (CPT) resonances. We show that a short-term stability of 1-2 x 10(-11) tau(-1/2) may be reached in a compact system using a modulated vertical cavity surface-emitting laser. Here the stability is limited by the detection noise level and can be improved up to a factor of 4 by increasing the lock-in detection frequency to several tens of kilohertz, which is not possible in standard double resonance atomic clocks.

Endogenous marinobufagenin-like immunoreactive substance. A possible endogenous Na, K-ATPase inhibitor with vasoconstrictor activity.

Vasoconstrictor and Na/K pump inhibitory properties of a bufodienolide Na/K-ATPase inhibitor, marinobufagenin, were studied in isolated rings of 2 to 3 order branches of human pulmonary arteries respectively. Marinobufagenin displayed concentration-dependent vasoconstrictor activity (0.01 to 10 mmol/L).

[The effect of certain factors on binding of tert-butyloxycarbonylamino acids to Merrifield polymer during interphase catalysis and assessment of racemization of the bound amino acid].

In order to reduce the influence of hydrogen bonds on the acylamino acid salts attachment to the chloromethylated resin, it is proposed to use compounds that can compete for the hydrogen bonds formation. The best solvent proved to be hexamethylphosphoric triamide. Use of interphase catalysts, e.

Upper boundary of the biosphere.

By using meterological rockets fitted with specially designed analyzers, samples for microbiological investigation have been taken. The analyzer design prevented extraneous microorganisms from penetrating into the analyzer. Before being used, the analyzers were sterilized with high gamma-ray doses.

[Method of obtaining enzymatic preparations of lipase from the fungi of the genus Geotrichum under semi-industrial conditions].

A method of manufacturing stable enzymic preparations of lipase from fungi Geotrichum candidum and G. asteroides under semi-industrial conditions has been developed. The paper describes the preparation of the inoculate, fermentation nutrient medium, scheme of cultivation and isolation of the raw enzyme with a yield of 31.

[Spontaneous crystallization of antibiotic substance during submerged fermentation of Actinomyces hygroscopicus].

A rare case of spontaneous crystallization of the antibiotic substance was detected during submerged cultivation of Actinomyces hygroscopicus, strain 33x, under periodic conditions directly in the MTF 5L3 fermenter ("Marubishi"). Leaf-shaped plates of the antibiotic found in the cultural broth of the strain 33x were active against gram-positive and gram-negative microorganisms, yeasts, and fungi. The crystalline state of the structures was confirmed by the X-ray analysis.

On micro-organisms of the stratosphere.

The lower parts of the biosphere are well studied since various live beings are found in oceans and at the bottom of large hollows. Contrary to this, we have no data about the upper boundaries of the biosphere. Samples were obtained with the help of specially constructed analysers which were installed in meteorological rockets and reached an altitude of 100 km.

[Rapid selection of microorganisms producing extracellular lipases].

A method for rapid selection of microorganisms producing extracellular lipases is described. The method is based on diffusion of the enzyme into agar containing olive oil. The hydrolysis zones revcal by 0,05--0,25% OSO4 solution.