We report the final results of the Phase II SIMPLE measurements, comprising two run stages of 15 superheated droplet detectors each, the second stage including an improved neutron shielding. The analyses includes a refined signal analysis, and revised nucleation efficiency based on reanalysis of previously-reported monochromatic neutron irradiations. The combined results yield a contour minimum of σp = 5.7 × 10 −3 pb at 35 GeV/c 2 in the spin-dependent sector of WIMP-proton interactions, the most restrictive to date for MW ≤ 60 GeV/c 2 from a direct search experiment and overlapping for the first time results previously obtained only indirectly. In the spin-independent sector, a minimum of 4.7 × 10 −6 pb at 35 GeV/c 2 is achieved, with the exclusion contour challenging a significant part of the light mass WIMP region of current interest.The search for weakly interacting massive particle (WIMP) dark matter remains at the forefront of modern physics activity. Estimated to comprise ∼ 23% of the Universe mass, it is the role of direct detection efforts to elaborate its nature, and whether its interaction with nucleons is spin-independent (SI) or spin-dependent (SD). SIMPLE (Superheated Instrument for Massive ParticLe Experiments) [1] is a direct search activity using superheated liquid detectors, and one of only a few in the international panorama with sensitivity to the WIMPproton sector of the SD phase space. It is operated at the 1500 mwe level of the Low Noise Underground Laboratory (LSBB) in southern France.In [1], we reported the first results of a two stage Phase II measurement, comprising a 14.1 kgd Stage 1 exposure of 15 superheated droplet detectors (SDDs) [2-4] with a total active mass of 0.208 kg. We here provide the results of the full Phase II measurement, including a 13.67 kgd Stage 2 exposure of a second 15 SDD set, together with improved neutron shielding and a refined analysis of the individual detector run signals, sensitivities, and nucleation efficiency.A SDD consists of a dispersion of superheated liquid droplets homogeneously distributed within a gel matrix, which may undergo a transition to the gas phase upon energy deposition by incident radiation. Two conditions are required for the nucleation of the gas phase of the superheated droplets [5]: (i) the energy deposited must be greater than a thermodynamic minimum, and (ii) this * criodets@cii.fc.ul.pt energy must be deposited within a thermodynamicallydefined minimum distance (Λr c ) inside the droplet, where Λ is the nucleation parameter and r c = the thermodynamic critical bubble radius. Adjustment of the two conditions results in the necessity of depositions of order ≥ 150 keV/µm for a bubble nucleation, rendering the SDD effectively insensitive to the majority of traditional detector backgrounds (including electrons, γ's and cosmic muons) which complicate more conventional dark matter search detectors, leaving only α-and neutron-induced events.The 15 Stage 2 SDDs were fabricated as described in [1], each containing between 11-19 g of C 2 ...
Spin tunnel junctions with tunneling magnetoresistance of 36.5%±0.5%, resistance-area product of 35±6 kΩ×μm2, and junction area between 6 and 75 μm2 were fabricated. The barrier height is 2.5±0.3 eV and the barrier thickness is 7.7±0.3 Å. Large tunneling magnetoresistance (TMR) values are obtained by vacuum anneal (at temperatures from 100 to 240 °C for over 5 h) of junctions prepared with as-deposited TMR of 21%±1.7%, and an as-deposited resistance-area product of 25±6 kΩ×μm2. Two regimes occur during anneal. The first one occurs for anneals up to 200 °C where TMR and junction resistance increase, but the barrier parameters are unaltered. The second occurs above 200 °C, where TMR increases faster, together with an increase in barrier height. At 240 °C, TMR starts to decrease. Rutherford backscattering analysis indicates an asymmetry in the oxygen distribution in the as-deposited barrier. The oxygen distribution becomes homogeneous for anneals above 150 °C.
NaBi(WO 4 ) 2 (NBW), NaBi(MoO 4 ) 2 (NBMo) and LiBi(MoO 4 ) 2 (LBMo) single crystals grown by the Czochralski technique have been doped up to a praseodymium concentration of [Pr] ≈ 1 × 10 20 cm −3 in the crystal. 10 K polarized optical absorption and photoluminescence measurements have been used to determine the energy position of 32, 39 and 36 Pr 3+ Stark levels in NBW, NBMo and LBMo crystals, respectively. These energy levels were labelled with the appropriate irreducible representations corresponding to a C 2 local symmetry of an average optical centre. Single-electron Hamiltonians including free-ion and crystal field interactions have been used in the fitting of experimental energy levels and in the simulation of the full sequence of the 4f 2 Pr 3+ configuration. 300 K absorption spectra of different 2S+1 L J Pr 3+ multiplets were determined and used in the context of the Judd-Ofelt theory and for the calculation of the 1 D 2 -related emission cross sections of this average Pr 3+ centre. Non-radiative electron relaxation from the 3 P 0 level feeds the 1 D 2 multiplet. This latter level efficiently decays radiatively to the ground 3 H 4 multiplet but still there is a significant rate of radiative decay to the 1 D 2 → 3 F 3 praseodymium laser channel. For [Pr] 2 × 10 19 cm −3 , non-radiative electric dipole-dipole Pr pair energy transfer limits the radiative yield.
The One Touch Pipeline (OTP) is an automation platform managing Next-Generation Sequencing (NGS) data and calling bioinformatic pipelines for processing these data. OTP handles the complete digital process from import of raw sequence data via alignment of sequencing reads to identify genomic events in an automated and scalable way. Three major goals are pursued: firstly, reduction of human resources required for data management by introducing automated processes. Secondly, reduction of time until the sequences can be analyzed by bioinformatic experts, by executing all operations more reliably and quickly. Thirdly, storing all information in one system with secure web access and search capabilities. From software architecture perspective, OTP is both information center and workflow management system. As a workflow management system, OTP call several NGS pipelines that can easily be adapted and extended according to new requirements. As an information center, it comprises a database for metadata information as well as a structured file system. Based on complete and consistent information, data management and bioinformatic pipelines within OTP are executed automatically with all steps book-kept in a database.
Because of the incongruent melting of LiYb(MoO 4 ) 2 compound at 912 °C, Li 2 MoO 4 and Li 2 Mo 2 O 7 fluxes have been used to nucleate single crystals of this compound. From the latter flux, crystals of about 1 cm 3 have been pulled by the top-seeded solution-growth method. Details on the preparation and growth procedures are provided. The Li concentration in the crystal has been assessed using 7 Li(p,R) 4 He nuclear reaction induced by protons. The [Yb]/[Li] molar composition ratio obtained in several samples is in the 1.01-1.05 range. This result compares well with the ratio [Yb]/[Li] ) 1 expected from the above chemical formula, therefore nonextensive Li loss is experienced during the crystal growth. Polymorphic transformations to phases with symmetry lower than tetragonal have not been observed upon cooling. At room temperature the crystal structure shows the tetragonal space group I4 h (No. 82), with lattice parameters a ) 5.1191 (9) Å and c ) 11.109 (3) Å, V ) 291.11(10) Å 3 , and Z ) 2. This implies a high ytterbium density, namely [Yb] ) 6.87 × 10 21 cm -3 . The optical absorption and photoluminescence properties are described in detail consistently with the anisotropic character of the tetragonal phase. The relative energies of the Yb 3+ Stark levels have been determined and the perspectives for applications as a laser material are evaluated.
Phase II of SIMPLE (Superheated Instrument for Massive ParticLe Experiments) searched for astroparticle dark matter using superheated liquid C2ClF5 droplet detectors. Each droplet generally requires an energy deposition with linear energy transfer (LET) > ∼ 150 keV/µm for a liquid-to-gas phase transition, providing an intrinsic rejection against minimum ionizing particles of order 10 −10 , and reducing the backgrounds to primarily α and neutron-induced recoil events. The droplet phase transition generates a millimetric-sized gas bubble which is recorded by acoustic means. We describe the SIMPLE detectors, their acoustic instrumentation, and the characterizations, signal analysis and data selection which yield a particle-induced, "true nucleation" event detection efficiency of better than 97% at a 95% C.L. The recoil-α event discrimination, determined using detectors first irradiated with neutrons and then doped with alpha emitters, provides a recoil identification of better than 99%; it differs from those of COUPP and PICASSO primarily as a result of their different liquids with lower critical LETs. The science measurements, comprising two shielded arrays of fifteen detectors each and a total exposure of 27.77 kgd, are detailed. Removal of the 1.94 kgd Stage 1 installation period data, which had previously been mistakenly included in the data, reduces the science exposure from 20.18 to 18.24 kgd and provides new contour minima of σp = 4.3 × 10 −3 pb at 35 GeV/c 2 in the spin-dependent sector of WIMP-proton interactions and σN = 3.6 × 10 −6 pb at 35 GeV/c 2 in the spin-independent sector. These results are examined with respect to the fluorine spin and halo parameters used in the previous data analysis.
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