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194 result(s) for "K. Eitel"
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Templated Grain Growth of Textured Piezoelectric Ceramics
Crystallographic texturing of polycrystalline ferroelectric ceramics offers a means of achieving significant enhancements in the piezoelectric response. Templated grain growth (TGG) enables the fabrication of textured ceramics with single crystal-like properties, as well as single crystals. In TGG, nucleation and growth of the desired crystal on aligned single crystal template particles results in an increased fraction of oriented material with heating. To facilitate alignment during forming, template particles must be anisometric in shape. To serve as the preferred sites for epitaxy and subsequent oriented growth of the matrix, the template particles need to be single crystal and chemically stable up to the growth temperature. Besides templating the growth process, the template particles may also serve as seed sites for phase formation of a reactive matrix. This process, referred to as Reactive TGG (RTGG), has been used to obtain highly oriented Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 , Sr 0.53 Ba 0.47 Nb 2 O 6 , and (Na 1/2 Bi 1/2 )TiO 3 -BaTiO 3 . Highly oriented Bi 4 Ti 3 O 12 , Sr 2 Nb 2 O 7 , CaBi 4 Ti 4 O 15 , Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 , Sr 0.53 Ba 0.47 Nb 2 O 6 and (Na 1/2 Bi 1/2 )TiO 3 -BaTiO 3 ceramics have been produced by TGG. The resulting ceramics show texture levels up to 90%, and significant enhancements in the piezoelectric properties relative to randomly oriented ceramics with comparable densities. For example, piezoelectric coefficients of textured piezoelectrics are from 2 to 3 times higher than polycrystalline ceramics and as high as 90% of the single crystal values. In textured PMN-PT, a low field (< 5 kV/cm) piezoelectric coefficient (d 33 ) of ∼1600 pC/N was obtained with > 0.3% strain (at 50 kV/cm). The high field dielectric and electromechanical properties of textured perovskites are more hysteretic than those of single crystals, probably as a result of clamping by the residual template particles, residual random grains, the presence of non-ferroelectric second phases, and a wide orientation distribution. Lateral clamping of one grain by another may also be an important factor in fiber-textured samples. Means to further improve the quality of texture and thus properties of textured piezoelectric ceramics by TGG are presented.
High Impedance TES Bolometers for EDELWEISS
The EDELWEISS collaboration aims for direct detection of light dark matter using germanium cryogenic detectors with low threshold phonon sensor technologies and efficient charge readout designs. We describe here the development of Ge bolometers equipped with high impedance thermistors based on a Nb x Si 1−x TES alloy. High aspect ratio spiral designs allow the TES impedance to match with JFET or HEMT front-end amplifiers. We detail the behavior of the superconducting transition properties of these sensors and the detector optimization in terms of sensitivity to a-thermal phonons. We report preliminary results of a 200 g Ge detector that was calibrated using 71 Ge activation by neutrons at the LSM underground laboratory.
\\upbeta \\ -Decay spectrum, response function and statistical model for neutrino mass measurements with the KATRIN experiment
The objective of the Karlsruhe Tritium Neutrino (KATRIN) experiment is to determine the effective electron neutrino mass \\[m(\\upnu _\\text {e})\\] with an unprecedented sensitivity of \\[0.2 \\hbox {eV}/\\hbox {c}^2\\] (\\[90 \\%\\,\\hbox {C.L.}\\]) by precision electron spectroscopy close to the endpoint of the \\[\\upbeta \\]-decay of tritium. We present a consistent theoretical description of the \\[\\upbeta \\]-electron energy spectrum in the endpoint region, an accurate model of the apparatus response function, and the statistical approaches suited to interpret and analyze tritium \\[\\upbeta \\]-decay data observed with KATRIN with the envisaged precision. In addition to providing detailed analytical expressions for all formulae used in the presented model framework with the necessary detail of derivation, we discuss and quantify the impact of theoretical and experimental corrections on the measured \\[m(\\upnu _\\text {e})\\]. Finally, we outline the statistical methods for parameter inference and the construction of confidence intervals that are appropriate for a neutrino mass measurement with KATRIN. In this context, we briefly discuss the choice of the \\[\\upbeta \\]-energy analysis interval and the distribution of measuring time within that range.
Conceptus estrogen and prostaglandins provide the maternal recognition of pregnancy signal to prevent luteolysis during early pregnancy in the pig
Conceptus estrogens and prostaglandins have long been considered the primary signals for maternal recognition of pregnancy (MRP) in the pig. However, loss-of-function studies targeting conceptus aromatase genes (CYP19A1 and CYP19A2) and prostaglandin–endoperoxide synthase 2 (PTGS2) indicated that conceptuses can not only signal MRP without estrogens or prostaglandins but can maintain early pregnancy. However, complete loss of estrogen production leads to abortion after day 25 of gestation. Although neither conceptus estrogens nor prostaglandins had a significant effect on early maintenance of corpora lutea (CL) function alone, the two conceptus factors have a biological relationship. To investigate the role that both conceptus estrogens and prostaglandins have on MRP and maintenance of pregnancy, a triple loss-of function model (TKO) was generated for conceptus CYP19A1, CYP19A2, and PTGS2. In addition, a conceptus CYP19A2–/– model (A2KO) was established to determine the role of placental estrogen during later pregnancy. Estrogen and prostaglandin synthesis were greatly reduced in TKO concept uses which resulted in a failure to inhibit luteolysis after day 15 of pregnancy despite the presence of conceptuses in the uterine lumen. However, A2KO placentae not only maintained functional CL but were able to maintain pregnancy to day 32 of gestation. Despite the loss of placental CYP19A2 expression, the allantois fluid content of estrogen was not affected as the placenta compensated by expressing CYP19A1 and CYP19A3, which are normally absent in controls. Results suggest conceptuses can signal MRP through production of conceptus PGE or stimulating PGE synthesis from the endometrium through conceptus estrogen. Failure of conceptuses to produce both factors results in failure of MRP and loss of pregnancy. Summary Sentence Triple knockout of conceptus CYP19A1/CYP19A2/PTGS2 results in failure to prevent luteolysis during early pregnancy in the pig. Graphical Abstract
Pulse-Shape Analysis of Ionization Signals in Cryogenic Ge Detectors for Dark Matter
The detectors of the direct dark matter search experiment EDELWEISS consist of high-purity germanium crystals operated at cryogenic temperatures ( < 20 mK ) and low electric fields ( < 1 V / cm ). The surface discrimination is based on the simultaneous measurement of the charge amplitudes on different sets of electrodes. As the rise time of a charge signal strongly depends on the location of an interaction in the crystal, a time-resolved measurement can also be used to identify surface interactions. This contribution presents the results of a study of the discrimination power of the rise time parameter from a hot carrier transport simulation in combination with time-resolved measurements using an EDELWEISS-type detector in a test cryostat at ground level. We show the setup for the time-resolved ionization signal read-out in the EDELWEISS-III experiment and first results from data taking in the underground laboratory of Modane.
Final results on the 0νββ decay half-life limit of 100Mo from the CUPID-Mo experiment
The CUPID-Mo experiment to search for 0νββ decay in 100Mo has been recently completed after about 1.5 years of operation at Laboratoire Souterrain de Modane (France). It served as a demonstrator for CUPID, a next generation 0νββ decay experiment. CUPID-Mo was comprised of 20 enriched Li2100MoO4 scintillating calorimeters, each with a mass of ∼0.2 kg, operated at ∼20 mK. We present here the final analysis with the full exposure of CUPID-Mo (100Mo exposure of 1.47 kg×year) used to search for lepton number violation via 0νββ decay. We report on various analysis improvements since the previous result on a subset of data, reprocessing all data with these new techniques. We observe zero events in the region of interest and set a new limit on the 100Mo 0νββ decay half-life of T1/20ν>1.8×1024 year (stat. + syst.) at 90% CI. Under the light Majorana neutrino exchange mechanism this corresponds to an effective Majorana neutrino mass of mββ <(0.28-0.49) eV, dependent upon the nuclear matrix element utilized.
Development of 100Mo-containing scintillating bolometers for a high-sensitivity neutrinoless double-beta decay search
This paper reports on the development of a technology involving 100 Mo -enriched scintillating bolometers, compatible with the goals of CUPID, a proposed next-generation bolometric experiment to search for neutrinoless double-beta decay. Large mass ( ∼ 1 kg ), high optical quality, radiopure 100 Mo -containing zinc and lithium molybdate crystals have been produced and used to develop high performance single detector modules based on 0.2–0.4 kg scintillating bolometers. In particular, the energy resolution of the lithium molybdate detectors near the Q -value of the double-beta transition of 100 Mo (3034 keV) is 4–6 keV FWHM. The rejection of the α -induced dominant background above 2.6 MeV is better than 8 σ . Less than 10 μ Bq/kg activity of 232 Th ( 228 Th ) and 226 Ra in the crystals is ensured by boule recrystallization. The potential of 100 Mo -enriched scintillating bolometers to perform high sensitivity double-beta decay searches has been demonstrated with only 10 kg × d exposure: the two neutrino double-beta decay half-life of 100 Mo has been measured with the up-to-date highest accuracy as T 1 / 2 = [6.90 ± 0.15(stat.) ± 0.37(syst.)] × 10 18 years . Both crystallization and detector technologies favor lithium molybdate, which has been selected for the ongoing construction of the CUPID-0/Mo demonstrator, containing several kg of 100 Mo .
The background model of the CUPID-Mo 0νββ experiment
CUPID-Mo, located in the Laboratoire Souterrain de Modane (France), was a demonstrator for the next generation 0 ν β β decay experiment, CUPID. It consisted of an array of 20 enriched Li 2 100 MoO 4 bolometers and 20 Ge light detectors and has demonstrated that the technology of scintillating bolometers with particle identification capabilities is mature. Furthermore, CUPID-Mo can inform and validate the background prediction for CUPID. In this paper, we present a detailed model of the CUPID-Mo backgrounds. This model is able to describe well the features of the experimental data and enables studies of the 2 ν β β decay and other processes with high precision. We also measure the radio-purity of the Li 2 100 MoO 4 crystals which are found to be sufficient for the CUPID goals. Finally, we also obtain a background index in the region of interest of 3.7  - 0.8 + 0.9  (stat) - 0.7 + 1.5  (syst)  × 10 - 3  counts/ Δ E FWHM / mol iso / year , the lowest in a bolometric 0 ν β β decay experiment.
Low-energy calibration of XENON1T with an internal$$^{{\\textbf {37}}}$$ Ar source
A low-energy electronic recoil calibration of XENON1T, a dual-phase xenon time projection chamber, with an internal$^{37}$$37 Ar source was performed. This calibration source features a 35-day half-life and provides two mono-energetic lines at 2.82 keV and 0.27 keV. The photon yield and electron yield at 2.82 keV are measured to be ($$32.3\\,\\pm \\,0.3$$32.3 ± 0.3 ) photons/keV and ($$40.6\\,\\pm \\,0.5$$40.6 ± 0.5 ) electrons/keV, respectively, in agreement with other measurements and with NEST predictions. The electron yield at 0.27 keV is also measured and it is ($$68.0^{+6.3}_{-3.7}$$68 . 0 - 3.7 + 6.3 ) electrons/keV. The$^{37}$$37 Ar calibration confirms that the detector is well-understood in the energy region close to the detection threshold, with the 2.82 keV line reconstructed at ($$2.83\\,\\pm \\,0.02$$2.83 ± 0.02 ) keV, which further validates the model used to interpret the low-energy electronic recoil excess previously reported by XENON1T. The ability to efficiently remove argon with cryogenic distillation after the calibration proves that$^{37}$$37 Ar can be considered as a regular calibration source for multi-tonne xenon detectors.
Measurement of the inhomogeneity of the KATRIN tritium source electric potential by high-resolution spectroscopy of conversion electrons from$$\\mathbf {^{83m}}$$ Kr
Precision spectroscopy of the electron spectrum of the tritium$$\\upbeta $$β -decay near the kinematic endpoint is a direct method to determine the effective electron antineutrino mass. The KArlsruhe TRItium Neutrino (KATRIN) experiment aims to determine this quantity with a sensitivity of better than$${0.3}{\\hbox { eV}}$$0.3 eV ($$90\\%$$90 %  C.L.). An inhomogeneous electric potential in the tritium source of KATRIN can lead to distortions of the$$\\upbeta $$β -spectrum, which directly impact the neutrino-mass observable. This effect can be quantified through precision spectroscopy of the conversion-electrons of co-circulated metastable$$^{83\\text {m}}\\text {Kr}$$83 m Kr . Therefore, dedicated, several-weeks long measurement campaigns have been performed within the KATRIN data taking schedule. In this work, we infer the tritium source potential observables from these measurements, and present their implications for the neutrino-mass determination.