Search results for "Ultra"
showing 10 items of 4451 documents
Pulsed electron beam excited transient absorption in SrTiO3
2002
Abstract Transient absorption (TA) spectra and optical density relaxation kinetics in SrTiO3 (STO), STO–Nb and STO–V were studied. The electron polaron free or bound at intrinsic defect is suggested to be responsible for the TA band at ∼1.4 eV observed in STO. The band peaking below 0.75 eV in STO–Nb is proposed to be from Nb4+. The electron center V3+ or electron polaron bound in the vicinity of V4+ is responsible for the absorption band at 1.0 eV in STO–V. The absorption from hole polarons is suggested to be in the range 1.8–2.3 eV. It is shown that TA in pure STO at room temperature decays due to electron–hole polaron recombination.
Intercomparison measurements between accelerator and laser based mass spectrometry for ultra-trace determination of 41Ca in the 10−11–10−10 isotopic …
2005
Abstract Selective ultra-trace determination of the long-lived radioisotope 41 Ca has applications in environmental and biomedical research, as well as in cosmochemistry. We have conducted an intercomparison between the two currently available methods for measurement at these low (radio) activities: accelerator mass spectrometry (AMS) and resonance ionization mass spectrometry (RIMS). Three artificially produced 41 Ca samples, primarily of cosmochemical importance, with isotopic abundances in the range of 10 −11 –10 −10 were used and results of these measurements show good agreement between the two methods, within the experimental uncertainties.
Temperature dependence of the dynamics of ultrafine particles in a polymeric network
1990
Simple model systems with pronounced dynamical features will help to get a deeper insight into the complicated dynamics of large molecular networks. We investigated the bounded diffusion of ultrafine Fe(OH)3 particles (∼30 A in diameter) in the three-dimensional network of the cation exchanger Dowex 50 W which was solvated with a water solution of sucrose (60 wt%). Mossbauer spectra were recorded in the temperature range from 80 K to 305 K. At temperatures above 250 K broad diffusional lines of different widths appear in the spectrum proving the bounded nature of the diffusion. The line widths strongly increase with temperature to values of several hundred mm/s. Around 300 K a large portion…
Studies for low mass, large area monolithic silicon pixel detector modules using the MALTA CMOS pixel chip
2021
Abstract The MALTA monolithic silicon pixel sensors have been used to study dicing and thinning of monolithic silicon pixel detectors for large area and low mass modules. Dicing as close as possible to the active circuitry will allow to build modules with very narrow inactive regions between the sensors. Inactive edge regions of less than 5 μ m to the electronic circuitry could be achieved for 100 μ m thick sensors. The MALTA chip (Cardella et al., 2019) also offers the possibility to transfer data and power directly from chip to chip. Tests have been carried out connecting two MALTA chips directly using ultrasonic wedge wire bonding. Results from lab tests show that the data accumulated in…
High-precision electron-capture Q value measurement of 111In for electron-neutrino mass determination
2022
A precise determination of the ground state $^{111}$In ($9/2^+$) electron capture to ground state of $^{111}$Cd ($1/2^+$) $Q$ value has been performed utilizing the double Penning trap mass spectrometer, JYFLTRAP. A value of 857.63(17) keV was obtained, which is nearly a factor of 20 more precise than the value extracted from the Atomic Mass Evaluation 2020 (AME2020). The high-precision electron-capture $Q$ value measurement along with the nuclear energy level data of 866.60(6) keV, 864.8(3) keV, 855.6(10) keV, and 853.94(7) keV for $^{111}$Cd was used to determine whether the four states are energetically allowed for a potential ultra-low $Q$-value $\beta^{}$ decay or electron-capture deca…
Numerical evaluation of NLO multiparton processes
2013
We discuss an algorithm for the numerical evaluation of NLO multiparton processes. We focus hereby on the virtual part of the NLO calculation, i.e. on evaluating the one-loop integration numerically. We employ and extend the ideas of the subtraction method to the virtual part and we use subtraction terms for the soft, collinear and ultraviolet regions, which allows us to evaluate the loop integral numerically in four dimensions. A second ingredient is a method to deform the integration contour of the loop integration into the complex plane. The algorithm is derived on the level of the primitive amplitudes, where we utilise recursive relations to generate the corresponding one-loop off-shell…
Ultra-high resolution mass separator—Application to detection of nuclear weapons tests
2009
Abstract A Penning trap-based purification process having a resolution of about 1 ppm is reported. In this context, we present for the first time a production method for the most complicated and crucially important nuclear weapons test signature, 133mXe. These pure xenon samples are required by the Comprehensive Nuclear-Test-Ban Treaty Organization to standardize and calibrate the worldwide network of xenon detectors.
Improvement of ESR dosimetry for thermal neutron beams through the addition of gadolinium.
2007
In this paper, the addition of gadolinium is proposed as a useful tool to enhance the electron spin resonance (ESR) sensitivity of organic compounds to thermal neutrons. The target of this work is the detection, through the ESR technique, of the thermal neutron fluence in a mixed field of photons and neutrons. Gadolinium was chosen because it has a very high capture cross section to thermal neutrons; its nuclear reaction with thermal neutrons induces complex inner shell transitions that generate, besides other particles, Auger electrons, which in turn release their energy in the neighborhood (only several nanometers) of the place of reaction. Gadolinium was added to two organic molecules: a…
From ‘green’ technologies to ‘red’ antioxidant compounds extraction of purple corn: a combined ultrasound-ultrafiltration-purification approach
2018
A pilot scale process consisting of ultrasound-assisted extraction, ammonium sulfate precipitation, cross-flow ultrafiltration and AB-8 macroporous resins purification aiming to recover anthocyanins and zein from purple corn (PC) was optimized and scaled-up. The effects of five independent variables (ethanol concentration, liquid to solid ratio, ultrasound temperature, time and power) were discussed and the most influential factors were optimized.; Results: The highest total anthocyanin (0.45 ± 0.01 g kg-1 ) and zein (17.14 ± 1.73 g kg-1 ) contents from purple corn were obtained using an ultrasound power of 105 W, an extraction time of 90 min, an ethanol concentration of 74% and a liquid to…
Recent advances in the application of pulsed light processing for improving food safety and increasing shelf life
2019
Abstract Background New technologies of non-thermal disinfection such as pulsed light (PL) have emerged lately as an alternative to traditional (thermal and chemical) disinfection and preservation methods. PL can be used to decontaminate a great variety of foods as well as to decontaminate contact surfaces, thus improving safety in foods and extending their shelf life. Moreover, this technology can prevent or reduce some of the detrimental effects of traditional methods on nutrients and bioactive compounds of food products. Scope and approach The combination of PL with other techniques such as ultraviolet light (UV), thermosonication (TS), pulsed electric fields (PEF), manothermosonication …