Search results for "Conversion"
showing 10 items of 707 documents
Layer formation on silicon steel by processing in H2/H2O at elevated temperatures
1992
Silicon steel (Fe-3wt%Si), as used for transformers and generators, has been annealed in wet hydrogen at elevated temperatures. The composition, sequence, and thicknesses of the layers found by conversion electron Mossbauer spectroscopy (CEMS) and Auger electron spectroscopy (AES) depth profiling for a 10 minutes anneal in different atmospheres are reported. In the range from 500°C to 720°C we observed carbide formation, indicating that the decarburization is hindered. Above 800°C, the layers consist of fayalite or of fayalite and iron oxides, depending on the oxygen potentialaO. At 843°C, the onset of iron oxide formation was found ataO=0.33.
A Portable Readout System for Microstrip Silicon Sensors (ALIBAVA)
2009
A readout system for microstrip silicon sensors has been developed. This system is able to measure the collected charge in one or two microstrip silicon sensors by reading out all the channels of the sensor(s), up to 256. The system can operate either with non-irradiated and irradiated sensors as well as with n-type and p-type microstrip silicon sensors. Heavily irradiated sensors will be used at the Super Large Hadron Collider, so this system can be used to research the performance of microstrip silicon sensors in conditions as similar as possible to the Super Large Hadron Collider operating conditions. The system has two main parts: a hardware part and a software part. The hardware part a…
High-performance Mössbauer spectroscopy: Criteria, possibilities, limitations
1992
Increasing attention is being paid to non-conventional Mossbauer methods in view of the extension of Mossbauer Spectroscopy (MS) to a broadening field of applications. With such long-lasting experiments the shortening of the measuring time required for a given statistical significance is of major practical importance. It is shown that the statistical utility rateu allows one to determine which experimental parameters have a primary role, and it also enables sucessive optimization. It is pointed out for various MS measurements that the strategy for improving the experimental performance is strongly dependent on the given problem. As examples, time-differential Mossbauer measurements and conv…
Study of Fe−Ti and Fe−TiN interfaces by conversion electron Mössbauer spectroscopy
1992
Titanium and titanium nitride-iron interfaces obtained by PVD coated thin films of Ti and TiN onto argon plasma etched iron substrates at various temperatures and negative bias were studied by use of CEMS. It was found that intermixing to Ti with Fe resulted in the appearance of an amorphous FeTi1−x phase. Furthermore, a comparison of CEM spectra of samples before and after heating in UHV has shown rather strong influence of thermal treatments on Fe/Ti as well as Fe/TiN interfaces.
Observation of substitutional Fe in CEMS measurements on synthetic CVD diamond
2004
Conversion electron Mossbauer spectroscopy measurements have been made on a diamond sample synthesized by chemical vapour deposition. The sample was implanted with 70 keV 57Fe to a dose of 5 × 1014 cm−2 and Mossbauer measurements were made on the as-implanted sample and after annealing at temperatures of 600 K, 950 K and 1470 K. The spectra at the lower temperatures were characterized by broad doublets, but the annealing at 1470 K resulted in dramatic decrease in the intensity of the doublet components, and the appearance of a strong single line with an isomer shift of δ = −0.90(5) mm/s and areal intensity of 30%, and a weaker line (5%) with δ = +0.07(4). Arguments are presented to attribut…
A collision timing monitor for SuperKEKB
2017
Abstract The analysis of beamstrahlung radiation, emitted from a beam of charged particles due to the electromagnetic interaction with a second beam of charged particles, provides a diagnostic tool that can be used to monitor beam–beam collisions in a e + e − storage ring. In this paper we show that the beamstrahlung time profile is related to the timing of the collisions and the length of the beams, and how its measurement can be used to monitor and optimize collisions at the interaction point of the SuperKEKB collider. The method has a unique passive monitor capability, since it allows to monitor the timing of the collision without disturbing (scanning) the beam–beam timing, which needs t…
Optimization of a conversion electron Mössbauer spectroscopy gas flow He/CH4 proportional counter
1992
A new detector for CEMS has been built and optimized with respect to the statistical quality of spectra obtained. The optimization has been performed by measuring Mosbauer and pulse height spectra at in- and off-resonance. Single channel analyzer settings were calculated by a new optimization routine. A comparison of different detector designs has been performed using the statistical utility rate of spectra obtained from a stainless steel foil. A procedure for determining optimal operating parameters for ICEMS gas flow proportional counters is proposed.
High-resolution spectroscopy of gaseous $^\mathrm{83m}$Kr conversion electrons with the KATRIN experiment
2020
In this work, we present the first spectroscopic measurements of conversion electrons originating from the decay of metastable gaseous $^\mathrm{83m}$Kr with the Karlsruhe Tritium Neutrino (KATRIN) experiment. The results obtained in this calibration measurement represent a major commissioning milestone for the upcoming direct neutrino mass measurement with KATRIN. The successful campaign demonstrates the functionalities of the full KATRIN beamline. The KATRIN main spectrometer's excellent energy resolution of ~ 1 eV made it possible to determine the narrow K-32 and L$_3$-32 conversion electron line widths with an unprecedented precision of ~ 1 %.
Corrosion processes and their inhibition as studied by Mössbauer conversion and other electron spectroscopies
1989
To study corrosion processes of iron and steel and measures of their inhibition, a detailed knowledge of the phase composition and of phase transformations in very thin layers close to the attacked surface of the material is necessary. The information depths of integral (ICEMS) and depth selective (DCEMS) conversion electron Mossbauer spectroscopy are well suited for such investigations, but some effort is necessary if technical samples, i.e. nonenriched in57Fe, are to be studied. In many cases of practical importance, full information on the corroded surfaces cannot be got from Mossbauer spectra only, and a combination with Auger and photoelectron spectroscopies, in-including scanning and …
Icems and dcems study of Fe layers evaporated onto Al and Si
1990
Thin layers of57Fe (2.5 nm, 10 nm and 70 nm thickness), vacuum evaporated onto Al and Si plates, have been investigated by conversion electron Mossbauer spectroscopy (CEMS). The measurements were performed employing both a proportional counter and a channeltron for conventional and ultrahigh-vacuum integral CEMS (UHV-ICEMS) studies, respectively, and a channeltron for depth-selective CEMS (DCEMS). The phase analysis of the layers on base of experimental results has indicated the presence of metallic iron and one or two iron compounds, ascribed to iron reaction products formed with the residual gas during evaporation. These products are most likely rather stable iron nitrides, are more or le…