Proton beams were successfully steered through the entire ring of the CERN Large Hadron Collider (LHC) on September the 10th of 2008. A reasonable lifetime was achieved for the counterclockwise beam, ...namely beam 2, after the radiofrequency capture of the particle bunch was established. This provided the unique opportunity of acquiring turn-by-turn betatron oscillations for a maximum of 90 turns right at injection. Transverse coupling was not corrected and chromaticity was estimated to be large. Despite this largely constrained scenario, reliable optics measurements have been accomplished. These measurements together with the application of new algorithms for the reconstruction of optics errors have led to the identification of a dominant error source.
The beam-gas vertex (BGV) detector is an innovative instrument measuring noninvasively the transverse beam size in the Large Hadron Collider (LHC) using reconstructed tracks from beam-gas ...interactions. The BGV detector was installed in 2016 as part of the R&D for the High-Luminosity LHC project. It allows beam size measurements throughout the LHC acceleration cycle with high-intensity physics beams. A precision better than 2% with an integration time of less than 30 s is obtained on the average beam size measured, while the transverse size of individual proton bunches is measured with a resolution of 5% within 5 min. Particles emerging from beam-gas interactions in a specially developed gas volume along the beam direction are recorded by two tracking stations made of scintillating fibers. A scintillator trigger system selects, on-line, events with tracks originating from the interaction region. All the detector elements are located outside the beam vacuum pipe to simplify the design and minimize interference with the accelerated particle beam. The beam size measurement results presented here are based on the correlation between tracks originating from the same beam-gas interaction vertex.
► GD-QMS studies of high temperature oxide film formed on Alloy 690. ► Defect density reduced with increase in temperature. ► Electrochemical behaviour of oxide film correlated to the Cr-content in ...oxide.
High temperature passivation studies on Alloy 690 were carried out in lithiated water at 250
°C, 275
°C and 300
°C for 72
h. The passive films were characterized by glow discharge-quadrupole mass spectroscopy (GD-QMS) for compositional variation across the depth and micro laser Raman spectroscopy for oxide composition on the surface. The defect density in the oxide films was established from the Mott–Schottky analysis using electrochemical impedance spectroscopy. Electrochemical experiments at room temperature in chloride medium revealed best passivity behaviour by the oxide film formed at 300
°C for 72
h. The electrochemical studies were correlated to the chromium (and oxygen) content of the oxide films. Autoclaving at 300
°C resulted in the best passive film formation on Alloy 690 in lithiated water.
The ENUBET experiment is developing a new narrow-band neutrino beam in which the flux and the flavor composition are known at 1
level, and the energy with O(10
) precision. Such a goal is ...accomplished monitoring the associated charged leptons produced in the decay region of the ENUBET facility:
and
from kaons are measured by a segmented calorimeter instrumenting the walls of the decay tunnel, while muon stations after the hadron dump can monitor muons from pions. We report an update on the status of the project.
Austenitic stainless steels are the main materials of construction in nuclear spent fuel reprocessing and waste management plants that use nitric acid (HNO^sub 3^ as the process fluid. In this study, ...it has been shown that the potential, attained either by addition of oxidizing ions or by external application, determines the corrosion behavior of stainless steels. An equation derived from curve fitting of the measured corrosion data is proposed for predicting the corrosion rates of a specific stainless steel at any given operating potential. The influence of microstructure ("step," "dual," and "ditch") of Type 304L (UNS S30403) stainless steel was also studied. PUBLICATION ABSTRACT
The focus of the study is to establish the role of nitrogen addition to type 304L stainless steel, in sensitised condition, on the crack growth rate (CGR) by intergranular stress corrosion cracking ...(IGSCC) in the simulated boiling water reactor (BWR) environment. The CGR studies were carried out for two heats of type 304L stainless steel with 0.10 and 0.16
wt.% nitrogen and at different dissolved oxygen (DO) levels in high temperature demineralised water whose chemistry was maintained in a recirculating loop. The degree of sensitisation (DOS) was characterised quantitatively by double loop electrochemical potentiodynamic reactivation (DL-EPR) technique. The results clearly show that the susceptibility to IGSCC was substantially lower in the stainless steel with a higher level of nitrogen as reflected by the CGR values. This was attributed to the beneficial role of nitrogen addition against sensitization i.e. lesser coverage of the chromium depleted regions and higher level of chromium in the depleted regions in the stainless steels with higher nitrogen content.
Aluminium coatings were electrodeposited on Fe9Cr1Mo steel from AlCl
3
-1-ethyl-3-methyl imidazolium chloride ionic liquid at room temperature and the effect of solution stirring on deposition rate, ...preferred crystal orientation, surface morphology and roughness have been investigated. Aluminium coating could not be obtained in the unstirred solution for a deposition current density of 20 mA cm
−2
or higher. However, vigorous stirring of the bath enabled the deposition at a current density of 20 mA cm
−2
or higher, along with a significant increase in coating thickness. On the other hand, roughness of the coating increased at higher stirring speeds. X-ray diffraction measurement showed 26% increase in normalised intensity of (111) reflection on increasing the stirring speed up to 800 rev min
−1
, whereas the intensity of (200) reflection was found to be decreased by 37%. Scanning electron microscopy and energy dispersive X-ray analysis of the anodised aluminium showed formation of less porous aluminium oxide film.
The corrosion behavior of Type 304L (UNS S30403) nitric acid grade (NAG) stainless steel in boiling 9 M and 1 M nitric acid (HNO3) and with the addition of 0.03 M sodium fluoride (NaF) and with ...fluoride complexed with 0.06 M to 0.15 M aluminum nitrate (AlNO33) and 0.015 to 0.0375 M zirconium nitrate (ZrNO34) has been established. The corrosion behavior has also been studied using potentiodynamic polarization in the same environments at room temperature and at near boiling temperature and correlated to the measured corrosion rates. It was shown that the fluoride addition accelerates anodic dissolution. The surface film formed on stainless steel was analyzed using x-ray photoelectron spectroscopy to show that fluorides do not remain attached to the surface. The effect of different ratios of complexing with Al(NO3)3 and Zr(NO3)4 has been studied, showing more effectiveness of zirconium. The corrosion behavior of Types 304L, 304L (welded), 310L (UNS S31000) stainless steels and Alloy 690 (UNS N06690) was established in boiling HNO3 and HNO3 with complexed fluoride and in its vapor and condensate phases. The corrosion rates were shown to be higher in the vapor phase than in the concentrate phase for all the materials tested. The differences in the corrosion rates measured in 48 h or 120 h exposures have been explained.
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