Search results for "BEAM"
showing 10 items of 2126 documents
Optical Properties of Irradiated Yttrium Aluminum Garnet
2012
The results of investigation of the photoluminescence (PL) and optical absorption of crystals Y3Al5O12(YAG) doped with different concentrations of manganese ions exposed to fast neutron irradiation and electron irradiation are presented. Photoluminescence spectra of YAG before neutron irradiation at T=80 K contain fine lines in orange region of spectrum, ascribed to Mn2+ ions in octahedral position. After irradiation band broadening is observed in the luminescence spectra of garnet crystals. Electron irradiation produced broad band with a complex structure related to Mn4+ ions. Exchange interaction between radiation defect and impurity ions during neutron irradiation and electron irradiatio…
Influence of radiation defects on tritium release parameters from Li2O
1998
Abstract The study of the influence of radiation defects on tritium release behavior from polycrystalline Li2O was performed by simultaneous measurements of the luminescence emission and tritium release. It was found that the radiation defects in Li2O introduced by electron irradiation cause the retention of tritium. It is thought that the tritium recovery is affected by the formation of a Li–T bond, which is tolerant of high temperatures. The retardation of tritium decreases with increasing absorbed dose in the dose range from 50 to 140 MGy. The aggregation of radiation defects at high irradiation doses is considered to be responsible for the decrease of the interaction of tritium with rad…
Study of the response of phenol compounds exposed to thermal neutrons beams for Electron Paramagnetic Resonance dosimetry
2015
Abstract This paper reports the results regarding a new organic compound (IRGANOX ® 1076 phenols) with and without low content (5% by weight) of gadolinium oxide (Gd 2 O 3 ) for Electron Paramagnetic Resonance (EPR) dosimetry of neutron beams. The dependence of EPR signal as function of neutron dose was investigated in the fluence range studied between 10 11 cm −2 to 10 14 cm −2 . We evaluated also the effect of gadolinium on 60 Co gamma photon sensitivity of this organic compound. Our analysis showed that a low concentration of gadolinium oxide (of the order of 5% of the total mass of the dosimeter) can enhance the thermal neutron sensitivity more than 10 times with a small reduction of …
Exclusive measurement of quasi-free η-photoproduction from deuterium
2003
Quasi-free photoproduction of eta-mesons from the deuteron has been measured at the tagged photon facility of the Mainz microtron MAMI with the photon spectrometer TAPS for incident photon energies from the production threshold at 630 MeV up to 820 MeV. In a fully exclusive measurement eta-mesons and recoil nucleons were detected in coincidence. At incident photon energies above the production threshold on the free nucleon, where final state interaction effects are negligible, an almost constant ratio of sigma(n)/sigma(p)=0.66+/-0.10 was found. At lower incident photon energies the ratio rises due to re-scattering effects. The average ratio agrees with the value extracted from a comparison …
Discovery of the new isotopes ²⁴⁰Es and ²³⁶Bk and in-beam spectroscopic studies of ²⁴⁴Cf
2017
The hitherto unknown neutron-deficient nuclei 240Es and 236Bk were synthesised using the fusion-evaporation reaction 209Bi(34S,3n)240Es. The ritu gas-filled recoil separator and the great spectrometer were used in this decay spectroscopic study. The measured electron-capture delayed fission (ECDF) branches in both of the new isotopes complement the experimental data available in the heavier odd-odd Es and Bk isotopes. Furthermore, the ECDF branches show a continuation in the exponential increase of the ECDF probabilities as a function of QEC − Bsf when approaching the proton dripline. In addition, an in-beam γ-ray spectroscopic study of the neutron-deficient isotope 244Cf was made using the fus…
Laser assisted decay spectroscopy at the CRIS beam line at ISOLDE
2012
A new collinear resonant ionization spectroscopy (Cris)beam line has recently been installed at Isolde, Cern utilising lasers to combine collinear laser spectroscopy and resonant ionization spectroscopy. The combined technique offers the ability to purify an ion beam that is heavily contaminated with radioactive isobars, including the ground state of an isotope from its isomer, allowing sensitive secondary experiments to be performed. A new programme aiming to use the Cris technique for the separation of nuclear isomeric states for decay spectroscopy will commence in 2011. A decay spectroscopy station, consisting of a rotating wheel implantation system for alpha decay spectroscopy, and thre…
All-Fiber Laser With Intracavity Acousto-Optic Dynamic Mode Converter for Efficient Generation of Radially Polarized Cylindrical Vector Beams
2017
We report an all-fiber laser that emits a radially polarized cylindrical vector beam (CVB) at 1 μm based on an intracavity acousto-optic mode converter. We efficiently generate the CVB, taking advantage of the acousto-optic coupling from the HE11 mode to the TM01 mode in a two-mode fiber. The laser can be switched from emitting a Gaussian-like beam to a radially polarized CVB. Radially polarized CVBs with modal and polarization purities >98% and a maximum power of 65 mW were generated.
Design and development of safety and control systems in ATLAS
2021
El gran colisionador de hadrones, o LHC, es el acelerador de partículas más grande y potente del mundo. Ha sido construido por el CERN, la Organización Europea para la Investigación Nuclear, entre 1998 y 2008 en Ginebra, Suiza. Sucesivas mejoras en el LHC supondrán a partir de mediados del 2027 un incremento de la luminosidad, cuando pasará a llamarse High Luminosity LHC (HL-LHC). Esta tesis se divide en dos partes, por una parte la seguridad y operación de la infraestructura y por otra los sistemas de control y toma de datos. La primera parte de la tesis se dedica a la seguridad y operación de la infraestructura. Después de más de 10 años de funcionamiento, el riesgo de posibles fallos en …
Searches for lepton number violation and resonances in K± → πμμ decays
2017
The NA48/2 experiment at CERN collected a large sample of charged kaon decays to final states with multiple charged particles in 2003–2004. A new upper limit on the rate of the lepton number violating decay K±→π∓μ±μ± is reported: B(K±→π∓μ±μ±)<8.6×10−11 at 90% CL. Searches for two-body resonances X in K±→πμμ decays (such as heavy neutral leptons N4 and inflatons χ ) are also presented. In the absence of signals, upper limits are set on the products of branching fractions B(K±→μ±N4)B(N4→πμ) and B(K±→π±X)B(X→μ+μ−) for ranges of assumed resonance masses and lifetimes. The limits are in the (10−11,10−9) range for resonance lifetimes below 100 ps.
Prevalence and morphometric analysis of the retromolar canal in a Spanish population sample: a helical CT scan study.
2021
BACKGROUND: The retromolar canal (RMC) is an anatomical variation of the mandibular canal (MC) whose identification and study should be considered given its implication in the surgical procedures of the retromolar area. The prevalence of the RMC widely varies according to previous studies and may be influenced by the followed study method. This work aimed to evaluate the prevalence of the RMC in a Spanish population sample. MATERIAL AND METHODS: For this purpose, 225 CT scan images (with a higher resolution than the cone beam CT used in other previous studies) from the Hospital Clinico Universitario de Valencia were analyzed. The Osirix MD radiological image analysis system was applied to a…