Search results for "Radiation effect"
showing 10 items of 111 documents
Key Contributions to the Cross Section of NAND Flash Memories Irradiated With Heavy Ions
2008
Heavy-ion irradiation of NAND flash memories under operating conditions leads to errors with complex, data-dependent signatures. We present upsets due to hits in the floating gate array and in the peripheral circuitry, discussing their peculiarities in terms of pattern dependence and annealing. We also illustrate single event functional interruptions, which lead to errors during erase and program operations. To account for all the phenomena we observe during and after irradiation, we propose an ldquoeffective cross section,rdquo which takes into account the array and peripheral circuitry contributions to the SEU sensitivity, as well as the operating conditions.
Aging measurements with the gas electron multiplier (GEM)
2001
Abstract Continuing previous aging measurements with detectors based on the Gas Electron Multiplier (GEM), we investigated a 31×31 cm 2 triple-GEM detector, as used in the small area tracking of the COMPASS experiment at CERN. With a detector identical to those installed in the experiment, long-term high-rate exposures to 8.9 keV X-ray radiation were performed to study its aging properties. In standard operation conditions, with Ar/CO2 (70:30) gas filling and operated at an effective gain of 8.5×103, no change in gain and energy resolution is observed after collecting a total charge of 7 mC / mm 2 , corresponding to seven years of normal operation. This observation confirms previous results…
Discrimination of Radiation Quality Through Second Harmonic Out-of-Phase cw-ESR Detection
2014
The ability to discriminate the quality of ionizing radiation is important because the biological effects produced in tissue strongly depends on both absorbed dose and linear energy transfer (LET) of ionizing particles. Here we present an experimental electron spin resonance (ESR) analysis aimed at discriminating the effective LETs of various radiation beams (e.g., 19.3 MeV protons, 60Co photons and thermal neutrons). The measurement of the intensities of the continuous wave spectrometer signal channel first harmonic in-phase and the second harmonic out-of-phase components are used to distinguish the radiation quality. A computational analysis, was carried out to evaluate the dependence of …
A nanodosimetric model of radiation-induced clustered DNA damage yields
2010
International audience; We present a nanodosimetric model for predicting the yield of double strand breaks (DSBs) and non-DSB clustered damages induced in irradiated DNA. The model uses experimental ionization cluster size distributions measured in a gas model by an ion counting nanodosimeter or, alternatively, distributions simulated by a Monte Carlo track structure code developed to simulate the nanodosimeter. The model is based on a straightforward combinatorial approach translating ionizations, as measured or simulated in a sensitive gas volume, to lesions in a DNA segment of one-two helical turns considered equivalent to the sensitive volume of the nanodosimeter. The two model paramete…
Photoluminescence in gamma-irradiated alpha-quartz investigated by synchrotron radiation
2004
Abstract We report an experimental investigation of the photoluminescence, under excitation by synchrotron radiation within the absorption band at 7.6 eV , induced in γ-irradiated α-quartz. Two emissions centered at 4.9 and 2.7 eV are observed at low temperature: the former decreases above 40 K , whereas the second band exhibits an initial slight increase and its quenching is effective above 100 K . Furthermore, the decay kinetics of both emissions occur in a time scale of nanoseconds: at T=17.5 K we measured a lifetime τ∼1.0 ns for the photoluminescence at 4.9 eV and τ∼3.6 ns for that at 2.7 eV . These results give new insight on the optical properties associated with defects peculiar of c…
Radiation responses of Yb/Er-doped phosphosilicate optical fibers: hardening mechanisms related to Ce-codoping
2012
International audience; In this paper, we investigated the origins of the Ce positive influence on the radiation response of Yb/Er-doped phosphosilicate optical fibers. To this purpose, we carried out during γ-irradiations an online characterization on active optical fiber prototypes, made with different Ce concentrations and integrated in optical amplifiers. The hardening effect of Ce-codoping is highlighted, as well as some aspects related to the radiation response of the phosphosilicate host glass of the active optical fibers.
Radiation effects in nitride read-only memories
2010
Abstract We report on the influence of different types of radiation on the nitride read-only memories (NROM®). The memory cells were irradiated by light ions (Boron), X-rays and γ-rays. Memory transistor parameters, such as threshold voltage and subthreshold drain leakage were studied as a function of the accumulated radiation dose and compared to the as-programmed (-erased) devices parameters. Their time evolution was registered in the range from few hours up to 5 months after the irradiation. The NROM® cells showed good radiation robustness up to high accumulated doses. Sufficient program margin (difference of threshold voltage in the programmed state and the read-out voltage level) remai…
Irradiation effects on the absorption edge of silica glass
2007
Abstract Vacuum ultraviolet absorption experiments were carried out on a variety of specimens of amorphous silica β-irradiated at different doses from ∼103 to 5 × 106 kGy. Changes in the width of the absorption (Urbach) edge were investigated. These changes strongly depend on the kind of silica considered: in particular the Urbach energy of silica of industrial manufacture increases in the irradiated samples, whereas in sol–gel silica it is poorly influenced by the irradiation. The fictive temperature of the different materials before and after irradiation was also monitored. The changes of the Urbach energy and of the fictive temperature are tentatively discussed considering the disorder d…
Spectral heterogeneity of oxygen-deficient centers in Ge-doped silica
2004
Abstract We report an experimental investigation of the emission spectra of a 1000 mol ppm sol–gel Ge-doped silica by fine tuning the excitation energy in the ultraviolet (UV) range, around 5 eV , and in the vacuum-UV range, around 7.3 eV , at room temperature and at 10 K . The sample is characterized by a blue (centered at ∼3.2 eV ) and an UV (centered at ∼4.3 eV ) bands. We have found that the ratio between the area of the blue and the UV bands depends on the temperature and on the excitation energy in both the vacuum-UV and the UV range. At both temperatures the spectral features of the blue and the UV bands are weakly affected when the excitation is varied in the vacuum-UV. At variance,…
Variability of the Si-O-Si angle in amorphous-SiO2 probed by electron paramagnetic resonance and Raman spectroscopy
2009
We report an experimental investigation by electron paramagnetic resonance (EPR) and Raman spectroscopy on a variety of amorphous silicon dioxide materials. Our study by EPR have permitted us to point out that the splitting of the primary hyperfine doublet of the Eγ′ center shows a relevant sample-to-sample variability, changing from ∼41.8 to ∼42.6 mT in the set of materials we considered. The parallel study by Raman spectroscopy has enabled us to state that this variability is attributable to the different Si-O-Si angle characterizing the matrices of the different materials. © 2009 Elsevier B.V. All rights reserved.