5,654 research outputs found
Characterisation of AMS H35 HV-CMOS monolithic active pixel sensor prototypes for HEP applications
Monolithic active pixel sensors produced in High Voltage CMOS (HV-CMOS)
technology are being considered for High Energy Physics applications due to the
ease of production and the reduced costs. Such technology is especially
appealing when large areas to be covered and material budget are concerned.
This is the case of the outermost pixel layers of the future ATLAS tracking
detector for the HL-LHC. For experiments at hadron colliders, radiation
hardness is a key requirement which is not fulfilled by standard CMOS sensor
designs that collect charge by diffusion. This issue has been addressed by
depleted active pixel sensors in which electronics are embedded into a large
deep implantation ensuring uniform charge collection by drift. Very first small
prototypes of hybrid depleted active pixel sensors have already shown a
radiation hardness compatible with the ATLAS requirements. Nevertheless, to
compete with the present hybrid solutions a further reduction in costs
achievable by a fully monolithic design is desirable. The H35DEMO is a large
electrode full reticle demonstrator chip produced in AMS 350 nm HV-CMOS
technology by the collaboration of Karlsruher Institut f\"ur Technologie (KIT),
Institut de F\'isica d'Altes Energies (IFAE), University of Liverpool and
University of Geneva. It includes two large monolithic pixel matrices which can
be operated standalone. One of these two matrices has been characterised at
beam test before and after irradiation with protons and neutrons. Results
demonstrated the feasibility of producing radiation hard large area fully
monolithic pixel sensors in HV-CMOS technology. H35DEMO chips with a substrate
resistivity of 200 cm irradiated with neutrons showed a radiation
hardness up to a fluence of ncm with a hit efficiency of
about 99% and a noise occupancy lower than hits in a LHC bunch
crossing of 25ns at 150V
Prototyping of an HV-CMOS demonstrator for the High Luminosity-LHC upgrade
HV-CMOS sensors can offer important advantages in terms of material budget, granularity and cost for large area tracking systems in high energy physics experiments. This article presents the design and simulated results of an HV-CMOS pixel demonstrator for the High Luminosity-LHC. The pixel demonstrator has been designed in the 0.35 μm HV-CMOS process from ams AG and submitted for fabrication through an engineering run. To improve the response of the sensor, different wafers with moderate to high substrate resistivities are used to fabricate the design. The prototype consists of four large analog and standalone matrices with several pixel flavours, which are all compatible for readout with the FE-I4 ASIC. Details about the matrices and the pixel flavours are provided in this article
Structural determinants in ApoA-I amyloidogenic variants explain improved cholesterol metabolism despite low HDL levels.
Twenty Apolipoprotein A-I (ApoA-I) variants are responsible for a systemic hereditary amyloidosis in which protein fibrils can accumulate in different organs, leading to their failure. Several ApoA-I amyloidogenic mutations are also associated with hypoalphalipoproteinemia, low ApoA-I and high-density lipoprotein (HDL)-cholesterol plasma levels; however, subjects affected by ApoA-I-related amyloidosis do not show a higher risk of cardiovascular diseases (CVD). The structural features, the lipid binding properties and the functionality of four ApoA-I amyloidogenic variants were therefore inspected in order to clarify the paradox observed in the clinical phenotype of the affected subjects. Our results show that ApoA-I amyloidogenic variants are characterized by a different oligomerization pattern and that the position of the mutation in the ApoA-I sequence affects the molecular structure of the formed HDL particles. Although lipidation increases ApoA-I proteins stability, all the amyloidogenic variants analyzed show a lower affinity for lipids, both in vitro and in ex vivo mouse serum. Interestingly, the lower efficiency at forming HDL particles is compensated by a higher efficiency at catalysing cholesterol efflux from macrophages. The decreased affinity of ApoA-I amyloidogenic variants for lipids, together with the increased efficiency in the cholesterol efflux process, could explain why, despite the unfavourable lipid profile, patients affected by ApoA-I related amyloidosis do not show a higher CVD risk
Management of imatinib-resistant CML patients
Imatinib has had marked impact on outcomes in chronic myelogenous leukemia (CML) patients for all stages of the disease and is endorsed by international treatment guidelines as the first line option. Although imatinib is highly effective and well tolerated, the development of resistance represents a clinical challenge. Since the most frequently identified mechanism of acquired imatinib resistance is bcr-abl kinase domain point mutations, periodic hematologic, cytogenetic, and molecular monitoring is critical throughout imatinib therapy. Once cytogenetic remission is achieved, residual disease can be monitored by bcr-abl transcript levels as assayed by reverse transcription polymerase chain reaction (RT-PCR). Detection of bcr-abl mutants prior to and during imatinib therapy can aid in risk stratification as well as in determining therapeutic strategies. Thus, mutation screening is indicated in patients lacking or losing hematologic response. Moreover, search for mutations should also be performed when a 3-log reduction of bcr-abl transcripts is not achieved or there is a reproducible increase of transcript levels. In patients harboring mutations which confer imatinib resistance, novel second line tyrosine kinase inhibitors have demonstrated encouraging efficacy with low toxicity. Only the T315I bcr-abl mutant has proved totally resistant to all clinically available bcr-abl inhibitors. Strategies to further increase the rates of complete molecular remissions represent the next frontier in the targeted therapy of CML patients
Tourism income and economic growth in Greece: Empirical evidence from their cyclical components
This paper examines the relationship between the cyclical
components of Greek GDP and international tourism income for
Greece for the period 1976–2004. Using spectral analysis the authors
find that cyclical fluctuations of GDP have a length of about nine
years and that international tourism income has a cycle of about
seven years. The volatility of tourism income is more than eight
times the volatility of the Greek GDP cycle. VAR analysis shows that
the cyclical component of tourism income is significantly influencing
the cyclical component of GDP in Greece. The findings support the
tourism-led economic growth hypothesis and are of particular
interest and importance to policy makers, financial analysts and
investors dealing with the Greek tourism industry
A double-sided silicon micro-strip super-module for the ATLAS inner detector upgrade in the high-luminosity LHC
The ATLAS experiment is a general purpose detector aiming to fully exploit the discovery potential of the Large Hadron Collider (LHC) at CERN. It is foreseen that after several years of successful data-taking, the LHC physics programme will be extended in the so-called High-Luminosity LHC, where the instantaneous luminosity will be increased up to 5 × 1034 cm−2 s−1. For ATLAS, an upgrade scenario will imply the complete replacement of its internal tracker, as the existing detector will not provide the required performance due to the cumulated radiation damage and the increase in the detector occupancy. The current baseline layout for the new ATLAS tracker is an all-silicon-based detector, with pixel sensors in the inner layers and silicon micro-strip detectors at intermediate and outer radii. The super-module is an integration concept proposed for the strip region of the future ATLAS tracker, where double-sided stereo silicon micro-strip modules are assembled into a low-mass local support structure. An electrical super-module prototype for eight double-sided strip modules has been constructed. The aim is to exercise the multi-module readout chain and to investigate the noise performance of such a system. In this paper, the main components of the current super-module prototype are described and its electrical performance is presented in detail
HV/HR-CMOS sensors for the ATLAS upgrade—concepts and test chip results
In order to extend its discovery potential, the Large Hadron Collider (LHC) will have a major upgrade (Phase II Upgrade) scheduled for 2022. The LHC after the upgrade, called High-Luminosity LHC (HL-LHC), will operate at a nominal leveled instantaneous luminosity of 5× 1034 cm−2 s−1, more than twice the expected Phase I . The new Inner Tracker needs to cope with this extremely high luminosity. Therefore it requires higher granularity, reduced material budget and increased radiation hardness of all components. A new pixel detector based on High Voltage CMOS (HVCMOS) technology targeting the upgraded ATLAS pixel detector is under study. The main advantages of the HVCMOS technology are its potential for low material budget, use of possible cheaper interconnection technologies, reduced pixel size and lower cost with respect to traditional hybrid pixel detector. Several first prototypes were produced and characterized within ATLAS upgrade R&D effort, to explore the performance and radiation hardness of this technology.
In this paper, an overview of the HVCMOS sensor concepts is given. Laboratory tests and irradiation tests of two technologies, HVCMOS AMS and HVCMOS GF, are also given
Study of single muons with the Large Volume Detector at Gran Sasso Laboratory
The present study is based on the sample of about 3 mln single muons observed
by LVD at underground Gran Sasso Laboratory during 36500 live hours from June
1992 to February 1998. We have measured the muon intensity at slant depths from
3 km w.e. to 20 km w.e. Most events are high energy downward muons produced by
meson decay in the atmosphere. The analysis of these muons has revealed the
power index of pion and kaon spectrum: 2.76 \pm 0.05. The reminders are
horizontal muons produced by the neutrino interactions in the rock surrounding
LVD. The value of this flux is obtained. The results are compared with Monte
Carlo simulations and the world data.Comment: 13 pages, 2 figures, accepted for publication in "Physics of Atomic
Nuclei
Multijet production in neutral current deep inelastic scattering at HERA and determination of α_{s}
Multijet production rates in neutral current deep inelastic scattering have been measured in the range of exchanged boson virtualities 10 5 GeV and –1 < η_{LAB}^{jet} < 2.5. Next-to-leading-order QCD calculations describe the data well. The value of the strong coupling constant α_{s} (M_{z}), determined from the ratio of the trijet to dijet cross sections, is α_{s} (M_{z}) = 0.1179 ± 0.0013 (stat.)_{-0.0046}^{+0.0028}(exp.)_{-0.0046}^{+0.0028}(th.)
Upper Limit on the Prompt Muon Flux Derived from the LVD Underground Experiment
We present the analysis of the muon events with all muon multiplicities
collected during 21804 hours of operation of the first LVD tower. The measured
depth-angular distribution of muon intensities has been used to obtain the
normalization factor, A, the power index, gamma, of the primary all-nucleon
spectrum and the ratio, R_c, of prompt muon flux to that of pi-mesons - the
main parameters which determine the spectrum of cosmic ray muons at the sea
level. The value of gamma = 2.77 +/- 0.05 (68% C.L.) and R_c < 2.0 x 10^-3 (95%
C.L.) have been obtained. The upper limit to the prompt muon flux favours the
models of charm production based on QGSM and the dual parton model.Comment: 10 pages, 4 figures, RevTex. To appear in Phys. Rev.
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