Resistive Plate Chambers (RPCs) provide the barrel region of the ATLAS detector with an independent muon trigger and a two-coordinate measurement. The chambers, 3600 gas volumes in total covering a ...surface area of about 4000 m super(2), are arranged in three concentric double layers and operated in a strong magnetic toroidal field. During Run-1 the LHC has provided protonproton collisions at 7 and 8 TeV in the centre-of-mass frame with a steady increase in instantaneous luminosity, summing up to an integrated luminosity of about 30 fb super(-1). For Run-2, a further increase in beam energy, luminosity and also backgrounds is expected with rates and doses approaching the limits for which the RPCs were certified to work at irradiation facilities. In this scenario, a precise and granular monitoring of the detector (gas gap currents, gas flow, trigger rates) along with a safe operation will become even more important. The operational experience from Run-1 and the present plans of upgrade and consolidation are presented along with a discussion from the view point of the detector monitoring and control system.
Background:
Although fine-needle aspiration cytology remains the mainstay of the preoperative workup of thyroid nodules, those with follicular proliferation still represent a diagnostic challenge. ...Real-time elastography (RTE) estimates the stiffness/elasticity of lesions and is regarded as a promising technique for the presurgical selection of thyroid nodules (including those with indeterminate cytology).
Aim:
Our aim was to verify the potential role of RTE in the presurgical diagnosis of cancer in a large cohort of consecutive patients with follicular thyroid nodules.
Patients and Methods:
One hundred two patients were submitted to conventional ultrasonography and RTE evaluation before being operated on for thyroid nodule with indeterminate cytology (54% single nodules). Tissue stiffness on RTE was scored from 1 (greatest elasticity) to 4 (no elasticity).
Results:
At conventional ultrasonography examination, the nodules (median diameter 2.2 cm) were solid (cystic areas < 10%); microcalcifications were detected in 56% of them and a hypoechoic pattern in 64%. Elasticity was high in eight cases only (score 1–2) although low in 94 (score 3–4). Cancer was diagnosed in 36 nodules (35%), being associated with microcalcifications (P < 0.0001) and inversely related to nodule diameter (P < 0.01). Malignancy was detected in 50% of the nodules with RTE score 1–2 and in 34% of those with score 3–4. Therefore, either the positive (34%) or the negative predictive value (50%) was clinically negligible.
Conclusions:
The current study does not confirm the recently reported usefulness of RTE in presurgical selection of nodules with indeterminate cytology and suggest the need for quantitative analytical assessment of nodule stiffness to improve RTE efficacy.
Novel considerations are presented on the physics, apparatus and accelerator designs for a future, luminous, energy frontier electron-hadron (
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) scattering experiment at the LHC in the thirties ...for which key physics topics and their relation to the hadron-hadron HL-LHC physics programme are discussed. Demands are derived set by these physics topics on the design of the LHeC detector, a corresponding update of which is described. Optimisations on the accelerator design, especially the interaction region (IR), are presented. Initial accelerator considerations indicate that a common IR is possible to be built which alternately could serve
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collisions while other experiments would stay on
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in either condition. A forward-backward symmetrised option of the LHeC detector is sketched which would permit extending the LHeC physics programme to also include aspects of hadron-hadron physics. The vision of a joint
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physics experiment is shown to open new prospects for solving fundamental problems of high energy heavy-ion physics including the partonic structure of nuclei and the emergence of hydrodynamics in quantum field theory while the genuine TeV scale DIS physics is of unprecedented rank.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Resistive Plate Chamber detectors are largely used in current High Energy Physics experiments, typically operated in avalanche mode with large fractions of Tetrafluoroethane (C2H2F4), a gas recently ...banned by the European Union due to its high Global Warming Potential (GWP). An intense R&D activity is ongoing to improve RPC technology in view of future HEP applications. In the last few years the RPC EcoGas@GIF++ Collaboration has been putting in place a joint effort between the ALICE, ATLAS, CMS, LHCb/SHiP and EP-DT Communities to investigate the performance of present and future RPC generations with eco-friendly gas mixtures. Detectors with different layout and electronics have been operated with ecological gas mixtures, with and without irradiation at the CERN Gamma Irradiation Facility (GIF++). Results of these performance studies together with plans for an aging test campaign are discussed in this article.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the last few years, an intense R &D activity on particle detectors for future HEP applications has been carried on with the aim of developing new techniques as well as studying the performance of ...already existing detectors when operated in a high rate environment. As for Resistive Plate Chamber detectors, the main challenges to face are the improvement of their detection capabilities and longevity at very high-rates, and the search for new eco-friendly gasmixtures free from greenhouse components. Results obtained in the framework of the RPC ECOGas@GIF++ Collaboration on a thin-Resistive Plate Chamber exposed at the CERN Gamma Irradiation Facility and operated with eco-friendly gas mixtures based on Tetrafluoropropene and Carbon dioxide will be discussed in this paper.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Results obtained by the RPC ECOgas@GIF++ Collaboration, using Resistive Plate Chambers operated with new, eco-friendly gas mixtures, based on tetrafluoropropene and carbon dioxide, are shown and ...discussed in this paper. Tests aimed to assess the performance of this kind of detectors in high-irradiation conditions, analogous to the ones foreseen for the coming years at the Large Hadron Collider experiments, were performed, and demonstrate a performance basically similar to the one obtained with the gas mixtures currently in use, based on tetrafluoroethane, which is being progressively phased out for its possible contribution to the greenhouse effect. Long term aging tests are also being carried out, with the goal to demonstrate the possibility of using these eco-friendly gas mixtures during the whole High Luminosity phase of the Large Hadron Collider.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract The exclusive photoproduction reactions γp → J/ψ(1S)p and γp → ψ(2S)p have been measured at an ep centre-of-mass energy of 318 GeV with the ZEUS detector at HERA using an integrated ...luminosity of 373 pb −1. The measurement was made in the kinematic range 30 < W < 180 GeV, Q 2 < 1 GeV2 and |t| < 1 GeV2, where W is the photon-proton centre-of-mass energy, Q 2 is the photon virtuality and t is the squared four-momentum transfer at the proton vertex. The decay channels used were J/ψ(1S) → μ + μ − , ψ(2S) → μ + μ − and ψ(2S) → J/ψ(1S)π + π − with subsequent decay J/ψ(1S) → μ + μ − . The ratio of the production cross sections, R = σ ψ(2S) /σ J/ψ(1S), has been measured as a function of W and |t| and compared to previous data in photoproduction and deep inelastic scattering and with predictions of QCD-inspired models of exclusive vector-meson production, which are in reasonable agreement with the data.
Introduction:
Human leukocyte antigen-G (HLA-G), a nonclassical major histocompatibility complex class I antigen, plays a pivotal role in immune tolerance and a paradoxical role in cancers.
Aims:
Our ...aims were to evaluate plasma soluble HLA-G (sHLA-G) concentrations and the 14-bp insertion/deletion polymorphism of the HLA-G gene in patients with papillary thyroid carcinoma (PTC) or Hashimoto's thyroiditis (HT) and to assess the possible association of these parameters with PTC aggressiveness.
Methods:
Samples for the analysis of sHLA-G and +14/−14-bp HLA-G polymorphism were obtained from 121 patients with HT and 183 with PTC; 245 gender- and age-matched healthy subjects served as controls. PTC histopathological aggressiveness was defined according to the last American Thyroid Association guidelines.
Results:
Positive serum antithyroid antibody titers were observed in 22% of PTC patients and lymphocyte infiltration of thyroid parenchyma at histological examination in 21%, whereas both circulating and histological autoimmunity was detectable in 12% of PTC patients. No differences in the +14/−14-bp polymorphism frequencies were observed between the study groups. The prevalence of detectable sHLA-G was lower in healthy controls (52%) as compared with both HT (57%) and PTC (62%) patients. By stratifying the study groups according to sHLA-G level of positive subjects, significantly higher plasma sHLA-G values in PTC (42.9 ± 3.3 ng/ml; P = 0.002) and HT patients (49.1 ± 2.6 ng/ml; P < 0.002) as compared with healthy controls (8.5 ± 1.8 ng/ml) were obtained. Moreover, PTC patients with detectable plasma sHLA-G levels showed a higher aggressive behavior (P < 0.04) than those without.
Conclusions:
Although confirming the frequent association between PTC and chronic autoimmune thyroiditis, these data suggest that elevated circulating sHLA-G levels, besides an important signal of alterations of immune homeostasis, may be considered a potential, novel marker of PTC histopathological aggressiveness at diagnosis. Additional studies are needed to confirm the actual role and clinical relevance of the HLA-G complex in PTC development and progression.
Due to their simplicity and comparatively low cost, Resistive Plate Chambers are gaseous detectors widely used in high-energy and cosmic rays physics when large detection areas are needed. However, ...the best gaseous mixtures are currently based on tetrafluoroethane, which has the undesirable characteristic of a large Global Warming Potential (GWP) of about 1400 and because of this, it is currently being phased out from industrial use. As a possible replacement, tetrafluoropropene (which has a GWP close to 1) has been taken into account. Since tetrafluoropropene is more electronegative than tetrafluoroethane, it has to be diluted with gases with a lower attachment coefficient in order to maintain the operating voltage close to 10 kV. One of the main candidates for this role is carbon dioxide. In order to ascertain the feasibility and the performance of tetrafluoropropene-CO2 based mixtures, an R&D program is being carried out in the ALICE collaboration, which employs an array of 72 Bakelite RPCs (Muon Identifier, MID) to identify muons. Different proportions of tetrafluoropropene and CO2, with the addition of small quantities of isobutane and sulphur hexafluoride, have been tested with 50 × 50 cm2 RPC prototypes with 2 mm wide gas gap and 2 mm thick Bakelite electrodes. In the presentation, results from tests with cosmic rays will be presented, together with data concerning the current drawn by a RPC exposed to the gamma-ray flux of the Gamma Irradiation Facility (GIF) at CERN.
Resistive Plate Chambers provide the barrel region of the ATLAS detector with an independent muon trigger and a two-coordinate measurement. The chambers, arranged in three concentric double layers, ...are operated in a strong magnetic toroidal field and cover a surface area of about 4000m super(2). During 2011 the LHC has provided proton-proton collisions at 7 TeV in the center-of-mass frame with a steady increase in instantaneous luminosity, summing up to about 5 fb super(-1). The operational experience for this running period is presented along with studies of the detector performance as a function of luminosity, environmental conditions and working point settings. Non-event based information including in particular the large number of gas gap currents, individually monitored with nA accuracy, have been used to study the detector behavior with growing luminosity and beam currents. These data are shown to provide, when calibrated, an independent luminosity measurement and a crucial handle for understanding the ATLAS backgrounds well beyond the scope of muon triggering and detection. The measurements presented here allow to plan a strategy for the data taking in the next years and make some predictions about the detector performance at higher luminosities. They also improve the knowledge on RPC detector physics.
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