Performance of triple GEM prototypes has been evaluated by means of a muon beam at the H4 line of the SPS test area at CERN. The data from two planar prototypes have been reconstructed and analyzed ...offline with two clusterization methods: the center of gravity of the charge distribution and the micro Time Projection Chamber (μTPC). GEM prototype performance evaluation, performed with the analysis of data from a TB, showed that two-dimensional cluster efficiency is above 95% for a wide range of operational settings. Concerning the spatial resolution, the charge centroid cluster reconstruction performs extremely well with no magnetic field: the resolution is well below 100 μm. Increasing the magnetic field intensity, the resolution degrades almost linearly as effect of the Lorentz force that displaces, broadens and asymmetrizes the electron avalanche. Tuning the electric fields of the GEM prototype we could achieve the unprecedented spatial resolution of 190 μm at 1 Tesla. In order to boost the spatial resolution with strong magnetic field and inclined tracks a μTPC cluster reconstruction has been investigated. Such a readout mode exploits the good time resolution of the GEM detector and electronics to reconstruct the trajectory of the particle inside the conversion gap. Beside the improvement of the spatial resolution, information on the track angle can be also extracted. The new clustering algorithm has been tested with diagonal tracks with no magnetic field showing a resolution between 100 μm and 150 μm for the incident angle ranging from 10° to 45°. Studies show similar performance with 1 Tesla magnetic field. This is the first use of a μTPC readout with a triple GEM detector in magnetic field. This study has shown that a combined readout is capable to guarantee stable performance over a broad spectrum of particle momenta and incident angles, up to a 1 Tesla magnetic field.
The Beijing Electron Spectrometer III (BESIII) is a multipurpose detector that collects data provided by the collision in the Beijing Electron Positron Collider II (BEPCII), hosted at the Institute ...of High Energy Physics of Beijing. Since the beginning of its operation, BESIII has collected the world largest sample of J/{\psi} and {\psi}(2s). Due to the increase of the luminosity up to its nominal value of 10^33 cm-2 s-1 and aging effect, the MDC decreases its efficiency in the first layers up to 35% with respect to the value in 2014. Since BESIII has to take data up to 2022 with the chance to continue up to 2027, the Italian collaboration proposed to replace the inner part of the MDC with three independent layers of Cylindrical triple-GEM (CGEM). The CGEM-IT project will deploy several new features and innovation with respect the other current GEM based detector: the {\mu}TPC and analog readout, with time and charge measurements will allow to reach the 130 {\mu}m spatial resolution in 1 T magnetic field requested by the BESIII collaboration. In this proceeding, an update of the status of the project will be presented, with a particular focus on the results with planar and cylindrical prototypes with test beams data. These results are beyond the state of the art for GEM technology in magnetic field.
Performance of triple GEM prototypes has been evaluated by means of a muon beam at the H4 line of the SPS test area at CERN. The data from two planar prototypes have been reconstructed and analyzed ...offline with two clusterization methods: the enter of gravity of the charge distribution and the micro Time Projection Chamber (\muTPC). Concerning the spatial resolution, the charge centroid cluster reconstruction performs extremely well with no magnetic field: the resolution is well below 100 \mum . Increasing the magnetic field intensity, the resolution degrades almost linearly as effect of the Lorentz force that displaces, broadens and asymmetrizes the electron avalanche. Tuning the electric fields of the GEM prototype we could achieve the unprecedented spatial resolution of 190 \mum at 1 Tesla. In order to boost the spatial resolution with strong magnetic field and inclined tracks a \muTPC cluster reconstruction has been investigated. Such a readout mode exploits the good time resolution of the GEM detector and electronics to reconstruct the trajectory of the particle inside the conversion gap. Beside the improvement of the spatial resolution, information on the track angle can be also extracted. The new clustering algorithm has been tested with diagonal tracks with no magnetic field showing a resolution between 100 um and 150 um for the incident angle ranging from 10{\deg} to 45{\deg} . Studies show similar performance with 1 Tesla magnetic field. This is the first use of a \muTPC readout with a triple GEM detector in magnetic field. This study has shown that a combined readout is capable to guarantee stable performance over a broad spectrum of particle momenta and incident angles, up to a 1 Tesla magnetic field.
We investigate the evolution of waves driven by the linearly polarized Alfvén wave in the magnetic field‐aligned cross‐field shear flow. The generated electric field is derived in ideal MHD using ...analytical solutions for the driven waves. A single particle dynamics in the generated electromagnetic field is considered and governing equations for the particle's total kinetic energy and particle parallel velocity are obtained. Our goal is to show how the driven wave inclusion modifies the evolution of these quantities. It is shown that the total kinetic energy of the particle as well as the particle's parallel velocity is not conserved in the driven wave fields and there is a force exerted on particles. A specific example is considered using solar coronal hole plasma parameters. The process presented in this work might also be important in the laboratory, terrestrial and astrophysical plasma processes where the inhomogeneous flows are present.
Key Points
Driven wave generated electric field in the solar corona
The European integration processes is not losing its topicality to this day. It still remains as the important political challenge of the 21st century in the geopolitical area of the modern world. In ...these processes Georgia is actively participating today too, as it is known an agreement of the association between Georgia and the European Union was signed in summer 2014. This fact was a landmark of the greatest historical importance for Georgian people. It means returning of the Georgian people to its initial homeland-Europe, which always struggled and strived for it. It must be noted that we are not entering the Europe with empty hands but are widely credited with the propaganda of European qualities and bringing them to Georgia. It is still not widely known to the general public that at the starting point of uniting the European Union (European Confederation) were standing famous Georgian scientists and public figures. M. Muskhelishvili and A. Nikuradze. While Robert Schuman and Jean Monnet talked about the idea of uniting Europe, M. Muskhelishvili and A. Nikuradze were publishing articles on the same subject in the leading newspapers and magazines and actively participated in the processes of creating the European Union.
We revisit our earlier study of the evolution of an initial propagating Alfven wave in a magnetic-field-aligned flow with a cross-field velocity shear. Our goal is to show how the Alfven wave drives ...up plasma density fluctuations which might be observed and serve as a signature of the presence of Alfven waves in regions such as the solar corona which are inaccessible to direct observations. Here, we introduce a new initial condition which takes into account the initial distortion of the streamlines by the Alfven wave, and we present new analytical results for the driven waves. We find that the density fluctuations of a properly placed linearly polarized Alfven wave in a shear flow are much smaller than we originally estimated.
An endoscopic transorbital approach has been recently included in the neurosurgical armamentarium. 1 We present a case of a 31-year-old female patient with a history of recent-onset refractory ...epilepsy related to a left temporal pole cavernoma operated through a superior eyelid endoscopic transorbital approach. The operative video shows the key surgical steps to ensure optimal surgical freedom, adequate exposure, and complete tumor resection. 2 The postoperative course was uneventful, and the patient obtained seizure control and good cosmetic results without postoperative complications. The brain computed tomography and MRI showed the size of bone removal and confirmed the complete removal of the lesion, respectively. At 3-month follow-up, the patient is epileptic seizures-free without medications. An endoscopic transorbital approach provides adequate exposure of the temporal pole, allowing safe tumor resection. Complication avoidance encompasses careful dissection of palpebral muscles, dynamic orbital retraction, and neuronavigation guidance; sphenoidal drilling according to key anatomic landmarks (eg, sagittal crest 3 ); and anatomic knowledge of the cavernous sinus and internal carotid artery and its tributaries course from a transorbital perspective 4 and reconstruction filling the empty spaces using fat, fascia lata, or dural substitutes. All procedures performed were approved by the ethics committee of both centers and in accordance with Declaration of Helsinki and its later amendments. The patient consented to the procedure and to the publication of her images, and appropriate consent was obtained for publication of cadaveric images.
Purpose:Remote access thyroid surgery using a bilateral axillary breast approach (BABA) or a transoral endoscopic thyroidectomy vestibular approach (TOETVA) are increasingly performed worldwide. In ...the Caucasus, these methods were first applied in the Republic of Georgia. This study compares these two methods of endoscopic thyroid surgery performed on patients in a tertiary hospital in Tbilisi, Georgia. Methods: Between December 2015 and January 2018, 41 patients underwent endoscopic thyroid surgery at the Aversi Clinic, including 32 who underwent BABA endoscopic thyroidectomy for benign nodules and nine who underwent TOETVA for thyroid cancers. Patients’ medical records were retrospectively reviewed. Results: Tumors were significantly larger (2.38±0.38cm versus 1.70±0.31cm, p-value < 0.001), operation time was significantly longer (177.66±21.02 min versus 116.66±5.59 min, p-value < 0.001), and blood loss was significantly greater (149.07±28.10 ml versus 102.22±8.33 ml, p-value < 0.001) in patients who underwent BABA than TOETVA. There were no significant difference in postoperative complications between the two groups. Conclusions: Remote access thyroid surgery, either BABA or TOETVA, was successfully started, without harmful complications, at the Aversi Clinic in Tbilisi, Georgia. BABA is suitable for large sized benign nodules and TOETVA for thyroid cancers with central lymph node dissection. KCI Citation Count: 0
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