We report about the development status of large area gaseous single photon detectors based on a novel hybrid concept for RICH applications.
The hybrid concept combines Thick Gaseous Electron ...Multipliers (THGEMs) coupled to CsI, working as a photon sensitive pre-amplification stage, and Micromegas, as a multiplication stage. The most recent achievements within the research and development programme consist in the assembly and study of 300×300mm2 hybrid photon detectors, the optimization of front-end electronics, and engineering towards large area detectors. Hybrid detectors with an active area of 300×300mm2 have been successfully operated in laboratory conditions and at a CERN PS T10 test beam, achieving effective gains in the order of 105 and good time resolution (σ=7ns); APV25 front-end chips have been coupled to the detector resulting in noise levels lower than 1000 electrons; the production and characterization of 300×600mm2 THGEMs is ongoing.
A set of hybrid detectors with 600×600mm2 active area is envisaged to upgrade COMPASS RICH-1 at CERN in 2016.
•The hybrid detector is a novel concept for large area gaseous photon detectors.•The hybrid concept combines Thick Gaseous Electron Multipliers and Micromegas.•The COMPASS RICH-1 upgrade will adopt hybrid detectors to replace the existing MWPCs
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We are developing large size THick GEM (THGEM)-based detectors of single photons, mainly meant for Cherenkov imaging applications. The R&D programme includes the complete characterisation of the ...THGEM electron multipliers, the study of the aspects related to the detection of single photons and the engineering towards large size detector prototypes. Our most recent achievements include dedicated studies concerning the ion backflow to the photocathode; relevant progress in the engineering aspects, in particularly related to the production of large-size THGEMs, where the strict correlation between the local gain-value and the local thickness-value has been demonstrated and a 300300 mm super(2) active area detector has been successfully operated at the CERN PS T10 test beam; the introduction of a new hybrid detector architecture, offering promising performance, which is formed by a THGEM layer which acts both as photocathode and pre-amplification device, followed by a MICROMEGAS (MM) multiplication stage. We report about the general status of the R&D programme and, in detail, about the recent progress.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
43.
THGEM-based photon detectors for the upgrade of COMPASS RICH-1 Alexeev, M.; Birsa, R.; Bradamante, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Volume:
732
Journal Article
Peer reviewed
Open access
New Cherenkov photon detectors are being developed for the upgrade of COMPASS RICH-1. The detectors are based on THGEMs, arranged in a three layer architecture, with a CsI film on the first layer ...acting as a reflective photocathode. The response of THGEMs with various geometries under different conditions has been studied and photon detector prototypes have been built, tested in laboratory and operated during test beam runs providing a typical gain of 105 and a time resolution of better than 10ns. A photon detector prototype with 300×300mm2 active area, operated at the CERN PS T10 test beam in November 2012, has confirmed the validity of this novel technology and has allowed further studies of the detector response.
•The COMPASS THGEM R&D team has performed systematic studies and parameter optimization for THGEMs to be used in RICH applications.•A triple-THGEM photon detector with 300×300mm2 active area has been successfully tested at the CERN PS T10 test-beam.•A photon detector prototype based on coupling THGEM and Micromegas has provided encouraging results in laboratory tests.•For the upgrade of COMPASS RICH-1 a set of THGEM-based photon detectors will be produced.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
As placement of implants into immediate sites involves management of the remaining root structure, these residual roots may be used as a guide for the development of osteotomy. This aids in implant ...positioning and prevents drill slippage into the residual root spaces during osteotomy drilling. Following completion of the osteotomy, the remaining root structure is extracted prior to implant placement into the site. The aim of this study is to assess the success rate of implants when the residual roots were used as anatomical guides for osteotomy. One hundred implants were placed in 57 patients, and 4 different types of implants were used: 47 Bioner TOP DM implants, 20 Nobel Biocare Replace implants, 25 Biohorizons Tapered Internal implants (Birmingham, Ala), and 8 Alpha-Bio Tec SPI Implants. The implants were placed into 57 patients. Osteotomies were placed through intact residual roots, which acted as anatomical guides for implant surgical placement. Patients had a follow-up period of 2 years, and in that time none reported discomfort after implant placement. There were no signs of peri-implantitis observed in any of the patients. Of all the implants placed, the Bioner TOP DM implant showed the least amount of crestal bone loss. Placing implants through residual roots as an anatomical guide is a useful technique that shows good results over a 2-year follow-up period.
Typically, the posterior maxilla demonstrates the lowest density of bone in the oral cavity. The posterior edentulous maxilla also presents special challenges in implant placement compared with other ...areas of the mouth due to progressive resorption that results in less available bone. This poor quality and quantity of available bone challenges the essential condition for successful implant placement. The maxillary sinus is an air cavity located in the maxilla that enlarges after tooth loss, complicating implant placement in this region. It is pyramidal in shape and is frequently reinforced with internal vertical septa, creating further intrasinus cavities. The use of a trephine allows better prepared osteotomy in less time, making the procedure comfortable for the clinician and the patient and providing greater confidence and security. The membrane perforation risk during osteotomy is minimal, thereby reducing related complications. However, clinician must be experienced in using a trephine and should be used with caution.
•Dechlorination of CF3OCFClCF2Cl to produce unsaturated CF3OCF=CF2 was studied.•Hydrodechlorination over metal-supported catalysts led to a new sustainable process.•A wider diversity in reaction ...products was obtained with Ru, Ni and Pd catalysts.•Pd/Ru and Pd/Cu carbon-supported catalysts resulted very active and selective.
In this work the hydrogen-assisted dechlorination of CF3OCFClCF2Cl to produce unsaturated CF3OCF=CF2 was studied over a series of metal catalysts supported on activated carbon. The results obtained indicated that the activity, stability, and selectivity of the materials were strongly dependent on the metal used. The activity of the monometallic catalysts follows the order Pd/C>Ru/C> Ni/C, while the sequence Ru/C>Ni/C>Pd/C was found for the selectivity to the target product. A wide diversity in reaction products was obtained with these materials. Pd-supported samples mainly yield saturated products. In contrast, CF3OCF=CF2 was the product most formed with Ru/C catalysts which, nevertheless, showed the lowest stability. However, when Ru or Cu was added to Pd catalysts, some very active, stable, and selective materials were obtained. Spent samples were characterized by TPD/MS, TGA, XRD, and FESEM techniques. The results obtained revealed that Ru-based catalyst deactivation was mainly due to the formation of heavy halogenated carbonaceous deposits.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Veterinary dentistry has tended to follow the trends and advancements in the human dental field. As for any procedure performed on a patient, whether human or animal, an informed decision is based on ...the available evidence regarding treatment options. This is certainly true for the more involved treatments in veterinary dentistry which can include the disciplines of endodontics and dental implantology. A number of published case reports have been accepted by the specialty that endodontic therapy is indeed a predictable and a valuable service that can be offered to pet owners. Oral implantology has become an accepted and predictable procedure in the human dental field and can now be offered to pet owners if performed by suitable trained veterinary clinicians. The success rate for endosseous implant osseointegration is very high in humans. Success rates are also very high in animals used for implantology research. Canine studies have shown good bone-to-implant contact of around 73% in osseointegrated endosseous implants based on histological sections. Radiographic and histological findings demonstrate stable alveolar crestal bone levels after loading endosseous implants for up to 12 months in a dog model. This article discusses use of dental implants in the rostral mandible of a companion dog to replace periodontally diseased incisors, their restoration, to return the animal to full dental function and 3-year follow-up.
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CMK, NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
BACKGROUND:Magnetic resonance-guided focused ultrasound (MRgFUS) is a novel imaging-guided surgical technique that allows the performance of noninvasive and radiation-free ablation. Presently, ...computed tomography (CT)-guided radiofrequency ablation, a minimally invasive percutaneous technique, is the standard for treating symptomatic osteoid osteomas. The purpose of this study was to evaluate the use of MRgFUS ablation for the treatment of nonspinal osteoid osteomas in terms of technical success, complications, and clinical success through one year of follow-up.
METHODS:In this prospective multicenter study, thirty consecutive patients with a nonspinal osteoid osteoma were enrolled between May 2010 and April 2012 at three different university centers; twenty-nine of the patients were treated with use of MRgFUS. Lesions had been previously diagnosed on the basis of imaging, including dynamic contrast-enhanced MR. The mean number of sonications and energy deposition were determined. Technical success was evaluated through an assessment of complications immediately after treatment. Clinical success was determined on the basis of pain reduction as measured with a visual analog scale (VAS), recurrence, and long-term complications through twelve months.
RESULTS:Technical success of MRgFUS was observed for all twenty-nine patients. The mean number of sonications (and standard deviation) was 7 ± 3, and the mean delivered acoustic energy was 1180 ± 736 J. At the twelve-month follow-up, complete clinical success was observed in twenty-six (90%) of the twenty-nine patients (95% confidence interval CI = 84 to 95; mean VAS, 0 ± 0 points). Partial success was observed in three (10%) of the twenty-nine patients (95% CI = 5 to 16; mean VAS score, 5 ± 0 points); two of these patients subsequently underwent CT-guided radiofrequency ablation, and one underwent open surgery. Pain score values showed a significant reduction (p < 0.001) between baseline (mean VAS score, 8 ± 1 points) and post treatment (mean VAS score, 1 ± 2 points). No complications were observed.
CONCLUSIONS:MRgFUS may be an effective and safe alternative approach in the treatment of nonspinal osteoid osteoma. A complete clinical success rate of 90% was demonstrated without adverse events. MRgFUS is totally noninvasive and eliminates radiation exposure.
LEVEL OF EVIDENCE:Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Background
Thoracic mesenchymal hamartomas are rare benign lesions. Rarely symptomatic, they may compress pulmonary parenchyma, leading to respiratory distress. Although spontaneous regression has ...been documented, the more common outcome is progressive growth. The treatment of choice is en bloc excision of the involved portion of the chest wall, frequently leading to significant deformity.
Objective
The aim of our study was to describe percutaneous techniques to treat these lesions.
Materials and methods
We collected data of children with thoracic mesenchymal hamartomas who were treated at our institution from 2005 to 2020 using various percutaneous techniques. Techniques included radiofrequency thermoablation, microwave thermoablation (microwave thermoablation) and cryoablation.
Results
Five children were treated for chest wall hamartomas; one child showed bilateral localization of the mass. Two children underwent microwave thermoablation, one radiofrequency thermoablation and two cryoablation; one child treated with cryoablation also had radiofrequency thermoablation because mass volume increased after the cryoablation procedure. The median reduction of tumor volume was 69.6% (24.0–96.5%). One child treated with microwave thermoablation showed volumetric increase of the mass and underwent surgical removal of the tumor. No major complication was reported.
Conclusion
Percutaneous ablation is technically feasible for expert radiologists and might represent a valid and less invasive treatment for chest wall chondroid hamartoma, avoiding skeletal deformities.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, VSZLJ, ZAGLJ
COMPASS is a fixed target experiment at CERN SPS aimed to study hadron structure and spectroscopy. Hadron identification in the momentum range between 3 and 55 GeV/c is provided by a large gaseous ...Ring Imaging Cherenkov Counter, RICH-1. To cope with the challenges imposed by the new physics program of COMPASS, RICH-1 has been upgraded by replacing four MWPC-based photon detectors with newly developed MPGD-based photon detectors. The architecture of the novel detectors is a hybrid combination of two layers of THGEMs and a Micromegas. The top of the first THGEM is coated with CsI acting as a reflective photo-cathode. The anode is segmented in pads capacitively coupled to the APV-25 based readout. The new hybrid detectors have been commissioned during the 2016 COMPASS data taking and stably operated during the 2017 run. In this paper design, construction, operation and performance aspects of the novel photon detectors for COMPASS RICH-1 are discussed.
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