A cylindrical GEM detector is under development, to serve as an upgraded inner tracker at the BESIII spectrometer. It will consist of three layers of cylindrically-shaped triple GEMs surrounding the ...interaction point. The experiment is taking data at the e+e− collider BEPCII in Beijing (China) and the GEM tracker will be installed in 2018. Tests on the performances of triple GEMs in strong magnetic field have been run by means of the muon beam available in the H4 line of SPS (CERN) with both planar chambers and the first cylindrical prototype. Efficiencies and resolutions have been evaluated using different gains, gas mixtures, with and without magnetic field. The obtained efficiency is 97–98% on single coordinate view, in many operational arrangements. The spatial resolution for planar GEMs has been evaluated with two different algorithms for the position determination: the charge centroid and the micro time projection chamber (μ-TPC) methods. The two modes are complementary and are able to cope with the asymmetry of the electron avalanche when running in magnetic field, and with non-orthogonal incident tracks. With the charge centroid, a resolution lower than 100μm has been reached without magnetic field and lower than 200μm with a magnetic field up to 1 T. The μ-TPC mode showed to be able to improve those results. In the first beam test with the cylindrical prototype, the detector had a very good stability under different voltage configurations and particle intensities. The resolution evaluation is in progress.
A cylindrical GEM Inner Tracker for the BESIII experiment Amoroso, A.; Baldini, R.; Bertani, M. ...
Il nuovo cimento della Società italiana di fisica. Sezione C, Geophysics and space physics,
2016, Letnik:
39, Številka:
1
Journal Article
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We are developing a cylindrical GEM detector with analog readout to upgrade the Inner Tracker of the BESIII experiment at IHEP (Beijing). The new detector will match the requirements for momentum ...resolution (sigma(pt)/pt similar to 0.5% at 1GeV) and radial resolution (sigma(xy) similar to 100 mu m) of the existing drift chamber and will improve significantly the spatial resolution along the beam direction (sigma(z) similar to 150 mu m) with very small material budget (about 1% of X-0). A beam test has been performed at CERN in order to measure the performance of a BESIII GEM prototype in a magnetic field up to 1 tesla. An overview of the project and the preliminary results of the test will be presented in the talk. The project has been recognised as a Significant Research Project within the Executive Programme for Scientific and Technological Cooperation between Italy and PRC for the years 2013-2015, and more recently has been selected as one of the project funded by the European Commission within the call H2020-MSCA-RISE-2014.
The NA48/2 experiment at CERN collected two data samples with minimum bias trigger conditions in 2003 and 2004. A measurement of the rate and dynamic properties of the rare decay K plus or minus ...arrow right pi plus or minus gamma gamma K plus or minus arrow right pi plus or minus gamma gamma from these data sets based on 149 decay candidates with an estimated background of 15.5 plus or minus 0.715.5 plus or minus 0.7 events is reported. The model-independent branching ratio in the kinematic range z=(m gamma gamma /mK)2>0.2z=(m gamma gamma /mK)2>0.2 is measured to be BMI(z>0.2)=(0.877 plus or minus 0.089)10-6BMI(z>0.2)=(0.877 plus or minus 0.089)10-6, and the branching ratio in the full kinematic range assuming a particular Chiral Perturbation Theory description to be B(K pi gamma gamma )=(0.910 plus or minus 0.075)10-6B(K pi gamma gamma )=(0.910 plus or minus 0.075)10-6.
Gas detectors are one of the pillars of the research in fundamental physics. Since several years, a new concept of detectors, called Micro Pattern Gas Detectors (MPGD), allows to overcome many of the ...problems of other types of commonly used detectors, like drift chambers and microstrip detectors, reducing the discharge rate and increasing the radiation tolerance. Among these, one of the most commonly used is the Gas Electron Multiplier (GEM). GEMs have become an important reality for fundamental physics detectors. Commonly deployed as fast timing detectors and triggers, due to their fast response, high rate capability and high radiation hardness, they can also be used as trackers. The readout scheme is one of the most important features in tracking technology. The center of gravity technique allows to overcome the limit of the digital pads, whose spatial resolution is constrained by the pitch dimension. The presence of a high external magnetic field can distort the electronic cloud and affect the spatial resolution. The micro-TPC (μ-TPC) reconstruction method allows to reconstruct the three dimensional particle position as in a traditional Time Projection Chamber, but within a drift gap of a few millimeters. This method brings these detectors into a new perspective for what concerns the spatial resolution in strong magnetic field. In this report, the basis of this new technique will be shown and it will be compared to the traditional center of gravity. The results of a series of test beam performed with 10 × 10 cm 2 planar prototypes in magnetic field will also be presented. This is one of the first implementations of this technique for GEM detectors in magnetic field and allows to reach unprecedented performance for gas detectors, up to a limit of 120 \mu~{\mathrm {m}} at 1 T, one of the world's best results for MPGDs in strong magnetic field. The μ-TPC reconstruction has been recently tested at very high rates in a test beam at the MAMI facility; preliminary results of the test will be presented.
From the 2002 data taking with a neutral kaon beam extracted from the CERN-SPS, the NA48/1 experiment observed 97 I 0 a IL + mu - I12 A= mu candidates with a background contamination of 30.8 +/- 4.2 ...events. From this sample, the BR (I 0 a IL + mu - I12 A= mu ) is measured to be (2.17 +/- 0.32 stat +/- 0.17 syst) X 10 - 6 .
A new inner tracker based on a cylindrical gas electron-multiplier detector is under development to replace the current inner drift chamber of the BES III spectrometer. The BES III experiment is ...carried out at the BEPC II e
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collider in Beijing at center-of-mass energies in the tau-charm region with a design luminosity of 1.0
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. The new inner tracker consists of three cylindrical layers of triple GEM surrounding the interaction point, covering 93% of solid angle. To fulfill physics requirements, a spatial resolution of 130 μm must be achieved. Both planar and cylindrical prototypes have been built and tested. A custom ASIC using UMC 110-nm technology has been designed to provide charge and time measurements—the first prototype is in testing. Notable and innovative aspects of the new inner tracker and the performance of the detector prototypes and readout ASIC are reported here.
The PANDA spectrometer will be built at the FAIR facility at Darmstadt (Germany) to perform accurate tests of the strong interaction through pp and pA annihilation studies. The charged particle ...tracking at PANDA will be done using both solid state and gaseous detectors. Among the latter, two straw tube detector systems will be built 1, The cylindrical, central straw tube tracker features a high spatial and momentum resolution for a wide range of particle momenta from about 8 GeV/c down to a few 100 MeV/c, together with particle identification in the momentum region below about 1 GeV/c by measuring the specific energy-loss, A new technique, based on self-supporting straw double layers with intrinsic wire tension developed for the COSY-TOF straw tracker 2, has been adopted for the PANDA trackers. The development of the readout electronics for the straw tubes is ongoing. Prototypes have been produced and used to instrument straw tube modules that have been tested with cosmic rays and proton beams. Design issues of the PANDA straw tubes, together with the results of the prototype tests are presented.
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