The experiment BESIII, running at the accelerator BEPCII in Beijing (P.R.C.), is going to be updated with the replacement of the Inner Drift Chamber with a Cylindrical triple-GEM Inner Tracker ...(CGEM-IT). In the R&D stage, two standalone C++ codes were implemented: GTS (Garfield-based Triple-GEM Simulator), for digitization and tuning of simulated data to the experimental ones, and GRAAL (GEM Reconstruction And Analysis Library), for the reconstruction and analysis of the experimental events collected in testbeams. GTS simulates the triple-GEM response to the particle passage, treating each stage separately: ionization, GEM properties, gas mixture, magnetic field and finally the induction of the signal on the anode. The necessary information was extracted by GARFIELD++ simulations, parametrized and used as input in GTS. This speeds up the simulation, since GTS performs only samplings instead of the full digitization chain. The simulated events were reconstructed with the same procedure used for experimental data and tuning factors were evaluated to obtain a satisfactory match. GRAAL is used in the analysis of the testbeam experimental data. It provides several levels of reconstruction: from the cluster formation, gathering contiguous firing strips, to the spatial position and the signal time reconstruciton. Two algorithms are used: the charge centroid and the micro-TPC, which exploit the charge deposition on the strips and the time information. Also a merging of the two algorithms is available to efficiently weight the two outcomes and obtain the best estimate of the spatial coordinate. Moreover, GRAAL performs tracking and alignment. Both codes are going to be made available also for other MPGDs simulation and reconstruction.
Activity of CERN and LNF groups on large area GEM detectors Alfonsi, M.; Bencivenni, G.; Brock, I. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We report on the activity of CERN and INFN-LNF groups on the development of large area GEM detectors. The two groups work together within the RD51 Collaboration, to aim at the development of ...Micro-pattern Gas detectors technologies. The vast request for large area foils by the GEM community has driven a change in the manufacturing procedure by the TS-DEM-PMT laboratory, needed to overcome the previous size limitation of
450
×
450
mm
2
. Now a single-mask technology is used allowing foils to be made as large as
450
×
2000
mm
2
. The limitation in the short size, due to the definite width of the raw material, can be overcome by splicing more foils together. A
10
×
10
cm
2
GEM detector with the new single-mask foil has been tested with X-rays and the results are shown. Possible future applications for large area GEM are the TOTEM experiment upgrade at CERN, and the KLOE-2 experiment at the Dafne
Φ
-factory in Frascati.
The upgrade of the KLOE detector at DAFNE, the Φ-factory at the Laboratori Nazionali di Frascati, foresees the insertion of an Inner Tracker around the interaction region, composed of four layers ...with diameters from 26cm to 41cm and an active length of 70cm. Each layer is realized as a cylindrical triple-GEM detector, a solution that allows to keep the total material of the Inner Tracker below 2% of a radiation length, which is of utmost importance to limit the multiple scattering of low-momentum tracks and to minimize dead spaces, thus maximizing the detector's active area. The peculiar read-out pattern with X and V strips provides a spatial resolution of about 200μm and 400μm for azimuthal and longitudinal coordinates, respectively.
After 2 years, the construction of the Inner Tracker has been completed and the detector is ready to be inserted in the KLOE apparatus for a next data-taking run. The details of the manufacturing procedure as well as the results of validation tests are reported.
A cylindrical GEM detector with analog readout is under development for the upgrade of the Inner Tracker of the BESIII experiment at IHEP (Beijing). The new detector will match the requirements for ...momentum resolution (σpt/pt~0.5% at 1GeV) and radial resolution (σxy~120μm) of the existing drift chamber and will improve significantly the spatial resolution along the beam direction (σz~150μm) with very small material budget (less than 1.5% of X0). With respect to the state of the art the following innovations will be deployed: a lighter mechanical structure based on Rohacell, a new XV anode readout plane with jagged strip layout to reduce the parasitic capacitance, and the use of the analogue readout inside a high intensity magnetic field to have good spatial resolution without increasing the number of channels.
GASTONE64 (Gem Amplifier Shaper Tracking ON Events) is a novel 64-channel mixed analog-digital ASIC developed to readout the cylindrical GEM inner tracking detector of the KLOE-2 apparatus at the ...e+e−DAΦNE collider. It has been designed in the CMOS 0.35μm technology and each analog channel is made of preamplifier, shaper and discriminator. The expected input charge ranges between few fC up to 40fC, the charge sensitivity is 16mV/fC while the equivalent input noise charge (ENC) is 800e−+40e−/pF. The discriminated signals are read-out using a 100MBit/s LVDS serial data link. The power consumption is about 6mW/channel.
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