P. Bene

First-level charged particle trigger for the L3 detector

Abstract A first-level charged particle trigger based on parallel processing and look-up tables has been developed for the L3 detector. It processes analog signals generated by the central tracking detector, a drift chamber with axial wires. The trigger decision is made on the total number of tracks, the number of coplanar pairs of tracks, or on more complicated topologies found in the projection normal to the beam axis. The system is very flexible and can be adjusted to a wide range of background conditions and tracking chamber efficiencies.

High pT trigger electronics for a large orthogonal readout electromagnetic calorimeter

Abstract A trigger system has been designed and built to select events containing high p T electromagnetic showers detected in a large calorimeter with orthogonal readout. The electronics include analog adders with up to 123 inputs, pulse shapers with 20 ns integration time, 100 MHz flash ADCs and ECL loop-up tables. The total number of input channels is 3072 and the trigger decision is made in about 120 ns.

A GEM based TPC with two large 3-GEM Towers

A large size prototype of a TPC with GEM amplification has been successfully built and operated. To obtain an active area larger than the one provided by the largest GEM foil on the market, 2 independent GEM towers have been hosted on a single pad plane minimising the dead space between the towers. This readout structure has been inserted in a test-bed available at CERN, inherited from the HARP-TPC installation at the PS East Hall, made by a cylindrical field-cage of 80 cm diameter and around 150 cm active length, all placed inside a solenoid magnet capable of 0.7 T. This setup is equipped with about 1500 readout channels. The initial choice for relatively large squared pads (8mm) is driven by the need to study the performances in view of a neutrino oscillation experiment, where the track density is low. A systematic study of the performances has been performed as a function of several parameters like the operating voltages of the GEM towers, the magnetic and the drift fields and the gas mixture. Special care has been taken in the study of the gas, with a large range of mixtures including Ar:CF4:iC4H10.

TPG, test results

TPG is the acronym for Time Projection Chamber with GEM amplification, high-granularity hexaboard read-out and FADC electronics. We have constructed a TPG read-out module, called TPG-head, with three GEM foils and a multilayer board, called hexaboard, covered with 710 000 hexagonal pads of 300 mum size. The total active area of this module is a disk of 30 cm diameter. The 710 000 pads are read by three sets of 576 strips dephased by 120 degrees. Each strip is read by a FADC channel with 100 ns sampling time. The module is mounted in a test-bed formed by a cylindrical field cage of 80 cm diameter and 150 cm length inside a solenoidal magnet that operates with a magnetic field up to B=0.7 Tesla. Tests with X-ray sources show an intrinsic spatial resolution of the order of 40 mum. The threshold for transverse momentum measurement of low energy tracks is below 0.1 MeV/c with a magnetic field of 0.07 Tesla. At 0.7 Tesla the intrinsic space point resolution of the chamber is such that the error on the measurement of the transverse momentum is DeltaPtsime0.1 MeV/c in absence of distortions from the drift region

Progress in TPG construction [particle detector]

TPG is the acronym for a 3D imaging gas chamber with GEM amplification, hexaboard read-out and FADC electronics. We have constructed a TPG-head with three GEM foils (30 cm diameter) and a read-out board (30 cm diameter active surface) covered with 710000 hexagonal pads of 300 /spl mu/m size. The aligned pads are connected in parallel to one strip out of three sets of 576 parallel strips (500 /spl mu/m pitch). The three sets of strips run at 120 degrees from each other and at three different depths inside the hexaboard multi-layer structure. Each strip is read by FADC electronics. The TPG-head is under initial test in a small container with a drift volume 33 mm long and of 30 cm diameter. A 150 cm long drift volume inside a 0.7 Tesla solenoidal magnetic field has been prepared by using HARP-TPC instrumentation as a test bed.

Frontend and readout electronics of the MICE Electron Muon Ranger detector

The MICE experiment is being commissioned at RAL to study the feasibility of a Neutrino Factory: muons are cooled by a dedicated system based on radiofrequency while the particle ID is performed by a KLOE-light detector followed by EMR (Electron Muon Ranger), a fully active tracker-calorimeter positioned at the end of the beamline. EMR consists of 48 planes of 59 1.1 m long scintillator bars with a triangular section. The light in each bar is collected by one 1.2 mm WLS fiber and is readout by a single PMT (Philips XP2972) on one side to provide the information on the charge deposit in the plane and a 64 channel multianode PMT (Hamamatsu) on the other one to digitize the trigger output of each single bar. The single PMT is readout by a CAEN V1731 Waveform Digitizer, while the frontend electronics to treat the multianode signals is organized in two near-detector boards: a FEB (FrontEnd Board) and a buffer board. The FEB hosts a dedicated socket for the MAPMT, the frontend ASIC and two control FPGAs (Altera CYCLONE II) while the buffer board stores the data during the spill. The PMT is connected to the FEB through a flexible multilayer kapton cable. The 64 MAPMT signals are pre-amplified, shaped and discriminated by the MAROC-2 (Omega, LAL), a low noise single power rail ASIC with multiplexed analog and parallel digital outputs. The experiment foresees one event every 5 µs during a spill of 1 ms every 1 s. The 64 discriminated signals are sampled with a 400 MHz clock and in presence of the experiment trigger, the above threshold bars numbers are stored together with a timestamp in the buffer board to be sent to the VME DAQ system during the interspill. The communication is based on the TLK1501 Gigabit link: 6 buffer boards are daisy chained for a total of 8 VME control boards. A configuration board completes the DAQ and is responsible of the configuration of the frontend and of the distribution of the trigger and synchronization clock signals. This paper presents the tests of the electronics and its performance both with a small EMR prototype with square bars and in the test system for the mass production of the final modules.