W. Richter

Performance of the ALEPH Time Projection Chamber

Abstract The performance of the ALEPH Time Projection Chamber (TPC) has been studied using data taken during the LEP running periods in 1989 and 1990. After correction of residual distortions and optimisation of coordinate reconstruction algorithms, single coordinate resolutions of 173 μm in the azimuthal and 740 μm in the longitudinal direction are achieved. This results in a momentum resolution for the TPC of Δp / p 2 = 1.2 × 10 −3 (GeV/ c ) −1 . In combination with the ALEPH Inner Tracking Chamber (ITC), a total momentum resolution of Δp / p 2 = 0.8 × 10 −3 (GeV/ c ) −1 is obtained. With respect to particle identification, the detector achieves a resolution of 4.4% for the measurement of the ionisation energy loss.

Performance of a liquid argon electromagnetic calorimeter with an “accordion” geometry

Abstract The first prototype of a lead—liquid-argon e.m. calorimeter with accordion-shaped absorber and electrode plates has been built and tested with electron and muon beams at the CERN SPS. This novel geometry combines good granularity with high readout speed and minimal dead space. For a response peaking time of 140 ns, an energy resolution of 10%/ E[ GeV ] and a space resolution of 4.4 mm/ E[ GeV ] with a 2.7 cm cell size have been achieved for electrons. The position accuracy for muons is better than 2 mm.

Performance of a liquid argon Accordion calorimeter with fast readout

Abstract A prototype lead-liquid-argon electromagnetic calorimeter with parallel plates and Accordion geometry has been equipped with high speed readout electronics and tested with electron and muon beams at the CERN SPS. For a response peaking time of about 35 ns, fast enough for operation at the future hadron colliders, the energy resolution for electrons is 9.6%/√E[GeV] with a local constant term of 0.3% and a noise contribution of 0.33 E[ GeV ] . The spatial accuracy achieved with a detector granularity of 2.7 cm is 3.7 mm E[ GeV ] and the angular resolution 12 mrad at 60 GeV.

Performance of a liquid argon preshower detector integrated with an Accordion calorimeter

Abstract A prototype liquid argon preshower detector with a strip granularity of 2.5 mm has been tested at the CERN SPS in front of a liquid argon Accordion calorimeter. For charged tracks a signal-to-noise ratio of 9.4 and a space resolution of 340 μm were measured; the rejection power against overlapping photons produced in the decay of 50 GeV π 0 s is larger than 3; the precision on

Performance of a liquid argon electromagnetic calorimeter with a cylindrical accordion geometry

Abstract A prototype of a lead liquid argon accordion calorimeter with two types of cylindrical geometry was constructed and equipped with high speed readout electronics. The energy resolution for electrons is 10%/√E (GeV) with a local constant term of 0.65%. The resolutions obtained for position and angular measurements are given.

A shaped solenoid for muon spectroscopy at high-energy hadron colliders

Abstract The conceptual design of a large solenoid is described. It is optimized for precision muon spectroscopy for experiments at future hadron colliders, providing polar-angle coverage from 6(10) to (170)174 degrees. The design uses mass-produced industrial components with the aim of reducing construction costs.

GAS SYSTEM FOR ALEPH TPC

Abstract Operation of the time projection chamber of the ALEPH experiment at LEP requires a high-purity argon/methane gas mixture supplied to the detector under stable conditions to ensure minimum signal attenuation throughout the 43 m 3 detector volume (max. 2.2 m drift length) and maintain near-constant electron drift velocity in the gas over extended periods of time. Design considerations for a gas system to fulfil these conditions are presented and details given of the construction, operational aspects and of the achieved performance.

Electronic chain for the readout of a fast liquid argon prototype calorimeter

Summary form only given. A research and development program is being conducted in view of realizing an electromagnetic and hadronic calorimeter for the Large Hadron Collider (LHC). The authors report on tests on fast electronics, coupled to an electromagnetic prototype calorimeter built with an accordion structure. Three different types of preamplifiers have been used. In two (Si and GaAs hybrids), the preamplifier is operated in liquid argon. In the third one, a common based (Si JFET or GaAs) transistor is in the liquid, the charge preamplifier being outside the cryostat, after about 6 m of 50- Omega cable. The shaping amplifier uses RC-CR filtering. The response to a short current pulse peaks after about 20 ns. When the system is connected to the calorimeter, the liquid argon signals peak, as expected, after 30 ns. Noise, linearity, and cross-talk between channels were investigated. First results from an exposure of the calorimeter to electrons of energy 30 to 175 GeV were obtained.<<ETX>>

The read-out processors of the Aleph time projection chamber and their performance

The Aleph detector is installed on the LEP electron-positron storage ring. Its central tracking detector, a time projection chamber (TPC), has about 50000 channels of sampling electronics. The digitized signals are processed by 72 double-width Fastbus modules built around an MC 68020 processor. The time projection processor is described, and the solutions, both hardware and software, adopted to run and manage such a complex system in a Fastbus-VAX environment are discussed. Practical experience with the system is reported. >

Application of Remote Handling in the CPS Tunnel

Two hands and a crane are controlled from the ring centre via 300 m long cables and observed with three closed-loop TV chains. This installation, with more than 30 remote controlled functions, is capable of performing work along 40 m of the PS ring tunnel. The second hand, which has been developed at CERN, executes the more delicate work such as disconnecting ordinary water and electrical cornnectors of different types. One test operation was the removal of a vacuum tank with a septum magnet of the ejection system. Althougn this equipment was not designed for remote handling, only the connection to the power cable could not be removed from a distance. All the other work - vacuum connections to chamber and. pumps, electrical and water connections, lifting out onto a chariot - was done with no one present in the ring tunnel.