B. Hallgren

The Embedded Local Monitor Board (ELMB) in the LHC Front-end I/O Control System

The Embedded Local Monitor Board is a plug-on board to be used in LHC detectors for a range of different front-end control and monitoring tasks. It is based on the CAN serial bus system and is radiation tolerant and can be used in magnetic fields. The main features of the ELMB are described and results of several radiation tests are presented.

Performance of an electromagnetic liquid krypton calorimeter based on a ribbon electrode tower structure

The NA48 collaboration is preparing a new experiment at CERN aiming to study CP violation in the K0-K0 system with an accuracy of 2 × 10−4 in the parameter Re(ϵ′/ϵ). Decays in two π0s will be recorded by a quasi-homogeneous liquid krypton calorimeter. A liquid krypton calorimeter has been chosen to combine good energy, position and time resolution with precise charge calibration and long-term stability. The prototype calorimeter incorporating the final design of the electrode read-out structure is presented in this paper. An energy resolution of ≃3.5%√E with a constant term smaller than 0.5% has been obtained. The time resolution was found to be better than 300 ps above 15 GeV.

The trigger for K0→π0π0 decays of the NA48 experiment at CERN

The trigger used for the collection of the samples of K0→π0π0 decays in the NA48 experiment at CERN uses a novel pipeline design in order to satisfy the demanding specifications of a high rate kaon beam. The trigger algorithms, architecture and performance are described.

PERFORMANCE OF AN ELECTROMAGNETIC LIQUID KRYPTON CALORIMETER

Abstract A prototype electromagnetic calorimeter containing 180 litres of liquid krypton has been tested in electron and muon beams at the CERN SPS. The main features of this detector are its active shower medium, a granularity of 2 cm with tower readout, and the use of the initial current readout technique with an effective shaping time of about 60 ns. An energy resolution for electrons of 4.1% √E[ GeV ] with a constant term of 0.4% and a noise contribution of 50 MeV has been achieved. The calorimeter has a spatial resolution of 4.5 mm √E[ GeV ] with a constant term of 0.3 mm and a time resolution of about 0.5 ns for energies larger than 10 GeV.

High rate large dynamic range analog circuitry and digitizers for fast calorimetry

This paper describes the issues encountered in the design of a large dynamic range digitizer for calorimetry. A gain switching technology developed for the liquid krypton calorimeter of the NA48 CP-violation experiment at CERN is described in detail. 14 bit dynamic range and better than 300 ps time resolution were achieved in beam tests with an 8 channel prototype. A mixed analog/digital ASIC has been developed. A 13,500 channel system is being produced which will be put into operation in 1996.

The NA48 LKr calorimeter digitizer electronics chain

Abstract The 13xa0500 channels of the NA48 liquid-krypton electromagnetic calorimeter readout electronics were put into operation in 1997. The digitizer electronics employs a new gain switching technique that expands the dynamic range of a standard 10-bit ADC to 14 bits at 40xa0MHz sampling rate employing a custom-developed integrated circuit (KRYPTON). The KRYPTON has been fabricated in 1.2xa0μm BiCMOS technology and was successfully developed together with industry on a short timescale. The performance and the experience from the first year of the operation of the liquid-krypton calorimeter electronics will also be briefly discussed.

The NA48 liquid krypton prototype calorimeter

Abstract The NA48 experiment for a precision measurement of the CP violation parameter ϵ′ ϵ in K 0 → 2 π decays will require a fast electromagnetic calorimeter with excellent energy and time resolution. A quasi homogeneous calorimeter using liquid krypton and a fast readout with 40 MHz FADCs is proposed. A prototype with 400 kg of liquid krypton was built and tested in an electron beam. Results for the energy, space and time resolution of this prototype are given.

A 40 MHz-pipelined trigger for K0→2π0 decays for the CERN NA48 experiment

A first level trigger system based on a 40 MHz digital pipeline has been developed for the CERN NA48 [l] experiment, aiming at measuring CP violation in KO -+ 2n decays. The outputs of the 13340 cells of the 10 m3 liquid krypton calorimeter are summed into 64 X and 64 Y projection strips and continuously digitised with 40 MHz FADCs. This information is used to reconstruct at each clock cycle and for the two calorimeter projections, the number of clusters, the impact time of each of them (with a precision of about 3 ns), their total energy and the first and second moments of the energy distribution. Based on the quantities listed above, a programmable look-up table system subsequently computes online the longitudinal position of the kaon decay vertex and performs an event selection. The system is described.

A 40 MHz pipelined trigger for K/sup 0//spl rarr/2/spl pi//sup 0/ decays for the CERN NA48 experiment

A first level trigger system based on a 40 MHz digital pipeline has been developed for the CERN NA48 experiment, aiming at measuring CP violation in K/sup 0//spl rarr/2/spl pi/ decays. The outputs of the 13340 cells of the 10 m/sup 3/ liquid krypton calorimeter are summed into 64 X and 64 Y projection strips and continuously digitised with 40 MHz FADCs. This information is used to reconstruct at each clock cycle and for the two calorimeter projections, the number of clusters, the impact time of each of them (with a precision of about 3 ns), their total energy and the first and second moments of the energy distribution. Based on the quantities listed above, a programmable look-up table system subsequently computes online the longitudinal position of the kaon decay vertex and performs an event selection. The system is described.

Development of fluorocarbon evaporative cooling recirculators and controls for the ATLAS inner silicon tracker

We report on the development of evaporative fluorocarbon cooling recirculators and their control systems for the ATLAS inner silicon tracker. We have developed a prototype circulator using a dry, hermetic compressor with C/sub 3/F/sup 8/ refrigerant, and have prototyped the remote-control analog pneumatic links for the regulation of coolant mass flows and operating temperatures that will be necessary in the magnetic field and radiation environment around ATLAS. Temperature, pressure and flow measurement and control use 150+ channels of standard ATLAS LMB (Local Monitor Board) DAQ and DACs on a multi-drop CAN network administered through a BridgeVIEW user interface. A hardwired thermal interlock system has been developed to cut power to individual silicon modules should their temperatures exceed safe values. Highly satisfactory performance of the circulator under steady state, partial-load and transient conditions was seen, with proportional fluid flow tuned to varying circuit power. Future developments, including a 6 kW demonstrator with /spl sim/25 cooling circuits, are outlined.