C. De La Taille

Radiation qualification of the front-end electronics for the readout of the ATLAS liquid argon calorimeters

The ATLAS detector has been built to study the reactions produced by the Large Hadron Collider (LHC). ATLAS includes a system of liquid argon calorimeters for energy measurements. The electronics for amplifying, shaping, sampling, pipelining, and digitizing the calorimeter signals is implemented on a set of front-end electronic boards. The front-end boards are installed in crates mounted between the calorimeters, where they will be subjected to significant levels of radiation during LHC operation. As a result, all components used on the front-end boards had to be subjected to an extensive set of radiation qualification tests. This paper describes radiation-tolerant designs, radiation testing, and radiation qualification of the front-end readout system for the ATLAS liquid argon calorimeters.

Experimental results on cable-coupled preamplifiers (ØT)

Abstract Warm preamplifiers connected to a detector through 8 m cables have been evaluated in the frame of the RD3 accordion LAr calorimeter. The noise performance on workbench and on testbeam are presented and discussed. For fast calorimetry and for a particular range of detector capacitance, the warm preamplifiers are competitive with cold ones.

Automated system for equivalent noise charge measurements from 10 ns to 10 μs

Abstract Noise measurements versus filter time constant constitute a very powerful method to investigate series, parallel and 1/f noise contributions in front end electronics. Usually performed with a set of filters and a multichannel analyser, they are tedious and often limited to values greater than 100 ns. We describe here a very low noise bipolar filter whose time constant can be selected via GPIB bus from 10ns to 10 μs in 10 steps. The data are transferred from a digital scope to a computer which generates a baseline histogram and determines the overall gain. The ENC is then calculated for each time constant and a fit to the results determines the various noise parameters.

Construction, assembly and tests of the ATLAS electromagnetic end-cap calorimeters

The construction and the assembly of the two end-caps of the ATLAS liquid argon electromagnetic calorimeter as well as their test and qualification programs are described. The work described here started at the beginning of 2001 and lasted for approximately three years. The results of the qualification tests performed before installation in the LHC ATLAS pit are given. The detectors are now installed in the ATLAS cavern, full of liquid argon and being commissioned. The complete detectors coverage is powered with high voltage and readout.

First test of a power-pulsed electronics system on a GRPC detector in a 3-Tesla magnetic field

An important technological step towards the realization of an ultra-granular hadronic calorimeter to be used in the future International Linear Collider (ILC) experiments has been made. A 33X50 cm2 GRPC detector equipped with a power-pulsed electronics board offering a 1cm2 lateral segmentation was successfully tested in a 3-Tesla magnet operating at the H2 beam line of the CERN SPS. An important reduction of power consumption with no deterioration of the detector performance is obtained when the power-pulsing mode is applied. This important result shows that ultra-granular calorimeters for ILC experiments are not only an attractive but also a realistic option.

The UFFO (Ultra Fast Flash Observatory) Pathfinder: Science and Mission

Hundreds of gamma-ray burst (GRB) optical light curves have been measured since the discovery of opti- cal afterglows. However, even after nearly 7 years of operation of the Swift Observatory, only a handful of measure- ments have been made soon (within a minute) after the gamma ray signal. This lack of early observations fails to ad- dress burst physics at short time scales associated with prompt emissions and progenitors. Because of this lack of sub- minute data, the characteristics of the rise phase of optical light curve of short-hard type GRB and rapid-rising GRB, which may account for ~30% of all GRB, remain practically unknown. We have developed methods for reaching sub- minute and sub-second timescales in a small spacecraft observatory. Rather than slewing the entire spacecraft to aim the optical instrument at the GRB position, we use rapidly moving mirror to redirect our optical beam. As a first step, we employ motorized slewing mirror telescope (SMT), which can point to the event within 1s, in the UFFO Pathfind- er GRB Telescope onboard the Lomonosov satellite to be launched in Nov. 2011. UFFOs sub-minute measurements of the optical emission of dozens of GRB each year will result in a more rigorous test of current internal shock mod- els, probe the extremes of bulk Lorentz factors, provide the first early and detailed measurements of fast-rise GRB optical light curves, and help verify the prospect of GRB as a new standard candle. We will describe the science and the mission of the current UFFO Pathfinder project, and our plan of a full-scale UFFO-100 as the next step.

Subnano time to digital converter implemented in PARISROC for PMm2 R&D program

PARISROC is a complete read out chip, in a BiCMOS SiGe 0.35μm technology from AustriaMicroSystems, for photomultipliers array. It allows triggerless acquisition for next generation neutrino experiments and is part of a R&D program called PMm2. The ASIC integrates 16 independent and auto triggered channels with variable gain and provides charge and time measurement by a 10-bit Wilkinson ADC and a 24-bit counter. The time measurement is made of 2 complementary systems: a 24-bit gray counter (coarse time) with a step of 100 ns, and a double ramp TDC (fine time) with a 10-bit resolution and a measured precision of 425 ps RMS. Only the analog TDC will be explained in this paper by detailing the double ramp TDC architecture, the special cares and the first fine time measurements. One of the fine time TDC characteristics is the fact that the double ramp generator is common to all channels.

The readout electronic of EUSO-Balloon experiment

The EUSO-Balloon experiment is a pathfinder for the satellite mission JEM-EUSO whose goal will be to observe Extensive Air Showers produced in the atmosphere by the passage can detect fluorescent UV photons released by the EAS thanks to Multi-anode photomultipliers (MAPMT) arranged in 6 × 6 matrices inside Photo Detector Modules (PDM). A set of lenses is used to focus the photons on the PDM which can be compared to a UV camera taking pictures every 2.5 μs period (GTU: Gate Time Unit). The experiment consists in launching a balloon, at an altitude of 40 km, equipped with complete PDM and Data Processing systems. This project, supported by CNES and constructed by the JEM-EUSO collaboration, is meant to prove that the technology of such an instrument is possible and that the performance is satisfying, raising the Technical Readiness Level (TRL) of JEM-EUSO. Moreover, complex trigger algorithms will be assessed and the main back ground (night glow plus star light) will be studied. A complex readout electronic chain has been designed for the EUSO-Balloon project. It contains two elements: the 9 EC units and the 6 EC-ASIC boards. The EC unit includes four 64-channel Multi-Anode Photomultipliers and a set of pcbs used to supply the 14 different high voltages needed by the MAPMTs and to read out the analog anode signals. These signals are transmitted to the EC-ASIC boards which contain 6 SPACIROC ASICs each. During the year 2012, prototypes of each board were produced and tested successfully, leading to the production of the flight model PCBs in 2013.

Characteristics of a prototype matrix of Silicon PhotoMultipliers (SiPM)

This work reports on the electrical (static and dynamic) as well as on the optical characteristics of a prototype matrix of Silicon Photomultipliers (SiPM). The prototype matrix consists of 4 ? 4 SiPMs on the same substrat fabricated at FBK-irst (Trento, Italy). Each SiPM of the matrix has an area of 1 ? 1mm2 and it is composed of 625 microcells connected in parallel. Each microcell of the SiPM is a GM-APD (n+/p junction on P+ substrate) with an area of 40 ? 40 ?m2 connected in series with its integrated polysilicon quenching resistance. The static characteristics as breakdown voltage, quenching resistance, post-breakdown dark current as well as the dynamic characteristics as gain and dark count rate have been analysed. The photon detection efficiency as a function of wavelength and operation voltage has been also estimated.