LAPAS: A SiGe Front End Prototype for the Upgraded ATLAS LAr Calorimeter

We have designed and fabricated a very low noise preamplifier and shaper to replace the existing ATLAS Liquid Argon readout for use at the Large Hadron Collider upgrade (sLHC). IBM’s 8WL 130nm SiGe process was chosen for it’s radiation tolerance, low noise bipolar NPN devices, wide voltage rand and potential use in other sLHC detector subsystems. Although the requirements for the final design can not be set at this time, the prototype was designed to accommodate a 16 bit dynamic range. This was accomplished by using a single stage, low noise, wide dynamic range preamp followed by a dual range shaper. The low noise of the preamp is made possible by the low base spreading resistance of the Silicon Germanium NPN bipolar transistors. The relatively high voltage rating of the NPN transistors is exploited to allow a gain of 650V/A in the preamplifier which eases the input voltage noise requirement on the shaper. Each shaper stage is designed as a cascaded differential operational amplifier doublet with a common mode operating point regulated by an internal feedback loop. Measurement of the fabricated circuits indicates their performance is consistent with the desig

High Radiation Resistant DC-DC Converter Regulators for use in Magnetic fields for LHC High Luminosity Silicon Trackers

For more efficient power transport to the electronics embedded inside large colliding beam detectors, we explore the feasibility of supplying higher DC voltage and using local DC-DC conversion to 1.3 V (or lower, depending upon on the lithography of the embedded electronics) using switch mode regulators located very close to the front end electronics. These devices will be exposed to high radiation and high magnetic fields, 10 – 100 Mrads and 2 - 4 Tesla at the SLHC

Linear low power preamplifier for the atlas liquid argon em calorimeter

In a previous paper, it was shown that, for shaping times of the order of the transmission line delay, a remote, external preamplifier could perform as well as one connected directly to a liquid argon calorimeter. Here we describe an improved circuit configuration where, by attributing the functions of low noise and high dynamic range to two different transistors, the linearity can be improved and the noise can be decreased while reducing the power dissipation by a factor of three (to about 40 mW). The gain (i.e., the transresistance) and the input impedance can be chosen independently without changing the power supply voltages and power dissipation

Optically Based Charge Injection System for Ionization Detectors

An optically coupled charge injection system for ionization based radiation detectors which allows a test charge to be injected without the creation of ground loops has been developed. An ionization like signal from an external source is brought into the detector through an optical fiber and injected into the electrodes by means of a photodiode. As an application example, crosstalk measurements on a liquid Argon electromagnetic calorimeter readout electrodes were performed

Monolithic front-end preamplifiers for a broad range of calorimetry applications

The present paper summarizes the salient results of a research and development activity in the area of low noise preamplifiers for different applications in calorimetry. Design target for all circuits considered here are low noise, ability to cope with broad energy ranges and radiation hardness

LAPAS: A SiGe Front End Prototype for the Upgraded ATLAS LAr

We have designed and fabricated a very low noise preamplifier and shaper with a (RC)2 – CR response to replace the existing ATLAS Liquid Argon readout for use at SLHC. IBM’s 8WL 130nm SiGe process was chosen for its radiation tolerance wide voltage range and potential for use in other LHC detector subsystems. The required dynamic range of 15 bits is accomplished by utilization of a single stage, low noise, wide dynamic range preamp connected to a dual range shaper. The low noise of the preamp (~.01nA / √Hz) is achieved by utilizing the process Silicon Germanium bipolar transistors. The relatively high voltage rating of the npn transistors is exploited to allow a gain of 650V/A. With this gain the equivalent input voltage noise requirement on the shaper to about 2.2nV/ √Hz. Each shaper stage is designed as a cascaded differential op amp doublet with a common mode operating point regulated by an internal feedback loop. The shaper outputs are designed to be compatible with the 130nm CMOS ADC being developed in parallel with this effort. Preliminary measurement of the fabricated circuits indicates their performance is consistent with the design specifications

Progress on DC-DC Converters for a Silicon Tracker for the sLHC Upgrade

There is a need for DC-DC converters which can operate in the extremely harsh environment of the sLHC Si Tracker. The environment requires radiation qualification to a total ionizing radiation dose of 50 Mrad and a displacement damage fluence of 5 x 1014 /cm2 of 1 MeV equivalent neutrons. In addition a static magnetic field of 2 Tesla or greater prevents the use of any magnetic components or materials. In February 2007 an Enpirion EN5360 was qualified for the sLHC radiation dosage but the converter has an input voltage limited to a maximum of 5.5V. From a systems point of view this input voltage was not sufficient for the application. Commercial LDMOS FETs have developed using a 0.25 μm process which provided a 12 volt input and were still radiation hard. These results are reported here and in previous papers. Plug in power cards with ×10 voltage ratio are being developed for testing the hybrids with ABCN chips. These plug-in cards have air coils but use commercial chips that are not designed to be radiation hard. This development helps in evaluating system noise and performance. GaN FETs are tested for radiation hardness to ionizing radiation and displacement damage and preliminary results are given

Methodological approach to spatial analysis of agricultural pest dispersal in olive landscapes

The effectiveness of a Geographical Information Systems cost-distance tool for detecting landscape permeability in relation to the movement of pests in olive landscapes was established. The simplification of agricultural systems is linked to an increased incidence of pests on crops. Therefore, it is important to understand the impact of different land uses surrounding olive groves on pests. In this work, we analysed the effect of the structure of the olive landscape on the movement of two main olive pests—the olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae) and the olive moth, Prays oleae (Bernard) (Lepidopetera: Praydidae). We applied linear mixed effects models to analyse the relationship between pest abundance and cost-distance, using different hypotheses to evaluate those land uses that are favourable or unfavourable for the movement of these pests. The results show that this methodology is effective in detecting possible unfavourable land uses with a barrier effect, such as woodland and artificial land uses, and favourable land uses with a corridor effect such as olive groves. Whether other land uses, such as scrubland or riverbanks, act as a barrier or corridor depends on the pest and its life cycle stage. The effect that different land uses have in maintaining low levels of pest populations and ensuring the long-term sustainability of these agricultural systems are discussed. The implications of landscape permeability for the physical structure of the landscape and the dispersal of organisms, and the potential of that landscape to impact the continuous flow of natural processes are also addressed