Emilio Gatti

SEMICONDUCTOR DRIFT CHAMBER - AN APPLICATION OF A NOVEL CHARGE TRANSPORT SCHEME

The purpose of this paper is to describe a novel charge tranport scheme in semiconductors in which the field responsible for the charge transport is independent of the depletion field. The application of the novel charge transport scheme leads to the following new semiconductor detectors: (1) Semiconductor Draft Chamber; (2) Ultra low capacitance - large semiconductor x-ray spectrometers and photodiodes; and (3) Fully depleted thick CCD. Special attention is paid to the concept of the Semiconductor Draft Chamber as a position sensing detector for high energy charged particles. Position resolution limiting factors are considered, and the values of the resolutions are given.

Study of the Electric Field inside Microchannel Plate Multipliers

Electric field inside high gain microchannel plate multipliers was studied. The calculations were based directly on the solution of the Maxwell equations applied to the microchannel plate (MCP) rather than on the conventional lumped RC model. The results are important to explain the performance of MCPs, i) under a pulsed bias tension and, ii) at high rate conditions. The results were tested experimentally and a new method of MCP operation free from the positive ion feedback was demonstrated.

Performance of silicon drift detectors in a magnetic field

Abstract A study of the properties of silicon drift detectors in a magnetic field was carried out. A silicon drift detector with 41 anodes, providing unambiguous x and y position information, was used for measurements. Studies were done in three principal orientations of the detector relative to the direction of the magnetic field. The magnetic field was varied between 0 and 0.7 T and the drift field between 300 and 600 V/cm. Basic agreement with the theory of electron transport in semiconductors in a magnetic field was found. The transport properties of electrons in a magnetic field can be described by a mobility matrix. The components of the matrix depend on the electron mobility, Hall mobility and on the vector of the magnetic field. The precision of measurement was better than 0.2% for most of the parameters. For the electric field of a silicon drift detector, there is a first-order effect of the magnetic field only in one out of three principal directions. In this direction, the plane of the detector is perpendicular to the magnetic field and electrons drift at an angle α relative to the direction of the drift field. In two other principal directions, which are more important for tracking of the particles with drift detectors, there are no first-order magnetic effects.

A new class of weighting functions: Energy resolution improvement from an input shunt inductor

Abstract A new class of optimum weighting functions is described, yielding optimum noise performances with a shunt inductance in the input circuit. Such an inductance is inherently present when transformer coupling is employed between the detector and the active device at the preamplifier input. The optimum weighting functions turn out to be area-balanced; they yield always less noise then optimum area-balanced functions optimized for input circuits without shunt inductance. The effects of the finite quality factor Q of the inductor are finally dealt with.

Particle Identification by Processing of Signals from Multiple Detectors

It is shown that for particle identification it is convenient to develop instrumentation based on coding the output of the detectors according to the ratio of probabilities that a particular signal is given by the two kinds of particles considered. Particular emphasis has been given to uncorrelated responses of each detector of a set, but the case of correlated responses leads to obvious extensions of the ideas presented. (auth)

Germanium drift detector: A new tomographic device providing information on the chemical properties of a body section☆☆☆

Abstract A system to analyze the chemical properties of a region of tissue located deep inside the human body without having to penetrate the body is proposed. The method is based on a high precision detection of X-rays or γ-rays (photons) from an external source Compton scattered from the tissue under inspection.