Studies of dynamics of electron clouds in STAR silicon drift detectors

The dynamics of electrons generated in silicon drift detectors was studied using an IR LED. Electrons were generated at different drift distances. In this way, the evolution of the cloud as a function of drift time was measur ed. Two methods were used to measure the cloud size. The method of cumulati ve functions was used to extract the electron cloud profiles. Another metho d obtains the cloud width from measurements of the charge collected on a si ngle anode as a function of coordinate of the light spot. The evolution of the electron cloud width with drift time is compared with theoretical calcu lations. Experimental results agreed with theoretical expectations. (C) 200 0 Elsevier Science B.V. All rights reserved.