CDF Run II silicon vertex detector annealing study

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Vol. 743; pp. 68 - 78
• Main Authors: Stancari, M., Knoepfel, K., Behari, S., Christian, D., Di Ruzza, B., Jindariani, S., Junk, T.R., Mattson, M., Mitra, A., Mondragon, M.N., Sukhanov, A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier B.V 11.04.2014; Elsevier
• Subjects: Annealing; Bias; CDF; CDF detector operations; Depletion; Detector operations; Detectors; Electric potential; INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; Mathematical models; Silicon; Vertex detector; Voltage; Annealing; Silicon; CDF; Vertex detector; Detector operations
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2014.01.017

Between Run II commissioning in early 2001 and the end of operations in September 2011, the Tevatron collider delivered 12fb−1 of pp¯ collisions at s=1.96TeV to the Collider Detector at Fermilab (CDF). During that time, the CDF silicon vertex detector was subject to radiation doses of up to 12Mrad. After the end of operations, the silicon detector was annealed for 24days at 18°C. In this paper, we present a measurement of the change in the bias currents for a subset of sensors during the annealing period. We also introduce a novel method for monitoring the depletion voltage throughout the annealing period. The observed bias current evolution can be characterized by a falling exponential term with time constant τI=17.88±0.36(stat.)±0.25(syst.) days. We observe an average decrease of (27±3)% in the depletion voltage, whose evolution can similarly be described by an exponential time constant of τV=6.21±0.21days. These results are consistent with the Hamburg model within the measurement uncertainties.