Operational experience, improvements, and performance of the CDF Run II silicon vertex detector

TL;DR

This paper reviews a decade of operational experience with the CDF Run II silicon vertex detector, highlighting challenges, improvements, and performance metrics crucial for heavy flavor physics at Fermilab.

Contribution

It provides a detailed account of the operational challenges, maintenance strategies, and performance monitoring methods for the silicon detector over an extended period beyond initial expectations.

Findings

Detectors operated effectively despite higher radiation doses than planned.

Performance metrics such as vertex resolution and tagging efficiency were maintained.

Operational improvements extended the detector's useful lifespan significantly.

Abstract

The Collider Detector at Fermilab (CDF) pursues a broad physics program at Fermilab's Tevatron collider. Between Run II commissioning in early 2001 and the end of operations in September 2011, the Tevatron delivered 12 fb-1 of integrated luminosity of p-pbar collisions at sqrt(s)=1.96 TeV. Many physics analyses undertaken by CDF require heavy flavor tagging with large charged particle tracking acceptance. To realize these goals, in 2001 CDF installed eight layers of silicon microstrip detectors around its interaction region. These detectors were designed for 2--5 years of operation, radiation doses up to 2 Mrad (0.02 Gy), and were expected to be replaced in 2004. The sensors were not replaced, and the Tevatron run was extended for several years beyond its design, exposing the sensors and electronics to much higher radiation doses than anticipated. In this paper we describe the operational challenges encountered over the past 10 years of running the CDF silicon detectors, the preventive measures undertaken, and the improvements made along the way to ensure their optimal performance for collecting high quality physics data. In addition, we describe the quantities and methods used to monitor radiation damage in the sensors for optimal performance and summarize the detector performance quantities important to CDF's physics program, including vertex resolution, heavy flavor tagging, and silicon vertex trigger performance.