5 The threshold of each pixel in the Pixel Detector, measured in electrons (e), must be 6 properly set in order to optimize position resolution and particle detection efficiency. 7 This note details the threshold tuning performed for the full pixel detector over a 48 month period in the fall of 2008. At the end of this period, 94% of the detector was 9 tuned to a measured mean threshold value of 3939 e, which is offset from the true 10 threshold value by∼60 e, with an RMS of 37 e. The remaining 6% of the detector was 11 not measurable due to software or hardware problems. 12 1)Iowa State University, Iowa City, Iowa 52242, USA 2)Universitat Bonn, 53113 Bonn, Germany 3)SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA 4)Oklahoma State University, Stillwater, OK 74078, USA 5)California Institute of Technology, Pasadena, CA 91125, USA 6)Columbia University, New York, NY 10027, USA