Appendix A: Technical Overview 137
Threshold
The threshold is the level at which the system starts to measure signal pulses. A
threshold is defined for a specific detector signal. The system continuously
samples the digitized signal data and calculates pulse area, height, and width for
all channels based on the time interval during which the threshold is exceeded.
Thresholds can also be set for more than one parameter, and pulse measures are
based on either of the following:
• intervals during which ALL signals exceed their threshold value
• intervals during which ANY signal exceeds its threshold value
Laser Controls
Controls in the Laser tab of the Instrument window are used to set the (laser)
delay, area scaling, and window extension values.
These parameters are set by BD Biosciences service personnel when the
BD LSR II flow cytometer is installed, and they rarely need to be changed.
Record and save these parameter values for future reference.
If needed, see Appendix G for instructions on optimizing laser delay settings. Do
not otherwise change the settings in the Laser tab unless instructed to do so by
BD Biosciences. Changing the settings will affect your data.
LSR2.book Page 137 Tuesday, April 25, 2006 3:34 PM
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