BSA Flow Software Installation and User's Guide - CSI

7.10 Histograms
Correlation [LDA1] [x²]
1,00
0,90
0,80
0,70
0,60
0,50
0,40
0,30
0,20
0,10
0,00
-0,10
-0,20
0,000 20,000 40,000 60,000 80,000
Time [ms]
Autocorrelation function up to 100 ms
Correlation [LDA1] [x²]
1,00
0,90
0,80
0,70
0,60
0,50
0,40
0,30
0,20
0,10
0,00
-0,10
-0,20
7.10.1 Velocity histogram
0,000 5,000 10,000 15,000
Time [ms]
The same function, zoomed in on the x axis
The time scale depends on the flow, but the shape of the correlation function
typically decays rapidly to near zero and then fluctuates around zero. In the
example above, the correlation function passes through 0 at approx. 4 ms
and again at 10 ms, after which the correlation is low.
τI would be estimated to 4 ms in the above example, so the Dead Time
should be set to 8 ms or more.
Repeat the above steps in different parts of the flow, to find the region with
the largest τI, typically in regions with low velocity.
To ensure statistically independent data in all parts of the flow, the Dead
Time should be set according to the largest τI.
Velocity histograms are calculated from the histogram object according to
the following equations.
Ni
is the number of plotted size classes (bins) and selected by the user
7-106 BSA Flow Software: Reference guide