Operating Basics
Rev. 007 Date 2010-01-13
CyFlow
®
space Instrument Operating Manual
15/26
PMT High Voltage, Gain, and Log Amplification
Controls
Gain
Note
Gain
and
lin/log
amplification mode
cannot be adjusted
after the acquisition.
Note
Be sure not to use
too high gain values.
Increasing the gain
values too much can
cause a decrease of
amplification or a
loss of signals due
to saturation effects.
Note
The gain value does
not necessarily be
equal to the PMT
high
voltage
nor
does
it
be
proportional to the
amplification.
Log
Typical
effect
of
change
DNA distribution of
bull sperms with X-
and Y-chromosomes.
Gain = 445
.
DNA distribution of
bull sperms with X-
and Y-chromosomes.
Gain = 476.5
.
EAT
cells,
linear
amplification
EAT cells, log 3 (3
decade) amplification
Adjustment
By means of the gain, the signal amplification can be
individually adjusted in a wide range for each
parameter. For the used photomultiplier tubes
(PMTs) by changing the gain value, the PMT's high
voltage is adjusted.
The gain value of a parameter can be selected by
clicking into the corresponding gain value field in the
instrument settings box (see Fig. 4). By using the
Right (Left) buttons gain values are increased
(decreased).
In case linear amplification is used, peaks are
expanded to the right (compressed to the left) when
increasing (decreasing) the gain (see example on
the left).
In case logarithmic amplification is used, peaks are
moved
to
the
right
(left)
when
increasing
(decreasing) the gain.
Use the gain to move the peaks of interest to a
suited position in the histograms.
Start with low gain values around 250. When
increasing the gain, make sure the most intense
signals still appear in the histogram and are not
moved out of scale.
Increasing
(decreasing)
the
gain
by
50
approximately causes an increase (decrease) of
amplification by a factor of two. Gain values between
250 and 600 are a good start for adjustment.
For each parameter, you can choose between linear
or
logarithmic
amplification.
In
logarithmic
amplification mode, the signal range can be set to 3
(log3) or 4 decades (log4), corresponding to a range
of 1...1000 or 0.1...1000. Generally, a logarithmic
amplification is advisable if particles with a broad
range of intensities above 1:10 are to be analysed.
Click the little arrow, select one of the following
lin
(linear)
log3
(logarithmic, 3 decade range)
log4
(logarithmic, 4 decade range)
and click it.
