Caen ELS BEST, User Manual, Page: 36 / 47

BEST Local GUI BEST User’s Manual
36
where I
TOP
, I
RIGHT,
I
BOTTOM
and I
LEFT
are the acquired input channels currents values.
Referring to
Figure 25
, I
TOP
, I
RIGHT,
I
BOTTOM
and I
LEFT
are assigned to Ch1, Ch2, Ch3
and Ch4 respectively, K
X
and K
Y
are respectively “X scaling” and “Y scaling”
parameters and Offset
X
and Offset
Y
are respectively “X offset” and “Y offset”
parameters.
It is recommended to either scan the detector in the beam or move the beam in a
controlled way over the detector in order to correctly match the
TetrAMM
channels to the detector.
K
x
, K
y
are the scaling factor for X and Y dimension, respectively. They should be
determined experimentally by moving the beam over the detector (or vice-versa) by a
known amount and comparing this given amount with the un-calibrated response of
the phBPM. Then, they must be store in the X scaling and Y scaling input windows
shown in
Figure 25 .
In some cases, a second phBPM is installed on the same beamline, either intrinsically
with a different geometry (e.g.: diamond-based phBPM) or with the phBPM system
rotated CW by 45° in order not to get shadowed by the first unit upstream. Then, the
computation needs to be modified. The equations used in a 45° rotated phBPM system
are the following:
( ) ( )
( ) ( )
Referring to
Figure 25
, I
TOP-RIGHT
, I
BOTTOM-RIGHT,
I
BOTTOM-LEFT
and I
TOP-LEFT
are
assigned to Ch1, Ch2, Ch3 and Ch4 respectively, K
X
and K
Y
are respectively “X
scaling” and “Y scaling” parameters and Offset
X
and Offset
Y
are respectively “X
offset” and “Y offset” parameters.
4.3.2 Bias Voltage - optional
The Bias Voltage settings allow to set the bias voltage possibly required by the
detecting system. The field “HV Status” shows whether the optional embedded bias
voltage module in the
TetrAMM
is switched ON or OFF. The bias voltage
module can be switched on by clicking the “Enable HV” button. Then the desired bias
output voltage value can be set by entering its value in “Bias voltage” field and by
pressing the “Set HV” button.
The fields “Voltage readout” and “Current readout” report the real, measured voltage
and current values at the output of the bias voltage module.