PowerPoint Presentation - CUE Web Summary for halldweb.jlab.org
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Some Remarks on Calibration of
BCAL.
After recent
I made some tests and
communications with
I didn’t measure any
the BCAL team, seems
deterioration of the
that we have to use a 2
signal.
wire cable, 5-10 cm,
from the board so as
Do we need an
only the LED is
extension with the
attached on the light
trapezoidal L-Gs?
guide.
Pending issues.
Position and support of the board.
Piggy-back on the Amplifier board.
Any other suggestion from the engineers.
Protocol:
Any 2-wire protocol.
Serial Xon/Xoff as requested.
Intensity and Dynamic Range.
Intensity can be Controlled by:
Dc Voltage Adjustment.
A piece of Film Filter between LED and the Light
Guide.
Range:
Using an LED with Longer Wavelength, Below the
Absorbing Band of the Fiber (not enough).
Lower the Voltage of Near Side to a Safe Value, while
Pulsing the Far Side.
Possible magic.
Test with trapezoidal light guide.
• There is enough space between the L-Gs for the LED
board.
• We positioned the board 3 cm from the photocathode.
• We used the demo, (baby) calorimeter.
• We measured the pulse high at the near and the far side.
• The ratio near / far was 8 to 10.
• Variation because of positioning.
Pictures of Light guide with LED
board.
Pictures of pulsesI
Near side
Far side
Pictures of pulses II
Near side
Far side
Other Approaches.
Return to fibers.
Not as elegant as it sounds.
• Splitters Cost ~ 2000 $ for 16 channels
• Inflexible
• Need Groove on Light Guide.