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LYCCA ToF scintillators [message #18548] Wed, 07 October 2015 10:09 Go to next message
a_boso is currently offline  a_boso
Messages: 16
Registered: July 2014
occasional visitor
From: *pd.infn.it
Dear all,

I am trying to use ToF Start scintillator to get position informations.

Looking at the code I saw the possibility to use a "x_shear" parameter, which permits to introduce a "y-dependent" offset on the x position.
Which is the physical meaning of this quantity? How can I optimize it?

More generally, do you know how can I optimize the position information of the Lycca ToF scintillators? Which resolution should I expect?

Last question:

Could you please share the positions of the PMTs you have in the Lycca/Lycca/Membrane.par file for the ToFStart and ToFStop scintillators?
I have more than one set, and I don't know which one is the right one.

Thank you very much!

Alberto
Re: LYCCA ToF scintillators [message #19423 is a reply to message #18548] Fri, 12 August 2016 15:35 Go to previous messageGo to next message
Michael Reese is currently offline  Michael Reese
Messages: 9
Registered: August 2016
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From: *gsi.de
Hi,

By just plotting the x vs. y position as it comes from the ToF-scintillator, you will get a pattern of squares. The pattern comes from the gaps between the LYCCA modules.
If everything would be perfect, the lines in the pattern should be perpendicular. In practice they might look a bit sheard.
The "x_shear" and "y_shear" parameters are there to correct for that.

I hope the following schematic drawing makes it clear.

index.php?t=getfile&id=8739&private=0

In addition, the pattern might be shifted in x and y direction, and rotated. There are other parameters forseen to correct these errors.

Regards,
Michael
Re: LYCCA ToF scintillators [message #19424 is a reply to message #19423] Fri, 12 August 2016 16:26 Go to previous messageGo to next message
SMilne is currently offline  SMilne
Messages: 30
Registered: July 2014
Location: York
continuous participant
From: 5.151.46*
Hi Michael,

Could I please ask how this calibration would likewise be performed for the ToF start scintillator, i.e. where no such lines are present.

Thanks,
Scott
Re: LYCCA ToF scintillators [message #19425 is a reply to message #19424] Fri, 12 August 2016 17:20 Go to previous messageGo to next message
Michael Reese is currently offline  Michael Reese
Messages: 9
Registered: August 2016
occasional visitor
From: *gsi.de
Hi,

You need to create a pattern artificially. One possible way to do this is to draw a rectangular gate around the projected TPC-position, i.e. the "true" position, and make a gated ToF x:y plot with the condition that the "true" position is inside that gate. You'll see the distorted shape of whatever gate you have drawn.

Reminder of how to create such a rectangular gate in the config file (I didn't test that piece of code... there might be typos inside):
processor ToF_Start/TPC/gate UTILS.ConditionWindow2D
  x  <-  Frs/S4tracking.xs[5]
  y  <-  Frs/S4tracking.ys[5]
  display x:y | xy_window
end

processor ToF_Start/distored UTILS.PairWithCondition
  first  <- Lycca/ToFStart/Membrane.x
  second <- Lycca/ToFStart/Membrane.y
  condition <- ToF_Start/TPC/gate.inside
  display tested_first:tested_second 
end


If you want to have multiple gates, you could do something like this for 6 gates:
for $i in [0:5]
  processor ToF_Start/TPC/gate_$i UTILS.ConditionWindow2D
    x  <-  Frs/S4tracking.xs[5]
    y  <-  Frs/S4tracking.ys[5]
    display x:y | xy_window
  end
end

processor ToF_Start/distored UTILS.PairWithCondition
  first  <- Lycca/ToFStart/Membrane.x
  second <- Lycca/ToFStart/Membrane.y
  for $i in [0:5]
    condition <- ToF_Start/TPC/gate_$i.inside
  end
  display tested_first:tested_second 
end


Then you could draw gates in the shape of horizontal lines, three gates in the shape of vertical lines, and together they'll make a grid-like shape.

[Updated on: Fri, 12 August 2016 17:24]

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Re: LYCCA ToF scintillators [message #19426 is a reply to message #19425] Fri, 12 August 2016 17:27 Go to previous messageGo to next message
Michael Reese is currently offline  Michael Reese
Messages: 9
Registered: August 2016
occasional visitor
From: *gsi.de
I should mention, that all these corrections should be done after the calibration of the PMTs is already optimized.
Calibrated PMTs will already give a good x:y pattern. The offset, rotation, and shear corrections are for fine-tuning the result.
Re: LYCCA ToF scintillators [message #19427 is a reply to message #19426] Fri, 12 August 2016 17:32 Go to previous message
SMilne is currently offline  SMilne
Messages: 30
Registered: July 2014
Location: York
continuous participant
From: 5.151.46*
Hi Michael,

Thanks for your response. I will give it a try and see what I get.

Yeah, the other calibrations are already completed, this was just to try and optimise them a little more.

Thanks,
Scott
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