ADC data

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ADC data

Given that the center of the paddle is x=0 and +x is to the left and -x is to the right we have the following quantities.

  • From TDC: with L the length of the paddle, t_{{o}} the time of flight of the particle, v_{{o}} the effective speed of light in the paddle t_{{L}} is the internal delay including all cables, PMT transit times ect. and same for t_{{R}}
    1. T_{{L}}=t_{{o}}+{\frac  {L-x}{v_{{o}}}}+t_{{L}}
    2. T_{{R}}=t_{{o}}+{\frac  {L+x}{v_{{o}}}}+t_{{R}}
    3. \Delta T=T_{{R}}-T_{{L}}
    4. \delta =t_{{R}}-t_{{L}}
    5. x={\frac  {1}{2}}(\Delta T-\delta )v_{{o}}
  • From ADC: with E_{{0}} the original energy deposition, d the attenuation length and \epsilon _{{L}} the light transmission through all couplings including the gain of the PMT and attenuation in the cables. L and R refer to left and right.
    1. E_{{L}}=\epsilon _{{L}}E_{{0}}e^{{{\frac  {-(L-x)}{d}}}}
    2. E_{{R}}=\epsilon _{{R}}E_{{0}}e^{{{\frac  {-(L+x)}{d}}}}
    3. x=ln({\frac  {E_{{L}}}{E_{{R}}}}{\frac  {\epsilon _{{R}}}{\epsilon _{{L}}}}){\frac  {d}{2}}

Now we can plot the x information from the TDC against the x information from the ADC:

  • X-pos from TDC vs X-pos from ADC

fitting the slope will result in the attenuation length d and the horizontal shift is the ration of the two epsilons.

And also the Energy vs. the X-Pos of the ADC:

  • E0 vs X-pos from ADC

the position of the minimum ionizing peak can be determined by a projection to the vertical axis. The location of the peak varies from paddle to paddle.

  • E0