1. CERN Summer Student Presentation Session
Attenuation Length Measurements for the LHCb Scintillating Fibre Tracker
CERN Summer Student Presentation Session
Tuesday 6th August, 2019
Mustafa Ozkaynak

2. What is a Scintillating Fibre?
First layer of cladding, Plexiglass, n≈1.49
Second layer of cladding, fluorinated polymer, n≈1.42
Polystytene core n≈1.59
Image above taken from: Christian Joram, ‘Scintillating Fibres – Tracking Particles With (a little) Light The new Fibre Tracker for LHCb’ Available at:
06/08/2019
Mustafa Ozkaynak

3. The setup used
The fibre is doped with Wavelength shifters that convert the UV light into visible blue light, that is read out by the photodiode.
Image taken from: Christian Joram, ‘Scintillating Fibres – Tracking Particles With (a little) Light The new Fibre Tracker for LHCb’ Available at:
06/08/2019
Mustafa Ozkaynak

4. A real life look at the setup
06/08/2019
Mustafa Ozkaynak

5. Potential Sources of Errors due to Equipment
Warming up of the:
Ammeter
Power supply
The LEDs
How much fluctuations on intensity is there at a particular position?
How much does intensity vary due to not being able to place the rail at the exact same position?
Insignificant
Insignificant
06/08/2019
Mustafa Ozkaynak

6. Sources of Error in the equipment
LED+Power Supply
Error due to variation in positioning of the rail
06/08/2019
Mustafa Ozkaynak

7. Damaging the Fibres Before radiating the same position
After radiating the same position for 3 hours
06/08/2019
Mustafa Ozkaynak

8. Repeatability of measurements
Are there differences due to operators?
What is the random variance due to the equipment?
What is the effect of setting up the measurement?
06/08/2019
Mustafa Ozkaynak

9. Different operators -setup reset- -setup untouched- Operator Mustafa
Operator Jan
-setup untouched-
-setup reset-
06/08/2019
Mustafa Ozkaynak

10. Results
Using 80 unique data points that are picked randomly for samples sizes ranging between 3-80, standard error is calculated in order to find how many repetitions are necessary in the future
σx̅ = σ 𝑁
The equation corresponding to the fit that was used to extrapolate the data.
σx̅= (𝐴𝑒 −𝐵𝑥 +𝐶 𝑒 −𝐷𝑥 )
06/08/2019
Mustafa Ozkaynak