How to calibrate TOF counters

1. How to calibrate TOF counters Slewing procedure Timing resolution of all region(40cm)

2. Setup of beam line • Type : phase1 • p=3GeV/c TOF3 TOF ref2

3. Types of calibration • Slewing : TDC.vs.ADC ⇒To estimate bias on timing measurement • Calibration 1 : w/ref2 , done • Difference between PMTA-PMTB • ->Ideal timing resolution canceling slewing • Calibration 2 : w/ref2, not yet (tof3 done) • Center,width 5mm : No position dependence • From TOF-T1,TOF-ref2,T1-ref2 plots, we can calculate intrinsic timing resolution of each counter • Slewing : tdctofa vs adctofa , tdctofb vs adctofb

4. Types of calibration2 • Calibration 3 : Calibration of all region(40cm) of the counter • ref2 can’t operate on magnetic field • To compare w/o magnetic field to w/ magnetic field …., calibration of all region • This beam test : w/o spectrometer • We can’t determine the hit position on TOF counter in magnetic field without tracker. • TDC : We have to erase the factor of position. • The solution is TDCave=(tofa+tofb)/2 • Slewing : TDCave vs adctofa , TDCave vs adctofb

5. -26000 tof3ave-t1ave(tdc,ps) This curve is similar to a•sin(x)+bx+c -31000 0.125 0.325 0.125 0.325 1/sqrt(adctof3a) Time Walk • There are two components in these plot

6. tof3ave-t1ave(tdc,ps) 100 0 -100 0.12 0.28 0.14 0.28 Time Walk (after correction) • We used sin curve correction • There remained a small distortion even after time walk corrections (1/sqrt(adctof3a)+1/sqrt(adctof3b))/2

7. Timing Resolution in all region • tof3ave-t1ave σ=83.1ps • σ(t1)=41.8ps ⇒σ（tof3）=71.8ps (all region) tof3ave-t1ave tdc(ps)

8. Timing resolution of all TOF Timing resolution • There are no difference between w/ magnetic field and w/o magnetic field # of TOF

9. Summary • Ideal resolution is estimated from the difference between PMTA - PMTB〜60ps • We calibrate the slewing effect on TOF counters in the magnetic field.〜70ps • No significant degrade on timing resolution in the magnetic field.