1 MPPC Timing Resolution Akito Kobayashi Shinshu University Table of contents ・ Timing Resolution ・ Set up ・ data treatment ・ result(1) ・ result(2) ・ result(3) ・ Summary and plan

2 What is Timing Resolution? Timing Resolution is timing fluctuation that MPPC signal reach to Threshold voltage. Timing Resolution is measured by TDC Threshold Voltage Timing resolution 700mV 200ns

3 Set Up Start pulse : Clock generator Stop pulse : MPPC signal MPPC type : 100,400,1600,2500pixels in 1mm*1mm MPPC bias : dV = 1.0V 100ns ×64 hamamatsu Threshold:100mV 5kHz λ~450nm V=8.5~18.5V Width = 15ns 25ps/ch

4 Set up photoMPPC MPPC LED For the plastic package MPPC sensor positions is the same for two kinds of packages. For the ceramic package 5cm 5cm

5 Treatment of data Use gauss fitting for TDC distribution, and get fluctuation parameter as sigma in fitting function. This parameter[ch] is converted to time[ps] by using TDC resolution 25ps/ch For example, sigma = →1.514ch ×25ps/ch = 38ps Set the fitting range as minimum sigma

6 plot(1) Y axis : Timing Resolution [ps] X axis : Supply voltage for LED Driver[V] （ V LED ） Example ： V LED = 15V 、 sigma = 2.0ch Plot the data as X = 15 Y = 2.0*25 =50

7 result(1) If the number of pixels is large, timing resolution would be a little bit. （ =sigma would be large ） If amount of light is large, timing resolution would be better. (=sigma would be small)

8 plot(2) Y axis : timing resolution [ps] X axis : number of photon detected by MPPC(=N fired ) [p.e.] Example : V LED = 15V N fired = 4000p.e., sigma = 2.0ch ※ ADC peak = 2000ch, 1p.e.peak = 0.5ch ⇒ N fired = 2000/0.5 = 4000p.e.

9 result(2) Comparing the data of 4MPPC is difficult, because number of photon of these MPPC have big difference.

10 plot(3) Y axis : Timing Resolution[ps] X axis : Number of photon deveded by the number of pixels [p.e. / N pix ] ex : N fired = 4000p.e., sigma = 20ch at 1600pixel MPPC Plot the data as X = 4000 / 1600 = 2.5 Y = 2.0*25 = 50

11 result(3) Data points of 400pixel, 1600pixel, 2500pixel aligned except 100pixel. There is the relation without effect of number of pixels. Have to study this relation.

12 Summary Measured the timing resolution of 4 MPPCs and compared these data by using 3 kinds of plot. The results show two trends. →If the number of pixels is large, timing resolution would be a little bit. （ =sigma is large ） If amount of light is large, timing resolution would be better. (=sigma is small) X value is N fired / N pix →data points of 3 MPPC aligned. 100pixel was also linear, but didn’t align with other MPPCs.

13 Plan Study the effect of saturation for 100pixel. Study the effect of MPPC bias voltage. (dV)

14 Thank you for your attention