pmt calibration

PMT CalibrationR.Sawada7/Jan/2007

Time calibrationMethod was talked at the previous meeting.

The problems which was shown before were because I used PMTs in shadow from LED.

3

Distance [cm]

Distance [cm]

Distance [cm]

Distance [cm]

Tim

e [

nse

c]

Tim

e [

nse

c]

Tim

e [

nse

c]

Tim

e [

nse

c]

4

Time offset and DRS channel

According to Matthis, there is similar dependence in DC data.

Chip:0 Chip:1

5

Time offset and DRS board

Crate:4 Crate:5

Slot:2

There is small correlation. This was not expected because time difference due to electronics is

corrected by using clock analysis.

This can be variation of cable length in liquid xenon. (due to temperature co-efficient)

6

Time distribution before calibration

Distance [cm]

Tim

e [

nse

c]

Crate:4,Chip0

Crate:4,Chip1Crate:5,Chip0

Crate:5,Chip1

Crate:5,Slot12

7

Time distribution before calibration

Distance [cm]

Tim

e [

nse

c]

8

Result

Time offset [nsec] Time offset uncertainty [nsec]

One entry is one PMT

This result is available in analysis and simulation.

This number is uncertainty of measurement of one LED.Average is 1/sqrt(2)-1/sqrt(4) better.

Q.E.

Analyzed by using a task developed by Pisa group, with my small modification.

10

PMT Nphe fit (Same as LP)

Gaussian when mean of nphe > 20

Poisson x Gaussian when mean of nphe < 20Sigma of Gaussian is obtained from pedestal events

11

gas alpha

Noise

Outer wall alpha

Wire alpha + Top/Bottom wall alpha

Qsum2 > 2500

12

liquid alpha

13

Data:MC

One graph is one PMT. One point is one alpha.

Gas data (1/10 statistics, full statistics analysis is still running)

14

Data:MC

One graph is one PMT. One point is one alpha.

Liquid data (full statistics)

15

Result

Q.E. liquid

Full statistics of gas is running.

Q.E

. in

liqu

idQ.E. in LP or Pisa

16

Summary

• Time calibration was done in 200-500 psec uncertainty. Result is available

• Speed of light observed on Inner/Outer and lateral is slightly different.

• Q.E. estimation using liquid data was done. Gas will be finished soon.

• Result will be available in 1-2 days.

• Uncertainty is currently fitting error of “data v.s. MC.” It looks rather small. I will check the code again.

• I used MC result produced by Pisa group. I will check it with my MC. (It must be same, because we are using the same MC software.)

• PMT calibration was almost finished. I will proceed to absorption length estimation, Q.E. estimation dependence on geometry (check of MC), reconstruction and detector calibration.

÷ 1/sqrt(2) ~ 1/sqrt(4)