TDC test beam data analysisTDC test beam data analysisB. AngelucciB. Angelucci

Università di Pisa & INFN PisaUniversità di Pisa & INFN Pisa

01/04/200901/04/2009• Introduction

• Hit distribution & noisy channels

• Missed hits in algo A & B

• PMT time resolution

Layout of 400PMT RICH Prototype test

TELL1

TDCB

TDCB

TDCB

TDCB GBE

PC &

STORAGE

NIN

O

CA

RD

S

Laser Ext trigger

~400 PMs

~25 cables

1 Gb channel

• Test with 400 PMs

• Laser and defocusing lens, ~30PMT fire each laser pulse

• Variable frequency (~Hz - ~MHz )

• Only one GBE output channel (max 1GBit/s)

• ~2% channels masked

Setup

channel channel

ch91

ch76

10 kHz 100 kHz

Noisy channels

Evidence of a difference between 10kHz and 100 kHz runs, for some channels (33, 42, 63, 69, 76, 91, 111, 137, 139, 155,

159, 169, 177, 179, 222, 258, 396, 417, 424)

Noisy channels

window of absolute time ~20s

Events all channels

channel 91

channel 90

Noisy channels

Events all channels

channel 91

channel 90

100us

Noise independent from events’ rate: more relevant in 10kHz runs

Missed hits in Algo A

10 kHz 100 kHz

Number of words per event

Number of words per event

• It is expected only an even number of words (leading & trailing edge)

• From data: uniform distribution (odd/even) in 10kHz runs, even predominance in 100kHz runs

Missed hits in Algo A

100 kHzDifference between number of trailing and leading per event for 100kHz runs

•The peak at dTL=0 indicates the predominance of an even number of words

• An odd |dTL| means an odd number of words

• dTL≠0 shows the presence of unpaired leading or trailing

30 leading 26 trailing

3 trailing from next event

Missed hits in Algo A

120 clk edges readout window

adjustable offset

Algo A scheme

Example of event in which dTL= -4

• The leak of trailing words is partially recovered from next event

ALGO A 10kHz

9% 1%

90%

good events

leading recovered

leading not justif ied

ALGO A 10kHz

15%

49%

36% good events

trailing recovered

trailing not justif ied

ALGO A 100kHz

32%

7%61%

good events

leading recovered

leading not justif ied

ALGO A 100kHz

43%

44%

13%

good events

trailing recovered

trailing not justif ied

Missed hits in Algo A

• Good events means no unpaired leading or trailing

• Not justified means not totally recovered

• Under analysis: debugging using pattern generator in progress

Missed hits in Algo B

10 kHz 100 kHz

Number of words per event

Number of words per event

trigger

Readout window

data flux in LB

Wait trigger on data

Algo B scheme

Missed hits in Algo B

• Good events means no unpaired leading or trailing

• Not justified means not totally recovered

ALGO B 10kHz

13%

72%

15%good events

leading recovered

leading not justif ied

ALGO B 10kHz

6% 5%

89%

good events

trailing recovered

trailing not justif ied

ALGO B 100kHz

40%

50%

10%

good events

leading recovered

leading not justif ied

ALGO B 100kHz

22%

8%

70%

good events

trailing recovered

trailing not justif ied

• Under analysis: debugging using pattern generator in progress

Differences Trailing time – Leading time

<tT – tL> for each channel σ[tT – tL] for each channel

threshold

tL tT

The difference tT-tL is rather proportional to signal’s amplitude

Resolution (ref ch14)

Offset <∆t(chx-ch14)>

for each channel

Raw resolution

for each channel

Offset and raw resolution: analizing the time difference ∆t(chx-ch14) for each event with both chx and ch14

Slewing correction for time resolution

∆t(ch31-ch14) vs (tT – tL)ch31 for each event

mean of each binx content

fit function

(2nd degree)

Raw & corrected resolutions

∆t(ch31-ch14) raw ∆t(ch31-ch14) corrected

σraw ~ 540 ps σcorr ~ 200 ps

A detailed analysis of test beam data has been presented

Comparison between 10kHz and 100kHz runs points out the presence of ~5% noisy channels (due to front-end electronics)

Most of the events show no more than one lost hit over ~ 60 at the edges of the readout window. Probable bug in the firmware under investigation

Single photo-electron time resolution of PMTs in fair agreement with measurements with CAEN TDCs (<250ps)

Next step: systematic measurements using fast and high resolution pattern generator

Conclusions