SCT week 2003 Dec

Module Testing with Nd:YAG Laser
K. Hara (U Tsukuba)
SCT Japan Group
Contents:Laser testing system
Mean response vs. time
Consistency with DAQ calibration results
new dead channels
new low gain channels
Gain spread
Cross-talkSummary

YAG Laser Test System

VME SCTdaq system

ZstageLaser
headLaser power supply
Module tobe tested

IV meters

XYstage

Intensity
reduction&focusing

System parameters① Measurement (incl. setting-up) should complete in 1 hr per side
Response be measured along
two lines at both ends
Strip breaks
incomplete wirebonds…
Line-2(768 strips/side)

Line-1

Record Vth curves of bothneighbors as well

Information on cross-talks
Vth curve: 50 events at each of 10 points: 100, 130, [220, 360,20]
if VT50 < 220[150, 360,20]
If VT50 > 360[220, 480,40]

System parameters① to complete in 1 hr … （trigger rate dependence））[60,450,10] 100evts (0,0)
1000Time (sec)/Vth_scan

Vt50 (mV)

500
400
300
200
100

100

1010
10100

1000

10000

10Trig Freq. (Hz)Response (=laser output) decreases above
１ｋHz frequency

1001000
10000
Trig Freq. (Hz)DAQ speed will not improve above 2 kHz

Trigger rate＝１kHzFor each strip
Vth curve （50 ev@10 Vth）：1.1sstage movement: 0.2s

meas. along 2 lines + movem’t＝40 min
pedestal, XY-Z calib ＜15 minSystem parameters② Height adjustment

VT50 (mV)

350
300

Height adjusted

250

Height not adjusted

200

Z precision of 15 µm is goodenough in view of response
variation (see plot in next page)150
10050Line2Line10

Module warp ~ 50 µm
Position precision in module box
Channel Number~ 100÷200 µm
Minimum effort is required to calibrate the height⇒ measure height at three points along the scan line; interpolate with a parabola
769

897

1025

1153

1281

1409

System parameters③ XY precision achievable
Use 2 sensor fiducials(no computer-aided pattern recognition, so far)
Thermal deformation should be minimized; wait long enough*(we have a Cu block at 10degC under the module)
Deviation: 5 µm at this side
*10-20 µm if not careful
350

25 µm
Spot: 2 µm□

Mean PH (vt50) (mV)

300
250
200
focus(ch-)
focus (ch+)+15um (ch-)+15um (ch+)-15um( ch-)-15um (ch+)

15010050⇒absolute gain can vary by ±7%,010including uncertainty in height control

15202530

3540

Distance (um) from ch-45

50

55

Line-2
Line-1
vt50 vs strip#
Stage control and fitting results display

DAQ panel

Online Monitor

Threshold curve
Hit distribution

500

1st module on Aug 8.

400
300
200
100

25-35 modules/week
JPS meeting

Number of Tested Modules

Number of Tested Modules

08/4

9/1

9/29

10/27

Date (2003)

11/24

12/22

Mean Response vs. Time
Mean laser response （ｍV)

350
300
250

±7%

200
150
100

Link0 line1
Link0 line2
Link1 line1
Link1 line2

interrupted by other study using laser

500050100150200250measurement)
Module Number (order of250

mean=265mV=5.15fC

Number of Lines

200

Short-term variation explained by ±7%
Long-term drift of ~10%/month may exist
We adjust the laser intensity to keep 4-6 fC

300

1501004.28fC

6.02fC

500150200

250300mean Laser Response (mV)

350

400

Total number of irregular channels#irregulars consistent with DAQ#irregulars "inconsistent" with DAQ
DEADhigh gain
DEADlow gain
DEADOKOK
high gain
OKlow gainOKdead
unbonded
OKhigh noise(lowG)
partbonded
dead
partbonded
low gainhigh noise
Not judged

346
125110548
21024
61211112

Number of Modules

Consistency with DAQ calibration
200total: 286 modules"high noise": not counted

150
100
50
002

4

6810 12 14 >15

Number of Irregular Strips/Module

These are not inconsistent:
Various criteria being applied in
DAQ to judge the channel isdead… (need a check)next slides
ENC=801 (unbonded is correct)

Bonded, but low gain (DAQ gain=46)⇒small ENC⇒partbondedOf 6 “new” deadLine2Line1

Link1350

5 are identified as Al break250

4 are known from HPK probing
1 was not known by HPK (see photo)200

VT50-ped

300

150
100
50
AL open

0769

897

1025

1153

1281

1409

-50
Channel Number

Guess: the Al bridge
evaporated in the process ofprobing when the next
neighbor strip was at 120V

1 un-identified:Such a new break may
exist under the hybridOf 24 “low Gain” channel
Response from DAQ gain, offset,
beforeTrim
300

DAQ gain given after Trim
70

Entry=24

DAQ gain (mV/fC)

6025050Laser<DAQ:16200

401503020Laser~DAQ: 810100

mean050
000.2
0.4
0.6
0.8
Laser Response (normalized)

100.2
0.4
0.60.8Laser Response (normalized)

Laser response normalized by of neiboring channels
consistent with DAQ, though
the channel was judged OKChannels with large negative
offsets: ー(41÷77) mV

1

0.12
Rms/Mean (gain normalized)

Gain Spread
0.12
Link0
Link1

0.08

0.1
0.08
0.06
0.04
0.02
000.0650100
150200Module (meas. Order)

250300100
DAQ normalized

0.04
0.02
000.02

0.04
0.06
0.08
0.1
DAQ normalized rms/mean

0.12

Num ber of Links

Laser rms/mean

0.1

Link0
Link1

806040200Spread corrected with DAQ gain is
not much improved except for modules
with large spread…

0.01

0.02

0.03

0.04 0.05
RMS/mean

0.06

0.07

(rms spread)/mean~2.9%<4% for 92.8% of Links

Link1Gain Spread (Module 431)
400
350
0.12

VT50-ped

0.1

250

3500.06

1503000.04

1002500.02500000.02

0.04
0.06
0.08
0.1
DAQ normalized rms/mean

0.12-50769

897

Small gain of M08 chip is nicely
corrected by DAQ calibration on Nov 7
Q: why M08 is not judged low gain?
A: M08 was just normal when tested
on June 6 … what happened!?

Laser gain (mV)

2000.08

Nov
7
Line2
Line1

200
150100
1025

1153

50

Channel Number

0350
0-50300
Laser gain (mV)

Laser rms/mean

300

Link0
Link1

1281

20140940

60

DAQ gain (mV/fC)

250
200
150
100

June 6500-5002040

DAQ gain (mV/fC)

60

Gain Spread (Module 40)
Link03000.12
Link0
Link1

250
2000.08VT50-ped

Laser rms/mean

0.1

0.06
0.04

150
1000.02

Line2Line150000.02

0.04
0.06
0.080.1
DAQ normalized rms/mean

0.1200128

256384512640768

4060

80-50

Laser response looks just normal,
but S02 DAQ gain is too high…

250200Laser gain (mV)

80
70
60
50
4030

Z39993-W04-9

Channel Number

300

150
10050

20010001

129

257

385513641

20-50
DAQ gain (mV/fC)

Line2Line1Others : cross talkLink1400
350

cross-talk is distinctive:
1/2 response in successive channels

VT50-ped

300
250
200
150
100
500

DAQ judged these as DEAD

-50

769

897

1025

1153
Channel Number

Module 24

Module 478

1281

1409

SummaryLaser testing is in progress:
DAQ results are verified mostly
Some findings
6 “new” dead ⇒ 5 are identified Al breaks (4 since HPK)
24 “new” low gain ⇒8 are low since DAQ,
others with large negative offset
one chip may have calibration line 40% offCount

Current Problem: Mustard reports “no header”/ “no data”
probably, data are lost during module60
to VME transmission (?)
50
this limits the gain uniformity precision 40
30
2010

reset Mustard when “this” curve is obtained 080
re-route the cables if this continues...

120160200

240 280
Vth (mV)

320

360400