Dec 22 2006 LED monitoring system

Beam-test LED monitor

Ｊａｎ /23/200 ７K.Toyama, H.Ono

Niigata University, MSU-IIT GLD-CAL

Dec 22 2006 LED monitoring system

Setup of Y-strip

45mm

90mm

10mm90mm

FFC

MPPC

FPCB

24.7mm

FPCB

24.7mm

Dec 22 2006 LED monitoring system

Setup of X-strip

90mm

90mmMPPC

FFC

FPCBFPCB

10mm

Dec 22 2006 LED monitoring system

FFC connector board

FFC connector board

FFC connector board

Y-Strip

X-StripTungsten 3.5mm

FFC

FFC

Dec 22 2006 LED monitoring system

ECAL assembly

• LED flush through the white PET sheet.• Need to make a small hole on the black sheet ．

Black sheetWhite PET

Mega strip

LED with FFC

Dec 22 2006 LED monitoring system

Bench test setup

ＰＭＴ

ＡＤＣ

３ｃｍ

2mm thickness scintillator

LED light pass through the white PET sheet.

WLSF

White PETLED

Dec 22 2006 LED monitoring system

Bias voltage vs light yield (ADC)

0

50

100

150

200

250

300

350

400

2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

LED Volt V Plus 20ns（ ）

AD

C C

ount

Mean

NoWhitePet

In WhitePet

Dec 22 2006 LED monitoring system

We can see light yield through sheet

• 2/3 Light yield reduce by white PET sheet. • We can see linearity of bias voltage vs light yield t

hrough white PET sheet

• ADC spec : 0.25pc/count

Dec 22 2006 LED monitoring system

Now Doing

• Measure how many LEDs can drive by TTL one signal.

Dec 22 2006 LED monitoring system

Problem

• We planned that thirteen LEDs connect in parallel by NIM-TTL one signal.

• When we use many LED in parallel, the bias from NIM-TTL module become low.

TTL In 5V,25ns

Measure by probe

Dec 22 2006 LED monitoring system

Oscilloscope picture from probe 1

No LED One LED

X axis scale 25nsY axis scale 500mV

Probe makes 1/10V

Dec 22 2006 LED monitoring system

Oscilloscope picture from probe 2

three LEDs four LEDs

X axis scale 25nsY axis scale 500mV

Probe makes 1/10V

Dec 22 2006 LED monitoring system

Three LEDs connected in parallel

• When we connect three LEDs in parallel, light yield slightly decreased.

We didn’t use FFC and MPPC in this time.We used general cable and PMT.

LED yield

Event frequency

Dec 22 2006 LED monitoring system

Four LEDs connected in parallel

• When we connect four LEDs ,we cannot see light yield peak.

• Pedestal and light yield are almost equal.

Event frequency

LED yield

Dec 22 2006 LED monitoring system

Summery and Next

• We should consider how to drive LEDs,– TTL pulse width should be a little wider?– Reduce LEDs on one board, one TTL drive pulse?

• Test by MPPC.

• We already receive all the parts expect for LEDs.• It takes only a few days to assemble them.