APD and Electronics Testing

Leon Mualem

Univ. of Minnesota

October 2, 2003

From Concept…

To Reality

Test Cooling Circuitry, Components, and Capacity

Actual board, powered and

cooled to –25C

Higher Value Resistors

Filter on voltage Regulator

Bypassing on Vref and Vcc

Fix Some Issues on Rev. A

Initial Noise msmt at FNAL with new board•MASDA noise best case expected 330 e-

•15 Channels with reduced noise after fixes.•4 @ 390e-

•6 @ 420e-

•3 @ 450e-

•2 @ 480e-

•Reminder: This is an interim solution, a properly matched front end should get ~250e- according to Tom Zimmerman

Channel Noise (RMS e-)

1 390

2 390

3 390

4 420

5 390

6 420

7 420

8 420

9 420

10 450

11 420

12 450

13 480

14 450

15 480

18 M

eg O

hms

9 M

eg O

hms

Noise testing parameters

• Maximum bandwidth setting

• 21mV/fC gain 300e-/mV

• 1mV=1ADC count

• Integration Time (SAFT-SBEF) = 2s

Noise Levels on Bare Board

W/10pF

W/18M W/9M

Fit to noise showing Tails…there aren’t any

Breakdown Voltage vs. TempVbr I=15uA

375

380

385

390

395

400

405

410

415

-25 -15 -5 5 15 25 35

Temperature (C)

Bre

ak

do

wn

vo

lta

ge

Current vs. Voltage by temp.

0.1

1

10

100

1000

10000

300 320 340 360 380 400

Voltage

Cu

rren

t (n

A)

25

20

15

10

5

0

-5

-10

-15

-19

Noise vs. Voltage by temp.

100

1000

10000

100000

300 320 340 360 380 400

Voltage

RM

S n

ois

e (

ele

ctr

on

s) 25

20151050-5-10-15-19

Issues …

• Cooler plate must not be left floating – Electrically connect to

board

Future Plans

• Measure noise with powered APD

• Measure noise with APD vs. Temperature • Gain measurement with Temperature

• Measure noise as a function of Tint

• Measure LED generated signal

• Measure signal from scintillator with trigger

• …