1Jim Grahl, U. Minnesota

ECALECAL

CMS Week ECAL Electronics Meeting, 16 Mar 2004

ECAL Data Links

Preliminary Results of GOH Irradiation

CMS Week

ECAL Electronics Meeting

16 Mar 2004

2Jim Grahl, U. Minnesota

ECALECAL

CMS Week ECAL Electronics Meeting, 16 Mar 2004

Irradiation Test Setup

Ten GOH were irradiated in 60 MeV proton beam at PSI, 27-29 Feb.

PC running LabVIEW

control program

GIII Tx GOH eval board

GIII Rx

I2C controller

data, clock, I2C

“Sen

der”

car

dclock

GO

H

GO

H

“Sandwich” GOH(clock, I2C only)

GO

H

GO

H

BERT GOH (data, clock, I2C)

data

data

beam area

control room

beam

Rx eval board

deser eval

board

~30 m

data

• One BERT GOH to observe any data errors.• Nine “sandwich” GOH to observe evolution of eye diagram vs. dose and also have some statistics in case of GOL or laser failure.

Mothertest card

scope

3Jim Grahl, U. Minnesota

ECALECAL

CMS Week ECAL Electronics Meeting, 16 Mar 2004

Some photos

In the control room Serious cabling

Closeup of the GOH stack Setup in the beam area

4Jim Grahl, U. Minnesota

ECALECAL

CMS Week ECAL Electronics Meeting, 16 Mar 2004

Beam conditions

• The BERT GOH was exposed to an integrated dose of 8 * 1013 p/cm2 over 25 hours. (Beam intensity measured by PSI.)

• Beam was steady except for two incidents that crashed the beam monitor.

• “Sandwich” GOH were progressively shielded according to their position in the stack.

• Beam was well centered and aligned on the GOH stack (see later photo).

5Jim Grahl, U. Minnesota

ECALECAL

CMS Week ECAL Electronics Meeting, 16 Mar 2004

Data-taking

• For the BERT GOH, we measured bit error rate continuously.

• For the sandwich GOH, we recorded eye diagrams and measured eye opening every ~1013 p/cm2, at three bias settings. (9 x 9 x 3 = 243 measurements, by hand!)

• GOH 4, at 4 * 1013 p/cm2:

Bias current = 17mA Bias current = 13mA Bias current = 9 mA

6Jim Grahl, U. Minnesota

ECALECAL

CMS Week ECAL Electronics Meeting, 16 Mar 2004

Expected results

• For all GOH: No dead GOH

• For BERT GOH: No errors

• For sandwich GOH: Increase in laser threshold current with increasing dose, but minimal change in laser efficiency (slope)

minimal change in eye amplitude (as long as bias currents above threshold) minimal effect on optical power budget.

ΔIthr

7Jim Grahl, U. Minnesota

ECALECAL

CMS Week ECAL Electronics Meeting, 16 Mar 2004

Actual results: all GOH and BERT GOH

• For all GOH: No dead GOH

• For BERT GOH: • At most ~5 errors over the entire experiment, but these all occurred exactly when changing bias currents for sandwich GOH, and so should probably be discounted.• After ~20 hours there was a third beam incident after which the BERT could not be recovered. Probably non-rad-hard electronics on the mother test board were killed despite the lead shielding.

8Jim Grahl, U. Minnesota

ECALECAL

CMS Week ECAL Electronics Meeting, 16 Mar 2004

Actual results: sandwich GOH - 1

• For sandwich GOH:

• Eye amplitude stays roughly constant with increasing dose, as expected:

• Shielding of GOH higher in the stack is evident both in the plots above and in the photo taken after irradiation:

9Jim Grahl, U. Minnesota

ECALECAL

CMS Week ECAL Electronics Meeting, 16 Mar 2004

Actual results: sandwich GOH - 2

• Also for sandwich GOH: • Extracting threshold current and efficiency from the previous plots:

G. Dewhirst G. Dewhirst

• Threshold current rises smoothly with dose, as expected, for GOH 1 to 4. GOH 5 to 9 appear shielded.

• Efficiency (slope) is flat, as expected.

10Jim Grahl, U. Minnesota

ECALECAL

CMS Week ECAL Electronics Meeting, 16 Mar 2004

Conclusions

• All GOH survived irradiation, with doses up to 8 * 1013 p/cm2 .

• The BER observed was either extremely small (equivalent to 5 errors over the lifetime irradiation of ECAL) or zero.

• The GOH behaved as expected with respect to threshold current, efficiency and eye amplitude vs. dose.

• We plan to repeat these tests when we have assembled GOH with the CRT4T transistor.