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.