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Opto Working Group

SummaryF. Vasey, T. Flick

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WG meeting at TWEPP is the 2nd of the year, after a first WG meeting in spring

Topics of interest: Performance of the optical links in the various systems Plans for upgrades R&D projects

This year some of these topics were to be addressed in the optoelectronics and poster sessions on Thursday, and were not repeated during the WG.

Opto session details: https://indico.cern.ch/sessionDisplay.py?sessionId=19&confId=120853#20110928

Opto WG

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A. Current and future systems

B. Environmental tests

Agenda

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A. Current and future systems

B. Environmental tests

Agenda

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Decision: Death rate is ‘acceptable’

Regular repairs during technical stops – detectors are accessible

New batch of spares purchased from vendor no further action planned

1. LHCb StatusAs of Sept 2011, 1.8% of VCSELs died (and replaced)Silicon Tracker (IT+TT) most affected (2000 VCSELs)1 – 2 deaths per month

Ken Wyllie, CERN

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Triggerless readout: zero-suppression at front-end Use GBT + Versatile Link: ~ 11,000 data links + TTC/Slow-control

LHCb Upgrade plans

Ken Wyllie, CERN

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2. CMS Tracker

Jan Troska, CERN

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CMS Tracker

Jan

Tros

ka, C

ERN

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3. CMS E-Cal

Improvement

A.Singovski

University of

Minnesota

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Running very well, only some minor issues have been observed and are under study

Instability of some data and trigger links: loss of sync, timeout, etc. were fixed by decreasing GOH laser bias current

14 cases in 2011 (some new) Both EE and EB Bias current down to 16-22 (default = 32)

More or less uniform over the year not directly linked to LHC luminosity

In two cases: EE-7, TT3 and EB-12, TT15 decrease of laser bias current was not sufficient. The problem in both cases was fixed by the additional attenuator

CMS E-Cal

A.Singovski

University of

Minnesota

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present HCAL optolinkswork very well

For upgrade:Use GBT chipsetand commercial receivers at off-detector side and…

Eric Hazen, BU

4.

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5. AtlasTony Weidberg,

Oxford

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A. Current and future systems

B. Environmental tests

Agenda

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1. Irradiation Tests by CERN

VTx

VRxJan Troska, CERN

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2. Links at low Temperatures

Goal is to develop an optical data link system for the LBNE LArTPC.The challenge lies in the transmitting side in the LAr cryostat:- What about functionality and reliability TestingTests done using liquid nitrogen is used (LN2, 77 K) instead of liquid argon (LAr, 89 K) due to the cost.Tiankuan Liu,

SMU

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Test of different parts: fibres, connectors, laser diodes, drivers, serializer, FPGAs, resistors, capacitors by using a LN2 bath.

Tests performed

Temperature CurvePower through fibres

Laser driver @ 77K FP Laser operation I/V and L/I

Basically the componentscan work at lowtemperatures…

… but there is still a long way and Systematic studies are required to address reliability issues

Tiankuan Liu,

SMU

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Open reports about operational experience and progress Running systems either experience minor or very severe

problems. ATLAS SCT/Lar VCSEL problems seem to be under control. Thanks to very open reports, lessons are being shared.

Several systems have major upgrade plans: Medium term: LHCb and CMS-HCAL

Opto WG @ TWEPP is good to touch base. The attendance was larger than in the past years. The time was short, but sufficient to allow some discussion. Together with the spring WG mini-workshop, it offers a good and regular forum for information exchange and discussion.

Summary