Sophie Baron TTC 1

TTC status

February 2005

ATLAS electronics

Sophie Baron TTC 2

TTC news

TTC backbone• General structure and main modules

TTC support

2004 structured test beam

TTC modules• TTCrq

• TTCoc

• Clock generator

TTC fibres• Timing stability

• Commissioning

TTC future

Sophie Baron TTC 3

TTC global view

Bunch Clock and Orbit transmission

BC=40.079MHz, Orbit=11.246kHz

Phase Stabilized SM fibre - 9.5km

Normal SM fibre - 3.8km

PCR

Back to temp check

Sophie Baron TTC 4

TTC partition

TTC in Atlas

LTP

CTPL1A triggers Rod Busy

L1A

LHC BC & ORBIT

BCID, EVID, TType, calibration and test signals

TTCvi

TTCoc

TTCrq

TTCrx

TTCmi

TTCexTTCtx

TTCvx

Sophie Baron TTC 5

TTC receivers

TTCrm-Agilent-TTCrx

TTCrq-TRR -TTCrx -QPLL

TRT-TTC-TTCrq

TIM-TTCrq

Agilent-2316T

Truelight-TRR-1B43

Optoelectronics receivers

+

TTCrx

+ (QPLL)

TTCmi/LHCrx-TTCrm

-Low jitter <50ps rms-Add constraints on the BC frequency. Locking range:40.0786MHz +/- 3.7kHz

--------------------------------- Used in ------------------------------------------------------------

Sophie Baron TTC 6

TTC support

Support:• Orders, production, testing and delivery of modules

o Markus JOOS / PH-ESSo Web site: http://ess.web.cern.ch/ESS/TTCsupport/index.htmo Q1-2/05, production of:

• TTCrq 2000 pieces• TTCex/tx 120 pieces

• Engineering and technical support o Sophie Baron / PH-ESSo Web site: http://ttc.web.cern.ch/

Sophie Baron TTC 7

2004 Structured Test Beam 14-21 June, 5-11 October 12 seconds cycles, with bunches at 25ns spacing fixed BC and real SPS orbit transmitted by the TTC system SPS RF frequency “resynchronized” 500ms before beam extraction

to fixed 40.0788 MHz,

5Hz

Sophie Baron TTC 8

TTC modules status - TTCrq

-10 0 10 20 30 40 50 60 7040.074

40.075

40.076

40.077

40.078

40.079

40.08

40.081

40.082

40.083

40.084Excess Jitter Points for crystal xtal MC A

Temperature [C]

Fre

quen

cy [

MH

z]

Activity dips problem - August-November 2004: • Problem discovery: at some frequencies

and temperatures the QPLL jitter was largely exceeding the typical values.

• With the help of Nevis, CERN and Micro Crystal worked quite hard to analyse the problem and finally confirm that it was due to activity dips in the crystal due to excessive power driving.

Activity dips are due to vibration modes that are mechanically coupled to the fundamental resonant mode.• These modes can have frequencies quite

close to the fundamental mode and are very dependent on temperature.

• They can thus interfere with the fundamental mode distorting the electrical characteristics of the crystal near the resonance.

Sophie Baron TTC 9

-10 0 10 20 30 40 50 60 7040.074

40.075

40.076

40.077

40.078

40.079

40.08

40.081

40.082

40.083

40.084Excess Jitter Points for crystal xtal super A MC

Temperature [C]

Fre

quen

cy [

MH

z]

TTC modules status

TTCrq – activity dips problem: • November-December:

o Once the problem analysed: Find a simple and effective way of reducing the power delivered to the crystal.

o Solution validated, design and layout modifiedo Pre-production to be received this week

R1 = 62 , R2 = 240 , C = 10 nF

Sophie Baron TTC 10

TTC modules status

TTCoc

TTCreceiver

TTC crate

TTCreceiver

TTCreceiver

TTCreceiver

TTCreceiver

TTCreceiver

TTCex/ Single mode

TTCoc/ Multi mode

MultiMode Fibers

MultiMode Fiber

MultiMode Fibers

Sophie Baron TTC 11

TTC modules status

TTCoc (cont.)

Consequences of mixing different modes:• Insertion loss can not be specified: measurements shown 20dB spread between 2 outputs

and could be worst• Although the “standard” TTC receiver (TrueLight) works in a very wide range [-5dBm, -

26dBm], some of the ATLAS sub-systems have stringent requirements on the level of lighto E.g. Tile : [-15dBm,-21dBm], using the Agilent receiver

Solution proposed for ATLAS: Fibernet hybrid coupler: • single-mode input and multi-mode output

• Same cost as initial design

• No need for changing existing fibres

• Very good uniformity

Some other solutions have been proposed for other experiments (SM2SM couplers, Mode Scramblers)

Optical power attenuation of 6 TTCoc with single mode source (TTCex)

-25

-23

-21

-19

-17

-15

-13

-11

-9

-7

-5

0 5 10 15 20 25 30 35

Output #

Op

tic

al p

ow

er

(dB

) fibernet

TTCocPrototype

TTCoc19

TTCoc10

Fibernet16B

Fibernet32B

Optical Power on the output of 6 TTCoc with multimode source (TTCvx)

-41

-40

-39

-38

-37

-36

-35

-34

0 5 10 15 20 25 30 35

output #

Mea

sure

d O

pti

cal

po

wer

(dB

m)

fibernet

C502

FCI19

FCI10

i-tronik 10

i-tronik 8

Sophie Baron TTC 12

TTC modules status

New Clock generator module:• 40.078 MHz => compatible with QPLL

• ECL fanout

• VME form-factor

• Quartz 80.1574MHz ordered by Per Gallno and already delivered

• Will be done 1Q/05

Sophie Baron TTC 13

TTC fibres

Phase stability problem• Clock journey

• Fibres are buried but the temperature is not constanto Temperature coefficient 6.8 ppm/oC

• Measurements of phase shift versus external temperature made J. Troska and S. baron on a round trip PCR-PA5 i.e. 20 km

Sophie Baron TTC 14

TTC fibres

Phase stability problem (cont.)

20km: 200ps typical diurnal variation

ATLAS (4km): ~50ps typical diurnal variation

CMS-PCR-CMS fibre loop: Phase shift & temp vs time -17/12/04-03/01/05

-5.00E-10

0.00E+00

5.00E-10

1.00E-09

1.50E-09

2.00E-09

15 20 25 30

time (days)

Ph

ase

mea

sure

men

t

-8

-6

-4

-2

0

2

4

6

8

10

12

Loop-ref

Temp

Poly. (Temp)

=> Not acceptable for ATLAS

=> Investigation on the use of Phase Stabilised Optical Fibres (PSOF) from Prevessin to ATLAS.

20km: 1ns for 2°C average variation

ATLAS (4km):

• 100ps variation / 1°C

• 1.5ns typical seasonal variation (15°C)

Sophie Baron TTC 15

TTC fibres

Atlas commissioning• OTDR requested for fibres measurements

• Precision : 5cm : photon counting technique (22000-26000 €)

• Wavelength 1310nm

• Single-mode or Multi-mode?

• Purchased by the pool and rented to experiments

Other needs?

Sophie Baron TTC 16

TTC future

TTC crates relocation:o January 2005: PCR => AB/CO labo December 2005: AB/CO lab => CCCo New fibres being installed nowo Simulated 40.078MHz will be available in March (no machine timing)o Fibres available for ATLAS for testing purpose.

Maintenance problems:• Maintenance of the TTCmi crates

• Maintenance of the high power lasers (PCR)

Installation:• PSOF if needed

• Installation of the SR4 transmitters