1. Time Calibration for KM3NeT ARCA (and ORCA?)
Phase 2: Full white rabbit system

2. All White rabbit devices synchornised and synthonises
Pre-requisites:
1) all connections:
a) are bidirectional with one single fiber by design WRS fabric in DOM and Base* (SC and DC path with same fiber length)
WRS-Grand Master (GM) to/from WRS-Masters (M), on shore and test WRS fabrics
CLB (DOM to/from WWRS)
b) in SS and JB asymmetries (see slide 3) must be measured in advance and must be added as HW delays in the info files of WR network elements*.
the info files of all WR devices should be configurable also from shore
WRS-Master (on shore) to/from WWRS A and WWRS B (DU Base)
WWRS A to/from WWRS B (DU Base) (In case of failure of one WWRS the other will take over)
2) The WR hardware delays (electronics) of CLB, WWRS and WRS fabric elements (each port!), including SFPs must be measured and set into the info files of each WR devices*.
Calibration Procedure
3) The chromatic dispersion of MEOC fibers must be measured and set into the info files of WR network elements* (IL and VEOC are negligible but can be also considered)
* and stored in the Km3NeT Database

3. Detector Architecture: Time Calibration view Shore Station (SS)* DOM
TGPS = TAI
PPS synchronisation on-shore
Set RXS/TXS
Set MEOC fibre asymmetry
GPS
VEOC
TWR
THit=TWR+(TTPMT+TTelec)
WRS-M
WWRS-A
CLB
DOM
TWR
JB*
Measure Delay PPS
(GPS-WRS-GM)
TWR
CLB
base IL
TWR=
TAI+ DT
PPS synchronisation on-shore
Set RXS/TXS
Set VEOC fibre asymmetry
(x7 JBs)
PPS synchronisation on-shore
Set RXS/TXS
No fibre asymmetry
WRS-GM
PPS synchronisation
on-shore
Set RXS/TXS
WWRS-B
WRS-M
TWR
WRS-M
WRS-M
DU Base
WRS-M
* Fiber lengths asymmetries to be measured
WRS-M

4. DOMs
DU base JB SS SC SC SC DC DC DC
NO SC/DC asymmetry:
Single fibre
Asymmetries SC/DC:
measure before JB integration
Asymmetries SC/DC:
measure during SS integration
NO SC/DC asymmetry:
fibres of same length
by design

5. Procedures
A) GPS – WRS GM delay (connection Lemo/BNC line):
in place*
B) Shore and Test station WRS fabric (GM/M) syntho/synchronisation
C) WRS-M – WWRS syntho/synchronisation
WWRS – CLBs syntho/synchronisation
on bench (new)
D) Measurement of fiber length asymmetries of JB an SS
E) Measurement of chromatic dispersion of MEOC
F) PMT – CLB time delay
in dark room, in place* (with few modifications) *

6. WRS-M – WWRS syntho/synchronisation
Equipment:
WR—GM, 2 WWRS, Scope or TDC, 3 lemo/SMC delay lines (same propagation time),
3 Optical fibers (same propagation time)
Use the WRS-GM and WWRS ports that will be used off-shore for the final DU connection
Procedure:
Align PPS’s, modifying and setting the WWRS WR info files (RXS/TXS, see reference procedure* for WRS fabric synchronisation)
WWRS-A
WRS-GM
Test Bench
WWRS-B
PPS
PPS
PPS
Scope or TDC
Carried out at the WWRS production site or in one KM3NeT site
Optimistic: all WWRS have the same physical HW delay (one set of parameters for all)
Pessimistic: each WWRS has a different physical delay (measurement needed for all boards) *

7. WWRS – CLB syntho/synchronisation (Option 1) Equipment:
WR—GM, 2 WWRS (pre-calibrated), 32 ch TDC, 19 CLBs and 22 lemo/SMC delay lines (same propagation time)
Use the WRS-GM and WWRS ports that will be used off-shore for the final DU connection
Procedure:
align CLB PPS modifying WR info files of CLB or WWRS (see next slide)
CLBs must have a Lemo Connector for PPS out
PPS x 18
WRS-GM
Test Bench
X18 CLBs
PPS
PPS
32 ChTDC
PPS
Carried out at the CLB manufacturer or in one KM3NeT site
CLBs syntonisation must be verified in both connection options
(through WWRS-A or WWRS-B)

8. WWRS – CLB syntho/synchronisation (Option 1)
Optimistic Case:
all CLBs and all WWRS have the same HW delay (port dependent)
One test bench can be used to perform calibration measurements and (optionally) checks
maintain CLB WR RXS and TXS parameters=0, set only WWRS ports RXM and TXM parameters (equal for all WWRS)
Pessimistic Case:
each CLB and WWRS has a different HW delay
Measure and set WR parameters before distributing WWRs and CLBs for integration.
DU/DOM of CLBs and WWRSs will be defined at this stage
In both cases add asymmetry due chromatic dispersion of VEOC (if larger than 100 ps for 750m VEOC)

9. 19 Output signal generator
WWRS – CLB syntho/synchronisation (Option 2)
Equipment:
WR—GM, 2 WWRS (pre-calibrated), 19 output signal generator, 19 cables (same propagation time)
Use the WRS-GM and WWRS ports that will be used off-shore for the final DU connection
Procedure:
Measure Thit on each CLB
In this case the CLB time will have a fixed delay with respect to the WR time
ToT-Like signal x18
WRS-GM
Test Bench
X18 CLBs
ToT-Like signal
19 Output signal generator
Carried out at the CLB manufacturer or in one KM3NeT site
CLBs syntonisation must be verified in both connection options
(through WWRS-A or WWRS-B)

10. Dark Room Calibration (TTPMT + TTelec delay)
Equipment:
Test Station (1 WWRS-GM), laser emitter and splitting system
Use the WRS-GM that will be used off-shore for the final DU connection
Procedure:
Perform Intra-DOM calibration* (40K glass coincidences): Thit measures TTPMT+TTelec
Perform Inter DOM calibration* (laser, cosmics) as a check measurement (CLBs are time calibrated)
Provide DU T0 set (per each PMT)
Clock+PPS
VEOC
x18
Laser emitter
Test Station
DU Base
GPS
WRS-GM *

11. From Dark room to Sea
After Dark Room Calibration
1) add in the WWRS WR info file (RXS and TXS of the port connecting to WRS-M on shore) the fiber length asymmetry (SC-DC) values measured in the Shore Station and in the JB
2) In the same port add the asymmetry value due to MEOC chromatic dispersion
neglect IL if effect is <100 ps for the maxium IL length
T0 set remains unchanged
In sea:
Re-perform 40K intra-DOM time calibration,
Change T0 set
Periodically check inter-dom time calibration with nano-beacons and laser beacon
(choice to be clarified: in case of differences act on WWRS port HW delays or T0 set ?)