1. Moving towards Elba and the TDR …
Dominique Breton
(with special thanks to Andy Lankford)
SuperB workshop – SLAC – February 2008

2. Dominique Breton – SuperB workshop – SLAC – February 2008
Workshop summary (1)
Trigger and DAQ:
Need of a fully triggered system, including EMC
Aim at level 3 track precursors from SVT
The main worry is the event size (background and new detector dependent)
Some intelligence is necessary on the detector in order to cope with the high data and trigger rates. Whatever it is has to be remotely and safely reprogrammable.
L1 central Trigger hardware is an electronics subsystem by itself
A note will be circulated before Elba, in order to roughly define the requirements
Boundary between DAQ and subsystems:
The optical link is just a natural physical separation between them
We could imagine that DAQ and FCTS linked common elements can be considered as part of DAQ on the detector side
Their physical implementation could however be in charge of subsystem groups and reviewed by DAQ experts
Radiation:
Simulations have to be performed, especially for neutron flux (electronics can therefore be defined as a subsystem)
Mitigation methods including choice of components will depend on the resulting rates.
Dominique Breton – SuperB workshop – SLAC – February 2008

3. Dominique Breton – SuperB workshop – SLAC – February 2008
Workshop summary (2)
FCTS :
Mixing of clock and data in the same link may be inadequate for ps-sensitive detectors
New gigabit transceivers have to be tested
Use of jitter cleaning PLLs might be necessary
Length of time counters has to be studied to keep data rate reasonable
Coarse time information could be shared between channels
Common design:
Detector-sided electronics may be common if necessary in case of global common needs
This is especially true for FCTS and DAQ linked elements
Interaction has to be maximum between subsystems
Subsystems:
Should aim at presenting a preliminary architecture coping with the common trigger/DAQ requirements in Elba
Dominique Breton – SuperB workshop – SLAC – February 2008

4. Dominique Breton – SuperB workshop – SLAC – February 2008
Electronics organization (1)
In BABAR, the grouping at the design and realization phase of all electronics in one electronics group proved very effective to assure commonality and uniformity. The caveat here is to maintain enough relationship with the subdetector group, but this is not very hard to achieve.
Like in BABAR, we could group all of the following in a single working group:
Front-end electronics
Data acquisition (and dataflow software)
Trigger (including Level 3 Trigger)
Electronics for detector controls
Electronics infrastructure
Each subsystem has at least a representative attending the meetings of this group.
Each of said subgroups concentrates in its work area.
This comprehensive group has to worry about:
The conception of the system design
Setting up the reviews during the design cycle
Sharing solutions between subsystems
Pushing subsystems to help each other out during design and implementation
Affording the flexibility to redeploy resources
Dominique Breton – SuperB workshop – SLAC – February 2008

5. Dominique Breton – SuperB workshop – SLAC – February 2008
Electronics organization (2)
Regarding working with multiple institutions:
There is a need for good communications and frequent contact.
"Developing electronics with the involvement of several labs on two continents requires very good communication between teams. Thanks to the Web and video conferences, it is now easy to exchange quickly any kind of documents. However, at the very beginning and at the end obviously, nothing can replace meetings and work in-situ. Reviews offer opportunities to exchange ideas, stay on (or leave a bad) track, get out of your computer screen."
There must be at least one qualified person at the institution.
Significant travel is involved:
Regular meetings for all (at least 3/year)
Site visits for coordinators
Reviews are even more important (with the participation of experts from other subdetectors):
particularly to cover interfaces
for sharing the knowledge and experience between groups
for making the design effort more harmonious
Dominique Breton – SuperB workshop – SLAC – February 2008

6. Dominique Breton – SuperB workshop – SLAC – February 2008
Requirements
Defining requirements at the outset of the project is essential.
Proper discourse between engineers and physicists is mandatory.
Requirements provide the yardstick against which performance of prototype and production systems are measured.
Without this metric, risk that:
System will not meet the performance requirements of the experiment.
Design will not converge as design team strives for useless performance.
Design will be overly complex, causing undue technical risk.
Requirements should be realistic: simple is beautiful!
Why take undue technical risk (and hence cost & schedule risk)?
"Everyone can add features that delay and sometimes compromise the main goals. Unnecessary complexity is often the result of too many people interacting. This is a drawback of easy communication.“
Requirements should be documented.
In order that they are not forgotten, and are available to newcomers on project.
Motivation for requirements should also be documented.
Designers should be able to question requirements when they are found difficult to meet.
This record can be important if the underlying assumptions of a requirement change.
Dominique Breton – SuperB workshop – SLAC – February 2008

7. Dominique Breton – SuperB workshop – SLAC – February 2008
System design (1)
Do the system design first.
Do the system design "top down", not "bottoms up".
Seems obvious, but it often doesn't happen that way.
Establish a system design with unified :
Control mechanisms.
Data acquisition.
Monitoring.
Make certain that all subsystems buy into the common solutions, yet give the subsystems flexibility in the detailed implementation.
Acceptance is important to the completeness and success in the implementation.
We established acceptance by involving the entire community in the development of the protocols and standards.
Flexibility in detailed implementation.
Allows subsystems to tailor protocols and standards to the details of their system.
Allows subsystem designers to take ownership of their subsystem.
Dominique Breton – SuperB workshop – SLAC – February 2008

8. Dominique Breton – SuperB workshop – SLAC – February 2008
System design (2)
One should not always follow standard approaches or architectures.
Understand your requirements.
Depart from convention when it simplifies your system design
Although BABAR adopted a "standard" deadtimeless, multilevel architecture,
Its all digital L1 latency buffers allowed a long L1 decision time (12.5s). This simplified requirements and reduced the cost of L1 Trigger without impacting front-end cost
Its modest occupancies allowed a "pull" architecture between FEE & DAQ. This greatly simplifies buffer management and event synchronization.
We have to pay attention to all aspects of the system during the design phase, including:
Power supplies & power distribution.
Cabling.
Cooling.
And, of course, Grounding & Shielding
An experienced electronics engineer contributes invaluably to the success of the system design.
Dominique Breton – SuperB workshop – SLAC – February 2008

9. Dominique Breton – SuperB workshop – SLAC – February 2008
Planning
We’ve to budget plenty of design time up front.
"Spending sufficient time to make sure the design (overall and detail) is right and that it communicates properly with other parts is very important, since making it later work by testing and debugging the hardware is much more time consuming and expensive."
When drawing up our schedule, we should plan backwards from the earliest date that the electronics could be used by the detector. Then we conservatively schedule time for commissioning, installation, testing, production, and prototyping. Then we add some contingency. All the remaining time, we allow for design.
For all board-level components, we should schedule:
1 full-functionality prototype, most of the time preceded by partial prototypes
1 preproduction model, intended to be identical to production version
1 production run for high volume items, assembly & test of 1st articles before full system
For IC's, we’ll probably have to budget more prototyping rounds
Dominique Breton – SuperB workshop – SLAC – February 2008

10. Dominique Breton – SuperB workshop – SLAC – February 2008
Towards the TDR
We would like to have the TDR ready beginning of 2010.
The architecture of all the subsystems electronics has to be clearly defined ahead.
Not only the subdetector specific but also the common solutions have to be described
The ASIC requirements and architecture have to be fixed
Alternate solutions can be described, but a baseline must be chosen
Cost must be estimated as sharply as possible, including prototypes
TDR writing also relies on electronics groups.
Electronics meetings have to take a growing place during the SuperB collaboration meetings
Electronics groups organization should be set up about one year ahead of TDR.
Top-down transmission of the requirements have to specify the constraints on the DAQ and trigger sides of subsystems electronics as early as possible
We have to pay attention to all formerly quoted aspects of the system while preparing the TDR, trying to normalize:
Power supplies & power distribution.
Cabling.
Cooling.
Grounding & Shielding
It’s also important to describe the radiation mitigation policy.
Dominique Breton – SuperB workshop – SLAC – February 2008

11. Dominique Breton – SuperB workshop – SLAC – February 2008
Conclusion
See you there …
Dominique Breton – SuperB workshop – SLAC – February 2008