Why a course We will try to answer the following questions:
How do know I am in a “risky” area I design a rad-tolerant electronic system
(hardware/software)? How do I make sure the device is really radiation
tolerant? What should I test it and where can I do it? What kind of support may I receive for the test? What kind of resources my group (leader) has to
provide for the preparation and test? How can I do all that, and deal with irradiated
electronics SAFELY
Federico Faccio - CERN
Dealing with the radiation hazard
Define the requirements for the components
Identify the candidate components
Test the candidate components
Get a good knowledge of the environment
Understand the effects
Engineer the system
Summary Make sure you understand the requirements
Simulation of the environment is essential Try to select the components/technologies
Pay attention to the requirements Test your components
Look around, you may find some information about the selected components
Try to assess the risk SEU may not be critical, or it can be catastrophic
Mitigate Verify
2/6/2009 R2E Radiation School: SEU effects in FPGA 3
June 2nd, 2009 R2E Radiation Workshop&School - F.Anghinolfi PH/ESE
4
Federico Faccio - CERN
Summary• Radiation effects• Risk management
– risk avoidance impossible with COTS!– more efficiently applied at system level!
• Steps to deal with the radiation hazard– know the environment– understand the effects– define the requirements– identify the candidate components– test– engineer the system
June 2nd, 2009 R2E Radiation Workshop&School - F.Anghinolfi PH/ESE
Radiation Concerns in Power Supplies
6
Some conclusions :
The SEB, specific defect of “high voltage” power devices, is easily turned down by the proper derating of VDS (tests are necessary)
TID, NIEL (neutrons) can still be a problem for long term operations, upgrades … (Voltage reference drifts, optocouplers functional loss)
Logic circuits in exposed areas are subject to functional failures, some of them may be critical in power systems (SEU)
Custom made power units (in the case of experiments, “customized” because of the radiation and/or magnetic field tolerance …) were always (?) presenting some reliability issues after fabrication.
THE TESTS IN APPROPRIATE PARTICLE ENVIRONMENT (Ionizing, NIEL, high energy PROTONS) PROVED TO BE USEFUL FOR THE DEFECT ANALYSIS
What risks to take ? Risk analysis
What local failures provokes what system failures ?
This is often more complicated than initially thought Can a given failure destroy other equipment Hard and soft failures How long does it take to recover from this ?
Fold in radiation induced failure types and rates Zero risk do not exist Very low risk will be very expensive Anything else than low risk will be
unacceptable7
Radiation “zones” High level zones: 1MGy – 1KGy, 1015 – 1011 >2oMev h cm-2 , 10
years (trackers) Everybody knows (must be made to know) that radiation has to be
taken into account and special systems based on special components needs to be designed/tested/qualified/etc.
TID, NIEL, SEE - Estimate of soft failure rates -> TMR ASIC’s
Intermediate zones: 100Gy – 1kGy, 1011 – 1010 >2oMev h cm-2 (calorimeters and muon)
ASIC’s Potential use of COTS
Radiation tests for TID, (NIEL), SEE (Use available tests if appropriate) Special design principles for SEE (e.g. Triple Modular Redundant, TMR in FPGA’s)
Low level zones: < 100Gy, <1010 >2oMev h cm-2 (cavern),
Extensive use of COTS TID and NIEL not a major problem SEE effects can be severely underestimated
Safe zones: < ? (LHC experiments: counting house with full access)
One has to be very careful of how such zones are defined. Do not confuse with low rate zones !!!
8
The Wall (not by Pink Floyd) LHCb experience:
Physical (thin) walls does not make problem disappear.
What you do not see, you do not worry about.
When you see it, it is too late. Lots of concrete needed to give
effective radiation shielding. Political/organisatorial walls
does not make things better
All participants in global project (experiments + machine + ?) must be aware of the potential problems.
Extensive exchange of information/experience
Key part of project requirements Reviews
Shielding wall
COTS Electronics + CPU farm
Custom rad hardOn-detectorelectronics
LHC machine equipmentnext to experiment and in “hidden” service cavern !
9
What to avoid Underestimate the problem Safety systems in radiation Forget that local errors can propagate to the system level
and make the whole system fall over (very hard to verify in advance for complex systems)
Assume that somebody else will magically solve this.
Complicated not well known electronics (black box) in radiation environment
Computers, PLC, Complicated Communication interfaces , , High power devices in radiation zones
SEE effects can become “catastrophic” Particular known weak components
Some types of opto couplers, etc. Uncritical use of complicated devices (e.g. FPGA’s)
10
11
Triple Module Redundancy Triple redundancy
Three copies of same user logic + state_register
Voting logic decides 2 out of three (majority)
Used regularly in: High reliability
electronics Mainframes
Problems: 300% area and power corrects only 1 error can get very wrong with
two errors Problem: How do you
make sure that the voting logic itself is not affected by SEU?
FSM1
FSM2
FSM3
Votin
g lo
gic
InputOutput
CLK
A. Marchioro / PH-ESE
ABACBC
Logic for Voting
12
What to duplicate?
Reg
Input
Output
A. Marchioro / PH-ESE
Logic
Reg
Com
paris
on lo
gic
Reg
Input
Output
Logic
Reg
Com
paris
on lo
gic
Logic
Use this:If clock frequency is high and
technology is “advanced”.
Use this: If clock frequency is low and technology is “old”.
Reg Logic
Reg
Radiation Engineering
CERN Radiation school Divonne
DoseDisplacement
Single Events
EM cascadeh > 100 KeV
h > 20 MeV
60Co sourcenuclear reactor
p,n,p or HI beams
nuclear cascade
radiation damage semiconductors
Radiation Testing
6/3/2009
Lessons Learned• Preparation has to be impeccable :
– Dedicated team of at least 2 persons/device– Complete test setup prepared– Irradiation plan– Sufficient spares– Dry run before leaving CERN
• Data validation: back to home, it is too late– To have the beam data in real time– to perform a data analysis (first check) upon completion of each run
• Set-up installation: trouble issues– Cables and connectors:– inversion, pin integrity,cables blocked or damaged during a tilt, etc– Electrical noise– Parasitic light
CERN Radiation school Divonne6/3/2009
A systematic, unified approach is being followed by a unique inquiry form (EDMS 998529) to collect the equipment exploitation data. The form covers:① Equipment Identification Structuring the collected data, (traceability, existing documentation);② Characteristics Scoring the relevance of the need/equipment (operational, radiological, economical)③ Maintenance Identifying the technical needs (maintenance, machining, radiological)④ Storage Locating where the needs are/could be fulfilled (technical, operational, radiological, present & future needs).
How we are doing it?A unified inquiry form
Buffe
r
Med
ium
Term
Long
Term
Ope
r. W
aste
① ②
③
④
Material Controls & Waste Zoning
ZDR
ZDC
ZOZone
operationnel
Individual controls of material and wasteby DG-SCR not required - follow up by sampling
DG-SCR controls required(comprises all CERN accelerator tunnels, target areas and experiments of SPS, PS complex, ZO of LHC experiments
And NOW?
LHC tomorrow Areas and system classified in terms of
criticality: Radiation levels assessed (or under assessment) Priorities for systems:
1. Safety of personnel2. Safety of the machine3. Operation of the machine (reduction of downtime)
Short term measures (now!!) for 1 and partially for 2
Long term measures (shutdown 2010/2011) for 2 and 3
Radiation levels http:\\Cern.ch\R2E
If not sure, contact Markus Brugger
Design reviews If you need help, volunteer for a design/test
review.
If your system is critical, it is not excluded that you will be requested to organise a review.
Please participate to RADWG, and contact Thijs who can advise you or send you to the right people.
Share your experience with the others.
A big THANK Markus Brugger & C., for organisation
PH-ESE for support and for being here the two days (and finding the speakers).
DG-SCR (RP)
All the lecturers