Transcript conclusionsx

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

Dealing with the radiation hazard
Get a good knowledge
of the environment
Understand
the effects
Define the requirements
for the components
Identify the candidate
components
Test the candidate
components
Engineer the system
Federico Faccio - CERN

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
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
Federico Faccio - CERN
Radiation Concerns in Power Supplies
 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
June 2nd, 2009
R2E Radiation Workshop&School F.Anghinolfi PH/ESE
6
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 unacceptable
7
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



Low level zones: < 100Gy, <1010 >2oMev h cm-2
(cavern),




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)
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.





Shielding wall
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
COTS Electronics
+ CPU farm
All participants in global project
(experiments + machine + ?) must
be aware of the potential problems.



Custom rad hard
On-detector
electronics
LHC machine equipment
next to experiment and
in “hidden” service cavern !
Extensive exchange of
information/experience
Key part of project requirements
Reviews
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


High power devices in radiation zones


SEE effects can become “catastrophic”
Particular known weak components


Computers, PLC, Complicated Communication interfaces , ,
Some types of opto couplers, etc.
Uncritical use of complicated devices (e.g. FPGA’s)
10
Triple Module Redundancy

Triple redundancy

Input
FSM2
Voting logic
FSM1

Output

Used regularly in:


FSM3

CLK


Logic for Voting
11

A. Marchioro / PH-ESE
High reliability
electronics
Mainframes
Problems:

A
B
A
C
B
C
Three copies of same
user logic +
state_register
Voting logic decides 2
out of three (majority)
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?
Logic
Use this:
If clock frequency is low
and technology is “old”.
12
Comparison logic
Logic
Reg
Comparison logic
Output
Logic
Output
Reg
Input
Reg
Reg
Logic
Reg
Input
Reg
What to duplicate?
Use this:
If clock frequency is high and
technology is “advanced”.
A. Marchioro / PH-ESE
Radiation Engineering
h > 20 MeV
Single Events
h > 100 KeV
EM cascade
nuclear cascade
Dose
Displacement
p,n,p or HI beams
radiation damage
semiconductors
60Co
nuclear reactor
source
Radiation Testing
6/3/2009
CERN Radiation school Divonne
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
–
–
–
–
6/3/2009
Cables and connectors:
inversion, pin integrity,cables blocked or damaged during a tilt, etc
Electrical noise
Parasitic light
CERN Radiation school Divonne
How we are doing it?
A unified inquiry form
①
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
①
Structuring the collected data,
(traceability, existing documentation);
①
② Characteristics
Scoring the relevance of the need/equipment
(operational, radiological, economical)
③ Maintenance
Identifying the technical needs (maintenance,
machining, radiological)
①
Oper. Waste
Long Term
Medium Term
Buffer
④ Storage
Locating where the needs are/could be fulfilled
(technical, operational, radiological,
present & future needs).
Material Controls & Waste Zoning
ZDC
Individual controls of material and waste
by DG-SCR not required - follow up by sampling
ZO
Zone
operationnel
ZDR
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.
2.
3.


Safety of personnel
Safety of the machine
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