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