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Radiation Assurance in the LHC experiments

Martin DentanCEA Saclay

Philippe FarthouatCERN

With the help of

Francis AnghinolfiJorgen Christiansen

Mika HuhtinenPeter Sharp

Giorgio Stefanini

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Outline

Radiation Issues Radiation constraints in the experiments Radiation hardness assurance in the

experiments A few examples of difficulties Conclusions

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Radiation Issues (1)

Cumulative effects– Total Ionising Dose (TID)

» Energy deposited in the electronics by radiation in the form of ionization.

» Unit:Gray (Gy), 1 Gy = 100 rad» Affects all electronics devices

– Non Ionising Energy Loss (NIEL)» Displacement damage» Unit: particles/cm2 » Complex radiation 1 MeV neutrons equivalent» CMOS devices are not affected

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Radiation Issues (2)

Single Event Effect (SEE)– Destructive effects: SEL, SEB, SEGR, …– Upsets: SEU (logic), SET (linear)– Instantaneous effect: may occur just after the

beam is switched on.

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Radiation Issues: TID

Charge trapping in oxides and interfaces Vt shift, change gm, leakage current, noise, … Cumulated damage => delayed effect Dose rate and temperature dependence Effects on MOSFETs, BJTs, diodes, … May appear after only few krads

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Radiation Issues: NIEL

Bulk defects in semiconductors , noise, … Cumulated damage => delayed effect Effects on bipolar devices No effect on MOSFETs

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Radiation Issues: SEE

Energy deposition in the component Can change the state of logic node (SEU) or generate

transients in linear circuitry (SET) Can trigger parasitic components and generate latch-up

(SEL), burn-out (SEB),.. A work done by M. Huhtinen, F. Faccio has shown that only the

hadrons of E > 20 MeV have to be considered

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Radiation constraints: ALICE

TID (10 years) – 2.5kGy (pixels

inner layer @ 3.9cm radius)

– 1 Gy (in the experimental hall)

NIEL (10 years)– 2.1012 n.cm-2 (pixels

inner layer @ 3.9cm radius)

– 108 n.cm-2 (in the experimental hall)

Radiation levels: internal note with updated calculations–A. Morsch, B. Pastircak (to become available end Sept 02)

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Radiation constraints: ATLAS

TID (10 years)– 3 MGy (Pixels)– 5 Gy (Cavern)

NIEL (10 years)– 2 1015 n.cm-2 (Pixels)– 2 1010 n.cm-2

(Cavern) SEE (10 years)

– 3 1013 h.cm-2 (Pixels)– 2 109 h.cm-2

(Cavern)– h > 20 MeV

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Radiation constraints: CMS

TID (10 years)– 8 MGy (Pixels)– 5 Gy (Cavern)

NIEL (10 years)– 2.5 1015 n.cm-2

(Pixels)– 2 1010 n.cm-2

(Cavern) SEE (10 years)

– 3 1013 h.cm-2 (Pixels)

– 2 109 h.cm-2 (Cavern)

– h > 20 MeV

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Radiation constraints: LHCb

TID (10 years)– 0.1 MGy (vertex)– < 100 Gy (cavern)

NIEL (10 years)– 1015 n.cm-2

(vertex)– 2 1012 n.cm-2

(cavern)

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Radiation constraints: summary

ATLAS and CMS are very similar– 10’s of MRad in the trackers– 100 – 1000 kRad in the calorimeters (Em)– A few kRad in the muon spectrometers and the

caverns LHCb

– A few Mrad in the vertex– A few kRad in the calorimeter and muon

» Although the muon electronics has more ALICE has lower levels

– 250 kRad in the pixel– Less than a kRad in the cavern– SEE have still to be taken into account

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Radiation Hardness Assurance

Goal: reliability of the experiment with respect to radiation

The radiation hardness assurance methods must be applied to each sub-system of the experiments– Particular attention should be paid to the

identification of critical elements and to the possible failure modes

Should be coherent– Same rules for every system

Apart for the tracker electronics, there are differences between the experiments

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Radiation hardness for inner trackers

Very uniform policy within the four experiments– Use of radiation hard technology (DMILL)– Use of DSM technology with a rad-hard lay-out– Very strict qualification for other components

» e.g the optical links components

Status of design and production

Experiment Detector Chips Techno Status ALICE Pixels FE DSM Pre-production Si Strip HAL25 DSM Prototyped Si Drift PASCAL, AMBRA

/ CARLOS DSM Prototyped

ATLAS Pixels FE DSM Prototyped

Control DSM Prototyped

SCT ABCD DMILL Production almost finished TRT ASDBLR DMILL On going pre-production

DTMROC DSM Fully working prototype

CMS Pixels FE DMILL Prototyped FE DSM Being designed Tracker APV25 DSM Production started LHCb Vertex FE DSM Prototyped Beetle DSM Prototyped

Others SCTA DMILL Prototyped

Otis DSM Prototyped Carioca DSM Prototyped Dialog DSM Prototyped Sync DSM Prototyped GOL DSM Prototyped

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Radiation Hardness Assurance: Constraints

Basis for the tests to be done Needed:

– TID (Gy), NIEL (1 MeV equiv. N.cm-2), “SEE” h.cm-2 (E > 20 MeV) Very desirable to have tools to get these constraints in

small elementary domains– Averaging may lead to optimism

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Radiation Hardness Assurance: Constraints

ATLAS MDT readout ASICLeakage current versus TID

Average constraint

Hot points(a few 10’s of ASICs)

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Radiation Hardness Assurance: Constraints

Constraints from simulation tools (Fluka, Gcalor, Mars)– There are uncertainties due to the physics models,

to the detector model, …– There are uncertainties with the electronics

Safety Factors

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Safety Factors

Simulation uncertainties (location and type dependent)– ALICE proposes from 2 to 3 – ATLAS ranges from 1.5 to 6 – LHCb uses 2– CMS quotes from 1.3 to 3

Electronics effects– Low dose rate effects

» ATLAS ranges from 1 to 5 depending on radiation type, technology and tests procedures (e.g. annealing at high temperature)

– Lot to lot variation for the COTS» ATLAS ranges from 1 to 5» LHCb ranges from 2 to 100

– Safety factors are there to flag possible problems Dosimetry uncertainties

– LHCb applies a factor 2– Others trust the dosimetry

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Testing Procedures

Testing electronics against radiation is complex– Tests conditions– Type of radiation– Biasing conditions– Annealing conditions

Better to base the tests on standard methods– ESA or MIL

Tests to be done several times– Pre-selection– Qualification of production lots

Experiments policy– ATLAS has defined some testing procedures– LHCb is pointing to them

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Results book keeping

Very desirable to have a standard radiation test report– To be sure that nothing is forgotten– To be easily reviewed and shared

A central place to store them is also desirable– To share the results between different groups

A data base accessible through the WEB is available– Developed by Chris Parkman for ATLAS– Adopted by RD49 i.e available for all experiments– Not sufficiently used

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Management

Two main types Radiation Hardness treated centrally

– One responsible for the experiment, One per sub-system, one per electronics entity (boards)

– Common rules for everybody– Common rules for the reviews– Preselection and qualification processes

Radiation Hardness treated by each sub-system – As an extra specification– No specified rules

ATLAS is using the first model, CMS the second one

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Interpretation of the results

Assuming a perfect procedure has been applied we should know when launching the production– How the electronics will behave in time with respect to

cumulative effects– What is the cross-section of SEE

The agreement for starting the production still needs some extra thinking– Can we have some maintenance for cumulative effects

» Physical access and financial capability

– Can we overcome the effects of SEE» In the design in implementing special techniques (e.g

redundancy)» In the system in implementing reset sequences or continuous

monitoring of the key data» In the power supplies for latch-up detection and automatic

switch off» In just living with them (e.g data corruption)

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Interpretation of the results –cont.-

The most difficult point concerns the SEE as this is a statistical process and that it is not needed to have high doses to be disturbed

The experience that we have got in ATLAS is that there has not been a single SEE test not leading to problems

FPGA are particularly sensitive– LHCb has issued a rule for using only antifuse FPGA and triple

redundancy– Several systems are going to use ASICs or Gate Arrays instead of

FPGA (ATLAS Liquid Argon and Muon trigger) or are moving the complexity at safer places (ATLAS Muon tracking, LHC machine)

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A few examples of difficulties

ATLAS Liquid Argon electronics and power supplies

ELMB Low voltage regulators

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Liquid Argon Electronics

Radiation Tolerance Criteria for LAr– TID = 525–3500 Gy/10yr – NIEL = 1.6–3.2 1013 N/cm2/10yr– SEE = 7.7-15 1012 h/cm2/10yr

Electronics in crates around the detectorG’dammI am good!

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Liquid Argon Electronics

1 responsible per board– FEB (1600 boards) : J. Parsons– Calib (120 boards) : N seguin– Controller (120 boards) : B. Laforge– Tower builder (120 boards) : J. Pascual– Tower driver board (23 boards) : E.Ladyguin– LV distrib ( ) : H. Brettel– Purity (?) : C. Zeitnitz– Temperature : ?

1 representant for power supplies– Helio Takai

1 representant for optical links– Jingbo Yee

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Liquid Argon Electronics

First tests made with COTS were very disappointing…

Decision to avoid them as much as possible

A lot of extra design work

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Liquid Argon Electronics: FEB

10 different custom rad-tol ASICs, relatively few COTs

DMILL

DSM

AMS

COTS

32 SCA 16 ADC 8 GainSel

1 GLink1 Config.2 SCAC

1 SPAC

1 MUX32 Shaper

1 TTCRx7 CLKFO14 pos. Vregs+6 neg. Vregs

2 LSB

32 0T

128input

signals

1 fiber to RODAnalog

sumsto TBB

2 DCU

TTC,SPACsignals

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Liquid Argon Electronics: ASICs

LARG Chip Techno Status HAMAC-SCA DMI LL Production on- going SCA Controller DSM Working prototype Gain Selector DSM Working prototype BiMUX DMI LL Production on- going Clock FO DSM Prototyped DAC DMI LL Production on- going SPAC slave DMI LL Prototyped OpAmp DMI LL Production on- going Config. Controller DMI LL Ready for production MUX DMI LL Redesign Calibration Logic DMI LL Ready for production

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Liquid Argon Electronics

Tracking of the status of radiation hardness of components

Still possible to forget a component– E.g opto-receiver of the TTC

Complete crate with radiation tolerant electronics to be ready in 2003

Part Responsible for RHA

Pre-selection Qualification

AD9042AST CMS completed by CMS. Reports missing.

to be done by CMS (date?)

AD8042AR LARG/FEB Group

SEE and NIEL test completed (150 MeV protons); reports missing. TID test to be done separately.

to be done (date?)

HDMP-1022 LARG/Links Group (SMU)

completed by LARG/Links Group (SMU); reports missing.

to be done by LARG/Links Group (SMU) (date?)

Optical Transmitter

LARG/Links Group (Taiwan)

completed by LARG/Links Group (Taiwan); reports missing.

to be done by LARG/Links Group (Taiwan) in March-April 2002

MC10H116D LARG/FEB Group

SEE and NIEL test completed (150 MeV protons); reports missing. TID test to be done separately.

to be done (date?)

AD8001 LARG/FEB Group ? CMS ?

completed by Tower builder. to be done by FEB or by CMS (date?)

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Liquid Argon Power Supplies

Each crate requires 3 kW 4 kW DC-DC based power supply has been designed

– To be located inside the detector– 300 V DC input

2-3 years of measurement and development to understand and solve radiation problems

Most severe problem was SEB (Single Event Burn-out)– SEB destroys the MOSFET.– SEB depends on how the MOSFET is biased and therefore on

the topology of the power supply. Resonant circuits for example are particularly bad for SEB because VDS depends on the load

– The second effect that one has to be aware is the asymmetric nature of the SEB cross section. When particles hit from the drain side it can be significantly larger than from the gate side. This has been determined for ~6 different power MOSFET.

Test Goal Achieved

Ionizing Radiation 10kRad 300kRad

NIEL 1.15x1012 5.0x1013

Hadrons E>20MeV 5x1011 SEB<1x10-16 cm2

SEL<7x10-13 cm2

Magnetic Field 20 G 120 G

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Liquid Argon Power Supplies –cont-

NOT because of loss of power supplies! SEB and SEGR are potential hazards that can short

converters and failure in protection systems could lead to instant fire hazard. Power supplies are rated to 4kW.

Note that they are located in places that are inaccessible in case of emergency.

Ionizing radiation damage leads to loss of regulation and potentially loss of electronics.

Magnetic Field saturates transformers and supplies ceases to work with possible short in the input stage.

Unknown background is the one that will do the job. Currently SEB for pions, kaons are unknown but we know that SEE induced by pions can be 5x larger than neutrons. Production of fragments in packaging, etc have not been considered.

Still a Lot of Concerns !!

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Embedded Local Monitor Box (ELMB)

Basic element for the slow control of the ATLAS muon chambers

Radiation constraints (including safety factors)– TID : 8.4 Gy in 10 years;– NIEL: 5.7E11 n/cm2 (1 MeV eq.) in 10 years;– SEE: 9.5E10 h/cm2 (>20 MeV) in 10 years.

CAN SAE81C91

3.3 to 5.4V option?

VSup

50 mm

67 mm

DIP-SWIDBAUD

ISP

OPTOs

Voltage regulators

ATMELmicros

CAN Tranceiver

ADC AnalogMUX

REF

Logic

Latch

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ELMB –cont-

Comparison GIF

99

104

109

114

119

124

0 10 20 30 40 50 60

TID (Gy)

Ch

an

ge

in

cu

rre

nt

(%)

ELMB3 ELMB5 ELMB6

GIF ELMB3 0.48 Gy/hcontinously

GIF ELMB5 0.45 Gy/h continously

ELMB5Reprog37% duty cycle~0.17 Gy/h

GIFELMB60.09 Gy/hcontinously

TID results: one of the processors is sensitive (although well within the requirements)

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ELMB –cont-

SEE results: requirement for an automatic power on-off

Care being taken for the use of the RAM– “SEE resistant” software

Requirements ELMB Result

6250 21 6

1429 5 1.4

45 4 1.2

0.0083 (0) (0)0)

for 9.5*1010 h/cm2

Soft SEE

Category

Hard SEE

SEE upsets forSEE upsets for3.3*1011p/cm2

automatic recovery

software reset

requiring power off-on

ELMB ResultsELMB Resultsfor 9.5*1010 h/cm2

Requirements ELMB Result

6250 21 6

1429 5 1.4

45 4 1.2

0.0083 (0) (0)0)

for 9.5*1010 h/cm2

Soft SEE

Category

Hard SEE

SEE upsets forSEE upsets for3.3*1011p/cm2

automatic recovery

software reset

requiring power off-on

ELMB ResultsELMB Resultsfor 9.5*1010 h/cm2

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ELMB –cont-

Additional work going on– Current design has two processors. Next will have

one only. Improved TID response– Software to counteract the SEE being improved

Production organisation– Qualification of batches of components

Safe definition of where the ELMB can be used:– TID > 40 Gy for protons – NIEL > 5*1012 neutrons/cm2– SEE >> MDT requirements

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Low Voltage Regulators

Radiation tolerant low voltage regulators (a few krad and a few 1012 n.cm-2) almost impossible to find– One from Intersil may be OK for ATLAS calorimeter

but costs too much RD49 has initiated a development with ST

Electronics– Positive and negative adjustable regulators– Very hard (several Mrad)

Positive version available Negative version had a bug

– Has been corrected– A few 100’s available in November (not lifetime

qualified)– Quantities in January-February 2002

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Summary-Conclusions

Radiation Hardness is still an issue in the experiments– SEE is a major concern

The knowledge of the problems has reached a reasonably good level in the community thanks to tutorials organised either in the experiments or by RD49

The radiation hardness assurance approaches are not identical in the experiments (or in the machine)

Book keeping is a key issue if one wants to benefit from the work done– The existing data base should be more widely used– It requires a effort of documentation from all of us

» Tests descriptions» Results