radiation monitoring: what do we have and what do we need?

Radiation monitoring: what do we have and what do we need?M. Calviani, M. Brugger, P. Peronnard, J. Saraiva, G. Spiezia (EN/STI)

R2E/Availability Workshop October 2014

M. Calviani: Radiation monitoring - R2E/Availability Workshop

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SummaryUse of the monitoring systemBrief summary of Run I experienceRadMon development Injectors monitoringRequirements from usersWhat would be needed for Run II

October 2014


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What do we use the monitoring for

Measurement of radiation levels in the machines:High energy hadron fluence (HEH)Total ionizing dose (TID)

1. Understanding of the radiation field in the tunnel and shielded areas and support for simulation extrapolation

2. Important service to equipment groups for failure analysis

3. Input/requirement for equipment design

October 2014


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What would happen if don’t have it

Cannot correlate equipment failure with radiation

levels risk of changing equipment w/o solving the

problem

Cannot anticipate need for equipment upgrades –

rad-tolerant

Cannot study radiation impact of changing

operational parameters

Cannot dissociate the possible radiation source

Limited info on eventual radiation quantity

responsible for degradation (TID, NIEL, HEH)October 2014


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Types of detectors employed

October 2014

• RadMons/RadFETs (HEH/cm2, Gy(SiO2))• Radiation levels close to equipment of interest, non

necessary “standard” locations• Time profile available

Dedicated detectors

• BLM (Gy – cumulated)• Provide loss distribution (dynamic view)• Total dose

Other detectors with high granularity

• TLD/HLD (Gy – cumulated)• Integral dose at the location of interest

Passive dosimetry


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LHC RadMon coverage

October 2014

LHCCritical

areas (UJ, RR, US, UX, RE, UA)

DS and start of ARC

LSSExperiments


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RadMon locations in DS/ARC

October 2014

DS/ARC (from cell 7 to 20)

RadMon are placed

below the interconnect

between the last MB/MQ

of a given cell

Equipment below

MB/MQ!

MB MB MQ

MB MB MQMB

MB

MBcell i cell i+1

cell i cell i+1

Dedicated LHC-MD extraction of an operative ratio between BLM

dose and expected HEH from RadMons = ~1 SEU count/mGy

Tunnel equipment (QPS, CRYO, BLM or EPC)


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Experience from Run I (1/5)Nice summary of Run I observation is

available here Radiation levels summarized with the use

of different types of detectors (RadMons, BLMs, FGCs, etc.)

October 2014

https://cds.cern.ch/record/1551923?ln=en


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Experience from Run I (2/5)Lesson: Important to follow-up machine

operational parameters (TCL/RR)

October 2014


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Experience from Run I (3/5)

October 2014

Lessons:BLM analysis fundamental for the DS/ARCWhen BLM/RadMon available, good

agreement between them

Point 4


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October 2014

Very important to follow-up radiation monitoring following operational variationsSometimes just scaling is risky...

Predictions2012

Observations end 2012

Decreased: TCL closed

Increased: tight collimators

Increased: higher cum. lumi


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October 2014

We should not forget the p-Pb and Pb-Pb runs Due to the Bound-Free Pair Production (BFPP), even for

short runs, radiation levels can be up to 5 times those of a “standard” pp run

DS cells most affected

~7 months

~3 days


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Open points in view of Run II

October 2014

25 ns operation uncertainties:Evolution of beam-gas levels during 25 ns

operation still to be fully clarifiedDuring Chamonix 2012 it was stated that

pressure will not increase more than 2x with respect to 50 nsHowever – experience showed that

pressure variation depends strongly on real operational parameters

Still an open point


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Open points in view of Run IILHC Point 4 and Point 6UX45: radiation levels in 2012 higher than

expected from 2011 triggered TE/CRG relocation activitiesHow the situation will evolve with 25ns

operation?UX65: still calm, as no special equipment

might increase the beam-gas interactionMonitoring has been improved

October 2014


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RadMons developments

October 2014

During LS1 more than 100 RadMons have been installed in machines450 in total Injectors, target area, experimental areas..

LHC: ARC P1-2-5-8 + relocations for R2E

RadMon v5 LHC

RadMon v6 Experimental areas (n_TOF, AD) Injection lines


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RadMons development Features of v6:

Remote configurability

Self-diagnostic

Radiation resistance 3 times higher

New sensors

October 2014

Advantages with respect to v5:Resolution improved by a factor of 10Reduced number of tunnel access to change

settingsLonger life-time


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RadMons development Overall resolution improvement – factor of 3 to 10 TID limit 3x times larger

October 2014

Sensor Sensitivity*Resolution

Range(Prev) (New-V6)

Fet100 50 rad/mV

300 rad

20 rad

1Mrad

Fet100Bias

14 rad/mV NA 6

rad 0.4

Mrad

BPW (3)

4·109

n/cm2/mV3·1010 n/cm2

6·109

n/cm2

1013

n/cm2

BPW(1)

1·1010 n/cm2/mV

7·1010 n/cm2

2·1010 n/cm2

5·1014 n/cm2

Toshiba 2·106 n/cm2/count

2·108 n/cm2

2·108 n/cm2

2·1011 n/cm2

Cypress 1.5·105(8·105)

n/cm2/count NA1.5·107(8·107)

n/cm2

4·1011 n/cm2


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BatMon – versatile instrument

October 2014

Where versatile installation is requiredE.g. PLC failures in LHC Point

4 and 6 requiring urgent checks

1. Validation of the relocation strategy

2. Measure R-factor in critical area via voltage change

3. Measurement requests for machine studies


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Injector’s radiation monitoring

R2E up to 2012 concentrated on the LHC, in order to mitigate radiation effects for Run 1

However issues are present in the injector chain as well, simply “less visible”

In order to guarantee machine availability also in the future, it’s important to dedicate resources on it as well

Info available at http://r2e-injectors.web.cern.ch/

October 2014

http://r2e-injectors.web.cern.ch/




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Issues with present radiation monitoring

October 2014

BLMs (ACEM – Aluminum Cathode Electron Multipliers)

Saturation in critical areas, of no use for loss distribution Not calibrated to dose Ongoing campaign to install LHC-type BLMs in PSB (not

PS) important to be able to evaluate cumulative dose SPS ionisation chambers – low granularity (1 every 32

meters) HLD (not online system) Radiation Surveys

Depends on activation, cannot directly relate to rad levels for equipment


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PSB example (RS vs. HLD)

October 2014


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PS example (RS vs. HLD)

October 2014


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Injector monitoring - future

October 2014

Requirements: Appropriate BLM coverage with sufficient granularity in

PS/PSB/SPS RadMon installation extension Passive dosimetry

Important to follow-up this measurements and improve analysis speed


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Requirements from users

October 2014

A weekly report was published during 2011/2012, providing radiation levels in critical areasService to users in support of the RadWG


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October 2014

However: It was a manual system, requiring full support

from the MCWG teamDifficult for users to understand levels if

equipment away from the detector location interpretation/extrapolation from MCWG team needed

Loss scenarios can modify radiation levels distributions

Investment should be made to try to automatize it!


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October 2014

An attempt of realizing an online system was performed in collaboration with EN/ICE

Dedicated support of EN/ICE requested to revise the system

LHC R2E Dashboard

Complex to maintain, since as of now data requires manual manipulation


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What will be needed for Run II

1. Reactivation of the MCWG analysis team

2. Dedicated support from the BLM team to provide

cumulated doses on a weekly basis

3. RadMon team to continue support the detectors

4. Continue keep track of the detectors inventory

(Layout DB?)

5. Support of the groups for fast reporting on

equipment failures

6. Continue improving on radiation monitoring in the

injectorsOctober 2014


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Fundamental to follow-up on these, at the moment done manually!


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ConclusionsMonitoring is and will be an important

aspects of the R2E (and Availability) activities In the LHC and in the Injector chain It is now required as a service rather than

studiesPowerful instrument that allow providing a

service to equipment owners in understanding radiation-related failures

October 2014

radiation monitoring: what do we have and what do we need?

Documents

followup radiation monitoring

radiation field

monitoring systembrief

equipment failure

equipment groups

equipment designoctober

blm dose

pbpb runsdue