Status report on studying and Status report on studying and preventing ageing in the LHCb preventing ageing in the LHCb

OTOT

S.Bachmann (on behalf of the LHCb OT group)

Physikalisches Institut Heidelberg

Many thanks to A.Pellegrino and U.Uwer for providing material!

LHCC Referee Meeting, Sep 24, 2007

Outer Tracker Aging Investigations on Outer Tracker Aging Investigations on Ageing:Ageing:

StatusoUnderstanding ageing:

Epoxy (Araldite AY103) has been identified as cause for ageing.

oPreventing ageing:

Main line:

Long term flushing + heating of modules.

More studies on:

Adding new component to gas, i.e. oxygen (beneficial) and CF4 (non-beneficial).

HV training (inspection of wire after training, long term).

Detailed study of chemical properties of AY103/HY991.

Glue Tests in Mini OT Modules:Glue Tests in Mini OT Modules:Constructed mini OT modules to test effect of different glues

o 32 channels, 1m longo materials and procedure in so far as possible from mass production

Could consider constructing a real OT module with different glue (e.g. Tra-Bond 2115 epoxy, from TRA-CON) to test our ability to produce modules not affected by the ageing problem

o availability of components (F or S module?)

Araldite at straw entrance:Araldite at straw entrance:No araldite used:No araldite used:

Test module (straws):480 hrs, 20mCu

Finding the culprit for ageing using Finding the culprit for ageing using an openable test chamber:an openable test chamber:

Glue Tests in Openable ChamberGlue Tests in Openable Chamber

Normal F-module:20 hrs, 20mCu

Openable chamber:17 hrs, 2 mCu

Gas flow

Glue Tests in Openable Chamber Glue Tests in Openable Chamber (cont’d)(cont’d)

Openable chamber:17 hrs, 2 mCu

Gas flow

o Irradiation damage related to gas flow

• Pollution transported

o no ageing if glue is removed

out-gassing of AY103/HY991

Effect of long term flushing:Effect of long term flushing:

Taken from PhD thesis T. Haas

Exponential to black dots

c = 18.3 m3

c = 22.6 m3

c = 15.7 m3

cVole

Note: All detectors have been installed and continuously flushed since

November ’06 (C-side) and June ’07 (A-side)

• A warm-up of the modules (10 days at 40oC while being flushed) leads in many cases to additional improvement.

12% 10% 14% 10%

43h 112h

Before heating

After heating

20h 90h

source

Effect of heating:Effect of heating:

• Summary of the heating of nine modules (taken from PhD thesis T.Haas)

Preparation of possibility to warm-up the modules

Bar to protect the modules

Electrical Heating blankets:

-4 blankets per side

-8 blanktes per C frame

Avoid heating of the vertical C arm

5950

475

985

475

5000

Heating area

First Prototype

2 point regulation

Temperature

sensors

Uniformity test in vertical position:

2 blankets on mini C frame w/ 4 modules

Measured between module & blanket

Measured between modules

Temperature results in vertical position

Module length

Heat sink at bottom

Larger heating zones also work

Tnominal ~40 oC Tnominal ~40 oC

2oC

2oC

Installation at the pit

Lessons learned from prototypes:Lessons learned from prototypes:

5160

520 5202060 2060

•electrical and mechanical design ok

•homogeneous warm-up of a complete frame possible

•account for possible heat sinks located at the upper and lower C frame arm Modification of the heating zones:

•Still to be checked that no heat is spread to the vertical arm of the C-frame (1st warm-up test is situ planned after LHCb Magnet test)

Monitoring ageing in situ:Monitoring ageing in situ:Module Scanning Tool for ageing-test in situ is ready for installation (using 90Sr radioactive source(s))

Monitor evolution of module performance under continuous flushing

Give Feed-Back about heating Monitor long-term effects during regular beam operations (tool “parked” out of acceptance, usable during access)

C-Frame Warm-Up StatusC-Frame Warm-Up StatusStatus

oA full set of blankets (improved design) has been ordered

• 1st blanket ready, being checked at Heidelberg, test at LHCb after Magnet Test

oExpect delivery of remaining blankets by end of October

oControl system (including safety interlocks) being worked on Monitoring

oPrepare ageing-test system to be operated in situ to (sample) check results of warm-up

• Scanning tool being built

o During 1st warm-up, careful monitoring of the mechanical clearances that could be affected (e.g. module supports)

• special attention to the temperature monitoring in the vicinity of the RICH2

C-Frame Warm-Up OutlookC-Frame Warm-Up OutlookRealistic (pessimistic?) scenario:o fully operation from the beginning of Novembero serial operations (one C-Frame at the time)

Side C

Side A

Backup slides

Update on Ageing Studies:Update on Ageing Studies:Although attention focused on preparations for warming-up and monitoring tools in situ, a number of ageing studies was carried on during the summer:

o Further warm-up tests on the bench with F and S modules• (see summary talk(s) from September 2007 LHCb Week)

o Resume studies with added O2 to gas mixture

• (see summary talk(s) from September 2007 LHCb Week)

o Further investigations of treatment with high-currents (direct and reverse polarity)

• wire inspection after treatmento Studies with openable test vessel to establish origin of the problem

o Detailed studies of the AY103/HY991 properties (degree of polymerization, out-gassing, etc.) in cooperation with the CERN chemistry department (P. Chiggiato, R. Setnescu, I. Sorin, B. Teissandier, D. Letant-Delrieux, …)

• studies in progress, joint report in preparation

Cure – Negative HV Training:Cure – Negative HV Training:

Trained straws

Before Training

~60 hours at -1480 V repairs the damage previously inflicted by

irradiation

Cure – Positive HV Training:Cure – Positive HV Training:Gas flow

340 hrs

After HV After HV

340+350 hrs

2nd HV training

1st HV training

3rd HV training• ~20 hours at +1900 V repairs the damage previously inflicted by irradiation

• HV training repeatable

Wire Inspection after HV Training:Wire Inspection after HV Training:

11 Sep 2007

Recommendation of the Ageing Workshop panel:

1: not irradiated, trained

25/17

1: not irradiated, trained1: not irradiated, trained

4: irradiated, trained

12: new wire off the shelf

inspect wire after HV training to check that high currents have no “burning” effects on the anode surface qualityTook various samples of wire from openable chamber from the trained and non-trained region and from the irradiated and non-irradiate region, and compare with wire from new spool

No effect on wire surface from optical inspection (20 50

magnification)

Glue Tests in Mini OT Modules:Glue Tests in Mini OT Modules:Constructed mini OT modules to test effect of different glues

o 32 channels, 1m longo materials and procedure in so far as possiblefrom mass production

Could consider constructing a real OT module with different glue (e.g. Tra-Bond 2115 epoxy, from TRA-CON) to test our ability to produce modules not affected by the ageing problem

o availability of components (F or S module?)