TRT (and a bit beyond) – Overview

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TRT (and a bit beyond) – Overview

TRT DaysJune 25 2013

A.Loginov, A.RomanioukFor the ATLAS TRT Collaboration

TRT Days, June 2013 2

DQ @ 99.8% in pp @ 2012• TRT Desynchronization

– [206248: 1 -> 206248: 533), elog– ROD firmware issue

• Reverted to the before-the-TS settings to resolve the issue

• HV Crate issues– [215027: 1 -> 215027: 268) : (TRT_NODATA_06, HV Crate in the barrel tripped

and had to be replaced)– [215414: 1 -> 215414: 163) : (TRT_NODATA_06, HV Crate tripped and had to

be replaced)– An environmental / external issue?

• Lacquered contacts in the end of last year, no problems since then

• DQ @ 100% in other runs, despite gas leaks and minor problems– Got a number of tolerable defects (TRT_BADGAS_01, TRT_BADGAS_02)

• Number of dead channels Is stable– within declared 2.7% (2.4%)

https://atlasop.cern.ch/elisa/displayThreadID.htm?threadID=210465&display=1&expand=210524


TRT DAQ in Run 2 – Goal: 100kHz trigger rate @ high occupancy– Bottlenecks:

•Front End to ROD bandwidth– Changing from full readout mode (27 low threshold bits) to reduced mode (23 low

threshold bits) increases trigger rate limit from 89 kHz to 105 kHz (ongoing activity)– Dropping last 4 LT bits – minimal impact on tracking (not losing the leading age)

•ROD processing rate– Event processing time proportional to occupancy due to on-board compression– Solutions include:

» Increasing clock speed from 80 MHz to 100 MHz on compression chip increases bandwidth» Hard-coding common words to decrease occupancy that compression chip must process» Applying validity gate on all words to decrease overall occupancy

•ROD to ROS bandwidth– Extrapolation to high lumi indicates that this is not limiting factor– Optimization of compression table reduces load – Monitoring of fragment size in place


Other TRT DAQ Issues• Increasing number of automatic resyncs during stable

beams at end of 2012 (order once per hour)– May be caused by power instabilities in VME crate which affect

sensitive components on ROD – Crates will undergo upgrade to increase current limits on relevant

lines • Maraton LV power supply upgrades (connector upgrade and

internal wire replacement)– Rolling upgrade to be completed during LS1, currently on-

schedule• Sufficient number of spares


eFastOr• Upgrade the existing FastOr trigger– https://cds.cern.ch/record/1516518– Physics motivation: HIP (monopole, Q-ball…)

• Potential timeline

https://cds.cern.ch/record/1516518


High Voltage

• February’2012: crates 003 (tripped), found that crate 004 had similar damage– Crates in the same rack – external factor?– To solve the problem: HV pins were covered with lacquer

• November’2012: Two issues caused by the same problem– Small debris of Al / dust found on the board– The issues got addressed (cleaning + protection lacquer), no

problems since then• Have 3 spare crates (1 x USA15, 2 x SR1)– And a few spare HVM modules

• Lacquer all the contacts to prevent similar issues– Ongoing activity


Active gas issues

• Excellent work of TRT active gas team– Despite all the leaks, the DQ didn’t suffer

• TDR specs: Xe leak @ 100 l/day– Before early 2012 the leaks were a few times smaller– By the end of 2012 we got ~200 l/day

• Leaks– Stress corrosion enhanced by Ozone presence– Strategy discussions since few months, study insitu /

repair during last few weeks• Repair work finished


Leaks• Repaired whatever was accessible– Both EC Side C / Side A

A1 crack along the pipe (PPF1 connector)

PPF1 brackets

Detector connector

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Electronics

Gas manifold

Gas

Straws/radiator

Electronics

Gas manifold

Gas

Straws/radiator

Gas IN

Gas OUTPEEK pipes shown in pink

Places of stress

EC wheel type A connectivity

TRT Days, June 2013


What’s then?• Will do our best to start running in 2015 with in Xe

mode only– Work is ongoing to automate active gas system operation• 80 channels to regulate• Adjustments of leaking channels have been done manually so

far• Can we stabilize leaks at 150 l/h?

– Ar affects quite a few physics aspects (TR!)• Had a combined Ar / Xe mode of operation in 2013 to study• Will post a note summarizing this in the coming days

– Electron ID, triggers are affected…

– What about tracking with Ar?


Xe vs Ar: Tracking• Resolution (tracking @ Ar is not affected)– Run 218391: Ar/CO2/O2 @ 80/17/3, HV @ 1365 V– Barrel: 0.123 mm (Xe) / 0.131 mm (Ar)– EndCap: 0.123 (Xe) / 0.127 (Ar)


Active Gas System: Ar studies• Studies with both the TRT and at test stands– measurements of signal shapes for different gas mixtures and

ASDBLR shaping options (report by X.Poveda link)• Main conclusion: afterpulses at 100 ns after the main pulse are

observed if Xe shaping has to be used, more pronounced for high HV values

– Different mixtures, HV settings (report by K.Vorobev link)• Study stability, gas gain limitations etc

https://indico.cern.ch/getFile.py/access?contribId=6&resId=0&materialId=slides&confId=236045



TRT DCS• Very successful operation in Run 1

– Quickly prepared tools for Xe/Ar combined running• Massive upgrades planned for LS1 (report by E.Banaś, Z.Hajduk,

J.Olszowska link)– As a part of general DCS upgrade (windows -> linux etc)

• Need to develop some TRT specific tools• Constraints from central DCS

• Overall strategy for the LS1 upgrade– Fully reversible upgraded <-> old DCS– All the time most of TRT hardware is under control

• Also will upgrade GGSS (report by B.Mindur link)– Standard PCs, exchange of all existing internal PCI cards to internal ones, can

replace straws if needed• All proposed HW components are linux/windows compatible

– Need to rewrite the core of GGSS so that it runs on linux




LHC: Run 2


ATLAS: Run 2• Many discussions on how to operate ATLAS– See the “ATLAS Post-LS1 Operation Workshop”

https://indico.cern.ch/conferenceDisplay.py?confId=256916

• Fewer shifters–More information to look at (muon system will be

completed + IBL + etc)– Better tools / more uniformity (or more headache during

the operation)• Updates of the CR layout, calibration procedures,

shifters’ training etc etc etc–Will be (again and again) asking for inputs to make sure

that TRT is properly taken care of by the shift crew




Summary• Run 1 was success– Thanks to all the expertise and dedication of the TRT team:

the team made the TRT a great detector!• Will have things ready for the Run 2– DAQ updates: get ready for high occupancies and rates

(ongoing)– Hardware and firmware improvements

• Improved Maratons, HV crates, etc– Active gas system

• Possible repairs are (almost) done, have more work ahead (automation and optimization)

• Studies of Ar mixture, possible modes of operation are ongoing– eFastOr is progressing well


TRT BBQ this WEDNESDAY @ 18h• BBQ site @ Prevessin:

– Map @ https://maps.cern.ch/mapsearch/mapsearch.htm?no=[9401]– Sign up @ http://doodle.com/wft6cuha4gxreu9y

https://maps.cern.ch/mapsearch/mapsearch.htm?no=%5B9401



http://doodle.com/wft6cuha4gxreu9y




Few backup slides


Active Gas System Plans• Possible to stabilize most leaks. Need to control 2

parameters:– gas flow in a leaking channel

• Remote flow regulation?– pressure in the TRT outlet (pump inlet pressure)

• Need 0.005 mbar accuracy (with the original requirement of 1 mbar)– precise pressure sensor– additional buffer for pressure sensor– pump input resistance regulation– cavern-USA pressure difference feedback to the pump operation

• Ar mixture blow out setup– Have a temporary setup operating for the pPb running

• Automate N2 removal (because of the TRT leak)


TRT Performance in Heavy Ion runs

• Excellent performance even with extreme occupancies (plots taken from link)



TRT DCS: PCs, Systems and HW… A “simple” drawing


Xe vs Ar Saga

• Put Ar in few parts of the detector (both in barrel and EC)– Prepare tools / Learn from the operation / Save Xenon– Vary gas mixtures / HV settings to study operation

• Studies with the TRT and on a test stand

• Argon shaping issue– Mis-stuffed resistors in a fraction of EndCaps (and hence bit problems)– Under studies

• Xe->Ar => electron ID is affected– Argon can be operated with larger gain than Xe– Electron Drift-time for Ar is shorter than Xe– Transition Radiation absorption down by ~10 compared to Xe– Need to understand the consequences


Xe vs Ar Saga: PID• This is under study, but here are few points below– No TRT seeding hits for conversion finding => CPU time for

conversion finding increases by a factor of 10• Overall, back tracking is affected

– High-PT electron trigger affected• Increase by 20-30% without HT hits information @ HLT

– Jpsi -> ee trigger affected• Rates increase by a factor of 2

• So…many things to try– Find / repair the leaks @ EC – AND Cheaper Xenon (30% lower price) from the Russian supplier?– AND Optimize performance / study combined Xe / Ar operation

effect on physics / etc


Leak Hunt and More: few Dates

• 8-13 March– ID End-plate leak search (CO2)

• 18 April – September– TRT gas leak repair work• Developing tools…

• 18 February – November 2014– Active gas racks test / modifications etc– Replacements of Maratons– PP2 replacement/tests/repair

TRT (and a bit beyond) – Overview

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