content: t0 status t0 sor, eor, busy issues other running issues high background data taking

Tatiana Karavicheva, Review meeting. CERN,27-06-2012

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T0: Current detector issuesand LS1 plans

T.Karavicheva,V.Kaplin,A.Kurepin, A.Maeskaya,

W.Trzaska on behalf of T0 group

T0 review 27 June 2012

Content: T0 statusT0 SOR, EOR, Busy Issues Other Running Issues High Background Data TakingRunning in p+AT0 LS1 Activities Other TC Questions

2Tatiana Karavicheva, Review meeting. CERN,27-06-2012

• 100% of channels are working (without aging)

• T0 is in a good shape, very stable during p-p physics

• Precise start signal for TOF

(time resolution ~ 40 ps)• Luminosity measurement

Trigger functions (on-line): • Rough vertex position (OTVX)

resolution of vertex cuts 0.6 cm;

Performance during the pp 2012 run

T0 status


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T0 SOR, EOR, Busy Issues SOR :

T00::dcsSorCommandError => the origin of “real” SOR problems not solved …. But rare runs: 178513, 1785100

EOR: Hardware Error T00::hardwareError (T0 incomplete events lead to backpressure

and TPC busy )runs: 181984, 177858 , 177620 , 177612, 177167, 177166,177120

It happens when interaction occurs close to ORBIT RESET.

New DRM firmware will be installed to solve this problem and also Sync events.

EOR: Busy at SOR T00::detectorBusy

runs:177982, 177981, 177980, 177957, 177956 , 177165, 177155 –Ok after FanIn/FanOut module re-initialization


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Other Running Issues

One amplifier from A-side was broken, spare amplifier was

installed . Ok Last time when we measure L0 signal with A.Jusco in the

pit (on CTP scope outputs), the width of L0 signal was 18ns. During the TS access we measured the signal on the output of T0 FE, and we see 25ns. I.e. the width of the signal seems to be shortened by L0 lvds cable connecting to L0 input to CTP. The length of L0 cable is 45m. Cable equalizers installation is under discussion (should be done now during TS). ->Done last night.

QTC (Charge to time converter) used for amplitude slewing correction. The module has the problem with

high interaction rate (the problem is under investigation) OTVX range is ±30 cm (pb-pb it was set ± 10 cm)

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V0 total rate Data taking T0 TimeZero/Lumi

>400kHz no save

~400kHz PHYSICS_2 (PHOS,EMCAL,T0,SDD,SPD,SSD)

(test physics )

- Trigger Detector- Luminometer- with readout

Luminosity measurement and T0 data

~250kHz PHYSICS_1:: (without TOF) - Trigger Detector- Luminometer- as readout detector

Do not need the best timeResolution without TOF

~150kHz PHYSICS_1: all available detectors

- Luminometer- As trigger & readout detector

the best timeresolution needed for TOF


High Background Data Taking from 14.06.2012 to TS-2

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T0 trigger electronics could run now with the bunch repetition rate up to 40 MHz for L0 inputs , luminosity monitoring ;

But the maximum anode average current according to the PMT datasheet is 2 uA


V0 rate [kHz]

T0 PTM rate(nominal HV)kHz}

Anode current [uA]( width of signal ~10 ns)

How long T0 can be switch on?

>500 ~100-200 >2,1 Less than 0.5 hour

500 ~70 ~2,1 Less than 0.5 hour

350 ~ 40 ~1.2 Long time

250 ~ 32 ~0,96 Long time

Principle issues related to T0 rate

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T0 PMTs We use Russian PMT-187 (R3432-01 was the prototype).

R3432 had the maximum anode average current 10 ua

For T0 detector PMT’s selection were made.

Probably the anode average current specified

for PMT-187 was made with a large supply

At T0 lab test going to READY at higher p+p V0_tot rates (laser test result: real width of the signal is ~ 4 ns,

200 kHz per PMT is OK during 5 days)

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p-A running• p-Pb interaction rates of up to 200kHz can be expected i.e. equivalent p-p

rates of 700kHz.

• At this moment (1380 bunches 1.4x1011 p/bunch) we have V0tot rates of up to 700kHz at the beginning of the p-p fill.

T0 works stable with V0tot rates of up to 400kHz

( it is switched on at the beginning of the fill for short time- OK).

Take into account the shorter width of the signal we estimate

max. V0tot rates as ~800 kHz

What will be OTVX range for p-A (p-p ->±30 cm or pb-pb-> ±10 cm)?

(install second module to generate second OTVX?)

. Tatiana Karavicheva, Review meeting. CERN,27-06-2012


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LS1 Major Activities (1)

• The main expenses for the upcoming years will cover the exchange of the light sensors (PMT) during the major shutdown of LHC. We are currently negotiating the price and specifications with Hamamatsu (V0 aging?). The upgrade will remedy some of the problems with after-pulses and noticed deterioration of the sensors after the major He leak to the system resulting from the 19 September 2008 incident.

• Spares are required


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ALICE trigger upgradeAfter LS1 (not yet fixed)

Mechanical implementations-if ever possible to move T0,V0,TOF FEEs ..?-where to install (contact ALICE technical coordinator)inside magnet, close to CTP (C-side)?necessary space for all FEE and trigger units rack? …


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• Modifications of the mechanical support to accommodate new PMT tubes (start from A-side) and attempt to reduce the length of the detector units to make space for the improvement in the muon detection system (MFT) of ALICE (under discussion).

• There is also an urgent need to modify the trigger electronics and locate it inside of the L3 magnet to significantly reduce the cable delay. To conform with this demand by ALICE new electronic modules have to be build (?).

• repair of replacement of PS, Crates and R/O modules based on the experience accumulated so far.

LS1 Major Activities (2)


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TC Questions

• Cables from CRs to Cavern?

no• Hardware Interventions?

see list above LS1 activity• Hardware interlocks ?

no• Cooling - upgrades and necessary improvements?

Now not used. If the scheme of installing our electronics inside of the L3 magnet will be realized, we would need a cooling system for the racks and racks that work in B of up to 0.5 T

• Gas – upgrades?

Not used

Thank you for your attention!

Tatiana Karavicheva, Review meeting. CERN,27-06-2012 14

content: t0 status t0 sor, eor, busy issues other running issues high background data taking

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