CERN November 22, 2004 1W.H.Trzaska HIP Jyväskylä

T0 answers

Meeting with LHCC referees

CERN, November 22, 2004

CERN November 22, 2004 2W.H.Trzaska HIP Jyväskylä

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Vertex position (cm)

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High Threshold

Low Threshold

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Vertex Position (cm)

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Old TVDC efficiency plot

New TDR figure

New TVDC efficiency plot

r.m.s. = 3 cm

0 < width < 1.6 m

CERN November 22, 2004 3W.H.Trzaska HIP Jyväskylä

Important: 24 + 12 option for T0-A

CERN November 22, 2004 4W.H.Trzaska HIP Jyväskylä

How to translate physics into counts?

Contribute more

Contribute less

diffractive dominate Identified with

minimum bias

exchange of color neutral

objects

basis for comparison

between pp and HI

CERN November 22, 2004 5W.H.Trzaska HIP Jyväskylä

Detectors understand only counts!

What is the multiplicity distribution?

Where is the border line between:

•minimum bias

•semi central

•central collisions

CERN November 22, 2004 6W.H.Trzaska HIP Jyväskylä

Multiplicity distribution (Pythia)

30 mmT0-A & T0-C

Pythia's predictions are right (if properly interpreted)!

A case in point: Croesus, King of Lydia, asked if he should wage

war with Persia. Pythia replied: if you waged war

you’d destroy a great power. Croesus lost badly!

Pythia’a explanation: we meant your power, of course.

CERN November 22, 2004 7W.H.Trzaska HIP Jyväskylä

New simulations

What to make of it?

CERN November 22, 2004 8W.H.Trzaska HIP Jyväskylä

What if only one side of T0 responded?

• No T0 trigger!• Trigger&wake-up

from V0• No interaction

time on-line!• Can be calculated

off-line – Reconstructed

vertex (tracking)– Slightly lower

accuracy (~1.4 * 28 ps)

CERN November 22, 2004 9W.H.Trzaska HIP Jyväskylä

Decisions are needed:

• On radiator’s diameter– 30 mm – current baseline– 20 mm – proposed by T0

• On the number of detectors (T0-A + T0-C)– 12 + 12 (current baseline)– 24 + 12 (more electronic$ and rack Space)

• Decision needed by the end of 2004 to keep up with the milestones

CERN November 22, 2004 10W.H.Trzaska HIP Jyväskylä

Major milestones for T0• Nov 2004: Freezing radiator size• Dec 2004: Electronics Design Review (joint with V0)

• Feb 2005: Detector module frozen; mechanics PRR

• Sep 2005: Full chain readout test• Dec 2005: T0 Mechanics ready

• Feb 2006: Electronics PRR• Jun 2006: T0-C ready for installation in ALICE; installation of electronics at CERN;

tests of the installed T0-C• Dec 2006: T0-A ready for installation in ALICE; tests of the installed T0-A

CERN November 22, 2004 11W.H.Trzaska HIP Jyväskylä

New publicity for T0

• Our T0 detector was presented at IEEE in Rome in October 2004– submitted to

Transactions on Nuclear Science

• Two instrumental papers in preparation– Performance of PMT-187

– In-beam test results of the detector and electronics

CERN November 22, 2004 12W.H.Trzaska HIP Jyväskylä

New shoebox

• Has been redesigned as the result of June 2004 test at CERN:– Unaltered signal on direct output

• Time deterioration ≤ 2 ps (was 20 ps)• Amplitude ~1.0 (was ~ 0.71)

– Reduced PCB size– Reduced power consumption

• Performance has been tested in Jyväskylä (T0) and Lyon (V0)

• Further (minor) changes will be implemented– pulse clipping after the first stage OLDOLDOLDOLD

NEWNEWNEWNEW

CERN November 22, 2004 13W.H.Trzaska HIP Jyväskylä

New HV divider

• Fixed all small glitches of the previous design– Output protection

• High quality components – e.g. uses gold-plated pin connectors

• Proper fixtures– cables (type and length) – and connectors

• Tomorrow (24/11/2004) we’ll get the new HV divider for full tests in Jyväskylä

CERN November 22, 2004 14W.H.Trzaska HIP Jyväskylä

New PMT (optimum photocathode sensitivity)

• Our measurements indicate that we may decrease slightly photocathode sensitivity (to be able to work at higher HV)

• Tomorrow the new batch of PMTs is arriving for tests in our Lab (using laser and 0.5T magnet)

• The best performance of a PMT in the magnetic field is achieved at the highest HV setting

• PMT gain increases with HV

CERN November 22, 2004 15W.H.Trzaska HIP Jyväskylä

New detector shell