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Update on HPD noise study

Pawel, Dima, Kerem, Numan

Richard,Ted, Ellie, Terry,

Christian, Pam, Alexander

HCAL commissioning MtgFebruary 23, 2008

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Summary of issues:

A) fake triggers

TPs set on, but no energy in corresponding QIE channels

B) HPD noise rate

single-HPD events

multi-HPD events

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TP vs ADC, r35672

Fake triggers~ 90% of events

Good triggers~ 10% of events

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ADC and TP in eta-phi space

R35127, ev6366, 3d plot

Adc (qie)

Trigger primitives (TP)

Fake trigger problem

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Noise runs: Fake trigger problem

A lot of triggers does not have ADC confirmation

Problem appears in 4x2 blocks of triggersections

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Eta/Phi distribution of TP>=20 after fake triggers removed

Only ADC confirmed TP Occupancy

ADC> 20 lin adc counts (~ 4 GeV cut)

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TP vs digi mismatch existed also in GREN HCAL Trigger

Run 30205: HCAL trigger only

Run 30478: DT+RPC+HCAL trigger

GREN run, HCAL top-and-bottom trigger

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Summary: fake trigger issue fake hcal triggers, we mean triggers which do not have matching

(correspondence) in qie energy• Qie energy for all hcal towers is consistent with pedestals, event

appears to be healthy (proper number of digis reconstructed• Fake TPs appear in blocks 2x4 (in phi x eta).• They apper in proper time bucket. For runs taken on fri-feb15 this

was TP(2), for runs taken on wed-feb20 this was TP(3). Earlier bx have no sign of corrupted TPs.

• Fake HCAL triggers first noticed in r30205(gren, top-bottom coincidene),

• Also present in r35127 (first attempt to take HPDnoise data (fri, feb15)

• Also present in r35605 (wed, feb20)• In r35672, almost 90% of triggers were fake.• within run, fake trigger rate is not stable (for r35127, it only started after evt

6000

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TP and QIE energy, r35605 (Trig Th = 10 GeV)

Lin ADC counts

Lin ADC counts

TP 100 GeV =500 Lin Qie counts

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TP and QIE energy, r35672, Trig Th = 20 GeV

TP :100 GeV = 500 Lin qie counts

Lin ADC countsLin ADC counts

Lin ADC counts

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Single HPD noise: Event examples

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Single HPD noise

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Multi-HPD noise: Event examples

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Multi-HPD noise

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HPD and pixel multiplicity

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Single and multi-HPD occupancy

Single-HPD noise HB- Single-HPD noise HB+

Multi-HPD noise HB- Multi-HPD noise HB+

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Summary: HPD noiseHPD noise data taken on wed-feb20:Runs taken with two thresholds: 10 GeV and 20 GeVHBplus, HBminus, HEplus included in the triggerRates (raw, reported by GT), 1-5kHz at 10 GeV, 10-70Hz for 20 GeV (not clear what real rates are, as we have fake trigger problem)We see two types of events single-HPD noise event (only one HPD shows signs of noise) multi-HPD noise events (two or more events within same RBX show signs of noiseHPD multiplicity: 95% are single-HPD noise (at 20 GeV TP cut)If you lower TP cut to 5 GeV, amost 10% of events have noise in full RBX

Pixel/HPD multiplicity: 50% of events have one or two pixels firing. Multi-pixel events (>2pixels/HPD) have flat distribution (as likely to have 4 pixels firing as 10 or 16.

In HB, there are five most noisy single-HPD (>100 events/6k total)-1, -52, -63, -68, +8Not all HPDs which are noisy in single-HPD mode, are also noisy in multi-HPD mode. HPD -63, -68 and +8 only contribute to single-HPD noiseHPDs -1 and -52 contribute both to single-HPD noise and multi-HPD noise.

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Back-up slides

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HB TP occupancy, TP> 5 GeV(includes also fake triggers)

40k events from r35672(trig.th=20GeV)

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HB TP occupancy, TP> 5 GeV(fake triggers removed)

40k events from r35672 (trig.th=20GeV)

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HB TP occupancy, TP>10 GeV(fake triggers removed)

40k events from r35605 (trig.th=10GeV)

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HB TP occupancy, TP > 20GeV(fake triggers removed)

40k events from r35672(trig.th=20GeV)