14/02/2007 Paolo Walter Cattaneo 1

1. Trigger analysis

2. Muon rate

3. Q distribution

4. Baseline

5. Pulse shape

6. Z measurement

7. Att measurement

OUTLINE

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Trigger DataCharge vs Amplitude PMT

Key for the Trigger System using pulse height with no information about pulse charge (RUN

236,237,239)

Amplitude (a.u.)

Charg

e (

a.u

.)

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Charge Inner vs Outer

We observe that charge distributions are different between inner and outer PMTs (RUN

236, 237, 239).

Charge Inner PMTs

Charge Outer PMTs

Q (a.u.)

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Comparison with MC Data

DATA

MONTECARLO

Measured charge distribution for inner PMTs the Montecarlo

one are in agreement, as well as the outer ones

Q (a.u.)

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Low energy events on PMT spectrum

Bar 16 (first of upstream TC) Outer PMT

Bar 19 (fourth of upstream TC) Outer PMT

Data

Montecarlo

Q (a.u.)

Q (a.u.)

RUN 236, 237, 239

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TRG vs DRS height pulse correlation Key for Type3 boards and LXe acquisition, we can see a good linearity until 0.6 mV (0.1 V on DRS 0.4 V on TRG) (RUN 236, 237,

239).

(V)

(V)

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We used MC computed acceptance to convert experimental trigger rate to stopped muon rate.

Muon rate vs beam intensity

MC acceptance including cuts

4.2 %

MC acceptance including cuts

3.7 %

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Bar number 11, run 154

Bar number 6, run 154

Calibrated by superimposing charge peak position of MC events on experimental data

Charge distribution (1)Charge distribution (1)Red = Data

Black = MC

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Charge distribution (2)

Data wider probably for difficulties of individual software calibration

Run 154 Low Intensity

Run 236 High Intensity

Red = Data

Black = MC

Charge

Charge

All bars together

All bars together

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Run 154 Low Intensity

Red = Data

Black = MC

Run 236 High Intensity

Number of hit bar per Number of hit bar per eventevent

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Number of hits on each bar

Down stream

Down stream

Up stream

Up stream

Run 154 Low Intensity

Run 236 High Intensity

10*

KH

z

KH

z

In COBRA, with and without Beam; acquisition with oscilloscope of waveform from PMs with single bar triggering, and evaluation of charge ratio for each pulse, with no selection of impact position;distribution of log(Qin/Qout) for each bar reflects event distribution on each bar; width of the distribution is inversely proportional to attenuation length of bar => clue to the applicability of position reconstruction by means of “charge division”

Position reconstruction by

means of charge ratio – PSI

setup

charge distribution on a bar from cosmic rays

waveform analysis - continue

Beam turned on: event distribution on 4 US bars

most of the events are on the inner part of the detector;

needed calibration of each bar to determine impact point.

Inner PMT Outer PMT

CAMAC results – position

correlations

correlation between adjacent bars, distribution of charge ratio on bar 1 for selected impact position on bar 0

CAMAC results – position

correlations

correlation between adjacent bars: US TC (left) and DS TC(right);curves are fit to the data

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Baseline & noise analysis 1Search signal

pulse

Search pulsein the region

Fix region just before pulse

calculate baseline use database value

no

no yes

yes

low threshold

Threshold ?

Range ?

How stable ?

How often ?

● averaging● did not try fitting

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Baseline & noise analysis 2: StabilityNoise level 0.6 ~ 1mV

Baseline fluctuation in a run ~0.3mV

Baseline shift

with change of beam intensity

with change of trigger type

Baseline is stable among same condition runs

We need baseline value in database each run condition.

TC no

TC high

NaI no

TC no

TC low

NaI low

NaI high

NaI no

NaI highbaseline fluctuation

Baseline run in database

already in database for all run

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Pulse shape of PMT signalMade one template waveform for all channel.

Fitting seem to work well

● Not yet making template for each channel

● Feed back to simulation parameter.

Use timing extracted by the fitfor following analysis.

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First Look at Beam dataMichel positron from beam, TC trigger

2GHz sampling data, high intensity beam (#79,80,81)

● Trigger related pulses are located 120~150 nsec in DRS window. Trigger latency ~370 nsec, enough for baseline calculation.

● Pulse height : peak ~60mV, tail with Landau Distribution. about 2.2% pulses are saturated.

Pulse Timing Distribution

Pulse Height Distribution

saturated

trigger pulse

accidental BG

all channels

100ns 200ns

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Z reconstructionReconstruct z-position by time difference of both side PMTs

Roughly estimate ● Effective light velocity (width)● Relative time pedestal (center)

Preliminary

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Z position correction

Effective velocity ~ 15 cm/ns

Time pedestals in database

Preliminary

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Relative gain estimationUsing spectra, estimated relative gain.

Pulse height after correction by position

● Fit with Landau distribution● Compare the MPV

Preliminary

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Height ratioIf pulse height ratio is mainly determined by attenuation length,

● Roughly extracted effective attenuation length Att ~ 96 cm

Preliminary

log(H0/H1) = z*2/Att

Due to variety of solid angle