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Analysis of TOF data

Yordan Karadzhov

St.Kliment Ohridski University of Sofia

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electron beam finger 1

Bar 1

Bar 2 DAQ system

Bar 3 finger 2

Layout of the TOF system in Frascati test

PMT left scintillator PMT right

TOF bar

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List of analyzed runs Run Energy TDC Splitter

Discriminator

• 124-133 350 MeV V1290 Active CAEN N417 • 141-149 300 MeV V1290 Active CAEN N417 & PLS 711

• 215-217 200 MeV V1290 & V775 Passive CAEN N417 & PLS 711 • 250-255 350 MeV V1290 & V775 Passive PLS 711• 255-259 350 MeV V775 Passive CAEN N417

Because of the poor statistics we need to use a chainof runs taken in same conditions (experimental setup) and same beam energies.

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ADC pulse height distribution (left PMT of bar 1)

Example of the general event selection cut

ADC spectrum inlogarithmic scaleSelection of single electron events

Part of the same spectrum in linear scale

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Intrinsic time resolution of the TOF bar

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1122

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rightbar

leftbar

rightbar

leftbar

barbar

TTTTTOF

Timebar2 Timebar1

2_rightleft

barT

TTn

The quantity (Tleft – Tright )/2 has the same variation as (Tleft + Tright )/2 but time jitter cancelled out, so the intrinsic time resolution of the bar could be evaluated more conveniently from its distribution.

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Intrinsic time resolution of TOF bars Run 141 – 149 Distributions of (Tleft – Tright )/2

TDC V1290

Bicron BC420 - 4cm thick impact point at 10cm from Center Discr CAEN N417σ = 63.91 ps

Bicron BC420 - 4cm thick impact point at centerDiscr PLS 711σ = 66.18 ps

Bicron BC408 - 6cm thick impact point at centerDiscr PLS 711σ = 109.7 ps

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Intrinsic time resolution of TOF bars Run 124 – 133

Distributions of (Tleft – Tright )/2

TDC V1290 Discr CAEN N417 Bicron BC420 - 4cm thick impact point at 15 cm from center (5 cm from edge)σ = 72.73 ps

Bicron BC420 - 4cm thick impact point at centerσ = 64.91 ps

Bicron BC408 - 6cm thick impact point at centerσ = 107.2 ps

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Intrinsic time resolution of TOF bars Run 215 – 217 Distributions of (Tleft – Tright )/2

TDC V1290

Bicron BC420 - 4cm thick impact at center Discr CAEN N417σ = 44.22 ps

Bicron BC420 - 4cm thick impact point at centerDiscr PLS 711σ = 97.16 ps

Bicron BC404 - 6cm thick impact point at centerDiscr PLS 711σ = 49.21 ps

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Intrinsic time resolution of TOF bars Run 215 – 217

Distributions of (Tleft – Tright )/2

TDC V775

Bicron BC420 - 4cm thick impact point at centerDiscr PLS 711σ = 94.16 ps

Bicron BC404 - 6cm thick impact point at centerDiscr PLS 711σ = 41.61 ps

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Intrinsic time resolution of TOF bars Run 250 and 251

Distributions of (Tleft – Tright )/2

TDC V1290

Bicron BC420 - 4cm thick impact at center Discr PLS 711σ = 47.24 ps

Bicron BC420 - 4cm thick impact point at centerDiscr PLS 711σ = 115.4 ps

Bicron BC404 - 6cm thick impact point at centerDiscr PLS 711σ = 71.63 ps

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Intrinsic time resolution of TOF bars Run 250 and 251

Distributions of (Tleft – Tright )/2

TDC V775

Bicron BC420 - 4cm thick impact at center Discr PLS 711σ = 49.95 ps

Bicron BC420 - 4cm thick impact point at centerDiscr PLS 711σ = 101.4 ps

Bicron BC404 - 6cm thick impact point at centerDiscr PLS 711σ = 66.67 ps

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Intrinsic time resolution of TOF bars Run 255 – 259

Distributions of (Tleft – Tright )/2

TDC V775 Discr

Bicron BC420 - 4cm thick impact at center CAEN N417σ = 90.76 ps

Bicron BC420 - 4cm thick impact point at centerCAEN N417σ = 83.47 ps

Bicron BC404 - 6cm thick impact point at centerCAEN N417σ = 105.4 ps

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Run Energy TDC Splitter Discriminator

124-133 350 MeV V1290 Active CAEN N417 BC 420 – 72.73 ps

V1290 Active CAEN N417 BC 420 – 64.91 ps

V1290 Active CAEN N417 BC 408 – 107.2 ps

141-149 300 MeV V1290 Active CAEN N417 BC 420 – 63.91 ps

V1290 Active PLS 711 BC 420 – 66.18 ps

V1290 Active PLS 711 BC 408 – 109.7 ps

215-217 200 MeV V1290 Passive CAEN N417 BC 420 – 44.22 ps

V1290 Passive PLS 711 BC 420 – 97.16 ps

V1290 Passive PLS 711 BC 404 – 49.21 ps

215-217 200 MeV V775 Passive CAEN N417 BC 420 –

V775 Passive PLS 711 BC 420 – 94.16 ps

V775 Passive PLS 711 BC 404 – 41.61 ps

250-251 350 MeV V1290 Passive PLS 711 BC 420 – 47.24 ps

V1290 Passive PLS 711 BC 420 – 115.4 ps

V1290 Passive PLS 711 BC 404 – 71.63 ps

250-251 350 MeV V775 Passive PLS 711 BC 420 – 49.95 ps

V775 Passive PLS 711 BC 420 – 101.4 ps

V775 Passive PLS 711 BC 404 – 66.67 ps

255-259 350 MeV V775 Passive CAEN N417 BC 420 – 90.76 ps

V775 Passive CAEN N417 BC 420 – 83.47 ps

V775 Passive CAEN N417 BC 404 – 105.4 ps

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Time of Flight and Time-walk effect

• Because leading edge discriminator has been used for the time measurements, the time-walk effect should occur.

• Time-walk should effect measured TOF especially in cases when we have different total charge collected in the bars.

• This effect can be suppressed by constrain on difference in ADC pulse heights (signals with same pulse heights will give approximately same time-walk).

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Time of Flight and Time-walk effectRun 124-133

25.01

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rightPMTbar

rightPMTbar

rightPMTbar

ADC

ADCADC

no constrain σ = 134.7 ps

σ = 123.5 ps

σ = 91.27 ps

10.01

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rightPMTbar

rightPMTbar

rightPMTbar

ADC

ADCADC

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Time Of Flight and Time-walk effect

Run 124-133

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2211left

barright

barleft

barright

bar ADCADCADCADCADC

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Conclusions • Intrinsic resolution of the bars made of BC404 or BC420

is satisfactory. BC 408 is significantly worse.

• Passive splitter gives better performance than active.

• TDC V775 gives a little bit better results than V1290.

• We need more detailed investigation of the relation between intrinsic time resolution and position of the impact point.

• The effect of time-walk is significant and should be corrected for.