CDF

Aug. 20th, 2000 1

Scintillation counters for the CDF Muon Upgrade

DPF 2000, Columbus OhioG. Pauletta, for the CDF Collaboration

Outline:Overview

upgrade objectives and the role of the scintillation counters

The Run I countersCharacteristics, performance and problems

Filling the holes and extending the coverage: New countersdesign and performance

Refurbishing old countersmethod and results

CDF

Aug. 20th, 2000 2

Muon Upgrade objectives

Trigger on muons at increased luminosity ( >1032) and shorter bunch crossings (396 ns, 132 ns) Increase coverage

RUN I -------- > RUN II

CMU CMP/CSP CMX/CSX BMU/BSUCoverage 0<<0.6 0<<0.6 0.6<<1 1<<1.5drift time 800 ns 1.4 s 1.4 s 800 ns

CDF

Aug. 20th, 2000 3

The muon trigger

scintillation ctrs. serve to“time stamp” and/or reduceuncorrelated b.g. at level 1

CDF

Aug. 20th, 2000 4

Muon Upgrade subdetectors

Central Muon eXtension(CSX + CMX)

“miniskirt” (new)lower 90o

Intermediate MuonBMU + BSU + TSU (new)

Central MuonuPgrade (CSP + CMP)(new)(old)

Central Muonchambers

CDF

Aug. 20th, 2000 5

Old counter design

EMI 9815 PMT

PVT - base scintillator (NE114)

3 m long

30 cm

2 cm thick

CSPs

CSX “minskirt counter”

CSX “arch” counters

~ 2m

~ 2 m

CDF

Aug. 20th, 2000 6

New counter design

Scintillator: UPS-923A from Monokristal, Kharkov, Ukraine. Polystyrene doped with PTP(2%) and POPOP(.03%)

Ctr. type number dimensions

CSP 150 320cm x 30.5cm x 2 cmBSU 432 164 cm x 17 cm x 1.5 cm

Wls fiber: double - clad Y11 fiber from Kuraray fiber “mirrored at far end.

Hamamatsu H5783 photomultiplier + Cockroft - walton base

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Aug. 20th, 2000 7

Counter readout

Wls fiber

PAD

CDF

Aug. 20th, 2000 8

New counter assembly

PAD

LED

LED

CDF

Aug. 20th, 2000 9

Counter output calibration

Each counter output is calibrated in absolute terms (number of photoelectrons/ADC channel) by exposing it to low - level pulsed light ( ~1 p.e./pulse) and locating the centroid single p.e. distribution.

CDF

Aug. 20th, 2000 10

Counter response ( in photoelectrons) to cosmic muonsis measured in steps of ~20 cm and the results are fittedto extract counter characteristics

Measurements are automated (4 ctrs at a time)Offline fit

npe(x) = n0(exp(-x/l) + r * exp(-(2L -x)/l))From the fit , one extracts:n0 (zero extrapolation)r (reflection coefficient of fiber mirrors)keeping known fiber attenuation constant at 3 m

npe

distance (x) from pmt

CDF

Aug. 20th, 2000 11

RUSSIAN L3 COUNTER ASSEMBLY AND TEST RECORDSLum gain at gain at LED

L3 n pe at PMT sens 800 v 950 v Attenuation measurement PLATEAU AMPL at

counter 315 cm s/n E-05 E+05 E+06 n 0 nend r nend' EAST WEST PAD # Voltage PLATEAU

85 24.5 5440 6.91 6.27 2.47 37.1 24.6 0.85 25.0 1 850 8.186 21.7 5436 7.35 4.69 3.44 37.5 23.8 0.76 23.0 1 23587 23.1 4515 7.93 2.62 2.98 30.3 18.3 0.66 18.0 1 950 6.988 27.7 4704 6.20 4.65 3.40 35.1 22.1 0.74 21.0 1 875 9.6

Fermi VS Dubna NPE

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

1 9

17

25

33

41

49

57

65

73

81

89

97

10

5

Fermi NPE

Dubna NPE

CSP Test Results

0

2

4

6

8

10

12

14

16

18

20

Number of photoelectrons at 20cm from end

fre

qu

en

cy

csp yield

Counter parametersand test results using cosmic muons

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Aug. 20th, 2000 12

Problems with “Old” counters:efficiencies were lower than expected

CSP efficiencies CSX efficiencies

time dependence evident

CDF

Aug. 20th, 2000 13

Attenuation - length for good an bad counters

Response to cosmic muonsconfirms degradation in

attenuation-lengthand

reveals a correspondingdegradation in light yield

Or LED

CDF

Aug. 20th, 2000 14

We unwrap some counters

Good NE114 Bad NE114

Most of the countersdisplay pronounced

aging effects

CDF

Aug. 20th, 2000 15

Old Counter refurbishment:wls fiber ribbon addes to one side and routed to

existing pmt

CDF

Aug. 20th, 2000 16

CSP Repair: Work at Lab 5

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Aug. 20th, 2000 17

npe at 20 cm from end

0

2

4

6

8

10

12

14

16

18

20

1 4 7 10 13 15 19 22 25 28 31 34 37 40

npe

freq

. Series1

Series2

npe at 20 cm from PMT

0

2

4

6

8

10

12

14

16

npe

frew

. Series1

Series2

Distributions of fixed counter outputs

Average npe = 16 p.e. Average npe = 58 p.e.

CDF

Aug. 20th, 2000 18

Muon Upgrade objectives

Trigger on muons at increased luminosity ( >1032) and shorter bunch crossings (396 ns, 132 ns) Increase coverage

RUN I -------- > RUN II

CMU CMP/CSP CMX/CSX BMU/BSUCoverage 0<<0.6 0<<0.6 0.6<<1 1<<1.5drift time 800 ns 1.4 s 1.4 s 800 ns