scintillator based muon upgrade / belle super b factory workshop in hawaii 19-22 jan 2004, honolulu,...

Scintillator based muon upgrade / BELLE

Super B Factory Workshop In Hawaii19-22 Jan 2004, Honolulu, Hawaii

1. Scintillator strip option2. Geiger photodiodes (SiPM & MRS APD)3. Scintillator tile option4. First tests at BELLE5. Conclusions

Outline

M.Danilov, D.Liventsev, R.Mizuk, P.Pakhlov, V.Rusinov, E.Tarkovsky, I.Tikhomirov, T.Uglov (ITEP Moscow)

Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov 2

Scintillator Strip Geometry (1)

System consists of ~17k scintillator strips with WLS fiber readout.


Scintillator Strip Geometry (2)

Max. strip length ~2.8m.


Light Yield in MINOS Scintillator Strips1cm x 4cm, 1.2mm Y11 fiber

5p.e. correspond to efficiency of about 99%.Mirroring of fiber far end increases light yield by a factor 2 (at the end).

N p

.e.

Distance along strip, m


Problems with PM Readout

• Complicated transportation of light with clear fibers.• Difference of gain between different pixels (up to factor 3).• Cross-talk ~ 5-10% → ghost clusters (at acceptable level).


SiPM

For further details see:«Advanced study of SiPM»http://www.slac.stanford.edu/pubs/icfa/fall01.html

2ns

2mV

SiPM main features:• Sensitive size 1x1mm2 on chip 1.5x1.5 mm2

• Gain 2106

• Ubias~50V• Recovery time ~ 100 ns/pixel• Number of pixels: 576-1024• Insensitive to magnetic field• Dynamic range ~103/mm2

R 50

h

pixels

Ubias

50V

Al

DepletionRegion 2m

substrate

ResistorRn=400 k

20m

42m


0

10

20

30

40

0 1 2 3 4 5 60

5

10

15

20

Ubreakdown

=48V

operating voltage

one pixel gain (exp. data) one pixel gain (linear fit)

One

pix

el g

ain

M, 1

05

Overvoltage U=U-Ubreakdown

, V

detection efficiency (=565nm)

Det

ectio

n ef

ficie

ncy

, %

Gain & Efficiency of SiPM vs. Overvoltage

Efficiency = QEgeom

geom~0.3

(B.Dolgoshein et al. )


SiPM Cross-talk

Pixel Gain, 105

Inte

rpix

el C

ross

-tal

k (>

1 to

1 r

atio

)


Efficiency vs. Wavelength

200 300 400 500 600 700 8000

20

40

60

80

QE•geom

SiPM

PMT XP2020Q number 40979(according to Philips Photonics)

APD EG&G C30626E (NIM A428 (1999) 413-431)

room temperature

QE

, %

Wavelength , nm

(B.Dolgoshein et al. )


Emission Spectrum of Y11 WLS Fiber

Measured at distances 10cm, 30cm, 100cm and 300cm from source.


SiPM Noiserandom trigger

1p.e.2p.e.

3p.e.Ped.

noise rate vs. threshold

Optimization of operatingvoltage is subject of R&Dat the moment.

1p.e. noise rate ~2MHz.threshold 3.5p.e. ~10kHzthreshold 6p.e. ~1kHz


Scan of Strip Using Cosmics Setup

LED cosmics

∑ PoissXtalk·G(x0+i·Δx,0+1 ·√i) Center of strip, N pixels (peak) = 9.7

groove depth 2.5mm


Scan of Strip Using Cosmics Setup (2)

Poisson mean for MIP at normal incidence

Strip 200x2.5x1cm3

MC: light yield for 4x1cm2 stripwill be ~25% smaller.

In the middle of 280x4x1cm3 strip we expect ~ 9p.e.

With threshold 4.5p.e. • noise rate <10kHz• efficiency 98%• average efficiency >99%

Similar detector - MRS APD - with smaller x-talk and similar efficiencyis under investigation now. Expect efficiency >99.5% with noise <1kHz


Metal-Resistor-Semiconductor APD (CPTA, Moscow)


MRS APD Cross-talk


MRS APD Efficiency vs. Wavelength


Scintillator Tile Geometry (1)


Scintillator Tile Geometry (2)


Light Yield from 16x16x0.5cm3 Tile with Circular WLS

Y11 MC 1mm fiber, Vladimir Scintillator


Experience of CALICE (1)



Amplitude distributions for LED and for triggered 90Sr signals in 5x5x0.5cm3 tile.



Light Yield from 129 Minical tiles.


Measurement of Scintillator Sensitivity to Neutron Background at BELLE


Neutral KLM Clusters with Matching ECL Originating from Background

cosθ

MC (no continuum)

BB + bg

BB only

dataexp 13

(lab.system)

• Random KL background exists already at present background rates even if coincidence between two layers is required.

• With scintillator KLM even one layer clusters could be considered for KL reconstruction.

cosθ


Conclusions

1. Most probably RPC KLM will not be able to work good enoughat higher luminosity in end-cap region.

2. Scintillator technique can be used to build reliable, very efficient and simple in operation KLM.

3. Many parameters should still be optimized.


Tests of Different Shapes of Grooves


Amplitude Dependence on Temperature

T=+9.5oC

T=+14.6oC

T=+20.1oC

T=+25.3oC


Light Yield from 5x4x1cm3 Scintillator with Straight Central Groove (1mm Y11 WLS fiber, β-source)

80

90

100

110

120

130

140

150

0 2 4 6 8

Series1

groove depth, mm


Tests of Different WLS Fibers and Scintillator Types

WLS

Y11 MC1 mm

BC-92 SC1 mm

5*5 cmcircle

5*5 cmdiagonal

1 1

0.46 0.58

To understand different light loss withBC-92 for circular and straight grooveslight loss in a fiber loop was tested:

-source

scint

PMR=22mm

Y11 has 6% light loss; BC-92 -27% (with respect to a straight fiber)

I. Comparison of Y11 and BC-92.

BICRON-408 scintillator gives x1.5 more light than Russian scintillators.It is order of magnitude more expensive. Therefore we use Russian scintillator.


Light Yield of Individual MINOS Sc. StripsThere is a substantial difference in individual strip responce.However all strips give more than 3p.e. at 3m.

Nonuniformity across strip is about 5% only for 4cm x 1cm strips.


Problems with RPC

• Hit rate at 1200mA/800mA– Barrel: ~ 0.02 Hz/cm2 (~same as

no beam case)– Endcap: ~ 0.1 Hz/cm2

• Extrapolation to x20 beam current (assuming linear)– Barrel: at most ~ 0.4 Hz/cm2 at

most a few % efficiency drop, acceptable

– Endcap: ~ 2 Hz/cm2 significant efficiency drop, something must be done

scintillator based muon upgrade / belle super b factory workshop in hawaii 19-22 jan 2004, honolulu,...

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