Scintillator wls fiber readout with psips
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Scintillator/WLS Fiber Readout with PSiPs. Pablo Bauleo, Yvan Caffari, Eric Martin, David Warner, Robert J. Wilson Department of Physics Colorado State University. International Workshop on new Photon-Detectors (PD07) Kobe, Japan. June 27 nd 2007. Overview.

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Scintillator/WLS Fiber Readout with PSiPs

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Scintillator wls fiber readout with psips

Scintillator/WLS Fiber Readout with PSiPs

Pablo Bauleo, Yvan Caffari,Eric Martin, David Warner,

Robert J. Wilson

Department of Physics

Colorado State University

International Workshop on new Photon-Detectors (PD07)

Kobe, Japan.

June 27nd 2007


Overview

Overview

  • Pixelated Silicon Photosensors (PSiPs)

  • Motivation: T2K/ND280 + ILC Detector

  • Bench Tests – aPeak GPDs

  • FNAL Beam Test – HPK MPPC & CPTA MRS

  • Summary

R.J.Wilson


Motivation

Motivation

  • Linear Collider Detector

    • Muon, calorimeter systems

    • MINOS scintillator bar w/ Y-11 WLS fiber muon system candidate

  • T2K Near Detector at 280 m (ND280)

    • Beam Monitor (NGRID), Fine-Grained Detector (FGD), Sideways-Muon Ranging Detector (SMRD), Pi-zero Detector (P0D)

    • P0D : 98% n interactions <19 MeV/bar; 30% <1MeV/bar

  • Historically CSU also motivated by Ring Imaging Cerenkov Detectors

    • BaBar DIRC with array of ~11,000 1” pmts and large water tank outside magnetic field

    • R&D on Focusing DIRC with small arrays of single UV photon sensitive solid state pixels in the magnetic field

    • Led to association with US developer of PSiPs (aPeak Inc.)

R.J.Wilson


Pmt cosmic ray led charge distributions

LED

g180-s145-250V - ADC0

PMT Cosmic Ray/LED charge distributions

  • PMT (EMI 911B) response to ~ vertical cosmics rays (VCR) as a reference

  • Simulate with 550 nm LED (matched to peak of Y11 WLS fiber output peak)

  • Allows for rapid data collection

  • LED distribution lacks high tail of cosmic ray sample

  • LED settings adjusted to shift peak for range 0.2-13 VCR; shape and spectrum of true multiple VCRs unknown

  • ~2 MeV deposited/VCR

  • No absolute calibration 1 VCR  200 “photons” out of Y11 WLS

MINOS/ILC-Muon bar

1 “VCR”

1 ADC ct. = 0.125 pc

Mean charge ~11 pC in 300 ns gate defines unit of 1 VCR;

Same PMT fitted with a mask with 1 mm diameter circular hole; placed 80 cm from 550 nm LED

LED voltage (2.5 V) and pulse width (14.5 ns) adjusted to ~ replicate charge spectrum of 1 VCR (180 ns gate)

Cosmics

Charge (ADC bins)

R.J.Wilson


Apeak inc 64 fiber readout 16 gpd pixel

aPeak Inc. 64-fiber Readout (16-GPD/pixel)

  • aPeak goal - high efficiency, high-density, compact, low-cost WLS/fiber readout primarily for non-calorimetric use

  • 64 x 1 mm2 fiber readout on one chip

  • Each pixel is a cluster of sixteen 160x160 mm2 GPDs on 240 mm centers

  • Geometrical efficiency for 1.2 mm diameter fiber ~ 0.36 (0.45 for 1 mm)

  • Signal out proportional to number of hit GPDs; allows hit threshold tuning (not optimized for calorimetry)

  • Very low operating bias: ~14 V

1.2 mm

10 mm

2006

R.J.Wilson


Gpd signal

Single shot

Average many triggers

GPD Signal

500 ns

500 ns

  • GPD bias -14.2 V

  • 550 nm LED illumination

  • 10x linear amplifier

  • Setup not optimized for fast signals – intrinsic device speed much faster (aPeak)

  • DC offset – origin unclear, depends on bias

R.J.Wilson


Detection efficiency dark count rate

Detection Efficiency & Dark Count Rate

1.8

0.2

0.4

1.6

0.7

1.4

0.9

1.2

1.2

DE & DCR (MHz)

2.6

1

3.9

0.8

5.2

0.6

6.5

7.9

0.4

9.2

0.2

10.5

DCR

0

0

-200

-400

-600

-800

-1000

V

( mV )

th

Detection Efficiency/Dark Count Rate

  • Dark Count Rate (DCR) from scaler of discriminated signal

  • Product of signal width (w) and dark count rate (DCR) reduces effective detection efficiency by factor ~ (1-w*DCR)

  • DEmeas = 95% for 1 VCR has 0.6 MHz DCR so 300ns gate => DEeff ~ 78%

  • Improve by lowering temperature

    • Developed computer controlled system with Peltier refrigerator

LED

Intensity

GPD bias -14.2 V

DCR

95% DE

2.6 VCR

0.9 VCR

5.2 VCR

At low Vth rate

too high leadssignal overlap

Note: GPD signal with 10x amplifier

DE = measured rate – dark rate LED rate

R.J.Wilson


Detection efficiency charge distribution

-10°C

At low temp./low bias

begin to see “features”

-19°C

Detection Efficiency: Charge Distribution

DE = # triggers with charge above “threshold” # triggers

-10°C

Range bias voltage: 13.1-14.1 V

- 1 “VCR” LED intensity ()

- Dark ()

R.J.Wilson


Single photoelectron peaks

Single Photoelectron Peaks

-19°C-13.3V

  • First time individual peaks resolved in aPeak device

  • Absolute gain from pe peaks ~2.5 x 106

  • Dark spectrum -> crosstalk low

2 pe

3 pe

4 pe

1 pe

-19°C-13.3V

R.J.Wilson


Pixel charge vs intensity

Pixel Charge vs. Intensity

  • Mean measured GPD charge linear for 0-1.3 VCR; 1VCR~10pe

  • Plateau corresponds ~ to all 16 GPDs in the cluster registering a hit; shape consistent with a model based on earlier single GPD DE measurements;

  • Large “dark” charge => high rate of thermal electrons initiated signals

GPD bias -14.2 VRoom temp. ( ~23°C)

corrected for -29 dB attenuator but not 10x amplifier

R.J.Wilson


Apeak gpds summary

aPeak GPDs Summary

  • New aPeak high density readout (64 fibers/chip)

    • Modest “calorimetric” response demonstrated; useful for threshold tuning

    • High efficiency for relatively high light levels at room temperature due to high dark count rate/long pulses

    • Low temp. demonstrated single p.e. for first time

  • aPeak plans

    • “Can reduce DCR 50-70% in medium volume run (planned for next run)”

    • “This will allow us to provide both verified-reliability, highly-manufacturable devices and customized devices for low-noise needs” 

    • “Cost/die should be similar for both technologies, however the medium volume approach would require large orders  for new layouts or if stock is depleted”

    • “Both technologies should provide reliable devices but only the high-volume process and layout have been (extensively) verified at aPeak for reliability and radiation damage”

  • Single fiber readout 129-pixel devices in-hand

    • Uses high volume process

    • Calorimetric behavior demonstrated at room temp

R.J.Wilson


Fnal beam test experiment t695

FNAL Beam Test – Experiment T695

  • Cosmics give MIP response and energy scale but low rate makes it difficult to test many devices

  • LED flasher is fast but not the same spectrum as Y11 output and doesn’t map position response (especially in triangular P0D bars)

  • Beam test at new Fermi National Accelerator Lab Test Beam Facility (FTBF) – Experiment T695

  • First FTBF beams delivered February 2007 and we were there just one month later – a few “hiccups” but went reasonably well.

R.J.Wilson


Beam parameters

Beam Parameters

  • 120 GeV protons (MIPs)

  • Timing structure

    • Bunch train: 84 x 18.87ns buckets in 1.58 ms

    • 1 train every ~12 ms (if 1 main injector bunch)

    • 4 sec “spill”  3.33 x 105 trains/spill

    • ~60,000 protons/spill

    • Estimate single proton per trigger ~85% of time

  • Beam size:

    • 3-4 mm RMS horizontal (along bars)

    • 5-6 mm RMS vertical (across the bars)

  • Trigger

    • Scintillator hodoscopes up/downstream of test box

    • No precision tracking in the analysis

R.J.Wilson


Csu beam test team

CSU Beam Test Team

Pablo Bauleo

  • DAQ/online s/w

    Eric Martin

  • Electronics

David Warner

  • Design/fabrication

    Yvan Caffari

  • Offline analysis

Robert J. Wilson

  • PI

R.J.Wilson


Test structure

Test Structure

CSU PSiP housing;optical grease used for coupling;

PMTs at far end (expect low reflection)

3 MINERVA/P0D + 2 MINOS/ILC

scintillator + Y11 WLS fiber

R.J.Wilson


Test structure1

Test Structure

A calibrated PMT can be mounted

in the same location as each PSiP

“Beam Box” checkout at CSU

R.J.Wilson


Fnal beam test

Remote controllable vertical/horizontal table

FNAL Beam Test

R.J.Wilson


Devices tested

Devices Tested

  • 5 HPK MPPC-11-T2K-5808: 400 pixel

    • Vop ~70 V

  • 4 CPTA MRS 1710: 556 pixel

    • 2 with Vop~44V

    • 2 with Vop~48V

  • 5 aPeak Inc. GPD 100 pixel

    • Vop~14 V

    • Not reported here

R.J.Wilson


Calibration monitoring configurations

Calibration/Monitoring/Configurations

  • Monitoring pmts at opposite fiber end from PSiPs(except one)

    • Hamamatsu R268, Vop=1300V

  • Initial run through all planned beam positions with pmt replacing PSiP

    • Electron Tubes 9111A, Vop = -950V, gain 1.03 x 107

  • “Beam Off” data (100 Hz pulser) taken interspersed with “Beam On”

  • “Long cables” configuration ~11ft/3.3 m cables , temp 23°C

    • MPPC 50Gv x 6dB attenuator; 400 ns gate

    • MRS 50Gv, no attenuator; 400 ns gate

  • “Short cables” configuration ~3ft/1 m; temp. 17°C

    • MPPC 50Gv, no attenuator; 200 ns gate

    • MRS 50Gv, no attenuator; 400 ns gate

R.J.Wilson


Fnal beam test1

y

x

3 horizontal positions

3-5 vertical positions

4

y

x

120 GeV/c protons

3

1

5

66 mm

40.8 mm

2 MINOS/ILC bars

3 MINERVA/P0D bars

2

FNAL Beam Test

near end

center

far end

PSiP

or

Calibration

PMT

Monitoring

PMT

Not to scale

4in/10cm

35in/89cm

69in/175cm

To scale

R.J.Wilson


Beam hodoscope

Beam – Hodoscope

2 protons

1 proton

Beam Off

All plots following are “1 proton” or “Beam Off” (for pedestal/DCR)

R.J.Wilson


Calibration pmt psip comparison

  • The monitoring PMT has the

    same behavior for both runs.

  • So can directly compare the PSiP response to the calibration PMT

Monitoring PMT

MPPC Vbias = -70.0V

Calibration PMT - PSiP Comparison

Beam on the center of a

MINERVA bar.

2 independent runs :

  • 1 run with a calibration PMT

    at the near end with

    1 monitoring PMT at the far

  • 1 run with 1 MPPC at the near

    end and the same monitoring

    PMT.

Monitoring PMT

Calibration PMT

R.J.Wilson


Mppc charge spectrum 1 run

4

3

1

5

2

PSiPs

MPPC Charge Spectrum – 1 run

Not to scale

R.J.Wilson


Mrs charge spectrum

MRS Charge Spectrum

Near-end

Far-end

R.J.Wilson


Calibration dark signal spectrum

Dark spectrum

Dark spectrum

0 p.e.

0 p.e.

1 p.e.

1 p.e.

2 p.e.

2 p.e.

3 p.e.

3 p.e.

4 p.e.

4 p.e.

Calibration – Dark + Signal Spectrum

  • Beam Off (pulser) and Beam Ondata

  • MPPC: use p.e. in low intensity signal and use of the p.e. in the dark spectrum (self-calibration)

  • MRS: use p.e. in low intensity signal; no distinct p.e. peaks in dark spectrum

  • Calibration PMT: known characteristics and beam data

Dark spectrum

MRS

Dark spectrumMPPC

0 p.e.

1 p.e.

2 p.e.

3 p.e.

4 p.e.

R.J.Wilson


Scintillator wls fiber readout with psips

HPK MPPC : Cross-talk

0.5 p.e.

1.5 p.e.

# events above 1.5 p.e threshold

Cross talk =

# events above 0.5 p.e. threshold

(no subtraction of random coincidences)

R.J.Wilson


Hpk mppc gain curve

HPK MPPC : Gain curve

ND280 electronics req.

  • From just beam off dark spectrum (similar results with signal spectrum)

  • Linear - Slope ~ 4.5 x 105 /V

  • => self-calibration

  • From fit to data – no crosstalk correction

  • Measured Npe ~ linear w/ V=(Vbias-Vbd)

  • “kink” at 3rd point – not understood…

R.J.Wilson


Scintillator wls fiber readout with psips

HPK MPPC : Dark Rate

  • Dark Count Rate calculated from Beam Off spectrum for 0.5 p.e. & 1.5 p.e. thresholds

  • Compare with manufacturer data

    • Gain measurements consistent (to 10%)

    • > 0.5 p.e. rates lower 10-30%

    • > 1.5 p.e. rates higher by factor 5-7

  • Effect of high crosstalk

R.J.Wilson


Cpta mrs gain npe

CPTA MRS : Gain/Npe

ND280 electronics req.

# pde increase linear with V

  • From signal spectrum

  • Gain ~ linear with V=(Vbias-Vbd)

  • Slope ~ 3.8 x 105 /V

R.J.Wilson


Attenuation pmt on minos minerva

Attenuation –PMT on MINOS+MINERVA

Beam on vertical center of middle MINERVA bar

MINERVA/P0D

MINOS

Bars indicate RMS of distributions

R.J.Wilson


Attenuation mppc mrs on minos bar

Attenuation – MPPC/MRS on MINOS bar

  • Beam on vertical center of MINOS bar

  • From fit to data – no crosstalk correction (30-35% for MPPC)

MPPC

MRS

c.f. PMT range 14.5 p.e. – 6 p.e.

R.J.Wilson


Scintillator wls fiber readout with psips

Attenuation –MPPC/MRS on MINERVA/P0D bar

  • Beam on vertical center of MINERVA/P0D bar

  • From fit to data – no crosstalk correction (30-35% for MPPC)

MPPC

MRS

c.f. PMT range 13 p.e. – 5.5 p.e.

R.J.Wilson


Attenuation summary

Attenuation Summary

  • MPPC and MRS bias chosen to meet T2K/ND280 electronics gain & DCR requirements

    • MPPC_54: V=70.3V, Vop-Vbr =1.67V, Gain=822k, Xtalk=30%

    • MRS_111: V=42.5, Vop-Vbr=2.2V, Gain=738k

  • Fit to an exponential, signal at end of 240 m P0D bar would be:

    • 5.9 p.e. for MPPC

    • 2.4 p.e. for MRS

    • 3.5 p.e. for PMT

  • P0D simulation assumes 6.5 p.e. for blackened fiber end (~3.3 p.e./MeV)

MPPC – xtalk corrected

PMT

MRS

R.J.Wilson


Summary

Summary

  • US developer (aPeak) with high density, (potential) low cost design

    • 64 fiber r/o with modest dynamic range (16-pixels)

    • Room temp. operation but single p.e. resolution only below -10°C

    • Recent 100-pixel single fiber r/o device tested

    • Future developments include lower DCR design (room temp. p.e.?)

  • Beam test of HPK/MPPC and CPTA/MRS with MINOS & T2K/ND280 P0D bars

    • Beam test conditions i.e. many noise sources, long cables etc.

    • Evaluated basic performance characteristics

    • MPPC promising for QE & single p.e. DCR but crosstalk worrisome

    • MRS older design – PDE not high enough for P0D

  • T2K/ND280 committed to PSiPs rather early in their commercial history - a bold choice not without risks… continued testing is essential

R.J.Wilson


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