Technology Choices for the sPHENIX Calorimeter Systems

C.WoodyFor the PHENIX Collaboration

CALOR12Santa Fe, NMJune 5, 2012

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4.65 m

70 cm

95 cm

210 cm

3

Detector Requirements that Determine Technology Choices

Technology Choices:• EMCAL → Tungsten Scintillating Fiber Accordion • HCAL → Iron Scintillating Tile with WLS Fiber • Readout → SiPMs

Detector Requirements • Large solid angle coverage (± 1.1 in h, 2p in f)• Moderate energy resolution

• EMCAL ~ 15%/√E • HCAL ~ 50-100 %/√E (single particle)

• Compact (for EMCAL small RM, short X0)• Hermetic• Projective (approximately)• Readout works in a magnetic field• Low cost

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Optical Accordion

• Volume increases with radius

• Scintillator thickness doesn’t increase with radius, so either tungsten thickness must increase or the amplitude of the oscillation must increase, or both

• Plate thickness cannot be totally uniform due to the undulations

• Small amplitude oscillations minimize both of these problems

Layered accordion of tungsten plates and scintillating fibers

Accordion design similar to ATLAS Liquid Argon Calorimeter

Want to be projective in both r-f and h

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Sintered Tungsten Plates

Variable thickness W-platesScintillating fibers in between

Density r ~ 17.5 g/cm3

Problem is that cannot make sintered plates larger than ~ 20 cm

Phase I SBIR with

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Tungsten-SciFi Epoxy Sandwich

Scintillating fibers 1.0 mm

Pure tungsten metal sheet (r ~ 19.3 g/cm3) Thickness: 2x1.0 mm

Tungsten powder epoxy ( r ~ 10-11 g/cm3) 0.08-0.2 mm

Uniform thickness, thin pure tungsten metal sheets with wedge shaped SciFi + tungsten powder epoxy layer in between

Can be made into larger modules (> 1m)Fabricate in industry

2 W plates/layer 0.6 X0 sampling

X0 = 5.3 mm RM = 15.4 mm

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Effect of Glue on Light Yield

• Gluing fibers reduces light output due to loss of cladding light

• Depends on glue

• Does not seem to depend on whether glue contains tungsten powder or not

glued 6x6 fiber bundle

adc channels

0 100 200 300 400

coun

ts

0

100

200

300

400

500

bundle on pmtfit (mean=202ch ~ 100 pe/MeV)

With a sampling fraction of 4% and 100 p.e./MeV in scintillator

4000 p.e./GeV in the calorimeter

100 p.e./MeV

Direct fiber readout on PMT

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Light Yield and Readout DevicesWant to have small photostatistics contribution to the energy resolution

Need sufficient light output from fibers to allow randomizing and collecting the light onto a small readout device

SiPM

ScintillatingFibers

Possible Readout Schemes

Small reflecting cavity or wavelength shifting block

Need to match ~126 1 mm diameter fibers onto a 3x3 mm2 SiPM with good efficiency and uniformity (earea ~ 2%)

21 mm

21 mm

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Module Construction

Tungsten-SciFi “sandwiches” are cast together in 6 layers to form a module ~ 2 cm “tower” in r-f, ~ 9.5 cm depth, ~ 1.4 m long (L/2)

Modules assembled in groups of 4 to form sectors (~ 400 lb each)64 sectors arranged azimuthally to cover 2p (x2 for both sides)

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Hadron Calorimeter

• Steel plates with scintillating tiles parallel to beam direction Tapered steel plates sampling fraction changes with depth• Divided into two longitudinal sections Measure longitudinal center of gravity correct for longitudinal fluctuations • Plates tilted ± 5o in opposite directions to avoid channeling • Iron in steel serves as flux return

4 inner and 4 outer plates joined together to

form one section

60 cm3.5 labs

30 cm1.5 labs

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HCAL ReadoutSimilar to T2K: Scintillating tiles with WLS fibers embedded in serpentine grooves (Scint:extruded polystyrene made in Russia, WLS:Kuraray Y11)

Fibers embedded in grooves on both sides of tile Expect ~ 12 p.e./MIP/tile (T2K) ~ 400 p.e./GeV in HCAL

T

2x11 segments in h ( Dh =0.1)64 segments in f ( Df =0.1) 1408 x 2(inner,outer) = 2816 towers

2x11 scintillator tile shapes

Inner

Outer

Inner readout(~10x10 cm2)

Outer readout

SiPMs + mixers

8 readout fibers per tower

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Testing HCAL Scintillator ComponentsBNL University of Colorado

Russia

Mixer and SiPM readout

Groved tiles

Extruded scintillator with WLS readout

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SiPM Readout

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Common readout for both EMCAL and HCAL

EMCAL segmentation ~ .025 x .025 (h x f) ~ 25K channels HCAL segmentation ~ 0.1 x 0.1 ~ 3K channels

Considering various devices: Hamamatsu, AdvanSiD, Zecotek,…

Also considering APDs

• Want dynamic range ~ few x 103

10 MeV – 20 GeV per tower

• Due to saturation, must tune light levels to give ~5 – 10,000 p.e.

• Avoid noise a 1 p.e. level

• Requires temperature compensation and control dVbr/dT ~50 mV/°C dG/dT ~ 10% /°C

S10362-33-25C

Zecotek MAPD-3N3x3 mm2, 135K pixels

3x3 mm2,14.4K pixels (25 mm)G ~ 2 x 105, peak PDE ~ 25% @ 440 nm

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Readout ElectronicsLarge signals don’t need ultra low noise electronics Can use a conventional voltage/current amplifierDynamic range essentially determined by SiPM

SiPM preamp with differential output

SiPM preamp impulse response (SPICE)

Readout will use either a derivative of an existing PHENIX ADC system from the Hadron Blind Detector or the CERN SRS system interfaced through the Beetle chip

VB Adj

ORNL

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Summary

• The upgrade from PHENIX to sPHENIX will require the design and construction of two new major calorimeter systems:

• W-SciFi Optical Accordion EMCAL• Iron Scintillating Tile WLS Fiber HCAL

• Both will implement new technologies made possible through the development of new materials, photodetectors and construction techniques.

• Both calorimeters will build on existing and proven designs, but will also incorporate several new and novel designs features that need to be thoroughly understood and tested.

• We feel we have a good, sound basic design concept, but we have a lot of work to do to insure that these detectors will work as we hope.

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Backup Slides

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HCAL Outer

HCAL Inner

EMCAL

Solenoid

VTX

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EMCAL Energy Resolution

Accordion Layers:• Tungsten metal: 2x1 mm• Scintillating fiber: 1 mm• Tungsten-epoxy: 0.08 – 0.20 mm

Sampling frequency: 0.6 X0 Sampling fraction: 4.2%Total layers: 30Total depth: 17.4 X0

Total thickness: 9.5 cm

sE/E ~ 14%/√E

GEANT4 Simulation

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Single Particle Energy Resolution

No CoG weighting

No CoG or E/H weighting

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Total Calorimeter Jet Resolution

Central Au+Au events (HIJING) w/o detector resolution but including underlying events

PYTHIA + Full GEANT4 simulation Recon: FastJet anti-kT, R=0.2

Single jet resolution in p+p collisions

PYTHIA + FastJet + jet energy smearing

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Origin of the Optical AccordionE. Kistenev and colleagues from IHEP circa ~2005

Pb + Scintillator Plate + WLS Fiber