Technology Choices for the sPHENIX Calorimeter Systems C.Woody For the PHENIX Collaboration CALOR12 Santa Fe, NM June 5, 2012

C.Woody, CALOR12, 6/5/ m 70 cm 95 cm 210 cm

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 , 2  in  ) Moderate energy resolution EMCAL ~ 15%/√E HCAL ~ %/√E (single particle) Compact (for EMCAL  small R M, short X 0 ) Hermetic Projective (approximately) Readout works in a magnetic field Low cost C.Woody, CALOR12, 6/5/12 3

Optical Accordion C.Woody, CALOR12, 6/5/12 4 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-  and 

Sintered Tungsten Plates C.Woody, CALOR12, 6/5/12 5 Variable thickness W-plates Scintillating fibers in between Density  ~ 17.5 g/cm 3 Problem is that cannot make sintered plates larger than ~ 20 cm Phase I SBIR with

Tungsten-SciFi Epoxy Sandwich C.Woody, CALOR12, 6/5/12 6 Scintillating fibers 1.0 mm Pure tungsten metal sheet (  ~ 19.3 g/cm 3 ) Thickness: 2x1.0 mm Tungsten powder epoxy (  ~ g/cm 3 ) 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 X 0 sampling X 0 = 5.3 mm R M = 15.4 mm

Effect of Glue on Light Yield C.Woody, CALOR12, 6/5/12 7 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 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

Light Yield and Readout Devices C.Woody, CALOR12, 6/5/12 8 Want 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 Scintillating Fibers Possible Readout Schemes Small reflecting cavity or wavelength shifting block Need to match ~126 1 mm diameter fibers onto a 3x3 mm 2 SiPM with good efficiency and uniformity (  area ~ 2%) 21 mm

Module Construction C.Woody, CALOR12, 6/5/12 9 Tungsten-SciFi “sandwiches” are cast together in 6 layers to form a module ~ 2 cm “tower” in r- , ~ 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 2  (x2 for both sides)

Hadron Calorimeter C.Woody, CALOR12, 6/5/12 10 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 ± 5 o 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 cm 3.5  abs 30 cm 1.5  abs

HCAL Readout C.Woody, CALOR12, 6/5/12 11 Similar 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  (  =0.1) 64 segments in  (  =0.1) 1408 x 2(inner,outer) = 2816 towers 2x11 scintillator tile shapes Inner Outer Inner readout (~10x10 cm 2 ) Outer readout SiPMs + mixers 8 readout fibers per tower

Testing HCAL Scintillator Components C.Woody, CALOR12, 6/5/12 12 BNL University of Colorado Russia Mixer and SiPM readout Groved tiles Extruded scintillator with WLS readout

SiPM Readout C.Woody, CALOR12, 6/5/12 13 Common readout for both EMCAL and HCAL EMCAL segmentation ~.025 x.025 (  x  )  ~ 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 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 dV br /dT ~50 mV/°C  dG/dT ~ 10% /°C S C Zecotek MAPD-3N 3x3 mm 2, 135K pixels 3x3 mm 2,14.4K pixels (25  m) G ~ 2 x 10 5, peak PDE ~ 440 nm

Readout Electronics C.Woody, CALOR12, 6/5/12 14 Large signals  don’t need ultra low noise electronics Can use a conventional voltage/current amplifier Dynamic 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 V B Adj ORNL

Summary C.Woody, CALOR12, 6/5/12 15 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.

Backup Slides C.Woody, CALOR12, 6/5/12 16

C.Woody, CALOR12, 6/5/12 17 HCAL Outer HCAL Inner EMCAL Solenoid VTX

EMCAL Energy Resolution C.Woody, CALOR12, 6/5/12 18 Accordion Layers: Tungsten metal: 2x1 mm Scintillating fiber: 1 mm Tungsten-epoxy: 0.08 – 0.20 mm Sampling frequency: 0.6 X 0 Sampling fraction: 4.2% Total layers: 30 Total depth: 17.4 X 0 Total thickness: 9.5 cm  E /E ~ 14%/√E GEANT4 Simulation

Single Particle Energy Resolution C.Woody, CALOR12, 6/5/12 19 No CoG weighting No CoG or E/H weighting

Total Calorimeter Jet Resolution C.Woody, CALOR12, 6/5/12 20 Central Au+Au events (HIJING) w/o detector resolution but including underlying events PYTHIA + Full GEANT4 simulation Recon: FastJet anti-k T, R=0.2 Single jet resolution in p+p collisions PYTHIA + FastJet + jet energy smearing

Origin of the Optical Accordion C.Woody, CALOR12, 6/5/12 21 E. Kistenev and colleagues from IHEP circa ~2005 Pb + Scintillator Plate + WLS Fiber