sPHENIX EMCAL R&D Craig Woody BNL sPHENIX Design Study Meeting September 7, 2011

C.Woody, sPHENIX Design Study, 9/7/112 Three Approaches 1.Optical Accordion 2.Projective Shashlik 3.Scintillating fiber (similar to Optical Accordion) Issues for each: 1.Absorber material (W vs Pb) 2.Sampling fraction (Moliere radius vs energy resolution) 3.Light Yield (  photostatistics contribution to energy resolution) 4.Readout device (SiPM, APD, PMT ?) 5.Combine with Preshower for total energy measurement

C.Woody, sPHENIX Design Study, 9/7/113 Optical Accordion Fundamental Geometry: Something has to get bigger Volume increases with radius Fibers don’t increase their diameter so either the thickness of the tungsten must increase with radius 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

C.Woody, sPHENIX Design Study, 9/7/114 Progressively Tapered Accordion Plate

C.Woody, sPHENIX Design Study, 9/7/115 Accordion Shaped Tungsten Composite Plates Tungsten Heavy Powder, Inc (San Diego, CA) SBIR submitted November 2010 (not funded) Will be resubmitted (with new preliminary data) September 2011 Density ~ 17.5 g/cm 3

C.Woody, sPHENIX Design Study, 9/7/116 Measure Light Output of Scintillating Fibers with SiPM Collimated Cs137 source Hamamatsu 3x3mm MPPC Trigger pmt BCF 60 1x1mm square scintillating fibers In fixture 3x3 1x9 S.Stoll

C.Woody, sPHENIX Design Study, 9/7/117 Light Output Measurements Scintillating Fibers + SiPM S.Stoll Challenge is to collect all this light onto a relatively small area (SiPM or APD)

C.Woody, sPHENIX Design Study, 9/7/118 Measure Light Output of Scintillating Fibers with SiPM S.Stoll ~41 pe ~44 pe~38 pe ~23 pe Measured light output of a bundle of 9, 1x1mm square BCF60 scint fibers at different source positions (Sr-90 source). Sr-90 source

C.Woody, sPHENIX Design Study, 9/7/119 Projective Shashlik Size of absorber and scintillator plates would both increase as a function of depth Small size improves light collection compared with our current shashlik Again, challenge is to collect all the light onto a SiPM or APD

C.Woody, sPHENIX Design Study, 9/7/1110 Measuring Light Output of Shashlik Configurations S.Stoll SiPM Trigger pmt Tile stack Cs137 source 2 cm

C.Woody, sPHENIX Design Study, 9/7/1111 Light Output Measurements Scintillating Tiles + WLS Fibers + SiPM First started looking at “old” polystyrene scintillator samples from PHENIX EMCAL Then got “new” scintillator samples from IHEP which looked much better Now have additional samples from Uniplast (courtesy of Dimitri & Justin) and are currently in the process of measuring those S.Stoll

C.Woody, sPHENIX Design Study, 9/7/1112 Light Output Dependence on Separator Material pe S.Stoll 14.0 pe 30 mm stack of 22x22x1.5 mm tiles read out with 3x3 mm SiPM

C.Woody, sPHENIX Design Study, 9/7/1113 Sci-Fi Design Study A.Denisov and V.Bumazhnov (IHEP Protvino) Two types of Scintillator+absorber structures have been simulated: 1) “spaghetti” with maximal geometrical sampling uniformity (left figure); 2)”slice” type for simplest mechanical treatment (right figure); Simulations have been performed for calorimeter modules with cross-section of 300mm x 300mm and length of absorber of 200 mm(along of electron beam). The volume scintillator/absorber ratio is of about 30% for both cases. Geometry modification to take into account projective geometry requirements has not been implemented in this simulation yet. We believe that this effect should be small enough. W and Pb absorbers

C.Woody, sPHENIX Design Study, 9/7/1114 Preliminary Results from SciFi Simulation Effective Moliere radius for this type of EMCAL defined as radius for 90% deposited energy containment have been calculated based on simulated 1 Gev electrons: cm for lead (Pb) and 2.0 cm for heavymet (0.98W+0.02Cu); Light yield and energy resolution for 1 Gev electrons with NO inclination angle and hit of calorimeter in between of fibers. Tungsten pre-shower with different thickness was placed just before of the module. It was considered as “dead” material. A.Denisov and V.Bumazhnov (IHEP Protvino)

C.Woody, sPHENIX Design Study, 9/7/1115 Preliminary Results from SciFi Simulation (cont’d) Angle of incidence dependence Uniformity of response No preshower 3 X 0 preshower A.Denisov and V.Bumazhnov (IHEP Protvino)

C.Woody, sPHENIX Design Study, 9/7/1116 SciFi Cal R&D at UCLA for STAR SPACAL Embedding scint fibers in an absorber matrix (Oleg Tsai) UCLA Prototype 0.25x0.25, 0.3 mm fibers 0.8 mm spacing “Spacardeon” Also working with Tungsten Heavy Powder Will likely team up with them on an EIC R&D proposal in the spring

C.Woody, sPHENIX Design Study, 9/7/1117 GEANT4 Simulation (representative of a Shashlik)

C.Woody, sPHENIX Design Study, 9/7/1118 Summary 1.R&D proceeding on three approaches for a Compact EMCAL Optical Accordion Projective Shashlik Sci Fi 2.Light yields in all configurations look promising 3.Simulation efforts have started for several designs 4.Development of a Preshower Detector is also proceeding (in connection with the the MPC-EX- future update by E.Kistenev)