Alternative CEPC Calorimeter Options Tianchi Zhao IHEP, Beijing tianchi@u.washington.edi Nov. 7, 2017

Outline Structure of dual readout calorimeter Photon sensors for fiber based calorimeter Neutron compensated calorimeter

Structure of dual readout calorimeter

A Dual Readout Calorimeter Tower Short fibers Full length fibers 10  2-2.5 m Total number of PMTs determined by readout granularity and total area of the calorimeter outside surface area End face of a tower 5 cm OD = 8 m, L = 8 m Total area = ~300 m2 Barrel = ~200 m2 End caps = 2 x 50 m2 Total PMTs = 2 x 400 x 300 = 240,000

An Alternative Readout Scheme Scintillation light readout from front end SiPMs (S-fibers) (C-fiber) Cherenkov light from back end All full length fiber Sampling ratio changes 10 （> 2 m） TOF for particle ID Scintillating light Cherenkov light Shower time profile Correct light attenuation Correct sampling ratio change Particle arrival times (front and back) PFA friendly?

Modify RD 52 Dual Readout Calorimeter Cell All long fibers span the entire calorimeter depth Sampling ratio changes with the depth 1.0 mm 2.0 mm Front 1.5 mm 1.0 mm 3.0 mm Back

Another tower configuration Cu ~ 60% Fiber ~ 35% Air ~ 5% RD52 coper module (2012) 1 mm 1.5 mm 1.5 mm X0 ~ 2.4 cm lint ~ 25 cm 1 mm 1.5 mm Front 1.5 mm Another tower configuration (average ~ 20 cm) 1 mm 2.0 mm Rear 2.0 mm

Modified Wigmans DREAM Prototype Cell Front 4.0x 4.0 mm2, back 6.0 x 6.0 mm2 hole 2.5 mm x 2.5 mm Cu 4.0 2.4 S C Frond face (64% Cu) 6.0 mm Back face (84% Cu) Average Over the Length int ~ 19 cm 10 int ~ 190 cm

Optimize the Performance of EMCal Use a dense absorber material in front section of the tower Use fine readout segmentation (e.g. 4 mm x 4 mm) Tantalum Back face (84% Cu) Frond face (64% Ta) Cu Ta EM Section Parameter X0 ~ 0.5 cm Rm ~ 1.4 cm 2.4 S C 2.4 S C Can be as good as or better than the W/Si EMCal 4.0 mm 6.0 mm

Radiation length (X0) (cm) Nuclear Interaction length EM section may be made from Tantalum Material Radiation length (X0) (cm) Density (g/cm3) Molière radius (cm) Nuclear Interaction length Tungsten (W) 0.35 19.3 0.93 9.65 Tantalum (Ta) 0.41 16.6 1.07 11.5 Lead (Pb) 0.56 11.3 1.60 17.6 Copper (Cu) 1.44 8.96 1.57 15.3 BGO Crystal 1.12 7.1 2.3 21 A tantalum beam calorimeter built in 1995 was quoted as 1k CHF/kg. Should be much cheaper if made in China. Ref. A position sensitive highly radiation hard and fast hadron calorimeter for a lead ion experiment at CERN SPS Nuclear Instruments and Methods in Physics Research A 367 (1995) 267-270 E. Chiavassa, G. Dellacasa, N. De Marco, M. Gallio, P Guaita, A. Musso *, A. Piccotti,,E. Scomparin, E. Vercellin INFN - Ser. di Torino and Dipartimento di Fisica Sperimentale. Universifu’ di Torino, I viu P. Giurirr, 10125 Torino, Italy

Time for Light to reach PMT Global light start time 0 40 80 120 160 200 15 10 5 Depth in calorimeter tower (cm) Scintillation light arrival time (ns) Time for Light to reach PMT Global light start time 18.5 ns 6.7 ns Time profile of waveform is potentially useful Forward high energy particle speed ~ 30 cm/ns scintillation light speed ~ 17 cm/ns Effective light speed ~ 11 cm/ns

Photon sensors for fiber based calorimeter

Attaching SiPMs modules Directly to the end face of towers SiPM modules used in commercial TOF-PET scanners 25 mm PMT size: 25 mm x 25 mm Pixel size: 3 mm x 3 mm 4 mm x 4 mm

Example of SiPM Modules used in medical TOF-PET int ~ 19 cm UV sensitive SiPMs Exist

Readout Fiber Calorimeter by MCP-PMTs We believe we can develop and make MCP-PMTs at an affordable cost in China MCP-PMTs can work in strong magnetic field to some level

Neutron compensated calorimeter

Space -Time evolution of Hadron showers and its use in hadron Calorimetry E. Auffrey, A.Benaglia, P. Lecoq, M. Lucchini, A.Para, H. Wenzel CPAD Workshop October 10, 2016 Also TICAL ERC Grant, P. Lecoq et al This effort was started by Adam Para and myself in 2005 at Fermilab (I stopped working on this around 2010)

(EM components and direct charge particles) Global Time of Fast Signals in Calorimeter Tower (EM components and direct charge particles) Fast signals are generated in a fraction of ns locally and propagate to the light detectors within nanoseconds

Neutron Signals are Much Slower (normally invisible) are much slower due to the nature of hadron shower generation. The time requires to collect neutron signals: W: ~ a few 100 ns Fe: ~ a few s Pb: many s 4 mm W – 1 mm Sc 4 mm Pb – 1 mm Sc 4 mm Fe – 1 mm Sc Neutron signals and time profile can be used to make compensated calorimeters

Dual gate compensation Geant4 simulation Hadron Calorimeter compensated using ratio of Fast/Slow Signals Neutron signal time profile can be used to compensate the “invisible” energy loss in hadron showers based signal time profile and achieve E/H =1 Dual gate compensation Geant4 simulation Dual readout Scintillation + Cherenkov Dual Gate = 1.5 ns = 10 s

Capability of Dual Readout and Dual Gate Calorimeters Can completely eliminate the constant term in resolution function

Linearity of protons and pions in Dual Gate Calorimeters

Realization of Neutron Compensated Calorimeter (1) Based on conventional hadron calorimeter designs CDF, ZEUS, ATLAS, CMS, ILD, etc. W is preferred for capturing neutron signals Absorber tiles: W, Cu, Pb, S.S., ····· Active material : Scintillator, LAr, silicon Main signals : Ionization or Scintillation Compensation: Signal time profile (waveform digitization) or short/long signal integration gates PFA can be used if segmentation is fine enough

Realization of Neutron Compensated Calorimeter (2) Based on the Spaghetti calorimeter with scintillation fibers only Main signals : Scintillation Compensation: Signal time profile (waveform digitization) or short/long dual gates Fast PMT Scintillation fibers only PFA can be used if segmentation is small enough