1. Alternative CEPC Calorimeter
Options
Tianchi Zhao
IHEP, Beijing
Nov. 7, 2017

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

3. Structure of dual readout calorimeter

4. A Dual Readout Calorimeter Tower
Short fibers
Full length fibers
10  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

5. 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?

6. 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

7. 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

8. 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

9. 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

10. 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)
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, Torino, Italy

11. Time for Light to reach PMT Global light start time 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

12. Photon sensors for fiber based calorimeter

13. 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

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

15. 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

16. Neutron compensated calorimeter

17. 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)

18. (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

19. 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

20. 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

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

22. Linearity of protons and pions in Dual Gate Calorimeters

23. 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

24. 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