1. CEPC 数字强子量能器读出电子学预研进展
张俊斌
中国科学技术大学
核探测与核电子学国家重点实验室
2016/8/22

2. OUTLINE BACKGROUND CEPC-Detector CEPC-HCAL DHCAL SDHCAL USTC-SDHCAL
MICROROC
Detector plane overview
Phase I: prototype readout scheme
Microroc & Hardroc2b test board
SDHCAL DIF board
Active Sensor Array board
Status

3. CEPC(Circular Electron Positron Collider)
Beam Energy:
120GeV
Luminosity:
2× 𝑐𝑚 −2 𝑠 −1
Circumference:
53.6km
Higgs factory

4. JET ENERGY MEASUREMENT
Classic Calorimeter
𝐸 𝐽𝑒𝑡 = 𝐸 𝑒𝑐𝑎𝑙 + 𝐸 ℎ𝑐𝑎𝑙
Approximately 72% of the jet energy is measured with the
precision of the combined ECAL and HCAL for hadrons and the jet
energy resolution is limited by the relatively poor hadronic energy
resolution.

5. Particle flow algorithm & calorimetry
PFA Calorimeter
Particle flow algorithm
Charged particles –tracker
Photons – electromagnetic calorimeter
Neutral hadrons – hadronic calorimeter
High-
granular
ECAL: separate energy deposits from photoelectrons and hadrons
HCAL: separate energy deposits from charged and neutral hadrons

6. CEPC-DETector
The CEPC calorimeters, including the high granularity electromagnetic calorimeter (ECAL) and the hadron calorimeter (HCAL), are designed for precise energy measurements of electrons, photons, taus and hadronic jets. The basic resolution requirements for the ECAL and HCAL are about 16%/ 𝐸(𝐺𝑒𝑉) and 50%/ 𝐸(𝐺𝑒𝑉) .
To achieve these, a Particle Algorithm oriented calorimetry system is being considered as the baseline design.

7. CEPC-HCAL AHCAL DHCAL HCAL SDHCAL
A high-granularity HCAL plays an essential role in CEPC. It allows separation of energy deposits from charged and neutral hadrons. The measurement accuracy of the neutral hadrons is the leading contribution to the jet energy resolution for jets with energy up to 100GeV.
sampling calorimeter (steel + Gaseous detector)
AHCAL
Scintillator + SiPM + SPIROC(ASIC), channels,1m3
HCAL
DHCAL
GEM/RPC/Micromegas + DCAL(ASIC), 4× chn/m3
A hadron calorimeter with only one threshold readout is
called a Digital Hadron Calorimeter (DHCAL).
SDHCAL
GEM/RPC/Micromegas + HARDROC(ASIC), 4× chn/m3
A more general calorimeter with multi-threshold readout (e.g. 3 thresholds) is therefore also considered, a so-called Semi-Digital Hadron Calorimeter (SDHCAL).

8. DHCAL Architectural of the DHCAL
The first 1 m3 RPC-based DHCAL prototype built at Argonne National Laboratory(ANL) in 2010
Architectural of the DHCAL
54 layers with 1m2 area per layer. Each layer has 2cm iron absorber.
The first 38 layers have a uniform thickness of absorber, while the last 16 layers increase of the absorber thickness from 2cm to 10cm, used as tail catcher for very high energy particles
The prototype has about half a million channels

9. DHCAL-readout system
Multi-muon tracks passing through

10. SDHCAL
An SDHCAL prototype was built by IPNL.
comprising 48 active layers
Each layer is made of 1 m2 GRPC, which readout through 9216 pads of 1cm2 each.
An 80GeV pion event display with red indicating pads fired at the highest threshold, blue those at the middle threshold, and green those at the lowest threshold.
The use of the three thresholds has a very good impact on the energy resolution at energies higher than 40GeV. Excellent linearity and energy resolution up to 80GeV were obtained during the two periods of beam exposure at CERN.

11. SDHCAL-readout system

12. USTC-SDHCAL PADs readout
Approximatively, 95% Energy included longitudinal length:
L(95%)=[0.56*ln(E/GeV)+2.33] λI
E=100GeV, L(95%)=4.9 λI =82.2cm(Fe)=48.7cm(W)=75.1cm(Cu)
The energy resolution of HCAL will be improved by using more sampling layers, but it won’t work any more when d<2cm (for Fe) .
95% Energy included transverse radius: ~30cm for 50GeV π±, 99% hits in 70cm× 70cm.
PADs readout 70 cm

13. microroc
Multi-thresholds
channels
Dynamic range
Hardroc2 64
10fC~10pC
Hardroc3
10fC~50pC
Microroc
1fC~500fC
MICROROC is dedicated chip for GEM/MICROMEGAS. MICROROC (pin pin compatible with HR2b) is based on HR2b same back-end, same readout format, same pinout, only the preamplifier is changing.

14. Microroc Gain =4 1fc~500fC Gain =1
The noise of the PAC followed by the HG shaper (tp=200 ns) have been simulated and found equal to 0.25 fC which allows to set the threshold of the discriminator that follow the HG shaper to a very low value such as 2fC.

15. Detector plane overview
1m2 detector plane: 4 ASUs
Detector plane characteristics:
PCB with buried blind vias.
36 MICROROC chips / ASU
9216 channels / plane
1.2mm max thickness (PCB)
All components on top < 1.4mm
ASU-ASU
Connector
DIF
Detector InterFace
ASU
Active Sensor Unit

16. Ustc SDHCAL readout for future

17. ECAL&HCAL readout for future

18. Phase I : prototype

19. Microroc & Hardroc2b test board

20. SDHCAL DIF board

21. Active Sensor Array board
Active area:30𝑐𝑚×30𝑐𝑚
900 pads in total (4 pads unused)
14 connectors
Layout Cross Section:
GND--SIG1--GND--SIG2--GND--SIG3--GND--PADs
(Top bottom)

22. Kapton cables
Test board DIF
Test board ASA board

23. Status status Test board √ DIF board Active Sensor Array board
Test board DIF (Kapton)
ASA board Test board(Kapton)
FPGA firmware
just started
Application software

24. END