ALICE FoCal Project
Tatsuya Chujo(University of Tsukuba)
TCHoU member meeting, November 28, 2022, Tsukuba

2

1. INTRODUCTION:
FoCal physics

QCD phase diagram 3TQuark Gluon Plasma(QGP)

Chiral Symmetry

High Energy
Nucleus-Nucleus Collisions

Crossover Phase
Transition

TPC

CERN (Switzerland)
LHC (2009-), 27 km
sNN = 2.76, 5.02 TeV Pb-Pb•

Creation of QGP in thelaboratory•

Properties of QGP, Restorationof Chiral Symmetry, Origin ofnucleon mass

Chiral SB

Neutron Star Merger
Interior of Neutron StarChiral SBHadron⟨q̄q⟩ ≠ 0Normal Nucleus

Baryon density* Neutron star image: https://phys.org/news/2018-09-neutron-star-jets-theory.html

A Journey through QCD•

ALICE white paper (10 years of ALICE)•328 pages, summary of Run-1 andRun-2 physics results•

https://arxiv.org/abs/2211.04384•

Submitted to arXiv on November 8th,
2022

4

5

How QGP is created?
-1

00.6

20

Time t (fm/c)

Thermalization: ~0.6 fm/c

CGC?
(undiscovered yet)collision

New research©︎ S.Bass

Quark Gluon Plazma(QGP)

Hadronization

Freeze-out

On-going research

Three Open Questions
Q1) What is the creation mechanism of QGP?
Q2) Why QGC rapidly thermalized?
Q3) Does Color Glass Condensate exist?

Q1 and Q2: Possible scenario of QGP formation
Before collision

Thermalization ~0.6 fm/c

After collision
Color Electric/Magnetic
Fields: E, BA

A(1) Color GlassCondensate(2)
Productionof ColorElectric andMagneticFields(3)
Productionof Quarks
and Gluons

Ridge formation?

(4) QGP Formation(5) Hadron Gas

67

PDF: Parton Distribution Function
PDF:
Probability density of quarks and gluons as a function of themomentum fraction

x = pq,g / pp ,depend on the wave length (Q2)u, d quark PDF (1/3)

Sea quark PDF

Small xLarge xLarge uncertainty at small x

EPPS16x

2Pb
2R g (x, Q = 10 GeV )Gluon PDF in proton

2Pb
2R g (x, Q = 1 .69 GeV )Gluon PDF in nucleus

8

Q3: Appearance of Color Glass Condensate (CGC)- Initial condition for QGP formationNormal
Proton, Neutron

Color Glass Condensate (GCG)x≈Large x

2pTs

Small x~９０° (η is small)~０° (η is large)

Low energy ( s small), pT Large
g→gg

g →gg
gg →g

High energy ( s large), pT small

η = − ln(tan(θ/2))
K. Watanabeexp−ηThe FoCal project- Forward Calorimeter- Endorsed by LHCC as an

FoCal-H

FoCal-E

Hadron Calorimeter

Electromagnetic Calorimeter

upgrade project towards TDR(Technical Design Report) for
LHC Run-4 (2029-)- TDR in 2023 summer

z=7m

Collision Point
3.2 < η < 5.8

Observables:••••

π0 (and other neutral mesons)
Isolated (direct) photons
Jets (and di-jets)
J/psi, UPC

η = − ln(tan(θ/2))
FoCal Public Note (LoI) : CERN-LHCC-2020-009

9New physics explored by zero degree frontier at high energy
θ=90°η=0• FoCal can access to …
① Forward→ Zero degrees② Higher energy→ Highest collision energy at LHC

θ=0°

Put detector at very
forward region③ Sensitive probe → Photons④ proton < Lead

→ Heavy ion acceleration at LHC

Q ~ pT (Transverse Momentum)（GeV)

LHC
New regime to be explored

Direct measurement of gluon
density by “photons”(penetrating and sensitive probe)

by FoCal

6 times faster to create CGC
by using Lead nucleus

Satisfied all 4 points,
Access to the new regime
to detect CGC clearly
for the first time
→ Physics case is compelling

Expected region
for CGC

Higher energy/ more forwardx≈

2pTsexp−η101. Quantify nuclear modification of the gluon density at small-x• Isolated photons in pp and pPb collisions

2. Explore non-linear QCD evolution• Azimuthal π0-π0 and isolated photon-π0 (or jet) correlationsin pp and pPb collisions

3. Investigate the origin of long range flow-like correlations• Azimuthal π0-h correlations using FoCal and central ALICE(and muon arm?) in pp and pPb collisions

4. Explore jet quenching, color field strength at forward rapidity• Measure high pT neutral pion production in PbPb

EPPS16x

R gPb (x, Q 2 = 10 GeV2)

FoCal: Physics goals

R gPb (x, Q 2 = 1 .69 GeV2)

11EPPS16x

12Determination of gluon distribution in Pb nucleus by FoCal- Isolated photon measurement -Rgp-Pb / p-p4

nNNPDF10208Pb reweighting

3EIC fit 90% CL
FOCAL refit 90% CLQ2=10 GeV2

Current
Uncertainty

2

Determine 1for the
first time
by FoCal
010−610−510−4

10−310−2

New regime to be explored by FoCal

10−11xQ ~ pT (Transverse Momentum)（GeV)nNNPDF 90% CL

New regime to be explored
by FoCal

Expected region
for CGC

Higher energy/ more forwardx≈

2pTs

exp−η

Energy loss in Color E/B fields in Pb-Pb

13

Color Electric/Magnetic Fields E, B

Nucleus

Nucleus

FoCal
Suppression of π0 yield?
Forward direction

Energy loss in ColorField？

π014

Physics in Extreme; Strong fields (gravitational, electromagnetic, color)
Magneter
Strong magnetic field

Early Universe
Strong Gravitational, color, E/M fields

強いカラー場・電磁場

Heavy Ion Collisions
Strong color field, Strong magnetic fieldElementary particle, nuclear physics

High Intensity Laser

Black hole

Strong Electric field

Strong gravitational field

Material physics

Astrophysics

15

2. FoCal detector

List of institutes participating in FoCal (LoI, 2020)

ALICE-FoCal collaboration
34 institutes, 12 countries

FoCal Japan Group

7 institutes and 24 members

๏ University of Tsukuba✦ Responsible: FoCal-E pad (all)✦ T. Chujo, (N. Novitzky), Y. Miake, A. Ghimouz, S.

Sakai, T. Kumaoka (D3), Y. Asatani (M2), T.
Kawaguchi (M2), K. Sato (M2), T. Inukai (B4)๏ Tsukuba University of Technology✦ Responsible: FoCal-E pad electronics, IV/CV,

probe station, module assembly✦ M. Inaba๏ Hiroshima University✦ Responsible: Integration✦ T. Sugitate๏ Nara Women’s University✦ Responsible: test beam, IV/CV temp dep.
✦ M. Shimomura, T. Hachiya, M. Hata (B4)๏ RIKEN✦ Responsible: Irradiation test, trigger✦ Y. Goto, I. Nakagawa, R. Seidl, M. Kim(PD), S.

Shimizu (PD), (T. Kumaoka, JRA D2)

๏ Nagasaki Institute of Applied Science✦ Responsible: CRU, trigger✦ K. Oyama, (one PhD student)๏ Saga University✦ Responsible: CRU, trigger✦ T. Fusayasu, T. Ishida (M2)

Detector design
FoCal-E

20 layers of W(3.5 mm ≈ 1X0) + silicon sensors:
Two types: Pad (LG) and Pixel (HG)

• Pad: shower profile and total energy• Pixel: position resolution to resolve overlapping showers
Separate γ/π0 at high energy
Two photon separation from π0 decay (pT=10 GeV, η=4.5) ~5mm

• Requires small Molière radius and high granularity readout• Si-W calorimeter with effective granularity ≈ 1mm2
FoCal-H

Longitudinal profile (2γ showers)

Trans. profile

Conventional metal-scintillator design
Sampling / tower structure not yet defined
No longitudinal readout required

18

19

FoCal integration
Module:18 PAD layers + 2 PIXEL layers
16 cm

8 cm

FoCal-H

45 cm

FoCal-E

FoCal-E: 22 modules

20

FoCal R&D status
1.FoCal-E PAD
2.FoCal-E PIXEL
3.FoCal-H

CERN EP Newsletter (March, 2022) on FoCal test beam in 2021:
https://ep-news.web.cern.ch/content/towards-focal-alice-experimentFoCal PS/ SPS test beam in 2021/2022
FoCal-E PAD & PIXEL• June @ PS, CERN (<15 GeV h, <5 GeV e)• Sep. & Nov. @ SPS, CERN (<200 GeV, h and e)
FoCal-E• 18 single pad, and 2 pixel layers• PAD: HGCROC for PAD w/ aggregator board• PIXEL
FoCal-H• 9 modules, 3x3• Each module: 6.5 x 6.5 x 110 cm3PIXELFoCal-H21PS test beam, T9 line (2022.06)

22

PS test beam (2022.06)

23

24

FoCal-E PAD sensor
1 cm

First time use of p-type for FoCal (2021, Feb., ELPL)
1 cm

calibration cells

Main cell- 8x9 cells + calibration cells (w/Al), produced 30.
- More rad. hard than n-type.
- used APV25 hybrid board, compatible with HGCROC (readout
ASIC for final detector).

- Seen clear MIP signal (cosmic etc.), 25-33 ADC counts,
10-15% variation.

Histogram: MIP peak position
Numbers: Dark current from Hamamatsu

103Channel: 76
Gaus: mean = -0.68 ± 0.06
σ = 4.69 ± 0.04
mpv = 28.06 ± 0.38
Landau:σ = 3.79 ± 0.24
Corrected MIP pos: 28.74

Hamamatsu S16211-0813
p-sub, 320 um, w/ Al,back side (Au)

1 cm2 pad cell size

1004418

1978

8

3

3413

3

53

464 5551

30150

ADC

ELPH (Tohoku U.) test beam 2021

3351

36

332489

20
32

O.L.

148249

O.L.

4873

14

4642

633152 O.L.

33333

325

30

10O.L.

354

735433359828

4359513281503821

100425y padfront side (w/ Al)

entries

102

640024x pad

6850

FoCal-E PAD : Results
Position scan by hadron beams (15 GeV/c)
Clear MIP peaks have been observed for(almost all) channels layers
Extracted position scan for each layers:• Study the edge-effect of the silicon sensor• Data analysis is on-going.
Full depletion around 300 Vyx25

SPS test beam, H6 line (2022.09)

HCalECal26

SPS test beam, H6 line (2022.09)
ECal PAD

ECal PIXEL

27

SPS test beam, H6 line (2022.09)

LTU
LV

CRU

PIXEL readout
FLP

Source meter(vias V for PAD)

28

SPS test beam, H2 line (2022.11)

29

SPS test beam, H2 line (2022.11)

30

ADC distributions around hit (Layer 0)
K. SatoMIP peaks

QC plot
FoCal-E PAD hit map
Run: 1327 (Nov. 6, 2022)
Hadron beams at 350 GeV
SPS H2

Beam energy scan for FoCal-E pad
TOT (Time over Threshold) outputs
for different beam energies forelectrons
Layer 7, Channel 61 only- TOA threshold = 250- TOT threshold = 350
Energy resolution (TOT only)
Resolution (%)

K. Sato15

M. KimData (no layer5)
Simulation (no layer5)
Simulation

Preliminary

105~ Charge

0050

100

150200250

Energy (GeV)2) FoCal-E PIXEL @ SPS test beam in 2021
(Bergen, Utrecht / Nikhef, LTU, Kharkov)

60 GeV,
hadron60 GeV
hadron+e• Full illumination of the ALPIDE layers at layer 5
and layer 10• Observation of electromagnetic showers in bothlayers• Deviation between data and simulation in theorder of 10% or smaller

332) FoCal-E PIXEL @ SPS test beam in 2022
(Bergen, Utrecht / Nikhef, LTU, Kharkov)

343) FoCal-H• Spaghetti-type calorimeter• Copper tubes- outer diameter 2.5 mm- inner diameter 1.2 mm• Scintillator fiber- diameter 1.0mm- 36 x 40 = 1440 fibers• Module Size: 95 x 95 x 550 mm3• Si-PM: Onsemi MICROFC-60035-SMT-TR1
with 35 µm cell
• Two CAEN A1702 boards for readout

35

FoCal-E and FoCal-H combined analysis (2022 SPS, Nov)

ADC (ch)(Copenhagen, Sophia)3. Future Plan

Timeline

37

Final R&D in 2022 towards Technical Design Report in 2023
Production in 2024-2026, Installation in 2027, Physics data taking in 2029-2032 (LHC Run-4)

38Plan in Japan (2022-2023)
1. PS test beam (06.2022) [done]
2. SPS test beam (09.2022), CRU-FLP readout, common for PIXEL and HCal [done]
3. 2nd RANS test @ RIKEN for irradiation test (regulator, Si sensor) (1.2023)
4. SPS test beam (11.2022) [done]
5. KEK PF-AR test beam (2023)
6. Probe station in Japan operational [~done]
7. HGCROC v2 packaging (3.2023) [ongoing]
8. New PCB production (single/ 5 pad layer) (3.2023), and module production
9. ELPH test beam (02.2023)

Probe station for large sensors in Japan (1)39(M. Inaba)

40

RANS irradiation test

March 3-4, 2022, RANS at RIKEN- Monitor PD, baby chips were used

- irradiated ~1014 neutron /cm2 in two days
- Future: IV, CV test, components irradiation test
n-typep-typeIndium foils

PCBs with sensors(M. Inaba)41Temp. dep. of I/V for p-type sensor

2 x 2 baby chip

• I/V curves for 2x2 and 1x1 babies have been measured at Nara
Women’s Univ. before the irradiation.

• Initial measurements after irradiation was done (April, 2022)(M. Hata, T. Hachiya,
M. Shimomura)Setup in Saga Univ.

Being operational (Aug. 2022)

42

FoCal-E pad trigger and readout scheme discussion

43(K. Oyama)• Towards the final design of integrated readout for all subsystems.

Trigger simulation (T. Kumaoka)

Timeline

44

Physics data taking in 2029-2032 (LHC Run-4)

ALICE3 & FoCal+? (Run-5, 2035-)

ALICE3 LoI in arXiv
https://arxiv.org/abs/2211.02491
https://alice-collaboration.web.cern.ch/alice3

CGC, Glasma

QGP production, Chiral symmetry
restoration @ high T45

46

EIC eA vs. LHC HI- At BNL, EIC will start to operate in 2032

- A high luminosity polarized e, p / ion collider at √s = 28-140 GeV- Factor 100 to 1000 higher luminosity as HERA
- ECCE has been recommended as “Detector-1” by DPAP (Mar.
2022) → EPIC

Good synergies
with EIC

CGC, initial condition ofHeavy IonDetector
Technology→EPICZDC design for EIC47Summary• FoCal has unique capabilities to access the origin of Quark-Gluon Plasma at LHC• New technology: Silicon-tungsten + Pixel hybrid detector for ECal and HCal
• Final R&D and evaluations are ongoing towards Technical Design Report• FoCal in Run-4: New ALICE apparatuses for new discoveries* Plan to have an international workshop in Tsukuba on Forward Physics and FoCal in March 2023

Thank you for your attentions !