ALICE physics andFoCal upgrade proposal
Tatsuya Chujo
Univ. of Tsukuba
TCHoU meeting, June 2, 2019 @ U. Tsukuba

LHC (2009-)
Creation of larger, high temp. longer lifetimesQGP than that of RHIC

this talk

Temperature

Tc

Crossoverphasetransition

QGP

RHIC (2000-)
Discovery of strongly coupled
QGP(success of hydrodynamics)

Hadron gas

SPS (1986-)
low mass lepton pair enhancement Neutron starmerger?
J/ψ suppression
AGS (1986-1995)
Strong baryon stopping
Elliptic flow (v2): negative →positive
chemicalfreeze-out

Neutron star?

Liquid-Gas
Phase transitionNormal nucleardensity* Neutron star image: https://phys.org/news/2018-09-neutron-star-jets-theory.html

Baryon Density

ALICE 国際共同実験 (CERN)ALICE Physics Papers Timeline | Publications and Article Submissions

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LHC加速器 (2009-)
核子対辺り重心衝突系 Pb-Pb
sNN = 5.02 TeV

2018/11/12 12'31Directory( 約 ２５本/ 年)

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ALICE Physics Papers Timeline240

233 papers submitted
as of 12-11-2018

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http://alice-publications.web.cern.ch/node/4

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40 カ国, 175 研究機関
~1,975 の研究者
LHC で唯一、重イオン実験とクォーク・グルーオンプラズマ研究に特化した実験!3Publications and Article
論文：９年間で約２３０本 (PRL, PRC, JHEP など）
Submissions

http://alice-collaboration.web.cern.ch
http://alice-j.org

ALICE Tsukuba group• Largest ALICE group in Japan– staff 5, students (PD1, M 10, D 1,T 1, G 1): 19•

Team leader: Yasuo Miake– Deputy team leaders: Tatsuya Chujo, ShinIchi Esumi• Roles in ALICE– Construction, installation/ operation of EMCal/DCal (Y. Miake, T. Chujo)– PWG JE convenor (2017-2019), EMCal/DCal deputy project leader(2013-2017): TC– PWG HF-e PAG (-2018): S. Sakai– Major role in FoCal upgrade project• Utrecht U, CiC research invitation program (FY2017-2021)• Deputy PI: N. Novitzky, Utrecht PI: T. Peitzmann (ex-upgradecoordinator), M. van Leeuwen (Physics coordinator)– ALICE Tier 2 center @ Tsukuba (on-going)– http://alice-j.org (ALICE-J homepage, maintained by TC)

41. Jet physics in ALICEDi-jet energy imbalance

6CMS, PRC 84, 024906 (2011)

1) Large energy imbalance isobserved in central Pb-Pb.
ATLAS, PRL, 105 (2010) 252303

pT,1: leading jet
pT,2: sub-leading jet2) Large AJ : low momentum
particle (< 4 GeV/c) emitted
at large angle on away side.

Hard probes in heavy-ion collisions!7• Hard probes:• Originated at the parton hard scattering (large Q 2),prior to QGP formation time (1/Q ≪ 1 fm/c)• Well calibrated (pQCD)• Jets: reflect a whole evolution of the system• Access to the medium properties:• dE/dx of partons (g, q (uds, c, b)) & L dep.)• Large angle emissions• Jet tomography by different probes & techniquesside by D. d’Enterria (slide at QGPWS, 2008)
Picture form Y. Tachibana(Heavy Ion Cafe 2017)

HF jetTatsuya Chujo

Jets in ALICE!8• Jet reconstruction by tracking (TPC+ITS) + calorimetry• Go to low jet pT and low constituent pT (> 0.15 GeV/c for charged) in large heavyion background✓ Detailed characterization of background fluctuations (JHEP 1203 (2012), 053)
✓ Gamma and jet triggers by EMCal/DCal, PHOS for high pT• Measurements:✓ High pT hadrons✓ Inclusive jet✓ Jet + hadron correlations (soft hadron, w/ PID)
✓ Gamma-jet correlations, c/b taged jets, jet-jet✓ Jet substructure

EMCal/ DCal+PHOS
Tatsuya Chujo

(1) Jet spectra and jet RAA
RAA =arXiv 1805.05424”hot/dense QCDmedium”
dnAA /dpT dy=”QCD vacuum”
Nbinary · dnpp /dpT dy!9

arXiv:1805.05635

What can we learn from RAA measurement of jet, beyond energy loss ?
ALICE:• Low pT (< 100 GeV/c): pT dependence of RAA• High pT up to 200 GeV/c by using the current statistics• Complementary to ATLAS/CMS

Tatsuya Chujo

Inclusive charged jet production!10

R. Hosokawa• Submitted to arXiv https://arxiv.org/abs/1905.02536• Comparison to a NLO pQCD-based model prediction(POWHEG+Pythia8)• Good agreement within large theoretical uncertainty– Higher-order (NNLO) calculation will improve scale uncertainties in pQCD calculation– Further understanding of non-perturbative effects (e.g. Underlying events) will also becrucial for low pT region

Jets in Pb-Pb atsNN = 5.02 TeV (Run-2)!11

R = 0.2

R = 0.3

H. Yokoyama

ALI-PREL-159649- Strong suppression of jet in Pb-Pb central.
- p dependence espacial for R=0.2 at lower p- Little R dependence- Charged particle jets and full jets are consistent
ALI-PREL-159653

T

H. Yokoyama, TYL Yonginvestigator award(2017.05, Strasbourg)

TTatsuya Chujo

Jet-hadron corr. in Pb-Pb at

sNN = 5.02 TeV
R. Hosokawa

A slightly wider distribution for out-of-plane in lower pT
associated tracks (0.7 < pT < 2 GeV/c)

Tatsuya Chujo!12

A future direction of jet physic in ALICE

13

3+1 hydro + jet (Tachibana, Hirano) QM2012• ALICE: PID capability for charged hadrons (0.15 – 20 GeV/c), photon, di-jets• Constituents of bulk vs. medium response (large angle emission)• AJ (di-jet energy asymmetry) as a parameter for the energy deposit.
• Use di-jets, γ-jet events.

• Possible new window to : cs, EOS by comparing with theories• Need high rate data taking with jets.

2. Heavy Flavor physics
in ALICEHeavy flavours in heavy-ion collisions● Heavy flavour (charm & beauty)● Large mass : mc (~1.5 GeV/c), mb (~4.5 GeV/c) >> ΛQCD (0.2GeV/c)● Produced initial hard partonic scattering processes● Gluon scattering is dominant LHC → sensitive to gluon
nPDF● Cross section calculate by perturbative QCD (pQCD)● Short formation time τ ~ 1/2 mq ~ 0.07 fm < QGP (~0.1-1 fm)● Produce before QGP and go through the medium● Heavy flavour in QGP● Brownian motion● Sensitive to QGP transportation coefficient● Energy lose via collisional & radiative● QCD prediction ; ΔE(u,d,s)> Δ E(c) > Δ E(b)● a test for QCD in extremely high and dense matter15

Large suppression HF production in Pb-Pb
D meson

16
S. Sakai

HF e■ Large Suppression of D meson productions in Pb-Pb at 5.02 TeV■ Large suppression of electrons from D and B in Pb-Pb at 5.02 TeV■ Indicates significant energy loss of charm and beauty in the QGPHeavy Flavor electrons in small system
HF-e v2

17

S. Sakai, D. Kawana
HF-e RpPb T. Suzuki et al.

- Positive v2 of heavy flavours in p-Pb collisions- RpPb ~ 1 within uncertainties in the whole pT interval• No suppression of heavy-flavour production is observedΛc production in Pb−Pb collisions at sNN = 5.02 TeV 18
Y. Watanabe et al.

Phys. Lett. B 793(2019) 212

Ratio to D0 meson• Larger than that of pp and p−Pb collisions• Described by a model• With charm quark hadronization via quark
coalescence without vacuum fragmentation

Nuclear modification factor• Suggest less suppression than inclusive
charged hadrons and D mesons

3. Open questions

Q1) How QGP is thermalized so quickly ?

20

Unknown !

CGCcollisions?
t = -1 fm

GlasmaQGP

hadron gas?
t = 0 fm

Courtesy of S. Basst= 0.6 fm/c

t= 20
t fm
CGC

• What is the initial condition?
• Why so rapidly thermalized (t=0.6 fm/c)?
• Instability of strong color field？

high densit
color field• No clear evidence for CGC as an initial condition yet.
• initial condition ⬄CGC strong color fields⬄ thermalized QGP
QGP rapid thermalization?

Q2) Origin of ridge, collectivity in small system? 21

Yen-Jie Lee, heavy ion town meeting (2018)

4. ALICE FoCal upgrade
proposal

LHC timeline

23

John Jewett (QM2018)

LHC timeline

Run-2

24

ALICE major upgrade

Run-3

LHCb Phase-I upgrade

ALICE upgrade plan
ATLAS/CMS major upgradeRun-4 (HL-LHC)

Run-5 (HLLHCb upgrade LHC)
plan (phase-II)

Run-5

ALICE upgrade(conceptual)

ALICE FoCal!25

FoCal = Forward Calorimeter:
FoCal-E: EM Calorimeter
FoCal-H: Hadronic Calorimeter• ~7 m away from the interaction point• main challenge: separate γ/π0 at high energy• Si-W calorimeter (hybrid Si: pad 1cm2 & MAPS 30μm2)• Considered as an ALICE upgrade for Run-4• Look for CGC effects at small-x (~10-5)• Origin of Quark Gluon Plasma• main observables: Direct photons, π0 ,π0-π0 correlations

MAPS detectormini-FoCal (PAD)Centralhadron, photons,jets, leptons-0.9 < η < 0.9MFTphotons, hadrons, jets

muons

FoCal

2.45 < -η < 3.

3.5 < η < 5.8γ, π0μμjet

Collision pointCentral

7.5 m

ALICE Forward Upgrade (Run-3/4)

MFT FoCalEM shower separation by FoCal

FoCal-H

FoCal-E(one module)
FoCal-E

10 mm

New kinematic regime explored by FoCal

A region where CGC
signals can be detectedFoCal による単光子測定の精度

単光子の収量比： (p+Pb)/ (p+p)とカラーグラス凝縮 (CGC) の明確なシグナル

CGC なし(通常の原子核効果)

CGC ありA. Rezaeian, PLB 718, 1058

単光子の横運動量

Saturation physics at small-x!30

Physics Impact on PDF for gluons
by FoCalsmall-x

hard process• At small x and small Q2, the parton density becomes large andnon-linear effects (gluon fusion) may set in➡Gluon Saturation, Color Glass Condensate (CGC)• Large uncertainties of nPDFs at small-x
Tatsuya Chujo

mini-FoCal 検出器, CERN-PS/SPS ビーム実験
ユトレヒト大学と日本グループで実施 (2018)
SPS テストビーム実験の様子↑ エネルギー分解能ΔΕ/Ε ~ 6 % @ 150 GeV/c 陽電子(未発表, 暫定結果)← 日本グループが新たに開発した
mini-FoCal 検出器* 日本グループ：筑波大、筑波技術大、広島大、奈良女子大、東大CNS、長崎総合科学大2018 年 ALICE に mini-FoCal 設置
13 TeV pp 衝突でのmini-FoCal データ収集に成功

mini-FoCal
LHC beam pipe
@ ALICE P2

実際の衝突データ (hit map)

FoCal 検出器開発とこれからの国際協力
FoCal-E
PAD 部

FoCal-E
MAPS 部

新たな参加機関
フランス

PAD読出
ASIC

ブラジル

PAD読出

米国

FoCal-H

SAMPA

日本

インド

オランダ

PAD
Si センサー

MAPS
現在の主要な参加機関

Forward Workshop in Tsukuba (2019.03)!34

ALICE実験代表、物理部会長を含む国内外の招待講演者を招き、“International Workshop on Forward Physics andForward Calorimeter Upgrade in ALICE”を開催（国外 10名、国内28名、計38名）
https://indico.cern.ch/event/783989/

筑波大における ALICE Grid Tier2 構築• LHC ALICE Run-3 に向けて

– 日本における ALICE コンピューティング資源の確保・拡充!35– 2019年2月、実効 168 TB RAID ディスク購入(本新学術予算)– 2019年5月、SINET5 (Hepnet-J 経由) に 10 Gbps で接続する
光ファイバー新規導入– （予定）2019年6-7月、Tsukuba T2 運用再開
– Worker node の増設↑購入した RAID ディスク
ZE-G824F16-4G-N8000x24(8TB SATA HDD x 24,

eﬀective 168 TB (RAID6/SPARE1))

https://www.sinet.ad.jp/aboutsinet/interconnectivities

Summary and future plan!36

✓ Physics:• One journal submission in pp (jet)• Two preliminaries in Pb-Pb, and paper is in preparation (jet)• HF: New preliminary (2), p-Pb & Pb-Pb papers (2)• two PhD double degrees (Grenoble-Tsukuba)• H. Yokoyama (2018), R. Hosokawa (2019)• Towards jet with PID• Heavy flavor, baryon/ meson with Jets
• March cone?
• HF-e (Sakai), Gamma (Novitzky), Jet (Chujo)✓ FoCal upgrade proposal:• mini-FoCal projection and successful data taking at PS/SPS andLHC-ALICE (2018)• in 2019: towards LoI and TDR• Final design• Forming new international collaboration (FR, USA, BR)