LHC_8:
Measurements of Jets andPhotons in Heavy Ion Collisions
at the Highest Beam Energy
during the LHC-Run 2 by ALICE
Hiroshi Masui, University of Tsukuba!
2014 Joint Workshop of the France-Japan (TYL/FJPPL) and France-Korea(FKPPL) Particle Physics Laboratories, May 26-28, 2014

H. Masui / Univ. of Tsukuba

1Outline• Quark Gluon Plasma• ALICE experiment & Di-jet Calorimeter• Activities in FY2013• Plan for FY2014• Current & future activities• Summary

H. Masui / Univ. of Tsukuba

2

QCD matter in high temperature
QCD phase diagram from BNL web site!
http://www.bnl.gov/bnlweb/pubaf/pr/photos/2012/07/RHIC_Graphics_Fig1-HR.jpg• Hadron gas to Quark

Gluon Plasma (QGP)
phase transition at T ~150-170 MeV‣ from Lattice QCD• LHC (and RHIC) would

be able to access suchhigh temperature regime
with ultra-relativistic
heavy ion collisions• Study the properties ofQGP‣ QGP state in a few µsec

after big-bang

H. Masui / Univ. of Tsukuba3ay of hadrons resulting from the fragmentation of an outgoing parton 10iset”.
10Jet quenching (energy loss of parton in QGP)
10-9

Study QGP properties by hard probes-110246810121416182002468101214p (GeV/c)
T161820p (GeV/c)T”hot/dense
QCDmedium”
dnAA/dpand
Fig. 15. Invariant+0 yields measured
by PHENIX in peripheral(left)
T dycentral (right)
R==
AA
AuAu collisions(squares)[89], comparedto the (TAA -scaled)
pp → +·0dn+ X crosssection (cir”QCDvacuum”
Nbinary
pp /dpT dycles) [134] and to a NLO pQCD calculation (curves and yellow band) [119].
RAA

Au+Au - 200 GeV (central collisions):
Direct 2 , 2 * [PHENIX]
Inclusive h± [STAR]+0 [PHENIX]. [PHENIX]g
GLV energy loss (dN /dy = 1400)

10Ncoll scaling

110-1

Npart scaling

quenching” in a head-on nucleus-nucleus collision. Two quarks suffer a hard scat02468101214161820p(GeV/c):8"."/",#%&$%*,*"+01*-.0&)"
goes
out directly
to the vacuum, radiates a few gluons and hadronises, the otherTh the dense plasma created (characterised by transport coefficient q̂, gluon density
Fig. 16. RAA (pT ) measured in central AuAu at 200 GeV for +0 [89] and . [135] mesons,5&")!/
temperature T ), suffers energy loss due to medium-induced gluonstrahlung andcharged hadrons [114], and direct photons [136, 137] compared to theoretical predictions forments outside into a (quenched) jet.
parton energy loss in a dense medium with dN g /dy = 1400 (yellow curve) [138].

,,/".20&,+0),3". ,))&!&+$
Probe: hard processes (jets&photons) - calculable in pQCD
"*"+".$5"$
the first proposed “smoking guns” of QGP formation was “jet quench-•;8&/--".+",# (0,('"0/Strong suppressionof highp hadrons at RHIC & LHC•+".$5),//7#"3"#*

top RHIC energies is very close to the “participant scaling”, (N part /2)/Ncoll ≈ 0.17,. the attenuation or disappearance of the spray of hadrons resulting fromexpected in the strong quenching limit where only hadrons coming from partons
T at the surface of the medium show no final-state modifications in theirproducedntation of a parton having suffered energy loss in the dense plasma prospectra [141]. From the RAA one can approximately obtain the fraction of energy
he reaction (Fig. 2). The energy lost by a particle in a medium, &E, prolost, !loss = &pT /pT , via‣amental information
on its properties. In a general way, &E depends both1/(n−2)!loss ≈ 1 − RAA,(36)
acteristics of the particle traversing it (energy E, mass m, and charge) andparton energy loss in QGP• Jet tomography (di-jet, gamma-jet correlations), soft hadron++,0"4-)&+"!5%!.,+$/

ma properties (temperature T , particle-medium interaction coupling1when', the AuAu and pp invariant spectra are both a power-law with exponent n, i.e.
ess L),9+",#0%""2&!"+i.e. &E(E, m, T, ', L). The following (closelyrelated) variables1/p
areT dN/d pT # p−n [142].
pedestaland flow
At RHIC(n ≈ 8, RAA ≈ 0.2), one finds !loss ≈ 0.2.
"/,#T
useful to characterise the interactions of a particle inside a medium:
The high-pT AuAu suppression can be well reproduced by parton energy loss

production associated with jet#,.*0&,+models that assume the formation of a very dense system with initial gluon ra-T. Chujo,2013)Jointof FJPPL()(TYL)
Yonsei Univ.
Seoul, Korea, June 4, 2013
an free path ( = 1/()*),
whereis theWorkshop
medium density# T 3andfor FKPPL,
ang /dypidity
densitiesdN≈ 1400 (yellow line in Fig. 16) [138], transport coeffi2,as) and * the integrated cross section of the particle-medium interaction
H.inMasui/ Univ.
Tsukubacients ⟨q̂⟩ ≈ 13 GeV2 /fm (red lineFig. 17,left)of[78],or plasma temperatures

4

ALICE experiment
EMCal
Lead-scintillator sampling calorimeterΔη=1.4, Δφ=100o

TPC
Charged particles tracking + PID
Δη=1.8, Δφ=2π

PHOS
EMCal based on leadtungstate crystals (PWO)
Δη=0.24, Δφ=100o• Strength of ALICE; low p (downTto pT ~ 150 MeV/c), and various
PID techniques
H. Masui / Univ. of Tsukuba

5Di-jet Calorimeter (DCAL)
DCAL
beam view

PHOS• DCAL - extension of EMCal acceptance‣ Δη=0.7, Δφ=66o on opposite side of EMCal → allows hadron-jet, di-jet

measurements in ALICE, with R=0.4, up to pT ~ 150 GeV/c‣ Energy resolution ~ 10%/√E• Enhance photon, jet trigger capability
H. Masui / Univ. of Tsukuba

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Activities in FY2013, LHC_5• DCAL‣ Installed half of DCAL super modules (C-side) in Nov. 2013

- see short movie for installation in youtube http://www.youtube.com/watch?
v=91BQB405rkQ‣ Firmware preparation for readout electronics since Dec. 2013
‣ EMCAL, DCAL C-side commissioning in Mar. 2014

• ALICE Physics analysis and Tier-1/2 workshop at Tsukuba inMar. 2014

‣ http://indico.cern.ch/event/274974!

• Data analysis‣ Preliminary results on π0-hadron in p+p and Pb+Pb, π0-jet correlations

in p+p collisions are presented in Quark Matter 2014 conference lastweek
H. Masui / Univ. of Tsukuba

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ALICE workshop at Tsukuba in Mar. 2014

The workshop is sponsored by
Japan Society for Promotion ofScience (JSPS), France-JapanParticle Physics Laboratory (FJPPL),University of Tsukuba, andHiroshima University• France-Japan analysis workshop to discuss ALICE physics,
ALICE detector upgrades• T1-T2 workshop for the status of Grid computing in LS1H. Masui / Univ. of Tsukuba

8

rgy>

ww
w
Analysis
resultsand discussEi● 2 photons merged cluster

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tot

i

tot

ALI-PERF-29549

Fig.5&λ &v
w=Max (0, w +log()), w =4.500Eandπ-jetcorrelationes π -hadronV1 clusterization® Azimuthal angle correlations
Modification
where i is a cell®
of thecluster, 0⩽η <48,0⩽ϕ <24. of perwhere$i&is$a$cell$of$the$clusterngle Method 1: smaller shower shape cluster with V2 clusterizer
Xiangrong Zhu (CCNU/LBNL)
Photon(:(ppPb-Pbed.
 Select V2 clusters identified as photon candidates Cluster&selec4on
via shower
20cell0cluster0ii0.1)<)λ02)<)0.27)

shape cut (0.1 < l0 < 0.27)• andcharged particle veto.
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over all clusters, shownλ02)>)0.5))
of$the$calorimeter$
In the V1 clusterizer, thein the right figure upper. A Gauss+3rd order polynomial
is fitted2)par1cles)cluster)
decayphotons“EMshowers”• Clusters$must$contain$at$least$4$cells$$sto the distribution between 8.0 < pT < 15.0 GeV/c (Figure 2).
start to merge at 6 GeV. The• Removal$of$the$cluster$containing$a$bad$ch
 Method 2: larger shower
shape cluster + cluster splitting
fraction of merged photons
7(with V1 clusterizer(high$energy$deposi;on$in$a$single$tower$d0increases with p energy. It is.4&The&shower&shape&geometries&of&direct&photons&and&decay&photons.&& A V1 cluster with l0 > 0.5 issplit into two new clusters.
neutrons)$
larger than 50% above 10 GeV.
 Every new cluster is centeredaround seed cells with local•
Timing$cut$:$?25$<$;me$<$20$ns$and Emin in this analysis:
maximal energy and formed with maximum of 3x3 cells.
• Charged$par;cle$veto$:$track$matching$Δφ= 100 MeV, Emin = 50 MeV (V1, V2)
 If cells are common to bothclusters, their energy is divided
with the energy of the seed cell as weights.
= 300 MeV, Emin = 150 MeV (V1)
 With the two new split clusters, the invariant mass is calculated (FigureFigure 1

100gger pn theALICE Preliminary
pp s = 7 TeV
EMCal-triggered
p assoc> 10 GeV/c
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p assoc> 20 GeV/c
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1/N /0 dN ch,jet/d6 (rad-1)

15

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y#to#include#the#ﬂow#BKG#subtrac-on#method#for#PbPb.#
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Based on the24 < invariantp< 36 GeV/cmass distribution using method 2, p candida
around the masspeak
at 0.10 < mgg < 0.18 GeV/c2 .
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oton-hadron correlations in pp at 7Figure
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0&for&trigger&π0&p &regions&&Fig.7&π0Ujet&azimuthal&correla4ons&normalized&by&number&of&trigger&πH. Masui / Univ. of Tsukuba T
9c2 )Proposal for FY2014, LHC_8
FJPPL (TYL) application 2014-2015
Fiscal year April 1st 2014 – March 31st 2015Please replace the red examples by the appropriate data in black

ID 1:LHC_8

Title: Measurements of Jets and Photons in Heavy Ion Collisions at the Highest Beam Energy
during the LHC-Run 2 by ALICE
French Group
Name

Name

Lab/Organis. 3Title

DR1

SUBATECH

Leader: Tatsuya Chujo

Dr

U. Tsukuba

Marie Germain

CR1

SUBATECH

Yasuo Miake

PrU. Tsukuba

Deputy leader :Pr

LPSC

ShinIchi Esumi

DrU. Tsukuba

Renaud Vernet

Dr

CCIN2P3

Toru Sugitate

PrU. Hiroshima

Magali Estienne

CR1

SUBATECH

Kenta Shigaki

PrU. Hiroshima

Gustavo ConesaDRLPSC

Hideki Hamagaki

PrU. Tokyo

Rachid Guernane

CR1LPSC

Taku Gunji

DrU. Tokyo

Julien Faivre

MCLPSC

Motoi Inaba

PrU. Tsukuba Tech.

Alexandre Shabetai

CR1SUBATECH

Hiroshi Masui

DrU. Tsukuba

U

MembersLab./Organis. 2

Leader: Yves Schutz
U

LeaderTitle

Japanese Group

Christophe Furget• Special emphasis on jets and photons
Funding Request from France€/unitNb of units

Total (€)

Requested to 4:‣ by utilising DCAL combined with other ALICE subsystems
Description

Student stay in France

90/day30 days

2700

Visit to Japan (local expense)

100/day

10 days10001500

1 travel

Travels

H.1500
Masui / Univ. of Tsukuba

10

ofTeV in p-p), so that we are about to enter a new era of the physics program at LHC with a newly
built detector at the highest beam energy ever. To continue and further develop a fruitful physics
programs by the Japan-France collaboration at the new stage of LHC running, we propose thefollowing research plan spanning for four years.
Research Plan:
xYear 1 (2014 - 2015): DCAL/EMCAL/PHOS detector commissioning & operation (including
Level-1 photon and jet trigger development), Jet and photon analysis using Run 1 data.
x
Year 2 (2015 - 2016): 1st year of Run-2, DCAL/EMCAL/PHOS operation and 1st data of DCAL
x
Year 3 (2016 - 2017): 2nd year of Run-2, Data analysis & publications, DCAL/EMCAL/PHOSoperation.
x
Year 4 (2017 - 2018): 3rd year of Run-2, Data analysis & publications, DCAL/EMCAL/PHOSoperation.
In the first year (2014-2015), we concentrate on the detector commissioning especially on DCALand PHOS (new electronics), and also development of Level-1 trigger for photons and jets by thecollaboration between Grenoble and Tsukuba. On the analysis part, we will perform neutral pionsand jets measurements using EMCal, DCal (the first data), PHOS and TPC. We will perform S0-jet,hadron-jet and gamma-jet correlation measurements in p-p, Pb-Pb and p-Pb, as well as di-jets
measurements for the study of QGP path length dependence and energy re-distribution following
the transport of jets through the medium. The Japan-France ALICE data analysis workshop in
France in 2014 is also planed. We also utilize the support by JSPS (Bilateral Research,
CNRS-JSPS, 2013.04 – 2015.03) in order to keep strong this collaboration.

Proposal for FY2014, LHC_8Project• Main task in FY2014; detector commissioning‣ DCAL installation‣ Level-1 photon & jet triggers for DCAL (and PHOS)‣ Keep working on Run 1 data analysis
H. Masui / Univ. of Tsukuba

11

Current activities and future plan

• DCAL commissioning‣ Preparation of firmware for Level-1 photon & jet trigger- Commissioning at test-bench & at ALICE sometime this summer‣ Install other half (A-side) of DCAL super modules (Sep. - Nov.)- depending on PHOS installation• Data analysis‣ Correlation measurement between π0 & photon with hadron & jet inPb+Pb collisions at √sNN = 2.76 TeV to understand parton energy loss
mechanisms• France-Japan ALICE workshop 2015 in Saint-Tropez, France

H. Masui / Univ. of Tsukuba

12Summary• France-Japan collaboration plays important role on DCALproject‣ C-side DCAL super modules installed- Level-1 trigger commissioning for DCAL will take place in this summer‣ Full DCAL will be installed this year (Sep.-Nov.), start physics datataking from Run-2 (2015-)‣ Physics analysis in Run-1 data proceed well, preliminary results ofcorrelation measurements have been presented in QM2014
conference last week• Request for travel support in FY2014 to keep strong FranceJapan collaboration for detector upgrade as well as physics
data analysis

H. Masui / Univ. of Tsukuba

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back up

H. Masui / Univ. of Tsukuba

14

Rachid Guernane

CR1

LPSC

Taku Gunji

DrU. Tokyo

Julien Faivre

MCLPSC

Motoi Inaba

Pr

U. Tsukuba Tech.

Alexandre Shabetai

CR1

SUBATECH

Hiroshi Masui

Dr

U. Tsukuba

FY2014 request for LHC_8
Funding Request from France€/unitDescription

Nb of units

Requested to 4:

Total (€)

Student stay in France

90/day30 days

2700

Visit to Japan (local expense)

100/day

10 days

1000

1500

1 travel

1500

Travels

Total

5200
Funding Request from KEKk¥/Unit

Description
Visit to France
Travels

Nb of units

Total (k¥)

Requested to:

10/day32 days

320

KEK

150

4 travels

600

KEK

Total

920

Additional Funding from France
Provided by/Requested to 5

Type€

Additional Funding from Japan
Provided by/Requested to 6

Type

MEXT & U. Tsukuba

Travel3,000

JSPS (Kiban B, Y. Miake)

Travel etc.

2,400

JSPS

Travel2,500(BilateralResearch,k¥

CNRS-JSPS, T. Chujo)
Total

12Total

ID: identification, if program continuation, use previous ID; if new project, ID will be set by the TYL directors;
e.g. LAPP/IN2P3 or Irfu/CEA

7,900

H. Masui / Univ. of Tsukuba

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