Forward Calorimeter
upgrade in ALICE
Tatsuya Chujo
Univ. of Tsukuba
Sep. 13, 2016
ALICE Calo meeting, NRC Kurchatov InstituteOutline
1. Physics motivations
2. Forward Calorimeter Project in ALICE• Detector design, organization• MAPS detector• PAD detector
3. Schedule
4. Summary2

Gluon Density in nucleon/ nuclear at high energy
distribution function

high energy

hard process

momentum fraction

At small x and small Q2, the parton density
will become large by non-linear effects due to gluon fusion!Gluon density saturate, called;• Gluon Saturation, or• Color Glass Condensate (CGC)3

J'K9+"L>

CGC

Color Glass Condensate (CGC)./01'%2%"0(3'4#"-+"&① Saturated gluon state by the quantum fluctuation② Universal picture at high energy nucleus andnucleon③ But no clear experimental evidence for thecreation of CGC#"$"%&'(!"#$%&'$('')#*+,
To find/ test CGC by
experiment!

#"$"%&')（１）more forward（２）Higher energy（３）proton < nucleus（４）cleanness: h < gamma!")#"-+"&

56 ./01'!+"7/8,%'4,9:'+7'4#"-+"&'"%0/#2';6 </44/89,7'7#'=%+>9"%'&/"%87'!1#7#2'+7'4#"-+"&'?97@'! A%+>9"%=%27'/>'!#>>/$,%'$('B/'7%812/8>'
C*ADBEAFGB3'GF<H'I

Signal of CGC: RpA•Two scenarios forforward ! production
in p+A at LHC:–

Normal nuclear effects
linear evolution,
shadowing–

Saturation/CGC running
coupling BK evolution• Strong suppression in direct ! RpA.
• Signals expected at forward ", low-intermediate pT.
5

QGP thermalization mechanism
QGP (known):
rapid thermalization, stronglyinteracting perfect fluid

M2L2#-2'I

CGC

collisions"*+,-.,

QGP

hadron gas/"$"'%"0.""""""""""""""""""/"$"&"0.""""""""""""""""""""""""""""""""""""""/$"&12"0.34""""""""""""""""""""/$"5&"0.34

7CGC• High energy nucleus ＝ What is the initial condition?
• Why so rapidly thermalized (t=0.6 fm/c)?
• Instability of strong color field？" need to determine

high density
color field

the initial condition clearly.
• Find the clear evidence for CGC formation as an initialcondition (or exclude it).
QGP rapid thermalization?

Long range correlations in AA and pA (“Ridge”)
RHIC (STAR, Au+Au 200 GeV)

LHC (ALICE, pPb, 5.02 TeV)

• long range !" correlations (ridge) at RHIC and LHC.
• Origin is still unknown.
• by CGC (initial condition) or others?
7photons vs. charm: D0 meson (LHCb)

8

RpPb for D0 (LHCb)

9

Isolated photons vs. hadrons
Isolated direct photons canprovide strong constraints on
the gluon PDFs

photons

R. Ichou and D. d’Enterria, Phys. Rev. D 82, 014015 (2010)• LO dominant process: quarkgluon Compton.
• Quark-anti-quark annihilation
contributing mostly at large x.
• NLO: At LHC, the majority ofprompt photons are produced in
the fragmentation process• Fragmentation photon can belargely suppressed by the isolation
cut.

→quark-gluon Compton
process dominant, more directaccess to the gluon PDFs andsaturation physics

hadronsby T. Peitzmann10M2/K9%2%>>'#4'71/>'=%+>9"%=%27'./01'&%2>/7('0,9#2'=+77%"'N.#7'O9+"L'A+77%"

Nuclear effect:;<=4/"6>?/?@"A6B① Evidence for CGC
・direct photon ＝ most clean signal for CGC
・Forward direct photon: RpA " CGC or not.

② Nature of CGC
・Direct photon RpA: system, multiplicity, y & pT dep.

A. Rezaeian, PLB 718, 1058

CGC

676

" characterize CGC size, structure, onset.

③CGC and QGP thermalization mechanism

6789

・Size of CGC (direct photon) and QGP temperature ,expansion velocity, fluctuation.
・forward photon /hadron vs. mid. photon / hadron! correlation between CGC size andQGP thermalization (e-by-e)" Mechanism of rapid thermalization④ Creation of new research fieldFPQ*R')#"-+"&''!1#7#2'＝*S*'>7+7%*S*'>7+7%

・「strong field」: QCD color (gluon) field vs. QED field (Neutron star)
・「forward」：High energy cosmic rays

p+p 13 TeVHigh multiplicity event

FPQ*R'=/&'C<*+,3'G.DB3'TG*H
FPQ*R'=/&'C<*+,3'G.DB3'TG*H'!1#7#2'＝7%=!%"+79"%'
1+&"#2＝%:!+2>/#2'U%,#8/7(

ALICE FoCal Project

12

Kinematic reach by FoCal

13

FoCal-E prototypes• Si/W sandwich calorimeter layer structure:- W absorbers (thickness 1X0)+ Si sensors• Longitudinal segmentation:- 4 segments low granularity (LG)
- 2 segments high granularity (HG)
• LG segments- 4 (or 5) layers- Si-pad with analog readout- cell size 1 x 1 cm2- longitudinally summed• HG segments- single layer- CMOS-pixel (MAPS*)- pixel size # 25 x 25 $m2- digitally summed in 1mm2 cells*MAPS = Monolithic Active Pixel Sensor (cm)14

FoCal project (Institutes)

15

FoCal project (components)

16

High Granularity (HG) Prototype, MAPS
MAPS prototype• 4x4 cm2 cross section, 28 X0 depth• 24 layers: W absorber + 4 MAPS each
• MIMOSA PHASE 2 chip (IPHC Strasbourg)- 30 $m pixels- 640 $s integration time(needs upgrade – too slow for experiment)• 39 M pixels total• Test with beams at DESY, CERN PS, SPS

Event Display:measurement (DESY) ofpile-up of two 5.4 GeV
electrons, demonstrates
two-shower separation
capabilities
17

High Granularity (HG) Prototype, MAPS

Linearity

Energy resolution

Shower profile

18

Low Granularity (LG) Prototype, PAD (India)

19

Low Granularity (LG) Prototype, PAD (JP, US))#*+,'GF<'!"#7#'7(!%3'5'>%0=%27'CDVWP3'T>9L9$+3'*WBET#L(#H20

FoCal test bench @ U. Tsukuba
mmDAQ

SRS	  readout	  system• SRS	  readout	  system	  +	  APV	  25	  hybrid	  readout	  system.	  
• Same	  system	  has	  been	  used	  for	  the	  PS/SPS	  test	  beam.	  

ALICE Calo Meeting, Moscow, Sep. 13, 2016

Si	  with	  cosmic	  ray	  measurements

21

summing board

APV25beam

FOCal PAD (4 segments)

MAPS

Test	  beam	  setup	  @	  PS	  (same	  for	  SPS)	  in	  2015

Linearity and energy resolution (2015 beam test, Tsukuba)• Good linearity
within ~3%from PS to SPSenergies.

• Stochastic term: close tothe expected value.
• Constant term: < 10%

ALICE Calo Meeting, Moscow, Sep. 13, 201623

R&D for fast readout: RD51 (VMM2/3)• R&D and test for VMM2 and VMM3 hybrid boards with SRS +DATE (ALICE DAQ) system.
• R&D of combined design; on-board VMM2/3 on FoCal summingboard, and modification for FoCal needs (dynamic range & triggercapability)[AA;SRS readout

ALICE DATE for VMM (developed by RD51)

ALICE Calo Meeting, Moscow, Sep. 13, 201624

2016 SPS test beam (Sep. 7-12 (14))

2 staff members from Tsukuba (Motoi Inaba, TC)
4 undergrad students from Tsukuba
1 master student from Nara W. U.
4 from Utrecht (MAPS)
Total: 1125

2016 SPS test beam (Sep. 7-12)Signals from new SBs• New summing board (by M. Inaba)
installed for all 4 LGLs, tested with beams(<140 GeV/c).
• Wider dynamic range and• Also the data matching between MAPSand PAD (LGL) is possible by the trigger
bits recording in the both data stream
26

Electron signals at 130 GeV/c (LGL2)
by Daichi Kawana

27

New activities in JapanNew• Si sensor R&D

New– Nara Women’s Univ. + other Japanese institutes.
– Basic study of Hamamatsu Si-PD, bonding test

• Visit Kyushu Univ. “CALICE” group (Sep. 20)
Ne•w VMM2/3 R&D in TsukubaNew– will move the VMM station at RD51 Lab. toTsukuba after the beam test.

• Physics discussion with theorists– First round (Aug. 26, 2016)28

Tentative schedulefinalize detector
LOI (2016) spec (2017)

final prototype (MiniFoCal), TDR(2018/2019)

final design(2020)

production & test
(2021-2023)
physics
w/ Mini-FoCal(2021-2023)

Physics prototypes, beam test and analysis(2016-2019)pre-assembly(2023)
production & test
(2021-2023)
physics w/ Mini-FoCal(2021-2023)

installation andcommissioning(2024-2025)

physics(2026-2029)

physics(2026-2029)

ALICE Calo Meeting, Moscow, Sep. 13, 201629

Summary• At forward region at LHC: unexplored physics
regime, there are rich physics programs:• CGC, nature of CGC (size & structure) if exist• thermalization mechanism and strong field.
• long range eta correlations (ridge origin)• Extensive R&D efforts, well defined target.
• LoI has been already prepared.
• Awaiting the project approval by the collaboration.

• We warmly welcome the Russian participationin the FoCal project !

ALICE Calo Meeting, Moscow, Sep. 13, 201630