the VHMPID D etector Upgrade for ALICE experiment at LHC

Jungyu YiPusan National University

for the ALICE-VHMPID Collaboration

The 4th Asian Triangle Heavy Ion ConferencePusan, Nov. 14-17,2012

THE VHMPID DETECTOR UPGRADE

for ALICE experiment at LHC

R&D of VHMPID - ATHIC 2012 2

Outline What is the VHMPID ?

VHMPID RICH detector Layout & Characteristics

Why VHMPID ? From ALICE HMPID to VHMPID High pT PID Comparison in ALICE Physics Motivation

What is the challenge? Studies for Gas Radiator

- Pressurized Gas radiator- Transparency measurement

Integration in ALICE

How it works? Beam test 2012 : performances / Result at PS,CERN

Summary & OutlookJunGyu Yi <[email protected]>


The VHMPID RICH detector • Very High Momentum Particle

Identification Detector; Ring Imaging Cherenkov(RICH) Detector

JunGyu Yi <[email protected]>

Ring Imaging : Principle of Focusing RICH

2R

f

R

O

Mirror

r = f θc

n : refractive indexf : focal length of mirror

Cherenkov radiation

*RICH can identify the charged particle combined with detectors for momentum measurement.


Layout & Characteristics• Fluorocarbon (C4F8O / C4F10)

Gasfor Cherenkov Radiator– <n> ≈ 1.0014 at 175 nm, γth

≈ 18.9– pressure 3.5 atm, 40°C– 50cm length volume

• CsI photon-detector– with MIP position, avalanche

detector : MWPC /GEM• Spherical Mirror

– f = 50cm– carbon fiber substrate– Al + MgF2 coated for UV

• window (CaF2 / Sapphire)• FEE – HMPID GASSIPLEX


3σ PID of π, K, p5 GeV/c < p < 25

GeV/c track-by-track basis Simulated : π, K, p at p =

16 GeV/c


From ALICE HMPID


C6F14 liquid radiator<n> ≈ 1.292

3 sigma π/K/p , 1 < p <5 Gev/c

separation @ 3σ separation @ 2σ

VHMPID

C4F10 / C4F8O Gas radiator

3.5 atm, <n> ≈ 1.0014

3σ π/K/p , 5 < p <25 Gev/c


PID for high pT : TPC rdE/dx and VHMPID


rdE/dx• Statistical, reaching high

pT• Clean π sample• p/K separations are

difficult• No kaon PID

VHMPID• Track-by-track• 3σ π/K separation in high pT• Limited acceptance

(maximum 30% of central barrel)


Physics Motivation with VHMPID• Jet characteristics in p-p and A-A collisions with Track - by -

Track PID

• Hadro-chemistry & PID-triggerd Jet anlaysis in pp collision– baryon fragmentation functions via protons and anti- protons in jets– charmonium production process via pid characteristics in subleading heavy

quark jet.– quark vs gluon fragmentation by measuring hadro- chemistry in tagged jets.

• Hadronization & Jet Quenching in Pb-Pb collison– baryon enhancement at intermediate to high pT– Detailed mapping of gluon splitting process (energy loss in medium)via measurement of hadro-chemistry in tagged jets.

– Medium modification of charmonium production and gluon/quark fragmentation

– Baryon/anti-baryon imbalancevia momentum dependent p/anti-p measurement in tagged jets in medium



Studies for Gas Radiator• Pressure dependence – refractive index– Cherenkov angle vs. momentum for Pressure


Higher pressure higher refractive index larger Cherenkov angle & better resolution for separation at lower momentum

We are focusing 5 GeV/c < p < 25 GeV/c


Pressurized Gas System


To keep the ‘Gas’ phase,We have to heat the radiator

[fig] Phase diagram curves for some fluorocarbon compounds.

Heating~

40°C

heated & insulated,- Radiator tank- supply line- Detector

vessel- gas rack

C4F8O gas radiator @ 3.5 atm T >36°C

Detector

C4F8O

Gas Rack


Transparency Measurement


Transparency =

Sig. Ar / Ref. at C4F8O

Sig. / Ref. at Ar

Optical properties in VHMPID

0

0.2

0.4

0.6

0.8

1

1.2

110 120 130 140 150 160 170 180 190 200 210 220 230

l [nm]

tran

spar

ency

, effi

cien

cy [%

]

C4F10 T (85 cm)CaF2 T (5 mm)mirror TCH4 T (5 mm)CsI QEtotal efficiency

On-line measurements/monitoringof gas radiator qualities are needed!!Detector efficiency is sensitive to,- O2 , H2O and chemical

contaminants.- Photon Transmittance in radiator,

especially for UV light.


Control System for Gas radiator


Pressurized Gas Supply system

Transparency Measurement system

H/W - PLC (Programmable Logic

Controller)- Electric valves, flow meters,

regulators- T, P sensors- O2, H2O analyzer

S/W : ‘STEP7’ for PLC + Based on PVSS control panel1)

H/W - PLC (Programmable Logic Controller)- Deutrium light source 2)

- Monochromator 2) : λ = 30~275 nm, σλ = 0.1 nm

- T, P sensors- O2, H2O analyzer

1) http://j2eeps.cern.ch/wikis/display/EN/PVSS+Service2) http

://www.mcphersoninc.com/spectrometers/vuvuvvis/model234302.htm

http://www.mcphersoninc.com/spectrometers/vuvuvvis/model234302.htm







Integration in ALICE


• VHMPID + (DCaL) or PHOS system in 5 sector (20o each), 3 Stages

• 30% central barrel acceptance– Stage 1 : 15% acceptance wrt

TPC– Stage 2 : 25% acceptance wrt

TPC– |η | < 0.5 : with full installation in

Stage3 Jet fully contained• Radiator length 50 cm

keeping basic performance

on Stage1

Longitudinal cross section of VHMPID central module (proposed)


Beam Test 2012 June (1) – Layout study

• Anode-Cathode gap test,– Geometrical constraints in ALICE– 0.8 mm vs. HMPID’s : 2.0 mm

• Performance Test with– C6F14 liquid radiator (HMPID

like)– 6GeV/c e+π beam (T10,PS)


gapR

gapY

l = 3mm

2mm

*layout of variable gap chamber


Test Performance/Result


• Pad size = 4*8 mm2 (dx*dy)• # of pads = 960 = 60 * 16 (x*y)• 1 FEE (3 GASSIPLEXs) = 3*16 pads • 20 FEEs for test• 3 mm thickness radiator C6F14

1850V , CH4 gas for MWPC4 sigma OFFLINE ZERO suppressionRaw Clusters

π- beam (p =6GeV/c), radiator thickness =3mm

0.8mm , small but good performance!!


2012 Nov. : Pressurized Gas radiator Test

• Beam (T10, PS, CERN)– e- , π- & K- contaminants– 1.5 GeV/c < p < 6 geV/c

• Trigger– Long Cherenkov counter for

momentum selection– 4 (2x2) scintillators+PMT : size 1x1

cm2

– Big scintillator +iron for Muon trigger

• Radiator– C4F8O @ 3.5 atm, 40°C– 50cm length, tube vessel

• Photon detector– Anode-Cathode gap : 1.5

mm– pad size : 8x 4 mm2



Test Performance/Result


p= 6 GeV/c beam C4F8O at 3.5 atmAnode-cathode gap : 1.5 mm

SimulationTest Performance

with On-line Measured Transparency

Peakon the “Kaon”

expected!!

π-

K-


Summary & Outlook• VHMPID Upgrade in ALICE

– PID at high momentum : 5 < p < 25 GeV/c – track-by-track basis– New regime of hard processes in proton-proton and heavy-ion collisions.

• Challenges are on going ! with some harvests.– Pressurized gas radiator system– On-line Control system has installed– Transparency meter has installed and tested

• Beam tests– Layout studies has done.– Pressurized gas (C4F8O) radiator has studied.– Pressurized Gas system & Vessel also works well.– Good Performance in UV region with CsI + MWPC.– Visible range photon detection test with MCP-PMT will be in December.

• We are waiting the ALICE approval in March 2013


Unique measurements at LHC !!


Collaboration


Thank

you!!


BACK UP


R&D of VHMPID - ATHIC 2012 20JunGyu Yi <[email protected]>

Neutral Atom

↑ Dipole

charged particle

Medium (radiator)

Cherenkov Radiationphoton energy per unit length

Nobel Prize in 1958


ALICE PID Capabilities


VHMPID

separation @ 2sseparation @ 3s


Layout Optimization test• Radiator thickness : 3mm • Radiator Gap : gapR

– 35, 45, 55, 65, 70 (mm)

• Anode-Cathode pad Gap : gapY– 2.0, 1.6, 1.2, 0.8 (mm)

• HV scan– 1600 ~ 2050V– Vmin. & Vmax. are related w/ gapY.

• Beam Rate (Triggered particle/spill)– 10, 180, 380, 750

• Veto study– w/o, 5, 10, 20, 30, 40, 50 (μs)

• Delay– 750 (ns)– 250, 500, 625, 800, 875, 1000– 2000, 5000, 10000

gapR

gapY

l = 3mm

2mm



Clusters and parameters

parameters.list

x_min. = 12.5 x_max. = 16.5y_min. = 4.5y_max. = 8.5r_min. = 3.0r_max. = 7.0

r_max.

x_min. x_max.

y_max.

y_min.r_min.

*[cm]


x

y4×8 mm2

16 r

ows =

128

mm

60 columns = 240 mm

fiducial

MIP


Abstract• The Very High Momentum Particle

Identification (VHMPID) detector represents a possible upgrade for the ALICE experiment at LHC. It has been conceived to extend hadron identification on a track-by-track basis in 5 GeV/c < p < 25GeV/c momentum range. The VHMPID is a ring imaging Cherenkov detector with pressurized gaseous radiator coupled to CsI-based photon detector. We will present the detector development status and some results from the beam tests at PS, CERN.


the VHMPID D etector Upgrade for ALICE experiment at LHC

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