forward rpc upgrade at phenix

Forward RPC upgrade at PHENIXChong Kim

Korea UniversityNew Frontiers in QCD - Oct. 27, Yonsei University

for the PHENIX collaboration

Contents

1. Introductiona. Spin physics at PHENIXb. Forward muon trigger upgrade

2. Station 3a. Geometrical structureb. Module assemblyc. Module QAd. Half Octants assembly and QAe. Efficiency measurement

3. Station 1a. Geometrical structureb. Module assembly, QA, and installation

4. Summary and Perspectives

2/30

1. Introduction - a. Spin physics at PHENIX3/30

PHENIXSTAR

PHOBOS BRAHMS

• RHIC (Relativistic Heavy-Ion Collider) at BNL, NY, US:• Max. √sNN : 500 GeV (pp) / 200 GeV (AA)• Max. luminosity: 1.5 × 1032 cm−2 s−1 (pp) / 2 × 1026 cm−2 s−1 (AA)• The only machine capable of colliding high-energy polarized proton beams

• PHENIX (Pioneering High-Energy Nuclear Interactions

eXperiment):• One of the two ongoing physics experiments at RHIC• Goal: Discover and examine the QGP & Analyze the proton spin

1.a.b.

2.

3.

4.


• Spin crisis:• DIS result at 1980s: proton spin is not a simple sum of its constituent quarks• Component-by-component approach:

quarks/antiquarks, gluons, and their angular momenta

→ ½ = ½ΔΣ + ΔG + Lz

• W measurement at PHENIX:• Full flavor separation of quarks/antiquarks• Measure the polarization of the quark by leptons decayed from W boson

)()()()(1

WNWNWNWN

pA RL

RLWL

ALW: single spin asymmetry

p: beam polarization (Max. 70 % for 500 GeV pp)NL(R)(W) : # of events contains the muons from W

with corresponding helicity (L or R)

)()(

)()(

)()()()()()()()(

1

1

1

1

2121

2121

xdxdor

xuxu

xuxdxdxuxuxdxdxuA

WL

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2.

3.

4.

ΔΣ = 0.33 ± 0.025 (exp) ± 0.030 (th)


PHENIX detector

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4.

1. Introduction - b. Forward muon trigger upgrade6/30

Muon

Hadron

Muon Tracker(MuTr)

Muon ID(MuID)

PHENIX muon arms (before up-

grade)

• Acceptance- 1.2 < |η| < 2.2- Δφ = 2π

• Muon Tracker (MuTR)- 3 stations of CSCs

• Muon ID (MuID)- 5 gaps of larocci tube in x & y directions- Total 80 cm thick steel absorber (plates)

• Muon tracking and triggering- Tracking by hit positions from each station- Most hadrons are absorbed before

reaching last gap of the MuID- Current 1st level rejection factor (RF):

~ 100 (MuID based 1st level trigger)

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Simulated muons into Muon Arms(2000 pb-1, with PYTHIA 5.7)

Current Muon trigger at PHENIX

W measurement at PHENIX muon arms• √s = 500 GeV

• σ = 60 mb

• L = 1.5 x 1032 cm-2s-1

→ 3.0 x 1032 cm-2s-1 (after luminosity upgrade)

• Total interaction rate: 9 MHz

• DAQ limit: 2 kHz

• Required 1st level rejection factor (RF): 4500

• Dedicated trigger system is required:

→ Forward muon trigger upgrade

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After triggerupgrade


RPC 3 RPC 3

MuTRG

RPC 1

35 cm thick Fe absorber

• PHENIX forward muon trigger upgrade• Iron (Fe) absorber: reduce hadron background• MuTRG: fast determination of high momentum tracks (tracking)• RPC: provide timing information and rough position information (timing + tracking)

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• Momentum selectivity through online sagitta measurement• Uses MuTr station 1, 2, 3 and RPC station 1, 3• Implement trigger using fast, parallel logic on FPGA’s• Beam related background rejected by RPC’s timing information

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RPC 1

RPC 3


• PHENIX muon trigger RPC• Bakelite double gap RPC• Based on CMS endcap RPC technology and expertise• Fast time response: 1 ~ 2 ns for MIP• Gas mixture:

- 95 % C2H2F4 (R134A, base gas for avalanche mode RPC)- 4.5 % i-C4H10 (isobutane, photon quencher)- 0.5 % SF6 (electron quencher)

- ~ 40 % relative humidity

Cu foil (2 mm)Mylar sheet

Module frame (Al) PHENIX RPC requirements• Most conditions are same as

those for the CMS endcap RPCs

Time resolution ≤ 3 ns

Average cluster size ≤ 2 strips

Efficiency ＞ 95 %

Rate capability 0.5 kHz/cm2

Average noise rate ＜ 10 Hz/cm2

# of streamer mode ＜ 10 %

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Station 3 (16 half oc-tants) A half octant (3 RPC modules)

RPC3

Module C

Module B

Module A

1.96 m

3.59 m

0.56 m

2. Station 3 - a. Geometrical structure11/30

• RPC station 3• One side (N or S) of RPC station 3 is composed of 16 half octants• A half octant is composed of 3 RPC modules (type A, B, and C)• Each module is a double-gap RPC which satisfies PHENIX requirements

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RPC 3 RPC 3

2. Station 3 - b. Module assembly12/30

Module assembly flow

Lay down a Mylar sheet & Cu foilon the bottom module frame

Put lower gap &Attach service lines (H.V, gas)

Prepare readout strips &Place it on the lower gap

Put upper gap on the strip &Attach service lines

Put a Mylar sheet on upper gap &Wrap the cu foil

Close module frame

• Modules for the station 3: ALL (total 96) modules were produced

Fully assembled RPC detector moduleBefore wrap the Cu foilConnect CPE cable to the H.V cable (upper gap)Connect gas tubes to the upper gapPut upper gap on the readout stripPut readout strip on the lower gapPreparing readout strip (attach signal cables)Connect CPE cable to H.V cable on the bottom RPC gapConnected gas tubePlace lower gap into Cu foil & Connect Polyethylene gas tubesLay down Cu foil on the Mylar sheet (+ frame)

Assembly of module C

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2. Station 3 - c. Module QA13/30

Module QABefore assembly

(Gap QA)• Spacer pop check• Gas leakage check

• HV hold• Dark current

After assembly(module QA)

• Noise rate check• Cosmic ray test

• QA(Quality Assurance) for a detector module:• Before assembly: spacer condition, gas leakage, HV hold and dark current• After assembly (test by cosmic muons):

noise rate, total & strip efficiencie, time resolution & cluster size

RPC cosmic ray test stand - event display

cosmic raytrigger scintillators

RPC readout stripplanes

cosmic ray trajectory

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2. Station 3 - c. Module QA14/30

Noise rate:RPC HV = 9.5 kV, PHENIX RPC FEE threshold = 160 mV

Noise rate (Hz/cm2)Raw TDC :1 unit = 100 ns/44 = 2.41 ns

Time resolution vs. HV

Efficiency of a module (%) vs. HVwith different threshold

Cluster size of a module vs. HVwith different threshold

Operation voltage

Operation voltage

PHENIX require-ments

PHENIX require-ments

Module QA results

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2. Station 3 - d. Half octants assembly and QA15/30

Half octant assembly

Route service lines of the modulefor the assembly

Insert prepared modulesto the HO frame

Connect & Re-route service linesto the patch pannel View from inside of patch pannel

Insert prepared modulesto the HO frame (2)

Insert prepared modulesto the HO frame (3)

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Integrated result of half-octants QA AT FACTORY

Average noise rate: 0.37 Hz/cm2

↔ PHENIX requirement: ＜ 10 Hz/cm2

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Integrated result of half-octants QA AT FACTORY

RPC3S

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Average noise rate: 0.25 Hz/cm2

↔ PHENIX requirement: ＜ 10 Hz/cm2


RPC3N - installation (Nov. 11th, 2009) RPC3S - installation (Sep. 22nd , 2010)

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2. Station 3 - e. Efficiency measurement19/30

3D Event display

Relative efficiency calculation:# of hits on RPC / # of projected track on RPC= # of RPC TDC count / # of Muons

Raw RPC TDC distribution

Count

TDC (106 ns for 44 bins)

RPC coincidence timing hit

Projected hits on RPC3 * Muon tracks at boundaries cut out

Muon pT (GeV)

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Efficiency vs. runsRUN 11, pp 500 GeV

Before gas mixture optimization:High dark current

After gas mixture optimization:Dark current problem resolved

Blue: south Red: north

Black: top sideRed: bottom side

Black: module ARed: module BGreen: module C

Effici

ency

(%)

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Module A

Module B

Module C


Efficiency of modules

Average cluster size ( < 2 )

Efficiency vs. Height of HO

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• Temperature: almost constant at tunnels• Relative humidity correlated with pressure• Pressure affects RPC efficiency:

ADC gain changed in the chamber

• ΔEfficiency / ΔPressure: ~ - 0.219(* 30 mbar ~ 12 inches of water)

Slope: - 0.219

Good runs selectedEfficiency vs. environment

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Efficiency vs. BBC rate

RPC3 North & South

BBC rate (MHz)

Effici

ency

(%)

Effici

ency

(%)

BBC rate (MHz)

RPC3 North & South,module A, B, and C

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Absolute efficiency measurement

RPC3 MuID MuTR

Hodoscope

Hodoscope design

Location of hodoscope

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RPC1

90 cm

67 cmOctant

34 cm

3. Station 1 - a. Geometrical structure25/30

• Structure - RPC station 1• Composed of 16 octants for both sides (8 octants for one side)• Each octant is a double-gap RPC• Two types of octants (A1, A2) for one side: geometrical condition was consid-

ered

RPC 1

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3. Station 1 - b. Module assembly, QA, and installation26/30

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RIGHTLEFT

Trigger scintillator

Trigger scintillator

123456789

10

• QA by using cosmic ray• Same QA process to the station 3 case• Average noise rate, Efficiency, Cluster size, etc…

Intermediate QA result (efficiency)for the south side octants

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RPC1N - installation (Sep. 22nd , 2011)

• Station 1 status• All octants (total 26, 10 as spares) were assembled• North side installed in Sep. 22nd • QA is underway for the south side octants• South side installation is expected in the end of October• Preparing for the integration

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4. Summary and Perspectives29/30

• PHENIX RPCs for the forward muon trigger system:- Provide timing and additional position information- Triggers muons with pT 20 ≥ GeV from W decay

• Station 3:- Installation, integration, and commission was completed by early 2011- Relative efficiency was measured for various conditions:

trigger works fine, but still requires stability test- Absoulte efficiency measurement by using hodoscopes is underway

• Station 1:- All 26 octants production completed- North side installed at late Septetmber- South side QA is underway- Installation of south side expected at the end of October- Preparing for the integration

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30/30 Thanks!

Backup slides31

MuTRGADTX

MuTRGMRG

Level 1TriggerBoard

MuTrFEE

Resistive Plate Chamber(RPC) (Φ segmented)

B

2 planes

5%

95%

Trigger

Trigger

Trigger

Interaction Region Rack Room

Optical

1.2Gbps

Amp/Discri.Transmit

DataMerge

MuTRG

RPCFEE

Trigger events with straight track(i.e. Δstrip ≤ 1)

RPC / MuTRG data arealso recorded on disk

Backup slides32

Backup slides33

Backup slides34

Backup slides35

forward rpc upgrade at phenix

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