February 13, 2008RPC2007-Mumbai1 RPC Production for Fast Muon Trigger System for Byungsik Hong Korea...

February 13, 2008 RPC2007-Mumbai 1

RPC Production for Fast Muon Trigger System for

Byungsik Hong Korea University

for the PHENIX Collaboration


Contents Motivation Characteristics for PHENIX RPCs Quality assurance plan Schedule

Gap production and installation Summary


Motivation The origin of the proton spin

u

ud

Quark Spin ΔΣ = 0.25 0.10∓→ known as Spin Crisis

Ref.) EMC, Phys.Lett.B206, 364 (1988); Nucl.Phys.B328, 1 (1989)

zseavalence LGΣ 2

1

2

1

Spin ½ quarks

Spin ½ q-bars

Spin 1 gluons


Present Understanding

x

sPDF'

different

Spin dependent gluon distribution functions by the QCD analysis of DIS data ΔG = 0.47 ∓ 1.08 (largely unknown)

(Ref.) M. Hirai, S. Kumano, N. Saito, Phys. Rev. D 74, 014015 (2006)

Spin dependent quark distribution functions by the QCD analysis of DIS data Δq(x) : well known, Δq(x) : not well known


Detailed Quark and Antiquark Spins Main motivation of the PHENIX RPC upgrade W-boson production

The sea quark polarizations of the proton can be probed by

The single spin asymmetry, AL, of W+ and W-.

)()(

)()(1

WNWN

WNWN

PA

LR

LRW

L

)()(

)()(1

WNWN

WNWN

PA

LR

LRW

L

R

L


Analysis Method The quark and antiquark polar

izations of the proton can be estimated through AL, at Q 2 = MW

2,

)()()()(

)()()()(

2121

2121

xuxdxdxu

xuxdxdxuA W

L

)()()()(

)()()()(

2121

2121

xdxuxuxd

xdxuxuxdA W

L

)( - )()(

ondistributiquark dependent Spin

xqxqxq

proton polarized for the

/ , /

1

21

xx

esQxesQx WW yy

x2>>x1

x2>>x1

x1>>x2

x1>>x2


Experimental Requirement

Design Luminosity of RHICL = 2x1032/cm2/s for √s = 500 GeVσtot = 60 mb

Raw rate at PHENIX = 12 MHz

PHENIX DAQ limit ≈ 2 kHz for muon arms

Required RF ~ 6,000Cf.) Current RF by MuID trigger ~ 500

We need to introduce the muon trigger, based on the momentum measurement.→ RPC based muon trigger upgrade


PHENIX RPC Locations

RPC1(a,b)RPC2 RPC2RPC3 RPC3

We need total 256 RPC modules.(For the detailed plan, see Rusty Towell’s talk in PL-8 on Friday.)


Why do we employ RPC? General characteristics of RPC

Fast response- Suitable for the trigger device

Good timing resolution: 1~2 ns Good spatial resolution

- Typically a few cm- Determined by the strip width and the cluster size

Low production cost High-rate capability

in avalanche mode


Specific Characteristics of Trigger RPC

Characteristics of double gap RPC in avalanche mode as a muon trigger detector

Time resolution 1 ~ 2 ns for M.I.P.

Efficiency > 95 % for M.I.P.

Rate capability 1 ~ 2 kHz/cm2

Noise rate for plain RPCs 10 ~ 50 Hz/cm2 for ~ 1010Ohm∙cm

Noise rate for oiled RPCs 0.5 ~ 5 Hz/cm2 for ~ 1010Ohm∙cm

Resistivity of resistive plates 1010 ~ 1011 Ohm∙cm

Typical strip multiplicity 1.5 ~ 3.0


EfficiencyTypical shape of the efficiency curve for various thresholds

Efficiencies for double- and single gap

(Ref.) S. H. Ahn et al., Nucl. Instrum. Methods A 508, 147 (2003)

fC) 200~ :(CMS

fC. 300 ~ 100typically

ranges thresholdCharge


Time Resolution

FWHM ~ 3 ns

No SF6

Time spectrum at 9.0 kV with Th = 270 fC Time resolutions as a function of HV

No SF6


Charge Our definition of the avala

nche charge <q> < 10 pC

Definition of the avalanche mode operation P(streamers) < 10%

Large pulse Large number of strips Cause difficulty for the rec

onstruction of high momentum muons

No SF6


For the specific R&D effort for the PHENIX RPC, see Beau Meredith’s talk in PL-11 on Sat.

<q>~10 pC for the limit of avalanche

<q>~2.7 pC at ε~95%


Korea Univ. & CMSThe Korea Detector Laboratory (KODEL) of Korea University has been an active member of the CMS (Compact Muon Solenoid)/LHC at CERN since 1997.

For more details, see the following two talks:

Sung Keun Park in PL-3 on Thursday

Kyong Sei Lee in PL-7 on Friday


Endcap Region of CMS

Phase IPhase II

Gap Production for CMS Endcap RPCs


►Bakelites are produced and cut in Italy ►Gas gaps are produced at Korea University►RPC frame & parts are procured in China (CIAE) ►Final assembly is done at BNL.

Flow of RPC Gaps and Parts for PHENIX

bakelite route

gas cell route

frames and parts

Korea BNL

China

Italy


Quality Control of Gaps Inspection of raw bakelite for the surface quality Checking the graphite surface and the condition for PET

coating Test for gas leak and spacer bonding

Add 20 hPa to each gap (1 hPa=1 mbar) No detached spacers Pressure loss : < 0.2 hPa for 15 minutes

Test for high-voltage holding and current 1.5 days for flushing + 5 days for HV test Current limit for each gas gap right after the production: < 3 μA/

m2/gap at working HV (9.4 kV at 1013 hPa) Assignment of the bar code only for the qualified gas ga

ps


Current Limits for PHENIX

PHENIX RegionCurrent limit for

each gap at 8.5 kV (μA)

Current limit for each gap

at 9.4 kV (μA)

Current limit for RPC

at 9.4 kV (μA)

RE3 Ring 1-2 (N+S) 1 2 10

RE3 Ring 3-4 (N+S) 2 4 15

RE3 Ring 5-6 (N+S) 3 5 15

RE2 Ring 1-2 (N+S) 1 2 10

RE2 Ring 3-4 (N+S) 2 4 15

RE2 Ring 5-6 (N+S) 2 5 15

RE2 Ring 7-8 (N+S) 3 5 15


Examples of CMS Endcap RPCs

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43

9.4 kV (72 h)

0

0.05

0.1

0.15

0.2

0.25

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43

8.5 kV (12 h)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1 4 7 10 13 16 19 22 25 28 31 34 37 40 430

2

4

6

8

10

12

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43

Cu

rre

nt (

μA)

Individual Gap ID

Rejected Gaps

Blue: begin

Pink: end


PHENIX Schedule I 2008

January Send 6 sets of prototype C (RPC3

A) gaps to BNL March Send prototype D gaps to BNL

• Complete RPC3 ‘half octant’ Install two ‘half octant’s in one ar

m• One in the RPC2 and another

one in the RPC3 positions Install one octant absorber made

of ~30 cm (or 2 λI) thick Cu in one arm

~June Start the mass production of RPC

gaps for PHENIX

RPC 3A

RPC 3B

RPC 3C


PHENIX Schedule II 2009

Install absorber in the North arm Install RPC2 and RPC3 in the North arm

2010 Install absorber in the South arm Install RPC2 and RPC3 in the South arm

2011 Take out one nuclear interaction length absorber Install RPC1 in both arms Start to take the high statistics polarized p+p data


Current Production PlanPHENIX Region

Number of RPC Modules (Gap

s)

Estimated months for production

Tentative Schedule

RPC3 (North) 48(96) ~ 2.5Start ~June

2008

RPC2 (North) 64(128) ~ 3.0Finish by the end of 2008

RPC3 (South) 48(96) ~ 2.5

RPC2 (South) 64(128) ~ 3.0Finish by the end of 2009

RPC1a (both arms) 16(48) ~1

RPC1b (both arms) 16(64) ~1Finish by the end of 2010

Sum 256 (560) ~13


Summary The origin of the proton spin is the fundamental question of nuclear

physics. The PHENIX is upgrading the muon trigger system by using the RPC

s in order to filter out the small cross-section W-candidate events. The flavor dependent quark and anti-quark spin distribution functions c

an be measured. Korea University will produce all PHENIX RPC gas gaps.

The mass production and installation will be completed by 2011. Additional potential application of the L1 muon trigger for heavy-ion

collisions still need to be explored, for example, Heavy-flavor trigger in combination with the forward vertex upgrade Dimuon trigger for the vector mesons for RHIC II


Back-up Slides


CMS Endcap RPC1. Function : L1 muon triggers 2 wings (RE+, RE-) 4 stations (RE1, RE2, RE3, RE4) Pseudo rapidity coverage : 0.9 < η < 2.1 (1.6) η segmentations : 10 (6) 2. Total # of RPCs : 756 (432) Total # of FEBs : 2,268 (1,296) Total # of channels : 85,248 (41,472) 3. By March 2007, the gap production for phase I (0.9 < η < 1.6) was completed for the first operation of CMS in 2008.

February 13, 2008RPC2007-Mumbai1 RPC Production for Fast Muon Trigger System for Byungsik Hong Korea...

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