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February 13, 2008 RPC2007-Mumbai 1
RPC Production for Fast Muon Trigger System for
Byungsik Hong Korea University
for the PHENIX Collaboration
February 13, 2008 RPC2007-Mumbai 2
Contents Motivation Characteristics for PHENIX RPCs Quality assurance plan Schedule
Gap production and installation Summary
February 13, 2008 RPC2007-Mumbai 3
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
February 13, 2008 RPC2007-Mumbai 4
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
February 13, 2008 RPC2007-Mumbai 5
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
February 13, 2008 RPC2007-Mumbai 6
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
February 13, 2008 RPC2007-Mumbai 7
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
February 13, 2008 RPC2007-Mumbai 8
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.)
February 13, 2008 RPC2007-Mumbai 9
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
February 13, 2008 RPC2007-Mumbai 10
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
February 13, 2008 RPC2007-Mumbai 11
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
February 13, 2008 RPC2007-Mumbai 12
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
February 13, 2008 RPC2007-Mumbai 13
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
February 13, 2008 RPC2007-Mumbai 14
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%
February 13, 2008 RPC2007-Mumbai 15
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
February 13, 2008 RPC2007-Mumbai 16
Endcap Region of CMS
Phase IPhase II
Gap Production for CMS Endcap RPCs
February 13, 2008 RPC2007-Mumbai 17
February 13, 2008 RPC2007-Mumbai 18
►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
February 13, 2008 RPC2007-Mumbai 19
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
February 13, 2008 RPC2007-Mumbai 20
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
February 13, 2008 RPC2007-Mumbai 21
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
February 13, 2008 RPC2007-Mumbai 22
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
February 13, 2008 RPC2007-Mumbai 23
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
February 13, 2008 RPC2007-Mumbai 24
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
February 13, 2008 RPC2007-Mumbai 25
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
February 13, 2008 RPC2007-Mumbai 26
Back-up Slides
February 13, 2008 RPC2007-Mumbai 27
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.