RPCs for the W measurement in PHENIX
Chong Kim
Korea University
Japan-Korea PHENIX collaboration workshop, Nov. 27, 2012
for the PHENIX collaboration
2/24
Outline
1. PHENIX RPCs
2. Ongoing activities and Preparations for Run 13
3. Summary
3/24
1. PHENIX RPCs
MuTRG
RPC 1
RPC 3
RPC 3
35 cm thick SS310 absorber
• PHENIX forward muon trigger upgrade for W program
•
•
•
SS310 (Stainless Steel) absorber: reduce low-p hadron’s punch through
MuTRG: fast determination of high momentum tracks (tracking)
RPCs: provide timing information and rough position information (timing + tracking)
4/24
1. PHENIX RPCs
PHENIX RPC requirements
Module frame (Al)
Mylar sheet
Cu foil (2 mm)
 Most conditions are same to
those for the CMS endcap RPCs
• PHENIX muon trigger RPC
•
•
•
•
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 %
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
5/24
1. PHENIX RPCs
2.05 m
Module C
RPC3
Module B
4.93 m
Module A
0.54 m
RPC 3
Station 3 (16 half octants)
A half octant (3 RPC modules)
• RPC station 3
•
•
•
One side (N or S) of RPC station 3 is composed of 16 half octants
An half octant is composed of 3 RPC modules (type A, B, and C)
Each module is a double-gap RPC which satisfies PHENIX requirements
RPC 3
6/24
1. PHENIX RPCs
Module assembly flow
Lay down a Mylar sheet & Cu foil
on 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
assembled
RPC
detector
module
Lay
down
Cu
foil
on
the
Mylar
sheet
(+lower
frame)
Place lower
Connect
gap
Connect
CPE
into
Preparing
cable
CuFully
CPE
foil
Put
to
readout
cable
&H.V
upper
readout
Connect
cable
to
strip
gap
the
Before
strip
on
Polyethylene
Connected
on
H.V
(attach
the
on
the
cable
wrap
bottom
the
readout
signal
(upper
the
gas
gas
RPC
Cu
cables)
tube
strip
gap
tubes
foil
gap)
gap
Connect
gas
tubes
to
the
upper
gap
Assembly of module C
•
Production of a module for Station 3
Put a Mylar sheet on upper gap &
Wrap the cu foil
Close module frame
7/24
1. PHENIX RPCs
RPC cosmic ray test stand - event display
Module QA
Before assembly
(Gap QA)
cosmic ray
trigger scintillators
• Spacer pop check
• Gas leakage check
• HV hold
• Dark current
RPC readout strip
planes
After assembly
(module QA)
cosmic ray trajectory
• 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 efficiency, time resolution & cluster size
8/24
1. PHENIX RPCs
Module QA results
Noise rate:
RPC HV = 9.5 kV, PHENIX RPC FEE threshold = 160 mV
Noise rate
(Hz/cm2)
Efficiency of a module (%) vs. HV
with different thresholds
PHENIX
requirements
Operation voltage
Time resolution vs. HV
Raw TDC :
1 unit = 100 ns/44 = 2.41 ns
Cluster size of a module vs. HV
with different thresholds
Operation voltage
PHENIX
requirements
9/24
1. PHENIX RPCs
Integrated result of half-octants QA AT FACTORY
Average noise rate: 0.37 Hz/cm2
↔ PHENIX requirement: ＜10 Hz/cm2
10/24
1. PHENIX RPCs
Integrated result of half-octants QA AT FACTORY
RPC3S
Average noise rate: 0.25 Hz/cm2
↔ PHENIX requirement: ＜10 Hz/cm2
11/24
1. PHENIX RPCs
RPC3N - installation (Nov. 11th, 2009)
RPC3S - installation (Sep. 22nd , 2010)
Full integration to the PHENIX DAQ system
was completed during Run 11
12/24
1. PHENIX RPCs
RPC 1
90 cm
RPC1
Octant
67 cm
34 cm
• 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
considered
13/24
1. PHENIX RPCs
14/24
1. PHENIX RPCs
RPC1N - installation (Sep. 22nd , 2011)
RPC1S - installation (Dec. 07th , 2011)
15/24
2. Ongoing activities and Preparations for Run 13
3D Event display
Relative efficiency measurement (St 3 and St 1):
ε = # of hits on RPC / # of projected μ track on RPC
Hitmap of MuTR and RPC3
(Matched to RPC3 geometry)
Timing distributions of RPC3
Raw hits
Muon Track
Associated hits
16/24
2. Ongoing activities and Preparations for Run 13
Run 363088 (pp200GeV, official) :
example of ongoing efficiency study, p > 3 GeV (NOT final: contains a lot of fakes!)
Efficiency vs. Half Octants
Efficiency vs. Positions
• Improvement in efficiency calculating method is underway
• Both RPC3 and RPC1 efficiency study is ongoing
17/24
2. Ongoing activities and Preparations for Run 13
Efficiency vs. Run by Module type, for all pp 200 GeV Runs (NOT final!)
18/24
2. Ongoing activities and Preparations for Run 13
Absolute efficiency measurement by using Hodoscope (St 3)
RPC3
D. Jumper (UIUC)
MuID
MuTR
Efficiency by Hodoscope (NOT final)
!
Location
Design of Hodoscope
19/24
2. Ongoing activities and Preparations for Run 13
St 1 efficiency measurement by using cosmic muons
M. Sarsour (GSU)
(NOT final)
RPC1
MuTR
St 1
Track extrapolated from MuTR St 1 to RPC1
20/24
2. Ongoing activities and Preparations for Run 13
Additional shielding plan
M. Leitgab (UIUC) and PHENIX thechs
Figure made by R. Seidl, Plots
used made
by M. by
Leitgab,
Ralf Seidl, used by M. Leitgab, quoted by C. Kim
and quote by C.Kim
Figure by D. Lynch
1) Shielding lower Half-Octants vs. backsplashes from DX magnet
•
•
•
•
By using 144 steel bricks, each 5.1×10.2×20.3 (cm) @ 8.2 kg (300 total ordered)
Stacked in 7.6 (cm) high, 40.7 wide, 3 rows
Gives layer of steel in 61.0 (cm, in z) × 15.2 thick × 162.6 (x)
Fill any additional spaces with spares/scrap steel
21/24
2. Ongoing activities and Preparations for Run 13
Additional shielding plan
M. Leitgab (UIUC) and PHENIX techs
22/24
2. Ongoing activities and Preparations for Run 13
RPC1 temperature control
•
F. Giordano, D. Jumper (UIUC) and PHENIX techs
Temperature control: Very little space remains when Muon arms are in Run position
•
•
•
Install thermocouples (2 per side) for monitoring
Install blowers (2 per side) to increase air flow
Thermocouple calibration and Blower installation is underway
23/24
2. Ongoing activities and Preparations for Run 13
Gas recirculation
Case 1
•
F. Giordano, D. Jumper (UIUC) and PHENIX techs
Case 2
Case 3
Former gas circulation method suspected makes impurities in flowing gas
•
•
•
Performed all 3 test by using 2 spare RPC1 octants for 2 weeks: no effect
Case 1 test ongoing by using prototype RPC1 without linseed oil coating
Preparing for check gas itself by using gas analyzer
24/24
3. Summary
• PHENIX RPCs for the forward muon trigger system
•
Provides timing and additional position information
•
All of stations were produced, tested, and installed
• Ongoing activities and Preperations:
•
Efficiency measurement for both stations by using real data and cosmic muons…
•
Additional shielding, temperature control, gas recirculation tests, timing shift control,
dead/hot channels management, put ‘watchdog’ process in MuTrig for misalignment
in several RPC1…
•
Not an ideal we-are-ready-to-go state, but we’re closing to it step by step
Thanks!
B/1
Backup
• 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
ΔΣ = 0.366 ± 0.017
for Q2 = 10 and 0.001 ≤ x ≤ 1
• W measurement at PHENIX:
•
•
Full flavor separation of quarks/antiquarks
Measure the polarization of the quark by leptons decayed from W boson
AL
AL
W
W
1 N L (W )  N R (W )
  L
p N (W )  N R (W )

u ( x1 )d ( x2 )   d ( x1 )u ( x2 ) u ( x1 )
 d ( x1 )

or 
u ( x1 )
u ( x1 )d ( x2 )  d ( x1 )u ( x2 )
d ( x1 )
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)
B/2
Backup
• PHENIX Run 12 - pp 510 GeV remark
•
•
•
Statistics: more than 30 pb-1 for vtx ≤ 30 cm
Beam polarizability: larger than 60 %
Newly integrated detectors: RPC1 and FVTX
B/3
Backup
PHENIX muon arms (before upgrade)
• 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
Muon Tracker
(MuTr)
Muon ID
(MuID)
- 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)
B/4
Backup
Simulated muons into Muon Arms
(2000 pb-1, with PYTHIA 5.7)
W measurement at PHENIX muon arms
After trigger
upgrade
•
√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
MuID base trigger
(before trigger upgrade)
B/5
Backup
RPC 1
RPC 3
• 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
B/6
Backup
Resistive Plate Chamber
(RPC) (Φ segmented)
Trigger events with straight track
(e.g. Dstrip <= 1)
Trigger
Level 1
Trigger
Board
RPC
FEE
MuTRG
Data
Merge
Amp/Discri.
Transmit
5%
MuTRG
ADTX
MuTRG
MRG
1.2Gbps
Trigger
2 planes
B
Optical
Trigger
95%
RPC / MuTRG data are
also recorded on disk
MuTr
FEE
Interaction Region
Rack Room
B/7
Backup
B/8
Backup