Susumu Oda CNS, University of Tokyo For the PHENIX collaboration 2007/09/24
Performance of the PHENIX Ring Imaging Cherenkov detector Takao Sakaguchi, CNS U. Tokyo, for the...
-
Upload
ashlyn-glenn -
Category
Documents
-
view
222 -
download
0
Transcript of Performance of the PHENIX Ring Imaging Cherenkov detector Takao Sakaguchi, CNS U. Tokyo, for the...
Performance of the PHENIX Ring Imaging Cherenkov detector
Takao Sakaguchi, CNS U. Tokyo,
for the PHENIX Collaboration
CNS, U. Tokyo (H. Hamagaki, T. Matsumoto, S. Nishimura, K. Oyama, T. Sakaguchi)
Florida State U. (R. Chappell, D. Crook, A.D.Frawley, M. Kennedy)
KEK (Y. Akiba, K. Shigaki)
Nagasaki IAS (K. Ebisu, H. Hara, Y. Nagasaka, Y. Tanaka, T. Ushiroda)
ORNL (M.S.Emerry, C.G.Moscone, J.W.Walker, A.L.Wintenberg, G.R.Young)
SUNY at Stony Brook (R. Begay, J. Burward-Hoy, J.Ferriera, T.K.Hemmick, R.Hutter, S.Salomone)
U. Tokyo (R.S.Hayano)
Waseda U. (M.Hibino, S. Kametani, J. Kikuchi, M. Tamai)
The PHENIX RICH Team consists of 32 scientists from 8 institutions!
For Quark Matter 2001, Dec. 16, 2001
PHENIX Detector System
Search for Quark Gluon Plasma phase in Hot Dense Matter produced by 100 GeV/u Au+Au at BNL RHIC
(65 GeV/u Au+Au for Year-1)
Central ArmsCoverage (E&W) -0.35< y < 0.35 30o <||< 120o
A complex apparatus to measure: Hadrons, Muons, Electrons, Photons
Muon ArmsCoverage (N&S) -1.2< |y| <2.3 - < <
View From Beam
View From Top
For Quark Matter 2001, Dec. 16, 2001
PHENIX RICHCerenkov photons from e+ or e- are detected by array of PMTs
mirrorMost hadrons do not emit Cerenkov light
Electrons emit Cerenkov photonsin RICH.
Central Magnet
RICH
PMT arrayPMT array
•Primary electron ID device of PHENIX
•Hadron rejection at 104 level for single track
•Full acceptance coverage for PHENIX central arms
•|y| < 0.35 ; = 90 degrees x 2
•Threshold gas Cherenkov•C2H6 (th ~ 25) or CO2( th ~ 35)•eID pt range : 0.2 ~ 4 GeV/c
•PMT array readout•5,120 channels in 2 arms•pixel size ~ 1 degree x 1 degree
•2-D angles (,) of electron tracks were determined from center of Cerenkov ring, and associated with the tracks reconstructed by Drift Chamber(DC)+Pad Chamber(PC)+Time Expansion Chamber(TEC)
For Quark Matter 2001, Dec. 16, 2001
Gas VesselTwo RICH detectorsone for each arm - Weight: 7250 kg / arm - Gas volume: 40 m3 / arm - Radiator length: 0.9 - 1.5 m - Mirror system Radius : 403 cm Surface area: 20 m2 / arm - Photon detector: 2560 PMTs / arm - Radiation length Gas: 0.41 % (ethane) Windows: 0.2% Mirror panels: 0.53% Mirror support: 1.0% Total: 2.14%
The vessels are designed and fabricated at Florida State University.
For Quark Matter 2001, Dec. 16, 2001
RICH PMTHamamatsu H3171S
Cathode Diameter: 25 mmTube Diameter: 29 mmCathode: BialkaliGain: > 107
Operation Voltage: - 1400 ~ -1800 VDark current: < 100 nA at Gain=107
Cathode Luminous: >70 (mA/lm)Blue Sensitivity: > 9(mA/lm)Quantum efficiency: >19% at 300 nm
>5 % at 200 nmRise Time: < 2.5nsTransit Time Spread: < 750ps
Total number of PMTs in RICH: 5120• Each PMT is housed in a magnetic shielding case
– First 900 PMTs
• Soft iron and mu-metal
– Other 4220 PMTs:
• FERROPERM (NKK)
• A Winstone cone shaped conical mirror is attached to each PMT to collect Cherenkov light
– Entrance: 50 mm, Exit: 25 mm, Angular cut off: 30
Magnetic Shielding Case design
For Quark Matter 2001, Dec. 16, 2001
RICH PMT array•Supermodule are installed in RICH vessel to form a tightly packed PMT array•40 super-modules per one side of a RICH vessel, forming a 16x80 array•Two arrays per RICH vessel, 4 arrays in two arms. Total number of PMTs: 5120
Completed PMT array of the first RICH detector. There is an identical PMT array in the opposite side of the RICH
• 32 PMTs are assembled into 2x16 sub-assembly called “super module”
• PMTs are grouped by its gain so that 8 tubes can share the same HV
• Supermodules are assembled and tested at Stony Brook, and sent to BNL
• At BNL, Winston cones are installed in PMTs, and the completed supermodules are installed in the RICH vessel
Super Modules?
For Quark Matter 2001, Dec. 16, 2001
RICH MirrorSegmented spherical mirror
Radius: 403 cm 48 panels / arm 2 (side) x 2 (z) x 12 ()
Reflection surface Aluminum Total area: 20 m2 / area
Mirror mounts are adjusted so that all optical targets are within 0.25 mm of the designed sperical surface.
graphite fiber epoxy only 0.53 % of radiation leng
thMirror support structure
graphite fiber, Delrin, 1 % of radiation length (ave.)
Rohacell foam core (1.25 cm thick)
Gel-coat (0.05 mm thick)
4 ply graphite-epoxy (0.7 mm thick)
Structure of the mirror
• Mirror panels are mounted by adjustable 3 point mounts on the frame bars
• 2 x 12 miror panels forms a spherical surface for one side of a RICH vessel
• 2 spherical surfaces in a vessel, total of 48 panels
Completed mirror array of the first RICH
Design of 3 points mirror mounts
For Quark Matter 2001, Dec. 16, 2001
RICH (mirror alignment)
After mirrors are installed, the RICH vessel is rotated up in the same orientation as on PHENIX carriage
Positions of optical targets placed on mirror surface were surveyed with a computerized theodolite system (MANCAT).
BNL survey crew were measuring the optical targets on the mirror during the mirror alignment.
RICH (after mirror alignment)
For Quark Matter 2001, Dec. 16, 2001
• Readout Signals from 5120 PMTs:
Zero10 Photon Detection 0 pC 160 pC (Signal Preceded by Pre-Amp(x10) )
Time Resolution of 200 ps (For Background Rejection)
• Very Fast Operation: 9.6 MHz RHIC Beam Clock: Average Trigger Frequency 25 KHz
• Transfer to Data Collection Module (DCM) Data Link using G-LINK
• Compactness Processes 640 PMT Signals per Crate
Conceptual Design of RICH FEE• 9U VME Dimensions• One Controller Module • Two Trigger Modules and Readout Modules• Ten AMU/ADC Modules
Front End Electronics (FEE)
RICH-FEE Crate !
For Quark Matter 2001, Dec. 16, 2001
Readout ModuleController Module• Management of Analog Memory Unit (AMU)• Controls FEE synchronous to Master Timing System• Controls Burst Transfer• Generate AMU Write / TAC Stop Timing• Slow Serial Control using ARCNET
DSU/ALM
BTSK2
Readout FIFO
G-LinkTransmitter
ROC
PhaseShifter
• Transferring Data to PHENIX-DCM usingG-LINK at the maximum speed of 800 Mbps• G-LINK Transfer asynchronous to BUS Transfer inside RICH-FEE using four FIFOs (Depth: 9 events)
Analog Processing (AMU/ADC) Module
Inte
grat
or+
TA
C (
RIC
H)
Chi
p
AM
U/A
DC
Chi
p
AM
U/A
DC
Bur
st C
ontr
olle
r
• 64 Inputs, 64 Charge and TAC(Timing) Outputs/Board• Trigger Sum: 16 Trigger Sum Outputs/Board (4 PMT Signal Sum)• Burst Transfer to Readout Module in 20-40MHz• Serial Controllable ASICs on Board
• 8 RICH Chips (Integrator+VGA+LED+CFD+TAC+Trigger Sum)• 8 Inputs, 8 CHARGE and TAC outputs/Chip, and 4 TriggerSum/Chip
• 4 AMU/ADC Chips (Random Accessible Analog Memory Unit and ADC)
• 32 Inputs/Chip
For Quark Matter 2001, Dec. 16, 2001
RICH in Operation! (RHIC Year-1 RUN)
•High PT electron candidate is seen!
•Candidate selected with RICH, DC, and Electromagnetic Calorimeter (EMCal).
For Quark Matter 2001, Dec. 16, 2001
PHENIX RUN 12280 SEQ 0014 EVENT 850
View from North Side
South Side
East Arm West Arm
RICH EMCal
RICH ring(6 PMT hit)
EMCal hit(2.5GeV)
6 PMT RICH ring2.55 GeV/c track2.5 GeV EMCal hitelectron candidate
EMCal
RICHPC1
DC
EMCal
RICHPC1
DC
TOF
TECPC3
RICH in Operation! (Cont’d)
4480 of 5120 (7/8) PMT signals are readout.
Rests are not readout because of short of electronics
Only 52 dead channels
Used CO2 as a Radiator gas
Momentum acceptance down to 100 MeV/c is achieved
Provide very good e/ separation
RICH sees electrons in its geometrical acceptance
Red: e-, Blue: e+
For Quark Matter 2001, Dec. 16, 2001
RICH Hit and Multiplicity
•Number of PMTs fired has good correlation with number of PC1 hits which is corresponding to Multiplicity
•Occupancy at most central: 3.4 % (Magnetic field ON)
Num
ber
of P
MT
hit
s
Number of PC1 hits
For Quark Matter 2001, Dec. 16, 2001
Electrons seen in Ratio of Energy and MomentumRatio of energy (E) and momentum (p) of associated track
Momentum and energy are measured with DC and EMCal, respectively
Condition required PMT hits of more than two in t
he ring of 3.4cm<r<8.4cm Good ring shape
Peak is seen at E/p=1, which corresponds to electrons
Good separation of electrons is seen
For Quark Matter 2001, Dec. 16, 2001
Green: Raw spectra Black: Cherenkov hit required Blue: Estimated background Red: Background subtracted
0.3GeV<p<0.4GeV 0.6GeV<p<0.7GeV
0.8GeV<p<0.9GeV 1.1GeV<p<1.2GeV
Charge Calibration with Real DataFit pedestal for each RUN
Count events above pedestal
Exceed 5000?Accumulate more RUNs
Fit single photo-electron (P.E.)
Predict mean and sigma of double and triple P.E.
Fit double and triple P.E.
Using derived fit parameters,re-fit all P.E.s again
Substitute pedestal-fit only RUNs with P.E.-fitted parameters
NO
YES
1.p.e. peak resolution: = 0.42 p.e.
After Calibration
For Quark Matter 2001, Dec. 16, 2001
Timing Calibration with Real Data
•See the Timing data for identified Electron Hit.
•Correlate it with Beam Beam Counter (BBC) timing
•Determine Time 0 (T0) and conversion factor of RICH timing Data
•Recheck if (RICH T0 – BBC T0) are flat over entire BBC timing range
= 0.98 nsec
Correlation of RICH T0 and BBC T0Correlation of (RICH T0 - BBC T0)and BBC T0
Correction
For Quark Matter 2001, Dec. 16, 2001
Photo-electrons seen in RICH
•Number of PMT hits, number of photo-electrons are in agreement with simulation study
•e+ e- identified with Time of Flight (TOF) in the momentum range from 0.3GeV to 0.4GeV
•Overall figure of merit (N0) is estimated: N0=Npe/L/ <sinc> =119 cm-1
Npe: number of photo-electrons per ring L: path length in RICH vessel <sinc>: mean cherenkov cone half-angle
Black: Raw spectrum Blue: Background estimated Red: Background subtracted
Number of PMTs per ring (r<11cm) Number of photoelectrons per ring (r<11cm)
Number of photoelectrons divided bypath length in RICH vessel (r<11cm)
Mean=0.9798
For Quark Matter 2001, Dec. 16, 2001
RICH Ring Associated with Track•RICH ring associated with DC+PC1+EMCal reconstructed track
•Final mirror alignment check is done with no field data in offline
•Main hits of PMTs are seen in about 3cm<r<11cm
•Low multiplicity events (PC1 hits<100) are selected
•More than four PMT hits in r<11cm are required
• Ring center deviation with reference to track:
=0.5, z=3.3cm
Good association is seen with track!
For Quark Matter 2001, Dec. 16, 2001
Rejection Power of RICH (CO2 Gas)Real Data
e+ e- and + - identified with TOF in the momentum range from 0.3GeV to 0.4GeV
Efficiencies for electrons are 10% lower in this momentum range compared to those in the momentum range of simulation
Number of PMTs are taken within ring of 3.4cm<r<8.4cm
Ring shape cut is applied Timing cut is not applied (lose factor of two) Shielding for conversion electron at DC is
not included (lose factor of two) Event class defined by PC1 hit: Peripheral: (PC1 hit)<150 Central: (PC1 hit)>400 Errors are statistical only
Simulation Momentum range from 0.6 to 0.8GeV Au+Au Central Various electron ID cut is applied Timing cut applied Shielding included
Black: Simulation for Au+Au CentralBlue: Real data for Au+Au PeripheralRed: Real data for Au+Au Central
For Quark Matter 2001, Dec. 16, 2001
Rejection Power is good, and will be much better after planned improvement
Very Near Future PlanImprove Rejection Power
Shielding against conversion electron produced in the massive material at the edge of DC Establish Timing Cut
Develop trigger board to associate with EMCal hits in online.
Reaction rates at blue book luminosities
200 A GeV Au+Au: 1.2 kHz200 GeV p+p: 400 kHz
(4 MHz later)500 GeV p+p: 1.2 MHz(12 MHz later)
• DAQ capability: level-1 limit : 25 kHz (6 kHz initially)
required level-1 rejection power order of 102 ~ 103 for heavy ion physics
Access to rare probesJ(di-electron)charm (single electron)
Simulated Trigger RejectionPower for Au+Au
Trigger Scheme
RICHTriggerBoard
For Quark Matter 2001, Dec. 16, 2001
Summary• RICH has succeeded to operate in the RHIC Year-1 RUN.
• High PT electrons are successfully identified.
• 7/8 of all PMTs (5120PMTs) have been readout with very few dead channels.
• Charge and timing calibration procedure using online data are established, and confirmed they work well.
• Following performances are derived. Timing resolution: ~ 1 nsec
Charge resolution: = ~ 1/2 p.e. for single photo-electron
Overall figure of merit N0: 119 cm-1
Occupancy at most central: 3.4 % (Magnetic field on)
Ring center deviation with reference to track: =0.5, z=3.3cm
Rejection power at electron efficiency of 82%: 280 for Peripheral, 85 for Central (Without shielding for conversion electron and timing cut. Ring shape cut applied)
• Conversion electron shielding, timing cut will be applied for Year-2 RUN.
• RICH trigger board is developed and will be installed.
For Quark Matter 2001, Dec. 16, 2001