patrizia rossi for the rich collaboration laboratori nazionali di frascati- infn (italy) physics...
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Patrizia Rossi for the RICH Collaboration
Laboratori Nazionali di Frascati- INFN (Italy)
Physics motivations
Status of the project
Future Plans
CLAS12 2nd European Workshop - March 7-11, 2011- Paris, France
CLAS12 Physics ProgramCLAS12 Physics Program
Hadron PID to achieve flavor tagging
Hadron PID to strongly constrain the models
Hadron PID to access rare processes
Study of the internal nucleon dynamics: Study of the internal nucleon dynamics: TMD distribution and fragmentation functions & TMD distribution and fragmentation functions & GPDsGPDs
Quark hadronization in the nuclear mediumQuark hadronization in the nuclear medium
SpectroscopySpectroscopy
This program requires good identification of and K over the full kinematical range accessible with CLAS12 Particle identification is an essential part of any experiment, and has contributed substantially to our present understanding of elementary particles and their interaction
The power of a good PIDThe power of a good PID
Need to distinguish Bd from other similar topology 2-body decays and to distinguish B from anti-B using K tag.
LHCb (MC prediction)
NO RICH With RICH
CLAS12 PIDCLAS12 PID
RICH
SIDIS kinematics
full pion / kaon / proton separation over whole accessible momentum range of 2 – 8 GeV for SIDIS exp.
/K separation of 4-5 @ 8 GeV/c for a rejection factor ~1000
GeV/c 1 2 3 4 5 6 7 8 9 10
/K
/p
K/p
e/
HTCC
TOF
TOF
TOF
HTCC
HTCC
HTCCEC/PCAL
RIC
HRIC
H
LTCC
LTCCRICH
LTCCLTCCRICH
LTCCRICH
Concept of a RICH for CLAS12Concept of a RICH for CLAS12
Projective geometry: 6 radial sectors
1.2 m gap
~ 3 m radius
25o
FT
OF
wall
DC
3TOR
US
538 cm
124 cm
B ~ 40 G
RA
DIA
TO
R
RIC
8 mrad
2 mrad
Aerogel mandatory to separate hadrons in the 2-8 GeV/c momentum range collection of visible Cherenkov light use of PMTs
Freon+UV-light detection does not provide enough discrimination power in the 2-8 GeV/c momentum range
RICH
RICH for CLAS12RICH for CLAS12
RICH for CLAS12RICH for CLAS12
RIC
RIC
RIC
Large Detector area (several m2)
Operation in magnetic field & with high intensity e- beam
Challenging project:
Innovative new technologies Radiator Material Photo-detectors Electronics
RIC
~ 6 m2
entrance window
1 m depth
From a proximity focusing to an “hybrid” RICH
5 8 5 8 5 8 5 8 5 8
CC
K
RICH for CLAS12: status and plansRICH for CLAS12: status and plansMC Simulation for basic parameters studies ✔ (stand-alone GEANT-3 based code)- Aerogel refractive index and thickness - Photon detector pixel size - Gap dimension
Fix the pixel size of PMTs< 1cm
5 8 5 8 5 8 5 8 5 8
RICH for CLAS12: status and plansRICH for CLAS12: status and plans
MC Simulation with RICH geometry included into the CLAS12 GEMC package (Geant4/C++ based code)- focussing mirrors option studies in progress- Development of the reconstruction tracking algorithm of charged particles in progress Front-end & Readout Electonics- Available readout system to be customized for CLAS12 - Test of the modified system in CLAS12 conditions - Production of the needed boards- Quality checks/characterization
Preparation of a Conceptual Design Report by this Preparation of a Conceptual Design Report by this summersummer
MC Simulation for basic parameters studies ✔ (stand-alone GEANT-3 based code)- Aerogel refractive index and thickness - Photon detector pixel size - Gap dimension
Validation of simulations and check performances: RICH prototype construction- Procurements of parts done ✔- Tests of the radiators and the photo-detectors at Frascati – setup installation started- Prototype beam tests
Committed by UTFSM (Chile)
Transparent Silica Aerogel with High nTransparent Silica Aerogel with High n
0
10
20
30
40
50
60
70
1.00 1.05 1.10 1.15 1.20 1.25 1.30
refractive index @405nm
transmission length
@400nm [mm]
conventionalPD
New production technique invented for high
refractive index greater than 1.05
–Optical quality degraded if sample with n>1.05 is produced in a conventional method –“Pinhole drying (PD)” method artificially shrinks alcogel to obtain high index–Transparency doubled for n>1.05 aerogel with this new method
Makoto Tabata, Ichiro Adachi et al. for Belle II aerogel RICH group
Some new developments also in NovosibirskFirst use of high refractive index aerogel (n=1.13) in particle physics experiment [A.Yu.Barnyakov et.al., Nucl.Instr. and Meth. A 598 (2009) 163]
GEMC SimulationsGEMC Simulations
GEANT4 toolkit:Toward a complete simulation: realistic geometry / detailed optic effects track multiplicity / background full Cherenkov ring simulation chain
Ongoing activities: Improve simulation
Reduce costs mirrors
The focusing Mirror SystemThe focusing Mirror System
Goals: • instrument only forward region • reduce active area (~1 m2/sect)• minimize interference with TOF system• allow larger aerogel thickness (focalization)
Low material budget
Direct & reflected photons
The focusing Mirror SystemThe focusing Mirror System
Preliminary studies with mirrors (to reduce instrumented area): - focalization capabilities shown - ring patterns for positive and negative mesons at different angles and momenta reconstructed
• spherical (elliptical) mirror within gap volume for backward refl.
• plane mirror just beyond radiator for forward reflections
Different scenarios (refractive index, radiator thickness, mirror geometry) are being explored
TOF
Reflectinginside
direct &reflected
Low materialbudget
Minimize detector area (~1 m2/sector) interference with FTOF
The reconstruction algorithm: Direct Ray Tracing The reconstruction algorithm: Direct Ray Tracing (DRT)(DRT)
For each track, t, and particle hypothesis, h, use direct ray tracing for a large number of generated photons to determine the hit probability for each PMT
The measured hit pattern is compared to the hit probability densities for the different hypotheses by a likelihood function.
Hypothesis that maximizes is assumed to be true
is the probability of a hit given the kinematics of track t and hypothesis h
is the hit pattern from data = 1 if the ith PMT is hit= 0 if the ith PMT is not hit
is the probability of no hit
is the total number of expected PMT hits is a background term
ANL+INFN/FE
Direct ring exampleDirect ring example
Hit prob > 3 10-3
200 trials per event
Aerogel: - n=1.06 - thickness increasing with radius: 2 cm up to 13 deg 4 cm 13-15 deg 6 cm 15-17 deg 8 cm 17-20 deg 10 cm > 20 deg
Mirror: 14o-25o
PMTs: UBA
M. Contalbrigo INFN/FE
PPMT (i)
Average Average NNp.e.p.e.
Np.e. > 5 for reflected ringsNp.e.> 12 for direct rings
+ -
5°
LHLH-LH-LHK,pK,p+ -
Contamination as expected from the GEANT3 simulation!
Very promising results also for the reflected events
Contamination as expected from the GEANT3 simulation!
Very promising results also for the reflected events
5°
Average Average NNp.e.p.e.
Mirror up to 35o:Viable configurationMirror up to 35o:Viable configuration
+ -
Mirror 14°-25°
LHLHpp-LH -LH K,pK,p - Mirror 14 - Mirror 14oo-25-25oo
n=1.03 in principle good due to the larger Cherenkov angle separationn=1.03 in principle good due to the larger Cherenkov angle separation
n=1.06Aer. thick 2-4-6-8-10 cm
n=1.03Aer. thick 3-6-9-12-15 cm
+ - + -
n=1.06 better for patter recognition in the presenceof backgrouns
n=1.06 better for patter recognition in the presenceof backgrouns
Average Average NNp.e.p.e.
oo
+ -
n=1.06
Average Average NNp.e.p.e.
oo
+ -
Photo-detectorsPhoto-detectors
Multi-anode PMTsSiPM
visible light compact single photon
Small pad size
REQUESTS:
MA-PMT Dimentional outline (mm3)
Effective area (mm2)
Pixel size (mm2)
Comment
R7600 26x26x28 18x18 4.5x4.5 (4x4) Optimized for single photonRecommended by HamamLow packing factor
H8500-C 52x52x28 49x49 5.8x5.8 (8x8) Excellent packing factorNot optimized for single photonNot recommended by H.
H8500-C-03 UV glass window
R8900-00-M16
25x25x28 20x20 4.8x4.8 (4x4) Optimized for single photonHigh packing factorSensitive to B
R8900-100-M16
Super bialkali
R11265 23x23 2.8x2.8 (8x8) Optimized for single photonHigh packing factorInsensitive to BAvailable only 8x8 - Preliminary tests results with H8500 and R7600 at Glasgow U.
- R8900 will be tested soon
Front-end & Readout ElectronicsFront-end & Readout Electronics
• Independent channels (unique!) with selectable gain for non-uniformity compensation
• Smart (reconfigurable) self-triggering by active FPGA (trigger topology scheme)
• Up to 4096 channels in compact form factor
• Fast Readout
• Compact (high density of the front end)
Front-end & readout board developed by INFN-Genova group (front-end chip MAROC from IN2P3-Orsay)
A.G. Argentieri et al. NIM A 617 (2010) 348–350
Players in the GamePlayers in the GameINSTITUTIONS Researchers
ARGONNE NL 3
INFNBari, Ferrara, Genova, Frascati, Roma/ISS
13
GLASGOW U. 2
JLAB 2
U. CONN 3
UTFSM (Chile) 3NEW COLLABORATORS, CONTRIBUTIONS ($,
€..), MANPOWER, ARE VERY WELCOME TO JOIN THIS EXCTING PROJECT
ConclusionsConclusions
Good hadron identification is required for studies of the internal nucleon dynamics
RICH technique is the clear choice when hadron identification is required at high momenta
Preliminary studies show that aerogel plus visible light detection with MA-PMT can match the requirements for a RICH for CLAS12.
Work is in progress to:- Improve simulation and reconstruction algorithm - Define a CDR by this summer- validate simulations and check performances by testing components and building a prototype
Initial R&D funding available from INFN and ANL
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