Jochen Schwiening, SLAC RICH2004, Playa del Carmen, Nov 30- Dec 6, 2004 1/24 Outline: • DIRC Concept and Design • Detector Performance – Operations – Photon Yield – Detector Resolution Jochen Schwiening Jochen Schwiening P P ERFORMANCE OF THE ERFORMANCE OF THE B B A A B B AR AR D D IRC IRC
P ERFORMANCE OF THE B A B AR D IRC. Outline: • DIRC Concept and Design • Detector Performance – Operations – Photon Yield – Detector Resolution • Physics Application Examples. Jochen Schwiening. B A B AR DIRC NIM P APER. - PowerPoint PPT Presentation
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Jochen Schwiening, SLACRICH2004, Playa del Carmen, Nov 30-Dec 6, 2004 1/24
PPERFORMANCE OF THE ERFORMANCE OF THE BBAABBAR AR DDIRC IRC
PPERFORMANCE OF THE ERFORMANCE OF THE BBAABBAR AR DDIRC IRC
Jochen Schwiening, SLACRICH2004, Playa del Carmen, Nov 30-Dec 6, 2004 2/24
BBAABBARAR DIRC NIM P DIRC NIM PAPERAPER
New NIM paper describing design, construction, performance of the DIRC:
The DIRC Particle Identification System for the BABAR Experiment.
SLAC-PUB-10516 (Jun 2004), 83pp, to be published in Nucl. Instr. Methods A.
New NIM paper describing design, construction, performance of the DIRC:
The DIRC Particle Identification System for the BABAR Experiment.
SLAC-PUB-10516 (Jun 2004), 83pp, to be published in Nucl. Instr. Methods A.
→ download from SPIRES www.slac.stanford.edu/pubs/slacpubs/10000/slac-pub-10516.html
(I also brought a few copies.)
→ download from SPIRES www.slac.stanford.edu/pubs/slacpubs/10000/slac-pub-10516.html
(I also brought a few copies.)
Jochen Schwiening, SLACRICH2004, Playa del Carmen, Nov 30-Dec 6, 2004 3/24
a Stanford Linear Accelerator Centerb CEA-Saclay, c LPNHE des Universités Paris 6 et Paris 7d LAL, Universite Paris Sude Ecole Polytechnique, LPNHEf Lawrence Berkeley National Laboratoryg University of California, Santa Barbarah Colorado State Universityi University of Cincinnati
Novel RICH detector used for the first time in BABAR.
DIRC combines with dE/dx from drift chamber and vertex detector
(mostly in the 1/2 region) ashadronic particle identification
system for BABAR.
Novel RICH detector used for the first time in BABAR.
DIRC combines with dE/dx from drift chamber and vertex detector
(mostly in the 1/2 region) ashadronic particle identification
system for BABAR.
BBAABBARAR DIRC C DIRC COLLABORATIONOLLABORATION
The BABAR-DIRC Collaboration
R. Aleksan,b D. Aston,a N. van Bakel,a D. Bernard,e G. Bonneaud,e F. Brochard,e
Ph. Bourgeois,b D.N. Brown,f J. Chauveau,c M. Convery,a S. Emery,b A. Gaidot,b X. Giroux,b Ph. Grenier,e G. Grosdidier,d T. Hadig,a G. Hamel de Monchenault,b
B. Hartfiel,i A. Höcker,d M. John,c R.W. Kadel,f M. Krishnamurthy,j M. Legendre,b J. Libby,a A.-M. Lutz,d J. Malcles,c G. Mancinelli,h B.T. Meadows,h Ll.M. Mir,f
D. Muller,a J. Ocariz,c T. Petersen,d M. Pripstein,f B.N. Ratcliff,a L. Roos,c S. Schrenk,e M.-H. Schune,d K. Suzuki,a J. Schwiening,a V. Shelkov,f M.D. Sokoloff,h S. Spanier,j A.V. Telnov,f G. Therin,c Ch. Thiebaux,e
G. Vasileiadis,e G. Vasseur,b J. Va'vra,a M. Verderi,e R.J. Wilson,g G. Wormser,d A. Yarritu,a Ch. Yéche,b Q. Zeng,g M. Zitob
Jochen Schwiening, SLACRICH2004, Playa del Carmen, Nov 30-Dec 6, 2004 4/24
6.5mrad@4GeV/c
• 1.7 < |p| 4.2 GeV/c Pion/Kaon separation in rare charmless decays, e.g., B + – / B K
• Photons exit via wedge into expansion region (filled with 6m3 pure, de-ionized water).
• Pinhole imaging on PMT array (bar dimension small compared to standoff distance).(10,752 traditional PMTs ETL 9125, immersed in water, surrounded by hexagonal “light-catcher”,transit time spread ~1.5nsec, ~30mm diameter)
• DIRC is a 3-D device, measuring: x, y and time of Cherenkov photons,
defining cc tpropagation of photon.
DIRC PDIRC PRINCIPLERINCIPLE
Jochen Schwiening, SLACRICH2004, Playa del Carmen, Nov 30-Dec 6, 2004 6/24
Q=Q=(1-2(1-2ww))22wwEfficiencyEfficiencyFlavor tagFlavor tag
DIRC PDIRC PERFORMANCEERFORMANCE
0( ) (CP odd) modesScc K
BBAABBARARBBAABBARAR2004
Jochen Schwiening, SLACRICH2004, Playa del Carmen, Nov 30-Dec 6, 2004 24/24
The DIRC is a novel type of particle identification system, well matched to asymmetric B-factory environment, capable of -K separation for momenta up to ~ 4 GeV/c.
Five years of experience in PEP-II/BABAR B-factory mode: DIRC very reliable, robust, easy to operate, 98.5% of channels fully functional.
Machine backgrounds up to 200 kHz/PMT at 9·1033/cm2·s no problem for reconstruction;
new TDC chips, installed in 2002, keep DIRC safe for 1034/cm2·s luminosity.
Single photon time and Cherenkov angle resolution and photon yield close to nominal.
Track Cherenkov angle resolution within 10% of design.
DIRC plays significant role in almost all BABAR physics analyses published to date.
R&D program under way to prepare DIRC for 1034 /cm2·s and beyond.(see posters by J. Va’vra et al.)
Read more details in www.slac.stanford.edu/pubs/slacpubs/10000/slac-pub-10516.html
CCONCLUSIONONCLUSION
Jochen Schwiening, SLACRICH2004, Playa del Carmen, Nov 30-Dec 6, 2004 25/24
BBACKUPACKUP S SLIDESLIDES
Jochen Schwiening, SLACRICH2004, Playa del Carmen, Nov 30-Dec 6, 2004 26/24
Sodium and Boron levels (return-supply) in SOB water = f(time)
• measure Sodium and Boron levels;• measurements since 1999; • levels indicate loss of 2-3m per year
from PMT windows (1mm thick).
Chemical analysis of return water
from standoff box:
• measure Sodium and Boron levels;• measurements since 1999; • levels indicate loss of 2-3m per year
from PMT windows (1mm thick).
DIRC PDIRC PMT MT LLONGEVITYONGEVITY
Jochen Schwiening, SLACRICH2004, Playa del Carmen, Nov 30-Dec 6, 2004 27/24
Concern with mechanical stability of PMTs when front glass gets thinner (Super-K...)
• breaking test of PMT bundle at 4m and 8m water column (DIRC max. < 4m);• used sharp plunger to break PMT front glass; • no breaking of neighboring PMTs observed at either depth.
Concern with mechanical stability of PMTs when front glass gets thinner (Super-K...)
• breaking test of PMT bundle at 4m and 8m water column (DIRC max. < 4m);• used sharp plunger to break PMT front glass; • no breaking of neighboring PMTs observed at either depth.
plunger
PMT bundlewith light catchers
broken PMT
DIRC PDIRC PMT MT LLONGEVITYONGEVITY
Jochen Schwiening, SLACRICH2004, Playa del Carmen, Nov 30-Dec 6, 2004 28/24
Most spectacular failure mode of PMTs:
“Christmas Tree”
• loss of vacuum in PMT at base;• discharge in PMT creates many photons,
emitted via front or clear side glass;• extra photons are detected by neighbors
(sometimes scatter through entire SOB);• rates in affected PMT in MHz range,
several 100kHz in neighbors;• PMT dies after few hours – days;• HV of affected PMT immediately
(automatically) lowered to preserve data quality;
• observed rate: 5-6 per year.
Most spectacular failure mode of PMTs:
“Christmas Tree”
• loss of vacuum in PMT at base;• discharge in PMT creates many photons,
emitted via front or clear side glass;• extra photons are detected by neighbors
(sometimes scatter through entire SOB);• rates in affected PMT in MHz range,
several 100kHz in neighbors;• PMT dies after few hours – days;• HV of affected PMT immediately
(automatically) lowered to preserve data quality;
• observed rate: 5-6 per year.
Christmas Tree PMT
Rate in one sector
Rate in all sectors
DIRC PDIRC PMT MT LLONGEVITYONGEVITY
Jochen Schwiening, SLACRICH2004, Playa del Carmen, Nov 30-Dec 6, 2004 29/24
After over five years, ~160 PMTs out of 10,752 are dead or inefficient 98.5% fully functional
After over five years, ~160 PMTs out of 10,752 are dead or inefficient 98.5% fully functional
DIRC PDIRC PMT MT LLONGEVITYONGEVITY
Jochen Schwiening, SLACRICH2004, Playa del Carmen, Nov 30-Dec 6, 2004 30/24
DIRC is Stable and Robust
• Calibration constants stable: typical rms of T0 per channel ~ 0.1ns
(light pulser and data stream).
• Monitor humidity of nitrogen return line frombar box: dew points constant at -45... -55C,no leaks after installation.
• Water purification system keeps resistivityat 18.5Mcm (input) and 9.5Mcm (return).
• Water transmission in SOB remains stable at 98%/m (442nm, 325nm), 95%/m (266nm).
occu
panc
ym
ean
T0
(ns)
sigm
a T
0 (n
s)
elapsed time (days)
2ns
colors indicate sectors
DIRC CDIRC CALIBRATIONALIBRATION S STABILITYTABILITY
Jochen Schwiening, SLACRICH2004, Playa del Carmen, Nov 30-Dec 6, 2004 31/24
• Charged Hadron Spectra (, K, p/p) analysis.
• Cuts optimized to keep Mis-ID < 1-2% everywhere.
• In return, must accept somewhat lower ID efficiency especially at high momenta.
Example for combination of DIRC likelihoodswith drift chamber and vertex detector likelihoods