Blair Ratcliff 2 nd Workshop on SuperB, Frascati, March 2006 1 Status Update: the Status Update: the Focusing DIRC Prototype at Focusing DIRC Prototype at SLAC SLAC Blair Ratcliff Blair Ratcliff Representing: I. Bedajanek, J Benitez, J. Coleman, C. Field, D.W.G.S. Leith, G. Mazaheri, M. McCulloch, B. Ratcliff, R. Reif, J. Schwiening, K. Suzuki, S Kononov, J. Uher.
22
Embed
Blair Ratcliff2 nd Workshop on SuperB, Frascati, March 2006 1 Status Update: the Focusing DIRC Prototype at SLAC Blair Ratcliff Blair Ratcliff Representing:
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Blair Ratcliff2nd Workshop on SuperB, Frascati, March 20061
Status Update: the Status Update: the Focusing DIRC Prototype at Focusing DIRC Prototype at
SLACSLAC Blair RatcliffBlair Ratcliff
Representing: I. Bedajanek, J Benitez, J. Coleman, C. Field, D.W.G.S. Leith, G. Mazaheri, M. McCulloch, B. Ratcliff, R. Reif, J. Schwiening, K. Suzuki, S Kononov, J. Uher.
Blair Ratcliff2nd Workshop on SuperB, Frascati, March 20062
Focusing DIRC Prototype GoalsFocusing DIRC Prototype GoalsWork with manufacturers to develop and characterize one or more fast, pixelated photon detectors including;
• basic issues such as cross talk, tube lifetime, and absolute efficiency• operation in 15 KG field
Measure single photon Cherenkov angular resolution in a test beam• use a prototype with a small expansion region and mirror focusing, instrumented with a
a number of candidate pixelated photon detectors and fast (25 ps) timing electronics.• demonstrate performance parameters• demonstrate correction of chromatic production term via precise timing• measure N0 and timing performance of candidate detectors.
Blair Ratcliff2nd Workshop on SuperB, Frascati, March 20063
Prototype OpticsPrototype Optics
Radiator• 3.7m-long bar made from three spare high-quality
BABAR-DIRC barsExpansion region
• coupled to radiator bar with small fused silica block• filled with mineral oil (KamLand experiment) to match
fused silica refractive index • include optical fiber for electronics calibration• would ultimately like to used solid fused silica block
Focusing optics• spherical mirror from SLD-CRID detector (focal length 49.2cm)
Photon detector• placed in fixed slots allowing easy replacement.• typically using 2 Hamamatsu flat panel PMTs and 3 Burle MCP-PMTs in focal plane• readout to CAMAC/VME electronics with 25 ps resolution. Limited number of channels available.
Blair Ratcliff2nd Workshop on SuperB, Frascati, March 20064
Burle 85011-501 MCP-PMT• bialkali photocathode• 25μm pore MCP• gain ~5×105
Blair Ratcliff2nd Workshop on SuperB, Frascati, March 200612
Burle MCP-PMT with 10 micron holes: sensitivity to magnetic field angular rotation
wrt z axis ( B = 15kG)
Blair Ratcliff2nd Workshop on SuperB, Frascati, March 200613
Timing in Magnetic Field Timing in Magnetic Field (B=15 Kg)(B=15 Kg)
Blair Ratcliff2nd Workshop on SuperB, Frascati, March 200614
SummarySummary Photon detector performance continues to be improved by
manufacturers, and is approaching the required level for timing resolution, and single photon efficiency. Burle MCP-PMT detectors with 10 micron holes have acceptable gain and timing resolution in magnetic fields up to 15 KG.
Single photon Cherenkov angular resolution performance of DIRC prototype in timing mode looks fine, and meets MC expectations.
A fast DIRC is operationally challenging. Calibration is and will be a major issue.
We hope that many of the basic performance issues will be addressed during the next year with the prototype.
Many photon detector questions remain: Geometry, aging, rate capability, cross talk, sensitivity to
magnetic field, quantum efficiency, reliability, electronics, number of channels, and cost.
Blair Ratcliff2nd Workshop on SuperB, Frascati, March 200615
Additional SlidesAdditional Slides
Blair Ratcliff2nd Workshop on SuperB, Frascati, March 200616
Data SetData Setrun 1position 4 5,590 tracks
run 4position 7 8 tracks
run 7position 131,561 tracks
run 10position 5 5,107 tracks
run 13position 336,880 tracks
run 2position 4 4,650 tracks
run 3position 1 9,651 tracks
run 6position 622,911 tracks
run 9position 3 5,058 tracks
run 12position 131,914 tracks
run 5position 7 4,126 tracks
run 8position 2 6.232 tracks
run 11position 420,414 tracks
run 14position 517,475 tracks
Photon Pathlength in bar [cm]
Most of the data taken in positions 1, 3, 4, 5, 6
Blair Ratcliff2nd Workshop on SuperB, Frascati, March 200617
Beam DetectorsBeam Detectors
z coordinate (cm)
x co
ordi
nate
(cm
)
Hodoscope: single track hit map
Cherenkov counter: corrected event time
Lead glass: single track ADC distribution
Corrected time (ns)
Energy (ADC counts)
doubles
π –
e –
σnarrow≈50ps
Blair Ratcliff2nd Workshop on SuperB, Frascati, March 200618
Photon yield: 18-60 photoelectrons per track (depending on track polar angle)
Typical PMT hit rates: 200kHz/PMT (few-MeV photons from accelerator interacting in water)
Timing resolution: 1.7ns per photon (dominated by transit time spread of ETL 9125 PMT)
Cherenkov angle resolution: 9.6mrad per photon → 2.4mrad per track
Limited byLimited by BABAR-DIRCBABAR-DIRC Improvement strategyImprovement strategy
Size of bar imageSize of bar image ~ 4.1mrad~ 4.1mrad Focusing opticsFocusing opticsSize of PMT pixelSize of PMT pixel ~ 5.5mrad~ 5.5mrad Smaller pixel sizeSmaller pixel size