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Timing Counter status

Timing Counter status. From COBRA center. 105 cm. 25 cm. 8.5 º. 19 º. 22 º. 10 º. B. B. Timing Counter key features. Rotated Scintillator Slab ☺ greater response uniformity and better timing performance achievable by using the coincidences

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Timing Counter status

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  1. Timing Counter status

  2. From COBRA center 105 cm 25 cm 8.5º 19º 22º 10º B B Timing Counter key features Rotated Scintillator Slab ☺ greater response uniformity and better timing performance achievable by using the coincidences ☺Positron Path-Length (5 cm) enough for required p.e. statistics Maximal Matching Scin.-PM ☺all PM active area covered PM tilted of ~ 20º to Mag. Field ☺ lower Field Gain suppression factor PM active diameter: 39 mm 70º Scintillator Cross Section Sectional view PM outer Diameter :52 mm 0.75 T 1.05 T Long. view

  3. PM Drift Chamber assembly COBRA Magnet Scintillator slab Photomultipliers PMs have been separately tested inside COBRA for gain and TTS. Ordered in the Fall 2004. Should be delivered in April. Tilting angle reduced to 11°

  4. Beam test Frascati (nov 04) Scint. Slab Beam focus sx=2.5 mm sy=3.0 mm Slow calorimeter 5 mm Beam Geom. Select Fast 2-electron bunch veto Scint. Slab Scint. Slab Beam

  5. Exemple of PMs output of single counter

  6. All data for BC408 vs position at variuos impact angles Distance from center

  7. All data for BC404 vs position at several impact angle DT FWHM (ps) Distance from center(5cm)

  8. Comparison and final choice DT FWHM (ps) Distance from the center(cm)

  9. From COBRA center 105 cm 25 cm 19° 22° B B Validation test of single counter in COBRA (dec 04) 98 ps FWHM Pulsed Laser Light diffusor @ Frascati Beam 101 ps FWHM Pulsed Laser @ COBRA

  10. Comments • BC404 average resolution=91ps • BC408 average resolution = 113ps • Timing resolution over the whole length = ±5% Max. • Underlying systematic effect: • Slope of DT vs position : different Q.E. of both PMs • Up/down structure: focusing effect, non uniform surface roughness,… • Intrinsic rise-time of plastic scintillator plays a significant role in the timing performances of the two plastics • These effects are under study. • Plastics sizes, shapes and PM coupling works fine. • The solution has been indirectly validate in the COBRA • A test with the DRS in order to verify the readout solutions is foreseen.

  11. TC Final Design • A PLASTIC (BLACK PLEXIGLASS) SUPPORT STRUCTURE ARRANGES THE SCINTILLATOR BARS AS REQUESTED • THE BARS ARE GLUED ONTO THE SUPPORT • “LIGHT” INTERFACE ELEMENTS ARE GLUED ONTO THE BARS AND SUPPORT THE FIBRES • FIBRES ARE GLUED AS WELL • TEMPORARY ALUMINIUM BEAMS ARE USED TO HANDLE THE DETECTOR DURING INSTALLATION • PTFE SLIDERS WILL ENSURE A SMOOTH MOTION ALONG THE RAILS

  12. TC design • PMTs ARE ATTACHED, BY MEANS OF THE INTERFACE SOCKET, TO THESCINTILLATOR BARS • GIVEN THE MASS, AN ELASTIC AND REMOVABLE SILICONE GLUE IS APPROPRIATE • THE HOLLOW INTERFACE ELEMENT IS A “CUSTOMDESIGNED” PROFILE THAT ADDS A MINIMUM AMOUNT OF MATERIAL BETWEEN THE FIBRES AND THE BARS • SLOT FOR CABLES and OPTICAL FIBERS HAVE BEEN FORESEEN TO ALLOW THE CABLES FROM THE INNER PMT TO EXIT

  13. Comments on Design • Final design has been done and the main parts of the TC have been fixed • PM’s, Scintillator plastics, Scintillating Fiber are already ordered. • Building “Blocks”, such us PM’s socket, Hollow interface for scintillating fiber will be produces soon. • He bag under study • New batch of not irradiate APD have been delivered in these days. If test will be positive, we have to concentrate the construction of the 2 curved detectors in the next 6-8 months

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