1. INFN of Genova, Pavia and Roma Flavio Gatti, PSI, February 9 th, 2005 1 Timing Counter status Timing Counter status

2. INFN of Genova, Pavia and Roma Flavio Gatti, PSI, February 9 th, 2005 2 Timing Counter key features Scintillator Cross Section 70º PM outer Diameter :52 mm PM active diameter: 39 mm 19º 22º 8.5º From COBRA center 105 cm 10º 25 cm B B 0.75 T 1.05 T 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 Sectional view Long. view

3. INFN of Genova, Pavia and Roma Flavio Gatti, PSI, February 9 th, 2005 3 Photomultipliers Photomultipliers PM Drift Chamber assembly Scintillator slab COBRA Magnet 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. INFN of Genova, Pavia and Roma Flavio Gatti, PSI, February 9 th, 2005 4 Beam test Frascati (nov 04) Beam focus  x =2.5 mm  y=3.0 mm 5 mm Beam Geom. Select Fast 2-electron bunch veto Beam Scint. Slab Slow calorimeter

5. INFN of Genova, Pavia and Roma Flavio Gatti, PSI, February 9 th, 2005 5 Exemple of PMs output of single counter

6. INFN of Genova, Pavia and Roma Flavio Gatti, PSI, February 9 th, 2005 6 All data for BC408 vs position at variuos impact angles Distance from center

7. INFN of Genova, Pavia and Roma Flavio Gatti, PSI, February 9 th, 2005 7 All data for BC404 vs position at several impact angle Distance from center(5cm)  T FWHM (ps)

8. INFN of Genova, Pavia and Roma Flavio Gatti, PSI, February 9 th, 2005 8 Comparison and final choice Distance from the center(cm)  T FWHM (ps)

9. INFN of Genova, Pavia and Roma Flavio Gatti, PSI, February 9 th, 2005 9 Validation test of single counter in COBRA (dec 04) 19° 22° From COBRA center 105 cm25 cm B B Pulsed Laser 101 ps FWHM 98 ps FWHM @ Frascati Beam @ COBRA Light diffusor

10. INFN of Genova, Pavia and Roma Flavio Gatti, PSI, February 9 th, 2005 10 Comments  BC404 average resolution=91ps  BC408 average resolution = 113ps  Timing resolution over the whole length = ±5% Max.  Underlying systematic effect: 1.Slope of  T vs position : different Q.E. of both PMs 2.Up/down structure: focusing effect, non uniform surface roughness,… 3.Intrinsic rise-time of plastic scintillator plays a significant role in the timing performances of the two plastics 4.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. INFN of Genova, Pavia and Roma Flavio Gatti, PSI, February 9 th, 2005 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. INFN of Genova, Pavia and Roma Flavio Gatti, PSI, February 9 th, 2005 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. INFN of Genova, Pavia and Roma Flavio Gatti, PSI, February 9 th, 2005 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