Edge Scanning: new plate design for the European Scanning System

1. Edge Scanning: new plate design for the European Scanning System G. Sirri for Bologna group

3. Specifications of the glass window 10 μm a few fringes per inch 10 cm • This window is produced by Silo (Florence) according to the following specifications: Specifications: THICKNESS TOLERANCE:< 10 μm per 10 cm length PARALLELISM:< 3 arc min (1 mrad) FLATNESS:a few fringes per inch(~400 nm per cm)( local slope < 0.1 mrad)

4. 125.1 “Standard” vacuum plate D1 = 3.5 mm 95 mm 118 mm 99.8 D2 = 2.5 mm ~10% of the emulsion plate is outside the vacuum pipe. groove for vacuum

5. 102 mm 128 mm 99.8 (max 100.0, min 99.45) 125.1 (max 125.5, min 124.55) New vacuum plate for the European Scanning Sysyem to scan the whole area of the emulsion plate. The emulsion is glued on a larger adhesive support (similar to the Nagoya Plate Changer) in order to keep it steady during scanning.

6. Plate setting with adhesive support Emulsion Adhesive support on the bottom side groove for vacuum Emulsions manually glued to the support, having care to minimize troubles in scanning the bottom side (as micrometric air bubbles). Several adhesive support tested: very adhesive Not adhesive, problems scanning with oil Enough adhesive Sufficiently adhesive and very transparent Sufficiently adhesive, problems on the edge scaning with oil (thanks to japanese collegues and N. D’Ambrosio to provide us a sample of the adhesive tapes)

7. Data set Brick exposed in the cosmic ray pit for 4.75 days. Ref. efficiency on the center of the emulsions:~80 % 5 plates have been glued to adhesive tapes: 20 21 Nitto tape 31 RH 22 23 Nitto tape 31 BATR 24 25 Nitto tape 5058A5 26 27 3M tape 76991 28 29 Electrostatic tape 30 ODD PLATES emulsion tape glass EVEN PLATES tape emulsion glass All the others attached to the plate with a scotch tape (covering about 1 mm of the edge); some of them have been measured also using a “standard” plate.

8. Data acq glass X(m) • 3X3 cm2 on each plate • to test: • the scanning quality (distortions and efficiencies) with and without the adhesive support • base-track efficiency on the edge of the emulsions 69000 99500 Y (m) 60000 30000

9. Distortions 3 mm from the edge qtop- qbase P25 P22 -0.020 mrad P23 P20 -0.015 mrad P21 P24 -0.020 mrad position (mm)

10. Distortions near the edge Starting from 3 mm from the edge, distrortions are bad. We have 20 mrad for all plates, with or without the support. 1 cm from the edge

11. Nitto tape 31 RH • Nitto tape 31 BA TR • Nitto tape 5058A5 • 3M tape 76991 • Electrostatic tape • No support Efficiencies vs Plate (not edge)(d>1 cm from the edge) e = N6/(N6+N7)

12. Efficiencies (not edge) Average for all plates

13. Base-track density near the edge (d<1cm) New vacuum plate (emulsions with adhesive support) “Standard” vacuum plate Y (mm) X (mm) The vacuum groove is visible as a zone with a huge number of fake tracks. Outside we can still measure some tracks but volume-tracks are not well reconstructed. We can measure the whole area of the emulsions.

14. Efficiencies near the edge Average for all plates with adhesive support 29 27 e = N5/(N4+N5) 25 23 21

15. Efficiencies near the edge • New plate, emulsion with adhesive support (Nitto tape 31 BA TR) • “standard” plate Vacuum groove Outside the efficiency decrease to zero.

16. New plate without support Plate 24 Plate 26 Plate 28 The emulsion is not stable enough on the plate. The tape on the top side of the emulsion is fine to scan far away from the edge. Close to the edge, specially with oil, the system looses surfaces and miss some fragments.

17. Conclusions • The new vacuum plate allows to use emulsions glued on a larger adhesive support and to scan the whole area of the emulsion. • All the adhesive tapes we tested don’t decrease the quality of the acq. • Efficiency is good close to the edge, with respect to the “standard” plate. • Strong distortions from 3 mm far to the edge, related to emulsion itself.