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

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

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

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

Plate setting with adhesive support Adhesive support on the bottom side Emulsion 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: Type Thickness Nitto tape 31RH 72 μm Nitto tape 31 BATR 71 μm Nitto tape 5058A5 45 μm 3M tape 76991 47 μm 3M Electrostatic tape 150 μm very adhesive Enough adhesive Not adhesive, problems scanning with oil 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)

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 emulsion tape 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.

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

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

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

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

Efficiencies (not edge) Average for all plates

Base-track density near the edge (d<1cm) “Standard” vacuum plate New vacuum plate (emulsions with adhesive support) 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.

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

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.

New plate without support 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.

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.