1. Brick gas tightness & emulsion-lead compatibility Opera Collaboration Meeting Hamburg, 3-4-5 June 2004 F.Laudisio, G.Romano, C.Sirignano Salerno Emulsion Group J.Dupraz, S. Buontempo CERN

2. H 2 test at CERN (Jan 2004) 6 piles have been prepared (Lead-Em-Em-Em-Lead) with 3 types of lead (CERN pure, Goslar+Ca, Goslar+Ca washed) and both vacuum and mechanical packaging. Piles have been put in a vacuum chamber and when the pressure reached 10 -5 Torr, H 2 has been injected at about 100 Torr and piles have been removed after 20 hours. Fog measurements gave us a volume effect for all 6 piles. Before...After...

3. Results Reference (8.8 + 0.6) G/(10  m) 3 Vacuum (11.4 + 0.7) G/(10  m) 3 Mechanical (31.5 + 0.4) G/(10  m) 3

4. H 2 test at CERN (Feb 2004) 4 piles have been prepared (Lead-Em-Em-Em-Lead) with Goslar + Ca and both vacuum and mechanical packaging. Piles have been put in a vacuum chamber and after a 5 minutes Argon rinsing, H 2 has been injected at about 10 mbar. 2 piles have been removed after 24 hours 2 piles have been removed after 77 hours Mechanical packaging has been realized by means of aluminum tape and fiber glass tape

5. Summary Reference Feb ‘04 : (6.0 + 0.5) G/(10  m) 3 20 h Jan ‘0424 h Feb ’0477 h Feb ‘04 Vacuum 11.4 + 0.78.2 + 0.57.8 + 0.5 Mechanical 31.5 + 0.422.3 + 0.565.5 + 0.5 Reference Jan ‘04 : (8.8 + 0.6) G/(10  m) 3 These results shown that both packagins were not gas tight, then we decided to investigate a “realistic” poisoning effect coming from other gas mixtures (for example RPC gas mixture). We decided also to perform our test with real size bricks instead of small piles.

6. RPC gas test at CERN (May 2004) 6 fake bricks have been prepared with Goslar PbCa and both vacuum and mechanical packaging (with and without PE wrapping). Bricks have been put in a vacuum chamber and RPC gas mixture has been injected at atmospheric pressure. 3 piles have been removed after 24 hours 3 piles have been removed after 162 hours Fake brick composition Plastic blocks Plastic plate 1mm Lead - Emulsion - Lead cell

7. Reference (5.5 + 0.6) G/(10  m) 3 ---------------------------------------------------------------------- RPC gas + emulsion at 30° for 17 days (5.5 + 0.5) G/(10  m) 3 RPC gas is safe 24 h162 h Vacuum 5.5 + 0.45.4 + 0.4 Mechanical 5.1 + 0.15.3 + 0.4 Mechanical + PE 5.3 + 0.25.3 + 0.3

8. H 2 test at CERN (May 2004) 3 fake bricks have been prepared, both vacuum and mechanical packaging (with and without PE). Bricks have been put in a vacuum chamber and than it has been injected a gas mixture (10 % H 2 + N 2 ) for 24 h. 24 h Vacuum 5.3 + 0.2 Mechanical + PE 5.3 + 0.2 Mechanical 5.7 + 0.3

9. New lead (April 2004)... Since February we received from Goslar few samples of Pb+Cu, Pb pure and Pb+Ag. Small piles (Lead-Em1-Em2-Em3-Lead) have been realised under vacuum and stored at 30° for 77 days (9/2/2004  26/4/2004). Pb + Ca Pb + Ag Pb Pb+Cu 1 80 + 55.8 + 0.46.1 + 0.67.6 + 0.7 ** 2 78 + 55.9 + 0.36.3 + 0.47.5 + 0.4 3 82 + 55.8 + 0.46.2 + 0.38.1 + 0.8 ** ** These emulsion are seriously damaged on the surface in contact with lead Fog densities (grains/(10  m    measured are the following: Reference (6.8 + 0.7)

10. PbCu effect...

11. Long term test ( 26/11/2003  26/4/2004 ) Pb+Ca and old emulsions (C07-050) Emulsion Not refreshed Lead not washed Mechanichal pile (27 lead + 28 emulsion) Polyetine to avoid glue-emulsion direct contact Polyetilen wrapping Aluminum tape wrapping Last November we decided to perform a longer term compatibility test : After 5 months 30° NO Lead effect F.D. = 5.2 + 0.4

12. Test #1, July - September ‘03 (57 days) Reference emulsion stored at 20°C 10 20°C in contact with lead and vacuum packed 33 34°C in contact with lead and vacuum packed >100 20°C in contact with lead and packed mechanically 9 34°C in contact with lead and packed mechanically 12 Test #2, September- October ‘03 (3 weeks) No Lead effect in any case No effect

13. 30°C (23 days) 7343 7 4 7402 7361 MechanicalVacuum Reference 7 grains / (  m) 3 Test #3 October - November ‘03 There were realised several small piles using these 4 types of lead: 1. Ca-Lead laminated and punched with the same oil 2. Ca-Lead laminated and punched with the same oil, washed in an ultrasonic bath 3. Ca-Lead laminated and then punched with a different oil 4. Ca-Lead laminated and then punched with a different oil,washed in an ultrasonic bath NO Lead effect

14. Test #4, December - January ‘04 (4 weeks) 1. Pure CERN lead 2. Goslar Lead + Ca not washed 3. Goslar Lead + Ca washed at Cern in order to remove Ca from the surface. VacuumMechanical 1 98 2 128 3 11.58 20°C 30°C VacuumMechanical 198.5 2>508.5 3408.5 Reference 9 grains / (10  m) 3 NO Lead effect

15. New lead washed at CERN (May 2004)... We received from Goslar samples of Pb+Cu, Pb+Ag+Al and Pb+Ag+Sn. They were dirty and they have been washed. Small piles (Lead-Em1-Em2-Em3-Lead) have been realised under vacuum and stored at 30° for 3 weeks (21/4/2004  17/5/2004). Pb + Ag + Al Pb + Ag +Sn Pb + Cu 1 4.5 + 0.34.1 + 0.14.0 + 0.1 2 4.2 + 0.24.2 + 0.34.1 + 0.1 3 4.3 + 0.24.3 + 0.13.9 + 0.3 Fog densities (grains/(10  m    measured are the following: Reference (3.8 + 0.6)

16. New emulsions from Japan By the beginning of May ‘04 we got some new emulsions not refreshed from Japan. They have been store underground in GS lab emulsion shielded area. With Gianni,Alessandra and some technicians from Roma,Bari and Bologna we performed a test refreshing underground. We developed some not-refreshed emulsion and some of them soon after the refreshing. Fog measuremnts are the following: Refreshed (5.8 + 0.5) Not refreshed (3.3 + 0.7)

17. To evaluate refreshing efficiency a preliminary scanning has been performed. In Salerno we used a new version of Smart Tracker that we are now testing. 10 cm 12.5 cm 1.41 cm 2 After a quality cut we collect a sample of 1720 base-tracks on the refreshed emulsion. On the not refreshed emulsion the sample is 30 times bigger. A sample of 1097 tracks has been manually checked on the refreshed emulsion

18. Manual check results 1003 /1097 tracks found 91.4 + 0.2 22/1097 tracks only partially refreshed 72/1097 fake tracks 0.2 fake tracks/mm

19. Conclusions Both mechanichal and vacuum bricks are gas tight RPC gas does not poison our emulsions New lead coming from Goslar seems to be compatible with emulsions, but if it is very soft A long term test showed that old PbCa is safe if we don’t use vacuum We never observed fog increase in mechanical packagings