Brick gas tightness & emulsion-lead compatibility

1. Brick gas tightness&emulsion-lead compatibility F.Laudisio, G.Romano, C.SirignanoSalerno Emulsion GroupJ.Dupraz, S. BuontempoCERN Opera Collaboration Meeting Hamburg , 3-4-5 June 2004

2. H2 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, H2 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 mm)3 Vacuum (11.4 + 0.7) G/(10 mm)3 Mechanical (31.5 + 0.4) G/(10 mm)3

4. H2 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, H2 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 Jan ‘04 : (8.8 + 0.6) G/(10 mm)3 Reference Feb ‘04 : (6.0 + 0.5) G/(10 mm)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 mixturehas been injected at atmospheric pressure. • 3 piles have been removed after 24 hours • 3 piles have been removed after 162 hours Plastic blocks Fake brick composition Plastic plate 1mm Lead - Emulsion - Lead cell

7. Reference (5.5 + 0.6) G/(10 mm)3 ---------------------------------------------------------------------- RPC gas + emulsion at 30° for 17 days (5.5 + 0.5) G/(10 mm)3 RPC gas is safe

8. H2 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 % H2 + N2) for 24 h.

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). Fog densities (grains/(10 mm)3) measured are the following: Reference (6.8 + 0.7) ** These emulsion are seriously damaged on the surface in contact with lead

10. PbCu effect...

11. Polyetilen wrapping Aluminum tape wrapping Long term test (26/11/2003  26/4/2004) Last November we decided to perform a longer term compatibility test : • 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 After 5 months 30° NO Lead effect F.D. = 5.2 + 0.4

12. Test #2, September- October ‘03 (3 weeks) No Lead effect in any case • 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 #1, July - September ‘03 (57 days) No effect

13. Vacuum Mechanical 1 36 7 2 40 7 3 34 7 4 34 7 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 30°C (23 days) NO Lead effect Reference 7 grains / (10mm)3

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. Reference 9 grains / (10 mm)3 30°C 20°C 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). Fog densities (grains/(10 mm)3) 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. 10 cm 12.5 cm 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. 1.41 cm2 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