Report on special „LEAD-MEETING“ at CERN on May-18 2004

1. Report on special „LEAD-MEETING“ at CERN on May-18 2004 • Compatibility issues • mechanical hardness needed for BAM • chemical compatibility with emulsions • irrespective of packaging option (vacuum or mechanical) • Placement of priorities and urgencies • further test w/ emulsions ?? • prototype mass production ?? • Immediate financial commitment to low-activity • lead acquisition ?? • Must overcome deadlock situation

2. The two extremes: Pb & Pb-Ca Breaking point elasticity region of Pb-Ca tearing (fluidity region)

3. Tensile tests on different Pb alloys(as was provided by JLGoslar) did probably not contain Al

4. The most common lead alloys Pb-As (not tested) Pb-Ca (NO!!) Pb-Ag (too soft ??) Pb-Sn (deemed NO!!, but good surface qualities) Pb-Sb (not tested) binary alloys Pb-Ca-Sn (NO !!) Pb-Ag-Sn (deemed NO!!, but good surface qualities) Pb-Sb-Sn (deemed NO !!) Pb-Sb-Sn-As (not tested, but also contains Sn!!) ternary alloys Further options Pb-Cu (too soft) Pb-Al(0.02)-Ag(0.02) (potentially OK)

5. Following is a recap of tests done(already known from talk of DF in JAPAN) this information is only useful if Ca-Pb is still viable BUT in view of the problems it is wise not to further entertain a Pb-Ca solution for the moment Switch to page 18

6. Surface analysis of Pb As received samples: -Presence of Ca, below 1% at, in XPS (detection limit ~ 0.1% at in ~ 2 nm depth), 80% at of C -Ca is below C (X-ray Photoemission Spectroscopy as a function of emission angle) NGL cleaned samples (detergent for cleaning of UHV parts) -less Ca , not detected in XPS , sometimes in SIMS (5-10 times more sensitive, but not easily quantitative) - oxide thickness not well reproduced from one cleaning run to the other

7. Ca in Pb: Storage • NGL cleaned samples • Ca increases on NGL surface stored 2 weeks in ultra-high vacuum, oxide thickness 1 nm: surface segregation at room T ? • - Ca does not increase on surface stored 2 weeks in air (XPS), oxide thickness 2nm at the end • Thermal oxidation of NGL cleaned sample (4 hours – 150ºC in air): • - Ca diffusion toward the surface, through oxide (5 nm) .

8. Ca in Pb as-received, NGL cleaned, storage Element “concentration” (at.%), XPS XPS detection limit

9. Analysis on plates exposed to film-emulsion Pb as received vacuum packaging Pb NGL cleaned mechanical pressure packaging Pb pure (CERN store) Stored at 30° C in air , ~ 1 month and then analyzed: -F pollution (F on top) on all emulsion exposed faces (not on back) -Ca almost below detection limit (XPS) on all plates, both faces; detected in SIMS as trace (no quantitative evaluation) -No differences between samples in oxidation state or oxide thickness -No correlation with “fog” seen in the developed emulsions -The emulsion contains Ca, F, Na, S

10. XPS analysis of the emulsion (results in atomic %)

11. Ca in Pb as a function of storage method

12. XPS results: side exposed to emulsion

13. Hardening of the PbCa by precipitation of the Pb3Ca compound Aging

14. Pb-Ca alloys Overaging Aging Four transformations are observed for Pb-Ca alloys  TTT diagrams Pb-0.058wt.%Ca 20 ˚C Pb-0.09wt.%Ca New representation of the hardening processes of lead alloys by transformation-time-temperature (TTT) diagrams J.R Hilger, L. Bouirden, 1995.

15. Pb-0.11wt.%Ca-xwt.%Sn x = 0.24 Pb-Ca-Sn Alloys x = 0.44 x = 0.64 x = 1.09 New representation of the hardening processes of lead alloys by transformation-time-temperature (TTT) diagrams J.R Hilger, L. Bouirden, 1995.

16. The mechanical properties of Pb-Ca-Sn alloys depend mainlyon the ratio of tin contentto calcium content. (Lakshmi, Manders, Rice, 1997 ; Maitre, Bourgignon, 2001). %Sn

17. Effect of Ag Pb-0.11wt.%Ca-1.09wt.%Sn Pb-0.08wt.%Ca-1.11wt.%Sn-0.0027wt.%Ag New representation of the hardening processes of lead alloys by transformation-time-temperature (TTT) diagrams J.R Hilger, L. Bouirden, 1995.

18. 18 • Need to know more about details of „prototype“ mass production of lead • Need to inject knowledge about mechanical properties into BAM • Need to know more about quality control at level of production (flatness, surface, precision of cutting, etc) • All the above has not been possible with a low quantity of lead (so far less than 1t) • Even mixing the alloy (Pb-Ag-Al) is not possible with low quantities • So far we have been addressing each problem individually thereby loosing sight of the complexity of the whole project

19. Placement of priorities and urgencies Proposal: • JLGoslar will over the next month acquire up to about 100t of low-radioactivity lead and stock it. This will be done in such a way as to not upset the price of lead on the market • The activity level will be monitored (either thru PTB-Braunschweig or thru TARI-project of DF) for each charge. • Münster will set aside the funds for the lead acquisition (~100k€) • This repository of lead will be used to run several „prototype mass productions“, trying to achieve all necessary specifications (surface flatness, cutting precision, cleaniness, etc). • Several lead alloys can be tested under real conditions (collaboration will define composition --- JLGoslar will produce within 4 – 6 weeks) • An engineering study will be performed for on-line surface cleaning, using the cleaning prescription devised by CERN TS-Group (with NGL-detergent). The objective is to design an appropriate on-line cleaning facility for further mass production. FINANCING to be defined!! • Hardness of lead plates will be assessed and tested by BAM-factory • The chemical compatibility tests can continue in parallel without loosing time.

20. Advantages • Always clean lead available for chem-tests • Immediate feed-back possible (either from BAM, BMS, or emulsion-lab) • Always clearly defined conditions • Used lead can be recycled (in part) • JLGoslar is willing to cooperate

21. Cleaning recipe from CERN TSG