AdV - Internal Review of VAC subsystem Cryotrap design, 04 Mar 09 Summary: First issues from the 1st part of the review 2nd part : Agenda of presentations Planning and manpower

Cryotrap impact on phase noise Small-Large options similar vs vacuum performances = practically equivalent vs impact on phase noise, Design is driven by mechanical design, installation risks, easyness of operation, budget , diffused light mitigation… Optimization in progress: light shortening of the small trap (2.4m -> 2.0m ) _mechanical positioning of the ports for vacuum equipment _favourable for diffused light issue The average pressure increases by a factor about 1.5 phase noise for small and large traps , with low tube outg. to evidence performances

New trap : 2.0m long, 1m dia, 0.6m baffles, preliminary Water pressure, torr Safety factor vs goal pressure, 10-9mbar, is reasonabe

Bake-out equipment and experience

Bake-out equipment and experience

Traps periodical Regenerations A first evaluation of deposited water on a trap: regeneration of the trap driven by the extra-cost due to LN2 consumption and the general plan of the AdV activity. We don’t expect to regenerate traps more than once/twice a year. A possible procedure , to be discussed _close vacuum valves, remove LN2 from trap _ purge with ‘hot’ GN2 (Pwater<Psat) 2 days, tbc _ evacuation 1 day _ LN2 refill, cooldown _ temp steady reached < 2 days

Plan and manpower estimation, in preparation Dedicade web page by AdV coordinators http://wwwcascina.virgo.infn.it/advirgo/protected/project_management.html AdVplan http://wwwcascina.virgo.infn.it/advirgo/protected/docs/AdV_plan.pdf Design finalization http://wwwcascina.virgo.infn.it/advirgo/docs/forms/VAC_DFF.doc Construction tasks http://wwwcascina.virgo.infn.it/advirgo/docs/forms/VAC_CTF.doc

4 March , part II of the review: preliminary design, thermal and diffused light issues, costs, planning, man power Agenda of presentations 15' Trap mechanical design, J.VDBrand/M.Doets  15' Optical constraints and scattered light, C.Bradaschia  15' Thermal effects on test masses, A.Rocchi  60' General discussion