Sketch and rough estimation of a colder trap for AdV central area Size: external diameter= 1.5m , height=1m Speed >=5000l/s (N2) Daily consumption LN2<50liters (<100 watt) Lhe<25 liters (<1 watt) AL shields, no superinsulation. 1 face exposed to a grid cooled at 77K Port on a 1000mm flange 15keur , 1valve 500 30keur, trap 120keur = 170keur? Running costs: LN2<300eur/mese (0.2eur/lt) LH2<5000eur/mese (6eur/lt) Capacity LN2 ?liters , LHe<250liters, autonomy >1 week Refill period: weekly. Helium is not recovered!? Refill means: portable dewars. 200liters of Lhe possible? Alternatives: Neon + recondenser+zeolites, (LH2 ?) . LHe @ 20K ? 400mm port on a 1000mm flange. 500/650? 20cm, LN2 70cm, LHe 30-4K

comments Lhe not recovered -> work at 20K, to use latent + sensible heat? Remote condenser (15m) for Neon. Should work, more complex because the compressor @ 30K PsatN2=10^-3mbar PsatO2=10^-4 mbar. Zeolites/Ac. carbon Rem:He more dangerous for people (burning) More difficult for cool down; regenerations are more long Motivations: Air too would be ‘sticky’ and not quickly removable from well baked tube walls