WP4 Cryogenic Beam Vacuum System Conception: Activity LNF (task 4.4, 4.6) R. Cimino LNF-INFN, Frascati (Italy) 1

R. Cimino We are scientifically involved and responsible of task 4.4: Study vacuum stability at cryogenic temperature  We will determine vacuum stability and adsorption isotherms at different cryogenic beam-screen operating temperature ranges (D-4.1).For this, a post doc has been recruited (Marco Angelucci) and we are working on our set-ups. We are “technically” involved in task 4.6: Measurements on cryogenic beam vacuum system prototype.  A post doc have been recruited (Luis Gonzalez, since February 2016, now at CERN) which will be in charge of the synchrotron radiation induced photo desorption studies to be installed at ANKA. 2

R. Cimino Funding In July 2015 we (LNF-Na-Sa-Rm1) applied in CSV for additional funding also to support experimental for FCC-hh. (Call: cerca) Maintenance, Consumables, Travel money for the period (60k€ / Year). Hardware for best performing LT desorption studies (220/250 k€) In the October Meeting no funds have been allocated by INFN ! Different scientific priorities. Not a call... Low fundings on Accelerator based R&D (813 k€ in total!) 3

R. Cimino As now: We will resubmit a similar request for 2017, since it is clear that without consumables and new hardware it will be difficult to sustain and implement our expensive experimental activity. LNF-INFN is ready to: Make partially available the existing laboratory for FCC-hh experiments 4  Instrumentation  maintenance  upgrades. Marco will show you our activity next. We are now forced to count on available resources (with very limited mobility, no consumables, etc.).

R. Cimino Ouside Eurocircol priorities (as clearly stated in Paris Nov 15): But of potential interest to FCC-hh activity: we are following the study of photon reflectivity and photo yield both of interest as input parameters for instabilities calculation and to follow: We propose to coat the interior of the Beam Screen with a thin layer of carbon that reflects all the incident radiation. The carbon coating is designed so that the radiation, and the heat it carries, is transported away from colder regions towards periodically placed room-temperature absorbers, which are easier and cheaper to cool than the tube itself, potentially cutting the associated costs in half.

R. Cimino the baseline now is: It adsorbs all the power (>35 W/m/ring) in the cold part Can it be compatible with magnets running at 4.2°K? Alternative design and design studies are not encouraged nor funded within EuroCirCol and FCC-CERN.