Descope engineering

Chris Rogers
Geoff Barber
Durga Rajaram
Jason Tarrant

General discussion

Rogers introduced the overall issues, requirements and plans
There was a general discussion of forces; we discussed the current baseline and the various revised baselines. There was a lack of clarity on the forces in various different running scenarios (e.g. running some but not all modules, etc)
  • Need to contact Holge Re: revised forces
  • Concern about forces in the event that one or more modules are not powered
  • Need to understand force standoff on naked FC - what are the forces and how are they handled?
  • Need to understand revised forces on naked RF in the event of a quench
Question from Norbert: Do we need the naked secondary absorber?
  • Rogers: Yes - there is still naked RF in which needs shielding

SS2 upstream

The plan for revised TKD was outlined. The proposed geometry was described
  • 100 mm tracker station spacing feels tight due to required bend on fibres to escape past adjacent stations - Geoff to have a play with spare stations and understand the possible geometry
  • May be possible to muck about with the station configuration using extra available diameter - but looks risky and probably not the first thing we would look at

Jason has done engineering study on SS2 upstream. He added an additional spool piece to bridge gap from RF and PRY end plate
- 6.64 mm between RF tuners and LiH fasteners, with LiH on spool piece
- Not quite enough, prefer another 10-20 mm clearance
- regular SSD Helium window hard up against the LiH, attached to the proposed new spool piece

Discussed how the tracker could be contained
- discussed a standalone tracker box that would insert into the PRY end plate bore from outside.
- potentially only need one cryocooler
- aluminium - 10 microns + < 100 micron mylar to keep the tracker light tight; but not a vacuum window; the tracker would be at 1 atm; consider air/nitrogen in TKD region, thus obviating the need for He
- 0.5 mm aluminium at the downstream end of the tracker box
- note issue with radiation from RF cavity - PPS and detectors issue

SS2 downstream

The proposed geometry was discussed
- Propose 2 stations close to TOF0; 2 stations close to TOF1 with 200-300 mm spacing between stations
- noted that we could possibly use ckov region, moving the Ckov elsewhere
- KLong has looked and thinks there is space between Quads; but note region inside the mirror plates probably has stray fields
- Propose additionally 2 tracker stations downstream of diffuser
- then diffuser as far downstream as possible (TBC by optics studies)
- propose diffuser and tracker stations as combined unit,
- question - can we get tracker station between the quads? Geoff will have a look

- 1.0 m between TOF1 and quads
- note need for cryocooler nearby; so probably cryocooler near to TOF0 and cryocooler near to TOF1 (max three stations on each cryocooler but may be efficiency/dead channel issues); this may present an issue with the proposed geometry (which has 4 stations on the cryocooler near TOF1)
- 10 stations are available (5 production + 5 spare)