In attendance: Alexander Kiselev, Brett Parker, Brian Page, Dave Morrison, Holger White, Jun Huang, Julia Furletova, Kenneth Barish, Kondo Gnanvo, Leo Greiner, Mriganka M Mondal, Renuka Rajput-Ghoshal, Ruben Fair, Salvatore Fazio, Tanja Horn, Vladimir Berdnikov, Walt Akers, William Brooks.
Summary of considerations from the meeting:
IP6 and IP8 were considered as candidate EIC IP locations. Major discussion topics were whether the existing doors were big enough for the detector to be moved in and out of the IP region, and whether the adjacent staging areas were big enough for major disassembly and reassembly of the detector. If the detector can be segmented into three demountable pieces (barrel plus endcaps), then with plausible dimensions for these a plan can be made for insertion and removal of these three pieces separately, albeit with little extra clearance, and for IP6 the cryostat height as currently envisoned will not fit through the door without lowering the entire detector. The AFK proposal is to assemble the detector in the adjacent staging area, then to move it in large pieces into the IP area. Much discussion was had about whether there could be a way to not disturb the beam pipe, but leave it under vacuum while removing detector parts from around it. This was not initially contained in the AFK proposal. It makes it unnecessary to bake out the beam pipe after accessing the detectors, but may require significant mechanical fixturing to carry out with the positioning precision required for inner tracking devices, which could also potentially increase the material budget. The counter-point was also discussed, namely, that the ability to partially disassemble the detector in the IP room may be more efficient for many types of interventions in comparison with uncabling and removing the entire detector to the staging area for partial disassembly.
Specific comments:
- Assumed that IP6 (current-STAR) will be the EIC IP.
- Door is small, longitudinal space is just barely enough.
- Can’t assume beam line can be removed for maintenance.
- IP8 (PHENIX) Hall is similarly cramped, but installation door is large enough.
- Dimensions given in slides.
- With arrangement of EMCAL and HCAL, one can define barrel + endcaps as 3 independently dismountable volumes.
- Also allows future DIRC
- Endcaps will be on their own rollers, segmented into 2 pieces each.
- IP6 everything fits, tight. IP8 electronics trailer doesn’t fit entirely inside hall.
- Considered access for 3 durations: hours, days, months. Detector must be lifted up into place in IP6 because otherwise cryocan doesn’t fit through the door.
- Dave Morrison: there’s room in IP8 for racks if done overhead, which also allows access to cryogenics. Wouldn’t want to risk moving silicon for a days-timescale activity. Is it a requirement? He can provide a link to the most recent sPhenix review which includes a description of similar procedures. Have to bake out the beam pipe after removal, lengthy procedure. In sPhenix have worked out a procedure to reduce impacts of such interventions. See presentation https://indico.bnl.gov/event/8960/contributions/39787/attachments/29577/46054/sPHENIX_Integration_Feder_V1.pdf .
- Overhead cranes are similar in IP6 and IP8, but have different weight capacities.
- Leo Greiner: STAR: kinematic mounts and clever techniques allow positioning of trackers without removing the beam pipe. Also allows baking out. Beampipe has to be supported all along its length, at all times, and a method of transferring that support to the detector when it’s installed. In ALICE, beam pipe is in place, and detector halves roll in and clamp down on flanges of the beam pipe. Should consider patch panel requirements for disconnecting / reconnecting. Termination of these must be accessible.
- Dave Morrison: all cables are going to be as short as possible. How does that get accommodated when they move 1 meter when the detector is lowered down?
- Walt Akers: Electronics trolly could go up and down, or nearer-farther. Agreed that to have to disconnect to raise/lower detector is an unacceptable consequence. Can have a lower profile cryostat? would solve a lot of problems. Or cut door, or change to IP8. Staging space is limited in IP8, though.
- Is it possible/necessary to remove the detector without removing any part of the beam pipe? Currently assuming otherwise.
- Leo Greiner: this has been done both ways in the past. The proposed design is easier to install but much harder to perform maintenance.
- Can make the doorway wider in IP8? would help.
- Yulia Furletova: need to put a realistic beam pipe into the simulation to move forward in next stage of thinking about this.
- Leo Greiner: can also look into modification of wall in staging area, make more space available.
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