FCChh Detector and Experiments FCC advisory committee review

FCC-hh Detector and Experiments FCC advisory committee review, May 17 th, 2018 W. Riegler For the FCC Hadron Detector Working Group

For FCC-hh: New detector magnet design results in high stray field in cavern: technological limits on equipment and workers (permanent magnetization of iron components, structural members, gangways and platforms, tools, rotating machinery, …). Is this fully understood? How and when will the choice of forward magnets be made and what are the main criteria for decision? · The present baseline foresees widely separated caverns to avoid the stray field. Does this lead to inconvenience and issues e. g. with cable length, etc. ? What is the strategy for the HE-LHC detector in the CDR? For FCC-hh and HE LHC detectors, how do you plan to further study the impact (on the various sub-systems) of the very high-PU, in time for the CDR?

Reference detector for the CDR • • 4 T 10 m solenoid Forward solenoids Silicon tracker Barrel ECAL Lar Barrel HCAL Fe/Sci Endcap HCAL/ECAL LAr Forward HCAL/ECAL LAr

Muon System Standalone resolution (trigger, matching) between 5% and 30% in 0 < η < 2. 4 Analytic calculation and GEANT simulation for MS limit agree. Simulation for higher p. T numbers still to be done for CDR. No momentum measurement in the forward muon system η > 2. 5 with solenoid

How and when will the choice of forward magnets be made and what are the main criteria for decision?

In the CDR we present a reference detector i. e. a detector concept with reasonable technology assumptions and two different magnet configurations in order to set the scale of the challenge. Clearly there will be much different and more aggressive ideas and designs in the future. In the CDR we try to make the point that is is possible to build a detector that can fully exploit the FCC-hh physics potential. In that sense there is no question of a decision process … Clearly the dipole provides <1% momentum resolution up to eta=6 i. e. a close to 4 Pi detector (99. 6844% of 4 Pi).

* For FCC-hh: New detector magnet design results in high stray field in cavern: technological limits on equipment and workers (permanent magnetization of iron components, structural members, gangways and platforms, tools, rotating machinery, …). Is this fully understood? * The present baseline foresees widely separated caverns to avoid the stray field. Does this lead to inconvenience and issues e. g. with cable length, etc. ?

Fields at the outside of the detector are at around 400 m. T, at the cavern walls there are between 200 -300 m. T. We see no principle issue with the magnetic stray field. It is of course a specification and boundary condition that has to be taken into account for the equipment in the cavern. Also in the LHC experiments we have major amounts of equipment inside the detector i. e. inside large magnetic fields. In most present detectors, the signals are transported from the detector to the service cavern or the surface through optical fibers, without intermediate electronics in the experiment cavern. The main components to worry about are LV power supplies that are at present placed in racks (with cooling turbines) in the detector cavern. The distance of 50 m between the main cavern and service cavern are an advantage for civil engineering – easier construction – no large concrete pillar. We do not see issues for HV cables (e. g. already 150 m in ALICE) Cooling lines Optical fibers In view of a trigger processor, the LHC-Phase-II upgrade already foresees a L 1 latency of about 12 us due to complex trigger decision electronics. 2 x 50 m adds 0. 5 us of delay, so this cannot be a decisive factor.

For FCC-hh and HE LHC detectors, how do you plan to further study the impact (on the various sub-systems) of the very high-PU, in time for the CDR?

ECAL Tracker HCAL ECAL

The deterioration of calorimeter resolution for pileup of 1000 has been simulated, which does not yet take into account the possibilities of correcting the pileup by using tracker information. The probability of assigning more than 1 vertex to a given track has been simulated, together with the impact of timing detectors on this number. E. g. the HH channel has been studied for levels of resolution to see the impact of pileup. There is no general answer to the impact of pileup on a given physics channel. This really requires a full cycle of simulation, reconstruction, analysis, that is beyond the CDR scope. It is evident from the HL-LHC Phase-II studies that this requires significant personnel. In the near future, there will be the progress on Phase-II performance simulations. In parallel we have to keep open the possibility of using <25 ns bunchcrossing, lumi levelling to PU of 500, or stretching of the luminous region for possible mitigation of this pileup.

What is the strategy for the HE-LHC detector in the CDR?

The HE-LHC assumes no civil engineering modifications to the LHC infrastructure. The L* of 23 m and the detector caverns remain unchanged. At this moment we have only listed how the different challenges change from LHC->HL-LHC->HE-LHC->FCC-hh In terms of acceptance, the HE-LHC relates more to HL-LHC. In terms of radiation load, pileup and detector technology the HELHC related more to the FCC-hh. The table in the detector summary lists all these numbers. At this moment we have nothing that goes beyond this. For HE-LHC physics studies, the parametrization of LHC detectors is used. That’s all at this point.

Plan: 1 Page for HI detector challenges in the same format. 2 -3 pages for e-h detector in same format.