Choose timezone
Your profile timezone:
FCC-ee TDAQ Bi-Weekly
→
Europe/Zurich
14/5-022 (CERN)
FCCee TDAQ: chat with MDI experts
Elements to determine total rate:
-
Rate of interesting physics events (e.g. Z, H, ttbar → for Z 200 kHz)
-
Rate of beam induced background (BIB)
-
Rate due to detector noise
To compute these rates one needs digitisers of the subdetectors. Subdetectors for each detector concept are at different levels of maturity, no detector concept is complete.
Some work on-going:
-
Allegro MAPS+Calo → Andrea Ciarma
-
IDEA Drift chamber → Brieuc
-
Drift chamber at the moment gives only SimHits (and not RecoHits)
-
Studies on-going to see if analog readout may be favourable (e.g. for saving power) compared to digital
-
Optical readout under study from IDEA detector group
→ Among us, we decided that we can start to produce preliminary occupancy numbers also without the digitisers to understand order of magnitude. Refining can come later.
For BIB:
-
Beam-beam backgrounds available via generators
-
Incoherent pairs, IPC, produced via GuineaPig → ask files to Andrea Ciarma (andrea.ciarma@lnf.infn.it) /eos/experiment/fcc/users/a/aciarma/pairs/4IP_2024may29/
-
Radiative Bhabha (produced via bb-bream) → important (with IPC) for calo
-
Losses of collision spent beam → there is not yet an estimation
-
Single beam backgrounds: many sources (see slide 22), not for all there is an estimation yet, but feedback would be already welcome to decide shielding (where possible) and possibly choice of optics.
Estimation of these backgrounds via FLUKA because initiating particles produced well outside detector volume (FLUKA will track particles till the interface planes: usually one plane at beamline and one plane between calo-muon).
-
Files including some of the bkg sources are available (?) and recently it was possible to interface it with the simulation
-
Synchrotron radiation so high that need to be taken out affecting detector design too
Important for us:
-
Machine has to decide baseline optics by March 2026 → we should check both
-
All studies done so far for Z, it would be nice to know the data rate at other key points
-
for ZH bunch spacing 700ns, thus 30x smaller
-
ttbar synchrotron radiation will be order of magnitude higher, also 5ns spacing
-
Injection curiosity: to keep the positron beam, one needs to keep injecting positrons. This can be done by injecting positron off-energy (off-axis option had problems), which means that some BX would have collisions not yet at the correct centre of mass energy and that should be discarded → this is already a reason to have at least a minimal trigger system.
Chat with Brieuc Francois 8 July
-
Our effort on occupancy+rate+BW studies is very welcome for both ALLEGRO and other detectors to set a procedure so that we can trust and compare numbers
-
Past studies were done in a rush, now we should take the time to do them properly, and make sure that we can trust the simulation
-
Concern about synchrotron radiation background (generated with BDSim), specially for the IDEA Drift Chamber which has long readout (400 ns)
-
Concerns if current sync bkg estimation can be trusted → TODO: (re)check status of this estimation with MDI experts
-
Recently additional detector concept, ILD for FCC
-
All detectors share MDI with beam-pipe generated in CAD and exported to Geant4
-
Detailed beam pipe with knobs and screws has an significant effect on the background estimation (“simple” double conical shape beampipe does not seem to be accurate enough). The CAD version of the beampipe is provided by accelerator/MDI people
-
FLUKA bkg estimation would be ok for all detectors
-
Concerns about MDI design, including choice of having last collimator inside the detector volume, and shielding
-
Test a few configuration, run (detector) simulation and compare the results to provide feedback
-
Digitisers and close collaboration with subdetector people (to know how things were implemented in the simulation) would be important for our studies, however, he agrees that we can already start to put together the workflow
-
Software wise, philosophy to write general code (usage of metadata, podio and detector flags to be generic and not hard code specific detector) to be shared across detectors and experiments → common repository with linear and muon colliders
-
Common event data model
-
Detector description in DD4Hep
-
Simulation based on ddsim
-
Reconstruction based on Gaudi
-
We will start a git repository with a full workflow from simulation to plotting for our studies
-
We will add more documentation on the software on our mkdocs
There are minutes attached to this event.
Show them.
