Last edited 2022-03-0224
Next meeting: 4/13 2pm (TBC)
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Near Term Efforts identified at 2022-03-24 meeting:
- Configuration of beamlines
- LDMX downstream of test beam? Or deflect one or the other? Geometry and magnet constraints on each.
- Plan
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- to engage Carsten at 4/13 meeting to understand the boundary conditions
Stopper
Understand whether Alev's proposed S30XL stopper has large enough aperture to handle spread-out beam, power limitations, and tolerance to localized heating if quads over-focus the beam. (Tor is following up with Alev)
- Define hand-off between different instrumentation sets for low-current tuning
- ACMs for LESA line spec'ed to 10 nA (design on S30XL (ops?) budget, envisioned to proceed as electrical engineers roll off LCLS-II work)
Want a downstream diagnostic in ESA with sufficient resolution to verify bunch charge < 10^3 e at 40 MHz
- Expect that LDMX can be used at and below this level of current to characterize beam size and current.
- First layer of ECAL is key
- TS and tracker could be used too but provide only 1d information
- Deeper ECAL layers should be powered down at these multiplicities, to avoid damage to silicon.
- If new diagnostic is required, should start work this year.
- Should define these transitions more carefully and seek review from LDMX ECal subsystem experts. (Want to have a slide on this for "summer 2022" LDMX review)
Modeling of beam and backgrounds (potentially good project for student interested in both accelerator and detector physics). Includes:
Better understand initial beam shaping using spoiler and collimators in A-line
Model propagation downstream and generation of beam backgrounds between spoiler and LDMX
- Backgrounds at the detector, and their impact on physics analysis (on their own and when overlayed with standard events) quads
Uniformity of spot size -- and its impact on multi-electron performance of trigger scintillator, veto performance, etc
What particles does LDMX receive when beam is on upstream stopper? (Feeds into hardware design and understanding when DAQ and subsystems should be turned off)
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List as of 2022-03-02
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Protection of the Detector (overlaps others):
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- What are the procedures for establishing beam into ESA and to LDMX?
- Rough procedure:
- Start with tune beam (low rate LCSL-II bunches) to stopper (no spoiler)
- Insert stopper, want instrumentation at a couple of locations to make sure we have the optics we expect & measure the degree of current attenuation
- Switch to LESA low-current beam.
- Detector granularity sufficient to do a measurement from 1000e/bunch on down to 10^-3e/bunch.
- Rough procedure:
- What beam parameters in ESA need to be demonstrated before we use LDMX as instrument for further beam tuning? (e.g. Beam position, max spot size, current)? Do we have instrumentation needed to do that? If not, what simple instruments can be added for this stage?
- Before we're ready to run beam into LDMX, how do we protect LDMX? Stopper? Dipole? RP and accident-case consequences of each?
- Timeline driven by figuring out what instrumentation we don't yet know we'll need.
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