Revision as of 12:49, 9 September 2021 by Bruker
Opportunistic tests and long-term ideas off the top of my head
- Measure p spread on 703
- Not trivial because contribution of beta function is significant
- eta = length * tan(theta) = about 1.2 m
- sigma_x at 700 harp is about 0.5 mm. The intrinsic momentum spread is smaller than it looks; the beam moves visibly due to RF jitter, and the harp averages over that. In a sense, this is the "true" momentum spread; it depends on what we want to learn.
- Assuming Gaussian distributions: momentum spread = sqrt(sigma^2 - epsilon*beta) / eta, yes?
- epsilon*beta = 0 would give an upper bound of 4.6e-4.
- We know the emittance (7.3 nm at 8 MeV/c). How do we get the beta function?
- It would be trivial if the 600 harp were placed at the same distance from the dipole as the 700 harp, but it is not.
- Elegant can calculate the betas directly from first principles, but we can't trust the model until we validate it.
- qsUtility can measure alpha and beta upstream of Q504 using IHAM601 (already done in a test case). Elegant can predict beta at IHAM703 based on that. Sounds good enough to me? The prediction of beta_y is verifiable as the spot size in y is unaffected by dispersion.
- First, using Elegant, come up with a set of 501..504 quad values that will give a reasonably small beta_x at IHAM703, and verify that it is not too sensitive to the setpoints in practice. Making the intrinsic transverse size as small as possible (without it becoming unpredictable) will make sure the errors of beta and epsilon won't contribute too much to the error of the deconvolution result.
- Have the intermittent RF instabilities fixed
- Measure how much juice the BPMs need for reliable positions, particularly in the keV region
- Is there anything we can learn from the BPMs / correctors to supplement the gun kick study at CEBAF?
- Implement QE tool per Joe's request. Got shopping list from Michele
- It would be nice to have an extra corrector before the booster to get a nicer axis through both cavities. Prefer the duct-tape variety to nothing at all
- Permanently incorporate prep chamber stuff into EPICS
- stalk heater PS, temperature readback, ion pump current, anode current. Consider protection logic to disable heater if pressure or temp gets too high. Add oven timer. It should automagically post a completion notice to UITFLOG.
- maybe also an EPICS-switchable DC voltage for the auxiliary laser diode (replaces manual "beam shutter")?
- have a second PS for the dispenser; could be remote-controlled or not, don't really care... we can't automate the whole process anyway because of the manual valve
- Can we get decent, auto-aligning corrector mounts throughout the machine? The multipole moments are currently uncontrollable, presumably large, which is a bigger deal than one might think because the beam line alignment also looks terrible.
- Measure beam parameters downstream of booster as a function of gun energy. Maybe 4 or 5 energies. (Emittance, Energy spread)
Preparation for HKDL
- The keV emittance can be measured at 501 provided intrinsic energy spread is negligible (buncher off). I'm not sure if it is, but at least in y the result may still be meaningful.
- qsUtility lacks harps to directly measure the optical functions prior to M601, especially directly before and after the booster. Need to measure them at M601 for a few suitable beam energies and backpropagate to M401 in preparation for simulations of the HKDL optics.
- It may be useful to perform this measurement methodically for a variety of booster output energies. This could result in a separate tech note that contrasts the optical effect of the booster with what was measured at CEBAF (JLAB-TN-15-052). The quality of such results may, however, be affected by a poor understanding of the MeV optics, seeing as they will need to be adjusted. Maybe we can leave the last two quads off to alleviate this? Should be supplemented with Elegant simulations.