450 GeV - preliminary commissioning

Completed 2009 and repeated start of March 2010

Last update 3/3/2010

Aim: Get the machine in a good enough shape that we can sensibly start performing detailed adjustment and measurements and checks. No point in details if we're not sure the basic optics is not correct and the beam instrumentation isn't working properly. Prerequisite for safely increasing the number of bunches plus intensity.

Prerequisites: reasonable lifetime, circulating pilot, well adjusted tunes, chromaticity, orbit and coupling

Exit:

• Polarities and aperture checked.
• Basic optics checks performed.
• First pass commissioning of BI performed.
• Phase 1 of machine protection system commissioning performed.

Additional aims

1. Test the control and correction  (corrector polarity, cabling, control system, software, procedures, …).
2. Commission beam loss monitors - acquisition, display etc., connection to BIC, threshold checks with beam
3. Commission beam dump - phase 1
4. Commission beam interlock system with beam - phase 1. BIC to dump with beam. Check.
5. Commission transverse diagnostics: BPMs - capture mode, tune PLL, RF frequency modulation
6. Measurement program with pilots: polarities, aperture (first pass), beating
7. Linear optics checks: check trajectory versus kick, phase advance, BPM and corrector polarity.
8. Adjust tunes, orbit, chromaticity, coupling.
9. Commission BCTs: lifetime measurement

1. Initial Tuning of 450 GeV Machine

• Now should have a captured beam - work on the machine parameters to improve the lifetime.
• Commission key Instrumentation
  • Q-meter pickup and Q-kicker
  • Set-up BPM timing - check with BDI at what point this is needed.  Might be later?
  • Commission timing for Wirescanners.  Not much point for the BEUV etc
  • Beam loss monitoring on a circulating beam. Ring BLM's, special BLM's etc.  Averaging instead of single pass ...
• Measure and correct Orbit, Tune and Chromaticity - using standard techniques.
• Work on the orbit in IR3, IR7 and IR6 to establish a nice clean reference.

2. Systematic Pickup and Corrector Polarity Check and Aperture Scan

• Pickups:
  • Best done using single kicks and looking at the difference orbits.
  • Several Kicks in each plane with differing phase advance- and different correctors in case of polarity error!
  •  Probable relatively small kicks are best (~1-2mm?) avoid non-linear fields.
• Correctors:
  • Probably best to use a continuously sliding 3-bump, or some such and look at non-closure.
  • Apply a 1-2mm bump at a location and look at the rms of the difference orbit... we are looking for polarity errors - not minor optics errors.
  • Change bump sign and repeat.
  • Increase bump until a) lifetime bad, b) beam is dumped, c) beam is lost etc.  depending on state of the machine!!  Need to identify criteria and decide what we are measuring - since the higher order correction systems are not on and non-linear effects have not been attacked.  I guess we are looking for relatively large aperture problems.  We might be able to use this study as a first pass BLM calibration.

4. Revisit the Injection Settings

• Now can imagine roughly positioning the TDI, TCLI - ie coarse settings here as well.
• Using matching monitors in IR4 can now look at transfer line matching - correct optics of the line

5. Initial Commissioning of the Beam Dump.

• Measure orbit in IR6 - probably still based on averaging the first n turns.
• Put beam dump into inject/dump mode - how many turns between injection and dumping.  Initially leave several.
• Septa ON, dilution kickers (probably) OFF, extraction line screens in.
• Might be a good idea to put the TCDQ in before starting with the kickers - to protect somewhat the downstream parts
• Set-up extraction kickers (timing and kick).  Observe and correct trajectory using using the screens. 
• Screens at: 
  • Upstream of the TDCS (MSD) - adjust with kickers
  • Just downstream of the diluter kickers - adjust with septum
  • On the Beam Dump block.

& re-visit

• Re-optimize based on the reference orbit in IR6 and with (hopefully) the correct tunes.
• Commission and then Arm the Position/Angle beam dump system in IR6.
• Check and correct the TCDQ settings.
• Commission the dilution kicker part of the dump?  This is needed before multi-bunch injection.

6. Other Measurements/ Corrections

• Coupling, Dispersion : limited by BPM precision and Q-measurement precision.  Would like Q-history working here.
• First go at Beta-beating - same problem, but get an idea.
• Too early for K-modulation?
• Look at orbit kicks - maybe send the boys in to re-align? 
• Note that some correctors are common to the two beams.  In addition some quad effects are opposite for the 2 beams. 
• so don't go too far with one beam without looking with the other!
• When to commission the undulator to get the synchrotron light monitor working - check with BDI on intensity.
• ... must be some others ..