Minutes of 24 May 2007 SWMD Telephone Meeting

1. EM simulations
   GdfidL license expires end of June, need to decide where it should be renewed, currently at Birmingham e-science cluster, could be moved elsewhere (ASTeC Orion "cluster", Lancaster, Manchester, ...).
   Jonny to continue working with Adriana on modal decompostion from GdfidL.

   Will aim to make table of predicted kicks for run 3 collimators with (best estimate of) uncertainty from study of mesh stability.

2. Tracking simulations: Merlin enhancements.
   Adriana has implemented resistive wall wakes for the case of a single drift-collimator-drift section, seeing a small change in y^'.

   This is implemented using circular apertures, and effects are either resistive wakes or geometric, but not both.

   Plan is to extend to the whole BDS, quantify the effect of resistivity of Ti vs. Cu, which has obvious implications for material damage desgign.

3. Run 4: plans for collimators to test
   Can we reduce collimator width (in x), suggestion from CERN c/o Jonny to test x dependence. Too little time to fabricate new collimators now, could consider machining existing collimators...

   Need to decide which collimators should be remeasured, therefore to quantify relative uncertainty on existing data for the existing 3 runs. Working assumption is that we will keep sandwich 1 (SLAC) populated as for run 3, after reseating collimator in slot 2 to have the same aperture (half gap 1.4mm) as others in this sandwich.

   Luis to try to make summary table of measured collimator kicks for next meeting. We will use this to decide which collimators will be used for run 4.

4. ATF Damage Proposal
   • ATF Damage Proposal Draft (submitted 2 May 2007)
   Nigel to present the proposal to ATF Technical Board at their next meeting at Daresbury, 28-29 May, 45 mins allocated for this, and discuss radiation safety implications.

5. Preparations for PAC
   Brief discussion of readiness of papers, some already started to write contributions.

6. Discussion of T480 run 3 data
   
   • Luis: Noted correlation in reliability of x/y BPM measurements. Cuts on max. bpm_x for sandwich 2 ("SLAC") improve data quality, suggested to use abs(bpm_x <0.5mm), OK for sandwich 2 but most data rejected when applied to sandwich 1.
   • Bunch length measuremnts: Steve reported that remedial work carried out prior to run 3 had removed the double image artefact seen in 2006 data, therefore clean up of the LOLA images offline should allow retrospective improvement of bunch length measurement. Work will be completed relatively soon, as PAC abstract was submitted for this!
   • Mechanical measurements of collimator gaps:
     Discussion of half gaps from coordinate measuring machine at SLAC, for sandwich 2 these are typically ~1.85mm, much larger than corresponding measurements on sandwich 1 (~1.4mm) which agree well with the expectation. Suggested that some systematic accounts for the larger than expected apertures measured.
     Repeat measurements at SLAC either with CMM or by hand using micrometer?
   • Calibrations: status - prospects for improvement - plans (do we need more info. in .mat? q10ukphase, adc0. Nigel to try to modify Mark's root2mat converter to include addition data as necessary. Agreed Jonny would reprocess data using latest calibrations from Mark in meantime.
   • Andre S. slides
     Andre presented status of his study of run3 data, concentrating in detail on 1-2 specific runs to understand differences between what he finds and results of others. Suggested that median may be more robust statistic than mean to describe the deflections, less affected by outliers in the distribution. (Specific run studied, the outliers were the 1% of events with test triggers, usually removed by cut on charge or raw BPM position.)

7. Actions:
8. Next meeting: 08 June, 1600-1700 UK time.