1. Momentum and Momentum Spread Measurements

2. Momentum Measurement For Dipole 1 New addition to procedure
 (in MeV/c) = I (in Amps)
as implemented in the magnet table
New addition to procedure
measure charge on BPM-02 and BPM-03 to make sure all beam is measured
Is BPM-03 a better measure of 45 than YAG-04?
Need shot-by-shot measurement of beam centroid on YAG-04 to use!

3. Momentum v. Phase
New data shows no change from ‘run 3’ and ASTRA simulations (parameters not identical)

4. Momentum v. Power
New data shows same behaviour as previous experiments
Fit parameter indicates effective shunt impedance of 23.3 M/m
Missing momentum is still missing!

5. Momentum Spread Measurement
Beam size given by
If x is minimised using QUADS 1 - 4
Can calculate momentum spread from dispersion D and the beam size at YAG-04

6. Dispersion
Calculate
QUADS 5-6 must be off – may be a problem if beam image is large
Does not account for any residual fields
Calculated = pixels
Measured = pixels
Measure
Take data for three or more magnet settings/image positions on the screen
Measure on-the-fly
Measure dispersion for each data point

7. Measurement on-the-fly
Bottom 5 points taken at low charge – not representative!
Even then there is considerable statistical variation on dispersion for nominally identical measurements
Using an average value for dispersion produces smoother parameter response (all data re-analysed this way)
Measuring dispersion up-front and using a single value may lead to a small systematic error but removes large random error allowing trends to be seen more easily

8. Data extraction Summation Doesn’t assume particular line shape
Quick – no fitting!
Susceptible to problems with background
Gaussian Fitting
Seems to get width of signal even for non-Gaussian profiles
Still has issues with background at low charge
By-eye (pencil and paper)
Allows intelligent background subtraction
Cannot be used for large data sets

9. Momentum Spread v. Solenoid
Previous data showed higher momentum spread at optimum solenoid settings for transverse properties
Not confirmed by first re-measurement
Single shot data!
Subsequent data
Low charge data not good
Some hint in higher charge data
More detailed scans required
ASTRA simulations would also be good

10. Momentum Spread v. Phase
Previous data looked convincing
Minimum momentum spread not identical to simulation but parameters differ
Single shot data, phase for minimum momentum spread depends on analysis technique!
x not minimised
x not minimised
Data collected so far does not allow the phase for minimum momentum spread to be accurately assessed!

11. Momentum Spread v. Phase (TDC)
Two data sets, one with the beam set up for TDC work (y minimised?) and one with both x and y ‘minimised’ and TDC actually on.
x minimisation not good enough on either set to be useful
Getting slice momentum spread measurements could be extremely challenging!

12. Momentum Spread v. Charge
Previous work
Low charge data limited by clipping
New data
Low charge data influenced by background subtraction issues
Clipping in the magnet vessel

13. Charge Dependence Along the Beamline
BA2 – Measure on YAG-09, careful setting of QUAD-12 required BA1 – Measure on BA1-YAG-02, beam transport could be an issue, no QUADs after dipole so no control of dispersion

14. Charge Dependence Along the Beamline
Some interpolation and limited extrapolation
Is behaviour as expected?
Charge transport to BA1 an issue?
ICT in BA1
BPMs for charge measurement
AP shifts for characterising beam in BA1?

15. Summary Momentum measurements Momentum spread measurements
New data confirms previous results – momentum still missing!
Momentum spread measurements
Lots of data but much of it useless - need to improve procedures!
 minimisation
Eliminating background issues (turning lights off, subtracting dark images, optimising data extraction)
Shot-to shot YAG image analysis, automated data collection routines?
Important beam parameters not accurately measured
Phase for minimum energy spread
Evolution of charge dependence along the beamline
Simulations with matching parameters to data would help!