ICA Applied to Long Bunches Jeff Kolski Informal workshop on ICS and High Intensity accelerators Indiana University Los Alamos Nation Laboratory 3/17/10 LA-UR

Outline A brief overview of LANSCE operations ICA applied to long bunches Single turn kick experiment Some interesting ICA modes

Los Alamos Neutron Science Center (LANSCE)

Ion Sources Sector J Drift Tube Linac (DTL) (201 MHz) Transition Region (TR) Isotope Production Facility (IPF) Coupled Cavity Linac (CCL) (805 MHz) Proton Radiography (pRad) Ultra Cold Neutrons (UCN) Switch Yard (SY) Area A Lujan Center Weapons Nuclear Research (WNR) Central Control Room (CCR) Jeff’s Office Building 6 Proton Storage Ring (PSR) Google Maps

Proton Storage Ring (PSR) Circumference = 90m Beam energy = 798 MeV Revolution frequency =2.8 MHz Bunch length = 290 ns (73 m) Accumulation time = 625 μs = 1746 turns ES41y ES43q WM41 and WC41 RJM Pinger

Ring Parameters CircumferenceC90.2 m Beam Kinetic EnergyT798 MeV Betatron Tunesν x, ν y 3.19, 2.19 Transition γγ t 3.1 Phase Slip Factorη-.19 Max rf VoltageV rf 18KV Buncher Harmonic, Freqh, f1, MHz Synchrotron Tune (10KV)ν s Mean Pipe Radiusb.05 m

Injection Scheme Linac frequency MHz, 5 ns PSR frequency 2.8 MHz, 358 ns of the Linac frequency Turn 1Turn 2Turn 3Turn 14Turn 15

ICA for long bunches Instead of having several BPMs distributed around a ring, use one digitized BPM signal where each digitization bin is a time slice along the length of the beam. For ICA, the time slices are effectively BPMs along the beam length. The resulting spatial modes then describe the strength of the motion along the beam.

Setup for the Single Turn Kick Experiment Data taken by R. Macek in Oct Accumulate for 1225μs Store for 200 μs Give the beam a single turn kick ~400 turns before extraction to induce coherent betatron motion. Capture digitized BPM data using wc41 and wm41 (vertical sum (vs) and difference (vd), horizontal sum and difference).

… And begins the Fishing Expedition ICA of the vd signal from wm41 yields modes containing transverse information. (coherent tune shift) ICA using the vs signal from wm41 yields modes containing transverse and longitudinal information. (transverse coherent tune shift, longitudinal motion, and injection structure). ICA of wc41 yields the same modes as using wm41vs except with a low frequency bias.

A Betatron mode Mode only appears after the transverse kick. Temporal part of mode FFT peaks at twice the tune.

ICA and Coherent Tune Shift Several ICA modes describe the coherent tune shift. In this example, there are only three double modes. In principle there is an ICA tune mode for each the time slice. ICA yields the modes that most diagonalize the time- lag covariance matrices

Another Betatron mode Strongest betatron modes show double FFT peak. Could transverse profile be non- symetric?

A “Noise” Mode DC temporal mode without much frequency The SV from the time lag correlations are very small.

“Scope” mode Temporal mode is DC Spatial mode even where beam is not. Mode FFT peak ~ the scope clock.

The “Injection” Mode Mode only appears during injection. Mode FFT peaks at (the injection sub- harmonic PSR). 54 peaks in the spatial mode, same number as the injected micropulses per turn.

Combining Injection Modes

Late Injection? are

A Longitudinal Mode Shoulder on the front of the cumsum of the spatial mode. If beam was injected late, does this mode describe the motion of the beam filling the front of the bucket?

Another Longitudinal Mode Delay between the cumsum of the spatial mode and the beam current. Another example of injecting late?

Last Longitudinal Mode Spatial modes has three humps. Peaks at the synchro- nous phase and ± 90°.

Continuing Work Experimentally verify the ICA modes Understand how the number of turns, modes, time lags, and BPMs effect the ICA. Simple simulations

Acknowledgements A special thanks to ▫SY Lee and Xiaoying Pang (Indiana University) ▫Bob Macek and Rod McCrady (LANL)