Machine Physics at ISIS

1. Machine Physics at ISIS Proton Meeting 24th March 11 Dean Adams (On behalf of ISIS Accelerator Groups)

2. Machine Physics at ISIS • ISIS delivers ~ 225 µA, 800 MeV proton beam @ 50 Hz onto 2 neutron and 1 muon target for condensed matter and muon research. • Accelerator chain consists of: • 60 mA H- Ion source • 665 KeV RFQ • 70 MeVLinac • HEDS transport line • 70 – 800 MeV RCS running at 50 Hz • 800 MeVbeamlines feeding 2 neutron and 1 muon target. • Beam diagnostics include : Intensity , position, profile, temporal and beam loss. • Machine Physics measurements/simulations presented focus mainly on those which support ISIS operations.

3. Injector Machine Physics Chop a 100 ns injector pulse (1/15th turn) Inject into ring with RF off. Beam de-coheres over 100 turns giving dp/p Two Beam pickups in the HEDS TOF dt = 3.125 ns = 71.8 MeV

4. 70 MeV HEDS beam line Beam Profiles Measured using wire scanner monitor Vertical envelope Beam Half width (mm) Horizontal envelope Envelope and alignment control based on MAD models and IDL front end software. Phase Space matching studies at foil

5. Injection Dipoles Closed Orbit Dispersive Closed Orbit Measured betatron amplitude Fitted betatron amplitude Measured closed orbit Fitted closed orbit Foil Injected Beam Injection Septum Vertical Sweeper Synchrotron: Injection Painting H- charge exchange injection , 70 MeV , Accumulate ~3e13 ppp, 200 µs (133 turns) Anti-correlated Painting Horizontal Vertical 600 ns chopped beam ( 2/5th turn) measured on 2 ring position monitors

6. 2.5x1013 ppp -0.3ms -0.3ms -0.2ms -0.2ms -0.1ms -0.1ms Injection Measurements vs ORBIT Simulations Horizontal Vertical Horizontal Vertical Vertical Anti Correlated Anti Correlated Correlated

7. Coherent Tune Measurements Fractional Tune Measurement available: During injection with chopped beams During Acceleration with fast magnetic kickers Position (mm) Turns Vertical Q vs Intensity per bunch at 3 ms 0.26 Abs(FFT) Freq(n-Q) Intensity per bunch E13

8. Measurement of Beam Widths ISIS Q law Horizontal Profile Scan -0.4 – 2 ms π mm mrad turns ORBIT 3d Simulation Results

9. Ring Closed Orbit and Envelope Control Closed Orbits use 10 position monitors 7 steering magnets per plane MAD model and MICADO or SVD Relative Beta Envelope Measurement based on injected 600 ns chopped beam measured on 10 position monitors per plane. Correction uses 20 Trim quadrupoles and MAD model – In comissioning phase.

10. Longitudinal Measurements (V = Vh=2 sin (φ)) Measure Position Monitor Electrode sum signal over acceleration Split into turns wrt RF Phase Turns Profile @ 0ms Phase Tomographic Reconstruction at 0 ms ORBIT 1d Simulation

11. Longitudinal Measurements V = Vh=2 sin (φ) - Vh=4 sin (2φ+Ѳ) Measure Position Monitor Electrode sum signal over acceleration Split into turns wrt RF Phase Profile @ 0ms Tomographic Reconstruction at 0 ms ORBIT 1d Simulation

12. Beam loss Measurements ORBIT Simulation , Adam Dobbs, Imperial) No Space Charge 39 ring beam loss measurements over ISIS Cycle ORBIT Simulated Loss with 2.5d space charge Measured Sum Ring Beamloss Time (ms)

13. Dipole 2 Scintillators • Collector system is made of 13 copper/graphite collectors used to stop ~ 5 KW of beam lost during ISIS trapping and acceleration. Beam not collected can be dumped in dipole 2 leading to RF screen damage. • Array of 12 scintillators ~ 20hx10v cm inside dipole

14. Q13 -1.2m lattice 800 MeV Beamlines to Target 1 and 2 EPB1 Muon and Neutron Targets MAD Lattice Models allow envelope and trajectory control on EPB1 (left) and EPB2 (bottom) Beam Half width (mm) EPB2 Neutron Target Beam Half width (mm)