Target insertion matching and standard cell optics optimization 7th Muon collider meeting S.M.Liuzzo

To achieve this an insertion needs to be accommodated in the lattice: outline S. Guiducci suggests to reduce beta and dispersion at the target location. To achieve this an insertion needs to be accommodated in the lattice: Gradients not different from other magnets in the lattice Minimal number of dipoles removed (for space) keep length constant Minimal modification of the cell Easy rematch if cell optics modified This translated in: Matching script for cell Matching script for insertion l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

Half Cell and zoom on region to modify for insertion l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

1m straight for target Modified cell (ARCT) Visible quadrupoles have been modified in length and gradient to achieve the matching 1m straight for target l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

Matching 1) Remove 2 dipoles and rescale bending angle of all other dipoles for 2pi 2) Match ARCA cell to initial optics with new bending angles. 3) Match ARCT final quadrupoles to match required beta and dispersion at target. Quadrupole lengths also adjusted to achieve reasonable gradients. Chromaticity corrected, but no local sextupoles at insertion. Tune not fixed. QD1A: -11.41 T QD2A: -23.52 T QF1A: 29.68 T QF2A: 22.14 T QD1E: -73.54 T QD2E: -28.77 T QF1E: 57.96 T QF2E: 28.79 T QDT: 36.72 T QFT: -26.73 T QD1E: -11.41 T QD2E: -23.52 T QF1E: 29.68 T QF2E: 22.14 T Br=150 Disclaimer: This is a very first approach (V0.5), the insertion is not at all optimal and there are much better solutions. l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

Positron beam size evolution with target (105 e+) l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

Cell optics optimizations Objective: increase # e+ surviving after target First action: verify what is the most relevant parameter for optimization Loss pattern after target interaction. e+ survived vs: momentum acceptance at target (optics,sextupoles) momentum acceptance global (optics,sextupoles) angular acceptance at target ?? (optics, sextupoles) physical apertures (magnets gradients) Second action: look at the most relevant of the above parameters and optimize lattice optics knobs, sextupole fields, … l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

Positrons loss location after target interactions Turn 1 Turn 2 l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

Positrons loss location after target interactions bin = 0.5m bin = 10m Turn 1 Turn 2 bin = 200m l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

Increase negative apertures at high dispersion high hor. beta Increased apertures Standard apertures Standard apertures Increased apertures: Same particles, lost further in the lattice. Increase aperture at high loss locations l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

Positron beam size evolution with target (105 e+) with different P.A. No difference. Particles where already lost on Dynamic Aperture l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

Momentum aperture vs RF voltage After 1 turn, no visible difference After 256 turns, @12MV limited by RF acceptance #MV x2 RF cavity x 32 cells l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

Survived positrons VS RF voltage l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

momentum aperture at target vs Tune and chromaticity [%] 3 turns [%] 3 turns Starting tune: (.08, .20) Optimal tune: (.10, .40) Starting chromaticity: (2,2) Optimal chromaticity: (9,5) Q[FD][12] for tune change S[FD] to keep chromaticity fixed S[FD] to change chromaticity l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

Positron beam size evolution with target (103 e+) : tune & chromaticity Only few e+ more l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

Different target materials l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013

conclusions First attempt for a small beta and dispersion insertion: beam sizes increase is reduced if target at this location Studied lost positrons locations: all the particles are lost right after the target and at high dispersion regions. 5cm physical apertures are not a limitation for the beam acceptance. Positron survival plot as a function of RF cavity voltage Initial scan of tune working point (1 unit only) and chromaticity show some improvement. Much more work needs to be done, need parallelization of tracking with target. Different target materials are studied showing liquid He as the less detrimental for the positron beam. l 7th Muon Collider MEETING l 5 April 2017 l S.M.Liuzzo 26/07/2013