f Project X: 8 GeV Recycler Injection S. Nagaitsev, D. Johnson, J. Lackey Fermilab Accelerator Advisory Committee August 8, 2007 D. Johnson

f 2 Outline  Background  H - Transport  Design  Matching  Beam Loss  H - Injection  Injection Optics  Transverse Painting  Foil Issues  Beam Loss at Injection  Longitudinal Painting  Injection Absorber  Summary/Conclusions  Many of the slides today will discuss the design/development under HINS R&D and its application for Recycler H - injection. 2 Aug 8, 2007 AAC meeting D. Johnson

f 3 Background  Previous experience:  Fermilab Booster (400 MeV)  SNS (~ 1 GeV) plus a collection of others at 800 MeV (LANL)  The Proton Driver collaboration has performed extensive studies for the injection into MI:  H - Transport and Injection Mini-Workshop Dec. 9-10, 2004 at Fermilab: - workshop/hminus.html  Proton Driver’s Director Review: March, 2005 Many of the issues raised have been addressed under HINS R&D effort  “Found NO show stoppers”  We have a design for the MI; we can adopt it to the Recycler  Fermilab-Conf AD “An 8 GeV H- Multi-turn Injection System for the Fermilab Main Injector”  H - transport and stripping injection are considered together  Fermilab-Conf AD “Design of an 8 GeV H- Transport and Multi-turn Injection System”  BNL collaboration (HINS R&D) in optimization of the foil-stripping injection system  Collaboration ongoing  Items addressed include, transport line design and collimation, Electron catcher simulations, Foil peak temperature and temperature distribution, and in the future the Chicane magnet design  Continued carbon foil development (KEK, TRIUMF, SNS) Aug 8, 2007 AAC meeting D. Johnson

f 4 Transport Line (1) - Design  Design (developed under HINS R&D program)  Length ~1 km, 60 o FODO, max/min beta 75m/25m  Dipole field < 500G  Quad ~ 10kG/m  Elevation: MI ( ’)  Options for Recycler Injection Change elevation of Linac to ’ Add vertical achromat in matching section F 4 ABC DE F A: matching from Linac B: betatron collimation (clean up halo from Linac) C: CW achromat with momentum collimation D: Straight section E: CCW achromat F: Injection matching with longitudinal phase rotator (and vertical achromat) Aug 8, 2007 AAC meeting D. Johnson

f 5 Transport Line (2) - Matching  Matching from Linac to Transfer line  Flexible matching (gradients < 12 kG/m)  Matching into Main Injector (Recycler)  Beam waist at foil in both planes (flexible beam size)  Achromat (position stability on foil) ILC LinacPD Linac Beam size on foil matters 7.6 mm foil 8.3 mm absorber Aug 8, 2007 AAC meeting D. Johnson

f 6 Transport Line (3) - losses  A standard figure of merit for residual activation of accelerator components for hands on maintenance is 100 mrem/hr. This corresponds to a beam loss of 0.25 w/m on an unshielded beam pipe. Inside a shielded magnet losses of 3-10 w/m produce residual activation levels of 100 mrem/hr. [TM-2169]  For average residual activation levels in the transport line we would like loss rates a factor of 5 less at 20 mrem/hr  Beam pipe < 0.05 w/m  Magnets 0.6 to 2 w/m  It is always good to have residual levels even lower Aug 8, 2007 AAC meeting D. Johnson

f 7 Transport Line (4) - Losses  Multi-particle beam loss  Controlled (halo & momentum collimation)  Un-controlled (beam hitting aperture) Alignment, aperture ratio (magnet pole tip selection) Dipoles (reuse B2 with 4x2” aperture & new quad with 3” pole tip) – min ratio 3.5 (in V plane w/liner); typical 8-10  Single-particle beam loss (uncontrolled)  Black-body radiation (8x o K) Cryo shield-> lower detachment rate -> preliminary design  Gas stripping (1x torr, A150 line)  Magnetic Lorentz stripping (3.8x G)  Simulations (STRUCT, TRACK) 7 loss mechanism 360 kW360 kW with shield2.1 MW with shield [m -1 ][w/m][m -1 ][w/m][m -1 ][w/m] Black body8.00E E E E E E-03 Residual Gas (A torr)1.00E E E E E E-04 Magnetic (500 G)3.80E E E E E E-04 Total9.00E E E E E E-03 Aug 8, 2007 AAC meeting D. Johnson

f 8 Transport Line (5) – End-2-End Simulations  End-to-end simulations, from RFQ to injection foil, including errors, have been performed for PD and ILC like linac configurations  Transverse collimation for beam shaping on foil has been included  Longitudinal phase rotator cavity located in injection matching section has been included  Single particle loss mechanisms are being implemented to provide a more complete understanding of loss distributions and mitigation schemes.  Longitudinal and transverse phase space at foil are available for injection painting simulations Aug 8, 2007 AAC meeting D. Johnson

f 9 H- Injection – Injection Optics  Symmetric injection straight section for MI  Complete injection system contained within doublets. DC horizontal chicane Foil located at waist Zero dispersion at foil Adjustable circulating beam size (beta’s) Optics for injection absorber determined from transport line  Recycler  Recycler composed of permanent magnets – need to implement straight section design in Recycler 9 Aug 8, 2007 AAC meeting D. Johnson

f 10 H- Injection – Transverse painting  Phase space distribution  Minimize space charge tune shift-> KV-like uniform dist.  Transverse emittance -> 25  -mm-mr  Transverse painting algorithm  Anti-correlated to produce uniform x-y distribution  Algorithm proposed by KEK utilized in program STRUCT  Paint horizontally from inside phase space to outside by displacing horizontal closed orbit  Paint vertically by vertical angle mismatch (from large to zero) from beam line while keeping vertical position on the foil fixed.  Simulations performed for 1 and 3 ms single pulse injections (HINS R&D) – program STRUCT  Algorithm extended to 3 pulses of 1 ms injection each Aug 8, 2007 AAC meeting D. Johnson

f 11 H- Injection – Transverse painting (2) End 1 st injection End 2 nd injection End 3 rd injection Foil (injected beam) Closed orbit movement Move off foil Start injection Stripping foil Closed orbit Final distribution after painting to 25  at  H of 70 and  V of 30 (STRUCT) H- Foil H+ inj abs painting Chicane (DC) Cartoon of phase space painting with 3 linac pulses Horizontal orbit motion during painting Painting waveform for Recycler Injection Aug 8, 2007 AAC meeting D. Johnson

f 12 H- Injection – Foil Issues (1)  Foil Thickness/composition  Selection of foil thickness is a compromise between stripping efficiency (H + production and H 0 production), impact of single and multiple coulomb scattering and nuclear interactions.  New diamond like foils (TRIUMP)  Stripping Efficiency  Calculations (up to 100 GeV) and measurements ( up to 800 MeV) show good agreement -> OK to use calculations at 8 GeV  Utilize foil between 400 and 600  g/cm 2  Want < 2% un-stripped H - or H 0 in n=1 or 2 state for transport to the dump  Want to capture all states with n>2  Stripped Electrons  Same velocity as protons  For current design electrons strike 11 cm downstream of foil on horizontal plane - to be collected by e-catcher  Design folded into foil changer system ->not yet done. Charge State 425  g/cm  g/cm 2 H n= n= n= H E-4 Total H+ captured Aug 8, 2007 AAC meeting D. Johnson

f 13 H- Injection – Foil Issues (2)  Foil Heating (determines foil lifetime)  Simulations done for Proton Driver assuming 1E14/sec in either 1 ms or 3 ms injection and rep rate of.1 s or 1.5 s and incident beam sigma of 1, 1.5 and 2mm with and without circulating beam hitting foil. Peak temperature strong function of incident beam sigma Minimum equilibrium temperature reached after only 1 cycle even for 10 Hz. (297 o K -> 600 o K) need much higher freq to get temp. buildup Circulating beam hits uniformly distributed produces only small impact of peak foil temperature. For 1mm sigma with 3mm inj and 9 secondary hits –Peak temperature 2200 o K  Project X instantaneous intensity 3X LOWER Peak temperature estimated as 2200/3 ~ 750 o K Minimum equilibrium temp at 5Hz < 600 o K  Circulating beam hits  Can be reduced with decrease in foil transverse size.  More discussion under injection losses Aug 8, 2007 AAC meeting D. Johnson

f 14 H- Injection – Losses (1)  In the immediate injection area  Due to 1 st turn interaction with foil Electrons stripped from H - -> guide to electron catcher First turn H - missing foil –beam shaping with TL halo collimation –Transport to injection absorber H 0 excited state stripping in downstream magnets –Fix peak chicane dipole field < n=1,2 state (5.5 kG) –Taylor end field fall off to reduce spread in bend angle –Transport to injection absorber Nuclear collision length and inelastic interaction length are 60 and 86 g/cm 2, respectively - probability of interaction in thin foil ~6-8 x10 -6 leads to < 1 watt  Due to circulating proton interaction with foil Multiple coulomb scattering, small effect < 3  r/passage Inelastic interactions lead to less than 10W (10 hits/particle) Aug 8, 2007 AAC meeting D. Johnson

f 15 H- Injection – Losses (2)  Remainder of ring  Formation of beam halo due to large angle scattering  Calculate distribution function after passage thru thin foil  Estimate by passing a beam with 25  KV-like distribution through 500  g/cm 2 foil once  Relative # scattered outside 40  admittance ~ 7x10 -5 per passage  For 5 passages ->150 W  Need collimation system  Estimates very conservative Aug 8, 2007 AAC meeting D. Johnson

f 16 H- Injection – Longitudinal painting  Requirements  Recycler longitudinal emittance much be matched to that of the MI at injection.  Required MI longitudinal emittance between 0.4 to 0.5 eV-sec.  Assume Dual harmonic RF system 1 st harmonic amplitude 750 kV -> 99% bunch emittance of 0.5 eV-sec 2 nd harmonic voltage = ½ amplitude of 1 st harmonic  Beam parameters -> need painting  Linac rms bunch length (6 ps)/RR bucket length (19 ns) ~ 3E-4  Linac DE (full) ~ 2 MeV  Frequency mismatch  Linac freq (325 Mhz)/RR inj freq ( Mhz) ~  Linac chopper to remove 2 out of 6 linac bunches provides longitudinal painting in phase  Simulations  ESME simulations for 3ms microbunch injection with only ½ voltage assumed for Project X and only phase painting under HINS R&D -> bunch emittance of ~.25 eV-sec (99%) -> need x2 larger -> 2x voltage  Add in Energy painting by adjusting phase of longitudinal bunch rotator in transport line. Aug 8, 2007 AAC meeting D. Johnson

f 17 <100 mR/hr ~500 mrem/hr 30 mrem/hr 900 mrem/hr 40 mrem/hr Added 6” Marble 70 mrem/hr (wall) H - Injection – Injection absorber  Accepts un-stripped ions & H - that miss foil  Conceptual design for internal injection absorber (HINS) Developed for nominal 6.6 kW (1E20 protons/year) Easily meets all radiation safety criteria( prompt, residual, and surface and ground water contamination) Mechanically robust (temperature profile up to 132 kW) Short transport (with large aperture) from foil to absorber to minimize loss MARS and ANSYS calculations performed  Project X- 9 mA, 1 ms, 5 Hz -> 360 kW 2% to injection absorber -> 7.2 kW 5% to injection absorber -> 18 kW  Revisit design to verify new intensities Aug 8, 2007 AAC meeting D. Johnson

f 18 Summary  Future Work  Recycler lattice modifications for symmetric injection straight  Inclusion of single particle mechanisms into TRACK for loss distribution predictions  Design of Recycler collimation of particles with emittances > 40   Simulation of injection losses/ activation from foil interactions using MARS  Painting algorithm looks promising- continue development  Injection absorber design looks promising for Project X usage, although we need additional simulation for added beam power  Conclusions  Lower foil temperatures -> good foil lifetime  Power supply for painting waveform -> extension from HINS R&D  Robust transport line design – can be adapted for Recycler injection  Bottom line -> No show stoppers are seen for incorporating Recycler injection into Project X Aug 8, 2008 AAC meeting D. Johnson