Proton Driver Keith Gollwitzer May 31, 2014

Initial Design Overview For design purposes, the following is assumed –H - beam comes from PIP II and follow-on accelerator which will result in 3GeV beam of 1.9e8 ions/bunch spaced by 162.5MHz PIP II front end where 50% chopped for Accumulator RF filling –A Dual Use Linac (optimized for muon acceleration) will accelerate beam to 6.75GeV. (slide 4) –At 15 Hz, Linacs will run ions for 5ms pulses which will be converted into 4 proton bunches in Accumulator Ring (slide 5&6) –Every 16ms, a single bunch is extracted from Accumulator to Compressor Ring (slide 5&6); bunch rotation followed by extraction to Target Station (later slide) Results in 60Hz NF supported at 1MW May 31, 2014MAP 2014 Spring Meeting--Gollwitzer2

Upgrade Paths Neutrino Factory (60 Hz) –At first glance beam power can be handled in 4 bunches at 15 Hz in Accumulator Bunch compression challenge (slide 7) Muon Collider (≤15 Hz) –Need to send all four Accumulator bunches to Compressor for bunch rotation and extraction Need to design four beam lines to deliver beams simultaneously to target –Need final focus element(s) which handle four beams at one (slide 9) Beam Power into rings can be done by increasing beam per linac bunch as outline previously May 31, 2014MAP 2014 Spring Meeting--Gollwitzer3

Dual Use Linac – Friday am Discussion of possible issues of concerning Linac designed for muon acceleration –Strong focusing solenoids and quadrupoles needed for large muon beam possibly stripping H - ions due to Lorentz transforming B trans and Inter Beam Stripping (IBS). Ratio of normalized ε trans is 1e5 Alignment of Linac is crucial for muon transmission, H - beam on axis should see very little B trans ; quick calculations show there is no problem Need to crank IBS numbers; expect same margin as Lorentz stripping –Muon chicane feeding the DUL uses a strong Dipole PD will calculate amount of loss to see how much is stripped Alex will look at lengthening dipole and reducing field and/or change the angle for chicane Alex will run H - ions through lattice to see what results May 31, 2014MAP 2014 Spring Meeting--Gollwitzer4

Rings – Wednesday am Yuri (and Dave N) design of Flexible Momentum Compaction (FMC) Rings of ~300m designed for 8GeV Concerns about injection of 8GeV H - ions (transport injection beam line avoiding Lorentz stripping and how to contain unconverted ions) led to modified Accumulator design May 31, 2014MAP 2014 Spring Meeting--Gollwitzer5 Accumulator Compressor

Rings – Wednesday am Lattice exists and will work for both 6.75 and 8 GeV Magnet parameters to have sanity check by magnet designers/builders Challenge of injection/stripping of MW(+) H - beam –SNS existence proof of 1 GeV beam Extend to 8 GeV May 31, 2014MAP 2014 Spring Meeting--Gollwitzer6

Rings – Wednesday pm Beam stability –Old instability limit that was being used not applicable to FMC rings –Two weeks ago, asked Alexei Burov to look at 8 GeV 4MW beam in version one of FMC rings; reported first look AR tran : single bunch growth rate ~30ms; coupled bunch growth rate a few ms; he feels chromaticity selection can stabilize beam AR long : coupled bunch growth rate 30s CR tran : both single and coupled bunch modes are a few ms; he feels chromaticity selection can stabilize beam CR long : hit wall during compression; only able to compress a factor of 3 instead of desired factor of 10 –Possible solution is a two stage compression using higher multiple frequencies »Introduces need for more RF space as well as impedance which …. Alexahin, Burov, Lebedev are discussing May 31, 2014MAP 2014 Spring Meeting--Gollwitzer7

Interface w/Target - Wednesday am Made each other aware of where boundaries and possible interferences are –Beam line vacuum will be to a window just down stream of final focus element –Wasn’t exactly set in stone but will look to design final focus element to be 5m upstream Target station solenoid fringe field <1T Will not interfere with power and cooling infrastructure (Far) Future design effort will have to understand how to maneuver replacement of (consumable) target module and the final focus elements {remotely!} May 31, 2014MAP 2014 Spring Meeting--Gollwitzer8

Multi-beam Final Focus -- Wed am No dedicated design effort Magnet designers are aware of Quadrupole Magnet Array design for Heavy Ion Fusion Driver Further work May 31, 2014MAP 2014 Spring Meeting--Gollwitzer9

Prioritized Activities List 1.Transport Line (single beam) concept, lattice & documentation –Is 5m upstream of target correct position? 2.Resolve Compressor Ring longitudinal issue and achieve 3ns rms 3.Cross check rings’ transverse growth rates and stabilization with chromaticity selection 4.Define Accumulator injection line and waste beam handling 5.Rings documentation 6.Document non-issues of H - ions in DUL 7.Ring Stability Simulations 8.Multi-beam line design –Multi-beam final focus element(s) May 31, 2014MAP 2014 Spring Meeting--Gollwitzer10 Can finish in FY14

Activities Transferable to GARD Previous list leaves two items that are “general” to proton/electron sources and not necessarily for muon and neutrino sources –Ring stability simulations for very intense bunches –Multi-beam line designs for simultaneous delivery of beam with multi-beam final focus element(s) One could look further into MW+ injection/stripping for >1GeV as a natural progression including R&D already being done –Rotating foils –Laser stripping May 31, 2014MAP 2014 Spring Meeting--Gollwitzer11