Recent Progress Toward a Muon Recirculating Linear Accelerator

1. Recent Progress Toward a Muon Recirculating Linear Accelerator S.A.Bogacz, V.S.Morozov, Y.R.Roblin1, K.B.Beard2, A. Kurup, M. Aslaninejad, C. Bonţoiu, J.K. Pozimski 1Jefferson Lab, Newport News,VA, 2Muons, Inc., Batavia, IL, 3Imperial College of Science and Technology, London, UK 26 26 5 30 Size_Y[cm] Size_X[cm] BETA_X&Y[m] DISP_X&Y[m] 0 0 0 Ax_bet Ay_bet Ax_disp Ay_disp 202 Beta_X&Y[m] DISP_X&Y[m] 0 0 0 BETA_X BETA_Y DISP_X DISP_Y 389.302 5 15 BETA_X&Y[m] DISP_X&Y[m] 0 BETA_X BETA_Y DISP_X DISP_Y 30.5 0 0 0 BETA_X BETA_Y DISP_X DISP_Y 78.9103 Muons, Inc. 3 20 G[kG/cm]=0.3 B[kG]=9.9 Arc 1 1.2 GeV 6 m cells 1 m dipoles bx = 13.0 m by = 14.4 m ax=-1.2ay=1.5 1 m Pre-linac 244 MeV 900 MeV bx = 7.9 m by = 8.7 m ax=-0.8ay=1.3 244 MeV Arc 2 Arc 3 Arc 4 1.75 m Arc 1 20 +1 202 m bx = 6.3 m by = 7.9 m ax=-1.2ay=1.3 bx,y → bx,y axy → - axy BETA_X&Y[m] bx = 3.2 m by = 6.0 m ax=-1.1ay=1.5 DISP_X&Y[m] Double achromat Optics βxβyDx Dy bx,y → bx,y axy → - axy (2.5)2eN = 30 mm rad 3 GeV bx,y → bx,y axy → - axy bx,y → bx,y axy → - axy 900 MeV (2.5)2 sDpsz/mmc= 150 mm RLA I qin = 12.46 qout = 11.53 1.8 GeV -3 0 3.6 GeV 0.9 GeV 0 BETA_X BETA_Y DISP_X DISP_Y 113.5 86 m 0.6 GeV/pass 10 cells in qs = 11.53 1.2 GeV -V V V -V B[kG]=9.9 G[kG/cm]=0.6 -H -H 2 cells 3 24 short cryos 20 Arc 3 2.4 GeV 26 medium cryos 8 m cells 2 m dipoles -1 0 2.4 GeV 4 cells 3.6 GeV quad gradient -V V V -V H H -H RLA II -H 3.6 GeV 12.6 GeV BETA_X&Y[m] DISP_X&Y[m] 2 cells 255 m 2 GeV/pass 4 cells 3.0 GeV 0.9 GeV 1.2 GeV 1.8 GeV 2.4 GeV 3.6 GeV qin = 13.79 qout = 14.19 -3 0 0 BETA_X BETA_Y DISP_X DISP_Y 143.611 qs = 5.72 9 cells in PRELINAC Accelerates μ± from about 244 to 900 MeV total energy and accepts a high emittance beam about 30 cm wide with a 10% energy spread. ABSTRACT Both Neutrino Factories (NF) and Muon Colliders (MC) require very rapid acceleration due to the short lifetime of muons. After a capture and bunching section, a linac raises the energy to about 900 MeV, and is followed by one or more Recirculating Linear Accelerators (RLA), possibly followed by a Rapid Cycling Synchnotron (RCS) or Fixed-Field Alternating Gradient (FFAG) ring. A RLA reuses the expensive RF linac section for a number of passes at the price of having to deal with different energies within the same linac. Various techniques including pulsed focusing quadruopoles, beta frequency beating, and multipass arcs have been investigated via simulations to improve the performance and reduce the cost of such RLAs. FUTURE PLANS The neutrino factory baseline is being redesigned in light of recent experimental results; it is anticipated that only ~10 GeV is required, so the prelinac and RLAs will need be reoptimized and will feed a decay ring directly. PRELINAC TO RLA CHICANEThe current chicane separates the μ± with a dipole, then each is directed down 1.75m into the plane of RLA I, then directed by dipoles into the middle of the linac. On subsequent passes, the injection dipole separates the returning μ±, so a mini-chicane in the linac is used to correct the paths. INTERNATIONAL DESIGN STUDY The International Design Study for the Neutrino Factory (IDS-NF) baseline designinvolves a complex chain of accelerators including a single-pass prelinac, two recirculating linacs (RLA) and a fixed field alternating gradient accelerator (FFAG).[1] prelinac RLA I MULTIPASS ARCS By combining two arcs into one multipass arc, it is possible to greatly simplify the RLA by eliminating one arc’s chicanes and most of the switchyard. RLA II (arcs not shown) Beta functions in RLA I arcs 1 & 3 The arc’s cells are constructed of linear combined-functions magnets with variable dipole and quadrupolefield components. Unlike a fixed field alternating gradient design, opposing bends are not required. While pulsed quadrupoles could allow as many as 7 ½ passes, they aren’t needed for 4 ½ passes. Beta function beating in the RLA I linac. * Funding: Supported in part by US DOE STTR Grant DE-FG02-08ER86351. Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.