EIC Meeting, Stony Brook University, January 10, 2010 Dmitry Kayran for MeRHIC group EIC Meeting January , 2010 MeRHIC: Injection System

EIC Meeting, Stony Brook University, January 10, 2010 (April 09) Linac 1 Linac 2 Main ERLs; 6 cryomodules x 6 cavities x 18 Mev/cav = 0.65 GeV per linac 0.75, 2.05, 3.35 GeV 4 GeV 0.1, 1.4, 2.7 GeV Pre-accelerator 90 MeV ERL Electron gun 0.1 GeV IR2 region features: - asymmetric detector hall (appropriate for asymmetric detector for e-p collisions) - long wide (7.3m) tunnel on one side from the IR (enough space to place energy recovery linac(s)) Main components: -100 MeV injector on the basis of polarized electron gun (50 mA) and pre-accelerator ERL. -Two main ERLs (one of them in the RHIC tunnel) with maximum 0.65 GeV energy gain per linac. -Recirculation passes are going outside of the existing tunnel: warm magnets, acceptable synchrotron radiation power. 10 MeV Injector 90 MeV Linac 1 cryomodule 5 cavities+3 rd harmonics 100 MeV 11 m 10 MeV x 50 mA 0.5 MW Beam Dump Merger to MeRHIC Merger from eRHIC Merger to eRHIC 100MeV pre-accelerator MeRHIC: General layout

EIC Meeting, Stony Brook University, January 10, MeV Pre Accelerator ERL 3 Injector Parameters Polarized Gun (200kV) Cathode GaAs, Laser 780nm Emax= 10 MeV Iavr =50 mA, Q per bunch =5nC Pre-accelerator ERL: One pass Energy gain 90 MeV Einj & Eextr=10 MeV Emax =100 MeV eBeam parameters : E=100 MeV Iavr=50 mA Ipeak=500 A Rep.rate = 9.8 MHz Emittance =70 mm-mrad Banchlength = 2-3 mm dE/E = 1E-3 Gatling Gun (Ek=200keV) 10 MeV Injector 90 MeV Linac 1.4, 2.7, 4 GeV 11 m 10 MeV x 50 mA 0.5 MW Beam Dump from MeRHIC arcs to MeRHIC vertical combiner 10 MeV Booster Linac 30 m

EIC Meeting, Stony Brook University, January 10, 2010 Gatling Gun *) ParameterValue Laser longitudinal distribution Gaussian Bunch length at cathode0.5 nsec [FWHM] Laser transverse distribution Uniform Laser spot diameter8mm Bunch charge5nC Accelerating voltage200kV Cathode-anode gap3cm Integrated solenoid field2.1kG-cm Dogleg funneling system is spin transparent Electrostatic kicker Rotating field kicker ~ 50 mA from injector is needed. State of the art electron polarized source is 1 mA. The multi cathode to reduce load on a single cathode can be used. Each cathode illuminated by individual laser *) the Gatling gun is the first successful machine gun, invented by Dr. Richard Jordan Gatling. Electrostatic kicker

EIC Meeting, Stony Brook University, January 10, 2010 Laser No Commercial Laser to meet the need! LDRD for laser development 2W/mA (780 nm, 0.1% QE) Three possible approaches: –Fiber oscillator  Fiber amplifier  2ћω to 780 nm –Ti:S Oscillator  Ti:S amplifier 780 nm –Diode oscillator  Power amplifier 780 nm All three approaches will be evaluated Best selected, built & test to drive up to 2 mA Expected Results Laser to drive one cathode of the multi cathode gun Laser system scalable to deliver full EIC electron beam 2 LDRD’s for the new injector and laser have been approved

EIC Meeting, Stony Brook University, January 10, 2010 Beam pipe radius: 5cm DC Gun voltage 200 kV, GaAs cathode, with funneling system (L=1.5 m). Spin rotator ( Wien filter: B=36Gs, E=751 kV/m, 1m, spin rotation 90 degrees). Bunching cavity is a low frequency (112MHz) cavity with outer radius of about 105cm 3 rd harmonic frequency (336MHz) cavity with outer radius of about 35cm Booster linac (6x112MHz cavity ) boosts the beam energy to 10MeV (L=4.5 m). Solenoid Gun 200 KeV Spin rotator Solenoid Bunching Cavity 3 rd harmonic cavity Solenoid 11 m 10MeV Injector layout 10 MeV booster linac EB

EIC Meeting, Stony Brook University, January 10, , 2.7 GeV and 4 GeV beam lines are separated vertically. Each pass can be tuned separately. 30 m Low/High Energy Switch yards 11 m 10 MeV 10 MeV, 100MeV100 MeV, 10MeV 100MeV 2 Dog-Legs (at 10MeV): 2 x30°dipoles,B=560 Gauss L=30 cm 6 quadrupoles 2 Dog-Legs(at 100MeV): 2 x30° dipoles, B=5.6 kGauss, L= 30 cm 6 quadrupoles Beam Dump Injector

EIC Meeting, Stony Brook University, January 10, 2010 MeRHIC Pre-accelerator: 90 MeV Linac Pre-accelerator linac: Standard MeRHIC linac cryomodule (L~10m) with 5x703 MHz 5-cell cavities and one 3rd harmonic 2.11 GHz inside. Two transition sections (L=0.5 m each) attached from both ends Energy gain 90 MeV 10 MeV 100 MeV Standard main MeRHIC linac cryomodule Transition section MHz2.11 GHz

EIC Meeting, Stony Brook University, January 10, 2010 R&D ERL: Beam dump Simulation Setup: Bending dipole: 30 degree, R=60 cm Spreader: focusing solenoid: L= 10 cm, B= 2.7 kGauss Particles trajectories in collector Power density distribution Strong solenoid Modified 1MW CPI Klystron beam collector to accept 1MW= 2 MeV x 500mA beam (MeRHIC parameters: 10 MeV x 50mA=0.5 MW)

EIC Meeting, Stony Brook University, January 10, MeV 20 MeV 2-3 MeV SC RF Gun SC 5 Cell cavity Beam dump BPM DCCT 1MW Klystron SRF Linac 50 kW Transmitter ready to operate Arc assembly QuadrupoleDipole Tested in BLD912 ready for gun First cool- down, March, 2009 T=2K Measured, ready to be installed BNL R&D ERL: Status SRF Gun

EIC Meeting, Stony Brook University, January 10, 2010 Major issues to be addressed at BNL R&D ERL eRHIC/MeRHIC: – very high average current  SRF injector  BBU,  e-dump Proof of principal of coherent e-cooling / conventional pre-cooling –High charge per bunch –Low energy spread and emittances (3 rd harmonic is needed) –Conservation of beam parameter in merger (Z-bend test will give an answer) –Ion bunch much longer then electron one ( MHz train of e-bunches helps, will split laser beam to 2/4/8) For all projects Stability criteria for CW beam current Halo/losses control (G5 test will give us more information, first study then collimators at low energy in injection line will be installed )

EIC Meeting, Stony Brook University, January 10, 2010 ERLs beam parameters R&D ERL design BNL ERL projects requirements High CurrentHigh chargePoP CeC Test 40GeV MeRHICeRHIC 10/20 Charge per bunch, nC (9x1.56)518/3.5 Energy maximum/injection, MeV20/2.520/3.021/3 4000/ / /10 R.m.s. Normalized emittances ex/ey, mm*mrad 1.4/1.44.8/ R.m.s. Energy spread,  E/E 3.5x x x x x10 -3 R.m.s. Bunch length, ps Bunch rep-rate, MHz Gun/dumped avrg. current, mA Linac average current, mA / Injected/ejected beam power, MW Numbers of passes

EIC Meeting, Stony Brook University, January 10, 2010 Summary 100 MeV Pre Accelerator main elements: 10 MeV Injector: –the most challenging Polarized Gun/Cathode/Laser (approved 2 LDRD starts in 2009 ) –Spin rotator & power supply –Booster, Bunching, 3 rd harmonics 90 MeV linac will use: –One MeRHIC standard 10m cryo- module (going on research) –With 5 standard MeRHIC cavities + 3 rd hormonic Doglegs and matching sections – Magnets & Power supplies (dipoles, solenoids, quadrupoles, correctors) Beam dump is modified CPI Klystron electron beam collector similar what used for BNL R&D ERL Based on simulations: 10 MeV Injector will provide e-beam with required parameters both longitudinal and transverse Beam dynamics of high energy part (100 MeV) pre accelerators does not look challenging but needs to be done The R&D ERL (2011) will address key questions relevant to MeRHIC/eRHIC ERLs. High average current ERL operation R&D ERL can be used to proof-of-principal coherent electron cooling

EIC Meeting, Stony Brook University, January 10, 2010 Thank you!

EIC Meeting, Stony Brook University, January 10, 2010 Commisionnig plan: ERL fully operational in 2011 We start commissioning of the R&D ERL in cell SRF cavity cold emission test (first cool-down March, ) First, we develop the straight pass (gun -- 5 cell cavity -- beam stop) test for the SRF Gun performance studies. (end of 2010) #Metal cathode (low charge per bunch) #Multi-Alkaline Cathode (up to 5nC per bunch) Next, a novel concept of emittance preservation in a beam merger at the lower energy will be tested ( 2010) After recirculation loop completed, demonstrate energy recovery of high charge and high current beam.The prototype will serve as a test bed for studying issues relevant for very high current ERLs ( 2011 ) Proof of principle coherent electron cooling ions in RHIC at ~ 40 GeV/n is feasible with existing R&D ERL parameters ( ERL available around 2012 )