EIC Meeting, Stony Brook University, January 10, 2010

Dmitry Kayran for MeRHIC group

EIC Meeting

January 10 - 12, 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

Electrongun 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+3rd harmonics

100 MeV100 MeV

11 m11 m 10 MeV x 50 mA

0.5 MW Beam Dump

Merger to MeRHIC

Merger from eRHIC Merger to eRHIC100MeV pre-accelerator

MeRHIC: General layout

EIC Meeting, Stony Brook University, January 10, 2010

100 MeV Pre Accelerator ERL

3

Injector ParametersPolarized Gun (200kV)Cathode GaAs,Laser 780nm Emax= 10 MeV Iavr =50 mA, Q per bunch =5nC

Pre-accelerator ERL: One passEnergy gain 90 MeVEinj & Eextr=10 MeVEmax =100 MeV

eBeam parameters : E=100 MeVIavr=50 mAIpeak=500 ARep.rate = 9.8 MHzEmittance =70 mm-mradBanchlength = 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 11 m10 MeV x 50 mA

0.5 MW Beam Dump

from MeRHICarcs

to MeRHIC vertical combiner

10 MeV Booster Linac

30 m

EIC Meeting, Stony Brook University, January 10, 2010

Gatling Gun*)

Parameter Value

Laser longitudinal distribution

Gaussian

Bunch length at cathode 0.5 nsec [FWHM]

Laser transverse distribution

Uniform

Laser spot diameter 8mm

Bunch charge 5nC

Accelerating voltage 200kV

Cathode-anode gap 3cm

Integrated solenoid field 2.1kG-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

3rd harmonic frequency (336MHz) cavity with outer radius of about 35cm

Booster linac (6x112MHz cavity ) boosts the beam energy to 10MeV (L=4.5 m).

So

len

oid

Gun

200 KeV

Spin rotator

So

len

oid

So

len

oid

Bunching Cavity

3rd harmonic cavity

So

len

oid

11 m

10MeV Injector layout

10 MeV booster linacE B

EIC Meeting, Stony Brook University, January 10, 2010

1.4, 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 m10 MeV 10 MeV

10 MeV, 100MeV 100 MeV, 10MeV

100MeV100MeV

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 10 MeV

100 MeV100 MeVStandard main MeRHIC linac cryomodule

Transition section Transition section

703.75 MHz

2.11 GHz

EIC Meeting, Stony Brook University, January 10, 2010

0

50

100

150

200

250

300 350 400 450 500 550

Z, cm

Po

we

r d

en

sit

y, W

/cm

2

0

10

20

30

40

50

Ap

ert

ure

, cm

P, W/cm2

Collector contour

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, 2010

2-3 MeV

2-3 MeV

20 MeV

20 MeV

20 MeV

2-3 MeV

SC RF GunSC 5 Cell cavity

Beam dump

BPM

DCCT

1MW Klystron

SRF Linac50 kW Transmitter ready to operate

Arc assembly

Quadrupole

Dipole

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 (3rd harmonic is needed)– Conservation of beam parameter in merger (Z-bend test will give an answer)– Ion bunch much longer then electron one (703.75 MHz train of e-bunches helps,

will split laser beam to 2/4/8)

For all projects Stability criteria for CW beam currentHalo/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 Current High charge PoP CeC Test *) Pre-cooling @ 40GeV

MeRHIC eRHIC

10/20

Charge per bunch, nC 0.7 5 5 5 14 (9x1.56) 5 18/3.5

Energy maximum/injection, MeV 20/2.5 20/3.0 21/3 21/3 21/3 4000/10 10000/10

20000/10

R.m.s. Normalized emittances ex/ey, mm*mrad

1.4/1.4 4.8/5.3 5 5 3 7-73 77

R.m.s. Energy spread, E/E 3.5x10-3 1x10-2 1.5x 10-3 1.5x 10-3 8 10-4 2x10-3 1x10-3

R.m.s. Bunch length, ps 18 31 30 30 30 6.7 30

Bunch rep-rate, MHz 700 9.383 0.078 9.383 9.383 9.383 14.1

Gun/dumped avrg. current, mA 500 50 0.4 50 130 50 50

Linac average current, mA 1000 100 0.4 0.4/50 130 300 500

Injected/ejected beam power, MW 1.0 0.150 0.0012 0.15 0.390 0.5 0.5

Numbers of passes 1 1 1 1 1 3 5

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, 3rd harmonics

• 90 MeV linac will use:– One MeRHIC standard 10m cryo- module (going on research)– With 5 standard MeRHIC cavities + 3rd 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 20095cell SRF cavity cold emission test (first cool-down March, 14 2009)•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)