DESIGN OF THE BNL PROTON DRIVER
for SUPER NEUTRINO BEAM

W. T. Weng
Brookhaven National Laboratory

NBI2003, KEK
November 7-11, 2003

OUTLINEAGS Upgrade (1MW):
Beam loss considerations
1.2 GeV Superconducting Linac
H- injection study
2.5 Hz AGS power supply and rf system
Target and Horn system

AGS Upgrade (4MW)
Conclusion

AGS Upgrade to 1 MW
To RHICTo Target Station

High Intensity Source
plus RFQ
200 MeV Drift Tube Linac
BOOSTERAGS

1.2 GeV → 28 GeV
0.4 s cycle time (2.5 Hz)

200 MeV
400 MeVSuperconducting Linacs

800 MeV
1.2 GeV
0.2 szz

0.2 s

1.2 GeV superconducting linac extension for direct injection of ~ 1 × 1014 protons
low beam loss at injection; high repetition rate possible
further upgrade to 1.5 GeV and 2 × 1014 protons per pulse possible (x 2)
2.5 Hz AGS repetition rate
triple existing main magnet power supply and magnet current feeds
double rf power and accelerating gradientfurther upgrade to 5 Hz possible (x 2)

AGS Proton Driver Parameterspresent AGS 1 MW AGS 4 MW AGS J-PARC
Total beam power [MW]
0.14
1.00
4.00
0.75
Beam energy [GeV]
24282850
Average current [µA]63614415Cycle time [s]20.4
0.2
3.4
No. of protons per fill
0.7 × 1014
0.9 × 1014
1.8 × 1014
3.3 × 1014
Average circulating current [A] 4.2
5.0
10
12
No. of bunches at extraction
624248
No. of protons per bunch
1 × 1013
0.4 × 1013
0.8 × 1013
4 × 1013
No. of protons per 107 sec.
3.5 × 1020
23 × 1020
90 × 1020
10 × 1020

1.2 GeV Superconducting Linac
Beam energy
0.2 → 0.4 GeV
Rf frequency
805 MHz
Accelerating gradient 10.8 MeV/m
Length37.8 mBeam power, linac exit 17 kW

0.4 → 0.8 GeV
1610 MHz
23.5 MeV/m
41.4 m34 kW

0.8 → 1.2 GeV
1610 MHz
23.4 MeV/m
38.3 m50 kW

Layout of the 1.2 GeV SCLBeam Loss at H- Injection Energy

Beam power, Linac exit, kW
Kinetic Energy, MeV
Number of Protons NP, 1012
Vertical Acceptance A, π µm
β 2 γ3
NP / (β2γ3 A), 1012 / π µm
Total Beam Losses, %Total Loss Power, W
Circumference, mLoss Power per Meter, W/m

AGS Booster PSR LANL SNS

1 MW AGS

32001589
0.57
0.296
5150
2020.850
1200
10055
9.56
0.190
31440
807
1.880
800
31140
4.50
0.049
0.3
240
90
2.7

1000
1000
100
480
6.75
0.031
0.1
1000
248
4.0

AGS Injection Simulation
Injection parameters:
Injection turns
360
Repetition rate
2.5 HzPulse length
1.08 ms
Chopping rate
0.65
Linac average/peak current 20 / 30 mA
Momentum spread± 0.15 %Inj. beam emittance (95 %) 12 π µm
RF voltage
450 kV
Bunch length
85 nsLongitudinal emittance
1.2 eVs
Momentum spread± 0.48 %Circ. beam emittance (95 %) 100 π µm

Halo in AGS as Function of Linac Emittance

For acceptable operation, the linac
emittance has to be less than 1.5π

Linac Emittance Improvement

750 keV Line Upgrade Options
Emittance at source 0.4 pi mm mr (rms,nor)RMS Emittance growth (x,y,z)Comments

Line Configuration

Transmission(A)Present (RFQ, 12 quads,3bunchers, fast & slow chopper)~70 %

450%, 500%, 300%

-7 meter long(B)RFQ + DTL(no 750 keV line)

100 %64%, 40%, 64%-Requires new chopping in LEBT
-0.07 long(C)RFQ +3 quads +2 Bunchers

100 %16%, 0%, 74%-Requires new chopping in LEBT
-0.5 meter(D)Present, with 2 modified
triplet, and splitting fast & slowchoppers

98%31%, 11 %, 222%

-5 meter longOptions Layout

New AGS Main Magnet Power Supply
Repetition ratez Peak powerz Average powerz Peak current
z Peak total voltage
z Number of power converters / feeds

presently:
1 Hz
50 MW
4 MW
5 kA
± 10 kV22.5 Hz110 MW
4 MW
5 kA± 25 kV
6z

6 RING FEEDS+/-5KV
P TYPE/ 5KV PER FEED+/-5KV
P TYPER/L/
66+/-5KV P& F TYPE

L/

R/6

L/6 R/6
SUPER PERIOD C,D6

SUPER PERIOD E,FSUPER PERIOD A,BSUPER PERIOD G,H

R/6

SUPER PERIOD K,L

L/6
R/6

L/6
SUPER PERIOD I,J

R/6 L/6+/-5KV
P TYPE+/-5KVP TYPE+/-5KV P& F TYPEEddy Current Losses in AGS Magnets

For 2.5 (5.0) Hz:
In pipe: 65 (260) W/m
In coil: 225 (900) W/m

AGS RF System Upgrade
Use present cavities with upgraded power supplies (two 300 kW tetrodes/cavity)• Rf voltage/turn• harmonic number• Rf frequency• Rf peak power• Rf magnetic field

0.8 MV24~ 9 MHz
2 MW
18 mT

presently:
0.4 MV
6 - 123 - 4.5 MHz

Neutrino Beam Production• 1 MW He gas-cooled Carboncarbon target• New horn design• Target on down-hill slope forlong baseline experiment• Beam dump well above groundwater table to avoid activation

Super Neutrino Beam Geographical Layout• BNL can provide a 1 MW capable
Super Neutrino Beam for $104M
FY03 (TEC) dollars• the neutrino beam can aim at any
site in the western U.S. theHomestake Mine is shown here)• there will be no environmental
issues if the beam is produced
atop the hill illustrated here andthe beam dumped well above
the local water table• construction of the Super Neutrino
Beam is essentially de-coupledfrom AGS and RHIC operations

Path Towards 4 MW
Linac intensity/pulse
Linac rep. rate
Linac extraction energy
β 2 γ3
Beam power
AGS intensity/pulse
AGS rep. rate
Rf peak power
Rf gap volts/turnAGS extraction energy
Beam power

Upgrade I

Upgrade IIUpgrade III

1.0 × 1014
2.5 Hz1.2 GeV9.654 kW
0.9 × 1014
2.5 Hz2 MW
0.8 MV
28 GeV1 MW

2.0 × 1014
2.5 Hz1.5 GeV14.9
144 kW
1.8 × 1014
2.5 Hz4 MW
0.8 MV
28 GeV2 MW

2.0 × 1014
5.0 Hz1.5 GeV
14.9
288 kW
1.8 × 1014
5.0 Hz8 MW
1.5 MV
28 GeV
4 MW

4 MW AGS Proton Driver Layout

To RHICTo Target Station

High Intensity Source
plus RFQ
200 MeV Drift Tube Linac
BOOSTERAGS

1.2 GeV → 28 GeV
0.2 s cycle time (5 Hz)

200 MeV
400 MeVSuperconducting Linacs

800 MeV

1.5 GeV

0.1 s

0.1 s

Additional Work Planned
1.
2.
3.
4.
5.
6.
7.

Reduction of the Linac Emittance
Cryogenic System Design
LLRF Tuning and Feedback of SCL
Transition Crossing in the AGS
Beam Collimation
Optimization of the Target and Horn System
Improvement of Upgrade Path

Conclusions
1. The feasibility has been demonstrated for a 1MW
upgrade for the AGS
2. It is possible to further upgrade the AGS to 4MW

Such a high power proton driver is essential for very
long base line neutrino experiment and also for theneutrino factory.