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Design of Proton Driver for a Neutrino Factory

W. T. Weng

Brookhaven National Laboratory

NuFact Workshop 2006

Irvine, CA, Aug/25, 2006

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Outline

• Examples of parameter dependence

• Possible design parameter phase space

• Improvements on existing designs and

example of new design

• Summary and Conclusions

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Considerations of parameters - I

To deliver 4 MW beam power on target,

we consider the effects of

1. Energy

2. Repetition Rate

3. Intensity

4. Bunch Length

Of the Proton Driver

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Proton per pulse required for 4 MW

10 Hz 25 Hz 50 Hz

10 GeV 250 × 1012 100 × 1012 50 × 1012

20 GeV 125 × 1012 50 × 1012 25 × 1012

]Hz[feN]eV[E)w(Prep

arc

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Process mesons through Cooling

Analysis II Post CoolingCount mesons withinacceptance of 30π mm

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Post-cooling 30π Acceptance

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Summary

• For Negatives the peak occurs for

6 Gev < Proton KE < 11 GeV

• For Positives the peak occurs for

9 Gev < Proton KE < 19 GeV

• Consensus: 10 GeV is a good place to start

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Target/Beam Baseline used for comparison

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1 MW Proton Driver - Temperature Issues

Power and Heat removal capacity from target go hand-in-hand

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1 MW/50 Hz PD – target peak stresses3ns – 30ns – 300ns – 600ns

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SUMMARY of Performance

1 MW/50 Hz

12.0 e+12 ppp

YES

4 MW/50 Hz

48.0 e+12 ppp

NO

1 MW/200 Hz

3.0 e+12 ppp

YES

4 MW/200 Hz

12.0 e+12 ppp

MAYBE

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Design Parameter Phase Space

1. 8.0 GeV < Energy < 20.0 GeV

2. Rep Rate ~ 50(25) Hz

3. Intensity 50*10**(12) ppp, at 10(20) GeV

( very difficulty with solid target )

4. Bunch Length < 3 ns, for longitudinal

acceptance

5. Cost ???

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Examples of Future Improvements

1. Power Upgrade of J-PARC

2. Bunch Length of BNL

3. New Design of RAL

4. FFAG

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Short Bunch Length at BNL

• Longitudinal space charge force

• Experience for MECO

• Bunch length at transition energy

• Scale to new intensity and harmonic no.

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2 MW AGS Proton Driver

AGS proton driver layout for alternate injector linac design.

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Typical variation of , R, and E as the beam energy increases.

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Longitudinal Space Charge

sc parameter,

scaling relation,

(E. Courant, 1968)

3g

coseV

hmc2

R

r

2

N330

0

s2

2p

0

4/3

i

i

4/5

0 V

h

R

Nconst

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Longitudinal phase space of the proton beam before, at, and after crossing the transition energy in the AGS obtained with the computer code TIBETAN.

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Expected fractional beam loss upon transition crossing as a function of the initial (95%) longitudinal beam area obtained with the computer code TIBETAN.

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One Method of generating Short Bunch

• Short bunch can be generated by compressing RF system

• It can also be generated by bunch rotation

in the ring, or in the external beam line

• We try to do it by getting to transition

energy at extraction( lower voltage )

( C. Prior showed RAL methods at ISS )

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AGS as a Proton Driver

Present Upgrade VLBL NnFact Average Beam Power 0.14 2.0 4.0 Beam Energy (GeV) 24 28 10 Number of Protons per Fill 7.0 × 1013 9.0 × 1013 25.0 × 1013 Number of Bunches per Fill 12 23 5 Protons per Bunch 5.8 × 1012 3.91 × 1012 5.0 × 1013 Repetition Rate (Hz) 0.5 5.0 10.0 Linac Energy (MeV) 200 1500 1500 Linac rms Emitt (p mm mr, nor) 2.0 1.0 1.0 Pulse Length (ms) 0.5 0.72 0.72

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Summary and Conclusions

• We have presented the parameter constraint

for the Proton Driver

• A preferred parameter phase space has been

identified.

• Examples of new design and improvements on existing PD have been shown.