1. The SPL-based Proton Driver at CERN
OUTLINE
1. Introduction
2. SPL characteristics
3. On-going work
4. Staging
5. Summary and Conclusion
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2. SPL Working Group REFERENCE
Conceptual Design of the SPL, a High Power Superconducting Proton Linac at CERN
Ed. M. Vretenar, CERN
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3. 1. Introduction CERN baseline scenario for a Neutrino Factory
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4. Other applications of the proton driver
Approved physics experiments
CERN Neutrinos to Gran Sasso (CNGS): increased flux (~ ´ 2)
Anti-proton Decelerator: increased flux
Neutrons Time Of Flight (TOF) experiments: increased flux
ISOLDE: increased flux, higher duty factor, multiple energies...
LHC: faster filling time, increased operational margin...
Future potential users
“Conventional” neutrino beam from the SPL “super-beam”
Second generation ISOLDE facility (“EURISOL” -like)
LHC performance upgrade beyond ultimate…
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5. 2. SPL characteristics H- source, 25 mA 14% duty cycle CCDTL
new SC cavities: b=0.52,0.7,0.8
Fast chopper
(2 ns transition time)
RF system:
freq.: 352 MHz
ampli.: tetrodes and LEP klystrons
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6. Improvements w.r.t. the reference design
Improved transitions between sections  better beam stability
Doubled period length above 1.1 GeV  save 25 doublets, 8m, 3 MCHF
Improved error studies  100% beam radius < 20 mm, even for large error case (30 %)  quad. radius reduced from 100 mm to 60 mm, (17rms)  save MCHF
Reduced longitudinal emittance: 0.6  0.3 ºMeV  improved design of the transfer line (drift length 230  175 m, bunch length 180  130 ps)
Use of beta=0.8 cavities up to the highest energy  shorter tunnel (- 100 m), less cavities per klystron, better control of mechanical resonances
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7. SPL beam specifications
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8. Accumulator-Compressor scheme
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9. Characteristics of the beam sent to the target
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10. Layout on the CERN site (top view)
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11. Cross section
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12. 3. On-going work
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13. Collaboration on RFQs with CEA-IN2P3 (IPHI) and INFN Legnaro
Progress highlights
Chopper structure
3 D view of a coupled cavity
drift tube module
(CCDTL)
Scaled model
(1 GHz) in test
Full performance prototype tested
Driver amplifier in development
Collaboration on RFQs with CEA-IN2P3 (IPHI) and INFN Legnaro
352 MHz test place prepared (planned tests of CEA-built DTL structures in 2002)
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14. Chopper
 Travelling wave electrostatic deflector, meander line to match beam and wave velocity
 Used to create gaps in the linac bunch distribution between accumulator buckets
 Needs very short rise/fall times (2 ns !) to avoid partially deflected bunches
 Development of pulser
198+2mm (33 cells)
50 mm
accumulator bucket
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15. Study of RT structures for the SPL front-endbl
Alvarez Drift Tube Linac
unsurpassable <20 MeV
good but expensive for MeV bl
Cell Coupled Drift Tube Linac
attractive solution for MeV
(a cold model is being designed)
bl/2
Coupled-Cell Cavity (LEP1)
better efficiency >110 MeV
quadrupole
quadrupole
The final choice will depend on preferred apertures, RT final energy, etc.
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16. Superconducting cavities
 CERN technique of Nb/Cu sputtering
for b=0.7, b=0.8 cavities (352 MHz):
excellent thermal and mechanical stability
(very important for pulsed systems)
lower material cost, large apertures, released
tolerances, 4.5 K operation with Q = 109
The b=0.7 4-cell prototype
 Bulk Nb or mixed technique for b=0.52 (one 100 kW tetrode per cavity)
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17. RF and Superconducting cavities Parameters
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18. Pulsed operation of a LEP klystron set-up
RF output power
(800 kW max.)
Mod anode driver
5 ms/div
1 ms/div
14/05/ H. Frischholz
Þ LEP power supplies and klystrons are capable to operate in pulsed mode after minor modifications
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19. RF power distribution & field regulation in the superconducting cavities
Effect
on field
regulation
Effect on
the beam
Þ unsolved problem ! Needs work
Þ similar difficulties are likely in the muon accelerators...
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20. 4. Staging Test of the 3 MeV H- injector
Means: strengthen collaboration with the CEA-IN2P3 and jointly exploit the IPHI set-up
Contribute to the chopper and bunchers
120 MeV H- linac in the PS South Hall
Goal: increase beam intensity for CNGS and improve characteristics of all proton beams (LHC, ISOLDE…)
Under study: detailed design report with cost estimate in 2003
Needs new resources (collaborations, manpower, money)
SPL
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21. Proton Intensity increase:
location of the SPL front-end in the PS South Hall PS
To the PSB
Beam dump
H- source
LEIR
Þ Increased brightness for LHC, ´ 1.8 the flux to CNGS & ISOLDE, … (with upgrades to the PSB, PS & SPS)
Þ “cheap” installation, giving benefits from SPL related hardware before the full machine is operational & shortening the final setting-up
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22. 5. Summary and Conclusion
The SPL design is improving
Work is started on most items, based on collaborations
A staged approach is proposed
Feedback (and support !) is needed from potential users
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