1. Superbeams with SPL at CERN
SPL = Superconducting Proton Linac
A concept for modern high intensity proton beams at CERN based
on a high-energy Superconducting Linear Accelerator
1. Introduction
2. SPL principle and characteristics
3. On-going R&D
4. Staging
5. Summary and Conclusion
M. Vretenar for the SPL W.G. 1

2. From Neutrino Factory to Neutrino Superbeam
from SPL
nm from p decay,
energy
250 MeV
Optimal baseline
for far detector
130 km
CERN baseline
scenario for a
neutrino Factory
m from p decay
collected, cooled,
accelerated and
circulated in a
decay ring
Optimal baseline km
M. Vretenar for the SPL W.G. 2

3. 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…
M. Vretenar for the SPL W.G. 3

4. The Team Work going on since 1999… Neutrino Factory Working Group(
Superconducting Proton Linac Working Group (
Proton Driver Rings Working Group (
Target Study Team
M. Vretenar for the SPL W.G. 4

5. The SPL Working Group REFERENCE :
Conceptual Design of the SPL, a High Power Superconducting Proton
Linac at CERN
Ed. M. Vretenar, CERN
M. Vretenar for the SPL W.G. 5

6. The Superconducting Proton Linac: Main Principles
 In line with modern High Power Proton Accelerator projects
(SNS, JKJ,…)
 Re-use of the LEP RF equipment (SC cavities, cryostats, klystrons,
waveguides, circulators, etc.)
The LEP klystron
Storage of the LEP
cavities in the ISR tunnel
M. Vretenar for the SPL W.G. 6

7. The Superconducting Proton Linac: Design (1)
H- source, 25 mA
14% duty cycle
Cell Coupled Drift Tube Linac
Fast chopper
(2 ns transition time)
2.2 GeV energy:
direct injection into PS
threshold for p production
new SC cavities: b=0.52,0.7,0.8
5-cell b 0.8 cavities replacing 4-cell b 1 cavities in the LEP cryostat
RF system:
freq.: 352 MHz
amplifiers: tetrodes and LEP klystrons
M. Vretenar for the SPL W.G. 7

8. The SPL: Design (2) 54 cryostats, 32 directly from LEP,
the others reconstructed
51 LEP-type klystrons (44 used in LEP)
M. Vretenar for the SPL W.G. 8

9. SPL Beam Specifications
M. Vretenar for the SPL W.G. 9

10. The Accumulator – Compressor Scheme
Two Rings in the ISR Tunnel
Accumulator:
3.3 ms burst of
144 bunches at
44 MHz
Compressor:
Bunch length
reduced to 3 ns
M. Vretenar for the SPL W.G. 10

11. Characteristics of the beam sent to the target
M. Vretenar for the SPL W.G. 11

12. Layout on the CERN site
M. Vretenar for the SPL W.G. 12

13. Cross section
M. Vretenar for the SPL W.G. 13

14. SPL R&D Topics
Minimise beam loss to avoid activation of the machine (loss<1 W/m)
Beam Dynamics studies, optimise layout and beam optics
Chopper structure to create a time distribution in the beam that
minimises losses in the accumulator
Travelling wave deflector with rise time <2 ns
3. Efficient room-temperature section (W<120 MeV)
CCDTL concept
4. Development of SC cavities for b<1
Sputtering techniques
5. Pulsing of LEP klystrons
Built for CW, operated at 50 Hz, 14% duty
6. Pulsing of SC cavities and effects of vibrations on beam quality
Low power (feedback), high power (phase and amplitude
modulators) and active (piezos) compensation techniques
M. Vretenar for the SPL W.G. 14

15. Collaboration on RFQs with CEA-IN2P3 (IPHI) and INFN Legnaro
SPL R&D – Low Energy
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)
M. Vretenar for the SPL W.G. 15

16. SPL R&D – Low Beta SC 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)
M. Vretenar for the SPL W.G. 16

17. SPL R&D – Pulsing of LEP Klystrons
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
M. Vretenar for the SPL W.G. 17

18. SPL R&D – RF power distribution & field regulation in the SC cavities
Effect
on field
regulation
Effect on
the beam
Þ unsolved problem ! Needs work
(high power ph.&ampl. modulators, piezos,…)
Þ similar difficulties are likely in the muon accelerators!
M. Vretenar for the SPL W.G. 18

19. Staging Test of a 3 MeV H- injector
In collaboration with CEA-IN2P3 exploiting the IPHI set-up
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)
Full SPL
M. Vretenar for the SPL W.G. 19

20. The SPL Front-end (120 MeV) in the PS South Hall (intermediate proton intensity increase)
Beam dump
To the PSB
H- source
LEIR
Þ Increased brightness for LHC, ´ 1.8 the flux to CNGS & ISOLDE, … (with upgrades to the PSB, PS & SPS)
very cost-effective facility: hall and infrastructure are available in the PS
all the RF is recuperated from LEP
shielding is done with LEP dipoles!
M. Vretenar for the SPL W.G. 20

21. The 120 MeV Linac 75 m (100 m available in PS South Hall)
M. Vretenar for the SPL W.G. 21

22. Summary and Conclusion
The SPL design is improving, R&D is going on
Work in progress on most items, based on collaborations
A staged approach is proposed
Feedback (and support !) is needed from potential users
M. Vretenar for the SPL W.G. 22