The Beta-beam cern.ch/beta-beam

1. The Beta-beamhttp://cern.ch/beta-beam Mats Lindroos on behalf of The beta-beam study group

2. Collaborators • The beta-beam study group: • CEA, France: Jacques Bouchez, Saclay, Paris Olivier Napoly, Saclay, Paris Jacques Payet, Saclay, Paris • CERN, Switzerland: Michael Benedikt, AB Peter Butler, EP Roland Garoby, AB Steven Hancock, AB Ulli Koester, EP Mats Lindroos, AB Matteo Magistris, TIS Thomas Nilsson, EP Fredrik Wenander, AB • Geneva University, Switzerland: Alain Blondel Simone Gilardoni • GSI, Germany: Oliver Boine-Frankenheim B. Franzke R. Hollinger Markus Steck Peter Spiller Helmuth Weick • IFIC, Valencia: Jordi Burguet, Juan-Jose Gomez-Cadenas, Pilar Hernandez, Jose Bernabeu • IN2P3, France: Bernard Laune, Orsay, Paris Alex Mueller, Orsay, Paris Pascal Sortais, Grenoble Antonio Villari, GANIL, CAEN Cristina Volpe, Orsay, Paris • INFN, Italy: Alberto Facco, Legnaro Mauro Mezzetto, Padua Vittorio Palladino, Napoli Andrea Pisent, Legnaro Piero Zucchelli, Sezione di Ferrara • Louvain-la-neuve, Belgium: Thierry Delbar Guido Ryckewaert • UK: Marielle Chartier, Liverpool university Chris Prior, RAL and Oxford university • Uppsala university, The Svedberg laboratory, Sweden: Dag Reistad • Associate: Rick Baartman, TRIUMF, Vancouver, Canada Andreas Jansson, Fermi lab, USA, Mike Zisman, LBL, USA

3. The beta-beam • Idea by Piero Zucchelli • A novel concept for a neutrino factory: the beta-beam, Phys. Let. B, 532 (2002) 166-172 • The CERN base line scenario • Avoid anything that requires a “technology jump” which would cost time and money (and be risky) • Make use of a maximum of the existing infrastructure • If possible find an “existing” detector site

4. Nuclear Physics CERN: b-beam baseline scenario SPL Decay ring Brho = 1500 Tm B = 5 T Lss = 2500 m SPS Decay Ring ISOL target & Ion source ECR Cyclotrons, linac or FFAG Rapid cycling synchrotron PS

5. Target values for the decay ring 6Helium2+ • In Decay ring: 1.0x1014 ions • Energy: 139 GeV/u • Rel. gamma: 150 • Rigidity: 1500 Tm 18Neon10+ (single target) • In decay ring: 4.5x1012 ions • Energy: 55 GeV/u • Rel. gamma: 60 • Rigidity: 335 Tm • The neutrino beam at the experiment will have the “time stamp” of the circulating beam in the decay ring. • The beam has to be concentrated to as few and as short bunches as possible to aim for a duty factor of 10-4

6. SPL, ISOL and ECR Objective: • Production, ionization and pre-bunching of ions Challenges: • Production of ions with realistic driver beam current • Target deterioration • Accumulation, ionization and bunching of high currents at very low energies SPL ISOL Target + ECR Linac, cyclotron or FFAG Rapid cycling synchrotron PS SPS Decay ring

7. + spallation F r 2 0 1 1 GeV p fragmentation + + U 2 3 8 L i X 1 1 fission n + + p C s 1 4 3 Y ISOL production

8. 6He production by 9Be(n,a) Converter technology: (J. Nolen, NPA 701 (2002) 312c) Courtesy of Will Talbert, Mahlon Wilson (Los Alamaos) and Dave Ross (TRIUMF) Layout very similar to planned EURISOL converter target aiming for 1015 fissions per s.

9. Mercury jet converter H.Ravn, U.Koester, J.Lettry, S.Gardoni, A.Fabich

10. Production of b+ emitters • Spallation of close-by target nuclides: 18,19Ne from MgO and 34,35Ar in CaO • Production rate for 18Ne is 1x1012 s-1 (with 2.2 GeV 100 mA proton beam, cross-sections of some mb and a 1 m long oxide target of 10% theoretical density) • 19Ne can be produced with one order of magnitude higher intensity but the half life is 17 seconds!

11. 60-90 GHz « ECR Duoplasmatron » for pre-bunching of gaseous RIB 2.0 – 3.0 T pulsed coils or SC coils Very high density magnetized plasma ne ~ 1014 cm-3 Very small plasma chamber F ~ 20 mm / L ~ 5 cm Target Arbitrary distance if gas Rapid pulsed valve • 1-3 mm 100 KV extraction 60-90 GHz / 10-100 KW 10 –200 µs /  = 6-3 mm optical axial coupling UHF window or « glass » chamber (?) 20 – 100 µs 20 – 200 mA 1012 to 1013 ions per bunch with high efficiency Moriond meeting: Pascal Sortais et al. LPSC-Grenoble optical radial coupling (if gas only)

12. Low-energy stage Objective: • Fast acceleration of ions and injection • Acceleration of 16 batches to 100 MeV/u SPL ISOL Target + ECR Linac, cyclotron or FFAG Rapid cycling synchrotron PS SPS Decay ring

13. Rapid Cycling Synchrotron Objective: • Accumulation, bunching (h=1), acceleration and injection into PS Challenges: • High radioactive activation of ring • Efficiency and maximum acceptable time for injection process • Charge exchange injection • Multiturn injection • Electron cooling or transverse feedback system to counteract beam blow-up? SPL ISOL Target + ECR Linac, cyclotron or FFAG Rapid cycling synchrotron PS SPS Decay ring

14. PS • Accumulation of 16 bunches at 300 MeV/u • Acceleration to g=9.2, merging to 8 bunches and injection into the SPS • Question marks: • High radioactive activation of ring • Space charge bottleneck at SPS injection will require a transverse emittance blow-up SPL ISOL Target + ECR Linac, cyclotron or FFAG Fast cycling synchrotron PS SPS Decay ring

15. Overview: Accumulation • Sequential filling of 16 buckets in the PS from the storage ring

16. SPS Objective: • Acceleration of 8 bunches of 6He(2+) to g=150 • Acceleration to near transition with a new 40 MHz RF system • Transfer of particles to the existing 200 MHz RF system • Acceleration to top energy with the 200 MHz RF system • Ejection in batches of four to the decay ring Challenges: • Transverse acceptance SPL ISOL Target + ECR Linac, cyclotron or FFAG Fast cycling synchrotron PS SPS Decay ring

17. Decay ring Objective: • Injection of 4 off-momentum bunches on a matched dispersion trajectory • Rotation with a quarter turn in longitudinal phase space • Asymmetric bunch merging of fresh bunches with particles already in the ring SPL ISOL Target + ECR Linac, cyclotron or FFAG Fast cycling synchrotron PS SPS Decay ring

18. Injection into the decay ring • Bunch merging requires fresh bunch to be injected at ~10 ns from stack! • Conventional injection with fast elements is excluded. • Off-momentum injection on a matched dispersion trajectory. • Rotate the fresh bunch in longitudinal phase space by ¼ turn into starting configuration for bunch merging. • Relaxed time requirements on injection elements: fast bump brings the orbit close to injection septum, after injection the bump has to collapse within 1 turn in the decay ring (~20 ms). • Maximum flexibility for adjusting the relative distance bunch to stack on ns time scale.

19. Horizontal aperture layout • Assumed machine and beam parameters: • Dispersion: Dhor = 10 m • Beta-function: bhor = 20 √m • Moment. spread stack: Dp/p = ±1.0x10-3 (full) • Moment. spread bunch: dp/p = ± 2.0x10-4 (full) • Emit. (stack, bunch): egeom = 0.6 pmm Beam: ± 2 mm momentum ± 4 mm emittance Required bump: 22 mm Required separation: 30 mm, corresponds to 3x10-3 off-momentum. Septum & alignment 10 mm Stack: ± 10mm momentum ± 4 mm emittance 22 mm Central orbit undisplaced M. Benedikt

20. Full scale simulation with SPS as model • Simulation conditions: • Single bunch after injection and ¼ turn rotation. • Stacking again and again until steady state is reached. • Each repetition, a part of the stack (corresponding to b-decay) is removed. • Results: • Steady state intensity was ~85 % of theoretical value (for 100% effective merging). • Final stack intensity is ~10 times the bunch intensity (~15 effective mergings). • Moderate voltage of 10 MV is sufficient for 40 and 80 MHz systems for an incoming bunch of < 1 eVs.

21. SPS SPS SPS SPS SPS SPS SPS SPS Stacking in the Decay ring • Ejection to matched dispersion trajectory • Asymmetric bunch merging SPS

22. Asymmetric bunch merging

23. Asymmetric bunch merging (S. Hancock, M. Benedikt and J,-L.Vallet, A proof of principle of asymmteric bunch pair merging, AB-note-2003-080 MD)

24. Decay losses • Losses during acceleration are being studied: • Full FLUKA simulations in progress for all stages (M. Magistris and M. Silari, Parameters of radiological interest for a beta-beam decay ring, TIS-2003-017-RP-TN) • Preliminary results: • Can be managed in low energy part • PS will be heavily activated • New fast cycling PS? • SPS OK! • Full FLUKA simulations of decay ring losses: • Tritium and Sodium production surrounding rock well below national limits • Reasonable requirements of concreting of tunnel walls to enable decommissioning of the tunnel and fixation of Tritium and Sodium

25. Decay losses • Acceleration losses: A. Jansson

26. How bad is 9 W/m? • For comparison, a 50 GeV muon storage ring proposed for FNAL would dissipate 48 W/m in the 6T superconducting magnets. Using a tungsten liner to • reduce peak heat load for magnet to 9 W/m. • reduce peak power density in superconductor (to below 1mW/g) • Reduce activation to acceptable levels • Heat load may be OK for superconductor.

27. SC magnets • Dipoles can be built with no coils in the path of the decaying particles to minimize peak power density in superconductor • The losses have been simulated and one possible dipole design has been proposed S. Russenschuck, CERN

28. Tunnels and Magnets • Civil engineering costs: Estimate of 400 MCHF for 1.3% incline (13.9 mrad) • Ringlenth: 6850 m, Radius=300 m, Straight sections=2500 m • Magnet cost: First estimate at 100 MCHF FLUKA simulated losses in surrounding rock (no public health implications)

29. Intensities Only b-decay losses accounted for, add efficiency losses (50%)

30. CERN Geneve • SPL @ CERN • 2.2GeV, 50Hz, 2.3x1014p/pulse • 4MW Now under R&D phase 130km 40kt 400kt Italy CERN to FREJUS

31. The Super Beam

32. LOW-ENERGYBETA-BEAMS Beta-beam n n 6He C. Volpe, hep-ph/0303222 To appear in Journ. Phys. G. 30(2004)L1 boost THE PROPOSAL To exploit the beta-beam concept to produce intense and pure low-energy neutrino beams. PHYSICS POTENTIAL e ne C N Neutrino-nucleus interaction studies for particle, nuclear physics, astrophysics (nucleosynthesis). Neutrino properties, like n magnetic moment. A „BETA-BEAM“ FACILITY FOR LOW-ENERGY NEUTRINOS.

33. Prospects forthe neutrino magnetic moment PRESENT LIMIT : mn < 1.0 x 10-10mB. 6He 6Li+e+ne Qb=4. MeV n 5 X 10-11mB 6He e ne e ne ne-eevents with beta-beams (10 15n/s) with a 4p low threshold detector. 10-11mB mn=0 THE LIMIT CAN BE IMPROVED BY ONE ORDER of MAGNITUDE (a few x 10-11mB) . G.C. McLaughlin and C. Volpe, hep-ph/0303222, to appear in Phys. Lett. B.

34. Neutrino-nucleus Interaction Rates At a Low-energy Beta-beam Facility Neutrino Fluxes Events/year for g=14 ne+ Nucleus Small Ring Large Ring Small Ring : Lss = 150 m, Ltot = 450 m. Large Ring : Lss = 2.5 km, Ltot = 7.5 km ne+ D 1956 25779 ne+ 16O 82645 9453 ne+ 208Pb 103707 7922 INTERESTING INTERACTION RATES CAN BE OBTAINED. J. Serreau and C. Volpe, hep-ph/0403293, submitted to Phys. Rev. D.

35. Possible sites g Detectors Intensities 1012n/s GANIL 1 4p A. Villari (GANIL) 109n/s 1-10 4p and Close detector GSI H. Weick (GSI) 4p and Close detector CERN 1-100 1013n/s (EURISOL) Autin et al, J.Phys. (2003). CERN IS A UNIQUE SITE BOTH FOR THE n-INTENSITIES AND THE n-ENERGIES.

36. SPL ISOL Target + ECR Linac, cyclotron or FFAG Rapid cycling synchrotron PS SPS Decay ring R&D (improvements) • Production of RIB (intensity) • Simulations (GEANT, FLUKA) • Target design, only 200 kW primary proton beam in present design • Acceleration (cost) • FFAG versa linac/storage ring/RCS • High gamma option • Tracking studies (intensity) • Loss management • Superconducting dipoles (g of neutrinos) • Pulsed for new PS/SPS (GSI FAIR) • High field dipoles for decay ring to reduce arc length • Radiation hardness (Super FRS)

37. Comments & speculations:Ne and He in decay ring simultaneously • Possible gain in counting time and reduction of systematic errors • Cycle time for each ion type doubles! • Requiring g=(60)150 for He will at equal rigidity result in a g=(100)250 for Ne • Physics? • Detector simulation should give “best” compromise • Requiring equal revolution time will result in a DR of 97(16) mm (r=300 m) • Insertion in one straight section to compensate

38. 6He 8 s SPS cycling Accumulation (multiplication) factor 6He 16 s SPS cycling Time (s) Requires larger long. Acceptance! Comments & sepculations:Accumulation Ne + He in DECAY RING

39. 1 s in baseline Accumulation (PS or SPS) Production and bunching (ISOL and ECR) Number of ions constant from ECR source Comments & sepculations:Accumulation Ne + He before acceleration • Base line scenario assumes accumulation of 16 bunches for one second at 300 MeV/u (PS) for both He and Ne • Optimization assuming fixed ECR intensity (out): • Longer accumulation • SPS accumulation

40. PS Baseline Comments & speculations:Accumulation before acceleration SPS: Ne, one fill of 1 unit of ions every 1.2 s SPS: He, one fill of 1 unit of ions every 1.2 s Increase of intensity PS: Ne, one fill of 1 unit of ions every 1/16 s PS: He one fill of 1 unit of ions every 1/16 s Number of fills

41. Ramp time PS Reset time SPS Ramp time SPS Wasted time? Comments & speculations:Wasted time? Decay ring SPS PS Production 8 0 Time (s)

42. Comments & speculations:Higher Gamma? • Requires either a larger bending radius or a higher magnetic field for the decay ring, the baseline circumference is 6885 m and has a bending radius (r) of 300 m: • At g=500 (6He) , r=935 m at B=5 T • To keep the percentage of straight section the same as the baseline the ring would become 21.4 km long • Alternatively new dipoles: r=300 m at B=15.6 T • Or LHC type dipoles at B=10 T and r=468 m with a circumference of 7794 m • Requires an upgrade of SPS or ramping of the decay ring • SPS upgrade expensive and time consuming • Ramping of decay ring requires less frequent fills and higher total intensity

43. Comments & speculations:Duty factor (or empty buckets) • The baseline delivers a neutrino beam with an energy badly troubled by atmospheric background • Duty factor=4 10-4, 4 buckets out of 919 possible filled —› 10 ns total bunch length • At g=500 the duty factor can be increased to 10-2 (P. Hernandez), 92 buckets filled or 23 times the intensity theoretically, can that be realised?

44. Comments & speculations:Electron Capture, Monochromatic beams • Nuclei that only decay by electron capture generally have a long half-life (low Q value, <1022 keV) • Some possible candidates: 110Sn (4.1 h half life) and 164Yb (75.8 min half life) • Maybe possible if very high intensities can be collected in the decay ring and a high duty factor can be accepted (0.1) • High gamma with ramping of the decay ring? • For the baseline: With g=259, assuming 2.3 1016 ions in the decay ring and a duty factor of 0.1 there would be 4 109 neutrinos per second at 259x0.326 MeV=84.434 MeV, is that useful?

45. USERS Frejus Gran Sasso High Gamma Astro-Physics Nuclear Physics (g, intensity and duty factor) OTHER LABS TRIUMF FFAG Tracking Collimators US study Neutrino Factory DS Conceptual Design # with price ### M€ Design Study EURISOL Beta-beam Coordination Beta-beam parameter group Above 100 MeV/u Targets 60 GHz ECR Low energy beta-beam And many more…

46. Superbeam & Beta Beam cost estimates (NUFACT02)

47. Beta-beam n n 6He boost A EURISOL/beta-beam facility at CERN! • A boost for radioactive nuclear beams • A boost for neutrino physics “The chances of a neutrino actually hitting something as it travels through all this emptiness are roughly comparable to that of dropping a ball bearing from a cruising 747* and hitting, say an egg sandwich”, Douglas Adams, Mostly Harmless, Chapter 3 *) European A380, Prototype will fly in 2005 EURISOL Design Study, when will the beta-beam fly?