Accelerator based Neutrino beams Mats Lindroos Moriond meeting
Outline • Existing facilities • CNGS • The super beam • The neutrino factory • The beta beam • Conclusions Moriond meeting
Acknowledgments • CNGS • Konrad Elsener, CERN • The Superbeam • Helmut Haseroth, Konrad Elsener, Tsuyoshi Nakaya • The Neutrino Factory • The nufact study group • The beta beam • The beta beam working group Moriond meeting
Beta beam CNGS In Dec. 1999, CERN council approved the CNGS project: build an intense nm beam at CERN-SPS search for ntappearance at Gran Sasso laboratory (730 km from CERN) “long base-line”nm--ntoscillation experiment note: K2K (Japan) running; NuMI/MINOS (US) under construction Moriond meeting
CERN to CNGS Moriond meeting
The Gran Sasso laboratory Moriond meeting
p + C (interactions) p+, K+ (decay in flight) m+ + nm The CERN part Polarity change foreseen! …but the intensity will go down and the contamination goes up Moriond meeting
p / K profile at entrance to decay tunnel Moriond meeting
CNGS muon beam profiles first muon pit second muon pit Moriond meeting
Radial distribution of thenm- beam at Gran Sasso note: 1 mm -> 1 km Moriond meeting
Number of particles expected per year: For 1 year of CNGS operation, we expect: (4.8x1013 protons in SPS, 55% efficiency -- 1997) protons on target4.5 x 1019 pions / kaons at entrance to decay tunnel 5.8 x 1019 muons in first / second muon pit 3.6 x 1018 / 1.1 x 1017 nmin 100 m2 at Gran Sasso 3.5 x 1012 Upgrade with a factor of 1.5 feasible but requires investment in CERN injector complex Moriond meeting
Unwanted neutrino species Relative to the main nm component: ne / nm= 0.8 % anti-nm / nm= 2.1 % anti-ne / nm = 0.07 % Moriond meeting
CERN underground Moriond meeting
CNGS target station Moriond meeting
CNGS target -> 10 cm long graphite rods, Ø=5mm and/or 4mm proton beam Note: - target rods interspaced to “let the pions out” - target is helium cooled (remove heat deposited by the particles) Moriond meeting
CNGS focusing devices “Magnetic Horn” (S. v.der Meer, CERN) length: 6.5 m diameter: 70 cm weight: 1500 kg Pulsed devices: 150kA / 180 kA, 1 ms water-cooled: distributed nozzles Moriond meeting
inner conductor Principle of focusing with a Magnetic Horn Magnetic volume given by “one turn” at high current: specially shaped inner conductor - end plates cylindrical outer conductor Moriond meeting
CNGS Horn test Moriond meeting
CNGS decay tube + hadron stop - dimensions of decay tube: 2.45 m diameter steel tubes, 6 m long pieces, 1 km total welded together in-situ vacuum: ~1 mbar tube embedded in concrete - hadron stop: 3.2 m graphite 15 m iron blocks upstream end: water cooled Moriond meeting
Protons Protons Protons Protons Protons What is the Super Neutrino Beam? • No Clear definition, but it is a very intense neutrino beam produced by a high power (>1MW ) accelerator. • A conventional method. • Still technically challenging due to the high power and the high radiation environment, but not impossible. • Multiple targets Moriond meeting
Target stack? Moriond meeting
Neutrino factoryCERN • Superconducting proton linac as driver • Proton bunch train not longer than decay ring • Bunch to bucket philosophy • Longitudinal cooling using bunch rotation • Transversal cooling using ionization cooling • Recirculating linear accelerators • Decay ring Moriond meeting
Neutrino factoryJapan 3 GeV and 50 GeV rings are part of JAERI-KEK Joint Project Moriond meeting
American Study II Moriond meeting
Current of 300 kA p To decay channel Protons B = 0 Hg target B1/R Gilardoni Target and pion captureliquid jet+Horn Moriond meeting
Pion Capture: Solenoid 20T 1.25T Moriond meeting
Liquid jet Moriond meeting
Event #1125th April 2001 K. Mc Donald, H. Kirk, A. Fabich, J.Lettry Protons Picture timing [ms] 0.00 0.75 4.50 13.00 P-bunch: 2.71012 ppb 100 ns to = ~ 0.45 ms Hg- jet : diameter 1.2 cm jet-velocity 2.5 m/s perp. velocity ~ 5 m/s Jet test at BNL Moriond meeting
Targetry Many difficulties: enormous power density lifetime problems pion capture Stationary target: Replace target between bunches: Liquid mercury jet or rotating solid target Proposed rotating tantalum target ring Sievers Densham Moriond meeting
Ionization cooling IN Liquid H2:dE/dx sol H2 rf Beam sol RF restoresonly P//: E constant Moriond meeting OUT
Cooling experiment Moriond meeting
Cooling - rings Main advantages: shorter longitudinal cooling Balbekov Palmer Moriond meeting
System CERN FNAL (Study I) BNL (Study II) Japanese System rep rate 50 Hz 2.5/5 Hz Proton driver type Linac (SPL) Synchrotron Synchrotron (AGS) Synchrotron p driver energy 2.2 GeV 16 GeV 24 GeV 50 GeV Target material Hg C C Collection Horn Solenoid Solenoid Beam structure Bunch-to-bucket Re-bunching Re-bunching Phase rotation rf 2 induction linacs 3 induction linacs FFAG Cooling channel 88 MHz 200 MHz 200 MHz No cooling Acceleration 2 RLAs (20/50 GeV) 2 RLAs (20/50 GeV) 1 RLA (20 GeV) 4 FFAGs (1/3/ 10/20-50 GeV) Comparison of General Layout Moriond meeting
Decay ring Brho = 1500 Tm B = 5 T Lss = 2500 m SPL Decay Ring ISOL target & Ion source Cyclotrons Storage ring and fast cycling synchrotron b-beam baseline scenario SPS PS Moriond meeting
Objectives for CERN study • Present a coherent and “realistic” scenario for acceleration of radioactive ions: • Use known technology (or reasonable extrapolations of known technology) • Use innovations to increase the performance • Re-use a maximum of the existing CERN accelerators • Use the production limit for ions of interest as starting point Moriond meeting
SPL ISOL Target + ECR Cyclotrons or FFAG Storage ring Fast cycling synchrotron PS SPS Decay ring Low-energy stage • Fast acceleration of ions and injection into storage ring • Preference for cyclotrons • Known price and technology • Acceleration of 16 batches of 1.02x1012 or 2 1013 ions/s 6He(1+) from 20 MeV/u to 300 MeV/u • Comment: • Bunching in cyclotron? Moriond meeting
Storage ring SPL ISOL Target + ECR Cyclotrons or FFAG Storage ring Fast cycling synchrotron PS SPS Decay ring • Charge exchange injection into storage ring • Technology developed and in use at the Celsius ring in Uppsala • Accumulation, bunching (h=1) and injection into PS of 1.02x10126He(2+) ions • Question marks: • High radioactive activation of ring • Efficiency and maximum acceptable time for charge exchange injection • Electron cooling or transverse feedback system to counteract beam blow-up Moriond meeting
Overview: Accumulation • Sequential filling of 16 buckets in the PS from the storage ring Moriond meeting
PS SPL ISOL Target + ECR Cyclotrons or FFAG Storage ring Fast cycling synchrotron PS SPS Decay ring • Accumulation of 16 bunches at 300 MeV/u each consisting of 2.5x10126He(2+) ions • Acceleration to g=9.2, merging to 8 bunches and injection into the SPS • Question marks: • Very high radioactive activation of ring • Space charge bottleneck at SPS injection will require a transverse emittance blow-up Moriond meeting
SPS • 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 SPL ISOL Target + ECR Cyclotrons or FFAG Storage ring Fast cycling synchrotron PS SPS Decay ring Moriond meeting
Decay ring • Injection and accumulation will be described in talk on Thursday • Major challenge to construct radiation hard and high field magnets SPL ISOL Target + ECR Cyclotrons or FFAG Storage ring Fast cycling synchrotron PS SPS Decay ring Moriond meeting
Intensities: 18Ne • From ECR source: 0.8x1011 ions per second • Storage ring: 4.1 x1010 ions per bunch • Fast cycling synch: 4.1 x1010 ion per bunch • PS after acceleration: 5.2 x1011 ions per batch • SPS after acceleration: 4.9 x1011 ions per batch • Decay ring: 9.1x1012 ions in four 10 ns long bunch • Only b-decay losses accounted for, efficiency <50% Moriond meeting
Intensities: 6He • From ECR source: 2.0x1013 ions per second • Storage ring: 1.0 x1012 ions per bunch • Fast cycling synch: 1.0 x1012 ion per bunch • PS after acceleration: 1.0 x1013 ions per batch • SPS after acceleration: 0.9x1013 ions per batch • Decay ring: 2.0x1014 ions in four 10 ns long bunch • Only b-decay losses accounted for, efficiency <50% Moriond meeting
Result of CERN study • A baseline scenario for the beta-beam at CERN exists • While, possible solutions have been proposed for all identified bottlenecks we still have problems to overcome and… • …it is certainly possible to make major improvements! • Which could result in higher intensity in the decay ring! • First results are so encouraging that the beta-beam option should be fully explored • Investigate sites at other existing accelerator laboratories • Study a “Green field” scenario Moriond meeting
Higher energy in the decay ring? • LHC top rigidity (23270 Tm): • 6He has a g=2488.08 • 18Ne has a g= 4158.19 • With a “futuristic” radiation hard superconducting dipole design for the decay ring with a field of 5 Tesla the radius of the arcs will be r=4654 m! • Bigger than LHC arcs! • Lower intensities as LHC only can handle transversally small bunches Moriond meeting
Neutron beams? • As for a neutrino beam and neutron beam can be created if a beta-delayed neutron emitter is stored in the decay ring • High energy • Physics case? • Low energy • Medical use – neutron therapy • Waste transmutation at neutron resonances • Intensity? Moriond meeting
Comments • The super beam can be available soon (when the necessary high power drivers are completed) • The beta-beam is largely based on existing technology but requires costly civil engineering for the decay ring • Moderate extrapolations on target technology • Strong synergies with projects in nuclear physics • EURISOL • GSI upgrade • SPIRAL-2 • SPES in Legnaro • Ion programme in LHC and low energy ion (accelerator and) storage rings in Europe • The R&D for a full scale muon based neutrino factory is fascinating but very challenging • Target issues still requires major R&D • Ionization cooling has to be experimentally tested Moriond meeting
What I can see in the crystal ball As any Harry Potter reader knows that the art of crystal ball viewing is both very difficult and often prone to errors! • High power proton drivers become available • Next generation ISOL RNB facilities • Super beams • Low energy electron neutrino beams available • Physics case? • The beta-beam is taken to higher energies • Muon based neutrino factory starts delivering beam Moriond meeting
Conclusion • Beta-beam at CERN: • Low energy part will benefit nuclear physics • Acceleration to high energy is likely to benefit heavy ion programme • LHC beam brightness? • Find a way of benefiting ion programme in LHC with our decay ring and our luck might be made! • Having said that… • GSI is world leading on high energy ions • Should open new possibilities at GSI for ions • Having said that… • Italy is the only European country that seems willing to invest in high energy physics inclduing neutrinos and underground detectors • Low energy neutrino beams? • Having said that… • GANIL is one of the centers for accelerated radioactive ions • Low energy neutrino beams? • I hope I have set out a promising future for the research in to different aspects of the beta-beam! Moriond meeting
