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Further Demands on n beam • Intense, Intense, Intense, …. – Very far detector, extremely small cross section, search small osci. probability – High proton beam power – High efficiency pion collection with Horns • Fast (Time structure) – Background in detector: Cosmic rays, atm n (~8/day @SK) – Discriminate by timing info. • Long term stable operation and maintenance 1 Fast extraction from accelerator • Single turn fast extraction （JAPRC Phase-1): – 3.3x1014 protons in 8 bunches in ~4ms (3.5sec period) • 15bunch operation also being discussed to recover beam power – 4ms/3.5s~10-6 BG reduction – 2.6MJ/pulse(3.5 sec period) 598ns 4.2ms ~10TW 58ns • 330kJ (50GeVx4E13p) Huge power in short time – Thermal shock problem everywhere (+cooling problem) • Time scale ~ sound velocity ~ ms each bunch cumulative – makes components design difficult – cf. [hadron facility]x106 (slow ext) , [3GeV facility]x102 (50GeV/3GeVx8/1bunch) 2 Challenge and Technologies First high enrgy MW fast-ext’ed beam ! cm 3.3E14 ppp w/ 5ms pulse Residual radiation When this beam hits an iron block, > 1000Sv/h cm 1100o (cf. melting point 1536o) Material heavier than iron would melt. Thermal shock stress ET 3GPa (max stress ~300 MPa) Material science, Mechanical engineering, Radiation safety system engineering and remote maintenance engineering 3 Neutrino beam line with MW protons •Shock wave •Graphite for target and dump core •Heat generation •Various sources including dE/dX 4kW(water), MW (air) •magnets and their power water cooling •Target Horn TS-DV-BD wall /BD core water cooling •Radioactive water and air •radioactive water 13GBq / 3weeks (must be diluted <30Bq/cc to dispose) many tanks, ion exchange filter, backup loop radioactive He 7GBq / 3 weeks (must be diluted <5mBq/cc to dispose) Production cross section of Tritium in He is 1/10 of air 4 He vessel ( need O2 <10ppm) 4 Temparature rise of Horn at 750KW 5 Present Technology limit • Temparature rise and thermal shock limit us about 2MW proton beam – Alminum horn – Graphite target beam power – Ti vacuum window number of protons • Substantial R/D and experiences needed to go substantially beyond this limit 6 Far(?) future 7 BNL-FNAL1 joint study 8 9 10 11 12 13 14 15 New types of accelerators 16 Technical Challenges of the EURISOL Beta-beam Steven Hancock AB Department, CERN on behalf of the Beta-beam Study Group http://cern.ch/beta-beam/ 17 Production Mechanism 18 • Beta-beam proposal by Piero Zucchelli. – A novel concept for a neutrino factory: the beta-beam, Phys. Let. B, 532 (2002) 166-172. • AIM: production of a pure beam of electron neutrinos (or antineutrinos) through the beta-decay of radioactive ions circulating in a high-energy storage ring. • Baseline scenario. – Based on known technology and machines. – Makes maximum use of the existing CERN infrastructure. – ~100 6He or 18Ne ions. – Annual rate of 2.91018 antineutrinos or 1.11018 neutrinos. 19 EURISOL Beta-beam Ion production Acceleration Neutrino source Experiment Proton Driver SPL Acceleration to final energy 6 2 18 10 Neutrino Source Beam preparation Pulsed ECR PS Acceleration to medium energy RCS He 36 Li e n AverageE cms 1.937 MeV PS & SPS Ion production ISOL target & Ion source Ion acceleration Linac n ,n SPS Ne189 F e n AverageE cms 1.86 MeV Decay Ring n ,n 20 RCS PS SPS Decay ring • Cooling is not an option. Electron cooling is excluded because of the high electron beam energy and, in any case, the cooling time is far too long. Stochastic cooling is excluded by the high bunch intensities. Beam loss • Machine activation due to beta-decay losses alone is not a show-stopper but still deserves careful consideration. Will be comparable with NOMAD-CNGS operation. Radiation on Super conducting ring Space charge problem and RF system 21 Conclusions • Beta-beam baseline scenario is well established. • Main technical challenges rest firmly with the decay ring, with the focus of attention on rf and collimation systems. radioactivity and scraping may give background nm • Accelerator design is made “top-down” so that machine performance is compatible with target figures from physics, while the production side is studied within EURISOL. – Stop press: preliminary measurements at Louvain-LaNeuve indicate that direct production of 18Ne by 3He on a 16O target could reach the required rate. • Beta-beam task well integrated in the EURISOL DS: excellent example of synergy between nuclear and high-energy physics.22 Neutrino Factory The goal of a neutrino factory is to provide a source of neutrino and anti-neutrino beams that are intense, energetic, and well understood. The specific idea is to construct a muon storage ring with long straight sections and use n’s from m decays.. There are many technical challenges. Some of the most important ones are: 1. Design of target for high power beams (few Mw) 2. Cooling of muons (initial PT ~ 300 MeV) 3. Rapid acceleration of muons (from ~100 MeV to tens of GeV) 4. Construction of steep beam lines (tens of degrees) 23 Golden Signature The transition ne -> nm is detected by observation of the “wrong sign” muon. Should be relatively background free. Need a detector with magnetic field. 24 25 26 27 28 29 30 31 32 33 34 Mass hierarchy and CPV 35 2010-2014 • Neutrino experiments – Reactor experiment on q13 – ne appearance – To the level of 1/10 of the present upper limit • Yes, then full investigation of CPV – with a giant detector and proton decay – mass hierarchy with new type of accelerator • No, – continue searching small parameter • • LHC results on Higgs, SUSY and ? Linear collider 36