Status of the betabeam study Mats Lindroos on
Status of the beta-beam study Mats Lindroos on behalf of the EURISOL beta-beam task UK HEP FORUM 2008 The beta-beam team 1
Outline of message I would like to give in this talk n Beta-beam concept n A beta-beam facility n Layout (e. g EURISOL DS) n Challenges n How can we improve the beta-beam n Before we build it: n n High gamma Beta-beams After we built it: n n n Intensity and flux Electron capture Beta-beams High-Q vlaue Beta-beams The beta-beam team 2
n Introduction to betabeams Beta-beam proposal by Piero Zucchelli n n 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 ( ~100) storage ring. Ions move almost at the speed of light n First study in 2002 n Make maximum use of the existing infrastructure. The beta-beam team 3
Beta-beam Basics Aim: production of (anti-)neutrino beams from the beta decay of radio-active ions circulating in a storage ring n n Beta-decay at rest n n n Similar concept to the neutrino factory, but parent particle is a beta-active isotope instead of a muon. n-spectrum well known from electron spectrum Reaction energy Q typically of a few Me. V Accelerated parent ion to relativistic gmax n n Boosted neutrino energy spectrum: En 2 g. Q Forward focusing of neutrinos: 1/g 6 He n Beta-beam boost n g=100 The beta-beam team 4
The beta-beam options n Low energy beta-beams n n The medium energy beta-beams or the EURISOL beta-beam n n Lorenz gamma >1000 The high Q-value beta-beam n n Lorenz gamma 300 -500 and average neutrino energy at rest approx. 1. 5 Me. V The very high energy beta-beam n n Lorenz gamma approx. 100 and average neutrino energy at rest approx. 1. 5 Me. V (P. Zucchelli, 2002) The high energy beta-beam n n Nuclear physics, double beta-decay nuclear matrix elements, neutrino magnetic moments Lorenz gamma 100 -500 and average neutrino energy at rest 6 -7 Me. V The Electron capture beta-beam The beta-beam team Beta-beam requirements, 5
The EURISOL scenario n n n Based on CERN boundaries Ion choice: 6 He and 18 Ne Relativistic gamma=100/100 n n n EURISOL scenario SPS allows maximum of 150 (6 He) or 250 (18 Ne) Gamma choice optimized for physics reach Based on existing technology and machines n n Ion production through ISOL technique Bunching and first acceleration: ECR, linac Rapid cycling synchrotron Use of existing machines: PS and SPS n Opportunity to share a Mton Water Cerenkov detector with a CERN superbeam, proton decay studies and a neutrino observatory n Achieve an annual neutrino rate of either n n n 2. 9*1018 anti-neutrinos from 6 He Or 1. 1 1018 neutrinos from 18 Ne Once we have thoroughly studied the EURISOL scenario, we can “easily” extrapolate to other cases. EURISOL study could serve as a reference. The beta-beam team 6
Which ion is best? n Factors influencing ion choice n n n Need to produce reasonable amounts of ions. Noble gases preferred - simple diffusion out of target, gaseous at room temperature. Not too short half-life to get reasonable intensities. Not too long half-life as otherwise no decay at high energy. Avoid potentially dangerous and long-lived decay products. EURISOL Choice in 2002 n Helium-6 to produce antineutrinos: n Neon-18 to produce neutrinos: The beta-beam team 7
However, there are other… The beta-beam team Beta-beam requirements, 8
n Production of beta-beam The Isotope Separation On-Line (ISOL) method at isotopes medium energy n n Direct production n n EURISOL type production, uses typically 0. 1 -2 Ge. V protons with up to 100 -200 k. W beam power through spallation, fission and fragmentation Uses low energy but high intensity ion beams on solid or gas targets. Production through compound nuclei which forms with high cross section at low energies Direct production enhanced with a storage ring n n Enhancing the efficiency of the direct production through recirculation and re-acceleration of primary ions which doesn’t react in the first passage through the target. Possible thanks to ionization cooling! The beta-beam team Beta-beam requirements, 9
Options for production n ISOL method at 1 -2 Ge. V (200 k. W) n n n 201 >1 1013 6 He per second <8 1011 18 Ne per second 8 Li and 8 B not studied Studied within EURISOL 1 Ge. V p fragmentation + 238 n p + Fr U 11 Li fission 143 Cs + X + Y + Direct production n n spallation >1 1013 (? ) 6 He per second 1 1013 18 Ne per second 8 Li and 8 B not studied Studied at LLN, Soreq, WI and GANIL Production ring n n 1014 (? ) 8 Li >1013 (? ) 8 B 6 He and 18 Ne not studied Will be studied in the future The beta-beam team 10
6 He production from 9 Be(n, a) Converter technology: (J. Nolen, NPA 701 (2002) 312 c) n n Converter technology preferred to direct irradiation (heat transfer and efficient cooling allows higher power compared to insulating Be. O). 6 He production rate is ~2 x 1013 ions/s (dc) for ~200 k. W on target. The beta-beam team 11
Direct production: 16 O(3 He, n)18 Ne n Measurements at Louvain-La-Neuve (CRC) of cross section • The gas target was constructed like a cell with thin entrance foils • In experiment the target pressure and the 3 He beam energy was changed Courtesy to Semen Mitrofanov and Marc Loislet at CRC, Belgium Beam energy, Me. V Target pressure, mbar (torr). Eloss, Me. V 13 900 (675) 2 14. 8 1200 (900) 2. 4 The beta-beam team 12
Preliminary results from CRC n Production of 1012 18 Ne in a Mg. O target: n n n At 13 Me. V, 17 m. A of 3 He At 14. 8 Me. V, 13 m. A of 3 He Producing 1013 18 Ne could be possible with a beam power (at low energy) of 1 MW (or some 130 m. A 3 He beam). To keep the power density similar to LLN (today) the target has to be 60 cm in diameter. To be studied: n n n Extraction efficiency Ion Optimum energy beam Cooling of target unit High intensity and low energy ion linac High intensity ion source The beta-beam team Thinn Mg. O target Water cooled target holder and beam dump 13
Light RIB Production with a 40 Me. V Deuteron Beam n n n T. Y. Hirsh, D. Berkovits, M. Hass (Soreq, Weizmann I. ) Studied 9 Be(n, α)6 He, 11 B(n, a)8 Li and 9 Be(n, 2 n)8 Be production For a 2 m. A, 40 Me. V deuteron beam, the upper limit for the 6 He production rate via the two stage targets setup is ~6∙ 1013 atoms per second. The beta-beam team Beta-beam requirements, 14
A new approach for the production Beam cooling with ionisation losses – C. Rubbia, A Ferrari, Y. Kadi and V. Vlachoudis in NIM A 568 (2006) 475– 487 7 Li(d, p)8 Li 7 Li 6 Li(3 He, n)8 B 6 Li Missed opportunities See also: Development of FFAG accelerators and their applications for intense secondary particle production, Y. Mori, NIM A 562(2006)591 The beta-beam team 15
Critical review of the production ring concept n Low-energy Ionization cooling of ions for Beta Beam sources – D. Neufer (To be submitted) n n Mixing of longitudinal and horizontal motion necessary Less cooling than predcited Beam larger but that relaxes space charge issues If collection done with separator after target, a Li curtain target with 3 He and Deutron beam would be preferable n Separation larger in rigidity The beta-beam team 16
n Problems with collection device A large proportion of beam particles (6 Li) will be scattered into the collection device. n n The scattered primary beam intensity could be up to a factor of 100 larger than the RI intensity for 5 -13 degree using a Rutherford scattering approximation for the scattered primary beam particles (M. Loislet, UCL) The 8 B ions are produced in a cone of 13 degree with 20 Me. V 6 Li ions with an energy of 12 Me. V± 4 Me. V (33% !). Secondary ions Rutherford scattered particles Collection off-axes using Wien filter Beam Collection on-axes The beta-beam team 17
Low duty cycle, from dc to very short bunches… n …or how to make meatballs out of sausages! • Radioactive ions are usually produced as a “dc” beam but synchrotrons can only accelerate bunched beams. • For high energies, linacs are long and expensive, synchrotrons are cheaper and more efficient. The beta-beam team 18
60 GHz « ECR Duoplasmatron » for gaseous RIB 2. 0 – 3. 0 T pulsed coils or SC coils Very high density magnetized plasma ne ~ 1014 cm-3 Target Small plasma chamber F ~ 20 mm / L ~ 5 cm Arbitrary distance if gas Rapid pulsed valve ? F 1 -3 mm 100 KV extraction UHF window or « glass » chamber (? ) 60 -90 GHz / 10 -100 KW 10 – 200 µs / = 6 -3 mm optical axial coupling 20 – 100 µs 20 – 200 m. A 1012 per bunch with high efficiency optical radial (or axial) coupling (if gas only) The beta-beam team P. Sortais et al. 19
Charge state distribution! n Multiple charge state acceleration in linac? The beta-beam team 20
n What is important for the decay ring? The atmospheric neutrino background is large at 500 Me. V, the detector can only be open for a short moment every second n The decay products move with the ion bunch which results in a bunched neutrino beam Ions move almost at the speed of light Only “open” when neutrinos arrive n n Low duty cycle – short and few bunches in decay ring Accumulation to make use of as many decaying ions as possible from each acceleration cycle The beta-beam team 21
Injection The beta-beam team 22
Rotation The beta-beam team 23
Merging The beta-beam team 24
Repeated Merging The beta-beam team 25
Test experiment in CERN PS Ingredients energy – h=8 and h=16 systems of PS. – Phase and voltage variations. time S. Hancock, M. Benedikt and JL. Vallet, A proof of principle of asymmetric bunch pair merging, ABNote-2003 -080 MD The beta-beam team 26
The Large Aperture Dipole, first feasibility study Courtesy Christine Vollinger high tip field, noncritical 6 T LHC ”costheta” design Good-field requirements only apply to about half the horizontal aperture. 27 The beta-beam team
Collimation and absorption Merging: n n increases longitudinal emittance Ions pushed outside longitudinal acceptance momentum collimation in straight section Optical functions (m) n Decay product n n Daughter ion occurring continuously along decay ring To be avoided: n n magnet quenching: reduce particle deposition (average 10 W/m) Uncontrolled activation primary collimator s (m) Straight section: Ion extraction et each end Arcs: Lattice optimized for absorber system OR open mid-plane dipoles Deposited Power (W/m) n s (m) The beta-beam team A. Chance et al. , CEA Saclay 28
Model for absorbers Horizontal Plane Absorber outside beam-pipe Beam Pipe Dipole 1 Dipole 2 1 m 6 m 2 m The beta-beam team Absorber in beam pipe 6 m 1 m 2 m 29
Heat Deposition Model, one cell Q Absorbers B B Q (ISR model) ”Overlapping” Quad to check repeatability of pattern B (new design) B No Beampipe (angle large) Q 30 Concentric cylinders, copper (coil), iron (yoke) The beta-beam team
Local Power Deposition Local power deposition concentrated around the mid plane. Limit for quench 4. 3 m. W/cm 3 (LHC cable data including margin) • • 31 The beta-beam team Situation fine for 6 Li 18 F: 12 m. W/cm 3
Intra Beam scattering, growth times Results obtained with Mad-8 • 6 He • 18 Ne The beta-beam team 32
Particle turnover n ~1 MJ beam energy/cycle injected LHC project report 773 equivalent ion number to be removed ~25 W/m average bb deca y los Momentum collimation injection merging p-collimation ses aig Str ctio e ht s Arc n Arc Straight section n n Momentum collimation: ~5*1012 6 He ions to be collimated per cycle Decay: ~5*1012 6 Li ions to be removed per cycle per meter The beta-beam team 33
Decay losses • Losses during acceleration • Preliminary results: – 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). – Manageable in low-energy part. – PS heavily activated (1 s flat bottom). • Collimation? New machine? – SPS ok. – Decay ring losses: • Tritium and sodium production in rock is well below national limits. • Reasonable requirements for tunnel wall thickness to enable decommissioning of the tunnel and fixation of tritium and sodium. • Heat load should be ok for superconductor. The beta-beam team FLUKA simulated losses in surrounding rock (no public health implications) 34
Activation and coil damage in the PS n The coils could support 60 years operation with a EURISOL type beta-beam The beta-beam team Beta-beam requirements, 35
Radiation protection issues n Radiation safety for staff making interventions and maintenance at the target, bunching stage, accelerators and decay ring n n Safe collimation of “lost” ions during stacking n n 88% of 18 Ne and 75% of 6 He ions are lost between source and injection into the Decay ring ~1 MJ beam energy/cycle injected, equivalent ion number to be removed, ~25 W/m average Magnet protection Dynamic vacuum First study (Magistris and Silari, 2002) shows that Tritium and Sodium production in the ground water around the decay ring should not be forgotten The beta-beam team Beta-beam requirements, 36
Neutrino flux from a betabeam n EURISOL beta-beam study n n Aiming for 1018 (anti-)neutrinos per year It is possible that it could be increased to some 1019 (anti) neutrinos per year. However, this only be clarified by detailed and site specific studies of: n n Production Bunching n n Multiple charge state acceleration in linac Loss management n n n Magnet protection Cooling down times for interventions Tritium and Sodium production in ground water The beta-beam team Beta-beam requirements, 37
How effective is the different proposed improvements? n Increase production, improve bunching efficiency, accelerate more than one charge state and shorten acceleration n Accumulation n Improves performance linearly Can be done as an upgrades! Improves to saturation Can be done as an upgrade! Improve the stacking; sacrifice duty factor, add cooling or increase longitudinal bunch size n n Improves to saturation Can be done as an upgrade! The beta-beam team Beta-beam requirements, 38
Stacking efficiency and low duty factor Normalized Annual rate n For 15 effective stacking cycles, 54% of ultimate intensity is reached for 6 He and for 20 stacking cycles 26% is reached for 18 Ne The beta-beam team Beta-beam requirements, 39
Why do we gain with such an accumulation ring? n n Left: Cycle without accumulation Right: Cycle with accumulation. Note that we always produce ions in this case! The beta-beam team 40
n The beta-beam in EURONU DS The study will focus on production issues for Li and 8 n n 8 B is highly reactive and has never been produced as on ISOL beam Production ring enhanced direct production n n 8 B Which is the best ring lattice? How to collect the produced ions? What are the “real” cross sections for the reactions? How can the accelerator chain and decay ring be adapted to 8 Li and 8 B n n Magnet protection system Intensity limitations The beta-beam team Beta-beam requirements, 41
Gamma and decay-ring size, 6 He Gamma Rigidity [Tm] Ring length T=5 T f=0. 36 Dipole Field rho=300 m Length=6885 m 100 150 200 350 500 935 1403 1870 3273 4676 4197 6296 8395 14691 20987 3. 1 4. 7 6. 2 10. 9 15. 6 New SPS Civil engineering Magnet R&D New version corrected version posted 3 September 2008 thanks to Sanjib Kumar Agarwalla who spotted a mistake in the previous table.
Conclusions n The EURISOL beta-beam conceptual design report will be presented in second half of 2009 n n A beta-beam facility using 8 Li and 8 B n n Known technology with good performance …and tomorrow n n First result from Euronu DS WP A beta-beam facility can be built today… n n First coherent study of a beta-beam facility In a phased scenario the intensity and type of ion can be improved/changed Crucial to chose the right machine-detector combination (distance) from the beginning! The beta-beam team Beta-beam requirements, 43
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