Betabeams M Benedikt A Fabich and M Lindroos

Beta-beams M. Benedikt, A. Fabich and M. Lindroos, CERN on behalf of the Beta-beam Study Group http: //cern. ch/beta-beam BENE 06/CARE 06 IDS, March, CERN 2007 Beta-beam team 1

Outline • Beta-beam concept • EURISOL DS scenario – Layout – Main issues on acceleration scheme • Other scenarios – High-Q vlaue Beta-beams • Study II • Summary IDS, March, CERN 2007 Beta-beam team 2

Beta-beam principle Aim: production of (anti-)neutrino beams from the beta decay of radio-active ions circulating in a storage ring – Similar concept to the neutrino factory, but parent particle is a beta-active isotope instead of a muon. Beta-decay at rest – – • n-spectrum well known from electron spectrum Reaction energy Q typically of a few Me. V Accelerated parent ion to relativistic gmax – – Boosted neutrino energy spectrum: En 2 g. Q Forward focusing of neutrinos: 1/g • Pure electron (anti-)neutrino beam! • Physics applications of a beta-beam – – g=100 NB: Depending on b+- or b--decay we get a neutrino or anti-neutrino Two (or more) different parent ions for neutrino and anti-neutrino beams Primarily neutrino oscillation physics and CP-violation Cross-sections of neutrino-nucleus interaction IDS, March, CERN 2007 Beta-beam team 3

Guideline to n-beam scenarios based on radio-active ions • Low-energy beta-beam: relativistic g < 20 • Medium energy beta-beam: g ~ 100 • High energy beta-beam: g >350 • Monochromatic neutrino-beam • High-Q value beta-beam: g ~ 100 – Physics case: neutrino scattering – E. g. EURISOL DS – Today the only detailed study of a beta-beam accelerator complex – Take advantage of increased interaction cross-section of neutrinos – Take advantage of electron-capture process Accelerator physicists together with neutrino physicists defined the accelerator case of g=100/100 to be studied first (EURISOL DS). IDS, March, CERN 2007 Beta-beam team 4

The EURISOL scenario • • Based on CERN boundaries Ion choice: 6 He and 18 Ne • Relativistic gamma=100/100 • Based on existing technology and machines • Achieve an annual neutrino rate of either • Once we have thoroughly studied the EURISOL scenario, we can “easily” extrapolate to other cases. EURISOL study could serve as a reference. – – – – EURISOL scenario SPS allows maximum of 150 (6 He) or 250 (18 Ne) Gamma choice optimized for physics reach Ion production through ISOL technique Post acceleration: ECR, linac Rapid cycling synchrotron Use of existing machines: PS and SPS 2. 9*1018 anti-neutrinos from 6 He Or 1. 1 1018 neutrinos from 18 Ne IDS, March, CERN 2007 Beta-beam team 5

Intensity evolution during acceleration Bunch 20 th total 15 th 10 th 5 th 1 st Cycle optimized for neutrino rate towards the detector • • 30% of first 6 He bunch injected are reaching decay ring Overall only 50% (6 He) and 80% (18 Ne) reach decay ring • Normalization – Single bunch intensity to maximum/bunch – Total intensity to total number accumulated in RCS IDS, March, CERN 2007 Beta-beam team 6

Dynamic vacuum • Decay losses cause degradation of the vacuum due to desorption from the vacuum chamber C. Omet et al. , GSI • The current study includes the PS, which does not have an optimized lattice for unstable ion transport and has no collimation system – The dynamic vacuum degrades to 3*10 -8 Pa in steady state (6 He) • An optimized lattice with collimation system would improve the situation by more than an order of magnitude. IDS, March, CERN 2007 Beta-beam team P. Spiller et al. , GSI 7

Particle turnover • ~1 MJ beam energy/cycle injected equivalent ion number to be removed ~25 W/m average LHC project report 773 bb deca y los Momentum collimation injection merging p-collimation ses aig Str ctio e ht s Arc n Arc • • Straight section 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 IDS, March, CERN 2007 Beta-beam team 8

Collimation and absorption • Merging: • Decay product – Daughter ion occurring continuously along decay ring To be avoided: • • – Optical functions (m) – increases longitudinal emittance Ions pushed outside longitudinal acceptance momentum collimation in straight section primary collimator s (m) Straight section: Ion extraction et each end magnet quenching: reduce particle deposition (average 10 W/m) Uncontrolled activation Arcs: Lattice optimized for absorber system OR open mid-plane dipoles – IDS, March, CERN 2007 Deposited Power (W/m) – – s (m) Beta-beam team A. Chance et al. , CEA Saclay 9

Decay ring magnet protection • • Absorbers checked (in beam pipe): No absorber, Carbon, Iron, Tungsten Theis C. , et al. : "Interactive three dimensional visualization and creation of geometries for Monte Carlo calculations", Nuclear Instruments and Methods in Physics Research A 562, pp. 827 -829 (2006). IDS, March, CERN 2007 Beta-beam team 10

Longitudinal penetration in coil Power deposited in dipole Coil Abs Coil No absorber Carbon IDS, March, CERN 2007 Beta-beam team Abs Coil Stainless Steel 11

Impedance, 340 steps! Below 2. 3 GHz, a total of 340 steps (170 absorbers) would add up to 0. 5 m. H, which seems really high. lowest cut-off (2. 3 GHz) Im{Z}/W Impedance of one step (diameter 6 to 10 cm or 10 to 6 cm): L = 1. 53 n. H f/GHz IDS, March, CERN 2007 Beta-beam team 12

Possible new solution Cu or SS Between dipoles Top view, midplane y [m] In dipoles IDS, March, CERN 2007 60 degrees Cu or SS sheets with 60 degrees opening on the sides beams Beta-beam team 13

Intra Beam scattering, growth times Results obtained with Mad-8 • 6 He • 18 Ne IDS, March, CERN 2007 Beta-beam team 14

A new approach for the production Beam cooling with ionisation losses – C. Rubbia, A Ferrari, Y. Kadi and V. Vlachoudis in NIM A, In press “Many other applications in a number of different fields may also take profit of intense beams of radioactive ions. ” 7 Li 6 Li 7 Li(d, p)8 Li 6 Li(3 He, n)8 B Missed opportunities See also: Development of FFAG accelerators and their applications for IDS, intense March, CERN Beta-beam secondary particle production, Y. team Mori, NIM A 562(2006)591 2007 15

Transverse cooling in paper by Carlo Rubbia et al. “In these conditions, like in the similar case of the synchrotron radiation, the transverse emittance will converge to zero. In the case of ionisation cooling, a finite equilibrium emittance is due to the presence of the multiple Coulomb scattering. ” IDS, March, CERN 2007 Beta-beam team 16

Longitudinal cooling in paper by Carlo Rubbia et al. “In order to introduce a change in the d. U/d. E term — making it positive in order to achieve longitudinal cooling — the gas target may be located in a point of the lattice with a chromatic dispersion. The thickness of the foil must be wedge-shaped in order to introduce an appropriate energy loss change, proportionally to the displacement from the equilibrium orbit position. ” Number of turns IDS, March, CERN 2007 Beta-beam team 1) Without wedge, d. U/d. E<0 2) Wedge with d. U/d. E=0, no longitudinal cooling 3) Wedge with d. U/d. E=0. 0094 4) Electrons, cooling through synchrotron radiation 17

Inverse kinematics production and ionisation parameters in paper by Carlo Rubbia et al. 7 Li(d, p)8 Li 6 Li(3 He, n)8 B IDS, March, CERN 2007 Beta-beam team 18

Collection in paper by Carlo Rubbia et al. “The technique of using very thin targets in order to produce secondary neutral beams has been in use for many years. Probably the best known and most successful source of radioactive beams is ISOLDE. ” B form compounds and has never been produced in from a solid ISOL target. Can we use “Flourination” and extract BF? For me this is the most critical point of this proposal! IDS, March, CERN 2007 Beta-beam team 19

Reactions to study for EURISOL beta-beams • 20 Ne(p, t)18 Ne – H. Backhausen et al, RCA, 29(1981)1 • 16 O(3 He, n)18 Ne – V. Tatischeff et al, PRC, 68(2003)025804 • 6 C(CO 6 He)18 Ne? , 2 – K. I. Hahn et al, PRC, 54(1996)1999 • 7 Li(T, A)6 He IDS, March, CERN 2007 Beta-beam team 20

Collection in a gas cell • IGISOL technique (Ion Guide) Cool gas in Gas cell BEAM Extraction • Figure from Juha Aysto, Nucl. Phys. A 693(2001)477 • At 200 Torr of 4 He, 10% efficiency, space charge limit at 10 8 ions cm-3 (peak 1010 ions cm-3? ), Private communication Ari Jokinen • Consierably higher efficiency using cryogenic He gas. • Possible to use superfluid helium with very high efficiency but method to release ions have to be developed • Will scattered primary ion beam be a problem? • Can we separate the secondaries from the primaries with a fragment separator insertion to avoid hole? IDS, March, CERN 2007 Beta-beam team 21

What about the intensities? – Cross section similar or larger compared to those studied in detail in C. Rubbia et al. ’s paper – Heavier ions in the ring will require further beam dynamics study – Space charge effects will set the limit for the IGISOL type device. With a 1000 cm 3 gas cell, is 1011 ions s-1 realistic? – Collection with foils as proposed by C. Rubia et al? IDS, March, CERN 2007 Beta-beam team 22

Objectives • A High Intensity Neutrino Oscillation Facility in Europe – CDR for the three main options: Neutrino Factory, Betabeam and Super-beam – Focus on potential showstoppers – Preliminary costing to permit a fair comparison before the end of 2011 taking into account the latest results from running oscillation experiments – Total target for requested EU contribution: 4 Meuro • 3. 5 MEuro from EU for SB, NF and BB WPs plus lab contributions • 1. 5 MEuro to be shared between Mgt, Phys and Detectors WPs plus lab contributions • 4 year project IDS, March, CERN 2007 Beta-beam team 23

Beta-beam WPs • • • WP leader: Michael Benedikt, CERN Deputy: Adrian Fabich, CERN Objective: – – – • • Coordination task: CERN leads the task, is responsible for the parameter list and for the overall coherence of the baseline scenario. Review task: The work will start with a review of the base line design for the new isotopes 8 B and 8 Li performed by CERN and CEA. Bunching task: The work at LPSC with the 60 GHz ECR source for bunching studies of 6 He and 18 Ne started within EURISOL DS will continue with the objective of reaching the high efficiencies needed for the beta-beam. . Furthermore, a study and first tests will be done at LPSC of necessary modification to bunch 8 Li and 8 B. Cross sections and collection device task: The cross section for the reaction channels of interest will be (re-)measured and a prototype for the collection device will be built and tested with stable beams at LLN. Superconducting magnets, magnet protection and collimation task: A pre-study of possible lay-out for superconducting dipoles for the beta-beam will be done at CERN and a baseline design will be identified. The work started on beam collimation and magnet protection in EURISOL DS will be adapated for 8 Li and 8 B at CERN and CEA Participating institutes: CERN, UCL, IN 2 P 3 (LPSC), CEA Additional partners: INFN (LNL), TRIUMF, RAS/IAP, Princeton, ANL IDS, March, CERN 2007 Beta-beam team 24

Annual participants meeting EUROn DS • Annual meeting: – Monitoring of progress and coherence of the study by SC and IAP members – Annual review of project deliverables and milestones – Bringing the European (and International) Neutrino oscillation community together • Physics community and machine community IDS, March, CERN 2007 Beta-beam team 25

Summary • Beta-beam accelerator complex is a very high technical challenge due to high ion intensities – • • Activation Space charge So far it looks technically feasible. • The physics reach for the EURISOL DS scenario is competitive for 13>1 O. • The physics made possible with the new production concept proposed by Rubbia and Mori needs to be explored • We need a study II and we are working on a WP in Euron Design study • Working meeting for beta-beams at ANL 24 May! – – – Usefulness depends on the short/mid-term findings by other neutrino search facilities. Plenty of new ideas! Contact Jerry Nolen at ANL. Acknowledgment of the input given by S. Hancock, A. Jansson, M. Mezzetto, E. Wildner, EURISOL beta-beam task group and related EURISOL tasks IDS, March, CERN 2007 Beta-beam team 26