New Opportunities in the Physics Landscape at CERN
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500/1-001 - Main Auditorium (CERN)
Description
The Workshop will preview, and foster reflection on, experiments not directly related to the current LHC programme that could be carried out at CERN in the next 5-10 years.
It is scheduled for May 11th to 13th and will be held at CERN. It will look at activities requiring the accelerator infrastructures at CERN: SPS, PS, AD, ISOLDE, nTOF, as well as those non-accelerator experiments that are best carried out at CERN. The plans for neutrino physics, except for CNGS, will not be addressed during this workshop. A dedicated event will be organised at CERN in conjunction with a working group set up by the Scientific Policy Committee, on October 1st-3rd, to cover this subject.
The Workshop will be structured roughly along the lines of the various accelerators.
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Welcome Drink Restaurant 1
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Welcome 10mSpeaker: Rolf Heuer (CERN)
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Discussion 10m
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SPS Deep-Inelastic Scattering, including polarized targets 500/1-001 - Main Auditorium
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Longitudinal Spin Structure and Generalized Parton Distributions with Muon Beam at COMPASS 20mcombination of abstracts 27 (Study of Generalized Parton Distributions using high energy muon beams at COMPASS) and 28 ( Longitudinal Spin Structure of the Nucleon at COMPASS)Speaker: Nicole D'Hose (CEA/IRFU Saclay)
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Transverse Spin Structure with Muon Beam and Drell-Yan Measurements at COMPASS 20mCombination of abstracts 26 and 29:(Measurements of transverse spin asymmetries on a transversely polarized proton target with the high energy muon beam at the SPS) (Drell-Yan Physics with COMPASS)Speaker: Mr Franco Bradamante (Trieste)
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The measurement of the W mass at the LHC: shortcuts revisited 15mThe claim that the W mass will be measured at the LHC with a precision at the 10 MeV level is critically reviewed. It is argued that in order to achieve such precision, a considerably better knowledge of the u-valence, d-valence, s and c structure functions of the proton is needed. An experimental programme is suggested that will deliver the missing information. The core of this programme is a dedicated muon scattering experiment on a hydrogen/deuterium target at the CERN SPS.Speaker: Friedrich Dydak (CERN)
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Discussion 15m
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SPS Rare K-decays and CNGS 500/1-001 - Main Auditorium
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Search for heavy neutral leptons 10mThe search for 'sterile' neutrinos has been done in the past looking for decays of heavy states in a neutrino beam (PS191 experiment) With much higher luminosities available at future machines, the search could be repeated both at the PS (to improve the present limits for masses up to the K mass) and at the SPS (where masses up to the B can be investigated) The recent nuMSM model which tries to explain the active neutrino masses gives a new interest in such searches.Speaker: Francois Vannucci (Lab. Phys. Nucl. Hautes Energies (LPNHE)-Universites de Paris VI)
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NA62: New Opportunities in Rare Kaon Decays 15mThere are currently three main directions in elementary particle physics. On the one hand experiments at the highest possible energies are searching for the origin of electroweak breaking and direct evidence of New Physics (NP); a second line of attack aims to study the properties of neutrinos, both of accelerator and cosmic origin, and of other astro-particle messengers. The third strategy is to explore the precision frontier looking for deviations from the Standard Model (SM) predictions in rare or forbidden processes. In this latter case, the sensitivity to NP originates from the virtual contributions that can involve all discovered and not yet discovered particles in higher order quantum loops and therefore can address, indirectly, energy scales even beyond those accessible at colliders. Some of the most interesting rare decays are those Flavour Changing Neutral Currents (FCNC) that can be predicted with small hadronic uncertainties in the SM. There are only very few observables where there is both sensitivity to NP and a well calculable expectation within the SM. A very prominent example is given by the K --> pi nu nubar decays and it is on precisely this subject that the CERN kaon physics strategy has been developed. The NA62 experiments plans to address first the charged kaon decay by exploiting the current performance of the SPS. Possible future studies of the neutral kaon ultra-rare decays could be envisaged in the framework of an upgraded proton accelerator complex. The CERN proton complex is unique. The Super Proton Synchrotron (SPS) will remain in operation for the foreseeable future as LHC injector. This injection task should occupy only a few hours per day, leaving the SPS available to feed primary protons to fixed target experiments for most of the time. We shall present the physics sensitivity of the CERN-NA62 experiment to study ultra-rare decays at the CERN-SPS and its present status. In addition to the very rare decays, the proposal offers a rich physics programme ranging from precision tests of lepton universality to the study of strong interactions at low energy. An outlook will be presented for possibilities in the upgraded accelerator complex.Speaker: Augusto Ceccucci (CERN)
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DOUBLE-LAr: sterile neutrinos at the CERN-PS ? 15mThe development of the Liquid Argon Imaging TPC has been actively pursued by the ICARUS Collaboration during the last two decades. The technology has reached its fully mature level and a first underground experiment with some 600 tons of sensitive mass, the ICARUS T600 detector is now in its final phase of installation underground at the LNGS. First of its kind, it will become fully operational during 2009 and initiate the first full scale underground physics experiment based on LAr-Imaging technology (CNGS-2). It will also realistically open the way to future more massive detectors for accelerator and without accelerator driven phenomena (see for instance MODULAr) . The present LOI describes another very important physics domain in which the LAr Imaging should be extended with a detector of the approximate size of the T600 (about 200x the volume of Gargamelle, but comparable resolutions) associated with availability of a low energy neutrino beam (with L/E ~ 0.5 Km/GeV) within the CERN premises and reactivating the traditional PS driven neutrino beam. This project will benefit of the already developed and well tested technology of ICARUS T600, without the need of any major R&D activity. The PS beam is the one originally used by the BEBC-PS180 at 19.2 GeV/c, extracted from the PS via the transfer tunnels TT2, TT1 and TT7. The magnetic horn is designed to focus particles of momentum around 2 GeV/c. The decay tunnel is about 50 m long, followed by an iron beam stopper. The main location (far position) is at about 850 m from the target in the existing BEBC hall.Speaker: Carlo Rubbia (CERN & INFN)
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A new, very massive modular Liquid Argon Imaging Chamber to detect low energy off-axis neutrinos from the CNGS beam. (Project MODULAr) 10mThe present ICARUS with its 600 tons now in the CNGS beam, represents the real core of the experimental LAr neutrino physics and a necessary prerequisite for reaching many kton masses either at CERN (to LNGS), at Fermilab, or perhaps elsewhere. It is the result of about two decades of unique R&D developments in which the ICARUS team has had a dominant role. Our next step, called MODULAr has been amply described in two published papers, one scientific, the other technical to which we refer for details. MODULAr is based on the present neutrino beam from CERN to LNGS, but with a new LAr detector with about a 20 kton fiducial mass, located off-axis from the neutrino beam. The main request from CERN, beside machine time, are the already known improvements in the number of accelerated protons, already foreseen in parallel with the LHC related beam improvement programmes, although it assumes a dedicated operation of the fixed target use of the SPS, in parallel with LHC.Speaker: Alberto Guglielmi (Istituto Nazionale de Fisica Nucleare (INFN))
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Opportunities for European neutrino oscillation physics building on the T2K experience 10mThe current focus of the CERN program is the Large Hadron Collider (LHC), however, CERN is engaged in long baseline neutrino physics with the CNGS project and supports T2K as recognized CERN RE13, and for good reasons: a number of observed phenomena in high-energy physics and cosmology lack their resolution within the Standard Model of particle physics; these puzzles include the origin of neutrino masses, CP-violation in the leptonic sector, and baryon asymmetry of the Universe. They will only partially be addressed at LHC. T2K is optimized for searching for electron appearance with a sensitivity sin^2(2theta_{13}) < 0.01 (90%C.L.). A large fraction of the European neutrino community is visibly engaged in T2K, with participants from France, Germany, Italy, Poland, Spain, Switzerland and United Kingdom. The T2K beam will start commissioning in April 2009 and the first physics results are expected by summer 2010. The baseline intensity of the T2K beam is 750 kW. A plan to upgrade the Main Ring to 1.6 MW has been presented in the KEK roadmap. Possible scenarios for beam upgrade and new far detectors have been discussed at the 4th International Workshop on Nuclear and Particle Physics at J-PARC (NP08) in March 2008. A positive measurement of sin^22theta_{13}>0.01 in T2K would certainly give a tremendous boost to neutrino physics by opening the possibility to search for, and study, CP violation in the lepton sector and the determination of the neutrino mass hierarchy with upgraded conventional super-beams. These experiments (so called « Phase II ») require, in addition to an upgraded beam power, next generation very massive neutrino detectors with excellent energy resolution and high detection efficiency in a wide neutrino energy range, to cover 1st and 2nd oscillation maxima to help lift the degeneracy among the parameters governing neutrino oscillations, and excellent particle identification and pi0 background suppression. Two generations of large water Cherenkov detectors at Kamioka (Kamiokande and Super-Kamiokande) have been extremely successful. And there are good reasons to consider a third generation water Cherenkov detector with an order of magnitude larger mass than Super-Kamiokande for both non-accelerator (proton decay, supernovae, ...) and accelerator-based physics. In parallel, the pioneering developments of the ICARUS liquid Argon TPC with immersed readout wires, already the fruit of several decades of R&D, has not been able, although offering better physics performance, to deliver detectors competitive with Super-Kamiokande, nor envisage an ultimate detector challenging the planned third generation water Cerenkov detectors. Only a very massive underground liquid Argon detector of about 100 kton could represent a credible alternative for the precision measurements of « Phase-II » and aim at significantly new results in neutrino astroparticle and non-accelerator-based particle physics (e.g. proton decay). The new concept « GLACIER », scalable to a single detector unit of mass 100 kton, was proposed in 2003: it relies on a cryogenic storage tank developed by the petrochemical industry (LNG technology) and on a novel method of operation called the LAr LEM-TPC. LAr LEM-TPCs operate in double phase with charge extraction and amplification in the vapor phase. The concept has been very successfully demonstrated on small prototypes: ionization electrons, after drifting in the LAr volume, are extracted by a set of grids into the gas phase and driven into the holes of a double stage Large Electron Multiplier (LEM), where charge amplification occurs. Each LEM is a thick macroscopic hole multiplier, which can be manufactured with standard PCB techniques. The electrons signal is readout via two orthogonal coordinates, one using the induced signal on the segmented upper electrode of the LEM itself and the other by collecting the electrons on a segmented anode. The images obtained with the LAr LEM-TPC are of very high -- « bubble-chamber-like » -- quality, owing to the charge amplification in the LEM and have good measured dE/dx resolution. Compared to LAr TPCs with immersed wires, whose scaling is at least limited by mechanical and capacitance issues of the long thin wires and by signal attenuation along the drift direction, the LAr LEM-TPC is an elegant solution for very large liquid Argon TPCs with long drift paths and mm-sized readout pitch segmentation. A ton-scale LAr LEM-TPC detector is being operated at CERN in Blg 182 within the CERN RE18 experiment (ArDM). The proposed next step beyond that is the construction of device dedicated for the precise calibration, the study of the calorimetric response and for the particle recognition capability of such detectors. The proposed test beam will be located in the CERN North Area (see ePiLAr in test beam submission). The current CNGS optimization provides limited sensitivity to sin^2(2theta_{13}), CP-violation in the leptonic sector and mass hierarchy determination. Ideas to improve the sin^2(2theta_{13}) sensitivity at the CNGS have already been discussed in JHEP 0209 (2002) 004. More recently, the physics potential of an intensity upgraded and energy re-optimized CNGS neutrino beam coupled to a 100 kton liquid Argon TPC located at an appropriately chosen off-axis position was published in JHEP 0611, 032 (2006). The discussion relied on the observation that whereas J-PARC provides a rapid cycle with high intensity proton bunches at approx. 40 GeV/c, the CERN proton complex has fewer protons and a slower cycle but can accelerate to 400 GeV/c. Hence, the SPS higher energy can – on paper – compensate for the lower proton intensity. In addition, the intensity in SPS could profit from future upgrades of the LHC injection chain. In practice, calculations show that the sin^2(2theta_{13}) reach and the searches for CP-violation and mass hierarchy are competitive with future options at J-PARC if the CNGS beam intensity can be increased compared to its design value 4.5x10^{19} pot/yr by a factor x3-x10. Yet CNGS intensity limitations do not only come from the performance of the accelerator complex. An upgraded CNGS -- competitive with JPARC -- will require a re-classification and/or partial reconstruction of the neutrino beam-line infrastructure, raising questions of feasibility, timescale and costs. In the context of the EC FP7 design study LAGUNA, the possibility to rely on an alternative source of medium-energy high-intensity protons from CERN (e.g. from a newly built PS) is under discussion. The LAGUNA community is studying the feasibility of a new large underground infrastructure in Europe able to host next generation neutrino physics and astro-particle physics and proton decay experiments. Seven sites are presently being considered. Given the intensity limitation of the CNGS design, the option of a completely new high-intensity neutrino beam line from CERN towards one of the LAGUNA sites should be left open. For the longer term and in absence of a positive result from T2K, large underground detectors in the LAGUNA sites could be operated as well in connection with other, more advanced neutrino beams like for instance beta-beams or neutrino factories. Such beams are currently being studied within the FP7 design study EuroNU.Speaker: Andre Rubbia (ETH Zurich)
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Discussion 20m
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SPS Hadrons & Ions 500/1-001 - Main Auditorium
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More intense and energetic muon and hadron beams for nucleon structure and spectroscopy (10+5) 15mFundamental QCD questions could be answered at COMPASS if a substantial increase of luminosity of the muon beam, and of the energy of both the muon and hadron beams can be achieved. 1/ MUON BEAM. The high energy polarized muon beam of the CERN SPS is presently offering the unique place in the world where to perform polarized deep inelastic scattering experiments. The highest available energy with a high polarization is of the order of 200 GeV, and the maximum luminosity reached in the M2 beam line ~10^32. COMPASS has exploited this facility during the past years to provide important results on the spin of the nucleon. To go further and study in detail the transverse spin structure, the role of gluons in the spin structure, and the spatial distribution of gluons and quarks in the nucleon, it is essential to enlarge the kinematic range. This can be achieved only by increasing both the luminosity and the energy of the beams available at the COMPASS experiment which can handle polarized as well as unpolarized targets. Very precise measurements of inclusive and exclusive deep inelastic polarized processes at low x and high Q2 values are still needed, as well as new observables like the generalized parton distributions (GPDs) and the Transverse Momentum Dependent distributions (TMDs) which can be studied via both DIS or Drell-Yan processes and require high luminosity. The muon flux arriving at COMPASS has been carefully optimized over the last decade. The main limiting factor to reach higher intensities results from the maximum number of protons which can be extrated from SPS quoted as ~3.2*10^13 (~2*10^13) protons/spill for the long (short) SPS flat tops. Several other limiting factors have been identified: radio protection issues at several places along the beam line, resistance of the T6 primary production target, quadrupoles and other elements of the beam and transfer lines, and finally beam halo level in the experiment. As a consequence, a major upgrade of the beam line including eventually underground installation is unavoidable to reach higher luminosity. Projects for future facilities, like an electron ion collider, to resume studies in this field of physics are already under discussion in other labs. However, such a machine will not be available before 10 or 15 years, and CERN can be a major competitor in this physics domain meanwhile. 2/ HADRON BEAMS. Some of the important physics channels using hadron beams within COMPASS require highest possible energies from the SPS. These comprise central production of hadron resonances, where central production and diffractive production can only be separated kinematically. The central production process is governed by double region exchange and Pomeron-Pomeron scattering, the fraction of which is strongly energy dependent, where the latter one raises with energy. The second topic is connected with the installation of a hyperon beam inside the north area to study doubly charmed baryons. High energy boosts the decay length and thus yield of hyperons extracted from a double bent channel. In addition, charm production cross sections are strongly energy dependent at low center of mass energies, thus the gain in yield of doubly charmed baryon seems substantial. At present, the COMPASS beam line can only transport 270 GeV/c beams, mostly connected with power supplies of the magnets installed. It is desireable to increase the energy up to 450 GeV/c, the highest one available from SPS.Speaker: Fabienne Kunne (CEA/IRFU Saclay)
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Scientific plans of the DIRAC experiment beyond 2010 (20+5) 25mThe main task of the DIRAC experiment is to check precise predictions of low-energy QCD using ππ and πK atoms. At present, theory predicts the ππ s-wave scattering lengths with a precision of 1.5% for |a0-a2| and about 2.5% for a0 and a2. The theoretical uncertainty is mainly determined by uncertainties on two constants of ChPT. In 2006, these constants were obtained from Lattice calculation and one can expect that in a few years this calculation will give an even higher precision of ππ scattering lengths. Experimentally, the scattering lengths were obtained from K-meson decays (K3π, Ke4) and from the ππ-atom lifetime. At present, the precision of ππ scattering lengths measurements is a few percents worse than the theoretical precision. For this reason, improving the experimental accuracy is an important task. The experimental data collected by DIRAC in 2008 and 2009 will allow to reach the precision of about 2.5% for |a0-a2|. The low-energy QCD predicts πK scattering lengths with a precision of about 10%. In a near future, this accuracy will be significantly improved. The experimental estimations of πK scattering lengths were obtained from πK scattering phases at high energy using Roy-Steiner equations. Direct measurements of the πK phases at low energy or of the πK scattering lengths do not exist. The DIRAC experiment plans to observe πK atoms using data collected in 2007-2009 and to measure the lifetime of these atoms and, hence, to obtain the first evaluation the s-wave scattering length combination |a1/2-a3/2|. The measurement of the s-wave πK scattering lengths will test our understanding of the chiral SU(3)LSU(3)R symmetry breaking of QCD (u, d and s quarks), while the measurement of ππ scattering lengths checks only the SU(2)LSU(2)R symmetry breaking (u, d quarks). In 2009, we are planning to present a request for a data-taking run in 2010 with the aim of observing the long-lived states of ππ atoms. This experiment can be performed with the existing setup without modifications, neither of detectors nor of electronics. Further data taking will allow us to obtain experimentally a value of the Lamb shift ΔE(2s-2p) in this atom. The measurement of ΔE(2s-2p) allows determining the combination of ππ scattering lengths 2a0+a2 in a model-independent way. Together with the ππ atom lifetime measurement, this permits to determine a0 and a2 separately. The method of the Lamb shift measurement uses only the well-known theory of the Stark effect. From the data to be collected in 2008 and 2009, it will be possible to observe the Coulomb enhancement in the production of K+K− pairs, and thus to determine, in a model independent way, the number of K+K− atoms produced at the same time. This analysis will allow us to estimate the feasibility to observe these atoms and to measure their lifetime. The 2008-2009 data will also allow us to search for the Coulomb enhancement in the production of πμ pairs and thus to determine, in a model-independent way, the number of πμ atoms produced. This analysis will allow to decide if it is possible with this experiment to observe this atom. The final aim is to measure the Lamb shift in the πμ atom, which is strictly related to the electromagnetic radius of the charged pion. New possibilities to check the predictions of the low-energy QCD would be available after the installation of the DIRAC setup on the 450 GeV SPS proton beam. Simulations based on FRITIOF6, which gives correct π and K meson spectra in the dynamic range of the DIRAC spectrometer, show that at the same intensity of the secondary particles across the forward detectors the number of detected ππ atoms will be 15 times higher than the one at 24 GeV, the number of K+π− atoms 25 times higher and the number of K−π+ atoms 32 times higher. This enhancement in atom yields allows to obtain simultaneously |a0-a2| with a precision of about 1.5% and about 5% for |a1/2-a3/2| within 12 months of data taking. The measurement of the Lamb shift in ππ and πK atoms would take another run. These results would provide the crucial check of low-energy QCD predictions. Migration from PS to PS2 with the 50 GeV beam would also provide a significant gain in the mesonic atom production. The required statistics and achievable accuracy are under investigation.Speaker: Leonid Nemenov (Joint Institute for Nuclear Research (JINR))
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Critical Point and Onset of Deconfinement - Ion Program of NA61/SHINE at the CERN SPS (15+5) 20mThe NA61/SHINE experiment at the CERN SPS aims to discover the critical point of strongly interacting matter and study properties of the onset of deconfinement. These goals will be reached by measurements of hadron production properties in nucleus-nucleus, proton-proton and proton-lead interactions as a function of collision energy and size of the colliding nuclei. Furthermore, NA61/SHINE will perform numerous precision measurements needed for neutrino (T2K) and cosmic-ray (Pierre Auger Observatory and KASCADE) experiments. This contribution summarizes physics arguments for the NA61/SHINE ion program and presents the status and plans of the experiment for the next 5 years.Speaker: Marek Gazdzicki (Frankfurt University)
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Reflections about EXChALIBUR, the exclusive 4pi detector 15mThis provocative title is intended to call for the attention, emphasizing the brainstorming nature of this proposal. The acronym means: EXClusive HAdron and Lepton Instrument for Basic Universal Research. One is looking for the answer to two questions: - Can exclusive experiments help to understand QCD? - Is it possible to build complete 4pi detector? One tries to identify the technical limits which could be reachable within 5 to 10 years in the quest for the ideal particle physics detector.Speaker: Gyoergy Vesztergombi (Res. Inst. Particle & Nucl. Phys. - Hungarian Academy of Science)
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Search of the QCD critical point: study of dimuon pair production at the SPS in the energy range 40-160 GeV/nucleon 20mThe study of strongly interacting matter at high temperature and/or baryon density in ultra-relativistic heavy ion collisions is a field of research which has reached today a considerable maturity. Fixed- target experiments have been carried out at the AGS and SPS with heavy-ion beams at $\sqrt{s}\le$20 GeV/nucleon, and have been followed by an experimental program at the RHIC ion collider, up to $\sqrt{s}=$200 GeV/nucleon. The detection of lepton pairs played a very important role since the very beginning. Fundamental achievements, as the discovery of anomalous J/$\psi$ suppression (NA50, NA60 at SPS, PHENIX at RHIC) and the study of the low and intermediate mass continuum (CERES, HELIOS-3, NA50 and NA60 at SPS, PHENIX at RHIC), connected with chiral symmetry restoration, required in fact a very precise measurement of lepton pairs. In particular, the third generation NA60 experiment at the CERN SPS, coupling the use of a high granularity silicon tracker to a traditional magnetic spectrometer with a selective dimuon trigger, has pushed to unprecedented levels the statistical accuracy, the mass resolution and the background rejection capabilities. This permitted to perform for the first time a quantitative characterization of the $\rho$ spectral function and of the emission of thermal lepton pairs in nuclear collisions. As of today (beginning of 2009), the field is expected to evolve in two different directions. At the LHC, baryon-free deconfined matter with still higher initial temperature, extending over larger regions and with a longer lifetime, will be created. The produced medium will be a reasonable approximation in the lab of the state of the early universe a few micro-seconds after the Big-Bang. On the other hand, the study of the QCD phase diagram remains almost unexplored in the region of moderate temperature and high baryon density. In this regime, lattice QCD studies foresee the occurrence of a critical point, separating a region of a first-order phase transition from hadronic matter to the QGP from a region where the transition is a simple fast cross-over. The search for such a critical point largely motivated the fixed-target CBM experiment at the forthcoming FAIR facility, with a maximum beam energy of about 40 GeV/nucleon ($\sqrt{s}\sim$10 GeV/nucleon). This physics domain also attracted considerable interest inside the RHIC community, leading to the approval of a "low-energy" program, with beams down to a few GeV/nucleon. Finally, at the CERN SPS, the recently approved NA61 experiment aims at studying collisions again with emphasis on the low-energy side (a few tens GeV/nucleon), with a physics program similar to the one proposed at the other two facilities. Both the RHIC program and the NA61 experiment will essentially address the study of hadronic observables, due to the intrinsic low luminosity of the RHIC collider at low energy and to the TPC-based experimental set-up of NA61, resp. For this reason, it would be extremely interesting to extend the lepton measurements made by the NA60 experiment at the CERN SPS by performing an energy scan from the SPS topmost energy down to 40-50 GeV/nucleon, close to the maximum FAIR energy. This would permit the study of leptonic observables in a region of increasing baryon density, close to the possible position of the QCD critical point. The theoretical description of this region, in terms of phenomenology of leptonic probes, is still at a rather preliminary stage. However, there are effects seen at higher energy, as the enhancement of the dilepton yield in the region around the $\rho$ meson, that are expected to be proportional to the baryochemical potential, and that should therefore be considerably enhanced at lower energies. A pioneering measurement performed by CERES at 40 GeV/nucleon indeed seems to suggest this trend. Another key observable, J/$\psi$ suppression, exhibits a threshold- like behaviour at top SPS energy, when studied as a function of the centrality of the collision. The extension of its systematic study towards lower energy could reveal detailed information on the nature of the observed threshold behaviour, and allow a more direct connection with the underlying physics mechanism.Speaker: Gianluca Usai (Cagliari University)
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PS and Non-accelerator Experiments 500/1-001 - Main Auditorium
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Polarized beams at HIE-ISOLDE – from dreams to reality. 5mRadioactive beams of polarized nuclei can contribute substantially to the level of sensitivity of many experiments with exotic nuclei. Therefore obtaining an ion beam of few MeV/u of nuclei with polarized spins is a dream for many physicists. Polarized beams are a must for nuclear moment measurements and for studies of analyzing powers, which provide unique nuclear structure information that cannot be obtained by other means. There are several ways of obtaining an ensemble of nuclei with polarized spins. Among them one can mention the use of laser beams, reaction-induced polarization and by the application of the Tilted Foils (TF) technique. The Tilted Foils is one of the most appealing since it imposes the least requirements and is the easiest to use. In the TF method [1] the polarization is obtained for the atomic electrons via surface interaction of ions traversing a multifoil stack at an oblique angle. The atomic polarization thus produced is subsequently transferred to the nuclear spins. There are examples for the use of post-accelerated TF-polarized ions for Coulomb excitation studies [2] using stable isotopes. These experiments have been done using a LINAC very similar to the one of REX. REX-ISOLDE provides the first opportunity for post-acceleration of polarized radioactive beams. One of the key issues that needs deeper investigation before the TF-polarized beams can be routinely delivered by REX-ISOLDE is the velocity dependence of the polarization obtained. This will be done by the use of a beta-NMR setup, recently provided to ISOLDE by HMI, Berlin. [1] L. Baby et al., J. Phys. G 30, 519 (2004); and references therein. [2] J. Bendahan et al., Zeit. Phys. A331, 343 (1988)Speaker: Georgi Georgiev (CSNSM, Orsay, France)
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Test of the half-life oscillations observed at the ESR storage ring (GSI-Darmstadt) with the WITCH spectrometer at ISOLDE. 5m[submitted by N. Severijns for the CERN, Leuven, Aarhus, Chalmers, GSI-Darmstadt, Münster, Valencia, Bratislava2 collaboration.] Recently the studies on highly charged ions with ion storage rings [1] were extended to nuclear electron capture decays of hydrogenlike ions [2]. Careful experiments performed with only a few ions present in the storage ring at any given time have turned out to give a clear non-exponential distribution of the decay times [3]. There is as yet no consensus on the interpretation of this surprising finding, some theory papers have argued that this is a signature of neutrino-flavour mixing [4], whereas others have contested this suggestion [5]. To resolve this question more experimental data are needed. At present the non-exponential decay, an oscillation with period about 7 seconds on top of an exponential decay, has been observed for hydrogenlike 140Pr and 142Pm ions at the 99% confidence level [3]. We are currently exploring the possibility of testing for the effect in very different experimental circumstances, at ISOLDE. The electron capture decaying nuclei would be produced as usual in the ISOLDE targets, bunched in ISCOOL and/or REXTRAP, transferred to REXEBIS where they will be charge bred and finally let to an ion trap where the decay will be monitored. We propose to use the WITCH apparatus for the decay. With the WITCH spectrometer at ISOLDE, a worldwide unique combination of a Penning ion trap and a retardation spectrometer, the energy spectrum of the recoil ions is measured. The mono-energetic recoils from EC decays will show up as a peak that is, in the mass region we will focus on at ISOLDE (i.e. between about A = 20 and A = 40), typically about 80 eV more energetic than the endpoint energy of the recoils from beta+ decays. With the about 1% energy resolution of the spectrometer, these energies will be clearly separable. A random and flat beta particle background will be present under the recoil energy spectrum, the amplitude of which can be determined in the energy region above the EC recoil peak. If the oscillation period scales inversely with the mass of the decaying isotope (as suggested in [3]) it may turn out to be closer to one second for the lighter isotopes. Suitable candidates should therefore have half-lives in the range of one second to one minute. Combining this with the production yields at ISOLDE leaves 19Ne and 35Ar as clear candidates. The layout of the beamline connecting the REX mass separator with WITCH must be done and sufficient vacuum conditions established to allow the multiply charged ions to survive for several seconds. The ions must furthermore be cooled [6, 7] before being let into the decay trap (various choices for the cooling procedure are currently being discussed). This proposed experiment at REXEBIS and WITCH would give important independent information on the process of nuclear electron capture in few-electron systems. Measurements could start as soon as preparatory efforts will have created the required experimental conditions and the presently ongoing beta-neutrino correlation measurements with WITCH will have yielded the physics results. [1] F. Bosch, in The Euroschool Lectures on Physics with Exotic Beams, Vol. I, ed. J. Al-Khalili, E. Roeckl, Lect. Notes. Phys. 651 (Springer, Berlin Heidelberg, 2004) p. 137 [2] Yu.A. Litvinov et al., Phys. Rev. Lett. 99 (2007) 262501 [3] Yu.A. Litvinov et al., Phys. Lett. B 664 (2008) 162 [4] H.J. Lipkin, hep-ph/0801.1465; A.N. Ivanov et al., nucl-th/0801.2121, nucl-th/0803.1289, nucl-th/0804.1311; M. Faber, nucl-th/0801.3262; H. Kleinert and P. Kienle, nucl-th/0803.2938 [5] C. Giunti, Phys. Lett. B 665 (2008) 92; H. Burkhardt et al., hep- ph/0804.1099 [6] J. Bernard et al., Nucl. Instr. and Meth. A 532 (2004) 224. [7] Z. Ke et al., Hyperfine Interact. 173 (2006) 103.Speaker: Nathal Severijns (IKS, K.U.Leuven)
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Exploring nuclei at the limit of REX-ISOLDE and HIE-ISOLDE using an active target detector 5mThe beams of exotic nuclei produced at REX-ISOLDE presently, and at HIE-ISOLDE in the future, offer a unique possibility of applying direct reaction methods for the study of the nuclear structure very far from stability. In light-ion transfer reactions, which are performed in inverse kinematics, the energy resolution degrades rapidly with the target thickness when a solid target is used, thus preventing measurements with the most exotic and weak ion beams. The active target concept allows to overcome this problem. It is a gaseous detector, where the nuclei of the detection gas are at the same time the target nuclei. The tracks of ionizing particles are recorded, allowing a precise reconstruction of the reaction kinematics in the whole gas volume. It ensures a high efficiency coupled with a low detection threshold. Typically, the target thickness is one to two orders of magnitude larger than a conventional solid target. Direct reactions can thus be studied using the weakest post-accelerated beams. At REX-ISOLDE these studied can be performed in the neutron-rich Ni region, and with HIE-ISOLDE they will be extended to the Pb region. Information on masses (from reaction Q-values) and single-particle structure of states (from reaction cross sections) can be combined with that obtained by other techniques (decay and laser spectroscopy, Coulomb excitation), fully exploiting the unique opportunities present at ISOLDE.Speaker: Riccardo Raabe (GANIL)Slides
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High-precision studies on pure species using Penning traps 5mIn recent years, atomic physics techniques have provided major input in answering fundamentally important questions not only in atomic, but also in nuclear physics and astrophysics, for example concerning the structure of nuclides, the stellar processes powering the universe, and the processes responsible for heavy-element formation. Penning traps lead the way in such applications, as proved by the pioneering ISOLTRAP setup located at ISOLDE and devoted to high-precision mass measurements by cyclotron frequency determination. Because of many advantages of a three-dimensional ion confinement in well controlled fields the traps are currently used in many other online applications, from beam cooling and bunching (e.g. REXTRAP at ISOLDE) to studies of beta-neutrino correlations for weak-interaction studies (e.g. WITCH at ISOLDE). In addition, due to its high-resolving power the Penning-trap mass spectrometers have recently found a novel application, that of isobaric and isomeric beam purification for decay-spectroscopy studies. Currently, Penning traps allow reaching mass uncertainty better than 10-8 (e.g. Mg-22), a resolving power approaching 10 million (Hg isotopes), for singly or maximum doubly ionized species with production rates as low as 1 ion/s (No-252) and half-lives down to 10 ms (Li-11). However, these impressive performances in precision, resolving power, sensitivity and applicability could not be achieved simultaneously for one specific species. This contribution aims at pushing the present limits of online mass spectrometry even further, thus allowing studies of nuclides and physics questions inaccessible before. One of the planned developments is closely connected to the HIE-ISOLDE project, and is devoted to production and the use of highly-charge ions at ISOLTRAP. Since highly charged ions have higher cyclotron frequencies the resolving power and the precision are increased; or vice versa, a high-precision mass measurement can be performed in a much shorter time compared to the case of singly charged ions. This development will allow accessing very neutron-rich nuclides relevant for the nucleosynthesis rapid neutron capture (r process) which have too short half-lives to be studied efficiently with the required relative precision below 10-7 (especially those in transitional regions, e.g. around Te-140 at N=88). Also, new ways of checking the unitarity of the CKM quark mixing matrix will be possible by deriving with high-precision the Ft values of the T = 1/2 mirror beta transitions, which allow determining the Vud matrix element. For this application, the masses of a dozen of nuclides, e.g. O-15, Na-21, Mg-23, Ca-39, have to be known with the relative precision better than 10-8. When coupled to the newly developed decay-spectroscopy station at ISOLTRAP, also their half-lives and branching ratios (necessary to obtain precise Ft-values) will be accessible with no systematic uncertainties due to beam contamination.Speaker: Magdalena Kowalska (CERN)
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Beta-NMR as a novel technique using radioactive beams for biophysical studies 5mBeta-NMR, which is a part of the future plans for HIE-ISOLDE project, online perturbed angular correlation (PAC) and distribution (PAD) of gamma rays are nuclear techniques which have not been applied in biochemistry yet. Therefore, within the next couple of years we would like to focus on applying beta-NMR method for studies on biological systems. The use of a combination of the radioactive ion beam facility, such as ISOLDE, with tilted-foil technique opens up the wide spectrum of isotopes which are interesting from the biological point of view and allows for measurements of spectroscopic properties (e.g. the electric field gradient) in proteins containing probe atoms or ions that are spectroscopically silent in most other techniques, due to their closed shells. Cu(I) would be an attractive starting point, as it is such a closed shell ion which is present in many proteins involved in for example electron transport and catalysis of redox reactions. With the use of this techinque the detection efficiencies are as much as 10 orders of magnitiude greater than with conventional NMR spectroscopy and therefore it would have a considerable impact in biological chemistry.Speaker: Lars Hemmingsen (University of Copenhagen)
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A new technique for charting the reordering of quantum states in exotic nuclei 5mRecent and forth coming improvements to ISOLDE as part of the HIE-ISOLDE project will open up new regions of the nuclear chart previously inaccessible to the nuclear community. While this work aims at increasing the intensity of the produced beams, the yields of the most exotic rare isotopes will still remain at the periphery of experimental scope. In order to uncover new physics in these exotic systems, new techniques must be developed to which will provide higher sensitivity and better background suppression. A new innovation in laser spectroscopy, which combines the high resolution and sensitivity of two well established techniques (Collinear laser spectroscopy and resonant ionization spectroscopy) has demonstrated an improvement in detection efficiency by more than three orders of magnitude. Through studying the hyperfine structure with laser spectroscopy it is possible to extract the nuclear observables, such as the spin and electromagnetic moments, without introducing model dependence. Such measurements therefore allow the evolution of nuclear quantum states to be unambiguously studied far from stability. This technique also offers the ability to suppress isobaric contamination by more than 6 orders of magnitude, facilitating the production of extremely clean ion beams for decay spectroscopy.Speaker: Kieran Flanagan (IPN-Orsay)
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Measurement of octupole collectivity in 220,222Rn and 222,224Ra using Coulomb excitation 5mThe long range octupole-octupole part of the nuclear force is pronounced in nuclei for which the Fermi level is situated between close-lying subshells with a difference of total and orbital angular momentums of 3 [1]. Among others, such a configuration space is realised in the mass region near Z=88 (2f7/2; 1i13/2) and N=136 (2g9/2; 1j15/2), where 220,222Rn and 222,224Ra are situated. Especially, 224Ra is predicted in various models to be the most octupole soft nuclei. In some models even a static octupole deformation is predicted for this particular nucleus. The octupole softness/deformation is reflected in the low-lying level schemes of these nuclei, which were established in multi-nucleon transfer reactions [2,3]. Hereby, extremely low excitation energies for the octupole excitations (224Ra: E(3−)=290.4 keV) as well as the characteristic odd-even parity staggering for the Yrast states for levels with spin > 5 were observed. However, so far, no experimental information for the B(E3,0+ -> 3−) strength, directly related to the degree of octupole deformation beta_3, is available. Recent Coulomb excitation experiments on neutron-deficient Hg isotopes [4] demonstrated the unique capabilities of the ISOLDE facility to produce heavy nuclei in a sufficient amount and post-accelerate them using the REX Linac. Thus for the first time spectroscopic information about the crucial E3 transition strength, exploiting the well-established Coulomb excitation technique, can be obtained. Beyond the scope of nuclear structure this experiment is a first step towards the search for CP-violating effects inherent in the nuclear force. In octupole deformed odd-mass isotopes the pear-shaped octupole deformation of the intrinsic mean field results in close-lying parity doublets of particle-core coupled states [5]. In presence of parity violating forces the opposite parity partner will mix and the induced Schiff moment in the body-fixed frame is enhanced proportional to the octupole deformation. This makes the odd-mass Ra isotopes to a more favorable experimental laboratory for the search for flavorless CP-violation, than the classical case 199Hg [6]. [1] P. A. Butler and W. Nazarewicz, Rev. Mod. Phys. 68, 349 (1996). [2] J. F. C. Cocks et al., Phys. Rev. Lett. 78, 2920 (1997). [3] J. F. C. Cocks et al., Nucl. Phys. A645, 61 (1999). [4] P. A. Butler et al., ISOLDE proposal IS452. [5] N. Auerbach et al., Phys. of Atom. Nucl. Vol. 70, No. 9, 1654 (2007). [6] J. Dobaczewski and J. Engel, Phys. Rev. Lett. 94, 232502 (2005).Speaker: Marcus Scheck (University of Liverpool)
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Future opportunities for emission channeling lattice location experiments using position-sensitive detectors and radioisotopes produced at HIE-ISOLDE 5mEmission channeling is a sensitive technique to measure the lattice location of radioactive impurities embedded in single crystals. It is based on the fact that charged particles from nuclear decay (alpha, beta-, beta+, conversion electrons, Auger electrons) experience channeling or blocking effects along major crystallographic axes and planes. The resulting anisotropic emission yield from the crystal surface characterizes the lattice site occupied by the probe atoms during decay and is measured using position-sensitive detectors. In particular we use - Si pad detectors (developed at CERN for the Compton camera project) and Si pixel detectors (under consideration are MediPix, TimePix) for the detection of electrons in the energy range > 40 keV up to several MeV (beta-, beta+, conversion electrons); - Charged Coupled Devices (CCDs) for the detection of very low-energy conversion electrons (< 40 keV) and Auger electrons; - Si detectors working with the principle of resistive charge division for the detection of alpha particles > 1 MeV. The main application of emission channeling is the lattice location of electrical, optical and magnetic dopants in semiconductors and oxides, e.g. electrical dopants in novel wide-band gap semiconductors such as ZnO, AlN, InN and diamond, transition metals and rare earths as magnetic impurities in spintronic materials, and rare earths as optical dopants in nitride semiconductors. In order to suppress dechanneling, the radioisotopes used for emission channeling experiments must be incorporated at a depth smaller than a few thousand Å below the surface of the sample, which is usually accomplished by means of low-energy ion implantation. The technique hence relies on the availability of a wide range of pure beams of radioisotopes at relatively high intensities (> 10E6 ions/s) but low energies (< 100 keV), for which ISOLDE is a unique facility. In particular, such beams have not been foreseen to be developed at SPIRAL or FAIR. Emission channeling experiments have successfully been demonstrated using ~65 different isotopes of a variety of elements including Li, Na, P, Ca, Fe, Cu, Ga, As, Se, Br, Rb, Sr, Ag, Cd, In, Sn, Sb, I, Xe, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tm, Yb, Lu, Hf, Au, Hg, Bi, Po, At, Rn, Fr and Ra. The beam intensity upgrade and the new target and ion source developments foreseen at HIE-ISOLDE, in particular the upgrade of the resonant laser ion source (RILIS) along with new ionization schemes and improved techniques for reducing surface-ionized radioisotopes, will make available pure radioactive beams for a number of elements which have been unavailable so far, or of insufficient purity or intensity. Among the radioactive probes which are feasible at HIE-ISOLDE in the near future are, e.g., 27Mg (9.5 min), 31Si (2.6 h), 35S (87.5 d), 65Ni (2.5 h), 75Ge (83 min), 124Sb (60 d), or 198Au (2.7 d). In the long run, we would like to encourage beam development of other promising emission channeling probes, in particular of the light elements, e.g., 8B (0.76 s), 15C (2.5 s), 16N (7.2 s), 19O (27 s), or 33P (25 d).Speakers: João Guilherme Correia (ITN, Lisbon), Ulrich Wahl (ITN, Lisbon)
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Discussion 5m
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Nuclear data at n_TOF for fundamental science and technological applications 20mThe n_TOF facility at CERN offers unique conditions worldwide for the measurement of neutron capture and neutron induced fission cross sections. The high neutron intensity and optimized duty cycle of the n_TOF neutron beam allows measuring the properties of highly radioactive species. Such is the case, for example, of the heavy elements with Z≥90, which are difficult to investigate and handle due to their α and β-activity and, in some cases, spontaneous fission. The nuclear structure of such nuclei is of great relevance for the improvement of nuclear models and can be investigated efficiently by neutron bombardment. Indeed, the most reliable experimental data on nuclear level density parameters concerns the s-wave neutron resonance spacing D0 at the neutron separation energy Sn obtained in neutron capture experiments. Such experiments have also a great relevance for the sustainability of the nuclear energy production and, more particularly, for finding a satisfactory strategy for the final management of the nuclear waste. The n_TOF facility has also proven to be a unique place for investigating the nuclear fission process from thermal energies up to several hundred MeV in one single experiment. Properties like the fragment charges and mass distributions, the energy released, the fragment deformations, and excitation energies, which are among the questions not yet fully understood theoretically, can be addressed at n_TOF. Furthermore, n_TOF can contribute as well to the nuclear energy applications, where it remains of major importance in to be able to estimate accurately the probability that fission occurs when competing with other decay channels or the number of neutrons released during the fission process. Many measurements made at CERN in the previous campaign had become the best world wide data available and are opening new levels of detail in the structure of the neutron induced reactions. Those measurements are at the same time improving our evaluation of the feasibility and performance of transmutation reactors proposed for the nuclear waste minimization before final disposal. Several expert groups of international organizations (NEA/OCDE, IAEA) had prepared compilations of nuclear data needs to approach the required precision to grant the feasibility of the new applications providing enhanced sustainability on the use of resources and reduction of final waste and environmental impact. The n_TOF Facility in its present form can strongly contribute to reach several of this requirements in the best worldwide conditions, both for Z≥90 and for isotopes of lower Z with low capture cross sections or significant radioactivity. Furthermore, modifications of the present experimental area and the construction of a new short flight path and the associated experimental area, for which conceptual designs are available, would enable the utilization of samples of additional isotopes only available or manageable in very small amounts, thus opening the way to achieve a large fraction of the previously quoted nuclear data needs. The coincidence between the isotopes, reactions and precision requirements from the fundamental nuclear physics and astrophysics needs, and the needs for industrial applications is remarkable. This coincidence has been the base for the strong and close cooperation of the corresponding researchers within the n_TOF experiments in the past and the motivation to propose its continuation in future experiments.Speaker: Enrique Gonzalez Romero (Centro de Investigaciones Energ. Medioambientales y Tecn. - (CIE)
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Neutron studies at n_TOF – a window to stellar evolution and nucleosynthesis 20mOnly the first three chemical elements have been produced immediately after the Big Bang. All the other elements (Z>3) were synthesized in stars and in stellar explosions. The quest for the origin of the elements is, therefore, strongly connected to the mechanisms governing the life and evolution of stars and to the nuclear reaction processes taking place in their interiors. By far, most of the isotopes found in Nature are the result of neutron induced reactions in stars. Initiated by Carlo Rubbia and his colleagues and supported as a European project, the construction of the CERN spallation neutron source n_TOF took place in 2000. In parallel, the n_TOF Collaboration was established with about 120 participants from more than 30 institutes, mostly from the EU, but also from the USA and Russia, to perform the first measurement campaign starting in 2002. The facility is characterized by the combination of high neutron flux, excellent time resolution, and very low backgrounds. What is unique, however, is the outstanding duty cycle of only one intense proton pulse every 2.4 seconds, which makes n_TOF the most luminous neutron source world-wide. These features are providing the ideal environment for neutron time-of-flight experiments covering the full energy range of astrophysical interest. The excellent performance of the facility is complemented by the use of the most advanced detection and data acquisition techniques for neutron cross section studies. In the present paradigm for the origin of the elements there are two neutron capture processes, each contributing about half of the abundances beyond Fe, which are named according to their characteristic time scales. The rapid neutron capture process (r process) is commonly associated with supernova explosions. In this case, neutron capture times are in the range of milliseconds, much faster than beta decays. Accordingly, the r-process path runs close to the neutron drip line and comprises a complex reaction network among exotic and extremely neutron-rich nuclei. In contrast, the slow neutron capture process (s process) takes place during the He burning stages of stellar evolution. In the s process, neutron capture times are much longer than typical half-lives for beta decay. The relevant nuclear physics input for quantitative studies of the s and r process is determined by the time scales: in the s process the resulting abundances are directly correlated with the neutron capture cross sections of the stable nuclei in the stability valley, whereas the r abundances depend mostly on the unknown beta decay rates on the r-process path as well as on the decay chains back to stability. Obviously, the nuclear input for the s process can be accurately determined in laboratory experiments. Under stellar conditions, neutrons are quickly thermalized in the hot and dense stellar plasma and effective reaction rates need to be derived from energy dependent neutron capture cross sections in the range from 100 eV to well above 500 keV, where n_TOF offers outstanding opportunities. Such measurements are also important for unstable isotopes, which are crucial for the analysis of branchings in the reaction path of the s process, as will be illustrated at the example of Sm-151. An extensive experimental plan for continuation of neutron capture cross section measurements for s-process studies and related nuclear astrophysics phenomena (e.g. cosmic clocks) will be presented. This plan is partly based on the present installation but also envisaging the enormous improvement, which could be obtained with a second experimental area at a shorter flight-path. A hundred times higher flux, a factor of ten improvement in the duty factor and strongly reduced backgrounds will allow for investigation of important cases, which are inaccessible so far. This includes studies on unstable samples in the nanogram range, which could be produced by future radioactive ion beams at CERN.Speaker: Alberto Mengoni (IAEA, Vienna)
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Antiproton Decelerator (AD) 500/1-001 - Main Auditorium
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Introduction 20mSpeaker: Ralf Lehnert (Universidad Nacional Autónoma de México)
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ASACUSA - future opportunities 15mThe presently approved physics programme of ASACUSA (Atomic Spectroscopy and Collisions using Slow Antiprotons) includes 1) precision laser and microwave spectroscopy of antiprotonic helium atoms (tests of CPT invariance), 2) atomic and nuclear cross section measurements at very low energies using the RFQD (~100 keV) and the MUSASHI ultra low energy (~100 eV) beamline, and 3) a measurement of the antihydrogen ground-state hyperfine splitting using an anti-Helmholtz (cusp) trap and/or a super-conducting radio-frequency trap. Of these, the laser spectroscopy of antiprotonic helium (in which we aim at an improvement of a factor >>10 over the current precision) and the antihydrogen ground-state hyperfine splitting measurements (under development) will both require about 10 weeks of beamtime for the next 5-10 years in order to reach their design precision goals. We expect to complete the “kinematically complete” collision experiments within the next 5-6 years by adding an electrostatic antiproton recycler downstream of the MUSASHI beam line (CERN-SPSC-2009-005 /SR-040). If the ELENA ring is constructed, both antiprotonic helium and antihydrogen spectroscopy will benefit from the increased beam intensity and brightness. In addition, the slow extraction of antiprotons from MUSASHI should also increase with ELENA (by about a factor 5 relative to the RFQD plus possibly another factor of 2 due to beam stability), which may make it possible to perform antiprotonic x-ray experiments [1] and other nuclear physics experiments [2] which have hitherto been impossible with the fast extracted antiprotons at the AD. [1] Gotta et al., in the abstract book. [2] Zmeskal et al., in the abstract book.Speaker: Ryugo Hayano (University of Tokyo)
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Prospects for tests of CPT using trapped antihydrogen in ALPHA 15mWe will discuss the future prospects for antihydrogen physics in the ALPHA experiment at the Antiproton Decelerator (AD). The primary goal of this experiment is to spectroscopically compare hydrogen and antihydrogen as a test of CPT invariance. We will identify the physics and technical challenges that must be addressed in order to achieve this goal, and we will suggest a progression of increasingly precise microwave and laser measurements that could be performed on antihydrogen during the advertised operational lifetime of the AD. We will also discuss the impact that construction of the proposed ELENA ring would have on the viability of these measurements.Speaker: Jeffrey Scott Hangst (Institute of Physics and Astronomy - University of Aarhus)
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Antihydrogen Potential and Challenges for CERN'S Unique Low Energy Antiprotons 15mCERN not only leads the world in "high energy" physics. It has long also distinguished itself by pursuing fundamental particle physics at lower energy scales when the laboratory possesses the unique capability to do so. CERN introduced the world's lowest energy antiprotons at 5 MeV. Experimenters at LEAR and then the AD introduced particle traps to lower the energy by up to an additional ten orders of magnitude in energy, making it possible to compare q/m for the antiproton and proton at the 9 parts in 10^{10} level. Now, antihydrogen is being formed by two different methods at the AD. The expectation is that antihydrogen spectroscopy will provide comparisons of antihydrogen and hydrogen at much higher precisions. The lowest-ever (1.2 K) electron and positron temperatures recently realized bode well for making colder antihydrogen atoms,. These are needed to realize the goal of trapping antihydrogen atoms in magnetic traps that have been demonstrated at the AD. The future is challenging and exciting. The long term goal, for which the AD was constructed, is extremely accurate laser spectroscopy of antihydrogen atoms. Steady progress continues on the needed laser systems needed for cooling and spectroscopy, and a second generation of magnetic trap is under construction. Even lower plasma temperatures seem possible. On the side, it seems feasible to use a single antiproton to measure the antiproton magnetic moment a million times more accurately. An upgraded AD, able to deliver many more antiprotons at lower energies to traps, would speed the progress.Speaker: Gerald Gabrielse (Harvard University)
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AEGIS: measurement of the gravitational interaction of antihydrogen 10mThe experimental program of AD-6 has been described as part of the documents submitted to the SPSC [1]. In those documents, this program extends at least to 2013, which should allow us to achieve the main physics goal of the experiment - a measurement to 1% of the gravitational interaction of antimatter. Our program however is broader and longer-term than that. The attached timeline of the experiment covers the activities we intend to carry out over the next decade.Speaker: Daniel Comparat (Lab. Aimé Cotton, Orsay)
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An Experiment to Measure Antihydrogen Free Fall 10mIn our Letter of Intent of 2007 [1], we expressed our interest to use the CERN antiproton beam for a measurement of the acceleration of antihydrogen atoms in the gravity field of the Earth. The first step is to produce the Hbar+ ion, which can be manipulated and cooled down to µK temperatures (i.e. m/s velocities) according to Walz and Hänsch [2]. The excess positron can then be laser detached in order to recover the neutral and slow Hbar atom. Production involves a dense target made of positronium through the charge exchange process pbar + Ps → Hbar + e-, followed by Hbar + Ps → Hbar+ + e-. The antiprotons must be accumulated from the AD into a Penning trap such as developed in the ASACUSA collaboration. The high number of antiprotons needed would also benefit from an increased flux at low energies such as envisaged in the ELENA project. The positronium target is obtained by dumping 10**10 to 10**11 positrons, also from a Penning trap, onto a material that converts them into Ps. We have fabricated nanoporous SiO2 layers and measured their high efficiency to produce slow Ps [3]. An intense positron source is necessary to produce the required Ps density. We are developing a positron source based on a small electron linac, which is presently being commissioned at Saclay. Such a source could be placed in the AD hall and should produce of the order of 10**8 slow e+ per second. Distribution of these slow positrons to other experiments could be considered. [1] A new path to measure antimatter free fall, P. Pérez et al. CERN-SPSC-2007-038, CERN-SPSC-I-237, December 2007. [2] A Proposal to Measure Antimatter Gravity Using Ultracold AntihydrogenAtoms, J. Walz and T. Hänsch, General Relativity and Gravitation 36 (2004) 561. [3] Positronium reemission yield from mesostructured silica films, L. Liszkay et al., Appl. Phys. Lett. 92, 063114 (2008).Speaker: Patrice PEREZ (IRFU, CEA-Saclay, France)
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Measurement of the Spin–Dependence of the pbarp Interaction at the AD–ring 10mWe propose to use an internal polarized hydrogen storage cell gas target in the AD–ring to determine for the first time the two total spin–dependent pbarp cross sections σ1 and σ2 at antiproton beam energies in the range from 50 to 450 MeV [1]; a Technical Proposal will be submitted at the beginning of April to the SPS committee at CERN. The data obtained are of interest in itself for the general theory of pbarp interactions and will provide a first experimental characterization of the spin-dependence of the nucleon-antinucleon potential. They are furthermore required to define the optimum parameters of a dedicated Antiproton Polarizer Ring (APR) that shall be used to feed a double–polarized asymmetric pbarp collider with polarized antiprotons. Such a machine has been recently proposed by the PAX collaboration for the new Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt, Germany [2]. The availability of an intense beam of polarized antiprotons will provide access to a wealth of single– and double–spin observables, thereby opening a new window to QCD spin physics. A recent measurement at COSY revealed that ep spin–flip interactions provide insufficiently small cross sections to depolarize a stored proton beam [3]. This measurement rules out the use of polarized positrons to polarize an antiproton beam by e+pbar spin–flip interactions. Our approach to provide a beam of polarized antiprotons is based on spin filtering using an internal polarized hydrogen gas target — a method known to work for stored protons [4]. We are aiming to improve intensities of polarized antiproton beams by at least ten orders in magnitude compared to what has been achieved hitherto. Provided antiproton beams with a polarization around 20% can be obtained with the APR, the antiproton machine at FAIR (the High Energy Storage Ring) could be converted into a double–polarized asymmetric pbarp collider by installation of an additional COSY–like ring. In this setup, antiprotons of 3.5 GeV/c collide with protons of 15 GeV/c at c.m. energies of sqrt(s) ~ srqt(200) GeV with a luminosity in excess of 10^31 cm−2s−1. The PAX physics program proposed for FAIR [2] has been highly rated by various committees [5]. It includes foremost a first direct measurement of the transversity distribution of the valence quarks in the proton, and a first measurement of the moduli and the relative phase of the time–like electric and magnetic form factors GE,M of the proton. References [1] Letter–of–Intent for Measurement of the Spin–Dependence of the pbarp Interaction at the AD-Ring, PAX Collaboration, spokespersons: P. Lenisa (Ferrara University, Italy) and F. Rathmann (Forschungszentrum Juelich, Germany), available from http://lanl.arxiv.org/abs/nucl-ex/0512021. The proposals of the PAX collaboration can be found at the PAX website at http://www.fz-juelich.de/ikp/pax. [2] Technical Technical Proposal for Antiproton–Proton Scattering Experiments with Polarization, PAX Collaboration, spokespersons: P. Lenisa (Ferrara University, Italy) and F. Rathmann (Forschungszentrum J¨ulich, Germany), available from http://lanl.arxiv.org/abs/hep-ex/0505054. An update of the proposal is available from the PAX website at http://www.fz-juelich.de/ikp/pax. [3] D. Oellers et al., Polarizing a stored proton beam by spin flip?, accepted for publication in Phys. Lett. B, http://xxx.lanl.gov/abs/0902.1423. [4] F. Rathmann et al., Phys. Rev. Lett. 71, 1379 (1993). [5] Reports from different committees can be found in the News section of the PAX website at http://www.fz-juelich.de/ikp/pax.Speakers: Frank Rathmann (Forschungszentrum Juelich), Paolo Lenisa (Universita di Ferrara and INFN)
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Double-strangeness production with antiprotons at the AD 10mOne of the outstanding fundamental problems in hadron physics today is the question of the origin of the large hadron masses made up of light quarks. A possible way to gain information is to study how the meson mass changes in a nuclear medium. The mass shift of a meson in a nuclear medium will provide evidence of the partial restoration of spontaneous broken chiral symmetry. The use of antiprotons for the production of double-strangeness was recently discussed by Weise and Kienle [Int. Jour. Mod. Phys. A 22 (2007) 365] and indeed, it would be very challenging to produce and study such "double-strange nuclei" in the view of the prediction of Akaishi and Yamazaki [Phys. Lett. B 535 (2002) 70] that double-antikaon bound nuclear systems with strangeness (S = -2) will be formed with binding energies up to 200-300 MeV. Such binding energies might result in an increase of the average density to more than 3 times the average nuclear density. If such dense systems really exist they will indeed represent ideal conditions to investigate how the spontaneous and explicit symmetry breaking pattern of low-energy QCD changes in a dense nuclear medium. First results on events with the production of two K+ mesons were reported by the DIANA collaboration [Nucl. Phys. A 558 (1993) 361] and recently a reanalysis of part of the OBELIX data measured at LEAR [Nucl. Phys. A 797 (2007) 109] was published, giving a probability of ~10-4 for the production of two K+ mesons. Based on this observation we plan a dedicated experiment to search for double strange nuclear cluster formation following antiproton annihilation at rest in various targets using missing mass and invariant mass spectroscopy. One possible target might be helium, where the antiproton is stopped and a double strange tri-baryon system is produced: pbar +4He → K+ + K+ + pnnK-K- To investigate such systems a detector system with three different detector components are planned with almost 4π coverage and excellent particle identification and spectroscopy capabilities. As central detector, an essential part of this experimental setup, a Time Projection Chamber (TPC) for charged particle tracking is foreseen. Within a Joint Research Activity of the FP7 program HadronPhysics 2, the study and development of a similar prototype TPC is already planned. A first experiment could be performed at the CERN/AD using the MUSASHI trap (ASACUSA), which provides slow extraction. In future more detailed studies are planned at FLAIR.Speaker: Eberhard Widmann (Stefan Meyer Institute for Subatomic Physics)
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Discussion 10m
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Buffet dinner (remember to wear your badge) 3h Restaurant 1 (private)
Restaurant 1 (private)
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Test Beams & Irradiation facilities 500/1-001 - Main Auditorium
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Possible future developments 500/1-001 - Main Auditorium
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Introduction 5mSpeaker: Michelangelo Mangano (CERN)
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Solving the neutrino mass and baryon asymmetry puzzles with experiments at SPS 20mThe Standard Model cannot explain neutrino masses and oscillations, does not provide a candidate for dark matter particle and does not explain why the universe contains more matter than antimatter. A unified solution of these problems appears if the neutral fermion sector of the Standard Model is constructed in analogy with the structures we have in quarks or in charged leptons. Namely, every left-handed fermion can be required to have its right-handed counterpart. The properties of the new particles - relatively light neutral leptons, can be severely constrained by existing experiments and cosmology. Their mass is expected to be in a few GeV region, while their couplings to ordinary leptons are bounded both from above and from below. We will argue that the dedicated experiments with the use of intensive SPS and PS beams can provide an excellent opportunity for sensitive searches for these new particles.Speaker: Mikhail Shaposhnikov (EPFL Lausanne)
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Mono-energetic electron and gamma-ray beams at CERN. 20mA new method of delivering a monochromatic electron beam to the LHC interaction points is proposed. This method could enlarge the scope of the research programme of the present LHC detectors, by including the research programme of the electron-proton and electron-ion collisions. The carrier of the electron beam, over the full acceleration cycle, is the heavy ion beam. The storage of such a hybrid beam, in the LHC storage rings, could lead to a new exiting possibility of forming a mono-energetic, high-intensity, and highly-collimated gamma-ray beam at CERN - with higher efficiency than the present inverse-Compton-scattering gamma-ray sources. It could open up many new possibilities for basic research and applications, including photo-transmutation of nuclear isotopes, gamma-ray transmission radiography, cancer therapy and positron beam production.Speaker: Mieczyslaw Krasny (Universites de Paris VI et VII)
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Fixed target charmonium production with proton and lead beams at LHC 10mThe possibility to study the production of J/ψ mesons in the fixed target experiments with proton and lead beams at LHC has been investigated. At SPS energies the normal nucleus suppression of J/ψ in proton-nucleus collisions and anomalous suppression in central lead-lead collisions was observed in NA50 experiment. The anomalous suppression for central indium-indium events at SPS was confirmed by NA60 experiment. PHENIX experiment at RHIC shows that the J/ψ suppression in Au-Au and Cu-Cu collisions at 200 GeV in nucleon-nucleon centre of mass system is of the same order as the suppression at SPS energies. There is no theoretical models now that could reproduce all the data. Future experiments at much higher energies at ALICE, LHC could produce the charmonium and bottomonium families and possible suppression pattern can be studied. However an energy interval between SPS, RHIC and LHC is very important to study the mechanism of quarkonium production and suppression, to investigate medium effects and conditions for Quark Gluon Plasma formation. We suggest to plan at LHC fixed target experiment for charmonium production at the energy range between SPS and RHIC in p-A and A-A collisions with planning proton beam at T=7 TeV (sqr s = 114.6 GeV) and Pb beam at 2.75 TeV (sqr s = 71.8 GeV). This is unique possibility to clarify the mechanism of charmonium, J/ψ and ψ' production, to separate two possibilities: i): hard production and suppression in QGP and/or hadronic dissociation or ii): hard production and secondary statistical production with recombination, since the probability of recombination decreases with decreasing energy of collision in thermal model. As it was already used for the experiment on a collider with a fixed target at HERA-B, the target in the form of thin ribbon could be placed around the main orbit of LHC. The life time of the beam is determined by the beam-beam and beam-gas interactions. Therefore after some time the particles will leave the main orbit and will interact with target ribbon. So for the fixed target experiment at LHC only halo of the beam will be used. Hence no deterioration of the main beam will be introduced. The experiments at different interaction points will not feel any presence of the fixed target. The geometrical acceptances for the J/ψ production, luminosity and counting rate estimations for measurement at LHC with the fixed target are calculated and discussed.Speaker: Natalia Topilskaya (Institute for Nuclear Research (INR)-Russian Academy of Sciences)
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Measurement of magnetic moments of charmed baryons using an extracted beam at LHC 10mHigh energy external beams at LHC offer unique opportunities for specialized experiments. Besides providing beams of charmed mesons which may be used for total charm cross section measurements one such experiment is the determination of the magnetic moment of charmed baryons. We will present the physics and a possible technique for such a measurement, which constitutes a challenge in experimental physics. These experiments are based on crystal channeling of polarized charmed baryons at TeV energies allowing to observe sufficient spin rotation for a measurement of their magnetic moment.Speaker: Stephan Paul (Physik Department - Technische Universitaet Muenchen)
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Proposed Application of the LHC and SPS to Study High Energy Density Matter and Plasma Physics 10mThe Large Hadron Collider (LHC) will generate two counter rotating 7 TeV proton beams, each containing 362 MJ energy that is sufficient to melt 500 kg copper. Safety of operation is an extremely important issue when working with such powerful beams. Any uncontrolled release of a small fraction of the beam energy can cause considerable damage to the equipment. A worst case scenario could be that the entire beam is lost at a given point. In order to study the consequences of such an accident, extensive numerical simulations have been carried out over the past few years. First, the energy loss of the 7 TeV protons is calculated using the FLUKA code [1] that is a fully integrated Monte Carlo particle simulation model capable of treating all components of the particle cascades, up to multi-TeV energies. This data is used as input to a 2D computer code, BIG2 [2], that is used to study the hydrodynamic and thermodynamic response of a solid copper cylindrical target that is facially irradiated with the full LHC beam. It has been found that the LHC protons will penetrate about 35 m in solid copper [3] and the target will be severely damaged. A very interesting outcome of this work has been that the target material will be converted into a huge sample of High Energy Density (HED) matter. In fact the specific energy deposition by the LHC beam in the target is of the same order as is expected at a dedicated facility, FAIR (Facility for Antiprotons and Ion Research) [4-6]. It has therefore been proposed that HED physics studies could be an additional application of the LHC [7]. It is also interesting to note that according to our simulations, the SPS has also the potential to generate HED states in matter. References [1] A. Fasso et al., "FLUKA: A Multi-Particle Transport Code", CERN-2005-10, INFN/TC-05/11, SLAC-R-773 (2005). [2] V.E. Fortov et al., Nucl. Sci. Eng. 123 (1996) 169. [3] N. A. Tahir et al., J. Appl. Phys. 97 (2005) 083532. [4] W.F Henning, Nucl. Inst. Meth. A 214 (2004) 211. [5] N.A. Tahir et al., Phys. Rev. E 63 (2001) 016403. [6] N.A. Tahir et al., High Energy Density 2 (2006) 21. [7] N. A. Tahir et al., Phys. Rev. Lett. 94 (2005) 135004.Speaker: Naeem Tahir (GSI Darmstadt)
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Proton Driven Plasma Wakefield Acceleration (PDPWA) 10mA new scheme of plasma wakefield accelerator was recently proposed (A. Caldwell et al., arXiv, acc-ph: 0807.4599). The idea is to use existing high-energy proton bunches to drive a plasma wakefield. The strong plasma field then accelerates a trailing electron bunch to high energies. 2D and 3D Particle-in-Cell simulations show that a proton bunch with particle energy of 1 TeV, a bunch length of 100 µm, and 1011 protons can accelerate an electron bunch to beyond 500 GeV in a single plasma channel. A key element in realizing PDPWA is the production of a very short proton bunch. This is currently under study and recent results will be presented. A proof-of-principle experiment based on PDPWA is then proposed for consideration as a future CERN project. A proton bunch extracted from the PS or SPS would first be compressed through conventional magnetic compression and then enter into the plasma channel to exciting the plasma wakefield. In a first stage, the properties of the plasma wave could be studied without an electron bunch. Upon success of this stage, an electron bunch could be injected in the plasma and acceleration gradients demonstrated. Properties of the electron bunch would be studied in detail. A general facility for plasma wakefield studies could be envisaged.Speaker: Guoxing XIA (Max-Planck-Institute fuer Physics)
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Discussion 5m
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New Proton drivers at CERN 500/1-001 - Main Auditorium
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Requirements on the proton source for future neutrino facilities 10mAll proposed future options for second generation neutrino facilities that have been considered in Europe request a high power proton accelerator to produce the neutrino parents. This is in particular the case for those studied in the EUROnu design study. The more specific requirements in terms of proton energy and time structure are described. -- for the first option studied in EUROnu, a conventional neutrino superbeam, the physics performance of the project requires typically a 4 MW proton driver with a pulse rate of the order of 50 Hz. To minimize the energy consumption by the corresponding hadron collecting system and increase its lifetime, the proton pulse duration must remain as short as possible and not exceed 5 microseconds. -- the specification for the Neutrino Factory proton driver is that it will deliver a beam power of 4 MW at an energy of 10±5 GeV in one to three bunches of 2 ns duration at a repetition rate of 50 Hz. This challenging specification can be met using a super-conducting linac feeding a system of accumulator and compressor rings or by a novel non-scaling FFAG. - finally for the beta-beams, the use of spallation neutrons for indirect production of beta emitters 6He and 8Li is a valuable option within the capability of a superconducting proton linac. Increasing the production ability of other important candidates for beta beams, such as 18Ne, which is today insufficient, is actively pursued within the EURISOL program. It is noted finally that challenging muon physics, such as search for rare decays predicted in supersymmetric theories in particular, can be performed at a high intensity proton accelerator taking advantage of the flexible time structure of the SPL, especially with an accumulator ring.Speaker: Alain Blondel (Departement de Physique Nucleaire et Corpusculaire (DPNC))
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Concluding remarks - Physics 10mSpeaker: Sergio Bertolucci (CERN)
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