Search

In ultra-relativistic heavy-ion collisions a great variety of (anti-)(hyper-)nuclei are produced, namely deuteron, triton, 3He, 4He, hypertriton ( Λ 3 H ) and their antiparticles. The ALICE experiment is the most suited to investigate the production of (hyper-)nuclei at the LHC, thanks to an excellent particle identification and low-material budget detectors. Recent results on (hyper-)nuclei production as a function of transverse momentum (pT) and charged particle multiplicity (dN ch/d η ) in Pb–Pb collisions are presented. The evolution of the production yields with the system size is also shown, via comparison to the results obtained in small collision systems, like pp and p–Pb. The results on the production of (hyper-)nuclei are also compared with the predictions based on a naive coalescence approach and the statistical hadronization models. Furthermore, the latest and currently most precise measurement of the hypertriton lifetime is presented. It is compared with results obtained by different experimental techniques and with theoretical predictions.

We extract the valence part of the nucleón Boer-Mulder (BM) function from the new COMPASS data on the unpolarized cosϕh and cos2ϕh asymmetries in SIDIS on deuteron for producing the hadron h and its antiparticle h ¯ at azimuthal angle ϕh . Our results, obtained with only standard assumption of factorization of the xB (zh ) and transverse momentum dependences, differ significantly from the presently published data on the BM function, obtained using a model assumption of proportionality to the better known Sivers function. This suggests that the published results on the BM function should be reconsidered.

In direct accordance to the overall relevant experimental demonstrations, we represent the charged pion π- as a heavy electron h - in precessional-orbital (P-O) motion at essentially the light speed c about υ ¯ e -orbit of a normal at quantised angle π − θ1/2 = − arccos ( 1 / 3 ) to the z axis. h - is the level N = 1 oscillation of charge −e and its electromagnetic radiation originally generated in the weak potential field of another particle. The P-O kinetic energy current and two additional opposite ones created upon π- decay represent confined neutrinos υ ¯ e , υ ¯ μ , υ μ . The muon µ- is a xy-projected h - in two superposing P-O motions along υ ¯ e − , υ μ - orbits of normals at angles π − θ1/2, θ1/2 to z. The µ- (rest) mass is a geometric projection of the reduced π- mass, M μ = ( M π − M υ μ ) cos θ 1 / 2 = 105.86 MeV . The µ- mass is fundamentally predetermined by the mixed two states ml = −1, +1 of level n = 2 of a double heavy positronium in the CM frame produced in a relativistic e -, e + collision, and is ab initio predicted to be M μ − = ( 3 4 2 α + 1 ) M e = 105.549 MeV , where α = e 2 / 4 π ∈ 0 ℏ c . The un-projected n = 2 level gives the bound π- mass containing a friction term O η , M π + O η = ( 2 α + 1 ) M e = 140.525 MeV . Their antiparticles π+, µ+ and the tauons τ∓ can be similarly represented. The remaining unstable elementary particles can be constructed as composites of two or more single charged ones in certain spatial quantised P-O motions.

Neutrinoless double beta decay (0v\b{eta}\b{eta}) is considered the best potential resource to access the absolute neutrino mass scale. Moreover, if observed, it will signal that neutrinos are their own anti-particles (Majorana particles). Presently, this physics case is one of the most important research "beyond Standard Model" and might guide the way towards a Grand Unified Theory of fundamental interactions. Since the 0v\b{eta}\b{eta} decay process involves nuclei, its analysis necessarily implies nuclear structure issues. In the NURE project, supported by a Starting Grant of the European Research Council (ERC), nuclear reactions of double charge-exchange (DCE) are used as a tool to extract information on the 0v\b{eta}\b{eta} Nuclear Matrix Elements. In DCE reactions and \b{eta}\b{eta} decay indeed the initial and final nuclear states are the same and the transition operators have similar structure. Thus the measurement of the DCE absolute cross-sections can give crucial information on \b{eta}\b{eta} matrix elements. In a wider view, the NUMEN international collaboration plans a major upgrade of the INFN-LNS facilities in the next years in order to increase the experimental production of nuclei of at least two orders of magnitude, thus making feasible a systematic study of all the cases of interest as candidates for 0v\b{eta}\b{eta}.

The optical-gravitational methods for distinction between photons and antiphotons (galaxies, emitting photons and antigalaxies, emitting antiphotons) in the proposed hypothesis of totally gravitationally neutral (TGN)-Universe are considered. These methods are based on the extension of the earlier proposed the gravitationally neutral Universe concept, including now gravitational neutrality of vacuum. This concept contains (i) enlarged unbroken baryon-like, charge, parity and time and full ±M gr gravitational symmetries between all massive elementary particles–antiparticles, including (ia) ordinary matter (OM)–ordinary antimatter (OAM), (ib) dark matter (DM)–dark antimatter (DAM) and (ii) the resulting gravitational repulsion between equally presented (OM+DM)-galactic and (OAM+DAM)-antigalactic clusters, what spatially isolates and preserves their mutual annihilations in the large-scale TGN-Universe. It is assumed the gravitational balance not only between positive and negative gravitational masses of elementary particles and antiparticles, but also between all massless fields of the quantum field theory (QFT), including the opposite gravitational properties of photons and antiphotons, etc, realizing the totally gravitationally neutral vacuum in the QFT. These photons and antiphotons could be distinguishable optically-gravitationally, if one can observe a massive, deviating OM-star or a deviating (OM+DM)-galaxy from our galactic group, moving fast enough on the heavenly sphere, crossing the line directed to spatially separated far-remote galactic clusters (with the visible OM-markers, emitting photons) or antigalactic cluster (with the visible OAM-markers, emitting antiphotons). The deviations and gravitational microlensing with temporarily increased or decreased brightness of their OM and OAM rays will be opposite, indicating the galaxies and antigalaxies in the Universe.

Kinetic processes taking place after injection of antiprotons in cold positron cloud are discussed. Mixture of antiparticles is considered as low temperature non neutral weakly coupled plasma. Simple estimations of energy of antihydrogen atoms that may be formed due to three body recombination in the system are made. Dependence of atom energy on initial particles temperatures and influence of strong confining magnetic field are discussed.

Recent experiments in high enegry cosmic ray physics, PAMELA and AMS-02, excite a new interest to the mechanisms of generation of galactic antiparticles. In spite of the fact that global picture coincides with the predictions of the standard model, there are some black spots stimulating scientists to involve into research a particularly new physics like dark matter. In the present work, we make an attempt to estimate the impact of standard neutrino processes into the total flux of secondary antiprotons detected by contemporary experiments.

We are going to show that any conventional decaying dark matter model, providing an explanation of cosmic antiparticle excess observed by PAMELA and AMS-02, inevitably faces the contradiction with isotropic diffuse gamma-ray background, measured by FERMI/LAT.

The hypothesis of antigravitational interaction of elementary particles and antiparticles is applied to the simple two-component hydrodynamic model Λ-CDM (Lambda cold-dark matter) with gravitational repulsion and attraction. An increase in the Jeans instability rate, the presence of antiscreening, and the dominant role of the gravitational repulsion as a possible mechanism of spatial separation of matter and antimatter in the Universe are shown, as well as the observable acceleration of far galaxies. The sound wave is found for the two-component gravitational-antigravitational system. The suggested approach permits to reestablish the idea about baryon symmetry of the Universe, causing its steady large-scale flatness and accelerated Universe expansion.

We report on the development of an energy-tunable positronium beam apparatus at Tokyo University of Science. The positronium beam is generated using the photodetachment of the positronium negative ion, a bound state of one positron and two electrons. Positronium negative ions are efficiently emitted from a Na- coated tungsten surface by bombardment with a slow positron beam. The intermediate-energy positronium beam produced in this fashion can be used for fundamental studies of antimatter-matter interactions with solid surfaces.

We calculate pair production from bremsstrahlung as a classical effect in Stueckelberg-Horwitz electrodynamics. In this framework, worldlines are traced out dynamically through the evolution of events xμ(τ) parameterized by a chronological time τ that is independent of the spacetime coordinates. These events, defined in an unconstrained 8D phase space, interact through five τ-dependent gauge fields induced by the event evolution. The resulting theory differs in its underlying mechanics from conventional electromagnetism, but coincides with Maxwell theory in an equilibrium limit. In particular, the total mass-energy-momentum of particles and fields is conserved, but the mass-shell constraint is lifted from individual interacting events, so that the Feynman-Stueckelberg interpretation of pair creation/annihilation is implemented in classical mechanics.We consider a three-stage interaction which when parameterized by the laboratory clock x0 appears as (1) particle-1 scatters on a heavy nucleus to produce bremsstrahlung, (2) the radiation field produces a particle/antiparticle pair, (3) the antiparticle is annihilated with particle-2 in the presence of a second heavy nucleus. When parameterized in chronological time τ, the underlying process develops as (1) particle-2 scatters on the second nucleus and begins evolving backward in time with negative energy, (2) particle-1 scatters on the first nucleus and releases bremsstrahlung, (3) particle-2 absorbs radiation which returns it to forward time evolution with positive energy.

International audience; The Gravitational Behaviour of Antihydrogen at Rest experiment - GBAR - is designed to perform a direct measurement of the weak equivalence principle on antimatter by measuring the acceleration ((g) over bar) of antihydrogen atoms in free fall. Its originality is to produce (H) over bar (+) ions and use sympathetic cooling to minimize the initial velocity. These ions are produced using charge exchange reactions with a dense positronium cloud, created by an intense pulse of electron-linac-produced positrons that are accumulated in a Penning-Malmberg trap.

Total reflection high-energy positron diffraction (TRHEPD) promises to be an ideal technique for determining the atomic arrangement of solid surfaces. TRHEPD makes full use of the total reflection of the positron beam from a surface in reflection high-energy positron diffraction (RHEPD), the positron counterpart of reflection high-energy electron diffraction (RHEED). Owing to the development and use of a brightness-enhanced intense positron beam at KEK, it is now possible to obtain clear TRHEPD patterns. It is shown that the TRHEPD pattern from a Si(111)-7×7 reconstructed surface for the total reflection condition does not contain contributions from atoms in the bulk.

The effects of proton irradiation on Chinese domestic reactor pressure vessel (RPV) A508-3 steels have been investigated by variable energy positron annihilation spectroscopy. The samples were irradiated using 110 keV protons at doses ranging from 0.2 to 2.0 ×1017 cm−2 at room temperature. Defect profiles were analyzed by measuring the S parameter as a function of incident positron energy from 0.25 to 26keV, corresponding to mean depths of up to ~940nm. It is interesting to note that the S-parameter increases rapidly with increasing dose, which implies that matrix damage has a direct relation to dose-dependent effects in microstructural evolution.

Positron annihilation has been applied to study a series of non-stoichiometric pollucite samples with the composition Cs(1−x)Al(1−x)Si(2+x)O6 for x = 0.0–0.25. Lifetime results showed a monotonic increase in the o-Ps lifetime and intensity as the Cs concentration was reduced. This is consistent with literature suppositions that vacancies are created as the Cs content is reduced.

Positron lifetime spectroscopy was used to study multi-wall carbon nanotubes. The measurements were performed in vacuum on the samples having different average diameters. The positron lifetime values depend on the nanotube diameter. The results also show an influence of the nanotube diameter on the positron annihilation intensity on the nanotube surface. The change in the annihilation probability is described and interpreted by the modified diffusion model introducing the positron escape rate from the nanotubes to their external surface.

Spin-polarized positron annihilation spectroscopy will be useful in studying spintronics materials. Here, we summarize some fundamental aspects of this method for the future spintronics studies.

The Mg-Zn-Y alloys with long period stacking ordered (LPSO) structures have been studied by positron annihilation lifetime (PAL), coincidence Doppler broadening (CDB) and atom probe tomography (APT). The positron lifetime for all the Mg-Zn-Y alloys is in a range of 221~225 ps, very close to the positron lifetime for pure Mg bulk, 222 ps. Low temperature measurements of the positron lifetime also give no evidence for shallow positron trapping sites in the LPSO phases. The CDB shows that most of the positrons are annihilated with electrons of Mg. These results suggest that sub-nano scale open volumes, which were expected to exist in the Zn/Y enriched layers synchronized with stacking faults of the LPSO phases by the first principles calculations, are not present.

Time-of-flight spectra for the ortho-positronium emitted from clean and Na-coated tungsten surfaces have been measured using the pulsed slow positron beam at KEK-IMSS slow positron facility. Emission efficiency of positronium from the Na-coated sample was found to be several times greater than that from uncoated tungsten surfaces.

Reflection high-energy positron diffraction (RHEPD) is the positron counterpart of reflection high-energy electron diffraction (RHEED). Owing to the positive charge of the positron, RHEPD provides a powerful tool with which to determine the structure of the first surface layer. We have been investigating important surface systems concerning their unique electric and magnetic properties and also phase transition phenomena using positron beams (flux: 103~104 e+/sec) with 22Na sources. Currently, we are developing a new RHEPD apparatus with a bright and intense positron beam (flux: 105 e+/sec) based on the LINAC at the Slow Positron Facility, KEK. Here, we summarize the past results and the future prospects of the RHEPD study in the surface science.

This work is devoted to the calculation of the fluxes of the atmospheric antiprotons and antineutrons generated at various atmospheric depths, lying from 5 to 300 g/cm2. The simulations are carried out with the help of CORSIKA package involving a primary energy spectrum starting at the energy threshold of antiparticle production up to 1 PeV. The obtained results match well with the atmospheric antiproton spectra measured by the BESS-2001 experiment in the kinetic energy range 1-3 GeV.

Vibrational Feshbach resonances in annihilation are observed when a positron attaches to a molecule. For many molecules, the annihilation rates are enhanced due to intramolecular vibrational redistribution (IVR) and other effects, such as combination and overtone modes, are observed. Experiments to investigate these effects are presented and outstanding issues are discussed.

Neutrinoless Double Beta Decay ($0\nu\beta\beta$) is presently the only known experiment to distinguisch between Dirac neutrinos, different from their antiparticles, and Majorana neutrinos, identical with their antiparticles. In addition $0\nu\beta\beta$ allows to determine the absolute scale of the neutrino masses. This is not possible with neutrino oscillations. To determine the neutrino masses one must assume, that the light Majorana neutrino exchange is the leading mechanism for $0\nu\beta\beta$ and that the matrix element of this transition can ba calculated reliably. The experimental $0\nu\beta\beta$ transition amplitude in this mechanism is a product of the light left handed effective Majorana neutrino mass and of this transition matrix element. The different methods, Quasi-particle Random Phase Approximation (QRPA), Shell Model (SM), Projected Hartree-Fock-Bogoliubov (PHFB) and Interacting Boson Model (IBM2) used in the literature and the reliability of the matrix elements in these approaches are reviewed. In the second part it is investigated how one can determine the leading mechanism or mechanisms from the data of the $0\nu\beta\beta$ decay in different nuclei. Explicite expressions are given for the transition matrix elements. is shown, that possible interference terms allow to test CP (Charge and Parity conjugation) violation., Comment: Contribution to the EPS conference in Eilath: "Nuclear Physics in Astrophysics 5." April 3rd to 8th. 2011

The ASACUSA collaboration at the Antiproton Decelerator of CERN is planning to measure the ground-state hyperfine splitting of antihydrogen using an atomic beam line, consisting of a cusp trap as a source of partially polarized antihydrogen atoms, a radiofrequency spin-flip cavity, a superconducting sextupole magnet as spin analyser, and an antihydrogen detector. This will be a measurement of the antiproton magnetic moment, and also a test of the CPT invariance. Monte Carlo simulations predict that the antihydrogen ground-state hyperfine splitting can be determined with a relative precision of ~10−7. The first preliminary measurements of the hyperfine transitions will start in 2011.

The PAX (Polarized Antiproton eXperiment) collaboration aims to polarise antiproton beams stored in ring by means of spin-filtering. The experimental setup is based on a polarised internal gas target, surrounded by a detection system for the measu rement of spin observables. In this report, we present results from the commission of the PAX target (atomic beam source, openable cell, and polarimeter).

A proposal to add 60-GeV electron and positron beams to the LHC at CERN (LHeC) is currently being prepared. The provision of electron and positron longitudinal polarisation is an important component of the proposal and we are examining the feasibility of Sokolov-Ternov self-polarisation at energies up to 60 GeV in a storage ring in the LHC tunnel. But at this energy the attainable polarisation can be very strongly limited by depolarising effects. This paper summarises first calculations of the attainable polarisation including estimates of the efficacy of Siberian Snakes for weakening synchrotron sideband resonances

Sources of positrons and antiprotons that are currently used for the formation of antihydrogen with low kinetic energies are reviewed, mostly in the context of the ALPHA collaboration and its predecessor ATHENA. The experiments were undertaken at the Antiproton Decelerator facility, which is located at CERN. Operations performed on the clouds of antiparticles to facilitate their mixing to produce antihydrogen are described. These include accumulation, cooling and manipulation. The formation of antihydrogen and some of the characteristics of the anti-atoms that are created are discussed. Prospects for trapping antihydrogen in a magnetic minimum trap, as envisaged by the ALPHA collaboration, are reviewed.

Emission of secondary electrons induced by the passage of low energy positrons through thin carbon foils was studied by the Monte Carlo method. The positron and electron elastic cross sections were calculated by partial wave analysis. The inelastic positron-valence-electron was described by the energy loss function obtained from dielectric theory. The positron-core-electron interaction was modelled by the Gryzinski's excitation function. Positron transport inside the carbon foil was simulated in detail. Secondary electrons created by positrons and high energy secondary electrons through inelastic interactions were tracked through the foil. The positron transmission coefficient and secondary electron yielded in forward and backward geometry are calculated and dependences on positron energy and carbon foil thickness are discussed.

Variable-energy positron annihilation spectroscopy (VEPAS) has been used to probe the structure of gold nanoparticles suspended in a silica aerogel matrix by measuring the annihilation parameters S and W, and the ortho-positronium (o-Ps) fraction parameter F, as a function of incident positron energy. Correction methods have been developed to improve the sensitivity of F by removing background contributions to the number of recorded o-Ps annihilation events. Charging effects have also been observed and investigated.

Neutrino oscillation experiments have shown that neutrinos have very small but non vanishing masses. These experiments however are not able to determine neither the absolute mass scale of neutrinos nor whether they are two-component Majorana particles, i.e. their own antiparticles. Neutrino-less double beta decay can only occur if the neutrinos are Majorana particles, a preferred scenario in most possible schemes leading to finite masses. Among several viable candidate isotopes, EXO has chosen Xe-136 to search for this decay. Its main advantage is that the final state, i.e. the barium ion, can be tagged using optical spectroscopy. The detection of the double beta decay daughter nucleus can be the key to a background free measurement of such a rare process. An intermediate size detector (EXO-200) of 200 kg enriched xenon (80% Xe-136) is about to take data at the WIPP underground site in New Mexico. A ton-scale experiment is being designed with Ba ion tagging capability. EXO-full will detect, in addition to the two electrons, the coincident appearance of a barium ion. This improved event signature is expected to provide total elimination of the background from radioactive impurities.

We have installed in Saclay a facility for an intense positron source in November 2008. It is based on a compact 5.5 MeV electron linac connected to a reaction chamber with a tungsten target inside to produce positrons via pair production. The expected production rate for fast positrons is 5?1011 per second. The study of moderation of fast positrons and the construction of a slow positron trap are underway. In parallel, we have investigated an efficient positron-positronium convertor using porous silica materials. These studies are parts of a project to produce positively charged antihydrogen ions aiming to demonstrate the feasibility of a free fall antigravity measurement of neutral antihydrogen.

Our group ASACUSA-MUSASHI has established an efficient way for accumulating antiprotons in the cusp trap, a combination of an anti-Helmholz superconducting coil and a multi-ring electrode trap. The last piece for synthesizing antihydrogens in the cusp trap is positron. We have developed a compact system to effectively accumulate positrons based on N2 gas-buffer scheme with a specially designed high precision cylindrical multi-ring electrode trap. Millions of positrons were accumulated in the pre-accumulator just using polycrystalline tungsten moderators. The accumulated positrons were transported as a pulsed beam via three guiding coils and caught in the cusp trap under cryogenic and ultra high vacuum conditions without serious loss. Confinement of two kinds of numerous antiparticles, e.g., 108 positrons and 107 antiprotons, in the cusp trap becomes feasible.

The PAMELA (Payload for Antimatter Matter Exploration and Light nuclei Astrophysics) experiment is a satellite-borne apparatus installed on the Resurs DK1 Russian satellite, and launched from the Baikonur cosmodrome on June 15th 2006. It aims to study charged particles in the cosmic radiation focusing on antiparticles and light nuclei. The PAMELA apparatus is made of different sub-detectors: a time-of-flight system, a magnetic spectrometer, a silicon-tungsten electromagnetic calorimeter, an anticoincidence system, a shower tail catcher scintillator and a neutron detector. In this paper the capability of the sub-detectors to identify light nuclei, on the flight data, will be presented.

The PAMELA (Payload for Antimatter Matter Exploration and Light nuclei Astrophysics) experiment is a satellite-borne apparatus that performes measurements of the cosmic radiation with a particular focus on antiparticles and light nuclei. Accurate measurements of the elemental composition of cosmic rays are required in order to understand the origin, propagation and lifetime of the cosmic radiation. In particular PAMELA measures the light nuclear component of cosmic rays from Hydrogen up to Oxygen in the interval 200 MeV/n-200 GeV/n. Object of this paper is the presentation of light-charge identification capabilities of PAMELA instrument as evaluated during the first three years of flight.

Recently a new wave of swarm studies of positrons was initiated based on more complete scattering cross section sets. Initially some interesting and new physics was discovered, most importantly negative differential conductivity (NDC) that occurs only for the bulk drift velocity while it does not exist for the flux property. However the ultimate goal was to develop tools to model positron transport in realistic applications and the work that is progressing along these lines is reviewed here. It includes studies of positron transport in molecular gases, thermalization in generic swarm situations and in realistic gas filled traps and transport of positrons in crossed electric and magnetic fields. Finally we have extended the same technique of simulation (Monte Carlo) to studies of thermalization of positronium molecule. In addition, recently published first steps towards including effects of dense media on positron transport are summarized here.

We have installed in Saclay a facility for an intense positron source in November 2008. It is based on a compact 5.5 MeV electron linac and a reaction chamber with a tungsten target to produce positrons via pair production. The expected production rate for fast positrons is 4·1011 per second. The study of moderation of fast positrons and the construction of a slow positron trap are underway. We have also developed an efficient positron-positronium convertor at CERN. These studies are parts of a project to demonstrate the feasibility of an experiment to produce the positively charged antihydrogen ion for a free fall measurement of neutral antihydrogen.

We have been developing a so-called cusp trap to synthesize antihydrogen atoms, and to make high precision microwave spectroscopy. The cusp trap consists of an anti-Helmholtz coil and a multi-ring trap, which yield axially symmetric magnetic and electric fields. This axial symmetry is quite important to realize stable confinements of antiproton and positron plasmas, which guarantees stable operation during the antihydrogen synthesis.

A reaction microscope that will enable angle-differential positron impact ionisation measurements with atomic and molecular targets, has been recently designed and built to meet the specifications of the Australian Positron Beamline Facility. We present details of this new device, highlighting the modifications to the well-established technique that are required for compatibility with a positron beam, and report on the experimental parameters and detection scheme for the first experiments.

Antiproton, the antiparticle of proton, is a unique projectile in the study of atomic collision physics, which can be treated theoretically either as a 'negative proton' or a 'heavy electron'. Atomic capture of an antiproton will result in formation of a highly excited exotic atom. Antiprotonic helium atom has been studied intensively by means of precision laser spectroscopy, which has led to a stringent determination of antiproton mass and charge to a level of ppb. Comparison of these values with those of proton gives one of the best tests of CPT invariance, the most fundamental symmetry in physics. However, the dynamic processes of antiproton capture remain unclarified. With an aim to produce an antiproton beam at atomic-physics energies for 'pure' collision experiments, we have so far developed techniques to decelerate, cool and confine antiprotons in vacuo, using a sequential combination of the Antiproton Decelerator (AD) at CERN, a Radio-Frequency Quadrupole Decelerator (RFQD), and an electromagnetic trap. Our recent success in stable extraction of monoenergetic ultra-slow antiprotons, about 3 × 10 5 in number available every 5 minutes, has opened up the possibility to study ionization and atomic capture processes between an antiproton and an atom under the single collision condition. Our design and strategy of the cross-beam experiments are presented, together with technical challenges in the detection system to identify the rare events with a reaction rate of 10 −4 .

We explain the relationship between Majorana neutrinos, which are their own antiparticles, and Majorana neutrino masses. We point out that Majorana masses would make the neutrinos very distinctive particles, and explain why many theorists strongly suspect that neutrinos do have Majorana masses. The promising approach to confirming this suspicion is to seek neutrinoless double beta decay. We introduce a toy model that illustrates why this decay requires nonzero neutrino masses, even when there are both right-handed and left-handed weak currents., 8 pages, pdf

We have studied the physics reach of an experiment where neutrinos produced in a beta-beam facility at CERN are observed in a large magnetized iron calorimeter (ICAL) at the India-based Neutrino Observatory (INO). The idea of beta-beam is based on the production of a pure, intense, collimated beam of electron neutrinos or their antiparticles via the beta decay of accelerated radioactive ions circulating in a storage ring. Interestingly, the CERN-INO distance of 7152 km happens to be tantalizingly close to the so-called 'magic' baseline where the sensitivity to the neutrino mass ordering (sign of Δm231 ≡ m23 − m21) and more importantly, θ13, goes up significantly, while the sensitivity to the unknown CP phase is absent. This permits such an experiment involving the golden Peμ channel to make precise measurements of the mixing angle θ13 and neutrino mass hierarchy avoiding the issues of intrinsic degeneracies and correlations which plague other baselines.

The General Antiparticle Spectrometer (GAPS) exploits low energy antideuterons produced in neutralino-neutralino annihilations as an indirect dark matter (DM) signature that is effectively free from background. When an antiparticle is captured by a target material, it forms an exotic atom in an excited state which quickly decays by emitting X-rays of precisely defined energy and a correlated pion signature from nuclear annihilation. We have successfully demonstrated the GAPS method in an accelerator environment and are currently planning a prototype flight from Japan for 2009. This will lead to a long duration balloon (LDB) mission that will complement existing and planned direct DM searches as well as other indirect techniques, probing a different, and often unique, region of parameter space in a variety of proposed DM models. Planes of coarsely pixellated Si(Li) detectors form the heart of the GAPS flight detector, providing both high X-ray energy resolution and good particle tracking. We will describe the proto-flight mission that will verify the performance of our Si(Li) detectors and cooling system in a flight-like configuration. We also will outline the LDB science payload design.

A search for narrow baryonic resonances produced in deep inelastic scattering and decaying to K0sp (K0spp) or Ξ (π+ and their antiparticles) is carried out with the H1 detector at HERA. No signal is observed for a new baryonic state. Upper limits on σ(ep → eΘX) × BR(Θ+ → K0p) and on the ratio of the production rates of hypothetical baryonic states relative to the Ξ(1530)0 baryonic state are obtained at the 95% confidence level.