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1.
  • Singh, B. P., et al. (author)
  • Experimental access to Transition Distribution Amplitudes with the PANDA experiment at FAIR
  • 2015
  • In: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 51:8
  • Journal article (peer-reviewed)abstract
    • Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuable new information on hadron structure appear as building blocks in the collinear factorized description for several types of hard exclusive reactions. In this paper, we address the possibility of accessing nucleon-to-pion (pi N) TDAs from (p) over barp -> e(+)e(-)pi(0) reaction with the future PANDA detector at the FAIR facility. At high center-of-mass energy and high invariant mass squared of the lepton pair q(2), the amplitude of the signal channel (p) over barp -> e(+)e(-)pi(0) admits a QCD factorized description in terms of pi N TDAs and nucleon Distribution Amplitudes (DAs) in the forward aid backward kinematic regimes. Assuming the validity of this factorized description, we perform feasibility studies for measuring (p) over barp -> e(+)e(-)pi(0) with the PANDA detector. Detailed simulations on signal reconstruction efficiency as well as on rejection of the most severe background channel, i.e. (p) over barp -> pi(+)pi(-)pi(0) were performed for the center-of-mass energy squared s = 5 GeV2 and s = 10 GeV2, in the kinematic regions 3.0 < q(2) < 4.3 GeV2 and 5 < q(2) < 9 GeV2, respectively, with a neutral pion scattered in the forward or backward cone vertical bar cos theta(pi 0)vertical bar > 0.5 in the proton-antiproton center-of-mass frame. Results of the simulation show that the particle identification capabilities of the PANDA detector will allow to achieve a background rejection factor of 5 . 10(7) (1 . 10(7)) at low (high) q(2) for s = 5 GeV2, and of 1 . 10(8) (6 . 10(6)) at low (high) q(2) for s = 10 GeV2, while keeping the signal reconstruction efficiency at around 40%. At both energies, a clean lepton signal can be reconstructed with the expected statistics corresponding to 2 of integrated luminosity. The cross sections obtained from the simulations are used to show that a test of QCD collinear factorization can be done at the lowest order by measuring scaling laws and angular distributions. The future measurement of the signal channel cross section with PANDA will provide a new test of the perturbative QCD description of a novel class of hard exclusive reactions and will open the possibility of experimentally accessing pi N TDAs.
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2.
  • Singh, B., et al. (author)
  • Study of doubly strange systems using stored antiprotons
  • 2016
  • In: Nuclear Physics A. - : Elsevier. - 0375-9474 .- 1873-1554. ; 954, s. 323-340
  • Journal article (peer-reviewed)abstract
    • Bound nuclear systems with two units of strangeness are still poorly known despite their importance for many strong interaction phenomena. Stored antiprotons beams in the GeV range represent an unparalleled factory for various hyperon-antihyperon pairs. Their outstanding large production probability in antiproton collisions will open the floodgates for a series of new studies of systems which contain two or even more units of strangeness at the PANDA experiment at FAIR. For the first time, high resolution gamma-spectroscopy of doubly strange Lambda Lambda-hypernuclei will be performed, thus complementing measurements of ground state decays of Lambda Lambda-hypernuclei at J-PARC or possible decays of particle unstable hypernuclei in heavy ion reactions. High resolution spectroscopy of multistrange Xi(-) -atoms will be feasible and even the production of Omega(-) -atoms will be within reach. The latter might open the door to the vertical bar S vertical bar = 3 world in strangeness nuclear physics, by the study of the hadronic Omega(-) -nucleus interaction. For the first time it will be possible to study the behavior of Xi(+) in nuclear systems under well controlled conditions.
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3.
  • Erni, W., et al. (author)
  • Technical design report for the PANDA (AntiProton Annihilations at Darmstadt) Straw Tube Tracker
  • 2013
  • In: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 49:2
  • Journal article (peer-reviewed)abstract
    • This document describes the technical layout and the expected performance of the Straw Tube Tracker (STT), the main tracking detector of the PANDA target spectrometer. The STT encloses a Micro-Vertex-Detector (MVD) for the inner tracking and is followed in beam direction by a set of GEM stations. The tasks of the STT are the measurement of the particle momentum from the reconstructed trajectory and the measurement of the specific energy loss for a particle identification. Dedicated simulations with full analysis studies of certain proton-antiproton reactions, identified as being benchmark tests for the whole PANDA scientific program, have been performed to test the STT layout and performance. The results are presented, and the time lines to construct the STT are described.
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4.
  • Collaboration, The PANDA, et al. (author)
  • Feasibility studies of time-like proton electromagnetic form factors at PANDA at FAIR
  • 2016
  • In: European Physical Journal A. - : Springer Publishing Company. - 1434-6001 .- 1434-601X. ; 52:10
  • Journal article (peer-reviewed)abstract
    • Simulation results for future measurements of electromagnetic proton form factors at P ¯ ANDA (FAIR) within the PandaRoot software framework are reported. The statistical precision with which the proton form factors can be determined is estimated. The signal channel p¯ p→ e+e- is studied on the basis of two different but consistent procedures. The suppression of the main background channel, i.e.p¯ p→ π+π-, is studied. Furthermore, the background versus signal efficiency, statistical and systematical uncertainties on the extracted proton form factors are evaluated using two different procedures. The results are consistent with those of a previous simulation study using an older, simplified framework. However, a slightly better precision is achieved in the PandaRoot study in a large range of momentum transfer, assuming the nominal beam conditions and detector performance.
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5.
  • Singh, B., et al. (author)
  • Feasibility study for the measurement of pi N transition distribution amplitudes at (P)over-barANDA in (P)over-barp -> J/psi pi(0)
  • 2017
  • In: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 95:3
  • Journal article (peer-reviewed)abstract
    • The exclusive charmonium production process in (P) over barp annihilation with an associated pi 0 meson (p) over barp -> J/psi pi(0) is studied in the framework of QCD collinear factorization. The feasibility of measuring this reaction through the J/psi -> e(+) e(-) decay channel with the AntiProton ANnihilation at DArmstadt ((P) over bar ANDA) experiment is investigated. Simulations on signal reconstruction efficiency as well as the background rejection from various sources including the (P) over barp -> pi(+)pi(-)pi(0) and (p) over barp -> J/psi pi(0)pi(0) reactions are performed with PANDAROOT, the simulation and analysis software framework of the (P) over bar ANDA experiment. It is shown that the measurement can be done at (P) over bar ANDA with significant constraining power under the assumption of an integrated luminosity attainable in four to five months of data taking at the maximum design luminosity.
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6.
  • Barucca, G., et al. (author)
  • Study of excited Ξ baryons with the P¯ ANDA detector
  • 2021
  • In: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
  • Journal article (peer-reviewed)abstract
    • The study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards N∗ and Δ spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the N∗ and Δ spectra. The future antiproton experiment P¯ANDA will provide direct access to final states containing a Ξ¯ Ξ pair, for which production cross sections up to μb are expected in p¯p reactions. With a luminosity of L= 10 31 cm- 2 s- 1 in the first phase of the experiment, the expected cross sections correspond to a production rate of ∼106events/day. With a nearly 4 π detector acceptance, P¯ANDA will thus be a hyperon factory. In this study, reactions of the type p¯p → Ξ¯ +Ξ∗ - as well as p¯p → Ξ¯ ∗ +Ξ- with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.
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7.
  • Barucca, G., et al. (author)
  • The potential of Λ and Ξ- studies with PANDA at FAIR
  • 2021
  • In: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
  • Journal article (peer-reviewed)abstract
    • The antiproton experiment PANDA at FAIR is designed to bring hadron physics to a new level in terms of scope, precision and accuracy. In this work, its unique capability for studies of hyperons is outlined. We discuss ground-state hyperons as diagnostic tools to study non-perturbative aspects of the strong interaction, and fundamental symmetries. New simulation studies have been carried out for two benchmark hyperon-antihyperon production channels: p¯ p→ Λ¯ Λ and p¯ p→ Ξ¯ +Ξ-. The results, presented in detail in this paper, show that hyperon-antihyperon pairs from these reactions can be exclusively reconstructed with high efficiency and very low background contamination. In addition, the polarisation and spin correlations have been studied, exploiting the weak, self-analysing decay of hyperons and antihyperons. Two independent approaches to the finite efficiency have been applied and evaluated: one standard multidimensional efficiency correction approach, and one efficiency independent approach. The applicability of the latter was thoroughly evaluated for all channels, beam momenta and observables. The standard method yields good results in all cases, and shows that spin observables can be studied with high precision and accuracy already in the first phase of data taking with PANDA.
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8.
  • Ahrens, J., et al. (author)
  • Measurement of the cosmic ray composition at the knee with the SPASE-2/AMANDA-B10 detectors
  • 2004
  • In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 21:6, s. 565-581
  • Journal article (peer-reviewed)abstract
    • The mass composition of high-energy cosmic rays at energies above 1015 eV can provide crucial information for the understanding of their origin. Air showers were measured simultaneously with the SPASE-2 air shower array and the AMANDA-B10 Cherenkov telescope at the South Pole. This combination has the advantage to sample almost all high-energy shower muons and is thus a new approach to the determination of the cosmic ray composition. The change in the cosmic ray mass composition was measured versus existing data from direct measurements at low energies. Our data show an increase of the mean log atomic mass 〈lnA〉 by about 0.8 between 500 TeV and 5 PeV. This trend of an increasing mass through the "knee" region is robust against a variety of systematic effects. © 2004 Elsevier B.V. All rights reserved.
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9.
  • Adolph, C, et al. (author)
  • Measurement of the eta -> 3 pi(0) Dalitz plot distribution with the WASA detector at COSY
  • 2009
  • In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 677:1-2, s. 24-29
  • Journal article (peer-reviewed)abstract
    • In the first production run of the WASA experiment at COSY, the eta decay into three neutral pions was measured in proton-proton interactions at a proton beam kinetic energy of 1.4 GeV. The Dalitz plot of the three pious was Studied using 1.2 x 10(5) fully reconstructed events. and the quadratic slope parameter alpha was determined to be -0.027 +/- 0.008(stat) +/- 0.005(syst). The result is consistent with previous measurements and further corroborates the importance of pion-pion final state interactions. (C) 2009 Elsevier B.V. All rights reserved.
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10.
  • Ahrens, J., et al. (author)
  • Calibration and survey of AMANDA with the SPASE detectors
  • 2004
  • In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 522:3, s. 347-359
  • Journal article (peer-reviewed)abstract
    • We report on the analysis of air showers observed in coincidence by the Antarctic Muon and Neutrino detector array (AMANDA-B10) and the South Pole Air Shower Experiment (SPASE-1 and SPASE-2). We discuss the use of coincident events for calibration and survey of the deep AMANDA detector as well as the response of AMANDA to muon bundles. This analysis uses data taken during 1997 when both SPASE-1 and SPASE-2 were in operation to provide a stereo view of AMANDA. © 2003 Elsevier B.V. All rights reserved.
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11.
  • Ahrens, J., et al. (author)
  • Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector
  • 2003
  • In: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 90:25, s. 2511011-2511015
  • Journal article (peer-reviewed)abstract
    • A report on the limits, which could be placed on diffuse fluxes of high energy extraterrestrial neutrinos, was presented. The incorporation of neutrino oscillations was necessary for interpreting the limits in terms of the flux from a cosmological distributions of sources. The energetic accelerated environments were presented as the sources of high energy extraterrestrial neutrinos.
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12.
  • Ahrens, J., et al. (author)
  • Search for Extraterrestrial Point Sources of Neutrinos with AMANDA-II
  • 2004
  • In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 92:7, s. 711021-711025
  • Journal article (peer-reviewed)abstract
    • The results of a search for point sources of high energy neutrinos in the northern hemisphere were presented using AMANDA-II data collected in the year 2000. The results included the flux limits on several active-galactic-nuclei blazars, microquasars, magnetars, and other candidate neutrino sources. A search for excesses above a random background of cosmic ray induced atmospheric neutrinos and misreconstructed downgoing cosmic-rays muons, which revealed no statistically significant neutrino point sources was also presented. It was shown that AMANDA-II had achieved the sensitivity required to probe known TeV γ-ray sources such as the blazar Markarian 501 in its 1997 flaring state at a level where neutrino and γ-ray fluxes were equal.
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13.
  • Niessen, Peter, et al. (author)
  • Recent results from the amanda experiment
  • 2003
  • In: Proceedings of 38th Rencontres de Moriond on Electroweak Interactions and Unified Theories 15-22 Mar 2003. Les Arcs, France.
  • Conference paper (peer-reviewed)abstract
    • AMANDA (Antarctic Muon And Neutrino Detector Array) is a neutrino telescope built under the southern polar icecap and its scope is to explore the possibility to detect high energy cosmic neutrinos. This should generate insight into the powerful celestial objects where acceleration mechanisms can bring up to 10 20   eV. We describe the achievements and results from the AMANDA-B10 prototype and the preliminary results from the current AMANDA-II detector which show dramatic increase in sensitivity.
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14.
  • Andrés, E., et al. (author)
  • Observation of high-energy neutrinos using Čerenkov detectors embedded deep in Antarctic ice
  • 2001
  • In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 410:6827, s. 441-443
  • Journal article (peer-reviewed)abstract
    • Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova2, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by much larger, expandable detectors in, for example, deep water3,4 or ice5. Here we report the detection of upwardly propagating atmospheric neutrinos by the ice-based Antarctic muon and neutrino detector array (AMANDA). These results establish a technology with which to build a kilometre-scale neutrino observatory necessary for astrophysical observations1.
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15.
  • Andres, E., et al. (author)
  • Selected recent results from AMANDA
  • 2001
  • In: ICHEP 2000. Proceedings of the 30th International Conference on High Energy Physics. - : World Scientific. ; , s. 965-968
  • Conference paper (peer-reviewed)abstract
    • We present a selection of results based on data taken in 1997 with the 302-PMT Antarctic Muon and Neutrino Detector Array-B10 ("AMANDA-B10") array. Atmospheric neutrinos created in the northern hemisphere are observed indirectly through their charged current interactions which produce relativistic, Cherenkov-light-emitting upgoing muons in the South Pole ice cap. The reconstructed angular distribution of these events is in good agreement with expectation and demonstrates the viability of this ice-based device as a neutrino telescope. Studies of nearly vertical upgoing muons limit the available parameter space for WIMP dark matter under the assumption that WIMPS are trapped in the earth's gravitational potential well and annihilate with one another near the earth's center.
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16.
  • Karle, A., et al. (author)
  • Observation of high energy atmospheric neutrinos with AMANDA
  • 2000
  • In: AIP Conference Proceedings. - : American Institute of Physics (AIP). ; , s. 823-827
  • Conference paper (peer-reviewed)abstract
    • In 1997 the Antarctic Muon and Neutrino Detector Array (AMANDA) started operating with 10 strings. In an analysis of data taken during the first year of operation 188 atmospheric neutrino candidates were found. Their zenith angle distribution agrees with expectations based on Monte Carlo simulations. A preliminary upper limit is given on a diffuse flux of high energy neutrinos of astrophysical origin.
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17.
  • Adlarson, Patrik, et al. (author)
  • Search for C violation in the decay eta -> pi(0)e(+)e(-) with WASA-at-COSY
  • 2018
  • In: Physics Letters B. - : ELSEVIER SCIENCE BV. - 0370-2693 .- 1873-2445. ; 784, s. 378-384
  • Journal article (peer-reviewed)abstract
    • We report on the search for the rare decay eta -> pi(0)e(+)e(-) which is of interest to study C violation in the electromagnetic interaction which would indicate contributions from physics beyond the Standard Model, since the allowed decay via a two-photon intermediate state is strongly suppressed. The experiment has been performed using the WASA-at-COSY installation, located at the COSY accelerator of the Forschungszentrum Julich, Germany. In total 3 x 10(7) events of the reaction pd -> He-3 eta have been recorded at an excess energy of Q = 59.8MeV. Based on this data set the C parity violating decay eta -> pi(0)gamma* -> pi(0)e(+)e(-) via a single-photon intermediate state has been searched for, resulting in new upper limits of Gamma(eta -> pi(0)e(+) e(-))/Gamma(eta -> pi(+) pi(-) pi(0)) < 3.28 x 10(-5) and Gamma(eta -> pi(0)e(+) e(-))/Gamma(eta -> all)< 7.5 x 10(-6) (CL=90%), respectively. 
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18.
  • Ahrens, J., et al. (author)
  • Muon track reconstruction and data selection techniques in AMANDA
  • 2004
  • In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 524:1-3, s. 169-194
  • Journal article (peer-reviewed)abstract
    • The Antarctic Muon And Neutrino Detector Array (AMANDA) is a high-energy neutrino telescope operating at the geographic South Pole. It is a lattice of photo-multiplier tubes buried deep in the polar ice between 1500 and 2000 m. The primary goal of this detector is to discover astrophysical sources of high-energy neutrinos. A high-energy muon neutrino coming through the earth from the Northern Hemisphere can be identified by the secondary muon moving upward through the detector. The muon tracks are reconstructed with a maximum likelihood method. It models the arrival times and amplitudes of Cherenkov photons registered by the photo-multipliers. This paper describes the different methods of reconstruction, which have been successfully implemented within AMANDA. Strategies for optimizing the reconstruction performance and rejecting background are presented. For a typical analysis procedure the direction of tracks are reconstructed with about 2° accuracy. © 2004 Elsevier B.V. All rights reserved.
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19.
  • Ahrens, J., et al. (author)
  • Observation of high energy atmospheric neutrinos with the Antarctic muon and neutrino detector array
  • 2002
  • In: Physical Review D. - : American Physical Society. - 1550-7998 .- 1550-2368. ; 66:1, s. 120051-1200520
  • Journal article (peer-reviewed)abstract
    • The Antarctic muon and neutrino detector array (AMANDA) began collecting data with ten strings in 1997. Results from the first year of operation are presented. Neutrinos coming through the Earth from the Northern Hemisphere are identified by secondary muons moving upward through the array. Cosmic rays in the atmosphere generate a background of downward moving muons, which are about 106 times more abundant than the upward moving muons. Over 130 days of exposure, we observed a total of about 300 neutrino events. In the same period, a background of 1.05 × 109 cosmic ray muon events was recorded. The observed neutrino flux is consistent with atmospheric neutrino predictions. Monte Carlo simulations indicate that 90% of these events lie in the energy range 66 GeV to 3.4 TeV. The observation of atmospheric neutrinos consistent with expectations establishes AMANDA-B10 as a working neutrino telescope.
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20.
  • Ahrens, J., et al. (author)
  • Results from the AMANDA telescope
  • 2003
  • In: Nuclear Physics A. - : Elsevier. - 0375-9474 .- 1873-1554. ; 721, s. C545-C548
  • Journal article (peer-reviewed)abstract
    • We present results from the AMANDA high energy neutrino telescope located at the South Pole. They include measurements of the atmospheric neutrino flux, search for UHE point sources, and diffuse sources producing electromagnetic/hadronic showers at the detector or close to it.
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21.
  • Ahrens, J., et al. (author)
  • Search for supernova neutrino bursts with the AMANDA detector
  • 2001
  • In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 16:4, s. 345-359
  • Journal article (peer-reviewed)abstract
    • The core collapse of a massive star in the Milky Way will produce a neutrino burst, intense enough to be detected by existing underground detectors. The AMANDA neutrino telescope located deep in the South Pole ice can detect MeV neutrinos by a collective rate increase in all photo-multipliers on top of dark noise. The main source of light comes from positrons produced in the CC reaction of anti-electron neutrinos on free protons ve + p → e+ + n. This paper describes the first supernova search performed on the full sets of data taken during 1997 and 1998 (215 days of live time) with 302 of the detector's optical modules. No candidate events resulted from this search. The performance of the detector is calculated, yielding a 70% coverage of the galaxy with one background fake per year with 90% efficiency for the detector configuration under study. An upper limit at the 90% c.l. on the rate of stellar collapses in the Milky Way is derived, yielding 4.3 events per year. A trigger algorithm is presented and its performance estimated. Possible improvements of the detector hardware are reviewed.
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22.
  • Andrés, E., et al. (author)
  • Recent results from AMANDA
  • 2001
  • In: International Journal of Modern Physics A. - 0217-751X .- 1793-656X. ; 16:1C, s. 1013-1015
  • Journal article (peer-reviewed)abstract
    • We present results based on data taken in 1997 with the 302-PMT Antarctic Muon and Neutrino Detector Array-B10 ("AMANDA-B10") array. Atmospheric neutrinos created in the northern hemisphere are observed indirectly through their charged current interactions which produce relativistic, Cherenkov-light-emitting upgoing muons in the South Pole ice cap. The reconstructed angular distribution of these events is in good agreement with expectation and demonstrates the viability of this ice-based device as a neutrino telescope.
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23.
  • Andres, E., et al. (author)
  • Results from the AMANDA high energy neutrino detector
  • 2000
  • In: Nuclear physics B, Proceedings supplements. - : Elsevier. - 0920-5632 .- 1873-3832. ; 91:1-3, s. 423-430
  • Journal article (peer-reviewed)abstract
    • This paper briefly summarizes the search for astronomical sources of high-energy neutrinos using the AMANDA-B10 detector. The complete data set from 1997 was analyzed. For Eμ > 10 TeV, the detector exceeds 10,000 m2 in effective area between declinations of 25 and 90 degrees. Neutrinos generated in the atmosphere by cosmic ray interactions were used to verify the overall sensitivity of the detector. The absolute pointing accuracy and angular resolution has been confirmed by the analysis of coincident events between the SPASE air shower array and the AMANDA detector. Preliminary flux limits from point source candidates are presented. For declinations larger than +45 degrees, our results compare favorably to existing limits for sources in the Southern sky. We also present the current status of the searches for high energy neutrino emission from diffusely distributed sources, GRBs, and WIMPs from the center of the earth.
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24.
  • Adlarson, Patrik, et al. (author)
  • Differential cross sections for neutron-proton scattering in the region of the d* (2380) dibaryon resonance
  • 2020
  • In: Physical Review C. Nuclear Physics. - : AMER PHYSICAL SOC. - 0556-2813 .- 1089-490X. ; 102:1
  • Journal article (peer-reviewed)abstract
    • Differential cross sections have been extracted from exclusive and kinematically complete high-statistics measurements of quasifree polarized (n) over barp scattering performed in the energy region of the d* (2380) dibaryon resonance covering the range of beam energies T-n = 0.98-1.29 GeV (root s = 2.32-2.44 GeV). The experiment was carried out with the WASA-at-COSY setup having a polarized deuteron beam impinged on the hydrogen pellet target and utilizing the quasifree process dp -> np + p(spectator). In this way the np differential cross section sigma (Theta) was measured over a large angular range. The obtained angular distributions complement the corresponding analyzing power A(y)(Theta) measurements published previously. A SAID partial-wave analysis incorporating the new data strengthens the finding of a resonance pole in the coupled D-3(3) - (3)G(3) waves.
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25.
  • Adlarson, Patrik, et al. (author)
  • Evidence for a New Resonance from Polarized Neutron-Proton Scattering
  • 2014
  • In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 112:20, s. 202301-
  • Journal article (peer-reviewed)abstract
    • Exclusive and kinematically complete high-statistics measurements of quasifree polarized (n) over right arrowp scattering have been performed in the energy region of the narrow resonancelike structure d* with I(J(P)) = 0(3(+)),M approximate to 2380 MeV, and Gamma approximate to 70 MeV observed recently in the double-pionic fusion channels pn -> d pi(0)pi(0) and pn -> d pi(+)pi(-). The experiment was carried out with the WASA detector setup at COSY having a polarized deuteron beam impinged on the hydrogen pellet target and utilizing the quasifree process (d) over right arrowp -> np + p(spectator). This allowed the np analyzing power, A(y), to be measured over a broad angular range. The obtained A(y) angular distributions deviate systematically from the current SAID SP07 NN partial-wave solution. Incorporating the new A(y) data into the SAID analysis produces a pole in the D-3(3) - (3)G(3) waves in support of the d* resonance hypothesis.
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26.
  • Ahrens, J., et al. (author)
  • Initial results from AMANDA
  • 2001
  • In: 21st Rencontres de Moriond Workshop on Very High-Energy Phenomena in the Universe.
  • Conference paper (peer-reviewed)
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27.
  • Ahrens, J., et al. (author)
  • Limits to the muon flux from WIMP annihilation in the center of the Earth with the AMANDA detector
  • 2002
  • In: Physical Review D. - : American Physical Society. - 1550-7998 .- 1550-2368. ; 66:3, s. 032006-
  • Journal article (peer-reviewed)abstract
    • A search for nearly vertical up-going muon-neutrinos from neutralino annihilations in the center of the Earth has been performed with the AMANDA-B10 neutrino detector. The data collected in 130.1 days of live time in 1997, ∼10 9 events, have been analyzed for this search. No excess over the expected atmospheric neutrino background has been observed. An upper limit at 90% confidence level has been obtained on the annihilation rate of neutralinos in the center of the Earth, as well as the corresponding muon flux limit, both as a function of the neutralino mass in the range 100 GeV-5000 GeV. © 2002 The American Physical Society.
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28.
  • Ahrens, J., et al. (author)
  • Physics and operation of the AMANDA-II high energy neutrino telescope
  • 2002
  • In: Proceedings of the SPIE - The International Society for Optical Engineering 2003. - : Institution of Electrical Engineers (IEE). ; , s. 79-91
  • Conference paper (peer-reviewed)abstract
    • This paper briefly describes the principle of operation and science goals of the AMANDA high energy neutrino telescope located at the South Pole, Antarctica. Results from an earlier phase of the telescope, called AMANDA-B10, demonstrate both reliable operation and the broad astrophysical reach of this device, which includes searches for a variety of sources of ultrahigh energy neutrinos: generic point sources, Gamma-Ray Bursts and diffuse sources. The predicted sensitivity and angular resolution of the telescope were confirmed by studies of atmospheric muon and neutrino backgrounds. We also report on the status of the analysis from AMANDA-II, a larger version with far greater capabilities. At this stage of analysis, details of the ice properties and other systematic uncertainties of the AMANDA-II telescope are under study, but we have made progress toward critical science objectives. In particular, we focus on the search for continuous emission from astrophysical point sources and the search for correlated neutrino emission from Gamma Ray Bursts detected by BATSE before decommissioning in May 2000. During the next two years, we expect to exploit the full potential of AMANDA-II with the installation of a new data acquisition system that records full waveforms from the in-ice optical sensors.
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29.
  • Ahrens, J., et al. (author)
  • Search for neutrino-induced cascades with the AMANDA detector
  • 2003
  • In: Physical Review D. - : American Physical Society (APS). - 1550-7998 .- 1550-2368. ; 67:1, s. 012003-
  • Journal article (peer-reviewed)abstract
    • We report on a search for electromagnetic and/or hadronic showers (cascades) induced by a diffuse flux of neutrinos with energies between 5 TeV and 300 TeV from extraterrestrial sources. Cascades may be produced by matter interactions of all flavors of neutrinos, and contained cascades have better energy resolution and afford better background rejection than throughgoing νμ-induced muons. Data taken in 1997 with the AMANDA detector were searched for events with a high-energy cascadelike signature. The observed events are consistent with expected backgrounds from atmospheric neutrinos and catastrophic energy losses from atmospheric muons. Effective volumes for all flavors of neutrinos, which allow the calculation of limits for any neutrino flux model, are presented. The limit on cascades from a diffuse flux of νe+ νμ + ντ+ ν̄e + ν̄μ+ ν̄τ is E2(dΦ/dE)<9.8×10-6 GeV cm-2 s-1 sr-1, assuming a neutrino flavor flux ratio of 1:1:1 at the detector. The limit on cascades from a diffuse flux of νe+ν̄e is E2(dΦ/dE)<6. 5×10-6 GeV cm-2 s-1 sr-1, independent of the assumed neutrino flavor flux ratio. © 2003 The American Physical Society.
  •  
30.
  • Ahrens, J., et al. (author)
  • Search for point sources of high-energy neutrinos with AMANDA
  • 2003
  • In: Astrophysical Journal Letters. - : Institute of Physics (IOP). - 2041-8205 .- 0004-637X .- 1538-4357. ; 583:2 I, s. 1040-1057
  • Journal article (peer-reviewed)abstract
    • This paper describes the search for astronomical sources of high-energy neutrinos using the AMANDA-B10 detector, an array of 302 photomultiplier tubes used for the detection of Cerenkov light from upward-traveling neutrino-induced muons, buried deep in ice at the South Pole. The absolute pointing accuracy and angular resolution were studied by using coincident events between the AMANDA detector and two independent telescopes on the surface, the GASP air Cerenkov telescope and the SPASE extensive air shower array. Using data collected from 1997 April to October (130.1 days of live time), a general survey of the northern hemisphere revealed no statistically significant excess of events from any direction. The sensitivity for a flux of muon neutrinos is based on the effective detection area for through-going muons. Averaged over the northern sky, the effective detection area exceeds 10,000 m2 for E μ ≈ 10 TeV. Neutrinos generated in the atmosphere by cosmic-ray interactions were used to verify the predicted performance of the detector. For a source with a differential energy spectrum proportional to Eν -2 and declination larger than +40°, we obtain E2(dNν/dE) ≤ 10-6 GeV cm-2 s-1 for an energy threshold of 10 GeV.
  •  
31.
  • Andres, E., et al. (author)
  • AMANDA : Status, results and future
  • 1999
  • In: Proceedings, 8th International Workshop, Venice, Italy, February 23-26, 1999. Vol. 1, 2. ; , s. 63-79
  • Conference paper (peer-reviewed)abstract
    • We review the status of the AMANDA neutrino telescope. We present resultsobtained from the four-string prototype array AMANDA-B4 and describe themethods of track reconstruction and neutrino event separation. We give also firstresults of the analysis of the 10-string detector AMANDA-B10, in particular onatmospheric neutrinos and the search for magnetic monopoles. We sketch thefuture schedule on the way to a cube kilometer telescope at the South Pole,ICECUBE.
  •  
32.
  • Andrés, E. C., et al. (author)
  • The AMANDA neutrino telescope
  • 1999
  • In: Nuclear physics B, Proceedings supplements. - 0920-5632 .- 1873-3832. ; 77:1-3, s. 474-485
  • Journal article (peer-reviewed)abstract
    • With an effective telescope area of order 104 m2 for TeV neutrinos, a threshold near ∼50 GeV and a pointing accuracy of 2.5 degrees per muon track, the AMANDA detector represents the first of a new generation of high energy neutrino telescopes, reaching a scale envisaged over 25 years ago. We describe early results on the calibration of natural deep ice as a particle detector as well as on AMANDA's performance as a neutrino telescope.
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33.
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34.
  • Bai, X., et al. (author)
  • Status of the Neutrino Telescope AMANDA : Monopoles and WIMPS
  • 2001
  • In: Dark Matter in Astro- and Particle Physics. - Berlin, Heidelberg : Springer. - 9783642626081 ; , s. 699-706
  • Conference paper (peer-reviewed)abstract
    • The neutrino telescope AMANDA has been set up at the geographical South Pole as first step to a neutrino telescope of the scale of one cubic kilometer, which is the canonical size for a detector sensitive to neutrinos from Active Galactic Nuclei (AGN), Gamma Ray Bursts (GRB) and Topological Defects (TD). The location and depth in which the detector is installed is given by the requirement to detect neutrinos by the Cherenkov light produced by their reaction products and to keep the background due to atmospheric muons as small as possible. However, a detector optimized for this purpose is also capable to detect the bright Cherenkov light from relativistic Monopoles and neutrino signals from regions with high gravitational potential, where WIMPS are accumulated and possibly annihilate. Both hypothetical particles might contribute to the amount of dark matter. Therefore here a report about the status of the experiment (autumn 2000) and about the status of the search for these particles with the AMANDA B10 sub-detector is given.
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35.
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36.
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37.
  • Wiebusch, C., et al. (author)
  • Results from AMANDA
  • 2002
  • In: Modern Physics Letters A. - : Institution of Electrical Engineers (IEE). - 0217-7323 .- 1793-6632. ; 17:31, s. 2019-2037
  • Journal article (peer-reviewed)abstract
    • The Antarctic Muon and Neutrino Detector Array (AMANDA) is a high-energy neutrino telescope operating at the geographic South Pole. It is a lattice of photomultiplier tubes buried deep in the polar ice. The primary goal of this detector is to discover astrophysical sources of high energy neutrinos. We describe the detector methods of operation and present results from the AMANDA-B10 prototype. We demonstrate the improved sensitivity of the current AMANDA-II detector. We conclude with an outlook to the envisioned sensitivity of the future IceCube detector.
  •  
38.
  • Wischnewski, R., et al. (author)
  • The AMANDA neutrino detector : Status report
  • 2000
  • In: Nuclear physics B, Proceedings supplements. - 0920-5632 .- 1873-3832. ; 85:1-3, s. 141-145
  • Journal article (peer-reviewed)abstract
    • The first stage of the AMANDA High Energy Neutrino Detector at the South Pole, the 302 PMT array AMANDA-B10, is taking data since 1997. We describe results on atmospheric neutrinos, limits on indirect WIMP detection, seasonal muon flux variation, relativistic monopole flux limits, a search for gravitational collapse neutrinos, and a depth scan of the optical ice properties. The next stage 19-string detector AMANDA-II with ∼650 PMTs will be completed in spring 2000.
  •  
39.
  • Wischnewski, R., et al. (author)
  • The AMANDA neutrino detector
  • 1999
  • In: Nuclear physics B, Proceedings supplements. - : Elsevier. - 0920-5632 .- 1873-3832. ; 75:1-2, s. 412-414
  • Journal article (peer-reviewed)abstract
    • The first stage of the AMANDA High Energy Neutrino Detector at the South Pole, the 302 PMT array AMANDA-B with an expected effective area for TeV neutrinos of ∼ 104 m2, has been taking data since 1997. Progress with calibration, investigation of ice properties, as well as muon and neutrino data analysis are described. The next stage 20-string detector AMANDA-II with ∼800 PMTs will be completed in spring 2000.
  •  
40.
  • Abele, H., et al. (author)
  • Particle physics at the European Spallation Source
  • 2023
  • In: Physics reports. - : Elsevier. - 0370-1573 .- 1873-6270. ; 1023, s. 1-84
  • Research review (peer-reviewed)abstract
    • Presently under construction in Lund, Sweden, the European Spallation Source (ESS) will be the world’s brightest neutron source. As such, it has the potential for a particle physics program with a unique reach and which is complementary to that available at other facilities. This paper describes proposed particle physics activities for the ESS. These encompass the exploitation of both the neutrons and neutrinos produced at the ESS for high precision (sensitivity) measurements (searches).
  •  
41.
  • Adlarson, Patrik, et al. (author)
  • Abashian-Booth-Crowe Effect in Basic Double-Pionic Fusion : A New Resonance?
  • 2011
  • In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 106:24, s. 242302-
  • Journal article (peer-reviewed)abstract
    • We report on an exclusive and kinematically complete high-statistics measurement of the basic double-pionic fusion reaction pn -> d pi(0)pi(0) over the full energy region of the ABC effect, a pronounced low-mass enhancement in the pi pi-invariant mass spectrum. The measurements, which cover also the transition region to the conventional t- channel Delta Delta process, were performed with the upgraded WASA detector setup at COSY. The data reveal the Abashian-Booth-Crowe effect to be uniquely correlated with a Lorentzian energy dependence in the integral cross section. The observables are consistent with a narrow resonance with m = 2.37 GeV, Gamma approximate to 70 MeV and I(J(P)) = 0(3(+)) in both pn and Delta Delta systems. Necessary further tests of the resonance interpretation are discussed.
  •  
42.
  • Adlarson, Patrik, et al. (author)
  • Abashian-Booth-Crowe resonance structure in the double pionic fusion to He-4
  • 2012
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 86:3, s. 032201-
  • Journal article (peer-reviewed)abstract
    • Exclusive and kinematically complete high-statistics measurements of the double pionic fusion reaction dd -> He-4 pi(0)pi(0) have been performed in the energy range 0.8-1.4 GeV covering thus the region of the Abashian-Booth-Crowe effect, which denotes a pronounced low-mass enhancement in the pi pi invariant mass spectrum. The experiments were carried out with the WASA detector setup at the cooler synchrotron at Forshungszentrum Julich GmbH. Similar to the observation in the basic pn -> d pi(0)pi(0) reaction, the data reveal a correlation between the ABC effect and a resonancelike energy dependence in the total cross section. The maximum occurs at m = 2.37 GeV + 2m(N), i.e., at the same position as in the basic reaction. The observed resonance width Gamma approximate to 160 MeV can be understood from broadening due to Fermi motion of the nucleons in initial and final nuclei together with collision damping. Differential cross sections are described equally well by the hypothesis of a pn resonance formation during the reaction process.
  •  
43.
  • Adlarson, Patrik, et al. (author)
  • Cross section ratio and angular distributions of the reaction p + d -> He-3 + eta at 48.8MeV and 59.8MeV excess energy
  • 2014
  • In: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 50:6, s. 100-
  • Journal article (peer-reviewed)abstract
    • We present new data for angular distributions and on the cross section ratio of the p+d -> He-3+eta reaction at excess energies of Q - 48.8MeV and Q - 59.8 MeV. The data have been obtained at the WASA-at-COSY experiment (Forschungszentrum Julich) using a proton beam and a deuterium pellet target. While the shape of obtained angular distributions show only a slow variation with the energy, the new results indicate a distinct and unexpected total cross section fluctuation between Q = 20MeV and Q = 60 MeV, which might indicate the variation of the production mechanism within this energy interval.
  •  
44.
  • Adlarson, Patrik, et al. (author)
  • Exclusive measurement of the eta -> pi(+) pi(-) gamma decay
  • 2012
  • In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 707:2, s. 243-249
  • Journal article (peer-reviewed)abstract
    • An exclusive measurement of the decay eta -> pi(+) pi(-) gamma has been performed at the WASA facility at COSY. The eta mesons were produced in the fusion reaction pd -> He-3 X at a proton beam momentum of 1.7 GeV/c. Efficiency corrected differential distributions have been extracted based on 13 960 +/- 140 events after background subtraction. The measured pion angular distribution is consistent with a relative p-wave of the two-pion system, whereas the measured photon energy spectrum was found at variance with the simplest gauge invariant matrix element of eta -> pi(+) pi(-) gamma. A parameterization of the data can be achieved by the additional inclusion of the empirical pion vector form factor multiplied by a first-order polynomial in the squared invariant mass of the pi(+) pi(-) system.
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45.
  • Adlarson, Patrik, et al. (author)
  • Investigation of the dd -> (3)Hen pi(0) reaction with the FZ Julich WASA-at-COSY facility
  • 2013
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 88:1, s. 014004-
  • Journal article (peer-reviewed)abstract
    • An exclusive measurement of the dd -> (3)Hen pi(0) reaction was carried out at a beam momentum of p(d) = 1.2 GeV/c using the WASA-at-COSY facility. Information on the total cross section as well as differential distributions was obtained. The data are described by a phenomenological approach based on a combination of a quasifree model and a partial wave expansion for the three-body reaction. The total cross section is found to be sigma(tot) = ( 2.89 +/- 0.01(stat) +/- 0.06(sys) +/- 0.29(norm)) mu b. The contribution of the quasifree processes ( with the beam or target neutron being a spectator) accounts for 38% of the total cross section and dominates the differential distributions in specific regions of phase space. The remaining part of the cross section can be described by a partial wave decomposition indicating the significance of p-wave contributions in the final state.
  •  
46.
  • Adlarson, P., et al. (author)
  • Isospin decomposition of the basic double-pionic fusion in the region of the ABC effect
  • 2013
  • In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 721:4-5, s. 229-236
  • Journal article (peer-reviewed)abstract
    • Exclusive and kinematically complete high-statistics measurements of the basic double-pionic fusion reactions pn -> d pi(0)pi(0), pn -> d pi(+)pi(-) and pp -> d pi(+)pi(0) have been carried out simultaneously over the energy region of the ABC effect using the WASA detector setup at COSY. Whereas the isoscalar reaction part given by the d pi(0)pi(0) channel exhibits the ABC effect, i.e. a low-mass enhancement in the pi pi-invariant mass distribution, as well as the associated resonance structure in the total cross section, the isovector part given by the d pi(+)pi(0) channel shows a smooth behavior consistent with the conventional t-channel Delta Delta process. The d pi(+)pi(-) data are very well reproduced by combining the data for isovector and isoscalar contributions, if the kinematical consequences of the isospin violation due to different masses for charged and neutral pions are taken into account.
  •  
47.
  • Adlarson, Patrik, et al. (author)
  • Measurement of the eta -> pi(+)pi(-)pi(0) Dalitz plot distribution
  • 2014
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 90:4, s. 045207-
  • Journal article (peer-reviewed)abstract
    • The Dalitz plot distribution of the eta -> pi(+)pi(-)pi(0) decay is determined by using a data sample of 1.2 x 10(7) eta mesons from the pd -> He-3 eta reaction at 1 GeV collected by the WASA detector at COSY.
  •  
48.
  • Adlarson, Patrik, et al. (author)
  • Measurement of the pn -> pp pi(0)pi(-) reaction in search for the recently observed resonance structure in d pi(0)pi(0) and d pi(+)pi(-) systems
  • 2013
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 88:5, s. 055208-
  • Journal article (peer-reviewed)abstract
    • Exclusive measurements of the quasifree pn -> pp pi(0)pi(-) reaction have been performed by means of pd collisions at T-p = 1.2 GeV using the wide angle shower apparatus (WASA) detector setup at the cooler synchrotron COSY (Institut fur Kernphysik, Julich). Total and differential cross sections have been obtained covering the energy region root s = (2.35-2.46) GeV, which includes the region of the ABC effect and its associated resonance structure. NoABCeffect, i.e., low-mass enhancement is found in the pi(0)pi(-) -invariant mass spectrum, in agreement with the constraint from Bose statistics that the isovector pion pair can not be in relative s wave. At the upper end of the covered energy region t-channel processes for Roper, Delta(1600) and Delta Delta excitations provide a reasonable description of the data, but at low energies the measured cross sections are much larger than predicted by such processes. Adding a resonance amplitude for the resonance at m = 2.37 GeV with Gamma = 70 MeV and I (J(P)) = 0(3(+)) observed recently in pn -> d pi(0)pi(0) and pn -> d pi(+)pi(-) reactions leads to an agreement with the data also at low energies.
  •  
49.
  • Adlarson, Patrik, et al. (author)
  • Neutron-proton scattering in the context of the d*(2380) resonance
  • 2014
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 90:3, s. 035204-
  • Journal article (peer-reviewed)abstract
    • New data on quasifree polarized neutron-proton scattering in the region of the recently observed d* resonance structure are obtained by exclusive and kinematically complete high-statistics measurements with WASA at COSY. This paper details the determination of the beam polarization, checks of the quasifree character of the scattering process, on all obtained Ay angular distributions and on the new partial-wave analysis, which includes the new data producing a resonance pole in D-3(3)-(3)G(3) coupled partial waves at (2380 +/- 10 - i40 +/- 5) MeV-in accordance with the d* dibaryon resonance hypothesis. The effect of the new partial-wave solution on the description of total and differential cross-section data as well as specific combinations of spin-correlation and spin-transfer observables available from COSY-ANKE measurements at T-d = 2.27 GeV is discussed.
  •  
50.
  • Adlarson, Patrik, et al. (author)
  • Search for eta-mesic He-4 with the WASA-at-COSY detector
  • 2013
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 87:3, s. 035204-
  • Journal article (peer-reviewed)abstract
    • An exclusive measurement of the excitation function for the dd -> (3)Hep pi(-) reaction was performed at the Cooler Synchrotron COSY-Julich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 to 2.400 GeV/c crossing the kinematic threshold for the eta-meson production in the dd -> He-4 eta reaction at 2.336 GeV/c. The corresponding excess energy with respect to the He-4-eta system varied from -51.4 to 22 MeV. The integrated luminosity in the experiment was determined using the dd -> (3)Hen reaction. The shape of the excitation function for the dd -> (3)Hep pi(-) reaction was examined. No signal of the He-4-eta bound state was observed. An upper limit for the cross section for the bound state formation and decay in the process dd -> (He-4-eta)(bound) -> (3)Hep pi(-) was determined on the 90% confidence level and it varies from 20 to 27 nb for the bound state width ranging from 5 to 35 MeV, respectively. 
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