| 1. |
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| 2. |
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| 3. |
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| 4. |
- Barucca, G., et al.
(author)
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The potential of Λ and Ξ- studies with PANDA at FAIR
- 2021
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In: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
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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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| 5. |
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| 6. |
- Barucca, G., et al.
(author)
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Study of excited Ξ baryons with the P¯ ANDA detector
- 2021
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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. |
- Collaboration, The PANDA, et al.
(author)
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Feasibility studies of time-like proton electromagnetic form factors at PANDA at FAIR
- 2016
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In: European Physical Journal A. - : Springer Publishing Company. - 1434-6001 .- 1434-601X. ; 52:10
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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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| 8. |
- Singh, B., et al.
(author)
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Feasibility study for the measurement of pi N transition distribution amplitudes at (P)over-barANDA in (P)over-barp -> J/psi pi(0)
- 2017
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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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| 9. |
- Singh, B., et al.
(author)
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Study of doubly strange systems using stored antiprotons
- 2016
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In: Nuclear Physics A. - : Elsevier. - 0375-9474 .- 1873-1554. ; 954, s. 323-340
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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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| 10. |
- Erni, W., et al.
(author)
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Technical design report for the PANDA (AntiProton Annihilations at Darmstadt) Straw Tube Tracker
- 2013
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In: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 49:2
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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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| 11. |
- Singh, B. P., et al.
(author)
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Experimental access to Transition Distribution Amplitudes with the PANDA experiment at FAIR
- 2015
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In: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 51:8
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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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| 12. |
- Gross, C. P., et al.
(author)
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The biogeography of community assembly: latitude and predation drive variation in community trait distribution in a guild of epifaunal crustaceans
- 2022
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In: Proceedings of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2954 .- 0962-8452. ; 289:1969
-
Journal article (peer-reviewed)abstract
- While considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Studying how the distributions of traits in communities vary along global gradients can inform how variation in interactions and other factors contribute to the process of community assembly. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (Zostera marina) spanning 30° of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed while Atlantic communities were more clustered, and increasing epiphytes were associated with increased clustering. By examining how species interactions and environmental filters influence community structure across biogeographic regions, we demonstrate how both latitudinal variation in species interactions and historical contingency shape these responses. Community trait distributions have implications for ecosystem stability and functioning, and integrating large-scale observations of environmental filters, species interactions and traits can help us predict how communities may respond to environmental change.
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| 13. |
- Pawlowski, P., et al.
(author)
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Neutron recognition in the LAND detector for large neutron multiplicity
- 2012
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In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 694, s. 47-54
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Journal article (peer-reviewed)abstract
- The performance of the LAND neutron detector is studied. Using an event-mixing technique based on one-neutron data obtained in the S107 experiment at the GSI laboratory, we test the efficiency of various analytic tools used to determine the multiplicity and kinematic properties of detected neutrons. A new algorithm developed recently for recognizing neutron showers from spectator decays in the ALADIN experiment S254 is described in detail. Its performance is assessed in comparison with other methods. The properties of the observed neutron events are used to estimate the detection efficiency of LAND in this experiment. (C) 2012 Elsevier B.V. All rights reserved.
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| 14. |
- Ambrosio, M, et al.
(author)
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The MACRO detector at Gran Sasso
- 2002
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In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 486:3, s. 663-707
-
Journal article (peer-reviewed)abstract
- MACRO was an experiment that ran in the Laboratori Nazionali del Gran Sasso from 1988 to 2000. Its principal goal was to observe magnetic monopoles or set significantly lower experimental flux limits than had been previously available in the velocity range from about beta = 10(-4) to unity. In addition it made a variety of other observations. Examples are: setting flux limits on other so far unobserved particles such as nuclearites and lightly ionizing particles, searching for WIMP annihilations in the Earth and the Sun and for neutrino bursts from stellar collapses in or near our Galaxy, and making measurements relevant to high energy muon and neutrino astronomy and of the flux of up-going muons as a function of nadir angle showing evidence for neutrino oscillations. The apparatus consisted of three principal types of detectors: liquid scintillator counters, limited streamer tubes, and nuclear track etch detectors. In addition, over part of its area it contained a transition radiation detector. The general design philosophy emphasized redundancy and complementarity. This paper describes the technical aspects of the complete MACRO detector, its operational performance, and the techniques used to calibrate it and verify its proper operation. It supplements a previously published paper which described the first portion of the detector that was built and operated. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 15. |
- Lukasik, J., et al.
(author)
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Discriminant analysis and secondary-beam charge recognition
- 2008
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In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 587:2-3, s. 413-419
-
Journal article (peer-reviewed)abstract
- The discriminant-analysis method has been applied to optimize the exotic-beam charge recognition in a projectile fragmentation experiment. The experiment was carried out at the GSI using the fragment separator (FRS) to produce and select the relativistic secondary beams, and the ALADIN setup to measure their fragmentation products following collisions with Sn target nuclei. The beams of neutron poor isotopes around La-124 and Sn-107 were selected to study the isospin dependence of the limiting temperature of heavy nuclei by comparing with results for stable Sn-124 projectiles. A dedicated detector to measure the projectile charge upstream of the reaction target was not used, and alternative methods had to be developed. The presented method, based on the multivariate discriminant analysis, allowed to increase the efficacy of charge recognition up to about 90%, which was about 20% more than achieved with the simple scalar methods.
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| 16. |
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| 17. |
- Trautmann, W., et al.
(author)
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Isotopic dependence of the caloric curve
- 2009
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In: Progress in Particle and Nuclear Physics. - : Elsevier BV. - 0146-6410. ; 62:2, s. 407-412
-
Journal article (peer-reviewed)abstract
- Isotopic effects in projectile fragmentation at relativistic energies have been studied with the ALADIN forward spectrometer at SIS. Stable and radioactive Sn and La beams with an incident energy of 600 MeV per nucleon have been used in order to explore a wide range of isotopic compositions. Chemical freeze-out temperatures are found to be nearly invariant with respect to the A/Z ratio of the produced spectator sources, consistent with predictions for expanded systems. Consequences for the proposed interpretation of chemical breakup temperatures as representing the limiting temperatures predicted by microscopic models are discussed. (C) 2009 Elsevier B.V. All rights reserved.
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| 18. |
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| 19. |
- Pawłowski, P., et al.
(author)
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Neutrons from projectile fragmentation at 600 MeV/nucleon
- 2023
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In: Physical Review C. - 2469-9993 .- 2469-9985. ; 108:4
-
Journal article (peer-reviewed)abstract
- The neutron emission in projectile fragmentation at relativistic energies was studied with the Large-Area-Neutron-Detector LAND coupled to the ALADIN forward spectrometer at the GSI Schwerionen-Synchrotron (SIS). Stable Sn124 and radioactive Sn107 and La124 beams with an incident energy of 600 MeV/nucleon were used to explore the N/Z dependence of the identified neutron source. A cluster-recognition algorithm is applied for identifying individual particles within the hit distributions registered with LAND. The obtained momentum distributions are extrapolated over the full phase space occupied by the neutrons from the projectile-spectator source. The mean multiplicities of spectator neutrons reach values of up to about 11 and depend strongly on the isotopic composition of the projectile. An effective source temperature of T≈2-5 MeV, monotonically increasing with decreasing impact parameter, is deduced from the transverse momentum distributions. For the interpretation of the data, calculations with the statistical multifragmentation model were performed. The variety of excited projectile spectators assumed to decay statistically is represented by an ensemble of excited sources with parameters determined previously from the fragment production observed in the same experiments. The obtained agreement is very satisfactory for more peripheral collisions where, according to the model, neutrons are mainly emitted during the secondary decays of excited fragments. The neutron multiplicity in more central collisions is underestimated, indicating that other sources besides the modeled statistical breakup contribute to the observed neutron yield. The choice made for the symmetry-term coefficient of the liquid-drop description of produced fragments has a weak effect on the predicted neutron multiplicities.
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| 20. |
- Aglietta, M, et al.
(author)
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The cosmic ray primary composition between 10(15) and 10(16) eV from Extensive Air Showers electromagnetic and TeV muon data
- 2004
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In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 20:6, s. 641-652
-
Journal article (peer-reviewed)abstract
- The cosmic ray primary composition in the energy range between 10(15) and 10(16) eV, i.e., around the "knee" of the primary spectrum, has been studied through the combined measurements of the EAS-TOP air shower array (2005 m a. s.l., 10(5) m(2) collecting area) and the MACRO underground detector (963 m.a.s.l., 3100 m w.e. of minimum rock overburden, 920 m(2) effective area) at the National Gran Sasso Laboratories. The used observables are the air shower size (N-c) measured by EAS-TOP and the muon number (N-mu) recorded by MACRO. The two detectors are separated on average by 1200 m of rock, and located at a respective zenith angle of about 30degrees. The energy threshold at the surface for muons reaching the MACRO depth is approximately 1.3 TeV. Such muons are produced in the early stages of the shower development and in a kinematic region quite different from the one relevant for the usual N-mu - N-e studies. The measurement leads to a primary composition becoming heavier at the knee of the primary spectrum, the knee itself resulting from the steepening of the spectrum of a primary light component (p, He) of Deltay = 0.7 +/- 0.4 at E-0 similar to 4 x 10(15) eV. The result confirms the ones reported from the observation of the low energy muons at the surface (typically in the GeV energy range), showing that the conclusions do not depend on the production region kinematics. Thus, the hadronic interaction model used (CORSIKA/QGSJET) provides consistent composition results from data related to secondaries produced in a rapidity region exceeding the central one. Such an evolution of the composition in the knee region supports the "standard" galactic acceleration/propagation models that imply rigidity dependent breaks of the different components.. and therefore breaks occurring at lower energies in the spectra of the light nuclei. (C) 2003 Elsevier B.V. All rights reserved.
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| 21. |
- Aglietta, M, et al.
(author)
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The cosmic ray proton, helium and CNO fluxes in the 100 TeV energy region from TeV muons and EAS atmospheric Cherenkov light observations of MACRO and EAS-TOP
- 2004
-
In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 21:3, s. 223-240
-
Journal article (peer-reviewed)abstract
- The primary cosmic ray (CR) proton, helium and CNO fluxes in the energy range 80-300 TeV are studied at the National Gran Sasso Laboratories by means of EAS-TOP (Campo Imperatore, 2005 m a.s.l.) and MACRO (deep underground, 3100 m w.e., the surface energy threshold for a muon reaching the detector being E-mu(th) approximate to 1.3 TeV). The measurement is based on: (a) the selection of primaries based on their energy/nucleon (i.e., with energy/nucleon sufficient to produce a muon with energy larger than 1.3 TeV) and the reconstruction of the shower geometry by means of the muons recorded by MACRO in the deep underground laboratories; (b) the detection of the associated atmospheric Cherenkov light (C.l.) signals by means of the C.l. detector of EAS-TOP. The C.l. density at core distance r > 100 m is directly related to the total primary energy E-0. Proton and helium ("p + He") and proton, helium and CNO ("p + He + CNO") primaries are thus selected at E-0 approximate to 80 TeV, and at E-0 similar or equal to 250 TeV, respectively. Their flux is measured: J(p+He)(80 TeV) = (1.8 +/- 0.4) x 10(-6) m(-1)-s(-1) sr(-1) TeV-1, and J(p+He+CNO)(250 TeV) = (1.1 +/- 0.3) x 10(-7) m(-2)-s(-1) sr(-1) TeV-1, their relative weights being J(p+He)(J(p+He+CNO)) over bar (250 TeV) = 0.78 +/- 0.17. By using the measurements of the proton spectrum obtained from the direct experiments and hadron flux data in the atmosphere, we obtain for the relative weights of the three components at 250 TeV: J(p) : J(He) : J(CNO) = (0.20 +/- 0.08) : (0.58 +/- 0.19) : (0.22 +/- 0.17). This corresponds to the dominance of helium over proton primaries at 100-1000 TeV, and a possible non-negligible contribution from CNO. The lateral distribution of Cherenkov light in Extensive Air Showers (EASs), which is related to the rate of energy deposit of the primary in the atmosphere, is measured for a selected proton and helium primary beam, and good agreement is found when compared with the one calculated with the CORSIKA/QGSJET simulation model. (C) 2004 Elsevier B.V. All rights reserved.
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| 22. |
- Ambrosio, M, et al.
(author)
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A combined analysis technique for the search for fast magnetic monopoles with the MACRO detector
- 2002
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In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 18:1, s. 27-41
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Journal article (peer-reviewed)abstract
- We describe a search method for fast moving (beta = v/c > 5 x 10(-3)) magnetic monopoles using simultaneously the scintillator, streamer tube and track-etch subdetectors of the MACRO apparatus. The first two subdetectors are used primarily for the identification of candidates while the track-etch one is used as the final tool for their rejection or confirmation. Using this technique, a first sample of more than two-years of data has been analyzed without any evidence of a magnetic monopole. We set a 90% CL upper limit to the local monopole flux of 1.5 x 10(-15) cm(-2) s(-1) sr(-1) in the velocity range 5 x 10(-3) less than or equal to beta less than or equal to 0.99 and for nucleon decay catalysis cross-section smaller than similar to1 mb (C) 2002 Elsevier Science B.V. All rights reserved.
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| 23. |
- Ambrosio, M, et al.
(author)
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Atmospheric neutrino oscillations from upward throughgoing muon multiple scattering in MACRO
- 2003
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In: Physics Letters B. - 0370-2693 .- 1873-2445. ; 566:1-2, s. 35-44
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Journal article (peer-reviewed)abstract
- The energy of atmospheric neutrinos detected by MACRO was estimated using multiple Coulomb scattering of upward throughgoing muons. This analysis allows a test of atmospheric neutrino oscillations, relying on the distortion of the muon energy distribution. These results have been combined with those coming from the upward throughgoing muon angular distribution only. Both analyses are independent of the neutrino flux normalization and provide strong evidence, above the for level, in favour of neutrino oscillations. (C) 2003 Published by Elsevier B.V.
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| 24. |
- Ambrosio, M, et al.
(author)
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Final results of magnetic monopole searches with the MACRO experiment
- 2002
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In: European Physical Journal C. - : Springer. - 1434-6044 .- 1434-6052. ; 25:4, s. 511-522
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Journal article (peer-reviewed)abstract
- We present the final results obtained by the MACRO experiment in the search for GUT magnetic monopoles in the penetrating cosmic radiation, for the range 4 x 10(-5) < 3 < 1. Several searches with all the MACRO sub-detectors (i.e. scintillation counters, limited streamer tubes and nuclear track detectors) were performed, both in stand alone and combined ways. No candidates were detected and a 90% Confidence Level (C.L.) upper limit to the local magnetic monopole flux was set at the level of 1.4 x 10(-16) cm(-2) s(-1) sr(-1). This result is the first experimental limit obtained in direct searches which is well below the Parker bound in the whole 3 range in which GUT magnetic monopoles are,expected.
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| 25. |
- Ambrosio, M, et al.
(author)
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Matter effects in upward-going muons and sterile neutrino oscillations
- 2001
-
In: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 517:1-2, s. 59-66
-
Journal article (peer-reviewed)abstract
- The angular distribution of upward-going muons produced by atmospheric neutrinos in the rock below the MACRO detector shows anomalies in good agreement with two flavor nu (mu) --> nu (tau) oscillations with maximum mixing and Deltam(2) around 0.0024 eV(2). Exploiting the dependence of magnitude of the matter effect on oscillation channel, and using a set of 809 upward-going muons observed in MACRO, we show that the two flavor nu (mu) --> nu (s) oscillation is disfavored with 99% C.L. with respect to nu (mu) --> nu (tau). (C) 2001 Elsevier Science B.V. All rights reserved.
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| 26. |
- Ambrosio, M, et al.
(author)
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Measurement of the residual energy of muons in the Gran Sasso underground laboratories
- 2003
-
In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 19:3, s. 313-328
-
Journal article (peer-reviewed)abstract
- The MACRO detector was located in the Hall B of the Gran Sasso underground laboratories under an average rock overburden of 3700 hg/cm(2). A transition radiation detector composed of three identical modules, covering a total horizontal area of 36 m(2), was installed inside the empty upper part of the detector in order to measure the residual energy of muons. This paper presents the measurement of the residual energy of single and double muons crossing the apparatus. Our data show that double muons are more energetic than single ones. This measurement is performed over a standard rock depth range from 3000 to 6500 hg/cm(2). (C) 2002 Elsevier Science B.V. All rights reserved.
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| 27. |
- Ambrosio, M, et al.
(author)
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Measurements of atmospheric muon neutrino oscillations, global analysis of the data collected with MACRO detector
- 2004
-
In: European Physical Journal C. - : Springer. - 1434-6044 .- 1434-6052. ; 36:3, s. 323-339
-
Journal article (peer-reviewed)abstract
- The final analysis of atmospheric neutrino events collected with the MACRO detector is presented. Three different classes of events, generated by neutrinos in different energy ranges, are studied looking at rates, angular distributions and estimated energies. The results are consistent for all the subsamples and indicate a flux deficit that depends on energy and path - length of neutrinos. The no - oscillation hypothesis is excluded at similar to 5sigma, while the hypothesis of nu(mu) --> nu(tau) oscillation gives a satisfactory description of all data. The parameters with highest probability in a two flavor scenario are sin(2) 2theta(m) = 1 and Deltam(2) = 0.0023 eV(2). This result is independent of the absolute normalization of the atmospheric neutrino fluxes. The data can also be used to put experimental constrain on this normalization.
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| 28. |
- Ambrosio, M, et al.
(author)
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Moon and Sun shadowing effect in the MACRO detector
- 2003
-
In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 20:2, s. 145-156
-
Journal article (peer-reviewed)abstract
- Using data collected by the MACRO experiment from 1989 to the end of its operations in 2000, we have studied in the underground muon flux the shadowing. effects due to both the Moon and the Sun. We have observed the shadow cast by the Moon at its apparent position with a significance of 6.5sigma. The Moon shadowing effect has been used to verify the pointing capability of the detector and to determine the instrument resolution for the search of muon excesses from any direction of the celestial sphere. The dependence of the effect on the geomagnetic field is clearly shown by splitting the data sample in day and night observations. The Sun shadow, observed with a significance of 4.6sigma is displaced by about 0.6degrees from its apparent position. In this case however the explanation resides in the configuration of the Solar and Interplanetary Magnetic Fields, which affect the propagation of cosmic ray particles between the Sun, and the Earth. The displacement of the Sun shadow with respect to the real Sun position has been used to establish an upper limit on the antimatter flux in cosmic rays of about 48% at 68% c.l. and primary energies of about 20 TeV. (C) 2003 Elsevier B.V. All rights reserved.
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| 29. |
- Ambrosio, M, et al.
(author)
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Muon energy estimate through multiple scattering with the MACRO detector
- 2002
-
In: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 492:3, s. 376-386
-
Journal article (peer-reviewed)abstract
- Muon energy measurement represents an important issue for any experiment addressing neutrino-induced up-going muon studies. Since the neutrino oscillation probability depends on the neutrino energy, a measurement of the muon energy adds an important piece of information concerning the neutrino system. We show in this paper how the MACRO limited streamer tube system can be operated in drift mode by using the TDCs included in the QTPs, an electronics designed for magnetic monopole search. An improvement of the space resolution is obtained, through an analysis of the multiple scattering of muon tracks as they pass through our detector. This information can be used further to obtain an estimate of the energy of muons crossing the detector. Here we present the results of two dedicated tests, performed at CERN PS-T9 and SPS-X7 beam lines, to provide a full check of the electronics and to exploit the feasibility of such a multiple scattering analysis. We show that by using a neural network approach, we are able to reconstruct the muon energy for E-mu < 40 GeV. The test beam data provide an absolute energy calibration, which allows us to apply this method to MACRO data. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 30. |
- Ambrosio, M, et al.
(author)
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Search for cosmic ray sources using muons detected by the MACRO experiment
- 2003
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In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 18:6, s. 615-627
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Journal article (peer-reviewed)abstract
- The MACRO underground detector at Gran Sasso Laboratory recorded 60 million secondary cosmic ray muons from February 1989 until December 2000. Different techniques were used to analyze this sample in search for density excesses from astrophysical point-like sources. No evidence for DC excesses for any source in an all-sky survey is reported. In addition, searches for muon excess correlated with the known binary periods of Cygnus X-3 and Hercules X-1, and searches for statistically significant bursting episodes from known gamma-ray sources are also proved negative. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 31. |
- Ambrosio, M, et al.
(author)
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Search for diffuse neutrino flux from astrophysical sources with MACRO
- 2003
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In: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 19:1, s. 1-13
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Journal article (peer-reviewed)abstract
- Many galactic and extragalactic astrophysical sources are currently considered promising candidates as high-energy neutrino emitters. Astrophysical neutrinos can be detected as upward-going muons produced in charged-current interactions with the medium surrounding the detector. The expected neutrino fluxes from various models start to dominate on the atmospheric neutrino background at neutrino energies above some tens of TeV. We present the results of a search for an excess of high-energy upward-going muons among the sample of data collected by MACRO during similar to5.8 years of effective running time. No significant evidence for this signal was found. As a consequence, an upper limit on the flux of upward-going muons from high-energy neutrinos was set at the level of 1.7 x 10(-14) cm(-2) s(-1) sr(-1). The corresponding upper limit for the diffuse neutrino flux was evaluated assuming a neutrino power law spectrum. Our result was compared with theoretical predictions and upper limits from other experiments. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 32. |
- Ambrosio, M, et al.
(author)
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Search for nucleon decays induced by GUT magnetic monopoles with the MACRO experiment
- 2002
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In: European Physical Journal C. - : Springer. - 1434-6044 .- 1434-6052. ; 26:2, s. 163-172
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Journal article (peer-reviewed)abstract
- The interaction of a Grand Unification Magnetic Monopole with a nucleon can lead to a barion-number violating process in which the nucleon decays into a lepton and one or more mesons (catalysis of nucleon decay). In this paper we report an experimental study of the effects of a catalysis process in the MACRO detector. Using a dedicated analysis we obtain new magnetic monopole (MM) flux upper limits at the level of similar to 3 (.) 10(-16) cm(-2) s(-1) sr(-1) for 1.1(.) 10(-4) less than or equal to \beta\ less than or equal to 5 (.) 10(-3), based on the search for catalysis events in the MACRO data. We also analyze the dependence of the MM flux limit on the catalysis cross section.
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| 33. |
- Ambrosio, M, et al.
(author)
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Search for the sidereal and solar diurnal modulations in the total MACRO muon data set
- 2003
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In: Physical Review D. Particles and fields. - : American Physical Society. - 0556-2821 .- 1089-4918. ; 67:4
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Journal article (peer-reviewed)abstract
- We have analyzed 44.3M single muons collected by MACRO from 1991 through 2000 in 2145 live days of operation. We have searched for the solar diurnal, apparent sidereal, and pseudosidereal modulation of the underground muon rate by computing hourly deviations of the muon rate from 6 month averages. We find evidence for statistically significant modulations with the solar diurnal and the sidereal periods. The amplitudes of these modulations are <0.1%, and are at the limit of the detector statistics. The pseudosidereal modulation is not statistically significant. The solar diurnal modulation is due to the daily atmospheric temperature variations at 20 km, the altitude of primary cosmic ray interactions with the atmosphere; MACRO is the deepest experiment to report this result. The sidereal modulation is in addition to the expected Compton-Getting modulation due to solar system motion relative to the local standard of rest; it represents motion of the solar system with respect to the galactic cosmic rays toward the galactic plane.
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| 34. |
- Duffy, J. Emmett, et al.
(author)
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A Pleistocene legacy structures variation in modern seagrass ecosystems
- 2022
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 119:32
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Journal article (peer-reviewed)abstract
- Distribution of Earth's biomes is structured by the match between climate and plant traits, which in turn shape associated communities and ecosystem processes and services. However, that climate-trait match can be disrupted by historical events, with lasting ecosystem impacts. As Earth's environment changes faster than at any time in human history, critical questions are whether and how organismal traits and ecosystems can adjust to altered conditions. We quantified the relative importance of current environmental forcing versus evolutionary history in shaping the growth form (stature and biomass) and associated community of eelgrass (Zostera marina), a widespread foundation plant of marine ecosystems along Northern Hemisphere coastlines, which experienced major shifts in distribution and genetic composition during the Pleistocene. We found that eelgrass stature and biomass retain a legacy of the Pleistocene colonization of the Atlantic from the ancestral Pacific range and of more recent within-basin bottlenecks and genetic differentiation. This evolutionary legacy in turn influences the biomass of associated algae and invertebrates that fuel coastal food webs, with effects comparable to or stronger than effects of current environmental forcing. Such historical lags in phenotypic acclimatization may constrain ecosystem adjustments to rapid anthropogenic climate change, thus altering predictions about the future functioning of ecosystems.
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| 35. |
- Duffy, J. Emmett, et al.
(author)
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Toward a Coordinated Global Observing System for Seagrasses and Marine Macroalgae
- 2019
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In: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 6
-
Research review (peer-reviewed)abstract
- In coastal waters around the world, the dominant primary producers are benthic macrophytes, including seagrasses and macroalgae, that provide habitat structure and food for diverse and abundant biological communities and drive ecosystem processes. Seagrass meadows and macroalgal forests play key roles for coastal societies, contributing to fishery yields, storm protection, biogeochemical cycling and storage, and important cultural values. These socio-economically valuable services are threatened worldwide by human activities, with substantial areas of seagrass and macroalgal forests lost over the last half-century. Tracking the status and trends in marine macrophyte cover and quality is an emerging priority for ocean and coastal management, but doing so has been challenged by limited coordination across the numerous efforts to monitor macrophytes, which vary widely in goals, methodologies, scales, capacity, governance approaches, and data availability. Here, we present a consensus assessment and recommendations on the current state of and opportunities for advancing global marine macrophyte observations, integrating contributions from a community of researchers with broad geographic and disciplinary expertise. With the increasing scale of human impacts, the time is ripe to harmonize marine macrophyte observations by building on existing networks and identifying a core set of common metrics and approaches in sampling design, field measurements, governance, capacity building, and data management. We recommend a tiered observation system, with improvement of remote sensing and remote underwater imaging to expand capacity to capture broad-scale extent at intervals of several years, coordinated with strati fied in situ sampling annually to characterize the key variables of cover and taxonomic or functional group composition, and to provide ground-truth. A robust networked system of macrophyte observations will be facilitated by establishing best practices, including standard protocols, documentation, and sharing of resources at all stages of work flow, and secure archiving of open-access data. Because such a network is necessarily distributed, sustaining it depends on close engagement of local stakeholders and focusing on building and long-term maintenance of local capacity, particularly in the developing world. Realizing these recommendations will producemore effective, efficient, and responsive observing, a more accurate global picture of change in vegetated coastal systems, and stronger international capacity for sustaining observations.
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| 36. |
- Reynolds, P., et al.
(author)
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Latitude, temperature and habitat complexity predict predation pressure in eelgrass beds across the Northern Hemisphere
- 2018
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In: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 99:1, s. 29-35
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Journal article (peer-reviewed)abstract
- Latitudinal gradients in species interactions are widely cited as potential causes or consequences of global patterns of biodiversity. However, mechanistic studies documenting changes in interactions across broad geographic ranges are limited. We surveyed predation intensity on common prey (live amphipods and gastropods) in communities of eelgrass (Zostera marina) at 48 sites across its Northern Hemisphere range, encompassing over 370 of latitude and four continental coastlines. Predation on amphipods declined with latitude on all coasts but declined more strongly along western ocean margins where temperature gradients are steeper. Whereas in situ water temperature at the time of the experiments was uncorrelated with predation, mean annual temperature strongly positively predicted predation, suggesting a more complex mechanism than simple increased metabolic activity at the time of predation. This large-scale biogeographic pattern was modified by local habitat characteristics; predation declined with higher shoot density both among and within sites. Predation rates on gastropods, by contrast, were uniformly low and varied little among sites. The high replication and geographic extent of our study not only provides additional evidence to support biogeographic variation in intensity, but also insight into the mechanisms that relate temperature and biogeographic gradients in species interactions.
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| 37. |
- Togo, V, et al.
(author)
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Calibrations of CR39 and Makrofol nuclear track detectors and search for exotic particles
- 2003
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In: Nuclear physics B, Proceedings supplements. - : Elsevier. - 0920-5632 .- 1873-3832. ; 125, s. 217-221
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Journal article (peer-reviewed)abstract
- We present the final results of the search for exotic massive particles in the cosmic radiation performed with the MACRO underground experiment. Magnetic monopoles and nuclearites flux upper limits obtained with the CR39 nuclear track subdetector, the scintillation and streamer tube subdetectors are given. Searches at high altitude with the SLIM experiment are in progress.
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| 38. |
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| 39. |
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| 41. |
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| 42. |
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| 43. |
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| 44. |
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| 45. |
- Wild, Edward, et al.
(author)
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Abnormal peripheral chemokine profile in Huntington's disease.
- 2011
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In: PLoS Currents. - 2157-3999. ; 3
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Journal article (peer-reviewed)abstract
- Huntington's disease (HD) is an inherited neurodegenerative disorder characterized by both neurological and systemic abnormalities. Immune activation is a well-established feature of the HD brain and we have previously demonstrated a widespread, progressive innate immune response detectable in plasma throughout the course of HD. In the present work we used multiplex ELISA to quantify levels of chemokines in plasma from controls and subjects at different stages of HD. We found an altered chemokine profile tracking with disease progression, with significant elevations of five chemokines (eotaxin-3, MIP-1β, eotaxin, MCP-1 and MCP-4) while three (eotaxin-3, MIP-1β and eotaxin) showed significant linear increases across advancing disease stages. We validated our results in a separate sample cohort including subjects at different stages of HD. Here we saw that chemokine levels (MCP-1 and eotaxin) correlated with clinical scores. We conclude that, like cytokines, chemokines may be linked to the pathogenesis of HD, and that immune molecules may be valuable in tracking and exploring the pathogenesis of HD.
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| 46. |
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| 47. |
- Brockmann, Sarah J., et al.
(author)
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CHCHD10 mutations p.R15L and p.G66V cause motoneuron disease by haploinsufficiency
- 2018
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In: Human Molecular Genetics. - : Oxford University Press. - 0964-6906 .- 1460-2083. ; 27:4, s. 706-715
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Journal article (peer-reviewed)abstract
- Mutations in the mitochondrially located protein CHCHD10 cause motoneuron disease by an unknown mechanism. In this study, we investigate the mutations p. R15L and p. G66V in comparison to wild-type CHCHD10 and the non-pathogenic variant p. P34S in vitro, in patient cells as well as in the vertebrate in vivo model zebrafish. We demonstrate a reduction of CHCHD10 protein levels in p. R15L and p. G66V mutant patient cells to approximately 50%. Quantitative real-time PCR revealed that expression of CHCHD10 p. R15L, but not of CHCHD10 p. G66V, is already abrogated at the mRNA level. Altered secondary structure and rapid protein degradation are observed with regard to the CHCHD10 p. G66V mutant. In contrast, no significant differences in expression, degradation rate or secondary structure of non-pathogenic CHCHD10 p. P34S are detected when compared with wild-type protein. Knockdown of CHCHD10 expression in zebrafish to about 50% causes motoneuron pathology, abnormal myofibrillar structure and motility deficits in vivo. Thus, our data show that the CHCHD10 mutations p. R15L and p. G66V cause motoneuron disease primarily based on haploinsufficiency of CHCHD10.
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