-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
J H Field,
F. Filthaut,
W Fisher,
I Fisk,
G Forconi,
K. Freudenreich,
C Furetta,
Y. Galaktionov,
S N Ganguli,
P. Garcia-Abia
-
P. Bagnaia,
A. Bajo,
G. Baksay,
L. Baksay,
S. V. Baldew,
S. Banerjee,
A. Barczyk,
R. Barillere,
P. Bartalini,
M. Basile, [......],
R. van Gulik,
V. K. Gupta,
A. Gurtu,
L. J. Gutay,
D. Haas,
D. Hatzifotiadou,
T. Hebbeker,
A. Herve,
J. Hirschfelder,
H. Hofer
-
P. Bagnaia,
A. Bajo,
G. Baksay,
L. Baksay,
S. V. Baldew,
S. Banerjee,
A. Barczyk,
R. Barillere,
P. Bartalini,
M. Basile, [......],
R. van Gulik,
V. K. Gupta,
A. Gurtu,
L. J. Gutay,
D. Haas,
D. Hatzifotiadou,
T. Hebbeker,
A. Herve,
J. Hirschfelder,
H. Hofer
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
W Fisher,
G Forconi,
K. Freudenreich,
C Furetta,
Y. Galaktionov,
S N Ganguli,
P. Garcia-Abia,
M. Gataullin,
S Gentile,
S Giagu
-
E. Anassontzis,
M. Barone,
G. Contopoulos,
G. Fanourakis,
G. Grammatikakis,
P. Hatzios,
P. Ioannou,
G. Kalkanis,
S. Katsanevas,
C. Kourkoumelis, [......],
L. M. Zakarov,
I. M. Zheleznykh,
V. A. Zhukov,
A. P. Eremeev,
V. V. Ledenev,
M. N. Platonov,
V. K. Rucol,
N. A. Sheremet,
U. Camerini,
R. March
[show abstract]
[hide abstract]
ABSTRACT: A new program for an underwater neutrino astrophysics laboratory to be located in the international water off the Southwest of Greece, near the town of Pylos has now bee founded for the initial stage. In the last 2 years a group of physicista from Greece and Russia have carried out two demonstration experiments in 4 km deep water, counting muons and verifying the adequacy of the deep sea site. Plans are presented for a 100,000 m^2 high energy neutrino detector composed of a hexagon of hexagonal towers, with 1176 optical detector units. A progress is given and the physics potential of a single tower with 168 phototubes (currently under construction) is described.
-
S. Schael,
R. Barate,
R. Brunelière,
I. De Bonis,
D. Decamp,
C. Goy,
S. Jézéquel,
J.-P. Lees,
F. Martin,
E. Merle, [......],
G.W. Wilson,
J.A. Wilson,
T.R. Wyatt,
S. Yamashita,
D. Zer-Zion,
L. Zivkovic,
S. Heinemeyer,
A. Pilaftsis,
G. Weiglein,
The LEP Working Group for Higgs Boson Searches
[show abstract]
[hide abstract]
ABSTRACT: The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for the neutral Higgs bosons which are predicted by
the Minimal Supersymmetric standard model (MSSM). The data of the four collaborations are statistically combined and examined
for their consistency with the background hypothesis and with a possible Higgs boson signal. The combined LEP data show no
significant excess of events which would indicate the production of Higgs bosons. The search results are used to set upper
bounds on the cross-sections of various Higgs-like event topologies. The results are interpreted within the MSSM in a number
of “benchmark” models, including CP-conserving and CP-violating scenarios. These interpretations lead in all cases to large
exclusions in the MSSM parameter space. Absolute limits are set on the parameter cosβ and, in some scenarios, on the masses
of neutral Higgs bosons.
European Physical Journal C 04/2012; 47(3):547-587. · 3.63 Impact Factor
-
The Collaboration,
P. Achard,
O. Adriani,
M. Aguilar-Benitez,
J. Alcaraz,
G. Alemanni,
J. Allaby,
A. Aloisio,
M. G. Alviggi,
H. Anderhub, [......],
An. Zalite,
Yu. Zalite,
Z. P. Zhang,
J. Zhao,
G. Y. Zhu,
R. Y. Zhu,
H. L. Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zöller
[show abstract]
[hide abstract]
ABSTRACT: Bose–Einstein correlations of pairs of identical charged pions produced in hadronic Z decays are analyzed in terms of various
parametrizations. A good description is achieved using a Lévy stable distribution in conjunction with a model where a particle’s
momentum is correlated with its space–time point of production, the τ-model. Using this description and the measured rapidity and transverse momentum distributions, the space–time evolution of
particle emission in two-jet events is reconstructed. However, the elongation of the particle emission region previously observed
is not accommodated in the τ-model, and this is investigated using an adhoc modification.
European Physical Journal C 04/2012; 71(5):1-25. · 3.63 Impact Factor
-
O Adriani,
M. van den Akker,
T Aziz,
J. Bähr,
S Banerjee,
F Becattini,
L. Bellucci,
B L Betev,
J J Blaising,
G J. Bobbink, [......],
Z Q Yu,
C Zhang,
F Zhang,
J Zhang,
S Zhang,
S J Zhou,
G Y Zhu,
Q. Q. Zhu,
H L Zhuang,
A. N. M. Zwart
[show abstract]
[hide abstract]
ABSTRACT: The data collected by the L3+C muon spectrometer at the CERN Large Electron-Positron collider, LEP, have been used to search for short duration signals emitted by cosmic point sources. A sky survey performed from July to November 1999 and from April to November 2000 has revealed one single flux enhancement (chance probability = 2.6X10^{-3}) between the 17th and 20th of August 2000 from a direction with a galactic longitude of (265.02+-0.42)^° and latitude of (55.58+-0.24)^°. The energy of the detected muons was above 15 GeV.
Astroparticle Physics 03/2010; 33:24-39. · 3.22 Impact Factor
-
O. Adriani,
M. van den Akker,
T. Aziz,
J. Bähr,
S. Banerjee,
F. Becattini,
L. Bellucci,
B.L. Betev,
J.J. Blaising,
G.J. Bobbink, [......],
Z.Q. Yu,
C. Zhang,
F. Zhang,
J. Zhang,
S. Zhang,
S.J. Zhou,
G.Y. Zhu,
Q.Q. Zhu,
H.L. Zhuang,
A.N.M. Zwart
[show abstract]
[hide abstract]
ABSTRACT: The data collected by the L3+C muon spectrometer at the CERN Large Electron–Positron collider, LEP, have been used to search for short duration signals emitted by cosmic point sources. A sky survey performed from July to November 1999 and from April to November 2000 has revealed one single flux enhancement between the 17th and 20th of August 2000 from a direction with a galactic longitude of (265.02 ± 0.42)° and latitude of (55.58 ± 0.24)°. The energy of the detected muons was above 15 GeV.
Astroparticle Physics 03/2010; 33(1):24-39. · 3.22 Impact Factor
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
J Zhao,
S J Zhou,
G Y Zhu,
R Y Zhu,
Q. Q. Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoeller,
A. N. M. Zwart
[show abstract]
[hide abstract]
ABSTRACT: Context. Primary cosmic rays experience multiple deflections in the non-uniform galactic and heliospheric magnetic fields which may generate anisotropies. Aims. A study of anisotropies in the energy range between 100 and 500 GeV is performed. This energy range is not yet well explored. Methods. The L3 detector at the CERN electron-positron collider, LEP, is used for a study of the angular distribution of atmospheric muons with energies above 20 GeV. This distribution is used to investigate the isotropy of the time-dependent intensity of the primary cosmic-ray flux with a Fourier analysis. Results. A small deviation from isotropy at energies around 200 GeV is observed for the second harmonics at the solar frequency. No sidereal anisotropy is found at a level above 10(-4). The measurements were performed in the years 1999 and 2000.
Astronomy and Astrophysics 03/2008; 488:1093-1100. · 4.59 Impact Factor
-
P. Achard,
O. Adriani,
M. Aguilar-Benitez,
J. Alcaraz,
G. Alemanni,
J. Allaby,
A. Aloisio,
M.G. Alviggi,
H. Anderhub,
V.P. Andreev, [......],
Y. Zalite,
Z.P. Zhang,
J. Zhao,
G.Y. Zhu,
R.Y. Zhu,
H.L. Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zöller,
The Collaboration
[show abstract]
[hide abstract]
ABSTRACT: Measurements of inclusive production of the Λ, Ξ- and Ξ*(1530) baryons in two-photon collisions with the L3 detector at LEP are presented. The inclusive differential cross sections
for Λ and Ξ- are measured as a function of the baryon transverse momentum, pt, and pseudo-rapidity, η. The mean number of Λ, Ξ- and Ξ*(1530) baryons per hadronic two-photon event is determined in the kinematic range 0.4GeV<pt<2.5GeV, |η|<1.2. Overall agreement with the theoretical models and Monte Carlo predictions is observed. A search for inclusive
production of the pentaquark θ+(1540) in two-photon collisions through the decay θ+→pK0
S is also presented. No evidence for production of this state is found.
European Physical Journal C 12/2006; 49(2):395-410. · 3.63 Impact Factor
-
P. Achard,
O Adriani,
M Aguilar-Benítez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
James V Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
J Zhao,
S J Zhou,
G Y Zhu,
R Y Zhu,
Q. Q. Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M Zöller,
A. N. M. Zwart
[show abstract]
[hide abstract]
ABSTRACT: Several experiments have reported observations on possible correlations between the flux of high energy muons and intense solar flares. If confirmed, these observations would have significant implications for acceleration processes in the heliosphere able to accelerate protons and other ions to energies of at least tens of GeV. The solar flare of the 14 July 2000 offers a unique opportunity for the L3+C experiment to search for a correlated enhancement in the flux of muons using the L3 precision muon spectrometer. Its capabilities for observing a directional excess in the flux of muons above 15 GeV (corresponding to primary proton energies above 40 GeV) are presented along with observations made on the 14th of July 2000. We report an excess which appeared at a time coincident with the peak increase of solar protons observed at lower energies. The probability that the excess is a background fluctuation is estimated to be 1%. No similar excess of the muon flux was observed up to 1.5 hours after the solar flare time.
Astronomy and Astrophysics 11/2006; 456:351-357. · 4.59 Impact Factor
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
J Zhao,
S J Zhou,
G Y Zhu,
R Y Zhu,
Q. Q. Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M Zöller,
A. N. M. Zwart
[show abstract]
[hide abstract]
ABSTRACT: Aims.Several experiments have reported observations on possible correlations between the flux of high energy muons and intense solar flares. If confirmed, these observations would have significant implications for acceleration processes in the heliosphere able to accelerate protons and other ions to energies of at least tens of GeV. Methods: .The solar flare of the 14 of July 2000 offered a unique opportunity for the L3+C experiment to search for a correlated enhancement in the flux of muons using the L3 precision muon spectrometer. Its capabilities for observing a directional excess in the flux of muons above 15 GeV (corresponding to primary proton energies above 40 GeV) are presented along with observations made on the 14th of July 2000. Results: .We report an excess which appeared at a time coincident with the peak increase of solar protons observed at lower energies. The probability that the excess is a background fluctuation is estimated to be 1%. No similar excess of the muon flux was observed up to 1.5 h after the solar flare time.
Astronomy and Astrophysics 05/2006; 456:351-357. · 4.59 Impact Factor
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
J Zhao,
S J Zhou,
G Y Zhu,
R Y Zhu,
Q. Q. Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoller,
A. N. M. Zwart
[show abstract]
[hide abstract]
ABSTRACT: The L3+C muon detector at the CERN electron-positron collider, LEP, is used for the detection of very-high-energy cosmic gamma-ray sources through the observation of muons of energies above 20, 30, 50 and 100 GeV. Daily or monthly excesses in the rate of single-muon events pointing to some particular direction in the sky are searched for. The periods from mid July to November 1999, and April to November 2000 are considered. Special attention is also given to a selection of known gamma-ray sources. No statistically significant excess is observed for any direction or any particular source. (c) 2006 Elsevier B.V. All rights reserved.
Astroparticle Physics 03/2006; 25:298-310. · 3.22 Impact Factor
-
P. Achard,
O. Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J. Alcaraz,
G. Alemanni,
J. Allaby,
A. Aloisio,
M.G. Alviggi,
H. Anderhub, [......],
J. Zhao,
S.J. Zhou,
G.Y. Zhu,
R.Y. Zhu,
Q.Q. Zhu,
H.L. Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zöller,
A.N.M. Zwart
[show abstract]
[hide abstract]
ABSTRACT: The L3+C muon detector at the CERN electron–positron collider, LEP, is used for the detection of very-high-energy cosmic γ-ray sources through the observation of muons of energies above 20, 30, 50 and 100 GeV. Daily or monthly excesses in the rate of single-muon events pointing to some particular direction in the sky are searched for. The periods from mid July to November 1999, and April to November 2000 are considered. Special attention is also given to a selection of known γ-ray sources. No statistically significant excess is observed for any direction or any particular source.
Astroparticle Physics 03/2006; 25:298-310. · 3.22 Impact Factor
-
S. Straulino,
O. Adriani,
L. Bonechi,
M. Bongi, S. Bottai,
G. Castellini,
D. Fedele,
M. Grandi,
P. Papini,
S.B. Ricciarini,
P. Spillantini,
F. Taccetti,
E. Taddei,
E. Vannuccini
[show abstract]
[hide abstract]
ABSTRACT: The PAMELA apparatus has been assembled and it is ready to be launched in a satellite mission to study mainly the antiparticle component of cosmic rays. In this paper, the performances obtained for the silicon microstrip detectors used in the magnetic spectrometer are presented. This subdetector reconstructs the curvature of a charged particle in the magnetic field produced by a permanent magnet and consequently determines momentum and charge sign, thanks to a very good accuracy in the position measurements (better than in the bending coordinate). A complete simulation of the silicon microstrip detectors has been developed in order to investigate in great detail the sensor's characteristics. Simulated events have been then compared with data gathered from minimum ionizing particle (MIP) beams during the last years in order to tune free parameters of the simulation. Finally some either widely used or original position finding algorithms, designed for such kind of detectors, have been applied to events with different incidence angles. As a result of the analysis, a method of impact point reconstruction can be chosen, depending on both the particle's incidence angle and the cluster multiplicity, so as to maximize the capability of the spectrometer in antiparticle tagging.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 10/2005;
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
J Zhao,
S J Zhou,
G Y Zhu,
R Y Zhu,
Q. Q. Zhu,
H L Zhuang,
A. Zichichi,
B. Zimmermann,
M. Zoller,
A. N. M. Zwart
[show abstract]
[hide abstract]
ABSTRACT: The shadowing of high-energy cosmic rays by the Moon has been observed with a significance of 9.4 standard deviations with the L3 + C muon spectrometer at CERN. A significant effect of the Earth magnetic field is observed. Since no event deficit on the east side of the Moon has been observed, an upper limit at 90% confidence level on the antiproton to proton ratio of 0.11 is obtained for primary energies around 1 TeV. © 2005 Elsevier B.V. All rights reserved.
Astroparticle Physics 03/2005; 23:411-434. · 3.22 Impact Factor
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
F. Filthaut,
W Fisher,
I Fisk,
G Forconi,
K. Freudenreich,
C Furetta,
Y. Galaktionov,
S N Ganguli,
P. Garcia-Abia,
V.A. Naumov
[show abstract]
[hide abstract]
ABSTRACT: The absolute muon flux between 20 and 3000 GeV is measured with the L3 magnetic muon spectrometer for zenith angles ranging from 0degrees to 58degrees. Due to the large exposure of about 150 m**2 sr d, and the excellent momentum resolution of the L3 muon chambers, a precision of 2.3% at 150 GeV in the vertical direction is achieved. The ratio of positive to negative muons is studied between 20 and 500 GeV, and the average vertical muon charge ratio is found to be 1.285 +/- 0.003(stat.) +/-0.019(syst.).
Thw L3+C group dedicates this publication to the late Bianca Monteleoni.
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
J Zhao,
S J Zhou,
G Y Zhu,
R Y Zhu,
H L Zhuang,
Q. Q. Zhu,
A. Zichichi,
B. Zimmermann,
M. Zoller,
A. N. M. Zwart
[show abstract]
[hide abstract]
ABSTRACT: The absolute muon flux between 20 and 3000 GeV is measured with the L3 magnetic muon spectrometer for zenith angles ranging from 0degrees to 58degrees. Due to the large exposure of about 150 m**2 sr d, and the excellent momentum resolution of the L3 muon chambers, a precision of 2.3% at 150 GeV in the vertical direction is achieved. The ratio of positive to negative muons is studied between 20 and 500 GeV, and the average vertical muon charge ratio is found to be 1.285 +/- 0.003(stat.) +/-0.019(syst.).
(C) 2004 Elsevier B.V. All rights reserved.
Physics Letters B 08/2004; 598:15-32. · 3.95 Impact Factor
-
P. Achard,
O Adriani,
M. Aguilar-Benitez,
M. van den Akker,
J Alcaraz,
G. Alemanni,
J. Allaby,
A Aloisio,
M G Alviggi,
H Anderhub, [......],
J H Field,
F. Filthaut,
W Fisher,
I Fisk,
G Forconi,
K. Freudenreich,
C Furetta,
Y. Galaktionov,
S N Ganguli,
P. Garcia-Abia
