-
H. Anderhub,
M. Backes,
A. Biland,
V. Boccone,
I. Braun,
T. Bretz,
J. Buß,
F. Cadoux,
V. Commichau,
L. Djambazov, [......],
T. Steinbring,
F. Temme,
J. Thaele,
S. Tobler, G. Viertel,
P. Vogler,
R. Walter,
K. Warda,
Q. Weitzel,
M. Z"anglein
[show abstract]
[hide abstract]
ABSTRACT: The First G-APD Cherenkov Telescope (FACT) is designed to detect cosmic
gamma-rays with energies from several hundred GeV up to about 10 TeV using the
Imaging Atmospheric Cherenkov Technique. In contrast to former or existing
telescopes, the camera of the FACT telescope is comprised of solid-state
Geiger-mode Avalanche Photodiodes (G-APD) instead of photomultiplier tubes for
photo detection. It is the first full-scale device of its kind employing this
new technology. The telescope is operated at the Observatorio del Roque de los
Muchachos (La Palma, Canary Islands, Spain) since fall 2011. This paper
describes in detail the design, construction and operation of the system,
including hardware and software aspects. Technical experiences gained after one
year of operation are discussed and conclusions with regard to future projects
are drawn.
04/2013;
-
D. Abbaneo,
G. Abbiendi,
M. Abbrescia,
S. Abdullin,
A. Abdulsalam,
B.S. Acharya,
D. Acosta,
J.G. Acosta,
A. Adair,
W. Adam, [......],
M.H. Zoeller,
O. Zorba,
P. Zotto,
W. Zou,
G. Zumerle,
M. Zupan,
A. Zuranski,
R. Zuyeuski,
M. Zvada,
P. Zych
[show abstract]
[hide abstract]
ABSTRACT: The Higgs boson was postulated nearly five decades ago within the framework of the standard model of particle physics and
has been the subject of numerous searches at accelerators around the world. Its discovery would verify the existence of a
complex scalar field thought to give mass to three of the carriers of the electroweak force—the W+, W–, and Z0 bosons—as well as to the fundamental quarks and leptons. The CMS Collaboration has observed, with a statistical significance
of five standard deviations, a new particle produced in proton-proton collisions at the Large Hadron Collider at CERN. The
evidence is strongest in the diphoton and four-lepton (electrons and/or muons) final states, which provide the best mass resolution
in the CMS detector. The probability of the observed signal being due to a random fluctuation of the background is about 1
in 3 × 106. The new particle is a boson with spin not equal to 1 and has a mass of about 1.25 giga–electron volts. Although its measured
properties are, within the uncertainties of the present data, consistent with those expected of the Higgs boson, more data
are needed to elucidate the precise nature of the new particle.
Science 12/2012; 338(6114):1569-1575. · 31.20 Impact Factor
-
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
-
H Anderhub,
M Backes,
A Biland,
A Boller,
I Braun,
T Bretz,
V Commichau,
L Djambazov,
D Dorner,
C Farnier, [......],
R Rohlfs,
U Röser,
J -P Stucki,
J Thaele,
O Tibolla, G Viertel,
P Vogler,
R Walter,
K Warda,
Q Weitzel
[show abstract]
[hide abstract]
ABSTRACT: Within the FACT project, we construct a new type of camera based on Geiger-mode avalanche photodiodes (G-APDs). Compared to photomultipliers, G-APDs are more robust, need a lower operation voltage and have the potential of higher photon-detection efficiency and lower cost, but were never fully tested in the harsh environments of Cherenkov telescopes. The FACT camera consists of 1440 G-APD pixels and readout channels, based on the DRS4 (Domino Ring Sampler) analog pipeline chip and commercial Ethernet components. Preamplifiers, trigger system, digitization, slow control and power converters are integrated into the camera.
Journal of Instrumentation 01/2012; 7(01):C01073. · 1.87 Impact Factor
-
M. Aguilar,
J. Alcaraz,
J. Allaby,
B. Alpat,
G. Ambrosi,
H. Anderhub,
L. Ao,
A. Arefiev,
L. Arruda,
P. Azzarello, [......],
Z. P. Zhang,
D. X. Zhao,
F. Zhou,
Y. Zhou,
G. Y. Zhu,
W. Z. Zhu,
H. L. Zhuang,
A. Zichichi,
B. Zimmermann,
and P. Zuccon
[show abstract]
[hide abstract]
ABSTRACT: The variety of isotopes in cosmic rays allows us to study different aspects of the processes that cosmic rays undergo between the time they are produced and the time of their arrival in the heliosphere. In this paper, we present measurements of the isotopic ratios 2H/4He, 3He/4He, 6Li/7Li, 7Be/(9Be+10Be), and 10B/11B in the range 0.2-1.4 GeV of kinetic energy per nucleon. The measurements are based on the data collected by the Alpha Magnetic Spectrometer, AMS-01, during the STS-91 flight in 1998 June.
The Astrophysical Journal 07/2011; 736(2):105. · 6.02 Impact Factor
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M. Aguilar,
J. Alcaraz,
J. Allaby,
B. Alpat,
G. Ambrosi,
H. Anderhub,
L. Ao,
A. Arefiev,
L. Arruda,
P. Azzarello, [......],
Z. P. Zhang,
D. X. Zhao,
F. Zhou,
Y. Zhou,
G. Y. Zhu,
W. Z. Zhu,
H. L. Zhuang,
A. Zichichi,
B. Zimmermann,
and P. Zuccon
[show abstract]
[hide abstract]
ABSTRACT: Measurement of the chemical and isotopic composition of cosmic rays is essential for the precise understanding of their propagation in the galaxy. While the model parameters are mainly determined using the B/C ratio, the study of extended sets of ratios can provide stronger constraints on the propagation models. In this paper, the relative abundances of light-nuclei lithium, beryllium, boron, and carbon are presented. The secondary-to-primary ratios Li/C, Be/C, and B/C have been measured in the kinetic energy range 0.35-45 GeV nucleon–1. The isotopic ratio 7Li/6Li is also determined in the magnetic rigidity interval 2.5-6.3 GV. The secondary-to-secondary ratios Li/Be, Li/B, and Be/B are also reported. These measurements are based on the data collected by the Alpha Magnetic Spectrometer AMS-01 during the STS-91 space shuttle flight in 1998 June. Our experimental results are in substantial agreement with other measurements, where they exist. We describe our light-nuclei data with a diffusive-reacceleration model. A 10%-15% overproduction of Be is found in the model predictions and can be attributed to uncertainties in the production cross-section data.
The Astrophysical Journal 11/2010; 724(1):329. · 6.02 Impact Factor
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H Anderhub,
M. Backes,
A Biland,
A. Boller,
I. Braun,
T. Bretz,
S. Commichau,
V Commichau,
M. Domke,
D. Dorner, [......],
M. Rissi,
M. Ribordy,
U Röser,
L. S. Stark,
J. -P. Stucki,
O. Tibolla, G. Viertel,
P. Vogler,
K. Warda,
Q. Weitzel
[show abstract]
[hide abstract]
ABSTRACT: Geiger-mode Avalanche Photodiodes~(G-APD) bear the potential to significantly improve the sensitivity of Imaging Air Cherenkov Telescopes (IACT). We are currently building the First G-APD Cherenkov Telescope (FACT) by refurbishing an old IACT with a mirror area of 9.5 square meters and construct a new, fine pixelized camera using novel G-APDs. The main goal is to evaluate the performance of a complete system by observing very high energy gamma-rays from the Crab Nebula. This is an important field test to check the feasibility of G-APD-based cameras to replace at some time the PMT-based cameras of planned future IACTs like AGIS and CTA. In this article, we present the basic design of such a camera as well as some important details to be taken into account. Comment: Poster shown at HEAD 2010, Big Island, Hawaii, March 1-4, 2010
10/2010;
-
H Anderhub,
M. Backes,
A Biland,
A. Boller,
I. Braun,
T. Bretz,
S. Commichau,
V Commichau,
D. Dorner,
A. Gendotti, [......],
D Renker,
W. Rhode,
M. Rissi,
U Röser,
S. Rollke,
L. S. Stark,
J. -P. Stucki, G. Viertel,
P. Vogler,
Q. Weitzel
[show abstract]
[hide abstract]
ABSTRACT: Geiger-mode avalanche photodiodes (G-APD) are promising new sensors for light detection in atmospheric Cherenkov telescopes. In this paper, the design and commissioning of a 36-pixel G-APD prototype camera is presented. The data acquisition is based on the Domino Ring Sampling (DRS2) chip. A sub-nanosecond time resolution has been achieved. Cosmic-ray induced air showers have been recorded using an imaging mirror setup, in a self-triggered mode. This is the first time that such measurements have been carried out with a complete G-APD camera. Comment: 9 pages with 11 figures
11/2009;
-
A Moralejo,
C Baixeras,
D Bastieri,
W Bednarek,
C Bigongiari,
A Biland,
O Blanch,
R Böck,
T Bretz,
A Chilingarian, [......],
M Teshima,
N Tonello,
A Torres,
N Turini, G Viertel,
V Vitale,
S Volkov,
R Wagner,
T Wibig,
W Wittek
[show abstract]
[hide abstract]
ABSTRACT: The MAGIC telescope, presently at its commissioning phase, will become fully operative by the end of 2003. Placed at the Roque de los Muchachos Observatory (ORM) on the island of La Palma, MAGIC is the largest among new generation ground-based gamma ray telescopes, and will reach an energy threshold as low as 30 GeV. The range of the electromagnetic spectrum between 10 and 250 GeV remains to date mostly unexplored. Observations in this energy region are expected to provide key data for the understanding of a wide variety of astrophysical phenomena belonging to the so-called "non thermal Universe", like the processes in the nuclei of active galaxies, the radiation mechanisms of pulsars and supernova remnants, and the enigmatic gamma-ray bursts. An overview of the telescope and its physics goals is presented.
Chinese Journal of Astronomy and Astrophysics 04/2009; 3(S1):531. · 0.89 Impact Factor
-
The CMS Collaboration,
S Chatrchyan,
G Hmayakyan,
V Khachatryan,
A M Sirunyan,
W Adam,
T Bauer,
T Bergauer,
H Bergauer,
M Dragicevic, [......],
G Abdullaeva,
A Avezov,
M I Fazylov,
E M Gasanov,
A Khugaev,
Y N Koblik,
M Nishonov,
K Olimov,
A Umaraliev,
B S Yuldashev
[show abstract]
[hide abstract]
ABSTRACT: The Compact Muon Solenoid (CMS) detector is described. The detector operates at the Large Hadron Collider (LHC) at CERN. It was conceived to study proton-proton (and lead-lead) collisions at a centre-of-mass energy of 14 TeV (5.5 TeV nucleon-nucleon) and at luminosities up to 1034 cm−2 s−1 (1027 cm−2 s−1). At the core of the CMS detector sits a high-magnetic-field and large-bore superconducting solenoid surrounding an all-silicon pixel and strip tracker, a lead-tungstate scintillating-crystals electromagnetic calorimeter, and a brass-scintillator sampling hadron calorimeter. The iron yoke of the flux-return is instrumented with four stations of muon detectors covering most of the 4π solid angle. Forward sampling calorimeters extend the pseudorapidity coverage to high values (|η| ≤ 5) assuring very good hermeticity. The overall dimensions of the CMS detector are a length of 21.6 m, a diameter of 14.6 m and a total weight of 12500 t.
Journal of Instrumentation 08/2008; 3(08):S08004. · 1.87 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
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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. Adzic,
R. Alemany-Fernandez,
C.B. Almeida,
N.M. Almeida,
G. Anagnostou,
M.G. Anfreville,
I. Anicin,
Z. Antunovic,
E. Auffray,
S. Baccaro, [......],
I. Yaselli,
A. Zabi,
N. Zamiatin,
S. Zelepoukine,
M. Zeller,
L.Y. Zhang,
Y. Zhang,
K. Zhu,
R.Y. Zhu,
The CMS Electromagnetic Calorimeter Group
[show abstract]
[hide abstract]
ABSTRACT: The amplitude of the signal collected from the PbWO4 crystals of the CMS electromagnetic calorimeter is reconstructed by a digital filtering technique. The amplitude reconstruction
has been studied with test beam data recorded from a fully equipped barrel supermodule. Issues specific to data taken in the
test beam are investigated, and the implementation of the method for CMS data taking is discussed.
European Physical Journal C 06/2006; 46:23-35. · 3.63 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
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[show abstract]
[hide abstract]
ABSTRACT: The Alpha Magnetic Spectrometer (AMS) is a particle physics experiment based on the International Space Station (ISS). Its mission is to study cosmic rays in space, using a large superconducting magnet to deflect charged particles which can then be identified by a set of advanced detectors. This paper describes the design of the magnet cryogenic system, and the status of manufacture and testing. © 2006 American Institute of Physics
AIP Conference Proceedings. 04/2006; 823(1):1315-1322.
-
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
-
The CMS Electromagnetic Calorimeter Group,
P. Adzic,
R. Alemany-Fernandez,
C. B. Almeida,
N. M. Almeida,
G. Anagnostou,
M. G. Anfreville,
I. Anicin,
Z. Antunovic,
A. Asimidis, [......],
T. Virdee,
M. Wang,
J. H. Williams,
I. Yaselli,
N. Zamiatin,
S. Zelepoukine,
M. Zeller,
L. Y. Zhang,
K. Zhu,
R. Y. Zhu
[show abstract]
[hide abstract]
ABSTRACT: Performance tests of some aspects of the CMS ECAL were carried out on modules of the "barrel" sub-system in 2002 and 2003.
A brief test with high energy electron beams was made in late 2003 to validate prototypes of the new Very Front End electronics.
The final versions of the monitoring and cooling systems, and of the high and low voltage regulation were used in these tests.
The results are consistent with the performance targets including those for noise and overall energy resolution, required
to fulfil the physics programme of CMS at the LHC.
European Physical Journal C 12/2005; 44:1-10. · 3.63 Impact Factor
