-
N. V. Rabin,
D. A. Vasil'ev,
S. V. Vladimirov,
A. G. Nekhaev,
V. T. Smolyankin,
V. I. Ushakov,
P. N. Shishov,
H. Bokemeyer,
W. Koenig,
W. Kuhn, [......],
I. Iori,
A. Kugler,
T. Marek,
R. Pleskac,
A. Taranenko,
A. Tikhonov,
P. Tlusty,
M. Benovic,
S. Hlavac,
I. Turzo
[show abstract]
[hide abstract]
ABSTRACT: The HADES spectrometer and a time-of-flight detector based on long-sized (50–250 cm) scintillation counters are described.
The detector is designed for identification of electrons, pions, and protons with momenta of 0.1–1.5 GeV/c at a flight distance of 220–250 cm. The operating conditions are analyzed, and the requirements to the detector and counter
design are formulated. The design of the counters and their arrangement in the spectrometer are considered. The results of
experimental studies of such characteristics of long counters as the light attenuation length in a scintillator and temporal
and spatial resolutions, dependeing on the location of the point of the particle’s hit on the counter, are presented. Analysis
of the data has shown that the main factor determining the spatial resolution of long counters is the quality of the polishing
of the side faces of the scintillators, which determines the effective (averaged over the scintillator side surfaces) coefficient
of total internal reflectionR. It is shown that, forR>-0.99, it is quite possible to achieve temporal and spatial resolutions of 100 ns and 2–3 cm, respectively, for scintillators
with a length of up to 250 cm and a cross section of 1–20 cm2. Foreign and Russian photomultipliers were used in the counters.
Instruments and Experimental Techniques 04/2012; 43(4):435-452. · 0.36 Impact Factor
-
The HADES Collaboration,
S. Spataro,
G. Agakishiev,
C. Agodi,
A. Balanda, G. Bellia,
D. Belver,
A. Belyaev,
A. Blanco,
M. Böhmer, [......],
I. Veretenkin,
V. Wagner,
H. Wen,
M. Wisniowski,
T. Wojcik,
J. Wüstenfeld,
S. Yurevich,
Y. Zanevsky,
P. Zhou,
P. Zumbruch
[show abstract]
[hide abstract]
ABSTRACT: The HADES spectrometer at GSI (Darmstadt) is investigating the e
+
e
- pair production in p+p, p+A and A+A collisions. In this contribution we would like to highlight the physics motivations and the experiments performed so far,
focusing mainly on the first results coming from 12C + 12C collisions at 1 and 2AGeV, and on preliminary results from p+p/d+p collisions at 1.25AGeV.
European Physical Journal A 04/2012; 38(2):163-166. · 2.19 Impact Factor
-
M. Sudol,
G. Agakishiev,
C. Agodi,
A. Balanda, G. Bellia,
D. Belver,
A. Belyaev,
J. Bielcik,
A. Blanco,
A. Bortolotti, [......],
H. Tsertos,
V. Wagner,
M. Weber,
M. Wisniowski,
T. Wojcik,
J. Wüstenfeld,
S. Yurevich,
Y. Zanevsky,
P. Zhou,
P. Zumbruch
[show abstract]
[hide abstract]
ABSTRACT: HADES is a secondary generation experiment operated at GSI Darmstadt with the main goal to study dielectron production in
proton, pion and heavy ion induced reactions. The first part of the HADES mission is to reinvestigate the puzzling pair excess
measured by the DLS collaboration in C + C and Ca + Ca collisions at 1 AGeV. For this purpose dedicated measurements with the C + C system at 1 and 2 AGeV were performed. The pair excess above a cocktail of free hadronic decays has been extracted and compared to the one measured
by DLS. Furthermore, the excess is confronted with predictions of various model calculations.
European Physical Journal C 04/2012; 62(1):81-84. · 3.63 Impact Factor
-
The HADES Collaboration,
G. Agakichiev,
C. Agodi,
H. Alvarez-Pol,
E. Atkin,
E. Badura,
A. Balanda,
A. Bassi,
R. Bassini, G. Bellia, [......],
M. Wisniowski,
T. Wojcik,
J. Wüstenfeld,
S. Yurevich,
Y. V. Zanevsky,
K. Zeitelhack,
A. Zentek,
P. Zhou,
D. Zovinec,
P. Zumbruch
[show abstract]
[hide abstract]
ABSTRACT: HADES is a versatile magnetic spectrometer aimed at studying dielectron production in pion, proton and heavy-ion-induced collisions.
Its main features include a ring imaging gas Cherenkov detector for electron-hadron discrimination, a tracking system consisting
of a set of 6 superconducting coils producing a toroidal field and drift chambers and a multiplicity and electron trigger
array for additional electron-hadron discrimination and event characterization. A two-stage trigger system enhances events
containing electrons. The physics program is focused on the investigation of hadron properties in nuclei and in the hot and
dense hadronic matter. The detector system is characterized by an 85% azimuthal coverage over a polar angle interval from
18° to 85° , a single electron efficiency of 50% and a vector meson mass resolution of 2.5%. Identification of pions, kaons and protons
is achieved combining time-of-flight and energy loss measurements over a large momentum range ( 0.1 < p < 1.0 GeV/c . This paper describes the main features and the performance of the detector system.
European Physical Journal A 04/2012; 41(2):243-277. · 2.19 Impact Factor
-
F.G.A. Quarati,
Alan Owens,
P. Dorenbos,
J.T.M. de Haas,
G. Benzoni,
N. Blasi,
C. Boiano,
S. Brambilla,
F. Camera,
R. Alba, G. Bellia,
C. Maiolino,
D. Santonocito,
M. Ahmed,
N. Brown,
S. Stave,
H.R. Weller,
Y.K. Wu
[show abstract]
[hide abstract]
ABSTRACT: Lanthanum bromide scintillation detectors produce very high light outputs (∼60,000 ph/MeV) within a very short decay time (typically ∼20 ns) which means that high instantaneous currents can be generated in the photocathode and dynode chain of the photomultiplier tube (PMT) used for the scintillation readout. The net result is that signal saturation can occur long before the recommended PMT biasing conditions can be reached.In search of an optimized light readout system for LaBr3, we have tested and compared two different PMT configurations for detection of gamma-rays up to 15 MeV. This range was chosen as being appropriate for gamma-ray remote sensing and medium energy nuclear physics applications. The experiments were conducted at two facilities: the Laboratori Nazionali del Sud (LNS) in Catania, Italy [1] and the High Intensity Gamma-ray Source (HIγS) at Triangle University Nuclear Laboratory, in Durham, North Carolina, USA [2].The PMT configurations we have tested are (1) a standard dynode chain operated under-biased; (2) a 4-stage reduced chain operated at nominal inter-dynode bias.The results are that shortening the number of active stages, as in configuration (2), has advantages in preserving energy resolution and avoiding PMT saturation over a large energy range.However, the use of an under-biased PMT, configuration (1), can still be considered a satisfactory solution, at least in the case of PMTs manufactured by Photonis.The results of this study will be used in support of the Mercury Gamma-ray and Neutron Spectrometer (MGNS) on board of BepiColombo, the joint ESA/JAXA mission to Mercury, scheduled for launch in 2014.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 03/2011; 629(1):157-169. · 1.21 Impact Factor
-
The HADES Collaboration,
F. Krizek,
G. Agakishiev,
A. Balanda, G. Bellia,
D. Belver,
A. Belyaev,
A Blanco,
M. Boehmer,
J. L. Boyard, [......],
H. Tsertos,
I. Veretenkin,
V. Wagner,
M Weber,
M. Wisniowski,
J. Wuestenfeld,
S. Yurevich,
Y. Zanevsky,
P Zhou,
P. Zumbruch
[show abstract]
[hide abstract]
ABSTRACT: Results of the HADES measurement of inclusive dielectron production in Ar+KCl collisions at a kinetic beam energy of 1.76 AGeV are presented. For the first time, high mass resolution spectroscopy was performed. The invariant mass spectrum of dielectrons is compared with predictions of UrQMD and HSD transport codes. Comment: 4 pages, 3 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennessee
07/2009;
-
The HADES Collaboration,
P. Tlusty,
G. Agakishiev,
A. Balanda, G. Bellia,
D. Belver,
A. Belyaev,
A Blanco,
M. Boehmer,
J. L. Boyard, [......],
H. Tsertos,
I. Veretenkin,
V. Wagner,
M Weber,
M. Wisniowski,
J. Wuestenfeld,
S. Yurevich,
Y. Zanevsky,
P Zhou,
P. Zumbruch
[show abstract]
[hide abstract]
ABSTRACT: Results of a study of charged pion production in 12C+12C collisions at incident beam energies of 1A GeV and 2A GeV, and 40Ar+natKCl at 1.76AGeV, using the spectrometer HADES at GSI, are presented. We have performed a measurement of the transverse momentum distributions of pi+- mesons covering a fairly large rapidity interval, in case of the C+C collision system for the first time. The yields, transverse mass and angular distributions are compared with a transport model as well as with existing data from other experiments. Comment: 7 pages, 2 figures Contribution presented at the XLVII International Winter Meeting on Nuclear Physics, Bormio (Italy), Jan. 26-30, 2009
06/2009;
-
The HADES Collaboration,
I. Froehlich,
G. Agakishiev,
A. Balanda, G. Bellia,
D. Belver,
A. Belyaev,
A Blanco,
M. Boehmer,
J. L. Boyard, [......],
H. Tsertos,
I. Veretenkin,
V. Wagner,
M Weber,
M. Wisniowski,
J. Wuestenfeld,
S. Yurevich,
Y. Zanevsky,
P Zhou,
P. Zumbruch
[show abstract]
[hide abstract]
ABSTRACT: Currently, the HADES spectrometer undergoes un upgrade program to be prepared for measurements at the upcoming SIS-100 synchrotron at FAIR. We describe the current status of the HADES di-electron measurements at the SIS-18 and our future plans for SIS-100. Comment: Invited contribution presented at the XLVII International Winter Meeting on Nuclear Physics, Bormio (Italy), Jan. 26-30, 2009
05/2009;
-
The HADES Collaboration,
G. Agakishiev,
C. Agodi,
A. Balanda, G. Bellia,
D. Belver,
A. Belyaev,
J. Bielcik,
A Blanco,
A. Bortolotti, [......],
H. Tsertos,
V. Wagner,
M Weber,
M. Wisniowski,
T. Wojcik,
J. Wuestenfeld,
S. Yurevich,
Y. Zanevsky,
P Zhou,
P. Zumbruch
[show abstract]
[hide abstract]
ABSTRACT: We present the results of a study of charged pion production in 12C + 12C collisions at incident beam energies of 1A GeV and 2A GeV using the HADES spectrometer at GSI. The main emphasis of the HADES program is on the dielectron signal from the early phase of the collision. Here, however, we discuss the data with respect to the emission of charged hadrons, specifically the production of pi+- mesons, which are related to neutral pions representing a dominant contribution to the dielectron yield. We have performed the first large-angular range measurement of the distribution of pi+- mesons for the 12C + 12C collision system covering a fairly large rapidity interval. The pion yields, transverse-mass and angular distributions are compared with calculations done within a transport model, as well as with existing data from other experiments. The anisotropy of pion production is systematically analyzed. Comment: 15 pages, 13 figures, v2 - the text unchanged, only full author list added to METADATA (in v1 only the first author and collaboration name), reference to published paper added
02/2009;
-
Eur.Phys.J. 01/2008; A38:163-166.
-
HADES Collaboration: G. Agakishiev,
C. Agodi,
H. Alvarez-Pol,
A. Balanda,
R. Bassini, G. Bellia,
D. Belver,
A. Belyaev,
A Blanco,
M. Boehmer, [......],
V. Wagner,
M Weber,
H Wen,
M. Wisniowski,
T. Wojcik,
J. Wuestenfeld,
S. Yurevich,
Y. Zanevsky,
P Zhou,
P. Zumbruch
[show abstract]
[hide abstract]
ABSTRACT: The emission of e+e- pairs from C+C collisions at an incident energy of 1 GeV per nucleon has been investigated. The measured production probabilities, spanning from the pi0-Dalitz to the rho/omega! invariant-mass region, display a strong excess above the cocktail of standard hadronic sources. The bombarding-energy dependence of this excess is found to scale like pion production, rather than like eta production. The data are in good agreement with results obtained in the former DLS experiment.
12/2007;
-
A. Kugler,
H. Agakichiev,
C. Agodi,
H. Alvarez‐Pol,
A. Balanda, G. Bellia,
D. Bertini,
J. Bielcik,
M. Böhmer,
H. Bokemeyer, [......],
A. Vazquez,
V. Wagner,
W. Walus,
M. Wiśniowski,
T. Wojcik,
J. Wüstenfeld,
Yu. Zanevsky,
K. Zeitelhack,
D. Zovinec,
P. Zumbruch
[show abstract]
[hide abstract]
ABSTRACT: The High‐Acceptance Di‐Electron Spectrometer installed at GSI Darmstadt is a second generation experiment to study production of dielectron pairs from proton, pion and nucleus induced reactions at the SIS∕BEVALAC energy regime. During period 2002–4 medium‐resolution data have been taken with HADES on the light C+C system at 1 and 2 AGeV. The data analysis confirms former finding of the DLS collaboration. First physics run on slightly heavier system Ar+KCl was carried out will almost full HADES setup at 2005.
AIP Conference Proceedings. 10/2007; 947(1):436-440.
-
J Markert,
G Agakishiev,
C Agodi,
A Balanda, G Bellia,
D Belver,
A Belyaev,
A Blanco,
M Böhmer,
J L Boyard, [......],
H Tsertos,
I Veretenkin,
V Wagner,
H Wen,
M Wisniowski,
T Wojcik,
J Wüstenfeld,
S Yurevich,
Y Zanevsky,
P Zumbruch
[show abstract]
[hide abstract]
ABSTRACT: We report on a measurement of electron pair production in 12C+12C collisions at an incident energy of 2 GeV per nucleon with the HADES spectrometer. The measured pair production probabilities span over five orders of magnitude from the π0-Dalitz to the ρ/ω invariant-mass region. Dalitz decays of π0 and η account for all the yield up to 0.15 GeV/c2, but for only about 50% above this mass. The excess yield is in agreement with the former DLS result if one assumes that it scales with beam energy like pion production. A preliminary analysis of 12C+12C collisions at an incident energy of 1 A GeV, measured with the HADES detector, supports this scenario.
Journal of Physics G Nuclear and Particle Physics 07/2007; 34(8):S1041. · 4.18 Impact Factor
-
G Agakichiev,
C Agodi,
H Alvarez-Pol,
A Bałanda,
D Bertini,
J Bielcik, G Bellia,
M Böhmer,
H Bokemeyer,
J L Boyard, [......],
A Vázquez,
V Wagner,
W Waluś,
M Wiśniowski,
T Wójcik,
J Wüstenfeld,
Y Zanevsky,
K Zeitelhack,
D Zovinec,
P Zumbruch
[show abstract]
[hide abstract]
ABSTRACT: The invariant-mass spectrum of e+e- pairs produced in 12C+12C collisions at an incident energy of 2 GeV per nucleon has been measured for the first time. The measured pair production probabilities span over 5 orders of magnitude from the pi(0)-Dalitz to the rho/omega invariant-mass region. Dalitz decays of pi(0) and eta account for all the yield up to 0.15 GeV/c(2), but for only about 50% above this mass. A comparison with model calculations shows that the excess pair yield is likely due to baryon-resonance and vector-meson decays. Transport calculations based on vacuum spectral functions fail, however, to describe the entire mass region.
Physical Review Letters 03/2007; 98(5):052302. · 7.37 Impact Factor
-
I. Fröhlich,
G. Agakishiev,
C. Agodi,
A. Balanda, G. Bellia,
D. Belver,
A. Belyaev,
A. Blanco,
M. Böhmer,
J. L. Boyard, [......],
R. Trebacz,
H. Tsertos,
I. Veretenkin,
V. Wagner,
H. Wen,
M. Wisniowski,
T. Wojcik,
J. Wüstenfeld,
Y. Zanevsky,
P. Zumbruch
[show abstract]
[hide abstract]
ABSTRACT: e
+
e
− production was studied using the High Acceptance DiElectron Spectrometer (HADES). In pp collisions at 2.2 GeV kinetic beam energy, the exclusive η production and the Dalitz decay η → γe
+
e
− have been reconstructed. The electromagnetic form factor of the latter decay was found to be in good agreement with the existing
theoretical predictions. In addition, an inclusive e
+
e
− invariant-mass spectrum from the 12C + 12C reaction at 2 AGeV is presented and compared with a simplified thermal model.
12/2006: pages 541-545;
-
G. Agakichiev,
C. Agodi,
H. Alvarez-Pol,
E. Badura,
A. Balanda,
R. Bassini, G. Bellia,
E. Berdermann,
D. Bertini,
J. Bielcik, [......],
R. Varma,
V. Wagner,
W. Walus,
S. Winkler,
M. Wisniowski,
T. Wojcik,
J. Wstenfeld,
Y. Zanevsky,
D. Zovinec,
P. Zumbruch
Nuclear Physics A 07/2006; 774:940-941. · 1.54 Impact Factor
-
W. Przygoda,
G. Agakishiev,
C. Agodi,
H. Alvarez-Pol,
A. Balanda,
R. Bassini, G. Bellia,
D. Belver,
J. Bielcik,
A. Blanco, [......],
I. Turzo,
V. Wagner,
W. Walus,
C. Willmott,
S. Winkler,
M. Wisniowski,
T. Wojcik,
J. Wuestenfeld,
Y. Zanevsky,
P. Zumbruch
Acta Physica Polonica Series B 12/2005; 37:139. · 0.90 Impact Factor
-
P. M. Milazzo,
G. Vannini,
C. Agodi,
R. Alba, G. Bellia,
N. Colonna,
R. Coniglione,
A. Del Zoppo,
P. Finocchiaro,
F. Gramegna,
I. Iori,
C. Maiolino,
G. V. Margagliotti,
P. F. Mastinu,
E. Migneco,
A. Moroni,
P. Piattelli,
R. Rui,
D. Santonocito,
P Sapienza
[show abstract]
[hide abstract]
ABSTRACT: The results of experiments performed to investigate the Ni+Al, Ni+Ni, Ni+Ag
reactions at 30 MeV/nucleon are presented. From the study of dissipative
midperipheral collisions, it has been possible to detect events in which
Intermediate Mass Fragments (IMF) production takes place. The decay of a
quasi-projectile has been identified; its excitation energy leads to a
multifragmentation totally described in terms of a statistical disassembly of a
thermalized system (T$\simeq$4 MeV, E$^*\simeq$4 MeV/nucleon). Moreover, for
the systems Ni+Ni, Ni+Ag, in the same nuclear reaction, a source with velocity
intermediate between that of the quasi-projectile and that of the quasi-target,
emitting IMF, is observed. The fragments produced by this source are more
neutron rich than the average matter of the overall system, and have a charge
distribution different, with respect to those statistically emitted from the
quasi-projectile. The above features can be considered as a signature of the
dynamical origin of the midvelocity emission. The results of this analysis show
that IMF can be produced via different mechanisms simultaneously present within
the same collision. Moreover, once fixed the characteristics of the
quasi-projectile in the three considered reactions (in size, excitation energy
and temperature), one observes that the probability of a partner IMF production
via dynamical mechanism has a threshold (not present in the Ni+Al case) and
increases with the size of the target nucleus.
03/2005;
-
A Kugler,
H Agakichiev,
Bassi,
R Bassini~, G Bellia~~ '~,
D Bertini,
J Bielcik,
M B~hmer,
C Bo~ano,
H Bokemeyer, [......],
S Winkler,
M Wisniowski,
T Wojcik~,
J Wosti,
Nfeld '~,
N Yahlali~,
! Anevsky '~,
K ~eitelhack,
D Zovinec~,
P ~umbruch
Nuclear Physics A 06/2004; 734:78. · 1.54 Impact Factor
-
P. Salabura,
G. Agakichiev,
C. Agodi,
H. Alvarez-Pol,
A. Balanda, G. Bellia,
D. Belver,
J. Bielcik,
M. Boehmer,
H. Bokemeyer, [......],
A. Vazquez,
Y. Volkov,
V. Wagner,
W. Walus,
S. Winkler,
M. Wisniowski,
T. Wojcik,
J. Wuestenfeld,
Y. Zanevsky,
P. Zumbruch
[show abstract]
[hide abstract]
ABSTRACT: HADES is a second generation experiment designed to study dielectron
production in proton, pion, and heavy ion induced reactions at the GSI
accelerator facility in Darmstadt. The physics programme of HADES is
focused on in-medium properties of the light vector mesons. In this
contribution we discuss relevance of dielectron spectroscopy to the
problem of hadron mass origin. We present status of the HADES
experiment, demonstrate its capability to identify rare dielectron
signal and show first experimental results obtained from C+C reactions
at 2 AGeV.
Acta Physica Polonica Series B 02/2004; 35:1119. · 0.90 Impact Factor
