The invariant cross sections for forward charged-hadron production at zero angle in carbon–carbon collisions at a beam kinetic energy of 19.6 GeV per nucleon were measured at the U-70 accelerator in ...an experiment performed with the aid of a combined spectrometer including beam line 22 and detectors of the modified FODS setup. The beam line rigidity was varied between 7 and 70 GeV/
. The results are compared with the predictions of the FTFP model and a self-similar solution for nucleus–nucleus collisions.
The inclusive differential cross sections for the production of
and
mesons, protons, and antiprotons with momenta between 6 and 50 GeV/
c
and nuclear fragments of mass number
in the momentum range ...between 20 and 220 GeV/
c
were measured in carbon–lead collisions at a beam kinetic energy of 19.6 GeV per nucleon (
GeV). A comparison with the respective cross sections for carbon–carbon interactions is performed, and the dependence on the target mass number (
) is estimated. The present analysis shows that the observed particles originate predominantly from peripheral interactions.
The results of the simulation of the spectrometer acceptance for forward production of hadrons and nuclear fragments in nucleus−nucleus collisions at the U-70 accelerator complex are presented. The ...spectrometer is composed of beamline 22 of the U-70 accelerator and the detectors of the upgraded FODS facility with location of nuclear targets at the beamline head. The calculations have been performed in the virtual Monte Carlo environment of the ROOT package from the GEANT4 toolkit (version 4.10.02.p02). The passage of secondary hadrons (charged π and
K
mesons, protons, and antiprotons), secondary light nuclei (D, T), and heavier isotopes (He, Li, Be, B, and C) have been studied. In addition to the acceptance for each type of particles and nuclei, the coefficients of their escape from an ensemble due to decays and interactions during their passage through the spectrometer have been calculated.
A procedure for finding the trajectories of charged particles on the FODS (focusing double-arm spectrometer) is described, which includes channel calibration (
r
(
t
)-dependence) of drift detectors ...for calculating the coordinates of particles and reconstruction of tracks. The organization of time measurements and construction of a least-squares functional on their basis is considered. The criteria for selecting candidates for the tracks are discussed. A procedure has been developed for obtaining geodesic corrections for drift chambers and tubes at the analysis of physical events. Accuracies of measuring the coordinates in drift chambers of 600 μm and chambers on drift tubes of 500 μm were obtained. The distribution of particle trajectories in the target is given.
—
The issues of determining the momentum of charged particles at the focusing double-arm spectrometer (FODS) are discussed. The coordinate detectors are located at the exit from the analyzing magnet, ...while a profilometer of the center of gravity of the beam at the target during an accelerator cycle is at its entrance. ANSIS finite-element analysis software is used to obtain a regular grid of magnetic field vector values measured by the Hall sensor in a part of the magnet. The charged-particle momentum is determined based on the algorithm of decision tables with a polynomial approximation. Tables are produced by the Monte Carlo method by reconstructing the motion of a particle with a prescribed momentum in the magnetic field. The accuracies in determining the particle momentum and the particle production angles while accounting for the contributions from multiple scattering, measurement errors, and approximation uncertainties are presented. The distribution of the reconstructed trajectories in the target and the momentum spectrum of particles are shown.
Relative yields of high-
x
F
charged hadrons (
π
±
, К
±
,
р
,
p
¯
, and
d
) in proton–nucleus interactions at incident-proton momenta of 25 and 50 GeV/c were measured at an angle of 0° in the ...momentum range between 15 and 40 GeV/
c
. An upper limit on the forward production of two protons in proton–nucleus interactions at 50 GeV/
c
was estimated. The properties of a carbon beam with an energy of 25 GeV per nucleon and fragment yields in its interaction with nuclear targets were measured within a short exposure.
The inclusive differential cross sections for forward production of nuclear fragments at an angle of 0∘ in CC collisions at beam energy 20.5 GeV/nucleon (SNN=6.3GeV) are presented. Measurements have ...been performed at the U-70 Accelerator Complex (Protvino) using a combined spectrometer on base of the beamline. Fragments selection was carried out by measuring of ionization in scintillation counters taking into account the data from threshold Cherenkov counters and hadron calorimeter. Fragment mass was determined through Cherenkov light emission angle measured in the spectrometer of ring imaging Cherenkov radiation. Data are given for fragments with charge 1≤Z≤6, atomic number 1≤A≤10 and A/Z<3.4 with momenta from 20 to 210 GeV/c. The measurements are compared with Fritiof model, statistical models and theoretical parameterizations. The discovered differences between theory and experiment are discussed.
Small pad RPCs as detector for high granularity digital hadron calorimetry Ammosov, V.; Gapienko, V.; Ivanilov, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2004, Letnik:
533, Številka:
1-2
Journal Article
Recenzirano
Requirements for sampling hadron calorimetry with gaseous active medium and digital read-out for a future linear e+e--collider (FLC) are formulated. Monogap glass Resistive Plate Chamber (RPC) ...prototypes equipped with 1cm2 read-out pads and operated in saturated avalanche and streamer modes are studied as a possible detector for digital hadron calorimetry. Operating characteristics of the prototypes such as induced charges, efficiencies and fired pad multiplicities are measured for different gas mixtures, gas gap widths and anode thicknesses, electronics thresholds, beam incident angle and intensity. Choice of RPC working performance is outlined.
Exclusive electroproduction of
ω
mesons on unpolarized hydrogen and deuterium targets is studied in the kinematic region of
Q
2
>
1.0
GeV
2
, 3.0 GeV
<
W
<
6.3 GeV, and
-
t
′
<
0.2
GeV
2
. ...Results on the angular distribution of the
ω
meson, including its decay products, are presented. The data were accumulated with the HERMES forward spectrometer during the 1996–2007 running period using the 27.6 GeV longitudinally polarized electron or positron beam of HERA. The determination of the virtual-photon longitudinal-to-transverse cross-section ratio reveals that a considerable part of the cross section arises from transversely polarized photons. Spin density matrix elements are presented in projections of
Q
2
or
-
t
′
. Violation of
s
-channel helicity conservation is observed for some of these elements. A sizable contribution from unnatural-parity-exchange amplitudes is found and the phase shift between those amplitudes that describe transverse
ω
production by longitudinal and transverse virtual photons,
γ
L
∗
→
ω
T
and
γ
T
∗
→
ω
T
, is determined for the first time. A hierarchy of helicity amplitudes is established, which mainly means that the unnatural-parity-exchange amplitude describing the
γ
T
∗
→
ω
T
transition dominates over the two natural-parity-exchange amplitudes describing the
γ
L
∗
→
ω
L
and
γ
T
∗
→
ω
T
transitions, with the latter two being of similar magnitude. Good agreement is found between the HERMES proton data and results of a pQCD-inspired phenomenological model that includes pion-pole contributions, which are of unnatural parity.
PDF
