Abstract The measurements of the production of prompt $${{\mathrm{D}}^0}$$ D0 , $${{\mathrm{D}}^+}$$ D+ , $${{\mathrm{D}}^{*+}}$$ D∗+ , and $${{\mathrm{D}}^+_{\mathrm{s}}}$$ Ds+ mesons in ...proton–proton (pp) collisions at $$\sqrt{s}=5.02~\mathrm {TeV}$$ s=5.02TeV with the ALICE detector at the Large Hadron Collider (LHC) are reported. D mesons were reconstructed at mid-rapidity ($$|y|<0.5$$ |y|<0.5 ) via their hadronic decay channels $$\mathrm{D}^0 \rightarrow {\mathrm{K}}^-\pi ^+$$ D0→K-π+ , $$\mathrm{D}^+\rightarrow {\mathrm{K}}^-\pi ^+\pi ^+$$ D+→K-π+π+ , $${\mathrm{D}}^{*+} \rightarrow {\mathrm{D}}^0 \pi ^+ \rightarrow {\mathrm{K}}^- \pi ^+ \pi ^+$$ D∗+→D0π+→K-π+π+ , $${{\mathrm{D}}^{+}_{\mathrm{s}}\rightarrow \phi \pi ^+\rightarrow {\mathrm{K}}^{+} {\mathrm{K}}^{-} \pi ^{+}}$$ Ds+→ϕπ+→K+K-π+ , and their charge conjugates. The production cross sections were measured in the transverse momentum interval $$0<p_{\mathrm{T}}<36~\mathrm {GeV}/c$$ 0<pT<36GeV/c for $${{\mathrm{D}}^0}$$ D0 , $$1<p_{\mathrm{T}}<36~\mathrm {GeV}/c$$ 1<pT<36GeV/c for $${{\mathrm{D}}^+}$$ D+ and $${{\mathrm{D}}^{*+}}$$ D∗+ , and in $$2<p_{\mathrm{T}}<24~\mathrm {GeV}/c$$ 2<pT<24GeV/c for $${{\mathrm{D}}^+_{\mathrm{s}}}$$ Ds+ mesons. Thanks to the higher integrated luminosity, an analysis in finer $$p_{\mathrm{T}}$$ pT bins with respect to the previous measurements at $$\sqrt{s}=7~\mathrm {TeV}$$ s=7TeV was performed, allowing for a more detailed description of the cross-section $$p_{\mathrm{T}}$$ pT shape. The measured $$p_{\mathrm{T}}$$ pT -differential production cross sections are compared to the results at $$\sqrt{s}=7$$ s=7 TeV and to four different perturbative QCD calculations. Its rapidity dependence is also tested combining the ALICE and LHCb measurements in pp collisions at $$\sqrt{s}=5.02~\mathrm {TeV}$$ s=5.02TeV . This measurement will allow for a more accurate determination of the nuclear modification factor in p–Pb and Pb–Pb collisions performed at the same nucleon–nucleon centre-of-mass energy.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ϕ production in p-A and In-In collisions De Falco, Alessandro; Arnaldi, R.; Averbeck, R. ...
Nuclear Physics A,
2006, Letnik:
774
Journal Article, Conference Proceeding
Recenzirano
The NA60 experiment studied
ϕ meson production in p-A and In-In collisions at the CERN SPS. The ratio
ϕ
/
ω
shows an increase by a factor ∼2 from peripheral to central collisions. The inverse slope ...parameter T of the
p
T
spectrum increases with centrality, and seems to agree with the previous NA49 measurements.
The NA60 experiment studies muon pair production with proton and Indium beams. It is a second generation experiment, designed to answer specific questions left open, in the leptonic sector, by the ...previous round of SPS experiments, finished in 2000. The results presented in this paper cover the dimuon invariant mass range from the threshold to the J/
ψ. The main physics topics that we address include the in-medium modifications of the
ρ meson, the origin of the dimuon excess observed between the
ϕ and the J/
ψ, and the study of the anomalous J/
ψ suppression. For each of these subjects, the NA60 results represent a significant step forward towards a deeper understanding of the physics of heavy ion collisions at SPS energies.
Abstract The pseudorapidity density of charged particles, $$\mathrm {d}N_{\mathrm{ch}}/\mathrm {d}\eta $$ dNch/dη , in p–Pb collisions has been measured at a centre-of-mass energy per nucleon–nucleon ...pair of $$\sqrt{s_{\scriptscriptstyle {\mathrm{NN}}}$$ sNN = 8.16 TeV at mid-pseudorapidity for non-single-diffractive events. The results cover 3.6 units of pseudorapidity, $$|\eta |<1.8$$ |η|<1.8 . The $$\mathrm {d}N_{\mathrm{ch}}/\mathrm {d}\eta $$ dNch/dη value is $$19.1\pm 0.7$$ 19.1±0.7 at $$|\eta |<0.5$$ |η|<0.5 . This quantity divided by $$\langle N_{\mathrm{part}} \rangle $$ ⟨Npart⟩ / 2 is $$4.73\pm 0.20$$ 4.73±0.20 , where $$\langle N_{\mathrm{part}} \rangle $$ ⟨Npart⟩ is the average number of participating nucleons, is 9.5% higher than the corresponding value for p–Pb collisions at $$\sqrt{s_{\scriptscriptstyle {\mathrm{NN}}}$$ sNN = 5.02 TeV. Measurements are compared with models based on different mechanisms for particle production. All models agree within uncertainties with data in the Pb-going side, while HIJING overestimates, showing a symmetric behaviour, and EPOS underestimates the p-going side of the $$\mathrm {d}N_{\mathrm{ch}}/\mathrm {d}\eta $$ dNch/dη distribution. Saturation-based models reproduce the distributions well for $$\eta >-1.3$$ η>-1.3 . The $$\mathrm {d}N_{\mathrm{ch}}/\mathrm {d}\eta $$ dNch/dη is also measured for different centrality estimators, based both on the charged-particle multiplicity and on the energy deposited in the Zero-Degree Calorimeters. A study of the implications of the large multiplicity fluctuations due to the small number of participants for systems like p–Pb in the centrality calculation for multiplicity-based estimators is discussed, demonstrating the advantages of determining the centrality with energy deposited near beam rapidity.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract The ALICE Collaboration has measured the energy dependence of exclusive photoproduction of $$\mathrm {J}/\psi $$ J/ψ vector mesons off proton targets in ultra–peripheral p–Pb collisions at a ...centre-of-mass energy per nucleon pair $$\sqrt{s_\mathrm{NN}} = 5.02$$ sNN=5.02 TeV. The e$$^+$$ + e$$^-$$ - and $$\mu ^+\mu ^-$$ μ+μ- decay channels are used to measure the cross section as a function of the rapidity of the $$\mathrm {J}/\psi $$ J/ψ in the range $$-2.5< y < 2.7$$ -2.5<y<2.7 , corresponding to an energy in the $$\gamma $$ γ p centre-of-mass in the interval $$40< W_{\gamma \mathrm {p}}<550$$ 40<Wγp<550 GeV. The measurements, which are consistent with a power law dependence of the exclusive $$\mathrm {J}/\psi $$ J/ψ photoproduction cross section, are compared to previous results from HERA and the LHC and to several theoretical models. They are found to be compatible with previous measurements.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Spatial resolution of RPC in streamer mode Arnaldi, R.; Baldit, A.; Barret, V. ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,
09/2002, Letnik:
490, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
In the framework of an R&D program on the ALICE dimuon trigger system, the spatial resolution of Resistive Plate Chambers working in streamer mode has been investigated during beam tests. Preliminary ...studies with cosmic rays had evidenced a dependence of the charge profile to the high voltage and to the gas mixture. However, the spatial resolution measured from the beam tests is only slightly varying with the high voltage and is close to the expected value
w/
12
where w is the strip pitch, for strips of 1 and
2
cm
width. The probability to fire a strip as a function of the distance from the strip to the particle impact has been measured for various high voltages. A simple parametrisation of this probability has been achieved. This allows to predict, under various working condition, the cluster size distributions for RPCs with different strip widths and also to account for the effect of the particle incident angle.
Abstract First results on $$\hbox {K}/\pi $$ K/π , $$\hbox {p}/\pi $$ p/π and K/p fluctuations are obtained with the ALICE detector at the CERN LHC as a function of centrality in $$\text{ Pb--Pb }$$ ...Pb--Pb collisions at $$\sqrt{s_\mathrm{{NN}}} =2.76\hbox { TeV}$$ sNN=2.76TeV . The observable $$\nu _{\mathrm{dyn}}$$ νdyn , which is defined in terms of the moments of particle multiplicity distributions, is used to quantify the magnitude of dynamical fluctuations of relative particle yields and also provides insight into the correlation between particle pairs. This study is based on a novel experimental technique, called the Identity Method, which allows one to measure the moments of multiplicity distributions in case of incomplete particle identification. The results for $$\hbox {p}/\pi $$ p/π show a change of sign in $$\nu _{\mathrm{dyn}}$$ νdyn from positive to negative towards more peripheral collisions. For central collisions, the results follow the smooth trend of the data at lower energies and $$\nu _{\mathrm{dyn}}$$ νdyn exhibits a change in sign for $$\hbox {p}/\pi $$ p/π and K/p.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The study of dilepton production in heavy-ion collisions at the CERN SPS provided some of the most interesting observations done so far in the search for the quark gluon plasma. However, several ...aspects of the understanding of these measurements need to be clarified. For example, the study of the J/$\psi$ production in different colliding systems should help to distangle which is the variable driving the J/$_psi$ suppression. The NA60 experiment, with a new radiation tolerant Silicon pixel detector, studied Indium-Indium interactions in the year 2003. In this paper, we present the J/$\psi$/DY ratio, integrated over all the centralities of the collisions, together with a first study of the J/$\psi$ transverse momentum and polarization.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
70.
RPC for thermal neutron detection Arnaldi, R; Chiavassa, E; Colla, A ...
Journal of physics. Conference series,
05/2006, Letnik:
41, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The possibility to detect thermal neutrons with single gap Resistive Plate Chambers has been investigated. To detect neutrons a 10B4C thin coating on the inner surface of one RPC electrode is used as ...thermal neutron converter. The RPC detects the charged particles generated by neutrons via the (n, α) reaction on Boron. Tests on converter samples have been performed with a thermalized 252Cf source in order to evaluate the conversion efficiency: a good agreement between experimental results and simulation has been achieved. A detector prototype has been developed and tested on a low energy neutron beam at the European laboratories JRC in Belgium. A detailed description of the detector and the experimental test results are presented.
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