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Bellini, F.

Publications and source records attributed to Bellini, F..

396 records · Page 22
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DOE OSTI2014

Transverse momentum dependence of inclusive primary charged-particle production in p–Pb collisions at $\sqrt{s_\mathrm{{NN}}}=5.02~\text {TeV}$ = 5.02 TeV

The transverse momentum (p T ) distribution of primary charged particles is measured at midrapidity in minimum-bias p–Pb collisions at √s NN = 5.02 TeV with the ALICE detector at the LHC in the range. The spectra are compared to the expectation based on binary collision scaling of particle production in pp collisions, leading to a nuclear modification factor consistent with unity for p T larger than 2 GeV/c, with a weak indication of a Cronin-like enhancement for p T around 4 GeV/c. The measurement is compared to theoretical calculations and to data in Pb–Pb collisions at √s NN = 2.76 TeV.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2014

Search for axioelectric effect of solar axions using BGO scintillating bolometer

Here, a search for axioelectric absorption of solar axions produced in the p+d→ 3 He+γ (5.5 MeV) reaction has been performed with a BGO detector placed in a low-background setup. A model-independent limit on the combination of axion–nucleon and axion–electron coupling constants has been obtained: |g Ae x g$3\atop{AN}$| for 90 % confidence level. The constraint of the axion–electron coupling constant has been obtained for hadronic axion with masses of (0.1–1) MeV: |g Ae | ≤ (0.96 - 8.2) x 10 -8 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Measurement of quarkonium production at forward rapidity in pp collisions at √s = 7 TeV

The inclusive production cross sections at forward rapidity of J/ψ, ψ(2S), Y(1S) and Y(2S) are measured in pp collisions at √s = 7 TeV with the ALICE detector at the LHC. The analysis is based on a data sample corresponding to an integrated luminosity of 1.35 pb -1 . Quarkonia are reconstructed in the dimuon-decay channel and the signal yields are evaluated by fitting the μ + μ - invariant mass distributions. The differential production cross sections are measured as a function of the transverse momentum p T and rapidity y, over the ranges 0 < p T < 20 GeV/c for J/ψ, 0 < p T < 12 GeV/c for all other resonances and for 2.5 < y < 4. The measured cross sections integrated over p T and y, and assuming unpolarized quarkonia, are: σ J/ψ = 6.69 ± 0.04 ± 0.63 μb, σ ψ(2S) = 1.13 ± 0.07 ± 0.19 μb, σ Y(1S) = 54.2 ± 5.0 ± 6.7 nb and σ Y(2S) = 18.4 ± 3.7 ± 2.9 nb,where the first uncertainty is statistical and the second one is systematic. The results are compared to measurements performed by other LHC experiments and to theoretical models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Initial performance of the CUORE-0 experiment

CUORE-0 is a cryogenic detector that uses an array of tellurium dioxide bolometers to search for neutrinoless double-beta decay of 130 Te. We present the first data analysis with 7.1kg • y of total TeO 2 exposure focusing on background measurements and energy resolution. The background rates in the neutrinoless double-beta decay region of interest (2.47 to 2.57MeV) and in the α background-dominated region (2.70 to 3.90MeV) have been measured to be 0.071±0.011 and 0.019±0.002counts/(keV • kg • y), respectively. The latter result represents a factor of 6 improvement from a predecessor experiment, Cuoricino. The results verify our understanding of the background sources in CUORE-0, which is the basis of extrapolations to the full CUORE detector. The obtained energy resolution (full width at half maximum) in the region of interest is 5.7keV. Based on the measured background rate and energy resolution in the region of interest, CUORE-0 half-life sensitivity is expected to surpass the observed lower bound of Cuoricino with one year of live time.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

J/ψ production and nuclear effects in p-Pb collisions at $ \sqrt{{{{\mathrm{s}}_{\mathrm{NN}}}}} $ = 5.02 TeV

We studied inclusive J/ψ production with the ALICE detector in p-Pb collisions at the nucleon-nucleon center of mass energy √s NN = 5.02 TeV at the CERN LHC. The measurement is performed in the center of mass rapidity domains 2.03 < y cms < 3.53 and -4.46 < y cms < -2.96, down to zero transverse momentum, studying the μ + μ - decay mode. In this paper, the J/ψ production cross section and the nuclear modification factor R pPb for the rapidities under study are presented. Moreover, while at forward rapidity, corresponding to the proton direction, a suppression of the J/ψ yield with respect to binary-scaled pp collisions is observed, in the backward region no suppression is present. Finally, the ratio of the forward and backward yields is also measured differentially in rapidity and transverse momentum. Theoretical predictions based on nuclear shadowing, as well as on models including, in addition, a contribution from partonic energy loss, are in fair agreement with the experimental results.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Energy dependence of the transverse momentum distributions of charged particles in pp collisions measured by ALICE

Differential cross sections of charged particles in inelastic pp collisions as a function of p T have been measured at $\sqrt{s}$ = 0.9, 2.76 and 7 TeV at the LHC. The p T spectra are compared to NLO-pQCD calculations. Though the differential cross section for an individual √s cannot be described by NLO-pQCD, the relative increase of cross section with √s is in agreement with NLO-pQCD. Based on these measurements and observations, procedures are discussed to construct pp reference spectra at $\sqrt{s}$ = 2.76 and 5.02 TeV up to p T =50 GeV/c as required for the calculation of the nuclear modification factor in nucleus–nucleus and proton–nucleus collisions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Charmonium and e + e - pair photoproduction at mid-rapidity in ultra-peripheral Pb–Pb collisions at $\sqrt{s_{\mathrm{NN}}} $ = 2.76 TeV

The ALICE Collaboration at the LHC has measured the J/ψ and ψ' photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}} $ = 2.76 Tev. The charmonium is identified via its leptonic decay for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 23 μb -1 . The cross section for coherent and incoherent J/ψ production in the rapidity interval -0.9 < y < 0.9, are dσ coh J/ψ /dy = 2.38 +0.34 –0.24 (sta + sys) mb and dσ inc J/ψ /dy = 0.98 +0.19 –0.17 (sta + sys) mb, respectively. The results are compared to theoretical models for J/ψ production and the coherent cross section is found to be in good agreement with those models incorporating moderate nuclear gluon shadowing at Bjorken-x around 10 –3 , such as EPS09 parametrization. In addition the cross section for the process γγ→e + e – has been measured and found to be in agreement with models implementing QED at leading order.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

Current Status and Future Perspectives of the LUCIFER Experiment

In the field of fundamental particle physics, the neutrino has become more and more important in the last few years, since the discovery of its mass. In particular, the ultimate nature of the neutrino (if it is a Dirac or a Majorana particle) plays a crucial role not only in neutrino physics, but also in the overall framework of fundamental particle interactions and in cosmology. The only way to disentangle its ultimate nature is to search for the neutrinoless double beta decay. The idea of LUCIFER is to combine the bolometric technique proposed for the CUORE experiment with the bolometric light detection technique used in cryogenic dark matter experiments. The bolometric technique allows an extremely good energy resolution while its combination with the scintillation detection offers an ultimate tool for background rejection. The goal of LUCIFER is not only to build a background-free small-scale experiment but also to directly prove the potentiality of this technique. Preliminary tests on several detectors containing different interesting DBD emitters have clearly demonstrated the excellent background rejection capabilities that arise from the simultaneous, independent, double readout of heat and scintillation light.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Mid-rapidity anti-baryon to baryon ratios in pp collisions at $\sqrt{s} = 0.9,\ 2.76\mbox{ and }7\mbox{ TeV}$ measured by ALICE

The ratios of yields of anti-baryons to baryons probes the mechanisms of baryon-number transport. Results for \(\overline{\mathrm {p}}/{\mathrm{p}}\) , \(\overline{\Lambda}/{\Lambda}\) , \({{\overline{\Xi}}^{+}}/{\Xi ^{-}}\) and \({{\overline{\Omega}}^{+}}/{\Omega^{-}}\) in pp collisions at \(\sqrt{s} = 0.9,\ 2.76\mbox{ and }7\mbox{ TeV}\) , measured with the ALICE detector at the LHC, are reported. Within the experimental uncertainties and ranges covered by our measurement, these ratios are independent of rapidity, transverse momentum and multiplicity for all measured energies. The results are compared to expectations from event generators, such as PYTHIA and HIJING/B, that are used to model the particle production in pp collisions. The energy dependence of \(\overline{\mathrm{p}}/{\mathrm{p}}\) , \(\overline {\Lambda}/{\Lambda}\) , \({{\overline{\Xi}}^{+}}/{\Xi^{-}}\) and \({{\overline{\Omega}}^{+}}/{\Omega^{-}}\) , reaching values compatible with unity for \(\sqrt{s} = 7\mbox{ TeV}\) , complement the earlier \(\overline{\mathrm{p}}/{\mathrm{p}}\) measurement of ALICE. These dependencies can be described by exchanges with the Regge-trajectory intercept of \(\alpha_{\rm{J}} \approx0.5\) , which are suppressed with increasing rapidity interval Δ y . Any significant contribution of an exchange not suppressed at large Δ y (reached at LHC energies) is disfavoured.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurement of inelastic, single- and double-diffraction cross sections in proton–proton collisions at the LHC with ALICE

Measurements of cross sections of inelastic and diffractive processes in proton–proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass M X <200 GeV/ c 2 ) \(\sigma_{\mathrm{SD}}/\sigma_{\mathrm {INEL}} = 0.21 \pm 0.03, 0.20^{+0.07}_{-0.08}\) , and \(0.20^{+0.04}_{-0.07}\) , respectively at centre-of-mass energies \(\sqrt{s} = 0.9, 2.76\mbox{, and }7~\mbox{TeV}\) ; for double diffraction (for a pseudorapidity gap Δ η >3) σ DD / σ INEL =0.11±0.03,0.12±0.05, and \(0.12^{+0.05}_{-0.04}\) , respectively at \(\sqrt{s} = 0.9, 2.76\mbox{, and }7~\mbox{TeV}\) . To measure the inelastic cross section, beam properties were determined with van der Meer scans, and, using a simulation of diffraction adjusted to data, the following values were obtained: \(\sigma_{\mathrm{INEL}} = 62.8^{+2.4}_{-4.0} (\mathrm{model}) \pm1.2 (\mathrm{lumi})\) mb at \(\sqrt{s} = 2.76\ \mbox{TeV}\) and \(73.2^{+2.0}_{-4.6} (\mathrm{model}) \pm2.6 (\mathrm{lumi})~\mbox{mb}\) at \(\sqrt{s} = 7\ \mbox{TeV}\) . The single- and double-diffractive cross sections were calculated combining relative rates of diffraction with inelastic cross sections. The results are compared to previous measurements at proton–antiproton and proton–proton colliders at lower energies, to measurements by other experiments at the LHC, and to theoretical models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

The low energy spectrum of TeO{sub 2} bolometers: results and dark matter perspectives for the CUORE-0 and CUORE experiments

We collected 19.4 days of data from four 750 g TeO{sub 2} bolometers, and in three of them we were able to set the energy threshold around 3 keV using a new analysis technique. We found a background rate ranging from 25 cpd/keV/kg at 3 keV to 2 cpd/keV/kg at 25 keV, and a peak at 4.7 keV. The origin of this peak is presently unknown, but its presence is confirmed by a reanalysis of 62.7 kg·days of data from the finished CUORICINO experiment. Finally, we report the expected sensitivities of the CUORE-0 (52 bolometers) and CUORE (988 bolometers) experiments to a WIMP annual modulation signal.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

Production of K* (892) 0 and Φ (1020) in pp collisions at $\sqrt{s}$ = 7 TeV

>The production of K*(892) 0 and Φ (1020) in pp collisions at \(\sqrt{s}=7~\mathrm{TeV}\) was measured by the ALICE experiment at the LHC. The yields and the transverse momentum spectra d 2 N /d y d p T at midrapidity | y |<0.5 in the range 0< p T <6 GeV/ c for K * (892) 0 and 0.4< p T <6 GeV/ c for Φ (1020) are reported and compared to model predictions. Using the yield of pions, kaons, and Ω baryons measured previously by ALICE at \(\sqrt{s}=7\ \mathrm{TeV}\) , the ratios K*/K – , Φ /K * , Φ /K – , Φ / π – , and \((\Omega + \overline{\Omega })/\phi\) are presented. The values of the K*K – , Φ /K * and Φ /K – ratios are similar to those found at lower centre-of-mass energies. In contrast, the Φ / π – ratio, which has been observed to increase with energy, seems to saturate above 200 GeV. The \((\Omega + \overline {\Omega })/\phi\) ratio in the p T range 1–5 GeV/ c is found to be in good agreement with the prediction of the \(\mathrm{HIJING}/\mathrm{B}\overline{\mathrm{B}}\) v2.0 model with a strong colour field.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗