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Bellini, F.

Publications and source records attributed to Bellini, F..

At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Measurement of electrons from heavy-flavour hadron decays as a function of multiplicity in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

The multiplicity dependence of electron production from heavy-flavour hadron decays as a function of transverse momentum was measured in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV using the ALICE detector at the LHC. The measurement was performed in the centre-of-mass rapidity interval -1.07 < y cms < 0.14 and transverse momentum interval 2 < p T < 16 GeV/c. The multiplicity dependence of the production of electrons from heavy-flavour hadron decays was studied by comparing the p T spectra measured for different multiplicity classes with those measured in pp collisions (Q pPb ) and in peripheral p-Pb collisions (Q cp ). The Q pPb results obtained are consistent with unity within uncertainties in the measured p T interval and event classes. This indicates that heavy-flavour decay electron production is consistent with binary scaling and independent of the geometry of the collision system. Additionally, the results suggest that cold nuclear matter effects are negligible within uncertainties, in the production of heavy-flavour decay electrons at midrapidity in p-Pb collisions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Studies of J/ψ production at forward rapidity in Pb–Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

The inclusive J/ψ production in Pb–Pb collisions at the center-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV, measured with the ALICE detector at the CERN LHC, is reported. The J/ψ meson is reconstructed via the dimuon decay channel at forward rapidity (2.5 < y < 4) down to zero transverse momentum. The suppression of the J/ψ yield in Pb–Pb collisions with respect to binary-scaled pp collisions is quantified by the nuclear modification factor (R AA ). The R AA at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV is presented and compared with previous measurements at $\sqrt{s_{\mathrm{NN}}}$= 2.76 TeV as a function of the centrality of the collision, and of the J/ψ transverse momentum and rapidity. The inclusive J/ψ R AA shows a suppression increasing toward higher transverse momentum, with a steeper dependence for central collisions. The modification of the J/ψ average transverse momentum and average squared transverse momentum is also studied. Comparisons with the results of models based on a transport equation and on statistical hadronization are carried out.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

The CUPID-Mo experiment for neutrinoless double-beta decay: performance and prospects

CUPID-Mo is a bolometric experiment to search for neutrinoless double-beta decay ($0\nu\beta\beta$) of $^{100}$Mo. In this article, we detail the CUPID-Mo detector concept, assembly, installation in the underground laboratory in Modane in 2018, and provide results from the first datasets. The demonstrator consists of an array of 20 scintillating bolometers comprised of $^{100}$Mo-enriched 0.2 kg Li$_2$MoO$_4$ crystals. The detectors are complemented by 20 thin cryogenic Ge bolometers acting as light detectors to distinguish $\alpha$ from $\gamma$/$\beta$ events by the detection of both heat and scintillation light signals. We observe good detector uniformity, facilitating the operation of a large detector array as well as excellent energy resolution of 5.3 keV (6.5 keV) FWHM at 2615 keV, in calibration (physics) data. Based on the observed energy resolutions and light yields a separation of $\alpha$ particles at much better than 99.9\% with equally high acceptance for $\gamma$/$\beta$ events is expected for events in the region of interest for $^{100}$Mo $0\nu\beta\beta$. We present limits on the crystals' radiopurity ($\leq$3 $\mu$Bq/kg of $^{226}$Ra and $\leq$2 $\mu$Bq/kg of $^{232}$Th). Based on these initial results we also discuss a sensitivity study for the science reach of the CUPID-Mo experiment, in particular, the ability to set the most stringent half-life limit on the $^{100}$Mo $0\nu\beta\beta$ decay after half a year of livetime. In conclusion, the achieved results show that CUPID-Mo is a successful demonstrator of the technology - developed in the framework of the LUMINEU project - selected for the CUPID experiment, a proposed follow-up of CUORE, the currently running first tonne-scale cryogenic $0\nu\beta\beta$ experiment.

100Mo↗
DOE OSTI2019

Measurement of prompt D 0 , D + , D *+ , and DS+$ {\mathrm{D}}_{\mathrm{S}}^{+} $ production in p–Pb collisions at sNN$ \sqrt{{\mathrm{s}}_{\mathrm{NN}}} $ = 5.02 TeV

The measurement of the production of prompt D 0 , D + , D *+, and $D_S^+$ mesons in proton–lead (p–Pb) collisions at the centre-of-mass energy per nucleon pair of \mathrm{\sqrt{s_{NN}}}$ = 5.02 TeV, with an integrated luminosity of 292 ± 11 μb -1 , are reported. Differential production cross sections are measured at mid-rapidity (-96 < y cms < 0.04) as a function of transverse momentum (p T ) in the intervals 0 < p T < 36 GeV/c for D 0 , 1 < p T < 36 GeV/c for D + and D *+ , and 2 < p T < 24 GeV/c for D + mesons. For each species, the nuclear modification factor R pPb is calculated as a function of p T using a proton-proton (pp) reference measured at the same collision energy. The results are compatible with unity in the whole p T range. The average of the non-strange D mesons R pPb is compared with theoretical model predictions that include initial-state effects and parton transport model predictions. The p T dependence of the D 0 , D + , and D *+ nuclear modification factors is also reported in the interval 1 < p T < 36 GeV/c as a function of the collision centrality, and the central-to-peripheral ratios are computed from the D-meson yields measured in different centrality classes. The results are further compared with charged-particle measurements and a similar trend is observed in all the centrality classes. The ratios of the p T -differential cross sections of D 0 , D + , D *+ , and $D_S^+$ mesons are also reported. The $D_S^+$ and D + yields are compared as a function of the charged-particle multiplicity for several p T intervals. No modification in the relative abundances of the four species is observed with respect to pp collisions within the statistical and systematic uncertainties.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

First results from the CUORE experiment

CUORE (Cryogenic Underground Observatory for Rare Events) is a ton-scale experiment aiming to the search of neutrino-less double beta decay in 130 Te with a projected sensitivity on the Majorana effective mass close to the inverted hierarchy region. The CUORE detector consists of a segmented array of 988 TeO 2 bolometers, organized in 19 towers and operated at a temperature of about 10 mK thanks to a custom cryogenic system which, besides the uncommon scale, observes several constraints from the radio-purity of the materials to the mechanical decoupling of the cooling systems. The successful commissioning of the CUORE cryogenic system has been completed early in 2016 and represents an outstanding achievement by itself. The installation of the detector proceeded along 2016 followed by the cooldown to base temperature at the beginning of 2017. The CUORE detector is now operational and has been taking science data since Spring 2017. With the first ~3 weeks of collected data, we present here the most stringent constraint on the 130 Te half-live for the neutrino-less double beta decay.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Initial performance of the CUORE detector

CUORE, the Cryogenic Underground Observatory for Rare Events, is an experiment searching for the neutrinoless double-beta decay of 130 Te. The first CUORE dataset was acquired in May and June 2017 and consisted of 10.6 kg-yr of TeO 2 exposure, with several days of calibration data before and after the physics dataset. We discuss here the initial performance of the CUORE detector and cryostat in this first dataset.

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Measurement of the inclusive isolated photon production cross section in p p collisions at $\sqrt{s}$ =7 TeV

The production cross section of inclusive isolated photons has been measured by the ALICE experiment at the CERN LHC in pp collisions at a centre-of-momentum energy of √s= 7 TeV. The measurement is performed with the electromagnetic calorimeter EMCal and the central tracking detectors, covering a range of |η| < 0.27 in pseudorapidity and a transverse momentum range of 10< p γ T <60 GeV/c. The result extends the p T coverage of previously published results of the ATLAS and CMS experiments at the same collision energy to smaller p T . The measurement is compared to next-to-leading order perturbative QCD calculations and to the results from the ATLAS and CMS experiments. All measurements and theory predictions are in agreement with each other.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Charged-particle production as a function of multiplicity and transverse spherocity in pp collisions at $ \sqrt{s}$ = 5.02 and 13 TeV

Here, we present a study of the inclusive charged-particle transverse momentum ( p T ) spectra as a function of charged-particle multiplicity density at mid-pseudorapidity, d N ch /dη, in pp collisions at $ \sqrt{s}$ = 5.02 and 13 TeV covering the kinematic range |η| < 0.8 and 0.15 < p T < 20 GeV/ c . The results are presented for events with at least one charged particle in |η| < 1 (INEL>0). The p T spectra are reported for two multiplicity estimators covering different pseudorapidity regions. The p T spectra normalized to that for INEL>0 show little energy dependence. Moreover, the high- p T yields of charged particles increase faster than the charged-particle multiplicity density. The average p T as a function of multiplicity and transverse spherocity is reported for pp collisions at $ \sqrt{s}$=13 TeV. For low- (high-) spherocity events, corresponding to jet-like (isotropic) events, the average p T is higher (smaller) than that measured in INEL>0 pp collisions. Within uncertainties, the functional form of &lang; p T &rang; ( N ch ) is not affected by the spherocity selection. While EPOS LHC gives a good description of many features of data, PYTHIA overestimates the average p T in jet-like events.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Inclusive J/ψ production at mid-rapidity in pp collisions at $\sqrt{s}$ = 5.02 TeV

Inclusive J/ψ production is studied in minimum-bias proton-proton collisions at a centre-of-mass energy of √s = 5.02 TeV by ALICE at the CERN LHC. The measurement is performed at mid-rapidity (|y| < 0.9) in the dielectron decay channel down to zero transverse momentum p T , using a data sample corresponding to an integrated luminosity of L int = 19.4 ± 0.4 nb -1 . The measured p T -integrated inclusive J/ψ production cross sec- tion is dσ/dy = 5.64 ± 0.22(stat.) ± 0.33(syst.) ± 0.12(lumi.) μb. The p T -differential cross section d 2 σ/dp T dy is measured in the p T range 0–10 GeV/c and compared with state-of- the-art QCD calculations. The J/ψ &#12296pT&#12297 and &#12296B 2 T &#12297 are extracted and compared with results obtained at other collision energies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Double-beta decay of $^{130}\hbox {Te}$ to the first $0^+$ excited state of $^{130}\hbox {Xe}$ with CUORE-0

We report on a search for double beta decay of 130 Te to the first 0 + excited state of 130 Xe using a 9.8kg·yr exposure of 130 Te collected with the CUORE-0 experiment. In this work we exploit different topologies of coincident events to search for both the neutrinoless and two-neutrino double beta decay modes. We find no evidence for either mode and place lower bounds on the half-lives: $T_{0_1^+}^{0ν}$ > 7.9·10 23 yr and $T_{0_1^+}^{2ν}$ > 2.4·10 23 yr (90%CL). Combining our results with those obtained by the CUORICINO experiment, we achieve the most stringent constraints available for these processes: $T_{0_1^+}^{0ν}$ > 1.4·10 24 yr and $T_{0_1^+}^{2ν}$ > 2.5·10 23 yr (90%CL).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Event-shape and multiplicity dependence of freeze-out radii in pp collisions at $\sqrt{s}$= 7 TeV

Two-particle correlations in high-energy collision experiments enable the extraction of particle source radii by using the Bose-Einstein enhancement of pion production at low relative momentum q ∝ 1/R. It was previously observed that in pp collisions at $\sqrt{s}$ = 7TeV the average pair transverse momentum k T range of such analyses is limited due to large background correlations which were attributed to mini-jet phenomena. To investigate this further, an event-shape dependent analysis of Bose-Einstein correlations for pion pairs is performed in this work. By categorizing the events by their transverse sphericity S T into spherical (S T > 0:7) and jet-like (S T < 0:3) events a method was developed that allows for the determination of source radii for much larger values of k T for the first time. Spherical events demonstrate little or no background correlations while jet-like events are dominated by them. This observation agrees with the hypothesis of a mini-jet origin of the non-femtoscopic background correlations and gives new insight into the physics interpretation of the k T dependence of the radii. The emission source size in spherical events shows a substantially diminished k T dependence, while jet-like events show indications of a negative trend with respect to k T in the highest multiplicity events. Regarding the emission source shape, the correlation functions for both event sphericity classes show good agreement with an exponential shape, rather than a Gaussian one.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Coherent J/ψ photoproduction at forward rapidity in ultra-peripheral Pb–Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV

The ALICE collaboration performed the first rapidity-differential measurement of coherent J/ψ photoproduction in ultra-peripheral Pb–Pb collisions at a center-of-mass energy $ \sqrt{s_{NN}}$=5.02 TeV. The J/ψ is detected via its dimuon decay in the forward rapidity region (-4.0 < γ < -2.5) 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 750 μb -1 . The cross section for coherent J/ψ production is presented in six rapidity bins. The results are compared with theoretical models for coherent J/ψ photoproduction. These comparisons indicate that gluon shadowing effects play a role in the photoproduction process. The ratio of ψ' to J/ψ coherent photoproduction cross sections was measured and found to be consistent with that measured for photoproduction off protons.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗