PHENIX study of the initial state with forward hadron measurements in 200 GeV p(d)+A and 3He+Au collisions

International audienceForward hadron measurements in p(d)+A provide a signal to study nuclear shadowing, initial state energy loss and/or gluon saturation effects as a function of rapidity, centrality and energy. High p T identified π0 measurements are an essential first step toward measuring prompt photon production. The π0 measurements are enabled by the PHENIX MPC-EX detector, a Si-W preshower detector located in front of the Muon Piston Calorimeter (MPC), expanding the neutral pion reconstruction capabilities in the rapidity range 3.1 < η < 3.8 out to high energies, E < 80 GeV. Previous PHENIX measurements of punch-through charged hadrons in the muon arms in the rapidity range 1.4 < | η | < 2.2 were significantly improved through the capability of the forward silicon vertex detector (FVTX) to determine the transverse momentum and rapidity with high precision and reject background from secondary hadrons

Calibration of the photon spectrometer PHOS of the ALICE experiment

The procedure for the energy calibration of the high granularity electromagnetic calorimeter PHOS of the ALICE experiment is presented. The methods used to perform the relative gain calibration, to evaluate the geometrical alignment and the corresponding correction of the absolute energy scale, to obtain the nonlinearity correction coefficients and finally, to calculate the time-dependent calibration corrections, are discussed and illustrated by the PHOS performance in proton-proton (pp) collisions at s=13 TeV. After applying all corrections, the achieved mass resolutions for π0 and η mesons for pT &amp;gt; 1.7 GeV/c are σm π0 = 4.56 ± 0.03 MeV/c2 and σm η = 15.3 ± 1.0 MeV/c2, respectively. © 2019 CERN for the benefit of the Alice collaboration.

Publisher Correction: Unveiling the strong interaction among hadrons at the LHC (Nature, (2020), 588, 7837, (232-238), 10.1038/s41586-020-3001-6)

In Fig. 1c of this Article, owing to an error during the production process, the equation incorrectly began ‘C(k*, r*) = …’ instead of ‘C(k*) = …’. In addition, in affiliation 71 ‘Dipartimento di Fisica dell’Università degli studi di Bari Aldo Moro’ has been corrected to read ‘Dipartimento di Fisica dell’Università degli studi di Cagliari’. The original Article has been corrected online. *A list of authors and their affiliations appears online. © 2021, The Author(s), under exclusive licence to Springer Nature Limited

Calibration of the photon spectrometer PHOS of the ALICE experiment

The procedure for the energy calibration of the high granularity electromagnetic calorimeter PHOS of the ALICE experiment is presented. The methods used to perform the relative gain calibration, to evaluate the geometrical alignment and the corresponding correction of the absolute energy scale, to obtain the nonlinearity correction coefficients and finally, to calculate the time-dependent calibration corrections, are discussed and illustrated by the PHOS performance in proton-proton (pp) collisions at s=13 TeV. After applying all corrections, the achieved mass resolutions for \u3c00 and \u3b7 mesons for pT &gt; 1.7 GeV/c are \u3c3m\u3c0javax.xml.bind.JAXBElement@533d1c3d = 4.56 \ub1 0.03 MeV/c2 and \u3c3m\u3b7 = 15.3 \ub1 1.0 MeV/c2, respectively

Underlying Event Measurements In Pp Collisions At √s = 0:9 And 7 Tev With The Alice Experiment At The Lhc

2012

Energy dependence of exclusive J/ photoproduction off protons in ultra-peripheral p-Pb collisions at NN=5.02 TeV

The ALICE Collaboration has measured the energy dependence of exclusive photoproduction of J / \u3c8 vector mesons off proton targets in ultra\u2013peripheral p\u2013Pb collisions at a centre-of-mass energy per nucleon pair sNN=5.02 TeV. The e + e - and \u3bc + \u3bc - decay channels are used to measure the cross section as a function of the rapidity of the J / \u3c8 in the range - 2.5 &lt; y&lt; 2.7 , corresponding to an energy in the \u3b3p centre-of-mass in the interval 40 &lt; W \u3b3p &lt; 550 GeV. The measurements, which are consistent with a power law dependence of the exclusive J / \u3c8 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

Charged-particle pseudorapidity density at mid-rapidity in p-Pb collisions at root S-NN=8.16 TeV

The pseudorapidity density of charged particles, d N ch / d \u3b7, in p\u2013Pb collisions has been measured at a centre-of-mass energy per nucleon\u2013nucleon pair of 1asNN = 8.16 TeV at mid-pseudorapidity for non-single-diffractive events. The results cover 3.6 units of pseudorapidity, | \u3b7| &lt; 1.8. The d N ch / d \u3b7 value is 19.1 \ub1 0.7 at | \u3b7| &lt; 0.5. This quantity divided by \u27e8 N part \u27e9 /&nbsp;2 is 4.73 \ub1 0.20 , where \u27e8 N part \u27e9 is the average number of participating nucleons, is 9.5% higher than the corresponding value for p\u2013Pb collisions at 1asNN = 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 d N ch / d \u3b7 distribution. Saturation-based models reproduce the distributions well for \u3b7&gt; - 1.3. The d N ch / d \u3b7 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\u2013Pb in the centrality calculation for multiplicity-based estimators is discussed, demonstrating the advantages of determining the centrality with energy deposited near beam rapidity

Measurement of charged jet suppression in Pb-Pb collisions at root s(NN)=2.76 TeV

20143NSFC; National Natural Science Foundation of China; Helmholtz Associatio

J/\u3a8 production and nuclear effects in p-Pb collisions at 1asNN=5.02 TeV

Inclusive J/\u3a8 production has been studied with the ALICE detector in p-Pb collisions at the nucleon-nucleon center of mass energy 1asNN = 5.02TeV at the CERN LHC. The measurement is performed in the center of mass rapidity domains 2.03 < ycms < 3.53 and ?4.46 < ycms < ?2.96, down to zero transverse momentum, studying the \u3bc+\u3bc? decay mode. In this paper, the J/\u3a8 production cross section and the nuclear modification factor RpPb for the rapidities under study are presented. While at forward rapidity, corresponding to the proton direction, a suppression of the J/\u3a8 yield with respect to binary-scaled pp collisions is observed, in the backward region no suppression is present. 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

Measurement of pion, kaon and proton production in proton–proton collisions at √s = 7 TeV

The measurement of primary $$\pi ^{\pm }$$π±, $$K^{\pm }$$K±, $$p$$p and $${\overline{{p}}}$$p¯ production at mid-rapidity (|y| &lt;|y|&amp;lt; 0.5) in proton–proton collisions at $$\sqrt{s}$$s$$=$$= 7 TeV performed with a large ion collider experiment at the large hadron collider (LHC) is reported. Particle identification is performed using the specific ionisation energy-loss and time-of-flight information, the ring-imaging Cherenkov technique and the kink-topology identification of weak decays of charged kaons. Transverse momentum spectra are measured from 0.1 up to 3 GeV/$$c$$c for pions, from 0.2 up to 6 GeV/$$c$$c for kaons and from 0.3 up to 6 GeV/$$c$$c for protons. The measured spectra and particle ratios are compared with quantum chromodynamics-inspired models, tuned to reproduce also the earlier measurements performed at the LHC. Furthermore, the integrated particle yields and ratios as well as the average transverse momenta are compared with results at lower collision energies. © 2015, CERN for the benefit of the ALICE collaboration