The NA62 experiment at CERN

The goal of the NA62 experiment at CERN is to collect O(100) events of the ultrarare K\(^{+}\rightarrow \pi ^{+}\nu \bar {\nu }\) decay in two years. After a long R&D phase and a successful pilot run in 2014, the first data-taking phase took place in 2015. In this paper the importance of the experiment’s physics goal, as well as the experimental solutions adopted in order to attain it, will be reviewed.     

Simulations of the PHOS detector in the ALICE experiment at CERN

In 2005 the ALICE experiment will start at the Large Hadron Collider at CERN. It will investigate hot and dense strongly interacting matter formed in heavy ion collisions. The photon spectrometer of the ALICE detector will be designed to identify direct photons. To optimize the detector, simulations will be carried out.     

New CHOD detector for the NA62 experiment at CERN

The New CHOD is a scintillation hodoscope with a pad structure featuring a total of 148 counters. The signal from each pad is read out using wavelength-shifting fibers and two or four SensL SiPMs with a sensitive area of 3 × 3 mm². This photodetector has 4774 pixels 35 × 35 μm² in size. The key parameters (photon detection efficiency, dark current, crosstalk, and gain) were measured for 500 SiPMs.     

Results from the UA 2 experiment at the CERN p¯p Collider

This paper presents results on the production and decay properties of the Intermediate Vector Bosons (IVB)W and Z⁰ and on the search of the top quark in the upgraded UA 2 detector at the CERNp¯p Collider. The analysed data have been taken in the 1988 and 1989 Collider running periods at the centre of mass energy of 630 GeV, and correspond to an integrated luminosity of 7·4 pb^–1.     

Particle detectors for the future antiproton Paul trap of the ASACUSA experiment at CERN

Two detectors which will be used to commission a superconducting radiofrequency Paul trap for antiprotons, now being constructed at CERN and MPQ, are described. One is a microwire secondary electron emission monitor which will nondestructively measure the spatial profile of a low energy (E= 10?100 keV) antiproton beam. The other is a system of electromagnetic shower counters which will detect the secondary particles emerging from the antiproton annihilations occurring in the trap.     

Recent results on kaon decays by the NA48/2 experiment at CERN

The NA48/2 experiment reports the first observation of the rare decay K^± → π^±π⁰e⁺e^?, based on about 2000 candidates from 2003 data. The preliminary branching ratio in the full kinematic region is \(\mathcal {B}(K^{\pm } \to \pi ^{\pm }\pi ^{0}e^{+}e^{-})=(4.06\pm 0.17)\cdot 10^{-6}\). A sample of 4.687 × 10⁶\(K^{\pm }\to \pi ^{\pm }{\pi ^{0}_{D}}\) events collected in 2003/4 is analyzed to search for the dark photon (\(A^{\prime }\)) via the decay chain K^± → π^±π⁰, \(\pi ^{0}\to \gamma A^{\prime }\), \(A^{\prime }\to e^{+}e^{-}\). No signal is observed, limits in the plane mixing parameter ε² versus its mass \(m_{A^{\prime }}\) are reported.     

Results of the NA49 experiment on the search for the quark-gluon plasma at the CERN SPS

Experiment NA 49 at the CERN SPS has performed large acceptance measurements of hadron production in Pb+Pb collisions at 40 and 158 A-GeV beam energies. These data allowed a study of the space-time evolution, the hadro-chemical composition and event-by-event fluctuations of average event properties of the created hadron system. Results at top SPS energy are consistent with the existence of a transient deconfined phase in the early stage of the reaction.     

Methods to study event-by-event fluctuations in the NA61/SHINE experiment at the CERN SPS

Theoretical calculations locate the critical point (CP) of strongly interacting matter at energies accessible at the CERN SPS. Event-by-event transverse momentum and multiplicity fluctuations are considered as one of the most important tools to search for the CP. Pilot studies of the energy dependence and the system size dependence of both p _T and multiplicity fluctuations were performed by the NA49 experiment. The NA61/SHINE ion program is a continuation of these efforts. After briefly recalling the essential NA49 results on fluctuations we will discuss the technical methods (removing Non-Target interactions) which we plan to apply for future transverse momentum and multiplicity fluctuation analyses.     

A measurement of $K^{*\pm}$ production in the hyperon beam experiment at CERN

We report on a measurement of the differential cross sections of inclusive production in and neutron beams. A strong leading particle effect was observed for production by . The measured –distributions are compared with calculations based on the Lund model (PYTHIA) and the quark-gluon string model. Received: 6 August 2001 / Revised version: 3 September 2001 / Published online: 5 October 2001     

Inclusive Pomeron-Pomeron interactions at the CERN ISR

Data are presented for the first time on inclusive Pomeron-Pomeron interactions which produce a central systemX (composed mainly of multimeson states) in proton-proton collisions at \(\sqrt s \) at the CERN ISR. The systemX has a Feynman-x distribution which is sharply peaked atx _f=0, is inconsistent with any significant contributions from Reggeon exchange processes, and has an invariant mass dependence in good agreement with the predicted formM _x ^?2 . Kaon production is about 15% of pion production, nearly independent ofM _x, while proton-antiproton production averages about 5% of pion production and increases withM _x. The structure of the central systemX develops into a jetlike shape, asM _x increases, as would be expected from a model of Pomeron fragmentation. The shape of thex _f(π) distribution in the center of mass of theX system (although not proving existence) is consistent with asoft partonic substructure of the Pomeron.     

Atomic Physics Studies at the Gamma Factory at CERN

The Gamma Factory initiative proposes to develop novel research tools at CERN by producing, accelerating, and storing highly relativistic, partially stripped ion beams in the SPS and LHC storage rings. By exciting the electronic degrees of freedom of the stored ions with lasers, high-energy narrow-band photon beams will be produced by properly collimating the secondary radiation that is peaked in the direction of ions' propagation. Their intensities, up to 10¹⁷ photons per second, will be several orders of magnitude higher than those of the presently operating light sources in the particularly interesting γ–ray energy domain reaching up to 400 MeV. This article reviews opportunities that may be afforded by utilizing the primary beams for spectroscopy of partially stripped ions circulating in the storage ring, as well as the atomic-physics opportunities made possible by the use of the secondary high-energy photon beams. The Gamma Factory will enable ground-breaking experiments in spectroscopy and novel ways of testing fundamental symmetries of nature.     

Lead beam experiments at the CERN SPS

The acceleration in 1986 of¹⁶O beams to 200 GeV/nucleon at the CERN SPS created a new frontier of particle and nuclear physics, namely the study of high energy density systems with hundreds of quarks and gluons created in the central collisions of nuclei with heavy targets. In order to produce the largest piece of “quark matter”, beams as heavy as²⁰⁸Pb are needed. The Lead-Injector Project that would provide them is presented. Possible experimental approaches to extract the physics from collisions with thousands of produced particles are discussed.     

Ξ - production by Σ -,π - and neutrons in the hyperon beam experiment at CERN

Inclusive cross sections for Ξ ^- hyperon production in high-energy Σ ^-, π ^- and neutron induced interactions were measured by the experiment WA89 at CERN. Secondary Σ ^- and π ^- beams with average momenta of 345 GeV/c and a neutron beam of 260 GeV/c were produced by primary protons of 450 GeV/c from the CERN SPS. The influence of the target mass on the Ξ ^- cross section is explored by comparing reactions on copper and carbon nuclei. Both single and double differential cross sections are presented as a function of the transverse momentum and the Feynman variable x _F. A strong leading effect for Σ ^- produced by Σ ^- is observed.     

Proton-antiproton physics at the CERN intersecting storage rings

The storing of antiprotons in the CERN ISR allowed the comparison of proton-proton and proton-antiproton interactions through a variety of reactions ranging from total cross section measurements to hard scattering processes. This article reviews the results obtained at the ISR on such comparisons.     

Two-jet mass distributions at the CERN proton-antiproton collider

Two-jet mass distributions have been measured as a function of centre-of-mass scattering angle for high-mass jet pairs produced in proton-antiproton collisions at the CERN collider operating at a centre-of-mass energy of 630 GeV. The agreement between QCD expectations and the experimental measurements has been used to place limits on the production cross section of an object X decaying into two jets. In particular we consider the existence of a massive colour octet of vector gauge bosons (axigluons). We exclude axigluons with a width Λ_A < 0.4m_A and a mass m_A in the range 150 < m_A < 310 GeV/c² (95% CL).