Exclusive Jet Measurement in Special LHC Runs - Feasibility Studies

The feasibility studies of the central exclusive jet production at the LHC using the proton tagging technique are presented. Three classes of data taking scenarios are considered: double tag at high pile-up, single tag at low pile-up and double tag at low pile-up. Analyses were performed at the c.m. energy of 14 TeV for the ATLAS experiment, but are also valid for the CMS/TOTEM detectors.Comment: Presented at XXII Cracow Epiphany Conferenc

Machine Optics Studies for the LHC Measurements

In this work the properties of scattered protons in the vicinity of the ATLAS Interaction Point (IP1) for various LHC optics settings are discussed. Firstly, the beam elements installed around IP1 are presented. Then the ATLAS forward detector systems: Absolute Luminosity For ATLAS (ALFA) and ATLAS Forward Protons (AFP) are described and their similarities and differences are discussed. Next, the various optics used at Large Hadron Collider (LHC) are described and the beam divergence and width at the Interaction Point as well as at the ATLAS forward detectors locations are calculated. Finally, the geometric acceptance of the ATLAS forward detectors is shown and the impact of the LHC collimators on it is discussed.Comment: 15 pages, 10 figure

On the Possibility of Measuring the Single-tagged Exclusive Jets at the LHC

The feasibility studies of the measurement of the central exclusive jet production at the LHC using the proton tagging technique are presented. In order to reach the low jet-mass region, single tagged events were considered. The studies were performed at the c.m. energy of 14 TeV and the ATLAS detector, but are also applicable for the CMS-TOTEM experiments. Four data-taking scenarios were considered: AFP and ALFA detectors as forward proton taggers and $\beta^*$ = 0.55 m and $\beta^*$ = 90 m optics. After the event selection, the signal-to-background ratio ranges between 5 and $10^4$. Finally, the expected precision of the central exclusive dijet cross-section measurement for data collection period of 100 h is estimated

Gaps between jets in double-Pomeron-exchange processes at the LHC

The possibility to measure jet-gap-jet final states in double-Pomeron-exchange events at the LHC is presented. In the context of the ATLAS experiment with additional forward physics detectors, cross sections for different experimental settings and gap definitions are estimated. This is done in the framework of the Forward Physics Monte Carlo interfaced with a perturbative QCD model that successfully reproduces standard jet-gap-jet cross sections at the Tevatron. The extrapolation to LHC energies follows from the Balitsky-Fadin-Kuraev-Lipatov dynamics, implemented in the model at next-to-leading logarithmic accuracy.Comment: 8 pages, 5 figures, version to appear in PR

Exclusive π+π−\pi^+\pi^- Production at the LHC with Forward Proton Tagging

A process of Central Exclusive $\pi^+\pi^-$ production in proton-proton collisions and its theoretical description is presented. A possibility of its measurement, during the special low luminosity LHC runs, with the help of the ATLAS central detector for measuring pions and the ALFA stations for tagging the scattered protons is studied. A visible cross section is estimated to be 21 $\mu$b for $\sqrt{s}=7$ TeV, which gives over 2000 events for 100 $\mu$b$^{-1}$ of integrated luminosity. Differential distributions in pion pseudorapidities, pion and proton transverse momenta as well as $\pi^+\pi^-$ invariant mass are shown and discussed.Comment: 9 pages, 7 figure

SphinX soft X-ray spectrophotometer: Science objectives, design and performance

The goals and construction details of a new design Polish-led X-ray spectrophotometer are described. The instrument is aimed to observe emission from entire solar corona and is placed as a separate block within the Russian TESIS X- and EUV complex aboard the CORONAS-PHOTON solar orbiting observatory. SphinX uses silicon PIN diode detectors for high time resolution measurements of the solar spectra in the range 0.8–15 keV. Its spectral resolution allows for discerning more than hundred separate energy bands in this range. The instrument dynamic range extends two orders of magnitude below and above these representative for GOES. The relative and absolute accuracy of spectral measurements is expected to be better than few percent, as follows from extensive ground laboratory calibrations