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.
The dynamic alignment method of the forward proton detectors proposed by the CDF Collaboration is reviewed. Applicability of the method at the LHC is discussed.
Acta Physica Polonica B vol. 42 (2011) page 1861 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.
LHC Forward Physics Akiba, K; Albrow, M; Avati, V ...
arXiv.org,
12/2017
Paper, Journal Article
Odprti dostop
The goal of this report is to give a comprehensive overview of the rich field of forward physics, with a special attention to the topics that can be studied at the LHC. The report starts presenting a ...selection of the Monte Carlo simulation tools currently available, chapter 2, then enters the rich phenomenology of QCD at low, chapter 3, and high, chapter 4, momentum transfer, while the unique scattering conditions of central exclusive production are analyzed in chapter 5. The last two experimental topics, Cosmic Ray and Heavy Ion physics are presented in the chapter 6 and 7 respectively. Chapter 8 is dedicated to the BFKL dynamics, multiparton interactions, and saturation. The report ends with an overview of the forward detectors at LHC. Each chapter is correlated with a comprehensive bibliography, attempting to provide to the interested reader with a wide opportunity for further studies.
The ATLAS Roman Pot system is designed to determine the total proton-proton cross-section as well as the luminosity at the Large Hadron Collider (LHC) by measuring elastic proton scattering at very ...small angles. The system is made of four Roman Pot stations, located in the LHC tunnel in a distance of about 240~m at both sides of the ATLAS interaction point. Each station is equipped with tracking detectors, inserted in Roman Pots which approach the LHC beams vertically. The tracking detectors consist of multi-layer scintillating fibre structures readout by Multi-Anode-Photo-Multipliers.
This study aimed to assess the accuracy of post-traumatic stress disorder (PTSD) diagnoses made by mental health experts in people reporting post-traumatic stress symptoms related to traffic ...accidents. Data were collected from sixty participants: 30 with possible traumatic experiences and 30 who had never experienced this or other types of traumatic events. Six professional diagnosticians examined the participants with Structured Clinical Interview for the Study of Axis I Disorders (SCID-I for DSM-IV-TR) in conditions similar to those typical of judicial cases related to traffic accident damage claims. There was no significant difference in the number of PTSD diagnoses between malingerers and non-malingerers. Some PTSD symptoms were more frequently recognized in malingerers. This study demonstrates that even professional diagnosticians with clinical and jurisprudence experience have significant difficulty identifying PTSD malingering. This difficulty can be linked to the limitations of diagnoses based on introspective reports.
•Untrained malingerers can successfully fake PTSD symptoms and deceive diagnosticians•Some PTSD symptoms can be recognized more frequently in malingerers•Successful PTSD malingerers can rely solely on common knowledge of PTSD
The MoEDAL experiment is designed to search for magnetic monopoles and other highly-ionising particles produced in high-energy collisions at the LHC. The largely passive MoEDAL detector, deployed at ...Interaction Point 8 on the LHC ring, relies on two dedicated direct detection techniques. The first technique is based on stacks of nuclear-track detectors with surface area \(\sim\)18 m\(^2\), sensitive to particle ionisation exceeding a high threshold. These detectors are analysed offline by optical scanning microscopes. The second technique is based on the trapping of charged particles in an array of roughly 800 kg of aluminium samples. These samples are monitored offline for the presence of trapped magnetic charge at a remote superconducting magnetometer facility. We present here the results of a search for magnetic monopoles using a 160 kg prototype MoEDAL trapping detector exposed to 8 TeV proton-proton collisions at the LHC, for an integrated luminosity of 0.75 fb\(^{-1}\). No magnetic charge exceeding \(0.5g_{\rm D}\) (where \(g_{\rm D}\) is the Dirac magnetic charge) is measured in any of the exposed samples, allowing limits to be placed on monopole production in the mass range 100 GeV\(\leq m \leq\) 3500 GeV. Model-independent cross-section limits are presented in fiducial regions of monopole energy and direction for \(1g_{\rm D}\leq|g|\leq 6g_{\rm D}\), and model-dependent cross-section limits are obtained for Drell-Yan pair production of spin-1/2 and spin-0 monopoles for \(1g_{\rm D}\leq|g|\leq 4g_{\rm D}\). Under the assumption of Drell-Yan cross sections, mass limits are derived for \(|g|=2g_{\rm D}\) and \(|g|=3g_{\rm D}\) for the first time at the LHC, surpassing the results from previous collider experiments.
X-ray lines of helium-like calcium (Ca xix) between 3.17 and 3.21 and associated Ca xviii dielectronic satellites have previously been observed in solar flare spectra, and their excitation mechanisms ...are well established. Dielectronic satellites of lower-ionization stages (Ca xvii-Ca xv) are not as well characterized. Several spectra during a large solar flare in 2001 by the DIOGENESS X-ray spectrometer on the CORONAS-F spacecraft show the Ca xvii and Ca xvi satellites, as well as lines of ionized argon (Ar xvii, Ar xvi), including dielectronic satellites. The DIOGENESS spectra are compared with spectra from a synthesis code developed here based on an isothermal assumption with various atomic sources including dielectronic satellite data from the Cowan Hartree-Fock code. Best-fit comparisons are made by varying the temperature as the code's input (Ar/Ca abundance ratio fixed at 0.33); close agreement is achieved, although with adjustments to some ion fractions. The derived temperature is close to that derived from the two GOES X-ray channels, TGOES. Some lines are identified for the first time. Similar spectra from the P78-1 spacecraft and the Alcator C-Mod tokamak have also been analyzed and similar agreements were obtained. The importance of blends of calcium and argon lines is emphasized, affecting line ratios used for temperature diagnostics. This analysis will be applied to the Solar Maximum Mission Bent Crystal Spectrometer archive and to X-ray spectra expected from the ChemiX instrument on the Sun-orbiting Interhelioprobe spacecraft, while the relevance to X-ray spectra from non-solar sources is indicated.
Multiple Partonic Interactions are often crucial for interpreting results obtained at the Large Hadron Collider (LHC). The quest for a sound understanding of the dynamics behind MPI - particularly at ...this time when the LHC is due to start its "Run II" operations - has focused the aim of this workshop. MPI@LHC2014 concentrated mainly on the phenomenology of LHC measurements whilst keeping in perspective those results obtained at previous hadron colliders. The workshop has also debated some of the state-of-the-art theoretical considerations and the modeling of MPI in Monte Carlo event generators. The topics debated in the workshop included: Phenomenology of MPI processes and multiparton distributions; Considerations for the description of MPI in Quantum Chromodynamics (QCD); Measuring multiple partonic interactions; Experimental results on inelastic hadronic collisions: underlying event, minimum bias, forward energy flow; Monte Carlo generator development and tuning; Connections with low-x phenomena, diffraction, heavy-ion physics and cosmic rays. In a total of 57 plenary talks the workshop covered a wide range of experimental results, Monte Carlo development and tuning, phenomenology and dedicated measurements of MPI which were produced with data from the LHC's Run I. Recent progress of theoretical understanding of MPI in pp, pA and AA collisions as well as the role of MPI in diffraction and small-x physics were also covered. The workshop forstered close contact between the experimental and theoretical communities. It provided a setting to discuss many of the different aspects of MPI, eventually identifying them as a unifying concept between apparently different lines of research and evaluating their impact on the LHC physics programme.
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.
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