121 research outputs found
Monte Carlo study of particle production in diffractive proton-proton collisions at = 13 TeV with the very forward detector combined with central information
Very forward (VF) detectors in hadron colliders, having unique sensitivity to
diffractive processes, can be a powerful tool for studying diffractive
dissociation by combining them with central detectors. Several Monte Carlo
simulation samples in - collisions at TeV were analyzed,
and different nondiffractive and diffractive contributions were clarified
through differential cross sections of forward neutral particles. Diffraction
selection criteria in the VF-triggered-event samples were determined by using
the central track information. The corresponding selection applicable in real
experiments has 100% purity and 30%-70% efficiency. Consequently, the
central information enables classification of the forward productions into
diffraction and nondiffraction categories; in particular, most of the surviving
events from the selection belong to low-mass diffraction events at
. Therefore, the combined method can uniquely access
the low-mass diffraction regime experimentally.Comment: 10 pages, 16 figures, 1table
The LHCf experiment at LHC
The LHCf experiment will be installed in 2007 on the LHC collider in the forward direction at ±140m from the ATLAS interaction point. The purpose of LHCf is to precisely measure the pion production cross section near zero degrees through the measurement of the photons produced in neutral pion decay. This measurement is crucial for the simulation of the showers induced in the atmosphere by very high energy cosmic rays; the 14 TeV energy available in the center of mass frame corresponds in fact to an equivalent energy of 1017 eV in the laboratory system. The paper focus on the proposed experiment and on the physics results that we expect from it
Free-Floating planet Mass Function from MOA-II 9-year survey towards the Galactic Bulge
We present the first measurement of the mass function of free-floating
planets (FFP) or very wide orbit planets down to an Earth mass, from the MOA-II
microlensing survey in 2006-2014. Six events are likely to be due to planets
with Einstein radius crossing times, days, and the shortest has
days and an angular Einstein radius of as. We measure the detection efficiency depending on both
and with image level simulations for the first
time. These short events are well modeled by a power-law mass function,
dexstar with for . This implies a total of FFP or very wide orbit
planets of mass per star, with a total mass of
per star. The number of FFPs is
times the number of planets in wide orbits (beyond the snow line), while the
total masses are of the same order. This suggests that the FFPs have been
ejected from bound planetary systems that may have had an initial mass function
with a power-law index of , which would imply a total mass of
star. This model predicts that Roman Space
Telescope will detect FFPs with masses down to that of
Mars (including with ). The
Sumi(2011) large Jupiter-mass FFP population is excluded.Comment: 17 pages, 7 figures, accepted for publication in A
Forward photon energy spectrum at LHC 7 TeV p-p collisions measured by LHCf
Abstract The LHCf experiment is one of the LHC forward experiments. The aim is to measure the energy and the transverse momentum spectra of photons, neutrons and π 0 's at the very forward region (the pseudo-rapidity range of η > 8.4 ), which should be critical data to calibrate hadron interaction models used in the air shower simulations. LHCf successfully operated at s = 900 GeV and s = 7 TeV proton–proton collisions in 2009 and 2010. We present the first physics result, single photon energy spectra at s = 7 TeV proton–proton collisions and the pseudo-rapidity ranges of η > 10.94 and 8.81 η 8.9 . The obtained spectra were compared with the predictions by several hadron interaction models and the models do not reproduce the experimental results perfectly
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