5,712 research outputs found
Hadron detection with a dual-readout fiber calorimeter
In this paper, we describe measurements of the response functions of a
fiber-based dual- readout calorimeter for pions, protons and multiparticle
"jets" with energies in the range from 10 to 180 GeV. The calorimeter uses lead
as absorber material and has a total mass of 1350 kg. It is complemented by
leakage counters made of scintillating plastic, with a total mass of 500 kg.
The effects of these leakage counters on the calorimeter performance are
studied as well. In a separate section, we investigate and compare different
methods to measure the energy resolution of a calorimeter. Using only the
signals provided by the calorimeter, we demonstrate that our dual-readout
calorimeter, calibrated with electrons, is able to reconstruct the energy of
proton and pion beam particles to within a few percent at all energies. The
fractional widths of the signal distributions for these particles (sigma/E)
scale with the beam energy as 30%/sqrt(E), without any additional contributing
terms
Energy Dependence of the Pomeron Spin-Flip
There is no theoretical reason to think that the spin-flip component of the
Pomeron is zero. One can measure the spin-flip part using Coulomb-nuclear
interference (CNI). Perturbative QCD calculations show that the spin-flip
component is sensitive to the smallest quark separation in the proton, while
the non-flip part probes the largest separation. According to HERA results on
the proton structure function at very low x the energy dependence of the
cross-section correlates with the size of the color dipole. Analysing the data
from HERA we predict that the ratio of the spin-flip to non-flip amplitude
grows with energy as , violating Regge
factorisation of the Pomeron.Comment: A few comments and references are added. Based on invited talks at
the International Workshop on Diffraction Physics, Rio de Janeiro, February
16-20, 1998, and at DIS'98, Brussels, April 4-8, 199
Dual-Readout Calorimetry with Lead Tungstate Crystals
Results are presented of beam tests in which a small electromagnetic
calorimeter consisting of lead tungstate crystals was exposed to 50 GeV
electrons and pions. This calorimeter was backed up by the DREAM Dual-Readout
calorimeter, which measures the scintillation and \v{C}erenkov light produced
in the shower development, using two different media. The signals from the
crystal calorimeter were analyzed in great detail in an attempt to determine
the contributions from these two types of light to the signals, event by event.
This information makes it possible to eliminate the dominating source of
fluctuations and thus achieve an important improvement in hadronic calorimeter
performance.Comment: Preprint submitted to Nucl. Instrum. Meth. on July 23, 200
Diffractive effects in spin-flip pp amplitudes and predictions for relativistic energies
We analyze the diffractive (Pomeron) contribution to pp spin-flip amplitude
and discuss the possible scenarios for energies available at the Relativistic
Heavy-Ion Collider (RHIC). In particular, we show that RHIC data will be
instrumental in assessing the real contribution of diffraction to spin
amplitudes.Comment: 11 pages, 12 Encapsulated PostScript files, LaTeX2e use
Dual-readout Calorimetry
The RD52 Project at CERN is a pure instrumentation experiment whose goal is
to understand the fundamental limitations to hadronic energy resolution, and
other aspects of energy measurement, in high energy calorimeters. We have found
that dual-readout calorimetry provides heretofore unprecedented information
event-by-event for energy resolution, linearity of response, ease and
robustness of calibration, fidelity of data, and particle identification,
including energy lost to binding energy in nuclear break-up. We believe that
hadronic energy resolutions of {\sigma}/E 1 - 2% are within reach for
dual-readout calorimeters, enabling for the first time comparable measurement
preci- sions on electrons, photons, muons, and quarks (jets). We briefly
describe our current progress and near-term future plans. Complete information
on all aspects of our work is available at the RD52 website
http://highenergy.phys.ttu.edu/dream/.Comment: 10 pages, 10 figures, Snowmass White pape
The effects of the small t properties of hadronic scattering amplitude on the determination its real part
Taking into account the different forms of the Coulomb-hadron interference
phase and the possible spin-flip contribution the new analysis of the
experimental data of the proton-antiproton elastic scattering at GeV/c and small momentum transfer is carried out. It is shown that the
size of the spin-flip amplitude can be determined from the form of the
differential cross sections at small , and the deviation of
obtained from the examined experimental data of the scattering from
the analysis \cite{Kroll}, based on the dispersion relations, is conserved in
all xamined assumptions. The analysis of the proton-proton elastic scattering
at GeV/c also shows the impact of the examined effects on the
form of the differential cross sections.Comment: 13 pages, 3 figure
Modeling of laser-induced plasmon effects in GNS-DLC-based material for application in X-ray source array sensors
An important direction in the development of X-ray computed tomography sensors in systems with increased scanning speed and spatial resolution is the creation of an array of miniature current sources. In this paper, we describe a new material based on gold nanostars (GNS) embedded in nanoscale diamond-like carbon (DLC) films (thickness of 20 nm) for constructing a pixel current source with photoinduced electron emission. The effect of localized surface plasmon resonance in GNS on optical properties in the wavelength range from UV to near IR, peculiarities of localization of field and thermal sources, generation of high-energy hot electrons, and mechanisms of their transportation in vacuum are investigated. The advantages of the proposed material and the prospects for using X-ray computed tomography in the matrix source are evaluated
Black Holes at Future Colliders and Beyond: a Topical Review
One of the most dramatic consequences of low-scale (~1 TeV) quantum gravity
in models with large or warped extra dimension(s) is copious production of mini
black holes at future colliders and in ultra-high-energy cosmic ray collisions.
Hawking radiation of these black holes is expected to be constrained mainly to
our three-dimensional world and results in rich phenomenology. In this topical
review we discuss the current status of astrophysical observations of black
holes and selected aspects of mini black hole phenomenology, such as production
at colliders and in cosmic rays, black hole decay properties, Hawking radiation
as a sensitive probe of the dimensionality of extra space, as well as an
exciting possibility of finding new physics in the decays of black holes.Comment: 31 pages, 10 figures To appear in the Journal of Physics
The spin dependence of high energy proton scattering
Motivated by the need for an absolute polarimeter to determine the beam
polarization for the forthcoming RHIC spin program, we study the spin
dependence of the proton-proton elastic scattering amplitudes at high energy
and small momentum transfer.We examine experimental evidence for the existence
of an asymptotic part of the helicity-flip amplitude phi_5 which is not
negligible relative to the largely imaginary average non-flip amplitude phi_+.
We discuss theoretical estimates of r_5, essentially the ratio of phi_5 to
phi_+, based upon extrapolation of low and medium energy Regge phenomenological
results to high energies, models based on a hybrid of perturbative QCD and
non-relativistic quark models, and models based on eikonalization techniques.
We also apply the model-independent methods of analyticity and unitarity.The
preponderence of evidence at available energy indicates that r_5 is small,
probably less than 10%. The best available experimental limit comes from
Fermilab E704:those data indicate that |r_5|<15%. These bounds are important
because rigorous methods allow much larger values. In contradiction to a
widely-held prejudice that r_5 decreases with energy, general principles allow
it to grow as fast as ln(s) asymptotically, and some models show an even faster
growth in the RHIC range. One needs a more precise measurement of r_5 or to
bound it to be smaller than 5% in order to use the classical Coulomb-nuclear
interference technique for RHIC polarimetry. As part of this study, we
demonstrate the surprising result that proton-proton elastic scattering is
self-analysing, in the sense that all the helicity amplitudes can, in
principle, be determined experimentally at small momentum transfer without a
knowledge of the magnitude of the beam and target polarization
Design, performance, and calibration of the CMS hadron-outer calorimeter
The outer hadron calorimeter (HCAL HO) of the CMS detector is designed to measure the energy that is not contained by the barrel (HCAL HB) and electromagnetic (ECAL EB) calorimeters. Due to space limitation the barrel calorimeters do not contain completely the hadronic shower and an outer calorimeter (HO) was designed, constructed and inserted in the muon system of CMS to measure the energy leakage. Testing and calibration of the HO was carried out in a 300 GeV/c test beam that improved the linearity and resolution. HO will provide a net improvement in missing E T measurements at LHC energies. Information from HO will also be used for the muon trigger in CMS
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