3,652 research outputs found
Detailed Geant4 simulations of the ANITA and ANITA-CUP neutron facilities
Simulations of the ANITA spallation neutron source at The Svedberg Laboratory (TSL) are described. Neutron radiation calculations show close agreement with measurements at both standard and close user positions. Gamma radiation characteristics are also predicted
Vertex reconstruction framework and its implementation for CMS
The class framework developed for vertex reconstruction in CMS is described.
We emphasize how we proceed to develop a flexible, efficient and reliable piece
of reconstruction software. We describe the decomposition of the algorithms
into logical parts, the mathematical toolkit, and the way vertex reconstruction
integrates into the CMS reconstruction project ORCA. We discuss the tools that
we have developed for algorithm evaluation and optimization and for code
release.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 4 pages, LaTeX, no figures. PSN
TULT01
New vertex reconstruction algorithms for CMS
The reconstruction of interaction vertices can be decomposed into a pattern
recognition problem (``vertex finding'') and a statistical problem (``vertex
fitting''). We briefly review classical methods. We introduce novel approaches
and motivate them in the framework of high-luminosity experiments like at the
LHC. We then show comparisons with the classical methods in relevant physics
channelsComment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 5 pages, LaTeX, 3 eps figures. PSN
TULT01
Dispersion and damping of zone-boundary magnons in the noncentrosymmetric superconductor CePt3Si
Inelastic neutron scattering (INS) is employed to study damped spin-wave
excitations in the noncentrosymmetric heavy-fermion superconductor CePt3Si
along the antiferromagnetic Brillouin-zone boundary in the low-temperature
magnetically ordered state. Measurements along the (1/2 1/2 L) and (H H 1/2-H)
reciprocal-space directions reveal deviations in the spin-wave dispersion from
the previously reported model. Broad asymmetric shape of the peaks in energy
signifies strong spin-wave damping by interactions with the particle-hole
continuum. Their energy width exhibits no evident anomalies as a function of
momentum along the (1/2 1/2 L) direction, which could be attributed to
Fermi-surface nesting effects, implying the absence of pronounced commensurate
nesting vectors at the magnetic zone boundary. In agreement with a previous
study, we find no signatures of the superconducting transition in the magnetic
excitation spectrum, such as a magnetic resonant mode or a superconducting spin
gap, either at the magnetic ordering wavevector (0 0 1/2) or at the zone
boundary. However, the low superconducting transition temperature in this
material still leaves the possibility of such features being weak and therefore
hidden below the incoherent background at energies ~0.1 meV, precluding their
detection by INS
Measurement of neutron detection efficiency between 22 and 174 MeV using two different kinds of Pb-scintillating fiber sampling calorimeters
We exposed a prototype of the lead-scintillating fiber KLOE calorimeter to
neutron beam of 21, 46 and 174 MeV at The Svedberg Laboratory, Uppsala, to
study its neutron detection efficiency. This has been found larger than what
expected considering the scintillator thickness of the prototype. %To check our
method, we measured also the neutron %detection efficiency of a 5 cm thick
NE110 scintillator. We show preliminary measurement carried out with a
different prototype with a larger lead/fiber ratio, which proves the relevance
of passive material to neutron detection efficiency in this kind of
calorimeters
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