8,156 research outputs found
Benchmarking GEANT4 nuclear models for hadron therapy with 95 MeV/nucleon carbon ions
In carbon-therapy, the interaction of the incoming beam with human tissues
may lead to the production of a large amount of nuclear fragments and secondary
light particles. An accurate estimation of the biological dose deposited into
the tumor and the surrounding healthy tissues thus requires sophisticated
simulation tools based on nuclear reaction models. The validity of such models
requires intensive comparisons with as many sets of experimental data as
possible. Up to now, a rather limited set of double di erential carbon
fragmentation cross sections have been measured in the energy range used in
hadrontherapy (up to 400 MeV/A). However, new data have been recently obtained
at intermediate energy (95 MeV/A). The aim of this work is to compare the
reaction models embedded in the GEANT4 Monte Carlo toolkit with these new data.
The strengths and weaknesses of each tested model, i.e.
G4BinaryLightIonReaction, G4QMDReaction and INCL++, coupled to two di fferent
de-excitation models, i.e. the generalized evaporation model and the Fermi
break-up are discussed
Quasiperiodicity and non-computability in tilings
We study tilings of the plane that combine strong properties of different
nature: combinatorial and algorithmic. We prove existence of a tile set that
accepts only quasiperiodic and non-recursive tilings. Our construction is based
on the fixed point construction; we improve this general technique and make it
enforce the property of local regularity of tilings needed for
quasiperiodicity. We prove also a stronger result: any effectively closed set
can be recursively transformed into a tile set so that the Turing degrees of
the resulted tilings consists exactly of the upper cone based on the Turing
degrees of the later.Comment: v3: the version accepted to MFCS 201
Sealed operation, and circulation and purification of gas in the HARPO TPC
HARPO is a time projection chamber (TPC) demonstrator of a gamma-ray
telescope and polarimeter in the MeV-GeV range, for a future space mission. We
present the evolution of the TPC performance over a five month sealed-mode
operation, by the analysis of cosmic-ray data, followed by the fast and
complete recovery of the initial gas properties using a lightweight gas
circulation and purification system.Comment: Proceedings_MPGD2015, EPJ Web of Conference
Cooling Tests of the NectarCAM camera for the Cherenkov Telescope Array
The NectarCAM is a camera proposed for the medium-sized telescopes in the
framework of the Cherenkov Telescope Array (CTA), the next-generation
observatory for very-high-energy gamma-ray astronomy. The cameras are designed
to operate in an open environment and their mechanics must provide protection
for all their components under the conditions defined for the CTA observatory.
In order to operate in a stable environment and ensure the best physics
performance, each NectarCAM will be enclosed in a slightly overpressurized,
nearly air-tight, camera body, to prevent dust and water from entering. The
total power dissipation will be ~7.7 kW for a 1855-pixel camera. The largest
fraction is dissipated by the readout electronics in the modules. We present
the design and implementation of the cooling system together with the test
bench results obtained on the NectarCAM thermal demonstrator.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
Diffractive Dissociation and Eikonalization in High Energy pp and p Collisions
We show that eikonal corrections imposed on diffraction dissociation
processes calculated in the triple Regge limit, produce a radical change in the
energy dependence of the predicted cross section. The induced correction is
shown to be in general agreement with the new experimental data measured at the
Tevatron.Comment: 11 pages LATEX, ( two figures not included obtainable from authors)
(TAUP 2066-93 and FERMILAB PUB 93/ T
Heavy-Higgs Lifetime at Two Loops
The Standard-Model Higgs boson with mass decays almost
exclusively to pairs of and bosons. We calculate the dominant two-loop
corrections of to the partial widths of these decays. In
the on-mass-shell renormalization scheme, the correction factor is found to be
, where the second term is the
one-loop correction. We give full analytic results for all divergent two-loop
Feynman diagrams. A subset of finite two-loop vertex diagrams is computed to
high precision using numerical techniques. We find agreement with a previous
numerical analysis. The above correction factor is also in line with a recent
lattice calculation.Comment: 26 pages, 6 postscript figures. The complete paper including figures
is also available via WWW at
http://www.physik.tu-muenchen.de/tumphy/d/T30d/PAPERS/TUM-HEP-247-96.ps.g
National Football League Skilled and Unskilled Positions Vary in Opportunity and Yield in Return to Play After an Anterior Cruciate Ligament Injury.
BACKGROUND: Anterior cruciate ligament (ACL) injuries pose a significant risk to the careers of players in the National Football League (NFL). The relationships between draft round and position on return to play (RTP) among NFL players are not well understood, and the ability to return to preinjury performance levels remains unknown for most positions.
PURPOSE: To test for differences in RTP rates and changes in performance after an ACL injury by position and draft round. We hypothesized that skilled positions would return at a lower rate compared to unskilled positions. We further hypothesized that early draft-round status would relate to a greater rate of RTP and that skilled positions and a lower draft round would correlate with decreased performance for players who return to sport.
STUDY DESIGN: Case-control study; Level of evidence, 3.
METHODS: Utilizing a previously established database of publicly available information regarding ACL tears among NFL players, athletes with ACL tears occurring between the 2010 and 2013 seasons were identified. Generalized linear models and Kaplan-Meier time-to-event models were used to test the study hypotheses.
RESULTS: The overall RTP rate was 61.7%, with skilled players and unskilled players returning at rates of 64.1% and 60.4%, respectively (P = .74). Early draft-round players and unskilled late draft-round players had greater rates of RTP compared to skilled late draft-round players and both unskilled and skilled undrafted free agents (UDFAs). Skilled early draft-round players constituted the only cohort that played significantly fewer games after an injury. Unskilled UDFAs constituted the only cohort to show a significant increase in the number of games started and ratio of games started to games played, starting more games in which they played, after an injury.
CONCLUSION: Early draft-round and unskilled players were more likely to return compared to their later draft-round and skilled peers. Skilled early draft-round players, who displayed relatively high rates of RTP, constituted the only cohort to show a decline in performance. Unskilled UDFAs, who exhibited relatively low rates of RTP, constituted the only cohort to show an increase in performance. The significant effect of draft round and position type on RTP may be caused by a combination of differences in talent levels and in opportunities given to returning to play
Composite mirror facets for ground based gamma ray astronomy
Composite mirrors for gamma-ray astronomy have been developed to fulfill the
specifications required for the next generation of Cherenkov telescopes
represented by CTA (Cherenkov Telescope Array). In addition to the basic
requirements on focus and reflection efficiency, the mirrors have to be stiff,
lightweight, durable and cost efficient. In this paper, the technology
developed to produce such mirrors is described, as well as some tests that have
been performed to validate them. It is shown that these mirrors comply with the
needs of CTA, making them good candidates for use on a significant part of the
array.Comment: 16 pages, 13 figures, accepted to be published on NIM
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