902 research outputs found
Exploring Molecular Simulations of a Plausible Prebiotic Reduced Phospholipid Using Hyperchem Software
How the first cells emerged from the primordial milieu is one of the great questions in science. Biomolecular emergence scenarios abound in the literature, but the lack of bioaccessible phosphate and molecular oxygen on the primordial Earth has posed formidable challenges for deducing emergence pathways. One idea gaining wide acceptance invokes delivery of the phosphide mineral schreibersite ((Fe,Ni)3P) to Earth via meteorite impacts ca. 4.2 billion years ago, whereupon they were corroded to reduced phosphorous oxyacids and phosphonates in primordial aquatic environments. We previously proposed that these reduced phosphorus forms could readily combine with putative geochemical species in shallow mineral-rich alkaline hydrothermal systems to form reduced phospholipid analogs of contemporary phosphate-based phospholipids (Fitch, N.W., K.L. Even, L.J. Leinen and M.O. Gaylor. 2016. Plausible prebiotic assembly of a primitive reduced phospholipid from meteoritic phosphorus on the primordial earth. Proceedings of the South Dakota Academy of. Science 95:176.). Lacking resources to empirically validate this idea, we explored “water box” simulations of the proposed phospholipid structure using the HyperChem software package. Simulation results showed the hydrophobic tails migrating away from water molecules, while hydrophilic heads migrated towards them, resulting in quasistacking behaviors consistent with those of known amphiphiles in water. Inspired by these results, we are now investigating more complex primordial simulation scenarios
Testing the Higgs Mechanism in the Lepton Sector with multi-TeV e+e- Collisions
Multi-TeV e+e- collisions provide with a large enough sample of Higgs bosons
to enable measurements of its suppressed decays. Results of a detailed study of
the determination of the muon Yukawa coupling at 3 TeV, based on full detector
simulation and event reconstruction, are presented. The muon Yukawa coupling
can be determined with a relative accuracy of 0.04 to 0.08 for Higgs bosons
masses from 120 GeV to 150 GeV, with an integrated luminosity of 5 inverse-ab.
The result is not affected by overlapping two-photon background.Comment: 6 pages, 2 figures, submitted to J Phys G.: Nucl. Phy
Generic and Layered Framework Components for the Control of a Large Scale Data Acquisition System
The complexity of today's experiments in High Energy Physics results in a large amount of readout channels which can count up to a million and above. The experiments in general consist of various subsystems which themselves comprise a large amount of detectors requiring sophisticated DAQ and readout electronics. We report here on the structured software layers to control such a data acquisition system for the case of LHCb which is one of the four experiments for LHC. Additional focus is given on the protocols in use as well as the required hardware. An abstraction layer was implemented to allow access on the different and distinct hardware types in a coherent and generic manner. The hierarchical structure which allows propagating commands down to the subsystems is explained. Via finite state machines an expert system with auto-recovery abilities can be modeled
Mesoscale subduction at the Almeria-Oran front. Part 2: biophysical interactions.
This paper presents a detailed diagnostic analysis of hydrographic and current meter data from three, rapidly repeated, fine-scale surveys of the Almeria–Oran front. Instability of the frontal boundary, between surface waters of Atlantic and Mediterranean origin, is shown to provide a mechanism for significant heat transfer from the surface layers to the deep ocean in winter. The data were collected during the second observational phase of the EU funded OMEGA project on RRS Discovery cruise 224 during December 1996. High resolution hydrographic measurements using the towed undulating CTD vehicle, SeaSoar, traced the subduction of Mediterranean Surface Water across the Almeria–Oran front. This subduction is shown to result from a significant baroclinic component to the instability of the frontal jet. The Q-vector formulation of the omega equation is combined with a scale analysis to quantitatively diagnose vertical transport resulting from mesoscale ageostrophic circulation. The analyses are presented and discussed in the presence of satellite and airborne remotely sensed data; which provide the basis for a thorough and novel approach to the determination of observational error
Hadron shower decomposition in the highly granular CALICE analogue hadron calorimeter
The spatial development of hadronic showers in the CALICE scintillator-steel
analogue hadron calorimeter is studied using test beam data collected at CERN
and FNAL for single positive pions and protons with initial momenta in the
range from 10 to 80 GeV/c. Both longitudinal and radial development of hadron
showers are parametrised with two-component functions. The parametrisation is
fit to test beam data and simulations using the QGSP_BERT and FTFP_BERT physics
lists from Geant4 version 9.6. The parameters extracted from data and simulated
samples are compared for the two types of hadrons. The response to pions and
the ratio of the non-electromagnetic to the electromagnetic calorimeter
response, h/e, are estimated using the extrapolation and decomposition of the
longitudinal profiles.Comment: 38 pages, 19 figures, 5 tables; author list changed; submitted to
JINS
Shower development of particles with momenta from 15 GeV to 150 GeV in the CALICE scintillator-tungsten hadronic calorimeter
We present a study of showers initiated by electrons, pions, kaons, and
protons with momenta from 15 GeV to 150 GeV in the highly granular CALICE
scintillator-tungsten analogue hadronic calorimeter. The data were recorded at
the CERN Super Proton Synchrotron in 2011. The analysis includes measurements
of the calorimeter response to each particle type as well as measurements of
the energy resolution and studies of the longitudinal and radial shower
development for selected particles. The results are compared to Geant4
simulations (version 9.6.p02). In the study of the energy resolution we include
previously published data with beam momenta from 1 GeV to 10 GeV recorded at
the CERN Proton Synchrotron in 2010.Comment: 35 pages, 21 figures, 8 table
Performance of the first prototype of the CALICE scintillator strip electromagnetic calorimeter
A first prototype of a scintillator strip-based electromagnetic calorimeter
was built, consisting of 26 layers of tungsten absorber plates interleaved with
planes of 45x10x3 mm3 plastic scintillator strips. Data were collected using a
positron test beam at DESY with momenta between 1 and 6 GeV/c. The prototype's
performance is presented in terms of the linearity and resolution of the energy
measurement. These results represent an important milestone in the development
of highly granular calorimeters using scintillator strip technology. This
technology is being developed for a future linear collider experiment, aiming
at the precise measurement of jet energies using particle flow techniques
The Time Structure of Hadronic Showers in highly granular Calorimeters with Tungsten and Steel Absorbers
The intrinsic time structure of hadronic showers influences the timing
capability and the required integration time of hadronic calorimeters in
particle physics experiments, and depends on the active medium and on the
absorber of the calorimeter. With the CALICE T3B experiment, a setup of 15
small plastic scintillator tiles read out with Silicon Photomultipliers, the
time structure of showers is measured on a statistical basis with high spatial
and temporal resolution in sampling calorimeters with tungsten and steel
absorbers. The results are compared to GEANT4 (version 9.4 patch 03)
simulations with different hadronic physics models. These comparisons
demonstrate the importance of using high precision treatment of low-energy
neutrons for tungsten absorbers, while an overall good agreement between data
and simulations for all considered models is observed for steel.Comment: 24 pages including author list, 9 figures, published in JINS
TESLA Technical Design Report Part III: Physics at an e+e- Linear Collider
The TESLA Technical Design Report Part III: Physics at an e+e- Linear
ColliderComment: 192 pages, 131 figures. Some figures have reduced quality. Full
quality figures can be obtained from http://tesla.desy.de/tdr. Editors -
R.-D. Heuer, D.J. Miller, F. Richard, P.M. Zerwa
Pion and proton showers in the CALICE scintillator-steel analogue hadron calorimeter
Showers produced by positive hadrons in the highly granular CALICE
scintillator-steel analogue hadron calorimeter were studied. The experimental
data were collected at CERN and FNAL for single particles with initial momenta
from 10 to 80 GeV/c. The calorimeter response and resolution and spatial
characteristics of shower development for proton- and pion-induced showers for
test beam data and simulations using Geant4 version 9.6 are compared.Comment: 26 pages, 16 figures, JINST style, changes in the author list, typos
corrected, new section added, figures regrouped. Accepted for publication in
JINS
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