3,747 research outputs found
Hard Processes in Electron-Proton Scattering
This report summarizes some of the recent HERA results obtained by studying
hard processes in ep-scattering. By resolving the structure of the proton, hard
ep-reactions provide information on the parton content of the proton and may
give insight into the dynamics of the exchanged parton cascade. In addition,
their study offers the possibility to test the Standard Model, in particular
perturbative Quantum Chromodynamics, on which the theoretical predictions on
ep-scattering cross sections are generally based. Any observed deviation
between the data and existing theoretical models would either indicate the need
to calculate higher order contributions or hint at signs of new physics.Comment: 15 pages, 8 figures, talk given at 23rd International Conference on
Physics in Collision (PIC 2003), Zeuthen, Germany, 26-28 Jun 200
Ca2PN3: A New Phosphorus(V) Nitride with One-Dimensional Infinite Chains of Corner-Sharing PN4 Tetrahedra
Characterisation Studies of Silicon Photomultipliers
This paper describes an experimental setup that has been developed to measure
and characterise properties of Silicon Photomultipliers (SiPM). The measured
SiPM properties are of general interest for a multitude of potential
applications and comprise the Photon Detection Efficiency (PDE), the voltage
dependent cross-talk and the after-pulse probabilities. With the described
setup the absolute PDE can be determined as a function of wavelength covering a
spectral range from 350 to 1000nm. In addition, a method is presented which
allows to study the pixel uniformity in terms of the spatial variations of
sensitivity and gain. The results from various commercially available SiPMs -
three HAMAMATSU MPPCs and one SensL SPM - are presented and compared.Comment: 11 pages, 21 figures, submitted to Nuclear Instruments and Methods in
Physics Research Section
Associations between sole ulcer, white line disease and digital dermatitis and the milk yield of 1824 dairy cows on 30 dairy cow farms in England and Wales from February 2003–November 2004
The milk yields of 1824 cows were used to investigate the effect of lesion-specific causes of lameness, based on farmer treatment and diagnosis of lame cows, on milk yield. A three level hierarchical model of repeated test day yields within cows within herds was used to investigate the impact of lesion-specific causes of lameness (sole ulcer, white line disease, digital dermatitis and other causes) on milk yield before and after treatment compared with unaffected cows. Cattle which developed sole ulcer (SU) and white line disease (WLD) were higher yielding cattle before they were diagnosed. Their milk production fell to below that of the mean of unaffected cows before diagnosis and remained low after diagnosis. In cattle which developed digital dermatitis (DD) there was no significant difference in milk yield before treatment and a slightly raised milk yield immediately after treatment. The estimated milk loss attributable to SU and WLD was approximately 570kg and 370kg respectively. These results highlight that specific types of lameness vary by herds and within herds they are associated with higher yielding cattle. Consequently lesion-specific lameness reduction programmes targeting the cow and farm specific causes of lameness might be more effective than generic recommendations. They also highlight the importance of milk loss when estimating the economic impact of SU and WLD on the farms profitability
SENSE: A comparison of photon detection efficiency and optical crosstalk of various SiPM devices
This paper describes a comparison of photon detection efficiency and optical
crosstalk measurements performed by three partners: Geneva University, Catania
Observatory and Nagoya University. The measurements were compared for three
different SiPM devices with different active areas: from 9 up to 93.6
produced by Hamamatsu. The objective of this work is to establish the
measurements and analysis procedures for calculating the main SiPM parameters
and their precision. This work was done in the scope of SENSE project which
aims to build roadmap for the last developments in field of sensors for low
light level detection
Research Proposal for an Experiment to Search for the Decay {\mu} -> eee
We propose an experiment (Mu3e) to search for the lepton flavour violating
decay mu+ -> e+e-e+. We aim for an ultimate sensitivity of one in 10^16
mu-decays, four orders of magnitude better than previous searches. This
sensitivity is made possible by exploiting modern silicon pixel detectors
providing high spatial resolution and hodoscopes using scintillating fibres and
tiles providing precise timing information at high particle rates.Comment: Research proposal submitted to the Paul Scherrer Institute Research
Committee for Particle Physics at the Ring Cyclotron, 104 page
Towards testing a two-Higgs-doublet model with maximal CP symmetry at the LHC: construction of a Monte Carlo event generator
A Monte Carlo event generator is constructed for a two-Higgs-doublet model
with maximal CP symmetry, the MCPM. The model contains five physical Higgs
bosons; the , behaving similarly to the standard-model Higgs boson, two
extra neutral bosons and , and a charged pair . The special
feature of the MCPM is that, concerning the Yukawa couplings, the bosons ,
and couple directly only to the second generation fermions but
with strengths given by the third-generation-fermion masses. Our event
generator allows the simulation of the Drell-Yan-type production processes of
, and in proton-proton collisions at LHC energies. Also the
subsequent leptonic decays of these bosons into the , and channels are studied as well as the dominant
background processes. We estimate the integrated luminosities needed in
collisions at center-of-mass energies of 8 TeV and 14 TeV for significant
observations of the Higgs bosons , and in these muonic
channels
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