370 research outputs found
Muon Colliders
Muon Colliders have unique technical and physics advantages and disadvantages
when compared with both hadron and electron machines. They should thus be
regarded as complementary. Parameters are given of 4 TeV and 0.5 TeV high
luminosity \mumu colliders, and of a 0.5 TeV lower luminosity demonstration
machine. We discuss the various systems in such muon colliders, starting from
the proton accelerator needed to generate the muons and proceeding through muon
cooling, acceleration and storage in a collider ring. Problems of detector
background are also discussed.Comment: 28 pages, with 12 postscript figures. To be published Proceedings of
the 9th Advanced ICFA Beam Dynamics Workshop, AIP Pres
Systematic study related to the role of initial impurities and irradiation rates in the formation and evolution of complex defects in silicon for detectors in HEP experiments
The influence of oxygen and carbon impurities on the concentrations of
defects in silicon for detector uses, in complex fields of radiation,
characteristic to high energy physics experiments, is investigated in the frame
of the quantitative phenomenological model developed previously by the authors
and extended in the present paper. Continuous irradiation conditions are
considered, simulating realistically the environments for these experiments.
The generation rate of primary defects is calculated starting from the
projectile - silicon interaction and from the recoil energy redistribution in
the lattice. The mechanisms of formation of complex defects are explicitly
analysed. Vacancy-interstitial annihilation, interstitial and vacancy migration
to sinks, divacancy, vacancy- and interstitial-impurity complex formation and
decomposition are considered. Oxygen and carbon impurities present in silicon
could monitor the concentration of all stable defects, due to their interaction
with vacancies and interstitials. Their role in the mechanisms of formation and
decomposition of the following stable defects: V_2, VO, V_2O, C_i, C_iO_i,
C_iC_s and VP, is studied. The model predictions cover a generation primary
rate of defects between 10^2 pairs/cm3/s and 10^{11} pairs/cm3/s, and could be
a useful clue in obtaining harder materials for detectors for space missions,
at the new generation of accelerators, as, e.g. LHC, Super-LHC and Eloisatron,
or for industrial applications.Comment: 15 pages, work in the frame of CERN RD50 Collaboration, submitted to
Physica Script
'Just’ punishment? Offenders’ views on the meaning and severity of punishment
In England and Wales, ‘punishment’ is a central element of criminal justice. What punishment entails exactly, however, and how it relates to the other aims of sentencing (crime reduction, rehabilitation, public protection and reparation), remains contested. This article outlines different conceptualizations of punishment and explores to what extent offenders subscribe to these perspectives. The analysis is supported by findings from two empirical studies on the subjective experiences of imprisonment and probation, respectively. Semi-structured interviews were conducted with 15 male and 15 female prisoners and seven male and two female probationers. Two primary conceptualizations of punishment were identified: ‘punishment as deprivation of liberty’ and ‘punishment as hard treatment’. The comparative subjective severity of different sentences and the collateral (unintended) consequences of punishment are also discussed. It is shown that there are large individual differences in the interpretation and subjective experience of punishment, which has implications for the concept of retributive proportionality, as well as the function of punishment more generally
Transient thermal effects in solid noble gases as materials for the detection of Dark Matter
The transient phenomena produced in solid noble gases by the stopping of the
recoils resulting from the elastic scattering processes of WIMPs from the
galactic halo were modelled, as dependencies of the temperatures of lattice and
electronic subsystems on the distance to the recoil's trajectory, and time from
its passage. The peculiarities of these thermal transients produced in Ar, Kr
and Xe were analysed for different initial temperatures and WIMP energies, and
were correlated with the characteristics of the targets and with the energy
loss of the recoils. The results were compared with the thermal spikes produced
by the same WIMPs in Si and Ge. In the range of the energy of interest, up to
tens of keV for the self-recoil, local phase transitions solid - liquid and
even liquid - gas were found possible, and the threshold parameters were
established.Comment: Minor corrections and updated references; accepted to JCA
Modified Chrispin-Norman chest radiography score for cystic fibrosis: observer agreement and correlation with lung function
Contains fulltext :
96114.pdf ( ) (Closed access)OBJECTIVE: To test observer agreement and two strategies for possible improvement (consensus meeting and reference images) for the modified Chrispin-Norman score for children with cystic fibrosis (CF). METHODS: Before and after a consensus meeting and after developing reference images three observers scored sets of 25 chest radiographs from children with CF. Observer agreement was tested for line, ring, mottled and large soft shadows, for overinflation and for the composite modified Chrispin-Norman score. Correlation with lung function was assessed. RESULTS: Before the consensus meeting agreement between observers 1 and 2 was moderate-good, but with observer 3 agreement was poor-fair. Scores correlated significantly with spirometry for observers 1 and 2 (-0.72<R<-0.42, P < 0.05), but not for observer 3. Agreement with observer 3 improved after the consensus meeting. Reference images improved agreement for overinflation and mottled and large shadows and correlation with lung function, but agreement for the modified Chrispin-Norman score did not improve further. CONCLUSION: Consensus meetings and reference images improve among-observer agreement for the modified Chrispin-Norman score, but good agreement was not achieved among all observers for the modified Chrispin-Norman score and for bronchial line and ring shadows
Swimming physiology of European silver eels (Anguilla anguilla L.): energetic costs and effects on sexual maturation and reproduction
The European eel migrates 5,000–6,000 km to the Sargasso Sea to reproduce. Because they venture into the ocean in a pre-pubertal state and reproduce after swimming for months, a strong interaction between swimming and sexual maturation is expected. Many swimming trials have been performed in 22 swim tunnels to elucidate their performance and the impact on maturation. European eels are able to swim long distances at a cost of 10–12 mg fat/km which is 4–6 times more efficient than salmonids. The total energy costs of reproduction correspond to 67% of the fat stores. During long distance swimming, the body composition stays the same showing that energy consumption calculations cannot be based on fat alone but need to be compensated for protein oxidation. The optimal swimming speed is 0.61–0.67 m s−1, which is ~60% higher than the generally assumed cruise speed of 0.4 m s−1 and implies that female eels may reach the Sargasso Sea within 3.5 months instead of the assumed 6 months. Swimming trials showed lipid deposition and oocyte growth, which are the first steps of sexual maturation. To investigate effects of oceanic migration on maturation, we simulated group-wise migration in a large swim-gutter with seawater. These trials showed suppressed gonadotropin expression and vitellogenesis in females, while in contrast continued sexual maturation was observed in silver males. The induction of lipid deposition in the oocytes and the inhibition of vitellogenesis by swimming in females suggest a natural sequence of events quite different from artificial maturation protocols
Dramatic effect of pop-up satellite tags on eel swimming
The journey of the European eel to the spawning area in the Sargasso Sea is still a mystery. Several trials have been carried out to follow migrating eels with pop-up satellite tags (PSATs), without much success. As eels are very efficient swimmers, tags likely interfere with their high swimming efficiency. Here we report a more than twofold increase in swimming cost caused by a regular small satellite tag. The impact was determined at a range of swimming speeds with and without tag in a 2-m swimming tunnel. These results help to explain why the previous use of PSATs to identify spawning sites in the Sargasso Sea was thus far unsuccessful
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Interaction of high energy protons in nuclear emulsions loaded with b 10 and LiF
An experiment is proposed to expose nuclear emulsions loaded with B{sup 10} and LiF to high energy protons at 100 GeV, 150 GeV and 200 GeV. The purposes are: (i) to measure the total cross-sections at these incident energies, (ii) to investigate charged multiplicity as a function of energy, (iii) to investigate the angular distribution and development of hadron showers in collisions of protons with nuclei
Status of Muon Collider Research and Development and Future Plans
The status of the research on muon colliders is discussed and plans are
outlined for future theoretical and experimental studies. Besides continued
work on the parameters of a 3-4 and 0.5 TeV center-of-mass (CoM) energy
collider, many studies are now concentrating on a machine near 0.1 TeV (CoM)
that could be a factory for the s-channel production of Higgs particles. We
discuss the research on the various components in such muon colliders, starting
from the proton accelerator needed to generate pions from a heavy-Z target and
proceeding through the phase rotation and decay ()
channel, muon cooling, acceleration, storage in a collider ring and the
collider detector. We also present theoretical and experimental R & D plans for
the next several years that should lead to a better understanding of the design
and feasibility issues for all of the components. This report is an update of
the progress on the R & D since the Feasibility Study of Muon Colliders
presented at the Snowmass'96 Workshop [R. B. Palmer, A. Sessler and A.
Tollestrup, Proceedings of the 1996 DPF/DPB Summer Study on High-Energy Physics
(Stanford Linear Accelerator Center, Menlo Park, CA, 1997)].Comment: 95 pages, 75 figures. Submitted to Physical Review Special Topics,
Accelerators and Beam
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