5,264 research outputs found
Do phase transitions survive binomial reducibility and thermal scaling?
First order phase transitions are described in terms of the microcanonical
and canonical ensemble, with special attention to finite size effects.
Difficulties in interpreting a "caloric curve" are discussed. A robust
parameter indicating phase coexistence (univariance) or single phase
(bivariance) is extracted for charge distributions.Comment: 10 pages, TeX type, psfig, also available at
http://csa5.lbl.gov/moretto/ps/lgm.ps, to appear in the Proceedings of the
1st Catania Relativistic Ion Studies: Critical Phenomena and Collective
Observables, Acicastello, May 27-31, 199
The Role of Phase Space in Complex Fragment Emission from Low to Intermediate Energies
The experimental emission probabilities of complex fragments by low energy
compound nuclei and their dependence upon energy and atomic number are compared
to the transition state rates. Intermediate-mass-fragment multiplicity
distributions for a variety of reactions at intermediate energies are shown to
be binomial and thus reducible at all measured transverse energies. From these
distributions a single binary event probability can be extracted which has a
thermal dependence. A strong thermal signature is also found in the charge
distributions. The n-fold charge distributions are reducible to the 1-fold
charge distributions through a simple scaling dictated by fold number and
charge conservation.Comment: 15 pages, TeX type, psfig, also available at
http://csa5.lbl.gov/moretto/ps/brazil.ps, to appear in Proceedings of the 1st
International Conference on Nuclear Dynamics at Long and Short Distances,
April 8-12, 1996, Angra dos Reis, Brazi
New Wave of Component Reuse with Spring Framework - AP Case Study
The myth of component reuse has always been the “holy grail” of software engineering. The motivation var-ies from less time, effort and money expenditure to higher system quality and reliability which is especially impor-tant in the domain of high energy physics and accelerator controls. Identified as an issue by D. McIlroy in 1968 [1], it has been generally addressed in many ways with vari-ous success rates. But only recently with the advent of fresh ideas like the Spring Framework with its powerful yet simple “Inversion of Control” paradigm the solution to the problem has started to be surprisingly uncompli-cated. Gathered over years of experience this document explains best practices and lessons learned applied at CERN for the design of the operational software used to control the accelerator complex and focuses on features of the Spring Framework that render the component reuse achievable in practice. It also provides real life use cases of mission-critical control systems developed by the Ap-plication Section like the LHC Software Architecture (LSA), the Injector Control Architecture (InCA) or the Software Interlock System (SIS) that have built their own success mostly upon a stack of reusable software components
Negative heat capacities and first order phase transitions in nuclei
Anomalous negative heat capacities have been claimed as indicators of first order phase transitions in finite systems in general, and fornuclear systems in particular. A thermodynamic approach allowing for all Q value terms is used to evaluate heat capacities in finitevan der Waals fluids and finite lattice systems in the coexistence region. Fictitious large effects and negative heat capacities are observed in lattice systems when periodic boundary conditions are introduced. Small anomalous effects are predicted for small drops and for finite lattice systems. A straightforward application of the analysis to nuclei shows that negative heat capacities cannot be observed for A>60
Resilient Reducibility in Nuclear Multifragmentation
The resilience to averaging over an initial energy distribution of
reducibility and thermal scaling observed in nuclear multifragmentation is
studied. Poissonian reducibility and the associated thermal scaling of the mean
are shown to be robust. Binomial reducibility and thermal scaling of the
elementary probability are robust under a broad range of conditions. The
experimental data do not show any indication of deviation due to averaging.Comment: 5 pages, 6 figures, submitted to Physical Review
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