Low energy ring lattice of the PEP-II asymmetric B-Factory

Developing a lattice that contains a very low beta value at the interaction point (IP) and has adequate dynamic aperture is one of the major challenges in designing the PEP-II asymmetric B-factory. For the Low Energy Ring (LER) the authors have studied several different chromatic correction schemes since the conceptual design report (CDR). Based on these studies, a hybrid solution with local and semi-local chromatic sextupoles has been selected as the new baseline lattice to replace the local scheme in the CDR. The new design simplifies the interaction region (IR) and reduces the number of sextupoles in the arcs. Arc sextupoles are paired at {pi} phase difference and are not interleaved. In this paper the authors describe the baseline lattice with the emphasis on the lattice changes made since the CDR

PHYSICS WITH THE MAC DETECTORColorado-Frascati-Northeastern-SLAC-Utah-Wisconsin Collaboration

No abstract availabl

Prospects for collider vertex detectors

The technologies available for vertex detection and the restrictions imposed by event topologies and multiple coulomb scattering are discussed. It is shown that ultimate performance limits for collider detectors are set by how close active detection starts relative to the interaction region. This in turn is determined by the machine characteristics and the care taken to provide collimation and shielding to minimize radiation backgrounds

New PEP tau and B-lifetime results

New results on tau and B-lifetimes obtained at the PEP colliding beam ring are presented, including results from MAC and DELCO detectors

Determination of the masses of charged particles observed in the photographic plate

A study has been made of scattering of 40 protons and 160 mesons in photographic emulsions in order to determine the mass of the individual particles. The spread in the values so obtained is large, but the evidence suggests that the majority of mesons recorded by the emulsion can be identified both with the mesons, of mass ≃ 200 me, commonly observed in cloud-chamber experiments and with counters, and with the μ-mesons observed in the photographic plates. The slow particles producing nuclear disintegrations, σ-mesons, appear to contain a large proportion of particles with a mass equal to that of the π-mesons.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Implementation of one-turn maps in SSCTRK using ZLIB

The particle tracking code SSCTRK is currently being adapted to operational simulation and beam-beam effect studies for the Collider rings of the SSC. During beam-beam effect studies, the lattice content of the bending arcs is normally not varied, making fast truncated Taylor map tracking through the arcs an attractive option. The implementation of SSCTRK as a truncated Taylor map tracking program has been carried out using the differential algebra library ZLIB, which simplified the task to that of straightforward translation of SSCTRK kick and drift arithmetic operations to calls to the corresponding polynomial operation subroutines of ZLIB. The accuracy and speed (relative to normal SSCTRK tracking) of truncated Taylor map tracking at 2mm betatron oscillation amplitude was studied in various orders of the map. The seventh order map was found to be in agreement with the normal SSCTRK to about eight significant figures on the first turn, and to a fraction of 1% on the 100,000th turn, for a typical 5cm magnet aperture lattice, and could be made to track at ten times the speed of the normal SSCTRK kick-drift tracking on a scalar architecture (Sun) workstation. (The map tracking subroutines of ZLIB are optimized for vector and parallel architecture supercomputers, and typically achieve even faster relative performance on these, but operational simulation studies will be more conveniently carried out on dedicated workstations which have the incoming generation of superscalar'' CPUs)

Towards a microbial process-based understanding of the resilience of peatland ecosystem service provisioning – A research agenda

Peatlands are wetland ecosystems with great significance as natural habitats and as major global carbon stores. They have been subject to widespread exploitation and degradation with resulting losses in characteristic biota and ecosystem functions such as climate regulation. More recently, large-scale programmes have been established to restore peatland ecosystems and the various services they provide to society. Despite significant progress in peatland science and restoration practice, we lack a process-based understanding of how soil microbiota influence peatland functioning and mediate the resilience and recovery of ecosystem services, to perturbations associated with land use and climate change. We argue that there is a need to: in the short-term, characterise peatland microbial communities across a range of spatial and temporal scales and develop an improved understanding of the links between peatland habitat, ecological functions and microbial processes; in the medium term, define what a successfully restored ‘target’ peatland microbiome looks like for key carbon cycle related ecosystem services and develop microbial-based monitoring tools for assessing restoration needs; and in the longer term, to use this knowledge to influence restoration practices and assess progress on the trajectory towards ‘intact’ peatland status. Rapid advances in genetic characterisation of the structure and functions of microbial communities offer the potential for transformative progress in these areas, but the scale and speed of methodological and conceptual advances in studying ecosystem functions is a challenge for peatland scientists. Advances in this area require multidisciplinary collaborations between peatland scientists, data scientists and microbiologists and ultimately, collaboration with the modelling community. Developing a process-based understanding of the resilience and recovery of peatlands to perturbations, such as climate extremes, fires, and drainage, will be key to meeting climate targets and delivering ecosystem services cost effectively