日本物理学会誌及びJournal of the Physical Society of Japanの月刊について

In this paper we describe Herwig++ version 2.3, a general-purpose Monte Carlo event generator for the simulation of hard lepton-lepton, lepton-hadron and hadron-hadron collisions. A number of important hard scattering processes are available, together with an interface via the Les Houches Accord to specialized matrix element generators for additional processes. The simulation of Beyond the Standard Model (BSM) physics includes a range of models and allows new models to be added by encoding the Feynman rules of the model. The parton-shower approach is used to simulate initial- and final-state QCD radiation, including colour coherence effects, with special emphasis on the correct description of radiation from heavy particles. The underlying event is simulated using an eikonal multiple parton-parton scattering model. The formation of hadrons from the quarks and gluons produced in the parton shower is described using the cluster hadronization model. Hadron decays are simulated using matrix elements, where possible including spin correlations and off-shell effects. Comment: 153 pages, program and additional information available from http://projects.hepforge.org/herwig . Updated description to Herwig++ version 2.3 and added one author

/pdf/herwig-physics-and-manual-4sr09wbmek.pdf

Herwig++ Physics and Manual

https://bura.brunel.ac.uk/bitstream/2438/20604/1/FullText.pdf

Precision electroweak measurements on the Z resonance

We present an updated set of parameters for the PYTHIA 8 event generator. We reevaluate the constraints imposed by LEP and SLD on hadronization, in particular with regard to heavy-quark fragmentation and strangeness production. For hadron collisions, we combine the updated fragmentation parameters with the new NNPDF2.3 LO PDF set. We use minimum-bias, Drell–Yan, and underlying-event data from the LHC to constrain the initial-state-radiation and multi-parton-interaction parameters, combined with data from SPS and the Tevatron to constrain the energy scaling. Several distributions show significant improvements with respect to the current defaults, for both $$ee$$
 and $$pp$$
 collisions, though we emphasize that interesting discrepancies remain in particular for strange particles and baryons. The updated parameters are available as an option starting from PYTHIA 8.185, by setting Tune:ee = 7 and Tune:pp = 14.

/pdf/tuning-pythia-8-1-the-monash-2013-tune-3pdoticvpp.pdf

Tuning PYTHIA 8.1: the Monash 2013 tune

We present an updated set of parameters for the PYTHIA 8 event generator. We reevaluate the constraints imposed by LEP and SLD on hadronization, in particular with regard to heavy-quark fragmentation and strangeness production. For hadron collisions, we combine the updated fragmentation parameters with a new NNPDF2.3 LO PDF set. We use minimum-bias, Drell-Yan, and underlying-event data from the LHC to constrain the initial-state-radiation and multi-parton-interaction parameters, combined with data from SPS and the Tevatron to constrain the energy scaling. Several distributions show significant improvements with respect to the current defaults, for both ee and pp collisions, though we emphasize that interesting discrepancies remain in particular for strange particles and baryons. The updated parameters are available as an option starting from PYTHIA 8.185, by setting Tune:ee = 7 and Tune:pp = 14.

/pdf/tuning-pythia-8-1-the-monash-2013-tune-4b599x3syv.pdf

Tuning PYTHIA 8.1: the Monash 2013 Tune

One idea for controlling multibunch beam breakup in future linear colliders is to use accelerating structures that have a large ( approximately 10%) staggered tuning, that is, a large cell-to-cell spread in frequencies of the transverse dipole modes. Simulations of such structures using the programs TBCI and LINACBBU are compared. Issues relevant to the design and optimization of such structures, such as choice of cell frequency distribution and role of cell-to-cell coupling are discussed. >

/pdf/simulation-of-accelerating-structures-with-large-staggered-1gdg0tj22e.pdf

Simulation of accelerating structures with large staggered tuning

This is a summary of the design procedure for the detuned accelerator structure for SLAC's Next Linear Collider program. The 11.424 GHz accelerating mode of each cavity must be synchronous with the beam. The distribution of the disk thicknesses and lowest synchronous dipole mode frequencies of the cavities in the structure is Gaussian in order to reduce the effect of wake fields. The finite element field solver YAP calculated the accelerating mode frequency and the lowest synchronous dipole mode frequency for various cavity diameters, aperture diameters and disk thicknesses. Polynomial 3-parameter fits are used to calculate the dimensions for a 1.8 m detuned structure. The program SUPERFISH was used to calculate the shunt impedances, quality factors and group velocities. The RF parameters of the section like filling time, attenuation factor, accelerating gradient and maximum surface field along the section are evaluated. Error estimates are discussed and comparisons with conventional constant gradient and constant impedance structures are be presented. >

/pdf/design-of-the-detuned-accelerator-structure-38cx0dn5jd.pdf

Design of the detuned accelerator structure

A 1.8 m X-band damped-detuned structure (DDS-3) has been fabricated and characterized as part of the structure development program towards a TeV-scale e/sup +/e/sup -/ linear collider. In this joint venture, the Cu cells were precision-fabricated by LLNL, diffusion-bonded into a monolithic structure by KEK, and the structure completed and tested by SLAC. The overall process constitutes a baseline for future high-volume structure manufacture.

/pdf/fabrication-of-dds-3-an-11-4-ghz-damped-detuned-structure-5g5kkwit05.pdf

Fabrication of DDS-3, an 11.4 GHz damped-detuned structure

The power spectrum emerging from the damping manifolds of a DDS provides valuable quasi-local information on the displacement of a drive beam from the axis of individual cells, where the displacement may be due to beam offset, small cell misalignment, or a combination of the two. The degree of localization and the indexing of frequency to cell number is determined directly from the spectral function theory. Examples for specific DDS designs are presented. These relations can be used to determine geometrical misalignment patterns.

/pdf/analysis-and-application-of-microwave-radiation-from-the-1p6hdxi8f0.pdf

Analysis and application of microwave radiation from the damping manifolds of the SLAC damped detuned structures (DDS)

This paper describes an X-band RF system for the Next Linear Collider Test Accelerator. The RF system consists of a 90 MeV injector and a 540 MeV linac. The main components of the injector are two low-Q single-cavity prebunchers and two 0.9-m-long detuned accelerator sections. The linac system consists of six 1.8-m-long detuned and damped detuned accelerator sections powered in pairs. The RF power generation, compression, delivery, distribution and measurement systems consist of klystrons, SLED-II energy compression systems, rectangular waveguides, magic-T's, and directional couplers. The phase and amplitude for each prebuncher is adjusted via a magic-T type phase shifter/attenuator. Correct phasing between the two 0.9 m accelerator sections is obtained by properly aligning the sections and adjusting two squeeze type phase shifters. Bunch phase and bunch length can be monitored with special microwave cavities and measurement systems. The design, fabrication, microwave measurement, calibration, and operation of the sub-systems and their components are briefly presented.

/pdf/rf-systems-for-the-nlcta-132kxjh3ip.pdf

J.W. Wang

Papers

Simulation of accelerating structures with large staggered tuning

Design of the detuned accelerator structure

Fabrication of DDS-3, an 11.4 GHz damped-detuned structure

Analysis and application of microwave radiation from the damping manifolds of the SLAC damped detuned structures (DDS)

RF systems for the NLCTA