ITS is a powerful and user-friendly software package permitting state-of-the-art Monte Carlo solution of lineartime-independent coupled electron/photon radiation transport problems, with or without the presence of macroscopic electric and magnetic fields of arbitrary spatial dependence. Our goal has been to simultaneously maximize operational simplicity and physical accuracy. Through a set of preprocessor directives, the user selects one of the many ITS codes. The ease with which the makefile system is applied combines with an input scheme based on order-independent descriptive keywords that makes maximum use of defaults and internal error checking to provide experimentalists and theorists alike with a method for the routine but rigorous solution of sophisticated radiation transport problems. Physical rigor is provided by employing accurate cross sections, sampling distributions, and physical models for describing the production and transport of the electron/photon cascade from 1.0 GeV down to 1.0 keV. The availability of source code permitsthe more sophisticated user to tailor the codes to specific applications and to extend the capabilities of the codes to more complex applications. Version 6, the latest version of ITS, contains (1) improvements to the ITS 5.0 codes, and (2) conversion to Fortran 90. The general user friendliness of the software has been enhancedthroughmemory allocationtoreducetheneedfor userstomodifyandrecompilethe code. 3 AcknowledgmentThere have been many people involved in the development of the ITS codes over the years. We have undoubtedly lost track of the contributions of some, and even if we had not, there would betoomanytolisthere.ITShasbeen assembledbyborrowingand linking algorithmsfrommany generous sources. We are grateful to those who have shared their methods and grateful also to the many users who have suggested improvements over the years. While recognizing that this is necessarily an abbreviated list, we would like to acknowledge some of the contributions that we deem to have been most significant or most recent.The ITS codes owe most of their development to John Halbleib. He wrote the TIGER code and was the primary developer of the ITS codes throughout most of their history. The original TIGER code was built on the ETRAN code developed by Steve Seltzer and Martin Berger, both of NIST (the National Institute of Standards andTechnology). Further collaborations with NIST, ledtoimprovementsofthe algorithmsandcross sections usedby ITS.Tom Mehlhorn playedan importantrolein the first integrationof the Integrated TIGER Series.This release of ITS includes the multigroup capability. The development of MITS (Multigroup ITS) owes much to the contributions of Jim Morel. MITS is also dependent on the CEPXS cross section generating code that was principally developedby Len Lorence.The parallel capabilityoftheITS codes was implementedbyGregValdez. Much testingand many improvements have been contributedbyWesley Fan. Recent improvementsin the physical modelsin the ITS codes were impleme...

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High-irradiance short-pulse lasers incident on solid density thin foils provide high-energy, picosecond-duration, and monochromatic K(α) x-ray sources, but with limited conversion efficiency ϵ of laser energy into K(α) x-ray energy. A novel two-stage target concept is proposed that utilizes ultrahigh-contrast laser interactions with primary ultrathin foils in order to efficiently generate and transport in large quantities only the most effective K(α)-producing high-energy electrons into secondary x-ray converter foils. Benchmarked simulations with no free numerical parameters indicate an ϵ enhancement greater than tenfold over conventional single targets may be possible.

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Cylinder deactivation has been recently demonstrated to have fuel savings and aftertreatment thermal management benefits at low to moderate loads compared to conventional operation in diesel engines. This study discusses dynamic cylinder activation as an effective variant to fixed diesel engine cylinder deactivation. The set of inactive and active cylinders varies on a cycle-by-cycle basis during dynamic cylinder activation. This enables greater control over forcing frequencies of the engine, thereby allowing the engine to operate away from the drivetrain resonant frequency at all engine speeds, while maintaining similar fuel savings, thermal management, and emission characteristics as fixed cylinder deactivation. Additional benefits of dynamic cylinder activation include a reduction in the consecutive number of cycles a given cylinder is deactivated, and more even cylinder usage. Enablement of engine operation without exciting drivetrain resonant frequencies at similar fuel efficiency and emissions as fixed cylinder deactivation makes dynamic cylinder activation a strong candidate to augment the benefits already demonstrated for fixed cylinder deactivation.