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A parallel computing framework has been developed to use with general-purpose radiation transport codes. The framework was implemented as a C++ module that uses MPI for message passing. It is intended to be used with older radiation transport codes implemented in Fortran77, Fortran 90 or C. The module is significantly independent of radiation transport codes it can be used with, and is connected to the codes by means of a number of interface functions. The framework was developed and tested in conjunction with the MARS15 code. It is possible to use it with other codes such as PHITS, FLUKA and MCNP after certain adjustments. Besides the parallel computing functionality, the framework offers a checkpoint facility that allows restarting calculations with a saved checkpoint file. The checkpoint facility can be used in single process calculations as well as in the parallel regime. The framework corrects some of the known problems with the scheduling and load balancing found in the original implementations of the parallel computing functionality in MARS15 and PHITS. The framework can be used efficiently on homogeneous systems and networks of workstations, where the interference from the other users is possible.

Investigators at several laboratories are seriously considering the storage and transport, perhaps over long distances, of very low energy antiprotons as a part of basic physics research programs and perhaps even for practical applications. To do this will require proper attention to the prompt radiation hazards due to the release of energy in the annihilations of antiprotons with nuclei, under either planned or accidental circumstances. In this paper, the potential storage of very low energy antiprotons is discussed, and the major features of the radiation fields produced by their annihilations are reviewed both qualitatively and quantitatively. Detailed Monte Carlo shielding calculations for a conceptual source of annihilating antiprotons nearly at rest are presented. It is concluded that these radiation fields are readily understood and that the radiation hazards can be mitigated using conventional means.

To protect the CDF detector components in an event of an abort kicker prefire (AKP) in the Tevatron, a new collimator is to be installed at the A48 location during the summer 2003 shutdown. Detailed calculations have shown that this 0.5-m long ''single L-shape'' steel collimator will intercept a bunch of protons when such an incident occurs, providing reliable protection of the CDF main detector at an AKP. It will also mitigate the backgrounds induced by elastic beam-gas interactions upstream of B0. Although the Roman Pot detectors downstream of the A48 collimator will see an increased background, the amount of radiation they will receive either resulting from beam halo interactions in the collimator or during an AKP will not damage their sensitive parts. Secondaries resulting from beam halo interactions with the A48 collimator do not noticeably affect the downstream dipoles. The case of an AKP is quite different. As opposed to halo hits in the ''single-L shape'' unit (around 10{sup 5} p/s), a bunch lost on A48 during an AKP represents more than 2 x 10{sup 11} protons ''instantaneously'' interacting with the collimator material. Although the collimator protects the downstream superconducting (SC) dipoles against a damage in such an event,more » secondaries generated in A48 create a significant radiation load on the dipoles which will most likely result in a quench of the first one. This effect is studied in detail in this note. Energy deposition in the B0 dipoles downstream of a new A48 collimator to be installed in the Tevatron this summer is calculated with the MARS14 code to evaluate the dipole's quench stability at an abort kicker prefire.« less

To estimate groundwater activation around the Fermilab Switchyard, Meson Target Train and M03 Meson beam dumps at 120 GeV, express MARS14 [1] simulations have been performed. A proton beam RMS spot size is {sigma}{sub x}={sigma}{sub y}=1 cm in the first two cases, while {sigma}{sub x}={sigma}{sub y}=2 cm for M03. Calculated are star density distributions (above 50 MeV) normalized per one incident proton. The configurations proposed by Chuck Brown have been implemented into the MARS code.

A new three-dimensional visualization engine has been developed for the MARS14 code system. It is based on the OPENINVENTOR graphics library and integrated with the MARS built-in two-dimensional Graphical-User Interface, MARS-GUI-SLICE. The integrated package allows thorough checking of complex geometry systems and their fragments, materials, magnetic fields, particle tracks along with a visualization of calculated 2-D histograms. The algorithms and their optimization are described for two geometry classes along with examples in accelerator and detector applications.

Operational and accidental beam losses in hadron colliders can have a serious impact on machine and detector performance, resulting in effects ranging from minor to catastrophic. Principles and realization are described for a reliable beam collimation system required to sustain favorable background conditions in the collider detectors, provide quench stability of superconducting magnets, minimize irradiation of accelerator equipment, maintain operational reliability over the life of the machine, and reduce the impact of radiation on personnel and the environment. Based on detailed Monte‐Carlo simulations, such a system has been designed and incorporated in the Tevatron collider. Its performance, comparison to measurements and possible ways to further improve the collimation efficiency are described in detail. Specifics of the collimation systems designed for the SSC, LHC, VLHC, and HERA colliders are discussed.

In contrast to hadron colliders where particle backgrounds come both from interaction point (IP) and accelerator, almost all the backgrounds in the muon collider detectors aris in the machine. Two major classes of detector backgrounds, beam halo backgrounds and electorn backgrounds from μ→eνν decay occurring in the beam channel, in the muon collider are discussed. The nature of both of these backgrounds, results of calculations for both of these sources, and their effects on plausible detectors are discussed. Various shielding and collimation geometries have been simulated, and their efficacy and the nature of the surviving background discussed.(AIP)1995 American Institute of Physics.