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Abbreviated form of the title (less than 50 characters): Simulations for a 25 keV electron microbeam in water. [4,5]. Event by event trackstructure codes like PITS are considered superior for microdosimetric applications and they are written for this purpose. PITS tracks electrons in water down to 10 eV. PENELOPE is one of the few, among widely available general purpose codes, that can simulate random electron-photon showers in any material for energies from 100eV to 1GeV.The model for the comparison is a large water cylinder with an internal scoring geometry of spheres with 1µm diameter where the scoring quantities are calculated. The source is a 25 keV electron pencil beam impinging normally on the sphere surface. This work shows only the lineal energy as a function of position and lineal energy spectra at a given location since for microdosimetry and biology applications, and for discussion of radiation quality in general, these answers are more appropriate [6][7][8][9]. The computed PENELOPE results are in agreement with those obtained with the PITS code and previously published in this journal [3]. This paper demonstrates PENELOPE's usefulness at low energies and for small geometries. What is still needed are experimental results to confirm these analyses.

SUMMARYThere are more and more third-generation synchrotron radiation (SR) facilities in the world that utilize low emittance electron (or positron) beam circulating in a storage ring to generate synchrotron light for various types of experiments. A storage ring based SR facility consists of an injector, a storage ring, and many SR beamlines. When compared to other types of accelerator facilities, the design and practices for radiation safety of storage ring and SR beamlines are unique to SR facilities.Unlike many other accelerator facilities, the storage ring and beamlines of a SR facility are generally above ground with users and workers occupying the experimental floor frequently. The users are generally non-radiation workers and do not wear dosimeters, though basic facility safety training is required. Thus, the shielding design typically aims for an annual dose limit of 100 mrem over 2000 h without the need for administrative control for radiation hazards. On the other hand, for operational and cost considerations, the concrete ring wall (both lateral and ratchet walls) is often desired to be no more than a few feet thick (with an even thinner roof).Most SR facilities have similar operation modes and beam parameters (both injection and stored) for storage ring and SR beamlines. The facility typically operates almost full year with one-month start-up period, 10-month science program for experiments (with short accelerator physics studies and routine maintenance during the period of science program), and a month-long shutdown period. A typical operational mode for science program consists of long periods of circulating stored beam (which decays with a lifetime in tens of hours), interposed with short injection events (in minutes) to fill the stored current. The stored beam energy ranges

The effects on the response of eight radiation survey instruments in static magnetic fields up to 0.03 T (300 G) have been investigated. The instruments studied are the Xetex 303B Pacer, the Bicron Micro Rem survey meter, the Victoreen 450p survey meter, the Victoreen 440 survey meter, the SLAC orange meter, the Keithley 36150 survey meter, the Anderson-Braun neutron remmeter, and the Victoreen 488 neutron survey meter. The results show that the effect may depend on several factors such as instrument design, alignment of the instrument axis with the magnetic flux lines, whether the instrument is stationary or moving relative to the magnetic field, the direction of the movement relative to the magnetic flux lines, and the magnetic field intensity. Also presented are results of work to enhance magnetic shielding of some of the instruments.

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