The BIOCORE (BIOlogical COsmic Ray Experiment) Pocket Mouse Radiation Dosimeters are designed to record the trajectories of HZE cosmic ray particles passing through the heads of the mice to monitor injury to the brain and the eyes. For the dosimeter to retain its position beneath the scalp, it was necessary to develop a platform on which the dosimeter could be mounted to the skull.

Radiation Dosimeter: The particle detector is composed of four layers of plastic, the outer two layers of Lexan polycarbonate, and in between, two layers of cellulose nitrate (CN). The outer edges of the two Lexan layers are heat sealed, encasing the CN layers to form a rigid, compact dosimeter. The original surface area of the dosimeter is approximately 65 mm², while the usable (original less heat sealed) area for particle monitoring is 55 mm². From testing with experimental LET values, it was determined that cosmic ray particles with Z ¾ 8 which first register in the plastics are likely to have stopped before reaching the head. The dosimeter coated with 0.04- 0.04 mm Paralene C for protection against tissue fixatives. The dosimeter is designed to cover the entire brain from the olfactory bulbs anteriorly to the cerebellum posteriorly. The plastics are chemically etched postflight to render latent tracks produced by the passage of high-LET particles microscopically visible. For tracing trajectories into the heads, each particle trajectory in the flight mouse dosimeters was angularly measured with a stereotaxic apparatus, charted manila dosimeter mock-ups, and replicated on a control mice using a drill or needle.

Dosimeter Platform: The dosimeter is mounted on a custom platform, the underside of which is contoured to the skull. Platforms are cast in a mold prepared from the the upper part of the target skull. The front part of the platform is cut even with the front of the dosimeter. Platforms are constructed so as to minimize the distance between the dosimeter and skull. Maximum distance from the under surface of the most posterior part of dosimeter to the skull is 1 mm; the shortest distance between the dosimeter and the eyes is 1.38 mm. The assembly is implanted beneath the mouse scalp, where scalp tension fixes its position with respect to the skull.

Dimensions: 7.0 x 13.8 x 0.5842 mm

Weight: Unknown

Power: None

Surface Area: 65 mm² (55 mm² usable)

Thickness (Lexan): 0.19 mm (each layer)

Thickness (CN): 0.11 mm (each layer)

Radiation particle trajectory data

Mounting Boxes: Made of anodized aluminum. Head is supported by tapered bars inserted into each external auditory meatus, a jaw bar for snout, and a nose clamp.