SpacePhysicsDivision AirForceGeophysics Laboratory HanscomAFB,MA 01731

Data fromthe DMSP/F7satellitedosimeterstar eventcountersarepresented. TheDMSPdosimeterstar event counters measure the numberof pulsesthat exceedset energydeposition levels(40MeVforthree detectorsand75 MeV forthefourthdetector) behind fourdifferent thicknesses ofaluminumshielding. The term "starevent"is used becauselinearenergy transferdepositions above40 MeV can be produced by high energyproton or heavyion interactions with nucleiinthedetectorcreating a startypereleaseof energeticsecondaries.The energydeposition that createsthehighenergypulsesin thedetectors can come eitherdirectlyfrom incidentcosmic rays, directlyfromhighenergyprotonsthattraverselong pathlengthsin the detectorvolume,indirectly from nuclearreactionsin thedetectorcreatedbyincident high energy protons,or indirectly from nuclear reactionsinthevicinityof thedetectorwhichcreate recoiling nucleithatdepositenergyin thedetector. Thesenuclearstars and directenergypulsescreate singleeventupsets(SEUs)in microelectronic components in thenear-Earthspaceenvironment.Herewe willfirstdescribetheproperties ofthestarchannel of the dosimeteron DMSP/F7; thenpresentthe star countmapsof the840km regionof space;andfinally discusstheirrelationto upsetphenomena.