Page 152 of Radiation Medicine QA Solutions 2008/2009 by PTW

health physics radiation monitoring equipment moderator sphere neutron area monitor 0.1 liter chamber for radiation monitoring 300 mm polyethylene sphere for area monitoring of natural neutron radiation background using albedo dosemeters features suitable for area radiation monitoring measures the neutron component of the annual background radiation in three months periods uses the albedo neutron dosemeters the moderator sphere1 is a passive dose equivalent meter for area monitoring of natural radiation background it measures the neutron component of the natural annual background radiation of about 30 µsv the monitoring period is at least 3 months the passive neutron dose equivalent meter consists of a moderator polyethylene sphere of 300 mm diameter and a detector holder placed at a central position in the sphere an albedo dosemeter case with inserted tld card is placed inside the detector holder for measurement the user must specify the types of tld card and albedo dosemeter case in addition to the standard version of the moderator sphere a waterproof version is available for use in the open air a special support made of aluminum is used to set up the moderator sphere free in air at a certain distance from backscatter material 1 the moderator sphere has been developed in co-operation with the research center karlsruhe germany cylindrical al chamber for stationary and mobile radiation monitoring of high level gamma radiation features vented sensitive volume of 102 cm3 suitable as radiation monitoring chamber rigid construction for wall mounting gamma energy range 80 kev to 1.3 mev the 0.1 liter chamber is used for environmental radiation monitoring the rigid and compact construction makes the chamber suitable for stationary radiation monitoring as well as for mobile operation in vehicles due to its small size the chamber only requires little space the chamber is designed to measure very high dose rates of up to 4000 sv/h 90 saturation as they may occur after nuclear accidents the response is 3 · 10-6 c/sv since the sensitive volume is open to the surroundings air density correction is required for precise measurement the chamber is fully guarded up to the measuring volume the cylindrical chamber is made of aluminum with 4 mm wall thickness the ion-collecting electrode is made of aluminum too the external chamber diameter is 60 mm and the length is approx 150 mm for the transfer of the measuring signal and the polarizing voltage the chamber is supplied with two coaxial fischer connectors via an optional adapter cable of 1.5 m length the chamber can be connected to a dosemeter with m connector which has input circuits on ground potential the maximum length of an extension cable is 100 m the maximum chamber polarizing voltage is 500v ordering information t860 moderator sphere 300 mm t860/u901 moderator sphere 300 mm waterproof t8601 albedo dosemeter case insert for moderator sphere ordering information t32001 radiation monitoring chamber 0.1 l option t8602 support for moderator sphere albedo neutron dosemeter cases page 151 option t7262/u10-1.5 connection cable with m connector length 1.5 m unidos/unidos e dosemeters page 154 152

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