title: New PTB thermal neutron calibration facility: first results.
abstract: A new thermal neutron calibration facility based on a moderator assembly has been set up at PTB. It consists of 16 (241)Am-Be radionuclide sources mounted in a graphite block, 1.5 m wide, 1.5 m high and 1.8 m deep. The sources are distributed to eight different positions, at a mean distance of ∼1.25 m from the front face of the moderator. The neutron field at the reference position, 30 cm in front of the moderator device and 75 cm above the floor, has been characterised using calculations, Bonner sphere measurements and gold foil activation. First results are shown. The field is highly thermalised: 99 % in terms of fluence. It is quite homogenous within a 20 cm×20 cm area, but the absolute value of the thermal neutron fluence rate is small and yields an ambient dose equivalent rate of 3 µSv h(-1).
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, Braunschweig D-38116, Germany marlies.luszik-bhadra@ptb.de.
authors.forename: M
authors.initials: M
authors.lastname: Luszik-Bhadra
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, Braunschweig D-38116, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Reginatto
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, Braunschweig D-38116, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Wershofen
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, Braunschweig D-38116, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Wiegel
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, Braunschweig D-38116, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Zimbal
mesh_terms: D000576:Americium; D001608:Beryllium; D002104:Cadmium; D002138:Calibration; D004867:Equipment Design; D005160:Facility Design and Construction; D005857:Germanium; D005858:Germany; D006108:Graphite; D015994:Incidence; D009010:Monte Carlo Method; D009502:Neutrons; D009688:Nuclear Reactors; D019047:Phantoms, Imaging; D020959:Polyethylene; D011835:Radiation Protection / Q000295:instrumentation* / Q000379:methods; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D013696:Temperature
chemical_list: D005857:Germanium; D002104:Cadmium; D006108:Graphite; D020959:Polyethylene; D001608:Beryllium; D000576:Americium