GB813616A - Improvements in electroscopes for radiation detection - Google Patents

Abstract

813,616. Electroscopes. PHILIPS ELECTRICAL INDUSTRIES Ltd. June 17, 1957 [June 15, 1956], No. 18607/56. Class 37. [Also in Group XX] In a dosimeter of the insulated fibre type, a wire support to which the fibre is secured is carried on a conducting member which forms one electrode of the dosimeter ionization chamber, and the conducting member is supported within the ionization chamber by supports of insulating material which can engage the conducting member at one point at one end and at two points at the other end. As shown, the fibre 1 is in the form of an inverted U secured at its ends to a pair of aluminium support wires 2 which in turn are mounted at one end of a mounting head 3. The mounting head is a hollow cylinder of conducting plastic material such as graphite loaded " Bakelite " (Registered Trade Mark). An extension 4 of the mounting head constitutes the electrostatic deflector electrode for the fibre. The mounting head constitutes the inner wall of an ionization chamber, the outer wall 5 of which consists of conducting plastic material of the same character as the mounting head. The outer wall flts closely within an aluminium sheath 6. At the upper end of the chamber, an insulator 7 has a single projection 8 the end of which engages the end of the projection 4, which is flat, whereas the end of the projection 8 is rounded so that a very small area of contact results. Projections 4 and 8 are held in alignment by means of a pin 9. A lens clamp 11 at the lower end of the mounting head 3 has a pair of diametrically opposite recesses 12, the flat end faces of which are each engaged by one of a pair of correspondingly disposed rounded projections 14 on a lower insulator 13. These projections are also provided with a lining pin similar to the pin 9. The fibre is observed by means of a lens 24 secured to the upper end of the casing. A graticule 16, mounted on a support 17 at the lower end of the chamber, and a lens 25 mounted on the lens clamp 11, are arranged as described in Specification 813,615, [Group XX], in order to provide a reference scale for measuring the actual position of the fibre. The insulated mounting head 3 carrying the fibre 1 may be charged initially by means of a spring-loaded plunger 26, the end cap 27 with a window 28 being removed for this purpose.