The High-density Multiwire Drift Chamber

A multiwire propor t ional chamber , with a high-densi ty drift space at tached, has been developed as a posit ion-sensit ive detector for nonioniz ing radiat ion. A chamber with a 5 g /cm a d r i f t s p a c e , compris ing a l eadb i smuth matr ix o f 1 m m square holes on a 1.5 m m pi tch has been investigated. For 0.66 MeV pho tons a detection efficiency o f 5%, combined with a spatial resolut ion o f 1.3 m m fwhm, is obtained. M u c h higher efficiencies are possible. A theoretical analysis oi the detection efficiency as a funct ion o f pho ton energy is presented. It agrees well with exper imental results. The chamber offers new possibilities for pho ton and neut ron detection, and as a shower detector for high-energy particles.