The magnetization M-p of proximity-effect-induced superconducting Cu (PEISC) in multifilacentary NbTi/Cu composite conductors has been measured in transverse fields B-e smaller than B-cl of the NbTi filament at 4.2 K. The conductors were designed specifically to subtract out the magnetization of the NbTi filaments from magnetization of the conductors. The filament spacing is 1.38 mum and the width of the regular hexagonal filament is 7.60 mum. Twist pitches are 6.9, 13, 20, 94 and 189 mm. M-p was investigated as a function of the twist pitch I, and the field amplitude B,. The first penetration field B,,, of the magnetic flux, the decoupling field B-dp Of the filament coupling, and the width of the,II, at a given field are directly proportional to the twist pitch. ill, magnetization loops intersect each other for B-clp less than or equal to B-m less than or equal to B-dp and decrease suddenly at B-dp. The critical current density J(cp) of PEISC is proportional to B-e(-2) and its value is 10 kA/m(2) at 7 mT. (C) 2001 Elsevier Science B.V. All rights reserved.