US 6,982,428 B2
Particle detection by electron multiplication
Richard Stresau, Sydney (Australia); Kevin Hunter, Glenhaven (Australia); Wayne Sheils, Winmalee (Australia); Peter Raffin, Petersham (Australia); and Yair Benari, Hornsby (Australia)
Assigned to ETP Electron Multipliers Pty Ltd, Ermington (Australia)
Filed on Jan. 16, 2004, as Appl. No. 10/758,015.
Claims priority of application No. 2003900277 (AU), filed on Jan. 20, 2003.
Prior Publication US 2004/0159796 A1, Aug. 19, 2004
Int. Cl. G21G 5/00 (2006.01); H01J 25/50 (2006.01); H01J 19/82 (2006.01)
U.S. Cl. 250—492.3 35 Claims
OG exemplary drawing
 
1. A particle detector employing electron multiplication, comprising:
cathode means defining an impact surface on which particles impact, which surface has a finite probability of generating at least one electron for each impacting particle having predetermined characteristics;
a plurality of electron multiplication dynode segments, including a first dynode segment, arranged in an array; and
respective means for generating electrostatic and magnetic fields in a space extending from said impact surface past said dynode segments, whereby said electrons cascade and multiply successively along said array of dynode segments;
wherein said means for generating said magnetic and electrostatic fields are configured whereby the E/B2 ratio adjacent any of said dynode segments is smaller than adjacent the preceding dynode segment or impact surface relative to the direction of the cascade, whereby to decrease the radius of curvature of the electron trajectories along said cascade and to thereby focus the electron trajectories in at least one dimension.