the thickness of the thin strip is preferably less than 1 mm the width of the thin strip and thus the basic plates 15 see element c in fig4 is preferably 5 to 40 mm the length of the basic plates 15 is preferable n u00d7 b where n is an integer and b is the element shown in fig4 fig6 b illustrates the step of forming fine grooves and or ridges on the surface of the front and back sides of basic plates 15 referring to fig6 b fine grooves and ridges 16 are formed as a mesh on the surface of basic plates 15 this is done to improve adhesion of the adhering ti or tin particles the textured side walls also allow the resulting collimator to be more readily cleaned as a result of the two foregoing advantages contamination particles can be suppressed in the reactive container fig6 c illustrates the step of folding the patterned strips to form a portion of a series of pillar cells referring to fig6 c a pair of opposing folded strips are mated basic plate 15 for basic plate 15 to form hexagonal shaped pillar cells fig6 d illustrates the step of welding the mated pair of patterned strips to produce a final hexagonal shaped pillar structure referring to fig6 d the folded strips are welded so that various cells are connected to each other reference numeral 17 denotes the points to be welded once welded the pillar cells are bundled and placed into the cylindrical structure of the collimator shown in fig3 material used.