Ionization window

A detector, comprising:

• a pressurized chamber;
• a source of ionizing radiation at least partially in the chamber;
• an ionization window on at least one side of the chamber that allows the ionizing radiation to exit the chamber, the ionization window including
• a support layer having a thickness between a first side and a second side, at least one opening in the support layer extending between the first and second sides, the at least one opening having a first width dimension near the first side of the support layer and a second, larger width dimension near the second side of the support layer;
• and
• a window layer supported on the second side of the support layer, the window layer extending across the at least one opening to allow the ionizing radiation to pass through the at least one opening in a direction from the first side toward the second side and to exit the chamber.

A method of making an ionization window, comprising the steps of:

• establishing a plurality of support members on a wafer with a plurality of spaces between the support members;
• establishing a first width near one end of each the spaces;
• establishing a second, larger width near a second end of each of the spaces;
• coating the support members and the wafer in the spaces with a continuous ionization window layer;
• and
• removing material of the wafer adjacent the ionization window layer at the spaces between the support members to leave only the ionization window layer across the openings near the one end of the spaces.