Array of virtual Frisch-grid detectors with common cathode and reduced length of shielding electrodes
A radiation detector system that effectively solves the electron trapping problem by optimizing shielding of individual virtual Frisch-grid detectors in an array configuration with a common cathode.
1. A virtual Frisch-grid detector array comprising
a circuit board;
a plurality of virtual Frisch-grid detectors electrically connected to the circuit board wherein each virtual Frisch-grid detector comprises a semiconductor capable of operating as a single-carrier-transport device having a first surface and a second surface;
an anode connected to the first surface of the semiconductor and the circuit board;
a common cathode for the plurality of virtual Frisch-grid detectors, wherein the common cathode is connected to the second surface of the semiconductors;
a shielding electrode producing the virtual Frisch-grid effect spanning the perimeter of the semiconductor between the first surface and the second surface; and
a capacitor electrically connected to the common cathode and the circuit board.
2. A virtual Frisch-grid detector array according to claim 1 , further comprises a side insulating layer between the side surface of the semiconductor and the shielding electrode producing the virtual Frisch-grid effect.
3. A virtual Frisch-grid detector array according to claim 1 , wherein the shielding electrode is made from conducting metals.
4. A virtual Frisch-grid detector array according to claim 3 , wherein the conducting metals are selected from copper (Cu) or aluminum (Al).
5. A virtual Frisch-grid detector array according to claim 1 , further comprising an insulated wire running in-between a gap between two or more virtual Frisch-grid detectors, the insulated wire being attached to the circuit board at one end and the capacitor at an other end.
6. A virtual Frisch-grid detector array according to claim 1 , wherein a ratio between a cathode signal and an anode signal is used to reject events interacting close to the anode.
7. A virtual Frisch-grid detector array according to claim 1 , wherein the semiconductor is selected from the group consisting of Group III-V semiconductors and Group II-VI semiconductors.
8. A virtual Frisch-grid detector array according to claim 7 , wherein the semiconductor is made from binary compounds or ternary compounds or alloys.
9. A virtual Frisch-grid detector array according to claim 1 , wherein the semiconductor is selected from the group consisting of CdZnTe, CdTe, CdMnTe, HgI 2 , TlBr, HgCdTe, CdMnTe, HgZnSe, GaAs, PbI 2 , AlSb, InP, ZnSe, ZnTe, PbO, BiI 3 , SiC, Hg x Br 1-x I 2 , Hg x Cd 1-x I 2 , wherein x is greater than 0 and less than 1, InI 2 , Ga 2 Se 3 , Ga 2 Te 3 , TlPbI 3 , Tl 4 HgI 6 , Tl 3 As 2 Se 3 , TlGaSe 2 , and AgGaTe 2 .
10. A virtual Frisch-grid detector array according to claim 2 , wherein the side insulating layer is an insulating material made from a metal oxide, glass-ceramic, polyimide, photoresist, polymers, plastics, carbide ceramics, nitride ceramics or a combination thereof.
11. A virtual Frisch-grid detector array according to claim 10 , wherein the metal oxide is an alumina, zirconium oxide or quartz.
12. A virtual Frisch-grid detector array according to claim 2 , wherein the side insulating layer has a thickness adequate to provide electrical isolation and to avoid dielectric breakdown between the full-area metal anode and any surfaces with a differential bias.
13. A virtual Frisch-grid detector array according to claim 12 , wherein the side insulating layer has a thickness of about 10-2000 microns.
14. A virtual Frisch-grid detector array according to claim 1 , wherein the capacitor and circuit board are connected via a wire passing between the plurality of virtual Frisch-grid detectors.
15. A virtual Frisch-grid detector array according to claim 14 , wherein the wire passes between the plurality of virtual Frisch-grid detectors in an insulated conduit.
16. A radiation detector system comprising:
a virtual Frisch-grid detector array according to claim 1 ;
at least one application-specific-integrated-circuit (ASIC) connected to the virtual Frisch-grid detector array operable to receive a signal from said array; and
at least one microprocessor connected with the ASIC operable to control the ASIC.
17. The radiation detector system of claim 16 , wherein the at least one ASIC is attached to the circuit board.
18. The radiation detector system of claim 17 , further comprising a cooling plate thermally connected to the at least one ASIC.