Luminescent material including a rare earth halide and an apparatus including such material

1. A luminescent material including a rare earth halide having a chemical formula of:

RE (1-A-B-C) HT A DET B SET C X z ,

wherein:

RE is a rare earth element,

HT is an element or an interstitial site that provides a hole trap, wherein HT is selected from the group consisting of Ce, Pr, Sm, and Tb;

DET is a dopant that provides a relatively deep electron trap, wherein DET is selected from the group consisting of Group 1 elements and Group 2 elements other than Ca and Sr,

SET is a dopant that provides a relatively shallow electron trap, wherein SET is selected from the group consisting of Ca and Sr,

X is one or more halides,

each of A, B, and C has a value greater at least 0.00001 and at most 0.09,

Z has a value in a range of 2 to 4, and

a ratio of B:C is between 10:1 and 100:1 on an atomic basis.

2. The luminescent material of claim 1 , wherein the average value for the departure from perfect linearity (DFPL average ) is determined by:

DFP

⁢

L

a

⁢

v

⁢

e

⁢

r

⁢

a

⁢

g

⁢

e

=

∫

E

lower

E

upper

DFPL

⁡

(

E

i

)

·

dE

i

E

upper

-

E

lower

,

where

DFPL(Ei) is DFPL at energy E i ;

E upper is 20 keV; and

E lower is 5 keV.

3. The luminescent material of claim 1 , wherein the ratio of B:C is in a range of 15:1 to 95:1.

4. The luminescent material of claim 1 , wherein the ratio of B:C is in a range of 30:1 to 70:1.

5. The luminescent material of claim 3 , wherein Z has a value in a range of 2.8 to 3.2.

6. The luminescent material of claim 3 , wherein the luminescent material includes a base compound, wherein the base compound, without any dopant, has a minimum energy level of a conduction band that is closer to an ionization energy of the SET than to an ionization energy of the DET.

7. The luminescent material of claim 3 , wherein the luminescent material includes a base compound, wherein the base compound, without any dopant, has a bandgap energy, wherein an energy level difference between a minimum energy level of a conduction band of the base compound without any dopant and an ionization energy of the SET is at most 10% of the bandgap energy.

8. The luminescent material of claim 3 , wherein the luminescent material includes a base compound, wherein the undoped base compound, without any dopant, has a bandgap energy, wherein an energy level difference between a minimum energy level of a conduction band of the base compound without any dopant and an ionization energy of the DET is greater than 10% of the bandgap energy.

9. The luminescent material of claim 3 , wherein the luminescent material includes a base compound, wherein an energy level difference between a minimum energy level of a conduction band of the base compound without any dopant and an ionization energy of the SET is at most 0.3 eV.

10. The luminescent material of claim 9 , wherein the luminescent material includes a base compound, wherein an energy level difference between a minimum energy level of a conduction band of the base compound without any dopant and an ionization energy of the DET is greater than 0.3 eV.

11. A radiation detection apparatus comprising:

a scintillator having a formula RE (1-A-B-C) HT A DET B SET C X z ,

wherein:

RE is a rare earth element or Bi,

HT is an element or an interstitial site that provides a hole trap, wherein HT is selected from the group consisting of Ce, Pr, Sm, and Tb;

DET is a dopant that provides a relatively deep electron trap, wherein DET is selected from the group consisting of Group 1 elements and Group 2 elements other than Ca and Sr,

SET is a dopant that provides a relatively shallow electron trap, wherein SET is selected from the group consisting of Ca and Sr,

X is one or more halides,

each of A, B, and C has a value greater at least 0.00001 and at most 0.09,

Z has a value in a range of 2 to 4, and

a ratio of B:C is between 10:1 and 100:1 on an atomic basis; and

a photosensor configured to receive scintillating light from the luminescent material.

12. The radiation detection apparatus of claim 11 , wherein an energy level difference between a minimum energy level of a conduction band of the base compound without any dopant and an ionization energy of SET is at most 0.3 eV.

13. The radiation detection apparatus of claim 11 , wherein an energy level difference between a minimum energy level of a conduction band of the base compound without any dopant and an ionization energy of DET is greater than 0.3 eV.

14. The radiation detection apparatus of claim 11 , wherein the DET includes a Group 1 element, Mg, or Ba.

15. The radiation detection apparatus of claim 11 , wherein the HT, the DET, or the SET is Eu or Yt.

16. The radiation detection apparatus of claim 11 , wherein the ratio of B:C is in a range of 15:1 to 95:1.

17. The radiation detection apparatus of claim 11 , wherein the ratio of B:C is in a range of 20:1 to 80:1.

18. The radiation detection apparatus of claim 11 , wherein the ratio of B:C is in a range of 30:1 to 70:1.

19. The radiation detection apparatus of claim 11 , wherein the luminescent material includes a base compound, wherein the base compound, without any dopant, has a bandgap energy, wherein an energy level difference between a minimum energy level of a conduction band of the base compound without any dopant and an ionization energy of the SET is at most 10% of the bandgap energy.

20. The radiation detection apparatus of claim 11 , wherein the luminescent material includes a base compound, wherein the undoped base compound, without any dopant, has a bandgap energy, wherein an energy level difference between a minimum energy level of a conduction band of the base compound without any dopant and an ionization energy of the DET is greater than 10% of the bandgap energy.