Scintillation crystal including a co-doped rare earth silicate, a radiation detection apparatus including the scintillation crystal, and a process of forming the same
A scintillation crystal can include a rare earth silicate, an activator, and a Group 2 co-dopant. In an embodiment, the Group 2 co-dopant concentration may not exceed 200 ppm atomic in the crystal or 0.25 at % in the melt before the crystal is formed. The ratio of the Group 2 concentration/activator atomic concentration can be in a range of 0.4 to 2.5. In another embodiment, the scintillation crystal may have a decay time no greater than 40 ns, and in another embodiment, have the same or higher light output than another crystal having the same composition except without the Group 2 co-dopant. In a further embodiment, a boule can be grown to a diameter of at least 75 mm and have no spiral or very low spiral and no cracks. The scintillation crystal can be used in a radiation detection apparatus and be coupled to a photosensor.
1. A scintillation crystal comprising a rare earth silicate, a first dopant, and a second dopant, wherein:
the first dopant is an activator and has a first atomic concentration;
the second dopant includes Ca and has a second atomic concentration that does not exceed 200 ppm atomic based on a total rare earth content of the scintillation crystal; and
the scintillation crystal has a decay time of at least 15 ns and no greater than 40 ns.
2. The scintillation crystal of claim 1 , wherein the first dopant has a concentration in the scintillation crystal of at least 20 atomic ppm based on a total rare earth content in the scintillation crystal.
3. The scintillation crystal of claim 1 , wherein the atomic concentration of Ca does not exceed 160 ppm atomic based on a total rare earth content of the scintillation crystal.
4. The scintillation crystal of claim 1 , the scintillation crystal has a decay time of no greater than 38 ns.
5. The scintillation crystal of claim 1 , the scintillation crystal has a decay time of no greater than 36 ns.
6. The scintillation crystal of claim 1 , wherein the second dopant is Ca and has a concentration in the scintillation crystal no greater than 160 atomic ppm based on a total rare earth content in the scintillation crystal.
7. A scintillation crystal comprising a formula of Ln 2 SiO 5 :Ac, Me, wherein:
Ac is a first dopant and has a first atomic concentration, wherein the first dopant is Ce, Pr, Tb, or any combination thereof;
Ln includes one or more rare earth elements different from the first dopant;
Me is a second dopant and includes a Group 2 element and has a second atomic concentration that does not exceed 200 ppm atomic based on a total rare earth content of the scintillation crystal; and
the scintillation crystal has a decay time of no greater than 40 ns.
8. The scintillation crystal of claim 7 , wherein the first dopant has a concentration in the scintillation crystal of at least 20 atomic ppm based on a total rare earth content in the scintillation crystal.
9. The scintillation crystal of claim 7 , wherein the first dopant is an activator.
10. The scintillation crystal of claim 7 , wherein the second dopant is Ca.
11. The scintillation crystal of claim 7 , wherein Ln is Y, Gd, Lu, or any combination thereof.
12. The scintillation crystal of claim 7 , wherein Ln is Lu or Lu(1-x)Yx, wherein 0.0<x<1.0.
13. A Positron Emission Tomography (PET) device, comprising:
a scintillation crystal within the PET device, wherein the scintillation crystal comprises:
a rare earth silicate;
a first dopant; and
a second dopant, wherein the first dopant is an activator and has a first atomic concentration, wherein the second dopant includes a Group 2 element and has a second atomic concentration that does not exceed 200 ppm atomic based on a total rare earth content of the scintillation crystal, and wherein the scintillation crystal has a decay time no greater than 40 ns.
14. The PET device of claim 13 , wherein the PET device is a Time of Flight Positron Emission Tomography (TOP PET) imaging device.
15. The scintillation crystal of claim 13 , wherein the second dopant is Ca.
16. The scintillation crystal of claim 13 , wherein the second dopant is Ca and has a concentration in the scintillation crystal no greater than 160 atomic ppm based on a total rare earth content in the scintillation crystal.
17. The scintillation crystal of claim 13 , the scintillation crystal has a decay time of no greater than 38 ns.
18. The scintillation crystal of claim 13 , the scintillation crystal has a decay time of no greater than 36 ns.