A METHOD OF SHORTENING THE SCINTILLATION

Abstract

Problem to be solved: Currently, the known manner of shortening the scintillation response of scintillation material is to suppress the amplitude-minor slower components (2) of the scintillation response, whereas the possibilities of significant shortening of the amplitude-dominant component of the scintillation response in this manner are limited.

Solution: The invention concerns the manner of shortening the scintillation response of scintillator luminescence centres which uses co-doping with Ce or Pr together with co-doping with ions from the lanthanoids, 3d transition metals, 4d transition metals or 5s.sup.2 or 6s.sup.2 ions group. Having had the luminescence centres electrons excited as a result of absorbed electromagnetic radiation, the scintillator created in this manner is capable of taking away a part of the energy from the excited luminescence centres via a non-radiative energy transfer, which results in a significant shortening of the time of duration of the amplitude-dominant component (1) of the scintillation response.

Claims

1. A manner of shortening the scintillation response of a scintillator creating luminescence centres, containing at least one dopant Ce and/or Pr, wherein after excitation of electrons of the luminescence centres as a result of the absorbed electromagnetic radiation, a part of energy from the excited luminescence centres is taken away with a non-radiative energy transfer and a time of duration of the amplitude-dominant component of a scintillation response is shortened and the taking away of a part of energy in a non-radiative energy transfer is performed by inserting minimally one kind of a first co-dopant in the structure of the scintillator material, and the FWHM marking a co-dopant absorption band is in the extent of HWHM from the wavelength of a dopant emission band maximum where HWHM is half width at half maximum of the emission band.

2. A manner according to claim 1, wherein the first co-dopant is selected from a group of lanthanoids, 3d transition metals, 4d transition metals or 5s.sup.2 (In.sup.+, Sn.sup.2+, Sb.sup.3+) or 6s.sup.2 (Tl.sup.+, Pb.sup.2+, Bi.sup.3+) ions.

3. A manner according to claim 1, wherein at least one second co-dopant from a group of optically inactive ions is inserted in the structure of the scintillator material and the intensity of slower secondary components of the scintillation response is reduced.

4. A manner according to claim 3, characterized in that the second co-dopant is the Mg.sup.2+ or Ca.sup.2+ cation.

5. A scintillator material based on garnet with a general chemical formula A.sub.3B.sub.5O.sub.12 with shortened scintillation response by method of claim 1, wherein it corresponds to a general chemical formula A.sub.3x1x2.sup.1M.sub.x1.sup.2M.sub.x2B.sub.5O.sub.12 where substituent A is represented by a cation from the Y.sup.3+, Lu.sup.3+, Gd.sup.3+ group or their mixture, substituent B is represented by a cation from the Al.sup.3+, Ga.sup.3+, Sc.sup.3+, Mo.sup.3+group or their mixture, substituent .sup.1M represents a dopant cation from the Ce.sup.3+ or Pr.sup.3+ group and substituent .sup.2M represents a first codopant cation from the Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm lanthanoids group or from the Ti, V, Cr, Mn, Fe, Co, Ni, Cu 3d transition metals group or from the Zr, Nb, Mo, Ru, Rh, Ag 4d transition metals group or from the Ta, W 5d transition metals group or from the 5s.sup.2 In, Sn, Sb ions group or from the 6s.sup.2 Tl, Pb, Bi ions group.

6. A material according to claim 5 wherein the substituent .sup.2M represents a mixture of the first co-dopant and the second co-dopant where the second co-dopant is from the group of optically inactive ions.

7. A material according to claim 6 wherein substituent .sup.2M represents a mixture of the first co-dopant and the second co-dopant where the second co-dopant is a Mg.sup.2+ or Ca.sup.2+ cation.

8. A scintillator material based on perovskite with a general chemical formula ABO.sub.3 with shortened scintillation response by method of claim 1 wherein it corresponds to a general chemical formula A.sub.1x1x2.sup.1M.sub.x1.sup.2M.sub.x2BO.sub.3 where substituent A is represented by a cation from the Y.sup.3+, Lu.sup.3+, Gd.sup.3+ group or their mixture, substituent B is represented by a cation from the Al.sup.3+, Ga.sup.3+, Sc.sup.'+, Mo.sup.3+ group or their mixture, substituent .sup.1M represents a dopant cation from the Ce.sup.3+ or Pr.sup.3+ group and substituent .sup.2M represents a first codopant cation from the lanthanoids group, 3d transition metals, 4d transition metals, 5d transition metals group or 5s.sup.2 or 6s.sup.2 ions.

9. A material according to claim 8 wherein the substituent .sup.2M represents the first co-dopant from the Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm lanthanoid group or from the Ti, V, Cr, Mn, Fe, Co, Ni, Cu 3d transition metals or from the Zr, Nb, Mo, Ru, Rh, Ag 4d transition metals or from the Ta, W 5d transition metals or from the 5s.sup.2 In, Sn, Sb ion group or from the 6s.sup.2 Tl, Pb, Bi ion group.

10. A scintillator material based on silicate with a general chemical formula A.sub.2SiO.sub.5 with shortened scintillation response by method of claim 1 wherein it corresponds to a general chemical formula A.sub.2x1x2.sup.1M.sub.x1.sup.2M.sub.x2SiO.sub.5 where substituent A is represented by a cation from the Y.sup.3+, Lu.sup.3+, Gd.sup.3+ group or their mixture, substituent .sup.1M represents the a dopant cation from the Ce.sup.3+ or Pr.sup.3+ group and substituent .sup.2M represents a first codopant cation from the lanthanoids group, 3d transition metals, 4d transition metals, 5d transition metals group or 5s.sup.2 or 6s.sup.2 ions.

11. A material according to claim 10 wherein the substituent .sup.2M represents the first co-dopant from the Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm lanthanoid group or from the Ti, V, Cr, Mn, Fe, Co, Ni, Cu 3d transition metals or from the Zr, Nb, Mo, Ru, Rh, Ag 4d transition metals or from the Ta, W 5d transition metals or from the 5s.sup.2 In, Sn, Sb ion group or from the 6s.sup.2Tl, Pb, Bi ion group.

12. A material according to claim 10 wherein the substituent .sup.2M represents a mixture of the first co-dopant and the second co-dopant where the second codopant is from the group of optically inactive ions.

13. A material according to claim 12.sup.a wherein the substituent .sup.2M represents a mixture of the first co-dopant and the second co-dopant where the second co-dopant is a Mg.sup.2+ or Ca.sup.2+ cation.

Description

DESCRIPTION OF THE DRAWINGS

[0031] The invention shall be clarified more closely in the following drawings, where:

[0032] FIG. 1 illustrates a graph with the A curve of the Ce.sup.3+ luminescence centre time response in the LuAG:Ce scintillator and with the B curve of scintillation response of the LuAG:Ce,

[0033] FIG. 2 illustrates a graph of absorption spectrum with marked maximum and half width of absorption band of the respective Ce.sup.3+ centre in the LuAG:Ce scintillator,

[0034] FIG. 3 illustrates a graph of luminescence spectrum with marked maximum and half width of emission band of the Ce.sup.3+ centre in the LuAG:Ce scintillator,

[0035] FIG. 4 illustrates scintillation spectrum of the YAG:Ce single crystal (C curve) with marked half width of emission band and absorption spectrum of the YAG:Nd single crystal (D curve),

[0036] FIG. 5 illustrates scintillation response of crystals and YAG:Ce (E curve) and YAG:Ce, Nd (F curve),

[0037] FIG. 6 illustrates scintillation response of crystals YAG:Ce (G curve) and YAG:Ce, Ho (H curve),

[0038] FIG. 7 illustrates scintillation spectrum of the YAP:Pr crystal with marked half width of emission band,

[0039] FIG. 8 illustrates scintillation response of crystals YAP:Pr (I curve) and YAP:Pr, Gd (J curve and K curve),

[0040] FIG. 9 illustrates scintillation response of crystals YAP:Pr (identical with I curve in FIG. 8) and YAP:Pr, Tb (M curve and L curve),

[0041] FIG. 10 illustrates scintillation spectrum of crystal LGSO:Ce with marked half width of emission band,

[0042] FIG. 11 illustrates scintillation response of crystals LGSO:Ce (N curve) and LGSO:Ce Dy (O curve),

[0043] FIG. 12 illustrates thermal dependence of photoluminescence decay time of centres depicted by the P curve and Q curve in the YSO:Ce crystal,

[0044] FIG. 13 illustrates scintillation response of crystals YSO:Ce for temperatures of 295 K (R curve) and 450 K (S curve),

[0045] FIG. 14 illustrates scintillation response of crystals LuAG:Ce (T curve), YAG:Ce, Nd (U curve) and LuAG:Ce, Nd, Mg (V curve),

[0046] FIG. 15 illustrates scintillation spectrum of single crystal GGAG:Ce (W curve) with marked half width of emission band and absorption spectrum of the GGAG:Nd single crystal (X curve),

[0047] FIG. 16 illustrates scintillation response of crystals GGAG:Ce (Y curve) and GGAG:Ce, Nd (Z curve).

Examples of the Preferred Embodiments of the Invention

[0048] It is understood that the below stated and depicted specific examples of the invention execution are represented for illustration and not as the limitation of the invention to the stated examples. Experts knowledgeable of the state of technology will find or will be able to ensure, when performing routine experimentation, larger or smaller amount of equivalents to the specific executions of the invention which are described here. These equivalents shall be also included in the extent of the following patent claims.

[0049] Active scintillators may be prepared in the form of powder, such as via simple sintering, of an active layer, such as via epitaxial growth or plasma deposition, or of a volume single crystal, such as with the Czochralski,, EFG, microPD, Kyropoulos and other methods.

[0050] The scintillation response mechanism with known materials is schematically illustrated in FIGS. 1-3 with the example of the LuAG:Ce garnet material. Ce.sup.3+ is used as a dopant here. In FIG. 1, the A curve represents the response of the Ce.sup.3+ centre which is excited directly with photons of the 450 nm wavelength, the B curve represents the scintillation response of the Ce.sup.3+ centre which is excited with ionizing radiation, i.e. gamma photons with the 511 keV energy. In the scintillation response, there is marked the amplitude-dominant fast component 1, which is determined by the emission centre lifetime and where the A and B curves are practically identical, and the following amplitude-minor slow component 2 of the scintillation response arising as a result of the migration of charge carriers to the Ce.sup.3+ centres.

[0051] FIG. 2 illustrates a graph of absorption spectrum of the same material, i.e. LuAG:Ce, with marked maximum 3 of the absorption band and width in the half of absorption band maximum related to the Ce.sup.3+ centre in the LuAG;Ce scintillator. This width is designated as half width FWHM. The graph depicts the dependence of absorbance on the wavelength with marked absorption transition of Ce.sup.3+ between the 4f and 5d.sup.1 levels.

[0052] FIG. 3 illustrates a graph of luminescence spectrum with marked maximum 3 of the emission band and half width of emission band (FWHM) related to the Ce.sup.3+ centre in the LuAG:Ce scintillator, depicting the dependence of normalised intensity on the wavelength.

[0053] FIG. 1 clearly shows that the scintillation response of known scintillators is long also due to the long duration time of the amplitude-dominant component of the scintillation response. This time is significantly shortened in materials according to the following examples of invention execution:

Example 1Preparation of Sample of YAG:Ce, YAG:Nd a YAG:Ce Single Crystal Co-Doped with Nd (YAG:Ce, Nd)

[0054] Mixtures were prepared of Y.sub.2O.sub.3 and Al.sub.2O.sub.3 binary oxides with the Y.sub.3Al.sub.5O.sub.12 composition, CeO.sub.2 and Al.sub.2O.sub.3 with the Ce.sub.3Al.sub.5O.sub.12 composition, Nd.sub.2O.sub.3 and Al.sub.2O.sub.3 of the Nd.sub.3Al.sub.5O.sub.12 composition when the used materials were of the 5N purity. Mechanical mixing was followed with homogenisation via shaking and isostatic pressing into a block. The blocks were sintered at 1400 C. for the period of 24 hours in the air and subsequently were partially crushed and inserted into a molybdenum crucible. The YAG:Ce, YAG:Nd and YAG:Ce, Nd single crystals were grown from the mixture via the Czochralski method under a protective hydrogen/argon atmosphere. The composing of melt for growing was selected in such a manner that the resulting crystals are of the Y.sub.2.96Nd.sub.0.04Al.sub.5O.sub.12, Y.sub.2.91Nd.sub.0.04Ce.sub.0.05Al.sub.5O.sub.12 a Y.sub.2.95Ce.sub.0.05Al.sub.5O.sub.12 composition to compare their characteristics.

[0055] Small discs were cut from the prepared single crystals of 1 mm thickness and 10 mm diameter which were optically polished for the subsequent measurement of the spectra and scintillation responses.

[0056] FIG. 4 illustrates with the C and D curves the overlap of the emission band of the Ce.sup.3+ centre of the YAG:Ce crystal with marked maximum 3 at 525 nm and absorption transitions of the centre Nd.sup.3+ .sup.4I.sub.9/2.fwdarw..sup.4G.sub.5/2, .sup.4G.sub.7/2 (W. T. Carnall et al, J. Chem. Phys. 90, no. 7, 3443, 1989) in the spectrum range of 500-595 nm which corresponds to FWHM of the Ce.sup.3+ centre emission, utilizing X-ray radiation with the voltage on the X-ray tube of 40 kV. This overlap causes a non-radiative energy transfer from the Ce.sup.3+ centre to the Nd.sup.3+ centre which results in the acceleration of the amplitude-dominant component 1 in the scintillator response that is depicted in FIG. 5, where the E curve illustrates the scintillation response of the common YAG:Ce material and the F curve illustrates the scintillation response of the YAG:Ce material co-doped with Nd as the first co-dopant. Both the materials were exposed to gamma radiation with the photon energy 511 keV from the radioisotope .sup.22Na. For the purposes of quantitative assessment of the scintillation response shortening, the 1/e life time, denoted in FIG. 5, is standardly introduced. The life time is the time of duration from which the signal drops from the maximum amplitude 1 to 1/e, where e is the base of the natural logarithm, e=2.718. The life time of the YAG:Ce, Nd F crystal is shortened to 12 ns in comparison with 61 ns of the YAG:Ce material E, that is more than four times.

Example 2Preparation of Sample of YAG:Ce Single Crystal Co-Doped with Ho (YAG:Ce, Ho)

[0057] In the total amount of 5 g, the Y.sub.2O.sub.3, Al.sub.2O.sub.3, CeO.sub.2 and Ho.sub.2O.sub.3 binary oxides of the 5N purity were mixed in the ratio of the chemical Y.sub.2.91Ho.sub.0.04Ce.sub.0.05Al.sub.5O.sub.12 formula. After mechanical mixing and grinding in the grinding mortar there followed a two-stage sintering: in the first stage at 1300 C. for the period of 24 hours, in the second stage at 1400 C. for the period of 24 hours, in the air. The material was again mechanically ground in the grinding mortar between the individual steps. The powder was inserted into a molybdenum crucible and in the protective atmosphere of 70% argon/30% hydrogen a single crystal was drawn in the shape of a rod with the EFG method through a molybdenum die. The Y.sub.2.96Nd.sub.0.04Al.sub.5O.sub.12 and Y.sub.2.95Ce.sub.0.05Al.sub.5O.sub.12 single crystals were prepared in the same manner to compare their characteristics. Small discs of 1 mm thickness were cut from the prepared single crystal rods of 4 mm diameter which were optically polished for the subsequent measuring of spectra and scintillation responses.

[0058] The overlap of the emission band of the Ce.sup.3+ centre with maximum at 525 nm and absorption transition of the centre Ho.sup.3+ .sup.5I.sub.8.fwdarw..sup.5S.sub.2, .sup.5F.sub.4 centre with the maximum at 530-540 nm (W. T. Carnall et al, J. Chem. Phys. 90, no. 7, 3443, 1989) in the spectrum range of 500-595 nm which corresponds to FWHM of the Ce3+ centre emission, causes the acceleration of the amplitude-dominant component of the scintillator response which is depicted in FIG. 6, where the G curve illustrates the scintillation response of the common YAG:Ce material and the H curve illustrates the scintillation response of the YAG:Ce material co-doped with Ho as the first co-dopant. Both the materials were exposed to gamma radiation of the photon energy 511 keV from the radioisotope .sup.22Na. FIG. 6 depicts the life time of the YAG:Ce crystal with the G curve and YAG:Ce, Ho with the H curve which is shortened to 25.2 ns in comparison with 61 ns of the YAG:Ce material, that is more than twice.

Example 3Preparation of Sample of YAP:Pr Single Crystal and YAP:Pr Single Crystal Co-Doped with Gd (YAP:Pr, Gd)

[0059] The YAP:Pr and YAP:Pr, Gd single crystals were prepared and grown analogously according to Example 2 when the Y.sub.2O.sub.3, Al.sub.2O.sub.3, Gd.sub.2O.sub.3 and Pr.sub.6O.sub.11 binary oxides of the 5N purity were mixed in the ratio of the Y.sub.0.995Pr.sub.0.005AlO.sub.3, Y.sub.0.985Gd.sub.0.01Pr.sub.0.005AlO.sub.3 and Y.sub.0.945Gd.sub.0.05Pr.sub.0.005AlO.sub.3 chemical formulas. The spectra and scintillation responses were measured analogously as in Example 2.

[0060] FIG. 7 illustrates the emission band of the Pr.sup.3+ centre with marked maximum 3 at 247 nm and full width at half maximum (FWHM) related to the Pr.sup.3+ centre in the YAP:Pr scintillator.

[0061] The overlap of the emission band of the Pr.sup.3+ centre with absorption transition of the centre Gd.sup.3+ .sup.8S.sub.7/2.fwdarw..sup.6I.sub.x at 270-275 nm (W. T. Carnall et al, J. Chem. Phys. 90, no. 7, 3443, 1989) in the spectrum range of 235-285 nm which corresponds to FWHM of the Pr.sup.3+ centre emission, causes a non-radiative energy transfer from the Pr.sup.3+ centre to the Gd.sup.y+ centre which results in the acceleration of the amplitude-dominant component 1 in the scintillator response which is depicted in FIG. 8. The YAP:Pr and YAP:Pr, Gd single crystals were exposed to gamma radiation of the photon energy 511 keV from the radioisotope .sup.22Na. The life time of the amplitude-dominant component of the YAP:Pr, Gd single crystal is shortened in comparison with 16 ns of the YAP:Pr material, depicted with the I curve, to 11 ns for the YAP:Pr material co-doped with Gd (1% wt.) depicted with the J curve, and to 7 ns for the YAP:Pr material co-doped with Gd (5% wt.) depicted with the K curve. The life times were calculated from the convolution of the instrumental response (stated in FIG. 8) with a double exponential function.

Example 4Preparation of Sample of YAP:Pr Single Crystal and YAP:Pr Single Crystal Co-Doped with Tb (YAP:Pr, Tb)

[0062] The YAP:Pr and YAP:Pr co-doped with Tb single crystals were prepared and grown analogously according to Example 1. A mixture of Y.sub.2O.sub.3 and Al.sub.2O.sub.3 binary oxides was prepared with the ratio 1:1. Mechanical mixing was followed with homogenisation shaking and isostatic pressing into a block. The blocks were sintered at 1400 C. for the period of 24 hours in the air and subsequently were partially crushed and inserted into a tungsten crucible. To complete stoichiometry, the Al.sub.2O.sub.3, Tb.sub.4O.sub.7 and Pr.sub.6O.sub.11 oxides were used with materials of the 4N purity. Single crystal with Y.sub.0.995Pr.sub.0.005AlO.sub.3, Y.sub.0.985Tb.sub.0.01Pr.sub.0.005AlO.sub.3 and Y.sub.0.945Tb.sub.0.05Pr.sub.0.005AlO.sub.3 chemical formulas were prepared from the stated materials. The spectra and scintillation responses were measured analogously as in Example 1.

[0063] The overlap of the emission band of the Pr.sup.3+ centre with maximum at 247 nm and the lowest absorption band transition 4f-5d of the Tb.sup.3+ centre in range of 250-280 nm (K. S. Sohn et al, J. Electrochem. Soc., 147 (9) 3552, 2000) in the spectrum range of 235-285 nm which corresponds to FWHM of the Pr.sup.3+ centre emission, causes a non-radiative energy transfer from the Pr.sup.3+ centre to the Tb.sup.3+ centre which results in the acceleration of the amplitude-dominant component 1 in the scintillator response. It is depicted in FIG. 9. The YAP:Pr and YAP:Pr, Tb single crystals were exposed to gamma radiation of the photon energy 511 keV from the radioisotope .sup.22Na. The life time of the amplitude-dominant component of the YAP:Pr, Tb single crystal is shortened in comparison with 16 ns of the YAP:Pr material, depicted with the I curve from Example 3, to 11 ns for the YAP:Pr material co-doped with Td (1% wt.) depicted with the L curve, and to less than 1 ns for the YAP:Pr material co-doped with Tb (5% wt.) depicted with the M curve. The life times were calculated from the convolution of the instrumental response (shown in FIG. 9) with a double exponential function.

Example 5Preparation of Sample of LGSO:Ce Single Crystal and LGSO:Ce Single Crystal Co-Doped with Dy (LGSO:Ce, Dy)

[0064] The LGSO:Ce and LGSO:Ce co-doped with Dy single crystals were prepared and grown with the Czochralski method from iridium crucible under the protective atmosphere of nitrogen with traces of oxygen. The starting materials for growing the single crystal analogously according to Example 1 were the Lu.sub.2O.sub.3 and SiO.sub.2, Gd.sub.2O.sub.3 and SiO.sub.2, CeO.sub.4 and SiO.sub.2 and Dy.sub.2O.sub.3 and SiO.sub.2 binary oxides mixtures with the purity of 5N. The result of growth were the single crystals of the (Lu.sub.0.59Gd.sub.0.40Ce.sub.0.01).sub.2SiO.sub.5, and (Lu.sub.0.57Gd.sub.0.40Ce.sub.0.01Dy.sub.0.02).sub.2SiO.sub.5 chemical formulas. The spectra and scintillation responses were measured analogously as in Example 1.

[0065] The overlap of the emission band of the Ce.sup.3+ centre with marked maximum 3 at 425 nm and FWHM 400-465 nm and absorption transitions 4f-4f from the basic state of .sup.6H.sub.15/2 to higher 4f states .sup.4I.sub.15/2 and .sup.4G.sub.11/2 and .sup.4M.sub.21/2 of the Dy.sup.3+ centre in the range of 400-455 nm (W. T. Carnall et al, J. Chem. Phys. 90, no. 7, 3443, 1989), which is depicted in FIG. 10, causes a non-radiative energy transfer from the Ce.sup.3+ centre to the Dy.sup.3+ centre which results in the acceleration of the amplitude-dominant component 1 of the scintillator response. It is depicted in FIG. 11, where the N curve illustrates the scintillation response of the common LGSO:Ce material and the O curve illustrates the scintillation response of the LGSO:Ce material co-doped with Dy as the first co-dopant. Both the materials were exposed to gamma radiation of the photon energy 511 keV from the radioisotope .sup.22Na. The life time of the amplitude-dominant component of the LGSO:Ce crystal, co-doped with Dy, 2% wt. O is shortened when compared with 27.8 ns of the material LGSO:Ce N to 6.1 ns, that is more than four times.

Example 6Preparation of Sample of YSO:Ce Single Crystal

[0066] The YSO:Ce single crystal was prepared and grown analogously according to Example 4. The Y.sub.2O.sub.3, SiO2 and CeO.sub.4 binary oxides of 5N purity were mixed which resulted in a single crystal of the (Y.sub.0.99Ce.sub.0.01).sub.2SiO.sub.5 chemical formula. The spectra and scintillation responses were measured analogously as in Example 1.

[0067] A sufficient increase in temperature leads practically with every luminescence centre to the appearance of non-radiative thermal quenching of luminescence which can be utilized, too, for the shortening of the period of duration of the dominant component 1 in the scintillation response. In case of the emission band of both the Ce.sup.3+ centres, marked here as the P curve and the Q curve, in the host YSO crystal, the thermal quenching of both the P and Q centres occurs at approximately 350 K, as shown in FIG. 12. Around 90% of all cerium emission centres have maxima of emission at 400 nm, these emission centres are represented with the Q curve, the P curve represents minor cerium emission centres with the emission maximum at 490 nm. FIG. 13 illustrates how the dominant component 1 in the scintillation response at 450 K is shortened approximately three times when compared to the room temperature, when YSO:Ce crystals were excited by gamma radiation of the photon energy 511 keV from the radioisotope .sup.22Na. For the purposes of quantitative assessment of the scintillation response shortening, the 1/e life time is introduced as well as in all the previous examples, which is 39.3 ns at room temperature (295 K) and 13.4 ns at 450 K, as is illustrated with the R curve (295 K) and Q curve (450 K) in FIG. 13.

[0068] It is clear from Examples 1 to 6 that the utilization of the first co-dopant results in a significant acceleration in the time of duration of amplitude-dominant component of the scintillation response. The scintillation response consists also of slower components where it is possible to decrease intensity. This simultaneous action occurs with materials according to the following example of invention execution:

Example 7Preparation of Sample of Single Crystals LuAG:Ce and LuAG:Ce Co-Doped with Nd and LuAG:Ce Doubly Co-Doped with Nd and Mg (LuAG:Ce, Nd and LuAG:Ce, Nd, Mg)

[0069] The LuAG:Ce and LuAG:Ce co-doped with Nd and LuAG:Ce doubly do-doped with Nd and Mg single crystals were prepared and grown analogously according to Example 2 when the Lu.sub.2O.sub.3, Al.sub.2O.sub.3, CeO.sub.2, Nd.sub.2O.sub.3 and MgO binary oxides of 5N purity were mixed in the ratio of the Lu.sub.2.91Nd.sub.0.02Ce.sub.0.05Mg.sub.0.02Al.sub.5O.sub.12 and Lu.sub.2.93Nd.sub.0.02Ce.sub.0.05Al.sub.5O.sub.12 and Lu.sub.2.95Ce.sub.0.05Al.sub.5O.sub.12 chemical formulas. The spectra and scintillation responses were measured analogously as in Example 2.

[0070] The overlap of the emission band of the Ce.sup.3+ centre with maximum at 525 nm and absorption band transitions of the centre Nd.sup.3+ .sup.4I.sub.9/2.fwdarw..sup.4G.sub.5/2,.sup.4G.sub.7/2 Nd3+4I9/24G5/2,4G7/2 (W. T. Carnall et al, J. Chem. Phys. 90, no. 7, 3443, 1989) in the spectrum range of 500-595 nm which corresponds to FWHM of the Ce.sup.3+ centre emission, causes a non-radiative energy transfer from the Ce.sup.3+ centre to the Nd.sup.3+ centre which results in the acceleration of the amplitude-dominant component 1 in the scintillation response which is depicted in FIG. 14. The life time of the amplitude-dominant component of the LuAG:Ce, Nd single crystal is shortened in comparison with 66 ns of the LuAG;Ce material T to 43 ns U. Compared to the YAG:Ce crystal, the scintillation response contains significantly more intensive slow components 2, as can be seen when comparing FIG. 3 and FIG. 12. Their partial suppression may be achieved via the co-doping with the optically inactive double-valent ion (M. Nikl et al, Crystal Growth Design 14, 4827, 2014). The simultaneous application of this co-dopant results in a partial suppression in LuAG:Ce, Nd, Mg of the slow component 2 in the scintillation response in the material with accelerated dominant component 1 of the scintillation response, as illustrated in FIG. 14 where the T curve represents the scintillation response of the LuAG:Ce single crystal, the U curve demonstrates the shortening of the scintillation response of the amplitude-dominant component of the LuAG:Ce, Nd single crystal and the V curve demonstrates the shortening of the scintillation response of both the amplitude-dominant and the amplitude-minor components of the LuAG:Ce, Nd, Mg single crystal.

[0071] In other example of execution, the first co-dopant can be from the 3d transition metals groupTi, V, Cr, Mn, Fe, Co, Ni, Cu, 4d transition metals groupZr, Nb, Mo, Ru, Rh, Ag, 5d transition metals groupTa, W, 5s.sup.2 ionsIn, Sn, Sb, or from the 6s.sup.2 ions groupTl, Pb, Bi. In another example of execution the Ca.sup.2+ cation can be used as the second co-dopant.

Example 8Preparation of Sample of Single Crystals Gd.SUB.3.Ga.SUB.3.Al.SUB.2.O.SUB.12.:Ce (GGAG:Ce), GGAG:Nd and GGAG:Ce Co-Doped with Nd (GGAG:Ce, Nd)

[0072] The Gd.sub.3Ga.sub.3Al.sub.2O.sub.12:Ce (GGAG:Ce) single crystal was prepared and grown analogously according to Example 1 when the Gd.sub.2O.sub.3, Ga.sub.2O.sub.3, Al.sub.2O.sub.3, CeO.sub.2 and Nd.sub.2O.sub.3 binary oxides of 5N purity were mixed. The GGAG:Ce single crystal was grown from the mixture via the Czochralski method under a protective hydrogen/argon atmosphere, the composition of melt for the growth was selected in such a manner that the resulting crystal was composed in the ratio of the Gd.sub.2.955Nd.sub.0.03Ce.sub.0.015Ga.sub.3Al.sub.2O.sub.12 chemical formula. Analogously as in Example 1, the spectra and scintillation responses were subsequently measured. The Gd.sub.2.97Nd.sub.0.03Ga.sub.3Al.sub.2O.sub.12 and Gd.sub.2.985Ce.sub.0.15Ga.sub.3Al.sub.2O.sub.12 single crystals were prepared in the same manner to compare their characteristics.

[0073] FIG. 15 illustrates with the W and X curves the overlap of the emission band of the Ce.sup.3+ centre of the GGAG:Ce single crystal with marked maximum 3 at 535 nm and absorption transitions of the centre Nd.sup.3+ .sup.4I.sub.9/2.fwdarw..sup.4G.sub.5/2,.sup.4G.sub.7/2 (W. T. Carnall et al, J. Chem. Phys. 90, no. 7, 3443, 1989) in the spectrum range of 500-612 nm which corresponds to FWHM of the Ce.sup.3+ centre emission, causes a non-radiative energy transfer from the Ce.sup.3+ centre to the Nd.sup.3+ centre which results in the acceleration of the amplitude-dominant component 1 in the scintillation response which is depicted in FIG. 16, where the Y curve illustrates the scintillation response of the GGAG:Ce common material and the Z curve illustrates the scintillation response of the GGAG:Ce material co-doped with Nd as the first co-dopant. Both the materials were excited by gamma radiation of the photon energy 511 keV from the radioisotope .sup.22Na. FIG. 16 illustrates with the Y curve the life time of the GGAG:Ce crystal and with the Z curve the life time of the GGAG:Ce, Nd crystal which is shortened to 54 ns in comparison with 91 ns of the GGAG:Ce material.

Example 9Fast Scintillation Detector of Secondary Electrons

[0074] A double-sided polished scintillation disk with the diameter of 10 mm and thickness of 1 mm was manufactured from the Y.sub.0.985Tb.sub.0.01Pr.sub.0.005AlO.sub.3 crystal, grown in Example 4. On surface it was provided with aluminium coating of the thickness of 50 nm. The disc was glued in the face of the all-sides polished cylinder from quartz glass. Positive potential +10 kV is lead to the aluminium coating. The positive potential attracts electrons to the scintillation disk and inside it, fast light flashes are created. The quartz cylinder leads light pulses from the scintillation disc to the fast optical detector. The assembly of the scintillation disc and quartz cylinder is placed in the electronic scanning microscope chamber and enables to detect the signal of secondary electrons with a time response of 5 ns/pxl.

Example 10Fast Scintillation Detector of Secondary Electrons

[0075] A plate with the diameter of 15 mm and thickness of 2 mm in epitaxial quality was polished from the undoped YAG single crystal. 20 thick layer of Gd.sub.2.955Nd.sub.0.03Ce.sub.0.015Ga.sub.3Al.sub.2O.sub.12 was applied onto the surface of the plate via the LPE (Liquid Phase Epitaxy) method. The scintillation disc was worked and except for one head surface, the epitaxial layer was polished off. A thin conductive ITO coating was coated onto the surface with the LPE layer. The disc was glued in the face of the all-sides polished cylinder from quartz glass. Positive potential +10 kV is lead to the aluminium coating. The positive potential attracts electrons to the scintillation disk and inside it, fast light flashes are created. The quartz cylinder leads light pulses from the scintillation disc to the fast optical detector. The assembly of the scintillation disc and quartz cylinder is placed in the electronic scanning microscope chamber and enables to detect the signal of secondary electrons. When compared to the same detector which contains a polished YAG:Ce disc, this detector has a higher light yield and operates with a shorter time response.

Example 11Single Crystal Detector for PET Applications

[0076] The LYSO:Ce co-doped with Dy and GGAG:Ce co-doped with Nd single crystals were grown via the Czochralski method. Elements of 2210 mm, polished from all sides, were prepared from each single crystal. From these elements the modules (matrix) were composed with the size of 88 elements (pixels) which were optically separated from each other. Both the matrices were connected together optically with the accuracy of minimally 0.1 mm, pixel to pixel. The whole element was inserted in a plastic casing and the crystal was optically connected with 64-pixel APD. The whole module was used in a positron scanner for tumour imaging in small animals, with a high special resolution and speed.

Example 12Fast Detector for High Energy Particles Detection

[0077] A LuAG:Ce, Nd, Mg single crystal was grown via the Czochralski method according to Example 7 with a higher concentration of Nd in such a manner that the response of the single crystal on the cerium centre was 20 ns. Fibres of the size 11140 mm were prepared from the single crystal and all the surfaces were polished. A pixel detector was assembled from the fibres so that the fibres were interlaid with a tungsten sheet of 1 mm thickness. The detector contained 88 fibres. The detector was constructed in such a manner that there were no optical leaks among the individual fibres. The pixels were insulated from each other with tungsten. The detector was connected at its end with a 64-pixel APD. The detector was used as an electromagnetic calorimeter to detect high energy particles originating in a proton-proton collider with the timing of 25 ns. Due to its short response this solution significantly increased the efficiency of particles detection.

INDUSTRIAL APPLICABILITY

[0078] Scintillators with a shortened time of response according to the invention will be utilized in medical applications, working with ionizing radiation, such as positron emission tomography (PET) or CT, in scientific applications, such as in various calorimetric detectors, and in industry, particularly in detectors for the quality control of internal structures of mass produced products, such as chips, or e.g. during border controls.