CN102344808A - Scintillator, relative detection device and method thereof - Google Patents

Abstract

The invention relates to a scintillator, represented as (GdxLuyM1-x-y)2Si2O7, wherein, M represents Ce, Pr or a combination of Ce and Pr, x is larger than 0.32 and less than 1, y is no less than 0 and no larger than 0.63, the value of 1-x-y is larger than 0 and less than 0.05, and when y is 0, M represents the combination of Ce and Pr. The invention also relates to a detection device containing the scintillator. The invention further relates to a method for detecting energy with the detection device, comprising the following steps that: the scintillator receives radiation energy, and a photon detector connected with the scintillator is used for detecting the photon emitted by the scintillator.

Description

Scintillator, related detection device and method

Technical field

The relevant a kind of scintillator of the present invention, comprise the proofing unit of said scintillator and with the method for said proofing unit detected energy.

Background technology

Monocrystalline flicker is that a kind of very simply but very sensitive detects such as x ray, gamma ray and carries the method above the energy-rich radiation the high energy particle of kiloelectron volt (KeV).

Relatively Chang Yong scintillator material comprises thallium activated sodium iodide (NaI (Tl)), bismuth germanium oxide (BGO), mixes the positive gadolinium siliate of cerium (GSO), mixes the positive silicic acid lutetium of cerium (LSO) and mixes the positive silicic acid lutetium of cerium yttrium (LYSO).

Pyrosilicate like disilicic acid lutetium and so on once disclosed in one piece of article of people such as P.Szupryczynski; " mix cerium disilicic acid lutetium scintillator LPS and LYPS "; 2005 IEEE Nuclear ScienceSymposium Conference Record, the 1310th page to the 1313rd page.

No. the 6437336th, United States Patent (USP) and disclose for No. 6818896 and a kind ofly have disilicic acid lutetium structure and consist of LU _{2 (1-x)}M _2xSi ₂O ₇The monocline monocrystalline, wherein LU is from lutetium or contain Sc, Y, In, La chooses in one or more the lutetium-base alloy among the Gd, M is a cerium or by the substituted cerium of one or more non-lutetium element parts in the lanthanon family.

U.S. Patent application discloses No. 2010/0127176 and discloses a kind of scintillator composition, and it comprises cerium, praseodymium and the gadolinium of silicic acid lutetium or phosphoric acid lutetium matrix and some amount.

Mix cerium disilicic acid gadolinium (Gd ₂Si ₂O ₇: Ce) monocrystalline discloses in " mixing the float-zone method growth and the blinking characteristic of cerium disilicic acid gadolinium monocrystalline " literary composition of people such as Kawamura; This article is published in 2006 IEEE NuclearScience Symposium Conference Record, the 1160th page to the 1163rd page.But, do not have up to now, if to have also be seldom, about at Gd ₂Si ₂O ₇(GPS) add cerium unit in addition in and usually process the report of scintillator material, maybe be partly because Gd ₂Si ₂O ₇(GPS) growth of crystal itself is just difficult.

Although existing scintillator material has some ideal blinking characteristics really, thereby make their suitable some application, every kind of material all has one or more defectives that they use expansion that limit.

For example, high like the imaging of medical requirement crystal light output of Positron Emission Computed Tomography (PET) and so on, energy resolution is low, and fall time is short.But the scintillator material that can buy seldom can satisfy whole requirements of PET at present.In addition, industrial community also hopes to have more scintillator material to be developed to increase the elasticity that material is selected.

Therefore, a kind of new scintillator, relevant proofing unit and method need be provided.

Summary of the invention

The purpose of this invention is to provide a kind of new scintillator, relevant proofing unit and method.

The scintillator that the present invention relates to, it consists of (Gd _xLu _yM _1-x-y) ₂Si ₂O ₇, wherein M is Ce, Pr or its combination; 0.32＜x＜1 wherein; 0＜=y＜=0.63; 0＜1-x-y＜0.05; Wherein during y=0, M is the combination of Ce and Pr.

The present invention also relates to comprise the proofing unit of aforementioned scintillator.

The invention still further relates to the method for application of aforementioned proofing unit detected energy, it comprises: by scintillator received radiation energy, and use the photon detector that is connected with scintillator to detect the photon of scintillator emission.

Embodiment

In subsequent descriptions, known function or structure will not detail, to avoid making description unclear because of unnecessary details.

Mentioned numerical value comprises all numerical value of the unit increase in a unit from low to high among the present invention, supposes any than at least two unit, interval between low value and the high value here.For instance, if quantity or the value of a processing parameter of a component, such as, temperature, pressure; Time or the like is from 1 to 90,20 to 80 preferable, 30 to 70 the bests; Be to want to express all clear being set forth in this specification sheets such as 15 to 85,22 to 68,43 to 51,30 to 32 numerical value such as grade.For less than 1 numerical value, 0.0001,0.001,0.01 or 0.1 is considered to a more suitable unit.The aforementioned special example that will express of just hoping, all clearly are listed as in this manual minimum all being regarded as in a similar manner to the combinations of values between the maximum of enumerating.

Approximate term in specification sheets and the claim is used for modifying quantity, and expression the present invention is not limited to this concrete quantity, also comprises the part with the approaching acceptable correction of this quantity, and can not cause the change of relevant basic function.Accordingly, modify a numerical value, mean and the invention is not restricted to this accurate numerical value with " approximately ", " pact " etc.In some example, approximate term maybe be corresponding to the precision of the instrument of measuring numerical value.

On the one hand, the present invention relates to scintillator, it consists of (Gd _xLu _yM _1-x-y) ₂Si ₂O ₇, wherein M is Ce, Pr or its combination.0.32＜x＜1 wherein; 0＜=y＜=0.63; 0＜1-x-y＜0.05; Wherein during y=0, M is the combination of Ce and Pr.Except as otherwise noted, x and y are to be measure unit with the mole among the present invention.

In scintillator, lutetium and gadolinium are generally positive trivalent oxidation state and can be from various materials, like fluorochemical, muriate or bromide.In certain embodiments, 0＜y＜0.62 or 0＜y＜0.22.Among some embodiment, the weight ratio of lutetium and gadolinium was less than about 25: 75 or about 60: 40 or about 65: 35.Among some embodiment, scintillator comprises disilicic acid gadolinium crystalline phase.Technician like the present technique field understands, and in this case, we can say that also scintillator comprises disilicic acid gadolinium structure or matrix.Among some embodiment, scintillator comprises disilicic acid gadolinium crystalline phase and disilicic acid lutetium crystalline phase.In this case, disilicic acid gadolinium crystalline phase is main, like technician's understanding in present technique field, we can say that also scintillator comprises disilicic acid gadolinium structure/matrix and disilicic acid lutetium structure/matrix.

Understand like the technician in present technique field, M some the time also can be called as excimer or " hotchpotch ".Cerium and praseodymium are trivalent ion, i.e. Ce usually in scintillator ³⁺And Pr ³⁺In addition, they can be from different compounds, for example Cerium II Chloride or comprise cerium bromide.In some certain embodiments, scintillator consists of (Gd _0.98Ce _0.01Pr _0.01) ₂Si ₂O ₇, (Gd _0.9893Ce _0.0097Pr _0.001) ₂Si ₂O ₇, (Gd _0.7753Lu _0.2190Ce _0.00057) ₂Si ₂O ₇Perhaps (Gd _0.3800Lu _0.6181Ce _0.0019) ₂Si ₂O ₇

Scintillator can multi-form preparation and use.Among some embodiment, scintillator is a transparent crystals.They are specially adapted to as surveying the high-energy radiation proofing unit of gamma ray etc. and so on.But scintillator also can be other forms according to application need.Such as, it can be Powdered.Be understandable that, disclose, also can contain small amount of impurities in the scintillator like WO01/60944A2 and WO 01/60945A2.Impurity is derived from raw material usually and is lower than 0.1 weight % of scintillator gross weight, is lower than 0.01 weight % sometimes.Scintillator also can comprise parasitic additive, and its volume percent is usually less than about 1%.In addition, people also possibly painstakingly add other materials of trace in scintillator.

Can in all sorts of ways and prepare scintillator.Generally, at first preparation comprises the powder of correct proportions raw material, then calcining, die forging, sintering and/or hot isostatic pressing.Powder can make by mixing various reactants (like, the mixing of salt, halogenide, oxide compound or aforementioned substances).

As long as can guarantee thoroughly to mix uniformly, any available technology all can be used to mixed reactant.Such as, can be at the agate mortar sledge mill.Also available in addition stirrer or shredding unit are like ball mill, bowl grinding machine, hammer mill or jet-propelled pulverizing mill.As as known to those of skill in the art would, should note not introducing air or moisture in the mixing process usually.Also can contain various additives in the mixture, like diluted compounds and tackiness agent.When abrasive dust, add various liquid to be used as medium sometimes according to compatibility and/or solvability.Thereby medium should not pollute the reduction that scintillator causes its photoemissivity.

After the mixing, mixture can change into solid solution under the temperature and time that is fit to.Temperature and time depends in part on concrete raw material.During conversion, mixture places encloses container (like quartzy or silver pipe or crucible) to prevent loss of material usually.Generally, transform and in smelting furnace, carry out, temperature range is at about 1000 ℃ to about 1500 ℃.Transformation time is generally at about 15 minutes to about 10 hours.Transform and in the anaerobic dry environment, carry out usually, for example in the rare gas elementes such as vacuum or nitrogen, helium, neon, argon, krypton and xenon.Sometimes, conversion can be carried out under reducing environment.After transforming completion, product can be pulverized to process Powdered scintillator.The technician in present technique field can adopt existing method powder processing to be become the element of radiation detector.

The method for preparing monocrystalline is also for as known to those of skill in the art would.Nonrestrictive example discloses in people such as G.Blasse are published in " luminescent material " literary composition of Springer-Verlag (1994).Usually, the reactant of Shi Heing is fused into the congruent melting component under optimal temperature.Temperature of fusion depends on reactant itself, but generally all is higher than about 1500 ℃.

On the other hand, the present invention also relates to comprise the proofing unit of aforementioned scintillator.Proofing unit can comprise the scintillation detector with one or more aforementioned scintillator crystals.Scintillation detector is as known to those of skill in the art would, so will not detail at this.Many documents are mentioned this type of detector, and for example United States Patent (USP) the 6th, 585, No. 913, the 6th, 437, and No. 336 and the 6th, 624, No. 420.

The related proofing unit of the present invention detects x ray, gamma ray and carries the energy-rich radiation of high energy particle above kiloelectron volt (KeV) and so on.Generally speaking, produce corresponding photon after the radiation in the scintillator crystals received radiation source of proofing unit.Photon is detected by photodetector (photon detector), and said photon detector is connected with said scintillator light and produces an electrical signal according to the light pulse that scintillator sends.The machinery of photon detector and scintillator crystals, electronics mode of connection such as as known to those of skill in the art would.Photon detector can be any device as known to those of skill in the art would.Non-limiting example comprises photomultiplier, PIN type diode, photorectifier (like APD type diode), ccd sensor and image intensifier.The selection of concrete photodetector depends in part on the classification and the purposes of radiation detector (proofing unit).

The radiation detector that comprises scintillation detector and photodetector can be connected with device with various tool.Non-limiting example comprises logging tool and nuclear medical treatment device (like PET).Radiation detector also can be connected with digital imaging apparatus, like board device.In addition, scintillator also can be used as the assembly of screen flicker body.For example, scintillator powder can be shaped to put down to pull then and combine with blooming.Be derived from the high-energy radiation of some source of radiation,, and be converted into the optical photon on the blooming after scintillator contacts like the x ray.In addition, radiation detector also can be used for the security facility.Such as, they can be used for detecting whether radioactive material is arranged in the shipping goods.

Although many correlative details have been as known to those of skill in the art would, introduce some purposes here as an example.Aforementioned logging tool is represented an important use of radiation detector.The be operatively connected technology that radiation detector and well logging are managed is as known to those of skill in the art would.Its key concept is at United States Patent (USP) the 5th, 869, introduction arranged in No. 836.The end that the crystal that includes scintillator wraps in packing has an optical window.Pass twinkling light that the radiation of the optical window of crystal bag causes by light sensation device (photomultiplier) detection that is connected with the crystal bag.The light sensation device is converted into respective electronic device moulding, digitized electricimpulse with crystal visible light emitted.Through aforementioned process, can detect gamma ray, thereby the analysis around drilling well mouth rock ground condition is provided.What be worth to stress is that logging tool can have different types.

As previously mentioned, another important application of radiation detector is a medical imaging apparatus, like PET device.With the be operatively connected technology of radiation detector and PET device is as known to those of skill in the art would.Its key concept is at United States Patent (USP) the 6th, 624, introduction arranged in No. 422.In brief, in patient's body, inject radiopharmaceuticals, it is concentrated at the organ that needs detect.Radioactive nuleus decay in the medicine and emission positron.When positron runs into electronics, they are annihilated and are converted into photon or gamma ray.The PET scanner can three-dimensional localization is aforementioned be annihilated, thereby and again the shape of the organ that detects of construction so that observe.Detector module in the scanner contains a plurality of usually " detector block " and line related.Each detector block can contain the scintillator crystals and the photomultiplier of a series of particular arrangement.As logging tool, PET device also can be dissimilar.

In many application, like logging tool and PET device, the output of the light of scintillator is a very important characteristic.The related scintillator of the present invention can provide suitable light output.Under the certain situation, also other key properties can be provided simultaneously,, termination ability strong and acceptable energy resolution short like fall time.The related scintillator cost of the present invention is relatively low.They also can be used for other and need detect in the radiating device.

On the other hand, the invention still further relates to the method for application of aforementioned proofing unit detected energy, it comprises: by scintillator received radiation energy, and use the photon detector that is connected with scintillator to detect the photon of scintillator emission.

Example

Following experimental example can be implemented this invention for the people who has general technical ability in this area reference is provided.But these examples are not limited to the scope of claim.

Crystal growth

Starting material are the Gd more than 99.9% for the purity that obtains from Chinese Shanghai Chemical Reagent Co., Ltd., Sinopharm Group ₂O ₃, Lu ₂O ₃, CeO ₂, Pr ₆O ₁₁And SiO ₂

Stoichiometric composition according to shown in the table 1 weighs up raw material respectively, mixes, and the hydrostaticpressure at about 70Mpa is pressed into shaft respectively then.With shaft at following temperature sintering: be raised to 1500 degrees centigrade from room temperature in 3 hours, kept then 10 hours, in 4 hours, drop to room temperature again from 1500 degrees centigrade.

Table 1

The crystal title	Raw material is formed	The crystal title	Raw material is formed
				Crystal 1	(Gd 0.95Ce 0.05) 2Si 2O 7	Crystal 7	(Gd 0.99Ce 0.01) 2Si 2O 7
Crystal 2	(Gd 0.99Ce 0.01) 2Si 2O 7	Crystal 8	(Gd 0.99Ce 0.01) 2Si 2O 7
				Crystal 3	(Gd 0.99Ce 0.01) 2Si 2O 7	Crystal 9	(Gd 0.792Lu 0.2Ce 0.008) 2Si 2O 7
Crystal 4	(Gd 0.98Ce 0.01Pr 0.01) 2Si 2O 7	Crystal 10	(Gd 0.192Lu 0.8Ce 0.008) 2Si 2O 7
				Crystal 5	(Gd 0.989Ce 0.01Pr 0.001) 2Si 2O 7	Crystal 11	(Gd 0.492Lu 0.5Ce 0.008) 2Si 2O 7
Crystal 6	(Gd 0.992Ce 0.008) 2Si 2O 7	Crystal 12	(Lu 0.992Ce 0.008) 2Si 2O 7

The ceramic bar that burns till is put into an optics floating region stove (model 1000-H; Crystal Systems Inc. from the Salem city of Massachusetts, United States) so that adopts float-zone method to grow into crystal; Wherein the traction rate of each inversion axis be 2 millimeters per hour, speed of rotation is 30 to change per minutes.Two monocrystalline kinds are used to long crystal 7 and 8.

Except that crystal 7, other crystal all has serious slight crack.Crystal 7 has bigger transparent single crystal piece, but other crystal also can be chosen little transparent single crystal piece for analysis.After some crystal break, can observe the physics ruptured surface on < 100>direction.

Material characterizes

Crystalline structure is analyzed with X-ray diffractometer (XRD) (from the Bruker D8 Advance of the Bruker AxsGmbH of German Karlsruhe).The crystal sample of analyzing grinds to form thin powder.Some cleavage broken faces are directly analyzed to confirm the direction of breaking.

The X-ray diffraction result shows that crystal 1 to 9 is the GPS phase,, is the GPS structure that is.Crystal 10 and 12 be LPS mutually, that is, be the LPS structure.Be mainly the GPS phase in the crystal 11, but a small amount of LPS phase is arranged.

Crystal listed in the table 2 is formed with laser ablation sampling system (from the UP213 of California, USA Fremont city New Wave Research Inc.) and inductivity coupled plasma mass spectrometry analyser (LA-ICP-MS) (7500ce ICP-MS is from the AgilentTechnologies Inc. of California, USA Santa Clara).The crystal that analyzes is formed listed like table 2.The weight ratio of Gd/Lu also is listed in the table 2 in each crystal raw material and the crystal.

Table 2

Blinking characteristic

Measure little, the out-of-shape of transparent crystals sample (listed) size of blinking characteristic like table 3.

Adopt 10 μ Ci ¹³⁷Cs excites crystal.With

crystals with the collection of light.One end of the crystal through a Brookfield viscosity of the silicone rubber and 5000cpa from Photonis and have

base XP? 2020 photomultiplier tube (PMT) is connected.Testing is also used in high-pressure

preamplifier

Amplifiers and multi-band analyzer (MCA,

PCI-8k).The multiband analyzer writes down frequency spectrum with PC after electrical signal is converted into numerary signal.

As benchmark, the output of crystal light is as shown in table 3 below with a LYSO crystal that is of a size of 8mm x 8mm x 2mm.The halfwidth that records (FWHM) also is listed in the table below 3.

Table 3

The crystal title	Light output (%) with respect to LYSO	FWHM％
			8x8x2LYSO	100％	10.9％
Crystal 1	90.40％	13.60％
			Crystal 2	130.30％	11.20％
Crystal 4	67.87％	28.78％
			Crystal 5 #1	112.30％	14.50％
Crystal 5 #2	112.30％	13.60％
			Crystal 6	111.50％	12.50％
Crystal 9	89.50％	13.70％
			Crystal 11	58.90％	18.39％
Crystal 10	80.11％	13.66％
			Crystal 12	89.94％	15.72％

The technician in present technique field can find out that crystal 4,5, the output of 9 and 11 light and halfwidth (FWHM) are positioned at the tolerance interval like the proofing unit of PET and so on from table 3.

With the fall time that the FLS920 combination steady state of the Edinburgh Instrument Ltd of Britain Livingston and spectrograph (Combined Steady State and Lifetime Spectrometer) are throughout one's life measured crystal 2 and 9-12, the result is as shown in table 4 below.

Measure the luminescent spectrum of crystal 2 and 9-12 with luminescence spectrophotometer (the Perkin Elmer LS55 of the PerkinElmer Inc. of U.S. state Massachusetts Waltham).Wherein, setting transmitting boundary is that 300 nanometer to 450 nanometers and sweep velocity are 10 nanometer per minutes.The emission peak that records is as shown in table 4.

The density of crystal 2 and 9-12, effective atomic number, number of photons and deliquescence character also are listed in table 4.The correlation parameter of existing crystal NaI (Tl), BGO and LSO is also listed in table 4 as reference.

Table 4

Can find out that from table 4 crystal 9 and 11 character are suitable with other scintillator crystals.

Though describe the present invention in conjunction with the specific embodiments, those skilled in the art will appreciate that and to make many modifications and modification the present invention.Therefore, recognize that the intention of claims is to cover all such modifications and the modification in true spirit of the present invention and the scope.

Claims (11)

1. scintillator, it consists of (Gd _xLu _yM _1-x-y) ₂Si ₂O ₇, wherein M is Ce, Pr or its combination; 0.32＜x＜1 wherein; 0＜=y＜=0.63; 0＜1-x-y＜0.05; Wherein during y=0, M is the combination of Ce and Pr.

2. scintillator as claimed in claim 1 is characterized in that: 0＜y＜0.62.

3. scintillator as claimed in claim 1 is characterized in that: 0＜y＜0.22.

4. scintillator as claimed in claim 1 is characterized in that: M is Ce.

5. scintillator as claimed in claim 1, it is characterized in that: it consists of (Gd _0.7753Lu _0.2190Ce _0.00057) ₂Si ₂O ₇Or (Gd _0.3800Lu _0.6181Ce _0.0019) ₂Si ₂O ₇

6. scintillator as claimed in claim 1, it is characterized in that: it consists of (Gd _0.98Ce _0.01Pr _0.01) ₂Si ₂O ₇Or (Gd _0.9893Ce _0.0097Pr _0.001) ₂Si ₂O ₇

7. scintillator as claimed in claim 1 is characterized in that: it comprises disilicic acid gadolinium crystalline phase.

8. scintillator as claimed in claim 7 is characterized in that: it comprises disilicic acid lutetium crystalline phase.

9. proofing unit that comprises like the described scintillator of arbitrary claim in the claim 1 to 8.

10. proofing unit as claimed in claim 9 is characterized in that: it further comprises the photon detector that is connected with said scintillator light, and said photon detector produces an electrical signal according to the light pulse that scintillator sends.

11. the method with the described proofing unit detected energy of claim 9, it comprises:

By the scintillator received radiation;

Use the photon detector that is connected with scintillator to detect the photon that scintillator sends through radiation.