Fixed in-core detector design using SiC Schottky diodes configured for high axial and radial sensor density and enhanced fission gamma measurement sensitivity

Abstract

A system for measuring gamma spectroscopy of neutron-irradiated materials includes multiple semiconductor sensors. Each of the semiconductor sensors includes a gamma-ray receiving surface disposed on a Schottky layer in contact with an n-doped active layer. The receiving surface is configured to emit electrons upon irradiation with gamma rays. The receiving surface contacts an adjustable telescopic mount configured to adjust the distance between the receiving surface and the Schottky layer. The n-doped layer is fabricated to have a thickness designed to allow electrons having above a defined energy to pass through. The combination of the adjustable receiving surface and active layer thickness defines a minimum and maximum energy response for each of the sensors. Multiple sensors may be assembled into an array, each with its own energy response. Such an array of sensors can measure the gamma spectrum of a material irradiated with neutrons.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 013,859, filed April 22, 2020, the contents of which are incorporated herein by reference in their entirety.

[0002] The present invention relates to radiation detectors, and more particularly to an assembly of multiple Schottky diodes for measuring nuclear fission gamma radiation for power distribution measurements. [Background technology]

[0003] Gamma radiation is produced by nuclear decay, such as nuclear fission, that occurs in nuclear reactors. Nuclear reactors are equipped with measurement systems to detect and measure gamma radiation. However, the proliferation of new nuclear fuels and reactor designs presents challenges to the ability of existing measurement systems to confirm fuel design performance predictions and to provide detailed measurements of operational performance throughout reactor operation in the fuel cycle.

[0004] Nuclear reactor design relies on software simulations for core design and fuel performance predictions, and for reactor component performance predictions under both normal operating conditions and various accident scenarios. Software performance predictions are ultimately compared to actual measurements under normal operating conditions or to simulations of such measurements in test, commercial, or experimental reactors.

[0005] Early generations of light water reactor (LWR) designs used small fission chambers that continuously measured neutron flux along approximately one-third of the length of the fuel assemblies in the reactor to benchmark power distribution measurement and core design software methods. This type of measurement system is called a mobile in-core detector system (MIDS). The fine-spaced axial neutron distribution measurement resolution (~2.4 inches) provided by the MIDS measurement system enabled the identification and diagnosis of many fuel performance issues that caused significant reactor operation, including fuel rod bow geometry, debris deposits on the outside of fuel rods affecting heat transfer or reactivity, and inlet flow distribution asymmetries. The primary negative operational issues associated with the use of MIDS are the complexity, required size, and operation and maintenance costs associated with the use of associated piping and sensors.

[0006] Current generation reactor power distribution measurement systems, called fixed in-core detector (FID) systems, rely on a limited number of radiation sensors at fixed axial and radial locations within the reactor core. Figure 1 illustrates an embodiment 600 of the use of an FID detector system compared to a MIDS detector system. As shown in Figure 1, the signal from the FID sensor represents the average reactor power over a fixed axial region defined by the effective length of the sensing element. An example of a typical Rh FID detector system configuration 610 shows an axial detector spacing 613 of approximately 12 inches. A second example of an OPARSSEL V detector system configuration 620 shows an axial detector spacing 623 of approximately 24 inches. The radial distribution of FID measurements of fuel assemblies requires and is constrained by a location relative to penetration within the reactor vessel. The required averaging of FID systems and the radial distribution location constraints make it difficult to observe differences between highly localized, detailed measurements and predicted power distributions and long-term operating characteristics. For example, an overlaid flux distribution graph 630 depicts the measured flux distribution versus tracking points or core depth. For data acquired using a multiple MIDS detector configuration 625, finer resolution of depth versus flux measurements is more easily obtained than is possible with either the Rh FID configuration 610 or the OPARSSEL V FIG configuration 620. The ability to detect these differences can be important in qualifying the reactor design and in the safe operation of both the fuel and the reactor.

[0007] Furthermore, nuclides produced during the operation of a nuclear reactor can be detected and determined through the use of various types of spectroscopic measurements, including neutron and gamma radiation spectroscopy. The accuracy of performing gamma radiation spectroscopy using existing methods and apparatus is often limited by the interaction of different radiation energies in the active volume of the detector to produce the pulse of interest. It would also be useful for gamma radiation spectroscopy sensors to be small enough to be placed in multiple locations within a nuclear reactor. Disclosed herein are methods and systems that enable a clearer representation of the gamma energy and intensity emitted from the material being analyzed than is currently achievable with other solid-state gamma detector spectroscopy systems. Summary of the Invention

[0008] The following summary is provided to facilitate an understanding of some of the innovative features unique to the disclosed embodiments and is not intended to be a complete description. A complete understanding of the various aspects of the embodiments can be obtained by taking the specification, claims, abstract, and drawings, all of which are considered as a whole.

[0009] An assembly is described herein for in-core power distribution detection suitable for power distribution measurements. The assembly generally includes an elongated housing for placement within a nuclear reactor and a plurality of solid-state gamma radiation detectors, each detector being axially disposed within the housing in a radially spaced relationship with respect to each adjacent detector.

[0010] Each gamma radiation detector includes a Schottky diode having an active semiconductor region and a Schottky contact spanning at least a portion of the active semiconductor region, an ohmic contact layer beneath at least a portion of the active semiconductor region, a layer of Compton and photoelectron source material supported above the Schottky contact that reacts with incident gamma radiation to interact with electrons surrounding source atoms of a source material to generate energetic Compton and photoelectron electrons that permeate through the Schottky contact into the active region of the Schottky diode, the layer of Compton and photoelectron source material being supported above the Schottky contact, a layer of fluid interposed between the Schottky contact and the layer of Compton and photoelectron source material, a first lead extending upward from the radiation detector adjacent the source material, and a second lead extending upward from the radiation detector adjacent the ohmic contact layer. The detectors are spaced apart within the housing such that the first and second leads of each detector are spaced apart from the first and second leads of each of the other detectors.

[0011] Each detector may be covered by an intermediate layer and an outer layer. In various embodiments, the intermediate layer is an aluminum oxide layer. In various embodiments, the outer layer is a stainless steel layer.

[0012] In various embodiments, the distance between the Schottky contact and the layer of Compton and photoelectron source material can be adjusted. In various embodiments, the distance can be adjusted to detect only the highest energy prompt fission gamma radiation. For example, the distance can be adjusted to detect fission gamma radiation greater than about 5 MeV. [Brief explanation of the drawings]

[0013] The features and advantages of the present disclosure can be better understood with reference to the accompanying drawings.

[0014] [Figure 1] FIG. 1 shows a graph illustrating core flux measurements determined by fixed versus movable core sensor configurations in accordance with at least one embodiment of the present disclosure.

[0015] [Figure 2] FIG. 2 shows a side cross-sectional view of an exemplary prior art gamma detector having a Schottky contact in accordance with at least one embodiment of the present disclosure.

[0016] [Figure 3] FIG. 3 shows a cross-sectional side view of a schematic diagram of an example gamma detector used in an example assembly for power distribution detection in a nuclear reactor, in accordance with at least one embodiment of the present disclosure.

[0017] [Figure 4] FIG. 4 shows an axial view of a schematic illustrating an arrangement of three stacked gamma detectors rotated relative to each other within a thimble tube for power distribution detection in a nuclear reactor, according to at least one embodiment of the present disclosure.

[0018] [Figure 5] FIG. 5 illustrates a top view of a stack of multiple exemplary gamma detectors within a thimble tube showing a radial view of the arrangement of rotating signal output leads around the circumference of the thimble tube for power distribution detection within a nuclear reactor, in accordance with at least one embodiment of the present disclosure.

[0019] [Figure 6] FIG. 6 is a graph of gamma energy versus intensity measurements that can be used to identify elements present in an irradiated sample using neutron-driven analysis, according to at least one embodiment of the present disclosure.

[0020] [Figure 7] FIG. 7 is a cross-sectional side view of the gamma detector depicted in FIG. 3 used as part of a gamma radiation spectrometer located within a nuclear reactor, according to at least one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0021] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0022] Directional expressions used herein, such as, but not limited to, top, bottom, left, right, below, above, front, back, and variations thereof, relate to the orientation of the elements as shown in the accompanying drawings and do not limit the scope of the claims, unless expressly stated otherwise.

[0023] In this application, including the claims, unless otherwise stated, all numbers expressing quantities, values, or properties should be understood in all instances to be modified by the term "about." Accordingly, numbers can be read as if preceded by the word "about," even if the term "about" is not explicitly stated along with the number. Accordingly, unless indicated to the contrary, any numerical parameter set forth in the following description may vary depending on the desired properties sought to be obtained in the compositions and methods according to the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter set forth in the description should be construed, at least in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0024] Any numerical range recited herein is intended to include all subranges subsumed therein. For example, a range of "1 to 10" is intended to include all subranges between the recited minimum value of 1 and the recited maximum value of 10 (inclusive), i.e., all subranges with a minimum value of 1 or more and a maximum value of 10 or less.

[0025] As used herein, "axial" means in the direction of or aligned with an axis. In reference to two or more objects, axial means that the objects are positioned along an axis, either in coaxial alignment or parallel to the axis.

[0026] As used herein, "radially spaced" means that two or more objects are positioned such that the objects are spaced apart from one another along the arc of a circle, or disposed along a radius.

[0027] FIG. 4 shows an assembly 100 for in-core power distribution detection suitable for more modern nuclear fuel power distribution measurements and reactor designs. Assembly 100 uses multiple gamma detectors 10′ (shown in FIGS. 3 and 7) positioned preferably axially one above the other within an elongated vessel such as a tube 40. Each detector 10′ has two leads 26 and 28. The axial stack of detectors 10′ is rotated relative to one another along the length of elongated vessel 40 so that the leads of each detector 10′ do not interfere with the leads of other detectors and to maximize the density of measurements that can be obtained.

[0028] In various embodiments, the detector 10′ depicted in FIGS. 3 and 7 may be a modification of that described in U.S. Pat. No. 9,831,375, entitled “Solid State Radiation Detector with Enhanced Gamma Radiation Sensitivity,” which is incorporated herein by reference in its entirety and for all purposes. The previously disclosed gamma detector 10 depicted in FIG. 2 may include a Schottky diode having an active semiconductor region and a Schottky contact over at least a portion of the semiconductor region. The detector 10 described herein and in U.S. Pat. No. 9,831,375 includes, for example, an ohmic contact layer 12 made of tungsten positioned below a silicon carbide conductive substrate 14, which is covered by a layer of epitaxial silicon carbide 16. In various embodiments, the substrate 14 is approximately 300 microns thick, and in various embodiments, the epitaxial layer 16 is approximately 3-100 microns thick. The epitaxial silicon carbide layer 16 is covered by a Schottky contact 18. The Schottky contact 18 may be formed from a highly conductive metal such as platinum or gold, approximately 1 micron thick.

[0029] A thin layer of Compton and photoelectron source material 20, made from, for example, platinum or another suitable high-atom donor material such as lithium fluoride or tungsten, is located over and spaced from at least a portion of Schottky contact 18, defining a gap 22 that, in response to incident gamma radiation, emits electrons that penetrate active region 16 and contribute to the collection of charged particles within region 14. In response to incident gamma radiation, source or electron emitter material 20 can emit electrons that penetrate active region 16 and contribute to the collection of charged particles within the active region.

[0030] The distance defined by gap 22 between Schottky contact 18 and added source layer 20 is adjustable and preferably comprises a fluid with a low effective atomic number and negligible conductance, such as the properties of air at 1 atmosphere pressure with a relative humidity of 20% or less at 70°F (21°C), between electron donor layer 20 and Schottky contact 18. Any such fluid with known density and electron attenuation properties can be used for gap 22.

[0031] A gap 22 between the source layer 20 and the Schottky contact 18 ensures that only electrons generated by gamma radiation of the desired energy contribute to the measurement signal.

[0032] The material used and thickness of source layer 20 are selected based on the energy range of the targeted gamma radiation to be detected by the end user. The addition of an adjustable electron donor layer (symbolically represented by a retractable sleeve surrounding layer 24), i.e., a layer whose thickness and distance from Schottky contact 18 is adjustable, allows gamma radiation to interact with electrons surrounding source atoms in donor material 20 to generate high-energy Compton and photoelectric electrons in the donor layer that penetrate into the active region 16 of silicon carbide detector 10. The thickness of the fluid interposed in gap 22 controls the energy of the donor electrons so that they are collected in the active region.

[0033] Therefore, the charge deposited over a fixed amount of time is proportional to the energy of the gamma radiation incident on layer 20, and therefore the gamma energy and gamma radiation intensity can be determined from appropriate analysis of the electrical output from the silicon carbide device.

[0034] As shown in Figures 3 and 7, the detector 10 described above can be modified (detector 10') to include an insulating layer 34 between the ohmic contact layer 12 and the conductive layer 14. The insulating layer 34 prevents electron discharge and shorting of the tungsten ohmic contact 12. In various embodiments, the active region of the modified detector 10' includes SiC layers 14 and 16. The epitaxial layer 16 provides an additional electron source, n - In this context, photodoping can be achieved by using SiC lightly doped with a dopant of about 10 14 cm -3 ~about 10 16 cm -3 The conductive layer 14 may correspond to a concentration of electron donor elements on the order of . + In this context, heavily doped SiC can be formed using a doping ratio of about 10 18 cm -3 ~about 10 20 cm -3 This can correspond to a concentration of electron donor elements on the order of 1000 Ω. A heavily doped region can ensure better electron transport to the ohmic contact. Reverse bias depletes electrons in the n region 16, and ionizing radiation generates electron-hole pairs in the depletion region. Charge is collected at the ohmic contact under the influence of a voltage applied across the contact.

[0035] In an alternative embodiment, the active region may include epitaxial layer 16 consisting of two regions, one positively doped layer approximately 1 micron thick and one negatively doped layer approximately 3-10 microns thick. Conductive layer 14 may, in various embodiments, include hydrogen ions.

[0036] The detector 10' is very small, less than about 5 mm. The SiC detector is made of a source material 20 and a SiC epitaxial layer 16. -It is preferably configured to detect only the highest energy prompt fission gamma radiation (>~5 MeV) by adjusting the distance between the detector and the detector region.

[0037] 3 and 7, the outer surface of detector 10' is covered, in various embodiments, by an intermediate layer 30 made of aluminum oxide (Al2O3) or magnesium oxide (MgO) to act as an electrical dielectric and separate the conductive materials within the detector from one another, in addition to the stainless steel enclosure. Intermediate layer 30 is covered by an outer layer 32, preferably made of stainless steel or Iconel®, which acts as an enclosure to provide structural integrity to detector 10'.

[0038] A first lead 26, covered by an aluminum oxide layer 30 and an outer stainless steel layer 32, extends from the top of the detector 10' near the source material layer 20 at point 44. A second lead 28, also covered by an aluminum oxide layer 30 and an outer stainless steel layer 32, extends from the bottom of the detector 10' near the ohmic contact layer 12 at point 46. The first and second leads 26 and 28 are on opposite sides of the detector 10'. In a radial configuration, the first and second leads 26 and 28 of the detector 10' can be positioned, for example, 180° apart from each other. The distance between the first and second leads is indicated in Figures 3-5 and 7 by ΔV, which represents the voltage difference.

[0039] 4 and 5 show an arrangement of a detector 10' including an embodiment of the assembly 100 for power distribution measurements.

[0040] Detector 10' is shown as being housed in an elongated vessel, such as an instrument tube 40, that is positioned in use adjacent to a reactor vessel, e.g., a fuel rod. The distance between the inner surface of tube 40 and the outer surface of detector 10' defines an open space 42 that is filled with air, argon, or another inert gas.

[0041] FIG. 4 is an axial schematic view of the assembly 100, showing only three axially spaced detectors for illustrative purposes. FIG. 5 is a cross-sectional view of the assembly 100 shown in FIG. 3, illustrating the arrangement of the tube 40 and detectors 10′, showing three sets of leads 26 / 28 separated by distances indicated as ΔV1, ΔV2, and ΔV3, another set indicated as ΔVn, where n represents any number of additional detectors 10′. In use, there will be multiple detectors 10′. For example, a typical instrument tube 40 used in a nuclear reactor (not shown) may have as many as 61 detectors 10′. The number of detectors 10′ in any tube 40 will vary depending on the length of the tube and the measurement needs of the reactor. The detectors 10′ are arranged so that the leads 26 / 28 of each detector 10′ are radially spaced from the leads 26 / 28 of the remaining detectors 10′ in the tube 40.

[0042] This approach essentially eliminates the contribution of fission product gamma radiation to the measured signal. In various embodiments, the SiC detectors 10' are positioned at closely spaced locations inside and along the length of a drying tube 40 having an outer diameter small enough to fit, for example, in the central instrument thimble of a fuel assembly or other strategic measurement locations in or around the reactor and / or inside the reactor vessel. As used herein, "closely spaced" means less than about 12 inches, and in various embodiments, about 2-3 inches or less, preferably about 2.4 inches or less, and is comparable to or smaller than the spacing at the finely spaced axial neutron distribution measurement resolution (~2.4 inches) provided by the MIDS measurement system.

[0043] For each of the many SiC detectors 10' located in or around the core, there is a SiC signal response predicted by the core design software. The use of small, densely packed SiC detectors 10' essentially eliminates the effects of averaging flux measurements over long fuel assembly lengths, as shown at 630 in Figure 1. As previously explained, the required averaging and radial distribution location constraints of currently used FLD systems make it difficult to observe differences between highly localized, detailed measurements and predicted power distributions and long-term operating characteristics. The SiC detector 10' configuration described herein closely mimics the axial measurement density (e.g., 1 per 2.4 in) distribution of a MIDS mobile fission chamber and has the ability to resolve the effects on the core of grids, debris deposits (e.g., CRUD) outside the fuel rods that affect heat transfer or reactivity, and localized boiling. This allows for the development of more accurate synthesis of axial flux distributions. The difference between the measured detector 10' signal and the predicted detector 10' signal can be used to generate highly detailed core power distribution measurements that can be used to more precisely determine the accuracy of the core design modeling tools and to identify the presence of fuel performance anomalies.

[0044] The detector 100 assembly can be permanently placed inside every fuel assembly instrument thimble or inside a prepared location within the reactor fuel matrix.

[0045] The signal leads 26 / 28 used to output the detector signal within the detector tube 40 are oriented as shown in Figures 4 and 5 to maximize the SiC detector element active volume surface area and axial density while using a standard mineral insulated cable design for the signal leads. The SiC signal utilizes a common reactor ground to simplify the configuration of the electrical connector that couples the measured voltage difference to the signal processing electronics.

[0046] Novel aspects of the design of the detector assembly 100 described and illustrated herein include, for example: 1. The use of a rotational arrangement as a function of the axial position of the detector 10' inside the tube 40 maximizes the number of identical detectors 10' that can be accommodated within the tube 40 and minimizes the required outer diameter of the drying tube 40. 2. The use of SiC detectors 10' in an assembly 100 tuned by adjusting the gap 22 in each detector 10' to detect maximum energy prompt fission gamma energy allows for continuous measurement of the reactor's fission power distribution. This prompt fission information can be used for reactor anomaly detection, continuous power distribution monitoring, and reactor protection from a single sensor design. 3. The gamma-ray sensitive SiC detector 10' assembly 100 design allows the assembly to continue in use for the life of the reactor, as there are no components that degrade or decrease as a function of radiation exposure. 4. The thermal attributes of the SiC detector design shown in FIG. 5 may enable its use in designs for pressurized water reactors, boiling water reactors, high temperature gas-cooled reactors, and liquid metal-cooled reactors.

[0047] In principle, the design and configuration of the radiation detector assembly 100 shown in Figures 4 and 5 can replace all other radiation sensors used in nuclear reactor operation. Furthermore, the effort to migrate from current measurement systems to the radiation detector assembly 100 described herein should be very easy and cost-effective.

[0048] In a nuclear reactor, the coolant flow rate through the fuel channels is known and can be measured continuously or periodically, as desired, by known techniques. A fission product may be selected that is expected to be present in sufficient quantity in the event of a leak in the cladding tube to produce measurable gamma radiation. An exemplary fission product is La, since it is one of the most widely used fissile materials in reactors that use UO2 as the fissile material. 140 Furthermore, Xe 135It may be useful to monitor changes in the presence of other fission products in the coolant that produce relatively low-energy gamma radiation, such as the prompt n-γ emitted from La. This product is much more likely to escape the fuel matrix through fuel cladding defects, so if a leak occurs in the fuel cladding, La 140 neutron-irradiated materials can form nuclides capable of emitting gamma radiation. Gamma energy and intensity measurements can provide the information necessary to determine the composition of the neutron-irradiated elements as well as their quantities using neutron activation analysis (NAA) techniques well known to those skilled in the art.

[0049] Some examples of elements present in neutron-irradiated material samples can be determined by measuring gamma energy spectra, such as those shown in FIG. 6. Gamma energy and intensity measurements provide the information necessary to determine the elements and quantities present in the irradiated material using neutron activation analysis (NAA) techniques well known to those skilled in the art. The suppression of continuum noise observed in FIG. 6 may allow for more accurate determination of the intensity of a single gamma energy peak than is currently achievable using current gamma spectroscopy equipment. Continuum noise suppression allows for more accurate measurement of changes in fission product concentration in fuel channels, as described in U.S. Patent Application No. 16 / 439,061, filed June 12, 2019, entitled "Method and System for Detecting and Identifying In-Core Location of Fuel Bundles with Cladding Perforations in CANDU-Type Nuclear Reactors," the contents of which are incorporated herein by reference in their entirety and for all purposes. Such measurements may be useful for identifying the presence and axial location of fuel defects in fuel channels.

[0050] Using solid-state radiation detectors configured to be particularly sensitive to gamma radiation, gamma radiation spectrograms can be generated from neutron-irradiated material samples, as illustrated in FIG. 6. Such detectors are described in U.S. Pat. No. 9,831,375, previously referenced and further shown schematically in FIGS. 3 and 7. Each SiC detector can be configured as a single channel analyzer (SCA) (e.g., an ORTEC® 550A single channel analyzer) input, allowing each detector to cover an extremely narrow gamma energy range. The energy range can be determined according to the depth of the gap 22 between the electron emitter 20 and the Schottky contact 18 and the depth Te of the n-active region 16.

[0051] The gap 22 between the electron emitter 20 and the Schottky contact 18 may contain a fluid 24 interposed between the Schottky contact 18 and the layer of Compton and photoemissive material 20, as described above. Gamma radiation 810 impinging on the electron emitter 20 produces electrons having energies related to the energy of the impinging gamma radiation 810. Low-energy gamma radiation may result in corresponding low-energy Compton or photoemission scattered electrons. Low energy may be defined as an energy that results in electrons that cannot penetrate the full thickness of the gap 22 and therefore cannot enter the active n-region 16. As a result, such low-energy electrons cannot be detected by the SCA. An array of such detector elements may include individual elements, each with a gap 22 of a different thickness between the electron emitter 20 and the Schottky contact 18. Because the size of the gap 22 determines the low-energy cutoff of the detector, the array may include multiple detector elements with different lower-energy detection capabilities.

[0052] The value of the depth Te of the n-layer 16 can be selected to define an upper limit for the Compton or photoelectric scattered electrons 820 that can be detected by the sensor. Te can be calculated according to the following empirical formula by L. Katz and A. S. Penfold, Rev. Mod. Phys., 24 (1952), p. 28:

number

[0053] It will be appreciated that all electrons 815 having energies that result in a travel distance greater than Te along the thickness of the active volumes 16 and 14 will generate pulses in the SCA of substantially the same amplitude. These high-energy electrons 815 may result from Compton scattering and the photoelectric effect corresponding to high-energy gamma radiation 810 impinging on the electron emitter layer 20. The resulting high-energy electrons 815 may have sufficient energy to completely penetrate the thickness of the detector's active region 16, Te, and impinge on the rear ohmic contact 12. The pulses associated with these events all have essentially the same pulse amplitude and can be filtered out by the upper-level discriminator component of the SCA. It will be appreciated, therefore, that the thickness of Te determines the upper limit of the energy detected by the sensor.

[0054] Intermediate-energy electrons 820 can be generated by Compton scattering and the photoelectric effect, which corresponds to intermediate-energy gamma radiation 810. By definition, intermediate-energy electrons 820 can penetrate the gap 22 between the electron emitter layer 20 and the Schottky contact 18 but cannot pass beyond the active n-region 16. These electrons can be actively counted by the SCA as having a pulse height less than the maximum pulse height filtered by the upper discriminator. Thus, a detector array can be made from an array of Schottky sensors, each defined by a gap 22 and an active region depth Te. Thus, each sensor can be tuned at both the low-energy end (depth of the gap 22) and the high-energy end (thickness of the Te layer). Data from each gamma energy sensor in the SCA array, with different values of gap 22 and Te, can be combined to produce gamma energy and associated gamma intensity measurements, as shown in the spectrograph of FIG. 6. However, variations in the thickness of the gap 22 can reduce the lower continuum signal levels at measured gamma energies associated with particular nuclides, allowing for the detection of more sharply defined energy peaks at lower energy and intensity values.

[0055] All patents, patent applications, publications, or other disclosure materials mentioned herein are incorporated herein by reference in their entirety, just as if each individual reference were expressly incorporated by reference. All documents and any materials, or portions thereof, mentioned as being incorporated herein by reference are incorporated herein to the extent that the incorporated materials do not contradict existing definitions, descriptions, or other disclosure materials set forth in this disclosure. Therefore, to the extent necessary, the disclosure set forth herein supersedes any conflicting materials incorporated herein by reference, and the disclosure expressly set forth in this application takes precedence.

[0056] The present invention has been described with reference to various exemplary and illustrative embodiments. The embodiments described herein are understood to provide illustrative features of various details of various embodiments of the disclosed invention. Thus, unless otherwise indicated, it should be understood that, to the extent possible, one or more features, elements, components, ingredients, materials, structures, modules, and / or aspects of the disclosed embodiments can be combined, separated, substituted, and / or rearranged with one or more other features, elements, components, ingredients, materials, structures, modules, and / or aspects of the disclosed embodiments without departing from the scope of the disclosed invention. Accordingly, those skilled in the art will recognize that various substitutions, modifications, or combinations are possible in any of the exemplary embodiments without departing from the scope of the invention. Moreover, those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, upon review of this specification, many equivalents to the various embodiments of the invention described herein. Therefore, the present invention is limited by the claims, and not by the description of the various embodiments. The following items are elements that are claimed in the international application: (Item 1) 1. A method of manufacturing a gamma radiation detector, said method comprising: To provide a SiC radiation detector, the SiC radiation detector comprising: a Schottky diode having an active semiconductor region and a Schottky contact spanning at least a portion of the active semiconductor region; a layer of Compton and photoelectron source material supported on the Schottky contact, the layer of Compton and photoelectron source material configured to react with incident gamma radiation to emit Compton and photoelectron electrons that penetrate through the Schottky contact into the active semiconductor region of the Schottky diode; a layer of fluid interposed between the Schottky contact and the layer of Compton and photoelectron source material; providing, adjusting a distance between the Schottky contact and the layer of Compton and photoelectron source material, thereby adjusting a minimum detection energy of the SiC radiation detector; fabricating the active semiconductor region to have a particular thickness, thereby determining a maximum detection energy of the SiC radiation detector; contacting the SiC radiation detector to a charge input of a single channel analyzer; A method comprising: (Item 2) Item 10. The method of item 1, wherein providing a SiC radiation detector includes providing a SiC radiation detector having an n-active semiconductor region. (Item 3) 3. The method of claim 2, wherein providing a SiC radiation detector includes providing a SiC radiation detector having an n+ conductive region disposed below the active semiconductor region. (Item 4) 2. The method of claim 1, wherein adjusting the distance between the Schottky contact and the layer of Compton and photoelectron source material comprises actuating a telescoping sleeve in contact with the Compton and photoelectron source material surrounding a layer of fluid therebetween. (Item 5) Fabricating the active semiconductor region to have a particular thickness comprises fabricating the active semiconductor region by:

number

Claims

1. 1. A method of manufacturing a gamma radiation detector, said method comprising: A SiC radiation detector is provided, comprising: a Schottky diode having an active semiconductor region and a Schottky contact spanning at least a portion of the active semiconductor region; a layer of Compton and photoelectron source material supported on the Schottky contact, the layer of Compton and photoelectron source material configured to react with incident gamma radiation to emit Compton and photoelectron electrons that penetrate through the Schottky contact into the active semiconductor region of the Schottky diode; a layer of fluid interposed between the Schottky contact and the layer of Compton and photoelectron source material; providing the SiC radiation detector, adjusting a distance between the Schottky contact and the layer of Compton and photoelectron source material to thereby determine a minimum detection energy of the SiC radiation detector; fabricating the active semiconductor region to have a particular thickness, thereby determining a maximum detection energy of the SiC radiation detector; contacting the SiC radiation detector to a charge input of a single channel analyzer; A method comprising:

2. The method of claim 1 , wherein providing a SiC radiation detector comprises providing a SiC radiation detector having an n-active semiconductor region.

3. The method of claim 2 , wherein providing a SiC radiation detector comprises providing a SiC radiation detector having an n+ conductive region disposed beneath the active semiconductor region.

4. 4. The method of claim 1, wherein adjusting the distance between the Schottky contact and the layer of Compton and photoelectron source material comprises actuating a telescoping sleeve in contact with the Compton and photoelectron source material surrounding a layer of fluid therebetween.

5. Fabricating the active semiconductor region to have a particular thickness includes fabricating the active semiconductor region to have a particular thickness by: [Equation 1] wherein E β 5. The method of claim 1, wherein is a maximum value in MeV.

6. 1. A method of manufacturing a gamma radiation detector array, said method comprising:

1. Providing a plurality of SiC radiation detectors, each of which comprises: a Schottky diode having an active semiconductor region and a Schottky contact across at least a portion of the active semiconductor region; a layer of Compton and photoelectron source material supported on the Schottky contact, the layer of Compton and photoelectron source material configured to react with incident gamma radiation to emit Compton and photoelectron electrons that penetrate through the Schottky contact into the active semiconductor region of the Schottky diode; a layer of fluid interposed between the Schottky contact and the layer of Compton and photoelectron source material; providing the plurality of SiC radiation detectors, adjusting, for each of the plurality of SiC radiation detectors, a distance between the Schottky contact and the layer of Compton and photoelectron source material, thereby determining a minimum detection energy for each of the plurality of SiC radiation detectors; fabricating the active semiconductor region to have a particular thickness for each of the plurality of SiC radiation detectors, thereby determining a maximum detection energy for each of the plurality of SiC radiation detectors; contacting each of the plurality of SiC radiation detectors to a charge input of one of a plurality of single channel analyzers; A method comprising:

7. 7. The method of claim 6, wherein adjusting the distance between the Schottky contact and the layer of Compton and photoelectron source material for each of the plurality of SiC radiation detectors comprises adjusting a distance between the Schottky contact and the layer of Compton and photoelectron source material of a first SiC radiation detector, the distance being different from a distance between the Schottky contact and the layer of Compton and photoelectron source material of a second SiC radiation detector.

8. 8. The method of claim 6 or 7, wherein fabricating the active semiconductor region to have a particular thickness for each of the plurality of SiC radiation detectors comprises fabricating the active semiconductor region of a first SiC radiation detector to have a first particular thickness and fabricating the active semiconductor region of a second SiC radiation detector to have a second particular thickness.

9. 9. The method of claim 6, wherein determining a minimum detection energy for each of the plurality of SiC radiation detectors comprises determining a minimum detection energy for a first SiC radiation detector that is different from a minimum detection energy for a second SiC radiation detector.

10. 10. The method of claim 6, wherein determining a maximum detection energy of each of the plurality of SiC radiation detectors comprises determining a maximum detection energy of a first SiC radiation detector that is different from a maximum detection energy of a second SiC radiation detector.

11. 1. A system for measuring the energy and amplitude of gamma radiation emissions, comprising: A plurality of SiC radiation detectors, each of the plurality of SiC radiation detectors comprising: a Schottky diode having an active semiconductor region and a Schottky contact across at least a portion of the active semiconductor region; a layer of Compton and photoelectron source material configured to emit Compton and photoelectron electrons in response to incident gamma radiation to penetrate through the Schottky contact into the active semiconductor region of the Schottky diode, the layer of Compton and photoelectron source material supported on the Schottky contact; a layer of fluid interposed between the Schottky contact and the layer of Compton and photoelectron source material; Including, for each of the plurality of SiC radiation detectors, a distance between the Schottky contact and the layer of Compton and photoelectron source material is adjustable; for each of the plurality of SiC radiation detectors, the active semiconductor region is fabricated to have a particular thickness, thereby determining a maximum detection energy for each of the plurality of SiC radiation detectors; the plurality of SiC radiation detectors; a plurality of single channel analyzers, each configured with a charge input contacting one of the plurality of SiC radiation detectors; Including, the system.

12. The system of claim 11 , wherein each of the single channel analyzers is configured to apply a reverse bias voltage to its associated SiC radiation detector.

13. 13. The system of claim 11 or 12, wherein each of the plurality of SiC radiation detectors includes an adjustable, retractable sleeve in contact with the Compton and photoelectron source material surrounding the layer of fluid.

14. 14. The system of claim 11, wherein each of the plurality of SiC radiation detectors further comprises an insulating layer between an ohmic contact layer and the active semiconductor region.

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