Patent Publication Number: US-2016238503-A1

Title: Device, system and method for density measurements using gamma radiation

Description:
FIELD OF THE INVENTION 
     The present invention relates to processes for density measurements of raw materials, specifically, materials located under sea water or under other layer(s) of liquid(s). 
     BACKGROUND OF THE INVENTION 
     The mass density or density of a material is its mass per unit volume. Usually represented by the Greek letter ρ, density is defined as mass divided by volume: 
     
       
         
           
             
               ρ 
               = 
               
                 m 
                 V 
               
             
             , 
           
         
       
     
     where ρ is the density, m is the mass, and V is the volume. In some cases, density is also defined as its weight per unit volume. The term density is equally applicable to solids (including suspensions), liquids, and gases, whereas usually values of density are given in terms of grams per cubic centimeter. 
     If the average density (including any air below the waterline) of an object is less than water it will float in water and if it is more than water it will sink in water. 
     Density is sometimes expressed by the dimensionless quantity “specific gravity” or “relative density”, i.e. the ratio of the density of the material to that of a standard material, usually water. Thus a specific gravity less than one means that the substance floats in water. 
     A densitometer may be used to indicate and record the density of a flowing stream of a liquid or a gas. 
     Two precision methods, the oscillator or vibrator method and the magnetic method, have emerged which allow more rapid and accurate determinations on liquid systems. 
     In the oscillator method, the density of a sample is related to the change in resonance frequency of a laterally vibrating tube. This frequency is inversely proportional to the square root of the mass of the tube and its contents. By calibrating the tube with media of known density at a given temperature, the density of unknown solutions may be determined if the volumes are strictly identical. It is now established, that the accuracy of this method decreases as the viscosity of the medium increases. Hence, accurate viscosity measurements must accompany the density calibrations for a given instrument. 
     The density of a material varies with temperature and pressure. This variation is typically small for solids, suspensions and liquids but much greater for gases. 
     SUMMARY OF THE INVENTION 
     According to some demonstrative embodiments, there is provided a system for the measurement of density of a raw material including at least one penetrating device, wherein the device may include at least one radiation source; at least one detector; at least one input device; and at least one output device. 
     According to some embodiments, the raw material may be Carnallite. 
     According to some embodiments, the at least one radiation source may include a Gamma radiation source. 
     According to some embodiments, the Gamma radiation source may be Co-60. 
     According to some embodiments, the at least one detector may include a scintillator. 
     According to some embodiments, the scintillator may be made of inorganic crystal. 
     According to some embodiments, the at least one detector may be contained in a Teflon container. 
     According to some embodiments, the at least one penetrating device may include a tube wherein the at least one radiation source can be positioned at a first, inactive, position and at a second, active position. 
     According to some embodiments, the at least one penetrating device may include an opening at a predetermined angle, configured to enable the at least one radiation source to omit radiation towards the at least one detector. 
     According to some embodiments, the angle may be between 0-90 degrees, preferably between 20-50 degrees, most preferably, 45 degrees. 
     According to some demonstrative embodiments, there is provided a method for in situ measuring of the density of a raw material including inserting at least one penetrating device into the raw material, wherein said device includes at least one radiation source; positioning at least one detector at a predetermined angle from said penetrating device, wherein said detector is adapted to receive radiation omitted from said radiation source and wherein said detector is adapted to transmit information to at least one input device; and gathering information from said input device and providing density measurement results of said raw material via at least one output device. 
     According to some embodiments, transmitting information to at least one input device may include a wireless transmission. 
     According to some embodiments, positioning said at least one detector at a predetermined angle from said penetrating device may include placing said detector on the surface of the raw material. 
     According to some embodiments, the in situ measuring may be performed in a hazardous environment. 
     According to some embodiments, the hazardous environment may include liquid environments selected from the group including liquid environments rich in salt, acidic environments, high temperature environments or combinations thereof.
         According to some demonstrative embodiments, there is provided a penetrating device for the measurement of a density of a raw material, comprising: a hollow tube configured to encompass a radiation source; a lead covering, surrounding said tube; and a cylindrical housing configured to encompass said tube and said lead covering, wherein said device is configured to be inserted to said raw material and omit radiation.   According to some embodiments, the radiation source can be positioned at a first, inactive, position within said tube and at a second, active position within said tube.   According to some embodiments, when the source is at the second, active position within said tube, radiation omitted from said source can be detected by at least one detector.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become fully understood from the detailed description given herein below and the accompanying drawings, which are given by way of illustration and example only, and thus not limiting in any way, wherein: 
         FIG. 1  is a schematic illustration of a system in accordance with some demonstrative embodiments described herein. 
         FIG. 2 , is a schematic illustration of a system in accordance with some demonstrative embodiments described herein. 
         FIG. 3A  is a schematic illustration of a penetrating device, and in  FIG. 3B  is a schematic illustration of the angle of radiation transmission from a penetrating device to a detector in accordance with some demonstrative embodiments described herein. 
         FIG. 4  is a schematic illustration of an angle of radiation from a radiation source to a detector, in accordance with some demonstrative embodiments described herein. 
         FIG. 5  depicts a graph illustrating the use of a LaBr 3 (Ce) detector with Co-60 radiation source inside Carnallite, in accordance with some demonstrative embodiments described herein. 
         FIG. 6  is a schematic illustration of a statistical analysis of the density measurement results as measured by a radiation sampler and a manual cylindrical sampler. 
         FIG. 7  depicts a calibration graph in accordance with some demonstrative embodiments described herein. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In some demonstrative embodiments, there is provided a device, system and method for the in situ density measurement of raw materials using a source of radiation. 
     According to some demonstrative embodiments, the system of the present invention may be preferably used to determine the density measurement of a material located under at least one liquid layer, e.g., under sea water. 
     According to some embodiments, the system may include at least one radiation source, preferably emitting Gamma radiation, and at least one sensor, to determine the density of a raw material. 
     According to some demonstrative embodiments, the system described herein may be mounted on a vessel, e.g., a boat, and deployed to determine the in situ density of a material located below water level. 
     According to some demonstrative embodiments, the system described herein may be used to determine the in situ density of a material located in a hazardous environment. According to some embodiments, the term “hazardous environment” as used herein, may refer to any environment which may be hazardous to a human and/or a machine e.g., including electronic components, including, for example, liquid environments rich in salt, acidic environments, high temperature environments and the like. 
     According to some demonstrative embodiments, the present invention provides for a system for the in situ density measurements of materials. According to these embodiments, the in situ measurements are highly preferable, in comparison to manual extraction of a material and laboratory density measurements, whereas in situ measurements do not disturb the natural environment of the examined material, e.g., in manual measurements disturbing the natural environment of the examined sampler may cause the density results to be inaccurate. 
     According to some demonstrative embodiments, the system described herein may include at least one penetrating device which includes a radiation source, e.g., configured to penetrate a raw material for which the density is to be measured; at least one detector, e.g., configured to detect the radiation emitted from the radiation source; at least one data processing device (also referred to as “input device”), e.g., configured to receive input from the at least one detector; and at least one output device, e.g., configured to provide an output representing the density measured by the system. 
     According to some demonstrative embodiments, the at least one data processing device a computer, for example, a Personal Computer (PC), a desktop computer, a mobile computer, a laptop computer, a notebook computer, a tablet computer, a server computer, a handheld computer, a handheld device, a Personal Digital Assistant (PDA) device, a handheld PDA device, an on-board device, an off-board device, a hybrid device, a vehicular device, a non-vehicular device, a mobile or portable device, a consumer device, a non-mobile or non-portable device, a wireless communication station, a video device, an audio device, an audio-video (A/V) device, DVD player, a DVD recorder, a HD DVD recorder, a Personal Video Recorder (PVR), a broadcast HD receiver, a video source, an audio source, a video sink, an audio sink, a stereo tuner, a broadcast radio receiver, a flat panel display, a Personal Media Player (PMP), a digital video camera (DVC), a digital audio player, a speaker, an audio receiver, an audio amplifier, a gaming device, a data source, a data sink, a Digital Still camera (DSC), cellular radio-telephone communication systems, a cellular telephone, a wireless telephone, a Personal Communication Systems (PCS) device, multi-standard radio devices or systems, a wired or wireless handheld device (e.g., BlackBerry, Palm Treo), a Wireless Application Protocol (WAP) device, a Geographic Pointing System (GPS) or the like. 
     According to some demonstrative embodiments, the at least one output device may include, for example, a monitor, a screen, a flat panel display, a Cathode Ray Tube (CRT) display, a Liquid Crystal Display (LCD), an LED display, a plasma display unit, a printer, one or more audio speakers or earphones, or other suitable output devices. 
     Discussions herein utilizing terms such as, for example, “processing”, “computing”, “calculating”, “determining”, “establishing”, “analyzing”, “checking”, or the like, may refer to operation(s) and/or process(es) of a computer, a computing platform, a computing system, or other electronic computing device, that manipulate and/or transform data represented as physical (e.g., electronic) quantities within the computer&#39;s registers and/or memories into other data similarly represented as physical quantities within the computer&#39;s registers and/or memories or other information storage medium that may store instructions to perform operations and/or processes. 
     The terms “plurality” and “a plurality” as used herein include, for example, “multiple” or “two or more”. For example, “a plurality of items” includes two or more items. 
     According to some preferred embodiments, the system of the present invention may be used to measure and determine the in-situ density of salt and/or other suitable sediment. 
     According to some preferred embodiments, the system of the present invention may be used to measure and determine the density of Carnallite, which is an evaporite mineral, a hydrated potassium magnesium chloride with formula: KClMgCl 2 .6(H 2 O). 
     Carnallite usually forms in marine evaporite deposits where sea water has been concentrated and exposed to prolonged evaporation. Carnallite is usually massive to fibrous with rare pseudohexagonal orthorhombic crystals. 
     Being is an important source of Potassium Chloride (also referred to herein as “KCl” or “Potash”), which is an invaluable source for the production of synthetic fertilizers, measuring the density of Carnallite in aqueous ponds, where it precipitates, usually includes sampling the Carnallite and measuring the density in a lab. 
     In contrast, the present invention allows for the in situ measurement of Carnallite density. 
     According to some embodiments, the system described herein may include a device which emits radiation. The device may be configured to penetrate a material, e.g., a material for which the density id to be measured. 
     According to some embodiments, the device is configured to contain one or more radiation emitting sources. 
     According to some demonstrative embodiments, the term “radiation” may include any suitable energy that comes from a source and travels through some material or through space. Examples of radiation may include electromagnetic, e.g., Gamma radiation or X-ray radiation, particulate radiation, Co-60 radiation, Cs-137 radiation, Na-22 radiation, Na-24 radiation, Au-198 radiation, Zn-65 radiation, Mn-54 radiation, U nat  radiation, Th nat  radiation, Radium radiation, annihilation sources radiation and the like. 
     Gamma rays typically have frequencies above 10 exahertz (or &gt;1019 Hz), and therefore have energies above 100 keV and wavelengths less than 10 picometers. 
     According to some demonstrative embodiments, the preferred source for Gamma rays for the present invention may be Cobalt-60, (also referred to herein as “Co-60”). Co-60 is a synthetic radioactive isotope of cobalt with a half-life of 5.27 years. It may be produced artificially by neutron activation of the isotope Co-59. Co-60 decays by beta decay to the stable isotope nickel-60 ( 60 Ni), wherein the activated nickel nucleus emits two gamma rays. 
     In some demonstrative embodiments, the one or more radiation emitting sources (also referred to herein as “the radiation source”) and as described in detail below with respect to the drawings, may be contained within the device in a housing, e.g., a cylinder shape housing, for example, enabling the radiation source to move within the housing. As described in detail below, the moving of the radiation source within the housing may enable the concealment of the radiation source, e.g., when the device is not used. 
     According to some embodiments, the radiation source may be at least partially exposed when the device is used, in order to enable the measurement of a the density of a material. 
     According to some demonstrative embodiments, the radiation source may be mounted inside a lead shielding container (“lead cylinder”) that has a conical opening in a defined angle, e.g, having the angle aimed toward a detector located above the container. 
     According to some demonstrative embodiments, the angle may be at a range between 0-90 degrees. Preferably, the angle is between 20-50 degrees, most preferably 45 degrees or optionally 26.56 degrees. 
     As previously described, the lead cylinder may include a vertical hole, wherein the radiation source may be placed at two stages: at the center of the lead cylinder, e.g., during storage, and down, i.e., at the end of the lead cylinder, for example, during irradiation. 
     In some demonstrative embodiments, Co-60 may be the preferred radiation source due its dual energy emission lines at the energies: 1173, 1332 keV. The gamma rays can penetrate into a dense solid layer of several decimeters of a chosen material, e.g., Caranllite. The attenuation of the radiation intensity is dependent on the specific attenuation coefficient (for certain energy), on the layer thickness, and on the layer density (gram/cc). As mentioned hereinabove, the Co-60 has a half-life of 5.272 years, therefore the decay has to be taken into account in order to compare different measurements at different periods of time. 
     According to some demonstrative embodiments, the system may include a detector, configured to detect the gamma radiation emitted from the radiation source. 
     According to some demonstrative embodiments, the detector may include any device capable of recovering information contained in photon radiation, including, LaBr 3 (Ce) (also known as “BrilLianCE™”) or for example, NaI (Tl), CsI, CsI(Tl), CsI(Na), Li(Eu), BGO, CdWO 4 , ZnS(Ag), LuAP, GSO, YAP, YAG, LSO, CdZnTe. According to some embodiments, the preferred detector may be LaBr 3 (Ce), as this detector has optimal spectral resolution for detection of radiation at high levels of background radiation. 
     According to some preferred embodiments of the present invention, the detector may be scintillator. For example, a preferred detector may capable of converting the kinetic energy of charged particles to a visible light with substantial scintillation capabilities, for example, as taught by Glenn F. Knoll, “Radiation Detection and Measurement” 3 rd  ed. John Wiley &amp; Sons, 1999, in Chapter 8. 
     According to some demonstrative embodiments, the stages of detecting radiation by the scintillator detector may include:
         Radiation energy absorption: molecule excitation   Luminescence: visible light emission   Light transport to the photo-cathode   Light absorption and electron emission in the cathode   Multiplying electrons bunches by the Photomultiplier   Electronic signals output to the multi-channel-analyzer   Spectrum display and processing       

     The extent and ability of radiation detection of the detector according to some embodiments is further detailed below with respect to  FIG. 6 . 
     According to some demonstrative embodiments, the detector may be placed in a designated housing, for example, to prevent the penetration of liquid, e.g., water, to the detector. According to some embodiments, the housing may be extremely important when the detector is placed in a hazardous environment, 
     According to some preferred embodiments, the housing may be made of a material capable of blocking and/or preventing the hazardous environment from damaging the detector, including, for example, from Polytetrafluoroethylene (PTFE) (Teflon® by DuPont Co.) and/or silicone and the like. 
     According to some demonstrative embodiments, the detector may include one or more wireless device(s), e.g., configured to communicate with the at least one input device. The term “wireless device” as used herein includes, for example, a device capable of wireless communication, a communication device capable of wireless communication, a communication station capable of wireless communication, a portable or non-portable device capable of wireless communication, or the like. In some demonstrative embodiments, a wireless device may be or may include a peripheral that is integrated with a computer, or a peripheral that is attached to a computer. In some demonstrative embodiments, the term “wireless device” may optionally include a wireless service. 
     According to some embodiments, the system may preferably include a detector having one or more wireless device(s), e.g., due to the corrosive nature of hazardous environments which can harm communication cables and/or cords. 
     According to some embodiments, the radiation emitted from the source is preferably detected beyond and/or through an inspected material in order to implement an attenuation measurement method. 
     Reference is now made to  FIG. 1  which illustrates a system  100  in accordance with some demonstrative embodiments described herein. 
     As shown in  FIG. 1 , system  100  includes a penetrating device  102 , a detector  106 , an input device  108  and an output device  110 . 
     According to some demonstrative embodiments, penetrating device  102  includes a radiation source  104 , e.g., configured to radiate towards detector  106 . 
     According to some embodiments, device  102  is configured to penetrate into a raw material, for example, material  114 , which may include Carnallite and water as shown in  FIG. 1 . 
     Detector  106  is configured to be positioned on top of material  114 , e.g., not penetration into material  114 . 
     According to some embodiments, and as shown in  FIG. 1  source  104  may radiate abeam of radiation  112  towards detector  106 , for example, wherein the radiation passes through material  114  before it reaches detector  106 . 
     According to some embodiments, detector  106  is configured to transmit data to input device  108 , for example, data related to the amount of radiation received at detector  106  after passing through material  114 . 
     According to some embodiments, input device  108  may process the data received from detector  106  and calculate the density of material  114 . Input device  108  may transfer the calculated data to present a calibration graph and/or table on output device  110 . 
     Reference is now made to  FIG. 2 , which illustrates a system  100  in accordance with some demonstrative embodiments. 
     According to some embodiments, as shown in  FIG. 2 , system  100  may be mounted on a watercraft  204 , e.g., a boat. 
     Watercraft  204  may float on water layer  206 , e.g., a sea, wherein material  114  is located below layer  206 . 
     System  100  may be used to measure and determine the density of material  114 , wherein device  102  and detector  106  are lowered into water layer  206 . According to some embodiments, device  102  penetrates material  114 , e.g., a Carnallite floor, and detector  106  is placed on top of material  114 . 
     In some embodiments, device  102 , having been placed within material  114  radiates towards detector  106 . Detector  106  sends data  202  to input device  108 . According to some embodiments, data  202  may be send to device  108  via a cable, e.g., a USB cord, or via a wireless route. 
     According to some embodiments, input device  108  may process the data received from detector  106  and calculate the density of material  114 . Input device  108  may transfer the calculated data to present a calibration graph and/or table on output device  110 , e.g., and determining the result density of material  114 . 
     Reference is now made to  FIG. 3 , which illustrates in  FIG. 3A  a schematic illustration of penetrating device  102 , and in  FIG. 3B  a schematic illustration of the angle of radiation transmission from penetrating device  102  to detector  106 . 
     According to some embodiments, as shown in  FIG. 3B , device  102  may include a hollow cylinder  306  to contain a radiation source  302 . 
     According to some embodiments, device  102  may include lead (Pb) coating  304 , surrounding cylinder  306 . 
     According to some embodiments, device  102  may operate in a first and a second operating modes. According to some embodiments, the in the first operating mode, radiation source  302  may be positioned essentially in the center of cylinder  306 . According to these embodiments, device  102  is not active, and a user of device  102  is relatively protected from potentially harmful radiation from source  302  since source  302  is contained within cylinder  306  and surrounded by Pb. 
     According to other embodiments, device  102  may operate at a second operating mode, wherein radiation source  302  may be positioned at a position  310 , e.g., at the end of cylinder  306 . 
     According to some embodiments, coating  304  may have one or more openings  308 , to enable the exposure of the radiation from radiation source  302 . 
     According to some embodiments, opening  308  may be at a predetermined angle (as explained for example, with relation to  FIG. 3B  and  FIG. 4 ), for example, aimed toward a detector, e.g., detector  106  ( FIG. 1 ). According to some embodiments opening  308  may be sealed, e.g., to prevent penetration of liquid into device  102 . According to some embodiments, opening  308  may be sealed using any suitable material including, plastics, carbohydrate complex materials and the like. 
     According to some embodiments, when device  102  is operating in the second operating mode, source  302  is positioned at position  310 , e.g., radiating radiation. 
     According to some demonstrative embodiments, as shown in  FIG. 3B , when device  102  is operating in the second operating mode, i.e., when source  302  is positioned at position  310 , source  302  may radiate towards detector  106 . 
     In some embodiments, device  102  is penetrating into a layer, e.g, an examined layer for which the density is to be measured, to the depth (H). According to some embodiments, detector  106  is positioned on the layer, e.g., on the surface of the examined layer, at a horizontal distance (x). 
     Detector  106  is positioned at a specific distance (x), to enable the effective receipt of outgoing radiation from source  302 , passing through the examined layer. According to some embodiments, opening  308 , may be at a gazing angle tangent, e.g., determined in light of depth (H) and detector  106  position—the ratio H/x. 
     According to some demonstrative embodiments, the angle may be at a range between 0-90 degrees. Preferably, the angle is between 20-50 degrees, most preferably 45 degrees, e.g., when the ration H/x is 1/1. The angle may optionally be 26.56 degrees when the ratio H/x is 2/1. 
     According to some embodiments, when the material examined is shallow, e.g., when the examined layer is thin, the angle may be 63 degrees, e.g., when the ration H/x is 1/2. Reference is now made to  FIG. 4 , which is a schematic illustration of an angle  402  of radiation from a radiation source to a detector, according to some demonstrative embodiments. 
     Reference is now made to  FIG. 5 , which illustrates a graph depicting the use of a LaBr 3 (Ce) detector with Co-60 radiation source inside Carnallite. Axis X depicts the Gamma radiation energy, whereas Axis Y depicts the counts accumulated during a time period of ten minutes. As shown in the graph, peaks  502   a  and  502   b  correspond to the Co-60 source and peak  504  corresponds to the existing K-40, e.g., from the environment. 
     Reference is now made to Table 1, listing the results of a sampling using a manual cylindrical sampler (e.g., a sampler by Eijkelkamp®) and a radiation sampler. The statistical analysis of the density measurement are shown in  FIG. 6 . according to some demonstrative embodiments described herein. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 No. of 
                 Average Density 
                   
               
               
                 Sampling method 
                 samples 
                 (gr/cm 3 ) 
                 Variance 
               
               
                   
               
             
            
               
                 Manual cylindrical sampler 
                 100 
                 0.768 
                 0.077 
               
               
                 Radiation Sampler 
                 100 
                 0.773 
                 0.081 
               
               
                   
               
            
           
         
       
     
     As shown in  FIG. 6 , the results of the radiation sampler are statistically equivalent to those of the manual cylindrical sampler. The results are in good agreement with respect to the average density measured, and exhibit a relatively small variance. It is to be noted that the variance between the samplers can be reduced via longer measurements and/or higher source activity. 
     Reference is now made to  FIG. 7 , which illustrates a calibration graph in accordance with some demonstrative embodiments. 
     The main purpose of the calibration graph in accordance with some demonstrative embodiments described herein is to convert and/or quantify, i.e., to provide visual graphical representation, the response of the radiation detector to the bulk density for an examined layer placed in between a radiation source and the detector 
     According to some embodiments, one of the purposes of the graph is to assist in obtaining a calibration equation, wherein the variable of the equation is the peak net counts (in 10 min) as read by the detector. The calibration equation enables to calculate the density of the examined material, e.g., Carnallite density. 
     In the laboratory we prepared. 
     The graph shown in  FIG. 7  demonstrates the counts from a detector versus the spatial density of a bulk in g/cm3 as measured in an experiment conducted in a laboratory. In the experiment several mixtures of carnallite grain types were prepared and some pound solution was poured onto the grains until saturation has occurred to provide different materials for examination. 
     This procedure was repeated several times, wherein in each case a different liquid-to-dry ratio was set 
     As shown in  FIG. 7 , point  702  was obtained in a pound solution, and points  704 ,  706  and  708  are from different carnallite grain types. The calibration line enables finding the density at each measuring point from the detector&#39;s reading after using a “daily correction factor”. 
     At the start of every new pound measurements, there is an initial 10 min solution reading, in order to obtain the “daily correction factor”. The “daily correction factor” takes into consideration the specific pound conditions (solution density, temperature), and the current source activity to consider the source half-life. The ratio of this solution reading to the one on the graph is defined as the “daily correction factor”. 
     It is possible to convert reading to spatial density by the graph by fitting, or/and setting point on the line, or/and by interpolation/extrapolation. 
     Analysis of the Example: 
     The spatial density of the carnallite in the bulk (called also “dry density”) is calculated using the following equation developed by K. Preiss (K. Preiss “Carnallite Density Measurements in the Dead-Sea Pounds”, Negev Institute For Arid Zone Research, October 1971 (In Hebrew)): 
         d   bulk   =d   s ( d−d   l )/( d   z   −d   l ) 
     Where: 
     d—the measured medium density (“wet density) 
     d l —the solution density 
     d s =1.6742 g/cm 3  the specific density of pure solid carnallite. 
     From the system measurements, it is possible to obtain the bulk carnallite density. 
     While this invention has been described in terms of some specific examples, many modifications and variations are possible. It is therefore understood that within the scope of the appended claims, the invention may be realized otherwise than as specifically described.