Abstract:
An apparatus for destroying bacteria is provided which includes a neutron generator and a target polymer film which will receive the impact of neutron emissions. Neutrons impacting the target film produce a second emission of high energy protons which are made to move through an electromagnetic field external to the neutron tube thereby accelerating and steering a generated proton spray. This embodiment is well-suited for treating physical locations known to be infected by pathogenic microorganisms.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to destroying pathogenic bacteria and harmful microorganisms. More particularly, the present invention relates to an apparatus and method for generating protons from a neutron tube for the purpose of killing pathogenic bacteria and other harmful microorganisms. 
     2. Description of Related Art 
     A bioterrorism attack is the deliberate release of viruses, bacteria, or other germs (agents) used to cause illness or death in people, animals or plants. There are three types of agents classified by the US government as bio agents: categories A, B, and C. Category A agents are high priority agents posing a risk to national security, can be easily transmitted and disseminated, result in high mortality, have potential major public health impact, may cause public panic, and require special action for public health preparedness. Category B agents are moderately easy to disseminate and have low mortality rates. Category C agents are emerging pathogens that might be engineered for mass dissemination due to easy production and dissemination or possessing the capability of inflicting high mortality rates and major health impact. 
     Four of the six bio agents classified as Category A are bacterium. Botulism toxin is one of the deadliest toxins known and is produced by the bacterium  Clostridum botulinum . Botulism supplies are readily available worldwide due to its cosmetic applications in injections. Bubonic plague is a disease caused by  Yersinia pestis  bacterium. Historically spread via rodent hosts, the disease is transmitted to humans by flea bites or by aerosol in the form of pneumonic plague in which form a weaponized threat could be deployed. Tularemia, or rabbit fever, is caused by the  Francisella tularensis  bacterium and although it has a very low fatality rate, can severely incapacitate its victims. Anthrax is another deadly form of bacteria,  Bacillus anthracis , classified as a Category A bio agent. 
     The three common methods used for removing bacteria and other harmful microorganisms are fumigation, liquid bleach, and ultraviolet-light. With respect to fumigation, acceptable results have been achieved using industrial scale chlorine oxide gas. Another effective fumigation agent includes CH 3 Br as described by Kolbe et al. Despite some effectiveness, however, fumigation has several disadvantages. For instance, fumigation requires evacuation of the premises, use of protective gear by all operators, and a relatively long time for application of product, dissipation of poisonous gas fumes, and post application cleanup. Comparatively, while the use of liquid bleach is less expensive, it is also less effective on porous surfaces. Furthermore, on items such as upholstery, papers, books, wood surfaces, using bleach not only decontaminates objects but it also destroys them. Further, liquid bleach generally results in a less complete coverage of a targeted site. Alternatively, radiating with ultraviolet light from x-ray equipment provides good coverage but is expensive and difficult for field use. Nonetheless, a large facility has been constructed by Ion Beam Applications in Bridgeport, N.J. for the purpose of treating US mail against the threat of anthrax at a cost of several millions of dollars. In addition to the expense of owning and operating such a facility, there is the time, expense, inconvenience and public safety hazard of shipping contaminated materials to a fixed facility for decontamination. 
     Even when treated by conventional methods, dormant bacteria in the form of spores can exist in the inert state for a very long time. Endospores ensure the survival of bacterium through periods of environmental stress. They are therefore resistant to ultraviolet and gamma radiation, desiccation, lysozyme, temperature, starvation, and chemical disinfectants. An endospore is a non-reproductive structure that forms when a bacterium produces a thick internal wall that encloses its DNA and part of its cytoplasm. This DNA is capable of surviving most conventional cleaning methods. 
     Beyond the conventional methods, several alternative methods of destroying bacteria have been proposed. For instance, atomic oxygen, O 15  and O 16 , are known to be very effective against bacteria and many uses have been described in the recent past. However, each of these devices is limited and cannot produce energetic ions. Further, the treatment generally leaves large scars or burn marks on the treated surfaces. 
     Use of ozone has also been suggested. A company, O3Co, in Idaho has developed a process for delivering a high concentration of ozone for destroying bacteria. This requires sealing up an area to be cleaned and an exposure time of sixty minutes. 
     A British Company, BioQuell, employs hydrogen peroxide for decontamination of hospital wards and patient rooms. The treatment is effective against walls, beds, furniture, medical equipment and various touch screens. However, the gas is corrosive, the equipment is expensive and the resulting water vapors necessitate a drying cycle. 
     The use of neutrons for killing anthrax spores is advocated by Liu and Wang. They employ a strong radioactive source  235 Cf to produce 10 12  neutrons per second in the 2.3 MeV range. Neutrons are significantly more effective in penetrating and destroying bacteria, however, the strong radioactivity of the source and its half-life of 2.3 years is a concern. The fielding of the radioactive source is also a great logistical burden to the user. 
     Carnegie Mellon researchers, Colin Horwitz et al, have described the use of a nano-catalyst composed of iron and tetra amido macrocyclic ligand (Fe-TAML) in a spray of sodium carbonate and bicarbonates, followed by an oxidizing agent, butyl hydro peroxide. This method is effective but it requires extensive cleanup after the treatment. 
     Still another method of killing bacteria is described by Ouellete (“Femtosecond Lasers Prepare To Break Out of the Laboratory” Physics Today, Vo. 17, No. 1, pages 36-38, January 2008.”) This method, however, is less effective at killing bacteria spread over large areas and it requires significant amounts of energy. 
     In the end, none of the prior art discloses an effective and efficient way to destroy  Bacillus anthracis, Staphylococcus aureus  or any other pathogenic bacteria or other harmful encapsulated nucleic microorganism. Therefore, a need exists to develop a novel alternative that can kill microorganisms without the drawbacks evident in the prior art. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to overcome the shortcomings disclosed in the prior art. To achieve this object, the present invention provides an apparatus for destroying bacteria which includes a neutron generator and a target jacket polymer film which receives the impact of neutron emissions. The target jacket film produces a second emission of high energy protons which move through an electromagnetic field external to a neutron tube and focus electrode which accelerate and steer the protons to generate a proton spray. This embodiment is well-suited for treating physical locations known to be infected by pathogenic microorganisms. 
     There are several advantages found in one or more aspects of the present invention over the prior art. For instance, the apparatus of the present invention can be quickly deployed directly to an infected location. Further, the present invention does not require the use of bulky shielding devices and gas masks. Additionally, the present invention is relatively inexpensive when compared to conventional large facilities currently in use to irradiate infected bulk items. 
     A further advantage of the present invention is that it provides a much higher kill rate of highly resistant pathogenic bacteria. Effectiveness is increased a hundred fold over the conventional use of chemical, liquid form bactericide in commercial use. Further, by inflicting kinetic energy damage to cell walls and cell interiors, the bacteria is destroyed while minimizing damage to other material. Still further, because the proton emissions from one or more aspects of the present invention can be focused, accelerated, and steered to the target areas, the present invention is highly effective against a wide variety of resistant bacteria and bacillus endospore. Residual neutron emissions can also aid in destroying encapsulated microorganisms. 
     The accompanying drawings, which are incorporated in and constitute part of the specification, illustrate various embodiments of the invention and together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an example of a neutron generator as known in the prior art. 
         FIG. 2  shows first preferred embodiment of the present invention. 
         FIG. 3  shows the first preferred embodiment of the invention directing radiation against a bacterial cell. 
         FIG. 4  shows a further preferred embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is hereby intended and further applications of the principles of the invention are contemplated as would normally occur to one skilled in the art to which the invention relates. 
       FIG. 1  generally illustrates an exemplary neutron generator configuration for use with the present invention. As shown, a neutron generator  101  generally includes a neutron tube  100  connected to an external high voltage power supply  104  via high voltage cables  102 . As further shown, such a neutron generator  101  may generally include a control console  106  connected to the neutron tube  100  via control cables  108  which allow an operator to adjust the operating parameters of the neutron tube  100 . In operation, neutrons are produced by the neutron generator  101  creating deuterium ions and accelerating those ions into a target that contains tritium or deuterium. The deuterium-tritium reaction is used only in special circumstances because although the neutron yield from the deuterium-tritium reaction yields approximately 100 times more neutrons, the energetic neutrons from deuterium-tritium reaction are less effective in neutralizing bacteria. Example reactions which take place in the neutron tube are: D+ 2 H yields n+ 3 He, E n =2.5 MeV and D+ 3 H yields n+ 4 He, E n =14.2 MeV. Neutrons produced from the D-T (D+ 3 H) reaction are emitted uniformly in all directions from the target. Neutron emissions from the D-D (D+ 2 H) reaction is slightly peaked along the axis of the ion beam direction. In both cases, a He nucleus (α particle) is emitted in the exact opposite direction of the neutron. The neutron tube  100  which encloses the ion source, ion optics, and accelerating electrode is preferably a vacuum tight metal housing which employs heavy duty dielectrics to insulate the high voltage elements of the tube. 
     With reference now to  FIG. 2 , a cross sectional view of an exemplary neutron tube  100  for use with the present invention  200  will be detailed. As shown, a neutron tube  100  may include a Penning ion source  220 , a deuteron gas supply  222 , a heating element  221  a permanent magnet  218 , a source cathode  224 , an ion source anode  202 , a deuteron ion exit  204 , an accelerating electrode  216 , a deuteron entrance  205 , a dielectric insulator  206 , a deuterated target  208 , a vacuum  213 , neutron tube top  234 , a poly methyl methacrylate (PMMA) or polyethylene absorptive jacket  210 , a second target  228 , a proton accelerating electrode  232 , and a proton exit  230 . According to a preferred embodiment of the present invention, the second target  228  is preferably comprised of poly methyl methacrylate (PMMA) for producing high energy protons. Alternatively, the second target  228  may be comprised of a thin sheet of polyethylene for producing high energy protons. 
     With reference now to  FIGS. 2 and 3 , the preferred method for use of the present invention will now be discussed. In operation, the neutron tube  100  generates ions from Penning ion source  220  which is a low gas pressure cold cathode ion source. The ion source anode  202  is preferably at a positive potential, either direct current (dc) or pulsed with respect to the source cathode  224 . The ion source voltage is preferably between 2 and 7 kilovolts. A magnetic field oriented parallel to the source axis is produced by permanent magnet  218 . The gas pressure in the source is regulated by heating  221  and the reservoir element  222 . A plasma is formed along the axis of the anode  202  which traps electrons which in turn further ionizes gas in the source. The ions are extracted through an exit cathode  204 . Under normal operation, the ion species produced by the Penning Source  220  are preferably over 90% molecular ions. 
     Ions emerging from the exit cathode  204  are accelerated through the potential difference between the exit cathode  204  and the accelerator electrode  206 . Preferably, the exit cathode  204  is at ground potential and the target is at a high (negative) potential. The accelerating electrode  206  is preferably 100-200 kV (negative) with respect to the exit cathode  204 . The ions pass through the accelerator electrode  206  and strike a deuterated target  208 . A vacuum envelope  213  insulates the high voltage activity in the neutron tube  100 . To deliver maximum flux to a sample, the neutron tube  100  is preferably operated with the deuterated target  208  grounded and the source floating at high (positive) potential. The accelerator voltage  216  is preferably between 80-180 kV, meaning the polarity of the deuterated target  208  with respect to the ion source can be changed from negative to positive depending upon neutron beam properties. 
     Thereafter, the accelerated deuteron ions strike the deuterated target  208  emitting 2.5 MeV neutrons in the D-D reactions or 14.5 MeV neutrons in the D-T reaction. The deuterated target  208  is preferably a thin film of metal such as titanium, scandium, or zirconium which may be deposited on a copper or molybdenum substrate. Titanium, scandium or zirconium form stable chemical compounds called metal hydrides when combined with hydrogen or its isotopes. These metal hydrides are made up of two hydrogen (deuterium or tritium) atoms per metal atom and allow the deuterated target  208  to have extremely high densities of hydrogen maximizing the neutron yield of the neutron tube  100 . The gas reservoir  222  also uses metal hydrides as the active material. Preferably, the neutron tubes  100  are designed such that the gas reservoir element  222  and the deuterated target  208  each incorporate equal amounts of deuterium and tritium. 
     As discussed above, the target  228  is preferably comprised of poly methyl methacrylate (PMMA) or polyethylene. The high hydrogen content of these polymers, acts as an abundant source of protons. When high energy neutrons from the neutron tube  100  impact the hydrogen atoms in the polyethylene target or PMMA target  228 , protons are displaced from the material transferring all of the energy of the neutrons to the ejected protons. A second accelerator electrode  232  may be used to control the speed of the proton spray. In this way, protons can be focused, accelerated, and steered. 
     With respect to the energy of the proton spray, since the neutron can impact the proton at any angle, the energy of the recoil proton will vary from 0 to 2.5 MeV with an average of 1.25 MeV. The proton after traveling several inches in the air is capable of penetrating almost 50 microns in depth and destroying layers of  Bacillus anthracis  or  Staphylococcus aureus  which are roughly the size of one micron. 
     The absorptive thick layer of hydrogenous material  210  or neutron absorbing material assist to stop or convert neutrons traveling backwards or sideways. Neutrons that are not converted into protons, having a forward bias, though not as effective as protons, may exit via proton exit  230  and thereby also assist in destroying bacteria. 
     Now with reference to  FIG. 3 , the operation of the proton source  200  is further illustrated. As shown, ionizing radiation  306  penetrates a physical barrier  310  (such as cloth or other covering) before penetrating cell wall  302  and breaking the DNA bonds  304  thus eradicating pathogenic bacterium. Each 1.25 MeV proton generated by the interaction of the 2.5 MeV neutron and hydrogenous PMMA target film  228  or polyethylene target film  228  will deposit approximately 0.06 MeV (1 MeV=10 −13  J) in a cell. However, only a small fraction of this energy or 0.1155 gray unit (Gy) is absorbed by the bacterium (1 Gy=1 J/kg) with 1000 Gy considered a lethal dose. Accordingly, 1000 Gy of energy will be deposited in each bacterium using the neutron generator of the present invention which preferably generates 10 10  neutrons/second. 
     According to a third preferred embodiment of the present invention, the target film  228  may alternatively be comprised of a thin layer of U 235  deposited on a thin metal like aluminum as a target film. The bombardment of neutrons on U 235  aluminum substrate target film jacket will produce spontaneous energetic fission fragments which upon impact will also destroy highly resistant bacteria and bacillus endospore. This aspect of the invention also requires thermilization of neutrons. 
     According to a fourth preferred embodiment of the present invention, the target film  228  may alternatively be comprised of a thin layer of boron incorporated on an aluminum or copper substrate. The bombardment of neutrons on a boron/aluminum substrate target film or a boron/copper substrate target film will produce alpha-particles at 2.4 MeV which upon impact will also be highly effective in destroying highly resistant bacteria. This aspect of the invention also requires thermilization of neutrons. 
     With reference now to  FIG. 4 , a further example of the present invention is provided. In this example, a plurality of proton sources  402  are arranged and operated as one unit  400  from a control console  410  connected by reservoir cable  408 . The plurality of proton sources  402  are powered by a sufficient high voltage power source  404  connected by high voltage power cables  406 . This configuration may apply a larger coverage of protons effective in a larger target location. The neutron absorptive collar  401  would provide a uniform barrier which would absorb neutrons traveling in a direction other than a forward bias. 
     In addition to killing pathogenic bacteria, the present invention may also be applied to basements and carpets in order to destroy mold and fungus. The present invention may also be adapted for use in water purification systems and pasteurization processes. 
     As detailed herein, the present invention provides a reliable, lightweight, and relatively inexpensive means of eradicating deadly pathogenic bacterium such as  Bacillus anthracis  and  Staphylococcus aureus  and provides a more effective rate of kill than ultraviolet light, x-rays, or gamma rays. Furthermore, the present invention is able to consistently produce high yields of energetic protons from benign materials such as polyethylene and poly methyl methacrylate which significantly reduces the effects of radiation exposure when compared to the strong radioactive sources such as Cf 235  currently employed in neutron production. 
     While the above description contains much specificity, these should not be construed as limitations on the scope, but rather as examples. Many other variations are possible. For example, an embodiment of the proton source with an external electromagnetic field may be devised to focus a diverging beam of protons on an infected area. Still further, the present invention could include an external electromagnetic field devised to steer the proton beam for wider coverage of a target area by allowing the proton beam to move rather than the apparatus. As described above, adaptation of the present invention for use in water purification systems, pasteurization processes, and mold and fungus treatments are also alternative embodiments of the invention. Accordingly, the scope should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.