WO2000065603A1

WO2000065603A1 - A method of creating and concentrating high velocity alpha particles having two captured electrons

Info

Publication number: WO2000065603A1
Application number: PCT/US2000/004449
Authority: WO
Inventors: Jerome Drexler
Original assignee: Jerome Drexler
Priority date: 1999-04-23
Filing date: 2000-02-22
Publication date: 2000-11-02
Also published as: WO2000065603A8

Abstract

Methods for creating and utilizing of high velocity alpha particles accompanied by two captured electrons. The method uses a modification of the well-known Crockcroft and Walton experiment used to disintegrate lithium-6 or lithium-7 (21) into high energy alpha particles by bombarding the lithium with either high energy deuterons or protons (11) along with a beam of electrons (17). The created alpha particles having two captured electrons are capable of penetrating metals (25) and interacting with nuclei of atoms embedded or absorbed in metals.

Description

A METHOD OF CREATING AND CONCENTRATING HIGH VELOCITY ALPHA PARTICLES HAVING TWO CAPTURED ELECTRONS

TECHNICAL FIELD

The present invention pertains to atomic beams, and in particular to formation of a beam of high velocity alpha particles having captured electrons.

BACKGROUND ART

A valuable reference work providing background art relative to the invention is Nuclear and Particle Physics by W.S.C. Williams, Clarendon Press Oxford, 1991, particularly chapters 14, 13, and 11. In section 14.2, Big Bang Nucleosynthesis, it describes various nuclear reactions that began to take place 225 seconds after the Big Bang. The output of many of those reactions are alpha particles with kinetic energies of the order of 10 MeV. One of those nuclear reactions is:

Li⁷ + p α + + 17.35 MeV

Chapter 11 covers the subject of kinetic energy loss of charged particles by ionization of a metal's atoms by charged particles moving through the metals. The term "range" is defined as the distance moved by a charged particle through a metal before coming to rest. To determine the range for particular particles of a given energy, the number surviving various thicknesses of metal foils is measured. For alpha particles of energy up to tens of MeV, the survival rate is very nearly 100 percent until a certain thickness of a given material, after which the number of alpha particles drops to zero rapidly.

It is known that the ionization energy of the first electron removed from a stationary helium atom is 24.6 electron volts. When that electron is removed, it no longer partially shields the second electron from the two proton positive charge of the alpha particle nucleus and the second electron moves closer to the nucleus, resulting in an ionization energy for the lone electron of 54.4 electron volts.

In 1932, Cockcroft and Walton (they received the Nobel Prize in Physics for this achievement in 1951) conducted experiments which demonstrated experimentally that beams of protons, with kinetic energy of only

120,000 eV, are capable of breaking up the nucleus of the lithium atom and thereby creating two high energy alpha particles, according to the nuclear reaction:

Li⁷ + p —► + + 17.35 MeV

See Atomic Physics by Max Born, Dover Publications, Inc. 1969, page 71 and 73. Later experimenters disintegrated the lithium with protons down to less than 30,000 ev.

The two alpha particles are known to be emitted in opposite directions to satisfy the conservation of momentum law.

A closely related reaction involving lithium-6 and deuterium also can be achieved and produces even higher energy alpha particles :

Li⁶ + D —► α + α + 22.4 MeV It is an object of this invention to devise a method to create highly energetic electrically neutralized beams of alpha particles. The application for such highly energetic neutralized beams of alpha particles include penetration of metals and other materials, transferring kinetic energy to nuclei absorbed or embedded in metals by close-proximity scattering and penetrating nuclei to transmute atoms by adding alpha particles.

SUMMARY OF THE INVENTION

This object has been achieved with a method for creation of the sought after particles which uses a electron beam in a modification of the experiment of Cockcroft and Walton so as to allow electrons to be captured by the emitted 8.7 MeV or 11.2 MeV alpha particles. In the Cockcroft and Walton apparatus, which function in vacuum conditions, the number of bombarding protons greatly exceeded the number of protons leaving as part of the alpha particles, which comprise two protons and two neu- trons. This abundance of protons bombarding the lithium in the Cockcroft/Walton experiment prevent the electrons in the lithium-7 from attaching themselves to the departing alpha particles. By bombarding the lithium-7 sample with a beam of electrons as well as the beam of protons, with an electron flux exceeding the proton flux, an excess of electrons is created causing some of the departing alpha particles to carry with them one or two electrons. Similarly, a lithium-6 sample is used with a beam of deuterons and a beam of electrons bombarding the lithium-6 sample.

Captured electrons travel with the same high velocity as the alpha particles and therefore must fall through a much greater coulomb potential of the alpha particle than for the normal helium atom, whose nucleus is at rest. Therefore, the electron-alpha particle spacing is smaller than that for a helium atom. This closeness of the captured electron partially shields and neutralizes the positive charge of the alpha particle. When such a neutralized alpha particle bombards a metal sheet, its ionizing effect, and kinetic energy losses, are greatly diminished, allowing very much greater penetration into the metal sheet than possible by bombarding the same metal with ordinary alpha particles with the same kinetic energy.

To confirm that pairs of electrons have been captured by some of the alpha particles a detection method can be used which is based upon the difference in alpha particle penetration of a metal sheets located between the emitted alpha particles and a scintillation counter detector. A metal of a given thickness is selected such that only a small percentage of the ordinary alpha particles will pass through the metal sheets in front of the scintillation counter detector. The pene- trating particles can be detected using a scintillation counter such as a zinc sulphide scintillation counter.

An electron beam is then turned on and directed at the lithium target to neutralize the positive charges from the proton or deuteron beam and create an electron surplus. Some of the emitted alpha particles become neutralized by the tightly-bound captured electrons and pass through the metal sheets to be detected as a rise in particle count by the scintillation detector. The rise in the number of penetrating particles triggered by the electron beam flooding the lithium target with electrons is used to confirm the electron neutralization of the alpha particle positive charge. It should be noted that an ordinary helium atom bombarding the same metal sheets with the same kinetic energy would penetrate the metal sheets only slightly more than ordinary alpha particles, because the weakly-bound orbital electrons of atomic helium would be quickly stripped away from the alpha particle nucleus. It is known that for single electron atomic systems with a stationary nucleus that the Bohr classical physics approach yielded fairly accurate results. The Bohr energy states of the Bohr atom are derived for the hydrogen atom or single electron helium atom by setting the Coulomb attraction of the electron to equal the centrifugal force of the orbiting electron.

In the derivation of the energy states of the high velocity alpha particle-electron pair, relationships between velocities and energies are used, rather than equating the forces. For the high velocity alpha particle with an captured electron:

(1) The average linear velocity of the electron = the average linear velocity of the alpha particle.

That is, the electrons and alpha particles are traveling together at the same average velocity.

The kinetic energy of an electron, which has been accelerated by potential V is described by the fol- lowing equation, where eV is measured in electron volts. All of the kinetic energy of the electron is assumed to be derived from falling toward the positively charged alpha particle.

eV = 1 /2 Melectron V²electron

( 2 ) Thus , Velectron =

The kinetic energy of the alpha particle has no restrictions on it (essentially an independent variable) and is defined simply as Ealpha, measured in electron volts as Ealpha = 1/2 Malpha v²alpha and thus

(3) valpha =

equating the electron and alpha particle average linear velocities (2 ) and (3 ) as required by ( 1 ) we arrive at

, . . -,„ Melectron ----, Ealpha

( 4 ) eV = Ealpha =

Malpha 7344

This states that the energy of the captured electron, which is the same as the ionization potential, is equal to the kinetic energy of the alpha particle divided by 7344. This equation only accounts for the linear velocities and kinetic energies of the electron and alpha particle, but does not take into account the orbital kinetic energy of the electron. When the nucleus of a single electron helium atom is stationary its ionization energy is 54.4 electron volts, which should be added to the above equation to ensure that when the alpha particle kinetic energy falls to zero then eV equals 54.4 electron volts. For this case the electron can be con- sidered to have a helical orbit represented by equation 5.

(5) eV = ^^ + 54.4 7344 Equation (5) is very simple but very powerful in describing the many attributes of a high velocity alpha particle with a captured electron. Five of those attributes are described in the following five para- graphs. Paragraphs (a), (d) and (e) explain why normal absorption spectrum techniques would not be successful in detecting such neutralized alpha particles.

(a) The higher the kinetic energy of the alpha particle, the larger the coulomb potential that the electron must fall through to gain sufficient speed, so the electron must move closer to the alpha particle the greater the alpha particle kinetic energy, Ealpha. In the case of an alpha particle-electron pair with a kinetic energy of 11.2 MeV, the ionization energy or chemical binding energy of an electron to the alpha particle is about 1,525 plus 54 or 1,579 electron volts (which corresponds with an x-ray ionization energy wavelength of about 8 A⁰. ) and the distance of the electron to the alpha particle would be about the order of 4 x 10^"11 cm compared with the spacing of 2.64 x 10^"9 cm for the normal helium atom and about 1.2 x 10^"9 cm for a single electron helium atom. Thus, if there were a large number of identical alpha-particle electron pairs moving at the identical velocities they could be detected, theoretically, with x-ray quanta with a wavelength of 8 A° , which would ionize the electrons and thus x-ray quanta would be absorbed and thereby demonstrate an absorption spectra.

(b) Equation (5) holds for very high kinetic energies and velocities (v) of the two particles since for both Melectron and Malpha the masses vary with velocity as

(c) Equation (5) indicates at what kinetic energy of the alpha particle is the distance between electron and alpha particle one half of that for a helium atom with one electron that is in its ground state? The ionization energy of helium with one electron in its ground state is 54.4 electron volts. For this condition the ionization energy and kinetic energy of the electron would be 108.8 electron volts divided equally between the orbital energy and the linear energy. Therefore for the electron-alpha particle spacing to be halved, Ealpha = 7344 (54.4), or 400,000 eV. This means that to shield the alpha particle positive charge with an electron, the kinetic energy of the alpha particle must be very much greater than 400,000 eV so that the electron is much closer to the alpha particle than that in a helium atom. If such charge shielding is necessary, the preferred kinetic energy for a neutralized alpha particle would be in the range of 2 MeV to 11.2 MeV, with the higher end favored.

(d) The eV kinetic energy of the electron travelling with an alpha particle is the same as the ionization energy .

(e) If some captured electrons had some initial kinetic energy when they entered into the electric field of the alpha particles, their ionization energies would be different than for zero-kinetic-energy electron entries. These high energy alpha particles with two captured elec- trons have significantly different emission and absorption spectra than ordinary helium atoms.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view of apparatus of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Fig. 1 shows an apparatus under vacuum for creating alpha particles with a proton beam 11, with kinetic energy of greater than 30,000 eV and preferably between 80,000-160,000 eV, generated by a source 13 directed to the lithium target 21 according to the Cockcroft/Walton method. The apparatus further includes a scintillation detector 15 for detecting the alpha particles, an electron beam 17 from a conventional electron gun 19 emitting moderate energy, electrons, for neutralizing excess positive charge on the lithium target 21, and notches 23 for introducing metal sheets 25 be- tween the alpha particle source, i.e. the lithium target 21 and the scintillation counter 15. Lithium target 21 is a sheet of primarily lithium-7, although a sheet of primarily lithium-6 will also work if deuterons are substituted for protons. Lithium-6 and the deuterons are preferred because deuterons have a greater collision cross-section than protons and the created alpha particles from lithium-6 have a kinetic energy of 11.2 MeV compared to 8.7 MeV for those created from lithium-7. The preferred metal sheets for experimental work are aluminum foils ranging in thickness between 70-300 μm. Sheets of other metals can also be used if they can be made and handled yet thin enough so that at least three sheets would be required to reduce the scintillation count by about a factor of ten. Scintillation detector 15 comprises a material which scintillates upon alpha particle impact, a photomultiplier that produces a pulse of current for each scintillation, and an associated counter which counts scintillations. Initially, only the deuteron beam 11 is turned on to conduct the Cockcroft/Walton method for creating 11.2 MeV alpha particles, which emerge from lithium-6 target 21 in random directions, alpha particles directed toward the scintillation detector 15 are detected by the scintillation material and counted. The electron beam 17 is not yet turned on.

Sheets 25 of metal, perhaps aluminum 100 to 200 microns thick, are inserted in the notches 23 in the scintillation counter housing 27 to reduce the kinetic energies of the alpha particles. A number of aluminum sheets are inserted until the scintillation count is reduced to about ten percent of the initial scintillation counter reading.

The electron beam 17 is then turned on at a low current level, and the scintillation counter reading is checked. The current in the electron beam striking the lithium target is slowly increased so as not to damage the lithium target, which may be bonded to a heat sink for cooling. At some electron beam current level, the scintillation count will increase. This would imply that more alpha particles are reaching the scintillation detector, and the detection of neutralized alpha particles is confirmed. The electron beam flux should exceed the deuteron beam flux. The next two steps can be used for further confirmation.

An additional aluminum sheet is inserted, which should lower the scintillation count. When that happens, the electron beam current is raised to try to allow more of the generated alpha particles to capture electrons and thus cause greater penetration of the aluminum sheets and thus confirm the anticipated relationship between electron beam current and metal thickness penetration by the electron-shielded alpha particles. The above method distinguishes between (1) high kinetic energy normal alpha particles and (2) neutralized alpha particles with the same kinetic energy, accompanied by a pair of electrons by the differences in penetrating power of the neutralized particles versus the normal alpha particles and their respective ionization losses in metals. This method can be used to concentrate the alpha particles with two captured electrons.

One alternate way of separating a normal alpha particle from a neutralized alpha particle is to use a magnetic field transverse or orthogonal to the motion of the output alpha particles. A high velocity, positively charged alpha particle would be deflected much more by the orthogonal magnetic field than would the partially shielded alpha particle carrying one or two electrons. The orthogonal magnetic field would be in front of the scintillation counter, which would enable the scintillation counter to distinguish between a normal alpha particle and a partially or fully neutralized one. The magnetic field can be varied to adjust the beam deflection factor to an optimum level. This method can be used to concentrate the alpha particles with two captured electrons .

A second alternative way of separating normal alpha particles and single-electron alpha particles from fully neutralized alpha particles, in a vacuum system, is to pass them through a pair of defection plates with an electrical voltage across the plates. The fully- neutralized alpha particles would pass through unaffected while the two other types carrying positive charges would be deflected. This method can be used to concentrate the alpha particles with two captured electrons.

The high velocity neutralized alpha particle created by the methods described, can be used to pene- trate metals and other materials to a greater depth than normal alpha particles having the same kinetic energy. This comes about as a result of reduced ionization losses in the atoms of the metal or material being penetration and thus reduced kinetic energy losses of the penetrating neutralized alpha particles.

This enhanced penetrating capability of the neutralized alpha particles can be utilized to penetrate metals deeper, and/or to transfer momentum and kinetic energy by close-proximity Coulomb scattering to nuclei of atoms embedded or absorbed within a metal . In one example the metal is palladium and the absorbed atoms would be deuterium and lithium-6. The bombarding of this material by neutralized alpha particles could transfer momentum and a kinetic energy to the absorbed deuterons and lithium-6 nuclei by close-proximity Coulomb scattering thus raising their nuclei kinetic energies by more than 30 KeV and increasing the probability of some fusion reactions according to the equation:

Li⁶ + D → a. + + 22.4 MeV

Thus, the bombarding neutralized alpha particles triggered the creation of additional alpha particles. If excess electrons are available to neutralize some of these created alpha particles, by an electron beam or other means, the neutralized alpha particles could again transfer kinetic energy to the fuel nuclei by close-proximity Coulomb scattering and thereby create additional similar fusion reactions. Neutralized alpha particles with two captured electrons may be called "proto-atoms" of helium.

Another application for alpha particles neutralized by two electrons is to penetrate nuclei of atoms to transmute them to greater weight isotopes by adding alpha particles. Typically this technique would be appropriate for nuclei up to the size of the nucleus of iron. For nuclei greater in weight than that of iron the absorption of an alpha particle could create an iso- tope or possibly lead to disintegration of the nucleus. It is widely known that neutrons penetrate nuclei of atoms because they carry no electric charge and therefore are not repelled. A high velocity proto-atom of helium with a kinetic energy in the 5 MeV to 11.2 MeV range has its two electrons very close to the positive nucleus, thus shielding it well, thereby permitting it to penetrate nuclei of atoms.

Claims

1. A method of creating and concentrating high energy alpha particles having two captured electrons comprising: directing a beam of deuterons with a deuteron flux having kinetic energies ranging between 50,000 eV and 160,000 eV bombarding primarily lithium-6 target; and directing a beam of electrons at the said lithium-6 target with an electron flux exceeding the deuteron flux to create a surplus of electrons whereby the deuterons break up the nucleus of the lithium-6 atom, creating departing alpha particles according to the relation

Li⁶ + D → + α + 22.4 MeV

and some of the excess electrons on said lithium-6 target are captured by some of the departing alpha particles thereby forming alpha particles having captured electrons, passing the departing particles though a transverse magnetic field or electric field or a thin metal foil thereby concentrating high energy alpha particles having two captured electrons.

2. A method of creating and concentrating high energy alpha particles having two captured electrons comprising: directing a beam of deuterons with a deuteron flux having kinetic energies ranging between 50,000 eV and 160,000 eV bombarding a primarily lithium-7 target; and directing a beam of electrons with an electron flux greater than the proton flux, at the said lithium-7 target to create a surplus of electrons, the protons being capable of breaking up the nucleus of the lithium-7 atom according to the relation

Li⁷ + p → α + + 17.35 MeV

whereby some of the excess electrons on said lithium-7 target are captured by some of the departing alpha particles thereby forming some alpha particles having captured electrons, passing the departing particles through a transverse magnetic field or electric field or a thin metal foil thereby concentrating the high energy alpha particles having two captured electrons.

3. A method of transferring kinetic energy from high kinetic energy neutralized alpha particles having two captured electrons to nuclei of atoms absorbed in metals comprising: embedding or absorbing selected atoms in a metal sheet or foil, bombarding said metal sheet or foil with neutralized alpha particles having two captured electrons having kinetic energies primarily above 2 MeV, passing said neutralized alpha particles in close-proximity to said embedded or absorbed nuclei to permit coulomb charge repulsion of the nuclei, scattering of said nuclei by said neutralized alpha particles so as to transfer momentum and kinetic energy from said neutralized alpha particles to said nuclei of at least 30 KeV.

4. The method of claim 3 where the nuclei are nuclei selected from lithium-6, lithium- 7 and hydrogen, deuterium or tritium.

5. The method of claim 3 where the metal is selected from palladium, titanium and nickel .

6. A method of achieving penetration of nuclei of atoms with high kinetic energy neutralized alpha particles having two captured electrons comprising: embedding or absorbing selected atoms in a metal sheet or foil, bombarding said metal sheet or foil with said neutralized alpha particles having kinetic energies primarily above 5 MeV; passing said neutralized alpha particles in close-proximity to said embedded or absorbed nuclei, achieving penetration of at least a small number of said nuclei by said high kinetic energy neutralized alpha particles.

7. A method of separating moving alpha particles having two captured electrons from moving alpha particles having one or no captured electrons, comprising: creating a flux of moving alpha particles having one, two or no captured electrons; passing said flux of moving alpha particles through a transverse magnetic field so as to deflect those alpha particles with one or no captured electrons; and placing a target beyond said deflecting field which will be struck primarily by alpha particles with two captured electrons.

8. A method of separating moving alpha particles having two captured electrons from moving alpha particles having one or no captured electrons, comprising: creating a flux of moving alpha particles having one, two or no captured electrons; passing said flux of moving alpha particles through a transverse electric field so as to deflect those alpha particles with one or no captured electrons; and placing a target beyond said deflecting field which will be struck primarily by alpha particles with two captured electrons .

9. A method of separating moving alpha particles having two captured electrons from moving alpha particles having one or no captured electrons, comprising: creating a flux of moving alpha particles having one, two or no captured electrons; passing said flux of moving alpha particles through a combination of both a transverse magnetic field and a transverse electric field so as to deflect those alpha particles with one or no captured electrons; and placing a target beyond said deflecting fields which will be struck primarily by alpha particles with two captured electrons .