JPH02207445A - Positron microscope system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates generally to microscopy devices of the type that use submetallic particles in imaging processes, and in particular to transmission microscopy systems in which a low energy or slow positron beam is employed. and a re-emission positron (e.) microscope device.

[Problems to be solved by conventional technology and invention]

Over the last millennium, due to advances in technology, typically 10'e
Although it has become possible to generate a low-energy (about 1 eV) positron beam from an initially high-energy positron emission source with an intensity of about . It is the opinion of those skilled in the art that the development of an effective positron microscope device is not feasible due to the weak positron beam and low current density available. This is in sharp contrast to the ease of generating an electron (e-) beam with a flux strong enough to form a visible image. Such e-beams are easily generated, for example from heated tungsten filaments, are of high quality, and are of tens of microamperes (1015e-/sec) f.
) has a current value.

Current slow positron source means have low current densities, and while the beam quality is being improved to meet the requirements for forming high-quality images, the beam output flux is at least 103 The following are the causes of this decline:

1.S A set of electron focusing lenses is required between the radiation source and the sample to be examined, so as to generate a very narrow, well-collimated beam. This focusing reduces the beam intensity by a factor of ten.

2. After the beam interacts with the target, another set of electron lenses selects a very narrow pyramid of the emitted beam to form a high-contrast, high-resolution image. With such an angle selection, the speed can be increased by an additional 100 min.
suffer the loss of becoming

3. Finally, the beam is expanded and projected onto a detector. Since the size of the detector is limited, this magnification (M
) process also causes losses that increase as a function of M2. Therefore, for an electron radiation source, it takes approximately 10
12e/sec is available, whereas in the case of positrons it is clear that at most only 104e/sec is available.

The human eye, under the best possible conditions, is capable of detecting images produced by beam current densities as low as 1Q8e-/c2-118C incident on the phosphor screen. Using currently available image intensifiers in combination with computer-based signal averaging techniques, 10'
It is possible to detect images with low density of e-/cw+2-sec or less. iii When the microscope is set to the lowest possible effective magnification within its usable range, the above-mentioned positron beam is 1
05e◆/C intestine will have a current density of 2-sec. This is almost an order of magnitude lower than values typically used in high-resolution, low-dose electron microscopy, and is one of the main reasons why positron microscopy is considered unfeasible.

The importance of positron microscopy equipment in the art becomes clear by understanding the manner in which positrons interact with matter. When a positron is injected into a material, several interactions occur between the injected positron and the medium into which it is injected. Positrons may be scattered more than once, backscattered out of the medium, or cause the emission of secondary electrons. If the medium is thin enough and the positrons have sufficient energy, the positrons will completely penetrate the medium.

In the transmission mode of operation, no significant physical events are expected to occur at low magnification during operation of the transmission positron microscope. This is because the fundamental interaction involved in removing positrons from a transmission electron microscope beam is essentially the same as the fundamental interaction involved in removing electrons from a transmission electron microscope beam. On the other hand, the study of diffraction patterns obtained from thin samples could be carried out in a similar way to the study of diffraction using a transmission electron microscope. Diffraction patterns such as 7 are different from the corresponding electron diffraction patterns, especially at energies below LOKeV.

In addition, the positron beam of the present invention is spin-polarized, and the beam intensity is reduced by a factor of five, but it must be possible to take advantage of the fact that polarization as high as P-0.7 is possible. , which must enable polarized low-energy positron diffraction (PLEPD) in transmission mode, which is most commonly used to generate slow positron source means emitted from nuclear beta decay of radioactive isotopes. The populations of high-energy positrons that are generated become spin-polarized themselves as a result of the weak interactions that generated them. The spin polarization of the high-energy positron is maintained while the positron decelerates in the slow positron moderator. As a result, the slow positrons emitted from the moderator are also spin-polarized. Slow electrons can be accelerated and focused to form a spin-polarized beam. By placing a low atomic number absorber between the source of high energy positron radiation and the moderator, the degree of spin polarization of the slow positron source means can be adjusted. The absorber is based on the principle that the low-energy part of the source spectrum (starting at a few +KeV) that experiences a low level of spin polarization as a result of weak interactions is stopped in the absorber rather than in the moderator. It works. Only positrons that are spin-polarized to a high level in the source spectrum and have initially high energy pass through the absorber and reach the moderator, so that the slow positrons generated by the moderator are It is spin-polarized at the same level. The direction of spin polarization of the obtained positron beam can be controlled by appropriately applying an interlinkage electrostatic field and an interlinkage magnetic field. Polarized positron microscopy as a complement to the recently developed polarized electron microscopy should provide information on exchange interactions and other spin polarization phenomena.

The interactions described above occur with both positrons and electrons, but because positrons are antimatter, they have some properties that make them susceptible to types of interactions that they do not share with electrons. For example, a positron combines with an electron to annihilate a single particle, and each has an energy of about 511,0000eV (E
emit two gamma rays having the same polarity (mo2) in substantially opposite directions. Alternatively, the positron captures an electron to form a hydrogen-like positron-electron bond state called positronium (Ps). PS atoms are usually 1 depending on the medium
After a characteristic Ps lifetime, which is 3 nanoseconds long, it annihilates in the medium as two or three gamma rays. or,
Ps escapes from the medium and may exist in vacuum with a lifetime of 140 nanoseconds.In addition to the case of 0 or more, the positron may stop within the medium and slowly advance (diffuse) to the surface of the medium. , in which case positrons can be ejected from the medium by an electric field whose largest surface is in a vacuum. This surface electric field, also known as a work function, normally pulls electrons back into the medium, but can act to repel positrons from the medium.

The phenomenon of emitting slow positrons from a medium is known as "slow positron emission" and this phenomenon forms the basis of slow positron source means generation.

In some respects it is similar to the process of field emission.

In addition to the above, positrons injected into the medium may become trapped in defects, where positively charged atoms are absent. The positrons exist within the defect for a lifetime determined to some extent by the defect's size, charge, and other characteristics, and then disappear.

Therefore, positron microscopy equipment can be expected to produce images resulting from at least four phenomena: annihilation, positronium formation, slow positron emission, and defect trapping, which cannot be obtained with electron microscopy.

Despite the differences noted above, there are significant similarities between electrons and positrons, and the ways in which microscopy is performed using these particles. Now, to describe an electron microscope apparatus, an electron microscope can take different forms, such as a transmission electron microscope (TEM), a reflection electron microscope (REM), and the like. These two types apply a scanning process to image a relatively large area at high magnification.

TEM operates by passing a high-energy (20 KeV to 1 MeV) electron beam with a diameter as small as 10-5 meters through a thin slice of the material to be examined.

During the beam's transmission through the sample, different parts of the beam are strongly scattered or blocked from the beam. The degree of scattering depends on the vibrations in the composition of the target.

After transmission, the beam, which initially had a -like distribution, now has regions of low intensity, where the sample preferentially excluded electrons from the beam, and regions of high intensity, where the sample and the beam had little interaction. Immediately after transmitting through the sample, the difference in relative intensity between the low-intensity region and the high-intensity region is called the image contrast.
The beam and its image information are contained within the original 10-5 meter beam diameter, and the image size is determined by various features of the sample that give rise to regions of high and low intensity. It is the same as the size of the section. This narrow beam propagates close to a series of powerful electron lenses.

This electron lens, usually a magnetic field, increases the diameter of the beam by 10-
It is applied to expand from 5 meters to several meters. With this electronic lens, it is possible to obtain a maximum magnification of 106 times. Therefore, most of the outer edge of the beam is lost during the expansion process. The expanded high-energy electron beam then impinges on a phosphor screen, where the kinetic energy of the electrons is converted into light to form a light image. In this case, regions of high intensity correspond to areas where the predetermined feature is not present. At this point, the diameter in the sample is 1
The (IGic■) feature appears on the phosphor screen as a dark area with a diameter of 0.1 m, which is the size that can be seen by the human eye.

The ability to distinguish small features in an image is called the "resolution" of an electron microscope.In the case of feature 1 mentioned above, the resolution of the microscope is 1, J [as a rule, if the magnification and beam current density are high enough, Features of any size can be resolved into each other. However, in practice, quantum mechanical effects limit the resolution of electron microscopy to distinguish features of about 1 from each other.

Another phenomenon that appears in TEM is diffraction. This effect is quantum mechanical in nature and arises from the wave nature of the particles involved. In a sense, the single diffraction effect can be said to be similar in quality to the ripples produced when two waves cross each other on a pond. The ripples of the incident electrons interact with the different ripples of the electrons in the sample, and the different molecules that interact with each other to form extremely regular ripples consisting of high and low transmittance ripples, respectively. It has a unique diffraction pattern that allows molecules to be identified in the same way. Thus, diffraction patterns can be used to identify the composition of a given sample. A diffraction pattern is also susceptible to changes in the chemical bonds of one molecule to another, the orientation of any crystal planes that may be present in the sample, and any types of defects in the sample.

A reflection electron microscope (REM) also has a magnifying optical system like a TEM, but its optical system is...

Magnify the image obtained from electrons scattering backwards from the original beam direction. Those electrons are primarily generated from two processes and include (1) elastically backscattered electrons that retain high energy and (2) secondary electrons that are emitted with an energy of about 30 volts. Since the energy of electrons is low, TEM is used to form images from secondary electrons.
Detection methods often differ from those used in

Because the fundamental phase effects involved in the generation of the two types of electrons are different, the images formed from the emitted electrons highlight different features of the sample. Backscattered electrons are primarily generated from the nuclei of atoms, while secondary electrons are generated by interaction with electrons within the medium. Therefore, complementary features can be directly compared.

The advantages of performing electron microscopy in reflection mode are:
The basic point is that there is no need to make thin slices of the sample in order to form an image. including targets that may be destroyed by slicing.
A wider range of targets can be studied using REM. Such targets include, for example, integrated circuit chips.

Particularly effective images are obtained when secondary electron-based imaging is combined with scanning techniques. There must be no difference in wood quality between the structure of the deflection plate of a scanning electron microscope and the structure of the deflection plate of a scanning positron microscope.
It consists of pairs of parallel, independent plates, each pair rotated 90° relative to each other. One pair controls the X position of the beam and the other pair controls the Y position of the beam.

The x,y position of the beam is controlled by applying varying electric fields to the two pairs of plates. The plate is placed as the last element of the electron optics before the beam hits the target.

In this mode of operation, a very narrow beam, typically with a diameter on the order of 10-8 meters, is swept along the surface of the target by an electrical deflection plate. A secondary electron current is detected as the beam sweeps over the target, and an image is formed from the changes in the current as a function of position. The combination of scanning techniques allows the use of low energy (less than 1000 volts) electron beams, which reduces the amount of damage to the specimen and reduces the time required to inspect each specimen.

It is therefore an object of the present invention to provide a positron microscopy device.

Another object of the present invention is to provide a positron microscopy apparatus that utilizes slow positron source means.

It is also an object of the present invention to provide a positron microscopy apparatus that employs positron deceleration techniques to enhance the brightness of a high-energy positron-emitting source.

Another object of the present invention is to provide a positron microscopy apparatus that employs computer image analysis techniques.

Furthermore, it is an object of the invention to provide a positron microscopy device that is capable of imaging in a backscatter mode of operation, ie in reflection mode.

Yet another object of the invention is to provide a positron microscopy device capable of imaging in transmission mode of operation.

Another object of the present invention is to provide a positron microscope apparatus that can use an electron lens optical system.

Yet another object of the invention is to provide improved electron lens optics for use with decelerated positron beams.

Yet another object of the invention is to provide a positron microscopy device that can perform imaging using a beam with low current density.

Yet another object of the invention is to provide an apparatus for multiplying current density to form a visible image.

Another object of the present invention is to provide a positron microscope apparatus that utilizes the phenomenon of slow positron re-emission to form an image.

Furthermore, another object of the present invention is to provide a positron microscope apparatus that utilizes the phenomenon of positron annihilation to form an image.

Another object of the invention is to provide a positron microscopy device that utilizes the phenomenon of positronium formation to form an image.

An additional object of the present invention is to provide a positron microscopy device that utilizes the phenomenon of defect trapping to form an image.

Yet another object of the invention is to provide a slow positron accelerator with high contrast and resolution.

Another object of the invention is to provide a positron microscopy device capable of forming spatial images.

Yet another object of the invention is to provide an apparatus that can be used to study electron momentum and the distribution of electron momentum.

It is also an additional object of the invention to provide a device that can be used to form a spatial image corresponding to the distribution of electron momentum.

Yet another object of the present invention is to provide a positron microscopy device that utilizes positronium atoms to form images.

An additional object of the present invention is to provide a positron microscopy device that utilizes gamma rays generated as a result of positron annihilation to form an image.

Yet another object of the invention is to provide an apparatus that utilizes spin-polarized positrons to facilitate diffraction studies.

It is also an object of the present invention to provide a positron microscopy device that can generate correlated images using transmission and reflection modes of operation simultaneously.

Yet another object of the invention is to use spin-polarized positrons to form images.

[Means for solving problems]

The above and other objects are achieved by the present invention, which provides a positron microscopy device for forming a magnified image of a sample target. According to one embodiment of the present invention, the novel positron microscopy device provides a A slow positron source is provided that generates a positron source beam formed from positrons. A focusing arrangement is provided to focus the positron source beam and direct low energy positrons of the positron source beam to a sample target.

Furthermore, the single particle image enhancement arrangement forms an image in response to a target beam formed from low energy positrons in a positron source beam that in this embodiment is transmitted to the other side of the sample target.

Using the type of microscopy achieved by slow positron transmission, slow positrons on the other side of the sample target would be able to illuminate the thin, highly homogeneous, single-crystal sample that constitutes the sample target. generated and released in the form of a narrow cone. Placing a microscopic sample, such as a virus, on top of the crystal can prevent or reduce the emission of 5 slow positrons. Viruses therefore appear as dark areas in images obtained in response to slow positron flux. A major advantage of using slow positrons for performing imaging is that they exhibit a relatively narrow energy spread compared to electrons. As a result, a high contrast, high resolution image can be obtained.

In one embodiment of the invention, an objective lens and a subsequent projection lens focus the target beam into a single particle image enhancement arrangement that includes a target plate that receives the target beam. The target plate is
In response to the target beam being struck, each positron in the beam releases a large number of electrons. Further, the display plate supports the phosphor layer in a substantially planar configuration and substantially parallel to the target plate. The phosphor of the phosphor layer interacts with a number of electrons emitted by the target plate to generate a number of photons corresponding to each electron.

According to an important aspect of the invention, the slow positron source includes a positron moderator that generates low energy positrons, the positron moderator receives high energy positrons, and the positron source is formed from slow positrons as described above. A thermalization device responsively generates a beam.

In one particular embodiment of the invention, the thermalization device is formed from tungsten (W) and cooperates with a high energy positron source. In this embodiment, the high-energy positron source is arranged above a window located between the positron source and the thermalization device. In a practical embodiment of the invention, the high-energy positron source is The window can be formed from Ti. This allows the high-energy positrons emitted by the high-energy positron source to propagate through the window means and thermalize? T! Contact l. The thermalization device may be configured as a plurality of vanes arranged substantially parallel to the direction of travel of the positron source beam.

In another embodiment of the positron microscopy device, a positron source beam bending arrangement is further provided for bending the positron source beam. It is not necessary to position the positron microscopy apparatus on a perfectly straight axis; in fact, the positron source beam must be positioned so that the beam is out of the path of stray radiation emitted by the high-energy positron source used to generate the source beam. It is advantageous to bend the The objective lens is used to focus the target beam, and the contrast aperture controls the size of the seven perias of the target beam.

In a transmission positron microscope embodiment of the present invention, a slow positron source and a brightness level enhancement arrangement are placed on opposite sides of a sample target from each other. Therefore, an image is formed from the positrons transmitted through the sample target. Additionally, in such embodiments, another single particle image enhancement device may additionally be provided that is arranged to receive secondary electrons returned from the sample target in a direction generally toward the slow positron source. This separate single particle image enhancement device also allows reflection microscopy imaging at the same time, facilitating imaging and comparison of complementary features.

In embodiments of the reflective positron microscopy apparatus of the present invention, the slow positron source generates a positron source beam formed from low energy positrons, as described above. Additionally, a focusing arrangement is provided for focusing the positron source beam and directing low energy positrons of the positron source beam to the sample target. However, in this embodiment of the invention, the single particle image enhancement device is imaged in response to a re-emitted beam formed from low-energy positrons that are re-emitted by the sample target in a direction generally toward the slow positron source. form.

Re-emitted slow positrons are very sensitive to the surface properties of the sample target and are therefore very advantageous from an imaging standpoint. The surface of the sample target has a thickness approximately equal to the first few electron layers, usually 1
It is thought that it is two layers (101 am) from . In photoemission microscopy, this phenomenon can be observed in tens of l10-8
This is in contrast to known methods of forming images from photoelectrons generated by primary particles at a depth of C. Therefore, photoelectrons are less sensitive to surface properties than positrons as they exit the sample target. The high surface sensitivity of re-emitted slow positrons makes it possible to newly observe thin film phenomena such as biological cell walls and dielectric interfaces. Furthermore, the emission of slow positrons is also believed to sense the presence of a defect by trapping at least one positron in the defect on the surface of the sample target and annihilating it there. If a positron were to become trapped in a defect, it would appear as a dark spot in the image (where there are no annihilated slow positrons), which could be usefully used, for example, to scan integrated circuit chips. A lens focuses the re-emission beam, and an accelerator located between the sample target and the objective accelerates the positrons in the re-emission beam.

In practicing the present invention, the single particle image enhancement arrangement used to enhance the brightness of a display in response to incident particles includes a target plate that receives the incident particles.

The target plate emits a large number of electrons in response to incident particles. Those electrons are accelerated toward the phosphor, which interacts with the large number of electrons emitted by the target in a manner that results in the emission of light. moreover,
A display plate is provided that supports the phosphor in a substantially planar configuration and substantially parallel to the target plate.

As previously mentioned, a single particle image enhancement arrangement is provided with an accelerator that accelerates a large number of electrons emitted by the target plate in a direction toward the display plate. In one particular embodiment, the accelerator has a predetermined amplitude and amplitude for attracting a large number of electrons toward the display plate and causing at least a portion of the emitted large number of electrons to communicate with the phosphor. A power source is associated with the display plate to apply a polarized voltage to the display plate.

In another embodiment of the invention, a memory is further provided for storing an image formed in the vicinity of the display plate in response to the interaction of the emitted electrons with the phosphor;
This may be a computer memory; the image analysis device that analyzes the data stored in the memory operates based on the data stored in the memory. In some embodiments of the invention, the collection of images is This is done by a video system.

Such image collection may be required in embodiments of the invention where the current density of the display plate is too low to directly observe the image.

Regarding the electron multiplier of the present invention, the image enhancement apparatus utilizes a two-plate channel electron multiplier array (CEMA) and associated image storage and analysis electronics system. In some embodiments, the CEMA system is 10e-7cm2-5ea.

This enables image formation even at low current densities. CEMA
produces an electron cloud of about 108 electrons for each particle that collides with it. When accelerated onto the phosphor screen, this electron cloud multiplies the light output of a single particle by a factor of approximately 106, so that each individual particle can be visually detected.

In practice, channel electron multiplier arrays are thin (0,8 m
Maro) A piece of lead glass that runs through its thickness about 1
06 with a 10 uLm diameter channel. Each channel has a length-to-diameter aspect ratio of 80:1. The open debt area of the sheet is 50% open. That is, the channels occupy 50% of the surface area of the sheet. The lead glass is heat treated in a reducing atmosphere to give the surface of the channel a secondary electron emission probability greater than 1 to enable electron multiplication. This multiplication occurs after applying an electric field between the front and back surfaces. When a charged particle hits one side, it releases a secondary electron, which is pulled downward by the electric field along the channel until it reaches the surface, where it releases possibly two more electrons. do. after that,
Those secondary electrons are further accelerated until they collide with another surface, where they each release two more electrons. This process continues until approximately 5X103 electrons are emitted from the back side of the channel electron multiplier array for each incident charged particle. Approximately 3X107 from the rear end of
electrons are emitted. When three plates are used together.

The gain will be approximately I x l 08. This is the ultimate limit of gain because of the spatial saturation of the channel. Systems of this type work equally well in environments where the incident particles are positrons.

A low light level video camera device is positioned to receive the images formed by the CEMA system. This video camera may be a DAGEMTi 65 low brightness video camera, the output of the video camera is an analog camera signal in binary digital form, ie.

Digitizer board converting to 0=no event, l=event form, e.g. ChorusData Sys
It is sent to a digitizer board sold by TEMS. The digitized information is analyzed by a signal averaging device that forms an image from the side flashes, and Nu
In some embodiments of the present invention, such averaging is applied to a suitable memory location on a high-resolution (512 x 512 pixel) graphics board, such as those commercially available from NeCorporation.
It takes place over a period of 8 hours. The resulting information is displayed on a high resolution monitor such as an Apple IIE monitor. The host computer for the digitizer board and graphics board may be an IBM PC, and the video signal from the camera may be stored on a conventional video cassette recorder system.

Scanning of the sample target with the positron source beam is performed using an electrostatic polarizer. In some embodiments of the invention where the positron source beam is very narrow, such scanning provides the advantage that the target beam only needs to carry amplitude information. The light spots formed on the phosphor screen by scanning can thus be stored as amplitude values in a memory, in which image accumulation is carried out.

According to yet another aspect of the invention, it is possible to apply a positron microscopy device to electron momentum distribution. It is known that two gamma rays are generated when a positron annihilates with an electron. Due to the law of conservation of momentum, gamma rays are emitted exactly 180' apart.

However, since the momentum of the electrons in the medium is small, the angle formed by the gamma rays changes slightly. This change is necessary to enable conservation of momentum, and when the momentum of the electron is Pe, and the mass of the electron and the speed of light are m and c, respectively, it corresponds to P e / m c. Electron momentum changes in the sample target as a function of material composition, crystal structure, and many other factors, and such changes are represented by the angular distribution of annihilation gamma rays.

That is, when a positron decelerates (thermalizes) to KT in a material, several different phenomena occur. The positron diffuses 10-8 to 10-7 meters towards the surface and is emitted out of the material as a re-emitted slow positron due to the surface work function at the surface, if it is negative. Thermalization is the process that high-energy positrons emitted from a radioactive source undergo when they enter a moderator. After entering the moderator, the initial energy of the positron is 1/4
It is lost through a series of inelastic, non-conservative collisions with particles in the moderator until thermal equilibrium is reached at or near 0 eV. In this respect, thermal equilibrium represents the random orientation of the motion of a population of positrons, a phenomenon that forms the basis of positron re-emission microscopy, which is also described here.

The positron also combines with an electron within the diffusion distance (10-8 to 10"7 m) of its arrival point and annihilates instantly, 1
Two gamma rays of equal energy of 511 KeV are emitted 80° apart. When the electrons in the medium have a small momentum δp, and the momentum of the gamma ray is mc, the emission angle for prompt annihilation is θ=δp/
Determine the average electron momentum δP by measuring the average value of θ using a gamma-ray detector arranged in a ring similar to that used in PET cyclotrons, offset from 180° by an amount equal to m c. You can ask for it. Finally, positrons may collect electrons to form positronium. Positronium diffuses randomly from its point of formation up to 10-8 to 10-7 meters,
Once it reaches the surface, it escapes into the vacuum. In vacuum, positronium exists with a maximum lifetime of 140XIO-9 seconds before disappearing as its characteristic signature of three gamma rays.

By properly analyzing the annihilation gamma rays emitted by positrons and positronium at or near the target, the phenomena of prompt annihilation, electron momentum distribution and positronium formation can be distinguished from each other. To measure prompt annihilation, two gamma ray detectors such as sodium iodide are used at 180
This can be done by spaced apart and requiring time coincidence of their detectors to eliminate random background events. Being able to measure gamma-ray energies would also minimize non-random background events due to three gamma-ray positronium events occurring with one isochrony; It can be measured by requiring three gamma ray detectors placed in one plane to coincide in time.

Finally, the momentum distribution can be measured by placing two gamma-ray detector arrays with 7 rays 180° apart, with the ability to discriminate angular deviations of gamma-rays as small as 2X10-3 radians. It can be implemented. It is believed that gamma ray detector arrays are subject to similar time matching and energy measurement requirements as required for prompt annihilation detection.

According to the invention, a gamma microscope or a scanning reflection positron microscope can be used to construct an image of the distribution of electron momentum, thereby obtaining an image of the distribution of electron momentum as a function of spatial position. An aerial image can be constructed from the electron momentum distribution by simultaneously imaging the secondary electrons emitted from the sample target or by using a scanning positron beam to provide a positional correlation with the gamma rays. Since such an aerial image directly corresponds to an electron momentum image, it is possible to study the influence of specific changes in the target material on the momentum distribution. Such studies are not possible with electron microscopy. Examples of phenomena that can be studied using this method are changes in electron momentum that occur in response to changes in doping at interfaces inside integrated circuit chips and are equivalent to changes in Fermi level energy, or changes in the electron momentum that occur at interfaces inside integrated circuit chips, or when a foreign substance such as a drug is introduced. These include changes in the energy levels inside living cells. It will be appreciated that other types of positron-based microscopy are also possible, such as imaging using positronium emitted from a sample target.

If a method is adopted to mark the spatial position of positrons prior to their gamma annihilation, a positron gamma microscope can be configured to utilize those signals.
There are at least two spatial marking techniques that may be utilized in the practice of the present invention, each of which has advantages and disadvantages. In either method, the ultimate resolution of the microscope is the initial implantation of positrons.

1O-7 to 1O-
Limited to 8 meter resolution.

The first method is called "scanning". In this method, a narrow positron beam is swept horizontally and vertically along a target under tight control by a set of polarizers. The settings of the polarizer control determine the beam position at any instant and provide the spatial markers needed for microscopy. If the beam size is larger than the diffusion distance of the positron, the resolution of the scanning microscope is determined by the beam size. Due to the low current densities currently available when using slow positron source means, it is difficult to obtain the required beam size while maintaining adequate intensity without resorting to special techniques such as brightness enhancement. Using brightness enhancement techniques, currently developed scanning microscopes can obtain resolutions on the order of 2XlO-5 meters using gamma matching techniques to image positronium formation inside a sample. It was possible.

A second method of marking the position of positron implantation utilizes the phenomenon of secondary electron emission. High energies of about 300 volts and above, upon entering the sample, liberate secondary electrons before they are decelerated to thermal energy and diffuse into the target. The probability of secondary electron emission varies depending on the target composition and initial energy, but ranges from 50% to 200%. Since the electrons are emitted within 10-9 meters of the positron beam implantation position, the secondary electron spectrum contains the spatial information of the positron implantation. This spatial information can be obtained by imaging the electrons in a manner similar to that used in the positron re-emission microscope described here, with some modifications to the geometry). It can be taken out.

Since electrostatic or magnetic lenses are used to perform the imaging, the achievable resolution can be predicted by the same equations that describe transmission positron microscopy. However, in this case the current density is changed, taking into account the losses caused by the efficiency of the gamma ray detector and the probability of emission of secondary electrons. This loss is thought to be as high as 95%. Therefore.

If a resolution of 10-7 is desired, which in a transmission positron microscope requires a current density of about 1013 A/cm2, in a gamma-ray microscope 2X 10-
+2 A/cm2 rl) current densities would be required; such current densities can be utilized in many existing slow positron source means without the need to perform further brightness enhancement, and this This is the first advantage of the secondary electron method. For a given resolution, the required positron beam current density is approximately 10
It's as low as -4 minutes.

According to one aspect of the method of the invention, positrons! A method of implementing III microscopy includes the steps of emitting positrons having a first energy order to generate a positron source stream;
and slowing down the positron source stream to generate a slow positron source means having an energy order of 0. According to the present invention, the second energy order is lower than the first energy order; The method includes propagating a slow positron source means to a sample target to be imaged, and further propagating an image beam formed in response to communication of the slow positron source means with the sample target to the imaging target. , a large number of electron clouds are generated in response to contact of the image beam with the imaging target. The electron cloud is then accelerated, eg electrostatically, towards a phosphor screen that produces a visible display.

In one embodiment of the method of the invention, an image is formed in the vicinity of the phosphor screen in response to the interaction of accelerated electrons with the phosphor screen. The images may be obtained by a video system, preferably of low brightness type, and after being converted to corresponding data are stored in a memory and subsequently provided to a computing system. The data is then subjected to an analysis algorithm that modifies the stored data as necessary to generate enhancement data corresponding to an enhanced version of the acquired image.

According to one particular embodiment, the image is formed using positrons of a slow positron beam that are transmitted through a sample target. In the case of a scanning positron microscope device, the slow positron source means is scanned or rastered along the sample target and the signal is recorded as a function of beam position.

In another embodiment, the image is formed using positrons reflected from the sample target. Similar to the method described above, an image can be formed by scanning a slow positron source means along a sample target, with the image beam striking the sample at locations corresponding to multiple locations of the slow positron source means during the scan. It has properties that are responsive to features of the target.

In yet another embodiment of the invention, the information generated corresponds to an angular correlation image responsive to the angular shift of gamma rays generated during positron annihilation. The image represents the distribution of electron momentum in the sample target; further, in some embodiments, an angularly correlated image is generated to be correlated with the image formed in response to the image beam. Therefore, a large number of features and properties of the sample target can be imaged in a correlative manner. In a highly advantageous embodiment, the steps of forming the angularly correlated image and forming the image in response to the image beam are in response to another step of scanning the slow positron source means along the sample target. Implemented.

〔Example〕

The present invention will be easily understood by reading the following detailed description in conjunction with the accompanying drawings.

FIG. 1 is a schematic diagram illustrating a transmission positron microscope apparatus IO constructed in accordance with a portion of the principles of the present invention. The positrons are obtained from a moderator device 12, which is shown in detail in FIG. That is, this moderator device 12 includes a positron source 14 made of 22NB. In the particular embodiment illustrated here, the 22N5L positron source has a diameter of 5 mm.
and has a radioactivity of 4 mCl. In this example, the energy of the positrons generated by the M electron source 14 is 100 K.
eV 1/XL500Kl! There is IV1'. positron 11
14 is.

It is attached to a titanium (Ti) window 15 that blocks air flow but allows positrons to enter the interior of the positron microscope apparatus. The positron entering the positron microscope device is 25
A series of tungsten (W) vanes 16 are annealed at 00°C. Due to losses due to self-absorption of the positron source, approximately 4×10 −′ of the generated positrons will be emitted again at 2 volts.

High-energy positrons from the positron source 14 are incident on the tungsten vane 16 and are thermalized in the vane 16, resulting in the emission of low-velocity positrons. Such low-velocity positrons are emitted into the positron microscope apparatus with a probability of about 10<-3 >.

The low velocity positrons emitted from the tungsten vane 16 are
A positron source beam 20 is formed which is propagated inside the transmission positron microscope device 110. In this example, the positron source beam has a velocity of approximately 7×105 positrons/sec;
The bending magnet 24 in this embodiment directs the positron source beam 20 to propagate in a direction substantially orthogonal to the beam path 22, as seen in Figure 2. and makes it incident on the target 25.

However, after the positron source beam 20 is bent, the target 2
5, it passes through a focusing lens 26 which focuses the positron source beam onto the target.

Transmission type positron! In this particular application of the Il microscopic device IO, the target 25 is a polyvinyl chloride acetate copolymer (v.

Y-N, S,) foil. This foil has a thickness of less than 800^ and was selected for use for this purpose taking into account that a foil thin enough to be applied in this case can be easily manufactured. ing.

In such a transmission embodiment of the invention, each positron transmitted through target 25 forms a target beam 30 containing imaging information. The target beam is transmitted through an objective lens 31 and a contrast aperture 3.
2 and a projection lens 33, the channel electron multiplier array (CEMA) 3 has three plates.
5 and a phosphor 36 made of P39 phosphor with a long afterglow in this embodiment.

The combined structure of channel electron multiplier array 35 and phosphor 36 converts each positron into a 2Xl (12 cm) diameter light spot. This light spot (not shown) is preferably connected to a low brightness type video camera. and an image processor.

In operation, image analysis device 37 stores data corresponding to events in appropriate storage locations in memory (not specifically shown). In one embodiment, this memory may be in the form of a 384 x 384 array, resulting in signal averaging as a result of image processing performed in image analyzer 37;
This allows the image to be constructed from signal objects registered by the channel electron multiplier array 35. This action occurs at a slow rate of 200 Hz, which is 104 times lower than the lowest intensity normally used in electron microscopes.

FIG. 2 shows an image obtained using the above-described transmission positron microscope apparatus 10. As mentioned above, the target 25
V has a thickness estimated to be no less than 800 mm as measured using optical interferometry techniques.

Y, N, S, film. During the imaging process, the target 25 was supported by a Zoo line, 82% transmittance wire mesh. With this thickness, 2
0-50% was transmitted. The image shown in Figure 2 is 55X
The zero magnification, which represents a magnification of 0 and required 4 hours of signal averaging to accumulate, was calculated from a known wire grid spacing of 250 gm.

Figure 3 is a histogram of one of the grid wires whose image is shown in Figure 2 and corresponds to a least squares fit of a Gaussian function to the data shown in this figure accumulated during image formation. ing. By adjusting the number of zeros in the counts to display the entire gridwire profile and fitting the wire edges to a Gaussian function, we obtained a measurement resolution consistent with theory.

FIG. 4 is a schematic diagram illustrating a reflection positron re-emission microscope apparatus 50 constructed in accordance with the principles of the present invention. As shown in FIG. Reducer device explained in! 12, a positron moderator 52 supplies a low-velocity positron source beam 53.
Equipped with. The slow positron source beam 53 is a beam of approximately parallel incidence that propagates along the positron source beam axis 54 toward the target 55 . However, the positron source beam axis is straight only while the slow positron source beam 53 is propagating within the beam path 57. As the slow positron source beam 53 approaches the vicinity of the target 55, the propagation axis bends in response to the accelerating electric field present between the target 55 and the objective lens 59.

FIG. 5 is a schematic diagram showing the bending of the slow positron source beam 53 as it approaches the electric field between the target 55 and the objective lens 59. As a result of bending, the focal length is mw
This is effectively shortened from 1' of the O lens to 1. Additionally, the angle of incidence of the slow positron source beam on the target is shown varying from θX to θF in this figure. Therefore, it is believed that the electric field greatly influences the focal point position and forces the particles in the slow positron source beam 53 to follow a parabolic path as they approach the target.

Returning to FIG. 4 again, the slow positron source beam 5
It is heated by the target by the incidence on the target of 3,
A positron target beam 61 formed from positrons emitted again from the target 55 is accelerated by an electric field, and then propagated through an objective lens 59, a contrast aperture 62, an intermediate lens 63, and a projection lens 64. The channel electron multiplier array 65 is reached. This array may employ video and processing equipment similar to the image analysis equipment 37 described above with respect to FIG. Needless to say, it's a good thing.

FIG. 6 schematically shows a positron gamma microscope 70 advantageous for forming spatial images of double gamma ray coincidences (prompt annihilation), triple gamma ray coincidences (positronium formation) and momentum distributions (double gamma ray coincidences further including angular analysis). As shown in Figure 0, a positron gamma microscope 70 includes a slow positron generation, focusing, and transport device 71 that generates a nearly parallel beam 72. This beam is propagated through an input lens 73 and focused by a condenser lens 74 so as to pass through a deflection block aperture 5 and enter an accelerating deflection block 76 . The beam 72 is modified, for example by an electric field, while inside the acceleration deflection block 76 to follow a downwardly concave parabolic path;
Reach target 81. The acceleration deflection block 76 and the electric field geometry between the block and the target 80 are set so that the beam is substantially in focus when it reaches the target 80.

The secondary electrons emitted when the positron beam collides with the target 80 are converted into secondary electron beams 8 by the acceleration/deflection block 76.
It is accelerated as 2. The secondary electron beam 82 is propagated towards an objective lens 83 and focused by this lens. The electrons of the focused secondary electron beam 82 pass through a contrast aperture 84 which improves resolution by limiting the spread angle of the secondary electron beam 82. The secondary electron beam continues to propagate until an enlarged image is formed just before the projection lens 85. The projection lens focuses the image,
The image is further enlarged until a final enlarged image is formed on a channel electron multiplier array (CEMA) 87. The channel electron multiplier array generates a large number of electrons that are positioned as small dots for each incident electron, and the electrons are incident on a resistive anode encoder (RAE) 88 .

Resistive anode encoders are one of several devices that can generate signals suitable for simultaneously obtaining position analysis and timing information. These signals may take the form of x,y read signals and are
The signal is transmitted through the signal line 90 in a vacuum of zero. x, y
After the read signal is extracted from the positron gamma ray Jil microscope, the IK? As described, the signal is divided into signals suitable for position analysis and timing information.

Here, explaining the positrons that collided with the target 80, the positrons become gamma rays and disappear, and the gamma rays are detected by the gamma ray detector 92. There may be two gamma ray detectors as shown to detect annihilation, but there may be three gamma ray detectors to detect positronium formation, in an embodiment with three gamma ray detectors. In this case, the detectors are arranged so that they are approximately coplanar with each other. As explained later with respect to FIG.
Such gamma ray detectors may each be an array of gamma ray detectors, especially if it is desired to perform momentum analysis.

In FIG. 6, the x,y read signal is split into a position signal 93 suitable for position analysis and a timing signal 94 providing timing information.0 position value 93 is sent to an x,y position analysis system 100; Timing signal 94 is sent to time matching unit 101. The signals generated by gamma ray detector 92 are transmitted to gamma ray matching unit 10 which uses commercially available electronics to measure spatial matching and energy requirements.
Sent to 2. In this embodiment, the output of the gun line matching unit 102 is sent to one input terminal of the time matching unit 101 where it is determined whether there is a time match with the timing signal 94 from the resistive anode encoder 88. Ru.

If there is a match, the output signal of the matching unit 101 approximately matches the gamma ray matching unit 102 for 1 hour with respect to the processing speed of the x, y position analysis system 100 that was analyzing the position signal 93. The output signal of the 0 time delay device 104 is supplied to the 1 time delay device 104 to adjust the position of the 0 time delay device 104 to begin transmitting the event to the image processing memory and display section 105 of the computer.
The events are fed into a time gate (not shown) of the x,y position analysis system 100 and are stored in this memory and display 11&l0
5 is stored.

FIG. 7 is a functional block and line connection diagram illustrating one particular embodiment of the momentum distribution analysis electronic system 120. As shown in FIG.
It operates when the positron 121 annihilates with the electron to form a pair of simultaneous gamma rays, gamma rays 123 and gamma rays 124. Each gamma ray has an energy of approximately 511 KeV, but is offset by a small angle θ from 180'' due to electron momentum. Therefore, the gamma ray detector array 125 has a gamma ray detector array 125 that responds to gamma rays 123 separately from the gamma ray detector 126 that responds to gamma rays 124.
As shown, each gamma ray detector array is formed from a plurality of independent detectors having a predetermined positional relationship to each other. In this particular embodiment, each gamma ray detector array is shown as including six independent detectors.

Gamma ray detector arrays 125 and 126 each include:
Detector systems 130 and 131 are coupled to provide signals.

These detector systems determine which individual detectors in the detector array detect gamma rays and measure the energy of the gamma rays.

If the energy is sufficient, the timing signals from the detector systems 130 and 131 will be aligned in time.
2, where the resistive anode encoder (7th
A timing signal from (not shown in the figure) is awaited via timing signal [133]. Meanwhile, the signals from detector system 130 and detector system 131 corresponding to the number of detectors in the array that detected gamma rays are
It is sent to an angle measurement unit 140 which measures the angular deviation using a predetermined relative detector position.

If a triple time match occurs, the time-match unit) 1
32 sends a signal to the gate input terminal, angle measurement unit,)
The angle measurements are transmitted from 140 to x,y memory map unit 143. The angle measurements are calculated by the x,y measurement unit 145. This x,y measuring unit 145 measures the x,y positional signals at approximately the same time that the x,y memory map unit 143 receives the angle measurements.
The data is sent to the memory map unit 143. Once sufficient data has been accumulated, the momentum algorithm 146 calculates the electron momentum from the angular information in the x, y memory map unit 143 and stores the resulting value in the x, y momentum memory map 14.
Memorize to 7. x, vMth quantity memory map 147 generates a responsive display on video monitor 148.

Although the present invention has been described in terms of specific embodiments and applications, those skilled in the art will recognize, based on this teaching, that there is no way to go beyond the scope or spirit of the invention as set forth in the claims. Instead, additional embodiments can be constructed.

Accordingly, it should be understood that the drawings and descriptions in this specification are presented to facilitate understanding of the invention and are not to be construed as limiting the scope of the invention.

[Brief explanation of the drawing]

Diagram NS1 is a schematic diagram of a transmission type positron s'e mirror device. Figure 2 is a positron micrograph of the grain structure of the V, Y, N, and S films obtained using the positron microscope device in Figure 1, and Figure 3 is a least squares fitting of a Gaussian function. FIG. 2 is a histogram of the image of the grid wire obtained using the method of the present invention. FIG. FIG. 5 is a schematic diagram of a reflection positron re-emission microscope showing the bending of the slow positron source beam as it passes through the electric field between the target and the objective lens. Figure 6 shows double gamma-ray coincidence (prompt annihilation), triple gamma-ray coincidence (positronium form!&) and momentum distribution (double gamma-ray coincidence further including angular analysis)
A schematic diagram of a positron gamma ray microscope useful for forming spatial images of , and FIG. 7 is a functional block and line connection diagram of momentum distribution analysis electronics. (Explanation of symbols of main parts) IO... Transmission positron microscope device, 12... Moderator device, 14... Positron source, 15... Titanium window, 16
Tungsten vane, 20 Positron source beam, 24 Bending magnet, 25 Target, 26 Condensing lens, 30 Target beam, 31 Objective lens. 32... Contrast aperture, 33... Projection lens, 35... Channel electron multiplier tube array, 36...
- Fluorescent substance, 37... Image analysis device, 50... Reflection positron re-emission microscope device, 52... Positron moderator, 5
3...Slow positron source beam, 55...Target,
59... Objective lens, 61... Positron target beam, 62... Contrast aperture, 64...
Projection lens, 65... Channel electron multiplier array, 6
6... Phosphor screen, 70... Positron gamma ray microscope, 71... Low-speed positron generation, focusing, transport device,
72... Positron beam, 73... Input lens, 74
... Condenser lens, 75 ... Deflection block aperture, 76 ... Acceleration deflection block, 80 ... Target 82 ... Secondary electron beam, 83 ... Objective lens, 8
4... Contrast aperture, 85... Projection lens, 87... Channel electron multiplier tube array. 8B... Resistance anode encoder, 92... Gamma ray detector, 100... x, y position analysis system. 101... time-fi units), 102... gamma ray coincidence unit, 104... time delay device. 105... Image processing memory and display unit, 120...
Momentum distribution analysis electronic system, 123.124... Gamma ray, 125.126...
Gamma ray detector array, 130.131...Detector system, 132...Time coincidence unit 140...Angle measurement unit, 143...x, y memory map unit, 145...x, ym constant unit ), 14B...
Momentum algorithm. 147...x,y momentum memory map, 148...
Engraving of the video monitor drawing (no changes to the content) Te'82 Figure position (μM) Figure procedure amendment June 1999

Claims (1)

[Claims] 1. A positron microscope device for forming an enlarged image of a sample target, the positron microscope device comprising: a low-speed positron source means for generating a positron source beam formed from low-energy positrons; a focusing means for focusing and directing the low energy positrons of the positron source beam to a sample target; a single particle image enhancement means for forming an image in response to the target beam formed from low energy particles from the sample target; A device consisting of 2. A positron microscope apparatus according to claim 1, further comprising projector means for focusing the target beam onto the single particle image enhancement means. 3. The positron microscope apparatus according to claim 1, wherein the single particle image enhancement means receives the target beam and, in response to each particle in the colliding target beam, performs image enhancement on a particle-by-particle basis. An apparatus comprising: target plate means for emitting a large number of electrons; and phosphor means for interacting with the large number of electrons emitted by the target plate means to generate a large number of photons corresponding to each electron. 4. The positron microscope apparatus according to claim 3, further comprising display plate means for supporting the phosphor means in a substantially planar configuration and substantially parallel to the target plate means. 5. The positron microscope apparatus according to claim 1, wherein the low-speed positron source means includes positron moderator means for generating low-energy positrons. 6. A positron microscope apparatus according to claim 5, wherein the positron moderator means receives high-energy positrons and includes thermalization means for generating the positron source beam in response. 7. In the positron microscope apparatus according to claim 6, the thermalization means is made of W, and the positron moderator means includes: a high-energy positron source that generates high-energy positrons; and the high-energy positron source. and window means disposed between the thermalization means and the high energy positron source supporting the high energy positron source in close proximity to the thermalization means. 8. In the positron microscope apparatus according to claim 7, the high-energy positron source is made of ^2^2Na, and the window means is made of Ti, so that the high-energy positron source emits The high energy positrons transmitted through the window means communicate with the thermalization means. 9. The positron microscope apparatus according to claim 7, wherein the thermalization means is configured as a plurality of vanes. 10. The positron microscope apparatus according to claim 1, further comprising a positron source beam bending means for bending the positron source beam. 11. The positron microscope apparatus according to claim 1, further comprising objective lens means for focusing the target beam. 12. The positron microscope apparatus according to claim 11, further comprising aperture means for controlling the size of the aperture for the target beam. 13. A positron microscope apparatus according to claim 1, wherein the slow positron source means and the single particle image enhancement means are located on opposite sides of a sample target. 14. The positron microscope apparatus according to claim 1, further comprising another single particle image enhancement means arranged to receive positrons returned from the sample target in a direction generally toward the slow positron source means. Equipment provided. 15. The positron microscope apparatus according to claim 1, wherein the particles forming the target beam are positrons. 18. The positron microscope apparatus according to claim 1, wherein the particles forming the target beam are electrons. 17. A positron microscope apparatus for forming an enlarged image of a sample target, the positron microscope apparatus comprising: a low-velocity positron source means for generating a positron source beam formed from low-energy positrons; focusing means for directing said low-energy positrons of a beam to a sample target; An apparatus comprising: particle image enhancement means; 18. The positron microscope apparatus according to claim 17, further comprising objective lens means for focusing the re-emitted beam. 19. The positron microscope apparatus according to claim 18, further comprising accelerator means disposed between the sample target and the objective lens means for accelerating the particles in the re-emission beam. Device. 20. The positron microscope apparatus according to claim 18, further comprising contrast aperture means for controlling the size of the aperture for the target beam. 21. The positron microscope apparatus according to claim 18, further comprising lens means for focusing and enlarging the re-emitted beam. 22. The positron microscope apparatus according to claim 17, wherein the single particle image enhancement means receives the target beam, and in response to each particle in the impinging re-emission beam, performs particle-by-particle image enhancement. an apparatus comprising: target plate means for emitting a large number of electrons; and phosphor means for interacting with the large number of electrons emitted by the target plate means to generate a large number of photons corresponding to each electron; . 23. The positron microscope apparatus according to claim 22 further includes display plate means that supports the phosphor means in a substantially planar configuration and substantially parallel to the target plate means. 24. The positron microscope apparatus according to claim 17, wherein the low-velocity positron source means includes positron moderator means for generating low-energy positrons. 25. A positron microscope apparatus according to claim 17, wherein the particles forming the target beam are positrons. 28. The positron microscope apparatus according to claim 17, wherein the particles forming the target beam are electrons. 27. emitting positrons having a first energy level to generate a positron source stream; slowing down a positron source stream; propagating the slow positron beam toward a sample target to be imaged; and, in response to communication of the slow positron beam with the sample target, propagating an image beam formed from positrons toward an imaging target; generating a plurality of electron clouds in response to communication of the image beam with the imaging target; and directing the electron clouds to a phosphor screen. A microscopy method consisting of the process of accelerating towards; 28. The method of claim 27 further comprising the step of collecting an image formed in the vicinity of the phosphor screen. 29. The method of claim 28 further comprising the step of storing data in memory corresponding to the acquired image. 30. The method of claim 29, further comprising the step of providing the stored data to a computing system, wherein the data is configured to enhance the collected image. 2. A method under the action of an analysis algorithm for modifying said stored data to generate enhancement data corresponding to an image of said data. 31. The method of claim 27, further comprising the step of scanning the slow positron beam along the sample target, the image beam corresponding to a scanning location of the slow positron beam during the scanning. The method has a property responsive to a feature within the sample target at a location where the sample target is located. 32. The method of claim 27, further comprising the step of forming an angularly correlated image corresponding to an angular shift in response to the angle of gamma ray generation. 33. The method of claim 32, wherein the angularly correlated image is responsive to an electron momentum distribution in the sample target. 34. The method of claim 33, wherein the step of forming an angularly correlated image is performed to correlate with an image formed in response to the image beam. 35. The method of claim 34, wherein forming the angularly correlated image and forming the image in response to the image beam includes directing the slow positron beam along the sample target. A method performed in response to a scanning process. 36. The method of claim 27, wherein the slow positron beam is spin polarized. 37. The method of claim 27, wherein the image beam is formed from positrons reflected from the sample target. 38. generating a slow positron beam; propagating the slow positron beam toward a sample target; converting at least one gamma ray generated in response to contact between the slow positron beam and the sample target into gamma rays; A microscopy method consisting of: monitoring a process; 39. The method of claim 38, wherein the step of monitoring gamma rays comprises detecting a first gamma ray generated in response to communication between the slow positron beam and the sample target to a first gamma ray detector. performing a first monitoring with a second gamma ray detector; and a second monitoring of second gamma rays generated in response to communication between the slow positron beam and the sample target; How to include more. 40. The method of claim 39, further comprising the step of measuring an angle between the first gamma ray and the second gamma ray to obtain an electron momentum parameter value. 41. The method according to claim 39, further comprising the step of defining the timing of the first monitoring step and the second monitoring step to enable background noise elimination. method provided. 42. The method of claim 39, wherein the step of monitoring includes a third beam generated in response to communication of the slow positron beam with the sample target to detect the formation of positronium. The method further comprises the step of monitoring the gamma rays of the sample a third time with a third gamma ray detector. 43. In the method according to claim 42, the step of monitoring includes performing the first monitoring to determine that the first, second, and third gamma rays are generated simultaneously. The process includes a process of defining the timing of a second monitoring process and a third monitoring process. 44. The method of claim 38, further comprising the step of measuring the spatial position of the slow positron beam. 45. The method of claim 44, wherein the spatial position is measured in response to beam deflection plate data. 46. A positron microscope apparatus for forming an enlarged image of a sample target, the positron microscope apparatus comprising: slow positron source means for generating a positron source beam formed from low-energy positrons; focusing the positron source beam consisting of the positrons; a first focusing means for directing the low-energy positrons of the positron source beam onto a sample target; and a first focusing means for directing the low-energy positrons of the positron source beam onto a sample target; An apparatus comprising: second focusing means for focusing a beam of secondary electrons; and imaging means for generating an image signal in response to the beam of secondary electrons. 47. The positron microscopy apparatus of claim 46, wherein said imaging means comprises a single particle image enhancement arrangement that generates a substantially visible signal in response to said secondary electrons. 48. The positron microscope apparatus according to claim 47, wherein the single particle image enhancement arrangement comprises a channel electron image intensifier array that generates a large number of electrons each time the secondary electrons are incident thereon. . 49. A positron microscope apparatus according to claim 46, wherein said imaging means comprises position detector means for generating a position signal in response to said secondary electrons. 50. The positron microscope apparatus of claim 46, wherein said imaging means comprises timing means for generating a timing signal in response to said secondary electrons. 51. The positron microscopy apparatus of claim 46, further comprising gamma ray detector means for detecting the generation of at least one gamma ray in response to said positron being incident on a sample target. 52. A positron microscope apparatus according to claim 46, wherein said gamma ray detector means comprises a gamma ray detector array formed from a plurality of gamma ray detectors arranged in a predetermined positional relationship with respect to each other. 53. The positron microscope apparatus according to claim 52, further comprising gamma ray angular deviation analysis means for measuring the angular deviation of simultaneous gamma rays generated in response to the positrons being incident on the sample target.