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Claims  |
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What is claimed is:
1. An electron multiplier device comprising:
an insulating substrate having opposite first and second substrate surfaces
which are parallel with each other,
a plurality of through-holes in said substrate having first through-hole
surfaces at an obtuse angle with respect to said first substrate surfaces
and second through-hole surfaces opposing said first through-hole
surfaces,
a secondary electron emission layer formed on said first through-hole
surfaces,
a conductive layer formed on of non-electron emissive materials the second
through-hole surface of each respective through-hole separated from the
secondary electron emission layer of the respective through-hole,
first connection means to connect said secondary electron emission layer of
each through-hole to a respective first DC voltage supply through said
first substrate surface, and
second connection means to connect said conductive layer of each
through-hole to a respective second DC voltage supply through said second
substrate surface,
whereby electrons incident on said through-holes passing through said first
substrate surface and impinging on said secondary electron emission layer
are multiplied and accelerated toward the second substrate surface when
the DC voltage of the first and second DC voltage supplies are
respectively connected by said first and second connection means to said
secondary emission layer and said conductive layer of each through-hole
and the DC voltage of the second DC voltage supply is greater than the DC
voltage of the first DC voltage supply.
2. An electron multiplier device as claimed in claim (1), wherein each
through-hole is one of circular, rectangular, and hexagonal in said first
substrate surface and the through-holes are closely and regularly
arranged.
3. An electron multiplier device as claimed in claim 1, wherein said
insulating substrate is made of SiO.sub.2 and said through-holes are
formed by photoetching.
4. An electron multiplier device as claimed in claim 1, wherein said
substrate has a groove formed between and insulating from each other said
secondary electron emission layer and said conductive layer in each
through-hole.
5. An electron multiplier as in claim 1, further comprising first and
second DC voltage supplies respectively connected by said first and second
connecting means to said secondary electron emission layer and said
conductive layer, and the DC voltage of the second DC voltage source is
greater than the DC voltage of the first DC voltage source.
6. An electron multiplier device, comprising:
a plurality of successively adjacent dinode leaves successively layered on
each other, including an upper first leaf and a second leaf, one directly
adjacent the other, each of said plurality of leaves including
an insulating substrate having opposite first and second substrate surfaces
which are parallel with each other,
a plurality of through-holes in said substrate, each of said through-holes
being inclined to said first and second substrate surfaces and having a
first through-hole surface intersecting said first substrate surface at an
obtuse angle and a second through-hole surface opposing said first
through-hole surface and intersecting said second substrate surface at an
obtuse angle,
a secondary electron emission layer formed on said first through-hole
surfaces,
a conductive layer of non-electron emissive materials formed on the second
through-hole surface of each respective through-hole separated from the
secondary electron emission layer of the respective through-hole,
first connection means to connect said secondary electron emission layer of
each through-hole to a respective first DC voltage supply associated with
the respective leaf, through said first substrate surface, and
second connection means to connect said conductive layer of each
through-hole to a respective second DC voltage supply associated with the
respective leaf, through said second substrate surface, the second
connection means of said first leaf being electrically connected to the
first connection means of said second leaf so that the conductive layer of
each through-hole of said first leaf is at the same electrical potential
as the electron emission layer of each through-hole of said second leaf;
the respective through-holes of each leaf being aligned with a respective
one of the through-holes in each leaf adjacent thereto, the aligned
through-holes of adjacent leaves being inclined in opposite directions;
whereby electrons incident on each through-hole of said first leaf passing
through the first substrate surface thereof and impinging on said
secondary electron emission layer are multiplied and accelerated toward
the second substrate surface of said first leaf when the first and second
DC voltage supplies associated with said first leaf are respectively
connected by said first and second connection means to said secondary
electron emission layer and said conductive layer of each through-hole and
the DC voltage of the second DC voltage supply is greater than the DC
voltage of the first DC voltage supply, the electrons accelerated toward
the second substrate surface of said first leaf being incident of the
through-hole of said second leaf and impinging on the secondary electron
emission layer thereof and being further multiplied and accelerated toward
the second substrate surface of said second leaf when the first and second
DC voltage supplies associated with said second leaf are respectively
connected to said first and second connection means of said second leaf to
said secondary electron emission layer of said second leaf and said
conductive layer of each through-hole of said second leaf, and the DC
voltage of the second DC voltage supply associated with said second leaf
is greater than the DC voltage of the first DC voltage supply associated
with said second leaf, the DC voltage of the second DC voltage supply
associated with said first leaf being equal to the DC voltage of the first
DC voltage supply associated with said second leaf.
7. An electron multiplier device as in claim 6, wherein said substrate of
each of said leaves has a groove formed between and insulating from each
other said secondary electron emission layer and said conductive layer in
each through-hole.
8. An electron multiplier device as in claim 6, further comprising a first
leaf first DC voltage supply connected by said first connecting means of
said first leaf to said secondary electron emission layer of said first
leaf, a first leaf second DC voltage supply connected by said second
connecting means of said first leaf to said conductive layer of said first
leaf and by said secondary electron emission layer of said second leaf to
said secondary electron emission layer of said second leaf, and a second
leaf DC voltage supply connected by said second connecting means of said
second leaf to said conductive layer of said second leaf, the DC voltage
of said first leaf first voltage supply being less than the DC voltage of
said second leaf voltage source.
9. An electron multiplier device as in claim 8, wherein said substrate of
each of said leaves has a groove formed between and insulating from each
other said secondary electron emission layer and said conductive layer in
each through-hole.
10. An electron multiplier device as in claim 6, wherein the first
connecting means and second connecting means of each leaf are respectively
formed on the first substrate surface and second substrate surface
thereof, so as to respectively make direct physical and electrical contact
with the second connecting means and first connecting means of respective
ones of said leaves directly adjacent thereto.
11. An electron multiplier device as in claim 6, wherein said conductive
layer is formed of inactive conductive materials. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
The present invention relates to an electron multiplier device which can
emit secondary electrons, and more particularly to such a device which can
be used for a photomultiplier tube.
A prior electron multiplier device is known in which conventional dinodes
of the Venetian-blind type are used and in which electrons are multiplied
by a plurality of such dinodes which are closely arranged within a
relatively narrow space.
FIG. 1 shows a cross-sectional view of a part of the electron multiplier
device consisting of dinodes of the conventional venetian-blind type.
In FIG. 1, stages "i" and "i+1" of the electron multiplier device
consisting of a plurality of mesh-and-dinode stages which are stacked are
after another are shown in detail. Mi in FIG. 1 indicates the i-th mesh
arranged orthogonally to the electron path. Dyi indicates the i-th dinode.
Mi+1 indicates the "i+1"-th mesh. Dyi +1 --; and indicates the "i+1"-th
dinode.
The "i+1"-th dinode is inclined in the opposite direction to the i-th
dinode.
Dinodes with opposite inclination angles and the corresponding meshes are
alternately arranged to form an electron multiplier device.
The meshes are made of metal plates. Each metal plate is masked and
selectively etched by a photoetching process.
The dinode of Venetian-blind type is made by press work, and this type of
dinode is used as a secondary electron emission electrode.
Mesh Mi is connected to dinode Dyi and they are kept at potential Vi. Mesh
Mi+1 is connected to dinode Dyi+1 and they are kept at potential Vi+1.
Secondary electrons emitted from dinode Dyi responding to the electrons
incident on dinode Dyi are incident on inclined dinode Dyi+1 in the next
stage, and then they are multiplied there.
If the number of dinodes in the electron multiplier device consisting of a
plurality of dinodes of Venetian-blind type is increased, resolution at an
arbitrary point on the incident plane can be improved to some extent.
Secondary electrons emitted from dinode Dyi are once decelerated by the
rear surface of the adjacent dinode leaf and accelerated by mesh Mi+1--;
in the next stage. Secondary electrons are then incident on dinode Dyi+1.
Deceleration in the above process causes the electron transit time to be
increased and its variation to be enhanced.
The electron transit time and its variation are proportional to the
dimensions of the electrodes. The dinode sizes and the gaps between
adjacent dinode leaves are to be minimized to reduce the electron transit
time and its variation.
However, the accuracy of the dimensions in the dinodes finished by metal
work is limited. It is thus impossible for the electron transit time and
its variation to be reduced beyond the limit, and also for resolution at
an arbitrary point on the dinode to be greatly improved.
The objective of the present invention is to present an electron multiplier
device wherein the above problems can be solved.
SUMMARY OF THE INVENTION
An electron multiplier device of first type in accordance with the
invention consists of a substrate of insulating material with first and
second surfaces which are parallel with each other, a plurality of
through-holes formed on the substrate having first through-hole surfaces
at an obtuse angle with respect to the first surface of the substrate and
second through-hole surfaces against the first through-hole surfaces, a
secondary electron emission layer formed on the first surface of the
substrate by depositing active materials onto the first surface of the
substrate, a conductive layer formed on the second surface of each
through-hole which is separated from the secondary electron emission
layer, first connection means to connect the secondary electron emission
layer to the respective power supply through the first surface of the
substrate, second connection means to connect the conductive layer to the
respective power through the second surface of the substrate the means to
multiply the electrons incident on the through-holes passing through the
first surface of the substrate by using the secondary electron emission
layer, and to apply a pair of DC voltages to the first and second
connection means so that the multiplied electrons are accelerated toward
the second surface of the substrate.
An electron multiplier device of a second type in accordance with the
invention consists of a substrate of insulating material with first and
second surfaces which are parallel with each other, a plurality of
through-holes formed on the substrate having first through-hole surfaces
at an obtuse angle with respect to the first surface of the substrate and
second through-hole surfaces against the first through-hole surfaces, a
first secondary electron emission layer formed on the first surface of
each through-hole, a second secondary electron emission layer formed on
the second surface of each through-hole which is separated from the first
secondary electron emission layer, first connection means to connect the
first secondary electron emission layer to the respective power supply
through the first surface of the substrate, second connection means to
connect the second secondary electron emission layer to the respective
power supply through the second surface of the substrate, and means to
multiply the electrons incident on the through-holes passing through the
first surface of the substrate by using the secondary electron emission
layer, and to apply a pair of DC voltages to the first and second
connection means so that the multiplied electrons are accelerated toward
the second surface of the substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a cross-sectional view of the dinode arrangement of the
conventional Ventian-blind type.
FIG. 2 shows a plan view of the first embodiment of the first type of the
electron multiplier device in accordance with the present invention using
one electron multiplier element.
FIG. 3 is a cross-sectional view of the first embodiment shown in FIG. 2.
FIG. 4 is a perspective view of a part of the first embodiment shown in
FIG. 3.
FIG. 5 is a cross-sectional view of an embodiment of the first type of the
electron multiplier device consisting of three electron multiplier
elements.
FIG. 6 is a cross-sectional view of an embodiment of the photomultiplier
tube consisting of the first type of the electron multiplier device using
four electron multiplier elements in a vacuum envelope.
FIG. 7 is a plan view of the second embodiment of the first type of the
electron multiplier device in accordance with the present invention using
one electron multiplier element.
FIG. 8 is a plan view of the third embodiment of the first type of the
electron multiplier device built in accordance with the present invention
using one electron multiplier element.
FIG. 9 is a plan view of the fourth embodiment of the first type of the
electron multiplier device built in accordance with the present invention
using one electron multiplier element.
FIG. 10 is a cross-sectional view of another embodiment of the
photomultiplier tube consisting of the first type of the electron
multiplier device built in a vacuum envelope.
FIG. 11 shows a cross-sectional view of a further embodiment of the
photomultiplier tube consisting of the first type of the electron
multiplier device in a vacuum envelope.
FIG. 12 is a plan view of the first embodiment of the second type of the
electron multiplier device built in accordance with the present invention
using one electron multiplier element.
FIG. 13 is a cross-sectional view of the first embodiment of electron
multiplier device according to the second type of the present invention
shown in FIG. 12.
FIG. 14 is an enlarged view of a part of FIG. 13.
FIG. 15 is a cross-sectional view of an embodiment of the electron
multiplier device consisting of three electron multiplier elements
according to the second type of device of the present invention.
FIG. 16 is a cross-sectional view of an embodiment of the photomultiplier
tube consisting of the electron multiplier device using three electron
multiplier elements in a vacuum envelope according to the second type of
device of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The first type of electron multiplier device according to the invention
will be described hereinafter referring to FIGS. 2 through 11.
FIG. 2 is a plan view of the first embodiment of the first type of the
electron multiplier device built in accordance with the present invention
using one electron multiplier element. FIG. 3 is a cross-sectional view of
the first embodiment of the present invention shown in FIG. 2 when the
first embodiment of the electron multiplier device is operated. FIG. 4 is
a perspective view of a part of the first embodiment shown in FIG. 3.
A plurality of through-holes 2 circular apertures are bored on planar
insulating substrate 1 made of glass (SiO.sub.2), and these are inclined
to the incident plane of the electron beam.
Through-holes 2 are bored by a photoetching process.
When insulating substrate 1 is exposed to UV rays at the desired angle of
the inclination of the through-holes through a negative image mask whereon
a pattern consisting of the apertures and separation grooves are formed, a
latent image is formed on the glass plate constituting insulating
substrate 1 corresponding to the pattern of through-holes.
Thereafter, specific portions defined by the latent image are crystalized
by heat treatment. Crystalized portions are selectively etched by acid to
obtain a pattern of through-holes corresponding to the latent image
pattern.
Antimony (Sb) is evaporated onto a first inclined plane of each
through-hole which is at an obtuse angle with respect to RN upper surface
of the substrate 1 whereon through-holes 2 are bored, and then secondary
electron emission layer 5 is formed on this inclined plane.
Secondary electron emission layer 5 is insulated from the lower surface of
substrate 1 so that the secondary electron emission layer cannot extend to
the aperture in the other side of each through-hole.
An inactive conductive material such as aluminum (Al) is then evaporated
onto a second inclined plane of each through-hole, which is at an obtuse
angle with respect to the lower surface of the substrate 1 whereon
through-holes 2 are bored, and is separated from the secondary electron
emission layer by separation groove 7. Then, acceleration electrode layer
6 is formed onto this inclined plane by aluminum evaporation.
The acceleration electrode layer 6 is insulated from the upper surface of
substrate 1 so that the acceleration electrode layer 6 cannot extend to
the aperture in this side of the through-hole.
Connection means 3 to connect a plurality of secondary electron emission
layers 5 to the respective power supply are formed on the first (upper)
surface of insulating substrate 1 and connection means 4 to connect a
plurality of accelerating electrode layers 6 to the respective power
supplies are formed on the second (lower) surface of insulating substrate
1.
The function of the electron multiplier device built in accordance with the
present invention will mainly be described referring to FIG. 3.
The electron multiplier device built in accordance with the present
invention is arranged within a vacuum envelope. Connection means 3 and 4
are connected to power supplies 10a and 10b, respectively. DC voltage
V.sub.2 fed from power supply 10b is greater than De voltage V.sub.1 fed
from power supply 10a.
The potential difference between V.sub.1 and V.sub.2 causes an acceleration
field toward acceleration electrode layer 6 starting from secondary
electron emission layer 5.
Secondary electrons emitted from the first surface in the electron
multiplier device is incident on secondary electron emission layer 5.
A single leaf of dinode in the electron multiplier device is not always
used but a plurality of leaves of dinodes in the electron multiplier
device are always used.
FIG. 5 is a cross-sectional view of an embodiment of the first type of the
electron multiplier device consisting of three electron multiplier
element.
The first leaf in the electron multiplier device is fastened to the second
leaf in the electron multiplier device so that the through-holes in the
second leaf are inclined in the opposite direction to the through-holes in
the first leaf.
The second leaf in the electron multiplier device is fastened to the third
leaf in the electron multiplier device so that the through-holes in the
third leaf are inclined in the opposite direction to the through-holes in
the second leaf and in the same direction as the through-holes on the
first leaf. Power supplies 10a through 10d (V.sub.3 >V.sub.2 >V.sub.1 >Vo)
are connected to the respective terminals of the electron multiplier
device.
Acceleration electrode layer 6 of the first leaf in the electron multiplier
device and secondary electron emission layer 5 of the second leaf in the
electron multiplier device are held at the same potential (V.sub.1).
Acceleration electrode layer 6 of the first leaf in the electron
multiplier device is used to accelerate electrons multiplied by using
secondary electron emission layer 5 of the first leaf in the electron
multiplier device and to feed them to the secondary electron
multiplication layers of the second leaf in the electron multiplier
device.
This mode of operation is the same as the operation of the dinode of
Venetian-blind type with which an acceleration mesh electrode held at the
same potential as the dinode is provided.
Acceleration electrode layer 6 of the second leaf in the electron
multiplier device and secondary electron emission layer 5 of the third
leaf in the electron multiplier device are held at the same potential
(V.sub.2).
Electrons (60) incident onto electron emission layer 5 of the first leaf in
the electron multiplier device are multiplied by electron emission layer
5. Thereafter, these electrons are incident on electron emission layer 5
of the second leaf in the electron multiplier device, and then multiplied
there. Electrons multiplied by electron emission layer 5 of the second
leaf in the electron multiplier device are multiplied by electron emission
layer 5 of the third leaf in the electron multiplier device.
Electrons are thus multiplied by the second and third leaves in the
electron multiplier device, and the multiplied electrons are emitted from
the corresponding apertures.
A smaller number of electrons generated in the vicinity of the incident
light beam aperture can be trapped by acceleration electrode layer 6 of
the first leaf in the electron multiplier device before the secondary
electrons arrive at electron emission layer 5 in the next stage.
Most electrons, however, arrive at electron emission layer 5 in the next
stage and are multiplied there.
If smaller number of electrons are trapped by acceleration electrode layer
6 of the first leaf in the electron multiplier device, it causes no
problem. Unless the acceleration electrode layer 6 is provided, a small
number of electrons touch the wall of each through-hole, and electrons on
the wall of each through-hole can distort the electric field in the
vicinity of the wall. Thus, a small number of electrons are trapped by
acceleration electrode layer 6 of the first leaf in the electron
multiplier device when the acceleration electrode layer is provided, but
however, the electron multiplier device can be operated stably.
FIG. 6 is a cross-sectional view of an embodiment of the photomultiplier
tube wherein the electron multiplier device of the first type is provided
within a vacuum envelope.
Photocathode 14 is formed on the inner surface of the incident window of
vacuum envelope 9.
Anode 15 is provided corresponding to the emission aperture of the fourth
leaf in the electron multiplier device.
Power supplies are connected to the respective leaves of dinodes in the
electron multiplier device, and the highest DC voltage is applied to anode
15.
FIG. 7 is a plan view of a second embodiment of a electron multiplier
device of the first type in accordance with the invention using one
electron multiplier element. In the second embodiment, the aperture of
through-hole 2 is square in structure. Thus, the mask pattern is
simplified and the area of the aperture for the incident electrons is
larger than that in the first embodiment.
FIG. 8 is a plan view of a third embodiment of a electron multiplier device
of the first type accordance with the the invention, using one electron
multiplier element.
The aperture of through-hole 2 in the third embodiment is rectangular in
structure.
No two-dimensional information can be obtained by the electron multiplier
device of this structure, but high sensitivity is assured.
FIG. 9 is a plan view of the fourth embodiment of a electron multiplier
device of the first type in accordance with the invention, using one
electron multiplier element.
The aperture of through-hole 2 in the fourth embodiment is hexagonal in
structure.
No two-dimensional information can be obtained by the electron multiplier
device of this structure, but high sensitivity is assured.
FIG. 10 is a cross-sectional view of another embodiment of the
photomultiplier tube with an electron multiplier device in accordance with
the first type of the present invention, using one electron multiplier
element.
Photocathode 14 within vacuum envelope 9 is arranged against the first
plane (incident plane) of the front leaf of a dinode in the electron
multiplier device 70. The output signal is multiplied with a plurality of
leaves of dinodes in the electron multiplier device. Element 15 is the
anode.
FIG. 11 is a cross-sectional view of a further embodiment of the
photomultiplier tube wherein an electron multiplier device of the first
type of this invention is used.
The device in the embodiment shown in FIG. 11 consists of a plurality of
dinodes 70 of the conventional box type. Incident aperture 16 of the
photomultiplier tube is fastened to a dinode of box type. Anode 15 is used
to trap electrons multiplied by the electron multiplier device.
The second type of electron multiplier device according to the present
invention will be described hereinafter referring to FIGS. 12 through 16.
FIG. 12 is a plan view of a first embodiment of the electron multiplier
device of the second type in accordance with the invention. FIG. 13 is a
cross-sectional view of the embodiment shown in FIG. 12 in use. FIG. 14 is
an enlarged view of a part of the first embodiment shown in FIG. 13.
A plurality of through-holes 2 with circular apertures are bored on a
planar insulating substrate 1 made of glass (SiO.sub.2), and these are
inclined to the incident plane of the electron beam.
Through-holes 2 are bored by a photoetching process.
When insulating substrate 1 is exposed to the UV rays at an angle of the
inclination through a negative image mask whereon a pattern consisting of
the apertures and separation grooves are formed, a latent image is formed
on the glass plate constituting insulating substrate 1, corresponding to
the pattern of through-holes.
Thereafter, specific portions defined by the latent image are crystalyzed
by heat treatment. Crystalyzed portions are selectively etched by acid to
obtain a pattern of through-holes corresponding to the latent image
pattern.
Antimony (Sb) is evaporated onto a first inclined plane of each
through-hole, which is at an obtuse angle with respect to an upper surface
of the substrate 1 whereon through-holes 2 are bored to form a first
secondary electron emission layer 5 on this inclined plane. A second
inclined plane of each through-hole 2 at an obtuse angle with respect to
the lower surface of the substrate 1 whereon through-holes 2 are bored,
and is separated from the first secondary electron emission layer by
separation groove 7. Then, a second secondary electron emission layer 61
is formed onto this inclined plane by antimony evaporation.
The second secondary electron emission layer 61 is insulated from the upper
surface of substrate 1 so that the first secondary electron emission layer
61 cannot extend to the aperture in this side of the through-hole.
Connection means 3 to connect a plurality of secondary electron emission
layers 5 to the respective power supplies are formed on the first (upper)
surface of insulating substrate 1 and connection means 4 to connect a
plurality of second secondary electron emission layers 61 to the
respective power supplies are formed on the second (lower) surface of
insulating substrate 1.
The function of the electron multiplier device the second type in
accordance with the present invention will be described referring to FIG.
13.
The electron multiplier device built in accordance with the respect
invention is arranged within a vacuum envelope. Connection means 3 and 4
are connected to power supplies 10a and 10b, respectively. DC voltage
V.sub.2 fed from power supply 10b is greater DC voltage V.sub.1 fed from
power supply 10a.
The potential difference between V.sub.1 and V.sub.2 causes an acceleration
field toward second secondary electron emission layer 61 starting from the
first secondary electron emission layer 5.
Secondary electrons emitted from the first surface in the electron
multiplier device is incident on secondary electron emission layer 5.
Secondary electrons generated from the above electrons are incident on
second secondary electron emission layer 61 and then secondary electrons
are thus emitted.
FIG. 15 is a cross-sectional view of an embodiment of the second type of
the electron multiplier device in accordance with the present invention
consisting of three leaves of dinodes.
The first leaf in the electron multiplier device is fastened to the second
leaf in the electron multiplier device through insulating spacer 8a, so
that the through-holes in the second leaf are inclined in the opposite
direction to the through-holes in the first leaf.
The second leaf in the electron multiplier device is fastened to the third
leaf in the electron multiplier device through insulating spacer 8b, so
that the through-holes in the third leaf are inclined in the opposite
direction to the through-holes in the second leaf and in the same
direction as the through-holes in the first leaf. Power supplies 10a
through 10f (V.sub.5 >V.sub.4 >V.sub.3 >V.sub.2 >V.sub.1 >Vo) are
connected to the respective terminals of the electron multiplier device.
FIG. 16 is a cross-sectional view of an embodiment of the photomultiplier
tube wherein the electron multiplier device of the second type in
accordance with the present invention is provided within a vacuum
envelope.
Photocathode 14 is formed on the inner surface of the incident window of
vacuum envelope 9.
Anode 15 is provided corresponding to the emission aperture of the third
leaf in the electron multiplier device.
Power supplies are connected to the respective leaves of dinodes in the
electron multiplier device, and the highest DC voltage is applied to anode
15.
A plan view of the second embodiment of an electron multiplier device of
with the second type the present invention appears identical with FIG. 7.
In this second embodiment, the aperture of through-hole 2 is square in
structure. Holes on the insulating substrate can be finished in the same
manner as described above with respect to in the first embodiment.
A plan view of the third embodiment of an electron multiplier device with
the second type in accordance with the invention appears identical with
FIG. 8.
As shown in FIG. 8, the aperture of through-hole 2 in the third embodiment
is rectangular in structure.
No two-dimensional information can be obtained by the electron multiplier
device of this structure, but high sensitivity is assured.
A plan view of the fourth embodiment of the electron multiplier device of
the second type in accordance with the present invention appears identical
to FIG. 9.
The aperture of through-hole 2 in the fourth embodiment in hexagonal in
structure.
A cross-sectional view of another embodiment of a photomultiplier tube
built a the electron multiplier device in accordance with the second type
of the present invention appears just as in FIG. 11.
The device in this embodiment consists of a plurality of dinodes 70 of the
conventional box type. Incident aperture 16 of the photomultiplier tube is
fastened to a dinode of the box type. Anode 15 is used to trap electrons
multiplied by the electron multiplier device.
As described heretofore, the element of the electron multiplier device of
the first type accordance with present invention consists of an insulating
substrate with the first and second (upper and lower) surfaces which are
parallel with each other, a plurality of through-holes on the substrate
where first surfaces of the through-holes are at an obtuse angle with
respect to the first surface of substrate and second surfaces of the
through-holes against the first surfaces of the through-holes, a secondary
electron emission layer formed on the first surface of each through-hole
by depositing active materials onto the first surface of the substrate, a
conductive layer formed on the second surface of each through-hole which
is separated from the secondary electron emission layer, first connection
means to connect the secondary electron emission layer to the respective
power supplies through the first surface of the substrate, second
connection means to connect the conductive layer to the respective power
supply through the second surface of the substrate, and means to multiply
the electrons incident on the through-holes passing through the first
surface of the substrate by using the secondary electron emission layer,
and to apply a pair of DC voltages to the first and second connection
means so that the multiplied electrons are accelerated toward the second
surface of the substrate.
Such an electron multiplier device in accordance with the present invention
is composed of the above-mentioned elements, and thus the electron
multiplier device can be made compact.
For a small electron multiplier device, the electron transit time and its
variation can be reduced. This makes an electron multiplier device with
high time-resolution possible.
As described above, various types of photomultiplier tubes can be made with
this type of electron multiplier device.
These photomultipliers can be used for measuring instruments in many fields
because they are excellent in dimensional resolution and time resolution.
The normal electron multiplication factor (ratio of the number of output
electrons to that of incident electrons) in the electron multiplier device
of 10.sup.8 can be obtained by ten leaves of dinodes in the electron
multiplier device.
The leaf of each dinode in the electron multiplier device is 0.5 mm thick,
and thus the electron multiplier device can be made with a thickness of 5
mm or so.
The thickness of 5 mm is 1/8 of the thickness for the conventional electron
multiplier device.
As also described hereintofore, the element of the electron multiplier
device of the second type in accordance with the present invention
consists of an insulating substrate with the first and second (upper and
lower) surfaces which are parallel with each other, a plurality of
through-holes on the substrate where first surfaces of the through-holes
are at an obtuse angle with respect to the substrate and second surfaces
of the through-holes against the first surfaces of the through-holes, a
first secondary electron emission layer formed on the first surface of
each through-hole, a second secondary electron emission layer formed on
the second surface of each through-hole which is separated from the
secondary electron emission layer, first connection means to connect the
secondary electron emission layer to the respective power supplies through
the first surface of the substrate, second connection means to connect the
second secondary electron emission layer to the respective power supplies
through the second surface of the substrate, and means to multiply the
electrons incident on the through-holes passing through the first surface
of the substrate by using the secondary electron emission layer, and to
apply a pair of DC voltages to the first and second connection means so
that the multiplied electrons are accelerated toward the second surface of
the substrate.
Hence, secondary electrons are emitted twice from the incident electrons in
a single electron multiplier device. The through-holes on the substrate,
providing the electron multiplication function are arranged regularly, and
they can be used as an incident electron position detection device.
As described above, a number of electron multiplier devices are connected
in series to obtain a high electron multiplication factor.
The normal electron multiplication factor (ratio of the number of output
electrons to that of incident electrons) in the electron multiplier device
of 10.sup.8 can be obtained by five leaves of dinodes in this electron
multiplier device.
The leaf of dinode in the electron multiplier device is 0.5 mm thick, and
thus the electron multiplier device including the anode can be made with a
thickness of 4 mm or so because the insulating space is 0.25 to 0.35 mm
thick.
The thickness of 4 mm is 1/10 of the thickness for the conventional
electron multiplier device.
The electron multiplier device of the second type in accordance with the
present invention is composed of the above-mentioned elements, and thus
the electron multiplier can be made compact. For a small electron
multiplier device, the electron transit time and its variation can be
reduced.
This makes an electron multiplier device with high time-resolution
possible.
As described above, various types of photomultiplier tubes can be made with
this type of electron multiplier device.
Thes photomultipliers can be used for measuring instruments in many fields
because they are excellent in dimensional resolution and time resolution.
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