GB2167450A - Secondary electron emission surface - Google Patents
Secondary electron emission surface Download PDFInfo
- Publication number
- GB2167450A GB2167450A GB08524036A GB8524036A GB2167450A GB 2167450 A GB2167450 A GB 2167450A GB 08524036 A GB08524036 A GB 08524036A GB 8524036 A GB8524036 A GB 8524036A GB 2167450 A GB2167450 A GB 2167450A
- Authority
- GB
- United Kingdom
- Prior art keywords
- secondary electron
- electron emission
- emission surface
- aluminium metal
- forming
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
- H01J1/02—Main electrodes
- H01J1/32—Secondary-electron-emitting electrodes
Landscapes
- Common Detailed Techniques For Electron Tubes Or Discharge Tubes (AREA)
Abstract
A secondary electron emission surface is formed by oxidising the surface of an aluminium metal layer deposited onto a plate of nickel or another metal or onto a ceramic plate by vacuum deposition.
Description
SPECIFICATION
Secondary electron emission surface
The present invention relates to a secondary electron emission surface used for example to fabricate a dynodefor a photomultipliertube, secondary electron multiplier tube or image orthicon tube.
When electrons are incident on a metal surface, the incident primary electrons are reflected and secondary electrons are emitted from the metal. The surface from which the secondary electrons are emitted is called a secondary electron emission surface.
The conventional secondary electron emission surface is made with a nickel substrate on the surface of which antimony is evaporated and an alkali metal is absorbed, or made with a berylliumcopper or magnesium-silver alloy substrate which is subjected to either heat treatment or oxidization and on the surface of which a beryllium oxide layer or magnesium oxide layer is formed.
The fabrication of the conventional secondary electron emission surface made with a nickel substrate by means of the former method is a rather complicated process and it must be performed by skilled personnel.
The secondary electron emission surface made with a beryllium-copper or magnesium-silver alloy substrate by means of the latter method has a short life because the secondary electron multiplication ratio thereof decreases in a short period of time after the start of using the secondary electron emission surface.
The object of the present invention is to provide a secondary electron emission surface with a secondary electron multiplication ratio which remains unchanged for a long period of time.
The present invention provides a secondary electron emission surface formed by oxidation of an aluminium metal surface.
In a preferred embodiment of the present invention a layer of aluminium metal is deposited onto a surface of a nickel plate substrate, by vacuum deposition.
In accordance with another aspect of the invention there is provided a method of forming a secondary electron emission surface comprising oxidising an aluminium metal surface.
Certain embodiments of the invention will now be described in detail by way of example only and with reference to the accompanying drawings in which:
Figure 1 in a schematic view of a photomultiplier tube including dynodes having secondary electron emission surfaces constructed in accordance with the present invention.
Figures 2(a), 2(b), 2(c) and 2(d) are perspective views of the dynodes of the photomultiplier tube of
Figure 1, having the secondary electron emission surfaces according to this invention.
Figure 3 is a graph showing the variation of anode currents with time for a particular light intensity for a photomultiplier tube having secondary electron emission surfaces constructed in accordance with the present invention and a photomultipliertube having secondary electron emission surfaces constructed in accordance with the conventional technique.
The embodiment of the present invention described below deals with a secondary electron emission surface for use in a photomultiplier tube.
In Figure leach of the reference numerals 1 through 4 indicates a dynode, reference numeral 5 indicates an incident window, 6 indicates a focussing electrode, 7 indicates a photocathode, 8 indicates an anode, 9 indicates a lead electrode and 10 indicates an envelope.
The secondary electron emission surfaces are, as shown in Figures 2(a), 2(b), 2(c) and 2(d), formed on inner walls 1a through 4a of dynodes 1 through 4, respectively. Each secondary electron emission surface is made of aluminium oxide formed on the aluminium metal surface. The aluminium metal is formed by vacuum deposition onto a nickel plate substrate.
The fabrication process for the secondary electron emission surface in accordance with the present invention will be described hereinafter.
The secondary electron emission surfaces are fabricated by both evaporation and storage processes.
Thin aluminium layers, each having a thickness of approximately 50 mu, are formed on inner walls la through 4a of the surfaces of nickel plate substrates finished to constitute dynodes such as 1 through 4 as shown in Figures 2(a) through 2(d) during a vacuum deposition process.
The nickel plate substrates on which aluminium has been deposited by the vacuum deposition process are held at room temperature (approx. 25"C) in clean ambient air for 12 hours during a storage process. An aluminium oxide layer with a thickness of approximately 5 mu is formed on each surface of aluminium during the storage process.
The secondary electron emission surface is then built in envelope 10 as shown in Figure 1.
Envelope 10 is exhausted to obtain a vacuum and photocathode 7 is formed by depositing antimony, sodium, potassium and caesium onto the inner wall of incident window 5.
Evaporation sources 15 and 16 are arranged in a location between focussing electrode 6 and incident window 5. The sources are evaporated by electric current heating or high frequency induction heating.
A new type of photomultipliertube (called type A multiplier tube) having secondary electron emission surfaces built in accordance with the present invention was compared in an experiment with another type of photomultiplier tube of the same structure (called type B photomultipliertube) having secondary electron emission surfaces comprising beryllium oxide layers formed on the surfaces of beryllium-copper alloy substrates.
Avoltageof-1200volts DC was applied to photocathode 7, and a voltage of -1000 volts DC was applied to focussing electrode 6 and first dynode 1. Differences in voltage between the respective adjacent dynodes were set at -100 volts and anode 8 was set at zero volts.
The anode current was at first set at 100 uA by adjusting the incident light power with an aperture controller. Then, the anode currents were measured at subsequent time intervals, without changing the intensity of incident light. Measurement was carried out for 100 samples of type A photomultiplier tubes and for 100 samples of type B photomultiplier tubes.
Data in Figure 3 shows the averaged values for the respective samples.
Figure 3 shows the variation of anode currents with time for the photomultipliertubes having secondary electron emission surfaces in accordance with the present invention and the conventional technique, respectively, when a certain intensity of light is incident.
Data for types A and B is identified by curves (A) and (B). The conventional type B photomultiplier tube exhibits performance degradation in 100 hours after the start of operation while the type A photomultipliertube exhibits performance stability, the anode current remaining almost unchanged after 100 hours.
The secondary electron emission surface in the preferred embodiment of the present invention is made of aluminium oxide formed on an aluminium layer deposited onto a nickel plate substrate. The nickel plate can be replaced with a plate of another metal or by a ceramic plate and an aluminium layer can be deposited thereon.
The aluminium oxide layer can also be made by anodic oxidization.
As described heretofore, this invention presents a secondary electron emission surface, which can be fabricated easily and maintains its initial secondary electron multiplication ratio for a long period of time when used.
Claims (18)
1. A secondary electron emission surface formed by oxidation of an aluminium metal surface.
2. A secondary electron emission surface as claimed in claim 1,wherein aluminium metal is deposited onto a surface of a substrate prior to oxidation.
3. A secondary electron emission surface as claimed in claim 2 in which said substrate comprises a nickel plate.
4. A secondary electron emission surface as claimed in claim 2 in which said substrate comprises a ceramic plate.
5. A secondary electron emission surface as claimed in claim 2, 3 or 4 in which said aluminium metal is deposited onto said surface of said substrate by vacuum deposition.
6. A secondary electron emission surface as claimed in any preceding claim wherein said aluminium metal surface is oxidised by storing the metal in clean ambient air.
7. A secondary electron emission surface as claimed in any of claims 1 to 5 wherein said aluminium metal surface is oxidised by anodic oxidation.
8. A method of forming a secondary electron emission surface comprising oxidising an aluminium metal surface.
9. A method of forming a secondary electron emission surface as claimed in claim 8 comprising depositing aluminium metal onto a surface of a substrate prior to oxidation.
10. A method of forming a secondary electron emission surface as claimed in claim 9 in which said substrate comprises a nickel plate.
11. A method of forming a secondary electron emission surface as claimed in claim 9 in which said substrate comprises a ceramic plate.
12. A method of forming a secondary electron emission surface as claimed in claim 9, 10 or 11 further comprising depositing said aluminium metal onto said surface of said substrate by vacuum deposition.
13. A method of forming a secondary electron emission surface as claimed in any of claims 8 to 12 wherein said aluminium metal surface is oxidised by storing the metal in clean ambient air.
14. A method of forming a secondary electron emission surface as claimed in any of claims 8 to 12 wherein said aluminium metal surface is oxidised by anodic oxidation.
15. A photomultiplier tube including at least one dynode having a secondary electron emission surface formed by oxidation of an aluminium metal surface.
16. A secondary electron emission surface substantially as herein described with reference to the accompanying drawings.
17. Methods of making a secondary electron emission surface, substantially as herein described with reference to the accompanying drawings.
18. A photomultipliertube substantially as herein described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59206821A JPS6185747A (en) | 1984-10-02 | 1984-10-02 | Secondary electron emission surface |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8524036D0 GB8524036D0 (en) | 1985-11-06 |
| GB2167450A true GB2167450A (en) | 1986-05-29 |
Family
ID=16529638
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08524036A Withdrawn GB2167450A (en) | 1984-10-02 | 1985-09-30 | Secondary electron emission surface |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS6185747A (en) |
| DE (1) | DE3533520A1 (en) |
| GB (1) | GB2167450A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0812772B2 (en) * | 1987-04-12 | 1996-02-07 | 浜松ホトニクス株式会社 | Photomultiplier tube |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1107869A (en) * | 1964-04-06 | 1968-03-27 | Fujitsu Ltd | Improvements in or relating to metal film resistors |
| GB2023333A (en) * | 1978-06-14 | 1979-12-28 | Philips Electronic Associated | Electron multipliers |
| GB2045808A (en) * | 1979-04-02 | 1980-11-05 | Philips Electronic Associated | Method of forming a secondary emissive coating on a dynode |
| GB2075556A (en) * | 1980-05-09 | 1981-11-18 | Philips Nv | Forming a thermally black surface on metals |
| EP0068277A1 (en) * | 1981-06-30 | 1983-01-05 | International Business Machines Corporation | Method for passivating aluminum-based metallizations |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1216497A (en) * | 1968-06-18 | 1970-12-23 | Mullard Ltd | Improvements in or relating to electron multiplier and like devices |
| US3739216A (en) * | 1971-07-30 | 1973-06-12 | Zenith Radio Corp | Secondary electron multipliers with single layer cermet coatings |
| GB2048561B (en) * | 1979-04-02 | 1983-02-23 | Philips Electronic Associated | Method of forming a secondary emissive coating on a dynode |
-
1984
- 1984-10-02 JP JP59206821A patent/JPS6185747A/en active Pending
-
1985
- 1985-09-20 DE DE19853533520 patent/DE3533520A1/en not_active Ceased
- 1985-09-30 GB GB08524036A patent/GB2167450A/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1107869A (en) * | 1964-04-06 | 1968-03-27 | Fujitsu Ltd | Improvements in or relating to metal film resistors |
| GB2023333A (en) * | 1978-06-14 | 1979-12-28 | Philips Electronic Associated | Electron multipliers |
| GB2045808A (en) * | 1979-04-02 | 1980-11-05 | Philips Electronic Associated | Method of forming a secondary emissive coating on a dynode |
| GB2075556A (en) * | 1980-05-09 | 1981-11-18 | Philips Nv | Forming a thermally black surface on metals |
| EP0068277A1 (en) * | 1981-06-30 | 1983-01-05 | International Business Machines Corporation | Method for passivating aluminum-based metallizations |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8524036D0 (en) | 1985-11-06 |
| DE3533520A1 (en) | 1986-04-03 |
| JPS6185747A (en) | 1986-05-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |