JPH0210645A - Channel electron multiplier - Google Patents

Abstract

PURPOSE: To eliminate an unnecessary signal and noise by using glass containing a lead compound selected so as to restrict the unnecessary signal to a specified value. CONSTITUTION: Glass containing a lead compound selected so as to restrict an unnecessary signal to 0.1 or less per cm<2> sec is used. The composition of the glass is 30-35wt.% SiO2 , 50-57wt.% PbO, 2-10wt.% Cs2 O, 0-5wt.% ΣMgO+ CaO+SrO+BaO, 0.1-1wt.% ΣAl2 O3 +ZrO2 +TiO2 +Nb2 O5 . The ratio of Si to Pb is 2.0-2.4 in the molar ratio of SiO2 to PbO.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to channel electron multipliers, and more particularly to microchannel plates (MCPs) that have been improved to eliminate unwanted signals and noise from entering the channel electron multipliers.

(Summary of the invention) Figure M1 and Figure 2 show the input array 22 and the output array 2.
4 (only top left detail shown), each array has a number of channel sections with the same inner channel diameter and center-to-center spacing of the channels. Channel members 23 of array 22.24.
The inner diameter of the channel at 25 is 25 microns.

We have discovered that the new glass can be used to advantageously create low-noise channel electron multipliers, especially low-noise microchannel plates. This glass consists essentially of the following (% by weight):

Si0□ 30~3
5%Pb0
5G~57%Cs, 02~10% ΣMgO+CaO+SrO+BaOO-5%ΣAl2O
, +2rO, +TiO□+Nb, 0. 0.1-
1% Here, the ratio of Si to Pb is 2.0 to 2.4 expressed as the molar ratio of SiO2 to PbO.

EXAMPLE In a preferred example, the only alkali oxides included in the ingredient list are Cs and O.

The glass for making the array 22,24 has the following components:

Component Weight % PbO54.9 SiO□ 34.8Cs2O
5.9BsO4,0 AI2O. O,! As2O50
,2 As is clear from the table, this glass does not contain both rubidium and potassium, which have been found to increase unwanted signals and noise. Furthermore, although the lead oxide in the disclosed glass is selected from a range of commercially available lead oxides, some of the commercially available lead oxides induce more unwanted signals than others when used, so the overall composition is In addition to the above, the unnecessary signal is less than 1 per 10 seconds per square centimeter of the channel surface (i.e. c++"se
It is effective to select one that suppresses unnecessary signals to 0.1 or less per e.

The term ``spurions sig++al'' refers here to a signal with a length of 1 mm and a channel diameter of 10 mm.
It is defined as measured by the number of electrons originating from a wall source that appears at the output of a micron channel electron multiplier.

By removing rubidium and potassium and selecting lead oxide as described above, the presence of radioactive isotopes and trace elements in the glass is reduced. Otherwise,
These will naturally generate electrons in the multiplier wall that will enter the channel from the multiplier wall and cause unwanted signals.

In the most preferred series of embodiments, suppression can be as low as 0.03 per cm"sec and 0.01°0.
It can even be suppressed down to 0.003 and 0.001.

Other currently preferred embodiments of the glass of the present invention are as follows.

Oxide Raw material Weight% Compound weight (kg) 510
2 5102 34.25 6.87 kgP
bOPb, 0454.05 +1.04 klC
S2O CsC0,7,561,75kgB2OB
a(Cox)2 3.94 1. +13k
gAl2Os Al(OH)x O, 190,
06JAs2O. ^s=o, o, lo
Microchannel plates made by methods known in the art (including of course a reduction step) showed very good band current and electron gain as well as low dark noise.

By using such components in channel electron multipliers, potassium and rubidium could be eliminated and excellent manufacturing and operating characteristics could be achieved.

Although weights and mole percentages of oxides are described herein, it is understood in the art that various other metal element compounds can be substituted.

Other embodiments within the scope of the claims may occur to those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a side view of the microchannel plate, and FIG. 2 is a schematic sectional view taken along line 2-2 in FIG. 2O-m-microchannel plate, 2z-m-manual array, 2E-mountain array, 23, 25--channel member, :=,) Engraving (no change in content) FIG. FIG.2

Claims (1)

[Claims] 1. Combining with other components of the glass to reduce unnecessary signals to cm^2
A channel electron multiplier made of glass containing a lead compound selected to be effective in suppressing less than 0.1 per sec. 2. The multiplier according to claim 1, wherein the lead compound is selected to suppress the unnecessary signal to 0.03 per cm^2 sec or less. 3. The multiplier according to claim 2, wherein the lead compound is selected to suppress the unnecessary signal to less than 0.01 per cm^2 sec. 4. The multiplier according to claim 1, which does not contain rubidium. 5. The multiplier according to claim 1, which does not contain potassium. 6. Multiplier according to claim 1, containing neither rubidium nor potassium. 7. The multiplier of claim 3, wherein the lead compound is selected to suppress the unnecessary signal to 0.003 per cm^2 scc or less. 8. The multiplier according to claim 7, wherein the lead compound is selected to suppress the unnecessary signal to 0.001 per cm^2 sec or less. 9. In weight%, SiO_2 30-35% PbO 50-57% Cs_2O 2-10% ΣMgO+CaO+SrO+BaO 0-5%ΣAl_
2O_3+ZrO_2+TiO_2+Nb_2O_5
0.1 to 1%, wherein the ratio of Si to Pb is 2.0 to 2.4, expressed as the molar ratio of SiO_2 to PbO. 10. Glass according to claim 9, wherein the alkali oxide present therein consists essentially only of cesium oxide. 11. A glass consisting essentially of, in weight percent, SiO_2 34.25 PbO 54.06 Cs_2O 7.56 B_2O 3.94 Al_2O_3 0.19. A channel electron multiplier made of the glass according to claim 12, 9, 10, or 11. 13. A microchannel plate as defined in claim 12.