Voltage division circuit for a photomultiplier tube

• US 5,880,457 A
• Filed: 06/16/1997
• Issued: 03/09/1999
• Est. Priority Date: 06/14/1996
• Status: Expired due to Fees

• Current Assignee: Hamamatsu Photonics KK
• Original Assignee: Hamamatsu Photonics KK
• Inventors: Ema, Tsuyoshi, Tomiyama, Kimiyuki
• Primary Examiner(s): Allen, Stephone B.
• Application Number:
  US08/876,514
• Time in Patent Office: 631 Days
• Field of Search: 250/207, 250/214 VT, 250/363.02, 250/363.09, 313/105 R, 313/400, 313/535, 313/536, 315/383
• US Class Current: 250/207
• CPC Class Codes: H01J 43/30 Circuit arrangements not adapted to a particular application of the tube and not otherwise provided for

Abstract

A voltage division circuit for a photomultiplier tube in which an electron multiplication factor of the photomultiplier tube is readily changeable in a wide range with a low power consumption and without degrading a dynode'"'"'s collection efficiency and an output linearity. The voltage division portion 100 divides a high voltage (-HV) at a fixed voltage division ratio determined by the resistance values of resistors 111 to 116, 121 and 122, and 131 to 134 to thereby generate voltages applied to a focusing electrode 820, dynodes 831, 832 and 836 to 838. Another voltage division portion 300 includes a variable resistor 332 and generates voltages applied to the dynodes 833 to 835 by dividing the high voltage at a variable voltage division ratio upon operating the variable resistor.

Claims

1. A voltage division circuit for a photomultiplier tube which includes:

a photocathode which emits photoelectrons in response to light incident thereon;

a first dynode portion having at least one dynode, said first dynode portion receiving the photoelectrons emitted from said photocathode, multiplying the photoelectrons and emitting multiplied photoelectrons;

a second dynode portion having at least one dynode, said first dynode portion receiving the multiplied photoelectrons emitted from said first dynode portion, multiplying the multiplied photoelectrons and emitting further multiplied photoelectrons;

a third dynode portion having two or more dynodes, said third dynode portion receiving the multiplied photoelectrons emitted from said second dynode portion and emitting further multiplied photoelectrons; and

an anode receiving the further multiplied photoelectrons emitted from said third dynode portion,

a voltage division circuit which supplies relevant voltages to said photocathode, said first dynode portion, said second dynode portion, and said third dynode portion, comprising;

a first voltage division portion which is applied with a first side potential and a second side potential higher in voltage than the first side potential defining a high voltage and outputs voltages applied to said first dynode portion and said third dynode portion upon voltage dividing the high voltage at a predetermined voltage division ratio; and

a second voltage division portion which is applied with the first side potential and the second side potential of the high voltage and outputs a voltage applied to said second dynode portion upon voltage dividing the high voltage at a variable voltage division ratio.

2. The voltage division circuit according to claim 1, wherein said first voltage division portion comprises:

a first resistor array having a first number of resistors connected in series, said first resistor array having a first terminal connected to said photocathode, a second terminal, and at least one terminal connected to said at least one dynode in said first dynode portion;

a second resistor array having a second number of resistors connected in series, said second resistor array having a first terminal connected to said second terminal of said first resistor array, and a second terminal; and

a third resistor array having a third number of resistors connected in series, said third resistor array having a first terminal connected to the second terminal of said second resistor array, terminals connected respectively to the two or more dynodes of said third dynode portion, and a second terminal connected to the second side potential of the high voltage.

3. The voltage division circuit according to claim 1, wherein said first voltage division portion comprises:

a first resistor array having a first number of resistors connected in series, said first resistor array having a first terminal connected to said photocathode, a second terminal, and at least one terminal connected to said at least one dynode in said first dynode portion;

a second resistor array having a second number of resistors connected in series, said second resistor array having a first terminal connected to said second terminal of said first resistor array, and a second terminal;

a third resistor array having a third number of resistors connected in series, said third resistor array having a first terminal connected to the second terminal of said second resistor array, and a second terminal connected to the second side potential of the high voltage; and

a predetermined number of transistors which pass a voltage developed across said third dynode portion and voltages determined by said third resistor array to a predetermined number of dynodes closer in position to said anode, said predetermined number of transistors bypassing currents flowing in said predetermined number of dynodes.

4. The voltage division circuit according to claim 3, wherein said predetermined number of transistors are bipolar transistors.

5. The voltage division circuit according to claim 3, wherein said predetermined number of transistors are field effect transistors.

6. The voltage division circuit according to claim 1, wherein said second voltage division portion comprises:

a fourth resistor array having the first number of resistors connected in series, said fourth resistor array having a first terminal connected to said photocathode, and a second terminal;

a fifth resistor array having the second number of resistors connected in series, said fifth resistor array having a first terminal connected to said second terminal of said fourth resistor array, terminals connected to said at least one dynode in said second dynode portion, and a second terminal;

a variable resistor portion having a first terminal connected to the second terminal of said fourth resistor array, and a second terminal, said variable resistor portion being connected in parallel to said fifth resistor array; and

a sixth resistor array having the third number of resistors connected in series, said sixth resistor array having a first terminal connected to both the second terminal of said fifth resistor array and the second terminal of said variable resistor portion, and a second terminal connected to the second side potential of the high voltage.

7. A voltage division circuit for a photomultiplier tube which includes:

a photocathode which emits photoelectrons in response to light incident thereon;

a first dynode portion having at least one dynode, said first dynode portion receiving the photoelectrons emitted from said photocathode, multiplying the photoelectrons and emitting multiplied photoelectrons;

a second dynode portion having at least three dynode, said first dynode portion receiving the multiplied photoelectrons emitted from said first dynode portion, multiplying the multiplied photoelectrons and emitting further multiplied photoelectrons;

a third dynode portion having two or more dynodes, said third dynode portion receiving the multiplied photoelectrons emitted from said second dynode portion and emitting further multiplied photoelectrons; and

an anode receiving the further multiplied photoelectrons emitted from said third dynode portion,

the voltage division circuit which supplies relevant voltages to said photocathode, said first dynode portion, said second dynode portion, and said third dynode portion, comprising;

a first voltage division portion which is applied with a first side potential and a second side potential higher in voltage than the first side potential defining a high voltage and outputs voltages applied to said first dynode portion, said third dynode portion, and more than one predetermined dynodes in said second dynode portion excluding a first-stage dynode and a final-stage dynode in said second dynode portion upon voltage dividing the high voltage at a predetermined voltage division ratio; and

a second voltage division portion which is applied with a voltage output from said first voltage division portion and the second side potential of the high voltage and outputs voltages applied to dynodes in said second dynode portion other than said more than the predetermined dynodes upon voltage dividing the high voltage at a variable voltage division ratio.

8. The voltage division circuit according to claim 7, wherein said first voltage division portion generates a voltage applied to a dynode disposed substantially at a center in said second dynode portion.

9. The voltage division circuit according to claim 7, wherein said first voltage division portion comprises:

a first resistor array having a first number of resistors connected in series, said first resistor array having a first terminal connected to said photocathode, a second terminal, and at least one terminal connected to said at least one dynode in said first dynode portion;

a second resistor array having a second number of resistors connected in series, said second resistor array having a first terminal connected to said second terminal of said first resistor array, a terminal connected to the predetermined dynode in said second dynode portion, and a second terminal; and

a third resistor array having a third number of resistors connected in series, said third resistor array having a first terminal connected to the second terminal of said second resistor array, terminals connected respectively to the two or more dynodes of said third dynode portion, and a second terminal connected to the second side potential of the high voltage.

10. The voltage division circuit according to claim 7, wherein said first voltage division portion comprises:

a first resistor array having a first number of resistors connected in series, said first resistor array having a first terminal connected to said photocathode, a second terminal, and at least one terminal connected to said at least one dynode in said first dynode portion;

a second resistor array having a second number of resistors connected in series, said second resistor array having a first terminal connected to said second terminal of said first resistor array, a terminal connected to the predetermined dynode in said second dynode portion, and a second terminal;

a third resistor array having a third number of resistors connected in series, said third resistor array having a first terminal connected to the second terminal of said second resistor array, and a second terminal connected to the second side potential of the high voltage; and

a predetermined number of transistors which pass a voltage developed across said third dynode portion and voltages determined by said third resistor array to a predetermined number of dynodes closer in position to said anode, said predetermined number of transistors bypassing currents flowing in said predetermined number of dynodes.

11. The voltage division circuit according to claim 10, wherein said predetermined number of transistors are bipolar transistors.

12. The voltage division circuit according to claim 10, wherein said predetermined number of transistors are field effect transistors.

13. The voltage division circuit according to claim 7, wherein said second voltage division portion comprises:

a fourth resistor array having the first number of resistors connected in series, said fourth resistor array having a first terminal connected to said photocathode, and a second terminal;

a fifth resistor array having the second number of resistors connected in series, said fifth resistor array having a first terminal connected to said second terminal of said fourth resistor array, terminals connected to dynodes in said second dynode portion other than said predetermined dynode, and a second terminal;

a variable resistor portion having a first terminal connected to the second terminal of said fourth resistor array, and a second terminal, said variable resistor portion being connected in parallel to said fifth resistor array; and

a sixth resistor array having the second number of resistors connected in series, said sixth resistor array having a first terminal connected to both the second terminal of said fifth resistor array and the second terminal of said variable resistor portion, and a second terminal connected to the second side potential of the high voltage.