LOW ENERGY PARTICLE COUNTER WITH ONE-DIMENSIONAL POSITION SENSING

• US 3,691,382 A
• Filed: 10/30/1970
• Issued: 09/12/1972
• Est. Priority Date: 10/30/1970
• Status: Expired due to Term

• Current Assignee: Toivo A. Somer
• Original Assignee: Toivo A. Somer
• Inventors: Somer, Toivo A.
• Primary Examiner(s): Borchelt, Archie R.
• Application Number:
  US05/085,592
• Time in Patent Office: 683 Days
• Field of Search: 250/83R,83.3R,715R,83J,207,22M,203,213VT,211K,41.9D,49.5C 356/206,229 313/103 324/71EB
• US Class Current: 250/336.1
• CPC Class Codes: G01T 1/28 with secondary-emission detectors
• CPC Class Codes: G01T 1/2957 using channel multiplier arrays channel multipliers H01J43/18; G01T1/1645 takes precedence

Abstract

The invention provides one-dimensional position information relating to the detection of low energy particles such as photons or charged particles and also provides the capability of counting the detected particles. A particle detection device of known type is combined with a linear resistor which splits the charge emanating from the detection device in a ratio which is proportional to the position of the charge on the linear resistor. An analog divider divides the proportional charge on the linear resistor into the output charge from the detection device to thereby yield an output indication which is independent of the statistically variable total charge emanating from the detection device. The output of the divider is, therefore, an indication of the position at which the charge emanated from the detection device, and also shows that a detected particle impacted the input end of the detector. Accordingly, the number of detectable charges which impinged upon the input end of the detector within a chosen period of time can be counted, and the positions at which they struck the detector can be recorded.

Claims

1. A one-dimensional position indicating and counting radiation detection system comprising:

a radiation detection element for receiving the radiation to be detected and yielding an output charge in response to the radiation impinging upon said element;

first charge collection means receiving said output charge, said charge collection means being coupled to a first input of a divider means, so that said divider receives an input proportional to said output charge;

charge splitting means receiving said output charge, said charge splitting means splitting said output charge into a proportional charge indicative of the position at which said output charge strikes said splitting means, the output of said splitting means being coupled to a second input of said divider so that a voltage proportional to said proportional charge is input to said divider;

said divider serving to divide said proportional charge voltage by said output charge voltage so that the output of said divider is indicative of the position at which said radiation impinged upon said detection element.

2. The system of claim 1 wherein said radiation detection element is an electron multiplier, said radiation is low energy and said divider is an analog divider.

3. The system of claim 1 wherein said charge splitting means is a linear resistive element, one end of said resistive element being grounded.

4. The system of claim 3 wherein said linear resistive element is coupled to said divider through an amplifier having substantially zero input impedance.

5. The system of claim 4 wherein said output charge Q striking said resistive element is split according to the proportion Q (X/L) where:

X the distance from said grounded end to the point at which said charge strikes said resistive element, and L the total length of said resistive element.

6. The system of claim 5 wherein said first charge collection means receives said charge Q from said detection element so that said first input of said divider receives an input Q and said second input of said divider receives an input Q (X/L).

7. The system of claim 6 wherein said divider performs the operation so that the output of said divider is K (K/L) where K is a constant determined by the characteristics of said divider.

8. The system of claim 7 wherein said radiation detection element is a windowless electron multiplier capable of detecting low energy photons or charged particles.

9. The system of claim 8 wherein the voltage input to said first divider input is indicative of said output charge from said multiplier and the output of said divider is indicative of the position at which the detected energy impinged upon said multiplier so that said system yields information relative to the position said energy impacted with said electron multiplier;

and the total number of output indications in a given period of time is equal to the number of detectable particles impinging upon said detection element in said period of time.