JPS626191A - Constant-voltage power source for superconductor radiation detector - Google Patents

Abstract

PURPOSE:To obtain a radiation detector whose sensitivity and resolution are excellent, by detecting a current flowing to a superconductor of a superconductive tunnel junction, in a state that a potential difference across said superconductor is kept constant. CONSTITUTION:A potential difference across a superconductor 1 of a superconductive tunnel junction is detected through terminals 6, 7, and a current is made to flow between current terminals 8, 9 so that its potential difference becomes constant by a constant-voltage power source 3. When a radiant ray is made incident on the superconductor 1 in such a state, its current value is varied, therefore, by detecting its variation by a resistance 5, the radiant ray is detected. In this way, the radiant ray can be detected with a high accuracy.

Description

[Detailed Description of the Invention] Since the energy gap of a superconductor is as small as about 1 meV, which is several tenths of that of a semiconductor, a superconductor radiation detector using a superconducting tunnel junction is compared to a semiconductor detector. However, it has the potential to have much better sensitivity and resolution. The present invention relates to a constant voltage power supply for bringing out the excellent performance of a superconducting radiation detector.

Conventionally, in radiation detectors such as semiconductor detectors, as shown in Figure 1, a detector (4) and a load resistor (5) are connected in series to a constant voltage power supply (3), and radiation is detected by the incidence of radiation. The voltage change occurring in the detector (4) is extracted as a signal from the load resistor (5) or the detector (4).

That is, the potential difference between both ends of the radiation detector was not kept constant.

In the case of Figure 1, if the charge generated in the radiation detector (4) by radiation is Q and the capacitance of the radiation detector (4) is C, then the maximum voltage change that can occur across the detector due to Q is Q. /C. In superconducting radiation detectors, because C is large due to the thin tunnel barrier, and because the energy gap is small (several mV or less when converted to voltage), the conventional voltage bias method shown in Figure 1 cannot handle a sufficiently large voltage signal. It becomes difficult to take out.

As shown in FIG. 2, the present invention detects a potential difference between both ends of a superconducting radiation detector (1) through voltage terminals (6) and (7), and maintains the potential difference constant through a current terminal ( 8
)% (91), and the change in the current flowing through the constant voltage bias superconductor radiation detector (1) when radiation is incident can be extracted as a signal. Voltage terminal (6) and current terminal (8)
It is also possible to use one terminal for both purposes.

FIG. 3 shows an embodiment using an operational amplifier a.

In this example, the potential difference between both ends of the superconducting radiation detector (1) is kept equal to the voltage of the standard voltage source αυ, and the current change when radiation is incident is expressed as a voltage signal from the signal output terminal 03 of the signal output terminal a. Alternatively, the current signal can be extracted directly from the signal output terminal by removing the resistor a4.

A low constant voltage source of about 1 mV is required as the standard voltage source αυ. As this low constant voltage source, it is possible to use a voltage source such as an ordinary battery whose voltage is divided by a resistor, but it is possible to use the diode-like properties of superconducting tunnel junctions (2), which have even better stability especially at low temperatures. The fourth embodiment of the low constant voltage source
As shown in the figure. A low constant voltage source in which the voltage of a battery or the like is simply divided by a resistor has the disadvantage that the output voltage easily changes due to changes in the battery voltage or resistance value. A low constant voltage source that utilizes the diode-like properties of superconducting tunnel junctions can greatly improve this drawback.

[Brief explanation of drawings]

FIG. 1 is a connection diagram of a conventional constant voltage power supply and a radiation detector. FIG. 2 is a connection diagram of the constant voltage power supply and superconductor radiation detector of the present invention. FIG. 3 shows an embodiment of the present invention. Figure 4 shows Example 0 of a standard voltage power supply using a superconducting tunnel junction. Symbol (1): Superconducting radiation detector (2): Superconducting tunnel junction (3): Constant voltage power supply (4): Radiation detection (5): Load resistance (6): Voltage terminal (Crab voltage terminal (8): Current terminal (9
): Current terminal OI: Operational amplifier (Iυ: Standard voltage source α3: Signal output terminal aa: Signal output terminal αa: Resistor

Claims (2)

[Claims] (1) The potential difference between both ends of a superconducting radiation detector (1) using a superconducting tunnel junction is kept constant;
) A constant-voltage power supply for active superconductor radiation detectors that makes it possible to extract transient current changes as a signal due to the incidence of radiation. ...(*Requirements) (2) A standard voltage equal to the potential difference applied across the superconducting radiation detector (1) is applied to the other superconducting tunnel junction (2).
A standard voltage power supply produced using