JP2014196983A - Particle/photon detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particle/photon detector compatibly having a high response speed, a large sensitive area, less heat generation, and high signal strength, while capable of preventing generation of a non-sensing region.SOLUTION: When particles or photons collide with a detection unit 12 that is retained in a superconductive state to transfer the detection unit to a normal conductive state, a particle/photon detector 10 outputs an electric signal indicating a detection of particles or photons. The particle/photon detector 10 includes: a plurality of detection units 12 connected in series; and two wiring lines 26 and 28 arranged in parallel that are provided in parallel with the plurality of detection units 12 that are connected in series. Respective connection parts of adjacent detection units 12 are alternately connected to the two wiring lines 26 and 28 arranged in parallel via resistors 14, and electric signals from the plurality of detection units are read through at least one of the two wiring lines 26 and 28 arranged in parallel.

Description

  The present invention relates to a particle / photon detector that detects particles and photons using a detection unit in a superconducting state.

  Research on particle / photon detectors using a detector formed by forming fine wiring with a thin film of superconductor has been conducted. In this particle / photon detector, the detection part of the superconductor is cooled below the superconducting transition temperature, and a current smaller than the critical current (current that destroys the superconducting state) flows through the wiring forming the detection part. used. When particles or photons collide with the wiring of the detection unit thus made in the superconducting state, the value of the critical current in the microregion at the collision point decreases, so that the superconducting state is broken in the microregion, and the normal conducting state To metastasize. As a result, the wiring forming the detection unit has a slight resistance value, and a pulse-like voltage change reflecting this change in resistance value is output from the detection unit as an electrical signal. By observing this electrical signal, it is possible to detect particles or photons that have arrived at the detector (see, for example, Patent Document 1).

  In general, in the particle / photon detector, the response (that is, the time until the detection unit returns from the normal state to the superconducting state before the collision of the particle or the photon to the state where the particle or the photon can be detected again). It must be fast and have a large sensitive area. The response speed when detecting particles and photons in the particle / photon detector is determined by the kinetic inductance L of the superconductor detector and the resistance value R of the readout circuit that receives the electrical signal from the detector, A time constant (time constant at which the pulsed electric signal falls in the readout circuit) τ, which is an index of the response speed, is given by τ = L / R (for example, Non-Patent Document 1). By the way, in the high-speed signal readout circuit and transmission line, impedance matching is performed in order to avoid reflection, and the characteristic impedance is typically 50Ω or 75Ω and cannot be changed greatly. I can't change that much. Therefore, in order to increase the response speed of the particle / photon detector, it is common to design the kinetic inductance L to be small. On the other hand, the kinetic inductance L in the superconductor wiring forming the detection unit is proportional to the length of the wiring and inversely proportional to the line width and thickness. Increasing the line width and thickness lowers the detection efficiency and makes it difficult to return to the superconducting state after transitioning to the normal conducting state. Therefore, when the kinetic inductance L is reduced, the length is generally shortened. Done. For example, a response speed of about 50 picoseconds has been reported by a detection unit having a size of several microns (Non-Patent Document 2). This response speed is faster than that of existing detectors such as microchannel plates, photomultiplier tubes and avalanche photodiodes. The particle / photon detector using the superconductor wiring detection unit determines the arrival time of particles or photons. It can be detected precisely.

JP 2004-214293 A JP 2009-021478 A

Andrew et al., "Kinetic-inductance-limited reset time of superconducting nanowire photon counter", Applied Physics Letters, 2006, vol.88, pp111-116 Komeev et al., "Sensitivity and gigahertz counting performance of NbN superconducting single-photon detectors", Applied Physics Letters, 2004, vol.84, p5388 Casaburi et al., “Subnanosecond time response of large-area superconducting stripline detectors for keV molecular ions”, Appl. Phys. Lett. 94, 212502 (2009) Zen et al., "1mm ultrafast superconducting stripline molecule detector", Appl. Phys. Lett. 95, 172508 (2009) Suzuki et al., “Time Resolution Improvement of Superconducting NbN Stripline Detectors for Time-of-Flight Mass Spectrometry”, Appl. Phys. Express, Vol.1, p.031702, 2009

  As described above, a general particle / photon detector is required to have a fast response and a large sensitive area. However, as described above, if the length of the superconductor wiring forming the detection portion is shortened in pursuit of high-speed response, the sensitive area is inevitably reduced, and the practicality as a detector is impaired. This problem has been solved by connecting the detection units in parallel and reducing the effective inductance (for example, Patent Document 2, Non-Patent Document 3, and Non-Patent Document 4).

However, connecting in parallel causes the following three problems.
(1) The first problem is that the current flowing through the entire detector increases, heat generation increases, and the low temperature cannot be maintained. In the detector, there is no heat generation because the resistance value is zero on the wiring using the superconductor, that is, on the detection unit. On the other hand, the path (hereinafter referred to as a transmission line) for introducing a current into the detector from the outside increases the temperature of the low temperature part (particularly the detection part) due to the inflow of heat from the outside through the transmission line. In order to prevent this, a material having a low thermal conductivity, such as brass or stainless steel, is used. Brass and stainless steel have low conductivity, but the transmission line wiring has a resistance value of around 1Ω. The heat generation amount Q in the transmission line is expressed as Q = Ic ² Rc where the current value is Ic and the resistance value is Rc, and M detection units are connected in parallel to supply the same current value I to each detection unit. Then, Ic = MI, and the amount of heat generated in the transmission line is Q = (MI) ² × Rc = M ² I ² × Rc, which is proportional to the square of the number M of parallel detectors, that is, M ² . There are limits to parallelization. For example, in the case of a wiring having a resistance value of 1Ω, the heat generation amount Q in the transmission line wiring is expressed as Q = I ² Rc as described above. Therefore, when a current of 100 mA is passed, the heat generation amount reaches 10 mW. On the other hand, the cooling capacity of the refrigerator for cooling the detection unit is typically 1 W or less, and the heat generation amount must be 10 mW or less in order to stably maintain a low temperature. Therefore, considering that the value of the current supplied to one detection unit of the particle / photon detector using the superconductor wiring is typically about mA, the number of detection units arranged in parallel is about 100. It becomes a limit.

  (2) The second problem is that a dead area occurs. When particles / photons are detected, the detection unit composed of the superconductor wiring shifts to a normal state, and the current flowing therethrough decreases. The reduced current is often distributed to other detection units connected in parallel. After that, when the detection units that have transitioned to the normal conduction state are restored to the superconducting state again, the detection units of these superconductor wirings form a closed circuit with zero resistance. In the case of a normal conductor, the current flowing through the closed circuit recovers due to the induced electromotive force caused by the voltage drop in the other circuit parts connected in parallel. Since the resistance value is zero, there is no voltage drop in the other parts forming the closed circuit, and the current flowing through the detection unit once shifted to the normal conduction state remains reduced. In particle / photon detectors using a superconductor wiring detector, each detector operates as a detector only when the current value of each detector is close to the critical current. The detected part becomes a non-sensitive area, which causes a problem that an effective sensitive area is reduced. Note that the detection unit that has become the insensitive region is re-operated as a detector because the current is distributed when another detection unit (wiring unit) connected in parallel detects particles or photons.

  (3) The third problem is that the signal strength is reduced. In Non-Patent Document 3, units in which a plurality of superconductor wires are arranged in parallel as detection units are further connected in series, one end is grounded, and a signal is read from the other end. In the case of a single detection unit, the output voltage is approximately expressed by I × R using the bias current I and the impedance R of the readout circuit. However, when the arrangement of series connection and the arrangement of parallel connection are used together, Assuming that the current passed through one detector is I, the number of series N, and the number of parallel M, the output voltage is about IR / N, and the signal intensity decreases when the number of series increases (Non-patent Document 4).

  Therefore, an object of the present invention is to solve the problems existing in the prior art, and to provide particles / photons that have a high response speed, a large sensitive area, a small amount of heat generation, and a large signal intensity and can prevent the generation of insensitive areas. It is to provide a detector.

  In view of the above-described object, the present invention provides an electric signal indicating that particles or photons have been detected when particles or photons collide with a detection unit maintained in a superconducting state and the detection unit transitions to a normal conduction state. A particle / photon detector for outputting a signal, comprising: a plurality of detectors connected in series; and two parallel wires provided in parallel with the plurality of detectors connected in series; Each of the plurality of detection units connected to each other is connected to the two parallel wirings alternately via a resistor, and through at least one of the two parallel wirings, Provided is a particle / photon detector configured to read out an electric signal.

  In the particle / photon detector, it is preferable that a resistance value of the resistor is smaller than a resistance value of the detection unit when transitioning to a normal state.

  Further, one of the parallel wirings is connected to a current source via a bias T circuit and connected to one end of the plurality of detection units connected in series via a bias inductor, and is connected to the current source. Functions as a bias current supply wiring for supplying a bias current to the plurality of detection units connected in series, and functions as a readout wiring for reading out an electric signal in parallel from the plurality of detection units connected in series It is preferable to do.

  The other of the parallel wires may be a ground wire that is grounded, or may be a read wire for reading an electric signal from the plurality of detection units.

  In the particle / photon detector, the use of a plurality of detection units increases the sensitive area in proportion to the number of detection units. In addition, when a plurality of detection units are connected in series and the method of reading the output electric signal is not devised, the kinetic inductance of the entire circuit is calculated as follows: [kinetic inductance of one detection unit] × [series The number of connected detection units], the operation speed of the particle / photon detector (response time as viewed from the circuit output) becomes slower in proportion to the number of detection units in series. On the other hand, in the particle / photon detector, particles or photons collide by connecting each connecting portion of a plurality of detecting portions connected in series alternately to two parallel wirings via a resistor. When the detector transitions from the superconducting state to the normal conducting state, a current flows through one of the two parallel wires through the resistor before the detection unit. can do.

Further, with such an arrangement, it is possible to solve the problem of heat generation in an arrangement in which detection units are connected in parallel as in the prior art. In other words, heat generation occurs in the transmission line connecting the low temperature part and the normal temperature part, but because the detection part is connected in series, it is the same as one particle / photon detector regardless of the number of detection parts connected in series. The operation can be performed with a current value, and as a result, the amount of heat generation is extremely small, that is, 1/2 of N ² compared to the case where N detection units are connected in parallel.

  Furthermore, in a conventional arrangement in which a plurality of detection units are connected in parallel, once a detection unit detects particles or photons, the detection is performed until another detection unit connected in parallel detects particles or photons. The part was a dead area that did not operate as a detector. On the other hand, in the particle / photon detector according to the present invention, when the detection unit where the particle or photon collides changes from the superconducting state to the normal conducting state, the connection unit before the detecting unit passes through the resistor. Since a current flows through one of the two parallel wirings to cause a voltage drop, the superconducting state can be quickly recovered. Accordingly, the dead time of each detection unit can be adjusted by appropriately selecting the value of the resistor connected between the connection unit of the detection unit and the two parallel wirings.

  In addition, as in Non-Patent Document 3, the signal strength is increased as compared with the case where parallel connection and series connection are used in combination.

  According to the present invention, particles having no insensitive area, having high-speed response, large area, low heat generation, and large signal intensity by connecting the connecting portions of a plurality of detecting portions alternately to two parallel wirings via resistors.・ A photon detector can be realized.

It is a block diagram of the conventional particle | grain and photon detector using a single superconductor wiring. A schematic shape of the detection unit of the particle / photon detector shown in FIG. 1 is shown in (a), and an equivalent circuit is shown in (b). It is a schematic diagram which shows the structure of the other conventional particle | grain / photon detector which used parallel connection and series connection together. It is a schematic diagram which shows the structure of one Embodiment of the particle | grain / photon detector by this invention. It is a schematic diagram which shows the structure of other embodiment of the particle | grain / photon detector by this invention. It is a graph which shows the simulation result of the output voltage waveform of the particle | grain and photon detector shown by FIG. It is a graph which shows the simulation result of the current waveform which flows through each detection part of the particle | grain / photon detector shown by FIG.

  Embodiments of a particle / photon detector according to the present invention will be described below with reference to the drawings.

First, a conventional particle / photon detector 110 will be described with reference to FIGS. 1 to 3 for comparison with the present invention.
FIG. 1 is a configuration diagram of a conventional particle / photon detector using a single detector 112. The particle / photon detector 110 includes one detection unit 112, one shunt resistor 114, a transmission line 116 including a coaxial cable, a bias T circuit 118, and an amplifier 120. When it collides with the detection unit 112, an electric signal is output from the detection unit 112. The detection unit 112 and the shunt resistor 114 are connected in parallel. One end of the parallel connection is grounded, and the other end is connected to the transmission line 116. The transmission line 116 is connected to the amplifier 120 via a bias T circuit 118. 1 is cooled to a temperature lower than the superconducting transition temperature (typically a liquid helium temperature of 4.2 K) surrounded by a dotted line 150 in FIG.

A schematic shape of the detection unit 112 is shown in FIG. 2A, and an equivalent circuit is shown in FIG. The detection unit 112 is a wiring 112a (hereinafter referred to as a superconductor wiring) 112a having a predetermined pattern and formed of a superconductor, and bonding pads 112b are formed at both ends of the superconductor wiring 112a. Has been. The superconductor wiring 112a and the bonding pad 112b are formed of, for example, a thin film of NbN (niobium nitride). The film thickness of the NbN thin film is typically 10 nm or less, and the line width of the superconductor wiring 112a is typically about several tens of nm to 1 μm. The superconductor wiring 112a is formed in a meandering pattern in FIG. 2A, but is not limited to this, and can be an arbitrary pattern. The pattern region of the superconductor wiring 112a corresponds to a sensitive area where particles and photons can be detected, and the size is several μm ² to several tens of thousands μm ² . For example, in the case of the particle / photon detector disclosed in Non-Patent Document 5, the material of the thin film of the detection unit 112 is NbN, the thickness is 10 nm, the line width of the superconductor wiring 112a is 800 nm, and the detection unit 12 The size is 200 μm × 200 μm, the superconducting critical current is 581 μA, the kinetic inductance is 1.1 μH, and the sensitive area is 0.02 mm ² .

As shown in FIG. 2B, the equivalent circuit of the detection unit 112 can be represented by a coil 122, a switch 124, and a resistor 126. The switch 124 and the resistor 126 are connected in parallel. A coil 122 is connected in series to a switch 124 and a resistor 126 connected in parallel. When the detection unit 112 is kept in the superconducting state, the switch 124 is in a conductive state, and the resistance of the detection unit 112 becomes zero.
On the other hand, when a particle or photon collides with the superconductor wiring 112a of the detection unit 112, the switch 124 is opened corresponding to the minute region portion of the collision portion being in a normal conduction state, and the resistance 126 A resistance value appears in the superconductor wiring 112a, and an electric signal corresponding to the change in the resistance value is output.

  FIG. 3 is a configuration diagram of the particle / photon detector 110 ′ disclosed in Non-Patent Document 3 and Non-Patent Document 4. Hereinafter, the particle / photon detector 110 ′ having the structure shown in FIG. 3 is described as a particle / photon detector arranged in parallel and in series.

In the particle / photon detector 110 ′ arranged in parallel / series connection, M detection units 112 made of superconductor wiring are connected in parallel, and N detection units 112 are connected in series (in FIG. 3, each detection unit is represented by D _{M , N} ). One end of the series connection is grounded, and the other end is grounded via the shunt resistor 114 and is connected to the amplifier 120 via the transmission line 116 and the bias T circuit 118. In the particle / photon detector 110 ′ having such a configuration, for example, when M = 8 and N = 8 and the particle / photon detector described in Non-Patent Document 5 described above is connected, the combined inductance is 1 μH, This is the same as the particle / photon detector using one detector (superconductor wiring) 112. On the other hand, since the area is 64 times, the sensitivity is improved. Further, since the critical current value is 8 times, the bias current necessary for the operation is also 8 times, and the power consumed in the transmission line 116 is 64 times as large.

Next, the particle / photon detector 10 according to the present invention will be described with reference to FIG. FIG. 4 is a block diagram of the particle / photon detector 10 according to the present invention.
The particle / photon detector 10 includes N detectors D ₁ ,..., D _N (reference numeral 12), N resistors 14, a transmission line 16, a bias T circuit 18, an amplifier 20, 4 includes a bias inductor 22, a shunt resistor 24, and two parallel wirings 26 and 28, and a portion surrounded by a dotted line 50 in FIG. 4 (N detection units D ₁ ,..., D _N , N resistors 14, the bias inductor 22, the shunt resistor 24 and the two parallel wires 26, 28) are cooled to a temperature lower than the superconducting transition temperature (typically liquid helium temperature 4.2 K).

Each of the detection units D ₁ ,..., D _N (reference numeral 12) has the same configuration as the detection unit 112 described above, and is formed of a superconductor wiring. Thus, where each detector D _1, ..., a detailed description of the configuration of a D _N omitted. N number of detector D _1, ..., D _N are connected in series by connecting portions, detector D ₁ connected in series, ..., two parallel wires 26, 28 are provided in parallel with the D _N ing. Detector D ₁ connected in series, ..., the connecting portions of the D _N are alternately connected through a resistor 14 into two parallel lines 26, 28. Resistance value of the resistor 14, the detection unit D ₁ of the time that has metastasized to the normal state, ..., is selected to be smaller than the resistance value of the D _N. In the embodiment shown in FIG. 4, by connecting one of the parallel wiring 26 of the two parallel lines 26, 28 to the transmission line 16, detector D _1, ..., resistance to electrical signals from the D _N The other parallel wiring 28 is grounded to function as a ground wiring while functioning as a readout wiring for reading out to the outside in parallel through the device 14.

  One end of the transmission line 16 is connected to the parallel wiring 26 as described above, and the other end is connected to a bias current source (not shown) and the amplifier 20 via the bias T circuit 18. The bias T circuit 18 includes a coil and a capacitor. The transmission line 16 is commonly connected to the coil and the capacitor, and a terminal on the opposite side of the coil from the transmission line 16 is a bias current source (not shown). And the terminal of the capacitor opposite to the transmission line 16 is connected to the amplifier 20. The configuration of such a bias T circuit is already known, and detailed description thereof is omitted here.

In order to operate the particle / photon detector 10, it is necessary to apply a current (bias current) I slightly lower than the superconducting critical current to each of the detectors D ₁ ,..., D _N (reference numeral 12). Therefore, in the embodiment shown in FIG. 4, detector D ₁ connected in series, ..., with grounding the one end of the D _N, and the other end thereof is connected to the parallel wiring 26 through the bias inductor 22 Yes.

With this configuration, the bias current I from the bias current source, the bias T circuit 18, the transmission line 16, the individual through parallel wiring lines 26 and bias the inductor 22 detector D _1, ..., is supplied to D _N, the particle- The photon detector 10 can be operated. That is, parallel wiring 26, each detector D _1, ..., functions as a bias current supply wires for supplying a bias current to D _N. The resistance value of the bias inductor 22 is sufficiently smaller than the resistance value of the resistor 14 connecting the detection units D ₁ ,..., D _N (detection unit 12) connected in series with the parallel wiring 26. The bias current is supplied from the parallel wiring 26 to the detection units D ₁ ,..., D _N connected in series through the bias inductor 22.

In addition, the connection parts of the plurality of detection parts D ₁ ,..., D _N connected in series are alternately connected to the two parallel wirings 26, 28 via the resistor 14, and the resistance value of the resistor 14 There detector D ₁ of the time that has metastasized to the normal state, ..., is smaller than the resistance value of D _N, detector D ₁ in which the particles or photons _collide, ..., D _N is the normal state from the superconducting state When the transition occurs, a current flows through one of the two parallel wirings 26 and 28 via the resistor 14 before the voltage drop occurs, and this voltage is read out through the parallel line 26 as an electrical signal. Further, the electrical signals (which become high-frequency signals) from the detection units D ₁ ,..., D _N that have detected particles and photons are transmitted to the bias T circuit 18 through the parallel wiring 26 and the transmission line 16, and are on the side of the bias current source. Is blocked by the coil, and is output to the amplifier 20 through the capacitor of the bias T circuit 18 and amplified, and is amplified using the amplified electric signal, and the particle / photon collides with the detection unit 12. Is detected. That is, parallel wiring 26 functions as a read line, each detector D _1, ..., after the electrical signal from the D _N has been read in parallel through resistor 14 to the parallel lines 26, the transmission line 16, bias It is transmitted to the amplifier 20 through the T circuit 18 and it is detected that particles and photons collide with the detection unit 12.

The resistance value R of the resistor 14 affects the time (recovery time) τ until each detection unit D ₁ ,..., D _N recovers from the normal conduction state to the superconducting state, and the detection units connected in series. D _1, ..., when the number N of D _N is sufficiently large, the recovery time τ becomes approximately L / 2R. The resistance value R of the resistor 14 is preferably high from the viewpoint of high-speed operation, but is preferably low from the viewpoint of stable operation. Depending on the purpose, the detector 14 has a resistance value R in the range of about 1 to 1 kΩ. Any selection may be made within the range in which.

  Further, a shunt resistor 24 is connected to the end of the parallel wiring 26 connected to the transmission line 16 on the transmission line 16 side. The shunt resistor 24 functions to prevent heat generation when the entire superconductor wiring forming the detection unit 12 is transferred to the normal conduction state.

Thus, the particle-photon detector 10, N pieces of detector D _1, ..., because of the use of D _N, has the advantage that the sensitive area increases. Further, since the N detectors D ₁ ,..., _DN are connected in series, the particle / photon detector 10 can be operated with the same current value as when one detector is used. Heat generation occurs in the transmission line 16 connecting the low temperature part (the part surrounded by the dotted line 50 in FIG. 1) and the normal temperature part, but the current value used in the particle / photon detector 10 can be kept low. Compared with the case where _N detectors D ₁ ,..., DN are connected in parallel, the amount of heat generated in the transmission line 16 is extremely low at 1 / N ² .

Further, as described above, the response speed of the particle / photon detector is proportional to the kinetic inductance. Therefore, when N detectors D ₁ ,..., _DN are simply connected in series, each detector D ₁ ,..., _{DN, where} the kinetic inductance (hereinafter simply referred to as “inductance”) is L, the entire inductance of the detection unit 12 is N × L, and the detection units D _{1 ,.} The response speed decreases in proportion to the number N. In contrast, in the particle-photon detector 10 of the embodiment illustrated in Figure 4, detector D ₁ connected in series, ..., the two parallel lines 26 and 28 connecting portions of the D _N are alternately are connected, all the detector D _1, ..., but D _N is not little current flows through the parallel wiring lines 26 and 28 when the superconducting state, a part of the detector D _1, ..., D _N are normal conducting When the resistance value increases in the state, a current flows through the resistor 14 to the parallel wiring 26 or 28. Therefore, the same effect as increasing the resistance value of the readout circuit can be obtained, and the response speed can be increased.

The driving force for recovering from the normal state to the superconducting state is the induced electromotive force due to the change in the resistance value generated in the detecting unit 12 when the detecting unit 12 changes from the superconducting state to the normal conducting state ( V = −L × di / dt), and the recovery time is proportional to the inductance of the detection unit 12. Each detector D _1, ..., when connecting D _N in parallel, the resistance of the detection portion by the particles or photons is transferred to the normal conducting state by colliding with the one detection unit is increased, the detection unit The current that was flowing through the current is distributed to other detectors connected in parallel, but the other detectors are superconducting, have almost no resistance, and almost no voltage drop occurs due to the increase in current. Since there is no current, no current flows through the detection unit that has transitioned to the normal conduction state, which results in a dead zone. On the other hand, in the particle / photon detector 10 of the embodiment shown in FIG. 4, the connection parts of the detection parts D ₁ ,..., D _N connected in series are alternately two via the resistor 14. When some of the detection units D ₁ ,..., D _N are connected to the parallel wirings 26 and 28 and the resistance value increases, one of the two parallel wirings 26 and 28 passes through the resistor 14. , And a voltage drop occurs, so that the detection units D ₁ ,..., D _{N in} the normal conduction state quickly return to the superconducting state. Moreover, since the change of the output voltage from the detection part 12 also becomes large, signal strength also increases.

The particle / photon detector 10 according to the present invention has been described above with reference to the embodiment shown in FIG. 4, but the present invention is not limited to the illustrated embodiment. For example, in the embodiment shown in FIG. 4, and reads out one of the parallel wiring 26 wiring, detector D _1, ..., but is read in parallel electrical signals from the D _N, it is shown in Figure 5 As in the particle / photon detector 10 ′ of the present embodiment, in addition to the parallel wiring 26, the other parallel wiring 28 is connected to the amplifier 32 via the transmission line 30 and grounded via the shunt resistor 34. Thus, an electrical signal may be read from both of the two parallel wirings 26 and 28.

The embodiment shown in FIG. 4 (hereinafter referred to as the present embodiment.) In the detection unit D _1, ..., serial number 64 of D _N, 200 .mu.A bias current I, the resistance value of the shunt resistor 24 50Ω, the resistance value R of the resistor 14 is 50Ω, the electrical length of the transmission line 16 is 2 ns, and each detection unit D ₁ ,..., _DN has a kinetic inductance, that is, an equivalent circuit shown in FIG. The voltage waveform input to the amplifier 20 is calculated assuming that the inductance of the coil 122 is 1 μH, the resistance at the time of switching, that is, the resistance value of the resistance 126 of the equivalent circuit shown in FIG. 2B is 500Ω, and the switching time is 1 ns. The simulation results are shown in FIG. For comparison, FIG. 6 shows a particle / photon detector 110 using only one detector as shown in FIG. 1, and each detector 12 of the particle / photon detector 10 of the present embodiment. When the detection unit 112 having the same characteristics is used and the bias current of the detection unit 112 is 200 μA, and in the particle / photon detector 110 ′ arranged in parallel / series connection shown in FIG. Therefore, the detection unit 112 having the same number of characteristics as the particle / photon detector 10 of the present embodiment with the parallel number 8 and the serial number 8 is used, and the bias current of each detection unit 112 is the particle / photon detection according to the present embodiment. each detector D ₁ of the vessel 10, ..., for the case where the 1600μA the bias current in the transmission line 116 so that the same 200μA and D _N, shows the results of simulation performed similarly. The solid line 1 in FIG. 6 is the waveform of the output voltage from the particle / photon detector 110 using the single detector shown in FIG. 1, and the broken line 2 is the particle / photon detector 10 according to the present embodiment. The dotted line 3 is the waveform of the output voltage from the particle / photon detector 110 'in the parallel / series connection arrangement shown in FIG.

  The particle / photon detector 10 according to the present embodiment shown in FIG. 4 has a higher output voltage wave height than the particle / photon detector 110 using the single detector 112 shown in FIG. Although it is about half, the sensitive area is large and the response speed is extremely fast. Further, the output voltage of the particle / photon detector 110 ′ arranged in parallel / series connection shown in FIG. 3 has a wave height less than one third of that of the particle / photon detector 10 according to the present embodiment, and the response speed. Is too slow. Furthermore, the particle / photon detection unit 110 arranged in parallel / series connection and the particle / photon detector 10 of the present embodiment both use 64 detection units and have the same sensitive area. In the particle / photon detector 10 according to the form, the current value is 1/8 and the heat generation amount in the transmission line is 1/64 as compared with the particle / photon detector 110 ′ arranged in parallel / series connection. Get smaller.

FIG. 7 is a graph showing how the current flowing through the detector decreases and recovers when particles and photons are detected in the simulation described above. In FIG. 7, a solid line 1 indicates a waveform of a current flowing through each detection unit D _{M, N} (detection unit 112) in the particle / photon detector 110 ′ arranged in parallel / series connection, and a dotted line 2 indicates a particle / photon detector according to the present embodiment. The waveform of the electric current which flows through each detection part _DN (detection part 12) in the photon detector 10 is shown. As can be seen from the current waveform indicated by the solid line 1, in the particle / photon detector 110 ′ arranged in parallel and in a series connection, the current value once reduced does not recover, and therefore a dead region occurs. On the other hand, as can be seen from the current waveform shown by the dotted line 2, in the particle / photon detector 10 according to the present embodiment, the current value quickly recovers and the time scale at which the current value returns to about 10 ns. And early. The recovery time is expressed as Lk / 2R with the resistance value R of the single resistor 14 value inserted kinetic inductance Lk of detector D _N.

  As described above, according to the present invention, it is possible to realize a particle / photon detector which has a large area, a high-speed response, and a large signal intensity, and which has no dead region and operates with a small current value.

10 Particle / Photon Detector 12 Detector 14 Resistor 16 Transmission Line 18 Bias T Circuit 20 Amplifier 22 Bias Inductor 24 Shunt Resistance 26 Parallel Wiring 28 Parallel Wiring

Claims (5)

  A particle / photon detector that outputs an electrical signal indicating that a particle or photon has been detected when a particle or photon collides with the detection unit maintained in a superconducting state and the detection unit transitions to a normal conducting state. A plurality of detectors connected in series, and a plurality of detectors connected in series and two parallel wirings provided in parallel, the plurality of detectors connected in series Each connection portion is alternately connected to the two parallel wirings via a resistor, and the electrical signals from the plurality of detection units are read out through at least one of the two parallel wirings. Particle / photon detector.   2. The particle / photon detector according to claim 1, wherein a resistance value of the resistor is smaller than a resistance value of the detection unit when transitioning to a normal conduction state.   One of the parallel wirings is connected to a current source via a bias T circuit and is connected to one end of the plurality of detection units connected in series via a bias inductor, and is connected to the series from the current source. Functions as a bias current supply wiring for supplying a bias current to a plurality of detection units connected to the same, and functions as a readout wiring for reading out an electrical signal in parallel from the plurality of detection units connected in series. The particle / photon detector according to claim 1.   The particle / photon detector according to claim 3, wherein the other of the parallel wires is a ground wire that is grounded.   The particle / photon detector according to claim 3, wherein the other of the parallel wirings is a readout wiring for reading out an electrical signal from the plurality of detection units.

Images