DE102004054750A1 - Detector device for very low temperatures has a sensor cooled by a pulsed multi-tubular cooler and cooling devices in a vacuum pot - Google Patents

Abstract

A cryogenic detector device (CDD) has a first cooling device (CD) (10) that cools a second CD (20) in advance. A detector device (DD) (30) is thermally coupled to the second CD so as to detect particles, radiation or fields. The first and second CDs and the DD fit in a vacuum pot (40) sealed by an interface device (50), through which the required feed and drain lines are fed for the CDD.

Description

The The invention relates to a cryodetector device according to claim 1.

such Detector devices with a low temperature effect based Sensor in a first cooling stage is cooled by means of a pulse tube cooler, has a big one Application in analytical applications, particle, radiation or fields with high energy resolution and / or high time resolution to be examined at any location.

To the Cool of sensors based on a low-temperature effect (cryosensors or cryodetectors), cryostats are used in the prior art, a first cooling device and a second cooling device, that of the first cooling device pre-cooled is, wherein the sensor to the second cooling device thermally coupled. To generate a temperature of about 4K the first cooling device mostly from a coupled nitrogen / helium cooler. This is process and device technology very expensive and needs lots of space. Furthermore, the required liquid coolant (nitrogen, helium) on the one hand expensive and on the other hand not everywhere available. That's why It's the use of sensors that have a low temperature effect based, for Industrial purposes relatively unprofitable and therefore unsuitable.

Out Info-Phys-Tech No. 6, 1996, from VDI Technology Center, Physical Technologies, is a chiller in the form of a pulse tube cooler, the pulse tube cooler of comprising: a pulse tube having at its one end a cold heat exchanger, on the heat from the outside is provided, is provided, and at the other end a warm heat exchanger, after the heat Outside is provided, a regenerator, as a heat buffer serves, and a pressure oscillator, which serves to periodic pressure changes with the pulse tube at the end at which the cold heat exchanger is provided over respective lines over the Regenerator is connected to the pressure oscillator, so that a periodic Displacement of a working gas between the pulse tube and the pressure oscillator allows becomes.

From the EP 1 014 056 A2 For example, a cryodetector device having a plurality of cooling devices is known, wherein one of the cooling devices is a multi-stage pulse tube cooler. This known cryodetector apparatus comprises a first cooling means for providing a first cooling temperature comprising a two-stage pulse tube cooling system. In the two-stage pulse tube refrigerator system, a first pulse tube refrigerator cools a second pulse tube refrigerator. Furthermore, a second cooling device is provided for providing a second cooling temperature which is lower than the first cooling temperature. In this case, the second cooling device is pre-cooled by the first cooling device. Furthermore, this cryodetector device has a detector device for detecting particles, radiation or fields with a sensor based on a low-temperature effect, wherein the detector device is thermally coupled to the second cooling device. Thereby, a cryodetector device is provided with a comparatively simple cooling system, wherein sensors can be operated, which have a good energy resolution and can be used at quasi arbitrary locations due to the minimum device-technical effort of the cooling system. In the operation of this known Kryodetektorvorrichtung has been found that the parasitic loads due to the so-called DC flow, ie, an additional flow of gas in the radiator, are relatively large.

Starting from the EP 1 014 056 A2 It is therefore an object of the present invention to keep these parasitic loads as low as possible.

These The object is achieved by a cryodetector device according to the features of claim 1.

The cryodetector device according to the present invention comprises a cooling system having a first cooling device for providing a mean cooling temperature T _m and a second cooling device for providing a lower cooling temperature T _u . In this case, the second cooling device is pre-cooled by the first cooling device. The first cooling means comprises a first pulse tube refrigerator which cools from ambient temperature to an upper cooling temperature T _o , and a second pulse tube refrigerator which cools from ambient temperature to the mean cooling temperature T _m . The cold side of the first pulse tube refrigerator is connected to a first cold shield and the cold side of the second pulse tube refrigerator is connected to a second cold shield. Furthermore, the cryodetector device has a detector device for detecting particles, radiation or fields with a sensor based on a low-temperature effect, wherein the detector device is thermally coupled to the second cooling device.

By this structure, as in the prior art according to the EP 1 014 056 A2 a cryodetector device is provided which has a good energy resolution and due to the minimal vorrich technical effort can be used at virtually any location or is mobile. Furthermore, the operation or maintenance of the first cooling stage is cost-effective, since the pulse tube cooler only requires a supply of electrical current. The consequence of this is that also personnel can be saved since no person must be provided for monitoring or replenishment of coolant.

Both the first pulse tube refrigerator and the second pulse tube refrigerator cool from ambient temperature to their respective cooling temperature T _o or T _m , ie the second Puzlsröhrenkühler is in contrast to the prior art after EP 1 014 056 A2 not directly pre-cooled by the first pulse tube refrigerator. This parallel connection of the pulse tube coolers of the first cooling device makes it possible to reduce the parasitic loads due to the existing DC flow. The reduction of the cooling capacity due to the parallel connection instead of the series connection of the pulse tube coolers has been found to be negligible or is compensated by the reduced parasitic loads.

One Another advantage is the saving of electrical power since it is to be expected that the pulse tube refrigerator according to the present invention with less input power can be operated.

According to one advantageous embodiment, the first cooling device has a third or other pulse tube coolers. These can also be connected in parallel according to the first and second pulse tube coolers and / or arrange in series with the first or second pulse tube refrigerator.

According to one advantageous embodiment, each of the pulse tube cooler Pulse tube on, at one end of a cold heat exchanger, at the heat of Outside is provided, is provided, and at the other end a warm heat exchanger, on the heat outward is provided is provided. Furthermore, the pulse tube cooler has a Regenerator acting as a heat buffer serves, and a pressure oscillator, which serves to periodic pressure changes to create. Here, the pulse tube is at the end where the cold heat exchangers is provided, via respective Lines over the regenerator connected to the pressure oscillator, so that a periodic shift a working gas between the pulse tube and the pressure oscillator allows becomes. Unlike other mechanical coolers, the pulse tube cooler has the advantageous property that he very is low in vibration.

According to one further advantageous embodiment, the pulse tube at the end, where the warm heat exchanger is provided, further, a flow resistance and a container for receiving a ballast volume.

According to one Further advantageous embodiment, each of the pulse tube cooler further a secondary line extending from the end of the respective pulse tube at which the warm heat exchangers is provided to the line between the pressure oscillator and extends to the regenerator and opens into it, the secondary line having a variable or variably adjustable flow resistance.

The second cooling device is advantageously at or near the cold heat exchanger a pulse tube cooler arranged.

The Detector device may further comprise an absorber, the on the sensor is thermally coupled and in the incident particles and radiation interact. The absorber can be made of a dielectric or a semiconductor or a metal or a semi-metal or a semi-metal alloy or a superconductor or a combination consist of individual materials.

As the second cooling means, a demagnetization stage is advantageously used. Furthermore, a ³ He / ⁴ He demixing cooler or a ³ He cooler or a mechanical cooling device such as a helium compressor cooler or an electric cooling device such as a Peltier element or a superconducting tunnel diode such as an NIS diode can be used.

According to one further advantageous embodiment of the detector device according to the invention the cooling system Part of a cryostat in which housed the detector device is, wherein the cryostat further comprises an inlet opening for passing the to be examined particles and radiation from the exterior of the cryostat in the Interior of the cryostat to the detector device has. In addition, can the cryostat has a focusing device such as an X-ray lens or a Wolter arrangement or a Fresnel lens or focusing Tube bundle or electric focusing devices / defocusing devices or magnetic focusing devices / defocusing devices exhibit.

The cryogenic-based sensors used in the detector device, or cryodetectors or cryogenic detectors, are sensors which store energy deposited by radiation or particle absorption by means of an effect which is only or especially at low temperatures (operating temperature range less than 20 K, preferably but less than <4 K), measure up. These temperatures are provided by a heat sink, which is thermally coupled to the detector device, which has a respective sensor based on a cryogenic effect.

• i) Temperaturerhöhung nach Energiedeposition (Kalorimeter) in einem Absorber (Dielektrikum, Metall, Supraleiter, usw.). Diese Temperaturerhöhung ist umso höher je tiefer die Ausgangstemperatur ist, da die Wärmekapazitäten bei den tiefen Temperaturen abnehmen. Je größer die Temperaturerhöhung ist, desto genauer kann aus ihr die deponierte Energie abgeleitet werden.
• ii) Erzeugung von Phononen (Gitterschwingungen in einem Absorbermaterial) durch die Energiedeposition. Damit diese Gitterschwingungen möglichst stark "hervortreten", d.h., eine genaue Bestimmung der Energie (und eventuell des Ortes der Energiedeposition im Absorber) möglich ist, sollten im Ausgangszustand möglichst wenige Gitterschwingungen vorhanden sein. Je tiefer die Ausgangstemperatur, desto weniger Gitterschwingungen sind vorhanden.
• iii) Erzeugung von Quasiteilchen (Aufbrechen von Cooperpaaren) in einem Supraleiter. Supraleitung ist ein Tieftemperatureffekt. Je tiefer die Übergangstemperatur zur Supraleitung, desto mehr dieser Quasiteilchen werden durch die Energiedeposition erzeugt. Je mehr der Quasiteilchen erzeugt werden, desto genauer kann die Energie bestimmt werden.
• iv) Änderung der Spinausrichtung bzw. Magnetisierung in einem auf tiefe Temperaturen abgekühlten Spinsystem bestehend aus paramagnetischen Ionen aufgrund einer Energiedeposition.

These effects can be:

• i) Temperature increase after energy deposition (calorimeter) in an absorber (dielectric, metal, superconductor, etc.). This temperature increase is the higher the lower the initial temperature is, since the heat capacities decrease at the low temperatures. The greater the temperature increase, the more accurately the deposited energy can be derived from it.
• ii) Generation of phonons (lattice vibrations in an absorber material) by energy deposition. So that these lattice vibrations "emerge" as much as possible, ie, an accurate determination of the energy (and possibly the location of the energy deposition in the absorber) is possible, as few lattice vibrations should be present in the initial state. The lower the starting temperature, the less lattice vibrations are present.
• iii) Production of quasiparticles (disruption of Cooper pairs) in a superconductor. Superconductivity is a low temperature effect. The lower the transition temperature to superconductivity, the more of these quasiparticles are produced by the energy deposition. The more quasiparticles are produced, the more accurate the energy can be determined.
• iv) Change in the spin orientation or magnetization in a cooled to low temperatures spin system consisting of paramagnetic ions due to an energy deposition.

• a) Supraleitende Phasenübergangsthermometer, wie beispielsweise als Sensor in einem Mikrokalorimeter: Diese bestehen im wesentlichen aus einem Absorber, einem Thermometer (supraleitende Schicht, beispielsweise aus Wolfram, Iridium, Aluminium oder Tantal) und einer Kühleinrichtung bzw. einer Kopplung an eine Wärmesenke. Im Temperaturübergangsbereich zwischen seiner supraleitenden und normalleitenden Phase ändert das Thermometer seinen elektrischen Widerstand sehr stark in Abhängigkeit von der Temperatur, d.h., auch nach Absorption von Gitterschwingungen und Quasiteilchen.
• b) Supraleitende Tunneldioden: Sie bestehen aus zwei überlappenden dünnen supraleitenden Filmen (SIS: Supraleiter-Isolator-Supraleiter, wobei die Filme nicht notwendigerweise aus dem gleichen Supraleiter auf beiden Seiten bestehen müssen) oder einem supraleitenden und einem normalleitenden Film (NIS: Normalleiter-Isolator-Supraleiter), wobei die jeweiligen Filme durch eine dünne elektrisch isolierende Barriere getrennt sind. Die Barriere ist so dünn, daß sie quantenmechanisches Tunneln von Elektronen, bzw. Quasiteilchen von der einen Elektrode zur anderen erlauben. Wird die NIS-Diode oder SIS-Diode unterhalb der Sprungtemperatur der jeweiligen Supraleiter betrieben, und ist die angelegte Spannung kleiner als die der supraleitenden Energielücke entsprechenden Spannung (NIS) bzw. kleiner als zweimal diese Spannung (SIS), so steigt der über die Barriere fließende Strom, wenn in der Tunneldiode Energie deponiert wird. Die Deposition der Energie kann durch Temperaturerhöhung, Absorption von Gitterschwingungen oder Quasiteilchen oder direkt durch Absorption von Strahlung oder Teilchen geschehen.
• c) Thermistor, wie NTD-Thermometer (NTD: "Neutron Transmutation Doping", d.h., mit Neutronen hochdotierter Halbleiter). Diese Thermometer können zum Messen von Temperaturschwankungen verwendet werden, da bei ihnen, wie bei allen Halbleitern der Widerstand mit sinkender Temperatur zunimmt. Um zu vermeiden, daß bei sehr tiefen Temperaturen die Widerstände so hoch anwachsen, daß sie nicht mehr mit genügender Genauigkeit gemessen werden können, werden die verwendeten Halbleiter hochdotiert, wodurch ihr Widerstand abgesenkt wird.
• d) Magnetische Bolometer. Diese Sensoren, die eine schwache thermische Kopplung an ein Kältebad bzw. eine Wärmesenke mit einer Temperatur vorzugsweise im Millikelvinbereich haben, umfassen eine schwache Konzentration von paramagnetischen Ionen in einem magnetischen Feld. Als derartige Ionen werden vorteilhafterweise Ionen von seltenen Erden, wie beipsielsweise von Erbium (Er³⁺), verwendet. Wenn ein kleiner Energiebetrag, beispielsweise durch elektromagnetische Strahlung, in einem derartigen Sensor deponiert wird, verursacht der Temperaturanstieg eine Änderung der Magnetisierung des von den paramagnetischen Ionen gebildeten Paramagneten, die beispielsweise unter Verwendung einer Spule, die an einen Eingang eines SQUIDs angeschlossen ist, gemessen werden kann. Vorteilhafterweise ist an das magnetische Bolometer ein Absorber thermisch gekoppelt.

In order to measure the temperature increase, the lattice vibrations, the quasiparticles (in general the excitations) or the change in the magnetization, there are various possibilities, with the general rule that the excitations are generated in an absorber and detected in a sensor. Sensor and absorber can be identical. Suitable sensors are:

• a) Superconducting phase transition thermometers, such as a sensor in a microcalorimeter: These consist essentially of an absorber, a thermometer (superconducting layer, such as tungsten, iridium, aluminum or tantalum) and a cooling device or a coupling to a heat sink. In the temperature transition range between its superconducting and normal-conducting phase, the thermometer changes its electrical resistance very strongly as a function of the temperature, that is, even after absorption of lattice vibrations and quasiparticles.
• b) Superconducting tunnel diodes: They consist of two overlapping thin superconducting films (SIS: superconductor-insulator superconductor, where the films do not necessarily have to consist of the same superconductor on both sides) or a superconducting and a normal-conducting film (NIS: normal conductor insulator Superconductor), the respective films being separated by a thin electrically insulating barrier. The barrier is so thin that it allows quantum mechanical tunneling of electrons or quasiparticles from one electrode to another. If the NIS diode or SIS diode is operated below the transition temperature of the respective superconductors, and the applied voltage is less than the voltage corresponding to the superconducting energy gap (NIS) or less than twice this voltage (SIS), the voltage across the barrier increases flowing electricity when energy is deposited in the tunnel diode. The deposition of energy can be done by increasing the temperature, absorbing lattice vibrations or quasiparticles or directly by absorbing radiation or particles.
• c) Thermistor, such as NTD thermometer (NTD: "Neutron Transmutation Doping", ie with neutrons highly doped semiconductors). These thermometers can be used to measure temperature variations since, as with all semiconductors, the resistance increases with decreasing temperature. In order to avoid that at very low temperatures, the resistances grow so high that they can no longer be measured with sufficient accuracy, the semiconductors used are highly doped, whereby their resistance is lowered.
• d) Magnetic bolometers. These sensors, which have a weak thermal coupling to a cold bath or a heat sink with a temperature preferably in the millikelvin range, comprise a weak concentration of paramagnetic ions in a magnetic field. As such ions, ions of rare earths such as erbium (Er ³⁺ ) are advantageously used. When a small amount of energy, such as electromagnetic radiation, is deposited in such a sensor, the temperature rise causes a change in the magnetization of the paramagnets formed by the paramagnetic ions, measured, for example, using a coil connected to an input of a SQUID can. Advantageously, an absorber is thermally coupled to the magnetic bolometer.

The use of such cryogenic sensors offers several advantages. On the one hand, a good energy resolution should be mentioned, which is 6 eV X-radiation in the range of about 5 eV and at 1.5 keV X-radiation in the range of about 3 eV. ne ben the good energy resolution of the cryogenic sensors and their detection efficiency even at low energies (less than 2 keV) is advantageous. It can be detected and detected virtually any incident on the sensor photon. In addition, a predetermined energy range of particles or radiation to be analyzed can be detected simultaneously and the pulses generated by the particles or radiation in the detector can be read out quickly, as a result of which time-dependent phenomena with a short time constant can also be observed.

to Improvement of the readout speed or for setting a optimal operating temperature of the detector device or the sensor, Advantageously, a heating device is provided, which is connected to the Detector device is thermally coupled. Is the temperature or the temperature range of the cooling system or the second cooling device below the for the respective cryogenic sensor optimum temperature, or fluctuates the provided cooling temperature, that's how it works by controlling the energy supplied by the heater to the sensor set an optimal operating temperature. Furthermore, the setting offers a temperature above that provided by the cooling device Temperature the possibility the "active cooling". It understands one the removal of the heating power at one in the sensor device taking place energy deposition of an incident particle or incident radiation. Due to the quick reset of the sensor device to the predetermined optimum operating temperature can be in this way a signal acceleration and thus an improvement to achieve the readout speed.

To the Detecting magnetic fields or their changes can also SQUIDs ("Superconducting Quantum Interference Device ", superconducting quantum interference devices) are used as sensors become.

The Detector device may further comprise a plurality of sensors. This is advantageous, for example, if two different types Sensors are used, their energy resolution in each case different Energy ranges is different good.

Further Details, features and advantages of the invention will become apparent the following description of preferred embodiments with reference to the drawing.

It demonstrate:

1 a schematic representation of an embodiment of the invention;

2 a schematic representation of a pulse tube refrigerator according to a first embodiment;

3 a schematic representation of a pulse tube refrigerator according to a second embodiment;

4 a schematic representation of a pulse tube refrigerator according to a third embodiment;

5 a schematic representation of a pulse tube refrigerator according to the third embodiment in a more concrete representation than in 4 ;

6 a schematic cross-sectional view of a real geometry of a pulse tube refrigerator;

7 a schematic representation of a two-stage pulse tube refrigerator for a Krydetektorvorrichtung according to the present invention with the most important components;

8th a detailed presentation of 1 ;

9 a schematic representation of a real geometry of a usable as a detector microcalorimeter; and

10 a representation of the prior art according to the EP 1 014 056 A2 ,

overall system

First, be on it 1 which shows a schematic representation of the inventive cryodetector device. The cryodetector device comprises a first cooling device 10 that a second cooling device 20 pre-cooling. A detector device 30 for detecting particles, radiation or fields is to the second cooling device 20 thermally coupled. The cooling equipment 10 and 20 as well as the detector device 30 are in a vacuum pot 40 arranged by an interface device 50 is closed, over which the necessary supply and discharge lines of the cryodetector are performed. The first cooling device 10 includes a first pulse tube refrigerator 102 who has a first pulse tube 104 , a first regenerator 106 and a first coldhead 108 having. The first cooling device 10 further comprises a second pulse tube refrigerator 112 that has a second pulse tube 114 , a second regenerator 116 and a second coldhead 118 having. The first coldhead 108 is thermally connected to a first cold shield 110 and the second coldhead 118 is thermally connected to a second cold shield 120 coupled. The vacuum pot 40 as the outer shell, the first cold shield 110 as the middle shell and the second cold shield 120 as innermost shell form a cold finger 60 the in three consecutive entrance windows 70 ends, wherein behind the innermost window, the detector device 30 is arranged.

The first pulse tube cooler 102 cools from ambient temperature to an upper temperature T _o . This is the first cold head 108 and the thermally associated first cold shield 110 at the temperature T _o . The second pulse tube cooler 112 Cools from ambient temperature to an average temperature T _M. This is the second cold head 118 and the thermally associated second cold shield 120 on the temperature T _M.

10 shows one 1 corresponding representation of a cryodetector according to the EP 1 014 056 A2 , For parts corresponding to each other, the same reference numerals are used. The essential difference between the cryodetector device according to the present invention and the in 10 The prior art cryodetector device shown consists in the arrangement of the two pulse tube coolers 102 and 112 , more precisely in the arrangement of the two regenerators 106 and 116 , According to the prior art 10 are the first and second Rengenerator 1106 . 116 connected in series while being connected in parallel in the present invention.

Pulse tube cooler

The following describes the structure and operation of a pulse tube refrigerator. It shows 2 a schematic representation of a pulse tube refrigerator according to a first embodiment. Here, as in the following figures, like parts are designated by the same reference numerals.

The cooling effect of the pulse tube refrigerator is based on the periodic pressure change and displacement ("pulsing") of a working gas in a thin-walled cylinder with heat exchangers at both ends, the so-called pulse tube 104 . 114 , The pulse tube 104 . 114 is with a pressure oscillator 80 over the regenerator 16 . 116 connected. The regenerator 106 . 116 serves as a heat buffer, that of the pressure oscillator 80 inflowing gas before entering the pulse tube 104 . 114 cools and then the outflowing gas is warmed to room temperature. For this purpose is the regenerator 106 . 116 advantageously filled with a material of high heat capacity, which has a good heat exchange with the flowing gas at the same time low flow resistance. At temperatures above 30 K, stacks of fine-meshed stainless steel or bronze sieves are used as regenerator filling. For lower temperatures, for reasons of high heat capacity, lead shot and, more recently, magnetic materials, eg, Er-Ni alloys, are used.

To generate the pressure oscillation, as in 5 shown is a compressor 802 in combination with a downstream rotary valve 804 used, which periodically the high and low pressure side of the compressor 802 with the pulse tube cooler 102 . 112 combines. Alternatively, the pressure oscillation can be generated directly via the piston movement of a valveless compressor.

In the first embodiment of the pulse tube refrigerator 102 . 112 is the pulse tube 104 . 114 at the warm end 130 closed. The cooling process is qualitatively as follows: In the compression phase, this flows in the regenerator 106 . 116 precooled gas in the pulse tube 104 . 114 one. Due to the increase in pressure, the gas in the pulse tube 104 . 114 heated and at the same time to the warm heat exchanger 130 shifted where a portion of the heat of compression is dissipated to the environment. The subsequent expansion causes a cooling of the gas in the pulse tube 104 . 114 , The gas, which is the pulse tube 104 . 114 in the direction of the regenerator 106 . 116 leaves, is colder than at the entrance and can therefore heat over the cold heat exchanger or the cold head 108 . 118 from the object to be cooled. A closer analysis of the process in this embodiment shows that for the heat transfer from the cold 108 . 118 - to the warm - 130 - End heat exchange between gas and pipe wall is required ("surface heat pump"). Since the thermal contact, however, takes place only in a thin gas layer on the pipe wall, this cooling process is not yet optimized.

3 now shows a schematic representation of a pulse tube refrigerator 102 . 112 according to a second embodiment. This results in a significant increase in the effectiveness of the connection of a ballast volume 132 via a flow resistance (needle valve) 134 on the warm heat exchanger 130 , On the one hand, more gas flows through the warm heat exchanger 130 which can then give off compression heat there. On the other hand, the gas in the pulse tube 102 . 112 Work on moving gas into the ballast volume 132 , whereby a much higher cooling effect is achieved.

4 shows a schematic representation of a pulse tube refrigerator 102 . 112 according to a third embodiment, in which the effectiveness of the cooler can be further increased by the proportion of the gas flow, the pressure change in the warm part of the pulse tube 20 is necessary, by a second one leave over an inlet valve 136 at the warm end 130 is directed. Because this gas flow is no longer the regenerator 106 . 116 happens, the losses are in the regenerator 106 . 116 reduced. It also turns out at second intake 136 a more favorable for the cooling time sequence of pressure and flow variation.

5 shows a schematic overall construction of a pulse tube refrigerator according to the third embodiment in a more concrete representation than in 4 , It feeds in this system, a commercial helium compressor 802 a motorized rotary valve 804 , which serves to control the helium gas flow.

For mechanical decoupling and to reduce electromagnetic interference, the actual cooler and the rotary valve can be connected via a flexible plastic pipe 138 connected with each other.

A real geometry of a pulse tube refrigerator is shown in a schematic cross-sectional view in FIG 6 shown. To achieve the leanest possible design, are pulse tube 104 . 114 and regenerator 106 . 116 arranged coaxially. The warm heat exchanger 130 is only cooled by the ambient air. The cold head 108 . 118 with conically shaped inner surface for guiding the gas flow serves as a (cold) heat exchanger 108 . 118 between slides for objects to be cooled 140 and the working gas. An assembly comprising the vacuum insulation vessel 142 with the integrated ballast volume 132 is in the lower part, which are the objects to be cooled 140 encloses made of Plexiglas, whereby a reduction of the electronic noise is achieved. At the upper end of the pulse tube cooler 102 . 112 are gas inlets 144 for the warm heat exchanger 130 or the pulse tube 104 . 114 intended.

7 shows a more detailed representation of the first cooling device 10 with the two pulse tube coolers 102 and 112 as shown in the exemplary embodiment of the invention 1 is used. In addition to those already in 1 shown components are in 7 still the compressor 802 with rotary valve 804 , the balast volume 132-1 . 132-2 , the flow resistance (needle valve) 134-1 . 134-2 and the inlet valve 136-1 . 136-2 of the first and second pulse tube scanners 102 . 112 shown. The valves 134a . 134b . 136a . 146b , the secondary line 135 and the two balast volumes 132a . 132b form the interface device 50 , Unlike the in 5 Pulsröhrenküler shown is the two pulse tube cooler 102 and 112 in 7 the balustrade volume 132-1 . 132-2 at the warm end 130 the respective pulse tube 104 . 114 and the flexible supply line 138 from the pressure oscillator 80 is with the two regenerators 106 . 116 connected. This has the advantage that the gas circuits in the two pulse tube coolers 102 . 112 are separated from each other. This also includes the DC flow in the first pulse tube cooler 102 through the first inlet valve 134a , the first regenerator 106 , the first coldhead 108 and the first pulse tube 104 independent of the DC flow in the second pulse tube cooler 112 through the second inlet valve 134b , the second regenerator 116 , the second coldhead 118 and the second pulse tube 114 , The DC flow in both pulse tube coolers 102 . 112 can therefore be optimized independently of each other.

It is also conceivable that a common ballast volume is used instead of the two separate ballast volumes. The first coldhead 108 of the first pulse tube 104 cools first cold shield 110 down to about 50 K max. The second coldhead 118 of the second pulse tube 114 provides a temperature of about 2.2 to 4.2K.

Second cooling device

8th corresponds to 1 and additionally shows details of the second cooling device 20 , The second cooling device 20 is designed as an adiabatic demagnetization stage and provides a cooling temperature T _T of about 30 to 300 mK. At this temperature level, the detector device 30 thermally coupled.

The second cooling device comprises a magnet 150 put on the salt in a salt pill 152 magnetized. For thermal decoupling is the salt pill 152 about kevlar threads 154 hung, with the threads 154 through a tensioning device 156 For example, in the form of springs or materials that contract when the temperature decreases, are stretched. By means of a heat switch 158 can during the demagnetization stage 20 the salt pill 152 with the magnet 150 or the clamping device 156 thermally coupled. The demagnetization stage is of a magnetic shield 160 surround. The magnetic shield 160 serves to shield the magnet 150 opposite the environment. In the operating mode of the detector device 30 becomes the magnet 150 or its field slowly shut down, so that the temperature in the salt pill 150 constant at or below the operating temperature of the detector device 30 is held. The remaining magnetic field must be compensated and shielded. This can be done by the coil of the magnet 150 already have compensation coils. The magnetic shield 160 may consist of a superconductor (eg niobium, Ta) or of a material with high magnetization (eg Kryoperm or Vacrylux or a combination of both). At the bottom of the arranged around the demagnetization magnetic shield 160 a small hole through which the cold finger 60 which extends the detector device 30 holds.

Furthermore, the demagnetization stage and the detector device are 30 directly from the second chill plate 110 within which a temperature T _U of approximately 4 K is set. This temperature T _U is from the second cold head 118 the second pulse tube cooler 102 set. The second coldhead 118 This is thermal and mechanical to the magnet 150 coupled.

The second cold shield 110 is from the first cold shield 108 within which the average temperature T _M of approximately 67 K is set. This mean temperature T _M is from the first pulse tube refrigerator 102 set the first stage of the first cooling device 10 represents used pulse tube refrigerator system. The first cold head 108 with the first cold shield or 67K shield 110 connected.

The cooling systems the cryodetector device according to the invention, having pulse tube coolers, are very low vibration due to the lack of moving parts and therefore especially good for the cooling from sensitive sensors like SQUIDs.

detector device

When Detector device in a detector device according to the invention can For example, a microcalorimeter are used whose sensor a phase transition thermometer is. Generally included while a microcalorimeter consists of a sensor device a thermometer that has a superconducting material with a finite width transition temperature range from the normal conducting to the superconducting phase, wherein the transition temperature in the middle of the transition temperature range is and the electrical resistance of the superconducting material within the transition temperature range increases with increasing temperature. Furthermore, the microcalorimeter points an absorber thermally coupled to the thermometer and in which incident particles or radiation interact. A cooling device is to provide an operating temperature below the transition temperature provided by the thermometer, wherein by a heating device of Temperature operating point of the thermometer within the transition temperature range is adjustable. To register a resistance change due to of incident particles or radiation is readout electronics, which is electrically or magnetically connected to the thermometer and detected by the current flowing through the thermometer. To minimize the cooling power to be applied, the cooling device and the heater advantageously separated from each other the sensor device thermally coupled. To improve the Signal acceleration can be the cooling device or the heater or both at the same time with be thermally coupled to the sensor device. Flat thermal Coupling means here, that the Coupling over an extended contact area and not just quasi-point-shaped as with bonding wires he follows.

The 9 now show a schematic representation of a real geometry of the components of a microcalorimeter, which can be used in the detector device according to the invention as a detector device.

It shows 9a a top view of the Mikrokaloriemeteranordnung, 9b a sectional view along the in 9a shown line bb and 8c a sectional view along the in 9a represented line cc. From top to bottom is considered a thermometer (superconducting film) 201 via contact surfaces made of aluminum, so-called aluminum bonding pads 235 . 236 electrically contacted and via superconducting wires 245 . 246 by means of read-out electronics, for example a conventional preamplifier electronics, but preferably read by means of a SQUID system. As heating elements are gold heaters 222 . 223 via an electrically conductive absorber 202 connected. They are using aluminum bond pads 237 . 238 electrically contacted and via superconducting wires 247 . 248 connected to a voltage source (not shown). The gold heaters are about their thermal conductivity to the thermometer 201 and the absorber coupled. A substrate 230 offers a coupling to the second cooling device 20 ,

10

first cooling device

20

second cooling device

30

detector device

40

vacuum pot

50

Interface device

60

cold finger

70

entrance window

102

first Pulse tube cooler

104

first pulse tube

106

first regenerator

108

first cold head

110

first cold shield

112

second Pulse tube cooler

114

second pulse tube

116

second regenerator

118

second cold head

120

second cold shield

80

pressure oscillator

802

compressor

804

rotary valve

130

warm end of 104 . 114

132

Balastvolumen

134

Flow resistance, needle valve

136

second Inlet, Valve

138

flexible gas pipe

140

to cooling objects

142

Vakuumisoliergefäß

144

gas inlets

150

magnet

152

salt pill

154

Kevlar fibers

156

jig

158

thermal switch

160

magnetic shield

201

thermometer (superconducting film)

202

absorber

222.223

gold heater

230

substratum

235 236

Aluminiumbondpads on the thermometer

237, 238

Aluminiumbondpads at the gold heater

245, 246

superconducting elite wires on the thermometer

247, 248

superconducting wires at the gold heater

T _o

upper cooling temperature

T _M

middle cooling temperature

T _U

lower cooling temperature

Claims (11)

A detector apparatus comprising: a cooling system comprising: a first cooling device ( 10 ) with a two-stage pulse tube refrigerator system ( 102 . 112 ), which has a first pulse tube cooler ( 102 ) for providing an upper cooling temperature (T _o ) and for cooling a first cold shield ( 110 ) and a second pulse tube refrigerator ( 112 ) for providing a mean cooling temperature (T _m ) and for cooling a second cold shield ( 120 ), a second cooling device ( 20 ) For providing a lower annealing temperature (T _u) which is lower than the mean cooling temperature (T _m), wherein the second cooling device ( 20 ) from the second pulse tube refrigerator ( 112 ) is pre-cooled; and a detector device ( 30 ) for detecting particles, radiation or fields with a sensor based on a low temperature effect ( 201 ), wherein the detector device ( 30 ) to the second cooling device ( 20 ) is thermally coupled, characterized in that the first pulse tube refrigerator ( 102 ) From ambient temperature to the upper cooling temperature (T _o) is cooled and that the second pulse tube refrigerator ( 112 ) from ambient temperature to the mean temperature level (T _m ). Detector device according to claim 1, characterized in that that the first cooling device having a third or more pulse tube cooler. Detector device according to one of the preceding claims, characterized in that each of the pulse tube coolers ( 102 . 112 ): a pulse tube ( 104 . 114 ), at one end of which a cold heat exchanger ( 108 . 118 ), on which heat is absorbed from the outside, is provided, and at the other end of a warm heat exchanger ( 130 ), at which heat is discharged to the outside, is provided; a regenerator ( 106 . 116 ), which serves as a heat buffer; and a pressure oscillator ( 80 ), which serves to generate periodic pressure changes, wherein the pulse tube ( 104 . 114 ) at the end at which the cold heat exchanger ( 108 . 118 ) is provided via respective lines via the regenerator ( 106 . 116 ) with the pressure oscillator ( 80 ), so that a periodic displacement of a working gas between the pulse tube ( 104 . 114 ) and the pressure oscillator ( 80 ). Detector device according to claim 3, characterized in that the pulse tube ( 104 . 114 ) at the end where the warm heat exchanger ( 130 ) is provided, further a flow resistance ( 134 ) and a container ( 70 ) for receiving a ballast volume. Detector device according to claim 4, characterized in that each of the pulse tube coolers ( 102 . 112 ) a secondary line ( 135 ) extending from the end of the respective pulse tube ( 102 . 112 ), on which the warm heat exchanger ( 130 ), to the line ( 138 ) between the pressure oscillator ( 80 ) and the regenerator ( 106 . 116 ) and opens into it, the secondary line ( 135 ) a variable flow resistance ( 136 ) having. Detector device according to one of the preceding claims 3 to 5, characterized in that the second cooling device ( 20 ) at or near the cold heat exchanger ( 108 . 118 ) of a respective pulse tube ( 104 . 114 ) is arranged. Detector device according to one of the preceding claims, characterized in that the second cooling device ( 20 ) a demagnetization stage ( 150 ) or a ³ He / ⁴ He demixing cooler or a ³ He cooler or a mechanical cooling device such as a helium compressor radiator or an electric cooling device such as a Peltier element or a superconducting tunnel diode such as an NIS diode. Detector device according to one of the preceding claims 1 to 6, characterized in that the second cooling device ( 20 ) a demagnetization stage ( 150 ), which comprises: a salt pill ( 154 ), by a magnet ( 152 ) is surrounded; and a heat switch ( 160 ) for thermally coupling or decoupling the salt pill ( 154 ) to / from the magnet ( 152 ) during operation of the demagnetization stage ( 150 ). Detector device according to one of the preceding claims 7 to 8, characterized in that the second cooling device ( 20 ) several demagnetization stages ( 150 ). Detector device according to one of the preceding claims, characterized in that the cooling system ( 10 . 20 ) Part of a cryostat ( 90 ), in which the detector device ( 30 ), wherein the cryostat ( 90 ) further entrance window ( 70 ) for passing the particles to be examined and radiation from the exterior of the cryostat ( 80 ) into the interior of the cryostat ( 90 ) to the detector device ( 30 ) having. Detector device according to claim 10, characterized in that the cryostat ( 90 ) has a focusing device such as an X-ray lens or a Wolter arrangement or a Fresnel lens or focusing tube bundles or electrical focusing / defocusing or magnetic focusing / defocusing.