EP1073888A1

EP1073888A1 - Microcalorimeter

Info

Publication number: EP1073888A1
Application number: EP99915762A
Authority: EP
Inventors: Franz Von Feilitzsch; Jens HÖHNE; Josef Jochum; Johann Schnagl
Original assignee: CSP Cryogenic Spectrometers GmbH
Current assignee: CSP Cryogenic Spectrometers GmbH
Priority date: 1998-04-21
Filing date: 1999-04-16
Publication date: 2001-02-07
Also published as: DE29823004U1; WO1999054696A1; AU3421799A; DE19817786A1

Abstract

The invention relates to a microcalorimeter or a group of microcalorimeters, comprising a sensor component (1, 2) consisting of a thermometer (1) with a superconducting material and an absorber (2) which is thermally coupled to the thermometer, a cooling device (30), a heating device (20) and a read-out device. The cooling device and the heating device are thermally coupled to the sensor component separately from each other and at least the cooling device is thermally coupled to the sensor component across its surface. This design allows for the adjustment of a large dynamic area with minimum calorific output and for the cooling device and heating device to be optimized separately, resulting in improved energy resolution or signal acceleration. This type of microcalorimeter is used, for example, in material analysis or quality assurance by X-ray fluorescence analysis, preferably in the semiconductors industry, but is also suitable for the determination of molecules in biotechnology.

Description

description

Micro calorimeter

Technical field

The invention relates to a microcalorimeter according to claim 1, a group of microcalorimeters according to claim 23 and a device for measuring particles and radiation according to claim 26.

Such microcalorimeters have a wide range of applications. They are used, for example, in material analysis or quality assurance by means of X-ray fluorescence analysis, preferably in the semiconductor industry, but they are also suitable for the determination of molecules in biotechnology.

State of the art

Motivated by the research of new detectors for the detection of particles and radiation for astrophysical or particle physics experiments, detectors based on superconducting effects have been developed in recent years.

Microcalorimeter: structure, principle

One type of these detectors represent the so-called microcalorimeters. As can be seen in FIG. 1, they essentially consist of the components: sorber 2, thermometer 1 and a coupling 5 to a heat sink or cold bath together.

The thermometer 1 is a so-called phase transition thermometer with a superconducting material that changes from the normally conductive to the superconducting phase at a critical temperature, the transition temperature T _c . The transition from the normally conductive to the superconducting region does not occur abruptly due to material inhomogeneities, but rather over a region ΔT _{transition of a} few mK, as shown in FIG. 2. In the transition region with finite width ΔT _transition , the electrical resistance R of the superconducting material shows a strong temperature dependency, which makes it suitable for a very sensitive temperature measurement. The point of greatest slope with respect to the quotient from resistance change ΔR to temperature change ΔT in the transition region is selected as the working point or working temperature point of the superconducting material in order to achieve maximum sensitivity for temperature changes ΔT.

The principle of operation of the microcalorimeter is that a particle or radiation strikes the absorber 2 and interacts with it. The locally deposited energy .DELTA.E then spreads in the absorber, it thermalizes, and finally reaches the thermometer 1 connected to the heat sink. There, it causes a temperature increase .DELTA.T and leads to a change in resistance .DELTA.R, which is read out by readout electronics 40, such as it is shown in Figure 3 can be detected.

The readout electronics 40 shown in greatly simplified form in FIG. 3 have a readout circuit 44 with two branches connected in parallel, namely a branch having a shunt resistor R _s and a branch magnetic readout coil L and resistance R _τ connected in series, which is formed by the thermometer, having branch. The readout circuit 44 is fed by a constant current I ₀ . If a particle or radiation deposits energy in the microcalorimeter, this leads to a change in resistance in the thermometer R _τ , which causes a change in the current I _τ . This change in current in turn leads to a change in the magnetic field in the coil L, which is finally detected by an SQÜID 42 ("Superconducting Quantum Interference Device", a superconducting quantum interference device). The measurement signal obtained in this way is directly proportional to the incident energy ΔE.

US-A-5,641,961

From the American patent US-A-5,641,961 a low-temperature detector is known which has a phase transition thermometer. The electrical wiring of the readout electronics essentially corresponds to that as shown in FIG. 3. The signal generation or the acceleration of the signals is a special feature:

As shown in FIG. 4a, the temperature of the heat sink T _{s is kept} below the step temperature T _{c of} the superconductor or the thermometer. A suitable measuring voltage U on the thermometer dissipates the power P _H = P _joule = U ² / R in the thermometer, which is selected so that the thermometer is now stabilized in the transition area between the normally conductive and superconducting state, as shown in FIG. 4b is.

Is, as can be seen in Figure 4c, due to an incident particle or radiation the thermometer warms, this has an increase in resistance or temperature increase ΔT ₊ and thus an instantaneous reduction ΔT. the heating output corresponding to the temperature in the thermometer, which brings the temperature back to the working point. This directly counteracts the heating, which leads to a shortening of the signal length, ie an acceleration.

A disadvantage of the detector arises when measuring higher-energy radiation due to the limited dynamic range. As has been shown in FIG. 4a, the temperature of the heat sink T _{s is} below the transition temperature T _c or below the working temperature point, so that the thermometer must be heated to its working temperature point by a heating current flowing through the thermometer. The greater the temperature difference between the temperature of the heat sink and the working temperature point, the greater the heating power and the associated heating current must be. However, this in turn is limited because it must not exceed the critical current specific to the superconducting material of the thermometer. If, however, particles or radiation are to be measured that deposit a lot of energy, the temperature of the heat sink T _s must first be _set very low in order to ensure a large difference from the working temperature point and thus a large heating output. The greater the heating power that can be reduced to compensate for energy depositions, the greater the particle or radiation energy that can be detected with the shortened signal time. However, since the thermometer also serves as a heating device in the detector used here, the heating current is limited by the critical current and therefore the dynamic range. However, if the largest possible dynamic range is to be set, a large heating output or energy dissipation in the thermometer is required. After transforming the equation for the heating power shown above to P _joule = I ^{2 '} R, it can be seen that due to the limitation of the heating current up to the critical current, only the electrical resistance R can be varied in order to increase the heating power. However, this electrical resistance R depends on the length and width of the thermometer film, so that large lengths and small widths, for example, must be selected for large resistance values. This results in a limitation in the choice of the geometry of the thermometer.

Publication of 0. Meier

From the publication Inst. Phys. Conf. Ser. No 158, Paper presented at Applied Superconductivity, The Netherlands, 30 June - 30 July 1997, 1997 IOP Publishing LTD, with the title, "SQUID-Amplifier for Cryogenic Particle Detectors based on Superconducting Phase Transition Thermometers" by 0. Meier and others, a low-temperature calorimeter is known which has a thermometer with a heating device separate from it.

FIG. 5 shows a diagram of the electrical wiring of such a low-temperature calorimeter. The readout circuit 44 already explained in FIG. 3 is shown here with the shunt resistance R _s in one branch and the thermometer resistance R _τ and the coil L in the other branch. Furthermore, there is a heating resistor R _H , which is thermally coupled to the thermometer R _τ and via a control element 43 with a root extractor 43 and a conventional SQUID system 42 to the coil L for adjustment of the heating power is shown. If the thermometer is heated by an incident particle or incident radiation, the heating power at the resistor R _{H is} reduced by the just mentioned feedback in order to return the thermometer to the working temperature point. The signal is accelerated here by the feedback of the heating resistor R _H to the readout circuit 44.

By separating the thermometer and the heating device, the above-mentioned disadvantages of the detector from the American patent US-A-5,641,961 can be overcome. However, due to the fact that the thermometer is heated and cooled via a bond wire, which is both coupled to a heat sink and connected to a heating current source, the following disadvantages arise.

On the one hand, the bonding wire used as a heating device has a high thermal capacity in comparison to the thermometer and, due to the quasi punctiform or local coupling, a low thermal conductivity. This leads to a slower return of the thermometer to the working temperature point and thus to a deteriorated signal acceleration (see explanations on FIG. 4c). On the other hand, the heating power is reduced because, depending on the coupling, about half of the heating power is given off to the heat sink. In other words, in order to obtain a certain dynamic range, approximately twice the heating power must be applied. However, the inadvertent heating of the heat sink or the cold bath leads to an overuse of the cold bath and thus to a reduction in the service life. Presentation of the invention

It is an object of the present invention to further develop the microcalorimeter disclosed in the publication by 0. Meier in such a way that a large dynamic range can be set with minimal heating power.

This object is achieved with regard to the microcalorimeter according to claim 1, with regard to the group of microcalorimeters according to claim 23 and with regard to the device for measuring particles and radiation according to claim 26.

The microcalorimeter according to the present invention comprises a sensor component consisting of a thermometer with a superconducting material and an absorber thermally coupled to the thermometer, a cooling device, a heating device and a reading device. Because the cooling device and the heating device are separate devices which are thermally coupled separately from one another to the sensor component, the heating device can be arranged in such a way that the heat emitted by it flows through the thermometer into the cooling device. This leads to a minimization of the heating power or to a minimization of the cooling power to be applied by the cooling device, since heating power is not given directly and unused to the cooling device. Characterized in that at least the cooling device is thermally coupled to the sensor component, the cooling of the sensor component by the cooling device takes place uniformly, which in turn leads to a signal acceleration. This is additionally promoted by a flat thermal coupling of the heating device to the sensor component. Flat thermal Coupling here means that the coupling takes place over an extensive contact area and not only in a quasi-punctiform manner as with bond wires. Another advantage of the arrangement according to the invention is that the heating device or cooling device can be optimized separately from one another with regard to thermal capacity, thermal conductivity or geometry. For example, the areal heat coupling between the thermometer and the heating device can be brought to a suitable value in order to obtain an optimal signal amplitude. It is advantageous to set a poorer thermal conductivity in comparison to the thermometer, which results in a slower energy dissipation into the heat sink in comparison with the reduction in the heating power and thus a large signal amplitude or pulse height. This ensures a good energy resolution. However, the areal coupling offers the decisive advantage of uniform cooling of the thermometer, as a result of which temperature gradients within the thermometer are avoided and, in turn, the signals are accelerated and the energy resolution increased.

According to an advantageous embodiment of the invention, the heating device has one or more heating elements which are coupled to the sensor component. This makes it possible to heat either only the thermometer or only the absorber by means of a heating element or simultaneously the thermometer and the absorber with one heating element each. Furthermore, a large number of heating elements can be coupled to the sensor component in order to ensure an even supply of heat.

According to a further advantageous embodiment of the invention, the heat capacity of a heating element is dimensioned such that it is less than or equal to the heat capacity of the system of thermometer and absorber. Here- from it follows that only a small amount of heat can be stored in the heating element, which is rapidly dissipated when the thermometer is heated as a result of an energy deposition of an incident particle or radiation after reduction of the heating current in the heating element. As a result, a rapid return of the thermometer to the working temperature point can be achieved, which causes a signal acceleration. This improved acceleration can also be achieved by optimizing the thermal conductivity, which is created in that a heating element is formed by a heating film which is connected to a heating current source and is applied to the surface of the sensor component. It proves to be advantageous here to make the heating film meandering. Instead of applying a heating film, it is also possible for the heating element to be formed by a resistance element which is connected to a heating current source and which is glued to the sensor component.

According to a further advantageous embodiment of the invention, the cooling device for coupling to the sensor component has, for example, a substrate, an electrically insulating layer or a membrane. The advantages of the membrane lie in the fact that, compared to the substrate, it enables a weaker, but nevertheless uniform, thermal coupling of the thermometer to the heat sink. Furthermore, when measuring X-rays, there is the advantage that the probability of absorption below the thermometer is very minimized due to the small thickness compared to the substrate. In contrast to the substrate, there is therefore no deterioration in the energy resolution due to interfering signals.

By a large signal amplitude and thus also a good energy resolution of the energy occurring in the absorber 10

To be able to register events on the thermometer, it is necessary to ensure a good coupling of the two components. This can be achieved by applying the thermometer directly to the absorber. If, on the other hand, a spatial resolution of the event occurring in the absorber is desired, the absorber is locally coupled to the thermometer via a connecting device. The connecting device can be a bond wire that connects the absorber and the thermometer. However, it is also possible to arrange the absorber and thermometer next to one another in such a way that again only a local coupling is formed.

For an improved spatial resolution of an event occurring in the absorber, it is possible according to a further advantageous embodiment of the invention to design the thermometer with a large number of thermometer elements which are each coupled to the absorber at different points.

The readout electronics advantageously have a SQUID system with a single SQUID or a group of SQUIDs.

The following materials are advantageous for the components used in the microcalorimeter. The thermometer can have, for example, an element superconductor, a high-temperature superconductor, an alloy, a two-layer structure composed of two superconductors, a two-layer structure composed of a superconductor and a normal conductor, or a three-layer structure composed of normal conductors and superconductors. The element superconductors consist, for example, of tungsten, iridium, aluminum or tantalum, the two-layer structures from a combination of iridium / gold, iridium / silver, aluminum / silver, tantalum / silver, tantalum / gold, titanium / aluminum or titanium 11

tan / gold. The absorber and the substrate have, for example, a dielectric such as sapphire, a semiconductor such as silicon, germanium or gallium arsenide, or a metal such as gold or silver, a semimetal such as bismuth, semimetal alloys such as mercury-telluride, cadmium-telluride or mercury-cadmium-plate uride, or super conductor such as tantalum, aluminum or lead or a combination of the individual materials. The heating film can be made of gold or silver or platinum. The substrate is made of silicon, germanium or sapphire, for example, and the membrane is made of silicon nitride, silicon oxide or aluminum oxide.

According to a further advantageous embodiment of the invention, a multiplicity of microcalorimeters according to the present invention are arranged next to one another to form a group of microcalorimeters. On the one hand, three-dimensional structures can be formed, which are arranged, for example, for observation around an object. On the other hand, two-dimensional structures are also possible, in which the large number of microcalorimeters, analogous to a CCD camera, is arranged in one plane.

According to a further advantageous embodiment of the invention, a microcalorimeter or a group of microcalorimeters according to the invention is placed in a device for measuring particles and radiation with a first cooling device, with a second cooling device which is precooled by the first cooling device and itself an operating temperature ( T _s ) and used with an inlet opening for the passage of particles and radiation as a detection device for detecting particles and radiation. The microcalorimeter is thermally coupled to the second cooling device. 12

The first cooling device advantageously has a coupled nitrogen / helium cooler, a pulse tube cooler, a mechanical cooling device such as a helium compression cooler or an electrical cooling device such as a Peltier element. The second cooling device has, for example, a demagnetization stage, a ³ He / He separation cooler, a ³ He cooler, a mechanical cooling device such as a helium compressor cooler, an electrical cooling device such as a Peltier element or a superconducting tunnel diode such as an NIS diode.

According to a further advantageous embodiment of the device for measuring particles and radiation, the device has a focusing device such as, for example, an X-ray lens, a Wolter arrangement, a Fresnel lens, focusing tube bundles, electrical focusing devices or magnetic focusing devices which point in the direction from the detection device considered the inlet opening, is arranged in front of or behind the inlet opening.

Further details, features and advantages of the invention result from the following description of preferred embodiments with reference to the drawing.

Show it:

FIG. 1 shows a schematic illustration of a microcalorimeter with its essential components,

FIG. 2 shows a diagram which shows a typical course of a phase transition of a thermometer in a microcalorimeter, 13

FIG. 3 shows a greatly simplified schematic illustration of the readout electronics of a microcalorimeter,

4 each show a resistance-temperature diagram, by means of which the setting of the thermometer to the working temperature point or the reaction of the thermometer to events taking place in the absorber are explained,

FIG. 5 shows a schematic representation of the electrical wiring of a low-temperature calorimeter in the prior art according to 0. Meier and others,

FIG. 6 shows a schematic illustration of a first exemplary embodiment of the invention,

FIG. 7 shows a schematic illustration of a second exemplary embodiment of the invention,

FIG. 8 shows a schematic illustration of a third exemplary embodiment of the invention,

9 shows a schematic representation of a real geometry of the third exemplary embodiment of the invention,

10 shows a schematic representation of a real geometry of a fourth exemplary embodiment of the invention,

FIG. 11 shows a schematic illustration of a fifth exemplary embodiment of the invention,

FIG. 12 shows a schematic illustration of an exemplary embodiment of a group of microcalocal 14

rimimeters in a flat arrangement according to the invention, and

FIG. 13 shows a schematic illustration of an exemplary embodiment of a device for measuring radiation according to the invention.

Microcalorimeter: embodiments

FIG. 6 shows a schematic illustration of the arrangement of the individual components of a microcalorimeter according to a first exemplary embodiment of the present invention. Here, as in the following figures, the same parts are designated with the same reference numerals.

When viewed from the bottom up, a thermometer film 1 is first applied to a substrate 30 connected to a heat sink (not shown), then an absorber 2 and a heating film 20 are applied to this thermometer film 1. All components are thermally coupled to one another. As has already been mentioned, due to the coupling of the thermometer 1 over a large area to the heat sink, uniform cooling is achieved, which causes a signal acceleration. Furthermore, the entire heating power applied by the heating film 20 is dissipated into the heat sink via the thermometer 1, so that essentially only the heating power necessary for setting the working temperature point has to be provided in order to set a certain dynamic range.

A typical manufacturing process is briefly outlined with regard to the explanation of the real geometry of the third advantageous embodiment. 15

FIG. 7 shows a schematic representation of the arrangement of the individual components of a microcalorimeter according to a second exemplary embodiment of the present invention.

Similar to the first advantageous embodiment, when viewed from bottom to top, a thermometer film 1 is first applied to a substrate 30 connected to a heat sink (not shown). An absorber 2 is then applied to this thermometer film 1 and a heating film 20 is applied to this. Here, too, all components are thermally coupled to one another. In contrast to the first embodiment, the heating film 20 is coupled to the absorber 2 to achieve a more extensive and thus more uniform heating of the thermometer 1. This can also cause the signal to accelerate.

FIG. 8 shows a schematic illustration of the arrangement of the individual components of a microcalorimeter according to a third exemplary embodiment of the present invention. This embodiment represents a combination of the first two embodiments.

A thermometer film 1 is applied to a substrate 30 connected to a heat sink (not shown), and an absorber 2 and a heating film 20 are applied to this thermometer film 1. Finally, the absorber 2 is again provided with a heating film 20. All components are thermally coupled to one another. The heating films 20 on the absorber 2 and on the thermometer 1 can be connected in series, in parallel or independently with two different sources. One advantage of this arrangement is that a large-area and thus uniform heating of the thermometer 1 is provided, which means that 16

ne good thermal conductivity can be achieved. Furthermore, depending on the heat capacity of the individual components 1, 2, 20, a more or less fast active cooling of absorber 2 and thermometer 1 can be achieved. Active cooling means the loss of heating power in the event of an event taking place in the absorber. As has already been mentioned, a low heat capacity of the absorber 2 and heating film 20 components or good thermal conductivity to the thermometer 1 are a prerequisite for rapid active cooling and thus acceleration of the signals.

A special feature of this embodiment is the areal coupling of the absorber 2 to the thermometer 1. If there is an energy deposition of a particle in the absorber 2, the energy thermalizing in the direction of the thermometer 1 can be quickly released to the thermometer 1. This causes a rapidly increasing signal pulse with a large amplitude, whereby a good energy resolution with regard to incident particles or radiation to be observed can be achieved.

FIGS. 9 show a schematic representation of a real geometry of the individual components of a microcalorimeter according to the third exemplary embodiment of the invention.

9a shows a top view of the microcalorimeter arrangement, FIG. 9b shows a sectional view along line bb shown in FIG. 9a and FIG. 9c shows a sectional view along line cc shown in FIG. 9a. Viewed from top to bottom, thermometer 1 is electrically contacted via contacting surfaces made of aluminum, so-called aluminum bond pads 35, 36, and via superconducting wires 45, 46 by means of an 17

seelektronik (not shown), which essentially corresponds to that known from the publication by 0. Meier. Gold heaters are connected as heating elements via an electrically conductive absorber 2. They are electrically contacted via aluminum bond pads 37, 38 and connected to a voltage source (not shown) via superconducting wires 47, 48. The gold heaters are coupled to thermometer 1 and the absorber via their thermal conductivity.

A typical manufacturing process for such an arrangement of the component of a microcalorimeter is briefly described as follows. First, a thermometer film 1 is evaporated or sputtered onto the substrate 30. The thermometer 1 is then structured by means of a photolithographic process or etching and sputtering. A so-called lift-off mask for the heaters 22, 23 is then created using a photolithographic process. The heaters 22, 23 are vapor-deposited or sputtered and the lift-off mask is removed. A lift-off mask for the absorber 2 is then created using a photolithographic process. The absorber 2 is evaporated or sputtered and the lift-off mask is removed. A lift-off mask for the aluminum bond pads 35, 36, 37, 38 is then created using a photolithographic process. The aluminum bond pads 35, 36, 37, 38 are sputtered on and the lift-off mask is removed.

10 shows a schematic representation of a real geometry of the individual components of a microcalorimeter according to the fourth exemplary embodiment of the invention.

The structure of the microcalorimeter of this embodiment corresponds essentially to that of the third two 18th

playful embodiment, with the difference that the thermometer 1 is arranged on a membrane 32. This membrane 32 is applied to the substrate 30 during manufacture, the substrate 30 below the thermometer 1 then being removed, for example by etching. As already mentioned, this arrangement improves the energy resolution, particularly when measuring X-ray radiation, since the probability of disruptive signals resulting from events below the thermometer 1 is minimized.

Typical dimensions for the components used in microcalorimeters according to the present invention are 1 mm × 1 mm × 0.1 μm for the thermometer, 250 μm × 250 μm × 1 μm for the absorber 2, 1.5 mm × 1.5 mm × 0.4 for the membrane 32 μm and for the substrate 30 1.5mm x 1.5mm x lmm.

FIG. 11 shows a schematic illustration of the arrangement of the individual components of a microcalorimeter according to a fifth exemplary embodiment of the present invention.

The structure of the microcalorimeter of this embodiment essentially corresponds to that of the third exemplary embodiment, with the difference that the thermometer 1 is coupled to the absorber 2 via a bonding wire 5, the absorber 2 not being provided with a heating element. Although this small-area or local coupling of the two components 1, 2 results in poorer thermal conductivity than the large-area coupling in accordance with the third embodiment and thus a poorer energy resolution, a spatially resolved detection of events taking place in the absorber 2 is possible. 19

If an incident particle or incident radiation interacts in the absorber 2 in the vicinity of the connecting bonding wire 5, heat is released relatively quickly via the bonding wire 5 to the thermometer 1 and only a small part of the deposited energy is thermalized in the absorber. This results in a rapidly increasing signal pulse with a large amplitude. If, however, an incident particle or radiation interacts in the absorber 2, far away from the connecting bonding wire 5, the energy first thermalizes in the absorber 2 and only then reaches the thermometer 1. A slowly increasing signal pulse with a small amplitude thus arises.

Group of micro calorimeters

FIG. 12 shows a schematic illustration of an exemplary embodiment of a group of microcalorimeters in a planar arrangement according to the invention.

Microcalorimeters with their sensor components consisting of absorber 2 and thermometer 1, which are arranged in a plane next to one another similar to the principle of a CCD camera, are shown in a greatly simplified manner and, for the sake of a better overview, shown somewhat apart. In this way, two-dimensional imaging with the advantages for the microcalorimeter according to the invention can be created.

Device for measuring particles and radiation

FIG. 13 shows a schematic illustration of an exemplary embodiment of a device for measuring radiation according to the invention. 20th

Viewed from the inside out, a detection device 100 for particles and radiation, in this case an inventive microcalorimeter or a group of microcalorimeters, is thermally coupled to a demagnetization stage 110, which represents a heat sink with a temperature of approximately 50 to 100 mK . This arrangement is surrounded by a container 112 filled with liquid helium, which provides approximately a temperature of 4K. Separated by a vacuum 102, a helium-cooled shield 114 follows, which, separated by a further vacuum 102, is surrounded by a container 116 filled with liquid nitrogen, which provides a temperature of approximately 77K. Separated by a further vacuum 102, the entire inner arrangement is surrounded by an outer jacket 120. Entry windows 118 are provided so that radiation can strike the detection device 100.

Such a device is suitable, for example, for examining surface contaminants by means of X-ray fluorescence analysis, the basic measurement principle being able to be represented as follows. With an X-ray source, X-rays are radiated onto the surface to be examined, whereby the atoms on the surface are excited. During their relaxation or de-excitation, these surface atoms emit the so-called X-ray fluorescence radiation, which has a characteristic wavelength or frequency for each element. The detection of the X-ray fluorescence radiation takes place with the device described above, it being possible to use the measured frequency distribution to infer the frequency of the surface contaminations and their exact composition. 21

A device according to the invention has the advantage that, due to the large, adjustable dynamic range, a wide energy spectrum of radiation can be detected. Furthermore, due to the good energy resolution, an exact differentiation of different elements is possible, even if their X-ray lines are close together. In addition, large surfaces can be examined because, on the one hand, due to the signal acceleration, little measurement time is required and, on the other hand, due to the minimized heating power, the second cooling device, such as the demagnetization stage, can be kept at its temperature for a long time.

Disclosed is a microcalorimeter or a group of microcalorimeters which have a sensor component consisting of a thermometer with a superconducting material and an absorber thermally coupled to the thermometer, a cooling device, a heating device and a readout device, the cooling device and the heating device being separate from one another are thermally coupled to the sensor component and at least the cooling device is thermally coupled flat to the sensor component. This arrangement allows a large dynamic range to be set with minimal heating power, but it is also possible to optimize the cooling device and the heating device separately, as a result of which an improved energy resolution or signal acceleration is achieved. Microcalorimeters of this type are used, for example, in material analysis or quality assurance by means of X-ray fluorescence analysis, preferably in the semiconductor industry, but are also suitable for determining molecules in biotechnology. 22

Reference list

1 thermometer

2 absorbers

5 bond wire between absorber and thermometer

9 incident particles

10 Cooling device, coupling to the heat sink

20 heating device, heating film

22, 23 gold heater

30 substrate

32 membrane 3 355,. 3 366 aluminum bond pads on the thermometer

37, 38 aluminum bond pads on gold heater

40 readout electronics

42 SQUID, SQUID system

43 control element, root extractor 4 444 readout circuit

45, 46 superconducting read-out wires on the thermometer

47, 48 superconducting wires on the gold heater

100 Detection device for particles / radiation 1 10022 vacuum

110 degaussing stage, 2nd cooling device

112 container with liquid helium

114 helium-cooled shield 1 11166 container with liquid nitrogen

118 entry window

120 outer coat

ΔE deposited energy

Io electricity through readout electronics II _ττ current through resistor R _τ

Readout coil 23

∑ P _ou i _e heating power

R electrical resistance

ΔR change in electrical resistance

R _τ electrical resistance of the thermometer T temperature

T _c transition temperature of a superconductor

T _s temperature of the heat sink or cold bath

ΔT change in temperature ΔT ₊ temperature increase

ΔT_ temperature decrease

ΔT _transition transition area, transition width

Claims

24 claims

1. Microcalorimeter for measuring an energy pulse, with: a sensor component (1, 2) consisting of a thermometer (1), which has a superconducting material with a finite width transition temperature range (ΔT _transition ) from the normal conducting to the superconducting phase , where the transition temperature (T _c ) lies in the middle of the transition temperature range (ΔT _transition ) and the electrical resistance (R) of the superconducting material within the transition temperature range (ΔT _transition ) increases with increasing temperature, and from an absorber (2) which increases the thermometer (1) is thermally coupled and in which incident particles (9) or radiation (9) interact; a cooling device (10) which has an operating temperature (T _s ) below the step temperature (T _c ); a heating device (20, 22, 23) separate from the thermometer (1), by means of which the temperature operating point of the thermometer (1) can be set within the transition temperature range (ΔT _transition ); a readout electronics (40) which is electrically connected to the thermometer (1) and detects the current flowing through the thermometer (1), characterized in that the cooling device (10) and the heating device (20) are connected to the sensor component (1, 2 ) are thermally coupled separately and that at least the cooling device (10) is thermally coupled to the sensor component (1, 2). 25th

2. Microcalorimeter according to claim 1, characterized in that the heating device (20,22,23) has one or more heating elements (20,22,23) which are coupled to the sensor component (1,2).

3. Microcalorimeter according to claim 1, characterized in that the heat capacity of a heating element (20,22,23) is less than or equal to the heat capacity of the sensor component (1,2).

4. Microcalorimeter according to one of claims 1 to 3, characterized in that a heating element (20,22,23) of a heating film connected to a heating current source

(20,22,23) is formed, which is applied to the surface of the sensor component (1,2).

5. Microcalorimeter according to claim 4, characterized in that the heating film (20,22,23) is formed meandering.

6. Microcalorimeter according to one of claims 1 to 3, characterized in that a heating element (20,22,23) is formed by a resistance element connected to a heating current source, which is glued to the sensor component (1,2).

7. Microcalorimeter according to one of claims 1 to 6, characterized in that the heating device (20,22,23) has a heating element (20,22,23) which is coupled to the thermometer (1).

8. Microcalorimeter according to one of claims 1 to 6, characterized in that the heating device (20,22,23) has a heating element (20,22,23) which is coupled to the absorber (2). 26

9. Microcalorimeter according to one of claims 1 to 6, characterized in that the heating device

(20, 22, 23) has two heating elements (20, 22, 23), each of which is coupled to the thermometer (1) and to the absorber (2).

10. Microcalorimeter according to one of claims 1 to 9, characterized in that the cooling device (10) has a substrate connected to a heat sink (30) on which the sensor component (1, 2) is applied.

11. Microcalorimeter according to one of claims 1 to 9, characterized in that the cooling device (10) has a membrane connected to a heat sink (32) on which the sensor component (1, 2) is applied.

12. Microcalorimeter according to one of claims 1 to 9, characterized in that the cooling device (10) has an electrically insulating layer connected to a heat sink, on which the sensor component (1, 2) is applied.

13. Microcalorimeter according to one of claims 1 to 12, characterized in that the absorber (2) is applied directly to the thermometer (1).

14. Microcalorimeter according to one of claims 1 to 12, characterized in that the absorber (2) is coupled to the thermometer (1) via a connecting device (5).

15. Microcalorimeter according to one of claims 1 to 12, characterized in that the thermometer (1) consists of a plurality of thermometer elements, each of which is coupled to the absorber (2) at different points.

16. Microcalorimeter according to one of claims 1 to 15, characterized in that the readout electronics (40) has a SQUID system (42).

17. Microcalorimeter according to one of claims 1 to 16, characterized in that the thermometer (1) an element superconductor or a high-temperature superconductor or an alloy or a two-layer structure of two superconductors or a two-layer structure of a superconductor and a normal conductor or a three-layer structure of normal conductors and superconductors having.

18. Microcalorimeter according to claim 17, characterized in that the element superconductor made of tungsten or

Iridium or aluminum or tantalum, and the two-layer structures consist of a combination of iridium / gold or iridium / silver or aluminum / silver or tantalum / silver or tantalum / gold or titanium / aluminum or titanium / gold.

19. Microcalorimeter according to claim 1 to 18, characterized in that the absorber (2) made of a dielectric such as sapphire, or a semiconductor such as silicon or germanium or gallium arsenide, or of a metal such as gold or silver, or a semimetal such as bismuth , or a semi-metal alloy such as mercury-telluride or cadmium-telluride or mercury-cadmium-plate uride, or a superconductor such as tantalum or aluminum or lead or a combination of the individual materials.

20. Microcalorimeter according to claim 1 to 19, characterized in that the heating film (20,22,23) consists of gold or silver or platinum. 28

21. Microcalorimeter according to claim 1 to 20, characterized in that the substrate (30) made of a dielectric such as sapphire, or a semiconductor such as silicon or germanium or gallium arsenide, or of a metal such as gold or silver, or a semimetal such as bismuth, or a semi-metal alloy such as mercury telluride or cadmium telluride or mercury-cadmium plate uride, or a superconductor such as tantalum or aluminum or lead or a combination of the individual materials.

22. Microcalorimeter according to claim 1 to 21, characterized in that the membrane (32) consists of silicon nitride or silicon oxide or aluminum oxide.

23. Group of microcalorimeters, characterized in that a plurality of microcalorimeters according to one of claims 1 to 22 are arranged side by side.

24. Group of microcalorimeters according to claim 23, characterized in that the plurality of microcalorimeters is arranged in one plane.

25. Group of microcalorimeters according to claim 23, characterized in that the plurality of microcalorimeters is arranged in the form of a three-dimensional structure.

26. A device for measuring particles and radiation, comprising: a first cooling device (112, 114, 116); a second cooling device (110) which is precooled by the first cooling device (112, 114, 116) and which itself provides an operating temperature (T _s ); an entrance opening (118) for the passage of particles and radiation; 29

a detection device (100) for detecting particles and radiation, characterized in that the detection device (100) is a microcalorimeter according to one of claims 1 to 22 or a group of microcalorimeters according to one of claims 23 to 25, the one or the second Cooling device (110) are thermally coupled.

27. A device for measuring particles and radiation according to claim 26, characterized in that the first

Cooling device (112, 114, 116) has a coupled nitrogen / helium cooler or a pulse tube cooler or a mechanical cooling device such as a helium compression cooler or an electrical cooling device such as a Peltier element.

28. Device for measuring particles and radiation according to one of claims 26 or 27, characterized in that the second cooling device (110) has a demagnetization stage or a ³ He / He separation cooler or a ³ He cooler or a mechanical one Has cooling device such as a helium compressor cooler or an electrical cooling device such as a Peltier element or a superconducting tunnel diode such as an NIS diode.

29. Device for measuring particles and radiation according to one of claims 26 or 28, characterized in that the device has a focusing device such as an X-ray lens or a Wolter arrangement or a Fresnel lens or focusing tube bundle or electrical focusing devices or magnetic focusing devices viewed from the detection device in the direction of the inlet opening, is arranged in front of or behind the inlet opening.