Inter-laboratory Comparison of Impedance-Type Hygrometer in the Range from 10 % to 95 % at 5\,^{\circ }\hbox {C} to 55\,^{\circ }\hbox {C}

Traceability in the field of relative humidity (RH) measurements is typically assured indirectly through dew point and temperature scales. Conducting an inter-laboratory comparison at the national metrology institute (NMI) level, using a direct approach with a precision RH hygrometer as a transfer standard would, therefore, be of a particular interest, especially if the measurement setups were of a different type. This paper presents an RH comparison at the NMI level between the National Metrology Institute of South Africa (NMISA) and University of Ljubljana, Faculty of Electrical Engineering, Laboratory of Metrology and Quality (MIRS/UL-FE/LMK). In scope of this inter-comparison, calibration of an impedance-type hygrometer in the range from 10 %rh to 95 %rh at air temperatures of \(5\,^\circ \hbox {C}\) , \(25\,^\circ \hbox {C}\) , and \(55\,^\circ \hbox {C}\) , respectively, was performed. It was recommended that the participants use their standard procedure for the calibration of RH sensors and, at the same time, follow the specific criteria of the review protocol for uncertainty estimation accepted by Bureau International des Poids et Mesures (BIPM), marked as BIPM CCT-WG8/CMC-10. An interesting part of the comparison was the two different calibration methods which were used by the two partners and which also have different traceability routes. MIRS/UL-FE/LMK calibrated the sensor in the humidity generator by comparison against the reference chilled mirror hygrometer, which is traceable to the MIRS/UL-FE/LMK primary dew-point generator. NMISA calibrated the transfer standard against certified salt solutions, which were kept in a temperature-controlled chamber. Results showed acceptable agreement at all 15 calibration points.     

Comparison of the Calibration of Standard Platinum Thermometers by Comparison in the Range from $$-80\,^{\circ }\hbox {C}$$ to $$300\,^{\circ }\hbox {C}$$300∘C

In this paper, an interlaboratory comparison in the field of measurement of temperature is presented. Within the comparison, calibration of a standard platinum resistance thermometer (SPRT) by comparisons in the range from \(-80\,^{\circ }\hbox {C}\) to \(300\,^{\circ }\hbox {C}\) was performed. At the same time, in order to support the calibration and measurement capabilities (CMCs) entries of the participating laboratories, we have registered this as EURAMET Project 1251 (Comparison of the calibration of standard platinum resistance thermometers in the range from \(-80\,^{\circ }\hbox {C}\) to \(300\,^{\circ }\hbox {C}\) by comparison). It was recommended that the participants use their standard procedure for the calibration of the standard platinum resistance thermometers and follow instructions from the protocol of EURAMET Project 1251 during the temperature calibration and, if possible, avoid making extra time-consuming measurements. The interlaboratory comparison was organized by the University of Ljubljana, Faculty of Electrical Engineering, Laboratory of Metrology and Quality (MIRS/UL-FE/LMK) in the scope of the IPA 2011 project. The interlaboratory comparison included a maximum of eleven measurement points. However, certain laboratories did not perform measurements at all points in the range. They have performed only measurements in the range that they cover. Prior to the calibration by comparison in each laboratory, a test measurement at the triple point of water or ice point was done in order to assess the stability of the instruments. Results of the comparison show that all the measurements agree within declared uncertainties and thus supporting declared capabilities of the participating laboratories.     

Practical Calibration of Platinum Resistance Thermometers in the Range ?190?��C to 0?��C

The results obtained in the characterization of a low-temperature comparator and its performance in relation to the calibration of metal and borosilicate sheathed standard platinum resistance thermometers (SPRTs) calibrated at the International Temperature Scale of 1990 (ITS-90) fixed points, are presented and discussed. The principal influence quantities are addressed and the estimation of measurement uncertainty supporting the calibration and measurement capability (CMC) accredited by Entidad Nacional de Acreditación (ENAC), the Spanish Accreditation Body, are presented and discussed.     

A New Co–C Eutectic Fixed-Point Cell for Thermocouple Calibration at 1324\,^{\circ }\mathrm{C}

The eutectic Co–C is a promising system to serve as a thermometric fixed point beyond the freezing point of copper ( \(1084.62\,^{\circ }\mathrm{C}\) ). Some national metrology institutes have developed, characterized, and compared their Co–C fixed-point cells based on conventional designs. Indeed, the fixed-point cells constructed are directly inspired by the technologies applied to the fixed points of the ITS-90 to the lower levels of temperature. By studying the eutectic metal–carbon systems, is appears that the high temperatures of implementation give a set of difficulties, such as the strong mechanical stresses on the graphite crucibles, due to the important thermal expansion of the eutectic alloys during their phase transitions. If these devices are suitable with research activities to serve like primary standards, it is not envisaged to propose them for a direct application to the calibration activities for the industry. As regards the limited robustness of the conventional fixed-point cells constructed, an intensive use of these device would not be reasonable, in term of cost for example. In this paper, a new Co–C fixed-point design is introduced. This low cost device has been developed specifically for intensive use in thermocouple calibration activities, with the aim of achieving the lowest level of uncertainties as is practicable. Thus, in this paper, the metrological characterization of this device is also presented, and a direct comparison to a primary Co–C fixed-point cell previously constructed is discussed.     

Climatic Chamber for Temperatures up to 180\,^{\circ }\mathrm{C} and Pressures up to 0.5 MPa

A new relative-humidity setup was developed for calibrating sensors in the temperature range from \(-40\,^{\circ }\mathrm{C}\) up to \(180\,^{\circ }\mathrm{C}\) and at pressures down to 700 hPa and up to 0.5 MPa. The setup is based on the chamber-in-chamber model: a small additional chamber is positioned inside a climatic chamber. While the climatic chamber is used to generate the air temperature, a pre-conditioned gas from outside the climatic chamber delivers the required humidity in the new pressure chamber. Validation of the setup at atmospheric pressure showed relative-humidity uncertainties of 0.2 %rh at 5 %rh over the whole temperature range and 0.4 %rh at 95 %rh for temperatures above \(0\,^{\circ }\mathrm{C}\) . Below \(0\,^{\circ }\mathrm{C}\) , the maximum uncertainty increases to 0.9 %rh due to the influence of the temperature homogeneity. The temperature uncertainty of the new setup is between \(0.10\,^{\circ }\mathrm{C}\) and \(0.21\,^{\circ }\mathrm{C}\) . Five commercially available relative-humidity sensors, of different type and manufacturer and all suitable for high temperatures, were calibrated in the new setup. The measurements showed deviations outside the stated specifications of the manufacturer and the need of traceable calibration facilities.     

Coupled Dynamics for Superfluid $$^4\hbox {He}$$ in a Channel

We study the coupled dynamics of normal and superfluid components of superfluid \(^4\hbox {He}\) in a channel considering the counterflow turbulence with laminar normal component. In particular, we calculated profiles of the normal velocity, the mutual friction, the vortex line density and other flow properties and compared them to the case where the dynamic of the normal component is “frozen.” We have found that the coupling between the normal and superfluid components leads to flattening of the normal velocity profile, increasingly more pronounced with temperature, as the mutual friction, and therefore, coupling becomes stronger. The commonly measured flow properties also change when the coupling between the two components is taken into account.     

Hysteresis and Instability in Some IPRT Sensors Within Temperature Ranges Extending from $$-196\,^{\circ }\hbox {C}$$ to $$150\,^{\circ }\hbox {C}$$150∘C

Industrial platinum resistance thermometer (IPRT) sensors or probes suffer from some instability on cycling over significant ranges of temperature and, specifically, from hysteresis in which the resistance tends to follow different paths for increasing temperatures compared with decreasing temperatures. The effect is well known, and cases of quite large hysteresis have been reported in the literature. Therefore, in establishing calibration and measurement capabilities for IPRT calibrations it is important to include an assessment of the performance which can be expected of a ‘typical good’ IPRT and to include this in the overall uncertainty which the laboratory can expect to achieve in such calibrations, even though the effect itself is outside the laboratory’s control. This paper presents results which have been obtained in cycling IPRT probes from four sources within various temperature ranges of current interest at NPL, between \(-196\,^{\circ }\hbox {C}\) and \(150\,^{\circ }\hbox {C}\), to see what levels of hysteresis may be expected. The cycles were carried out quite quickly in order to detect the hysteresis before it was mitigated by relaxation effects, but the time dependence was not itself studied. In most cases, hysteresis was \({<}0.0025\,^{\circ }\hbox {C}\) between \(0\,^{\circ }\hbox {C}\) and \(100\,^{\circ }\hbox {C}\), and \({<}0.0035\,^{\circ }\hbox {C}\) when the range extended down to \(-80\,^{\circ }\hbox {C}\) or up to \(150\,^{\circ }\hbox {C}\). Greater instability occurred when the sensors were cooled to \(-196\,^{\circ }\hbox {C}\).     

Primary Dielectric-Constant Gas Thermometry in the Range from 2.4 K to 26 K at PTB

New dielectric-constant gas-thermometry (DCGT) measurements were performed at PTB from 2.4 K to 26 K in order to establish a temperature scale with reduced uncertainty. The progress concerning the measurement of capacitance changes, temperature, and pressure compared with the results published in 1996 is described. This is the first step on the way to determine the Boltzmann constant at the triple point of water. At more than 20 temperatures, isotherms were measured and evaluated performing both single- and multi-isotherm fits. Based on this evaluation, a more accurate DCGT scale has been established that is compared with the constant-volume gas-thermometry scale NPL-75, being one basis of the International Temperature Scale of 1990. Coincidence has been found within only a few tenths of a millikelvin above 3.3 K. This gives, together with literature data, confidence with respect to thermodynamic temperature at this level. Emphasis is also given to the results obtained for the virial coefficients, especially below 3.3 K, where the 1996 DCGT results show strong deviations from the expected behavior. The new experimental data for the second virial coefficient are compared with ab initio calculations.     

Calibration of Radiation Thermometers and Blackbodies in the Temperature Range from 160 ��C to 420 ��C

The NMIJ has established a new calibration facility consisting of a 1.6??m radiation thermometer and three fixed-point blackbodies of indium (156.5985 °C), tin (231.928 °C), and zinc (419.527 °C) in the temperature range from 160 °C to 420 °C. The expanded uncertainties (k = 2) of the fixed-point blackbodies are estimated to be 28 mK for the In point, 22 mK for the Sn point, and 32 mK for the Zn point. The expanded uncertainties in the temperature scale of the 1.6??m radiation thermometer are estimated to be 40 mK to 77 mK. When this standard is used to calibrate devices under test to be used in industry, uncertainties (k = 2) of 61 mK for the In point, 67 mK for the Sn point, and 99 mK for the Zn point, 91 mK to 136 mK for a 1.6??m radiation thermometer, and 73 mK to 116 mK for a variable-temperature blackbody can be achieved.     

Method for the Thermal Characterization of PCM Systems in the Volume Range from 100 ml to 1000 ml

The storage of latent heat in phase change materials (PCM) is of great interest in many applications, for example in building applications. However, there is no standard method for the determination of the thermophysical properties of application-sized PCM specimens, i.e., specimens with sizes around 100 ml to 1000 ml. In order to close this metrological gap, a commercially available heat flow meter was modified to perform enthalpy measurements. The feasibility of this method was proven by performing comparative measurements on a stainless steel specimen using both the standard method DSC and the modified heat flow meter. Furthermore, measurements on a gypsum board with microencapsulated PCM were performed with the heat flow meter in order to determine the enthalpy. The coincidence with literature values is within ±4% which demonstrates that this method is a good choice for performing measurements on application-sized PCM specimens.     

Thermodynamic Properties of ^{4}He Gas in the Temperature Range 4.2–10 K

The thermodynamic properties of $^{4}$ He gas are investigated in the temperature-range 4.2–10 K, with special emphasis on the second virial coefficient in both the classical and quantum regimes. The main input in computing the quantum coefficient is the ‘effective’ phase shifts. These are calculated within the framework of the Galitskii–Migdal–Feynman (GMF) formalism, using the HFDHE2 and Sposito potentials. The virial equation of state is constructed. Extensive calculations are carried out for the pressure–volume–temperature (P–V–T) behavior, as well as chemical potential, and nonideality of the system. The following results are obtained. First, the validity of the GMF formalism for the present system is demonstrated beyond any doubt. Second, the boiling point (phase-transition point) of $^{4}$ He gas is determined from the P–V behavior using the virial equation of state, its value being closest than all previous results to the experimental value. Third, the chemical potential $\upmu $ is evaluated from the quantum second virial coefficient. It is found that $\upmu $ increases (becomes less negative) as the temperature decreases or the number density n increases. Further, $\upmu $ shows no sensitivity to the differences between the potentials used up to n = 10 $^{27}$ m $^{-3}$ . Finally, the compressibility Z is computed and discussed as a measure of the nonideality of the system.     

Characterisation of a TES-Based X-ray Microcalorimeter in the Energy Range from 150 to 1800 eV Using an Adiabatic Demagnetisation Refrigerator

We characterised a TES-based X-ray microcalorimeter in an adiabatic demagnetisation refrigerator (ADR) using synchrotron radiation. The detector response and energy resolution was measured at the beam-line in the PTB radiometry laboratory at the electron storage ring BESSY II in the range from 200 to 1800 eV. We present and discuss the results of the energy resolution measurements as a function of energy, beam intensity and detector working point. The measured energy resolution ranges between 1.5 to 2.1 eV in the investigated energy range and is weakly dependent on the detector set point. A first analysis shows a count-rate capability, without considerable loss of performance, of about 500 counts per second.      

Stability of Tungsten�CRhenium Thermocouples in the Range from 0?��C to 1500?��C

The effect of exposure up to 1500 °C on emf values of type C (95 % tungsten 5 % rhenium vs. 74 % tungsten 26 % rhenium) thermocouples were evaluated. Three thermocouples consisting of thermocouple wires of 0.5 mm diameter, twin-bore beryllia tubes, and tantalum sheaths were prepared. After three type C thermocouples were calibrated in the range from 0 °C to 1550 °C, which confirmed insignificant difference among them, the drifts of two among them were measured at the palladium?Ccarbon (Pd?CC) eutectic point (1492 °C). They indicated a similar tendency, where the emf of thermocouples increased rapidly within the first 30 h, and after that, decreased gradually. To investigate the mechanism of the drift, the inhomogeneities of thermocouples were examined at 160 °C using a water heat-pipe furnace during the drift measurements at the Pd?CC eutectic point. It was found that the increase of emf within the first 30 h exposure at around 1500 °C was caused by the emf change due to inhomogeneity above 700 °C, and after that, the decrease of emf was caused by that around 1400 °C.     

Determination of the Thermal Diffusivity of Electrically Non-Conductive Solids in the Temperature Range from 80 K to 300 K by Laser-Flash Measurement

The adoption of the popular laser-flash method at temperatures far below 300 K is restricted by the weak signal-to-noise ratio and the limited spectral bandwidth of the commonly used mercury cadmium tellurite (MCT) infrared (IR) detector used as a non-contacting temperature probe. In this work, a different approach to measure the temperature rise in pulse heating experiments is described and evaluated. This method utilizes the change of the temperature-dependent electrical resistance of a thin strip of sputtered gold for the detection of a temperature rise as it was proposed by Kogure et al. The main advantage of this method at lower temperatures is the significantly higher signal-to-noise ratio compared to the commonly used IR detectors. A newly developed laser-flash apparatus using this detection method for the determination of the thermal diffusivity in the temperature range from 80 K to 300 K is presented. To test the accuracy of the new detection method, the thermal diffusivity of a borosilicate crown glass (BK7) specimen at 300 K was determined and compared to results derived with a MCT detector. Good agreement of the derived thermal diffusivity values within 3 % was found. The thermal diffusivity of BK7 and polycrystalline aluminum nitride (AlN) was measured at temperatures between 80 K and 300 K by a laser-flash method to test the functionality of the apparatus. Finally, the thermal conductivity was calculated using values for the specific heat capacity determined by temperature modulated differential scanning calorimetry (MDSC). Comparisons with literature data confirm the reliability of the experimental setup.     

Photoacoustic Spectroscopic Study of Optical Properties of $$\hbox {Cu}_{2}\hbox {GeTe}_{3}$$ in Temperature Range from 80 K to 300 K

We used photoacoustic spectroscopy to investigate the optical properties of \(\hbox {Cu}_{2}\hbox {GeTe}_{3}\). The temperature dependence of the bandgap energy was evaluated from optical absorption spectra obtained in the photon energy range of 0.76 eV to 0.81 eV between 80 K and 300 K. We used the empirical and semi-empirical models of Varshni, Viña, and Pässler to describe the observed bandgap shrinkage in this compound. The Debye temperature and effective phonon temperature of the compound were estimated to be approximately 227.4 K and 151.6 K, respectively. Thus, the temperature dependence of the bandgap is mediated by acoustic phonons.     

Measurement of Out-of-Plane Thermal Conductivity of Epitaxial $$\hbox {YBa}_{2}\hbox {Cu}_{3}\hbox {O}_{7-{\delta }}$$ Thin Films in the Temperature Range from 10 K to 300 K by Photothermal Reflectance

We measured the out-of-plane (c-axis) thermal conductivity of epitaxially grown \(\hbox {YBa}_{2}\hbox {Cu}_{3}\hbox {O}_{7-{\delta }}\) (YBCO) thin films (250 nm, 500 nm and 1000 nm) in the temperature range from 10 K to 300 K using the photothermal reflectance technique. The technique enables us to determine the thermal conductivity perpendicular to a thin film on a substrate by curve fitting analysis of the phase lag between the thermoreflectance signal and modulated heating laser beam in the frequency range from \(10^{2}\,\hbox {Hz}\) to \(10^{6}\,\hbox {Hz}\). The uncertainties of measured thermal conductivity of all samples were estimated to be within \({\pm }9\,\%\) at 300 K, \({\pm }12\,\%\) at 180 K, \({\pm }16\,\%\) at 90 K and \({\pm }20\,\%\) below 50 K. The experimental results show that the thermal conductivity is dependent on the thickness of the thin films across the entire temperature range. We also observed that the thermal conductivity of the present YBCO thin films showed \(T^{1.4}\) to \(T^{1.6}\) glass-like dependence below 50 K, even though the films are crystalline solids. In order to explain the reason for this temperature dependence, we attempted to analyze our results using phonon relaxation times for possible phonon scattering models, including stacking faults, grain boundary and tunneling states scattering models.