National Metrology Laboratory Research Articles

Determination of intrinsic energy dependence of point-like inorganic scintillation detector in brachytherapy.

Inorganic scintillation detectors (ISDs) are promising for in vivo dosimetry in brachytherapy (BT). ISDs have fast response, providing time resolved dose rate information, and high sensitivity, attributed to high atomic numbers. However, the conversion of the detector signal to absorbed dose-to-water is highly dependent on the energy spectrum of the incident radiation. This dependence is comprised of absorbed dose energy dependence, obtainable with Monte Carlo (MC) simulation, and the absorbed dose-to-signal conversion efficiency or intrinsic energy dependence requiring measurements. Studies have indicated negligible intrinsic energy dependence of ZnSe:O-based ISDs in Ir-192 BT. A full characterization has not been performed earlier. This study characterizes the intrinsic energy dependence of ZnSe:O-based ISDs for kV X-ray radiation qualities, with energies relevant for BT. Three point-like ISDs made from fiber-coupled cuboid ZnSe:O-based scintillators were calibrated at the Swedish National Metrology Laboratory for ionizing radiation. The calibration was done in terms of air kerma free-in-air, Kair , in 13 X-ray radiation qualities, Q, from 25 to 300 kVp (CCRI 25-250kV and ISO 4037 N-series), and in terms of absorbed dose to water, Dw , in a Co-60 beam, Q0 . The mean absorbed dose to the ISDs, relative to Kair and Dw , were obtained with the MC code TOPAS (Geant4) using X-ray spectra obtained with SpekPy software and laboratory filtration data and a generic Co-60 source. The intrinsic energy dependence was determined as a function of effective photon energy, , (relative to Co-60). The angular dependence of the ISD signal was measured in a 25 kVp (0.20mm Al HVL) and 135 kVp beam (0.48mm Cu HVL), by rotating the ISDs 180° around the fiber's longitudinal axis (perpendicular to the beam). A full 360° was not performed due to setup limitations. The impact of detector design was quantified with MC simulation. Above 30keV the intrinsic energy dependence varied with less than 5±4% from unity for all detectors (with the uncertainty expressed as the mean of all expanded measurement uncertainties for individual above 30keV, k=2). Below 30keV, it decreased with up to 17% and inter-detector variations of 13% were observed, likely due to differences in detector geometry not captured by the simulations using nominal geometry. In the 25 kVp radiation quality, the ISD signal varied with 24% over a ∼45° rotation. For 135 kVp, the corresponding variation was below 3%. Assuming a 0.05mm thicker layer of reflective paint around the sensitive volume changed the absorbed dose with 6.3% at the lowest , and with less than 2% at higher energies. The study suggests that the ISDs have an intrinsic energy dependence relative to Co-60 lower than 5±4% in radiation qualities with >30keV. Therefore, they could in principle be calibrated in a Co-60 beam quality and transferred to such radiation qualities with correction factors determined only by the absorbed dose energy dependence obtained from MC simulations. This encourages exploration of the ISDs' applications in intensity modulated BT with Yb-169 or other novel intermediate energy isotopes.

Proposed synergies between oceanography and metrology

Accurate and traceable measurements are required to understand ocean processes, to address pressing societal challenges, such as climate change and to sustainably manage marine resources. Although scientific and engineering research has resulted in advanced methods to measure Essential Ocean Variables (EOVs) there is a need for cross comparison of the techniques and traceability to recognized standards. Metrological laboratories are experienced in accredited methods and assessment of methodology. An EU INFRAIA-02-2020: Integrating Activities for Starting Communities project MINKE (Metrology for Integrated marine maNagement and Knowledge-transfer nEtwork https://minke.eu) brings European marine science and metrology Research Infrastructures together to identify synergies and create an innovative approach to Quality Assurance of oceanographic data. Quality depends both on the accuracy (that can be provided through the metrology component) and the completeness of the data sets. The collaboration between different Marine Research Infrastructures (RIs) places a fundamental role on assuring the completeness of the datasets, particularly at global scales. The MINKE project encourages enhancement through collaboration of national metrology laboratories and the oceanographic community. Metrological assessment of the accuracy and uncertainties within multidisciplinary ocean observations will provide data that are key to delivering policy information. Objectives across all the RIs are to facilitate ocean observation and build wider synergies. MINKE will investigate these synergies, then introduce metrology to the core of various EOV measurements. Currently the marine RIs cover laboratory and field operations, from the surface seafloor, coastal waters to deep sea, fixed ocean stations to ship and autonomous vehicle operations to ships of opportunity, and flux stations focusing on carbonate system variables. The nexus of these operations is the focal point for coordinated improvement of ocean observing methods. Measurement intercomparisons, traceability and uncertainty assessments should be at the core of the scientific observations. Specifically, MINKE will work with RIs and Metrology Institutes to improve the quality of dissolved oxygen, carbonate system, chlorophyll-fluorescence, ocean sound and current meter measurements, through access to metrology laboratories, Transnational Access and intercomparison studies across existing marine consortia and RIs. MINKE will also promote the development of absolute salinity observation, and improvements in marine litter measurements.

A novel traceability route to the SI in roughness measurements at IPQ

A new traceability methodology for roughness stylus calibration is being developed in the National Metrology Laboratory of the Portuguese Institute for Quality (IPQ) using a high-precision displacement transducer. The calibration and dissemination of roughness standards measurements is one of the activities of IPQ. A stylus instrument is used to acquire the height values of the scanned points on the surface of the roughness standard. Defined according to ISO standards, namely the ISO 21920-2:2021, the integrated software calculates the roughness parameters that quantify the surface. A set of roughness parameters, measured after stylus calibration with different standards artefacts, as defined in ISO 5436-1:2000 has been evaluated. The need for the development of a new route for the metrological traceability in roughness, with faster calibration and better accuracy was also analyzed. The use of a displacement transducer, as reference, was the studied solution.

Developments of interlaboratory comparisons on pressure measurements in the Philippines

The National Metrology Laboratory of the Philippines, Industrial Technology Development Institute under the Department of Science and Technology (ITDI-DOST) offered first of its kind interlaboratory comparison in pressure measurement in the country following a demand survey identifying the gaps in proving the competency of local calibration laboratories. This paper presents the development in implementing the two interlaboratory comparisons in the Philippines with six years interval using the same pressure artefact. With its many objectives, the program also aimed to provide these laboratories access to proficiency testing (PT) to comply with the ISO/IEC 17025 requirements. Comparatively, while both are considered successfully implemented, the improved awareness and commitment to quality of the participants and the enhanced competency of the pilot laboratory in implementing such activity are a few of the enumerated factors instigating the increase in the number of participants as well as those obtaining satisfactory results in the latter PT. The interlaboratory comparison schemes offered aimed at sustaining the demands of metrology stakeholders and continuously develop this service to support further progress in the calibration and measurement capabilities of local laboratories in the country.

Fast neutron response characterization of an EJ-276 plastic scintillator for use as a neutron monitor

EJ-276 is a recent development in plastic scintillators that comes with improved pulse shape discrimination over its predecessor EJ-299-33. In this work, the neutron response functions, proton light output function, and detection efficiency of EJ-276 were measured using mono-energetic neutron reference fields at the national metrology laboratory, Physikalisch-Technische Bundesanstalt, in the neutron energy range 1.5–19 MeV. In particular, the proton light output in the range 14–19 MeV is presented for the first time. The optimization of Pulse Shape Discrimination has also been investigated using an 241Am-Be source and results are presented. Finally, we study how, using a shadow-cone method and time of flight method, we can discriminate scattered and other spurious neutrons from the mono-energetic beam. The characterized EJ-276 detector is to be used in the monitor of the neutron fields and gamma background at the new Neutron Irradiation Laboratory for Electronics facility at the Rutherford Appleton Laboratory.

Statistics in Metrology: International Key Comparisons and Interlaboratory Studies

Stochastic modeling and analysis of international key compar isons (interlaboratory comparisons) pose several fundamental questions for statistical methodology. A key comparison (KC) is specifically designed to derive the key comparison reference value and to assess conformance of cal ibrations by participating national metrology laboratories at a few, “key”, settings for a particular measurement process. An approach to the statis tical study of key comparisons data is proposed using a model taken from meta-analysis. This model leads to a class of weighted means estimators for the consensus value and to a method of assessing the uncertainty of the resulting estimates.

Demonstration of a trapped-ion atomic clock in space

Atomic clocks, which lock the frequency of an oscillator to the extremely stable quantized energy levels of atoms, are essential for navigation applications such as deep space exploration1 and global navigation satellite systems2, and are useful toolswith which to address questions in fundamental physics3-6. Such satellite systems use precise measurement of signal propagation times determined by atomic clocks, together with propagation speed, to calculate position. Although space atomic clocks with low instability are an enabling technology for global navigation, they have not yet been applied to deep space navigation and have seen only limited application to space-based fundamental physics, owing to performance constraints imposed by the rigours of space operation7. Methods of electromagnetically trapping and cooling ions have revolutionized atomic clock performance8-13. Terrestrial trapped-ion clocks operating in the optical domain have achieved orders-of-magnitude improvements in performance over their predecessors and have become a key component in national metrology laboratory research programmes13, but transporting this new technology into space has remained challenging. Here we show the results from a trapped-ion atomic clock operating in space. On the ground, NASA's Deep Space Atomic Clock demonstrated a short-term fractional frequency stability of 1.5×10-13/τ1/2 (where τ is the averaging time)14. Launched in 2019, the clock has operated for more than 12months in space and demonstrated there a long-term stability of 3×10-15 at 23days (no drift removal), and an estimated drift of 3.0(0.7)×10-16 per day. Each of these exceeds current space clock performance by up to an order of magnitude15-17. The Deep Space Atomic Clock is particularly amenable to the space environment because of its low sensitivity to variations in radiation, temperature and magnetic fields. This level of space clock performance will enable one-way navigation in which signal delay times are measured in situ, making near-real-time navigation of deep space probes possible18.

Hydrostatic Determination of Test Weight Density and Uncertainty Evaluation by Monte Carlo Method

This paper presents the characterization of the hydrostatic weighing facility of the National Metrology Laboratory (NML) of the Philippines. The study aimed to evaluate its suitability for determination of solid density. It was used to hydrostatically measure the density of a stainless steel (OIML Class F1) test weight weighing 200 g. The measurement result obtained was 7.5827 g cm-3 ± 0.0041 g cm-3 at an approximately 95 % level of confidence. The uncertainty evaluated by the Law of Propagation of Uncertainty (LPU) according to JCGM 100:2008 (GUM) was verified by the Monte Carlo method (MCM), which gave a result of 0.0040 g cm-3. The value determined for the solid density of the sample with its associated expanded uncertainty was found to be within the tolerance interval between 7.39 g cm-3 and 8.73 g cm-3 as required in OIML R111-1 for Class F1 test weights.

Bilateral comparison of 10 V standards between the NSAI-NML (Ireland) and the BIPM

Main textAs part of the ongoing BIPM key comparison BIPM.EM-K11, a comparison of the 10 V voltage reference standards of the BIPM and the National Standards Authority of Ireland - National Metrology Laboratory (NSAI - NML), Dublin, Ireland, was carried out in November and December 2020. The objective for NSAI-NML in participating in this comparison was to demonstrate the international equivalence of its DC voltage measurement results and to support their calibration and measurement capabilities (CMCs) published in the Key Comparison Database of the BIPM (KCDB).Two BIPM Zener diode-based travelling standards (Fluke 732B), BIPM_8 (Z8) and BIPM_9 (Z9), were transported by freight to NSAI-NML. At NSAI-NML, the reference standard for DC voltage at the 10 V level consists of a group of characterized Zener diode-based electronic voltage standards. The output EMF (Electromotive Force) of each travelling standard was measured by direct comparison with the group standard.At the BIPM the travelling standards were calibrated, before and after the measurements at NSAI-NML, with the Josephson Voltage Standard, developed at the BIPM. The output EMF of each travelling standard was measured against the Josephson Voltage Standard (JVS). Results of all measurements were corrected for the dependence of the output voltages of the Zener standards on internal temperature and ambient atmospheric pressure.The comparison result is presented as the difference between the value assigned to a 10 V standard by NSAI-NML, at NSAI-NML, U NSAI-NML, and that assigned by the BIPM, at the BIPM, U BIPM, on the reference date of 2020/11/14, as U NSAI-NML - U BIPM = -2.99 µV; u c = 1.71 µVwhere u c is the combined standard uncertainty associated with the measured difference, including the uncertainty of the realization of the volt at NSAI-NML, and the uncertainty related to the comparison.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The documentary standards of the IEEE technical committee 10

Global trade relies on the ability to reproducibly and accurately communicate the performance of products and to support these attestations. This standardization is essential for accurate, reproducible, reliable, and communicable characterization of the performance of these devices, to support technology and product advancement, product comparison and performance tracking, and device calibration and traceability. Standard terms and definitions, reproducible test methods, and accurate computational procedures are necessary for this communication and facilitate economic growth and technology evolution through the common understanding of technology. The IEEE Technical Committee 10 (TC-10), the Waveform Generation, Measurement, and Analysis Committee of the IEEE Instrumentation and Measurement Society (IMS), fulfills the global need for standardized terms and test and computational methods for describing and/or measuring the parameters that describe the performance of signal generators and waveform recorders and analyzers. The TC-10 has developed and maintains the following documentary standards: IEEE Std 181-2011, “Standard on Transitions, Pulses, and Related Waveforms” [1]; IEEE Std 1057-2017, “Standard for Digitizing Waveform Recorders” [2]; IEEE Std 1241-2010, “Standard for Terminology and Test Methods for Analog-to-Digital Converters” [3]; IEEE Std 1658-2011, “Standard for Terminology and Test Methods for Digital-to-Analog Converters” [4]; and the IEEE Std 1696-2013, “Standard for Terminology and Test Methods for Circuit Probes” [5]. In development is the IEEE Draft Std P2414 “Draft Standard for Jitter and Phase Noise.” The TC-10 comprises an international group of electronics engineers, mathematicians, professors and physicists with representatives from national metrology laboratories, national science laboratories, component manufacturers, the test instrumentation industry, academia, and end users. The status of the TC-10 standards is described herein.

Investigation of a synthetic diamond detector response in kilovoltage photon beams.

An important characteristic of radiation dosimetry detectors is their energy response which consists of absorbed-dose and intrinsic energy responses. The former can be characterized using Monte Carlo (MC) simulations, whereas the latter (i.e., detector signal per absorbed dose to detector) is extracted from experimental data. Such a characterization is especially relevant when detectors are used in nonrelative measurements at a beam quality that differs from the calibration beam quality. Having in mind the possible application of synthetic diamond detectors (microDiamond PTW 60019, Freiburg, Germany) for nonrelative dosimetry of low-energy brachytherapy (BT) beams, we determined their intrinsic and absorbed-dose energy responses in 25-250kV beams relative to a 60 Co beam, which is usually the reference beam quality for detector calibration in radiotherapy. Three microDiamond detectors and, for comparison, two silicon diodes (PTW 60017) were calibrated in terms of air-kerma free in air in six x-ray beam qualities (from 25 to 250kV) and in terms of absorbed dose to water in a 60 Co beam at the national metrology laboratory in Sweden. The PENELOPE/penEasy MC radiation transport code was used to calculate the absorbed-dose energy response of the detectors (modeled based on blueprints) relative to air and water depending on calibration conditions. The MC results were used to extract the relative intrinsic energy response of the detectors from the overall energy response. Measurements using an independent setup with a single ophthalmic BEBIG I25.S16 125 I BT seed (effective photon energy of 28keV) were used as a qualitative check of the extracted intrinsic energy response correction factors. Additionally, the impact of the thickness of the active volume as well as the presence of extra-cameral components on the absorbed-dose energy response of a microDiamond detector was studied using MC simulations. The relative intrinsic energy response of the microDiamond detectors was higher by a factor of 2 in 25 and 50kV beams compared to the 60 Co beam. The variation in the relative intrinsic energy response of silicon diodes was within 10% over the investigated photon energy range. The use of relative intrinsic energy response correction factors improved the agreement among the absorbed dose to water values determined using microDiamond detectors and silicon diodes, as well as with the TG-43 formalism-based calculations for the 125 I seed. MC study of microDiamond detector design features provided a possible explanation for inter-detector response variation at low-energy photon beams by differences in the effective thickness of the active volume. MicroDiamond detectors had a non-negligible variation in the relative intrinsic energy response (factor of 2) which was comparable to that in the absorbed-dose energy response relative to water at low-energy photon beams. Silicon diodes, in contrast, had an absorbed-dose energy dependence on photon energy that varied by a factor of 6, whereas the intrinsic energy dependence on beam quality was within 10%. It is important to decouple these two responses for a full characterization of detector energy response especially when the user and reference beam qualities differ significantly, and MC alone is not enough.

Final report on supplementary comparison APMP.M.P-S9 in gas gauge pressure from 2 MPa to 20 MPa

This report describes the results of a supplementary comparison of gas pressure standards at three National Metrology Institutes - National Institute of Metrology (Thailand) (NIMT), Physikalisch-Technische Bundesanstalt (PTB) and National Metrology Laboratory of the Philippines (NMLPHIL) - carried out within the framework of Asia-Pacific Metrology Programme (APMP) in order to determine their degrees of equivalence at pressures in the range from 2 MPa to 20 MPa for gauge mode. The pilot institute was NIMT. The measurements were carried out from February 2016 to July 2016. All participating institutes used pressure balances as their pressure standards. A reference pressure monitor was used as a transfer standard. Characteristics of the transfer standard were evaluated at the pilot institute and then used for uncertainty estimations. After completing the comparison measurements, the transfer standard showed a less stable behaviour than expected, resulting in a significant contribution to the uncertainties of the results. The degrees of equivalence that were evaluated in terms of differences of the participant's results and the comparison reference values divided by their expanded uncertainties (k=2) are all within the unity. This demonstrates equivalence of the compared standards on the uncertainty level, which is unfortunately dominated by the uncertainty of the transfer standard.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Bilateral comparison of 10 V standards between the NSAI - NML (Ireland) and the BIPM (BIPM.EM-K11.b)

As part of the ongoing BIPM key comparison BIPM.EM-K11.b, a comparison of the 10 V voltage reference standards of the BIPM and the National Standards Authority of Ireland - National Metrology Laboratory (NSAI - NML), Dublin, Ireland, was carried out in May and June 2018. Two BIPM Zener diode-based travelling standards (Fluke 732B), BIPM_E (ZE) and BIPM_F (ZF), were transported by freight to NSAI-NML. At NSAI-NML, the reference standard for DC voltage at the 10 V level consists of a group of characterized Zener diode-based electronic voltage standards. The output EMF (Electromotive Force) of each travelling standard was measured by direct comparison with the group standard.At the BIPM the travelling standards were calibrated, before and after the measurements at NSAI-NML, with the Josephson Voltage Standard. Results of all measurements were corrected for the dependence of the output voltages of the Zener standards on internal temperature and ambient atmospheric pressure.The final result of the comparison is presented as the difference between the value assigned to DC voltage standard by NSAI-NML, at the level of 10 V, at NSAI-NML, U NML, and that assigned by the BIPM, at the BIPM, U BIPM, at the reference dates of 20 May 2018. U NML - U BIPM = - 1.21 μV, u c = 1.38 μV, at 10 Vwhere u c is the combined standard uncertainty associated with the measured difference, including the uncertainty of the representation of the volt at the BIPM, at NSAI-NML, and the uncertainty related to the comparison.The comparison result is within the claimed uncertainties despite the fact that one of the NSAI NML results (for standard ZF) differed from the BIPM value by -1.66 μV.The voltage standards maintained by NSAI-NML and the BIPM were equivalent, within their stated standard uncertainties, on the mean date of the comparison.KEY WORDS FOR SEARCHDC voltage, electronics secondary voltage standard, voltage referenceMain textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Contributions of National Standards on the growth of Barometric Pressure and Vacuum Industries

A rigorous data analysis has been carried out for various barometric pressure transmitters and sensors and vacuum gauges over a period of 8 years; it has been found that a small fraction of pressure and vacuum industries and research institutions from private and government organizations approach to National Metrology Laboratory (NMI), CSIR-NPL, for calibration of their equipment. The observation also pointed out that it might be possible that the traceability chain throughout the country is not properly maintained, especially keeping in view that India is one of the fastest economies in the world.

Pilot study on calibration of micropipettes using the photometric method

Micropipettes, or piston-pipettes, are used in analytical laboratories for medical applications when it is necessary to deliver liquid in the range of the microliter. In order to determine the exact delivered volume of each micropipette it is necessary to calibrate them using the appropriate methods described in ISO 8655[1]. One of the methods is the photometric method which uses a high-resolution photometer and colorimetric solutions to determine the volume delivered by a micropipette. Considering that there is still some lack of knowledge about the performance of this method by the National Metrology Laboratories, it was organized, by IPQ and Artel, a pilot study to verify the applicability of this method in each laboratory.

Metrological characterisation of the 5 kN·m torque standard machine of LNE

After the development of the new 5 kN·m torque standard machine, LNE realized its metrological characterisation. This paper describes the determination of the uncertainties of this torque standard machine, including the uncertainty due to the mobility and the sensitivity of the arm lever. It describes also the comparison carried out with the national metrology laboratory of Germany PTB. The results show that the estimated uncertainties are satisfactory because divided by a factor of at least four compared to the old standard machines.

Geodesy and metrology with a transportable optical clock

The advent of novel measurement instrumentation can lead to paradigm shifts in scientific research. Optical atomic clocks, due to their unprecedented stability and uncertainty, are already being used to test physical theories and herald a revision of the International System of units (SI). However, to unlock their potential for cross-disciplinary applications such as relativistic geodesy, a major challenge remains. This is their transformation from highly specialized instruments restricted to national metrology laboratories into flexible devices deployable in different locations. Here we report the first field measurement campaign performed with a ubiquitously applicable $^{87}$Sr optical lattice clock. We use it to determine the gravity potential difference between the middle of a mountain and a location 90 km apart, exploiting both local and remote clock comparisons to eliminate potential clock errors. A local comparison with a $^{171}$Yb lattice clock also serves as an important check on the international consistency of independently developed optical clocks. This campaign demonstrates the exciting prospects for transportable optical clocks.

A compact design of multi-feeder data logging system for power quality measurement with a multiplexer and a single PQ transducer

This paper presents a simple and costs effective equipment design multi-feeder data logger for recording and monitoring power quality. The system design uses remote supervising and multi-feeder data logging system (RESMOS). The data collected through resmos portable unit (RMPU) will automatically be saved with the format as binary and comma separated value (CSV). The time setting on the RMPU can be configured with minimum one minute per logging. This data logger uses a single transducer with a multiplexer for recording and monitoring ten channels of power quality at busbar. The system design has been validated with national metrology laboratory scientific and industrial research institute of Malaysia (SIRIM). This tool has the advantage that it can be used to measure harmonic data more than 21st at the same time for ten channels and equipped with software making it easier for analysis data with low operational costs versus another power quality equipment. The experimental results indicate that the proposed technique can accelerate data reading with conversion rate one sample per second for each channel. The device can be used to measure harmonic level and power quality with a confidence level above 95% and percentage error under 2.43% for total harmonics distortion (THD) and 1.72% for voltage harmonics.

Aspectos metrológicos na estimativa da atividade administrada em pacientes de medicina nuclear

In order to investigate the performance quality of routine measurements of Nuclear Medicine Services (NMS), the National Metrology Laboratory of Ionizing Radiation/Institute of Radiation Protection and Dosimetry (LNMRI/IRD) has been conducting, since 1998, a program of comparison for activity measurements of radiopharmaceuticals administered to patients in nuclear medicine. Correction factors are determined from the result of performance analysis in order to determine with better accuracy the activity to be administered to the patients.

Final report on APMP supplementary comparison of industrial platinum resistance thermometer for range -50 °C to 400 °C. (APMP.T-S6)

The National Metrology Laboratory, Malaysia (NML-SIRIM) had coordinated the Supplementary Comparison of Industrial Platinum Resistance Thermometer (IPRT) started from July 2009 until April 2011 together with the National Measurement Institute of Australia (NMIA) and Korea Research Institute of Standards and Science (KRISS). This comparison was opened to all APMP members and 16 participants had taken part in order to consolidate or improve their calibration and measurement capabilities (CMCs). Three units of artefacts 100-ohm IPRT belonging to NML-SIRIM, NMIA and KRISS were used and three loops of measurement were run in parallel to shorten the circulation time. The stability of artefacts was monitored with initial and final ice point measurement by each laboratory. The participants need to perform measurement at temperature points (0,-50,-30, 0, 100, 200, 300, 400,0) °C. All submitted data were compiled and adjusted at nominal temperature and by using the linkage from NMIA and KRISS as reference value for all three loops , the temperature deviation from participants from different loops can be compared. The approach of Birge Ratio for final exclusion comprised all the excluded results from the analysis of each loop and the measurement performance for each participant were summarized by the En number value.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).