TÜBİTAK UME continues to prepare the laboratory infrastructure for the changes in the definitions of kilogram, ampere, kelvin and mole units, which are expected to enter into force as of 2019.
According to the proposal adopted by the 25th General Conference on Weights and Measures (CGPM) in November 2014, the definitions of 4 of the 7 SI units will be changed and the units kilogram, ampere, kelvin and mole will be redefined in terms of the universal constants Planck's constant, elementary charge constant, Boltzmann's constant and Avogadro's constant respectively.
It is expected to be approved at the 26th CGPM meeting in November 2018 and will enter into force on May 20, 2019. Since the quantities on which the new definitions are based have been chosen in such a way that they will not be affected by possible advances in the technologies used to realize the units, it is planned that no new adjustments to the SI unit system will be needed in the future. Therefore, with this latest revision, all SI basic units will be able to be realized independent of time, location and person due to the stable nature of universal constants.
KILOGRAM
Since 1889, the definition of the kilogram, the unit of mass, has been based on a tangible measure, the International Prototype Kilogram (IPK). The reference standard is the kilogram unit, made of % 90 Platinum and % 10 Iridium alloy, 39 mm high and 39 mm in diameter, cylindrical in shape, kept in three glass cases at the International Bureau of Weights and Measures (BIPM), and whose access is controlled by the strict supervision of the Committee on Weights and Measures (CIPM) "Equals the mass of the IPK" is defined as ". This definition assumes that there is no change in the mass of the IPK. While this assumption is not testable, traceability for the kilogram unit can only be ensured by BIPM.
New definition of the kilogram unit Planck's constant numerical value h = 6,626 070 015 x 10-34 kg m2 s-1 is taken. In this definition, the meter is defined as the speed of light in vacuum (c) and the second is defined as the transition frequency (∆ν_Cs) between the fine structure levels of the Cesium-133 atom. Therefore, the new definition of the kilogram is associated with meters and seconds. With the new definition, the traceability of the kilogram unit, whose value is determined by a universal constant, will no longer have to be granted by BIPM.
Traceability will be available from all national metrology laboratories with a method (Kibble Balance or XRCD) that can perform the kilogram unit at primary level. By monitoring the IPK mass, it will be possible to observe how it has changed over the years and make retrospective inferences. At TÜBİTAK UME, work on the realization of the kilogram unit has been ongoing since 2014. The current uncertainty value, which was also published in the journal "Metrologia", is 6 ppm. TÜBİTAK UME aims to reach an uncertainty level of 0.1 ppm by the end of 2019.
AMPER
Unit of electric current. Since 1948, the definition adopted at the 9th CGPM Conference has been used. Ampere is defined as an infinitely long, circular cross-sectional area of negligible circular cross-sectional area, two flat conductor wires parallel to each other under vacuum at a distance of 1 m and 2 x 10–7 It is defined as a constant current that creates a force of magnitude N/m.
Since force is used in its current definition, it is not possible to obtain the unit of ampere without defining it in kilograms, meters and seconds. Definition of ampere vacuum magnetic permeability μ_0 = 4π x 10-7 H-m-1 is fixed as The new definition of the ampere unit is the numerical value of the elementary load e = 1,602 176 634 x 10–19 It is made on the basis of A s.
In this definition, the second SI unit is defined as the transition frequency (∆ν_Cs) between the fine structure levels of the cesium-133 atom. A single electron pump can be used to realize this definition. According to the new definition, the unit of amperes will no longer be associated with kilograms and meters, and the unit will no longer be related to the fundamental constant in physics (e) will be connected.
KELVIN
Since 1967/68, the thermodynamic temperature unit Kelvin is defined as 1/273.16 of the triple point temperature at which water is in thermal equilibrium in solid, liquid and gaseous states at the same time.
The new definition of the Kelvin unit is the numerical value of the Boltzman constant k = 1,380 649 x 10 -23 kg m2 s-1 K-1 is taken. In this definition, the kilogram Planck's constant (h), meter is the speed of light in vacuum (c) and the second is defined by the transition frequency (∆ν_Cs) between the fine structure levels of the Cesium-133 atom. With this change, Kelvin is associated with the definitions of kilogram, meter and second. Dielectric Constant Gas Thermometer, Acoustic Gas Thermometer, Johnson Noise Thermometer and Doppler Broadening Thermometer can be used to realize the Kelvin unit. TÜBİTAK UME will carry out thermodynamic temperature measurements by installing the Acoustic Gas Thermometer system, which it continues to work on within the scope of the investment project currently in force.
MOL
12 grams since 1971 12A system containing as many elementary particles (atoms, molecules, ions, electrons, or other particles) as there are atoms in C is defined as 1 mole.
New definition of the mole unit, numerical value of Avagadro's constant NA = 6,022 140 76 x 1023 mole-1 is taken into account. Systems containing Avogadro number of particles are defined as one mole.
In the realization of the mole unit 28Pure silicon spheres made from the Si isotope are used. With this definition 12The existing relationship between the mass of atom C, kilograms and moles would lose its validity.
What Happens If We Can't Keep Up With Change?
TÜBİTAK UME aims to contribute much more to increasing our country's export capability and competitiveness based on R&D and innovation in areas such as defense, space, environment, energy, automotive, health and food in areas such as defense, space, environment, energy, automotive, health and food, and to make progress in these areas in line with the geopolitical position and requirements of our country by developing its research infrastructure, especially by redefining, creating and ensuring the continuity of the kilogram, ampere, kelvin and mole units in the International System of Units (SI), which shape the future of metrology in line with the 2023 targets of our country.
With the aim of becoming one of the top 8 metrology institutes in the world, it has started new investment activities, especially the establishment of quantum metrology laboratories. With the traceability provided by TÜBİTAK UME, the number of certificates issued by accredited laboratories in the country has reached 4 million annually. However, if TÜBİTAK UME does not have the new definitions of kilogram, kelvin, ampere and mole units, the traceability of 1.7 million certificates will inevitably be dependent on foreign countries.
