The CCL-K11 ongoing key comparison Final report for the year 2011

Transcription

1 The CCL-K11 ongong key coparson Fnal report for the year 011 Mchael Matus BEV, Arltgasse 35, 1160 Wen, Austra M a del Mar Pérez CEM, Alfar, 8760 Tres Cantos, Madrd, Span Slobodan Zelenka DMDM, Mke Alasa 14, Belgrade, Serba Adar Dauletbayev, Chngs Kuanbayev RSE, KazInMetr, Orynbor str. 11, Astana, Kazakhstan Hate Hussen NIS, Tersa Street, El-Hara, P.O.Box 136, 111, Gza, Egypt Lennart Robertsson BIPM, Pavllon de Breteul, 931 Sèvres, France

2 Abstract Lasers fro four natonal etrologcal nsttutes (NMIs) were copared as part of the CCL- K11 ongong key coparson, ntated by the 13 th eetng of the Coté Consultatve des Longeurs (CCL) n 007. The absolute frequency of the f coponent of the R(17) 11-5 transton of olecular odne was easured for these lasers followng the techncal protocol for CCL-K11. The results of these easureents are copled n the present report. The coparson reports, as councated by each partcpant, are ncluded as appendces. Ths docuent consttutes the thrd fnal report for the ongong key coparson CCL-K11. Introducton The BIPM.L-K10 (K10) key coparson was ntated n 1993 to provde a bass for deonstratng equvalence of natonal realzatons of wavelength-standards used for the realzaton of the defnton of the etre accordng to the ethod (c) n what was called the Mse en Pratque (MeP, refers to the docuent Practcal realzaton of the defnton of the etre ). Such a coparson seeed of partcular portance snce the whole feld of densonal etrology had to be traceable to such realzatons of the etre. The K10 coparson took only the 633 n He-Ne standards nto consderaton. The easurand of the coparson was the dfference of the average frequency of the hyperfne coponents d, e, f, and g n the R(17) 11-5 lne as obtaned by atrx easureents. The frequency of the reference laser BIPM4 was used as the key coparson reference value, representng the value recoended n the MeP. The stuaton for realzaton of the SI-etre has changed due to the ntroducton of new technques for absolute frequency easureents. Ths has opened up the alternatve ethod (b) n the MeP to realze a frequency/wavelength standard traceable to the SI-second. The practcal consequences of ths developent are that at least two ethods are at the oent beng used to realze the etre, and that standards of dfferent wavelengths, portant for densonal etrology applcatons, can now deonstrate traceablty wth relatve ease. Consderng these crcustances the 11 th CCL eetng whch was held n October 003 at the BIPM decded to close the K10 coparson and ntate a new key coparson naed BIPM.L-K11. Frst easureents n BIPM.L-K11 were ade at the BIPM n May 004. Results fro BIPM.L-K10 and BIPM.L-K11 can be found at Subsequently, the CIPM has decded, that the cob-related work, whch used to provde external servces, should stop at the BIPM at the end of 006. Ths decson had drect plcatons on the actvty whch supported the BIPM.L-K11 that consequently were closed down at the end of year 006. A proposal for a new schee for the coparson, based on a group of node-laboratores n the dfferent RMOs and ploted by the Bundesat für Ech- und Veressungswesen (BEV, Austra) was therefore ade. Ths proposal, whch had been agreed on by the Presdent of the CCL, was gven support by the CIPM at ts 95 th eetng and was endorsed by the 13 th eetng of CCL n Septeber 007. The techncal protocol (avalable fro the BIPM web page) defnes the procedures to follow n ths new coparson, now transferred to the CCL, and naed CCL-K11. CCL-K11 page

3 Measureents and Evaluaton The easureents for the reported capagn took place at the node laboratory BEV. All partcpants took part wth odne stablzed HeNe-lasers at l 633 n workng on the f coponent of the 17 I R(17) 11-5 transton. Table 1 lsts the easureents n chronologcal order, specfyng the partcpants, the places and the dates. Table 1. Partcpants Country NMI Standard Contact person Node lab Date Egypt NIS NIS-134 Hate Hussen BEV Mar. 011 Serba DMDM DMDM-1 (forally LED-1) Slobodan Zelenka BEV Jun. 011 Span CEM CEM M a del Mar Pérez BEV Oct. 011 Kazakhstan RSE, KazInMetr KazInMetr Adar Dauletbayev, Chngs Kuanbayev BEV Nov. 011 All easureents reported here were perfored accordng to the so-called ethod 1 (Absolute frequency easureent traceable to the realsaton of the SI second), whch are easureents usng fetosecond frequency cobs. The fetosecond cob arrangeents n the node laboratores are outlned n the appendces of ths report. Intally to the actual easureents each partcpatng laboratory had to state: The expected frequency of the standard, f e. Ths should norally be the frequency used n ther calbraton servce. It s ether the recoended value or a value deterned by soe other eans. The standard uncertanty u e of the expected value. Ths should be a value copatble wth the uncertanty gven n the CMC for ths servce. The operatonal paraeters used to obtan the two values entoned above (f applcable). Senstvty coeffcents wth uncertantes for paraeters appearng n the uncertanty budget for the standard (f applcable). The stated frequency f e s the actual easurand n ths type of key coparson. It s copared on a per lab bass wth the easured frequency f possbly corrected to the reference operatonal paraeters as gven below. One has to note, that the coparson s blnd; the partcpant s not told the result of the easureent before statng hs value for f e. The standard uncertanty of the deterned frequency s coposed of two parts, one fro the frequency easureent, u 0, and one fro the uncertanty n the settngs of the workng (and other) paraeters, u p. The latter, the uncertantes related to the standard tself are to be estated by each operator n accordance wth ther qualty syste. The uncertanty steng CCL-K11 page 3

4 fro the easureents, u 0, s estated by the operator of the experent alone, or together wth personnel nvolved n the coparson, agan n accordance wth a qualty procedure. These uncertantes are reported n sectons D8 and D9 (of the Techncal Protocol) and should be gven as standard uncertantes followng GUM practce. The cobned uncertanty of u 0 and u p, u, reported n D10 should be gven as the root su squares of u 0 and u p. Denote the easured (uncorrected) frequency f 0 wth standard uncertanty u 0, and the easured frequency, corrected for nfluence of operatonal paraeters f wth standard uncertanty u. Then the followng holds: f f -d (1) = 0 The sybol d denotes the condensed nforaton about the nfluence of the actual workng paraeters and other quanttes on the laser frequency. A lnear odel s coonly used for ths: Â s Dx + Â d = d () Where the s denote the senstvty coeffcents and Dx the devatons of the respectve workng paraeters fro the nonal values (care ust be taken choosng the correct sgns for both quanttes). All other nfluence quanttes (e.g. electronc offsets, cavty algnents, etc.) are odelled wth the d. These have usually zero expectaton values but non-zero uncertantes. The uncertantes are thus derved n a straghtforward way as: and ( ( ) u s Dx ) + ( s u( Dx )) u( ) Â Â + Â up = d (3) p 0 u = u + u (4) Denote the expected frequency f e wth standard uncertanty u e, and the easured frequency, corrected for nfluence of operatonal paraeters f wth standard uncertanty u. For a partcular standard,, construct the densonless quanttes () ( ) - f( ) f () fe D f = (5) u r r () ( ) + u( ) f () ue = (6) It ust be noted that f e and f should be transferred to the sae (usually nonal) workng paraeters for the standard, whch would be expected to concde wth those for whch f e s vald f no other nstructons are gven by the partcpatng laboratory. CCL-K11 s not ndented to derve a better value for any of the frequences fro the lst of recoended radatons for the realsaton of the etre and other optcal frequency standards (forally known as MeP). Therefore t s not andatory that f e s a value out of ths lst, nor s t necessary to correct for the nonal workng paraeters. It s however necessary CCL-K11 page 4

5 for each partcpant to follow hs nternal workng procedures lke for any calbraton for the respectve CMC entry. Two of the partcpants (CEM and DMDM) use ther respectve standards n a turn-key ode,.e. they do not correct the laser frequency for operatonal paraeters. Consequently f 0 and f are equvalent n ths case. To test consstency between the easured values and the expected ones, hypothess testng at a confdence level of 95 % s to be perfored. The result wll serve as a bass for the revew of the CMC and ndcate the copatblty wth the claed capabltes. In ths fraework the degree of equvalence can be obtaned n the usual way. The consstency can thus be checked by the followng condton: -1 Dfr( ) E n = 1 wth Ur( ) ur( ) U () r = (7) As dscussed at the 14 th CCL eetng, June 009, t s not necessary nor useful to deterne a par-wse degree of equvalence. For all results reported the expanded uncertanty to a 95 % confdence level can be obtaned by ultplyng the standard uncertantes wth k =. Table gves the values used for the ost portant workng paraeters for each laser. Addtonal nforaton can be found n the appendces. Table. Workng paraeter values for the standards wth estated standard uncertantes n parenthess as gven n the easureent reports ncluded n the appendces. Note that soe of the devate fro the CIPM recoended values. Standard f n µw Modulaton wdth (peak to peak) n MHz I cold-fnger teperature n C Cell wall teperature n C NIS (3) 6.18 (0.10) 15.0 (0.1) ( ) DMDM-1 0 (3) 5.99 (0.10) 15.0 (0.1) ( ) CEM 67 (3) 5.77 (0.10) 15.0 (0.1) 5 (3) KazInMetr 69 (3) 6.9 (0.10) 14.8 (0.1) 5 (3) Results The stated frequences f e and the easured frequences f 0 and f are gven n table 3. The allocated standard uncertantes u e, u 0 and u, respectvely, are ncluded n parenthess. Two partcpants (DMDM and KazInMetr) estate f e and u e by usng the CIPM recoended values for the f coponent of the R(17) 11-5 transton. The reanng partcpants use other sources of knowledge to estate these values (ether cob calbratons n ther hoe laboratores or results fro forer coparsons). The data fro table 3 are used to calculate the fnal results accordng to equatons (5-7). The results are gven n table 4 and fgure 1, respectvely. CCL-K11 page 5

6 Table 3. Expected frequences f e, easured (uncorrected) frequences f 0, and easured frequences, corrected for nfluence of operatonal paraeters f together wth the respectve standard uncertantes of the standards. Standard All frequences gven are offset by MHz f e (u e ) / khz f 0 (u 0 ) / khz f (u ) / khz NIS (1.0) (0.) (1.8) DMDM (1) (1.9) (1.9) CEM (1.0) (0.1) (0.1) KazInMetr 604 (1) (0.1) (1.5) Table 4. Degree of equvalence for the standards. Standard Df r u r E n =Df r U r NIS DMDM CEM KazInMetr Fgure 1. Degree of equvalence for the standards. Error bars represent the expanded uncertantes U r () CCL-K11 page 6

7 Concluson Frequency easureents have been carred out on 4 natonal wavelength standards. A good agreeent between the stated and the easured frequency values was found. No correctve actons are necessary for any of the partcpants. Appendces Detals on the ndvdual standards can be found n the easureent reports collated n the appendces. These reports are electronc copes, the sgned orgnals are kept by the node laboratory. Mchael Matus, BEV (AT) Plot of CCL-K May 01 CCL-K11 page 7