Time dilation of moving particles
Time dilation of moving particles as predicted by special relativity can be measured in particle lifetime experiments. According to special relativity, a clock C traveling between two synchronized clocks A and B stationed in a laboratory, is retarded with respect to the laboratory clocks. Since any periodic process can be considered a clock, also the lifetimes of unstable particles such as muons must be affected, so that moving muons should have a longer lifetime than resting ones. Variations of experiments that actually confirmed this effect took place in the atmosphere or in particle accelerators. Other time dilation experiments belong to the group of Ives–Stilwell experiments. See also Tests of special relativity.
Contents |
[edit] Rossi–Hall experiment
Performed in 1940 at Echo Lake and Denver in Colorado, the Rossi–Hall experiment, named after Bruno Rossi and D. B. Hall, measured the relativistic decay of muons (which they thought were mesons). They only measured muons in the atmosphere traveling at 99,94% of the speed of light. If no time dilation exists, then those muons should decay in the upper regions of the atmosphere, however, as a consequence of time dilation, they are present in considerable amount also at much lower heights. A value for the muon lifetime was given as t0 = 2.3±0.2 µs, which was later refined in 1943 by Rossi and Nereson to t0 = 2.15±0.07 µs, which was still in excellent agreement with special relativity and even modern measurements (2.197034(21) µs).[1] [2] [3] [4]
A more precise repetition of the experiment was made by Frisch and Smith (1963), who also measured the lifetimes of muons.[5]
[edit] Laboratory tests
Such tests were made by many experimentalists in particle accelerators using different types of particles - also resulting in the confirmation of time dilation. By comparing the lifetimes of positive and negative particles, some of those experiments confirmed CPT symmetry as well.
| Pion | Kaon | Muon |
|---|---|---|
| Durbin et al. (1952)[6]
Eckhause et al. (1965)[7] Nordberg et al. (1967)[8] Greenburg et al. (1969)[9] Ayres et. al (1971)[10] |
Burrowes et al. (1959)[11]
Nordin (1961)[12] Boyarski et al. (1962)[13] Lobkowicz et al. (1969)[14] Ott et al. (1971)[15] Skjeggestad et al. (1971)[16] Geweniger et al. (1974)[17] Carithers et al. (1975)[18] |
Lundy (1962)[19]
Meyer et al. (1963)[20] Eckhause et al. (1963)[21] Balandin et al. (1974)[22] |
Bailey et al. (1977),[23] who measured the lifetime of positive and negative muons in the CERN Muon storage ring, measured time dilation sending muons around a loop. Therefore, this experiment also confirms the twin paradox, i.e. the hypothesis that clocks sent away and then coming back to their initial position, are retarded with respect to a resting clock. The so-called clock hypothesis of relativity, according to which the extent of acceleration doesn't influence the value of time dilation, was also confirmed in this experiment, as well as in the one of Roos et al. (1980).[25]
Today, time dilation of particles is routinely confirmed in particle accelerators, and its consideration is obligatory in the analysis of particle experiments at relativistic velocities.
[edit] References
- ^ Rossi, B.; Hall, D. B. (1941). "Variation of the Rate of Decay of Mesotrons with Momentum". Physical Review 59 (3): 223–228. Bibcode 1941PhRv...59..223R. doi:10.1103/PhysRev.59.223.
- ^ Rossi, B.; Greisen, K.; Stearns, J. C.; Froman, D. K.; Koontz, P. G. (1942). "Further Measurements of the Mesotron Lifetime". Physical Review 61 (11-12): 675–679. Bibcode 1942PhRv...61..675R. doi:10.1103/PhysRev.61.675.
- ^ Rossi, B.; Nereson, N. (1942). "Experimental Determination of the Disintegration Curve of Mesotrons". Physical Review 62 (9-10): 417–422. Bibcode 1942PhRv...62..417R. doi:10.1103/PhysRev.62.417.
- ^ Rossi, B.; Nereson, N. (1943). "Further Measurements on the Disintegration Curve of Mesotrons". Physical Review 64 (7-8): 199–201. Bibcode 1943PhRv...64..199N. doi:10.1103/PhysRev.64.199.
- ^ Frisch, D. H.; Smith, J. H. (1963). "Measurement of the Relativistic Time Dilation Using μ-Mesons". American Journal of Physics 31 (5): 342–355. Bibcode 1963AmJPh..31..342F. doi:10.1119/1.1969508.
- ^ Durbin, R. P.; Loar, H. H.; Havens, W. W. (1952). "The Lifetimes of the π+ and π-Mesons". Physical Review 88 (2): 179–183. Bibcode 1952PhRv...88..179D. doi:10.1103/PhysRev.88.179.
- ^ Eckhause, M.; Harris, R. J., Jr.; Shuler, W. B.; Siegel, R. T.; Welsh, R. E. (1967). "Remeasurement of the π+ lifetime". Physics Letters 19 (4): 348–350. Bibcode 1965PhL....19..348E. doi:10.1016/0031-9163(65)91016-4.
- ^ Nordberg, M. E.; Lobkowicz, F.; Burman, R. L. (1967). "Remeasurement of the π+ lifetime". Physics Letters B 24 (11): 594–596. Bibcode 1967PhLB...24..594N. doi:10.1016/0370-2693(67)90401-7.
- ^ Greenberg, A. J.; Ayres, D. S.; Cormack, A. M.; Kenney, R. W.; Caldwell, D. O.; Elings, V. B.; Hesse, W. P.; Morrison, R. J. (1969). "Charged-Pion Lifetime and a Limit on a Fundamental Length". Physical Review Letters 23 (21): 1267–1270. Bibcode 1969PhRvL..23.1267G. doi:10.1103/PhysRevLett.23.1267.
- ^ Ayres, D. S.; Cormack, A. M.; Greenberg, A. J.; Kenney, R. W.; Caldwell, D. O.; Elings, V. B.; Hesse, W. P.; Morrison, R. J. (1971). "Measurements of the Lifetimes of Positive and Negative Pions". Physical Review D 3 (5): 1051–1063. Bibcode 1971PhRvD...3.1051A. doi:10.1103/PhysRevD.3.1051.
- ^ Burrowes, H. C.; Caldwell, D. O.; Frisch, D. H.; Hill, D. A.; Ritson, D. M.; Schluter, R. A. (1959). "K-Meson-Nucleon Total Cross Sections from 0.6 to 2.0 Bev". Physical Review Letters 2 (3): 117–119. Bibcode 1959PhRvL...2..117B. doi:10.1103/PhysRevLett.2.117.
- ^ Nordin, Paul (1961). "S- and P-Wave Interactions of K- Mesons in Hydrogen". Physical Review 123 (6): 2168–2176. Bibcode 1961PhRv..123.2168N. doi:10.1103/PhysRev.123.2168.
- ^ Boyarski, A. M.; Loh, E. C.; Niemela, L. Q.; Ritson, D. M.; Weinstein, R.; Ozaki, S. (1962). "Study of the K+ Decay". Physical Review 128 (5): 2398–2402. Bibcode 1962PhRv..128.2398B. doi:10.1103/PhysRev.128.2398.
- ^ Lobkowicz, F.; Melissinos, A. C.; Nagashima, Y.; Tewksbury, S.; von Briesen, H.; Fox, J. D. (1969). "Precise Measurement of the K+K- Lifetime Ratio". Physical Review 185 (5): 1676–1686. Bibcode 1969PhRv..185.1676L. doi:10.1103/PhysRev.185.1676.
- ^ Ott, R. J.; Pritchard, T. W. (1971). "Precise Measurement of the K+ Lifetime". Physical Review D 3 (1): 52–56. Bibcode 1971PhRvD...3...52O. doi:10.1103/PhysRevD.3.52.
- ^ Skjeggestad, O.; James, F.; Montanet, L.; Paul, E.; Saetre, P.; Sendall, D. M.; Burgun, G.; Lesquoy, E.; Muller, A.; Pauli, E.; Zylberajch, S. (1972). "Measurement of the KSO mean life". Nuclear Physics B 48 (2): 343–352. Bibcode 1972NuPhB..48..343S. doi:10.1016/0550-3213(72)90174-5.
- ^ Geweniger, C.; Gjesdal, S.; Presser, G.; Steffen, P.; Steinberger, J.; Vannucci, F.; Wahl, H.; Eisele, F.; Filthuth, H.; Kleinknecht, K.; Lüth, V.; Zech, G. (1974). "A new determination of the Ko --> π+π- decay parameters". Physics Letters B 48 (5): 487–491. Bibcode 1974PhLB...48..487G. doi:10.1016/0370-2693(74)90385-2.
- ^ Carithers, W. C.; Modis, T.; Nygren, D. R.; Pun, T. P.; Schwartz, E. L.; Sticker, H.; Christenson, J. H. (1975). "Measurement of the Phase of the CP-Nonconservation Parameter η+- and the KS Total Decay Rate". Physical Review Letters 34 (19): 1244–1246. Bibcode 1975PhRvL..34.1244C. doi:10.1103/PhysRevLett.34.1244.
- ^ Lundy, R. A. (1962). "Precision Measurement of the μ+ Lifetime". Physical Review 125 (5): 1686–1696. Bibcode 1962PhRv..125.1686L. doi:10.1103/PhysRev.125.1686.
- ^ Meyer, S. L.; Anderson, E. W.; Bleser, E.; Lederman, I. M.; Rosen, J. L.; Rothberg, J.; Wang, I.-T. (1963). "Precision Lifetime Measurements on Positive and Negative Muons". Physical Review 132 (6): 2693–2698. Bibcode 1963PhRv..132.2693M. doi:10.1103/PhysRev.132.2693.
- ^ Eckhause, M.; Filippas, T. A.; Sutton, R. B.; Welsh, R. E. (1963). "Measurements of Negative-Muon Lifetimes in Light Isotopes". Physical Review 132 (1): 422–425. Bibcode 1963PhRv..132..422E. doi:10.1103/PhysRev.132.422.
- ^ Balandin, M. P.; Grebenyuk, V. M.; Zinov, V. G.; Konin, A. D.; Ponomarev, A. N. (1974). "Measurement of the lifetime of the positive muon". Soviet Physics JETP 40: 811. Bibcode 1974JETP...40..811B.
- ^ a b Bailey, H.; Borer, K.; Combley F.; Drumm H.; Krienen F.; Lange F.; Picasso E.; Ruden W. von; Farley F. J. M. ; Field J. H.; Flegel W. & Hattersley P. M. (1977). "Measurements of relativistic time dilatation for positive and negative muons in a circular orbit". Nature 268 (5618): 301–305. Bibcode 1977Natur.268..301B. doi:10.1038/268301a0.
- ^ Bailey, J.; Borer, K.; Combley, F.; Drumm, H.; Eck, C.; Farley, F. J. M.; Field, J. H.; Flegel, W.; Hattersley, P. M.; Krienen, F.; Lange, F.; Lebée, G.; McMillan, E.; Petrucci, G.; Picasso, E.; Rúnolfsson, O.; von Rüden, W.; Williams, R. W.; Wojcicki, S. (1979). "Final report on the CERN muon storage ring including the anomalous magnetic moment and the electric dipole moment of the muon, and a direct test of relativistic time dilation". Nuclear Physics B 150: 1–75. Bibcode 1979NuPhB.150....1B. doi:10.1016/0550-3213(79)90292-X.
- ^ Roos, C. E.; Marraffino, J.; Reucroft, S.; Waters, J.; Webster, M. S.; Williams, E. G. H. (1980). "σ+/- lifetimes and longitudinal acceleration". Nature 286 (5770): 244-245. Bibcode 1980Natur.286..244R. doi:10.1038/286244a0.
[edit] External links
- Roberts, T; Schleif, S; Dlugosz, JM (ed.) (2007). "What is the experimental basis of Special Relativity?". Usenet Physics FAQ. University of California, Riverside. http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html.
- Time Dilation - An Experiment With Mu-Mesons
- Bonizzoni, Ilaria; Giuliani, Giuseppe, The interpretations by experimenters of experiments on 'time dilation': 1940-1970 circa, arXiv:physics/0008012
|
|||||||||||||||||||||||
