Chronology of Milestone Events in Particle Physics - ALSTON 1961B
Chronology of Milestone Events in Particle Physics

  Nobel prize to L. W. Alvarez awarded in 1968 "for his decisive contribution to elementary particle physics, in particular the discovery of a large number of resonance states, made possible through his development of the hydrogen bubble chamber technique and data analysis''  


Alston, M.H.; Alvarez, L.W.; Eberhard, P.H.; Good, M.L.; Graziano, W.; Ticho, H.K.; Wojcicki, S.G.;
Resonance in the K- System
Phys. Rev. Lett. 6 (1961) 300;

Reprinted in
M. L. Good at the meeting of the American Physical Society, Chicago, November, 1960, Bull. Am. Phys. Soc. 5, 414 (1960).
R. N. Cahn and G. Goldhaber, The Experimental Foundations of Particle Physics, Cambridge Univ. Press (1991) 127.

Reactions of the form K p o p were studied in a 15 in. hydrogen bubble chamber exposed to a 1.15 BeV/c K beam. 48 events were observed giving a total cross section of 2.0 0.3 mb. The kinetic energies of protons resulting from the interactions show a strong peaking around a value of 20 MeV and this is interpreted as arising from a final-state K p resonance or K* particle: K p K*- p. The mean value of the total resonance energy (or mass) of the state is 885 3 MeV. After subtraction of estimated background, 22 events lie in the region of the peak and the full width of the peak at half-height is found to be 16 MeV, corresponding to a lifetime of 4 x 10-23 sec. The angular distribution of the decay of the K* is consistent with a spin J = 0 or J = 1 but not J > 2. A preliminary investigation of additional data from the reactions K p K o p and K p K + n also indicates resonances and a crude estimate of the branching ratio R = (K*- K o)/(K*- o ) is given as 0.75 0.35. This agrees with a ratio of 0.5 which should occur if the K* has isotopic spin I = 1 / 2. (Science Abstracts, 1961, 8502. J. D. Dowell).

Accelerator LBL Detectors HBC-15IN

Related references
More (earlier) information appears in
M. H. Alston et al., Phys. Rev. Lett. 5 (1960) 520;
M. L. Good, Bull.Am.Phys.Soc. 5 (1960) 414;
See also
J. Tiomno, A. L. L. Videira, and N. Zagury, Phys. Rev. Lett. 6 (1961) 120;
M. Gell-Mann, in Proc. of the 1960 Ann. Int. Conf. on High-Energy Physics at Rochester, Interscience Publishers, New York (1960) 508;
R. Spitzer and H. P. Stapp, Phys. Rev. 109 (1958) 540;

  K p p o 1.15 GeV (Plab) cs, mass
  K p p K o 1.15 GeV (Plab) mass
  K p n K + 1.15 GeV (Plab) mass
  K p p K*(892) 1.15 GeV (Plab)
  K p n *(892)o 1.15 GeV (Plab)
  K*(892) o

Particles studied
  K*(892) ex, mass, qn
  K*(892)o ex, mass, qn

Record comments
First evidence for the K*(892) resonance.
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