Evidence of Quarks in Air-Shower Cores

Abstract

It is well known that a considerable number of experiments using high-energy accelerators or low-energy cosmic radiation have failed to find the quark. 1 However, much higher energies occur in cosmic-ray air showers. Moreover, several groups have reported the occurrence of very large transverse momenta in interactions in these showers. 2 " 5 These momenta imply the operation of a very strong force and this might be the quark-quark interaction. Accordingly, we have looked for quarks in air-shower cores using a delayed-expansion Wilson cloud chamber. 6,7 In one year from July 1968 we found four tracks whose appearance was that expected for a quark of charge fe. 8 Several alternative explanations could be ruled out. For instance, the appearance of the tracks could not be due to a statistical fluctuation in the number of ions produced because the numbers involved were much too large. They could not be due to the Chudakoff effect because the track length at half-minimum ionization was greater than 10 cm in all cases and greater than 20 cm in one case. They could not be due to poor illumination because adjacent tracks were well illuminated. Another possible explanation of a track having half the normal specific ionization is that it is due to a particle that traversed the cloud chamber before the clearing field was removed. It would then be possible for ions of one sign to drift out of the illuminated re-(U.S.) . 29, 1 (1942).

An Estimate of the Flux of Free Quarks in High Energy Cosmic Radiation

“…These showers were mostly due to primary cosmic ray particles of energy between 10 15 and 10 17 eV. In 1969 we found a track in event 66240 with all the expected characteristics of a quark track and no contra-indications (McCusker and Cairns 1969). This event led to other searches in air shower cores and it also led to some criticisms and suggestions for other explanations of the event.…”

Search for quarks in cosmic rays with the Leeds cloud chamber

“…The search for quarks of charge 2 e as a nearly time-coincident component of cosmic-ray air showers was originated by McCusker et al and continued by others. Improved techniques have permitted the extension of the search to quarks of charge e [1 ]. We here report an extension of the search for -~ e quarks by using the Leeds cloud chamber [2] and an appraisal of the results in terms of an upper limit to the production cross section.…”

Is the Lightest Fractionally-Charged Particle Stable?

“…(Gvr "+GAr "rs)qp +sinsq/rsCGvr"+GAr"rs)qp. (2) In this expression we have defined the phases of qP and qJ. such that the coefficients cos s and sin s are real.…”