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Title: A Proposal to Search for Charmed Particles Originating from the Interactions of 400 GeV/c Protons in Emulsion Nuclei

Abstract

There has been much recent discussion of the possibility of the existence of 'charmed' particles, hadrons which possess non-zero values of 'charm', a further additive quantum number. These particles may be generated either in the three triplet model of Han and Nambu or by the postulate of a fourth, charm-bearing quark. On the assumption that charm, like strangeness, is conserved in strong and electromagnetic interactions (the opposite assumption would necessitate charmed particles coupling strongly to ordinary hadrons and the existence of yet undiscovered states, e.g. Z*s) but not conserved in weak interactions one might expect their production either singly in neutrino interactions or in pairs in associated production in high energy hadron collisions, to be followed by their subsequent, relatively slow, decay into 'uncharmed' particles. Various estimates as to mass, lifetime, production cross-sections and decay modes have been made for these particles. However their failure to appear as di-lepton events among the neutrino interactions of the Brookhaven A.G.S. and CERN P.S. experiments might suggest that their masses are in excess of 2 GeV/c{sup 2} the other hand, such particles would have been expected to have been observed directly in bubble chamber studies at FNAL had their lifetimes been greater thanmore » 10{sup -11}s as suggested by some authors. This proposal, which may be thought of as complementary to that of Burhop et al, is for a straightforward exposure of a stack of emulsions to a 400 GeV/c proton beam to look for evidence of the pair production of charmed particles. The spatial resolution of the emulsion technique is about one micron with the consequence that the decays of particles of mean lives in the range 10{sup -11} to 10{sup -14} s should be readily observable.« less

Authors:
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
910471
Report Number(s):
FERMILAB-PROPOSAL-0364
TRN: US200724%%180
DOE Contract Number:
AC02-07CH11359
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; BUBBLE CHAMBERS; CROSS SECTIONS; ELECTROMAGNETIC INTERACTIONS; NUCLEI; PAIR PRODUCTION; PRODUCTION; PROTON BEAMS; PROTONS; QUANTUM NUMBERS; SPATIAL RESOLUTION; WEAK INTERACTIONS; HADRONS

Citation Formats

Sacton, J. A Proposal to Search for Charmed Particles Originating from the Interactions of 400 GeV/c Protons in Emulsion Nuclei. United States: N. p., 1974. Web. doi:10.2172/910471.
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Sacton, J. A Proposal to Search for Charmed Particles Originating from the Interactions of 400 GeV/c Protons in Emulsion Nuclei. United States. doi:10.2172/910471.
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Sacton, J. Fri . "A Proposal to Search for Charmed Particles Originating from the Interactions of 400 GeV/c Protons in Emulsion Nuclei". United States. doi:10.2172/910471. https://www.osti.gov/servlets/purl/910471.
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@article{osti_910471,
title = {A Proposal to Search for Charmed Particles Originating from the Interactions of 400 GeV/c Protons in Emulsion Nuclei},
author = {Sacton, J.},
abstractNote = {There has been much recent discussion of the possibility of the existence of 'charmed' particles, hadrons which possess non-zero values of 'charm', a further additive quantum number. These particles may be generated either in the three triplet model of Han and Nambu or by the postulate of a fourth, charm-bearing quark. On the assumption that charm, like strangeness, is conserved in strong and electromagnetic interactions (the opposite assumption would necessitate charmed particles coupling strongly to ordinary hadrons and the existence of yet undiscovered states, e.g. Z*s) but not conserved in weak interactions one might expect their production either singly in neutrino interactions or in pairs in associated production in high energy hadron collisions, to be followed by their subsequent, relatively slow, decay into 'uncharmed' particles. Various estimates as to mass, lifetime, production cross-sections and decay modes have been made for these particles. However their failure to appear as di-lepton events among the neutrino interactions of the Brookhaven A.G.S. and CERN P.S. experiments might suggest that their masses are in excess of 2 GeV/c{sup 2} the other hand, such particles would have been expected to have been observed directly in bubble chamber studies at FNAL had their lifetimes been greater than 10{sup -11}s as suggested by some authors. This proposal, which may be thought of as complementary to that of Burhop et al, is for a straightforward exposure of a stack of emulsions to a 400 GeV/c proton beam to look for evidence of the pair production of charmed particles. The spatial resolution of the emulsion technique is about one micron with the consequence that the decays of particles of mean lives in the range 10{sup -11} to 10{sup -14} s should be readily observable.},
doi = {10.2172/910471},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Nov 01 00:00:00 EST 1974},
month = {Fri Nov 01 00:00:00 EST 1974}
}
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DOI:  10.2172/910471
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  • ; ; ; ...
    A stack of nuclear emulsions was irradiated by 400 Gev/c protons at FNAL. In this work a search for the short-lived particles has been carried out by a new method that allowed to detect secondary events (including the narrow ones) on short distances from the parent star. By measuring angles, momenta and ionizations of the secondary particles they could identify electrons and distinguish them from hadrons. In search for the decays of charged of particles on n{sub s} {ge} 3 charged relativistic particles or of neutral ones on two or four charged particles the environments of the 1120 stars hasmore » been looked through up to 1 mm from the center of parent star inside of cone 0{sub L} {le} 4{sup o}. By this method 21 secondary events of the type O + O + n{sub s} have been selected. After excluding background due to the nuclear and electro-magnetic interactions 9 events remained (from which 4 of the type O + O + 2n, 2 of the type O + O + 3p and 4 of the type O + O + 4n). They consider them as decays of the new short-lived particles. All these 9 events are characterized by jet like structure (O{sub L} {le} 10{sup -2} rad). At least in one of these events there is an electron, that is the particle suffered a semileptonic decay. Estimation of the masses of the decaying particles in most cases agree with the mass of the charmed barions. Mean life time estimated on the basis of 9 events is about 2,0.10{sup -14} sec. The rate of the production of the new short-lived particles is the following: neutral particles 6.10{sup -3} per star and charged ones -2.10{sup -3} per star in pA-interactions at 400 Gev/c. The total cross section for production of these particles is {approx} 100 {micro} bn. Detection of the charmed particles produced in association with the found ones needs further investigation.« less

  • - Sov. J. Nucl. Phys. (Engl. Transl.); (United States)
    The principal characteristics of multiplicity distributions and correlations are presented and discussed for various types of secondary charged particles from inelastic interactions of 400-GeV protons with the nuclei of nuclear emulsions, and also their energy dependence in the energy region up to 400 GeV.

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  • One-hundred-thirty-three interactions initiated in nuclear emulsions by 26.7 Bev/c protons are studied. The events are subject to separation into two groups, one in which most of the shower particles are emitied in a single nucleon- nucleon coliision in the target nucleus, the other in which multiple collisions produce the particles. Experimental procedure, classification of events, identification of tracks, and various distributions are discussed. Graphs of distributions are included. (27 references.) (D.C.W.)