H. Fuchi

Cross-sections for Neutrino Production of Charmed Particles

Abstract We have found 122 charmed-particle decays among 3855 neutrino interactions located in the fiducial volume of a hybrid emulsion spectrometer installed in the Fermilab wide-band neutrino beam. We obtain an average relative charmed-particle production cross section of σ(ν μ → c μ − ) σ(ν μ →μ − ) =4.9 −0.6 +0.7 % , at an average neutrino energy of 22 GeV. We also obtain a production rate of σ(ν μ → c c ν μ ) σ(ν μ →ν μ ) =0.13 −0.11 +0.31 % , if we assume that there was an undetected muon, a limit of σ(ν μ → c c μ − ) σ(ν μ → c μ − ) CL ) can be obtained. Other cross section ratios and limits are also presented.

Measurement of the D+, F+, and Lambda(c)+ Charmed Particle Lifetimes

From the analysis of 685 neutrino and antineutrino interactions in an emulsion target, fifteen candidates for the multiprong decay of charged charmed particles are found. This Letter presents liketimes for the D/sup + -/, F/sup + -/, and ..lambda../sub c//sup +/ states based on the fitted events of the sample.

EXPERIMENTAL DETAILS ON LIFETIME MEASUREMENTS OF NEUTRINO PRODUCED CHARMED PARTICLES IN A TAGGED EMULSION SPECTROMETER

Abstract A new type of hybrid appaatus, which consisted of an emulsion target and a magnet spectrometer, was successfully used in an experiment to measure lifetimes of charmed particles produced by the wide-band neutrino beam from 350 GeV protons at Fermilab. The emulsion target was essential to find short distance decay vertices andthe counter spectrometer was used both to localize the neutrino events in the emulsion and also to identify the particles from weak decays and those produced in the neutrino interactions. Newly introduced emulsion techniques such as the changeable sheet as a low background interface to couple the emulsion target with the counter spectrometer, and the single track followback method to locate interaction and decay vertices in the emulsion, were proved to be very powerful. Details of the experimental apparatus and of the method of analysis employed are described.

Charmed hadron production by neutrinos

Abstract Charmed hadron production has been studied using a hybrid emulsion spectrometer in the Fermilab wide-band neutrino beam. The relative rates of D0, D+, F+, and Λ+c production have been measured - the fraction of D mesons is 69 ± 8 10 % . Momentum, transverse momentum, Feynman X, and fragmentation (Z) distributions are presented. The mean Z for charmed hadrons is 0.59 ± 0.03 (±0.03). Charmed target fragments have been observed.

Production characteristics of charmed particles in neutrino interactions

Abstract Using a hybrid emulsion spectrometer installed in the Fermilab wide-band neutrino beam, we located a total of 3855 neutrino interactions in the fiducial volume of our target. For 122 charmed-particle decays found in these interactions, we present distributions of x , y , charm-muon angular projection, Feynman- X , and the fragmentation Z . We find that the number of strange quarks in the nucleon sea is 4.2±2.1±2.6% of the number of down quarks.

Cross sections for charm production by neutrinos

The production of charmed particles has been measured using a hybrid emulsion spectrometer in the Fermilab wide-band neutrino beam. The relative cross section for charged current charmed particle production is σ(v → μ−c)/σ(v → μ−) = 6.5 ±1.91.8%, and the energy dependence of the cross section is presented. One event with charm pair production was observed. A limit of σ(v → μcc)/σ(v → μc) < 6% (90% CL) is found for the ratio of charged current pair and single charm production.

Direct observation of charmed-particle pairs produced in 340 GeV/c negative-pion interactions in an emulsion chamber

(1) E . H . S . ]~URHOP, D. H . DAVIS, D. N. TOVEE, D. PETERSEN, ~k. L. ]:~EAD, G. COREMANS=BERTRA~TI), J. SACTON, P, VILAIN, t. BRESLIN, A. ~IONTWILL, i~. ~. ~OBERTS, D. A. GARBUTT, F. ~:~. STANNARD, G. BLAES, R . KLEIN, F . M. SCt~I~IITT, G. BARONI, F . CERADINI, M. CONVERSI, L. FEDERICI, M. L. FERRER, S. (]ENTILE, S. DI LIBERTO, S. PETRERA, G. ROMANO, I~. SANTONICO, G. BASSOMPIERRE, M. JUNG, N. KURTZ, ~[. PATY a n d M. SCHNEEGANS: Phys. Zett. B, 65, 299 (1976); D. ALLASIA, (J. ANGELINI, P . ]3AGNAIA, G. BARONI, J . H . BARTLEY, G. BERTRAND-CoREMANS, V. BISI, ~k. BRESLIN, E. H . S. BURttOP, F. CARENA, R . CASALI, G. CIAPETTI, ~/n CONVERSI, D. I t . DAVIS, S. DI LIEERTO, t~. FANTECRI, ]~[. b . FERRER, C. FRANZINETTI, D. GAM:BA, L. GODlVRE~ r, D. KEANE, E. LAMANNA, A. MARZARI, F . ]~[ARZANO, t . MONT~VILL, A. NAPPI, C. PALAZZI-CERR1NA, ~ . PAZZI, S. PETRERA, G. 51. PIERAZZINI, G. I~OMANO, A. ROMERO, S. SACTON, R. SANTONICO, R. SEVEE, F. I(. STANNARD, P~ TOLUN, D. N. TOVEE, P . VILAIN, J . H . ~VICKENS a n d G. ~r Phys. JSett. B, 87, 287 (1979); N. USHIDA, T. KONDO, G. FUJIOKA, H . FUKUSHI1VIA, Y. TAKAttASHI, S. TATSITMI, C. YOKOYAMA, Y. HOMMA, Y. TSUZUKI, S. BAHK, C. ElM, J . PARK, J . SONG, D. BAILEY, S. CONETTI, J . FISCHER, J . TRISCHUK, H . FUGHI, K . HOSHINO, M. MI~CANISttI, ] ( . NIU, K . NIWA, H . SHIBUYA, Y. YANAGISA~VA, S. ERREDE, M. GUTZWILLER, S. KURAMATA, N. ~vV. REAY, K . I~EIREL, T. A. ]~O~r l~. SIDWELL, N. T. STANTON, K . MORIYAMA, H . SHIBATA, W. HARA, 0 . KUSUMOTO, Y. NOGUCHI, M. TEEANAKA, ]~. OKABE, J . YOKOTA, J . HARNOIS, N. ]=IERBERT, J . HEBERT, S. LOKANATHAN, B. MOLEOD, S. TASAKA, P. DAVIS, J . MARTIN, D. PITMAN, J . D. PRENTICE, P . SINERVO, T. S. YOON, I t . KIMURA a n d Y. MAEDA : Phys. Rev. Left., 45, 1049, 1053 (1980). The other experiments of charmed particles exposed to hadron

Direct observation of a pair decay of neutral charmed particles produced in 400 GeVc proton interaction

Abstract The second evidence of a pair decay of charmed particles has been obtained in an emulsion chamber exposed to 400 GeV c protons. The life time and production cross section of the charmed particles have been evaluated as several times 10 −13 s and several tens of microbarns.

Technical aspects -- design, scanning and energy measurement in small emulsion chambers

Technical aspects of small emulsion chamber are discussed. Emulsion chamber is a detector which consists of nuclear emulsion plates and other light or heavy material plates. While a pure emulsion stack is likened to a micro bubble chamber, it could be compared to a complex counter detector assembly with super high spatial resolving power. It is possible to measure particle momenta by relative scattering method and trace back γ ray cascades to vertices a few centimeters away. Charged secondary tracks could be examined for sudden changes in direction several centimeters from production vertices. ’’Invention’’ of the emulsion chamber enabled one to extend the power of pure emulsions to study very high energy interactions to tens of TeV, and it opend a new windnow for search of short‐lived particles.

Measurement of D+, F+, and c+ charmed-particle lifetimes

From the analysis of 685 neutrino and antineutrino interactions in an emulsion target, fifteen candidates for the multiprong decay of charged charmed particles are found. This Letter presents liketimes for the D/sup + -/, F/sup + -/, and ..lambda../sub c//sup +/ states based on the fitted events of the sample.