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T. Kawabata

Publications and source records attributed to T. Kawabata.

75 records · Page 5Linked to original sources

n-p Short-Range Correlations from (p,2p + n) Measurements

Recently, a new technique for measuring short-range NN correlations in nuclei (NN SRCs) was reported by the E850 collaboration, using data from the EVA spectrometer at the AGS at Brookhaven Nat. Lab. In this talk, we will report on a larger set of data from new measurement by the collaboration, utilizing the same technique. This technique is based on a very simple kinematic approach. For quasi-elastic knockout of protons from a nucleus ($^{12}$C(p,2p) was used for the current work), we can reconstruct the momentum {\bf p$_f$} of the struck proton in the nucleus before the reaction, from the three momenta of the two detected protons, {\bf p$_1$} and {\bf p$_2$} and the three momentum of the incident proton, {\bf p$_0$} : {\bf p$_f$} = {\bf p$_1$} + {\bf p$_2$} - {\bf p$_0$} If there are significant n-p SRCs, then we would expect to find a neutron with momentum -{\bf p$_f$} in coincidence with the two protons, provided {\bf p$_f$} is larger than the Fermi momentum $k_F$ for the nucleus (${\sim}$220 MeV/c for $^{12}$C). Our results reported here confirm the earlier results from the E850 collaboration.

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Gamow-Teller Strengths of the Inverse-Beta Transition 176Yb --> 176Lu for Spectroscopy of Proton-Proton and other sub-MeV Solar Neutrinos

Discrete Gamow-Teller (GT) transitions, 176Yb-->176Lu at low excitation energies have been measured via the (3He,t) reaction at 450 MeV and at 0 degrees. For 176Yb, two low-lying states are observed, setting low thresholds Q(neutrino)=301 and 445 keV for neutrino capture. Capture rates estimated from the measured GT strengths, the simple two-state excitation structure, and the low Q(neutrino) in Yb--Lu indicate that Yb-based neutrino-detectors are well suited for a direct measurement of the complete sub-MeV solar electron-neutrino spectrum (including pp neutrinos) where definitive effects of flavor conversion are expected.

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Backward emitted high-energy neutrons in hard reactions of p and pi^+ on carbon

Beams of protons and pions of 5.9 GeV/c were incident on a C target. Neutrons emitted into the back hemisphere, in the laboratory system, were detected in (triple) coincidence with two emerging $p_t>$0.6 GeV/c particles. We present the momentum spectra of the backward going neutrons, which have the same universal shape observed in earlier (inclusive) reactions induced by hadrons, $γ$, $ν$, and $\barν$ beams. We also integrated the spectra and determined the fraction of the hard scattering events which are in coincidence with at least one neutron emitted into the back hemisphere, with momenta above 0.32 GeV/c. Contrary to the earlier measurements which found that only a small fraction (of the order of 10%) of the total inelastic cross section for light nuclei was associated with backward going nucleons, we find that about half of the events are of this nature. We speculate that the reason for the large difference is the strong total center of mass (s) dependence of the hard reaction and short range nucleon correlations in nuclei.

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