Nuclear reactions of 19,20C on a liquid hydrogen target measured with the superconducting TOF spectrometer

T. Yamaguchi, K. Tanaka, T. Suzuki, A. Ozawa, T. Ohtsubo, T. Aiba, N. Aoi, H. Baba, M. Fukuda, Y. Hashizume, K. Inafuku, N. Iwasa, T. Izumikawa, K. Kobayashi, M. Komuro, Y. Kondo, T. Kubo, M. Kurokawa, T. Matsuyama, S. MichimasaT. Motobayashi, T. Nakabayashi, S. Nakajima, T. Nakamura, H. Sakurai, R. Shinoda, M. Shinohara, H. Suzuki, M. Takechi, E. Takeshita, S. Takeuchi, Y. Togano, K. Yamada, T. Yasuno, M. Yoshitake

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4 Citations (Scopus)

Abstract

Reaction cross sections with various kinds of breakup channels for neutron-rich carbon isotopes 18-20C and for 9Be impinging on a liquid hydrogen target were investigated at 40 MeV/nucleon. The nuclides of interest were produced via projectile fragmentation from a 63 MeV/nucleon 40Ar beam and were separated in flight at the RIKEN projectile fragment separator (RIPS). The combination of the large-acceptance superconducting TOF spectrometer, TOMBEE (TOF Mass analyzer for exotic BEam Experiment), with a liquid hydrogen target, CRYPTA (CRYogenic ProTon and Alpha target system), enables simultaneous measurements of several reaction channels: the reaction cross sections (σR), individual elemental fragmentation cross sections (σΔZ), charge-changing cross sections (σcc), neutron-removal cross sections (σΔxn), and charge-pickup cross sections (σΔZ+1) for 19,20C; σΔZ, σΔxn, and σΔZ+1 for 18C; and σR for 9Be. The present σR of 9Be on proton, σR=397±23 mb, measured in the inverse kinematics, was consistent with the previous measurements using proton beams at different laboratories. The σR of 19C and 20C on proton were determined to be σR=754±22 mb and σR=791±34 mb, respectively. Taking into account the beam energy and target dependence of σR, the present σR are found to be considerably enhanced compared with those measured at around 1 GeV/nucleon. The σΔZ+1 appears to increase with the mass number of the projectiles, and it significantly contributes to σR in the present energy range. The finite-range optical-limit and few-body Glauber model analyses were performed for σR to study the nuclear matter density distributions and to derive the relative strength of the s-wave components of the valence neutrons in 19C and 20C. A neutron halo structure of 19C is confirmed with an s-wave dominance of the valence neutron when the effect of the charge-pickup reaction is taken into account. The large σΔn of 19C and σΔ2n of 20C also support the decoupled structures of 18C+n and 18C+2n, respectively. The σcc of 19C and 20C agree with each other within their experimental uncertainties, which might indicate a similar proton density distribution in 19C and 20C. The σΔZ decreases monotonically without the even-odd effect as the number of removed protons increases.

Original languageEnglish
Pages (from-to)1-37
Number of pages37
JournalNuclear Physics A
Volume864
Issue number1
DOIs
Publication statusPublished - 2011 Aug 1

Keywords

  • Calculated
  • Liquid hydrogen target and secondary radioactive beams
  • Measured
  • Nuclear reactions
  • Transmission method with TOMBEE spectrometer and CRYPTA target

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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